ORMDL3 regulates NLRP3 inflammasome activation by maintaining ER-mitochondria contacts in human macrophages and dictates ulcerative colitis patient outcome.

Genome-wide association studies in inflammatory bowel disease have identified risk loci in the orosomucoid-like protein 3/ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3) gene to confer susceptibility to ulcerative colitis (UC), but the underlying functional relevance remains unexplored. Here, we found that a subpopulation of the UC patients who had higher disease activity shows enhanced expression of ORMDL3 compared to the patients with lower disease activity and the non-UC controls. We also found that the patients showing high ORMDL3 mRNA expression have elevated interleukin-1ß cytokine levels indicating positive correlation. Further, knockdown of ORMDL3 in the human monocyte-derived macrophages resulted in significantly reduced interleukin-1ß release. Mechanistically, we report for the first time that ORMDL3 contributes to a mounting inflammatory response via modulating mitochondrial morphology and activation of the NLRP3 inflammasome. Specifically, we observed an increased fragmentation of mitochondria and enhanced contacts with the endoplasmic reticulum (ER) during ORMDL3 over-expression, enabling efficient NLRP3 inflammasome activation. We show that ORMDL3 that was previously known to be localized in the ER also becomes localized to mitochondria-associated membranes and mitochondria during inflammatory conditions. Additionally, ORMDL3 interacts with mitochondrial dynamic regulating protein Fis-1 present in the mitochondria-associated membrane. Accordingly, knockdown of ORMDL3 in a dextran sodium sulfate -induced colitis mouse model showed reduced colitis severity. Taken together, we have uncovered a functional role for ORMDL3 in mounting inflammation during UC pathogenesis by modulating ER-mitochondrial contact and dynamics.

The gut-liver-kidney axis: Novel regulator of fatty liver associated chronic kidney disease.

Increased interest in understanding the liver-kidney axis in health and disease during the last decade unveiled multiple recent evidence that suggested a strong association of fatty liver diseases with chronic kidney disease (CKD). Low-grade systemic inflammation is thought to be the major contributing factor to the pathogenesis of CKD associated with fatty liver. However, other contributing factors largely remained unclear, for example, gut microbiota and intestinal barrier integrity. Homeostasis of the gut microbiome is very crucial for the health of an individual. Imbalance in the gut microbiota leads to various diseases like fatty liver disease and CKD. On the contrary, disease conditions can also distinctly change gut microbiota. In this review, we propose the pathogenic role of the gut-liver-kidney axis in the development and progression of CKD associated with chronic fatty liver diseases, either non-alcoholic fatty liver disease or non-alcoholic steatohepatitis in experimental models and humans. Further, we discuss the therapeutic potential and highlight the future research directions for therapeutic targeting of the gut-liver-kidney axis.

Role of mitochondria in regulating immune response during bacterial infection.

Mitochondria are dynamic organelles of eukaryotes involved in energy production and fatty acid oxidation. Besides maintaining ATP production, calcium signaling, cellular apoptosis, and fatty acid synthesis, mitochondria are also known as the central hub of the immune system as it regulates the innate immune pathway during infection. Mitochondria mediated immune functions mainly involve regulation of reactive oxygen species production, inflammasome activation, cytokine secretion, and apoptosis of infected cells. Recent findings indicate that cellular mitochondria undergo constant biogenesis, fission, fusion and degradation, and these dynamics regulate cellular immuno-metabolism. Several intracellular pathogens target and modulate these normal functions of mitochondria to facilitate their own survival and growth. De-regulation of mitochondrial functions and dynamics favors bacterial infection and pathogens are able to protect themselves from mitochondria mediated immune responses. Here, we will discuss how mitochondria mediated anti-bacterial immune pathways help the host to evade pathogenic insult. In addition, examples of bacterial pathogens modulating mitochondrial metabolism and dynamics will also be elaborated. Study of these interactions between the mitochondria and bacterial pathogens during infection will lead to a better understanding of the mitochondrial metabolism pathways and dynamics important for the establishment of bacterial diseases. In conclusion, detailed studies on how mitochondria regulate the immune response during bacterial infection can open up new avenues to develop mitochondria centric anti-bacterial therapeutics.

CLUH functions as a negative regulator of inflammation in human macrophages and determines ulcerative colitis pathogenesis.

Altered mitochondrial function without a well-defined cause has been documented in patients with ulcerative colitis (UC). In our efforts to understand UC pathogenesis, we observed reduced expression of clustered mitochondrial homolog (CLUH) only in the active UC tissues compared with the unaffected areas from the same patient and healthy controls. Stimulation with bacterial Toll-like receptor (TLR) ligands similarly reduced CLUH expression in human primary macrophages. Further, CLUH negatively regulated secretion of proinflammatory cytokines IL-6 and TNF-α and rendered a proinflammatory niche in TLR ligand-stimulated macrophages. CLUH was further found to bind to mitochondrial fission protein dynamin related protein 1 (DRP1) and regulated DRP1 transcription in human macrophages. In the TLR ligand-stimulated macrophages, absence of CLUH led to enhanced DRP1 availability for mitochondrial fission, and a smaller dysfunctional mitochondrial pool was observed. Mechanistically, this fissioned mitochondrial pool in turn enhanced mitochondrial ROS production and reduced mitophagy and lysosomal function in CLUH-knockout macrophages. Remarkably, our studies in the mouse model of colitis with CLUH knockdown displayed exacerbated disease pathology. Taken together, this is the first report to our knowledge explaining the role of CLUH in UC pathogenesis, by means of regulating inflammation via maintaining mitochondrial-lysosomal functions in the human macrophages and intestinal mucosa.

