Robert Rothlein

A cell adhesion molecule, ICAM-1, is the major surface receptor for rhinoviruses

Rhinoviruses, which cause common colds, possess over 100 serotypes, 90% of which (the major group) share a single receptor. Lymphocyte function associated molecule 1 (LFA-1) mediates leukocyte adhesion to a wide variety of cell types by binding to intercellular adhesion molecule 1 (ICAM-1). We demonstrate identity between the receptor for the major group of rhinoviruses and ICAM-1. A major group rhinovirus binds specifically to purified ICAM-1 and to ICAM-1 expressed on transfected COS cells, and binding is blocked by three ICAM-1 monoclonal antibodies (MAb) that block ICAM-1-LFA-1 interaction, but not by an ICAM-1 MAb that does not block ICAM-1-LFA-1 interaction. This suggests that the ICAM-1 contact site(s) for LFA-1 and rhinoviruses is proximal or identical. In addition, ICAM-1 MAb block the cytopathic effect in HeLa cells mediated by representative major but not minor group rhinoviruses. ICAM-1 is induced by soluble mediators of inflammation, suggesting that the host immune response to rhinovirus may facilitate spread to uninfected cells.

Intercellular adhesion molecule-1 (ICAM-1) expression and cell signaling cascades

The collective interaction between cells is, in part, mediated by different families of adhesion molecules. Intercellular adhesion molecules (ICAMs) are structurally related members of the immunoglobulin supergene family and are ligands for the beta2 integrin molecules present on leukocytes. Of the five ICAMs identified, ICAM-1 is the most extensively studied. Although ICAM-1 is expressed constitutively at low levels on endothelial cells and on some lymphocytes and monocytes, its expression can be significantly increased in the presence of cytokines (TNFalpha, IL-1, IFNgamma) and reactive oxygen species. Depending upon cell type, ICAM-1 participates in trafficking of inflammatory cells, in cell:cell interactions during antigen presentation, in microbial pathogenesis, and in signal transduction through outside-in signaling events. Again, depending upon cell type examined, ICAM-1 engagement has been documented to activate specific kinases through phosphorylation, resulting in transcription factor activation and increased cytokine production, increased cell membrane protein expression, reactive oxygen species production, and cell proliferation.

Kinetics and characterization of intercellular adhesion molecule-1 (ICAM-1) expression on keratinocytes in various inflammatory skin lesions and malignant cutaneous lymphomas

The kinetics of expression of the intercellular adhesion molecule-1 (ICAM-1) were studied on keratinocytes in skin biopsy specimens of sensitive persons in whom the haptens were applied in a standardized format for allergic contact dermatitis testing. There was no ICAM-1 expressed on keratinocytes of normal skin; ICAM-1 was induced as early as 4 hours after the application of the patch in some subjects. By 48 hours after the application of the patch, all specimens contained ICAM-1-positive keratinocytes. This was concurrent with a heavy mononuclear cell dermal infiltrate and maximum clinical manifestations. Expression of human lymphocyte antigen (HLA)-DR or other inducible surface proteins on keratinocytes under these conditions was much less frequent. When specimens from primary irritant dermatitis were used, only 1 of 14 cases had keratinocytes expressing ICAM-1 at 48 hours, the time of maximum clinical manifestation. Among benign inflammatory lesions, most cases resembled the allergic patch test specimens in that ICAM-1 was expressed to a large degree on keratinocytes. Again, the expression of HLA-DR was variable. Malignant skin lesions, on the other hand, were much less consistent and generally lower in terms of ICAM-1 expression on keratinocytes. Furthermore, in contrast to the benign cutaneous conditions, some malignant skin lesions contained keratinocytes that expressed class II antigens or other inducible surface proteins in the absence of ICAM-1. These data suggest that ICAM-1 plays a role in the specific immune response by facilitating either antigen presentation or lymphocytic infiltration.

