Natural killer (NK) cells are innate immune cells able to recognize and eliminate virus-infected cells. NK cell activity strongly correlates with a metabolic reprogramming and breakdown of fatty acids by β-oxidation during virus infections. However, there is limited knowledge regarding the impact of obesity on antiviral NK cell functions. Here, employing the Friend retrovirus mouse model, we show that the cytotoxicity and cytokine production of NK cells was impaired in obesity, leading to higher viral loads. NK cells suppression in obesity was mediated by activated Tregs. Furthermore, obese mice that were switched back to a regular diet showed complete recovery of the NK cell activity. Interestingly, feeding mice with a high-fat diet (HFD) for just ten days caused NK cell dysfunction and increased retroviral burden. This study is the first to link the detrimental impact of an obesity-induced immunosuppressive microenvironment with NK cell dysfunction during an acute retroviral infection.

We report a nutritional intervention involving supplementation with boiled beans and secondary metabolites-enriched extracts (SMEEs) from a Chilean Phaseolus vulgaris landrace in mice with induced metabolic syndrome (MS).

The effects of supplementation were assessed in C57BL6 mice with MS induced by a high-fat diet. Boiled beans (75 and 150 mg animal day-1) and the SMEE (0.8 and 8 mg animal day-1) were administered daily for 4 months. Weight and glycemia were measured weekly. At the end of the experiment, glycemia, total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, triglycerides, protein carbonyls, and carboxymethyl lysine (CML) levels were determined in plasma. Oral intake of the SMEE decreased glycemia at the end of the intervention. No statistically significant difference in glycemia was found for the boiled beans compared with controls. The SMEE at 0.8 mg animal day-1 decreased the total amount of CML, mainly in proteins with molecular masses >75 kDa, in agreement with the results for carbonylated proteins.

The SMEE of Peumo beans reduces glycemia at the end of the intervention and decreases total CML in plasma, suggesting a potential beneficial effect of bean intake. The results obtained in the intervention encourage further studies in Chilean bean landraces.

Diabetes is a major risk factor for Alzheimer's disease (AD), yet the effect of specific carbohydrate sources in the diet on AD pathology remains unclear. The primary neuroimmune cell, microglia, undergo a metabolic shift during neuroinflammation associated with AD pathology. We utilized existing gene expression data and identified changes in sugar transporters (increased Slc2a1 (glucose) and decreased Slc2a5 (fructose) expression). To examine gene expression with respect to primary sugar source, N9 cells, a mouse microglia cell line, were cultured in glucose or fructose supplemented media and stimulated with lipopolysaccharide (LPS). RNA-sequencing analyses indicated significant changes between control and sugar supplemented media and several differentially expressed genes between glucose and fructose media. Concurrently, 5XFAD mice received equicaloric diets with specific carbohydrate sources: dextrose or fructose. Regardless of diet, sex, or genotype, all mice developed high blood sugar levels; confocal microscopy analyses indicated similar amyloid plaque burden and microglial response relative to the control diet, but there was a change in the microglial response between dextrose and fructose fed mice. Overall, these data indicate microglia preferentially express sugar transporters and sugar source may influence microglial reactivity in response to plaque pathology.

Diabetes Mellitus (DM) is a metabolic disease that manifests as a state of "chronic low-grade inflammation". Patients with DM have a disorder of intestinal flora. There is a discernible correlation between this disorder of intestinal flora and the onset and progression of eye diseases, which offers novel insights into treating eye diseases through the modulation of intestinal flora. Here, we demonstrated that a high-fat diet and streptozotocin injection-induced intestinal microbiota dysbiosis can lead to dry eye-like manifestations in T2DM mice. Probiotic and prebiotic treatments not only alleviated intestinal inflammation and barrier disruption, but also mitigated damage to the lacrimal barrier and suppressed immune cell infiltration and inflammatory responses. Additional mechanism investigation found that probiotics and prebiotics inhibited the TLR4/NF-κB signaling pathway and its downstream pro-inflammatory products both in the lacrimal gland and colon. 16S RNA sequencing identified a reduction in the bacterial genera Akkermansia and Lactobacillus in the fecal samples of DM mice. By contrast, treatment with probiotics and prebiotics led to a reshaping of the intestinal microbial community and a reduction in bile acid metabolites, such as taurocholic acid and deoxycholic acid. Our current study demonstrates that probiotic and prebiotic treatments can ameliorate dry eye-like symptoms and associated pathological changes in T2DM mice. Moreover, we proved that a high-fat diet and STZ-induced microbiota dysbiosis were involved in diabetic dry eye through the gut-eye axis.

Tacrolimus (TAC) is an immunosuppressant widely utilized in organ transplantation. One of its primary adverse effects is glucose metabolism disorder, which significantly increases the risk of diabetes. Investigating the molecular mechanisms underlying TAC-induced diabetes is essential for developing effective prevention and treatment strategies for these adverse effects. In addition, TAC can induce cost-effective, non-obese animal models of diabetes, where the metabolic parameter changes closely resemble those observed during the onset and progression of type 2 diabetes (T2DM), post-transplantation diabetes mellitus (PTDM), and associated complications. This review, based on articles indexed in PubMed up to August 19, 2024, identified 48 studies focusing on TAC-induced diabetic rodent models and 22 studies exploring the effects of TAC on diabetic or obese rodent models. These studies were systematically summarized based on TAC dosage, route of administration, duration of administration, and glucose metabolism indices used for evaluation. Additionally, the impact of TAC dose reduction or discontinuation on glucose metabolism was assessed, along with pharmacological agents that modulate TAC-induced diabetes, including anti-diabetic medications, anti-inflammatory and antioxidant compounds, biologics, and antibiotics. Key signaling pathways implicated in TAC-induced diabetes include CaN/NFAT, PI3K/AKT/mTOR, and TGF-β/Smad, all of which impair islet β-cell function, thereby contributing to diabetes development. This review provides a concise summary of the characteristics of relevant murine models, offering valuable guidance for selecting appropriate and economical animal models for future research.

