NLRP3 inflammasome pathway activation is associated with cardiac remodeling, gut microbiota dysbiosis, and dietary protein restriction in a rat heart failure model: an integrative exploratory analysis.

Objective: To characterize protein expression of NLRP3 inflammasome pathway components (NLRP3, TXNIP, ASC, IL-1β, IL-18, Caspase-1) in failing myocardium alongside exploratory mRNA profiling, elucidate their correlation with gut microbiota 16S rRNA gene profiles and the metabolite trimethylamine N-oxide (TMAO), and evaluate how dietary protein restriction and probiotic intervention modulate these pathways to influence heart failure progression. Methods: Five groups of male SD rats were established: Control, HF, HF + Pro, LHF, and LHF + Pro, using abdominal aortic constriction. Comprehensive genomic and molecular analyses included: (1) quantitative real-time PCR (qRT-PCR) profiling of six key inflammasome genes (NLRP3, TXNIP, ASC, IL-1β, IL-18, Caspase-1); (2) Western blot protein quantification of the NLRP3 pathway; (3) gut microbiota 16S rRNA gene sequencing (V3-V4 region, Illumina NovaSeq); (4) serum biomarker enzyme-linked immunosorbent assay (IL-18, IL-1β, TNF-α, brain natriuretic peptide, TMAO); and (5) histopathological and ultrastructural analysis of myocardial tissue. Results: Serum IL-18 protein levels were significantly elevated in the LHF group compared to controls (P < 0.05) by ELISA, with the most pronounced increase observed under dietary protein restriction; however, IL-18 mRNA expression by qRT-PCR showed directionally consistent but statistically non-significant trends across groups (P = 0.929, n = 3 per group). TMAO levels were decreased in HF and HF + Pro groups but paradoxically elevated in the LHF group, a finding discussed in detail in the context of dietary substrate availability and hepatic FMO3 activity. Western blot results showed that the expression of NLRP3, TXNIP, ASC, IL-1β, and IL-18 proteins increased in all heart failure groups compared to the control group, with the most significant increase in the low-protein diet group. Pathological examination revealed increased myocardial fibrosis in heart failure groups, which was further aggravated by low-protein diet, while probiotic intervention partially improved these pathological changes. Conclusion: Heart failure is associated with upregulation of NLRP3 inflammasome proteins (NLRP3-TXNIP-ASC-IL-1β/IL-18 axis) alongside gut microbiota dysbiosis; mRNA-level trends were directionally consistent but did not reach statistical significance. Low-protein diet markedly amplifies inflammasome protein expression and cardiac remodeling, while probiotic supplementation is associated with reduced NLRP3 pathway protein expression through microbiome restoration. These findings suggest NLRP3-related protein signatures as candidate biomarkers and potential therapeutic targets in heart failure, warranting further mechanistic investigation.