LPS-induced NLRP3 gene expression in chicken

NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) is a cytosolic sensor that detects many microbial pathogen-associated molecular patterns and damage-associated molecular patterns. It works as a pro-inflammatory cytokine that is encoded in the NLRP3 gene. This protein is profoundly expressed in macrophage and other innate immune system cells, and participates in the assembly of NLRP3 inflammasome. NLRP3 inflammasome activates caspase-1, which in turn renders the inactive precursors of the pro-inflammatory cytokines, the interleukin-1β (IL-1β) and the IL-18, into active forms. This cytokine may trigger many inflammatory responses and cell signaling pathways as well. Little is known about this cytokine in chickens, especially its role in vaccines or induced immune responses.

In this article, we sought to determine the presence of this gene mRNA in selected organs of male and female commercial, brown leghorn egg-type chickens. In addition, we sought to determine this gene's potential expression in these organs upon stimulation.

Using real-time polymerase chain reaction, first we tested the presence of the NLRP3 gene in the chickens. Second, the levels and the time course of NLRP3 gene expression have been tested after stimulation with bacterial lipopolysaccharide (LPS) for 12, 24, and 48 hours postinoculation (pi). One-hundred twenty, day-old males and females egg-type brown leghorn chickens were used for the study.

Our results showed that the gene mRNA is actually present in chickens solely. Also, there were no significant differences in the density of the expression and the distribution of the expression of the NLRP3 between male and female chickens and among different organs. Upon stimulation with LPS administration, however, there were marked elevations in the gene expression rates in small intestine, large intestine, gizzard, liver, lung, spleen, and Peyer's patches 12 hours pi. This elevation continued to elevate 24 hours pi. However, the significance of the expression was only recorded in the small intestine, large intestine, and with less significance, in Peyer's patches and spleen. This elevation in expression subsided and almost returned to normal within these organs 48 hours pi.

The results suggest that there were no significant differences in the NLRP3 gene expression between male and female. Upon stimulation, the course of the gene expression showed a time-dependent response. First, the dominance in the NLRP3 gene mRNA expression was in the small intestine and gizzard. Similarly, but less profoundly, the large intestine, Peyer's patches, and spleen expressed NLRP3 mRNA 12 and 24 hours pi with LPS. Secondary immune organs, lungs, small intestine, and large intestine expressed the NLRP3 mRNA significantly 24 hours pi. All the levels had diminished and almost returned to normal 48 hours pi.