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Chronic obstructive pulmonary disease (COPD) is characterized by an excessive inflammatory response to inhaled particles, mainly tobacco smoking. T lymphocytes are important regulatory cells that secrete several cytokines and participate actively in this inflammatory response. According to the pattern of cytokines secreted, the immune response is classified as cytotoxic or type 1 [interferon (IFN)-γ-, interleukin (IL)-2-dependent] and humoral or type 2 (IL-4-, IL-5-, IL-10- and IL-13-dependent). This paper sought to compare the intracellular profile of cytokine expression determined by flow cytometry in T lymphocytes harvested from bronchoalveolar lavage (BAL) and peripheral blood in patients with COPD, smokers with normal lung function and never smokers. We found that BAL T lymphocytes from COPD patients had a higher percentage of positive stained cells for most of the cytokines analysed when compared to never smokers or smokers with normal lung function. Differences reached statistical significance for IL-4, IL-10 and IL-13, particularly in CD8+ T cells. Furthermore, the expression of most of these cytokines was related inversely to the degree of airflow obstruction present suggesting local activation and/or selective homing of T lymphocytes to the lungs in COPD patients. These observations were not reproduced in circulating T lymphocytes. These results suggest that BAL T lymphocytes in patients with COPD produce more cytokines than in controls and tend to show a type 2 pattern of intracellular cytokine expression, particularly a Tc-2 profile. This is related inversely to the degree of airflow obstruction present. [ABSTRACT FROM AUTHOR]

Costimulatory molecules are cell surface glycoproteins that can direct, modulate and fine-tune T-cell receptor signals. The B7-1/B7-2–CD28/CTLA-4 and ICOS–B7RP-1 pathway provides key second signals that can regulate the activation, inhibition and fine-tuning of T-lymphocyte responses. The expression of B7-1/B7-2–CD28/CTLA-4 molecules on clinical samples from patients with asthma have been well studied, and the results indicate that different extents of these molecules are expressed on the surface of various cells, and that the concentrations of soluble form of these molecules are elevated in the sera of patients with asthma. There is a burst of papers describing an important role for B7-1/B7-2–CD28/CTLA-4 pathway in the Th1/Th2 balance. Similarly, ICOS stimulates both Th1 and Th2 cytokine production but may have a preferential role in Th2 cell development. Moreover, The B7-1/B7-2–CD28/CTLA-4 and ICOS–B7RP-1 pathway has been suggested of being involved in the development of airway inflammation and airway hyperresponsiveness. Further study of the functions of the pathways within the CD28/CTLA-4–CD80/CD86 and ICOS–B7RP-1 superfamily individually and their interplay should provide insights into the pathogenesis of asthma, and has great therapeutic potential for treatment of asthma. [ABSTRACT FROM AUTHOR]

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 (Tlr4WT) and C3H/HeJ (Tlr4defective) mice were exposed to air or CS for 5 weeks (subacute) and 26 weeks (chronic), and pulmonary inflammation was evaluated. Results: In Tlr4WT 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, Tlr4defective 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 Tlr4WT animals. After chronic CS exposure, however, the difference in pulmonary inflammation between Tlr4WT and Tlr4defective 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. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]