Danger-associated molecular patterns (DAMPs) are released on the onset of tissue injury or death, which tend to trigger innate immunity and regulate various immune pathways. Among the various DAMP molecules, S100A8 and S100A9 belonging to Ca2+ binding proteins with EF-hands and Zn2+ ion binding sites have been implicated in aggravating the pathogenesis of rheumatoid arthritis (RA), upon interaction with pattern recognition receptors (PRR) such as TLR4, RAGE and CD36 receptors. Thus, the present study aims to assess the effect of Ca2+ or Zn2+ ions on the interaction of S100A8 and S100A9 proteins towards the PRRs. Protein-protein interaction analysis showed that the TLR4-S100A8Ca2+Zn2+, TLR4-S100A8 Zn2+, RAGE-S100A8/A8Zn2+, RAGE-S100A8/A8Ca2+, CD36-S100A8Ca2+, and CD36-S100A9/A9Ca2+ showed higher affinity against each other. The 100 ns molecular dynamics simulation showed that the TLR4-S100A8Ca2+, RAGE-S100A8/A8Ca2+ and CD36-S100A8Ca2+ complexes showed minimal fluctuations in their trajectory indicating that Ca2+ bound complexes were more stable than the other complexes. Furthermore, SPR analysis showed that S100A9 exhibited higher binding affinity towards PRRs in the presence of Ca2+ and Zn2+ ions. Considering the fact that physiological levels of both Ca2+ and Zn2+ ions play a critical role in the binding of S100A8 and S100A9 proteins against the PRRs, it can be emphasized that the S100A9 and RAGE receptors could be the critical players in the RA pathogenesis due to its impeccable binding towards the PRRs in the presence of both Ca2+ and Zn2+ ions. Nonetheless, further in vivo, and in vitro studies are imperative to validate these findings and identify potential targets for RA treatment.

Introduction: Recent studies have shown that Erythroid progenitor cells exhibit a distinct immunosuppressive and immunoregulatory phenotype associated with the response to bacteria. Methods: The objective of this study was to comprehensively explore the traits of human bone marrow Erythroid cells through protein-protein interaction network analysis using cytokine secretion analysis, and single-cell immunoproteomic analysis using flow cytometry, as well as the re-analysis of publicly available human and mouse bone marrow Erythroid-cell transcriptomic data. Results: Our protein-protein interaction network analysis of human bone marrow Erythroid-cell protein-coding genes identified enrichment in the immune response to lipopolysaccharide, with Calprotectin and Cathepsin G being the main factors. We then mapped the Calprotectin to the CD45+ Erythroid cells of both humans and mice via the analysis of the publicly available scRNA-seq data. Additionally, we observed that human bone marrow Erythroid cells secrete cytokines and chemokines, such as IL-1b, IL-8, and IL-18, which are also mainly involved in the immune response to lipopolysaccharide. We also found that human and mouse bone marrow Erythroid-cell conditional media inhibit bacterial growth in vitro. Discussion: These findings suggest that both human and mouse bone marrow CD45+ Erythroid cells possess the potential to combat pathogenic microbes and thus play a role in innate antimicrobial immunity. Conclusions: CD45+ Erythroid cells are a potent immunoregulatory cell population in both humans and mice.

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory disease of the bladder for which no effective therapy is currently available. Understanding the pathogenesis of IC/BPS and identifying effective intervention targets are of great clinical importance for its effective treatment. Our work focuses on elucidating the key targets and underlying mechanisms of IC/BPS.

We established an experimental autoimmune cystitis (EAC) mouse model and generated gene knockout mice to elucidate key mediators triggering chronic inflammatory damage in IC/BPS through using single-cell RNA sequencing, proteomic sequencing, and molecular biology experiments.

Our study revealed that the infiltration and activation of macrophages, T cells, and mast cells exacerbated inflammatory bladder damage in both IC/BPS and EAC mice. Notably, cell-cell communication among bladder immune cells was significantly enhanced in EAC mice. Macrophages, as the main cell types altered in EAC mice, received and transmitted the most intensity signalling. Mechanistically, macrophages synthesized and secreted S100A9, which in turn facilitated macrophage polarization and promoted the production of pro-inflammatory cytokines. S100A9 emerged as an important pro-inflammatory and pathogenic molecule in IC/BPS and EAC. Further analysis demonstrated that S100A9 activation enhanced the inflammatory response and exacerbated bladder tissue damage in IC/BPS patients and EAC mice via TLR4/NF-κB and TLR4/p38 signalling pathways. Importantly, inhibition of S100A9 with paquinimod, as well as genetic knockout of S100A9, significantly attenuated the pathological process.

S100A9 is an important pro-inflammatory and pathogenic molecule in IC/BPS and EAC. Targeting S100A9-initiated signalling pathways may offer a novel therapeutic strategy for IC/BPS.

Endometriosis is a chronic inflammatory condition characterised by pain and infertility. We conducted a prospective study to elucidate the pathophysiological mechanisms underlying endometriosis development.

We examined the association between 1305 proteins measured by SomaScan proteomics and risk of endometriosis diagnosis in prospectively collected plasma from 200 laparoscopically-confirmed endometriosis cases and 200 risk-set sampling matched controls within the Nurses' Health Study II (NHSII) cohort. Using conditional logistic regression, we calculated odds ratios (OR) and 95% confidence intervals (CI) per one standard deviation increase in protein levels and area under the curve (AUC) to assess the multi-protein model in discriminating cases from controls. Analytical validation for three proteins was performed using immunoassays. Ingenuity Pathway Analysis and STRING analyses identified biological pathways and protein interactions.

Blood samples from cases were collected up to 9 years before diagnosis (median = 4 years). Among 61 individual proteins nominally significantly associated with risk of endometriosis diagnosis compared to controls, endometriosis cases had higher plasma levels of S100A9 (OR = 1.52, 95%CI = 1.19-1.94), ICAM2 (OR = 1.47, 95%CI = 1.17-1.85), HIST1H3A (OR = 1.42, 95%CI = 1.31-1.78), TOP1 (OR = 1.95, 95%CI = 1.24-3.06), CD5L (OR = 1.23, 95%CI = 1.00-1.51) and lower levels of IGFBP1 (OR = 0.70, 95%CI = 0.52-0.94). We further evaluated three of the proteins in an independent set of 103 matched case-control pairs within the NHSII cohort. Pathway analyses revealed upregulation of multiple immune-related pathways in blood samples collected years before endometriosis diagnosis.

In this prospective analysis using aptamer-based proteomics, we identified multiple proteins and biological pathways related to innate immune response upregulated years before endometriosis surgical diagnosis, suggesting the role of immune dysregulation in endometriosis development.

