ALKBH5-mediated m6A modification of IL-11 drives macrophage-to-myofibroblast transition and pathological cardiac fibrosis in mice.

Cardiac macrophage contributes to the development of cardiac fibrosis, but factors that regulate cardiac macrophages transition and activation during this process remains elusive. Here we show, by single-cell transcriptomics, lineage tracing and parabiosis, that cardiac macrophages from circulating monocytes preferentially commit to macrophage-to-myofibroblast transition (MMT) under angiotensin II (Ang II)-induced hypertension, with accompanying increased expression of the RNA N6-methyladenosine demethylases, ALKBH5. Meanwhile, macrophage-specific knockout of ALKBH5 inhibits Ang II-induced MMT, and subsequently ameliorates cardiac fibrosis and dysfunction. Mechanistically, RNA immunoprecipitation sequencing identifies interlukin-11 (IL-11) mRNA as a target for ALKBH5-mediated m6A demethylation, leading to increased IL-11 mRNA stability and protein levels. By contrast, overexpression of IL11 in circulating macrophages reverses the phenotype in ALKBH5-deficient mice and macrophage. Lastly, targeted delivery of ALKBH5 or IL-11 receptor α (IL11RA1) siRNA to monocytes/macrophages attenuates MMT and cardiac fibrosis under hypertensive stress. Our results thus suggest that the ALKBH5/IL-11/IL11RA1/MMT axis alters cardiac macrophage and contributes to hypertensive cardiac fibrosis and dysfunction in mice, and thereby identify potential targets for cardiac fibrosis therapy in patients.

Leonurine Attenuates Obesity-Related Vascular Dysfunction and Inflammation.

Oxidative stress in adipose tissue is a crucial pathogenic mechanism of obesity-associated cardiovascular diseases. Chronic low-grade inflammation caused by obesity increases ROS production and dysregulation of adipocytokines. Leonurine (LEO) is an active alkaloid extracted from Herba Leonuri and plays a protective role in the cardiovascular system. The present study tested whether LEO alleviates inflammation and oxidative stress, and improves vascular function in an obese mouse model. Here, we found that obesity leads to inflammation and oxidative stress in epididymal white adipose tissue (EWAT), as well as vascular dysfunction. LEO significantly improved inflammation and oxidative stress both in vivo and in vitro. Obesity-induced vascular dysfunction was also improved by LEO as evidenced by the ameliorated vascular tone and decreased mesenteric artery fibrosis. Using mass spectrometry, we identified YTHDF1 as the direct target of LEO. Taken together, we demonstrated that LEO improves oxidative stress and vascular remodeling induced by obesity and targets YTHDF1, raising the possibility of LEO treating other obesity-related metabolic syndromes.