Mitochondria provide a 'complex' solution to a bacterial problem

Role of metabolic reprogramming in pro-inflammatory cytokine secretion from LPS or silica-activated macrophages

In the lungs, macrophages constitute the first line of defense against pathogens and foreign bodies and play a fundamental role in maintaining tissue homeostasis. Activated macrophages show altered immunometabolism and metabolic changes governing immune effector mechanisms, such as cytokine secretion characterizing their classic (M1) or alternative (M2) activation. Lipopolysaccharide (LPS)-stimulated macrophages demonstrate enhanced glycolysis, blocked succinate dehydrogenase (SDH), and increased secretion of interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Glycolysis suppression using 2 deoxyglucose in LPS-stimulated macrophages inhibits IL-1β secretion, but not TNF-α, indicating metabolic pathway specificity that determines cytokine production. In contrast to LPS, the nature of the immunometabolic responses induced by non-organic particles, such as silica, in macrophages, its contribution to cytokine specification, and disease pathogenesis are not well understood. Silica-stimulated macrophages activate pattern recognition receptors (PRRs) and NLRP3 inflammasome and release IL-1β, TNF-α, and interferons, which are the key mediators of silicosis pathogenesis. In contrast to bacteria, silica particles cannot be degraded, and the persistent macrophage activation results in an increased NADPH oxidase (Phox) activation and mitochondrial reactive oxygen species (ROS) production, ultimately leading to macrophage death and release of silica particles that perpetuate inflammation. In this manuscript, we reviewed the effects of silica on macrophage mitochondrial respiration and central carbon metabolism determining cytokine specification responsible for the sustained inflammatory responses in the lungs.

Evaluation of Inhibitory Activities of UK-2A, an Antimycin-Type Antibiotic, and Its Synthetic Analogues against the Production of Anti-inflammatory Cytokine IL-4

The inhibitory activities of the antimycin-class antibiotics UK-2A, antimycin A, and splenocin B against the production of anti-inflammatory cytokine IL-4, which is related to IgE-mediated allergic responses in rat basophilic leukemia (RBL-2H3) cells, were evaluated. Although antimycin A and splenocin B showed cytotoxicity at concentrations at which IL-4 release from the cells was restricted, UK-2A was found to restrict IL-4 release without cytotoxicity. Three UK-2A analogues (4-6) were then synthesized and assessed. Compound 5 restricted IL-4 release dose-dependently without cytotoxicity, and its effect was more potent than that of UK-2A.

Tuning the Bandgap of Photo-Sensitive Polydopamine/Ag3PO4/Graphene Oxide Coating for Rapid, Noninvasive Disinfection of Implants

Bacterial infection and associated complications are threats to human health especially when biofilms form on biomedical devices and artificial implants. Herein, a hybrid polydopamine (PDA)/Ag3PO4/graphene oxide (GO) coating is designed and constructed to achieve rapid bacteria killing and eliminate biofilms in situ. By varying the amount of GO in the hybrid coating, the bandgap can be tuned from 2.52 to 2.0 eV so that irradiation with 660 nm visible light produces bacteria-killing effects synergistically in concert with reactive oxygen species (ROS). GO regulates the release rate of Ag+ to minimize the cytotoxicity while maintaining high antimicrobial activity, and a smaller particle size enhances the yield of ROS. After irradiation with 660 nm visible light for 15 min, the antimicrobial rates of the PDA/Ag3PO4/GO hybrid coating against Escherichia coli and Staphylococcus aureus are 99.53% and 99.66%, respectively. In addition, this hybrid coating can maintain a repeatable and sustained antibacterial efficacy. The released Ag+ and photocatalytic Ag3PO4 produce synergistic antimicrobial effects in which the ROS increases the permeability of the bacterial membranes to increase the probability of Ag+ to enter the cells to kill them together with ROS synergistically.

Epigenetic Treatment of Neurodegenerative Ophthalmic Disorders: An Eye Toward the Future

Eye disease is one of the primary medical conditions that requires attention and therapeutic intervention in ageing populations worldwide. Further, the global burden of diabetes and obesity, along with heart disease, all lead to secondary manifestations of ophthalmic distress. Therefore, there is increased interest in developing innovative new approaches that target various mechanisms and sequelae driving conditions that result in adverse vision. The research challenge is even greater given that the terrain of eye diseases is difficult to landscape into a single therapeutic theme. This report addresses the burden of eye disease due to mitochondrial dysfunction, including antioxidant, autophagic, epigenetic, mitophagic, and other cellular processes that modulate the biomedical end result. In this light, we single out lipoic acid as a potent known natural activator of these pathways, along with alternative and potentially more effective conjugates, which together harness the necessary potency, specificity, and biodistribution parameters required for improved therapeutic outcomes.