Background

Oxidative stress and inflammation promote the development and progression of chronic kidney disease. Oxidative stress is associated with depletion of tissue glutathione (GSH), the most abundant endogenous intracellular antioxidant, but degradation of oral GSH by digestive enzymes limits its therapeutic use. We hypothesized that GSH repletion with F1, a novel oral GSH precursor containing cystine as a cysteine carrier, would restore tissue GSH and attenuate oxidative stress and inflammation, and thereby reduce the severity of interstitial nephropathy in chronic renal failure (CRF).

Methods

Male Sprague-Dawley rats (n=5-8) were assigned to 3 groups: Control (regular rat chow), CRF (rat chow containing 0.7% adenine), and F1-treated CRF (rat chow containing 0.7% adenine and F1, 0.5g/kg/day) for 2-weeks. Animals were switched to regular chow and euthanized after 2 additional weeks.

Results

Consumption of 0.7% adenine-containing diet caused azotemia; severe kidney swelling; heavy tubular and glomerular damage; massive tubulointerstitial nephropathy; impaired urinary concentrating capacity; severe anemia; increased markers of oxidative stress, plasma oxidized glutathione disulfide (GSSG); reduced GSH/GSSG ratio and manganese superoxide dismutase; increased expression of inflammatory mediators (cyclooxygenase-2, cytoplasmic NF-κB, p-IκBα, nuclear NF-κB p65), and 3-nitrotyrosine, p<0.05. Co-treatment with F1 significantly attenuated tubulointerstitial inflammation and edema, improved urinary concentrating capacity, azotemia and anemia, and normalized markers of tissue oxidative and nitrosative stress, p<0.05.

Conclusions

The novel oxidative stress modulator, F1, markedly attenuated oxidative stress indicators, inflammation, renal injury and dysfunction in the rat model of CRF. Studies to determine the effects of F1 in other models of acute and CRF are warranted.

Nonalcoholic fatty liver disease (NAFLD) is the most common form of liver pathologies and is associated with obesity and the metabolic syndrome. Here, we investigated the molecular mechanisms by which a novel cystine based glutathione precursor with added selenomethionine (F1) prevents hepatic steatosis in a moderate high fat dietary model of NAFLD. Adult (8 weeks old), male apolipoprotein E (ApoE)−/− mice were fed with a normal diet (ND) or high fat diet (HFD), consisting of 21% fat and 0.21% cholesterol, with or without dietary supplementation of F1 (3 g/kg food) for 16 weeks. Compared with ApoE−/− mice fed with ND with or without F1, ApoE−/− mice fed with HFD exhibited significant weight gain, hepatomegaly, and increased serum cholesterol and triglycerides levels with no change in serum albumin levels. High resolution light and electron microscopy revealed micro-and macro-vesicular steatosis in ApoE−/− mice fed on a HFD. HFD- induced obesity also led to increased lipogenesis, oxidative stress, activation of c-Jun-NH₂-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), perturbation of the BAX/BCL-2 rheostat, hepatocyte apoptosis, and activation of caspases 9 and 3. F1 fully prevented the adverse effects of HFD on serum triglyceride levels, body and liver weights, and hepatic steatosis and substantially attenuated HFD-induced increase in lipogenesis, oxidative stress, kinase activation, apoptotic signaling, and hepatocyte ultrastructural abnormalities. These results demonstrate that administration of F1, a glutathione precursor, ameliorates HFD-induced hepatic steatosis in ApoE−/− mice and emphasizes the role of oxidative stress in diet-induced obesity and hepatic steatosis.