Ghorpade, D. S. | bioRxiv Science

bioRxiv2024

Diabetic liver-enriched secretory dipeptidyl peptidase 4 (DPP4) fuels gut inflammation via attenuation of autophagy

The recurrent pathological inflammation of the gut is a major concern in diabetic patients. With the failure of anti-inflammatory or diabetic drugs to limit relapse of colon inflammation demands the unearthing of mechanistic details underlying higher incidences of colitis in diabetic patients. Here we report the enrichment of DPP4 in the livers and blood samples of diabetic humans and mice models of diabesity that is in parallel to the development of colitis. Overexpression of DPP4 exacerbates or hepatic silencing of DPP4 impairs experimental colitis induced by DSS and STM. Mechanistically, we identified liver DPP4 attenuates gut-autophagic response to trigger enteric cell apoptosis, reduced mucin secretion, and compromised gut barrier leading to high infiltration of immune cells secreting inflammatory cytokines establishing pathological gut inflammation. Thus, liver-DPP4-mediated gut autophagy inhibition is a key pathway in diabesitic colitis.

physiology↗

bioRxiv2024

PPARγ mediated enhanced lipid biogenesis fuels Mycobacterium tuberculosis growth in hepatocytes.

Mycobacterium tuberculosis (Mtb) infection of the lungs, besides producing prolonged cough with mucus, also causes progressive fatigue and cachexia with debilitating loss of muscle mass. While anti-tuberculosis (TB) drug therapy is directed toward eliminating bacilli, the treatment regimen ignores the systemic pathogenic derailments that probably dictate TB-associated mortality and morbidity. Presently, it is not understood whether Mtb spreads to metabolic organs and brings about these impairments. Here we show that Mtb creates a replication-conducive milieu of lipid droplets in hepatocytes by upregulating transcription factor PPAR{gamma} and scavenging lipids from the host cells. In hepatocytes, Mtb shields itself against the common anti-TB drugs by inducing drug-metabolizing enzymes. Infection of the hepatocytes in the in vivo aerosol mice model can be consistently observed post-week 4 along with enhanced expression of PPAR{gamma} and drug-metabolizing enzymes. Moreover, histopathological analysis indeed shows the presence of Mtb in hepatocytes along with granuloma-like structures in human biopsied liver sections. Hepatotropism of Mtb during the chronic infectious cycle results in immuno-metabolic dysregulation that could magnify local and systemic pathogenicity, altering clinical presentations.

microbiology↗