Role of Janus Kinase 3 in Predisposition to Obesity-associated Metabolic Syndrome

Effects of Sesamin in Animal Models of Obesity-Associated Diseases: A Systematic Review and Meta-Analysis

CONTEXT

As living standards have improved and lifestyles have undergone changes, metabolic diseases associated with obesity have become increasingly prevalent. It is well established that sesamin (Ses) (PubChem CID: 72307), the primary lignans in sesame seeds and sesame oil, possess antioxidant and anti-inflammatory effects.

OBJECTIVE

In this study, a systematic review and meta-analysis of the effects of Ses on animal models of obesity-related diseases was performed to assess their impact on relevant disease parameters. Importantly, this study sought to provide insights for the design of future human clinical studies utilizing Ses as a nutritional supplement or drug.

DATA SOURCES

This study conducted a comprehensive search in PubMed, Web of Science, Embase, Scopus, and the Cochrane Library, identifying English language articles published from inception to April 2023.

DATA EXTRACTION

The search incorporated keywords such as "sesamin," "obesity," "non-alcoholic fatty liver disease," "type 2 diabetes mellitus," and "metabolic syndrome." The meta-analysis included 17 articles on non-alcoholic fatty liver disease, type 2 diabetes, and metabolic syndrome.

DATA ANALYSIS

Overall, the pooled results demonstrated that Ses significantly reduced levels of total serum cholesterol (P = .010), total serum triglycerides (P = .003), alanine transaminase (P = .003), and blood glucose (P < .001), and increased high-density lipoprotein cholesterol levels (P = .012) in animal models of nonalcoholic fatty liver disease. In the type 2 diabetes model, Ses mitigated drug-induced weight loss (P < .001), high-fat-diet-induced weight gain (P < .001), and blood glucose levels (P = .001). In the metabolic syndrome model, Ses was associated with a significant reduction in body weight (P < .001), total serum cholesterol (P < .001), total serum triglycerides (P < .001), blood glucose (P < .001), and alanine transaminase levels (P = .039).

CONCLUSION

The meta-analysis results of this study suggest that Ses supplementation yields favorable effects in animal models of obesity-related diseases, including hypolipidemic, insulin-lowering, and hypoglycemic abilities, as well as organ protection from oxidative stress and reduced inflammation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration No. CRD42023438502.

JAK-STAT signaling in inflammation and stress-related diseases: implications for therapeutic interventions

The Janus kinase-signal transducer and transcription activator pathway (JAK-STAT) serves as a cornerstone in cellular signaling, regulating physiological and pathological processes such as inflammation and stress. Dysregulation in this pathway can lead to severe immunodeficiencies and malignancies, and its role extends to neurotransduction and pro-inflammatory signaling mechanisms. Although JAK inhibitors (Jakinibs) have successfully treated immunological and inflammatory disorders, their application has generally been limited to diseases with similar pathogenic features. Despite the modest expression of JAK-STAT in the CNS, it is crucial for functions in the cortex, hippocampus, and cerebellum, making it relevant in conditions like Parkinson's disease and other neuroinflammatory disorders. Furthermore, the influence of the pathway on serotonin receptors and phospholipase C has implications for stress and mood disorders. This review expands the understanding of JAK-STAT, moving beyond traditional immunological contexts to explore its role in stress-related disorders and CNS function. Recent findings, such as the effectiveness of Jakinibs in chronic conditions such as rheumatoid arthritis, expand their therapeutic applicability. Advances in isoform-specific inhibitors, including filgotinib and upadacitinib, promise greater specificity with fewer off-target effects. Combination therapies, involving Jakinibs and monoclonal antibodies, aiming to enhance therapeutic specificity and efficacy also give great hope. Overall, this review bridges the gap between basic science and clinical application, elucidating the complex influence of the JAK-STAT pathway on human health and guiding future interventions.

JAK3/STAT5b/PPARγ Pathway Mediates the Association between Di(2-ethylhexyl) Phthalate Exposure and Lipid Metabolic Disorder in Chinese Adolescent Students

