Biomedical subjects

T S Kupper

Publications and source records attributed to T S Kupper.

At least 55 records · Page 3Linked to original sources

PubMed1995

The interleukin-1 axis and cutaneous inflammation.

Since the discovery that epidermal cell-derived thymocyte-activating factor was identical to interleukin (IL)-1 alpha and -beta in 1986, these molecules have been implicated in the pathogenesis of skin diseases. In 1995, it has become clear that a group of gene products function to regulate the activity of IL-1. IL-1 alpha and mature 17-kD IL-1 beta (cleaved from precursor by IL-1 beta-converting enzyme) bind to the type 1 IL-1 receptor to transduce a signal. This process can be antagonized at the level of the receptor by two distinct forms of the IL-1 receptor antagonist, which bind to the type I receptor but do not transduce a signal. The process can also be antagonized at the level of the ligand by either cell-bound or soluble type 2 IL-1 receptor. This type 2 IL-1 receptor binds ligand but does not transduce a signal. Keratinocytes can make each of these variables in vitro, and the balance between agonists and antagonists dictates the biologic outcome of a putative IL-1-mediated event. Transgenic mice that overexpress each of these factors individually in epidermis will be useful for enhancing our understanding of the cutaneous biology of IL-1.

Animals↗

PubMed1995

Keratinocyte-derived monocyte chemoattractant protein 1 (MCP-1): analysis in a transgenic model demonstrates MCP-1 can recruit dendritic and Langerhans cells to skin.

Chemokines are thought to play a central role in the recruitment and activation of leukocytes during inflammatory responses. Monocyte chemoattractant protein 1 (MCP-1) is a chemokine of the C-C or beta family that is chemotactic in vitro for monocytes, T cells, and basophils. Its excessive production by keratinocytes has been implicated in psoriasis and other skin diseases. To test the in vivo role of MCP-1 in inflammatory skin disease, we undertook the generation of transgenic mice that express murine MCP-1 in the basal layer of epidermis. Despite production of high levels of functional MCP-1 by basal keratinocytes, documented in vivo and in vitro, these mice did not exhibit spontaneous cutaneous inflammation or any other discernible skin pathology. In contrast, elicited inflammation in the skin of these mice differed qualitatively and quantitatively from that observed in non-transgenic controls. Contact hypersensitivity challenge responses in transgenic animals were characterized by an exaggerated lichenoid infiltration of monocytes and T cells. Additional phenotypic characterization of the normal appearing skin in these mice showed that the only spontaneous change was a dramatic increase and redistribution of CD45+, I-A+ cells that assumed a dendritic morphology in situ, including a subset that expressed markers characteristic of Langerhans cells. Taken together, these data indicate that tissue-specific expression of MCP-1 alone is not sufficient to induce an inflammatory response, though its presence can modify inflammatory and immune events initiated by exogenous stimuli. The recruitment of dendritic and Langerhans cells in the absence of inflammation is a previously unknown consequence of cutaneous MCP-1 production in vivo.

Afferent Pathways↗

PubMed1995

Adhesion molecules in scleroderma: collagen binding integrins.

In summary, adhesion molecules are likely to play a prominent role in scleroderma pathogenesis and evolution. Endothelial adhesion molecules required for leukocyte extravasation are upregulated in affected tissue, though the mechanism is unclear. Certainly, endothelial adhesion molecule expression is seen in the context of other diseases not characterized by fibrosis. Adhesion molecules on the fibroblast, particularly those that play a role in fibroblast collagen interactions, may be very important. The ability of fibroblasts to organize collagen fibrils, and to exert forces across collagenous tissue, is likely to involve a prominent role of alpha 2 beta 1 integrin. Enhanced organization and contraction of newly formed collagen, as well as unregulated procollagen production, may be intimately linked in this disease process. At least two factors that strongly enhance fibroblast force generation could potentially influence other aspects of scleroderma. TGF beta is a potent stimulus for collagen production and has been found to be elevated in lesional scleroderma. Endothelin 1 is also a potent vasoconstrictor and is elevated in scleroderma patient serum as well [60,62-65]. Its apparent role in other fibrocontractive diseases suggests that its potential role in the pathogenesis of scleroderma deserves additional attention.