Type 2 diabetes (T2D) is a progressive metabolic disorder characterised by obesity, insulin resistance, impaired glucose tolerance, and hyperglycaemia. The long time-course of T2D in humans makes accurate modelling of sustained T2D in animal models difficult. The goal of this study was to develop and characterise an accurate and reproducible, non-transgenic model of sustained T2D in mice. Adult, male C57BL/6 mice were placed on a high-fat diet (HFD) for 17 weeks. From weeks 3-5, osmotic mini-pumps were implanted subcutaneously to slowly infuse streptozotocin (STZ; 200-350 mg/kg) for 14-days after which mini-pumps were removed. Body weight, blood glucose concentration, and glucose tolerance were monitored for 12 weeks post STZ treatment. Our data demonstrate that the combination of HFD and 200 mg/kg STZ delivered by mini-pump leads to increased blood glucose concentrations and impaired glucose tolerance, while maintaining obesity and hepatic dyslipidaemia. In week 17, plasma insulin concentration was assessed and showed that with STZ treatment, mice still produce insulin, but that this is reduced compared with mice on HFD only. Lastly, we examined pancreas sections using immunohistochemistry and show that there is no overt loss of beta cell mass. In conclusion, we demonstrate development of a reproducible in vivo model of T2D in mice that replicates a number of key pathophysiological changes seen in humans with T2D.

Obesity exacerbates susceptibility to infectious diseases. We investigated the effects of a high-fat diet (HFD) on intestinal immunity, particularly immunoglobulin (Ig)A-producing cells, B-cell activating factor (BAFF), and a proliferation-inducing ligand (APRIL) localization. Mice (4- to 20-weeks old) were fed HFD or standard chow diet, and their jejunum and ileum were fixed using the in vivo cryotechnique. Immunohistochemistry was performed for IgA, BAFF, and APRIL. In the HFD group, IgA+, IgA+CD22+ (p < 0.001), and IgA+CD138- (p = 0.007) cell counts were diminished in the middle sections of the lamina propria of jejunal villi, and BAFF levels were significantly reduced in jejunal villi. The HFD effects on IgA+ cell distribution seem to be confined to jejunal villi, hinting at localized vulnerabilities in intestinal immunity during obesity. Moreover, in the HFD group, IgA+ B-cell counts were reduced in the middle jejunum, indicating inhibition of the IgA+ B-cells through a T-cell-independent pathway.

The nutrient sensor farnesoid X receptor (FXR) transcriptionally regulates whole-body lipid and glucose homeostasis. Several studies examined targeting FXR as a modality to treat obesity with varying conflicting results, emphasizing the need to study tissue-specific roles of FXR. We show that deletion of adipocyte Fxr results in increased adipocyte hypertrophy and suppression of several metabolic genes that is akin to some of the changes noted in high-fat diet (HFD)-fed control mice. Moreover, upon HFD challenge, these effects are worsened in adipocyte-specific Fxr knockout mice. We uncover that FXR regulates fatty acid amide hydrolase (Faah) such that its deletion lowers Faah expression. Conversely, FXR activation by its ligand, chenodeoxycholic acid, induces Faah transcription. Notably, HFD results in the reduction of adipose Faah expression in control mice and that Faah inhibition or deletion is linked to obesity. We report that the adipocyte FXR-Faah axis controls local 2-oleoyl glycerol and systemic N-acyl ethanolamine levels. Taken together, these findings show that loss of adipose FXR may contribute to the pathogenesis of obesity and subsequent metabolic defects.

Rodents have been the primary model for mammalian nutritional physiology for decades. Despite an extensive body of literature, controversies remain around the effects of specific nutrients and total energy intake on several aspects of nutritional biology, even in this well-studied model. One approach that is helping to bring clarity to the field is the geometric framework for nutrition (GFN). The GFN is a multidimensional paradigm that can be used to conceptualize nutrition and nutritional effects, design experiments, and interpret results. To date, more than 30 publications have applied the GFN to data from rodent models of nutrition. Here we review the major conclusions from these studies. We pay particular attention to the effects of macronutrients on satiety, glucose metabolism, lifespan and the biology of aging, reproductive function, immune function, and the microbiome. We finish by highlighting several knowledge gaps that became evident upon reviewing this literature.

Obesity increases the risk for developing several cancers, including colorectal cancer (CRC), and is associated with liver perturbations, which likely impacts treatment tolerance. 5 fluorouracil (5FU) remains a first line treatment for CRC, but efficacy is hampered by interpatient variable responsiveness and off-target toxicities. The current study examined the impact of diet-induced obesity (DIO) on 5FU cytopenia and efficacy using two established CRC models: MC38 (C57BL/6) and C26 (CD2F1). DIO increased tumor size in both MC38 and C26. DIO reduced liver dihydropyrimidine dehydrogenase (dpyd) expression, the enzyme that catalyzes 5FU's catabolism to become inactive, in MC38 mice, but not in C26. 5FU remained efficacious against early MC38 and C26 tumor growth; however, 5FU-induced tumor and liver immune cell death was exacerbated following three cycles of 5FU with MC38. DIO caused dramatic changes to liver Kupffer cells (KCs), wherein there were increased prometastatic, immunosuppressive KCs in Obese Control and MC38. 5FU, however, depleted these KCs and increased inflammatory KCs in both Lean and Obese MC38. DIO yielded a milder obesity phenotype in CD2F1 mice, and 5FU-induced cytopenia was not different between Lean and Obese. DIO increased total liver KCs; however, C26 tumors increased liver KCs, which were normalized with 5FU treatment, irrespective of DIO. Although 5FU remained efficacious in both models of CRC and did not reduce survival, multiple cycles of 5FU monotherapy increased liver and tumor immune cell death in DIO mice. Altogether, obesity was not protective but rather exacerbated chemotherapy-induced cytotoxicity and promoted a prometastatic liver environment.NEW & NOTEWORTHY The current study aimed to examine the impact of obesity on tumorigenesis and 5FU safety and efficacy with two established murine models of colorectal cancer. Diet-induced obesity increased tumor burden in both models, and 5FU's antitumor efficacy remained and extended survival with both tumor models. Obese mice demonstrated increased 5FU-induced immune cell cytotoxicity following multiple cycles of 5FU with distinct changes to liver macrophages, suggesting an increased propensity for liver metastasis.

