Regulation of interferon signaling in response to gut microbes by autophagy

Exploring the Connections: Autophagy, Gut Microbiota, and Inflammatory Bowel Disease Pathogenesis

Inflammatory Bowel Disease (IBD), which includes Crohn's disease and ulcerative colitis, represents a complex and growing global health issue with a multifaceted origin. This review delves into the intricate relationship between gut microbiota, autophagy, and the development of IBD. The gut microbiota, a diverse community of microorganisms, plays a vital role in maintaining gut health, while imbalances in this microbial community, known as dysbiosis, are linked to IBD. Autophagy, a process by which cells recycle their components, is essential for gut homeostasis and the regulation of immune responses. When autophagy is impaired and dysbiosis occurs, they individually contribute to IBD, with their combined impact intensifying inflammation. The interconnectedness of gut microbiota, autophagy, and the host's immune system is central to the onset of IBD. The review also examines how diet influences gut microbiota and its subsequent effects on IBD. It highlights the therapeutic potential of targeting the microbiota and modulating autophagic pathways as treatment strategies for IBD. Understanding these interactions could lead to personalized therapies within the rapidly advancing fields of microbiome research and immunology.

New insights into the interplay between autophagy, gut microbiota and insulin resistance in metabolic syndrome

Metabolic syndrome (MetS) is a widespread and multifactorial disorder, and the study of its pathogenesis and treatment remains challenging. Autophagy, an intracellular degradation system that maintains cellular renewal and homeostasis, is essential for maintaining antimicrobial defense, preserving epithelial barrier integrity, promoting mucosal immune response, maintaining intestinal homeostasis, and regulating gut microbiota and microbial metabolites. Dysfunctional autophagy is implicated in the pathological mechanisms of MetS, involving insulin resistance (IR), chronic inflammation, oxidative stress, and endoplasmic reticulum (ER) stress, with IR being a predominant feature. The study of autophagy represents a valuable field of research with significant clinical implications for identifying autophagy-related signals, pathways, mechanisms, and treatment options for MetS. Given the multifactorial etiology and various potential risk factors, it is imperative to explore the interplay between autophagy and gut microbiota in MetS more thoroughly. This will facilitate the elucidation of new mechanisms underlying the crosstalk among autophagy, gut microbiota, and MetS, thereby providing new insights into the diagnosis and treatment of MetS.

Vine tea extract ameliorated acute liver injury by inhibiting hepatic autophagy and reversing abnormal bile acid metabolism

Gut microbiota disturbance, autophagy dysregulation, and accumulation of hepatic bile acids (BAs) are essential features of liver injury. Therefore, regulating autophagy and BA metabolism are potential strategies for treating liver diseases. Vine tea has been seen beyond a pleasant tea in food science. Our previous study found that vine tea extract (VTE) intervention alleviated acute liver injury (ALI) by restoring gut microbiota dysbiosis. In this study, we aim to investigate the effect of VTE on carbon tetrachloride (CCl4)-induced hepatic autophagy and BA metabolism disorder in mice. The results showed that VTE effectively suppressed CCl4-induced liver fibrosis and hepatic autophagy. LC-MS/MS assay suggested that VTE affected fecal BA production by reducing the fecal BA levels and improving cholestasis in ALI mice. Besides, VTE inhibited BA synthesis, promoted BA transport in the liver, and enhanced BA reabsorption in the ileum through the farnesoid X receptor (FXR)-related signaling pathway. The hepatic expressions of Fxr and Abca1 were elevated by VTE. Finally, the depletion of gut microbiota in ALI mice had a negative impact on abnormal autophagy and BA metabolism. It was also noted that the administration of VTE did not provide any additional improvement in this regard. Overall, VTE ameliorated ALI by reversing hepatic autophagy and abnormal BA metabolism, and the beneficial effects of VTE on liver injury depended on the existence of gut microbiota.

