Abstract

Mycoplasma gallisepticum (MG) is a pathogenic microorganism that causes chronic respiratory disease (CRD). MG infection has a serious negative impact on the poultry industry. Andrographolide (AG) is known to regulate immune responses, antimicrobial infections, and anti-inflammatory responses. However, the underlying molecular mechanisms of AG action in MG-infected chickens remain unclear. Hence, we constructed models of MG infection by using chickens and chicken macrophage-like (HD11) cells in vivo and in vitro , respectively. The results showed that AG significantly inhibited the mRNA and protein expression of the toxic adhesion protein pMGA1.2 in vivo and in vitro . Meanwhile, AG treatment significantly decreased the mRNA expression of pro-inflammatory such as interleukin-6 (IL-6) and interleukin- 1β (IL-1β), and increased the mRNA expression of an anti-inflammatory such as interleukin-10 (IL-10) and transforming growth factor beta (TGF-β) in vivo and in vitro . Furthermore, AG treatment down-regulated inflammasome NLRP3 and apoptosis genes caspase3 and caspase9, and up-regulated autophagy protein light chain 3 (LC3) by regulating the PI3K/Akt signaling pathway in vitro . Our results suggest that AG can reduce the expression of NLRP3 and alleviate the inflammatory response from MG infection by inducing autophagy, probably by modulating PI3K/Akt signaling pathway. This study demonstrates that AG can be used as a specific target to prevent and treat MG infection effectively.