Chronic cigarette smoke exposure generates pathogenic T cells capable of driving COPD-like disease in Rag2-/- mice

Smoking: effects on multiple sclerosis susceptibility and disease progression

Multiple sclerosis (MS) is associated with both genetic and environmental factors that influence disease susceptibility. Exposure to cigarette smoke is emerging as a viable environmental risk factor for MS that contributes to both increased disease susceptibility and more rapid disease advancement. The relative risk for MS development is approximately 1.5 for smokers compared with nonsmokers. Furthermore, there may be important interactions between smoking, an individual's genetic background, and other environmental risk exposures. This review summarizes the current evidence supporting the association of smoking with MS risk and disease course, with additional comments on causation.

Pathogenesis of chronic obstructive pulmonary disease

The current epidemic of chronic obstructive pulmonary disease (COPD) has produced a worldwide health care burden, approaching that imposed by transmittable infectious diseases. COPD is a multidimensional disease, with varied intermediate and clinical phenotypes. This Review discusses the pathogenesis of COPD, with particular focus on emphysema, based on the concept that pulmonary injury involves stages of initiation (by exposure to cigarette smoke, pollutants, and infectious agents), progression, and consolidation. Tissue damage entails complex interactions among oxidative stress, inflammation, extracellular matrix proteolysis, and apoptotic and autophagic cell death. Lung damage by cigarette smoke ultimately leads to self-propagating processes, resulting in macromolecular and structural alterations - features similar to those seen in aging.

Cigarette smoke induction of osteopontin (SPP1) mediates T(H)17 inflammation in human and experimental emphysema

Smoking-related lung diseases are among the leading causes of death worldwide, underscoring the need to understand their pathogenesis and develop new effective therapies. We have shown that CD1a+ antigen-presenting cells (APCs) from lungs of patients with emphysema can induce autoreactive T helper 1 (T(H)1) and T(H)17 cells. Similarly, the canonical cytokines interferon-γ (IFN-γ) and interleukin-17A (IL-17A) are specifically linked to lung destruction in smokers, but how smoke activates APCs to mediate emphysema remains unknown. Here, we show that, in addition to increasing IFN-γ expression, cigarette smoke increased the expression of IL-17A in both CD4+ and γδ T cells from mouse lung. IL-17A deficiency resulted in attenuation of, whereas lack of γδ T cells exacerbated, smoke-induced emphysema in mice. Adoptive transfer of lung APCs isolated from mice with emphysema revealed that this cell population was capable of transferring disease even in the absence of active smoke exposure, a process that was dependent on IL-17A expression. Spp1 (the gene for osteopontin) was highly expressed in the pathogenic lung APCs of smoke-exposed mice and was required for the T(H)17 responses and emphysema in vivo, in part through its inhibition of the expression of the transcription factor Irf7. Thus, the Spp1-Irf7 axis is critical for induction of pathological T(H)17 responses, revealing a major mechanism by which smoke activates lung APCs to induce emphysema and identifying a pathway that could be targeted for therapeutic purposes.

Association between obstructive lung disease and markers of HIV infection in a high-risk cohort

BACKGROUND

Evidence suggests an association between HIV infection and the presence of obstructive lung disease (OLD). However, the associations between specific markers of HIV infection and OLD remain unclear. A study was undertaken to determine the independent associations of HIV infection, CD4 cell count and plasma HIV viral load with the presence of OLD in an urban cohort.

METHODS

Clinical, laboratory and spirometric data from the AIDS Linked to the Intravenous Experience (ALIVE) study, an observational study of current and former injection drug users in Baltimore, Maryland, were analysed. Multivariable logistic regression models were generated to identify HIV infection indices independently associated with OLD.

RESULTS

Of 1077 participants (mean±SD age 48±8 years), 89% were African-American, 65% were men and 86% were current smokers. A total of 303 (28%) were HIV infected and 176 (16%) had spirometry-defined OLD. Higher viral load was independently associated with OLD. HIV-infected individuals with viral load >200,000 copies/ml had a 3.4-fold increase in the odds of OLD compared with HIV-negative participants (95% CI 1.24 to 9.39; p=0.02). The association between higher HIV viral load and OLD persisted after accounting for antiretroviral therapy use (OR 4.06, 95% CI 1.41 to 11.7; p=0.01). No association was observed between HIV serostatus or CD4 cell count and the presence of OLD.