Our previous studies found that di (2-ethylhexyl) phthalate (DEHP) could disorder lipid metabolism in adolescents but the mechanisms underlying this association remained unclear. This study was undertaken to clarify the mediating effect of JAK3/STAT5/PPARγ on disorder lipid levels induced by DEHP in adolescents. We recruited 478 adolescent students (median age 18.1 years). The mRNA expression and DNA methylation levels of JAK3/STAT5/PPARγ were detected by real-time PCR and the MethylTarget, respectively. We used multiple linear regression to analyze the association between DEHP metabolites (MEHP, MEOHP, MEHHP, MECPP, MCMHP, and ΣDEHP) levels, mRNA expression, and DNA methylation levels. The mediating effect of JAK3/STAT5/PPARγ mRNA expression levels was examined by mediation analysis. We found that all DEHP metabolite levels were positively correlated with TC/HDL-C and LDL-C/HDL-C (P < 0.05). The MEOHP level was negatively associated with DNA methylation levels and positively associated with mRNA levels of PPARγ and STAT5b (P < 0.05). The MEHP level was negatively associated with the DNA methylation level and positively associated with the mRNA level of JAK3 (P < 0.05). Higher MEOHP was associated with a higher level of TC/HDL-C, the mediation analysis showed the mediation effect was 17.18% for the JAK3 level, 10.76% for the STAT5b level, and 11% for the PPARγ level. Higher MEHP was associated with a higher level of LDL-C/HDL-C, the mediation effect was 14.49% for the JAK3 level. In conclusion, DEHP metabolites decreased the DNA methylation levels, inducing the increase of the mRNA levels of JAK3/STAT5/PPARγ. In addition, the mRNA levels mediated the association between DEHP exposure and disorder lipid levels.

Molecular and Pathological Analyses of IARS1-Deficient Mice: An IARS Disorder Model

Most mitochondrial diseases are hereditary and highly heterogeneous. Cattle born with the V79L mutation in the isoleucyl-tRNA synthetase 1 (IARS1) protein exhibit weak calf syndrome. Recent human genomic studies about pediatric mitochondrial diseases also identified mutations in the IARS1 gene. Although severe prenatal-onset growth retardation and infantile hepatopathy have been reported in such patients, the relationship between IARS mutations and the symptoms is unknown. In this study, we generated hypomorphic IARS1^V79L mutant mice to develop an animal model of IARS mutation-related disorders. We found that compared to wild-type mice, IARS^V79L mutant mice showed a significant increase in hepatic triglyceride and serum ornithine carbamoyltransferase levels, indicating that IARS1^V79L mice suffer from mitochondrial hepatopathy. In addition, siRNA knockdown of the IARS1 gene decreased mitochondrial membrane potential and increased reactive oxygen species in the hepatocarcinoma-derived cell line HepG2. Furthermore, proteomic analysis revealed decreased levels of the mitochondrial function-associated protein NME4 (mitochondrial nucleoside diphosphate kinase). Concisely, our mutant mice model can be used to study IARS mutation-related disorders.

Gene expression associations with body mass index in the Multi-Ethnic Study of Atherosclerosis

BACKGROUND/OBJECTIVES

Obesity, defined as excessive fat accumulation that represents a health risk, is increasing in adults and children, reaching global epidemic proportions. Body mass index (BMI) correlates with body fat and future health risk, yet differs in prediction by fat distribution, across populations and by age. Nonetheless, few genetic studies of BMI have been conducted in ancestrally diverse populations. Gene expression association with BMI was assessed in the Multi-Ethnic Study of Atherosclerosis (MESA) in four self-identified race and ethnicity (SIRE) groups to identify genes associated with obesity.

SUBJECTS/METHODS

RNA-sequencing was performed on 1096 MESA participants (37.8% white, 24.3% Hispanic, 28.4% African American, and 9.5% Chinese American) and linear models were used to assess the association of expression from each gene for its effect on BMI, adjusting for age, sex, sequencing center, study site, five expression and four genetic principal components in each self-identified race group. Sample-size-weighted meta-analysis was performed to identify genes with BMI-associated expression across ancestry groups.

RESULTS

Within individual SIRE groups, there were zero to three genes whose expression is significantly (p < 1.97 × 10^-6) associated with BMI. Across all groups, 45 genes were identified by meta-analysis whose expression was significantly associated with BMI, explaining 29.7% of BMI variation. The 45 genes are expressed in a variety of tissues and cell types and are enriched for obesity-related processes including erythrocyte function, oxygen binding and transport, and JAK-STAT signaling.

CONCLUSIONS

We have identified genes whose expression is significantly associated with obesity in a multi-ethnic cohort. We have identified novel genes associated with BMI as well as confirmed previously identified genes from earlier genetic analyses. These novel genes and their biological pathways represent new targets for understanding the biology of obesity as well as new therapeutic intervention to reduce obesity and improve global public health.

