The lymphocytic alveolitis in sarcoidosis is associated with increased amounts of soluble and cell-bound adhesion molecules in bronchoalveolar lavage fluid and serum

Selectins in Biology and Human Disease: Opportunity in E-selectin Antagonism

Selectins are cell adhesion proteins discovered in the 1980s. As C-type lectins, selectins contain an essential calcium ion in the ligand-binding pocket and recognize the isomeric tetrasaccharides sialyl Lewisx (sLex) and sialyl Lewisa (sLea). Three selectins, E-selectin, P-selectin, and L-selectin, play distinct, complementary roles in inflammation, hematopoiesis, and tumor biology. They have been implicated in the pathology of diverse inflammatory disorders, and several selectin antagonists have been tested clinically. E-selectin plays a unique role in leukocyte activation, making it an attractive target for intervention, for example, in sickle cell disease (SCD). This review summarizes selectin biology and pathology, structure and ligand binding, and selectin antagonists that have reached clinical testing with an emphasis on E-selectin.

Novel Ligands Targeting α4β1 Integrin: Therapeutic Applications and Perspectives

Among the other members of the adhesion molecules' family, α4β1 integrin, a heterodimeric receptor, plays a crucial role in inflammatory diseases, cancer development, metastasis and stem cell mobilization or retention. In many cases, its function in pathogenesis is not yet completely understood and investigations on ligand binding and related stabilization of active/inactive conformations still represent an important goal. For this reason, starting from the highlight of α4β1 functions in human pathologies, we report an overview of synthetic α4β1 integrin ligands under development as potential therapeutic agents. The small molecule library that we have selected represents a collection of lead compounds. These molecules are the object of future refinement in academic and industrial research, in order to achieve a fine tuning of α4β1 integrin regulation for the development of novel agents against pathologies still eluding an effective solution.

Integrins as Therapeutic Targets for Respiratory Diseases

Integrins are a large family of transmembrane heterodimeric proteins that constitute the main receptors for extracellular matrix components. Integrins were initially thought to be primarily involved in the maintenance of cell adhesion and tissue integrity. However, it is now appreciated that integrins play important roles in many other biological processes such as cell survival, proliferation, differentiation, migration, cell shape and polarity. Lung cells express numerous combinations and permutations of integrin heterodimers. The complexity and diversity of different integrin heterodimers being implicated in different lung diseases present a major challenge for drug development. Here we provide a comprehensive overview of the current knowledge of integrins from studies in cell culture to integrin knockout mouse models and provide an update of results from clinical trials for which integrins are therapeutic targets with a focus on respiratory diseases (asthma, emphysema, pneumonia, lung cancer, pulmonary fibrosis and sarcoidosis).

Efficient generalized least squares method for mixed population and family-based samples in genome-wide association studies

Genome-wide association studies (GWAS) that draw samples from multiple studies with a mixture of relationship structures are becoming more common. Analytical methods exist for using mixed-sample data, but few methods have been proposed for the analysis of genotype-by-environment (G×E) interactions. Using GWAS data from a study of sarcoidosis susceptibility genes in related and unrelated African Americans, we explored the current analytic options for genotype association testing in studies using both unrelated and family-based designs. We propose a novel method-generalized least squares (GLX)-to estimate both SNP and G×E interaction effects for categorical environmental covariates and compared this method to generalized estimating equations (GEE), logistic regression, the Cochran-Armitage trend test, and the WQLS and MQLS methods. We used simulation to demonstrate that the GLX method reduces type I error under a variety of pedigree structures. We also demonstrate its superior power to detect SNP effects while offering computational advantages and comparable power to detect G×E interactions versus GEE. Using this method, we found two novel SNPs that demonstrate a significant genome-wide interaction with insecticide exposure-rs10499003 and rs7745248, located in the intronic and 3' UTR regions of the FUT9 gene on chromosome 6q16.1.

