Pulmonary alveolar macrophages from patients with active sarcoidosis express type IV collagenolytic proteinase. An enzymatic mechanism for influx of mononuclear phagocytes at sites of disease activity

SpotLight Proteomics-A IgG-Enrichment Phenotype Profiling Approach with Clinical Implications

Sarcoidosis is a systemic interstitial lung disease of unknown aetiology. Less invasive diagnostics are needed to decipher disease pathology and to distinguish sub-phenotypes. Here we test if SpotLight proteomics, which combines de novo MS/MS sequencing of enriched IgG and co-extracted proteins with subsequent label-free quantification of new and known peptides, can differentiate controls and sarcoidosis phenotypes (Löfgrens and non-Löfgrens syndrome, LS and nonLS). Intra-individually matched IgG enriched from serum and bronchial lavage fluid (BALF) from controls (n = 12), LS (n = 11) and nonLS (n = 12) were investigated. High-resolution mass-spectrometry SpotLight proteomics and uni- and multivariate-statistical analyses were used for data processing. Major differences were particularly observed in control-BALF versus sarcoidosis-BALF. However, interestingly, information obtained from BALF profiles was still present (but less prominent) in matched serum profiles. By using information from orthogonal partial least squares discriminant analysis (OPLS-DA) differentiating 1) sarcoidosis-BALF and control-BALF and 2) LS-BALF vs. nonLS-BALF, control-serum and sarcoidosis-serum (p = 0.0007) as well as LS-serum and nonLS-serum (p = 0.006) could be distinguished. Noteworthy, many factors prominent in identifying controls and patients were those associated with Fc-regulation, but also features from the IgG-Fab region and novel peptide variants. Differences between phenotypes were mostly IgG-specificity related. The results support the analytical utility of SpotLight proteomics which prospectively have potential to differentiate closely related phenotypes from a simple blood test.

TL1A/DR3 axis involvement in the inflammatory cytokine network during pulmonary sarcoidosis

Background

TNF-like ligand 1A (TL1A), a recently recognized member of the TNF superfamily, and its death domain receptor 3 (DR3), firstly identified for their relevant role in T lymphocyte homeostasis, are now well-known mediators of several immune-inflammatory diseases, ranging from rheumatoid arthritis to inflammatory bowel diseases to psoriasis, whereas no data are available on their involvement in sarcoidosis, a multisystemic granulomatous disease where a deregulated T helper (Th)1/Th17 response takes place.

Methods

In this study, by flow cytometry, real-time PCR, confocal microscopy and immunohistochemistry analyses, TL1A and DR3 were investigated in the pulmonary cells and the peripheral blood of 43 patients affected by sarcoidosis in different phases of the disease (29 patients with active sarcoidosis, 14 with the inactive form) and in 8 control subjects.

Results

Our results demonstrated a significant higher expression, both at protein and mRNA levels, of TL1A and DR3 in pulmonary T cells and alveolar macrophages of patients with active sarcoidosis as compared to patients with the inactive form of the disease and to controls. In patients with sarcoidosis TL1A was strongly more expressed in the lung than the blood, i.e., at the site of the involved organ. Additionally, zymography assays showed that TL1A is able to increase the production of matrix metalloproteinase 9 by sarcoid alveolar macrophages characterized, in patients with the active form of the disease, by reduced mRNA levels of the tissue inhibitor of metalloproteinase (TIMP)-1.

Conclusions

These data suggest that TL1A/DR3 interactions are part of the extended and complex immune-inflammatory network that characterizes sarcoidosis during its active phase and may contribute to the pathogenesis and to the progression of the disease.

Alveolar macrophage-T cell interactions during Th1-type sarcoid inflammation

Sarcoidosis is an immunomediated, multisystem disorder of unknown cause(s) characterized by a heightened Th1 immune response that leads to an uncontrolled granuloma formation at sites of disease activity. The past few years have seen outstanding advances in the understanding of immunological and molecular events involved in the pathogenesis of this disease. The idea is that several cytokines and chemokines, which are secreted at sites of disease activity, participate in granuloma formation. This paper describes recent data that have clarified some of the events that govern the development of the hypersensitivity reaction during sarcoidosis. In particular, we will review recent evidence indicating that a complex relationship exists between the macrophage/lymphocyte cellular axis and the tissue networks of cytokines.

