Catalytic Antioxidants in the Kidney

Reactive oxygen species and reactive nitrogen species are highly implicated in kidney injuries that include acute kidney injury, chronic kidney disease, hypertensive nephropathy, and diabetic nephropathy. Therefore, antioxidant agents are promising therapeutic strategies for kidney diseases. Catalytic antioxidants are defined as small molecular mimics of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, and some of them function as potent detoxifiers of lipid peroxides and peroxynitrite. Several catalytic antioxidants have been demonstrated to be effective in a variety of in vitro and in vivo disease models that are associated with oxidative stress, including kidney diseases. This review summarizes the evidence for the role of antioxidant enzymes in kidney diseases, the classifications of catalytic antioxidants, and their current applications to kidney diseases.

Epigenetic modifications and NF-κB pathway activity in Cu,Zn-SOD-deficient mice

The aim of this study was to examine the possible impact of Cu,Zn-SOD deficiency on the level of epigenetic modifications in different mouse tissues, and the relationship between these modifications and the NF-κB transcription factor activity. Cu,Zn-SOD deficiency did not influence the level of 5mdC or 5hmdC in the analyzed tissues. Statistically significant organ-/tissue-specific differences between the levels of 5mdC and 5hmdC were demonstrated within each genotype. Also correlations between analyzed parameters pointed to wide tissue/genotype variety; we observed a positive correlation between 5mdC and NF-кB proteins, p50 and RelA, in the liver of wild mice, as well as an inverse correlation between 5mdC and p65 in the brain of Cu,Zn-SOD-deficient animals. Moreover, a positive correlation was revealed between 5mdC and 5hmdC in the liver and brain of knockout mice. As the highest levels of both 5mdC and 5hmdC were observed in the brains of analyzed animals regardless of their genotype, and lower, comparable to each other, levels of these modifications were shown in the kidney and liver, active demethylation process seems to be tissue-/organ-specific and does not necessarily rely solely on the redox/oxidation state of cells. According to the most likely scenario, various tissues may differ in terms of their metabolic rates, which has potential influence on cofactors, and consequently on the activity of TET enzymes or activation of TET-independent mechanisms.

Copper-zinc superoxide dismutase-deficient mice show increased susceptibility to experimental autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein 35-55

In this report, we have addressed the role of copper-zinc superoxide dismutase (SOD1) deficiency in the mediation of central nervous system autoimmunity. We demonstrate that SOD1-deficient C57Bl/6 mice develop more severe autoimmune encephalomyelitis induced with myelin oligodendrocyte glycoprotein (MOG) 35-55, compared with wild type mice. This alteration in the disease phenotype was not due to aberrant expansion of MOG-specific T cells nor their ability to produce inflammatory cytokines; rather lymphocytes generated in SOD1-deficient mice were more prone to spontaneous cell death when compared with their wild type littermate controls. The data point to a role for SOD1 in the maintenance of self-tolerance leading to the suppression of autoimmune responses.

Association of SOD1 and SOD2 single nucleotide polymorphisms with susceptibility to gastric cancer in a Korean population

Oxidative stress is accepted as one of the main factors involved in the development and progression of cancer. Superoxide dismutases (SODs) are important in avoiding oxidative stress by eliminating reactive oxygen species (ROS). To determine whether single nucleotide polymorphisms at G7958A within SOD1 and at T5482C within SOD2 are associated with an increased susceptibility to gastric cancer, we investigated the genotype and allele frequencies of the genes from 294 gastric cancer patients and 300 healthy individuals. A polymerase chain reaction-single strand conformation polymorphism assay was used to identify the SOD1 G7958A and the SOD2 T5482C genotypes. Statistically significant differences in the genotype and allele frequencies of SOD2 T5482C were found between the healthy controls and gastric cancer patients (p = 0.0001 and p < 0.0001, respectively). When the data were stratified according to gastric cancer histological subtypes, the risk of both diffuse- and intestinal-type gastric cancer was statistically higher for carriers of the C allele compared with carriers of the T allele. However, there were no statistically significant differences in genotype distribution (p = 0.5069) and allele frequencies (p = 0.3714) of SOD1 G7958A between gastric cancer patients and controls. Our findings suggest that polymorphism of the SOD2 T5482C may be closely associated with an increased susceptibility to the development and differentiation of gastric cancer in the Korean population.

Putative proto-oncogene Pir expression is significantly up-regulated in the spleen and kidney of cytosolic superoxide dismutase-deficient mice

Iron binding protein pirin was isolated as an interactor of the NFIX transcription factor but it can also form complexes with Bcl3 and NF-κB1(p50). Alterations of pirin expression were observed in various tumors and after exposure to pro-carcinogenic oxidative stressors. The aim of the present work was to study the level of pirin transcription in an in vivo model of oxidative stress, namely, in Sod1-deficient mice. We have found that Sod1(-/-) mice have a significantly elevated level of Pir mRNA in the spleen and kidney but not in the liver, heart, or/and brain. We have also shown that similarly to its human ortholog, the mouse Pir gene transcription level varies significantly between organs. The highest expression was found in the liver and the lowest in the spleen and kidney. Based on literature data, we propose the involvement of Nrf2, AP-1, and NF-κB transcription factors in Pir up-regulation in Sod1(-/-) mice.

Alterations in the expression of genes related to NF-κB signaling in liver and kidney of CuZnSOD-deficient mice

NF-κB signaling pathway plays a central role in regulation of the cellular response to stress. Among numerous factors that modulate NF-κB dependent transcription, reactive oxygen species attracted special attention. In the present work, we compared the expression of 84 genes related to NF-κB signaling between cytosolic superoxide dismutase (CuZnSOD)-deficient and wild-type mice. In kidney, we found seven genes which expression was significantly affected by CuZnSOD deficiency. Among them, four were up-regulated, Egr1, Fos, Il1b, Tnfrsf10b, and three down-regulated, Card10, Ikbkb, Tgfbr2. In the case of liver, six genes were up-regulated, Fos, Il1b, Il1r1, Jun, Tlr7, Tnfrsf10b, and five down-regulated, Casp8, Ikbke, Irak1, Nfkb1, Raf1. The results demonstrate that CuZnSOD deficiency has a significant impact on the expression of NF-κB related genes in both kidney and liver. The differences in gene expression reported in our work may contribute to understanding of the molecular mechanisms underlying phenotypic abnormalities in CuZnSOD-deficient mice, e.g., increase in the incidence of liver cancer.