The α4β1 integrin in localization of Mycobacterium tuberculosis-specific T helper type 1 cells to the human lung

Rapid mobilization of antigen-specific T helper (Th) type 1-like CD4(+) T cells to the lung appears to be critically important for control of the respiratory pathogen Mycobacterium tuberculosis (M. tb), and for protection against pulmonary tuberculosis, the most contagious form of the disease. Accordingly, the preferential circulation of memory lymphocytes back to the tissues in which they first encountered antigen (i.e., "homing") may underlie the limited efficacy of current intradermal vaccination with the M. bovis strain bacillus Calmette-Guerrin. We previously developed a method of bronchoscopic antigen challenge with purified protein derivative of M. tb (PPD) to model local recall responses of healthy PPD-positive individuals who were infected via respiratory exposure to M. tb. Bronchoscopic challenge with PPD results in recruitment of additional antigen-specific Th1-like cells into challenged lung segments of healthy M. tb-infected individuals but not those of PPD-negative control subjects. In this study, we assessed the role of homing molecule expression in localization of M. tb-specific recall responses to the lung. Compared with peripheral blood, baseline bronchoalveolar lavage is significantly enriched for CD4(+) T cells expressing the α4β1 integrin homing molecule. This skewing is continued after PPD-induced recruitment of CD4(+) T cells, and is even more pronounced for recruited CD4(+) cells that display PPD-specific production of IFN-γ, of which over 83% express α4β1. Expression of the α4β1 integrin, therefore, appears likely to optimize localization of M. tb-specific Th1-like recall responses to the human lung.

T-cell activation profiles in different granulomatous interstitial lung diseases--a role for CD8+CD28(null) cells?

Lymphocytes play a crucial role in lung inflammation. Different interstitial lung diseases may show distinct lymphocyte activation profiles. The aim of this study was to examine the expression of a variety of activation markers on T lymphocyte subsets from blood and bronchoalveolar lavage fluid (BALF) of patients with different granulomatous interstitial lung diseases and healthy controls. Bronchoalveolar lavage cells and blood cells from 23 sarcoidosis patients, seven patients with hypersensitivity pneumonitis and 24 healthy controls were analysed. Lymphocyte activation status was determined by flow cytometry. Lymphocytes were stained with antibodies against CD3, CD4, CD8, CD25, CD28, CD69, very late antigen-1 (VLA)-1, VLA-4 and human leucocyte antigen D-related (HLA-DR). In general, CD28, CD69 and VLA-1 expression on BALF CD4+ lymphocytes and HLA-DR expression on BALF CD8+ lymphocytes was different in patients with hypersensitivity pneumonitis and sarcoidosis patients with parenchymal involvement. This BALF lymphocyte phenotype correlated with carbon monoxide diffusing lung capacity (Dlco) values across interstitial lung diseases (ILD) (r2 = 0.48, P = 0.0002). In sarcoidosis patients, CD8+CD28(null) blood lymphocytes correlated with lower Dlco values (r = -0.66, P = 0.004), chronic BALF lymphocyte activation phenotype (r2 = 0.65, P < 0.0001), radiographic staging (stage I versus stage II and higher, P = 0.006) and with the need for corticosteroid treatment (P = 0.001). Higher expression of CD69, VLA-1 and HLA-DR and lower expression of CD28 on BALF lymphocytes suggests prolonged stimulation and chronic lymphocyte activation in patients with ILD. In sarcoidosis, blood CD8+CD28(null) cells might be a new biomarker for disease severity but needs further investigation.

The immunology of sarcoidosis

Sarcoidosis continues to be a disease of research interest because of its complicated immune mechanisms and elusive etiology. So far, it has been established that granulomatous inflammation in sarcoidosis is predominantly a T-helper 1 immune response mediated by a complex network of lymphocytes, macrophages, and cytokines. The cause of progression to a chronic and potentially fibrotic form is unclear but may involve loss of apoptotic mechanisms, loss of regulatory response, or a persistent antigen that cannot be cleared. Recent genomic and proteomic technology has emphasized the importance of host susceptibility and gene-environment interaction in the expression of the disease.

Perforin Down-Regulation and Adhesion Molecules Activation in Pulmonary Sarcoidosis

BACKGROUND

Sarcoidosis is thought to be a T-helper type 1 cytokine-mediated disorder. Sputum induction has been proposed as a useful noninvasive method mainly for the assessment of airway diseases. However, it is unknown whether the balance of T-cytotoxic (Tc1) type 1 and Tc2 cells is altered in sarcoidosis.

STUDY OBJECTIVES

The primary aim of this study was to characterize the CD8+ T lymphocyte subpopulations in induced sputum from sarcoidosis patients, and to compare these subpopulations to those found in BAL fluid (BALF) from sarcoidosis patients. To further investigate the mechanism of the cytotoxic activity of CD8+ lymphocytes, we measured their perforin expression. Additionally, two adhesion molecules (CD62 and CD71), which are expressed on CD8+ T cells and may serve as novel immunologic markers, were detected.

