Expression of β-defensins in intestines of chickens injected with vitamin D3 and lipopolysaccharide.

The objective of this study was to evaluate the effect of vitamin D3 (VD3) on the regulation of chicken intestinal β-defensin genes under normal and lipopolysaccharides (LPS) conditions. Four treatment groups were used, including a negative control group, VD3-injection group, LPS-injection group, and both VD3-injection and LPS-injection group. At 4, 24, and 48 h post-injection, intestines were collected and RNA was isolated to measure the chicken β-defensin genes with putative vitamin D responsive elements using quantitative polymerase chain reaction. Expressions of all 7 chicken β-defensin genes was detectable in the intestines. Significant increases in GAL-6, -7 and -9 were found following LPS injection treatment at 4, 24, and 48 h post-injection, respectively, whereas VD3 injection did not affect the expression of any investigated genes under normal conditions. However, the expression of GAL-4, -5, -6, and -10 were synergistically upregulated by VD3 in combination with LPS. These results suggest that VD3 enhances the immune immunity during LPS challenge by inducing the expression of chicken β-defensin genes when birds are exposed to immune stressors.