Anti-Inflammatory Mechanisms of Dietary Flavones: Tapping into Nature to Control Chronic Inflammation in Obesity and Cancer

Flavones are natural phytochemicals broadly distributed in our diet. Their anti-inflammatory properties provide unique opportunities to control the innate immune system and inflammation. Here, we review the role of flavones in chronic inflammation with an emphasis on their impact on the molecular mechanisms underlying inflammatory diseases including obesity and cancer. Flavones can influence the innate immune cell repertoire restoring the immune landscape. Flavones impinge on NF-κB, STAT, COX-2, or NLRP3 inflammasome pathways reestablishing immune homeostasis. Devoid of adverse side effects, flavones could present alternative opportunities for the treatment and prevention of chronic inflammation that contributes to obesity and cancer.

Immunometabolism in the pathogenesis of vitiligo

Vitiligo is a common depigmenting skin disorder characterized by the selective loss of melanocytes. Autoimmunity, genetic, environmental, and biochemical etiology have been proposed in vitiligo pathogenesis. However, the exact molecular mechanisms of vitiligo development and progression are unclear, particularly for immunometabolism. Sporadic studies have suggested mitochondrial dysfunction, enhanced oxidative stress, and specific defects in other metabolic pathways can promote dysregulation of innate and adaptive immune responses in vitiligo. These abnormalities appear to be driven by genetic and epigenetic factors modulated by stochastic events. In addition, glucose and lipid abnormalities in metabolism have been associated with vitiligo. Specific skin cell populations are also involved in the critical role of dysregulation of metabolic pathways, including melanocytes, keratinocytes, and tissue-resident memory T cells in vitiligo pathogenesis. Novel therapeutic treatments are also raised based on the abnormalities of immunometabolism. This review summarizes the current knowledge on immunometabolism reprogramming in the pathogenesis of vitiligo and novel treatment options.

Mechanistic Role of Jak3 in Obesity-Associated Cognitive Impairments

Background and Aims: A compromise in intestinal mucosal functions is associated with several chronic inflammatory diseases. Previously, we reported that obese humans have a reduced expression of intestinal Janus kinase-3 (Jak3), a non-receptor tyrosine kinase, and a deficiency of Jak3 in mice led to predisposition to obesity-associated metabolic syndrome. Since meta-analyses show cognitive impairment as co-morbidity of obesity, the present study demonstrates the mechanistic role of Jak3 in obesity associated cognitive impairment. Our data show that high-fat diet (HFD) suppresses Jak3 expression both in intestinal mucosa and in the brain of wild-type mice. Methodology: Recapitulating these conditions using global (Jak3-KO) and intestinal epithelial cell-specific conditional (IEC-Jak3-KO) mice and using cognitive testing, western analysis, flow cytometry, immunofluorescence microscopy and 16s rRNA sequencing, we demonstrate that HFD-induced Jak3 deficiency is responsible for cognitive impairments in mice, and these are, in part, specifically due to intestinal epithelial deficiency of Jak3. Results: We reveal that Jak3 deficiency leads to gut dysbiosis, compromised TREM-2-functions-mediated activation of microglial cells, increased TLR-4 expression and HIF1-α-mediated inflammation in the brain. Together, these lead to compromised microglial-functions-mediated increased deposition of β-amyloid (Aβ) and hyperphosphorylated Tau (pTau), which are responsible for cognitive impairments. Collectively, these data illustrate how the drivers of obesity promote cognitive impairment and demonstrate the underlying mechanism where HFD-mediated impact on IEC-Jak3 deficiency is responsible for Jak3 deficiency in the brain, reduced microglial TREM2 expression, microglial activation and compromised clearance of Aβ and pTau as the mechanism during obesity-associated cognitive impairments. Conclusion: Thus, we not only demonstrate the mechanism of obesity-associated cognitive impairments but also characterize the tissue-specific role of Jak3 in such conditions through mucosal tolerance, gut–brain axis and regulation of microglial functions.

Alleviation of Fufang Fanshiliu decoction on type II diabetes mellitus by reducing insulin resistance: A comprehensive network prediction and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Fufang Fanshiliu decoction (FFSLD) is a Chinese herbal medicine prescription that has been used in type 2 diabetes mellitus (T2DM), while the underlying mechanism remains unclear.

AIM OF THE STUDY

To validate the efficacy and explore the potential mechanisms of FFSLD in treating T2DM via integrating a network pharmacological approach and experimental evaluation.

