Attenuation of Nitrogen Mustard-Induced Pulmonary Injury and Fibrosis by Anti-Tumor Necrosis Factor-α Antibody

Abstract

Nitrogen mustard (NM) is a bifunctional alkylating agent that causes acute injury to the lung that progresses to fibrosis. This is accompanied by a prominent infiltration of macrophages into the lung and upregulation of proinflammatory/profibrotic cytokines including tumor necrosis factor (TNF)α. In these studies, we analyzed the ability of anti-TNFα antibody to mitigate NM-induced lung injury, inflammation, and fibrosis. Treatment of rats with anti-TNFα antibody (15 mg/kg, iv, every 9 days) beginning 30 min after intratracheal administration of NM (0.125 mg/kg) reduced progressive histopathologic alterations in the lung including perivascular and peribronchial edema, macrophage/monocyte infiltration, interstitial thickening, bronchiolization of alveolar walls, fibrin deposition, emphysema, and fibrosis. NM-induced damage to the alveolar-epithelial barrier, measured by bronchoalveolar lavage (BAL) protein and cell content, was also reduced by anti-TNFα antibody, along with expression of the oxidative stress marker, heme oxygenase-1. Whereas the accumulation of proinflammatory/cytotoxic M1 macrophages in the lung in response to NM was suppressed by anti-TNFα antibody, anti-inflammatory/profibrotic M2 macrophages were increased or unchanged. Treatment of rats with anti-TNFα antibody also reduced NM-induced increases in expression of the profibrotic mediator, transforming growth factor-β. This was associated with a reduction in NM-induced collagen deposition in the lung. These data suggest that inhibiting TNFα may represent an efficacious approach to mitigating lung injury induced by mustards.

Inflammatory mechanisms of pulmonary injury induced by mustards

“…In an experimental model of NM toxicity, we observed increases in numbers of lung macrophages expressing markers of M2 macrophages including Ym-1, galectin (Gal)-3, and CD68 and expression of antiinflammatory profibrotic genes (i.e., IL-10, connective tissue growth factor) within 3 d suggesting that the process of fibrosis begins early in the pathogenic response (Malaviya et al, 2012; Sunil et al, 2014; Venosa et al, 2015). This is supported by our findings that the appearance of M2 macrophages in the lung correlates with increases in expression of the profibrotic mitogen, TGF-β and fibroplasia at 3 d post NM, and collagen deposits around bronchioles and alveolar septae after 7 d; by 28 d multiple fibrotic foci with mature collagen are evident around the airways, distorting the normal parenchymal structure (Malaviya et al, 2015; Malaviya et al, 2012). At this time, large and foamy macrophages expressing Ym-1 and Gal-3 occluding the alveoli are prominent (Fig.…”

“…once every 9 d, beginning 30 min after NM. Inhibition of TNFα with pentoxifylline or anti-TNFα antibody reduces progressive histopathologic alterations in the lung beginning at 3 d including perivascular and peribronchial edema, macrophage/monocyte infiltration, interstitial thickening, bronchiolization of alveolar walls, fibrin deposition, emphysema and fibrosis (Malaviya et al, 2015; Sunil et al, 2014). Inhibition of TNFα also reduces NM-induced damage to the alveolar-epithelial barrier, measured by BAL protein and cell content, along with expression of the oxidative stress markers, HO-1 and lipocalin-2.…”

“…TNFα inhibitors also effectively suppress the accumulation of proinflammatory/cytotoxic M1 macrophages in the lung in response to NM, whereas antiinflammatory/wound repair M2 macrophages are increased or unchanged. Treatment of rats with anti-TNFα antibody also reduces NM-induced increases in expression of the profibrotic mediator, TGF-β (Malaviya et al, 2015). This is associated with marked inhibition of NM-induced fibrosis and collagen deposition in the lung.…”

Anti-TNFα therapy in inflammatory lung diseases

“…Lung tissue and alveolar macrophages isolated from patients with IPF release increased amounts of TNFα and sTNF receptors compared to healthy subjects (Cu et al, 2009; Piguet et al, 1993; Zhang et al, 1993). Additionally, in rodents, targeting TNFα attenuates pulmonary fibrosis suggesting role of TNFα in fibrogenesis (Malaviya et al, 2015; Piguet et al, 1993; Piguet and Vesin, 1994; Sunil et al, 2014; Thrall et al, 1997; Zhang et al, 1993). …”

“…Consistent with a role of TNFα in lung injury and disease pathology are findings that TNFRI −/− , TNFRII −/− , or TNFRI/II −/− mice are protected from ozone, silica or vesicant-induced lung injury and fibrosis (Cho et al, 2001; Laskin et al, 1998; Ortiz et al, 2001; Pryhuber et al, 2003; Sunil et al, 2011). Similarly, treatment of rodents with pentoxifylline or anti-TNFα antibody attenuates histopathological alterations in the lung, inflammatory cytokine release, alveolar cell apoptosis and the development of emphysema following exposure to various pulmonary toxicants (Bhalla et al, 2002; Malaviya et al, 2015; Shvedova et al, 1996; Sunil et al, 2014; Zhang et al, 2011). Damage to the alveolar-epithelial barrier, measured by increases in BAL protein and cell content following mustard exposure, along with expression of the oxidative stress markers, heme oxygenase-1 and lipocalin-2, is also reduced by pharmacologic inhibition of TNFα, (Malaviya et al, 2015; Sunil et al, 2014).…”