Both age and diet can contribute to alterations in triglyceride metabolism and subsequent metabolic disease. In humans, plasma triglyceride levels increase with age. Diets high in saturated fats can increase triglyceride levels while diets high in omega-3 fatty acids decrease triglyceride levels. Here we asked how age and long-term diet altered triglyceride metabolism in mice. We fed male and female C57Bl/6 mice a low-fat diet, a western diet (WD), or a diet high in polyunsaturated and omega-3 fatty acids (n3D) for up to 2 years. We measured survival, body composition, plasma triglyceride levels, chylomicron clearance, and oral fat, glucose, and insulin tolerance. Triglyceride levels in mice did not increase with age, regardless of diet. Oral fat tolerance increased with age, while chylomicron clearance remained unchanged. Decreased survival was observed in WD-fed mice. Interestingly, n3D-fed mice gained more lean mass and had lower insulin levels than WD-fed or LFD-fed mice. Moreover, triglyceride uptake into the hearts of n3D-fed mice was strikingly higher than in other groups. Our data indicate that in C57Bl/6 mice, age-induced changes in triglyceride metabolism differ from those observed in humans. Mice, like humans, appeared to have decreased fat absorption with age, but in mice plasma triglyceride clearance did not decrease with age, resulting in lower plasma triglyceride levels and improved fat tolerance with age. Although a chronic diet high in omega-3 fatty acids increased insulin sensitivity and triglyceride uptake specifically into the heart, how these observations are connected is unclear.

Obesity is becoming a global pandemic with pandemic proportions. According to the WHO estimates, there were over 1.9 billion overweight individuals and over 650 million obese adults in the globe in 2016. In recent years, scientists have encountered difficulties in choosing acceptable animal models, leading to a multitude of contradicting aspects and incorrect outcomes. This review comprehensively evaluates different screening models of obesity and obesity-associated comorbidities to reveal the advantages and disadvantages/limitations of each model while also mentioning the time duration each model requires to induce obesity.

For this review, the authors have gone through a vast number of article sources from different scientific databases, such as Google Scholar, Web of Science, Medline, and PubMed.

In-vivo models used to represent a variety of obesity-inducing processes, such as diet-induced, drug-induced, surgical, chemical, stress-induced, and genetic models, are discussed. Animal cell models are examined with an emphasis on their use in understanding the molecular causes of obesity, for which we discussed in depth the important cell lines, including 3T3-L1, OP9, 3T3-F442A, and C3H10T1/2. Screening models of obesity-associated co-morbidities like diabetes, asthma, cardiovascular disorders, cancer, and polycystic ovarian syndrome (PCOS) were discussed, which provided light on the complex interactions between obesity and numerous health problems.

Mimicking obesity in an animal model reflects multifactorial aspects is a matter of challenge. Future studies could address the ethical issues surrounding the use of animals in obesity research as well as investigate newly developed models, such as non-mammalian models. In conclusion, improving our knowledge and management of obesity and related health problems will require ongoing assessment and improvement of study models.

Background/Objectives: There is controversy about the health risks of sugary diets. A recent study reported that chronic consumption of 11% sugar solutions improved glycemic control in lean mice. Based on this finding, we hypothesized that chronic consumption of the same 11% sugar solutions would also improve glycemic control in metabolically deranged mice. Methods: We exposed mice to a high-fat/high-sugar diet for 12 weeks. Then, we switched the mice to a control (i.e., standard chow) or one of four experimental diets for 8 weeks. The experimental diets contained standard chow plus an 11% solution of glucose or high-fructose syrup. The sugar syrups were derived from corn or cellulose. We included the cellulosic syrups because they contain polyphenols, which are thought to promote glycemic control. We measured body weight, adiposity, glucose tolerance, insulinemia, insulin sensitivity, body composition, and avidity for sweeteners. Results: Mice switched to the control diet lost weight, whereas mice switched to the experimental diets remained obese and hyperinsulinemic. Thus, the experimental diets did not cause the mice to regain normal metabolic health. Nevertheless, we observed (i) improvements in glucose tolerance in mice on both the control and experimental diets; (ii) reduced insulinemia and enhanced insulin sensitivity in mice offered the cellulosic syrups; (iii) elevations in cephalic-phase insulin responses in mice on the experimental diets; and (iv) increased avidity for sweeteners in mice on the control but not the experimental diets. Conclusions: Switching metabolically deranged mice to the experimental diets, particularly those with cellulosic sugars, improved glucose tolerance and insulin sensitivity.

Obesity is characterized by an imbalance between energy intake and expenditure that triggers abnormal growth of adipose tissues. Dimethyl fumarate (DMF) and its primary active metabolite, monomethyl fumarate (MMF), are Nrf2 activators and have been recognized as strategic antioxidants. This study aimed to evaluate the potential of MMF and DMF to interfere with adipogenesis and obesity, and identify the molecular mechanisms involved. The 3T3-L1 preadipocytes were incubated with differentiation medium (MIX) and simultaneously treated with different concentrations of MMF. In addition, male C57BL/6 mice were fed a standard diet or high-fat/high-sucrose diet (HFHSD) for 16 weeks, during the last 4 of which, they received oral DMF treatment. Exposure to MMF prevented the development of MIX-induced adipogenesis by reducing the expression of transcription factors that drive adipocyte differentiation and by decreasing triglyceride levels. In addition, various antioxidant and anti-inflammatory effects were observed after treatment with MMF as evidenced by the modulation of transcription factor activities and reduction in reactive oxygen species, adipokine, proinflammatory cytokine and resistin levels. In vivo treatment with DMF reduced calorie intake, body weight, and visceral and subcutaneous fat mass in HFHSD mice. Furthermore, DMF administration led to a better glycemic response as well as lower leptin and adiponectin plasma levels in these animals. Our data demonstrate that DMF and its metabolite MMF interfere with adipogenesis and prevent the key features of diet-induced obesity. Considering DMF is already a commercial drug used to treat psoriasis and multiple sclerosis, its pharmacological application for the treatment of obesity and related metabolic disorders holds promise.

