Genetic inactivation of the LIGHT (TNFSF14) cytokine in mice restores glucose homeostasis and diminishes hepatic steatosis

The double roles of T cell-mediated immune response in the progression of MASLD

Metabolic dysfunction-associated steatotic liver disease(MASLD), formerly known as non-alcoholic fatty liver disease(NAFLD), has become a major cause of chronic liver disease and a significant risk factor for hepatocellular carcinoma, which poses a huge burden on global public health and economy. MASLD includes steatotic liver disease, steatohepatitis, and cirrhosis, and the latter two cause great harm to human health and life, even complicated with liver cancer. Immunologic mechanism plays a major role in promoting its development into hepatitis and cirrhosis. Now more and more evidences show that T cells play an important role in the progression of MASLD. In this review, we discuss the double roles of T cells in MASLD from the perspective of T cell response pathways, as well as new evidences regarding the possible application of immunomodulatory therapy in MASH.

LIGHT/TNFSF14 Affects Adipose Tissue Phenotype

LIGHT/TNFSF14 is linked to several signaling pathways as a crucial member of a larger immunoregulatory network. It is primarily expressed in inflammatory effector cells, and high levels of LIGHT have been reported in obesity. Thus, with the aim of deepening the knowledge of the role of LIGHT on adipose tissue phenotype, we studied wild-type (WT), Tnfsf14-/-, Rag-/- and Rag-/Tnfsf14- (DKO) mice fed a normal diet (ND) or high-fat diet (HFD). Our results show that, although there is no significant weight gain between the mice with different genotypes, it is significant within each of them. We also detected an increase in visceral White Adipose Tissue (vWAT) weight in all mice fed HFD, together with the lowest levels of vWAT weight in Tnfsf14-/- and DKO mice fed ND with respect to the other strain. Inguinal WAT (iWAT) weight is significantly affected by genotype and HFD. The least amount of iWAT was detected in DKO mice fed ND. Histological analysis of vWAT showed that both the genotype and the diet significantly affect the adipocyte area, whereas the number is affected only by the genotype. In iWAT, the genotype and the diet significantly affect mean adipocyte area and number; interestingly, the area with the least adipocyte was detected in DKO mice fed ND, suggesting a potential browning effect due to the simultaneous lack of mature lymphocytes and LIGHT. Consistently, Uncoupling Protein 1 (UCP1) staining of iWAT demonstrated that few positive brown adipocytes appeared in DKO mice. Furthermore, LIGHT deficiency is associated with greater levels of UCP1, highlighting the lack of its expression in Rag-/- mice. Liver examination showed that all mice fed HFD had a steatotic liver, but it was particularly evident for DKO mice. In conclusion, our study demonstrates that the adipose tissue phenotype is affected by LIGHT levels but also much more by mature lymphocytes.

State of CD8+ T cells in progression from nonalcoholic steatohepatitis to hepatocellular carcinoma: From pathogenesis to immunotherapy

With the obesity epidemic, nonalcoholic steatohepatitis (NASH) is emerging as the fastest growing potential cause of hepatocellular carcinoma (HCC). NASH has been demonstrated to establish a tumor-prone liver microenvironment where both innate and adaptive immune systems are involved. As the most typical anti-tumor effector, the cell function of CD8+ T cells is remodeled by chronic inflammation, metabolic alteration, lipid toxicity and oxidative stress in the liver microenvironment along the NASH to HCC transition. Unexpectedly, NASH may blunt the effect of immune checkpoint inhibitor therapy against HCC due to the dysregulated CD8+ T cells. Growing evidence has supported that NASH is likely to facilitate the state transition of CD8+ T cells with changes in cell motility, effector function, metabolic reprogramming and gene transcription according to single-cell sequencing. However, the mechanistic insight of CD8+ T cell states in the NASH-driven HCC is not comprehensive. Herein, we focus on the characterization of state phenotypes of CD8+ T cells with both functional and metabolic signatures in NASH-driven fibrosis and HCC. The NASH-specific CD8+ T cells are speculated to mainly have a dualist effect, where its aberrant activated phenotype sustains chronic inflammation in NASH but subsequently triggers its exhaustion in HCC. As the exploration of CD8+ T cells on the distribution and phenotypic shifts will provide a new direction for the intervention strategies against HCC, we also discuss the implications for targeting different phenotypes of CD8+ T cells, shedding light on the personalized immunotherapy for NASH-driven HCC.

TNFSF14/LIGHT promotes cardiac fibrosis and atrial fibrillation vulnerability via PI3Kγ/SGK1 pathway-dependent M2 macrophage polarisation

BACKGROUND

Tumour necrosis factor superfamily protein 14 (TNFSF14), also called LIGHT, is an important regulator of immunological and fibrosis diseases. However, its specific involvement in cardiac fibrosis and atrial fibrillation (AF) has not been fully elucidated. The objective of this study is to examine the influence of LIGHT on the development of myocardial fibrosis and AF.