This study was supported by the Department of Defence, the 2017 Boston Center for Endometriosis Trainee Award. Investigators were supported by Aspira Women's Health and NIH which were not directly related to this project.

Calprotectin is a protein predominantly found in the cytosol of myeloid cells, such as neutrophils and monocytes. Calprotectin has several functions in innate immunity, such as attenuating bacteria, recruiting and activating immune cells, and aiding in the production of pro-inflammatory cytokines and reactive oxygen species. Due to its presence in inflammatory sites, it has been investigated as a biomarker for various medical conditions, especially Inflammatory bowel diseases (IBD), rheumatoid arthritis (RA), and has gained interest in the diagnosis of several infectious diseases, in particular for diagnosing periprosthetic joint infections (PJI). Synovial fluid calprotectin has demonstrated to be a sensitive and specific biomarker for both confirming as well as excluding PJI. Synovial fluid calprotectin can be measured using enzyme-linked immunosorbent assay (ELISA), immunoturbidimetry, and lateral flow methods. It is a generally stable biomarker, showing no significant decrease or increase in its levels despite blood or lipid contamination, storage duration, freeze-thaw cycles, and enzymatic pretreatments for viscosity reduction. This review discusses the biology and physiology of calprotectin, pathophysiology of PJI, and the clinical and analytical considerations surrounding its use in diagnosing PJI.

Rheumatoid arthritis (RA) is an autoimmune, chronic inflammatory disease that mainly affects the joints and periarticular soft tissues. Although there have been significant advances in RA treatment over the past two decades, approximately 40% of patients do not respond to first-line biological disease-modifying antirheumatic drugs (bDMARDs). Physicians often use an empirical, trial-and-error approach to select bDMARDs to treat patients with RA. This is inefficient and can be costly for healthcare systems which have limited resources. Unlike in oncology, where molecular pathology helps guide targeted therapies, reliable, predictive biomarkers for drug response in RA are yet to be identified. This narrative review aims to summarise current knowledge on novel biomarkers of disease activity and drug response in RA, with a particular focus on serum cytokine profiles and macrophage and fibroblast subsets in synovial tissue. We also highlight key areas of further research that could advance the development of targeted therapies for patients with RA.

We searched PubMed to identify studies pertaining to biomarkers of disease activity and drug response in the treatment of RA.

We present a detailed overview of the key studies that have identified serum cytokine profiles and synovial macrophage and fibroblast subsets as novel biomarkers of disease activity and drug response in RA.

A novel, evidence-based approach to precision medicine in RA, which involves tailoring treatment based on cytokine profiles and synovial tissue signatures, shows promise for improving patient care. However, more research is needed to identify biomarkers that predict drug response.

Acute kidney injury (AKI) is a major complication after acute type A aortic dissection (ATAAD), with an incidence rate of 20-66.7%. Many patients with AKI after ATAAD surgery show no clear signs of ischemia-reperfusion injury. In our previous study, S100A8 and S100A9 were identified as predictive biomarkers of AKI after ATAAD surgery. These proteins are primarily expressed in neutrophils and macrophages, where they contribute to cell damage and immune cell activation. However, the roles of S100A8/A9 in ATAAD-associated AKI remain unclear.

In this study, transcriptomics sequence was applied to identify differentially expressed genes in renal tubular epithelial cells (TCMK-1), stimulated by culture supernatant of S100A8/A9 overexpressed and downregulated RAW264.7 cells. Single-cell sequencing data were used to identify cell clusters with high S100A8/A9 expression. Cross-analysis between RNA sequencing datasets was used to investigate common pathways enrichment in both in vitro and in vivo models. Molecular biology experiments were used to explore the downstream signaling pathways of S100A8/S100A9.

We found that S100A8/S100A9 expression levels were increased and co-localized primarily with macrophages in the kidneys of AKI mice. Marker genes of M1-type macrophages, like Nos2 and Il1b, were upregulated in S100A8/A9 overexpressed M1-type macrophages, while the opposite was observed in the downregulated group. In transcription sequencing results, TCMK-1 cells stimulated by the supernatant from S100A8/A9 overexpressed and downregulated RAW264.7 cells can activate the TNF and PPAR pathway respectively. Cross-analysis revealed that the TNF signaling, IL-17 signaling, and other inflammatory pathways were enriched in both S100A8/A9-related renal tubular epithelial cell impairment and other AKI sequencing datasets. Finally, recombinant protein S100A8/A9 activated the TNF signaling pathway in renal tubular epithelial cells.

These findings suggested that S100A8/A9 were promising predictive biomarkers for AKI after surgery for ATAAD. S100A8/A9 were upregulated and primarily localized in renal macrophages, where they promoted the transformation of macrophages into the M1 phenotype. S100A8/A9 overexpressed macrophages activated the TNF signaling pathway through secretion and direct interaction with renal tubular epithelial cells, highlighting the critical role of TNF signaling in AKI after ATAAD surgery.

Chronic pancreatitis (CP) is a fibro-inflammatory syndrome with unclear pathogenesis and futile therapy. CP's microenvironment disrupts the fine-tuned balance of macrophage polarization toward a predominance of the M2-like phenotype associated with fibrosis. S100A9 is mainly expressed in monocytes as a potent regulator of macrophage phenotype and function. Here, we investigated the S100A9-related mechanisms underlying CP pathology induced by macrophages polarization.

S100a9 knockout (S100a9 -/-) mice and an in vitro coculture system of macrophages overexpressing S100a9 and primary PSCs were constructed to investigate the effects and mechanisms of S100A9-mediated macrophage polarization on pancreatic inflammation and fibrosis underpinning CP pathology. Furthermore, a variety of S100A9-targeted small-molecule compounds were screened from U.S. Food and Drug Administration (FDA)-listed drug libraries through molecular docking and virtual screening techniques.

In CP progression, S100A9 upregulation induces M2 macrophage polarization to accelerate fibrosis via thousand-and-one amino acid kinase 3 (TAOK3)-c-Jun N-terminal kinase (JNK) signaling pathway, and loss of S100A9 reduces CP injury in vitro and in vivo. Coimmunoprecipitation (co-IP) and molecular docking experiments proved that S100A9 may interact directly with TAOK3 through salt bridges and hydrogen bonding interactions of the residues in the S100A9 protein. Furthermore, cobamamide and daptomycin, as inactivators of the S100A9-TAOK3 interaction, can improve CP by inhibiting the polarization of M2 macrophages.

S100A9 is a significant promoter of M2-like macrophage-induced fibrosis in CP via the TAOK3-JNK signaling pathway. Cobamamide and daptomycin, targeted inhibitors of the S100A9-TAOK3 interaction, may become candidate drugs for CP immunotherapy.

The aim of this study was to investigate the relationship between placental abruption and maternal plasma calprotectin levels.