Type 2 diabetes (T2D) pathophysiology involves insulin resistance (IR) and inadequate insulin secretion. Current T2D management includes dietary adjustments and/or oral medications such as thiazolidinediones (TZDs). Carrots have shown to contain bioactive acetylenic oxylipins that are partial agonists of the peroxisome proliferator-activated receptor γ (Pparg) that mimic the antidiabetic effect of TZDs without any adverse effects. TZDs exert hypoglycemic effects through activation of Pparg and through the regulation of the gut microbiota (GM) producing short-chain fatty acids (SCFAs), which impact glucose and energy homeostasis, promote intestinal gluconeogenesis, and influence insulin signaling pathways. This study investigated the metabolic effects of carrot intake in a T2D mouse model, elucidating underlying mechanisms. Mice were fed a low-fat diet (LFD), high-fat diet (HFD), or adjusted HFD supplemented with 10% carrot powder for 16 weeks. Oral glucose tolerance tests were conducted at weeks 0 and 16. Fecal, cecum, and colon samples, as well as tissue samples, were collected at week 16 during the autopsy. Results showed improved oral glucose tolerance in the HFD carrot group compared to HFD alone after 16 weeks. GM analysis demonstrated increased diversity and compositional changes in the cecum of mice fed HFD with carrot relative to HFD. These findings suggest the potential effect of carrots in T2D management, possibly through modulation of GM. Gene expression analysis revealed no significant alterations in adipose or muscle tissue between diet groups. Further research into carrot-derived bioactive compounds and their mechanisms of action is warranted for developing effective dietary strategies against T2D.

Animal models are an important tool for studying noncommunicable diseases (NCDs) as they provide a unique opportunity to investigate real-time changes that occur in the onset of, and during, the diseased state. This is of particular importance given that the global prevalence of NCDs, such as type 2 diabetes mellitus (T2DM), is rising at an alarming rate. In South Africa, which has one of the highest levels of HIV in the world, the incidence of T2DM is thought to be associated, in part, with exposure to combination antiretrovirals. We report on the establishment of both nonobese and obese zebrafish models of T2DM, as well as associated changes in mRNA expression of preproinsulin and phosphoenolpyruvate carboxykinase (pck) 1 and 2. The diabetic state was achieved by either immersing adult zebrafish in a 2% glucose solution for 40 days or by overfeeding adult zebrafish for 10 weeks. Glucose immersion resulted in significantly elevated fasting blood glucose levels twice as high as control, whereas bodyweight did not change significantly (nonobese model). Overfeeding led to both significantly elevated fasting blood glucose and bodyweight compared with control (obese model). Both models were characterized by significantly increased preproinsulin mRNA expression indicating insulin resistance; mRNA expression of metabolic enzymes PCK 1 and 2 was also significantly upregulated, as seen in diabetic patients. These candidate gene expression changes, similar in both zebrafish models, establish a baseline that can be utilized to investigate the underlying mechanisms driving the increased T2DM incidence, using an excellent alternative to traditional rodent models.

The transient postnatal increase in circulating leptin levels, known as leptin surge, may increase later susceptibility to diet-induced obesity in rodents. However, the source of leptin during the surge needs to be better characterized, and the long-term effects of leptin are contradictory. Characterization of the interaction of leptin with the genetic background, sex, and other factors is required. Here, we focused on the impact of circulating leptin levels and several related variables, measured in 2- and 4-wk-old i) obesity-prone C57BL/6 (B6) and ii) obesity-resistant A/J mice. In total, 264 mice of both sexes were used. Posttranscriptionally controlled leptin secretion from subcutaneous white adipose tissue, the largest adipose tissue depot in mice pups, was the primary determinant of plasma leptin levels. When the animals were randomly assigned standard chow or high-fat diet (HFD) between 12 and 24 wk of age, the obesogenic effect of HFD feeding was observed in B6 but not A/J mice. Only leptin levels at 2 wk, i.e., close to the maximum in the postnatal leptin surge, correlated with both body weight (BW) trajectory throughout the life and adiposity of the 24-wk-old mice. Leptin surge explained 13 and 7% of the variance in BW and adiposity of B6 mice, and 9 and 35% of the variance in these parameters in A/J mice, with a minor role of sex. Our results prove the positive correlation between the leptin surge and adiposity in adulthood, reflecting the fundamental biological role of leptin. This role could be compromised in subjects with obesity.NEW & NOTEWORTHY The postnatal surge in circulating leptin levels in mice reflects particularly posttranscriptionally controlled release of this hormone from subcutaneous white adipose tissue. Leptinemia in 2-wk-old pups predicts both body weight and adiposity in adult mice fed a high-fat diet. The extent of these effects depends on genetically determined differences in propensity to obesity between C57BL/6 and A/J mice. The leptin effect on adiposity is compromised in the obesity-prone C57BL/6 mice.

This study investigates the differences in the heart response to an 8-week high-fat diet between young and aged mice. Isolated cardiomyocytes reveal a significant lower level in the lipid droplet-associated protein Plin5 in aged mice. High-fat diet, however, leads to an induction of Plin5 in aged mice and a low-response of lipid metabolism, whereas in cardiomyocytes from young animals the Plin5 level was largely unaffected by high-fat diet whereas several lipid metabolizing enzymes were induced. Therefore, the high-fat diet induced lipid droplet accumulation is more pronounced in cardiomyocytes isolated from aged animals.

Obesity, a growing global health concern, is closely linked to depression. However, the neural mechanism of association between obesity and depression remains poorly understood. In this study, neural-specific WFS1 deficiency exacerbates the vicious cycle of obesity and depression in mice fed a high-fat diet (HFD), positioning WFS1 as a crucial factor in this cycle. Through human pluripotent stem cells (hESCs) neural differentiation, it is demonstrated that WFS1 regulates Zn2+ homeostasis and the apoptosis of neural progenitor cells (NPCs) and cerebral organoids by inhibiting the zinc transporter ZnT3 under the situation of dysregulated lipid metabolism. Notably, riluzole regulates ZnT3 expression to maintain zinc homeostasis and protect NPCs from lipotoxicity-induced cell death. Importantly, riluzole, a therapeutic molecule targeting the nervous system, in vivo administration prevents HFD-induced obesity and associated depression. Thus, a WFS1-ZnT3-Zn2+ axis critical is demonstrated for the vicious cycle of obesity and depression and that riluzole may have the potential to reverse this process against obesity and depression.

