Extracellular matrix proteins, regulators of T-cell functions in healthy and diseased individuals

Intrathymic Cell Migration: Implications in Thymocyte Development and T Lymphocyte Repertoire Formation

During the development of T cells in the thymus, differentiating thymocytes move through specific thymic compartments and interact with the cortical and medullary microenvironments of the thymic lobules. This migration is primarily controlled by adhesion molecules, such as extracellular matrix ligands and receptors, and soluble factors like chemokines that are important for thymocyte differentiation. The migration events driven by these molecules include the entry of lymphoid progenitors from the bone marrow, movement within the thymus, and the exit of mature thymocytes. Notably, the migration of developing T cells can also impact the positive and negative selection processes, which are crucial for preventing the development of self-reactive T cells. This chapter will focus on the key molecules involved in thymocyte migration and how their expression patterns may affect T cell development and the formation of T cell repertoires.

Using adjusted local assortativity with Molecular Pixelation unveils colocalization of membrane proteins with immunological significance

Advances in spatial proteomics and protein colocalization are a driving force in the understanding of cellular mechanisms and their influence on biological processes. New methods in the field of spatial proteomics call for the development of algorithms and open up new avenues of research. The newly introduced Molecular Pixelation (MPX) provides spatial information on surface proteins and their relationship with each other in single cells. This allows for in silico representation of neighborhoods of membrane proteins as graphs. In order to analyze this new data modality, we adapted local assortativity in networks of MPX single-cell graphs and created a method that is able to capture detailed information on the spatial relationships of proteins. The introduced method can evaluate the pairwise colocalization of proteins and access higher-order similarity to investigate the colocalization of multiple proteins at the same time. We evaluated the method using publicly available MPX datasets where T cells were treated with a chemokine to study uropod formation. We demonstrate that adjusted local assortativity detects the effects of the stimuli at both single- and multiple-marker levels, which enhances our understanding of the uropod formation. We also applied our method to treating cancerous B-cell lines using a therapeutic antibody. With the adjusted local assortativity, we recapitulated the effect of rituximab on the polarity of CD20. Our computational method together with MPX improves our understanding of not only the formation of cell polarity and protein colocalization under stimuli but also advancing the overall insight into immune reaction and reorganization of cell surface proteins, which in turn allows the design of novel therapies. We foresee its applicability to other types of biological spatial data when represented as undirected graphs.

Upregulation of cathepsin S in psoriatic keratinocytes

Cathepsin S (CATS) is a cysteine protease, well known for its role in MHC class II-mediated antigen presentation and extracellular matrix degradation. Disturbance of the expression or metabolism of this protease is a concomitant feature of several diseases. Given this importance we studied the localization and regulation of CATS expression in normal and pathological human/mouse skin. In normal human skin CATS-immunostaining is mainly present in the dermis and is localized in macrophages, Langerhans, T- and endothelial cells, but absent in keratinocytes. In all analyzed pathological skin biopsies, i.e. atopic dermatitis, actinic keratosis and psoriasis, CATS staining is strongly increased in the dermis. But only in psoriasis, CATS-immunostaining is also detectable in keratinocytes. We show that cocultivation with T-cells as well as treatment with cytokines can trigger expression and secretion of CATS, which is involved in MHC II processing in keratinocytes. Our data provide first evidence that CATS expression (i) is selectively induced in psoriatic keratinocytes, (ii) is triggered by T-cells and (iii) might be involved in keratinocytic MHC class II expression, the processing of the MHC class II-associated invariant chain and remodeling of the extracellular matrix. This paper expands our knowledge on the important role of keratinocytes in dermatological disease.

The influence of extracellular matrix proteins on T-cell proliferation and apoptosis in women with endometriosis or uterine leiomyoma

PROBLEM

Interactions between the extracellular matrix (ECM) and peripheral blood T cells in women with endometriosis and leiomyoma are hardly unknown. We have investigated the influence of two major ECM components, collagen IV (C-IV) and fibronectin (Fn), on T-cell proliferation and apoptosis in women with endometriosis and uterine leiomyoma. beta1 integrin expression, responsible for interactions with ECM proteins, was also studied.

METHOD OF STUDY

Peripheral blood lymphocytes were obtained from 53 women (17 with uterine leiomyomas, 18 with endometriosis, and 18 from healthy donors). T cells were exposed to ECM proteins co-immobilized with monoclonal antibody anti-CD3 for 72 hr. Apoptosis and S phase of the cell cycle of the T cells were studied by DNA analysis using flow cytometry. The proliferation of T cells was evaluated by MTT assay. The percentage of CD3+ cells expressing CD29 (beta1 integrin chain) was evaluated by double-color flow cytometry. Results were analyzed statistically using the Mann-Whitney test.

