Role of Intestinal Proteostasis mediator HSP90 in alcoholic liver disease.

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ABSTRACT Chronic alcohol alters the enteric microbiome (dysbiosis), induces inflammation, impairs the gut barrier function resulting in a “leaky” gut, passage of microbial products into portal circulation and eventually liver inflammation. Current therapies targeting the microbiome or host pathways to restore barrier function have utilized antibiotics, probiotics, synbiotics, fecal microbiome transplant (FMT), bacteriophage therapy, FXR agonists and nutrient- based treatments. The major goal of this proposal is to investigate the pathogenic role of proteostasis mediator, HSP90 in the gut by intestinal targeting in vivo using specific pharmacological inhibitors to evaluate its effect on alcohol mediated host intestinal inflammation, barrier function and dysbiosis. Two predominant forms of mammalian stress inducible HSP90 paralogs are cytoplasmic (CYT) HSP90AA1 and HSP90B1/GP96 in the endoplasmic reticulum (ER). The chaperone function of HSP90 and GP96 is crucial in fine tuning immune cell activation and inflammatory responses. The precise role of proteostasis chaperones such as HSP90 in chronic alcohol mediated intestinal dysfunction is not yet investigated. We reported that targeting HSP90 using specific pharmacological inhibitor 17-DMAG, reduced gut derived circulating endotoxin in ALD. Myeloid specific HSP90B1/GP96 deficient mice also exhibit reduced circulating endotoxin in ALD. Further our preliminary data show induction of HSP90AA1 and HSP90B1/GP96 mRNA in intestine of chronic alcohol exposed mice. In addition, 17-DMAG is bioavailable in the intestine and inhibits inflammatory cytokine, TNFα in the jejunum and ileum. We hypothesize that chronic alcohol induces HSP90 in host intestine contributing to inflammation and compromising gut barrier function in ALD. In addition, since therapeutic targeting of gut inflammation can restore protective microbiota, as well as considering the antibiotic and antimycotic properties of 17-DMAG, it is likely that 17-DMAG treatment favors protective gut microbiota, facilitated by reduced host intestinal inflammation. Collectively, here we will explore the role of HSP90 in alcohol mediated gut inflammation and barrier function and also assess whether pharmacological targeting of host HSP90 impacts gut microbiota. The Specific Aims are: 1) To delineate the role of HSP90 isoforms on alcohol induced gut inflammation by- Evaluating expression of HSP90 isoforms, intestinal targeting of HSP90 using 17-DMAG encapsulated nanoparticles to study inflammatory responses in small intestine and immune cells in lamina propria and assessing whether myeloid specific HSP90B1/GP96 deficiency affects inflammatory responses in the gut. 2) To assess the functional relevance of HSP90 on alcohol mediated intestinal barrier integrity and dysbiosis by - Evaluating permeability and epithelial tight junction proteins during HSP90 and myeloid GP96 inhibition. B) Assessing the effect of intestine targeted nano-DMAG and myeloid GP96 deficiency on microbiota. Successful completion of the proposed studies will uncover the role of proteostasis chaperones in the gut and guide future studies to identify proteostasis pathways in alcohol mediated gut injury.