Significance: Dimeric nicotinamide nucleotide transhydrogenase (NNT) is embedded in the mitochondrial inner membrane and couples the conversion of NADP+/NADH into NADPH/NAD+ to mitochondrial matrix proton influx. NNT was implied in various cancers, but its physiological role and regulation still remain incompletely understood. Recent Advances: NNT function was analyzed by studying: (1) NNT gene mutations in human (adrenal) glucocorticoid deficiency 4 (GCCD4), (2) Nnt gene mutation in C57BL/6J mice, and (3) the effect of NNT knockdown/overexpression in (cancer) cells. In these three models, altered NNT function induced both common and differential aberrations. Critical Issues: Information on NNT protein expression in GCCD4 patients is still scarce. Moreover, NNT expression levels are tissue-specific in humans and mice and the functional consequences of NNT deficiency strongly depend on experimental conditions. In addition, data from intact cells and isolated mitochondria are often unsuited for direct comparison. This prevents a proper understanding of NNT-linked (patho)physiology in GCCD4 patients, C57BL/6J mice, and cancer (cell) models, which complicates translational comparison. Future Directions: Development of mice with conditional NNT deletion, cell-reprogramming-based adrenal (organoid) models harboring specific NNT mutations, and/or NNT-specific chemical inhibitors/activators would be useful. Moreover, live-cell analysis of NNT substrate levels and mitochondrial/cellular functioning with fluorescent reporter molecules might provide novel insights into the conditions under which NNT is active and how this activity links to other metabolic and signaling pathways. This would also allow a better dissection of local signaling and/or compartment-specific (i.e., mitochondrial matrix, cytosol, nucleus) effects of NNT (dys)function in a cellular context. Antioxid. Redox Signal. 41, 927-956.

Leukotrienes are potent mediators of the inflammatory response and 5-lipoxygenase, the enzyme responsible for their synthesis, is dependent on its interaction with 5-lipoxygenase activating protein for optimum catalysis. Previous studies had demonstrated that macrophage infiltration into adipose tissue is associated with obesity and atherosclerosis in LDLR-/- mice fed a high fat-high carbohydrate. The present study was undertaken to determine whether inhibition of 5-lipoxygenase activating protein is efficacious in attenuating adipose tissue inflammation in LDLR-/- mice fed a high fat-high carbohydrate. 10-week old male LDLR-/- mice were fed a high fat-high carbohydrate diet for 22-weeks, with or without MK886 (40 mg/kg/day, ad libitum) a well-established 5-lipoxygenase activating protein inhibitor. All mice had an approximate 2-fold increase in total body weight, but a 6-week course of MK886 treatment had differential effects on adipose tissue size, without affecting macrophage accumulation. MK886 exacerbated the dyslipidemia, increased serum amyloid A content of high-density lipoproteins and caused a profound hepatomegaly. Dyslipidemia and increased serum amyloid A were concomitant with increases in atherosclerosis. In conclusion, MK886 paradoxically exacerbated hyperlipidemia and the pro-inflammatory phenotype in a mouse model of diet-induced atherosclerosis, possibly via a disruption of hepatic lipid metabolism and increased inflammation.

Metabolic dysfunction-associated steatotic liver disease (MASLD) has recently been proposed as an alternative term to NAFLD. MASLD is a globally recognized chronic liver disease that poses significant health concerns and is frequently associated with obesity, insulin resistance, and hyperlipidemia. To better understand its pathogenesis and to develop effective treatments, it is essential to establish suitable animal models. Therefore, attempts have been made to establish modelling approaches that are highly similar to human diet, physiology, and pathology to better replicate disease progression. Here, we reviewed the pathogenesis of MASLD disease and summarised the used animal models of MASLD in the last 7 years through the PubMed database. In addition, we have summarised the commonly used animal models of MASLD and describe the advantages and disadvantages of various models of MASLD induction, including genetic models, diet, and chemically induced models, to provide directions for research on the pathogenesis and treatment of MASLD.

Weight gain variation is a great challenge in diet-induced obesity studies since low-gainer animals are of limited experimental value. The inbred C57BL/6 (B6) mice are frequently used models due to their genetic homogeneity and susceptibility to diet-induced obesity (DIO). The aim of this study is to investigate if the gut microbiota (GM) influences the fraction of low weight gainers in DIO studies. A total of 100 male B6 mice (donor population) were fed a high-fat diet for 14 weeks and divided into the study groups high gainer (HG) and low gainer (LG) based on their weight gain. Subsequently, fecal matter transplantation (FMT) was done on germ-free B6 mice with GM from HG and LG donors (FMT population). LG (13.35 ± 2.5 g) and HG (25.52 ± 2.0 g) animals were identified by the weight gain from week 1 to week 12. Interestingly, the start weight of the LG (20.36 ± 1.4 g) and HG (21.59 ± 0.7 g) groups differed significantly. Transplanting LG or HG fecal matter to germ-free mice resulted in significant differences in weight gain between HG and LG, as well as differences in serum leptin levels and epididymal fat pad weight. A clear LG-specific GM composition could not be distinguished by 16S rRNA gene amplicon sequencing. Surprisingly, significantly more fighting was recorded in LG groups of both donor populations and when transplanted to germ-free mice. The HG and LG phenotypes could be transferred to germ-free mice. The increased fighting in the LG group in both studies suggests not only that the tendency to fight can be transferred by FMT in these mice, but also that fighting should be prevented in DIO studies to minimize the number of LG animals.

We here assessed whether typical pathogens of laboratory mice affect the development of diet-induced obesity and glucose intolerance, and whether colonization affects the efficacy of the GLP-1R agonist liraglutide and of the GLP-1/GIP co-agonist MAR709 to treat obesity and diabetes.

Male C57BL/6J mice were experimentally infected with Helicobacter hepaticus, Rodentibacter pneumotropicus and Staphylococcus aureus and compared to a group of uninfected specific and opportunistic pathogen free (SOPF) mice. The development of diet-induced obesity and glucose intolerance was monitored over a period of 26 weeks. To study the influence of pathogens on drug treatment, mice were then subjected for 6 days daily treatment with either the GLP-1 receptor agonist liraglutide or the GLP-1/GIP co-agonist MAR709.