CONCLUSION

In a cohort at risk for OLD and HIV infection, high viral load but not CD4 cell count was associated with an increased prevalence of spirometry-defined OLD. These findings suggest that higher viral load may contribute mechanistically to the increased risk of OLD in patients with HIV infection.

The pathogenesis of COPD and IPF: distinct horns of the same devil?

New paradigms have been recently proposed in the pathogenesis of both chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), evidencing surprising similarities between these deadly diseases, despite their obvious clinical, radiological and pathologic differences. There is growing evidence supporting a "double hit" pathogenic model where in both COPD and IPF the cumulative action of an accelerated senescence of pulmonary parenchyma (determined by either telomere dysfunction and/or a variety of genetic predisposing factors), and the noxious activity of cigarette smoke-induced oxidative damage are able to severely compromise the regenerative potential of two pulmonary precursor cell compartments (alveolar epithelial precursors in IPF, mesenchymal precursor cells in COPD/emphysema). The consequent divergent derangement of signalling pathways involved in lung tissue renewal (mainly Wnt and Notch), can eventually lead to the distinct abnormal tissue remodelling and functional impairment that characterise the alveolar parenchyma in these diseases (irreversible fibrosis and bronchiolar honeycombing in IPF, emphysema and airway chronic inflammation in COPD).

Gene expression profiles of alveolar type II cells of chronic obstructive pulmonary disease: a case-control study

OBJECTIVES

The aim of this study was to identify the gene expression pattern specific in alveolar epithelial type II cells (ATII cells) isolated from patients with chronic obstructive pulmonary disease (COPD).

DESIGN

Case control.

SETTING

Two hospitals in Japan.

PARTICIPANTS

Three patients without COPD and three patients with COPD in microarray analyses. Five smokers without COPD and nine smokers with COPD in the following analyses. PRIMARY AND SECONDARY OUTCOME MEASURED: Primary outcome included identification of differentially expressed genes and activated or inhibited pathways in ATII cells of the patients with COPD, compared to those of the patients without COPD, using Affymetrix gene expression arrays. Secondary outcome included validation of the results of microarray analyses by quantitative reverse transcription-PCR.

RESULTS

We isolated ATII cells from COPD and non-COPD lungs using fluorescence-activated cell sorting. We performed Affymetrix gene expression arrays on both types of ATII cells. Gene set enrichment analyses revealed that two major gene sets were enriched in ATII cells from COPD lungs: interferon-responsive gene sets and gene sets associated with cell cycle progression. Gene ontology term enrichment analyses indicated that among the interferon-stimulated genes, ATII cells in COPD expressed genes such as PSMB8, PSMB9, TAP1 and TAP2 associated with the antigen processing and presentation pathway. We validated the results of the microarray analyses using quantitative reverse transcriptase-PCR. In addition, FACS analysis indicated that the percentage of ATII cells to CD45-negative lung cells isolated from COPD lungs were significantly increased more than that from non-COPD lungs.

CONCLUSIONS

Our study demonstrated that interferon-stimulated genes involved in the antigen processing and presentation pathway and genes involved in cell cycle progression were enriched in ATII cells of the patients with COPD. These pathways might alter phenotypes of ATII cells in COPD lungs.

Inducible NOS inhibition reverses tobacco-smoke-induced emphysema and pulmonary hypertension in mice

Chronic obstructive pulmonary disease (COPD) is one of the most common causes of death worldwide. We report in an emphysema model of mice chronically exposed to tobacco smoke that pulmonary vascular dysfunction, vascular remodeling, and pulmonary hypertension (PH) precede development of alveolar destruction. We provide evidence for a causative role of inducible nitric oxide synthase (iNOS) and peroxynitrite in this context. Mice lacking iNOS were protected against emphysema and PH. Treatment of wild-type mice with the iNOS inhibitor N(6)-(1-iminoethyl)-L-lysine (L-NIL) prevented structural and functional alterations of both the lung vasculature and alveoli and also reversed established disease. In chimeric mice lacking iNOS in bone marrow (BM)-derived cells, PH was dependent on iNOS from BM-derived cells, whereas emphysema development was dependent on iNOS from non-BM-derived cells. Similar regulatory and structural alterations as seen in mouse lungs were found in lung tissue from humans with end-stage COPD.

