Alizarin as an NLRP3 inflammasome blocker ameliorates metabolic dysfunction-associated steatotic liver disease.

ETHNOPHARMACOLOGICAL RELEVANCE: Rubia cordifolia L. (known as Qiancao in Chinese herb) is a commonly used herbal medicine in clinical practice. It exhibits tropism to the Liver Meridian and is traditionally recognized for its effects in cooling blood to stop bleeding and invigorating blood circulation to dispel stasis. Alizarin, its main anthraquinone component, has shown potential for clinical application. The nucleotide oligomerization domain-like receptors containing pyrin domain 3 (NLRP3) inflammasome is a promising therapeutic target for metabolic dysfunction-associated steatotic liver disease (MASLD). This study aimed to investigate the efficacy and mechanism of alizarin in treating MASLD via inhibition of the NLRP3 inflammasome.

MATERIALS AND

METHODS

We examined the effect of alizarin on NLRP3 inflammasome activation. The roles of alizarin in regulating NLRP3 transcription and inflammasome assembly were assessed. Its influence on lipid-induced NLRP3 activation was evaluated in mouse primary hepatocytes and Kupffer cells. The therapeutic potential of alizarin in ameliorating MASLD through NLRP3 inhibition was further verified in vivo.

RESULTS

Alizarin inhibited NLRP3 inflammasome activation by reducing the cleavage of pro-IL-1β and pro-caspase-1 in mouse bone marrow-derived macrophages (BMDMs). Similar inhibitory effects were observed in BMDMs, primary hepatocytes, and Kupffer cells stimulated with LPS plus cholesterol or oleic acid/palmitic acid (OA/PA). Alizarin did not affect LPS-induced phosphorylation of P65, JNK, ERK, or P38. Mechanistically, it suppressed NLRP3 inflammasome assembly by inhibiting the interaction between NLRP3 and ASC. In a methionine-choline deficient (MCD) diet-induced mouse model of MASLD, alizarin improved liver function, reduced serum inflammatory markers, lowered histopathological inflammation scores, and attenuated liver fibrosis, likely through regulation of the NLRP3 inflammasome.

CONCLUSIONS

Alizarin inhibits NLRP3 inflammasome assembly and may serve as a potential therapeutic agent for MASLD by targeting the NLRP3 inflammasome.