METHODS

PCR arrays of peripheral blood mononuclear cells (PBMCs) from patients with AF and sinus rhythm was used to identify the dominant differentially expressed genes, followed by ELISA to evaluate its serum protein levels. Morphological, functional, and electrophysiological changes in the heart were detected in vivo after the tail intravenous injection of recombinant LIGHT (rLIGHT) in mice for 4 weeks. rLIGHT was used to stimulate bone marrow-derived macrophages (BMDMs) to prepare a macrophage-conditioned medium (MCM) in vitro. Then, the MCM was used to culture mouse cardiac fibroblasts (CFs). The expression of relevant proteins and genes was determined using qRT-PCR, western blotting, and immunostaining.

RESULTS

The mRNA levels of LIGHT and TNFRSF14 were higher in the PBMCs of patients with AF than in those of the healthy controls. Additionally, the serum protein levels of LIGHT were higher in patients with AF than those in the healthy controls and were correlated with left atrial reverse remodelling. Furthermore, we demonstrated that rLIGHT injection promoted macrophage infiltration and M2 polarisation in the heart, in addition to promoting atrial fibrosis and AF inducibility in vivo, as detected with MASSON staining and atrial burst pacing respectively. RNA sequencing of heart samples revealed that the PI3Kγ/SGK1 pathway may participate in these pathological processes. Therefore, we confirmed the hypothesis that rLIGHT promotes BMDM M2 polarisation and TGB-β1 secretion, and that this process can be inhibited by PI3Kγ and SGK1 inhibitors in vitro. Meanwhile, increased collagen synthesis and myofibroblast transition were observed in LIGHT-stimulated MCM-cultured CFs and were ameliorated in the groups treated with PI3Kγ and SGK1 inhibitors.

CONCLUSION

LIGHT protein levels in peripheral blood can be used as a prognostic marker for AF and to evaluate its severity. LIGHT promotes cardiac fibrosis and AF inducibility by promoting macrophage M2 polarisation, wherein PI3Kγ and SGK1 activation is indispensable.

TNF superfamily control of tissue remodeling and fibrosis

Fibrosis is the result of extracellular matrix protein deposition and remains a leading cause of death in USA. Despite major advances in recent years, there remains an unmet need to develop therapeutic options that can effectively degrade or reverse fibrosis. The tumor necrosis super family (TNFSF) members, previously studied for their roles in inflammation and cell death, now represent attractive therapeutic targets for fibrotic diseases. In this review, we will summarize select TNFSF and their involvement in fibrosis of the lungs, the heart, the skin, the gastrointestinal tract, the kidney, and the liver. We will emphasize their direct activity on epithelial cells, fibroblasts, and smooth muscle cells. We will further report on major clinical trials targeting these ligands. Whether in isolation or in combination with other anti-TNFSF member or treatment, targeting this superfamily remains key to improve efficacy and selectivity of currently available therapies for fibrosis.

Immunological protein profiling of first-episode psychosis patients identifies CSF and blood biomarkers correlating with disease severity

BACKGROUND AND HYPOTHESIS

Immune activation is suggested to play an important role in psychosis. In this study, a large number of immune-related proteins were analyzed to obtain a more comprehensive picture of immune aberrations in schizophrenia.

STUDY DESIGN

Ninety-two immune markers were analyzed by the Olink Protein Extension Assay (Inflammatory Panel) in plasma and cerebrospinal fluid (CSF) from 77 first-episode psychosis (FEP) patients (of which 43 later received the diagnosis of schizophrenia) and 56 healthy controls, all recruited from the Karolinska Schizophrenia Project (KaSP), Stockholm, Sweden.

STUDY RESULTS

Differential analysis showed that 12 of 92 inflammatory proteins were significantly higher in the plasma of FEP patients (n = 77) than in controls, and several proteins were positively correlated with disease severity. Patients from the same cohort diagnosed with schizophrenia (n = 43), showed significantly higher levels of 15 plasma proteins compared to controls whereas those not receiving this diagnosis showed no significant differences. The presently used OLINK inflammatory panel allowed the detection of only 47 CSF proteins of which only CD5 differed between patients and controls.

CONCLUSIONS

The levels of several peripheral immune markers, particularly those interfering with WNT/β-catenin signaling, were significantly higher in patients with FEP than in healthy controls and associated with illness severity.

