High-Fat Diet Induces Inflammatory Injury in Mice Sertoli Cells via the IRE1α/TRAF2 Axis to Activate the NF-κB Signaling Pathway.

High-fat diet (HFD), characterized by an increased proportion of palmitic acid (PA), can induce inflammatory responses in Sertoli cells, trigger apoptosis, and cause spermatogenic dysfunction. Endoplasmic reticulum stress (ERS) is intimately linked to inflammation, but whether ERS contributes to HFD-induced Sertoli cell inflammatory injury remains unclear. This study investigated how HFD and PA mediated Sertoli cell injury by upregulating inflammatory response at the in vivo and cellular levels. Obese mice and TM4 cell models were established using HFD and PA, respectively. The sperm quality of mice was systematically assessed. Key regulatory pathways were identified via transcriptome sequencing, and the mechanism underlying HFD-induced Sertoli cell injury was validated using Western blot and flow cytometry. The results showed that HFD could upregulate the expression of inflammatory cytokines in Sertoli cells by activating the NF-κB signaling pathway, ultimately leading to a reduction in Sertoli cell numbers. Through transcriptome sequencing, we found that PA could activate ERS in TM4 cells. After inhibiting the activity of ERS transmembrane protein inositol-requiring 1α (IRE1α), the apoptosis rate, inflammatory cytokine production, and the expression levels of NF-κB signaling pathway proteins in PA-stimulated TM4 cells were significantly decreased. Notably, inhibition of IRE1α protein activity significantly downregulated the expression of adaptor protein tumor necrosis factor 2 (TRAF2). Knocking down TRAF2 reduced the expression of both NF-κB signaling pathway proteins and inflammatory cytokines. Overall, this study provides a theoretical basis for preventing and treating HFD-induced male reproductive dysfunction by targeting the IRE1α/ TRAF2/NF-κB axis.