Exploring a Possible Link between the Fecal Microbiota and the Production Performance of Pigs

The backfat thickness of pigs not only affects the physical properties and taste of meat, but it also closely relates to the reproduction performance of sows. Accumulating evidence indicates that, apart from genetic factors, gut microbiota can also modulate the fat deposition and muscle growth. However, the differential microbiota in pigs with different backfat thickness, and whether microbiota affects backfat thickness, remains elusive. Firstly, 16S ribosomal RNA (16S rRNA) gene sequencing was performed on 62 fecal samples from pigs with different backfat thicknesses, and the compositions of microbiota among different groups with different backfat thicknesses were different. The abundance of Lactobacillus. reuteri (L. reuteri) and Prevotella sp RS2 was significantly higher in pigs with low-backfat thickness than that in pigs with middle and high-backfat thickness; meanwhile, the abundance of Desulfovibrio piger was significantly lower (p < 0.05) in pigs with low-backfat thickness. Furthermore, the functional profiling of microbial communities suggested that the abundance of isoquinoline alkaloid biosynthesis and styrene degradation were significantly lower (p < 0.05) in the low-backfat thickness group than that in middle and high-backfat thickness groups. Finally, L. reuteri fed to Meishan piglets was capable of improving the production performance and had the potential to reduce backfat thickness. This study provides new evidence that microbiota can regulate the phenotype of the host, and dietary supplementation with L. reuteri can improve the production performance of piglets.

Inhibition of lncRNA NEAT1 protects endothelial cells against hypoxia/reoxygenation‑induced NLRP3 inflammasome activation by targeting the miR‑204/BRCC3 axis

Cardiovascular ischemia/reperfusion (I/R) injury is primarily caused by oxygen recovery after prolonged hypoxia. Previous studies found that the long non coding RNA (lncRNA) nuclear enriched abundant transcript 1 (NEAT1) was involved in cardiovascular pathology, and that NOD-like receptor protein 3 (NLRP3) inflammasome activation-dependent pyroptosis played a key role in cardiovascular I/R injury. The present study aimed to explore the molecular mechanism of I/R pathogenesis in order to provide novel insights for potential future therapies. Cell viability and lactate dehydrogenase enzyme activity assays were used to detect cell injury after human umbilical vein endothelial cells (HUVECs) were subjected to hypoxia/reoxygenation (H/R). The expression of the NEAT1/microRNA (miR)-204/BRCA1/BRCA2-containing complex subunit 3 (BRCC3) axis was examined by reverse transcription-quantitative PCR, and the associations among genes were confirmed by luciferase reporter assays. Western blotting and ELISA were used to measure the level of NLRP3 inflammasome activation-dependent pyroptosis. The results demonstrated that NEAT1, BRCC3 expression and NLRP3 inflammasome activation-dependent pyroptosis were significantly increased in H/R-injured HUVECs, whereas silencing BRCC3 or NEAT1 attenuated H/R-induced injury and pyroptosis. NEAT1 positively regulated BRCC3 expression via competitively binding with miR-204. Moreover, NEAT1 overexpression counteracted miR-204 mimic-induced injury, BRCC3 expression and NLRP3 inflammasome activation-dependent pyroptosis. Taken together, these findings demonstrated that inhibition of lncRNA NEAT1 protects HUVECs against H/R-induced NLRP3 inflammasome activation by targeting the miR-204/BRCC3 axis.

Type I interferon detection in autoimmune diseases: challenges and clinical applications

INTRODUCTION

Accumulating data highlights that the dysregulation of type I interferon (IFN) pathways plays a central role in the pathogenesis of several systemic and organ-specific autoimmune diseases. Advances in understanding the role of type I IFNs in these disorders can lead to targeted drug development as well as establishing potential disease biomarkers.

AREAS COVERED

Here, we summarize current knowledge regarding the role of type I IFNs in the major systemic, as well as organ-specific, autoimmune disorders, including prominent inflammatory CNS disorders like multiple sclerosis.

EXPERT OPINION

Type I IFN involvement and its clinical associations in a wide spectrum of autoimmune diseases represents a promising area for research aiming to unveil common pathogenetic pathways in systemic and organ-specific autoimmunity.

