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CD44 expression in alopecia areata and androgenetic alopecia

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Abstract

CD44 is a widely distributed cell surface protein thought to be involved in multiple steps of normal immune cell function, including T-cell activation, and in cellular adhesion where it mediates cell attachment to hyaluronate. In normal skin, CD44 is found by immunohistochemical means to be primarily in eccrine coil cells. In this study, we have looked at the expression of CD44 in normal scalp and in two different hair disorders, androgenetic alopecia and alopecia areata. In normal scalp and androgenetic alopecia, CD44 was found in its normal distribution in eccrine coil cells. In scalp of 30 patients with alopecia areata, there was no expression of this glycoprotein. Patients were also assessed pre and post treatment for their alopecia areata, and even though they had no significant hair regrowth, 2 patients regained expression of CD44, indicating a variable expression of this protein in the alopecia areata disease process. The absence of CD44 expression in alopecia areata-affected scalp may give further information regarding the pathogenesis of this disease.

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... Various mechanisms have since been proposed for the IP of the HF, with the most prominent one being a downregulation of MHC Class I expression (7). Hair loss disorders are associated with disruptions and changes in the immune milieu of the HF (8,9), and conversely, immunotherapy has been utilized to promote HF regrowth and regeneration. ...
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Article
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Article
Murine CD44 is a cell surface glycoprotein that is thought to play a role in leukocyte migration. We studied the structure and expression of CD44 on two populations of macrophages: those that reside in the peritoneum of unprimed mice, and those that have been elicited to migrate into the peritoneum by the intraperitoneal injection of agents that cause localized inflammatory responses. Our studies reveal structural variations in both the extracellular and intracellular domains of CD44 expressed by these two macrophage populations. The form of CD44 in elicited macrophages has an apparent molecular mass that is approximately 5 kD greater and more heterogenous than that in resident macrophages. This structural changes is posttranslational, extracellular, and apparently reflects increases in N-linked glycosylation. It is also specific for CD44 and does not occur with several other glycoproteins examined. This novel regulation of glycosylation may play an important role in the ability of CD44 to bind to different substrates, particularly lectin-like ligands. In addition, we demonstrate that CD44 in resident macrophages is divided into two pools, one containing nonphosphorylated, cytoskeletally associated CD44, and one containing phosphorylated, unassociated CD44. In contrast, CD44 on the surface of elicited macrophages does not associate with the cytoskeleton. The attachment of CD44 to the cytoskeleton involves either direct or indirect association with actin. The regulated association of CD44 with the cytoskeleton suggests that it may influence or be influenced by macrophage mobility.
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Summary In this study the number and function of sweat glands on the dorsum of the hand and foot were evaluated using a silastic imprint method. Twenty patients. 11 females and nine males with either alopecia areata. alopecia totalis. or alopecia universalis were included in the study. Patients showed a significant decrease in activated sweat-gland number and function compared to matched controls (P<0.001). There was no significant relationship between the degree of sweat-gland dysfunction and extent of hair loss, concurrent illnesses, or treatment. These findings suggest that eccrine sweat-gland function is compromised in patients with alopecia areata.
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CD44 is the principal cell surface receptor for hyaluronate. In non-inflamed skin, CD44 expression is limited to the cell membrane of eccrine coil cells. The distribution on these cells is assymetric, with intense staining on the dermal side and little staining on the luminal side of the coil cell. In skin containing a pathologic process, either inflammatory or neoplastic, CD44 expression can be widespread on the membranes of keratinocytes and on infiltrating lymphocytes in the vicinity of the process. Diverse roles have been proposed for CD44 and largely involve aspects of cellular adhesion in one setting or another. CD44 may identify a more mobile, proliferating keratinocyte that is responding to local injury. In eccrine coil, the stable presence of CD44 on the non-luminal surface of secretory cells indicates an undefined function for CD44 in the generation of eccrine sweat.
