iTRAQ-based quantitative proteomics analysis of the spleen reveals innate immunity and cell death pathways associated with heat stress in broilers (Gallus gallus).

Heat stress induces immune dysfunction and cell death, but the mechanisms by which this occurs are not fully understood. Therefore, the isobaric tags for relative and absolute quantification (iTRAQ) was used to identify differentially abundant proteins (DAPs) in the spleen between heat-stressed group and control group, and real time qPCR (RT-qPCR), and Parallel Reaction Monitoring (PRM) were performed to validate the differentially abundant proteins of interest. The results showed that nine down regulated DAPs related to innate immunity were enriched in the Toll-like receptor signaling pathway (IRF3 and CD40), NOD-like receptor signaling pathway (TNFAIP3, IL-18, CathL2, IRF3, IAP3 and CYBA), RIG-I-like receptor signaling pathway (TRIM25 and IRF3), and Cytosolic DNA-sensing pathway (IL-18, POLR3F and IRF3). Six down or up regulated DAPs related to cell death were enriched in apoptosis (CTSD, PARP3 and IAP3), ferroptosis (FTH) and necroptosis (FTH, CHMP1B, TNFAIP3, PARP3 and IAP3). In addition, compared with control group, heat stress significantly increased serums IL-1β, IL-6, TNF-α, and IFN-α, as well as the splenocyte apoptosis rate, whereas significantly decreased serum IFN-β. Taken together, these findings indicate that heat stress inhibits innate immunity and induces cell death through different pathways. SIGNIFICANCE: Our study identified potential signaling pathways and differentially abundant proteins related to the innate immunity and cell death of broilers under high temperature. These findings will facilitate a better understanding of the mechanisms of broiler response to heat stress and provide possible targets for alleviating heat stress in broiler production.