High levels of LIGHT/TNFSF14 in patients with Prader-Willi syndrome

PURPOSE/METHODS

Prader-Willi syndrome (PWS) is a rare genetic disorder displaying different clinical features, including obesity and bone impairment. LIGHT/TNFSF14 is a cytokine produced by immune cells affecting both fat and bone metabolism. The present study aimed to evaluate LIGHT serum levels in 28 children and 52 adult PWS patients compared to age and sex-matched controls, as well as correlations with parameters of bone and fat metabolism.

RESULTS

Median serum LIGHT levels were significantly increased in pediatric PWS with respect to controls [255.82 (284.43) pg/ml vs 168.11 (76.23) pg/ml, p ≤ 0.02] as well as in adult PWS compared to controls [296.85 (895.95) pg/ml vs 134.18 (141.18) pg/ml, p ≤ 0.001]. In pediatric PWS, LIGHT levels were positively correlated with weight-SDS, height-SDS, and glucose levels, and negatively with total 25 (OH) vitamin D, cholesterol, LDL cholesterol and triglycerides. Additionally, LIGHT levels were negatively correlated with total BMD and fat mass. In adult PWS, LIGHT levels were positively correlated with weight, HDL cholesterol and PTH, and negatively with glucose, insulin, HOMA-IR, total cholesterol, LDL cholesterol, triglycerides, calcium, phosphorus, 25(OH)Vitamin D as well as with instrumental parameters of bone and fat quality. Consistently, multiple regression analysis showed that LIGHT serum levels in pediatric and adult PWS were predicted by different parameters including 25 (OH) Vitamin D as well as DXA parameters of bone and fat quality.

CONCLUSIONS

In PWS children and adults the high levels of LIGHT could represent a marker of the altered bone and fat metabolism.

Decoding the role of immune T cells: A new territory for improvement of metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) is a new emerging concept and is associated with metabolic dysfunction, generally replacing the name of nonalcoholic fatty liver disease (NAFLD) due to heterogeneous liver condition and inaccuracies in definition. The prevalence of MAFLD is rising by year due to dietary changes, metabolic disorders, and no approved therapy, affecting a quarter of the global population and representing a major economic problem that burdens healthcare systems. Currently, in addition to the common causative factors like insulin resistance, oxidative stress, and lipotoxicity, the role of immune cells, especially T cells, played in MAFLD is increasingly being emphasized by global scholars. Based on the diverse classification and pathophysiological effects of immune T cells, we comprehensively analyzed their bidirectional regulatory effects on the hepatic inflammatory microenvironment and MAFLD progression. This interaction between MAFLD and T cells was also associated with hepatic-intestinal immune crosstalk and gut microbiota homeostasis. Moreover, we pointed out several T-cell-based therapeutic approaches including but not limited to adoptive transfer of T cells, fecal microbiota transplantation, and drug therapy, especially for natural products and Chinese herbal prescriptions. Overall, this study contributes to a better understanding of the important role of T cells played in MAFLD progression and corresponding therapeutic options and provides a potential reference for further drug development.

Vascular smooth muscle cell phenotype is modulated by ligands of the lymphotoxin β receptor and the tumor necrosis factor receptor

OBJECTIVE

Vascular smooth muscle cells (VSMCs) undergo a phenotypic-switching process during the generation of unstable atheroma plaques. In this investigation, the potential implication of the tumor necrosis factor superfamily (TNFSF) ligands, in the gene expression signature associated with VSMC plasticity was studied.

MATERIAL AND METHODS

Human aortic (ha)VSMCs were obtained commercially and treated with the cytokine TNFSF14, also called LIGHT, the lymphotoxin alpha (LTα), the heterotrimer LTα₁β₂ or with vehicle for 72h. The effect of the different treatments on gene expression was analyzed by quantitative PCR and included the study of genes associated with myofibroblast-like cell function, osteochondrogenesis, pluripotency, lymphorganogenesis and macrophage-like cell function.

RESULTS

HaVSMCs displayed a change in myofibroblast-like cell genes which consisted in reduced COL1A1 and TGFB1 mRNA levels when treated with LTα or LIGHT and with augmented MMP9 expression levels when treated with LTα. LTα and LIGHT treatments also diminished the expression of genes associated with osteochondrogenesis and pluripotency SOX9, CKIT, and KLF4. By contrary, all the above genes were no affected by the treatment with the trimer LTα₁β₂. In addition, haVSMC treatment with LTα, LTα₁β₂ and LIGHT altered lymphorganogenic cytokine gene expression which consisted of augmented CCL20 and CCL21 mRNA levels by LTα and a reduction in the gene expression of CCL21 and CXCL13 by LIGHT and LTα₁β₂ respectively. Neither, LTα or LIGHT or LTα₁β₂ treatments affected the expression of macrophage-like cell markers in haVSMC.