Cell Adhesion Molecules↗

PubMed1994

Keratinocyte expression of B7-1 in transgenic mice amplifies the primary immune response to cutaneous antigens.

Resting epidermal keratinocytes do not express B7-1 and other known CD28 counterligands with costimulatory activity. The absence of these costimulators on keratinocytes correlates with their ability to preferentially induce T-cell anergy instead of T-cell activation. To test the hypothesis that keratinocytes expressing a CD28 counterligand would be more effective inducers of T-cell-mediated immune responses in skin, we prepared transgenic mice in which expression of the B7-1 costimulator was targeted to basal keratinocytes by using the human K14 promoter. Keratinocytes from the K14/B7-1 transgenic line expressed high levels of surface B7-1. No spontaneous inflammatory changes were seen in transgenic skin, but epicutaneous application of contact sensitizers to these mice elicited a stronger primary ear swelling response than in controls. Sites of initial hapten application in transgenic mice also responded much more strongly to reapplication of hapten to a remote cutaneous site. Epidermal cell suspensions from transgenic mice contained normal numbers of Langerhans cells and dendritic epidermal T cells when analyzed by flow cytometry. Systemic treatment of the transgenic mice with interferon gamma induced high levels of class II major histocompatibility complex expression on keratinocytes but was not sufficient to initiate an inflammatory response. We conclude that the constitutive expression of the B7-1 molecule in vivo on a nonprofessional antigen-presenting cell is not by itself sufficient to trigger inflammatory changes, but B7-1 expression amplifies the host immune responses after exposure to nonself antigens presented by B7-1-expressing cells.

Animals↗

PubMed1994

Epidermal expression of intercellular adhesion molecule 1 is not a primary inducer of cutaneous inflammation in transgenic mice.

Keratinocytes at sites of cutaneous inflammation have increased expression of intercellular adhesion molecule 1 (ICAM-1), a cytokine-inducible adhesion molecule which binds the leukocyte integrins LFA-1 and Mac-1. Transgenic mice were prepared in which the expression of mouse ICAM-1 was targeted to basal keratinocytes by using the human K14 keratin promoter. The level of constitutive expression attained in the transgenic mice exceeded the peak level of ICAM-1 expression induced on nontransgenic mouse keratinocytes in vitro by optimal combinations of interferon gamma and tumor necrosis factor alpha or in vivo by proinflammatory stimuli such as phorbol 12-myristate 13-acetate. In vitro adhesion assays demonstrated that cultured transgenic keratinocytes were superior to normal keratinocytes as a substrate for the LFA-1-dependent binding of mouse T cells, confirming that the transgene-encoded ICAM-1 was expressed in a functional form. However, the high level of constitutive ICAM-1 expression achieved on keratinocytes in vivo in these transgenic mice did not result in additional recruitment of CD45+ leukocytes into transgenic epidermis, nor did it elicit dermal inflammation. Keratinocyte ICAM-1 expression also did not potentiate contact-hypersensitivity reactions to epicutaneous application of haptens. The absence of a spontaneous phenotype in these transgenic mice was not the result of increased levels of soluble ICAM-1, since serum levels of soluble ICAM-1 were equal in transgenic mice and controls. We conclude that elevated ICAM-1 expression on keratinocytes cannot act independently to influence leukocyte trafficking and elicit cutaneous inflammation.

Animals↗

PubMed1994

Human dermal microvascular endothelial cells express the 140-kD isoform of neural cell adhesion molecule.

