NLRC5 knockdown in chicken macrophages alters response to LPS and poly (I:C) stimulation

The expression of NLRC5, IFNA, IFNB, and IL-6 genes in negative irrelevant transfection controls was up-regulated at 2 hps after LPS treatment compared to the vehicle controls. S3-siRNA effectively knocked down NLRC5 expression at 4 hps, and the expression of IFNA and IFNB (but not IL-6 and MHC class I) was also down-regulated at 4 hps in s3-siRNA transfected cells, compared to negative irrelevant transfection controls. Stimulation by LPS appeared to relatively restore the decrease in NLRC5, IFNA, and IFNB expression, but the difference is not significant.Functional characterization of chicken NLRC5 in an in vitro system demonstrated its importance in regulating intracellular molecules involved in inflammatory response. The knockdown of NLRC5 expression negatively mediates gene expression of IFNA and IFNB in the chicken HD11 cell line; therefore, NLRC5 likely has a role in positive regulation of IFNA and IFNB expression. No direct relationship was found between NLRC5 knockdown and IL-6 and MHC class I expression. Future studies will further clarify the roles of NLRC5 and other NLRs in infectious diseases of chickens and may increase the efficacy of antiviral vaccine design.The host innate immune system recognizes various pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs) through pattern-recognition receptors (PRRs) and triggers the inflammatory response to defense against microorganisms invasion [1]. There are three classes of PRRs in vertebrates, Toll-like receptors (TLRs), nucleotide-binding oligomerization (NOD)-like receptors (NLRs), and the retinoid acid-inducible gene-I (RIG-I)-like receptors (RLRs) [1-6]. These molecules showed different subcellular localization, for example, most TLRs identify extracellular PAMPs, whereas NLRs and RLRs sense intracellular PAMPs [7,8]. Recently, the NLRs have gained attention because of their involvement in mediating innate immune responses to microbial invasion and controlling inn