This prospective study included 3865 pregnant women aged 24 weeks' gestation and older who were admitted to Etlik Zübeyde Hanım Women's Health Training and Research Hospital between January 2021 and January 2024. Calprotectin levels were prospectively studied in 33 pregnant women with placental abruption and compared with 48 healthy pregnant women matched for age, parity, body mass index (BMI) and week of gestation. Pregnant women with preeclampsia, gestational diabetes, chorioamnionitis, premature rupture of membranes, preterm labor, corticosteroid use within 7 days, cholestasis, fetal growth restriction, fetal anomalies, systemic infections and multiple pregnancies were excluded from the study. The calprotectin concentration in serum was measured with a Rayto Microplate Reader RT 2100 C (Rayto) using an immunoassay method at 450 wavelengths.

There was no difference between the groups regarding maternal age, gravidity, parity and BMI. Calprotectin levels were significantly higher in the placental abruption group (p < 0.001). The optimal cutoff value for calprotectin was 91.95 ng/ml (sensitivity 66.67%, specificity 89.58%, the area under the curve (AUC) 0.763, 95% confidence interval 0.649-0.876, and p < 0.001).

The results obtained in the present study revealed an association between placental abruption and higher maternal serum calprotectin levels.

Prior studies indicate that serum calprotectin (SC) and plasma calprotectin (PC) can be used as biomarkers in Crohn's disease (CD). The aim of this study was to investigate the diagnostic accuracy of SC and PC in patients with a clinical suspicion of CD.

This biobank study included patients from a prospective, blinded, multicenter study examining minimally invasive modalities for diagnosing CD. Patients had a standardized work-up including ileocolonoscopy, pan-enteric capsule endoscopy, and blood samples within a 2-week period. Plasma and serum were stored at - 80 °C until further analysis. A routine C-reactive protein (CRP) was measured on the same day. Pan-endoscopy served as reference standard.

126 patients entered the study, and 58 (46.0%) were diagnosed with CD. Patients with CD had a median PC of 0.37 mg/L (IQR 0.20-0.70) compared to 0.29 mg/L (IQR 0.16-0.41) in non-CD patients (p = 0.03). The median SC was 1.09 mg/L (IQR 0.80-1.80) and 0.93 mg/L (IQR 0.66-1.25), respectively (p = 0.01). Receiver operating characteristics curves showed an AUC of 0.63 (CI 0.53-0.73) for SC and 0.61 (CI 0.51-0.71) for PC for detection of CD, which was inferior to that of CRP (AUC = 0.76, CI 0.68-0.85) (p < 0.02). None of the biomarkers reflected the endoscopic severity of CD.

Although levels of PC and SC are elevated in patients with CD, diagnostic accuracies are inferior to CRP. SC and PC are not reliable as stand-alone blood-based biomarkers for diagnosing CD and selecting patients for endoscopy.

An ideal test to evaluate the inflammatory burden in ulcerative colitis is still an unmet need. Fecal calprotectin (FCP) and C-reactive protein (CRP) have significant limitations. Plasma calprotectin (PC) seems to be promising in inflammatory diseases, but its value in IBD is still to be determined. Our aim was to assess whether PC correlates with inflammatory activity in UC.

Prospective single center cohort study. Consecutive patients previously diagnosed with UC undergoing endoscopy were included (June 2021-September 2022). Demographic, clinical, analytical (CRP, PC and FCP), endoscopic and histologic data was collected at the time of colonoscopy. PC was assessed with Gentian Calprotectin Immunoassay and, in a subgroup of patients, also with QUANTA Flash Circulating Calprotectin from INOVA.

Inclusion of 98 patients (60.2% male) with a median age 49 (38-61) years. The extent of colitis was distal in 12 (12.2%), left-sided in 49 (50%), and extensive in 37 (37.8%). Mesalazine was taken by 65 (66.3%) patients, with biologic monotherapy used in 24 (24.5%) and combination therapy in 6 (6.1%). Clinical, endoscopic and histological remission were detected, in 56 (57.1%), 48 (49%) and in 55 (56.1%) patients, respectively. Comparing MES 0/1 vs MES 2/3, a statistically significant difference was found with PC, CRP and FCP. Concerning endoscopic (MES=1) and histological (GS<2) remission, FCP was the only biomarker able to detect these outcomes. PC (Gentian) and PCi (INOVA) were highly correlated with CRP.

PC has low value in distinguishing patients in remission from patients with endoscopic or histologic activity in UC. This essential role must continue be played by FCP.

The management of inflammatory bowel disease (IBD), which is characterized by immunodeficiency, has attracted increasing attention, highlighting the necessity for more precise and streamlined diagnostic approaches in clinics. Calprotectin, an immune cell-derived protein with inherent anti-inflammatory and antimicrobial properties, plays a pivotal role in immune regulation and intestinal homeostasis. Its expression levels are intricately linked to IBD activity, enabling differentiation between inflammatory and non-inflammatory states while predicting recurrence risks. As a non-invasive biomarker, fecal calprotectin (FC) and serum calprotectin (SC) analysis offers high reproducibility and clinical utility, facilitating both IBD diagnosis and real-time disease monitoring. Beyond its diagnostic specificity in distinguishing IBD from other gastrointestinal disorders, calprotectin also emerges as a promising therapeutic target, due to its dual role in modulating inflammatory pathways and interacting with the gut microbiota. With collaborative advancements in standardized detection protocols and innovative research methodologies, it is anticipated that calprotectin-based strategies will be integrated into mainstream clinical practice for IBD.

Ulcerative colitis (UC) is a chronic and refractory inflammatory disease of the colon and rectum. This study utilized bioinformatics methods to explore the potential of Nicotinamide adenine dinucleotide (NAD+) metabolism-related genes (NMRGs) as key genes in UC. Using the GSE87466 dataset, differentially expressed NMRGs were identified through differential expression analysis, weighted gene co-expression network analysis (WGCNA), and NMRG scoring. These NMRGs were used as exposure factors, with UC as the outcome, to identify causal candidate genes through Mendelian randomization (MR) analysis. Key genes were further validated as biomarkers using machine learning and expression validation in external datasets (GSE75214, GSE224758). A nomogram based on the expression levels of these biomarkers was constructed to predict UC risk, and the biomarkers' expression was validated through real-time quantitative polymerase chain reaction (RT-qPCR). Subsequently, signaling pathway analysis, enrichment analysis, immune infiltration analysis, and drug prediction were conducted to comprehensively understand the biological roles of the key genes in the human body. Single-cell (GSE116222) and spatial transcriptomic analyses (GSE189184) revealed the expression patterns of these key genes in specific cell types. NCF2, IL1B, S100A8, and SLC26A2 were identified as biomarkers, with NCF2 and IL1B serving as protective factors and S100A8 and SLC26A2 as risk factors for UC. The nomogram based on these biomarkers demonstrated strong predictive value. Functional analysis revealed significant IL1B, NCF2, and S100A8 enrichment in pathways such as IL-4 and IL-13 signaling, while SLC26A2 was strongly associated with respiratory electron transport. Significant differences in immune cells, such as macrophages and neutrophils, were also observed. Single-cell analysis showed high expression of NCF2, IL1B, and S100A8 in monocytes, while SLC26A2 was primarily expressed in epithelial cells, intestinal epithelial cells, and mast cells. Overall, these findings reveal the roles of NMRGs, providing valuable insights into the diagnosis and treatment of UC patients.