It has only recently been appreciated that the level of gene expression of cell surface markers can be different in endothelial cells derived from different anatomical sites, and that these differences can persist in vitro. In this study, we identify an immunoglobulin gene superfamily member, neural cell adhesion molecule (NCAM), that is expressed on the cell surface of human dermal microvascular endothelial celis but not on umbilical vein, pulmonary vein, aorta, or pulmonary artery derived endothelial cells. By western blot analysis, we identified the 140 kD isoform of NCAM on the surface of human dermal microvascular endothelial cells (HDMEC) derived from dermis. Isolates of HDMEC from human foreskin reproducibly expressed high levels of cell surface immunoreactive protein. In contrast, endothelial cells from large vessels never expressed NCAM constitutively and could not be induced to express NCAM by three proinflammatory cytokines. Western blot analysis of membrane preparations of HDMEC indicated that NCAM protein migrated as a single species with a molecular mass of 140 kD. RT-PCR identified NCAM mRNA in HDMEC cells. The potential for expression of NCAM on small vessels in skin can be interpreted in different ways. Members of the immunoglobulin gene family, including ICAM-1, ICAM-2, and VCAM-1, can be expressed on the cell surface of all endothelial cells and serve as adhesion molecules for leukocytes. It is also possible that, by analogy, NCAM serves as a ligand for a receptor on leukocytes, particularly those that also express NCAM (e.g., natural killer cells). Alternatively, it is possible that NCAM expression permits endothelial cell-cell adhesion, enhancing the structural integrity of microvessels or facilitates neural interactions with microvascular endothelium.

Antibodies, Monoclonal↗

PubMed1994

Leukocytosis and resistance to septic shock in intercellular adhesion molecule 1-deficient mice.

Intercellular adhesion molecule 1 (ICAM-1) is one of three immunoglobulin superfamily members that bind to the integrins lymphocyte function associated 1 (LFA-1) and Mac-1 on leukocytes. We have generated mice that are genetically and functionally deficient in ICAM-1. These mice have elevated numbers of circulating neutrophils and lymphocytes, as well as diminished allogeneic T cell responses and delayed type hypersensitivity. Mutant mice are resistant to lethal effects of high doses of endotoxin (lipopolysaccharide [LPS]), and this correlates with a significant decrease in neutrophil infiltration in the liver. Production of inflammatory cytokines such as tumor necrosis factor alpha or interleukin 1 is normal in ICAM-1-deficient mice, and thus protection appears to be related to a diminution in critical leukocyte-endothelial interactions. After sensitization with D-galactosamine (D-Gal), ICAM-1-deficient mice are resistant to the lethal effect of low doses of exotoxin (Staphylococcus aureus enterotoxin B [SEB]), which has been shown to mediate its toxic effects via the activation of specific T cells. In this model, ICAM-1-mediated protection against SEB lethality correlates with a decrease in the systemic release of inflammatory cytokines, as well as with prevention of extensive hepatocyte necrosis and hemorrhage. ICAM-1-deficient mice sensitized with D-Gal, however, are not protected from lethality when challenged with low doses of endotoxin (LPS). These studies show that the different contribution of ICAM-1 in the activation of either T cells or macrophages is decisive for the fatal outcome of the shock in these two models. This work suggests that anti-ICAM-1 therapy may be beneficial in both gram-positive and -negative septic shock, either by reducing T cell activation or by diminishing neutrophil infiltration.

Animals↗

PubMed1994

Skin disease-related T cells bind to endothelial selectins: expression of cutaneous lymphocyte antigen (CLA) predicts E-selectin but not P-selectin binding.

