Murine Model Of Chronic Obstructive Pulmonary Disease Research Articles

Increased T-regulatory cells in lungs and draining lymph nodes in a murine model of COPD: Fig. 1—

To the Editors: The characterisation of regulatory T (Treg) cells in chronic obstructive pulmonary disease (COPD) has become of particular interest considering the recent reports on adaptive immune responses in COPD. More specifically, peribronchial and parenchymal lymphoid follicles ( i.e. tertiary lymphoid organs) correlate in number with disease severity in COPD patients 1 and murine models of COPD 2, but their developing mechanisms and function have yet to be revealed 3. In COPD patients, pulmonary lymphoid follicles mainly appear as a B-cell core surrounded by a predominant cluster of differentiation (CD)4+ T-cell population 3. Treg cells situated within these structures are ideally located to exert cell contact-dependent immunosuppression. The observation on increased Treg cells in lymphoid follicles of moderate COPD patients by Plumb et al. 4, is therefore particularly intriguing. The different reports on Treg cells in COPD vary greatly, depending on the pulmonary anatomical compartment of interest and the phenotype used to define …

Pharmacological Blockade of the DP2 Receptor Inhibits Cigarette Smoke-Induced Inflammation, Mucus Cell Metaplasia, and Epithelial Hyperplasia in the Mouse Lung

Prostaglandin D(2) (PGD(2)) is one of a family of biologically active lipids derived from arachidonic acid via the action of COX-1 and COX-2. PGD(2) is released from mast cells and binds primarily to two G protein-coupled receptors, namely DP1 and DP2, the latter also known as chemoattractant receptor-homologous molecule expressed on Th2 cells. DP2 is predominantly expressed on eosinophils, Th2 cells, and basophils, but it is also expressed to a lesser extent on monocytes, mast cells, and epithelial cells. Interaction of PGD(2) and its active metabolites with DP2 results in cellular chemotaxis, degranulation, up-regulation of adhesion molecules, and cytokine production. Chronic obstructive pulmonary disease (COPD) is a chronic progressive inflammatory disease characterized by elevated lung neutrophils, macrophages, and CD8+ T lymphocytes and mucus hypersecretion. Cigarette smoke contributes to the etiology of COPD and was used here as a provoking agent in a murine model of COPD. In an acute model, {2'-[(cyclopropanecarbonyl-ethyl-amino)-methyl]-6-methoxy-4'-trifluoro-methyl-biphenyl-3-yl}-acetic acid, sodium salt (AM156) and (5-{2-[(benzoyloxycarbonyl-ethyl-amino)-methyl]-4-trifluoromethyl-phenyl}-pyridin-3-yl)-acetic acid, sodium salt) (AM206), potent DP2 receptor antagonists, dose-dependently inhibited influx of neutrophils and lymphocytes to smoke-exposed airways. In a subchronic model, AM156 and AM206 inhibited neutrophil and lymphocyte trafficking to the airways. Furthermore, AM156 and AM206 treatment inhibited mucus cell metaplasia and prevented the thickening of the airway epithelial layer induced by cigarette smoke. These data suggest that DP2 receptor antagonism may represent a novel therapy for COPD or other conditions characterized by neutrophil influx, mucus hypersecretion, and airway remodeling.

CCR7 Modulates Pulmonary and Lymph Node Inflammatory Responses in Cigarette Smoke-Exposed Mice

Peribronchial lymphoid follicles have recently been identified as one of the hallmark features of (severe) chronic obstructive pulmonary disease (COPD). However, little is known about the relative contribution of peribronchial lymphoid follicles vs mediastinal lymph nodes in inflammatory responses in COPD patients and animal models. In a murine model of COPD, we studied inflammatory responses in airways, lungs, and mediastinal lymph nodes of wild-type (WT) vs CCR7 knockout (CCR7(-/-)) mice upon subacute or chronic exposure to cigarette smoke (CS). Although crucial for the organization of the secondary lymphoid organs, CCR7 was not required for the development of chronic CS-induced pulmonary lymphoid follicles. Moreover, T cell numbers were significantly increased in airways and lungs of air-exposed CCR7(-/-) mice, and they continued to increase upon chronic CS exposure. Unexpectedly, subacute CS-induced inflammation in airways and lungs, including airway neutrophilia and the recruitment of inflammatory-type CD11b(+) dendritic cells, depended greatly on CCR7. In the draining lymph nodes, chronic CS exposure induced CCR7-dependent recruitment of airway-derived dendritic cells, accompanied by increases in CD4(+) and CD8(+) T cells. Correspondingly, CS exposure up-regulated mRNA expression of CCR7 ligands CCL19 and CCL21-Ser in lymph nodes of WT mice, but not CCR7(-/-) mice. In the lungs of WT mice, chronic CS exposure significantly increased CCL19 mRNA and protein. Furthermore, double staining for CCL19 and pro-surfactant protein C showed that alveolar type II cells express high levels of CCL19. These data unveil a so far unappreciated role for CCR7 in modulating inflammatory responses in airways and lungs.