CONCLUSIONS

Altogether, indicates that the TNFSF ligands through their interconnected network of signaling, are important in the preservation of VSMC identity against the acquisition of a genetic expression signature compatible with functional cellular plasticity.

Genetic Polymorphisms and Diversity in Nonalcoholic Fatty Liver Disease (NAFLD): A Mini Review

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease with a wide spectrum of liver conditions ranging from hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The prevalence of NAFLD varies across populations, and different ethnicities have specific risks for the disease. NAFLD is a multi-factorial disease where the genetics, metabolic, and environmental factors interplay and modulate the disease's development and progression. Several genetic polymorphisms have been identified and are associated with the disease risk. This mini-review discussed the NAFLD's genetic polymorphisms and focusing on the differences in the findings between the populations (diversity), including of those reports that did not show any significant association. The challenges of genetic diversity are also summarized. Understanding the genetic contribution of NAFLD will allow for better diagnosis and management explicitly tailored for the various populations.

Adipose methylome integrative-omic analyses reveal genetic and dietary metabolic health drivers and insulin resistance classifiers

BACKGROUND

There is considerable evidence for the importance of the DNA methylome in metabolic health, for example, a robust methylation signature has been associated with body mass index (BMI). However, visceral fat (VF) mass accumulation is a greater risk factor for metabolic disease than BMI alone. In this study, we dissect the subcutaneous adipose tissue (SAT) methylome signature relevant to metabolic health by focusing on VF as the major risk factor of metabolic disease. We integrate results with genetic, blood methylation, SAT gene expression, blood metabolomic, dietary intake and metabolic phenotype data to assess and quantify genetic and environmental drivers of the identified signals, as well as their potential functional roles.

METHODS

Epigenome-wide association analyses were carried out to determine visceral fat mass-associated differentially methylated positions (VF-DMPs) in SAT samples from 538 TwinsUK participants. Validation and replication were performed in 333 individuals from 3 independent cohorts. To assess functional impacts of the VF-DMPs, the association between VF and gene expression was determined at the genes annotated to the VF-DMPs and an association analysis was carried out to determine whether methylation at the VF-DMPs is associated with gene expression. Further epigenetic analyses were carried out to compare methylation levels at the VF-DMPs as the response variables and a range of different metabolic health phenotypes including android:gynoid fat ratio (AGR), lipids, blood metabolomic profiles, insulin resistance, T2D and dietary intake variables. The results from all analyses were integrated to identify signals that exhibit altered SAT function and have strong relevance to metabolic health.

RESULTS

We identified 1181 CpG positions in 788 genes to be differentially methylated with VF (VF-DMPs) with significant enrichment in the insulin signalling pathway. Follow-up cross-omic analysis of VF-DMPs integrating genetics, gene expression, metabolomics, diet, and metabolic traits highlighted VF-DMPs located in 9 genes with strong relevance to metabolic disease mechanisms, with replication of signals in FASN, SREBF1, TAGLN2, PC and CFAP410. PC methylation showed evidence for mediating effects of diet on VF. FASN DNA methylation exhibited putative causal effects on VF that were also strongly associated with insulin resistance and methylation levels in FASN better classified insulin resistance (AUC=0.91) than BMI or VF alone.

CONCLUSIONS

Our findings help characterise the adiposity-associated methylation signature of SAT, with insights for metabolic disease risk.

Realigning the LIGHT signaling network to control dysregulated inflammation

Advances in understanding the physiologic functions of the tumor necrosis factor superfamily (TNFSF) of ligands, receptors, and signaling networks are providing deeper insight into pathogenesis of infectious and autoimmune diseases and cancer. LIGHT (TNFSF14) has emerged as an important modulator of critical innate and adaptive immune responses. LIGHT and its signaling receptors, herpesvirus entry mediator (TNFRSF14), and lymphotoxin β receptor, form an immune regulatory network with two co-receptors of herpesvirus entry mediator, checkpoint inhibitor B and T lymphocyte attenuator, and CD160. Deciphering the fundamental features of this network reveals new understanding to guide therapeutic development. Accumulating evidence from infectious diseases points to the dysregulation of the LIGHT network as a disease-driving mechanism in autoimmune and inflammatory reactions in barrier organs, including coronavirus disease 2019 pneumonia and inflammatory bowel diseases. Recent clinical results warrant further investigation of the LIGHT regulatory network and application of target-modifying therapeutics for disease intervention.

Identification of Key Biomarkers and Immune Infiltration in Liver Tissue after Bariatric Surgery

Background

Few drugs are clearly available for nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH); nevertheless, mounting studies have provided sufficient evidence that bariatric surgery is efficient for multiple metabolic diseases, including NAFLD and NASH, while the molecular mechanisms are still poorly understood.