Cutaneous lymphocyte antigen (CLA), defined by the HECA-452 antibody, is a cell surface glycoprotein found on a subset of T cells in peripheral blood that binds specifically to E-selectin. This marker is present on the majority of T cells at sites of cutaneous inflammation and immune responses. Based upon such evidence, an association between T cell CLA expression and skin homing has been proposed. To understand better this relationship, we asked whether putative disease-related, antigen-specific T cells expressed CLA. In this study, we employed T helper type 2 (TH2) T cell clones specific for house dust mite (Dermatophagoides pteronyssinus) antigens. These cells were derived from challenged skin of an individual known to react positively to epicutaneous challenge with this agent. In this study, we show that these cloned T cells showed very high homogeneous expression of CLA (nearly 500-fold higher than T cell clones derived from peripheral blood) and bound specifically to recombinant E-selectin. The CLA molecule on these cells was identified not only by HECA-452, but also by CSLEX-1, indicating that it contained sialyl-Le(x) (S-Le(x)) determinants. T cells cloned under similar conditions from peripheral blood were CLA negative or low and bound poorly to E-selectin. Surprisingly, both skin and blood clones bound comparably to P-selectin. This binding was independent of S-Le(x) or CLA expression. We conclude that in sensitized individuals, antigen-specific T cells expressing high levels of CLA localize in skin promptly after epicutaneous challenge. This localization is likely to involve the interaction of S-Le(x) determinants on the CLA molecule with E-selectin on the dermal microvasculature. We further conclude that T cells can interest with P-selectin on endothelium and that S-Le(x) does not appear to be necessary for this interaction.

Animals↗

PubMed1994

Distinct cell surface ligands mediate T lymphocyte attachment and rolling on P and E selectin under physiological flow.

Memory T lymphocytes extravasate at sites of inflammation, but the mechanisms employed by these cells to initiate contact and tethering with endothelium are incompletely understood. An important part of leukocyte extravasation is the initiation of rolling adhesions on endothelial selectins; such events have been studied in monocytes and neutrophils but not lymphocytes. In this study, the potential of T lymphocytes to adhere and roll on endothelial selectins in vitro was investigated. We demonstrate that T cells can form tethers and rolling adhesions on P selectin and E selectin under physiologic flow conditions. Tethering and rolling on P selectin was independent of cell-surface cutaneous lymphocyte antigen (CLA) expression, which correlated strictly with the capacity of T cells to form rolling adhesions under flow on E selectin. T cell tethering to P selectin was abolished by selective removal of cell surface sialomucins by a P. haemolytica O-glycoprotease, while cutaneous lymphocyte antigen expression was unaffected. A sialomucin molecule identical or closely related to P selectin glycoprotein ligand-1 (PSGL-1), the major P selectin ligand on neutrophils and HL-60 cells, appears to be a major T cell ligand for P selectin. P selectin glycoprotein ligand-1 does not appear to support T cell rolling on E selectin. In turn, E selectin ligands do not appear to be associated with sialomucins. These data demonstrate the presence of structurally distinct ligands for P or E selectins on T cells, provide evidence that both ligands can be coexpressed on a single T cell, and mediate tethering and rolling on the respective selectins in a mutually exclusive fashion.

Antigens, Differentiation, T-Lymphocyte↗

PubMed1994

Detection of interleukin-1 receptors in human epidermis. Induction of the type II receptor after organ culture and in psoriasis.

Normal human epidermis is a rich source of biologically active interleukin-1 alpha (IL-1 alpha). Keratinocytes both synthesize this cytokine and respond to it via cell surface receptors (IL-1R), suggesting that the IL-1 system may play an important role in normal epidermal physiology and inflammation. In this study, we have examined the expression of IL-1R in normal and psoriatic epidermis, as judged at a functional level by the capacity to bind 125I-labeled IL-1 alpha (the principal IL-1 species present in epidermis) and by immunostaining with antibodies specific for each species of IL-1R. IL-1R was not readily detectable by either technique in normal, freshly isolated human epidermis. However, in lesional psoriasis or normal epidermis after 24 hours of organ culture, expression of IL-1R was dramatically induced, especially in basal keratinocytes. Immunostaining and antibody blocking studies demonstrated the induced IL-1R to be the type II species, a nonsignal transducing molecule previously demonstrated only on leukocytes. The Ka of this receptor was comparable to that previously demonstrated in vitro. mRNA for both species of IL-1R could be demonstrated by reverse transcriptase-polymerase chain reaction in fresh and cultured epidermis. These in vivo findings were confirmed in culture, where normal human keratinocytes expressed few IL-1R at rest but large numbers of type II IL-1R after activation by phorbol ester or interferon-gamma. We conclude that under resting conditions, epidermal expression of IL-1R is low. However, the potential for keratinocytes in vivo to express large numbers of the nonsignal transducing type II IL-1R is evident from both organ cultured and psoriatic epidermis. The in vitro induction of keratinocyte IL-1R by interferon-gamma suggests that this cytokine may be involved in the induction of type II IL-1R in inflammatory skin disease. The presence of bioactive IL-1 in epidermis, coupled with the inducible expression of the decoy type II IL-1R, indicates the existence of a highly regulated system of autocrine stimulation of keratinocytes by IL-1.