SETTINGS

Department of Thoracic Medicine, University of Crete, and Department of Pneumonology, Democritus University of Thrace, Alexandroupolis, Greece.

PATIENTS

We prospectively studied 22 patients with sarcoidosis (median age, 48 years; age range, 25 to 65 years) and 10 healthy subjects (5 female and 5 male; median age, 39 years; age range, 26 to 60 years).

INTERVENTIONS

The stimulation of lymphocytes with phorbol 12-myristate 13-acetate was followed by the use of double immunocytochemical methods to identify CD8+ interferon (IFN)-gamma producing cells (ie, Tc1) and CD8+ interleukin-4 producing cells (ie, Tc2).

MEASUREMENTS AND RESULTS

We found a significant decrease in the prestimulation percentage of IFN-gamma-positive CD8+ T cells in the BALF (p = 0.001) and induced sputum (p = 0.001) of sarcoidosis patients compared to the number in samples from healthy control subjects. However, no significant difference was documented between lymphocyte subsets poststimulation. Decreased levels of perforin expression were found in BALF (p = 0.001) and induced sputum (p < 0.001) of sarcoidosis patients compared to those in control subjects. The adhesion molecules were significantly increased in both the BALF and induced sputum of the sarcoid population compared to those in healthy control subjects.

CONCLUSIONS

Our results suggest that inflammation could be effectively and noninvasively determined by using sputum induction in sarcoidosis patients. In addition, we have provided evidence suggesting the possibility that CD8+ lymphocytes might not play a major role in sarcoidosis.

Pulmonary sarcoidosis with usual interstitial pneumonia distributed predominantly in the lower lung fields

Nodular and reticular opacities were detected in both lower lung fields of a 75-year-old man in 2000. Bronchoscopy revealed pulmonary sarcoidosis. In 2002, nodular and reticular opacities were shown in the right upper lobe, and video-assisted thoracoscopic surgery was performed. The histological findings revealed usual interstitial pneumonia (UIP)-like lesions, whereas non-caseous granulomas were not detected. In the present case of pulmonary sarcoidosis, nodular and reticular opacities were predominantly distributed in both lower lung fields, and the histological findings obtained by video-assisted thoracoscopic surgery showed UIP-like lesions. These findings may enlighten the assist in understanding of the process of development of pulmonary sarcoidosis.

Serum amyloid A and high-density lipoprotein cholesterol: serum markers of inflammation in sarcoidosis and other systemic disorders

Hypocholesterolemia has been observed in several inflammatory diseases such as rheumatoid arthritis, myeloproliferative disorders, systemic lupus erythematosus and sarcoidosis. Serum amyloid A is an acute-phase reactant that is related to the high-density lipoprotein cholesterol. This review discusses the relationship between the activation of the cells of the monocyte-macrophage system, determined by the serum amyloid A levels, and the lipid metabolism, measured as alterations in plasma lipoprotein concentrations. The mechanisms of this association during acute inflammation are also discussed in this review.

Elevated levels of soluble adhesion molecules in sera and BAL fluid of individuals infected with human T-cell lymphotropic virus type 1

STUDY OBJECTIVE

T-lymphocytic alveolitis and increased levels of interleukin-2 receptor-alpha (CD25)-bearing T cells in the BAL fluid (BALF) of human T-cell lymphotropic virus type 1 (HTLV-1) carriers have been reported. Several chemokines and adhesion molecules may contribute to the accumulation of T lymphocytes in the lungs of HTLV-1 carriers. To clarify the correlation between adhesion molecules and HTLV-1-associated pulmonary disorders, we compared the distribution of T-lymphocyte subsets and soluble adhesion molecules, including soluble intercellular adhesion molecule (sICAM)-1, soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble L-selectin (sL-selectin), soluble E-selectin (sE-selectin), and soluble P-selectin (sP-selectin), in BALF and peripheral blood, between HTLV-1 carriers and noninfected healthy subjects.

DESIGN

Flow cytometric analysis with monoclonal antibodies to cell-surface antigens was used to identify T-lymphocyte subsets in BALF samples from HTLV-1 carriers (n = 13) and noninfected healthy control subjects (n = 10). The levels of various soluble adhesion molecules in serum and in BALF were estimated by enzyme-linked immunosorbent assay.