MATERIALS AND METHODS

T2DM mice model induced by high-fat diet feeding combined with streptozotocin injection was selected to investigate the alleviation of FFSLD against T2DM, via detecting the levels of glucose, insulin, glucagon (GC), triglyceride (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). Network pharmacological analysis was used to predict the potential mechanisms, including the pharmacokinetics and drug-likeness screening, active ingredients and potential targets prediction, network analysis, and enrichment analysis. The candidate bioactive molecules of FFSLD, and targets information excavated through TCMSP, Uniprot, GeneCards, OMIM databases, were combined for comprehensive analysis by constructing "drug-compound-target-disease" and "protein-protein interaction" networks. Enrichment analysis was performed via Gene Ontology (GO) and Koto Encyclopedia of Genes and Genomes (KEGG) databases. HepG2 insulin-resistance (IR) cells model induced by high glucose was used to verify the potential mechanisms of FFSLD against T2DM which were predicted by the network pharmacology.

RESULTS

The animal study showed that FFSLD significantly decreased the blood glucose, and reversed the abnormal levels of insulin, GC, TG, TC, HDL-C, and LDL-C in T2DM mice. Network pharmacological analysis indicated that 106 active compounds of FFSLD might be correlated with 628 targets in treating T2DM, and the mechanism would probably be related to insulin resistance that harbored a high response value (P = 5.88844 E^-33) though regulating Akt1, ESR1, oxidoreductase activity, and JAK/STAT signalings. Experimental validation showed that FFSLD reduced the ROS level, up-regulated the expressions of p-AKT, Nrf-2, and ESR1, and down-regulated the expressions of JAK2, STAT3, and Keap-1 in the HepG2-IR cells model.

CONCLUSIONS

This study demonstrated that the therapeutic effect of FFSLD on T2DM was related to IR alleviation. The underlying mechanisms were associated with the regulation of PI3K/AKT, JAK/STAT, oxidative stress, and ESR signaling pathways.

A novel immune-related genes signature after bariatric surgery is histologically associated with non-alcoholic fatty liver disease

Increasing evidence shows that immune-related genes (IRGs) play an important role in bariatric surgery (BS). We identified differentially expressed immune-related genes (DEIRGs) of adipose tissue after BS by analysing the two expression profiles of GEO (GSE59034 and GSE29409). Subsequently, enrichment analysis, GSEA and PPI networks were examined to identify the hub IRGs and related pathways. The performance of the signature was evaluated by area under the curve (AUC) of the receiver operating characteristic (ROC). CIBERSORT algorithm was used to evaluate the relative abundance of infiltrated immune cells.42 DEIRGs were found between the GSE59034 and GSE29409 datasets. The AUC of the signature was 0.904 and 0.865 in the GSE58979 and GSE48452, respectively. Interestingly, the signature also showed good performance in diagnosing non-alcoholic fatty liver disease (NAFLD) (AUC was 0.834 and 0.800, respectively). The number of neutrophils, macrophages M2, macrophages M0 and dendritic cells activated decreased significantly. After BS, the infiltration of T cells regulatory, monocytes, mast cells resting and plasma cells in adipose tissue increased. The novel proposed IRGs signature reveals the underlying immune mechanism of BS and is a promising biomarker for distinguishing the severity of NAFLD. This will provide new insights into strategies for treating obesity and NAFLD.

Extra-Articular Manifestations and Comorbidities in Psoriatic Disease: A Journey Into the Immunologic Crosstalk

Psoriatic arthritis (PsA) is a chronic inflammatory disease primarily affecting peripheral and axial joints, with the possible presence of extra-articular manifestations (EAMs), such as psoriasis, uveitis, and inflammatory bowel disease. Recently, the concept of psoriatic disease (PsD) has been proposed to define a systemic condition encompassing, in addition to joints and EAMs, some comorbidities (e.g., metabolic syndrome, type II diabetes, hypertension) that can affect the disease outcome and the achievement of remission. EAMs and comorbidities in PsA share common immunopathogenic pathways linked to the systemic inflammation of this disease; these involve a broad variety of immune cells and cytokines. Currently, various therapeutics are available targeting different cytokines and molecules implicated in the inflammatory response of this condition; however, despite an improvement in the management of PsA, comprehensive disease control is often not achievable. There is, therefore, a big gap to fill especially in terms of comorbidities and EAMs management. In this review, we summarize the clinical aspects of the main comorbidities and EAMs in PsA, and we focus on the immunopathologic features they share with the articular manifestations. Moreover, we discuss the effect of a diverse immunomodulation and the current unmet needs in PsD.

