Disruption of gut microbiota could induce cardiorespiratory morbidity. Consistently, modulation of autonomic homeostasis via the gut microbiota-brain axis could control the heart rate [
41]. The adult gut system might be an extremely diverse and dynamic ecosystem [42, 43], which exert specific physiological functions including immune regulation, gut mucosal protection, and conservation of nutritional metabolism in addition to the development of several diseases [
44]. Microbiota elements can directly or indirectly trigger vagus nerve afferent fibers through the gut endocrine cells, which could stimulate the central nervous system (CNS). Depending on the substance, the different SCFAs produced by microbiota maybe activate vagal afferent fibers in different ways. For example, butyric acid, a short fatty acid, directly affects afferent terminals [45, 46]. An increase in the concentration of butyric acid at the colon may produce a significant hypotensive effect which depends on the afferent colonic vagus nerve signaling and GPR41/43 receptors [
46]. Several studies have investigated the effects of food components on gut microbiota, which could be an imperative target for the forthcoming treatment of arrhythmias through the modification of gut microbiota. For example, patients with arrhythmias may prefer to take further energy from animal fat [
47]. Therefore, patients with cardiac arrhythmias are often found with atherosclerosis. In addition, diabetes may be also a frequent co-morbidity in individuals with arrhythmias. Furthermore, the interaction between some drugs and their impact on gut microbiota may result in uncontrolled arrhythmias [
48-50]. Recent increasing data suggest that regulatory non-coding RNAs such as miRNAs, circular RNAs, and lncRNA may affect host-microbe interactions. These ncRNAs have been also suggested as potential biomarkers in microbiome-associated disorders with a direct cross-talk between microbiome composition and ncRNAs [
51]. Epigenetically,
miR-23a-3p could lead to Th17/Treg imbalance and participate in the progression of Graves' disease [
52], which might be also involved in the mechanism underlying atrial fibrillation. Gut microbiota plays a vital role in the pathogenesis both of atrial fibrillation and Graves' disease [
52]. The imbalance of Th17/Treg cells induced by the alteration of gut microbiota plays a vital role in the pathogenesis of arrhythmias [53, 54]. Interestingly, altered composition of gut microbiota could change the expression of hepatic
miR-34a [
55], which might be also involved in the development of atrial fibrillation. A negative correlation between
miR-122-5p and the intestinal bacteria including
Bacteriodes. uniformis and
Phascolarctobacterium. Faecium has been revealed, suggesting that the crosstalke between miRNA and gut microbiota could regulate the intracellular signal transduction by controlling key genes [
56]. As mentioned before, the
miR-122-5p could possess great diagnostic potential in arrhythmogenic cardiomyopathy patients [40, 57].
(Figure 2)
In these ways, evidence from numerous studies in both humans and animals suggests that the role of the gut microbiota and its metabolites in arrhythmia has been well established. Through a variety of pathways, the gut microbiota significantly affects cardiac arrhythmia, which may provide a wide range of potential therapeutic approaches [58, 59]. Linking the possible interfering role of gut microbiota in the pharmacokinetics of drugs used in management of cardiac arrhythmias would help to better understand the potential of probiotics [60, 61].
Figure 2.
Several factors and/or inflammation with ROS may affect the development of cardiovascular diseases including cardiac arrhythmias. Note that some critical pathways have been omitted for clarity.
Figure 2.
Several factors and/or inflammation with ROS may affect the development of cardiovascular diseases including cardiac arrhythmias. Note that some critical pathways have been omitted for clarity.