Methods

The mRNA expression profiling of GSE48452 and GSE83452 were retrieved and obtained from the Gene Expression Omnibus (GEO) database. The limma package was employed for identifying differentially expressed genes (DEGs), followed by clusterProfiler for performing Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, and GSEA software for performing GSEA analyses. The PPI network analyses were constructed using Metascape online analyses. WGCNA was also utilized to identify and verify the hub genes. CIBERSORT tools contributed to the analysis of immune cell infiltration of liver diseases.

Results

We identify coexpressed differential genes including 10 upregulated and 55 downregulated genes in liver tissue after bariatric surgery. GO and KEGG enrichment analyses indicated that DEGs were remarkably involved in the immune response. GSEA demonstrated that DEGs were markedly enriched in the immune response before surgery, while most were enriched in metabolism after surgery. Seven genes were screened through the MCC algorithm and KME values, including SRGN, CD53, EVI2B, MPEG1, NCKAP1L, LCP1, and TYROBP. The mRNA levels of these genes were verified in the Attie Lab Diabetes Database, and only LCP1 was found to have significant differences and correlation with certain immune cells.

Conclusion

Our knowledge of the mechanisms by which bariatric surgery benefits the liver and the discovery of LCP1 is expected to serve as potential biomarkers or therapeutic targets for NAFLD and NASH.

[Translated article] Practical Update of the Guidelines Published by the Psoriasis Group of the Spanish Academy of Dermatology and Venereology (GPs) on the Treatment of Psoriasis With Biologic Agents: Part 2-Management of Special Populations, Patients With Comorbid Conditions, and Risk

BACKGROUND AND OBJECTIVES

Since its inception, the Psoriasis Group (GPs) of the Spanish Academy of Dermatology and Venereology (AEDV) has worked to continuously update recommendations for the treatment of psoriasis based on the best available evidence and incorporating proposals arising from and aimed at clinical practice. An updated GPs consensus document on the treatment of moderate to severe psoriasis was needed because of changes in the treatment paradigm and the approval in recent years of a large number of new biologic agents.

METHODOLOGY

The consensus document was developed using the nominal group technique complemented by a scoping review. First, a designated coordinator selected a group of GPs members for the panel based on their experience and knowledge of psoriasis. The coordinator defined the objectives and key points for the document and, with the help of a documentalist, conducted a scoping review of articles in Medline, Embase, and the Cochrane Library up to January 2021. The review included systematic reviews and meta-analyses as well as clinical trials not included in those studies and high-quality real-world studies. National and international clinical practice guidelines and consensus documents on the management of moderate to severe psoriasis were also reviewed. The coordinator then drew up a set of proposed recommendations, which were discussed and modified in a nominal group meeting. After several review processes, including external review by other GPs members, the final document was drafted.

RESULTS

The present guidelines include updated recommendations on assessing the severity of psoriasis and criteria for the indication of systemic treatment. They also include general principles for the treatment of patients with moderate to severe psoriasis and define treatment goals for these patients as well as criteria for the indication and selection of initial and subsequent therapies Practical issues, such as treatment failure and maintenance of response, are also addressed.

Administration of Glutaredoxin-1 Attenuates Liver Fibrosis Caused by Aging and Non-Alcoholic Steatohepatitis

Liver fibrosis is a sign of non-alcoholic fatty liver disease progression towards steatohepatitis (NASH) and cirrhosis and is accelerated by aging. Glutaredoxin-1 (Glrx) controls redox signaling by reversing protein S-glutathionylation, induced by oxidative stress, and its deletion causes fatty liver in mice. Although Glrx regulates various pathways, including metabolism and apoptosis, the impact of Glrx on liver fibrosis has not been studied. Therefore, we evaluated the role of Glrx in liver fibrosis induced by aging or by a high-fat, high-fructose diet. We found that: (1) upregulation of Glrx expression level inhibits age-induced hepatic apoptosis and liver fibrosis. In vitro studies indicate that Glrx regulates Fas-induced apoptosis in hepatocytes; (2) diet-induced NASH leads to reduced expression of Glrx and higher levels of S-glutathionylated proteins in the liver. In the NASH model, hepatocyte-specific adeno-associated virus-mediated Glrx overexpression (AAV-Hep-Glrx) suppresses fibrosis and apoptosis and improves liver function; (3) AAV-Hep-Glrx significantly inhibits transcription of Zbtb16 and negatively regulates immune pathways in the NASH liver. In conclusion, the upregulation of Glrx is a potential therapeutic for the reversal of NASH progression by attenuating inflammatory and fibrotic processes.

