Carbon monoxide inhibits the nuclear-cytoplasmic translocation of HMGB1 in an in vitro oxidative stress injury model of mouse renal tubular epithelial cells

Carbon monoxide mechanism of protection against renal ischemia and reperfusion injury

Carbon monoxide is quickly moving past its historic label as a molecule once feared, to a therapeutic drug that modulates inflammation. The development of carbon monoxide releasing molecules and utilization of heme oxygenase-1 inducers have shown carbon monoxide to be a promising therapy in reducing renal ischemia and reperfusion injury and other inflammatory diseases. In this review, we will discuss the developments and application of carbon monoxide releasing molecules in renal ischemia and reperfusion injury, and transplantation. We will review the anti-inflammatory mechanisms of carbon monoxide in respect to mitigating apoptosis, suppressing dendritic cell maturation and signalling, inhibiting toll-like receptor activation, promoting anti-inflammatory responses, and the effects on renal vasculature.

DNA damage and antioxidant properties of CORM-2 in normal and cancer cells

In this study, we compared the effect of tricarbonyldichlororuthenium (II) dimer (CORM-2) and its CO-depleted molecule (iCORM-2) on human peripheral blood mononuclear cells (PBMCs) and human promyelocytic leukemia HL-60 cells. We determined cell viability, DNA damage and DNA repair kinetics. We also studied the effect of both compounds on DNA oxidative damage, free radical level and HO-1 gene expression. We showed that at low concentrations both CORM-2 and iCORM-2 stimulate PBMCs viability. After 24-h incubation, CORM-2 and iCORM-2, at the concentration of 100 µM, reduce the viability of both PBMCs and HL-60 cells. We also demonstrated that CORM-2 and iCORM-2, in the 0.01–100 µM concentration range, cause DNA damage such as strand breaks and alkaline labile sites. DNA damage was repaired efficiently only in HL-60 cells. CORM-2 significantly reduces oxidative stress induced by 1 mM H₂O₂ in normal and cancer cells. On the contrary, iCORM-2 in HL-60 cells increases the level of free radicals in the presence of 1 and 5 mM H₂O₂. We also revealed that both CORM-2 and iCORM-2 induce HO-1 gene expression. However, CORM-2 induces this gene to a greater extent than iCORM-2, especially in HL-60 cells at 100 µM. Finally, we showed that CORM-2 and iCORM-2 reduce H₂O₂-induced DNA oxidative damage. Furthermore, CORM-2 proved to be a compound with stronger antioxidant properties than iCORM-2. Our results suggest that both active CORM-2 and inactive iCORM-2 exert biological effects such as cyto- and genotoxicity, antioxidant properties and the ability to induce the HO-1 gene. The released CO as well as iCORM-2 can be responsible for these effects.

Severe COVID-19: NLRP3 Inflammasome Dysregulated

SARS-CoV-2 might directly activate NLRP3 inflammasome resulting in an endogenous adjuvant activity necessary to mount a proper adaptive immune response against the virus. Heterogeneous response of COVID-19 patients could be attributed to differences in not being able to properly downregulate NLRP3 inflammasome activation. This relates to the fitness of the immune system of the individual challenged by the virus. Patients with a reduced immune fitness can demonstrate a dysregulated NLRP3 inflammasome activity resulting in severe COVID-19 with tissue damage and a cytokine storm. We sketch the outlines of five possible scenarios for COVID-19 in medical practice and provide potential treatment options targeting dysregulated endogenous adjuvant activity in severe COVID-19 patients.

Regulation of Acetylation in High Mobility Group Protein B1 Cytosol Translocation

High mobility group protein B1 (HMGB1) is a nonhistone that mainly binds to nucleus DNA. As an important late inflammatory transmitter, extracellular HMGB1 is involved in the inflammatory immune response, tumor growth, infiltration, and metastasis. HMGB1 is actively released by activated inflammatory cells or passively released by necrotic cells. Then the released extracellular HMGB1 further induces monocytes/macrophages, neutrophils, and dendritic cells to secrete inflammatory cytokines. Therefore, HMGB1 can not only act as a proinflammatory factor to directly involve in tissue damage, but also acts as an inflammatory medium to aggravate the inflammatory cascade reaction. Studies have shown that the post-translational modification (PTM) participated in the process of HMGB1 cytosol translocation and extracellular release. The acetylation modification is the most common PTM for localization sequence of HMGB1, and the affinity of HMGB1 to DNA depends on the degree of acetylation for HMGB1. The acetylation can weaken the binding of HMGB1 to DNA, which means less HMGB1 cytosol translocation and extracellular release. This article reviews the acetylation regulation mechanisms of cytosol translocation and extracellular release of HMGB1 and provides a therapeutic strategy for controlling HMGB1-induced inflammatory responses in the future.

Effects of Qingshen Granules on the Oxidative Stress-NF/kB Signal Pathway in Unilateral Ureteral Obstruction Rats

Background. The activation of NF-kappa B (NF/kB) signaling pathway plays an important role in the process of epithelial-mesenchymal transition (EMT) and renal interstitial fibrosis (RIF) in renal tubules. The process of oxidative stress reaction in kidney is via excessive reactive oxygen species (ROS) production to activate NF/kB signaling pathway. Qingshen Granule (QSG) is an effective Chinese formula utilized to treat chronic renal failure. Previous studies confirmed that QSG could inhibit RIF in unilateral ureteral obstruction (UUO) rats. In this study, we used UUO rats to investigate the effects of QSG on oxidative stress and the activation of NF/kB signaling. Seventy male Sprague-Dawley (SD) rats were randomly divided into a sham group, UUO model group, Qingshen Granules (QSG) high-dose, medium-dose, and low-dose groups, PDTC group, and candesartan group (10 rats in each group). Our study demonstrated that oxidative stress-NF/kB signal pathway contributed to the formation of UUO renal interstitial fibrosis. QSG may protect against RIF by inhibiting the oxidative stress-NF/kB signal pathway, reducing inflammation, and improving renal tubular EMT.