Emerging data demonstrate systemic and local inflammation regulate right ventricular (RV) adaption in preclinical and human pulmonary arterial hypertension (PAH). Pathological RV inflammation is targetable as antagonism of glycoprotein-130 (GP130) signaling counteracts pathological microtubule remodeling and improves RV function in rodents. Microtubules control several aspects of cardiomyocyte biology including cellular and nuclear size/structure, t-tubule homeostasis, and the proper localization of connexin-43. The intestinal microbiome regulates systemic inflammation, but the impact of the gut microbiome on the GP130-microtubule axis in RV failure is unknown. Here, we examined how the anti-inflammatory bacteria, Lactobacillus , modulated cellular and physiological RV phenotypes in preclinical and clinical PAH. Lactobacillus supplementation restructured the gut micro/mycobiome, suppressed systemic inflammation, combatted pathological GP130-mediated RV cardiomyocyte microtubule remodeling, and augmented RV function in rodent PAH. Moreover, Lactobacillus was associated with superior RV adaption in human PAH. These data further support the hypothesis that inflammation negatively impacts RV adaption in PAH, and identify the gut microbiome as a potentially targetable regulator of RV function in PAH.