Regulation of alveolar macrophage-T cell interactions during Th1-type sarcoid inflammatory process

The accessory function of antigen-presenting cells depends on the presence of a number of costimulatory molecules, including members of the B7 family (CD80 and CD86) and the CD5 coligand CD72. The aim of this study was to evaluate the regulation of T cell-antigen-presenting cell costimulatory pathways in the lung of patients with a typical Th1-type reaction, i.e., sarcoidosis. Although normal alveolar macrophages (AMs) did not bear or bore low levels of costimulatory molecules, AMs from sarcoid patients with CD4 T-cell alveolitis upmodulated CD80, CD86, and CD72 and expressed high levels of interleukin (IL)-15; lymphocytes accounting for T-cell alveolitis expressed Th1-type cytokines [interferon (IFN)-gamma and/or IL-2] and bore high levels of CD5 and CD28 but not of CD152 molecules. In vitro stimulation of AMs with Th1-related cytokines (IL-15 and IFN-gamma) upregulated the expression of CD80 and CD86 molecules. However, stimulation with IL-15 induced the expression of Th1-type cytokines (IFN-gamma) and CD28 on sarcoid T cells, suggesting a role for this macrophage-derived cytokine in the activation of the sarcoid T-cell pool. The hypothesis that CD80 and CD86 molecules regulate the sarcoid T-cell response was confirmed by the evidence that AMs induced a strong proliferation of T cells that was inhibited by pretreatment with CD80 and CD86 monoclonal antibodies. To account for these data, it is proposed that locally released cytokines provide AMs with accessory properties that contribute to the development of sarcoid T-cell alveolitis.

Overexpression of alveolar macrophage gelatinase B (MMP-9) in patients with idiopathic pulmonary fibrosis: effects of steroid and immunosuppressive treatment

Alveolar macrophages (AM) express gelatinase B, a member of the matrix metalloproteinase family involved in the degradation and remodeling of extracellular matrix components. We evaluated the expression of gelatinase B in the course of idiopathic pulmonary fibrosis (IPF) by studying alveolar macrophages in culture AM and bronchoalveolar lavage fluid from 12 untreated patients with IPF, 11 patients with IPF under treatment with steroid and immunosuppressive agents, and 10 control subjects. By using zymography and quantitative image analysis, latent gelatinase B, as well an 88-kD active form, were investigated in culture medium (24 h) of AMs and were found to be significantly increased (P < 0.01) in untreated patients exhibiting severe IPF when compared with control subjects (4.1 +/- 1.7 versus 0.3 +/- 0.2 10(5) arbitrary units [AU]/10(4) AM for the 92-kD form). Concomitant studies of gelatinase B levels associated with cultured AM extracts or freshly harvested AM showed similar results, both at the mRNA and protein levels, respectively. Immunocytochemical studies on freshly harvested AM demonstrated that the enzyme was located mainly at the cell, suggesting some involvement of gelatinase B in AM migration. In contrast, gelatinase B activity secreted by AM tended to be normal in patients with IPF under steroid and immunosuppressive treatment. Simultaneously, level of the gelatinase B activity in epithelial lining fluid was increased in untreated IPF patients, whereas it was normal in treated patients. These results suggest that AM of patients with IPF are primed for gelatinase B expression and that steroid and immunosuppressive treatment induces negative modulation of the gelatinase B overexpression. We conclude that gelatinase B may play a role in lung remodeling in IPF.