To investigate the role of S100A8/A9 in the pathogenesis of Sjögren's dry eye disease (SjDED) and explore its potential mechanism of action.

S100A8/A9 expression was determined by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). Tear secretion, corneal fluorescein staining, and hematoxylin and eosin staining were used to evaluate the effect of paquinimod, a S100A8/A9 inhibitor, on dry eye disease in nonobese diabetic (NOD) mice. Immune cell infiltration and percentage were assessed by immunofluorescence and flow cytometry. Proinflammatory cytokine levels were examined by qRT-PCR or ELISA. The mechanism of action was analyzed using western blot, immunofluorescence, and chromatin immunoprecipitation.

S100A8/A9 was upregulated in peripheral blood mononuclear cells of patients with SjDED and lacrimal glands (LGs) of SjDED mice. The upregulation of S100A8/A9 was correlated with the dry eye severity and inflammatory infiltration levels in LGs. Administration of paquinimod ameliorated clinical and histopathological phenotypes of SjDED mice and reduced the proportion of Th17 cells in LGs, lymph nodes, and spleens. Further experiments revealed that S100A8/A9 did not directly affect Th17 generation and function but upregulated the expression of major histocompatibility complex Ⅱ (MHC Ⅱ) and Th17-polarizing cytokines in dendritic cells (DCs) to augment Th17 cell response. Mechanistically, S100A8/A9 induced the expression of Acod1 and thereby promoted the activation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3), resulting in increased Il23a transcription. STAT3 activator reversed the therapeutic effect of paquinimod on SjDED mice.

S100A8/A9 activated the Acod1/STAT3 pathway to promote DC-driven Th17 cell responses in SjDED. The S100A8/A9/Acod1/STAT3 pathway may represent a promising therapeutic target for SjDED.

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune condition that primarily affects the joints and periarticular soft tissues. In the past two decades, the discovery of new biomarkers has contributed to advances in the understanding of the pathogenesis and natural history of RA. These biomarkers, including genetic, clinical, serological and imaging biomarkers, play a key role in the different stages and aspects of RA, from the so called 'pre-clinical RA', which is characterized by subclinical pathological events, such as autoimmunity and inflammation, to diagnosis (including differential diagnosis), treatment decision making and disease monitoring.This review will provide an overview on the current role of traditional and newer biomarkers in the main aspects of RA management, from the identification of individuals 'at-risk' of RA who are likely to progress to clinically evident disease, to 'early' diagnosis of RA, prognosis, precision medicine, and prediction of response to treatment.

Mrp 8/14 is abundantly secreted by activated neutrophils during infection and inflammation. However, its prognostic value in acute respiratory distress dyndrome (ARDS) induced by sepsis is poorly understood. Our aim was to investigate the relationship between serum Mrp 8/14 and the prognosis in sepsis-induced ARDS patients admitted to the intensive care unit (ICU).

Serum Mrp 8/14 concentrations were analyzed in 118 ARDS patients induced by sepsis included in the analytical study. Patients were enrolled upon admission to the ICU of Nanjing Hospital affiliated to Nanjing Medical University. The baseline information and clinical outcomes were obtained. Patients were divided into survivor group and non-survivor group according to whether they died during ICU hospitalization.

The serum Mrp 8/14 levels were significantly increased in the non-survivor group compared to the survivor group (P < 0.05). Logistic regression analysis showed that serum Mrp 8/14, albumin and APACHE II were the independent factors for predicting the prognosis of sepsis-induced ARDS during ICU hospitalization after adjustment. Additionally, the area under the receiver operating characteristic curve for Mrp 8/14 combined with albumin was associated with ICU mortality and was higher than that of Mrp 8/14, albumin, APACHE II and Mrp 8/14 combined with APACHE II (all P < 0.05). A nomogram was constructed to predict ICU mortality and the c-indexes of predictive accuracy was 0.830 in the cohort (P < 0.05).

The serum Mrp 8/14 upon ICU admission in septic patients may be useful for predicting mortality in sepsis-induced ARDS patients during ICU hospitalization.

In recent years, numerous potential prognostic biomarkers for rheumatoid arthritis (RA) have been investigated. Despite these advancements, clinical practice primarily relies on autoantibody tests-for rheumatoid factor (RF) and anti-citrullinated protein antibody (anti-CCP)-alongside inflammatory markers, such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Expanding the repertoire of diagnostic and therapeutic biomarkers is critical for improving clinical outcomes in RA. Emerging evidence highlights the significance of synovial fluid biomarkers, including aggrecan, matrix metalloproteinases, glucosyl-galactosyl-pyridinoline, hyaluronic acid, S100 proteins, calprotectin, and various cytokines, as well as immunological markers. Additionally, specific components of extracellular vesicles, such as non-coding RNAs, heat shock proteins, and lipids, are gaining attention. This review focuses on molecular markers found in synovial fluid and extracellular vesicles, excluding clinical and imaging biomarkers, and explores their potential applications in the diagnosis and management of RA.

Nucleic acid vaccines play important roles in prevention and treatment of diseases. However, limited immunogenicity remains a major obstacle for DNA vaccine applications in the clinic. To address the issue, the present study investigates a cocktail approach to DNA vaccination. In this proof-of-the-concept study, the cocktail consists of two DNAs encoding viral hemagglutinin (HA) and granulocyte-macrophage colony stimulatory factor (GM-CSF), respectively. Data from the study demonstrate that recruitment and activation of antigen-presenting cells (APCs) can be substantially improved by spatiotemporal regulation of GM-CSF and HA expressions at the site of vaccination. The types of recruited APCs and their phenotypes are also controllable by adjusting the cocktail compositions. Compared to mono-ingredient vaccine, the optimized cocktail vaccine is able to enhance the anti-viral humoral and T cell immune responses. No significant systemic inflammation has been detected after either prime or boost immunization using the cocktail vaccine. Data in the study suggest that the DNA cocktail is a safe, effective, and controllable platform for improving vaccine efficacy.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder marked by sustained joint inflammation, with an etiology that remains elusive. Achieving an early and precise diagnosis poses significant challenges. This study aims to elucidate the molecular pathways involved in RA pathogenesis by screening genes associated with its occurrence, analyzing the related molecular activities, and ultimately developing more effective molecular-level treatments for RA.

