Objective: To explore the effects of HFD on male reproductive tissues, and the mechanism of pyruvate carboxylase(PC)-mediated macrophage polarization regulation of male reproductive function under HFD.
To provide a new metabolism-immune regulation mechanism for obesity-induced male infertility.
Methods: By establishing an obese mice model induced by HFD, the effects of HFD on metabolism and systemic organs in mice were studied, and their reproductive function was tested. Flow cytometry was performed to detect the number and polarization of macrophages in the male reproductive tissues of HFD and normal diet (ND) mice. RNA-Seq sequencing was performed on male reproductive tissues to analyze differential genes and validated through fluorescence quantitative PCR. A co-culture system was established for macrophages and adipocytes, which were treated adipocytes with different concentrations of PC inhibitors, namely Erianin (Eri), the number and polarization of macrophages were measured.
Results: ①Compared with the ND group mice, the HFD group mice showed a significant increase in body weight and blood sugar, disrupted lipid metabolism, and altered organ morphology. The morphological changes in the testes and epididymis of mice fed with HFD diet resulted in a decrease in sperm quality. ②Flow cytometry analysis showed that HFD induced an increase in the number of macrophages in epididymal adipose tissue and epididymal tissue, and differentiated towards M1 type.This was accompanied by an increase in local inflammatory factors in mouse epididymal fat tissue and epididymal caput tissue. The RNA seq sequencing results showed that the expression of PC gene increased most significantly in epididymal fat. ③When mature adipocytes and macrophages are co-cultured in vitro, they can significantly increase the number of macrophages and polarize towards the M1 type. Eri can inhibit macrophage proliferation and polarization towards the M1 type, and the inhibitory effect becomes more pronounced as the concentration of Eri increases.
Conclusions: The sperm motility and sperm viability of obese mice induced by HFD were significantly reduced. HFD-induced obesity resulted in a significant increase in the expression of adipose tissue PC in the epididymis, inducing polarization of epididymal macrophages towards M1 type, thus leading to local chronic inflammation of the epididymis and damaging sperm quality and male reproductive function.