Autoradiography↗

PubMed1993

Antigen-independent processes in antigen-specific immunity. A role for alpha 4 integrin.

It has been proposed that the migration of immune T cells out of blood vessels through connective tissue to the site of antigenic challenge is facilitated by the interaction of VLA integrins on lymphocytes with endothelial cell adhesion molecules and matrix proteins. Indeed, we have recently demonstrated that peptides derived from sequences in fibronectin abrogate the T cell-mediated contact hypersensitivity (CHS) reactions in vivo. These peptides blocked the interaction of the integrins VLA-4 and VLA-5 with fibronectin (FN), and our results suggested that by preventing the interaction of T cell integrins with FN, we successfully prevented the migration of T cells to sites of antigenic challenge. To further explore the role of integrins in T cell migration, we have used an antibody (R1-2) specific for the alpha-chain of alpha 4 integrins. Our data show that this antibody stains more than 90% of CD3+ T cells, and this percentage does not change after the mice have been immunized with a contact sensitizer. We also show that this antibody blocks the interaction of cells with immobilized FN and vascular cell adhesion molecule-1 on activated endothelial cells. Although R1-2 identifies alpha 4 integrin on a large number of T cells, it does not discriminate between activated and resting forms of this integrin, because very few T cells from immune or nonimmune mice actually bind FN or activated endothelium. In vivo, antibody R1-2 effectively blocks Ag-specific CHS, but has little effect on the non-Ag-specific cells that localize to the site of antigenic challenge. The population of cells that adoptively transfer CHS exits with the population of cells that bind to FN or to activated endothelial cells. Our data demonstrate that a small number of Ag-specific T cells use alpha 4 integrin to enter sites of inflammation and mediate effector immune responses. Ag-independent accumulation of T cells near sites of inflammation does not appear to be mediated by alpha 4 integrin.

Animals↗

PubMed1993

Production of IL-3 by non-transformed primary neonatal murine keratinocytes: evidence for constitutive IL-3 gene expression in neonatal epidermis.

Interleukin 3 (IL-3) is a cytokine produced by activated T lymphocytes that is best understood as a hematopoietic growth and differentiation factor. Production of IL-3 by other cell types is controversial; while certain transformed non-lymphocyte cell lines can produce IL-3, it is generally assumed that their non-transformed counterparts do not. It has been previously reported that Pam 212, a transformed murine keratinocyte cell line, produces IL-3. In this study we report that IL-3 can also be secreted by normal murine keratinocytes. Using a cell line (FL5.12) which is responsive to IL-3 and not to other keratinocyte derived cytokines, (e.g. GM-CSF, IL-1 and IL-6), we tested conditioned media from cultures of normal neonatal keratinocytes for biologically active IL-3. These media stimulated the proliferation of FL5.12, and the effect could be neutralized by specific antibodies to IL-3. The presence of IL-3 mRNA was demonstrated by polymerase chain reaction (PCR) amplification of reverse transcribed IL-3 mRNA from cultured normal neonatal keratinocytes and confirmed by Southern blot analysis. By similar techniques, IL-3 mRNA could be identified in freshly isolated neonatal epidermis but not dermis. These data indicated that IL-3 is produced by keratinocytes in the skin of normal neonatal mice, raising the likelihood that the neonatal epidermal microenvironment may have hematopoietic or lymphopoietic properties.

Animals↗

PubMed1993

A potential pathophysiologic role for alpha 2 beta 1 integrin in human eye diseases involving vitreoretinal traction.