Microarray expression profiling datasets GSE1919, GSE10500, GSE15573, GSE77298, GSE206848, and GSE236924 were sourced from the Gene Expression Omnibus (GEO) database. Samples were divided into experimental (RA) and control (normal) groups. Differentially expressed genes (DEGs) were identified using R software packages such as limma, glmnet, e1071 as well as randomForest. Cross-validation of DEGs was conducted using lasso regression and the random forest (RF) algorithm in R software to pinpoint intersecting genes that met the criteria. Among these, one gene was selected as the target for correlation analysis to identify DEGs related to the target gene. Enrichment analysis utilized the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway databases and Gene Ontology (GO) data. Gene Set Enrichment Analysis (GSEA) was performed to compare the expression levels of the target gene (PDK4) across various biological pathways and functions in groups with high and low expression. The relationship between target gene expression levels and cellular immune function was assessed using the immune function score technique. The discrepancy in immune cell distribution between the control and experimental groups, as well as their correlation with target gene expression levels, was elucidated using CIBERSORT. The relationships between mRNA, lncRNA, and miRNA were depicted in the ceRNA regulation network. The expression levels of the target gene were validated using Western blot and qRT-PCR.

In this study, six intersecting genes meeting the criteria were identified through cross-validation, and PDK4 was chosen as the target gene for further investigation. Functional analysis using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) revealed that PDK4-associated DEGs are primarily enriched in the PPAR signaling pathway, thereby regulating synovial cell proliferation and migration, ultimately influencing the onset and progression of rheumatoid arthritis (RA). Immune infiltration analysis suggested that eosinophil quantity may influence the progression of RA. Experimental results from PCR and Western blot confirmed the downregulation of PDK4 in the RA group.

The significant downregulation of PDK4 expression in patients diagnosed with rheumatoid arthritis (RA) was confirmed. PDK4 may function as a novel regulatory factor in the onset and progression of RA, with potential applications as a diagnostic biomarker for the condition.

This study investigates the role of S100A9 in sepsis-associated AKI (SA-AKI) through the lens of pyroptosis, a controlled form of cell death mediated by the gasdermin protein family. Using C57BL/6 mice and S100A9 knockout mice subjected to cecal ligation and puncture (CLP), RNA sequencing and bioinformatics analyses revealed differentially expressed genes (DEGs) related to inflammation and immune responses, with notable upregulation of S100A9. Functional enrichment analyses (GO and KEGG) indicated these DEGs are involved in interferon-beta response, immune processes, and cell adhesion. Protein-protein interaction (PPI) network analyses further emphasized S100A9's pivotal role in SA-AKI.Clinical validation measured S100A9 levels in serum and urine samples from SA-AKI patients and healthy volunteers, finding elevated S100A9 levels in the former. In vivo experiments showed that S100A9 knockout mice exhibited reduced kidney injury and inflammation, indicated by lower serum creatinine, urea nitrogen, and inflammatory markers (IL-1β and IL-18). Histopathological analyses and immunohistochemistry confirmed less renal damage and reduced expression of cleaved IL-1β and GSDMD-N in S100A9-deficient mice. Electron microscopy and Western blotting validated that S100A9 deficiency mitigates caspase-1-dependent pyroptosis.Cellular experiments with HK-2 cells demonstrated that S100A9 knockdown alleviated LPS-induced cell damage and reduced pyroptosis markers. These findings illuminate S100A9's involvement in NLRP3 inflammasome activation and pyroptosis, suggesting potential therapeutic targets for SA-AKI. Targeting S100A9 may offer new therapeutic avenues, improving outcomes for sepsis-related kidney injury patients. Future research should aim to validate these findings in larger clinical settings.

The calcium-binding protein S100A9 has emerged as a pivotal biomolecular actor in oncology, implicated in numerous malignancies. This comprehensive bioinformatics study transcends traditional boundaries, investigating the prognostic and therapeutic potential of S100A9 across diverse neoplastic entities. Leveraging a wide array of bioinformatics tools and publicly available cancer genomics databases, such as TCGA, we systematically examined the S100A9 gene. Our approach included differential expression analysis, mutational burden assessment, protein interaction networks, and survival analysis. This robust computational framework provided a high-resolution view of S100A9's role in cancer biology. The study meticulously explored S100A9's oncogenic facets, incorporating comprehensive analyses of its relationship with prognosis, tumor mutational burden (TMB), microsatellite instability (MSI), DNA methylation, and immune cell infiltration across various tumor types. This study presents a panoramic view of S100A9 expression across a spectrum of human cancers, revealing a heterogeneous expression landscape. Elevated S100A9 expression was detected in malignancies such as BLCA (Bladder Urothelial Carcinoma), CESC (Cervical squamous cell carcinoma and endocervical adenocarcinoma), COAD (Colon adenocarcinoma), ESCA (Esophageal carcinoma), and GBM (Glioblastoma multiforme), while reduced expression was noted in BRCA (Breast invasive carcinoma), HNSC (Head and Neck squamous cell carcinoma), and KICH (Kidney Chromophobe). This disparate expression pattern suggests that S100A9's role in cancer biology is multifaceted and context-dependent. Prognostically, S100A9 expression correlates variably with patient outcomes across different cancer types. Furthermore, its expression is intricately associated with TMB and MSI in nine cancer types. Detailed examination of six selected tumors-BRCA, CESC, KIRC (Kidney renal clear cell carcinoma), LUSC (Lung squamous cell carcinoma), SKCM (Skin Cutaneous Melanoma); STAD (Stomach adenocarcinoma)-revealed a negative correlation of S100A9 expression with the infiltration of most immune cells, but a positive correlation with neutrophils, M1 macrophages, and activated NK cells, highlighting the complex interplay between S100A9 and the tumor immune environment. This bioinformatics synthesis posits S100A9 as a significant player in cancer progression, offering valuable prognostic insights. The data underscore the utility of S100A9 as a prognostic biomarker and its potential as a therapeutic target. The therapeutic implications are profound, suggesting that modulation of S100A9 activity could significantly impact cancer management strategies.

