NLRP3 Inflammasome Activation is a Prognostic Marker of Recovery in HEV-Infected Patients.

Abstract

Hepatitis E contributes to 3.3 million acute hepatitis cases worldwide with 30% mortality in pregnant women. Pathogenesis of Hepatitis E is complex; thus, the present study was aimed at inflammasomes and associated cytokines in the immunopathogenesis of viral hepatitis E. PBMCs were isolated from 45 HEV IgM/HEV RNA-positive AVH/ALF and 19 healthy individuals and processed for mRNA expressions of NLRs, RLRs, and cytokines. PBMCs were cultured and stimulated with HEV-pORF-2 peptide in vitro for mRNA expression by RT-PCR and cytokines levels in serum/culture supernatant by ELISA. siRNA transfection and post-silencing effect in AVH PBMCs were also assessed by NLRP3 gene expression and IL-1β and IL-18 levels by ELISA. The results demonstrated high viral load in ALF than AVH cases. mRNA expression of NLRP3 in AVH patients was found to be positively correlated with IL-18 (r = 0.74) and IL-1β (r = 0.68); P < 0.0001***. Significant levels of serum IL-1β and IL-18 cytokines were observed in AVH as compared to ALF patients. The levels of IL-1β in the culture supernatant in mock and stimulated conditions were significantly higher in AVH than in ALF patients. Significant downregulation in NLRP3 gene expression was correlated with the reduced levels of IL-1β and IL-18 cytokines in NLRP3-siRNA-transfected PBMCs. This study highlighted the significance of upregulated NLRP3 inflammasome leading to increased production of IL-18 and IL-1β cytokines in sera of AVH patients. Thus, it indicated the role of Th1 response acting through the NLRP3 pathway which might have been helpful in the recovery of AVH patients. These promising results open multiple treatment avenues where specific inhibitors can be designed to modulate the progress of disease and its pathogenicity.