The Contribution of LIGHT to the Development of Systemic Sclerosis by Modulating IL-6 and T Helper Type 1 Chemokine Expression in Dermal Fibroblasts

Systemic sclerosis (SSc) is an autoimmune and vascular disease resulting in multiple organ fibrosis, in which IL-6 and T helper (Th)2/Th17 cytokines serve as critical disease drivers. LIGHT is a proinflammatory cytokine promoting IL-6 production in lung fibroblasts and Th1 chemokine expression in dermal fibroblasts (DFs) stimulated with IFN-γ. In this study, we investigated the potential contribution of LIGHT to SSc development using clinical samples and animal models. In SSc-involved skin, LIGHT was upregulated in inflammatory cells, whereas herpesvirus entry mediator (HVEM), a receptor of LIGHT, was downregulated in DFs. Similar expression profiles of LIGHT and HVEM were reproduced in bleomycin-treated mice. Transcription factor FLI1 bound to the HVEM promoter, and FLI1 small interfering RNA suppressed HVEM expression in normal DFs. In SSc DFs, LIGHT significantly increased IL-6 production, whereas IFN-γ/LIGHT-dependent Th1 chemokine induction was decreased compared with that in normal DFs. Importantly, LIGHT small interfering RNA significantly attenuated bleomycin-induced skin fibrosis, and serum LIGHT levels were elevated in patients with diffuse cutaneous SSc and positively correlated with clinical parameters reflecting skin and pulmonary fibrosis. Taken together, these results suggest that altered response of DFs to LIGHT, namely increased IL-6 production and decreased Th1 chemokine expression, contributes to the development of skin fibrosis in SSc.

LIGHT (TNFSF14) inhibits glucose uptake of adipocytes by downregulating GLUT4 expression via AKT signaling pathway

Glucose homeostasis of adipocytes could be regulated by immune-adipose crosstalk. In order to investigate the effects of Lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells (LIGHT) on glucose metabolism, we performed the present study. Our results showed that LIGHT deficiency improved glucose tolerance and enhanced glucose consumption of inguinal white adipose tissue (iWAT) under high fat diet. Consistently, Light overexpression could inhibit glucose uptake during the process of white adipogenesis. Mechanistically, LIGHT interacted with lymphotoxin-β receptor (LTβR) to attenuate AKT pathway leading to downregulation of glucose transporter-4 (GLUT4) expression, which resulted in glucose uptake inhibition. In summary, our findings revealed LIGHT-LTβR-AKT-GLUT4 axis as a regulator of glucose uptake in adipose tissue, which suggested the pivotal role of LIGHT in maintaining glucose homeostasis.

HES5-mediated repression of LIGHT transcription may contribute to apoptosis in hepatocytes

Non-alcoholic fatty liver disease (NAFLD) is prototypical form of metabolic syndrome and has become a global pandemic. Hepatocytes undergo apoptosis in the pathogenesis of NAFLD. We report that the lymphokine LIGHT/TNFSF14 was upregulated in the murine NAFLD livers and in hepatocytes treated with free fatty acids (palmitate, PA). LIGHT knockdown or neutralization attenuated PA-induced apoptosis of hepatocytes. Similarly, knockdown or blockade of LTβR, the receptor for LIGHT, ameliorated apoptosis in hepatocytes exposed to PA. Ingenuity pathway analysis (IPA) revealed several Notch-related transcription factors as upstream regulators of LIGHT, of which HES5 expression was downregulated paralleling LIGHT induction in the pathogenesis of NAFLD. HES5 knockdown enhanced whereas HES5 over-expression weakened LIGHT induction in hepatocytes. HES5 was found to directly bind to the LIGHT promoter and repress LIGHT transcription. Mechanistically, HES5 interacted with SIRT1 to deacetylate histone H3/H4 on the LIGHT promoter to repress LIGHT transcription. SIRT1 knockdown or inhibition offset the effect of HES5 over-expression on LIGHT transcription and hepatocyte apoptosis. In conclusion, our data unveil a novel mechanism that might contribute to excessive apoptosis in hepatocyte exposed to free fatty acids.

Dissecting Abdominal Aortic Aneurysm Is Aggravated by Genetic Inactivation of LIGHT (TNFSF14)