RESULTS

Higher percentages of CD3+ cells, CD3-expressing human leukocyte antigen-DR antigen, and CD3+CD25+ cells were detected in the BALF of HTLV-1 carriers than in that of noninfected control subjects. The concentrations of sICAM-1, sVCAM-1, sL-selectin, SE- selectin, and sP-selectin in the sera of patients were significantly higher than those in noninfected healthy control subjects. The concentration of sICAM-1 in the BALF of patients was significantly higher than that in noninfected healthy control subjects, and the concentration of sICAM-1 correlated well with the percentage of CD3+CD25+ cells.

CONCLUSION

The concentrations of adhesion molecules in the sera of and sICAM-1 in the BALF of HTLV-1 carriers were significantly higher than those in noninfected individuals, and the concentration of sICAM-1 correlated well with the percentage of CD3+CD25+ cells in BALF. Our results suggest a possible interaction between activated T cells bearing CD25 and soluble adhesion molecules, especially sICAM-1, which may contribute to the pulmonary involvement in HTLV-1 carriers.

Possible role of L-selectin in T lymphocyte alveolitis in patients with active pulmonary sarcoidosis

A number of adhesion molecules participate in the recruitment of inflammatory cells to the site of inflammation, and selectins together with their ligands are important in the early transient adhesion phase. In this study, we evaluated the role of L-selectin in T lymphocyte alveolitis in patients with active pulmonary sarcoidosis. We measured serum and bronchoalveolar lavage fluid (BALF) concentrations of soluble (s)L-selectin using an ELISA. Serum and BALF concentrations of sL-selectin were significantly elevated in patients with sarcoidosis compared with control healthy subjects and idiopathic pulmonary fibrosis (IPF) patients (P < 0.05 and P < 0. 01, respectively). The lymphocyte surface marker was also examined in peripheral blood and BALF by flow cytometric analysis. The percentage of CD3+CD62L+ cells (L-selectin-bearing T lymphocytes) was significantly lower in peripheral blood of sarcoidosis than in that of healthy subjects (P < 0.01). In contrast, the percentage of CD3+CD62L- cells (L-selectin-negative T lymphocytes) in BALF of patients with sarcoidosis was significantly higher than in healthy subjects (P < 0.05) and IPF patients (P < 0.01). Furthermore, there was a significant correlation between serum concentrations of sL-selectin and the number of L-selectin-negative T lymphocytes in BALF (r = 0.535, P < 0.01). Our results suggest that L-selectin may be involved in T lymphocyte alveolitis in patients with active pulmonary sarcoidosis.

Phenotypic analysis of lymphocytes and monocytes/macrophages in peripheral blood and bronchoalveolar lavage fluid from patients with pulmonary sarcoidosis

BACKGROUND

The granulomatous inflammation in sarcoidosis is driven by the interplay between T cells and macrophages. To gain a better understanding of this process the expression by these cells of cell surface activation markers, co-stimulatory molecules, and adhesion molecules was analysed.

METHODS

CD4+ and CD8+ T lymphocytes from peripheral blood (PBL) or bronchoalveolar lavage (BAL) fluid, as well as paired peripheral blood monocytes and alveolar macrophages from 27 patients with sarcoidosis were analysed by flow cytometry.

RESULTS

CD26, CD54, CD69, CD95, and gp240 were all overexpressed in T cells from BAL fluid compared with those from PBL in both the CD4+ and CD8+ subsets, while CD57 was overexpressed only in BAL CD4+ cells. In contrast, CD28 tended to be underexpressed in the BAL T cells. Monocyte/macrophage markers included CD11a, CD11b, CD11c, CD14, CD16, CD54, CD71, CD80 and CD86 and HLA class II. CD11a expression in alveolar macrophages (and peripheral blood monocytes) was increased in patients with active disease and correlated positively with the percentage of BAL lymphocytes. Expression of CD80 in macrophages correlated with the BAL CD4/CD8 ratio.

CONCLUSIONS

Our data indicate substantial activation of both CD4+ and CD8+ lung T cells in sarcoidosis. There were also increased numbers of BAL lymphocytes whose phenotypic characteristics have earlier been associated with clonally expanded, replicatively senescent cells of the Th1 type.