Rheumatoid arthritis (RA) is a chronic autoimmune disease with a complex etiology. Neutrophil extracellular traps (NETs are NETwork protein structures activated by neutrophils to induce the cleavage and release of DNA-protein complexes). Current studies have shown the critical involvement of NETs in the progression of autoimmune diseases, Neutrophils mostly gather in the inflammatory sites of patients and participate in the pathogenesis of autoimmune diseases in various ways. NETs, as the activated state of neutrophils, have attracted much attention in immune diseases. Many molecules released in NETs are targeted autoantigens in autoimmune diseases, such as histones, citrulline peptides, and myeloperoxidase. All of these suggest that NETs have a direct causal relationship between the production of autoantigens and autoimmune diseases. For RA in particular, as a disorder of the innate and adaptive immune response, the pathogenesis of RA is inseparable from the generation of RA. In this article, we investigate the emerging role of NETs in the pathogenesis of RA and suggest that NETs may be an important target for the treatment of inflammatory autoimmune diseases.

Fabry disease (FD) is a X-linked rare lysosomal storage disorder caused by deficient α-galactosidase A (α-GalA) activity. Early diagnosis and the prediction of disease course are complicated by the clinical heterogeneity of FD, as well as by the frequently inconclusive biochemical and genetic test results that do not correlate with clinical course. We sought to identify potential biomarkers of FD to better understand the underlying pathophysiology and clinical phenotypes. We compared the plasma proteomes of 50 FD patients and 50 matched healthy controls using DDA and SWATH-MS. The >30 proteins that were differentially expressed between the 2 groups included proteins implicated in processes such as inflammation, heme and haemoglobin metabolism, oxidative stress, coagulation, complement cascade, glucose and lipid metabolism, and glycocalyx formation. Stratification by sex revealed that certain proteins were differentially expressed in a sex-dependent manner. Apolipoprotein A-IV was upregulated in FD patients with complications, especially those with chronic kidney disease, and apolipoprotein C-III and fetuin-A were identified as possible markers of FD with left ventricular hypertrophy. All these proteins had a greater capacity to identify the presence of complications in FD patients than lyso-GB3, with apolipoprotein A-IV standing out as being more sensitive and effective in differentiating the presence and absence of chronic kidney disease in FD patients than renal markers such as creatinine, glomerular filtration rate and microalbuminuria. Identification of these potential biomarkers can help further our understanding of the pathophysiological processes that underlie the heterogeneous clinical manifestations associated with FD.

Fecal calprotectin is a valuable biomarker for assessing intestinal inflammation in pediatric gastrointestinal diseases. However, its role, pros, and cons in various conditions must be comprehensively elucidated.

To explore the role of fecal calprotectin in pediatric gastrointestinal diseases, including its advantages and limitations.

A comprehensive search was conducted on PubMed, PubMed Central, Google Scholar, and other scientific research engines until February 24, 2024. The review included 88 research articles, 56 review articles, six meta-analyses, two systematic reviews, two consensus papers, and two letters to the editors.

Fecal calprotectin is a non-invasive marker for detecting intestinal inflammation and monitoring disease activity in pediatric conditions such as functional gastrointestinal disorders, inflammatory bowel disease, coeliac disease, coronavirus disease 2019-induced gastrointestinal disorders, gastroenteritis, and cystic fibrosis-associated intestinal pathology. However, its lack of specificity and susceptibility to various confounding factors pose challenges in interpretation. Despite these limitations, fecal calprotectin offers significant advantages in diagnosing, monitoring, and managing pediatric gastrointestinal diseases.

Fecal calprotectin holds promise as a valuable tool in pediatric gastroenterology, offering insights into disease activity, treatment response, and prognosis. Standardized protocols and guidelines are needed to optimize its clinical utility and mitigate interpretation challenges. Further research is warranted to address the identified limitations and enhance our understanding of fecal calprotectin in pediatric gastrointestinal diseases.

Inflammation is involved in the pathogenesis of diabetes, however the impact of diabetes on organ-specific autoimmune diseases remains unexplored. Experimental autoimmune uveoretinitis (EAU) is a widely accepted animal model of human endogenous uveitis. In this study, we investigated the effects of diabetic conditions on the development of EAU using a mouse diabetes model.

EAU was induced in wild-type C57BL/6 (WT) mice and Ins2Akita (Akita) mice with spontaneous diabetes by immunization with IRBP peptide. Clinical and histopathological examinations, and analysis of T cell activation state were conducted. In addition, alternations in the composition of immune cell types and gene expression profiles of relevant immune functions were identified using single-cell RNA sequencing.

The development of EAU was significantly attenuated in immunized Akita (Akita-EAU) mice compared with immunized WT (WT-EAU) mice, although T cells were fully activated in Akita-EAU mice, and the differentiation into Th17 cells and regulatory T (Treg) cells was promoted. However, Th1 cell differentiation was inhibited in Akita-EAU mice, and single-cell analysis indicated that gene expression associated AP-1 signaling pathway (JUN, FOS, and FOSB) was downregulated not only in Th1 cells but also in Th17, and Treg cells in Akita-EAU mice at the onset of EAU.

In diabetic mice, EAU was significantly attenuated. This was related to selective inhibition of Th1 cell differentiation and downregulated AP-1 signaling pathway in both Th1 and Th17 cells.

This study assesses the accuracy of neutrophil activation markers, including neutrophil extracellular traps (NETs) and calprotectin, as biomarkers of disease activity in patients with established rheumatoid arthritis (RA). We also analyse the relationship between NETs and various types of therapies as well as their association with autoimmunity.

Observational cross-sectional study of patients with RA receiving treatment with biological disease-modifying antirheumatic drugs or Janus kinase inhibitors (JAK-inhibitors) for at least 3 months. Plasma calprotectin levels were measured using an enzyme-linked immunosorbent assay test kit and NETs by measuring their remnants in plasma (neutrophil elastase-DNA and histone-DNA complexes). We also assessed clinical disease activity, joint ultrasound findings and autoantibody status [reumatoid factor (RF), anti-citrullinated peptide/protein antibodies (ACPAs) and anti-carbamylated protein (anti-CarP)]. Associations between neutrophilic biomarkers and clinical or ultrasound scores were sought using correlation analysis. The discriminatory capacity of both neutrophilic biomarkers to detect ultrasound synovitis was analysed through receiver-operating characteristic (ROC) curves.

One hundred fourteen patients were included. Two control groups were included to compare NET levels. The active control group consisted of 15 patients. The second control group consisted of 30 healthy subjects. Plasma NET levels did not correlate with clinical disease status, regardless of the clinic index analysed or the biological therapy administered. No significant correlation was observed between NET remnants and ultrasound synovitis. There was no correlation between plasma NET and autoantibodies. In contrast, plasma calprotectin positively correlated with clinical parameters (swollen joint count [SJC] rho = 0.49; P < 0.001, Clinical Disease Activity Index [CDAI] rho = 0.30; P < 0.001) and ultrasound parameters (rho > 0.50; P < 0.001). Notably, this correlation was stronger than that observed with acute phase reactants.