Swertia purpurascens Wall ethanolic extract mitigates hepatic fibrosis and restores hepatic hepcidin levels via inhibition of TGFß/SMAD/NFκB signaling in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Swertia purpurascens Wall belongs to a well-known genus in traditional systems of medicine worldwide. In folklore, it is used to treat various ailments, including hepatic disorders, as an alternative to the endangered species Swertia chirayita. However, the therapeutic potential of Swertia purpurascens Wall against hepatic fibrosis has not been validated yet. AIM OF THE STUDY: The present study was planned to evaluate the efficacy of the Swertia purpurascens Wall extract (SPE) against hepatic fibrosis and elucidate the underlying mechanism of action. MATERIALS AND METHODS: The metabolite profiling of the SPE was done using UHPLC-QTOF-MS/MS. The acute oral toxicity study of SPE at 2 g/kg BW dose was done in rats. Further, the liver fibrosis was induced by the CCl4 intoxication, and the efficacy of SPE at three doses (100, 200 and 400 mg/kg BW) was evaluated by studying biochemical parameters, histopathology, immunohistochemistry, qRT-PCR, western blotting and in silico analysis. RESULTS: UHPLC-QTOF-MS/MS analysis revealed the presence of a total of 23 compounds in SPE. Acute oral toxicity study of SPE at 2 g/kg BW showed no harmful effects in rats. Further, the liver fibrosis was induced by the CCl4 administration, and the efficacy of SPE was evaluated at three doses (100, 200 and 400 mg/kg BW). SPE treatment significantly improved the body weight gain, the relative liver weight, serum liver injury markers and endogenous antioxidant enzyme levels in the CCl4-treated rats. SPE also recovered the altered liver histology and effectively reduced the fibrotic tissue deposition in the hepatic parenchyma. Further, SPE significantly inhibited the fibrotic (TGFß, αSMA, SMADs and Col1A), proinflammatory markers (NFκB, TNFα and IL1ß) and apoptosis in the liver tissue. Interestingly, SPE treatment also restored the altered hepcidin levels in the liver tissue. In silico study revealed the potential of various metabolites as drug candidates and their interaction with target proteins. CONCLUSION: Altogether, SPE showed its therapeutic potential against CCl4-induced hepatic fibrosis by restoring the hepatic hepcidin levels and inhibiting TGFß/SMAD/NFκB signaling in rats.

A machine learning-based approach to determine infection status in recipients of BBV152 (Covaxin) whole-virion inactivated SARS-CoV-2 vaccine for serological surveys.

Data science has been an invaluable part of the COVID-19 pandemic response with multiple applications, ranging from tracking viral evolution to understanding the vaccine effectiveness. Asymptomatic breakthrough infections have been a major problem in assessing vaccine effectiveness in populations globally. Serological discrimination of vaccine response from infection has so far been limited to Spike protein vaccines since whole virion vaccines generate antibodies against all the viral proteins. Here, we show how a statistical and machine learning (ML) based approach can be used to discriminate between SARS-CoV-2 infection and immune response to an inactivated whole virion vaccine (BBV152, Covaxin). For this, we assessed serial data on antibodies against Spike and Nucleocapsid antigens, along with age, sex, number of doses taken, and days since last dose, for 1823 Covaxin recipients. An ensemble ML model, incorporating a consensus clustering approach alongside the support vector machine model, was built on 1063 samples where reliable qualifying data existed, and then applied to the entire dataset. Of 1448 self-reported negative subjects, our ensemble ML model classified 724 to be infected. For method validation, we determined the relative ability of a random subset of samples to neutralize Delta versus wild-type strain using a surrogate neutralization assay. We worked on the premise that antibodies generated by a whole virion vaccine would neutralize wild type more efficiently than delta strain. In 100 of 156 samples, where ML prediction differed from self-reported uninfected status, neutralization against Delta strain was more effective, indicating infection. We found 71.8% subjects predicted to be infected during the surge, which is concordant with the percentage of sequences classified as Delta (75.6%-80.2%) over the same period. Our approach will help in real-world vaccine effectiveness assessments where whole virion vaccines are commonly used.

Modulation of host mitochondrial dynamics during bacterial infection.

Mitochondria is a dynamic organelle of the cell that can regulate and maintain cellular ATP level, ROS production, calcium signaling and immune response. In order to retain their shape and distribution, mitochondria go through coordinated cycles of fission and fusion. Further, dysfunctional mitochondria are selectively eliminated from the cell via mitophagy to synchronize mitochondrial quality control and cellular homeostasis. In addition, mitochondria when in close proximity with the endoplasmic reticulum can alter the signaling pathways and some recent findings also reveal a direct correlation between the mitochondrial localization in the cell to the immune response elicited against the invading pathogen. These modulations in the mitochondrial network are collectively termed as 'mitochondrial dynamics'. Diverse bacteria, virus and parasitic pathogens upon infecting a cell can alter the host mitochondrial dynamics in favor of their multiplication and this in turn can be a major determinant of the disease outcome. Pharmacological perturbations in these pathways thus could lead to generation of additional therapeutic opportunities. This review will focus on the pathogenic modulation of the host mitochondrial dynamics, specifically during the bacterial infections and describes how dysregulated mitochondrial dynamics facilitates the pathogen's ability to establish efficient infection.