Involvement of the IP-10 Chemokine in Sarcoid Granulomatous Reactions

The accumulation of T cells and monocytes at sites of ongoing inflammation represents the earliest step in the series of events that lead to granuloma formation in sarcoidosis. In this study, we evaluated the pulmonary production of IFN-inducible protein 10 (IP-10), a CXC chemokine that stimulates the directional migration of activated T cells. Striking levels of IP-10 were demonstrated in the bronchoalveolar lavage (BAL) fluid of 24 patients with pulmonary sarcoidosis and lymphocytic alveolitis, as compared with patients with inactive disease or control subjects. A positive correlation was demonstrated between IP-10 levels and the number of sarcoid CD45R0+/CD4+ cells in the BAL. Immunochemistry, performed with an anti-human IP-10 polyclonal Ab in lymph nodes displaying prominent sarcoid granulomas, showed that cells bearing IP-10 were mainly epithelioid cells and CD68+ macrophages located inside granulomatous areas. Macrophages recovered from the BAL of sarcoid patients stained positive for IP-10 protein. Furthermore, alveolar macrophages isolated from sarcoid patients with T cell alveolitis and cultured for 24 h in presence of IFN-γ secreted definite levels of IP-10 capable of inducing T cell chemiotaxis. Interestingly, alveolar lymphocytes recovered from patients with active sarcoidosis were CD4+ T cells expressing Th1 cytokines (IL-2 and IFN-γ) and high levels of CXCR3. Taken together, these data suggest the potential role of IP-10 in regulating the migration and activation of T cells toward sites of sarcoid inflammatory process and the consequent granuloma formation.

Cells and molecules involved in the development of sarcoid granuloma

Although the etiology of sarcoidosis is still unknown, characteristic morphologic aspects and immunohistological patterns of sarcoid granulomatous lesions suggest that they are the consequence of an exaggerated immunological response against an undefined antigen which persists at different sites of disease involvement. This article reviews the newly emerging hypothesis regarding the molecular bases which drive the development of sarcoid granulomas. The accumulation of Th1 cells represents the pivotal step along the series of events that lead to the formation of granuloma; furthermore, a set of biological mediators of the immune response define immune regulatory networks that may contribute to tissue damage. It is also thought that shifts of the Th1/Th2 networks and alterations in the complex networks between immunocompetent cells and mesenchymal cells may set the stage for the remodeling of tissues surrounding granulomatous lesions.

Immunohistochemical study of metalloproteinases and their tissue inhibitors in the lungs of patients with diffuse alveolar damage and idiopathic pulmonary fibrosis

Immunohistochemical and confocal microscopic studies of the localization of matrix metalloproteinases (MMPs), their tissue inhibitors (TIMPs), and type IV collagen were made in lung tissues from patients with normal pulmonary histology (n = 3), diffuse alveolar damage (n = 14), and idiopathic pulmonary fibrosis (n = 12). Pretreatment with pepsin revealed otherwise undetectable MMP- and TIMP-immunoreactive sites. In normal lung, MMP-2, MMP-9, TIMP-1, and TIMP-2 were localized in ciliated cells, endothelial cells, pneumocytes, macrophages, and smooth muscle cells; fibroblasts showed a strong reaction only for MMP-2. Only TIMP-2 showed co-localization with type IV collagen. Myofibroblasts and epithelial cells expressed increased reactivity for MMPs and TIMPs in both disorders. The reactivities for MMPs and TIMPs were stronger in diffuse alveolar damage. MMP-2 showed focal co-localization in capillary endothelial and disrupted epithelial basement membranes, suggesting activation of collagenolysis. A protective effect against this lysis was suggested by the extensive co-localization of TIMP-2 with type IV collagen and fibrillar collagens. Alveolar buds showed increased reactivity for MMPs and TIMPs in their lining epithelial cells, myofibroblasts, and their basement membranes; however, their matrices were mostly unreactive. These findings emphasize the complexity of the roles of MMPs and TIMPs in collagen turnover in diffuse alvcolar damage and idiopathic pulmonary fibrosis.

Phenotypic markers of alveolar macrophage maturation in pulmonary sarcoidosis

The expression of maturation-associated antigens on alveolar macrophages (AMs) was studied in bronchoalveolar fluid of 30 patients with sarcoidosis and 11 control subjects. The percent of AMs expressing CD14 or CD11b (common for blood monocytes) was significantly increased in patients with active sarcoidosis compared to those with inactive disease, and control subjects. On the other hand, the mean expression of antigens characteristic for mature macrophages showed no significant difference (25F9), or was even increased in patients with sarcoidosis (CD71, KiM8). Since CD14 and CD11b molecules were also frequently expressed on large phagocytes morphologically similar to mature macrophages, and recent studies showed modulation of these glycoproteins by the activation of myeloid cells, our data indicate that the majority of AMs recovered by bronchoalveolar lavage in sarcoidosis are mature, activated cells.

