Mitochondria participate in various intracellular metabolic pathways such as generating intracellular ATP, synthesizing several essential molecules, regulating calcium homeostasis, and producing the cell’s reactive oxygen species (ROS). Emerging studies have demonstrated newly discovered roles of mitochondria, which participate in the regulation of innate immune responses by modulating NLRP3 inflammasomes. Here, we review the recently proposed pathways to be involved in mitochondria-mediated regulation of inflammasome activation and inflammation: 1) mitochondrial ROS, 2) calcium mobilization, 3) nicotinamide adenine dinucleotide (NAD+) reduction, 4) cardiolipin, 5) mitofusin, 6) mitochondrial DNA, 7) mitochondrial antiviral signaling protein. Furthermore, we highlight the significance of mitophagy as a negative regulator of mitochondrial damage and NLRP3 inflammasome activation, as potentially helpful therapeutic approaches which could potentially address uncontrolled inflammation.

Interleukin-1b (IL-1β), a proinflammatory cytokine, regulates the innate immune responses against bacterial infection. Mature IL-1β is produced from pro-IL-1β by activated caspase-1, which in turn is activated by the inflammasome complex formation. In this study, we compared the inflammasome mRNA expression induced by S. sanguinis, S. oralis, F. nucleatum and P. intermedia. Among the tested bacteria, S. sanguinis induced the highest IL-1β secretion. S. oralis, F. nucleatum and P. intermedia induced very weak IL-1β secretion. S. sanguinis mostly induced the NLRP3 mRNA expressions. Although F. nucleatum did not induce high IL-1β secretion, it induced high expression levels of AIM2, NLRP2, and NLRP3. No specific inflammasomes were induced by S. oralis and P.intermedia. Studying the inflammasome complex activation induced by oral bacteria may thus enhance our understanding of the pathogenesis of oral diseases.

Inflammation mainly mediated by innate immune cells as the first line of host defense against pathogens is an acute response that limits tissue damage and eliminates pathogens in the body. In triggering inflammation, several pattern recognition receptors work together; membrane-associated Toll-like receptors, c-type lectin receptors, retinoic acid-inducible gene-like helicase receptors, absent in melanoma-like receptors, and cytosolic nucleotide-binding domain and leucine-rich repeat receptors. Among them, inflammasome is a newly trigger of inflammation in response to exogenous and endogenous stimuli and its activation leads to the assembly of multiprotein platforms composed of NLRP3 (NOD-like receptor family, pyrin domain containing 3), ASC (apoptosis associated speck-like protein containing a CARD), and procaspase 1. Thus, the activated inflammasome activates caspase 1, resulting in processing and secretion of interleukin (IL)-1β. Recent emerging data suggest that dysregulated metabolites, i.e., amyloids, ceramides, and cholesterol crystals, have been classified as inflammasome activators. In addition, IL-1β may play a critical role in the pathogenesis of chronic inflammation-induced disorders such as Alzheimer’s diseases, type 2 diabetes, and atheriosclerosis. This review introduces the basic concept of inflammasome activation and auto-inflammatory diseases. In addition, it discusses the updated signaling models of inflammasome activation that link metabolic dysfunction in order to outline future therapeutic approaches to inflammasome-mediating diseases.