Andrographolide Inhibits Expression of NLPR3 Inflammasome in Canine Mononuclear Leukocytes

Inflammasomes are multiprotein complexes that trigger processes through caspase-1 activation, leading to the maturation of proinflammatory cytokines, such as IL-1β and IL-18. The gene encoding the inflammasome stimulatory protein NLRP3 is conserved in canines. Caspase-1/4 homologues have been identified in multiple carnivores, including canines, and caspase-1 activity has been shown in humans. The NLRP3 inflammasome has also been described in some canine inflammatory diseases. Andrographolide, a labdane diterpene, is the principal active ingredient in the herb Andrographis paniculate. The objective of this study was to determine the effect of andrographolide on the gene expression of the components of the NLRP3 inflammasome, proinflammatory cytokines, and IL-1β secretion in canine peripheral blood mononuclear cells. For this, MTT assays and real-time PCR were employed to assess the cytotoxicity and gene expression. Further, an ELISA test was performed to measure the IL-1β concentration. The findings reveal that andrographolide significantly reduces the expression of NLRP3, caspase-1/4, IL-1β, and IL-18. Additionally, it decreases the secretion of IL-1β and other proinflammatory cytokines, including IL-6, IL-8, and TNF-α. The results show that andrographolide decreases the expression of NLRP3, caspase-1/4, IL-1β, and IL-18. Andrographolide also reduces proinflammatory cytokines expression, and decreases IL-1β secretion. This indicates that andrographolide can interfere with the activation and function of the inflammasome, resulting in a decrease in the inflammatory response in canines. Research in this area is still budding, and more studies are necessary to fully understand andrographolide's mechanisms of action and its therapeutic potential in relation to the NLRP3 inflammasome in dogs.