While NET formation induced by neutrophils may play a role in RA pathogenesis, our study raises questions about the utility of NET remnants in peripheral circulation as a biomarker for inflammatory activity. In contrast, this study strongly supports the usefulness of calprotectin as a biomarker of inflammatory activity in patients with RA.

Background: Calprotectin (CP) is a calcium- and zinc-binding protein that plays a key role in innate immunity and in the recruitment of inflammatory cells. CP can be detected both in serum and in fecal samples. Serum CP (sCP) is more specific for autoimmune diseases, while fecal CP (fCP) has been well investigated for gastrointestinal diseases. Few studies have shown the clinical effectiveness of sCP as an acute-phase biomarker for gastrointestinal diseases. Aim: The aim of this narrative review is to discuss the role of sCP as a useful alternative biomarker of the acute-phase activity of gastrointestinal diseases and as a possible tool for screening and monitoring these diseases. Material and Methods: We searched original articles, abstracts, reviews, case reports, and clinical trials on PubMed®, Up-to-Date®, and Medscape® in the last ten years. Conclusion: We found that sCP could represent a useful biomarker in the evaluation of the inflammatory stage in patients with immune-mediated gastrointestinal diseases, but more studies are needed to promote its routine use in clinical practice as a diagnostic and prognostic biomarker as a replacement for fCP.

Rheumatoid arthritis (RA) is an autoimmune disease of unknown exact cause, characterized by chronic inflammation. The prognostic nutritional index (PNI), reflecting albumin concentration and lymphocyte count, is a newly established inflammation-based nutritional score. This study aimed to determine the relationship between PNI and disease activity in RA patients.

This cross-sectional study included 138 RA patients who met the 2010 revised criteria of the American College of Rheumatology (ACR) for RA. PNI was calculated using the following formula: 10 × serum albumin value (g/dL) + 0.005 × total lymphocyte count in the peripheral blood (per mm3). The study population was divided into two groups: DAS28-ESR ≤ 3.2 (group 1 with remission and low disease activity) and DAS28-ESR > 3.2 (group 2 with moderate and high disease activity).

A total of 138 patients with a mean age of 52.1 years were recruited. While the female gender was more prevalent in both groups, it was significantly higher in group 2 (p < 0.05). Group 2 exhibited a lower PNI compared to those in group 1 (42.17 ± 3.46 vs. 44.02 ± 2.92; p = 0.001). Multivariate logistic regression analyses revealed that PNI was an independent predictor of disease activity (OR, 0.850; 95% CI, 0.735-0.983; p = 0.029). ROC curve analysis determined that the optimal cutoff value of PNI for disease activity was 43.01, with a sensitivity of 69.1% and specificity of 57.7% (AUC, 0.66; 95% CI, 0.57-0.75, p = 0.001).

This study demonstrates that the simple and readily available PNI could serve as an independent predictor of disease activity in rheumatoid arthritis patients. Key Points •The relationship between disease activity and the prognostic nutritional index, which is a nutritional indicator, in rheumatoid arthritis patients was investigated. •It has been shown that there is a connection between low PNI and high disease activity. •It has been shown that PNI can be used to evaluate disease severity with a simple calculation.

The present study aimed to investigate the value of calprotectin and other inflammatory parameters in patients with glaucoma and systemic diseases accompanying pseudoexfoliation syndrome (PEX-S).

This prospective study included 45 PEX-S patients and 45 non-PEX control patients. Patients were investigated for the presence of glaucoma, cardiovascular disease (CVD), ischemic brain disease (IBD), Alzheimer's disease, and neurosensory hearing loss (NSHL). After excluding diseases that may affect inflammatory parameters, a detailed biomicroscopic examination, and blood tests were performed for the patients.

Glaucoma, CVD, NVK, Alzheimer's disease, and NSHL were high in the PEX-S group ( P = 0.01, P = 0.01, P = 0.04, P = 0.04, and P = 0.03, respectively). Calprotectin, ferritin, neutrophil-to-platelet ratio, and lymphocyte-to-platelet ratio were found to be high in the PEX-S group ( P < 0.01, P = 0.04, P < 0.01, and P < 0.01, respectively). On evaluating the relationship between PEX-S and glaucoma and systemic diseases, it was found that elevated calprotectin increased the risk of glaucoma by 4.36 times and elevated neutrophil-to-lymphocyte ratio (NLR) increased the risk of CVD by 3.23 times in PEX-S patients ( P = 0.02 and P = 0.03, respectively).

This study demonstrated the value of calprotectin elevation in detecting concomitant glaucoma in PEX-S patients and, in addition, the value of NLR elevation in detecting concomitant CVD.

S100A8 and S100A9 belong to the calcium-binding, damage associated molecular pattern (DAMP) proteins shown to aggravate the pathogenesis of rheumatoid arthritis (RA) through their interaction with the TLR4, RAGE and CD36 receptors. S100A8 and S100A9 proteins tend to exist in monomeric, homo and heterodimeric forms, which have been implicated in the pathogenesis of RA, via interacting with Pattern Recognition receptors (PRRs). The study aims to assess the influence of changes in the structure and biological assembly of S100A8 and S100A9 proteins as well as their interaction with significant receptors in RA through computational methods and surface plasmon resonance (SPR) analysis. Molecular docking analysis revealed that the S100A9 homodimer and S100A8/A9 heterodimer showed higher binding affinity towards the target receptors. Most S100 proteins showed good binding affinity towards TLR4 compared to other receptors. Based on the 50 ns MD simulations, TLR4, RAGE, and CD36 formed stable complexes with the monomeric and dimeric forms of S100A8 and S100A9 proteins. However, SPR analysis showed that the S100A8/A9 heterodimers formed stable complexes and exhibited high binding affinity towards the receptors. SPR data also indicated that TLR4 and its interactions with S100A8/A9 proteins may play a primary role in the pathogenesis of RA, with additional contributions from CD36 and RAGE interactions. Subsequent in vitro and in vivo investigations are warranted to corroborate the involvement of S100A8/A9 and the expression of TLR4, RAGE, and CD36 in the pathophysiology of RA.

The incidence of chronic kidney disease (CKD) has been increasing in recent years, gradually becoming a global health crisis. Due to limited treatment options, novel molecular pathways are urgently required to advance the treatment and diagnosis of CKD.

The characteristics of differentially expressed genes (DEGs) in CKD patients were analyzed using Gene Expression Omnibus (GEO) database, and genes related to oxidative stress were retrieved from the Genecard database. Subsequently, a comprehensive approach was applied, including immune infiltration analysis, weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) network analysis, to identify hub genes among differentially expressed immune-related oxidative stress genes (DEIOSGs). Validation of hub genes was performed using an external data set, and diagnostic potential capability was evaluated through receiver operating curve (ROC) analysis. In animal experiments, the expression of hub genes in CKD was confirmed by inducing a CKD model through a 5/6 nephrectomy procedure. Finally, the relationship between these hub genes and clinical characteristics were assessed using the Nephroseq v5 database.