RESULTS AND CONCLUSIONS

(1) A general increase in the percentage of T cells in S phase could be seen in women with endometriosis and uterine leiomyoma in all culture conditions what may suggest general activation of T cells. (2) A significant increase in the percentage of cells in S phase was shown only in the case of T cells exposed to anti-CD3 + C-IV in both women with uterine leiomyoma and endometriosis. (3) However, no apoptotic cells were observed. (4) T cells from patients with uterine leiomyoma exhibited significantly increased level of proliferation after culture with anti-CD3 + C-IV. (5) More T cells expressed beta1 integrin in women with endometriosis or uterine leiomyoma than in healthy donors. Our data may suggest that increased beta1 integrin expression may enhance T-cell-ECM interactions, which may be responsible for the increased proliferation of T cells but not for apoptosis. Therefore, it is possible that interactions of T cells with ECM proteins, especially with C-IV, may contribute to the pathogenesis of endometriosis and uterine leiomyoma.

Extracellular Matrix Protein-dependent Apoptosis of T Cells in Women with a History of Recurrent Spontaneous Abortion

PROBLEM

The purpose of the study was to determine the role of T-cell apoptosis in extracellular matrix (ECM) environment in pregnancy maintenance in women with a history of recurrent spontaneous abortion (RSA).

METHOD OF STUDY

Thirty-nine non-pregnant women with the history of RSA (anatomic, genetic, endocrine and microbiologic causes were excluded) and 22 healthy women with the previous successful pregnancy outcome were studied. In addition, 21 women with the history of RSA were also studied at the beginning of their next pregnancy. We studied apoptosis of peripheral blood T cells after culture with monoclonal antibody (mAb) OKT-3 alone or with mAb OKT-3 following ECM proteins: collagen IV (C-IV) or fibronectin (Fn). We used Cell Death Detection ELISA for studying cell death in cell population. In addition, apoptotic peripheral blood T cells were identified by annexin V-PE staining protocol using flow cytometry. CD29+ and CD95+ T-cell surface receptors were also analyzed by flow cytometry.

RESULTS

The significantly higher values of enrichment factor: mU of the sample (dying/dead cells) per mU of the corresponding control (viable cells) were observed after peripheral blood T-cell culture with C-IV (P = 0.0002) or Fn (P = 0.004) in samples of non-pregnant women with the history of RSA when compared with control women. The significantly higher values of enrichment factor were observed after peripheral blood T-cell culture with C-IV in samples of pregnant women with the history of RSA with successful pregnancy outcome when compared with pregnant women with the history of RSA with failed pregnancy outcome (P = 0.01). However, the percentage of apoptotic T cells stained by annexin V was significantly lower in non-pregnant RSA women compared with control (P = 0.0001). CD95 expression was significantly lower in non-pregnant RSA women compared with control (P = 0.01).

CONCLUSIONS

Apoptosis of T cells might be an interesting possible explanation of successful pregnancy outcome in women with the history of RSA.

Enhanced T cells interactions with extracellular matrix proteins in infertile women with endometriosis

Essential features of endometriosis involve interactions with extracellular matrix (ECM). Recent data emphasize the important role of ECM proteins in the regulation of T cell function. The aim of this study was to determine activated T cell adhesion to ECM proteins in infertile women with endometriosis. Nine women with endometriosis diagnosed by laparoscopy according to the Revised American Fertility Society classification and ten normal healthy women with a previous successful pregnancy outcome were studied. We investigated phorbol acetate myristate (PMA) or phytohemaglutinin (PHA) activated peripheral blood T cell adhesion to the following proteins of ECM: collagen IV (C-IV), elastin (E) and fibronectin (Fn). In addition, CD4, CD8, CD29, CD45RO expression on peripheral CD3(+) T cells were studied using flow cytometry. We determine that PHA-activated T cell adhesion to C-IV and Fn are significantly higher in infertile women with endometriosis when compared to normal healthy women (P<0.05). No significant differences were noted in T cell's surface antigens expression between study groups. Our data suggest the existence of disturbed T cell-ECM interactions in infertile women with endometriosis. Further studies are needed to determine the role of these abnormalities in the pathogenesis of endometriosis.

T-cell-mediated immunity in thyroid-associated ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is considered to be an autoimmune inflammatory disorder of the extraocular muscles and the orbital fat/connective tissue. Recent studies analyzing T cells infiltrating retrobulbar tissues generated important insights into the immunopathogenesis of TAO. The present review focuses on advances in our understanding of mechanisms responsible for the autoimmune inflammation in TAO, especially T cell migration to the inflammatory site, T cell activation by autoantigens and costimulatory signals and their cytokine profile. The elucidation of these processes might lead to the development of novel therapeutic strategies directed against autoreactive T cells.

