Expression Of Integrin Adhesion Molecules Research Articles

Extracorporeal photopheresis as a non-specific immune therapy of autoimmune diseases and skin T-cell lymphoma (a review of the literature and own studies)

Aim:To present well-known and disputable mechanisms of the effects of extracorporeal photopheresis (ECP) in heterogeneous clinical conditions, as well as to demonstrate its advantages over conventional hormonal, immunosuppressive and cytostatic treatments, with a recommendation to widely implement it into practical management of autoimmune disease and cutaneous T-cell lymphomas (CTCLs).Key points:Despite convincing evidence of the ECP efficacy in the treatment of T-cell mediated disorders, a unifying concept of its mechanism has not been established so far. In this review, we attempted to determine the value of multiple, sometimes contradictory and equivocal points of view to immunobiochemical processes underlying the restoration of mechanism of immune tolerance in some autoimmune diseases and CTCLs. We focused our attention on our own clinical and immunological data obtained during a 20-years' experience with the use of ECP in clinical departments of MONIKI (Russia). Based on this, we have shown that ECP is more effective in autoimmune diseases than conventional treatment approaches with hormones, immunosuppressants and cytostatics. Unlike them, ECP is selectively targeted to auto-aggressive T-cells without induction of systemic immunosuppression. The leading role is played by the transformation of activated (immunogenic) myeloid dendrite cells (DC) into tolerogenic cell associated with their synthesis of inhibitor cytokines. The interplay of the cytokines with an antigen results in polarization of CD4+ Т lymphocytes via the Th2 pathway with restoration of the Th1/Th2 balance and their cytokine production. ECP triggers regulatory anti-clonotypic effector memory cells at the end stage of CD3+/CD8+/CD27-/CD28-/CD62L+ differentiation, that provide and maintain the peripheral immune tolerance, by deletion of the clone of auto-reactive cytotoxic lymphocytes and inducing their apoptosis. In autoimmune disorders, ECP results in reduction of the expression of integrin adhesion molecules on auto-reactive cell membranes with subsequent loss of their ability to migrate through the endothelium to their target cells. In its turn, it leads to decreasing immunoinflammatory response in the lesion. Both clinical and experimental data indicate that the mechanism of ECP action against CTCLs is characterized by activation of tumor cell apoptosis, unblocking of co-activation receptors on the antigen-presenting DC providing the functioning of the second signaling pathway for T lymphocyte activation. This results in proliferation of anti-tumor effector cells pool, production of DC activating cytokines that participate in the CD4+ polarization via Th1 pathway. In addition, this review considers the mechanism of the immunomodulating effect of ECP in the context of its influence at the levels of transcription and translation of proteins contributing to the pathophysiology of the disorders, based on molecular immunogenetic studies. Thus, ECP is able to induce antigen-specific immunological tolerance through the transformation of antigen-presenting cells, modulation of cytokine profile, adhesion and activation molecules, as well as through formatting of the regulatory T cells (Tregs).Conclusion:Undoubtedly, the immunobiological ECP technique has significant advantages over well-known conventional hormonal, immunosuppressive, and cytostatic therapies of autoimmune diseases and CTCLs.

Evaluation of lipopolysaccharide-induced activation of equine neutrophils.

To evaluate lipopolysaccharide (LPS)-induced activation of equine neutrophils in blood. Blood samples from 5 healthy adult Thoroughbreds. Neutrophil integrin (CD11/CD18) expression, size variation, degranulation, and deformability were measured with and without incubation with LPS. Time and concentration studies were done. The mechanism of endotoxin-induced neutrophil activation was investigated by inactivating complement or preincubating neutrophils with inhibitors of tumor necrosis factor-alpha (TNF-alpha) synthesis, prostaglandin-leukotriene synthesis, or platelet-activating factor. Incubation of equine neutrophils with LPS increased cell surface expression of CD11/CD18, decreased neutrophil deformability, increased and decreased neutrophil size, and induced neutrophil degranulation. The LPS-induced neutrophil activation was attenuated by addition of inhibitors of TNF-alpha and prostaglandin-leukotriene synthesis. Equine neutrophils are readily activated in vitro by LPS, resulting in increased expression of integrin adhesion molecules, decreased deformability, variation in neutrophil size, and degranulation. The tests used to detect activated neutrophils in this study may be useful in detecting in vivo neutrophil activation in horses with sepsis and endotoxemia.