Effects of astaxanthin in animal models of obesity-associated diseases: A systematic review and meta-analysis

BACKGROUND AND AIM

Obesity is a major risk factor for several diseases, including metabolic syndrome (MetS), non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes (T2D). The use of natural products, such as astaxanthin (ASX), a potent antioxidant compound produced by the freshwater green microalga Haematococcus pluvialis, has gained particular interest to reduce oxidative stress and inflammation, and to improve redox status, often associated with obesity. A systematic review and meta-analysis was performed to comprehensively examine the effects of ASX in animal models of diet induced obesity-associated diseases in order to inform the design of future human clinical studies for ASX use as supplement or nutraceutical.

METHODS

Cinahl, Cochraine, MEDLINE, Scopus and Web of Science were searched for English-language manuscripts published between January 2000 and April 2020 using the following key words: astaxanthin, obesity, non-alcoholic fatty liver disease, diabetes mellitus type 2, NAFLD and metabolic.

RESULTS

Seventeen eligible articles, corresponding to 21 animal studies, were included in the final quantitative analysis. ASX, at different concentrations and administered for different length of time, induced a significant reduction in adipose tissue weight (P = 0.05) and systolic blood pressure (P < 0.0001) in control animals. In animal models of T2D, ASX significantly reduced serum glucose levels (P = 0.04); whereas it improved several disease biomarkers in the blood (e.g. cholesterol, triglycerides, ALT and AST, P < 0.10), and reduced liver (P = 0.0002) and body weight (P = 0.11), in animal models of NAFLD.

CONCLUSIONS

Supplementation of ASX in the diet has positive effects on symptoms associated with obesity related diseases in animals, by having lipid-lowering, hypo-insulin and hypoglycaemic capacity, protecting organs from oxidative stress and mitigating the immune system, as suggested in this review.

Drug-induced liver injury and prospect of cytokine based therapy; A focus on IL-2 based therapies

Drug-induced liver injury (DILI) is one of the most frequent sources of liver failure and the leading cause of liver transplant. Common non-prescription medications such as non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, and other prescription drugs when taken at more than the recommended doses may lead to DILI. The severity of DILI is affected by factors such as age, ethnicity, race, gender, nutritional status, on-going liver diseases, renal function, pregnancy, alcohol consumption, and drug-drug interactions. Characteristics of DILI-associated inflammation include apoptosis and necrosis of hepatocytes and hepatic infiltration of pro-inflammatory immune cells. If untreated or if the inflammation continues, DILI and associated hepatic inflammation may lead to development of hepatocarcinoma. The therapeutic approach for DILI-associated hepatic inflammation depends on whether the inflammation is acute or chronic. Discontinuing the causative medication, vaccination, and special dietary supplementation are some of the conventional approaches to treat DILI. In this review, we discuss a concise overview of DILI-associated liver complications, and current therapeutic options with special emphasis on biologics including the scope of cytokine therapy in hepatic repair and resolution of inflammation caused by over- the-counter (OTC) or prescription drugs.

Mucosal Epithelial Jak Kinases in Health and Diseases

Janus kinases (Jaks) are a family of nonreceptor tyrosine kinase that include four different members, viz., Jak1, Jak2, Jak3, and Tyk2. Jaks play critical roles in immune cells functions; however, recent studies suggest they also play essential roles in nonimmune cell physiology. This review highlights the significance of epithelial Jaks in understanding the molecular basis of some of the diseases through regulation of epithelial-mesenchymal transition, cell survival, cell growth, development, and differentiation. Growth factors and cytokines produced by the cells of hematopoietic origin use Jak kinases for signal transduction in both immune and nonimmune cells. Among Jaks, Jak3 is widely expressed in both immune cells and in intestinal epithelial cells (IECs) of both humans and mice. Mutations that abrogate Jak3 functions cause an autosomal severe combined immunodeficiency disease (SCID) while activating Jak3 mutations lead to the development of hematologic and epithelial cancers. A selective Jak3 inhibitor CP-690550 (Xeljanz) approved by the FDA for certain chronic inflammatory conditions demonstrates immunosuppressive activity in rheumatoid arthritis, psoriasis, and organ transplant rejection. Here, we also focus on the consequences of Jak3-directed drugs on adverse effects in light of recent discoveries in mucosal epithelial functions of Jak3 with some information on other Jaks. Lastly, we brief on structural implications of Jak3 domains beyond the immune cells. As information about the roles of Jak3 in gastrointestinal functions and associated diseases are only just emerging, in the review, we summarize its implications in gastrointestinal wound repair, inflammatory bowel disease, obesity-associated metabolic syndrome, and epithelial cancers. Lastly, we shed lights on identifying potential novel targets in developing therapeutic interventions of diseases associated with dysfunctional IEC.

In silico analysis of non-coding RNAs and putative target genes implicated in metabolic syndrome

Regulation of gene expression is vital to maintain normal cellular functions and its dysregulation leads to molecular pathogenesis of many diseases and disorders. Non-coding RNAs regulate the expression of approximately 60% of protein-coding genes and their malfunction contribute to the development of numerous diseases. The involvement of variant forms of circulating non-coding RNAs in diseases has been established. However, their function as biomarkers or therapeutic targets in metabolic disorders are underexploited. The aim of this study was to predict therapeutic targets and construction of biomarker panel for early detection of metabolic syndrome (MS). Non-coding RNAs including circular RNAs (circRNAs), long chain non-coding RNAs (lncRNA) and micro RNAs (miRNAs) were extracted from intensive literature search and experimentally supported databases. Raw data of gene expression profiles of MS were obtained from the GEO dataset and analyzed to get differentially expressed genes (DEGs). Functional enrichment analysis, network illustration of non-coding RNAs and predicted target DEGs were performed. Furthermore, a few numbers of miRNAs targeted DEGs were subjected to homology study. The strong association of hsa-miR-548c-3p, hsa-miR-579-3p, hsa-miR-17-5p and hsa-miR-320a was observed with the pathogenesis of MS. It includes the regulation of genes in glucose and lipid homeostasis, MAPKK activity, regulation of inflammatory responses and many signaling pathways such as insulin resistance, JAK/STAT and mTOR. Finally, interactions of hsa-miR-17-5p:STAT3, hsa-miR-320:JAK2, hsa-miR-320:S6K and hsa-let-7:DVL hybrids were predicted. Results of this study suggest the designing of a biomarker panel to detect early onset and molecular approach for the management of MS.

Baricitinib counteracts metaflammation, thus protecting against diet-induced metabolic abnormalities in mice

OBJECTIVE

Recent evidence suggests the substantial pathogenic role of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway in the development of low-grade chronic inflammatory response, known as "metaflammation," which contributes to obesity and type 2 diabetes. In this study, we investigated the effects of the JAK1/2 inhibitor baricitinib, recently approved for the treatment of rheumatoid arthritis, in a murine high-fat-high sugar diet model.

METHODS

Male C57BL/6 mice were fed with a control normal diet (ND) or a high-fat-high sugar diet (HD) for 22 weeks. A sub-group of HD fed mice was treated with baricitinib (10 mg/kg die, p.o.) for the last 16 weeks (HD + Bar).

RESULTS

HD feeding resulted in obesity, insulin-resistance, hypercholesterolemia and alterations in gut microbial composition. The metabolic abnormalities were dramatically reduced by chronic baricitinib administration. Treatment of HD mice with baricitinib did not change the diet-induced alterations in the gut, but restored insulin signaling in the liver and skeletal muscle, resulting in improvements of diet-induced myosteatosis, mesangial expansion and associated proteinuria. The skeletal muscle and renal protection were due to inhibition of the local JAK2-STAT2 pathway by baricitinib. We also demonstrated that restored tissue levels of JAK2-STAT2 activity were associated with a significant reduction in cytokine levels in the blood.

CONCLUSIONS

In summary, our data suggest that the JAK2-STAT2 pathway may represent a novel candidate for the treatment of diet-related metabolic derangements, with the potential for EMA- and FDA-approved JAK inhibitors to be repurposed for the treatment of type 2 diabetes and/or its complications.

Intestinal breast cancer resistance protein (BCRP) requires Janus kinase 3 activity for drug efflux and barrier functions in obesity

Breast cancer resistance protein (BCRP) is a member of ATP-binding cassette (ABC) transporter proteins whose primary function is to efflux substrates bound to the plasma membrane. Impaired intestinal barrier functions play a major role in chronic low-grade inflammation (CLGI)-associated obesity, but the regulation of BCRP during obesity and its role in maintaining the intestinal barrier function during CLGI-associated obesity are unknown. In the present study, using several approaches, including efflux assays, immunoprecipitation, immunoblotting, immunohistochemistry, paracellular permeability assay, FACS, cytokine assay, and immunofluorescence microscopy, we report that obese individuals have compromised intestinal BCRP functions and that diet-induced obese mice recapitulate these outcomes. We demonstrate that the compromised BCRP functions during obesity are because of loss of Janus kinase 3 (JAK3)-mediated tyrosine phosphorylation of BCRP. Our results indicate that JAK3-mediated phosphorylation of BCRP promotes its interactions with membrane-localized β-catenin essential not only for BCRP expression and surface localization, but also for the maintenance of BCRP-mediated intestinal drug efflux and barrier functions. We observed that reduced intestinal JAK3 expression during human obesity or JAK3 knockout in mouse or siRNA-mediated β-catenin knockdown in human intestinal epithelial cells all result in significant loss of intestinal BCRP expression and compromised colonic drug efflux and barrier functions. Our results uncover a mechanism of BCRP-mediated intestinal drug efflux and barrier functions and establish a role for BCRP in preventing CLGI-associated obesity both in humans and in mice.

Fusobacterium nucleatum Aggravates the Progression of Colitis by Regulating M1 Macrophage Polarization via AKT2 Pathway

Disordered intestinal flora and discordant immune response are associated with the development of ulcerative colitis (UC). Recent work has described the ability of macrophages to undergo repolarization toward a proinflammatory M1 or anti-inflammatory M2 phenotype in response to particular bacterium-derived signals. Fusobacterium nucleatum (F. nucleatum, Fn) is a species of intestinal commensal bacteria with potential pathogenicity, but its association with UC and how it may contribute to progression of UC is largely unknown. In this study, we provide new evidence that F. nucleatum accumulated heavily in the intestine of UC patients and was accompanied by the secretion of IFN-γ and the skewing of M1 macrophages. Mechanistically, our data showed that F. nucleatum aggravated dextran sodium sulfate (DSS)-induced colitis in the production of Th1-related cytokines IFN-γ through the AKT2 signaling pathway in vitro and in vivo. To further confirm the disease-relevance of these shifts in macrophage repolarization in response to F. nucleatum, stimulated bone marrow-derived macrophages (BMDMs) were transferred into recipient mice with DSS colitis. This transfer resulted in increased disease activity and inflammatory cytokine production. Taken together, we show clearly that F. nucleatum can promote the progression of UC via proinflammatory M1 macrophage skewing, and targeting F. nucleatum or AKT2 signaling may be a viable means of blocking development of UC.

Genome-wide identification of directed gene networks using large-scale population genomics data

Identification of causal drivers behind regulatory gene networks is crucial in understanding gene function. Here, we develop a method for the large-scale inference of gene-gene interactions in observational population genomics data that are both directed (using local genetic instruments as causal anchors, akin to Mendelian Randomization) and specific (by controlling for linkage disequilibrium and pleiotropy). Analysis of genotype and whole-blood RNA-sequencing data from 3072 individuals identified 49 genes as drivers of downstream transcriptional changes (Wald P < 7 × 10-10), among which transcription factors were overrepresented (Fisher's P = 3.3 × 10-7). Our analysis suggests new gene functions and targets, including for SENP7 (zinc-finger genes involved in retroviral repression) and BCL2A1 (target genes possibly involved in auditory dysfunction). Our work highlights the utility of population genomics data in deriving directed gene expression networks. A resource of trans-effects for all 6600 genes with a genetic instrument can be explored individually using a web-based browser.

JAK/STAT - Emerging Players in Metabolism

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway is crucial for transducing signals from a variety of metabolically relevant hormones and cytokines including growth hormone, leptin, erythropoietin, IL4, IL6 and IFNγ. A growing body of evidence suggests that this pathway is dysregulated in the context of obesity and metabolic disease. Recent development of animal models has been instrumental in identifying the role of JAK/STAT signaling in the peripheral metabolic organs including adipose, liver, muscle, pancreas, and the immune system. In this review we summarize current knowledge about the function of JAK/STAT proteins in the regulation of metabolism, and highlight new potential therapeutic targets for the treatment of obesity and diabetes.

Janus kinase 3 regulates adherens junctions and epithelial mesenchymal transition through β-catenin

