Protein 3-nitrotyrosine formation during Trypanosoma cruzi infection in mice

Abstract

Tyrosine nitration is a post-translational modification resulting from the addition of a nitro (-NO 2 ) group to the ortho-position of tyrosine residues. Detection of protein 3-nitrotyrosine is regarded as a marker of nitro-oxidative stress and is observed in inflammatory processes. The formation and role of nitrating species in the control and myocardiopathy of T. cruzi infection remain to be studied. We investigated the levels of • NO and protein 3-nitrotyrosine in the plasma of C3H and BALB/c mice and pharmacologically modulated their production during the acute phase of T. cruzi infection. We also looked for protein 3-nitrotyrosine in the hearts of infected animals. Our results demonstrated that C3H animals produced higher amounts of • NO than BALB/c mice, but their generation of peroxynitrite was not proportionally enhanced and they had higher parasitemias. While N G -nitroarginine methyl ester treatment abolished • NO production and drastically augmented the parasitism, mercaptoethylguanidine and guanidoethyl disulfide, at doses that moderately reduced the • NO and 3-nitrotyrosine levels, paradoxically diminished the parasitemia in both strains. Nitrated proteins were also demonstrated in myocardial cells of infected mice. These data suggest that the control of T. cruzi infection depends not only on the capacity to produce • NO, but also on its metabolic fate, including the generation of nitrating species that may constitute an important element in parasite resistance and collateral myocardial damage.

Increased Myeloperoxidase Activity and Protein Nitration Are Indicators of Inflammation in Patients with Chagas' Disease

“…The plasma level of 3NT was monitored by ELISA as described previously (27). Briefly, 96-well plates were coated overnight at 4°C with 100-l serum samples (1:100 dilution in 0.1 M carbonate buffer, pH 9.6).…”

“…For example, ONOO Ϫ -mediated increased protein 3-nitrotyrosine (3NT) formation is detected in the plasma and heart of mice infected by T. cruzi (13,27). We have found increased plasma and cardiac levels of protein carbonyls and malonyldialdehydes (MDA; lipid peroxidation markers) in mice and rats infected by T. cruzi (13,40).…”

“…Besides ROS, activated macrophages produce nitric oxide ( ⅐ NO) via the inflammatory activation of inducible nitric oxide synthase (iNOS) in response to T. cruzi infection (27). ⅐ NO, produced in abundance by iNOS, directly reacts with O 2 ⅐ Ϫ to form peroxynitrite (ONOO Ϫ ) and peroxynitrous acid (ONOOH), which have been shown to kill T. cruzi (36).…”

Myeloid-Derived Suppressor Cells Infiltrate the Heart in Acute Trypanosoma cruzi Infection

“…To evaluate the relevance of MDSCs, we followed an alternative approach: we inhibited iNOS with L-NAME treatment of infected mice resulting in a dramatic increase in parasitemia, mortality, and parasite load in heart tissue with respect to untreated mice, showing that iNOS, and by extension NO-producing MDSCs, are necessary to control the T. cruzi infection (31)(32)(33)(34). In addition, Larginine supplementation reduced parasite burden in heart tissue, indicating that restoration of L-arginine levels is beneficial for the host.…”

Nitrative thioredoxin inactivation as a cause of enhanced myocardial ischemia/reperfusion injury in the aging heart

“…Cardiac nitrotyrosine, a footprint of in vivo RNS (e.g., ONOO − ) formation, was determined by using an ELISA procedure that has been used by numerous investigators [17,18]. In brief, the free wall of the left ventricle was separated and homogenized in ice-cold PBS (pH 7.0).…”