Cell-mediated contraction of tissues containing fibrillar collagens can lead to organ compromise and loss of function. The same process that is biologically advantageous during the contraction phase of wound healing can be subverted in diseases such as hepatic cirrhosis, pulmonary fibrosis, and scleroderma, although the cellular and molecular mechanism of matrix tissue contraction is difficult to study in such chronic diseases. However, certain human eye diseases that result in tractional detachment of the retina and loss of vision are characterized by acute cell-mediated contraction of collagenous tissue in the vitreous cavity. In this study, we demonstrate that human cells can contract vitreous, a complex biological gel containing type II collagen, in vitro. This cell-mediated contraction can be blocked by antibodies and peptides that antagonize the function of alpha 2 beta 1 integrin, and the potential for contraction can be conferred upon noncontracting cells by stable transfection of cells with alpha 2 cDNA. We also show that this contractile process, if focally resisted, can result in remodeling vitreous from a gel to a structure that resembles a planar membrane, and that substantial isometric forces can be measured across this tissue. We propose that in diseases such as proliferative diabetic retinopathy and proliferative vitreoretinopathy, alpha 2 beta 1 integrin-mediated contraction of the vitreous and tension at the site of vitreoretinal attachments contribute to the terminal event of tractional retinal detachment. By extension, we propose that alpha 2 beta 1 integrin is a centrally important molecule in human diseases characterized by remodeling and contraction of collagenous tissue (i.e., fibrocontractive diseases).

Antibodies↗

PubMed1993

Differential induction of intercellular adhesion molecule-1 in human skin by recombinant cytokines.

We examine the effects of the recombinant epidermal cytokines interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), interleukin 3 (IL-3), interleukin 6 (IL-6), granulocyte-macrophage colony stimulating factor (GM-CSF), macrophage colony stimulating factor (M-CSF), tumor necrosis factor alpha (TNF), and the effect of the lymphokine gamma interferon (gamma-IFN) on the expression of ICAM-1 in short term organ cultures of newborn human foreskins. In normal skin, ICAM-1 was detected immunohistochemically exclusively on endothelial cells. In addition to enhanced ICAM-1 expression by endothelial cells (at 1 h) and keratinocytes (by 6 h) exposed to gamma-IFN, increased endothelial cell expression also resulted at 24 h after exposure to IL-6 and GM-CSF and at 48 h to M-CSF. Dermal dendritic cell reactivity for ICAM-1 was observed at 24 h after supplementation with IL-1 alpha, IL-1 beta and IL-6, and at 48 h with GM-CSF and M-CSF. Incubation with culture medium alone or with IL-3 resulted in no change in baseline ICAM-1 expression on any cell type, and incubation with TNF resulted in enhanced ICAM-1 expression only by endothelial cells. Thus, in skin explants (as opposed to isolated cell in culture), ICAM-1 is induced on various cell types by a wide range of epidermal cytokines, including IL-6, GM-CSF, M-CSF, IL-1 alpha and IL-1 beta.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion Molecules↗

PubMed1992

Distinct cellular functions mediated by different VLA integrin alpha subunit cytoplasmic domains.

To characterize VLA alpha subunit cytoplasmic domain functions, unaltered alpha 2 cDNA (called X2C2) and two chimeric cDNAs (called X2C5 and X2C4) were constructed with extracellular alpha 2 domains and cytoplasmic alpha 2, alpha 5, and alpha 4 domains respectively. Upon transfection into rhabdomyosarcoma (RD) cells, each construct yielded comparable expression levels, immunoprecipitation profiles, and avidity for collagen and laminin. However, while RDX2C2 and RDX2C5 transfectants mediated collagen gel contraction, RDX2C4 and a mock transfectant (RDpF) did not. Conversely, only RDX2C4 cells (but not RDX2C2 or RDX2C5) showed enhanced cell migration on collagen and laminin compared with RDpF cells. This indicates markedly differing roles for integrin alpha subunit cytoplasmic domains in post-ligand binding events. Furthermore, stable exertion of physical force (collagen gel contraction) may involve fundamentally different cellular machinery than the transient adhesion occurring during cell migration. Finally, these findings provide insight into a functional flexibility perhaps resulting from multiple integrins binding to identical ligands.

