Nitrotyrosine Proteome Survey in Asthma Identifies Oxidative Mechanism of Catalase Inactivation

Abstract

Reactive oxygen species and reactive nitrogen species produced by epithelial and inflammatory cells are key mediators of the chronic airway inflammation of asthma. Detection of 3-nitrotyrosine in the asthmatic lung confirms the presence of increased reactive oxygen and nitrogen species, but the lack of identification of modified proteins has hindered an understanding of the potential mechanistic contributions of nitration/oxidation to airway inflammation. In this study, we applied a proteomic approach, using nitrotyrosine as a marker, to evaluate the oxidation of proteins in the allergen-induced murine model of asthma. Over 30 different proteins were targets of nitration following allergen challenge, including the antioxidant enzyme catalase. Oxidative modification and loss of catalase enzyme function were seen in this model. Subsequent investigation of human bronchoalveolar lavage fluid revealed that catalase activity was reduced in asthma by up to 50% relative to healthy controls. Analysis of catalase isolated from asthmatic airway epithelial cells revealed increased amounts of several protein oxidation markers, including chloro- and nitrotyrosine, linking oxidative modification to the reduced activity in vivo. Parallel in vitro studies using reactive chlorinating species revealed that catalase inactivation is accompanied by the oxidation of a specific cysteine (Cys(377)). Taken together, these studies provide evidence of multiple ongoing and profound oxidative reactions in asthmatic airways, with one early downstream consequence being catalase inactivation. Loss of catalase activity likely amplifies oxidative stress, contributing to the chronic inflammatory state of the asthmatic airway.

Ozone enhancement of lower airway allergic inflammation is prevented by γ-tocopherol

“…Supporting this idea is the observations that γT (but not αT) is a highly efficient quencher of nitric oxide and peroxynitrite in vitro [26], and that γT can inhibit protein nitration during systemic inflammation in laboratory rodents [44]. This may be very relevant to allergen-induced inflammation, as nitric oxide production during allergic inflammation, primarily from eosinophils, has been implicated in the nitration and inactivation of key anti-inflammatory and protective enzymes, including catalase, superoxide dismutase, and glutathione transferases [14]. It is reasonable therefore to speculate that γT could provide protection from nitrosative stress that occurs in allergic airways with eosinophilia.…”

“…Decreases in antioxidant vitamins E and C, and increases in oxidized glutathione have been reported in airway fluids of asthmatics [9][10][11]. In addition, enzymatic antiinflammatory capacity in the lung and plasma of asthmatics is depressed as indicated by lower activities of glutathione peroxidase, superoxide dismutase and catalase [12][13][14]. Deficient defenses in the airway microenvironment could allow for increased sensitivity to further oxidative insult by ozone exposure.…”

Catalase C-262T Gene Variant in Patients with Bronchial Asthma

“…Experimental studies showed that catalase activity is up to 50% lower in bronchoalveolar lavage of asthmatic lungs compared to healthy controls, which is considered to be the result of protein oxidative modification and not the decreased amount of enzyme (1,8). Moreover, erythrocytes of the asthmatic children showed decreased catalase activity compared to healthy children (9).…”

Protein Tyrosine Nitration of Aldolase in Mast Cells: A Plausible Pathway in Nitric Oxide-Mediated Regulation of Mast Cell Function

“…However, the expression of these isoforms is not restricted to specific tissues, (e.g., all three isoforms are expressed in kidney) (60,61). Tyrosine nitration of aldolase A, B, and C was reported in a wide range of tissues and under different inflammatory conditions (50,(62)(63)(64)(65). To define specific tyrosine residues that are nitrated in aldolase A or in aldolase C, MS identification of nitration-specific sites requires large amounts of protein; we are working toward enriching the nitrated aldolase fractions with specific techniques (66).…”

“…It is intriguing that aldolase A has been identified as a target of tyrosine nitration in several other cells and tissues, including diaphragm (50), human skin fibroblasts (35), quadriceps muscle of patients with severe chronic obstructive pulmonary disease (72), and in lung tissue in a model of asthma (65). However, this is the first report in human MCs.…”