Role of lymphotoxin- in cigarette smoke-induced inflammation and lymphoid neogenesis

In chronic obstructive pulmonary disease (COPD), chronic inflammation is accompanied by peribronchial lymphoid aggregates. Lymphotoxin (LT)-alpha, crucial in secondary lymphoid organogenesis, may be involved in lymphoid neogenesis. We examined cigarette smoke (CS)-induced pulmonary lymphoid neogenesis and inflammation in vivo in LTalpha knockout (LTalpha(-/-)) and wild-type (WT) mice and studied the expression of lymphoid chemokines by lung fibroblasts in vitro. T-cell numbers (in bronchoalveolar lavage fluid (BALF) and lungs) and lymphoid aggregate numbers were significantly higher in air-exposed LTalpha(-/-) mice than in WT animals, and increased upon chronic CS exposure in both genotypes. In contrast, local immunoglobulin A responses upon chronic CS exposure were attenuated in LTalpha(-/-) mice. CXC chemokine ligand (CXCL) 13 and CC chemokine ligand (CCL) 19 mRNA in total lung and CXCL13 protein level in BALF increased upon CS exposure in WT, but not in LTalpha(-/-) mice. In vitro lymphotoxin-beta receptor (LTbetaR) stimulation induced CXCL13 and CCL19 mRNA in WT lung fibroblasts. Furthermore, in vitro exposure to CS extract upregulated CXCL13 mRNA expression in WT, but not in LTbetaR(-/-), lung fibroblasts. In this murine model of COPD, CS induces pulmonary expression of lymphoid chemokines CXCL13 and CCL19 in a LTalphabeta-LTbetaR-dependent fashion. However, LTalpha is not required for CS-induced pulmonary lymphocyte accumulation and neogenesis of lymphoid aggregates.

Murine TLR4 Is Implicated in Cigarette Smoke-Induced Pulmonary Inflammation

Background: Chronic obstructive pulmonary disease (COPD) is associated with an abnormal inflammatory response of the lungs to noxious particles or gases. We investigated whether Toll-like receptor 4 (TLR4) is implicated in cigarette smoke (CS)-induced pulmonary inflammation in a murine model of COPD. Methods: C3H/HeOuJ (Tlr4^WT) and C3H/HeJ (Tlr4^defective) mice were exposed to air or CS for 5 weeks (subacute) and 26 weeks (chronic), and pulmonary inflammation was evaluated. Results: In Tlr4^WT mice, subacute and chronic CS exposure induced a substantial pulmonary infiltration of macrophages, neutrophils, lymphocytes and dendritic cells (DCs), that was absent in air-exposed mice. CS exposure increased the costimulatory marker expression on DCs, the levels of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) in bronchoalveolar lavage (BAL) fluid and induced the pulmonary expression of matrix metalloproteinase-12 (MMP-12), TLR4 and TLR2. In contrast, after subacute CS exposure, Tlr4^defective mice showed a limited (5-fold lower) increase of DCs and lymphocytes in BAL fluid, lower costimulatory marker expression on DCs and lower MCP-1 and TNF-α levels in BAL fluid compared to Tlr4^WT animals. After chronic CS exposure, however, the difference in pulmonary inflammation between Tlr4^WT and Tlr4^defective mice was less pronounced and both strains showed similar MCP-1 and TNF-α levels in BAL and similar pulmonary MMP-12, TLR4 and TLR2 expression. Conclusions: We demonstrated that the TLR4 mutation in C3H/HeJ mice is protective against CS-induced pulmonary influx of neutrophils, DCs and lymphocytes upon subacute CS exposure. However, TLR4 is only of minor importance in chronic CS-induced inflammation in mice.