Butyrate Produced by Gut Microbiota Regulates Atherosclerosis: A Narrative Review of the Latest Findings

Atherosclerosis (AS), a progressive inflammatory disease of coronary arteries, the aorta, and the internal carotid artery, is considered one of the main contributors to cardiovascular disorders. Blood flow is restricted by accumulating lipid-rich macrophages (foam cells), calcium, fibrin, and cellular debris into plaques on the intima of arterial walls. Butyrate maintains gut barrier integrity and modulates immune responses. Butyrate regulates G-protein-coupled receptor (GPCR) signaling and activates nuclear factor kappa-B (NF-κB), activator protein-1 (AP-1), and interferon regulatory factors (IFRs) involved in the production of proinflammatory cytokines. Depending on the inflammatory stimuli, butyrate may also inactivate NF-κB, resulting in the suppression of proinflammatory cytokines and the stimulation of anti-inflammatory cytokines. Butyrate modulates mitogen-activated protein kinase (MAPK) to promote or suppress macrophage inflammation, muscle cell growth, apoptosis, and the uptake of oxidized low-density lipoprotein (ox-LDL) in macrophages. Activation of the peroxisome proliferator-activated receptor γ (PPARγ) pathway plays a role in lipid metabolism, inflammation, and cell differentiation. Butyrate inhibits interferon γ (IFN-γ) signaling and suppresses NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) involved in inflammation and scar tissue formation. The dual role of butyrate in AS is discussed by addressing the interactions between butyrate, intestinal epithelial cells (IECs), endothelial cells (ECs) of the main arteries, and immune cells. Signals generated from these interactions may be applied in the diagnosis and intervention of AS. Reporters to detect early AS is suggested. This narrative review covers the most recent findings published in PubMed and Crossref databases.