Tumor Cell Interactions With the Microvasculature: A Rate-Limiting Step in Metastasis

Blood vessels facilitate the widespread dissemination of cancer cells in metastasis. Interactions between circulating intravascular cancer cells and the microvasculature involve mechanical contact and transient attachment, mediated by endothelial surface adhesion molecules and their ligands on the neoplastic cells. Initial interactions trigger a sequence of activation pathways that involve cytokines, growth factors, bioactive lipids, and reactive oxygen species produced by the cancer cell or the endothelium. These activation steps elicit the expression of integrin adhesion molecules in cancer cells and the endothelium, matrix metalloproteinases, and chemotactic factors that promote firm attachment of tumor cells to the vessel wall and transvascular penetration. On the other hand, induction of endothelial free radicals can be cytotoxic to cancer cells. Collectively, the sum of these interactions act as a rate-regulating step in the metastatic process.

Interactions between cancer cells and the endothelium in metastasis.

The haematogenous phase of cancer metastasis facilitates the transport of metastatic cells within the blood and incorporates a sequence of interactions between circulating intravascular cancer cells and the endothelium of blood vessels at the sites of tumour cell arrest. Initial interactions involve mechanical contact and transient adhesion, mediated by endothelial selectins and their ligands on the neoplastic cells. This contact initiates a sequence of activation pathways that involves cytokines, growth factors, bioactive lipids, and reactive oxygen species produced by either the cancer cell or the endothelium. These molecules elicit expression of integrin adhesion molecules in cancer cells and the endothelium, matrix metalloproteinases, and chemotactic factors that promote the attachment of tumour cells to the vessel wall and/or transvascular penetration. Induction of endothelial free radicals can be cytotoxic to cancer cells. Collectively, the sum of these interactions constitutes an interdependent relationship, the outcome of which determines the fate of the metastatic process.

Resting microglial cells in vitro: analysis of morphology and adhesion molecule expression in organotypic hippocampal slice cultures.

Neurons in organotypic hippocampal slice cultures (OHSCs) are known to preserve morphological and physiological features of the in vivo situation; however, little is known about the properties of microglial cells under these in vitro conditions. In this study, we addressed the question whether microglial cells in OHSCs are initially activated following explantation but return to a resting state during in vitro cultivation. Thus, we analyzed a) microglial cell morphology, b) microglial cell distribution, and c) expression of integrin adhesion molecules as putative markers of microglial activation. Hippocampal slices fixed immediately following explantation showed only resting microglial cells, mainly located in the paraventricular regions. After 3 days in vitro (div) OHSC surfaces were covered by activated microglia, whereas intermediate layers contained fewer microglial cells, giving the slices a sandwich-like appearance with the intact hippocampal formation being surrounded by glial tissue. After 3 div, microglial cells in intermediate layers of OHSCs showed activated morphology with ovaloid cytoplasm and no or merely few cytoplasmic processes; after 6 div, however, an increasing degree of ramification could be observed. After 9 div, microglia in intermediate layers had almost regained the morphological appearance of resting cells with filigrane cytoplasmic processes extended in all directions. The integrin adhesion molecules LFA-1 (alpha and beta chains) and VLA-4 were expressed on most microglial cells with activated morphology, as verified by co-localization with double immunofluorescence labeling for LFA-1 or VLA-4 and Griffonia simplicifolia isolectin B4 (GFS-B4). In contrast, only low levels of integrin adhesion molecule expression were also found on reactive astrocytes along slice surfaces. However, LFA-1 or VLA-4 were never found on ramified microglial cells, and double immunofluorescence labeling of LFA-1 or VLA-4 with ramified GFS-B4+ microglia never occurred. We conclude that a) originally resting microglial cells activated in an early phase of in vitro culture but regain a resting status after at least 6 div; and b) integrin adhesion molecules LFA1 and VLA-4 are potential markers of microglial activation, as they were found on activated but never on resting microglial cells. This enables further investigations on immunological and electrophysiological features of resting and activated microglial cells under in vitro conditions.

Expression of integrin adhesion molecules in normal ovary and epithelial ovarian tumors.