Immune abnormalities in aneurysmal subarachnoid haemorrhage patients: relation to delayed cerebral vasospasm

Peripheral blood CD3+, CD19+, CD4+, CD8+ and CD45RO+ mononuclear cell subsets, T-cell proliferative responses to combinations of coimmobilized OKT3 antibody and an ECM protein (collagen I, collagen IV, fibronectin or elastin), and T-cell adhesion to collagen IV, fibronectin and elastin were studied in patients with aneurysmal subarachnoid haemorrhage. No significant difference was found in the major lymphocyte subsets between subarachnoid haemorrhage patients receiving no dexamethasone for brain oedema treatment and healthy blood donors. Compared with the latter, both the dexamethasone-untreated and -treated subarachnoid haemorrhage patients showed decreased relative proliferative responses of circulating T cells to OKT3 combinations with collagen IV and fibronectin, and an increased PHA-activated T-cell adhesion to elastin. CD45RO+, CD4+ and CD19+ peripheral blood cell subsets, CD4+/CD8+ cell ratio, PHA-activated T-cell adhesion to fibronectin and collagen IV, and OKT3-triggered T-cell costimulatory responses to elastin, collagen IV and fibronectin were significantly higher in subarachnoid haemorrhage patients presenting with delayed cerebral vasospasm (DCV) than in their DCV-free counterparts. The DCV-related differences in circulating lymphocyte subsets showed no apparent relationship to the glucocorticoid treatment, whereas the differences in the other indices were confined to the dexamethasone-untreated subarachnoid haemorrhage patients. The above results suggest that the CD4+/CD8+ ratio and T cell-ECM interactions play a role in the emergence of subarachnoid haemorrhage/DCV and may represent potential targets for subarachnoid haemorrhage therapy.

Autoantibodies reactive with extracellular matrix proteins in patients with thyroid-associated ophthalmopathy

Autoantibodies reacting with extracellular matrix proteins have been extensively studied in various autoimmune connective tissue diseases. Because of the possibility that such antibodies may play a role in orbital connective tissue inflammation in thyroid-associated ophthalmopathy (TAO), we studied the humoral immune response against specific extracellular matrix (ECM) proteins, namely: collagen types I, III, IV, V (CI, CIII, CIV, CV), fibronectin (FN), and laminin (LM). Anti-ECM antibodies of immunoglobulin G (IgG), IgA, and IgM classes were determined by enzyme linked immunosorbent assay (ELISA). Overall, sera from 50% of patients with TAO contained antibodies reactive against one or more ECM proteins, compared to 27% with Graves' disease (GD) without evident eye involvement, 28% with Hashimoto's thyroiditis (HT), and 9% of normal subjects. Serum anti-CI, anti-CIII, anti-CV and anti-LM levels were significantly (p<0.05) higher in patients with TAO than in normals. Anti-CI, anti-CV and anti-LM reactivity was antigen-specific in most TAO sera, while anti-CIII antibodies cross-reacted with other antigens. Anti-collagen antibodies were mainly of the IgG class. To determine the structural epitopes of these proteins, we performed immunoblotting studies on cyanogenbromide (CNBr)-derived peptides of CI and CV. While sera from 9 of 10 patients with TAO reacted with CI peptides, the response was polyclonal and uniform in all patients. However, only 2 of 10 TAO sera reacted with CV peptides. In conclusion, our study suggests that a variety of ECM proteins (CI, CV, LM) may be secondary autoantigens that are recognized by antibodies in TAO. While these antibodies appear to react with epitopes expressed on both native and denatured proteins, and may therefore have the potential to bind to ECM in vivo, their pathogenic role in TAO remains unknown.

T cell interactions with extracellular matrix proteins in patients with thyroid-associated ophthalmopathy

Although thyroid-associated ophthalmopathy (TAO) is now generally accepted as an autoimmune inflammatory disorder of the extraocular muscles and the orbital connective tissue, its aetiopathogenesis remains poorly understood. Recent data indicate that impaired interactions between T cells and extracellular matrix (ECM) proteins may play an important role in development and maintaining of an inflammatory process. We report here results of the study focusing on interactions between T lymphocytes and collagen-I (Coll-I), collagen-IV (Coll-IV), fibronectin (FN), laminin (LM) in patients with TAO. Using a standard peripheral blood mononuclear cells (PBMC) proliferation assay, we observed a markedly enhanced T cell response to Coll-I in patients with active TAO (mean SI=4.5). The proliferatory response to Coll-I was significantly greater (Wilcoxon test; p < 0.001) than in normal subjects (mean SI=1.88), patients with stable TAO (mean SI=2.05) and patients with thyroid autoimmune diseases (AITD) without ophthalmopathy (mean SI=2.49). PBMC stimulation by Coll-I is likely to be antigen-dependent requiring engagement of the T cell receptor with collagen peptides, rather than mediated via integrins. The percentage of circulating CD29+ (beta1 integrin chain) T cells was not increased in patients with active TAO. Additionally in the assay of costimulation of CD3-mediated proliferation, we found that peripheral blood T cells from patients with TAO and AITD were costimulated only by FN. On the other hand a markedly enhanced costimulation of CD3-mediated proliferative responses by Coll-I, Coll-IV, FN and LM were observed in a retrobulbar T cell line. We conclude that abnormalities in T cell interactions with ECM proteins, especially Coll-I may play a role in the pathogenesis of TAO.