Modulatory roles of proinflammatory cytokines on the expression of cathelicidins in the lower regions of the oviduct of laying hens

The current study aimed to confirm and examine the physiological roles of the proinflammatory cytokines IL1B and IL6 on the immune functions which mediated by cathelicidins (CATHs) in the uterus and vagina of laying hens. Snaps of the mucosal tissues of uterus and vagina were incubated in culture medium or chicken recombinant IL1B and IL6 for 1.5 h or 3 h before extraction of total RNA to be used for examination of IL1B and IL6, their receptors, and cathelicidins by semi-quantitative PCR; and to examine the changes in cathelicidins expressions by real-time PCR. PCR analysis confirmed that IL1B and IL6, their receptors, and CATH1-3 were expressed in the mucosal tissues of the uterus and vagina. In uterus tissue, IL1B did not affect the expression of CATH1 and −2 at different doses and incubation time, whereas CATH3 was significantly downregulated by incubation with IL1B for 1.5 h. In the vaginal tissue, the expressed CATH1, −2 and −3 were significantly upregulated by incubation with IL1B for 1.5 h in a dose-dependent manner. In uterus tissue, CATH1 expression was down-regulate by IL6 incubation for 1.5 h, but not by 3 h however, CATH3 expression was significantly increased by incubation with IL6 for 1.5 h, but not for 3 h. In the vaginal tissues, all CATHs expression was not affected significantly by incubation with IL6. These current observations suggest that CATH1, −2 and −3 in the vagina are upregulated by IL1B, and CATH3 in the uterus is also upregulated by IL6. IL1B and IL6 synthesized in response to infection by the microbes may enhance the defense system in the oviduct mucosal tissues by increasing the synthesis of CATHs.