29 DEIOSGs were identified by comprehensive bioinformatics analysis. PPI analysis screened the hub genes NCF2, S100A9, and SELL. ROC analysis demonstrated excellent diagnostic efficacy. Further validation from other databases and animal experiments confirmed a substantial upregulation in the expression of hub genes in CKD. Additionally, clinical correlation analysis established a clear link between hub gene expression and renal function deterioration.

Our study confirms NCF2, S100A9, and SELL as diagnostic biomarkers associated with immune response and oxidative stress in CKD, suggesting their potential as novel targets for CKD diagnosis and treatment.

Patients with coronavirus disease-2019 (COVID-19) are characterized by hyperinflammation. Calprotectin (S100A8/S100A9) is a calcium- and zinc-binding protein mainly secreted by neutrophilic granulocytes or macrophages and has been suggested to be correlated with the severity and prognosis of COVID-19.

To thoroughly evaluate the diagnostic and prognostic utility of calprotectin in patients with COVID-19 by analyzing relevant studies.

PubMed, Web of Science, and Cochrane Library were comprehensively searched from inception to August 1, 2023 to retrieve studies about the application of calprotectin in COVID-19. Useful data such as the level of calprotectin in different groups and the diagnostic efficacy of this biomarker for severe COVID-19 were extracted and aggregated by using Stata 16.0 software.

Fifteen studies were brought into this meta-analysis. First, the pooled standardized mean differences (SMDs) were used to estimate the differences in the levels of circulating calprotectin between patients with severe and non-severe COVID-19. The results showed an overall estimate of 1.84 (95% confidence interval [CI]: 1.09-2.60). Diagnostic information was extracted from 11 studies, and the pooled sensitivity and specificity of calprotectin for diagnosing severe COVID-19 were 0.75 (95% CI: 0.64-0.84) and 0.88 (95% CI: 0.79-0.94), respectively. The AUC was 0.89 and the pooled DOR was 18.44 (95% CI: 9.07-37.51). Furthermore, there was a strong correlation between elevated levels of circulating calprotectin and a higher risk of mortality outcomes in COVID-19 patients (odds ratio: 8.60, 95% CI: 2.17-34.12; p < 0.1).

This meta-analysis showed that calprotectin was elevated in patients with severe COVID-19, and this atypical inflammatory cytokine might serve as a useful biomarker to distinguish the severity of COVID-19 and predict the prognosis.

Increasing evidence suggests that the calcium-binding and proinflammatory protein S100A9 is an important player in neuroinflammation-mediated Alzheimer's disease (AD). The amyloid co-aggregation of S100A9 with amyloid-β (Aβ) is an important hallmark of this pathology. Apolipoprotein E (ApoE) is also known to be one of the important genetic risk factors of AD. ApoE primarily exists in three isoforms, ApoE2 (Cys112/Cys158), ApoE3 (Cys112/Arg158), and ApoE4 (Arg112/Arg158). Even though the difference lies in just two amino acid residues, ApoE isoforms produce differential effects on the neuroinflammation and activation of the microglial state in AD. Here, we aim to understand the effect of the ApoE isoforms on the amyloid aggregation of S100A9. We found that both ApoE3 and ApoE4 suppress the aggregation of S100A9 in a concentration-dependent manner, even at sub-stoichiometric ratios compared to S100A9. These interactions lead to a reduction in the quantity and length of S100A9 fibrils. The inhibitory effect is more pronounced if ApoE isoforms are added in the lipid-free state versus lipidated ApoE. We found that, upon prolonged incubation, S100A9 and ApoE form low molecular weight complexes with stochiometric ratios of 1:1 and 2:1, which remain stable under SDS-gel conditions. These complexes self-assemble also under the native conditions; however, their interactions are transient, as revealed by glutaraldehyde cross-linking experiments and molecular dynamics (MD) simulation. MD simulation demonstrated that the lipid-binding C-terminal domain of ApoE and the second EF-hand calcium-binding motif of S100A9 are involved in these interactions. We found that amyloids of S100A9 are cytotoxic to neuroblastoma cells, and the presence of either ApoE isoforms does not change the level of their cytotoxicity. A significant inhibitory effect produced by both ApoE isoforms on S100A9 amyloid aggregation can modulate the amyloid-neuroinflammatory cascade in AD.

Parkinson's disease (PD) is a neurodegenerative disease due to degeneration of dopaminergic neurons (DNs) in the substantia nigra pars compacta (SNpc). PD is characterized by motor and non-motor symptoms. Non-motor symptoms such as constipation and dysfunction of gastrointestinal tract (GIT) motility together with medications used in the management of PD affect gut microbiota. Alterations of gut microbiota with development of gut dyspiosis can induce momentous changes in gut barrier with subsequent systemic inflammation and induction of neuroinflammation. It has been shown that calprotectin which reflect intestinal inflammation and gut barrier injury are augmented in PD. Therefore, this review aims to elucidate the possible role of gut barrier injury and associated dysbiois in PD neuropathology, and how calprotectin reflects gut barrier injury in PD. Benefit of this review was to elucidate that high fecal calprotectin level in PD patients indicated gut dysbiosis and intestinal inflammation. Early increment of fecal calprotectin indicates the development of gut dysbiosis and/or gut-barrier injury which may precede motor symptoms by decades. Thus, fecal calprotectin could be a diagnostic and prognostic biomarker in PD. preclinical and clinical studies are warranted in this regard to emphasize the potential role of fecal calprotectin in PD neuropathology.

Calprotectin (CP) is a calcium and zinc binding protein that is widely measured on faecal samples but its determination in other biological fluids might be of interest. The aim of this work was to validate the measurement of CP in pleural fluid by chemiluminescence.

LIAISON®XL, a fully automated chemiluminescence analyzer, was used for CP quantification on pleural fluid. A validation protocol was designed using both quality control materials provided by the manufacturer and pools of pleural fluid samples. Stability, imprecision, bias, linearity, detection capability and carry over effect were evaluated.

CP was stable on pleural fluid at least one week, under refrigerated conditions, and four weeks at -80 °C. The observed intra- and inter-day imprecision was between 2.2 and 6.49 %, with a negative bias under 5.51 %. The linearity of the method was verified up to 2,000 ng/mL. The LoQ for the assay was 48.52 ng/mL. A statistically significant carry-over effect was observed after measuring CP concentrations above the upper limit of linearity, but given the observed magnitude, a clinically relevant impact should not be expected.

DiaSorin Liaison® calprotectin assay allows reliable measurement of CP in pleural fluid.

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.