High throughput proteomic analysis of Labeo rohita liver infected with Edwardsiella tarda

Abstract

The liver is a multifunctional organ and very crucial for pathogenicity and toxicological analysis in fish. In this study, histopathological and proteomic analysis of liver tissue was performed to overview the changes in tissue anatomy and proteome profile following Edwardsiella tarda (Et) infection. The differential proteomic response against Et infection was investigated using label free quantitative proteomics. Compared to the control tissue, the histopathological changes in bacterial challenged group (ET) include hepatocyte enlargement and melanomacrophage centre (MMC) aggregation in response to disease. With the proteomic analysis, a total of 1275 proteins were identified of which 257 were found to be differentially expressed proteins (DEP) between the control and ET group. Functional analysis of DEPs using STRING and metascape tools revealed expression of proteins belonging to different pathways like ribosome, protein processing in the endoplasmic reticulum (rpl5a), metabolic pathways (acss2, prodha, cyp51a), oxidative phosphorylation (uqcrfs1, ndufb10, atp6v0d1), proteasome (psmd3), and N-glycan biosynthesis (dpm1) pathways. Proteins involved in response to the Et infection activate downstream processes of apoptosis, inflammatory cytokines (TIR, chp1, apoa1), MAC (c9, c5, c8a), PPAR signalling (acsl4), APR (a2m1, cp), and T-cell activation (Ilf2). A targeted proteomics approach (MRM) was used in rohu livers to validate differentially expressed proteins (itln2, steap4, gst, psap) involved in Et pathogenesis. Our results showed the putative histopathological effects of Et infection on liver tissue and insights into the metabolic and immune pathway-associated proteins that play a role during Et infection, thereby highlighting a potential way of enhancing fish immunity against bacteria. Our comprehensive liver proteome findings would contribute to understanding pathogenesis and revealing novel disease markers for rohu liver in Et infection.