Repurposing of Metormin for Older Patients with HFpEF

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Heart failure with preserved ejection fraction (HFpEF) is accepted as a geriatric syndrome and is nearly unique to older persons, particularly women. It affects 2.5 million persons, its prevalence is increasing, its prognosis is worsening, and pharmacologic trials have been negative. Our work and others’ suggest that HFpEF is initiated and promoted by systemic inflammation, which causes globally impaired organ function, including in the heart, arteries, lungs, and skeletal muscle, ultimately causing severe exercise intolerance, the primary manifestation of chronic HFpEF, impaired quality of life (QOL), hospitalization, loss of independence, and death. The source of the systemic inflammation has been unknown, but our preliminary data suggest a key role of abnormalities in the gut. Our preclinical studies show that barriers, including mucin production, are reduced in older gut causing ‘leaky gut’, which allows diffusion of bacteria and antigens from the gut into the circulation, thus causing systemic inflammation. Our clinical studies suggest that: a) older HFpEF patients have markedly reduced microbiome diversity with adverse gut microbiota that reduce production of beneficial metabolites that help maintain gut wall integrity and overall health; and b) that these abnormalities are associated with their severe exercise intolerance and are modifiable. Metformin, a generic, well-tolerated anti-diabetic medication may be an ideal candidate for repurposing for HFpEF. It has pleotropic effects against multiple aging-related mechanisms relevant to HFpEF. Our compelling preliminary data indicate that metformin strongly promotes favorable gut bacteria populations that produce beneficial metabolites, increases mucin production, and reduces leaky gut and systemic inflammation. We hypothesize that in older HFpEF patients, metformin will restore gut microbiome diversity and increase gut wall mucin, which in turn will reduce leaky gut and systemic inflammation and improve physical function. We will test this hypothesis with a randomized, blinded, placebo-controlled trial of 20 weeks of metformin in 80 older HFpEF patients > age 60 years with measurements at baseline and follow-up of physical function, QOL, microbiome diversity, markers of leaky gut, and systemic inflammation to address three Specific Aims: 1) Determine if metformin treatment improves physical function and QOL in older patients with HFpEF; 2) Determine if metformin increases microbiome diversity, mucin in the feces, and reduces markers of leaky gut in serum and inflammation in gut and blood; 3) Determine if metformin-mediated improvements in physical function and QOL are associated with increased microbiome diversity, mucin, and reduced leakiness in gut and systemic inflammatory markers. This study is well aligned with the goals of RFA-AG-22-011 and many other NIA priorities, and will be conducted by a diverse, cohesive multidisciplinary team with complementary expertise. The proposed project could have a large impact by identifying the first pharmacologic treatment to improve symptoms and exercise intolerance in the large, growing, vulnerable, under-served population of older patients with HFpEF.