Colonized mice did not differ from SOPF controls regarding HFD-induced body weight gain, food intake, body composition, glycemic control, or responsiveness to treatment with liraglutide or the GLP-1/GIP co-agonist MAR709.

We conclude that the occurrence of H. hepaticus, R. pneumotropicus and S. aureus does neither affect the development of diet-induced obesity or type 2 diabetes, nor the efficacy of GLP-1-based drugs to decrease body weight and to improve glucose control in mice.

Considering detrimental impacts of combustible cigarettes (CCs) on the exacerbation of diabetes mellitus (DM), a significant number of DM patients have substituted CCs with electronic nicotine delivery systems (ENDS). Herewith, we compared CCs and ENDS-dependent modulation of immune cell-driven inflammation in DM patients who used ENDS (DMENDS), CCs (DMCC) or were non-smokers (DMAIR), paving the way for the better understanding of ENDS-induced biological effects. Multiple low dose streptozotocin (MLD-STZ)-induced mice model of DM was used to support clinical findings. Both CCs and ENDS aggravated MLD-STZ-induced DM. Pancreatic injury and inflammation were more severe in CC-exposed than in ENDS-exposed diabetic mice. CCs promoted activation of NLRP3 inflammasome, enhanced production of inflammatory cytokines in neutrophils, macrophages and remarkably improved antigen presenting capacity of dendritic cells which resulted in the expansion of TNF-α, IFN-γ and IL-17-producing Th1 and Th17 lymphocytes, NK and NKT cells. Compared to CCs, ENDS more intensively promoted expansion of FoxP3-expressing, IL-10-producing NK and NKT cells and triggered less intense systemic inflammatory response in diabetic animals. Similar findings were observed in DM patients. The highest numbers of inflammatory, TNF-α and IL-1β-producing neutrophils and monocytes, TNF-α and IFN-γ-producing T lymphocytes, NK and NKT cells were determined in the blood of DMCC patients, while total number of immunosuppressive, TGF-β-producing CD3 + CD4 + T cells was the highest in the blood of DMENDS patients. In conclusion, although both CC and ENDS aggravate on-going inflammation in DM, ENDS have weaker capacity to induce production of inflammatory cytokines in immune cells than CCs.

Restenosis following percutaneous revascularization is a major challenge in patients with insulin resistance and diabetes. Currently, the vascular effects of insulin are not fully understood. In vitro, insulin's effects on endothelial cells (ECs) are beneficial, whereas on vascular smooth muscle cells (SMCs), they are mitogenic. We previously demonstrated a suppressive effect of insulin on neointimal growth under insulin-sensitive conditions that was abolished in insulin-resistant conditions. Here, we aimed to determine the cell-specific effects of insulin on neointimal growth in a model of restenosis under insulin-sensitive and insulin-resistant conditions. Vascular cell-specific insulin receptor (IR)-deficient mice were fed a low-fat diet (LFD) or a high-fat, high-sucrose diet (HFSD) and implanted with an insulin pellet or vehicle prior to femoral artery wire injury. In insulin-sensitive conditions, insulin decreased neointimal growth only in controls. However, under insulin-resistant conditions, insulin had no effect in either control, EC-specific or SMC-specific IR-deficient mice. These data demonstrate that EC and SMC IRs are required for the anti-restenotic effect of insulin in insulin-sensitive conditions and that, in insulin resistance, insulin has no adverse effect on vascular SMCs in vivo.

Weight loss can improve the metabolic complications of obesity. However, it is unclear whether insulin resistance persists despite weight loss and whether any protective benefits are preserved following weight regain (weight cycling). The impact of genetic background on weight cycling is undocumented. We aimed to investigate the effects of weight loss and weight cycling on metabolic outcomes and sought to clarify the role of genetics in this relationship.

Both C57BL/6 J and genetically heterogeneous Diversity Outbred Australia (DOz) mice were alternately fed high fat Western-style diet (WD) and a chow diet at 8-week intervals. Metabolic measures including body composition, glucose tolerance, pancreatic beta cell activity, liver lipid levels and adipose tissue insulin sensitivity were determined.

After diet switch from WD (8-week) to chow (8-week), C57BL/6 J mice displayed a rapid normalisation of body weight, adiposity, hyperinsulinemia, liver lipid levels and glucose uptake into adipose tissue comparable to chow-fed controls. In response to the same dietary intervention, genetically diverse DOz mice conversely maintained significantly higher fat mass and insulin levels compared to chow-fed controls and exhibited much more profound interindividual variability than C57BL/6 J mice. Weight cycled (WC) animals were re-exposed to WD (8-week) and compared to age-matched controls fed 8-week WD for the first time (LOb). In C57BL/6 J but not DOz mice, WC animals had significantly higher blood insulin levels than LOb controls. All WC animals exhibited significantly greater beta cell activity than LOb controls despite similar fat mass, glucose tolerance, liver lipid levels and insulin-stimulated glucose uptake in adipose tissue.

Following weight loss, metabolic outcomes return to baseline in C57BL/6 J mice with obesity. However, genetic diversity significantly impacts this response. A period of weight loss does not provide lasting benefits after weight regain, and weight cycling is detrimental and associated with hyperinsulinemia and elevated basal insulin secretion.

Peripheral neuropathy (PN) is a multifaceted disorder characterised by peripheral nerve damage, manifesting in symptoms like pain, weakness, and autonomic dysfunction. This review assesses preclinical models in PN research, evaluating their relevance to human disease and their role in therapeutic development. The Streptozotocin (STZ)-induced diabetic rat model is widely used to simulate diabetic neuropathy but has limitations in faithfully replicating disease onset and progression. Cisplatin-induced PN models are suitable for studying chemotherapy-induced peripheral neuropathy (CIPN) and closely resemble human pathology. However, they may not fully replicate the spectrum of sensory and motor deficits. Paclitaxel-induced models also contribute to understanding CIPN mechanisms and testing neuroprotective agents. Surgical or trauma-induced models offer insights into nerve regeneration and repair strategies. Medications such as gabapentin, pregabalin, duloxetine, and fluoxetine have demonstrated promise in these models, enhancing our understanding of their therapeutic efficacy. Despite progress, developing models that accurately mirror human PN remains imperative due to its complex nature. Continuous refinement and innovative approaches are critical for effective drug discovery. This review underscores the strengths and limitations of current models and advocates for an integrated approach to address the complexities of PN better and optimise treatment outcomes.