Abdominal aortic aneurysm (AAA), is a complex disorder characterized by vascular vessel wall remodeling. LIGHT (TNFSF14) is a proinflammatory cytokine associated with vascular disease. In the present study, the impact of genetic inactivation of Light was investigated in dissecting AAA induced by angiotensin II (AngII) in the Apolipoprotein E-deficient (Apoe^−/−) mice. Studies in aortic human (ah) vascular smooth muscle cells (VSMC) to study potential translation to human pathology were also performed. AngII-treated Apoe^−/−Light^−/− mice displayed increased abdominal aorta maximum diameter and AAA severity compared with Apoe^−/− mice. Notably, reduced smooth muscle α-actin+ area and Acta2 and Col1a1 gene expression were observed in AAA from Apoe^−/−Light^−/− mice, suggesting a loss of VSMC contractile phenotype compared with controls. Decreased Opn and augmented Sox9 expression, which are associated with detrimental and non-contractile osteochondrogenic VSMC phenotypes, were also seen in AngII-treated Apoe^−/−Light^−/− mouse AAA. Consistent with a role of LIGHT preserving VSMC contractile characteristics, LIGHT-treatment of ahVSMCs diminished the expression of SOX9 and of the pluripotency marker CKIT. These effects were partly mediated through lymphotoxin β receptor (LTβR) as the silencing of its gene ablated LIGHT effects on ahVSMCs. These studies suggest a protective role of LIGHT through mechanisms that prevent VSMC trans-differentiation in an LTβR-dependent manner.

TNFSF14-Derived Molecules as a Novel Treatment for Obesity and Type 2 Diabetes

Obesity is one of the most prevalent metabolic diseases in the Western world and correlates directly with glucose intolerance and insulin resistance, often culminating in Type 2 Diabetes (T2D). Importantly, our team has recently shown that the TNF superfamily (TNFSF) member protein, TNFSF14, has been reported to protect against high fat diet induced obesity and pre-diabetes. We hypothesized that mimics of TNFSF14 may therefore be valuable as anti-diabetic agents. In this study, we use in silico approaches to identify key regions of TNFSF14 responsible for binding to the Herpes virus entry mediator and Lymphotoxin β receptor. In vitro evaluation of a selection of optimised peptides identified six potentially therapeutic TNFSF14 peptides. We report that these peptides increased insulin and fatty acid oxidation signalling in skeletal muscle cells. We then selected one of these promising peptides to determine the efficacy to promote metabolic benefits in vivo. Importantly, the TNFSF14 peptide 7 reduced high fat diet-induced glucose intolerance, insulin resistance and hyperinsulinemia in a mouse model of obesity. In addition, we highlight that the TNFSF14 peptide 7 resulted in a marked reduction in liver steatosis and a concomitant increase in phospho-AMPK signalling. We conclude that TNFSF14-derived molecules positively regulate glucose homeostasis and lipid metabolism and may therefore open a completely novel therapeutic pathway for treating obesity and T2D.

Unraveling the Role of Immune Checkpoints in Leishmaniasis

Leishmaniasis are Neglected Tropical Diseases affecting millions of people every year in at least 98 countries and is one of the major unsolved world health issues. Leishmania is a parasitic protozoa which are transmitted by infected sandflies and in the host they mainly infect macrophages. Immunity elicited against those parasites is complex and immune checkpoints play a key role regulating its function. T cell receptors and their respective ligands, such as PD-1, CTLA-4, CD200, CD40, OX40, HVEM, LIGHT, 2B4 and TIM-3 have been characterized for their role in regulating adaptive immunity against different pathogens. However, the exact role those receptors perform during Leishmania infections remains to be better determined. This article addresses the key role immune checkpoints play during Leishmania infections, the limiting factors and translational implications.

Dapagliflozin Does Not Modulate Atherosclerosis in Mice with Insulin Resistance

Type 2 diabetes mellitus (T2DM) increases morbimortality in humans via enhanced susceptibility to cardiovascular disease (CVD). Sodium-glucose co-transporter 2 inhibitors (SGLT2i) are drugs designed for T2DM treatment to diminish hyperglycaemia by reducing up to 90% of renal tube glucose reabsorption. Clinical studies also suggest a beneficial action of SGLT2i in heart failure and CVD independent of its hypoglycaemiant effect. In the present study, we explored the effect of SGLT2i dapagliflozin (DAPA) in the metabolism and atherosclerosis in Apoe−/−Irs2+/− mice, which display accelerated atherosclerosis induced by insulin resistance. DAPA treatment of Apoe−/−Irs2+/− mice, which were fed a high-fat, high-cholesterol diet, failed to modify body weight, plasma glucose or lipid. Carbohydrate metabolism characterisation showed no effect of DAPA in the glucose tolerance test (GTT) despite augmented insulin levels during the test. In fact, decreased C-peptide levels in DAPA-treated mice during the GTT suggested impaired insulin release. Consistent with this, DAPA treatment of Apoe−/−Irs2+/− isolated islets displayed lower glucose-stimulated insulin secretion compared with vehicle-treated islets. Moreover, insulin-signalling experiments showed decreased pAKT activation in DAPA-treated adipose tissue indicating impaired insulin signalling in this tissue. No changes were seen in lesion size, vulnerability or content of macrophages, vascular smooth muscle cells, T cells or collagen. DAPA did not affect circulating inflammatory cells or cytokine levels. Hence, this study indicates that DAPA does not protect against atherosclerosis in insulin-resistant mice in hypercholesterolemic conditions.

