Inflammatory process and oxidative/nitrative stress: in vivo study in mucopolysaccharidosis type IV A patients under long-term enzyme replacement therapy.

Mucopolysaccharidosis type IV A (MPS IVA) is an inborn error of the metabolism (IEM) caused by a deficiency of the enzyme N-acetylgalactosamine 6-sulfate sulfatase (GALNS). Since 2014, enzyme replacement therapy (ERT) is the recommended treatment for these patients. It is known that the inflammatory response is closely related to antioxidant defenses and oxidative stress, and literature shows involvement of oxidative stress in the pathogenesis of IEM. The aim of this study is to investigate the mechanisms of oxidative/nitrative stress and inflammation in patients with MPS IVA under long-term ERT. In the present work we investigate parameters of oxidative/nitrative stress in plasma and urine of MPS IVA patients under long-term ERT and controls, such as plasmatic nitrate/nitrite levels using the LDH Method, urinary di-tyrosine levels by fluorometric method, plasmatic content of sulfhydryl groups, urinary oxidized guanine species by ELISA kit and the plasmatic total antioxidant status. We next evaluated the plasmatic pro and anti-inflammatory cytokines concentration (IL-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α) and the expression of factors and enzymes Nrf-2, NF-κß and HO-1, main mediators between inflammation and oxidative stress. In concern to the oxidative/nitrative stress parameters, there was no significant difference between the groups MPS IVA patients under long-term ERT and controls, showing that there is no overproducing of RNS, no protein damage, no DNA/RNA oxidative damage and no modification in the non-enzymatic antioxidant capacity of a tissue to prevent the damage associated to free radical processes in these patients. It was also verified no significant difference between the MPS IVA patients under long-term ERT and controls groups regarding the production of proinflammatory cytokines. About anti-inflammatory cytokines, IL 10 was shown to be elevated in MPS IVA patients under long-term ERT in comparison to the control group. We next evaluated the genic expression of Nrf-2, NF-κß and HO-1and there was no significant difference between the MPS IVA patients under long-term ERT and control groups. In conclusion, MPS IVA patients under long term ERT are not in an inflammatory state and there is no alteration in genic expression in the genes analyzed which are involved in oxidative stress and inflammatory pathways. It is,however, important to consider that absence of imbalance of antioxidant defenses in MPS IVA patients under long term ERT is so far preliminary it is supported by methodologies that are not highly sensitive nor very accurate. Further experiments in future using state-of-the-art methodologies will corroborate these findings. Nevertheless, our results demonstrated the protective effect of the treatment in relation to the parameters studied and the importance of starting treatment in the early stages of the disease.

Evaluation of oxidative damage to biomolecules and inflammation in patients with urea cycle disorders.

Urea cycle disorders (UCD) are inborn errors of metabolism that occur due to a loss of function in enzymes and transporters involved in the urea cycle, causing an intoxication by hyperammonemia and accumulation of metabolites. Patients can develop hepatic encephalopathy (HE), severe neurological and motor disabilities, and often death. The mechanisms involved in the pathophysiology of UCD are many and complex, but there are strong indications that oxidative stress and inflammation are present, being responsible for at least part of the cellular damage that occurs in these diseases. The aim of this study was to evaluate oxidative and nitrosative damage and inflammation in UCD, to better understand the pathophysiology mechanisms of these diseases. We evaluated the nitrite and nitrate content, thiobarbituric acid-reactive substances (TBARS), carbonyl protein content and a panel of cytokines in plasma sample of 14 patients. The UCD patients group consisted of individuals affected with ornithine transcarbamylase deficiency (n = 8), carbamoyl phosphate synthetase deficiency (n = 2), argininosuccinate synthetase deficiency (n = 2); arginase 1 deficiency (n = 1) and argininosuccinate lyase deficiency (n = 1). Patients mean age at diagnosis was 5.25 ± 9.86 years-old and mean concentrations were compared with healthy individuals of matched age and gender. We found a significant reduction in nitrogen reactive species in patients when compared to controls. TBARS was increased in patients, indicating lipid peroxidation. To evaluate protein oxidative damage in UCD, the carbonyl content was measured, and the results also demonstrated an increase in this biomarker. Finally, we found that UCD patients have enhanced concentrations of cytokines, with pro-inflammatory interleukins IL-6, IL-8, interferon-γ and TNF-α, and anti-inflammatory IL-10 being increased when compared to the control group. In conclusion, our results demonstrate that oxidative stress and inflammation occurs in UCD and probably contribute to the severe brain damage present in patients.