Article
Monoclonal antibodies in the Hermes family recognize a lymphocyte structure that participates in lymphocyte adhesion to endothelium and has been suggested to be the human homolog of the murine Mel-14 lymph node homing receptor. Recently, antibodies against the Hermes antigen, the polymorphic glycoprotein Pgp-1 antigen, and the broadly expressed CDw44 antigen have been shown to recognize the same structure. In this work, cDNA clones encoding the CDw44 antigen were isolated and expressed in COS cells. Two forms were identified: a lymphoid form expressed in hematopoietic cells, and an epithelial form weakly expressed in normal epithelium but highly expressed in carcinomas. The extracellular domain of CDw44 bears homology to cartilage link proteins and a related segment of proteoglycan core protein. However, comparison with the recently identified sequence of the Mel-14 antigen shows that CDw44 and Mel-14 are unrelated.
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CD44 is a broadly distributed cell surface protein thought to mediate cell attachment to extracellular matrix components or specific cell surface ligands. We have created soluble CD44-immunoglobulin fusion proteins and characterized their reactivity with tissue sections and lymph node high endothelial cells in primary culture. The CD44 target on high endothelial cells is sensitive to enzymes that degrade hyaluronate, and binding of soluble CD44 is blocked by low concentrations of hyaluronate or high concentrations of chondroitin 4- and 6-sulfates. A mouse anti-hamster hyaluronate receptor antibody reacts with COS cells expressing hamster CD44 cDNA. In sections of all tissues examined, including lymph nodes and Peyer's patches, predigestion with hyaluronidase eliminated CD44 binding.
Article
Biotinylated hyaluronan (HA) binding complex (HABC) from bovine articular cartilage proteoglycan was used as a histological probe to study the localization of HA in human skin. The distribution of HA was compared with its presumptive cell surface receptor, CD44, using monoclonal antibodies. In epidermis both HA and CD44 were found in the basal and spinous cell layers, but neither was present in the stratum granulosum and stratum corneum. In the keratinizing parts of hair follicles, i.e. in the outer and inner epidermal root sheath, pilosebaceous duct and the actual hair, HA and CD44 were found between the vital but not the terminally differentiated cells. In the sebaceous glands a small amount of HA was found around all cells, whereas CD44 was restricted to the basal cell layer. The secretory acini of the sweat glands stained intensively with anti-CD44 antibodies but only weakly with HABC. In the sweat gland, CD44 was localized on the basal and lateral surfaces of the clear cells, whereas the dark cells and the myoepithelial cells were negative. Both the lower and upper layers of the sweat gland ducts showed a faint but constant staining for CD44 and only minor amounts of HA. While in the keratinizing skin epithelia both HA and its CD44 receptor showed an intense staining with a close co-distribution, in the sweat and sebaceous glands their distribution patterns were not similar. It is suggested that in epithelia with divergent differentiation programs the functions of CD44 and HA may be different.
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The CD44 inhibitor Lutheran [In(Lu)]-related p80 molecule has recently been shown to be identical to the Hermes-1 lymphocyte homing receptor and to the human Pgp-1 molecule. We have determined the effect of addition of CD44 antibodies to in vitro activation assays of PBMC. CD44 antibodies did not induce PBMC proliferation alone, but markedly enhanced PBMC proliferation induced by a mitogenic CD2 antibody pair or by CD3 antibody. CD44 antibody addition had no effect upon PBMC activation induced by PHA or tetanus toxoid. CD44 antibody enhancement of CD2 antibody-induced T cell activation was specific for mature T cells as thymocytes could not be activated in the presence of combinations of CD2 and CD44 antibodies. CD44 antibody enhancement of CD2-mediated T cell triggering occurred if CD44 antibody was placed either on monocytes or on T cells. In experiments with purified monocyte and T cell suspensions, CD44 antibodies A3D8 and A1G3 augmented CD2-mediated T cell activation by three mechanisms. First, CD44 antibody binding to monocytes induced monocyte IL-1 release, second, CD44 antibodies enhanced the adhesion of T cells and monocytes in CD2 antibody-stimulated cultures, and third, CD44 antibodies augmented T cell IL-2 production in response to CD2 antibodies. Thus, ligand binding to CD44 molecules on T cells and monocytes may regulate numerous events on both cell types that are important for T cell activation. Given that recent data suggest that the CD44 molecule may bind to specific ligands on endothelial cells (vascular addressin) and within the extracellular matrix (collagen, fibronectin), these data raise the possibility that binding of T cells to endothelial cells or extracellular matrix proteins may induce or up-regulate T cell activation in inflammatory sites.