Both age and diet can contribute to alterations in triglyceride metabolism and subsequent metabolic disease. In humans, plasma triglyceride levels increase with age. Diets high in saturated fats can increase triglyceride levels while diets high in omega-3 fatty acids decrease triglyceride levels. Here we asked how age and long-term diet effected triglyceride metabolism in mice.

We fed male and female mice a low-fat diet, a western diet, or a diet high in polyunsaturated and omega-3 (n-3) fatty acids for up to 2 years. We measured survival, body composition, plasma triglyceride levels, chylomicron clearance, and oral fat, glucose, and insulin tolerance.

Triglyceride levels in mice did not increase with age, regardless of diet. Oral fat tolerance increased with age, while chylomicron clearance remained unchanged. Mice fed western diet had decreased survival. Interestingly, mice fed the n-3 diet gained more lean mass, and had lower insulin levels than mice fed either low-fat or western diet. Moreover, triglyceride uptake into the hearts of mice fed the n-3 diet was strikingly higher than in other groups.

In mice, age-induced changes in triglyceride metabolism did not match those in humans. Our data suggested that mice, like humans, had decreased fat absorption with age, but plasma triglyceride clearance did not decrease with age in mice, resulting in lower plasma triglyceride levels and improved oral fat tolerance with age. A chronic diet high in n-3 fatty acids increased insulin sensitivity and uptake of triglycerides specifically into the heart but how these observations are connected is unclear.

Scientific evidence highlights the influence of biological sex on the relationship between stress and metabolic dysfunctions. However, there is limited understanding of how diet and stress concurrently contribute to metabolic dysregulation in both males and females. Our study aimed to investigate the combined effects of high-fat diet (HFD) induced obesity and repeated stress on fear-related behaviors, metabolic, immune, and hypothalamic outcomes in male and female mice.

To investigate this, we used a highly reliable rodent behavioral model that faithfully recapitulates key aspects of post-traumatic stress disorder (PTSD)-like fear. We subjected mice to footshock stressor followed by a weekly singular footshock stressor or no stressor for 14 weeks while on either an HFD or chow diet. At weeks 10 and 14 we conducted glucose tolerance and insulin sensitivity measurements. Additionally, we placed the mice in metabolic chambers to perform indirect calorimetric measurements. Finally, we collected brain and peripheral tissues for cellular analysis.

We observed that HFD-induced obesity disrupted fear memory extinction, increased glucose intolerance, and affected energy expenditure specifically in male mice. Conversely, female mice on HFD exhibited reduced respiratory exchange ratio (RER), and a significant defect in glucose tolerance only when subjected to repeated stress. Furthermore, the combination of repeated stress and HFD led to sex-specific alterations in proinflammatory markers and hematopoietic stem cells across various peripheral metabolic tissues. Single-nuclei RNA sequencing (snRNAseq) analysis of the ventromedial hypothalamus (VMH) revealed microglial activation in female mice on HFD, while male mice on HFD exhibited astrocytic activation under repeated stress.

Overall, our findings provide insights into complex interplay between repeated stress, high-fat diet regimen, and their cumulative effects on health, including their potential contribution to the development of PTSD-like stress and metabolic dysfunctions, emphasizing the need for further research to fully understand these interconnected pathways and their implications for health.

Atherosclerosis is the major underlying pathology of cardiovascular disease and is driven by dyslipidemia and inflammation. Inhibition of the immunoproteasome, a proteasome variant that is predominantly expressed by immune cells and plays an important role in antigen presentation, has been shown to have immunosuppressive effects.

We assessed the effect of ONX-0914, an inhibitor of the immunoproteasomal catalytic subunits LMP7 (proteasome subunit β5i/large multifunctional peptidase 7) and LMP2 (proteasome subunit β1i/large multifunctional peptidase 2), on atherosclerosis and metabolism in LDLr-/- and APOE*3-Leiden.CETP mice.

ONX-0914 treatment significantly reduced atherosclerosis, reduced dendritic cell and macrophage levels and their activation, as well as the levels of antigen-experienced T cells during early plaque formation, and Th1 cells in advanced atherosclerosis in young and aged mice in various immune compartments. Additionally, ONX-0914 treatment led to a strong reduction in white adipose tissue mass and adipocyte progenitors, which coincided with neutrophil and macrophage accumulation in white adipose tissue. ONX-0914 reduced intestinal triglyceride uptake and gastric emptying, likely contributing to the reduction in white adipose tissue mass, as ONX-0914 did not increase energy expenditure or reduce total food intake. Concomitant with the reduction in white adipose tissue mass upon ONX-0914 treatment, we observed improvements in markers of metabolic syndrome, including lowered plasma triglyceride levels, insulin levels, and fasting blood glucose.

We propose that immunoproteasomal inhibition reduces 3 major causes underlying cardiovascular disease, dyslipidemia, metabolic syndrome, and inflammation and is a new target in drug development for atherosclerosis treatment.

The obesity epidemic continues to increase, with half of US women predicted to be obese by 2030. Women with obesity are at increased risk for not only cardiovascular and liver disease, but also reproductive disorders. Although mouse models are useful in studying the effects of obesity, there is inconsistency in obesity-induction methods, diet composition, and mouse strains, and studies using female mice are limited. In this study, we sought to compare the effects of a 45% high-fat diet (HFD) versus a 60% HFD on the uterine estrous cycle of nulligravid C57BL/6J mice. For 22 weeks, we placed a total of 20 mice on either a 60% HFD, 45% HFD, or each HFD-matched control diet (CD). Both HFDs produced significant weight gain, with 60% HFD and 45% HFD gaining significant weight after 2 weeks and 15 weeks, respectively. Additionally, both HFDs led to glucose intolerance, fatty liver, and adipocyte hypertrophy. Mice fed 60% HFD displayed hyperphagia in the first 12 weeks of HFD treatment. Moreover, 60% HFD-treated mice had a longer estrous cycle length and an increased percentage of estrus stage samplings compared to CD-treated mice. Estrous cycle stage-controlled 60% HFD-treated mice displayed an increased estrogen-to-progesterone ratio and decreased ovarian corpora lutea compared to CD-treated mice, which may underlie the observed estrous cycle differences. There was no significant difference between diets regarding endometrial morphology or the percent of endometrial CD45+ immune cells. Our results indicate that consideration is needed when selecting a HFD-induced obesity mouse model for research involving female reproductive health.