INTERCELLULAR ADHESION MOLECULE 1 ON LIVER ALLOGRAFTS DURING REJECTION

The expression of intercellular adhesion molecule 1 (ICAM-1), a ligand for the leucocyte adhesion receptor lymphocyte-function-associated antigen 1 (LFA-1), was studied on liver tissue after transplantation. There was greater ICAM-1 expression on bile ducts, endothelium, and perivenular hepatocytes (structures affected by the rejection process) in patients with acute rejection than in donor livers, patients with stable transplants, or patients with non-rejection complications. The expression on bile ducts and hepatocytes was greater in patients in whom there was progression to chronic, irreversible rejection. In patients with resolving rejection ICAM-1 expression was greatly reduced after high-dose corticosteroid treatment. The expression in patients with non-rejection complications and in those with long-term stable grafts was similar to that seen in the donor controls. The induction of ICAM-1 on tissues may be an important step in the development of the inflammatory response of rejection and in determining which cells are the targets of immune damage. The reduction of ICAM-1 expression seen after successful treatment with high-dose corticosteroids suggests that this might be an important mode of action of these drugs.

Monoclonal Antibodies to the Leukocyte Membrane CD18 Glycoprotein Complex and to Intercellular Adhesion Molecule‐1 Inhibit Leukocyte‐Endothelial Adhesion in Rabbits

Increasing evidence indicates that leukocyte‐endothelium adhesion is mediated, in part, by the CD11/CD18 family of heterodimeric glycoproteins expressed on the leukocyte plasma membrane and by intercellular adhesion molecule‐1 (ICAM‐1) which is expressed on endothelial cells. We have used the technique of intravital microscopy to visualize the microcirculation of the rabbit mesentery and to evaluate effects of antibodies against several adhesion glycoproteins on C5a‐induced leukocyte adhesion. Addition of zymosan‐activated serum (a source of C5a) to the buffer superfusing the mesenteric microvasculature induced rapid adhesion of leukocytes to the endothelium of post‐capillary venules. Monoclonal antibodies R15.7 (anti‐CD18), R7.1 (anti‐CD11a, LFA‐1), and R6.5 (anti‐ICAM‐1), administered intravenously before C5a exposure, strongly inhibited leukocyte adherence while antibody LM2 (anti‐CD11b, Mac‐1) produced significant, but weaker, inhibition. If these antibodies were administered after C5a‐induced adhesion had begun, both R15.7 and R7.1 displaced adherent leukocytes and prevented further leukocyte accumulation: LM2 and R6.5 did not displace adherent leukocytes or inhibit incoming leukocytes from adhering. These data confirm earlier findings establishing a role for CD18 in leukocyte adhesion in vivo and extend those observations to implicate both CD11a and CD11b in that adhesion. In addition, we report that ICAM‐1 mediates, in part, the initial leukocyte–endothelial cell adhesion following C5a exposure in vivo.

Integrins, ICAMs, and Selectins: Role and Regulation of Adhesion Molecules in Neutrophil Recruitment to Inflammatory Sites

Publisher Summary This chapter discusses the key adhesion molecules involved in leukocyte trafficking to sites of inflammation, focuses on mechanisms to regulate adhesion molecule expression and function, and defines some of the steps involved in neutrophil–endothelial cell interactions. The chapter summarizes the progress made in testing anti-adhesion molecule monoclonal antibodies (MAbs) in animal models of inflammatory diseases. Neutrophils are the front line of defense and are rapidly mobilized and recruited to sites of tissue injury or infection. This efficient response requires that neutrophils gain access to virtually any tissue. In addition to traditional random screening of large chemical libraries, it may be possible to rationally design drugs based on known ligand structures, such as small carbohydrates for selectins or peptide-based antagonists. In addition to direct receptor antagonists, drugs that modulate adhesion molecule regulation or expression may also be effective.

RAGE Ligation Affects T Cell Activation and Controls T Cell Differentiation

The pattern recognition receptor, RAGE, has been shown to be involved in adaptive immune responses but its role on the components of these responses is not well understood. We have studied the effects of a small molecule inhibitor of RAGE and the deletion of the receptor (RAGE−/− mice) on T cell responses involved in autoimmunity and allograft rejection. Syngeneic islet graft and islet allograft rejection was reduced in NOD and B6 mice treated with TTP488, a small molecule RAGE inhibitor (p < 0.001). RAGE−/− mice with streptozotocin-induced diabetes showed delayed rejection of islet allografts compared with wild type (WT) mice (p < 0.02). This response in vivo correlated with reduced proliferative responses of RAGE−/− T cells in MLRs and in WT T cells cultured with TTP488. Overall T cell proliferation following activation with anti-CD3 and anti-CD28 mAbs were similar in RAGE−/− and WT cells, but RAGE−/− T cells did not respond to costimulation with anti-CD28 mAb. Furthermore, culture supernatants from cultures with anti-CD3 and anti-CD28 mAbs showed higher levels of IL-10, IL-5, and TNF-α with RAGE−/− compared with WT T cells, and WT T cells showed reduced production of IFN-γ in the presence of TTP488, suggesting that RAGE may be important in the differentiation of T cell subjects. Indeed, by real-time PCR, we found higher levels of RAGE mRNA expression on clonal T cells activated under Th1 differentiating conditions. We conclude that activation of RAGE on T cells is involved in early events that lead to differentiation of Th1+ T cells.