Article
We describe a 90-kDa lymphocyte surface glycoprotein, recognized by the monoclonal antibody Hermes-1, that is involved in endothelial cell recognition and lymphocyte trafficking in man. This molecule is selectively expressed on normal or transformed lymphoid cells that are able to recognize and bind to high endothelial venules (HEV, specialized vessels that mediate lymphocyte exit from the blood into lymphoid organs); appears to be linked to HEV recognition function since, in fluorescence-activated cell sorting of variants of a cloned cell line, HEV binding ability co-selects with the Hermes-1 antigen; bears the predominant cell surface epitopes recognized by heterologous anti-human lymphocyte antibodies able to interfere with lymphocyte binding to HEV; and is structurally similar to a previously described mouse lymphocyte surface receptor for HEV. These findings demonstrate that the molecule defined by Hermes-1 either functions as a specific lymphocyte surface receptor for HEV, or is both precisely coregulated and physically and/or functionally associated with such receptors. The expression of this putative receptor for HEV on normal human lymphocyte populations parallels, and thus presumably helps determine, their migratory status in vivo. Hermes-1 should be a powerful tool for analyzing the role of endothelial cell recognition in the traffic of normal and neoplastic human lymphocytes.
Article
Lymphocyte interactions with high endothelial venules (HEV) during extravasation into lymphoid tissues involve an 85-95 kd class of lymphocyte surface glycoprotein(s), gp90Hermes (CD44). We report here the cloning of cDNA for gp90Hermes expressed in a mucosal HEV-binding B lymphoblastoid cell line, KCA. Northern hybridization revealed the presence of three invariant RNA bands at 1.5, 2.2, and 4.5 kb in mucosal HEV-, lymph node HEV-, or dual-binding cells. The deduced amino acid sequence predicts a mature protein with a C-terminal cytoplasmic tail, a hydrophobic transmembrane domain of 23 amino acids, and an N-terminal extracellular region of 248 amino acids. A proximal extracellular domain is the probable region of O-glycosylation and chondroitin sulfate linkage and displays at least two of the three immunodominant epitope clusters of native gp90Hermes. A distal region contains the majority of potential N-glycosylation sites and cysteines, and exhibits a striking homology to tandemly repeated domains of the cartilage link and proteoglycan core proteins. No significant similarities were found to the immunoglobulin, integrin, or cadherin gene families. Thus gp90Hermes represents a novel class of integral membrane protein involved in lymphocyte-endothelial cell interactions and lymphocyte homing.
Article
The migration of lymphocytes from the bloodstream into the secondary lymphoid organs, which is necessary for a successful immune response, occurs primarily within postcapillary venules that are characterized by high-walled endothelial cells. Lymphocyte adhesion to and extravasation at these sites is associated with the expression of specific lymphoid receptors for this specialized venule endothelium. We report here the molecular cloning from a baboon lymphoid cell line of a cDNA that encodes an adhesion receptor for HEV. The 362-amino acid protein encoded by this cDNA is not present in any of the data bases examined. The mature protein, resulting from the cleavage of a putative 20-amino acid signal peptide, has a calculated molecular mass of only 37 kDa, indicating that the 90-kDa cell surface protein is highly modified. The 342 amino acids, which lack any repeated sequences of significant length, encompass an extracellular domain (250 amino acids), a putative transmembrane domain (20 amino acids), and a cytoplasmic domain (72 amino acids).
