The attenuating effects of serine against cadmium induced immunotoxicity through regulating M1/M2 and Th1/Th2 balance in spleen of C57BL/6 mice.

Cadmium (Cd) has adverse effects on organisms. Serine is an essential nutritional factor and its nutritional value is extremely high for body. To explore the effects of serine on spleen toxicity induced by Cd in mice, cadmium chloride (CdCl2, 50 mg/L) and serine (50 g/L) were individually administered or co-administrated in drinking water of mice for 18 weeks. Results demonstrated that Cd exposure induced splenic toxicity and serine against the toxicity damage caused by Cd in mice. Under Cd stress, trace element homeostasis was disturbed, the mice's body weight and spleen index were increased, and splenic morphology and ultrastructure were altered. Furthermore, Cd exposure led to the cell populations disorder, which in turn triggers cell death. Notably, Cd treatment induced oxidative stress and inflammation, increased M1/M2 (iNOS, CD68) and Th1/Th2 (T-bet, CD4) levels, decreased M1/M2 (Arg1) and Th1/Th2 (GATA3) levels, while disrupted the macrophages and lymphocytes homeostasis, which trigged apoptosis and pyroptosis in spleen. In contrast, serine supplementation changed the levels of Cd and other elements, weakened Cd-induced tissue damage and inflammation, enhanced antioxidant capacity, significantly restored cell homeostasis, and effectively inhibited Cd-induced apoptosis and pyroptosis in the spleen. Shortly, the results verified that serine had an ameliorating toxicity effect and restored the M1/M2 and Th1/Th2 balance, restrained apoptosis and pyroptosis induced by Cd.