LIGHT deficiency aggravates cisplatin-induced acute kidney injury by upregulating mitochondrial apoptosis

Cisplatin is widely used as a chemotherapeutic agent for treating patients with solid tumors. The most common side effect of cisplatin treatment is nephrotoxicity. Recent studies have shown that mitochondrial apoptotic pathways are involved in cisplatin-induced acute kidney injury (Cis-AKI). LIGHT, the 14th member of the tumor necrosis factor superfamily (TNFSF14), was found to induce apoptosis of certain types of tumor cells. So far, a link between LIGHT and Cis-AKI has not been reported. In this study, we observed that expression of LIGHT and its receptors HVEM and LTβR was increased in kidney tissues of mice after cisplatin treatment. LIGHT deficiency aggravated kidney injury, as evidenced by more severe tubular injury; remarkably increased levels of serum creatinine (Scr), blood urea nitrogen (BUN), and both kidney injury molecule-1 (KIM-1) and inflammatory cytokine mRNAs in renal tissues. Moreover, in the renal tissues of LIGHT KO mice, cisplatin-induced mitochondrion injury and the levels of the pro-apoptotic molecules Bax, Cytochrome C (Cyt C), cleaved caspase-3, and cleaved caspase-9 were dramatically increased; in contrast, the expression of anti-apoptotic molecule Bcl-2 was markedly reduced, compared to those in WT mice, suggesting that LIGHT deficiency accelerated cisplatin-induced mitochondrial apoptosis of renal tubular cells in these mice. Accordingly, treatment with recombinant human LIGHT (rLIGHT) was shown to alleviate cisplatin-induced kidney injury in vivo. Similar results were observed after the human renal tubular epithelial cell line HK-2 cells exposure to rLIGHT stimulation, evidenced by the reduction in the mitochondrion dysfunction (as confirmed by the significant reduced oxidative stress and membrane potential changes) and in the percentage of cells apoptosis. While blocking LIGHT with the soluble fusion protein LTβR-Ig or HVEM-Ig accelerated the HK-2 cells apoptosis. In conclusion, LIGHT deficiency aggravates Cis-AKI by promoting mitochondrial apoptosis pathways.

The cellular pathways of liver fibrosis in non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is considered the advanced stage of non-alcoholic fatty liver disease (NAFLD). It is characterized by liver steatosis, inflammation and different degrees of fibrosis. Although the exact mechanisms by which fatty liver progresses to NASH are still not well understood, innate and adaptive immune responses seem to be essential key regulators in the establishment, progression, and chronicity of these disease. Diet-induced lipid overload of parenchymal and non-parenchymal liver cells is considered the first step for the development of fatty liver with the consequent organelle dysfunction, cellular stress and liver injury. These will generate the production of pro-inflammatory cytokines, chemokines and damage-associated molecular patterns (DAMPs) that will upregulate the activation of Kupffer cells (KCs) and monocyte-derived macrophages (MMs) favoring the polarization of the tolerogenic environment of the liver to an immunogenic phenotype with the resulting transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts developing fibrosis. In the long run, dendritic cells (DCs) will activate CD4+ T cells polarizing into the pro-inflammatory lymphocytes Th1 and Th17 worsening the liver damage and inflammation. Therefore, the objective of this review is to discuss in a systematic way the mechanisms known so far of the immune and non-proper immune liver cells in the development and progression of NASH.

Adaptive immunity: an emerging player in the progression of NAFLD

In the past decade, nonalcoholic fatty liver disease (NAFLD) has become a leading cause of chronic liver disease and cirrhosis, as well as an important risk factor for hepatocellular carcinoma (HCC). NAFLD encompasses a spectrum of liver lesions, including simple steatosis, steatohepatitis and fibrosis. Although steatosis is often harmless, the lobular inflammation that characterizes nonalcoholic steatohepatitis (NASH) is considered a driving force in the progression of NAFLD. The current view is that innate immune mechanisms represent a key element in supporting hepatic inflammation in NASH. However, increasing evidence points to the role of adaptive immunity as an additional factor promoting liver inflammation. This Review discusses data regarding the role of B cells and T cells in sustaining the progression of NASH to fibrosis and HCC, along with the findings that antigens originating from oxidative stress act as a trigger for immune responses. We also highlight the mechanisms affecting liver immune tolerance in the setting of steatohepatitis that favour lymphocyte activation. Finally, we analyse emerging evidence concerning the possible application of immune modulating treatments in NASH therapy.