Expression of alveolar macrophage adhesion molecules in pulmonary sarcoidosis

Beta-2-integrins belong to a family of leukocyte surface glycoproteins that are essential for immune functions of bronchoalveolar cells. The expression of three alpha chains designed as CD11a, CD11b, CD11c, a common beta chain CD18, and of a ligand for several integrins CD54 (ICAM-1) was studied on alveolar macrophages of patients with active and inactive sarcoidosis and in control subjects. The percentage of macrophages expressing CD11b (CR3) was significantly increased in patients with active sarcoidosis compared with patients who had inactive disease and control subjects. The adhesion molecule CD54 (ICAM-1) was detected on a higher percentage of alveolar macrophages in patients with active rather than inactive sarcoidosis and in control subjects. Since integrin-mediated adhesion seems to be important in macrophage-lymphocyte interactions during the immune response, higher expression of both CD11b and CD54 on sarcoid alveolar macrophages may be related to several immune abnormalities reported in pulmonary sarcoidosis.

Natural human monocyte gelatinase and its inhibitor

Gelatinases produced by stimulated peripheral blood monocytes were detected by substrate zymography and were compared with those derived from tumor cells. Stimulated monocytes were found to produce an 85 kDa gelatinase which co-migrated upon electrophoretic separation and cross-reacted in immunoprecipitation experiments with a phorbol ester inducible metalloprotease from human tumor cells. The intact natural gelatinase (85 kDa), a high molecular weight and complexed gelatinase as well as a proteolytic fragment (25 kDa) were purified by substrate- and antibody-affinity chromatography techniques. Aminoterminal sequence analysis showed that natural monocyte gelatinase occurs as a truncated form of tumor cell gelatinase/type IV collagenase. Furthermore, peripheral blood monocytes were found to also produce a tissue inhibitor of metalloproteases (TIMP). TIMP was co-purified with gelatinase on gelatin sepharose and identified by microsequencing. The balanced and regulated production of gelatinase and TIMP might be important in monocyte migration and tissue remodeling.

Immune responses in the lung: basic principles

The basic elements which regulate immunomodulation at the lung level and the constituents of in situ pulmonary host defense mechanisms that recognize, destroy, and remove potentially harmful inhaled antigenic materials are discussed. The relevance of these processes in term of pathogenesis of some lung disorders is briefly exemplified.

Cytotoxic events taking place in the lung of patients with HIV-1 infection. Evidence of an intrinsic defect of the major histocompatibility complex-unrestricted killing partially restored by the incubation with rIL-2

To characterize the cytotoxic events taking place in the lung of patients with HIV-1 infection, we studied the cells recovered from the bronchoalveolar lavage (BAL) of nine patients with AIDS, seven patients with AIDS-related complex, and two patients with lymphadenopathy. Phenotypic analysis was coupled to a series of functional evaluations of nonspecific cytotoxic abilities performed on lung effectors, including their property to bind K-562 targets, to release natural killer cytotoxic factor (NKCF), and to become cytotoxic following in vitro activation with rIL-2. Our results demonstrated that lung cells bearing the NK-related CD16, CD56, and CD57 antigens were quantitatively increased, irrespective of the disease stage. The majority of the cells also coexpressed the CD3 molecule and the alpha/beta T cell receptor (TCR), notably the phenotype characterizing MHC-unrestricted cytotoxic T cells. From a functional point of view, a severe impairment of the spontaneous cytotoxic ability was demonstrated in most patients. Evaluation at the single cell level showed a normal percentage of the effector/target conjugates formed by HIV-1 lymphocytes. The release of NKCF was undetectable in patients with AIDS even following lectin stimulation, whereas BAL cells from patients with earlier infection produced and/or could be triggered to release discrete amounts of NKCF by incubation with PHA. Studies designed to activate lung cytotoxic cells with rIL-2 showed that in most patients the stimulation of effector cells with rIL-2 enhanced the spontaneous killing and elicited a lymphokine-activated killer (LAK) phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS)