The role of the CC chemokine, RANTES, in acute lung allograft rejection

Lung transplantation is a therapeutic option for patients with end-stage lung disease. Acute allograft rejection is a major complication of lung transplantation and is characterized by the infiltration of activated mononuclear cells. The specific mechanisms that recruit these leukocytes have not been fully elucidated. The CC chemokine, RANTES, is a potent mononuclear cell chemoattractant. In this study we investigated RANTES involvement during acute lung allograft rejection in humans and in a rat model system. Patients with allograft rejection had a 2.3-fold increase in RANTES in their bronchoalveolar lavages compared with healthy allograft recipients. Rat lung allografts demonstrated a marked time-dependent increase in levels of RANTES compared with syngeneic control lungs. RANTES levels correlated with the temporal recruitment of mononuclear cells and the expression of RANTES receptors CCR1 and CCR5. To determine RANTES involvement in lung allograft rejection, lung allograft recipients were passively immunized with either anti-RANTES or control Abs. In vivo neutralization of RANTES attenuated acute lung allograft rejection and reduced allospecific responsiveness by markedly decreasing mononuclear cell recruitment. These experiments support the idea that RANTES, and the expression of its receptors have an important role in the pathogenesis of acute lung allograft rejection.     

T Cell Ig- and mucin-domain-containing molecule-3 (TIM-3) and TIM-1 molecules are differentially expressed on human Th1 and Th2 cells and in cerebrospinal fluid-derived mononuclear cells in multiple sclerosis

T cell Ig- and mucin-domain-containing molecules (TIMs) comprise a recently described family of molecules expressed on T cells. TIM-3 has been shown to be expressed on murine Th1 cell clones and has been implicated in the pathogenesis of Th1-driven experimental autoimmune encephalomyelitis. In contrast, association of TIM-1 polymorphisms to Th2-related airway hyperreactivity has been suggested in mice. The TIM molecules have not been investigated in human Th1- or Th2-mediated diseases. Using real-time (TaqMan) RT-PCR, we show that human Th1 lines expressed higher TIM-3 mRNA levels, while Th2 lines demonstrated a higher expression of TIM-1. Analysis of cerebrospinal fluid mononuclear cells obtained from patients with multiple sclerosis revealed significantly higher mRNA expression of TIM-1 compared with controls. Moreover, higher TIM-1 expression was associated with clinical remissions and low expression of IFN-gamma mRNA in cerebrospinal fluid mononuclear cells. In contrast, expression of TIM-3 correlated well with high expression of IFN-gamma and TNF-alpha. These data imply the differential expression of human TIM molecules by Th1 and Th2 cells and may suggest their differential involvement in different phases of a human autoimmune disease.     

Isolation and characterization of mononuclear cells from various thyroid tissue specimens

Extensive studies of humoral and cell mediated autoimmune responses to thyroid antigens have been performed in order to understand the underlying mechanisms of autoimmune thyroid disorders. Very little is known, however, about the nature of the lymphocyte subpopulations in the thyroid gland and their possible involvement in the pathogenesis of thyroid diseases. We have developed a Percoll gradient technique to separate mononuclear cells from thyroid cells of resected thyroid glands. Thyroid tissue was minced, incubated with Dispase and passed through a tissue sieve. The filtrate was layered onto a four step discontinuous Percoll gradient (densities 1.140, 1.077, 1.061, 1.030 g/ml). Thyroid cells appeared in band II and mononuclear cells in band III. Mononuclear cells were characterized using the monoclonal antibodies OKT-3, OKT-8, OKI-a and OKM-1, and the levels of these populations in peripheral blood and thyroid tissue compared. Patients have been classified by conventional clinical, immunological and histological criteria. The studies involved thyroid tissues from 8 patients with euthyroid nodular goitre, 7 patients with Graves' disease and 1 with Hashimoto's thyroiditis. In the thyroid tissue of non-autoimmune thyroid diseases we find significantly less OKT-3+ cells compared to peripheral blood. In thyroid tissue of autoimmune thyroid diseases there are significantly less OKT-8+ cells compared to peripheral blood. These preliminary results might be linked to the hypothesis of decreased suppressor T-cell activity in autoimmune thyroid disease.     

Expression of Fas antigen in the cells from bronchoalveolar lavage fluid (BALF)

Fas antigen is a cell surface receptor protein that mediates apoptosis expressed in various cells. In this study Fas expression was examined in cells of patients with lung diseases in which changes in the lung immunology were documented. We have performed bronchoalveolar lavage (BAL) in 24 patients with sarcoidosis (8), lung fibrosis (9), primary lung cancer (7), and we compared expression of Fas in BALF cells from all groups and healthy volunteers (6). Fas protein was detected by immunocytochemistry using APAAP technique with an LSAB 2 kit (Dako). Positive reactions for Fas were found in the cytoplasm of epithelial cells, macrophages, neutrophils and lymphocytes (according to the intensity). There were some differences in proportion of positive cells and intensity of reaction between patients with interstitial lung diseases, healthy volunteers as well as patients with lung cancer. Higher expression of Fas in alveolar macrophages was observed in patients with sarcoidosis, lower in patients with lung cancer, lung fibrosis and the lowest in healthy persons. The analysis of Fas antigen expression in the BALF cells may be useful in evaluation of the role of apoptosis in lung homeostasis and pathology.     

Role of CXCL9/CXCR3 chemokine biology during pathogenesis of acute lung allograft rejection

Acute allograft rejection is a major complication postlung transplantation and is the main risk factor for the development of bronchiolitis obliterans syndrome. Acute rejection is characterized by intragraft infiltration of activated mononuclear cells. The ELR-negative CXC chemokines CXCL9, CXCL10, and CXCL11) are potent chemoattractants for mononuclear cells and act through their shared receptor, CXCR3. Elevated levels of these chemokines in bronchoalveolar lavage fluid have been associated with human acute lung allograft rejection. This led to the hypothesis that the expression of these chemokines during an allogeneic response promotes the recruitment of mononuclear cells, leading to acute lung allograft rejection. We performed studies in a rat orthotopic lung transplantation model of acute rejection, and demonstrated increased expression of CXCL9 and CXCL10 paralleling the recruitment of mononuclear cells and cells expressing CXCR3 to the allograft. However, CXCL9 levels were 15-fold greater than CXCL10 during maximal rejection. Inhibition of CXCL9 decreased intragraft recruitment of mononuclear cells and cellular expression of CXCR3, resulting in lower acute lung allograft rejection scores. Furthermore, the combination of low dose cyclosporin A with anti-CXCL9 therapy had more profound effects on intragraft leukocyte infiltration and in reducing acute allograft rejection scores. This supports the notion that CXCL9 interaction with cells expressing CXCR3 has an important role in the recruitment of mononuclear cells, a pivotal event in the pathogenesis of acute lung allograft rejection.     

Intermediate filaments of the lung

Intermediate filaments (IF), a subfamily of the cytoskeletal filaments, provide structural support to cells. Human diseases related to mutations in IF proteins in which their tissue-specific expression is reflected have been found in a broad range of patients. The properties of identified IF mutants are well-studied in vitro in cultured cells and in vivo using transgenic mice expressing IF mutants. However, the association of IF proteins with diseases of the lung is not fully studied yet. Epithelial cells in normal lung express vimentin and various keratins, and the patterns of their expression are altered depending on the progression of the lung diseases. A growing number of studies performed in alveolar epithelial cells demonstrated IF involvement in disease-related aspects including their usefulness as tumor marker, in epithelial-mesenchymal transition and cell migration. However, the lung disease-associated IF functions in animal models are poorly understood, and IF mutations associated with lung diseases in humans have not been reported. In this review, we summarize recent studies that show the significance of IF proteins in lung epithelial cells. Understanding these aspects is an important prerequisite for further investigations on the role of lung IF in animal models and human lung diseases.     

Critical role for CXCR3 chemokine biology in the pathogenesis of bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is the major limitation to survival post-lung transplantation and is characterized by a persistent peribronchiolar inflammation that eventually gives way to airway fibrosis/obliteration. Acute rejection is the main risk factor for the development of BOS and is characterized by a perivascular/bronchiolar leukocyte infiltration. The specific mechanism(s) by which these leukocytes are recruited have not been elucidated. The CXC chemokines (monokine induced by IFN-gamma (MIG)/CXC chemokine ligand (CXCL)9, IP-10/CXCL10, and IFN-inducible T cell alpha chemoattractant (ITAC)/CXCL11) act through their shared receptor, CXCR3. Because they are potent leukocyte chemoattractants and are involved in other inflammation/fibroproliferative diseases, we hypothesized that the expression of these chemokines during an allogeneic response promotes the persistent recruitment of mononuclear cells, leading to chronic lung rejection. We found that elevated levels of MIG/CXCL9, IFN-inducible protein 10 (IP-10)/CXCL10, and ITAC/CXCL11 in human bronchoalveolar lavage fluid were associated with the continuum from acute to chronic rejection. Translational studies in a murine model demonstrated increased expression of MIG/CXCL9, IP-10/CXCL10, and ITAC/CXCL11 paralleling the recruitment of CXCR3-expressing mononuclear cells. In vivo neutralization of CXCR3 or its ligands MIG/CXCL9 and IP-10/CXCL10 decreased intragraft recruitment of CXCR3-expressing mononuclear cells and attenuated BOS. This supports the notion that ligand/CXCR3 biology plays an important role in the recruitment of mononuclear cells, a pivotal event in the pathogenesis of BOS.     

