Role of NOS2 in pulmonary injury and repair in response to bleomycin

Abstract

Nitric oxide (NO) is derived from multiple isoforms of the Nitric Oxide Synthases (NOSs) within the lung for a variety of functions; however, NOS2-derived nitrogen oxides seem to play an important role in inflammatory regulation. In this study, we investigate the role of NOS2 in pulmonary inflammation/fibrosis in response to intratracheal bleomycin instillation (ITB) and to determine if these effects are related to macrophage phenotype. Systemic NOS2 inhibition was achieved by administration of 1400 W, a specific and potent NOS2 inhibitor, via osmotic pump starting six days prior to ITB. 1400 W administration attenuated lung inflammation, decreased chemotactic activity of the broncheoalveolar lavage (BAL), and reduced BAL cell count and nitrogen oxide production. S-nitrosylated SP-D (SNO-SP-D), which has a pro-inflammatory function, was formed in response to ITB; but this formation, as well as structural disruption of SP-D, was inhibited by 1400 W. mRNA levels of IL-1β, CCL2 and Ptgs2 were decreased by 1400 W treatment. In contrast, expression of genes associated with alternate macrophage activation and fibrosis Fizz1, TGF-β and Ym-1 was not changed by 1400 W. Similar to the effects of 1400 W, NOS2−/− mice displayed an attenuated inflammatory response to ITB (day 3 and day 8 post-instillation). The DNA-binding activity of NF-κB was attenuated in NOS2−/− mice; in addition, expression of alternate activation genes (Fizz1, Ym-1, Gal3, Arg1) was increased. This shift towards an increase in alternate activation was confirmed by western blot for Fizz-1 and Gal-3 that show persistent up-regulation 15 days after ITB. In contrast arginase, which is increased in expression at 8 days post ITB in NOS2−/−, resolves by day 15. These data suggest that NOS2, while critical to the development of the acute inflammatory response to injury, is also necessary to control the late phase response to ITB.

Oxidative damage of SP-D abolishes control of eosinophil extracellular DNA trap formation

“…H). The multimeric (native) structure of SP‐D is known to be susceptible to chemical modifications by free radicals during airway inflammation and such change can result in a loss of its immune protective properties . Indeed, while O 3 enhanced mRNA as well as total SP‐D protein expression in the asthmatic mice, the proportion of highly oligomerized SP‐D was in fact significantly decreased in these animals (Fig.…”

Pathogenesis of Diffuse Alveolar Hemorrhage in Murine Lupus

“…6B) further supports the idea that macrophages rather than neutrophils mediate DAH. Although Nos2 has been implicated in bleomycin-induced lung injury [48], it was not involved in pristane-induced DAH (Fig. 6B).…”

Nitric Oxide Regulates Macrophage Fungicidal Activity via S-nitrosylation of Dectin-1

“…[51][52][53][54] In another scavenger molecule, surfactant protein-D (SP-D), critical thiol residues are involved in the assembly of the native multimer. [55][56][57][58] Nitrosylation of these thiols results in multimer disassembly and a switch in molecular function that allows SP-D to bind calreticulin and promote acute macrophage activation. 57,58 The cysteines involved in the regulation of SP-D function are located within a hydrophobic pocket in the tail domain of the molecule.…”

“…[55][56][57][58] Nitrosylation of these thiols results in multimer disassembly and a switch in molecular function that allows SP-D to bind calreticulin and promote acute macrophage activation. 57,58 The cysteines involved in the regulation of SP-D function are located within a hydrophobic pocket in the tail domain of the molecule. [55][56][57][58] Examination of the sequence of Dectin-1 reveals the presence of a cysteine residue, Cys54, within a hydropho-bic pocket (Fig.…”