Bisphenol A increases TLR4-mediated inflammatory response by up-regulation of autophagy-related protein in lung of adolescent mice

In previous studies we found that bisphenol A (BPA) aggravated OVA-induced lung inflammation. The aim of this research was to determine whether BPA exposure alone also induced inflammatory response in the lungs, which mechanism was associated with TLR4/NF-κB signaling pathway and the activation of mTOR-mediated autophagy. Female C57BL/6 mice aged 4 weeks were randomly divided into three groups (10/group): control group, 0.1 and 0.2 μg mL^-1 BPA groups. BPA induced the pathological changes in the lung and increased the levels of cytokines and inflammatory cells, as well as affected autophagy related proteins expression. In addition, the RAW264.7 cell culture experiment was conducted in order to confirm the role of autophagy. We found that BPA can enhance autophagy flux by enhancing autophagosome formation. It was further confirmed the details of the mechanism of action with chloroquine (CQ, a compound that inhibits the fusion of autophagosomes and lysosomes) intervention. The inhibition of autophagy led to down-regulation of expression levels associated with inflammation. This research results indicated that BPA induced inflammatory response in vitro and in vivo, and its mechanism may be related to TLR4/NF-κB signaling pathway and the activation of mTOR-mediated autophagy. After autophagy was suppressed, the inflammatory response also weakened. Our findings provide a new perspective into the mechanisms underlying inflammatory responses induced by the environmental exposure. These findings indicate that therapeutic strategies targeting autophagy may provide a new method for the treatment of inflammatory diseases.

Type I and II Interferon Signatures Can Predict the Response to Anti-TNF Agents in Inflammatory Bowel Disease Patients: Involvement of the Microbiota

BACKGROUND

Anti-TNF agents have been a cornerstone of IBD therapy; however, response to treatment has been variable, and clinically applicable biomarkers are urgently needed. We hypothesized that the type I and type II interferon (IFN) signatures may be a confounding factor for response to antitumor necrosis factor (TNF) treatment via interactions with the host and its gut microbiota.

METHODS

Peripheral blood from 30 IBD patients and 10 healthy controls was subjected to real-time quantitative real-time polymerase chain reaction for type I and type II IFN genes (IFNGs), both at baseline and after treatment with anti-TNF. Correlation between IFN signatures and microbiota composition was also determined for a subgroup of patients and controls.

RESULTS

At baseline, type I IFN score was significantly higher in IBD patients (P = 0.04 vs controls). Responders to subsequent anti-TNF treatment had significantly lower baseline scores for both type I and II IFN signatures (P < 0.005 vs nonresponders for both comparisons). During treatment with anti-TNF, the expression of type I and II IFNGs was significantly elevated in responders and decreased in nonresponders. In addition, changes in IFN signatures correlated to specific alterations in the abundance of several microbial taxa of the gut microbiome.

CONCLUSIONS

Baseline expression of type I and II IFN signatures and their kinetics during anti-TNF administration significantly correlate to treatment responses in IBD patients. Peripheral blood IFN signatures may serve as clinically meaningful biomarkers for the identification of subgroups of patients with favorable response to anti-TNF treatment. Additionally, the distinct synergies between different IFN types and microbiota might help drive therapeutic intervention.

Cell Type- and Stimulation-Dependent Transcriptional Programs Regulated by Atg16L1 and Its Crohn's Disease Risk Variant T300A

Genome-wide association studies have identified common genetic variants impacting human diseases; however, there are indications that the functional consequences of genetic polymorphisms can be distinct depending on cell type-specific contexts, which produce divergent phenotypic outcomes. Thus, the functional impact of genetic variation and the underlying mechanisms of disease risk are modified by cell type-specific effects of genotype on pathological phenotypes. In this study, we extend these concepts to interrogate the interdependence of cell type- and stimulation-specific programs influenced by the core autophagy gene Atg16L1 and its T300A coding polymorphism identified by genome-wide association studies as linked with increased risk of Crohn's disease. We applied a stimulation-based perturbational profiling approach to define Atg16L1 T300A phenotypes in dendritic cells and T lymphocytes. Accordingly, we identified stimulus-specific transcriptional signatures revealing T300A-dependent functional phenotypes that mechanistically link inflammatory cytokines, IFN response genes, steroid biosynthesis, and lipid metabolism in dendritic cells and iron homeostasis and lysosomal biogenesis in T lymphocytes. Collectively, these studies highlight the combined effects of Atg16L1 genetic variation and stimulatory context on immune function.