The metastatic potential of a solid tumor is dependent upon its ability to interact with the extracellular matrix. The integrin superfamily is a group of proteins that are fundamental in such interactions and play a major role in cell-cell and cell-matrix adhesion. Localization of the integrin proteins was performed in normal ovary, primary epithelial ovarian tumors and metastatic tumor cells in ascitic samples. Expression of alpha1, alpha3, alpha6 and beta4 was observed on normal ovarian epithelium with variable expression of alpha5. Loss of alpha1 expression by malignant cells in the primary tumors was noted. beta4, a component of the laminin receptor which was strongly expressed by both normal ovary and solid tumor, was absent from the ascitic tumor cells in the majority of cases. There was an associated loss of alpha6 expression, indicating a deficiency of hemidesmosomes in the ascitic tumor cells. This alteration of integrin expression by metastatic malignant epithelial ovarian tumor cells may therefore represent one important mechanism by which metastatic disease occurs.

Expression of integrin adhesion molecules in endometrium and endometriosis.

To compare the expression of cell adhesion molecules by endometrium and endometriosis. A comparative study of integrin expression, determined immunohistochemically, in eutopic and ectopic endometrium biopsied synchronously from patients with endometriosis diagnosed at laparoscopy or laparotomy. University Departments of Obstetrics and Gynaecology, and Pathology, Southampton; Department of Obstetrics and Gynaecology, Newcastle upon Tyne. Eighteen paired samples of endometria and endometriosis. A wide distribution of collagen-laminin receptor proteins was demonstrated. alpha 1 integrin expression was limited to secretory endometrium. beta 3 expression was only demonstrated on proliferative endometrium. Expressions of the integrin proteins differed between the various elements of the endometrium. Cyclical changes in integrin expression also were demonstrated. No difference in cell adhesion molecule expression was seen when comparing endometrial and endometriosis samples.

The binding of acute myeloid leukemia blast cells to human endothelium.

AML blast cell adhesion to endothelium is in all likelihood a prerequisite for blast cell migration across the vascular wall in the periphery and the subsequent establishment of leukemic extravascular disease. A general feature of malignant cells is their acquisition of altered or aberrant adhesive capabilities which appear to be associated with their ability to metastasize. Aberrant expression of integrin adhesion molecules and of membrane oligosaccharide structures is found in AML and various solid tumors. With respect to AML, these alterations in adhesive phenotype may confer a proliferative advantage on the malignant cells in the marrow, may facilitate egress from the bone marrow into the peripheral vasculature and may enable AML blast cells to traverse the vessel wall and so establish extravascular disease. Oncogenes may be directly involved in the acquisition of such aberrant adhesive phenotypes. Neutrophil extravasation is described as a model for leukocyte migration across the vessel wall and brief summaries of experimental work involving aspects of AML blast cell and normal CD34+ bone marrow cell adhesion to endothelium in vitro are described.

Diminished expression of integrin adhesion molecules on human colonic epithelial cells during the benign to malign tumour transformation.

Integrins are transmembrane molecules that mediate cell-cell and cell-substratum adhesion. Because alterations in the adhesive properties of tumour cells are thought to influence tumour cell invasion, the expression of integrin alpha and beta chains in 19 human colorectal carcinomas, eight adenomas, and eight normal colon tissues was examined immunohistochemically using an indirect immunofluorescent technique. Normal colonic epithelial cells were found to express the integrin alpha 3, alpha 5, alpha 6, beta 1, and beta 4 chains, whereas the alpha 2 chain was expressed only on epithelial cells lining the base of the crypts and was absent from cells lining the mouth of the crypts or the surface epithelium. No epithelial staining of the alpha 1, alpha 4, beta 2, and beta 3 chains was observed. A progressive reduction of all normally expressed alpha and beta chains was associated with increasing neoplastic transformation. The expression of the alpha 3 and alpha 5 chains was already noticeably reduced in adenomas, and was completely absent in most colonic carcinomas. In contrast, alpha 6, beta 1, and beta 4 expression was maintained in adenomas, whereas the transformation from benign to malignant neoplasms associated with infiltrative growth was characterised by diminished or lost expression of alpha 6, beta 1, and beta 4 chains. Thus, the decreased expression of integrins in human colon carcinomas may contribute to the altered adhesion and migration properties of these tumour cells.