Effects of Dietary Selenium on Inflammation and Hydrogen Sulfide in the Gastrointestinal Tract in Chickens

Selenium (Se) is an essential trace element for humans and animals and is associated with many physiological functions. Previous studies have shown that low-Se diet may affect inflammatory cytokine productions and histology in the digestive system and that sulfide hydrogen (H2S) may contribute to the protection against tissue injury and the inhibition of inflammation in the gastrointestinal tract. In this study, we investigated the relationship between Se deficiency-induced inflammation and H2S production in the small intestine in chickens. One hundred twenty 1-day-old chickens were fed with diets with different Se concentrations (0.15 mg/kg in the control and 0.028 mg/kg in the low-Se-diet group). Chickens were euthanized and small intestinal tissues were extracted. We observed histology, measured H2S concentration, and evaluated the mRNA expression of H2S-producing enzymes cystathionine gamma-lyase (CSE), cystathionine beta-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MST), and inflammatory factors TNF-alpha, NF-kappa B p50, COX-2, and PTGES. Our results showed that chickens fed with low-Se diet exhibited histological changes, lower H2S production, and lower mRNA expression of H2S-producing enzymes (CSE, CBS, and 3-MST) whereas higher mRNA expression of intestinal inflammatory factors (TNF-alpha, NF-kappa B p50, COX-2, and PTGES) compared to controls. Our results indicate that low-Se diet could impact H2S, H2S-producing enzymes, and inflammatory factors in the small intestine, implying that Se is important in maintaining intestinal functions and H2S production is downregulated in Se deficiency-induced inflammation. The downregulation exacerbates the inflammation and impacts H2S-mediated intestinal functions.