Animals↗

PubMed1991

Integrin alpha 2 beta 1 (VLA-2) mediates reorganization and contraction of collagen matrices by human cells.

The capacity of cells to organize and contract collagen fibrils is fundamental to processes as diverse as embryogenesis and wound healing. We analyzed different beta 1 integrins on diploid fibroblasts for their role in modifying the tertiary structure of collagen matrices. Using monoclonal antibodies that block the interaction of integrins with their ligands, evidence was obtained that alpha 2 beta 1 integrin is required for the contraction of a type I collagen matrix. Further supporting the role of alpha 2 beta 1, cell lines expressing minimal levels of this integrin uniformly failed to contract collagen matrices. In addition, transfection of a full-length alpha 2 cDNA into one such cell line led to enhanced cell surface expression of alpha 2 beta 1 and conferred the de novo capacity to contract collagen matrices.

Antibodies, Monoclonal↗

PubMed1991

Rapid and specific conversion of precursor interleukin 1 beta (IL-1 beta) to an active IL-1 species by human mast cell chymase.

Secretory granules of human dermal mast cells contain a chymotrypsin-like serine proteinase called chymase. In this study, we demonstrate that the inactive cytokine, 31 kD interleukin 1 beta (IL-1 beta), can be converted rapidly to an 18 kD biologically active species by human mast cell chymase. The product formed is three amino acids longer at the amino terminus than the mature IL-1 beta produced by peripheral blood mononuclear cells and has comparable biological activity. Because chymase is a secretory granule constituent, it is likely to be released into the surrounding tissue when mast cells degranulate. It is also known that non-bone marrow derived cells resident in skin (keratinocytes, fibroblasts) produce but do not process 31 kD IL-1 beta. In this context, chymase may be a potent activator of locally produced 31 kD IL-1 beta. Mast cells lie in close apposition to blood vessels in dermis; therefore, chymase mediated conversion of 31 kD IL-1 beta might be expected to have a critical role in the initiation of the inflammatory response in skin.

Amino Acid Sequence↗

PubMed1991

Two integrin-binding peptides abrogate T cell-mediated immune responses in vivo.

Two VLA proteins (or beta 1 integrins; originally called very late activation antigens) that bind to distinct determinants on fibronectin (FN) are increased on activated immune or memory T cells. VLA-4 binds to the peptide sequence Gly-Pro-Glu-Ile-Leu-Asp-Val-Pro-Ser-Thr (GPEILDVPST in single-letter code) on the alternatively spliced CS-1 form of FN, whereas VLA-5 binds to an Arg-Gly-Asp sequence found on all forms of FN. It has been proposed that the migration of immune T cells out of blood vessels and through connective tissue to a site of antigenic challenge is facilitated by the interaction of such integrins with matrix protein molecules. We have examined directly the role of T-cell integrins in vivo by using the well-characterized, T-cell-mediated contact hypersensitivity (CHS) response to the hapten trinitrochlorobenzene (TNCB). We demonstrate that the cells that transfer CHS to TNCB adhere to FN in the presence of Ca2+/Mg2+, and T-cell populations depleted of FN-adherent cells do not transfer immunity. We further show that TNCB-immune T cells treated with the synthetic peptides GPEILDVPST or Gly-Arg-Gly-Asp-Ser-Pro (GRGDSP in single-letter code), ligands for VLA-4 and VLA-5, respectively, lose their ability to mediate this immune response in a murine model, whereas the control peptides Val-Ile-Pro-Asp-Leu-Thr-Glu-Ser-Pro-Gly and Gly-Arg-Gly-Glu-Ser-Pro have no effect. Neither GPEILDVPST nor GRGDSP significantly inhibited the proliferative response of TNCB-immune T cells in vitro. These data suggest that FN-binding integrins on T cells play a role in the localization of T cells to sites of antigenic challenge in tissue.

Amino Acid Sequence↗