The role of small airways in obstructive airway diseases

This review article is a summary of a seminar organised by the European Respiratory Society on "The role of small airways in obstructive airway diseases" which was held in October 2010 in Amsterdam, the Netherlands. The aims of the seminar were to identify important questions related to small airways involvement in asthma and chronic obstructive pulmonary disease (COPD), and to discuss future approaches based on current and evolving knowledge. Data obtained by pathological and physiological measurements in small airways and their relevance to clinical manifestations and therapeutics in asthma and COPD were reviewed. It was concluded that our knowledge on the roles of small airways in asthma and COPD is limited. Studies of large numbers of well-characterised subjects using multiple methods (genetic characterisation, cell biology and physiology, imaging) and integration of the data using mathematical models are suggested to be of interest. The availability of these techniques coupled with our ability to better target inhaled molecules to small airways provide a unique opportunity for a reappraisal of the relevance of small airways in chronic airway diseases.

Anti-interleukin-17 antibodies attenuate airway inflammation in tobacco-smoke-exposed mice

CONTEXT

Our previous study showed that the interleukin-17 (IL-17) concentration in lung tissue and in bronchoalveolar lavage fluid (BALF) of rats with tobacco-smoke-induced chronic obstructive pulmonary disease (COPD) was higher than that of control group. However, whether IL-17 inhibitor could decrease the effect of tobacco smoking is not known yet.

OBJECTIVES

To investigate the significance of IL-17 antibodies (Ab) in tobacco-smoke-exposed (TSE) mice.

MATERIALS AND METHODS

Male C57/BL6 mice were randomly divided into three groups: TSE group, TSE + anti-IL-17 Ab group, and control group. The number of cells in BALF and the concentrations of IL-17, IL-6, IL-8 and MUC5AC in BALF and lung tissue homogenate were measured. Pulmonary function was measured by pressure sensors, and histologic analysis of the lungs was done in each group.

RESULTS

Lung function tests in TSE + anti-IL-17 Ab group were the same compared with TSE group (P > 0.05). The total cell count and the number of neutrophil cells in BALF were significantly higher in TSE group than the normal control group (P < 0.01). Compared with the TSE group, the total cell count in TSE + anti-IL-17 Ab group was decreased, and the percentage of neutrophils in BALF was highly decreased (P < 0.01). Airway inflammation was alleviated in TSE + anti-IL-17 Ab group by histologic analysis. The concentrations of IL-17 in lung tissue were significantly lower in TSE + anti-IL-17 Ab group than in TSE group (P < 0.01). IL-17 was mainly expressed in the epithelial cells in the airways of TSE mice. The concentration of IL-6, IL-8 and MUC5AC in BALF was decreased in TSE + anti-IL-17 Ab group compared with TSE group.

DISCUSSION AND CONCLUSIONS

These data support a potential role for IL-17 in airway neutrophilic inflammation in TSE mice. Anti-IL-17 decreased the number of neutrophils as well as the concentration of MUC5AC in the BALF and attenuated neutrophilic airway inflammation.

Role of th17 cell and autoimmunity in chronic obstructive pulmonary disease

The molecular mechanisms involved in the pathogenesis of chronic obstructive pulmonary disease (COPD) are poorly defined. Accumulating evidences indicate that chronic inflammatory responses and adaptive immunity play important roles in the development and progression of the disease. Recently, it has been shown that IL-17 producing CD4 T cells, named Th17 cells, which have been implicated in the pathogenesis of several inflammatory and autoimmune diseases, are involved in airway inflammation and COPD. In addition, we and others suggest that autoimmunity may play a critical role in the pathogenesis of COPD. Here, we will review the current understanding of roles of Th17 cells and autoimmune responses in COPD.