Probiotics Ameliorate Atrial Fibrillation-Associated Biomarkers and Inflammation in Rats via Modulation of the Gut Microbiota and NLRP3 Inflammasome Pathway.

BACKGROUND

The gut-heart axis, particularly the role of gut microbiota and the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, is increasingly implicated in the pathogenesis of atrial fibrillation (AF). While probiotics show therapeutic potential, their mechanism in AF remains unclear.

OBJECTIVES

This study investigates whether probiotics mitigate AF pathology by restoring gut microbiota homeostasis and inhibiting NLRP3 activation.

METHODS

An AF model was induced in rats via acetylcholine (ACH)/CaCl₂ infusion. Animals were divided into five groups: Sham, AF, AF+Probiotics, AF+MCC950 (NLRP3 inhibitor), and AF+Probiotics+MCC950. We analyzed gut microbiota (16S rRNA sequencing), serum short-chain fatty acids (SCFAs; GC-MS), and the expression of NLRP3 pathway components [NLRP3, caspase-1, interleukin-1β (IL-1β)] and AF biomarkers [pentraxin 3 (PTX3), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), chemerin, galectin-3 (Gal-3)] via immunohistochemistry (IHC), Western blot, and real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

Atrial fibrillation rats exhibited gut dysbiosis, characterized by reduced diversity (Shannon index significantly decreased vs. Sham, P < 0.01), decreased beneficial bacteria (e.g., Lactobacillus), and lower SCFA levels (acetic, propionic, and butyric acids reduced by 40 - 50%, P < 0.05). Probiotics restored microbial diversity, increased SCFA production (to levels comparable to Sham, P < 0.05), and suppressed NLRP3 inflammasome activation, as evidenced by reduced levels of NLRP3, caspase-1, and IL-1β (protein and mRNA expression decreased by 50 - 70%, P < 0.01). Consequently, the expression of key AF biomarkers was significantly downregulated (PTX3, IL-6, TNF-α, chemerin, Gal-3 reduced by 40 - 60%, P < 0.05). The combined intervention of probiotics and MCC950 yielded the most pronounced effects (all markers further reduced vs. either treatment alone, P < 0.05).

CONCLUSIONS

Probiotics alleviate AF-related inflammation and biomarker expression, potentially by modulating the gut microbiota and inhibiting the NLRP3 inflammasome pathway. These findings highlight the gut-heart axis as a promising target for AF management.