Humanin Mitochondrial Peptide Prevents Age-related Myocardial Fibrosis in Research

by Dr. James Ross

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Humanin (HN) is a mitochondria-derived peptide naturally produced in the body that is known for its cytoprotective actions, particularly its ability to reduce oxidative stress. In this study, researchers investigated whether prolonged administration of exogenous Humanin could prevent or reverse age-related cardiac fibrosis and cell death in the myocardium of middle-aged mice.

HNG treatment increased cardiomyocyte-to-fibroblast ratio and reduced fibrosis

Treatment with the Humanin analog HNG resulted in a measurable increase in the ratio of cardiomyocytes to fibroblasts within the aging heart. Immunofluorescence staining confirmed a higher proportion of cardiomyocytes relative to fibroblasts after HNG administration, without significant alterations in other cardiac cell populations.

Aged mouse hearts typically display elevated collagen accumulation, which contributes to fibrosis. However, picrosirius red staining demonstrated that HNG treatment markedly decreased collagen deposition in aging myocardium. Additionally, HNG suppressed cardiac fibroblast proliferation and downregulated pro-fibrotic mediators including transforming growth factor-β1 (TGF-β1), fibroblast growth factor-2 (FGF-2), and matrix metalloproteinase-2 (MMP-2). Myocardial apoptosis was also significantly reduced in HNG-treated animals, highlighting the peptide’s protective effects.

Humanin attenuates myocardial fibrosis and apoptosis via Akt/GSK-3β signaling

Cardiac fibrosis is a hallmark of aging and contributes to progressive myocardial dysfunction. For the first time, these findings demonstrated that exogenous Humanin supplementation can reduce both fibrosis and apoptosis in aging mouse hearts. Mechanistically, the protective action of Humanin analog treatment was associated with activation of the Akt/glycogen synthase kinase-3β (Akt/GSK-3β) pathway. This signaling cascade may underlie Humanin’s ability to preserve cardiac structure and function during aging.

HNG suppressed interstitial fibrosis and limited fibroblast proliferation in the aging heart

Quantitative analysis of collagen deposition revealed significant interstitial fibrosis in aged mice compared to young controls (0.24 ± 0.06% vs. 0.02 ± 0.01%, P < 0.01). HNG treatment reduced collagen accumulation in aged hearts to 0.07 ± 0.03% (P < 0.05). Interestingly, perivascular fibrosis did not differ significantly across groups, suggesting that Humanin’s anti-fibrotic activity may be more pronounced in interstitial tissue.