Antimicrobial peptides (AMPs) are critical components of innate immunity in animals and plants, exhibiting thrilling prospectives as alternatives to traditional antibiotics due to their ability to combat pathogens without leading to resistance. Among these, Human Neutrophil Peptide-1 (HNP-1), primarily produced by human neutrophils, exhibits broad-spectrum antimicrobial activity against bacteria and viruses. However, the clinical application of HNP-1 has been hampered by challenges associated with mass production and inconsistent understanding of its bactericidal mechanisms. This review explores the structure and function of HNP-1, discussing its gene expression, distribution, immune functions and the regulatory elements controlling its production, alongside insights into its antimicrobial mechanisms and potential clinical applications as an antimicrobial agent. Furthermore, the review highlights the biosynthesis of HNP-1 using microbial systems as a cost-effective alternative to human extraction and recent studies revealing HNP-1's endogenous bactericidal mechanism. A comprehensive understanding of HNP-1's working mechanisms and production methods will pave the way for its effective clinical utilization in combating antibiotic-resistant infections.

In the evolving landscape of cancer treatment, therapeutic peptides are assuming to play an increasingly vital role. Although the number of peptide drugs available for clinical cancer treatment is currently limited, extensive preclinical research is underway, presenting a promising trajectory for the future. The collaborative efforts of natural anti-cancer peptides (ACPs) and synthetic ACPs, propelled by advancements in molecular biology and peptide chemistry, are steering remarkable progress in this domain. We explores the intricate mechanisms underlying the anti-cancer effects of these peptides. The exploration of innovative strategies, including cancer immunotherapy and advanced drug delivery systems, is likely to contribute to the increasing presenceuse of peptide drugs in clinical cancer care. Furthermore, we delve into the potential implications and challenges associated with this anticipated shift, emphasizing the need for continued research and development to unlock the full therapeutic potential of peptide drugs in cancer treatment.

In Flanders, an estimated 300,000 leukoreduction filters are discarded as biological waste in the blood establishment each year. These filters are a possible source of fresh donor leukocytes for downstream purposes including research. We investigated leukocyte isolation from two types of filters either used for the preparation of platelet concentrates (PC-LRF) or erythrocyte concentrates (EC-LRF). Outcome parameters were leukocyte yield, differential count, turnaround time and effect of storage conditions. Leukocytes were harvested by reverse flow of a buffer solution. Control was the gold standard density gradient centrifugation of buffy coats. Total leukocyte number isolated from PC-LRF (1049 (± 40) x 106) was almost double that of control (632 (± 66) x 106) but the differential count was comparable. Total leukocyte number isolated from EC-LRF (78 (± 9) x 106) was significantly lower than control, but the sample was specifically enriched in granulocytes (81 ± 4%) compared to control (30 ± 1%). Isolation of leukocytes from either PC- or EC-LRF takes 20 min compared to 240 min for control density gradient centrifugation. Leukocyte viability is optimal when harvested on day 1 post donation (95 ± 0.9%) compared to day 3 (76.4 ± 2.4%). In conclusion, our study demonstrates that leukoreduction filters from specific blood component processing are easy to use and present a valuable source for viable leukocytes of all types.

The adverse consequences resulting from diabetes are often presented as severe complications. Diabetic wounds are one of the most commonly occurring complications in diabetes, and the control and treatment of this is costly. Due to a series of pathophysiological mechanisms, diabetic wounds remain in the inflammatory phase for a prolonged period of time, and face difficulty in entering the proliferative phase, thus leading to chronic non-healing wounds. The current consensus on the treatment of diabetic wounds is through multidisciplinary comprehensive management, however, standard wound treatment methods are still limited and therefore, more effective methods are required. In recent years, defensins have been found to play diverse roles in a variety of diseases; however, the molecular mechanisms underlying these activities are still largely unknown. Defensins can be constitutively or inductively produced in the skin, therefore, their local distribution is affected by the microenvironment of these diabetic wounds. Current evidence suggests that defensins are involved in the diabetic wound pathogenesis, and can potentially promote the early completion of each stage, thus making research on defensins a promising area for developing novel treatments for diabetic wounds. In this review, we describe the complex function of human defensins in the development of diabetic wounds, and suggest potential thera-peutic benefits.

Peripheral blood leukocytes are a suitable cell model for science research. However, blood samples from healthy volunteers are limited in volume and difficult to obtain due to the complexity of volunteer recruitment.

Therefore, it is urgent to find an alternative source of peripheral blood leukocytes.

One of the possibilities is the use of leukocyte reduction filters (LRFs) in blood banks that is used for preparation of leukoreduced blood products. More than 90% of the leukocytes are trapped in the leukofilters allowing the desired blood product to pass through.

It has been reported that the biological function of leukocytes collected from the filters are no different from those isolated from buffy coats, leukapheresis products and whole blood (WB) cells. Moreover, LRFs are waste products that are discarded after leukoreduction.

Thus, leukofilters represent an economic source of human cell populations that can be used for a variety of investigative purposes, with no cost. In the present study, we reviewed the different usage of LRFs in the research, clinical and commercial applications.

(1) Background: Therapeutic blocking of the interaction between programmed death-1 (PD-1) with its ligand PD-L1, an immune checkpoint, is a promising approach to restore the antitumor immune response. Improved clinical outcomes have been shown in different human cancers, including non-small cell lung cancer (NSCLC). Unfortunately, still a high number of NSCLC patients are treated with immunotherapy without obtaining any clinical benefit, due to the limitations of PD-L1 protein expression as the currently sole predictive biomarker for clinical use; (2) Methods: In this study, we applied mass spectrometry imaging (MSI) to discover new protein biomarkers, and to assess the possible correlation between candidate biomarkers and a positive immunotherapy response by matrix-assisted laser desorption/ionization (MALDI) MSI in 25 formalin-fixed paraffin-embedded (FFPE) pretreatment tumor biopsies (Biobank@UZA); (3) Results: Using MALDI MSI, we revealed that the addition of neutrophil defensin 1, 2 and 3 as pretreatment biomarkers may more accurately predict the outcome of immunotherapy treatment in NSCLC. These results were verified and confirmed with immunohistochemical analyses. In addition, we provide in-vitro evidence of the immune stimulatory effect of neutrophil defensins towards cancer cells; and (4) Conclusions: With proteomic approaches, we have discovered neutrophil defensins as additional prospective biomarkers for an anti-PD-(L)1 immunotherapy response. Thereby, we also demonstrated that the neutrophil defensins contribute in the activation of the immune response towards cancer cells, which could provide a new lead towards an anticancer therapy.