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The CDw44 glycoprotein was purified from 2.3 x 10(11) CD3+ CD4+ CD8- T-chronic lymphocytic leukaemia (CLL) cells using F10-44-2 monoclonal antibody affinity chromatography, DEAE-Sepharose anion-exchange chromatography, passage down carboxymethyl (CM)-Sepharose cation-exchange columns, wheat germ lectin affinity chromatography and gel-permeation chromatography. On elution in non-ionic detergents from the DEAE column, two distinct peaks of antigen activity were obtained. The CDw44 glycoprotein in each peak was a glycoprotein of 85,000 MW, but the amino acid composition of the peaks was noticeably different. Carbohydrate compositions showed that each peak contained approximately 30% (w/w) carbohydrate, the composition suggesting both O-linked and complex N-linked glycans. Modulation studies with the F10-44-2 antibody on normal peripheral blood mononuclear cells (PBMC) demonstrated that the CDw44 glycoprotein of T cells consisted of one fraction that was readily modulated, and the other which was resistant to modulation. Detailed tissue distribution studies for CDw44 were performed using the F10-44-2 antibody on frozen sections of human tissues. CDw44 has a restricted tissue distribution, but is found on many highly diverse cell types (e.g. T lymphocytes, smooth muscle cells, some secretory glands, skin epithelial cells).
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Studies of T cell adhesion and activation reveal two new functions of the CD44 molecule, a molecule now recognized to be identical to three molecules of functional interest: Pgp-1, Hermes, and extracellular matrix receptor type III (ECMRIII). By screening for mAb which inhibit T cell adhesion to E, we have identified a functionally unique CD44-specific mAb, NIH44-1, which partially inhibits T cell rosetting by binding to CD44 on the E. NIH44-1, which immunoprecipitates a protein of 85 to 110 kDa with broad tissue distribution, was determined to be specific for CD44 based on comparison of its tissue distribution with multiple CD44-specific reference mAb and sequential immunoprecipitation with such mAb. Anticipating a role for many adhesion molecules in signal transduction, we studied the effect of CD44 mAb on T cell activation and observed that CD44 mAb dramatically augments T cell proliferation induced by CD3- and CD2-receptor-mediated activation. The augmentation of the response to immobilized CD3 mAb by exhaustively monocyte-depleted T cells indicates that augmentation can be mediated by binding to the T cell. Thus, our studies demonstrate specific new roles for CD44 in T cell adhesion and activation. Furthermore, we suggest that: 1) CD44 has a role in adhesion of cells of multiple lineages; and 2) CD44 may participate in adhesion not (only) by functioning as an adhesion receptor but rather by serving as an anchorage site for other adhesion molecules.
Article
The study of cell surface molecules that are involved in interactions between immune and non-hematopoietic cells in various microenvironments is currently an area of great interest. One molecule that appears to be involved in multiple steps of normal immune cell function is now called CD44 and has been known previously as Pgp-1, In(Lu)-related p80, Hermes, ECM-III and HUTCH-I. Within the past year, the co-identity of all of these independently discovered molecules has become apparent, and the role of the CD44 molecule in T-cell activation has been discovered. In this review, Barton Haynes and his colleagues bring together numerous divergent lines of investigation on the CD44 molecule, review the many functional roles attributed to it, and present a unifying view of how, with numerous ligands, it may participate in several areas of normal immune cell function.
Article
The monoclonal antibody (F 10-44-2) described in this report recognizes an antigen which by quantitative absorption analysis is found predominantly on spleen, lymph node, bone marrow, thymus, granulocytes and brain, the amount of antigen on these tissues being approximately the same within a factor of 2 or 3. Analysis with the fluorescence-activated cell sorter showed that 29% of thymus cells, 61% of bone marrow cells, 95% of blood mononuclear cells, 98% of lymph node lymphocytes and 100% of granulocytes carried the antigen. With blood mononuclear cells and lymph node lymphocytes, there were two distinct peaks, with one peak labeling very weakly. Double labeling experiments established that the weakly labeled peak contained the B lymphocytes. Studies on frozen sections of thymus established that positive thymocytes were found only in the medulla indicating that the antigen appears late in T lymphocyte maturation. The lymphatic nodules (B lymphocyte areas) of spleen and lymph node appeared virtually negative on frozen sections showing that there was too little antigen on the B lymphocyte surface for confident detection by fluorescence microscopy. Sodium dodecyl sulfate polyacrylamide gel eletrophoresis of NaB3H4-labeled blood mononuclear cells established that the antigen was a major glycoprotein of the leukocyte membrane and that its mol. wt. was 105000. This antigen shows a striking similarity in biochemistry and tissue distribution to the W 3/13 antigen of the rat and is likely to be the human homologue of this antigen.
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