Mineral fibre toxicity: expression of retinoblastoma (Rb) and phospho-retinoblastoma (pRb) protein in alveolar epithelial and mesothelial cell lines exposed to fluoro-edenite fibres

Several asbestos-like mineral fibres, including fluoro-edenite, may cause lung cancer and/or other lung diseases. However, biological and molecular mechanisms linked to cancer development after mineral fibre exposure have not been fully investigated. In the present study, human non-malignant mesothelial (MeT-5A) and human bronchoalveolar alveolar epithelial (A549) cell lines were incubated with rising concentrations of fluoro-edenite to evaluate the expression of retinoblastoma (Rb) protein, which has been demonstrated to play an important role in cell cycle control and tumour progression. Intriguingly, these results show that Rb expression was unchanged, while the level of the phosphorylated protein increased significantly in a dose-dependent manner, suggesting an involvement of this regulator protein in the pathogenesis of the lung diseases induced by mineral fibres. In conclusion, fluoro-edenite regulates the expression of phospho-retinoblastoma to trigger a network of signals strictly connected with cell proliferation and neoplastic cell transformation.     

Cadherin-11 contributes to pulmonary fibrosis: potential role in TGF-β production and epithelial to mesenchymal transition

Pulmonary fibrosis, characterized by excess deposition of extracellular matrix by myofibroblasts, is a serious component of chronic lung diseases. Cadherin-11 (CDH11) is increased in wound healing and fibrotic skin. We hypothesized that CDH11 is increased in pulmonary fibrosis and contributes its development. CDH11 expression was assessed in lung tissue from idiopathic pulmonary fibrosis patients. The role of CDH11 in lung fibrosis was determined using the bleomycin model of pulmonary fibrosis, and in vitro analyses were performed on A549 cells during the process of epithelial to mesenchymal transition (EMT). Immunohistochemical studies demonstrated CDH11 expression on fibroblasts, epithelial cells, and alveolar macrophages of patients with pulmonary fibrosis and mice given bleomycin. Interestingly, CDH11-deficient mice had decreased fibrotic endpoints in the bleomycin model of pulmonary fibrosis compared to wild-type mice. Furthermore, anti-CDH11-neutralizing monoclonal antibodies successfully treated established pulmonary fibrosis induced by bleomycin. TGF-β levels were reduced in bronchoalveolar lavage (BAL) fluid, BAL cells, and primary alveolar macrophages from CDH11-deficient mice. Mechanistic studies demonstrated that TGF-β up-regulated CDH11 expression on A549 cells, and inhibition of CDH11 expression using siRNA reduced TGF-β-induced EMT. Together, these results identify CDH11 as a novel therapeutic target for pulmonary fibrosis.     

Interleukin-28A promotes IFN-γ production by peripheral blood mononuclear cells from patients with Behçet’s disease

Behçet’s disease (BD) is an autoimmune disease of unknown etiology. Interleukin-28A (IL-28A) promotes immune responses and may participate in the pathogenesis of autoimmune diseases. To examine the role of IL-28A in the pathogenesis of BD, we measured the expression of IFN-γ and IL-17 by IL-28A-stimulated peripheral blood mononuclear cells (PBMCs) from 19 patients with BD and 16 healthy individuals. We found that IFN-γ and IL-17 were undetectable in the sera from BD patients and control subjects. The mRNA expression and protein production of IFN-γ by IL-28A-stimulated PBMCs from BD patients were significantly increased compared to healthy individuals. No significant difference was observed in the mRNA expression and protein production of IL-17 by IL-28A-stimulated PBMCs between BD patients and normal individuals.     

Secretory leucocyte protease inhibitor inhibits interferon-gamma-induced cathepsin S expression

We have demonstrated that bronchoalveolar lavage fluid from chronic obstructive pulmonary disease patients contains higher levels of interferon-gamma compared with controls. Interferon-gamma is a potent inducer of various cathepsins and matrix metalloproteases. Therefore, we postulated that interferon-gamma could induce protease expression by macrophages in acute and chronic lung disease. Chronic obstructive pulmonary disease patients had greater levels of cathepsin S and matrix metalloprotease-12 in their bronchoalveolar lavage fluid. Macrophages incubated with chronic obstructive pulmonary disease bronchoalveolar lavage fluid exhibited increased expression of cathepsin S and matrix metalloprotease-12, which was inhibited by the addition of interferon-gamma-neutralizing immunoglobulin. Human secretory leukocyte protease inhibitor is an 11.7-kDa cationic non-glycosylated antiprotease synthesized and secreted by cells at the site of inflammation. We have demonstrated that secretory leukocyte protease inhibitor can inhibit interferon-gamma-induced cathepsin S production by macrophages. Pretreatment of macrophages with secretory leukocyte protease inhibitor inhibited interferon-gamma-induced inhibitor kappaB beta degradation and activation of nuclear factor kappaB. Secretory leukocyte protease inhibitor may prove to be therapeutically important as a potential inhibitor of protease expression in chronic obstructive pulmonary disease.