Elevated Levels of Circulating Adhesion Molecules in IDDM Patients and in Subjects at Risk for IDDM

Serum levels of recently discovered circulating forms of adhesion molecules, ICAM-1 and L-selectin, were found to be elevated in IDDM patients and in subjects at risk for developing IDDM compared with 100 normal, nondiabetic blood donors. Both adhesion molecules were determined by sandwich ELISA. Serum concentrations of either clCAM-1 or cL-selectin were >2SD of normal mean in 10 of 14 recent-onset IDDM patients (P < 0.05). Serum levels of clCAM-1 and cL-selectin did not correlate. In first-degree relatives, elevated adhesion molecule levels were observed in the 6 ICA+ individuals and in the ICA− individuals all (n = 14) with a genetic risk of IDDM (sharing HLA-DR3 and/or -DR4− with the diabetic relative) but not in the HLA-DR3− and/or -DR4− relatives (n = 13). We conclude that elevated clCAM-1 and cL-selectin levels occur independently of ICA status and probably reflect ongoing immune processes in recent-onset IDDM patients and first-degree relatives at risk for IDDM.

Intercellular adhesion molecule-1 (ICAM-1) expression correlated to inflammation

The presence of intercellular adhesion molecule‐1 (ICAM‐1) on keratinocytes of psoriatic skin lesions before and during 8‐methoxapsoralen and UVA light (PUVA) treatment was studied. ICAM‐1 was expressed on the keratinocytes in biopsies of the skin lesions of five patients with psoriasis. The patients who responded to PUVA treatment had a concurrent reduction of ICAM‐1 expression on the keratinocytes with a reduction of the number of cells in the mononuclear cellular infiltrate and a lessening of the severity of the disease. Patients who went into remission during therapy and then relapsed showed an increase in ICAM‐1 expression on keratinocytes with an increase in the number of cells in the mononuclear cell infiltrate and an increase in the severity of the disease. HLA‐DR expression on keratinocytes was variable during treatment and showed no strong correlation with disease severity.

Intercellular adhesion molecule-1 contributes to pulmonary oxygen toxicity in mice: Role of leukocytes revised

In immature or injured lungs, impaired alveolar gas exchange forces the use of elevated levels of inhaled oxygen to maintain life. But, at high concentrations oxygen induces lung injury, edema, and bronchopulmonary dysplasia, probably by stimulating the generation of reactive oxygen radicals and subsequent neutrophil infiltration. In addition to regulating neutrophil diapedesis, intercellular adhesion molecule-1 (ICAM-1) expression is marked on inflamed alveolar epithelium, suggesting a role for ICAM-1 in oxygen-induced, neutrophil-mediated parenchymal damage. To test this, we evaluated the rat anti-mouse ICAM-1 monoclonal antibody YN 1/1.7 in 2 protocols of oxygen-induced toxicity in adult, male Balb-c mice: ≥95% O2 for 84 hr and ≥95% O2 for 60 hr followed by 48 hr at 21% (ambient) O2. YN1/1.7 treatment partially attenuated the neutrophil infiltration, lung damage (lavage lactate dehydrogenase [LDH] activity) and dysfunction (reductions in respiratory system compliance [Crs] and diffusion capacity of the lungs for carbon monoxide [DLco] in the 84 hr exposure protocol. In the milder 60 hr exposure protocol, YN1/1.7 completely blocked the oxygen-induced lung dysfunction (reductions in Crs and DLco). These results confirm the contribution of leukocytes in the pathogenesis of pulmonary oxygen toxicity and indicate that antagonism of ICAM-1 may provide a therapeutic approach to reducing hyperoxic lung injury and dysfunction.