Mouse models of diet-induced type 2 diabetes mellitus provide powerful tools for studying the structural and physiological changes that are related to the disease progression. In this study, diabetic-like glucose dysregulation was induced in mice by feeding them a western diet, and light and transmission electron microscopy were used to study the ultrastructural changes in the pancreatic acinar cells. Acinar necrosis and vacuolization of the cytoplasm were the most prominent features. Furthermore, we observed intracellular and extracellular accumulation of lipid compounds in the form of lipid droplets, structural enlargement of the cisternae of the rough endoplasmic reticulum (RER), and altered mitochondrial morphology, with mitochondria lacking the typical organization of the inner membrane. Last, autophagic structures, i.e., autophagosomes, autolysosomes, and residual bodies, were abundant within the acinar cells of western diet-fed mice, and the autolysosomes contained lipids and material of varying electron density. While diets inducing obesity and type 2 diabetes are clearly associated with structural changes and dysfunction of the endocrine pancreas, we here demonstrate the strong effect of dietary intervention on the structure of acinar cells in the exocrine part of the organ before detectable changes in plasma amylase activity, which may help us better understand the development of non-alcoholic fatty pancreas disease and its association with endo- and exocrine dysfunction.

Genome-wide studies have identified three missense variants in the human gene ACVR1C, encoding the TGF-β superfamily receptor ALK7, that correlate with altered waist-to-hip ratio adjusted for body mass index (WHR/BMI), a measure of body fat distribution.

To move from correlation to causation and understand the effects of these variants on fat accumulation and adipose tissue function, we introduced each of the variants in the mouse Acvr1c locus and investigated metabolic phenotypes in comparison with a null mutation.

Mice carrying the I195T variant showed resistance to high fat diet (HFD)-induced obesity, increased catecholamine-induced adipose tissue lipolysis and impaired ALK7 signaling, phenocopying the null mutants. Mice with the I482V variant displayed an intermediate phenotype, with partial resistance to HFD-induced obesity, reduction in subcutaneous, but not visceral, fat mass, decreased systemic lipolysis and reduced ALK7 signaling. Surprisingly, mice carrying the N150H variant were metabolically indistinguishable from wild type under HFD, although ALK7 signaling was reduced at low ligand concentrations.

Together, these results validate ALK7 as an attractive drug target in human obesity and suggest a lower threshold for ALK7 function in humans compared to mice.

By exposing mice carrying a deletion of NADPH oxidase isoform 4, NOX4, specifically in pancreatic β cells (βNOX4-/-) to nutrient excess stimulated by a high-fat diet (HFD), this study aimed to elucidate the role of β-cell redox status in the development of meta-inflammation within the diabetic phenotype.

The authors performed basic phenotyping of βNOX4-/- mice on HFD involving insulin and glycemic analyses, histochemistry of adipocytes, indirect calorimetry, and cytokine analyses. To characterize local inflammation, the study used caspase-1 activity assay, interleukin-1β immunochemistry, and real-time polymerase chain reaction during coculturing of β cells with macrophages.

The phenotype of βNOX4-/- mice on HFD was not associated with hyperinsulinemia and hyperglycemia but showed accumulation of excessive lipids in epididymal fat and β cells. Surprisingly, mice showed significantly reduced systemic inflammation. Decreased interleukin-1β protein levels and downregulated NLRP3-inflammasome activity were observed on chronic glucose overload in βNOX4-/- isolated islets and NOX4-silenced INS1-E cells resulting in attenuated proinflammatory polarization of macrophages/monocytes in vitro and in situ and reduced local islet inflammation.

Experimental evidence suggests that NOX4 pro-oxidant activity in β cells is involved in NLRP3-inflammasome activation during chronic nutrient overload and participates in local inflammatory signaling and perhaps toward peripheral tissues, contributing to a diabetic inflammatory phenotype.

Intermittent hypoxia intervention (IHI) has been shown to reduces blood glucose and improves insulin resistance in type 2 diabetes (T2D) and has been suggested as a complementary or alternative intervention to exercise for individuals with limited mobility. Previous research on IHI has assessed cellular glucose uptake rather than utilization. The purpose of this study was to determine the effect of a 4-week IHI, with or without an aerobic exercise, on skeletal muscle glucose utilization as indicated by the changes in pyruvate, lactate, NAD+, and NADH, using a mouse model of diet-induced T2D. In addition, the effects of one exposure to hypoxia (acute) and of a 4-week IHI (chronic) were compared to explore their relationship.

C57BL/6J mice were randomly assigned to normal control and high-fat-diet groups, and the mice that developed diet-induced diabetes were assigned to diabetes control, and intervention groups with 1 hour (acute) or 4 weeks (1 hour/day, 6 days/week) exposure to a hypoxic envrionment (0.15 FiO2), exercise (treadmill run) in normoxia, and exercise in hypoxia, respectively, with N = 7 in each group. The effects of the interventions on concentrations of fasting blood glucose, muscle glucose, GLUT4, lactate, pyruvate, nicotinamide adenine dinucleotide (NAD+), and NADH were measured, and statistically compared between the groups.

Compared with diabetes control group, the mice treated in the hypoxic environment for 4 weeks showed a significantly higher pyruvate levels and lower lactate/pyruvate ratios in the quadriceps muscle, and the mice exposed to hypoxia without or with aerobic exercise for either for 4 weeks or just 1 hour showed higher NAD+ levels and lower NADH/NAD+ ratios.

Exposure to moderate hypoxia for either one bout or 4 weeks significantly increased the body's mitochondrial NAD cyclethe in diabetic mice even in the absence of aerobic exercise. The hypoxia and exercise interventions exhibited synergistic effects on glycolysis. These findings provide mechanistic insights into the effects of IHI in respect of the management of hyperglycemia.