Compromise in adherens junctions (AJs) is associated with several chronic inflammatory diseases. We reported previously that Janus kinase 3, a non-receptor tyrosine kinase, plays a crucial role in AJ formation through its interaction with β-catenin. In this report, we characterize the structural determinants responsible for Jak3 interactions with β-catenin and determine the functional implications of previously unknown tyrosine residues on β-catenin phosphorylated by Jak3. We demonstrate that Jak3 autophosphorylation was the rate-limiting step during Jak3 trans-phosphorylation of β-catenin, where Jak3 directly phosphorylated three tyrosine residues, viz. Tyr³⁰, Tyr⁶⁴, and Tyr⁸⁶ in the N-terminal domain (NTD) of β-catenin. However, prior phosphorylation of β-catenin at Tyr⁶⁵⁴ was essential for further phosphorylation of β-catenin by Jak3. Interaction studies indicated that phosphorylated Jak3 bound to phosphorylated β-catenin with a dissociation constant of 0.28 μm, and although both the kinase and FERM (Band 41, ezrin, radixin, and moesin) domains of Jak3 interacted with β-catenin, the NTD domain of β-catenin facilitated its interactions with Jak3. Physiologically, Jak3-mediated phosphorylation of β-catenin suppressed EGF-mediated epithelial-mesenchymal transition and facilitated epithelial barrier functions by AJ localization of phosphorylated β-catenin through its interactions with α-catenin. Moreover, loss of Jak3-mediated phosphorylation sites in β-catenin abrogated its AJ localization and compromised epithelial barrier functions. Thus, we not only characterize Jak3 interaction with β-catenin but also demonstrate the mechanism of molecular interplay between AJ dynamics and EMT by Jak3-mediated NTD phosphorylation of β-catenin.

Effects of Di-(2-ethylhexyl) Phthalate on Lipid Metabolism by the JAK/STAT Pathway in Rats

The most widely used plasticizer, di-(2-ethylhexyl) phthalate (DEHP), is known to affect lipid metabolism and adipogenesis. We studied the effects of dietary DEHP exposure on metabolism in rats as well as the role of the JAK/STAT pathway in this process. Eighty rats were exposed to DEHP (0, 5, 50 and 500 mg/kg/d) through dietary intake for 4 weeks. We then collected blood samples, liver, and adipose tissues to detect modifications in the levels of serum lipids, leptin, adiponectin and insulin. JAK3, STAT5a and PPARγ expression were detected at both the gene and protein levels. The activation of JAK3 and STAT5a was also detected. The DEHP-exposed rats had increased body weight, serum lipid, insulin, and leptin levels. Moreover, the JAK3/STAT5a pathway was activated in the adipose tissue; however, this pathway was not activated in the liver. The mRNA of SREBP-1c in the liver was increased significantly among each of the groups, in contrast to the levels found in the mature SREBP-1c protein form. Furthermore, the expression of FABP4, Acox and FASn was decreased in the liver, but increased in adipose tissue. Thus, we conclude that exposure to DEHP reduces the hydrolysis of lipid and promotes triglyceride accumulation by oppositely regulating the activation state of JAK/STAT pathway in the liver and adipose tissue, resulting in the disorder of body lipid metabolism and obesity.

JAK2 Disease-Risk Variants Are Gain of Function and JAK Signaling Threshold Determines Innate Receptor-Induced Proinflammatory Cytokine Secretion in Macrophages

JAK2 genetic variants are associated with inflammatory bowel disease (IBD) and JAK inhibitors are being evaluated for therapy targeting immune-mediated diseases, including IBD. As JAK pathway-mediated cytokine regulation varies across cell types and stimulation conditions, we examined how JAK signaling and IBD-associated JAK2 variants regulate distinct acute and chronic microbial product exposure outcomes in human myeloid cells, consistent with the conditions of initial entry and ongoing intestinal tissue residence, respectively. Macrophages from controls and ulcerative colitis patients carrying the IBD-risk rs10758669 CC genotype showed increased JAK2 expression and nucleotide-binding oligomerization domain 2-induced JAK2 phosphorylation relative to AA carriers. Interestingly, the threshold of JAK2 expression and signaling determined pattern-recognition receptor (PRR)-induced outcomes; whereas anti-inflammatory cytokines progressively decreased with lower JAK2 expression, proinflammatory cytokines switched from decreased to increased secretion below a certain JAK2 expression threshold. Low JAK2-expressing rs10758669 AA macrophages were above this threshold; consequently, both PRR-induced pro- and anti-inflammatory cytokines were decreased. However, relative to rs10758669 CC risk carriers, AA carrier macrophages switched to increased nucleotide-binding oligomerization domain 2-induced proinflammatory cytokines at lower therapeutically used JAK inhibitor doses. Importantly, JAK inhibitors increased proinflammatory cytokines secreted by peripheral macrophages following chronic PRR stimulation and by human intestinal myeloid cells following exposure to intestinal pathogens. Mechanistically, the decreased response to and secretion of autocrine/paracrine IL-10, IL-4, IL-22 and thymic stromal lymphopoietin regulated these JAK-dependent outcomes in myeloid cells. Taken together, the JAK signaling threshold determines whether PRR-induced pro- and anti-inflammatory cytokines are reciprocally regulated in myeloid cells; consideration of JAK2 genotype and targeting of specific cell types might improve JAK-targeted therapy in immune-mediated diseases.