Abstract 15932: Lactobacillus Suppresses Glycoprotein-130-Mediated Microtubule Remodeling to Support Right Ventricular Function in Pulmonary Arterial Hypertension

Abstract

Introduction: Microtubules (MTs) are crucial for cardiomyocyte function as they regulate t-tubule structure, nuclear morphology, and gap junction protein localization. Glycoprotein-130 (GP130) signaling promotes pathological MT remodeling and right ventricular (RV) dysfunction in pulmonary arterial hypertension (PAH), but the trigger for the inflammation-MT connection is unknown. Microbiome dysbiosis activates systemic inflammation, and levels of the anti-inflammatory bacteria Lactobacillus are associated with RV function in rodents. However, the direct effects of Lactobacillus on GP130 signaling, MT remodeling, and RV function in PAH are unknown. Methods: Rats were randomly allocated into 3 groups: control, MCT-water, and MCT rats given Lactobacillus (MCT- Lactobacillus ). Echocardiography and pressure-volume loops defined RV function. Next-generation sequencing evaluated the composition of the bacterial components of the fecal microbiome. SomaScan proteomics quantified the serum proteome. RV and jejunal morphology were assessed with light and super resolution confocal microscopy. The relationship between Lactobacillus abundance and RV response to afterload was assessed in 65 PAH patients. Results: Lactobacillus augmented RV function (A) and reduced RV hypertrophy and fibrosis without altering PAH severity. Lactobacillus shifted the serum proteomic signature towards control (B) and reduced circulating GP130 ligands, normalized RV t-tubule architecture (C), MT density (D), and nucleus size (E), and prevented connexin-43 lateralization in RV cardiomyocytes (F). Lactobacillus restructured the microbiome, and concomitantly improved jejunal epithelial cell morphology with increased villus/microvillus length and glycocalyx thickness. PAH patients with fecal Lactobacillus had superior RV adaptation as afterload increased (G). Conclusion: Lactobacillus combats GP130-mediated MT remodeling to support RV function.