Absence Of ICAM-1 Research Articles

ICAM-1null C57BL/6 Mice Are Not Protected from Experimental Ischemic Stroke.

Accumulation of neutrophils in the brain is a hallmark of cerebral ischemia and considered central in exacerbating tissue injury. Intercellular adhesion molecule (ICAM)-1 is upregulated on brain endothelial cells after ischemic stroke and considered pivotal in neutrophil recruitment as ICAM-1-deficient mouse lines were found protected from experimental stroke. Translation of therapeutic inhibition of ICAM-1 into the clinic however failed. This prompted us to investigate stroke pathogenesis in Icam1tm1Alb C57BL/6 mutants, a true ICAM-1null mouse line. Performing transient middle cerebral artery occlusion, we found that absence of ICAM-1 did not ameliorate stroke pathology at acute time points after reperfusion. Near-infrared imaging showed comparable accumulation of neutrophils in the ischemic hemispheres of ICAM-1null and wild type C57BL/6 mice. We also isolated equal numbers of neutrophils from the ischemic brains of ICAM-1null and wild type C57BL/6 mice. Immunostaining of the brains showed neutrophils to equally accumulate in the leptomeninges and brain parenchymal vessels of ICAM-1null and wild type C57BL/6 mice. In addition, the lesion size was comparable in ICAM-1null and wild type mice. Our study demonstrates that absence of ICAM-1 neither inhibits cerebral ischemia-induced accumulation of neutrophils in the brain nor provides protection from ischemic stroke.

ICAM-1 is a key receptor mediating cytoadherence and pathology in the Plasmodium chabaudi malaria model

BackgroundParasite cytoadherence within the microvasculature of tissues and organs of infected individuals is implicated in the pathogenesis of several malaria syndromes. Multiple host receptors may mediate sequestration. The identity of the host receptor(s), or the parasite ligand(s) responsible for sequestration of Plasmodium species other than Plasmodium falciparum is largely unknown. The rodent malaria parasites may be useful to model interactions of parasite species, which lack the var genes with their respective hosts, as other multigene families are shared between the species. The role of the endothelial receptors ICAM-1 and CD36 in cytoadherence and in the development of pathology was investigated in a Plasmodium chabaudi infection in C57BL/6 mice lacking these receptors. The schizont membrane-associated cytoadherence (SMAC) protein of Plasmodium berghei has been shown to exhibit reduced CD36-associated cytoadherence in P. berghei ANKA-infected mice.MethodsParasite tissue sequestration and the development of acute stage pathology in P. chabaudi infections of mice lacking CD36 or ICAM-1, their respective wild type controls, and in infections with mutant P. chabaudi parasites lacking the smac gene were compared. Peripheral blood parasitaemia, red blood cell numbers and weight change were monitored throughout the courses of infection. Imaging of bioluminescent parasites in isolated tissues (spleen, lungs, liver, kidney and gut) was used to measure tissue parasite load.ResultsThis study shows that neither the lack of CD36 nor the deletion of the smac gene from P. chabaudi significantly impacted on acute-stage pathology or parasite sequestration. By contrast, in the absence of ICAM-1, infected animals experience less anaemia and weight loss, reduced parasite accumulation in both spleen and liver and higher peripheral blood parasitaemia during acute stage malaria. The reduction in parasite tissue sequestration in infections of ICAM-1 null mice is maintained after mosquito transmission.ConclusionsThese results indicate that ICAM-1-mediated cytoadherence is important in the P. chabaudi model of malaria and suggest that for rodent malarias, as for P. falciparum, there may be multiple host and parasite molecules involved in sequestration.

Probing the Minimum Geometric Requirements for T-Cell Stimulation

The immune recognition process involves an elaborate arrangement of adhesion, costimulatory and signaling molecules organized into a stereotypic geometric structure known as the immunological synapse (IS). We have developed a versatile engineered platform to probe the minimum geometric requirements (in terms of spacing and stoichiometry) for T-cell stimulation. Arrays of metallic nanodots, ∼ 2-10 nm in size, to which a UCHT1 Fab antibody was bound, were created by nanolithography. These served as individual T-cell receptor (TCR) binding sites. The adhesion molecule ICAM-1 was either statically bound to a PEG-silane brush surrounding the nanodots, or it was allowed to move freely within the arrays in a supported lipid bilayer. T-cells were plated on arrays comprising individual TCR binding sites, small clusters and extended hexagonal close packed arrays, with spacings ranging from 40 nm and below to 1 μm. TCR signaling strength was monitored by measuring phosphorylated tyrosine (pY) intensity. T-cell adhesion was assessed by the number of cells bound to the arrays, as well as by the area of spread cells.Systematic variation of the spacing and cluster size of TCR binding sites in the arrays enabled determination of the minimum conditions that support T-cell signaling and the formation of the IS. TCR signaling increased with decreasing spacing below a threshold spacing ∼ 60 nm. For clusters with these spacings the formation of the stereotypic “bullseye” geometry that characterizes the immune synapse became evident, with ICAM-1 excluded to the periphery. In terms of stoichiometry, at least 4 TCR-binding sites (within ∼ 60 nm) were required for T-cell adhesion and spreading. Further, in the absence of ICAM-1 (or at low concentrations), a threshold density of agonist sites was found, above which the TCR apparently plays a dual role of immune activity and adhesion.

Ni–Cr based dental alloys; Ni release, corrosion and biological evaluation

In the last years the dental alloy market has undergone dramatic changes for reasons of economy and biocompatibility. Nickel based alloys have become widely used substitute for the much more expensive precious metal alloys.In Europe the prevalence of nickel allergy is 10–15% for female adults and 1–3% for male adults. Despite the restrictions imposed by the EU for the protection of the general population in contact dermatitis, the use of Ni–Cr dental alloys is on the increase. Some questions have to be faced regarding the safety risk of nickel contained in dental alloys.We have collected based on many EU markets, 8 Ni–Cr dental alloys. Microstructure characterization, corrosion resistance (generalized, crevice and pitting) in saliva and the quantities of cations released in particular nickel and CrVI have been evaluated. We have applied non parametric classification tests (Kendall rank correlation) for all chemical results. Also cytotoxicity tests and an evaluation specific to TNF-alpha have been conducted.According to the obtained results, it was found that their behavior to corrosion was weak but that nickel release was high. The quantities of nickel released are higher than the limits imposed in the EU concerning contact with the skin or piercing.Surprisingly the biological tests did not show any cytotoxic effect on Hela and L929 cells or any change in TNF-alpha expression in monocytic cells. The alloys did not show any proinflammatory response in endothelial cells as demonstrated by the absence of ICAM-1 induction.We note therefore that there is really no direct relationship between the in vitro biological evaluation tests and the physico-chemical characterization of these dental alloys. Clinical and epidemiological studies are required to clarify these aspects.

Memory CD8 T cell responses to IL-15 transpresentation are impaired in the absence of ICAM-1 (150.6)

Abstract Homeostatic proliferation is important for the long-term maintenance of memory CD8 T cells and is mediated by trans-presentation of IL-15. Since IL-15 transpresentation requires a cell-cell interaction, we asked whether ICAM-1 is important for IL-15 responses in memory CD8 T cells. After transfer into either Wt or ICAM-1-/- mice, Wt memory CD8 T cells displayed less homeostatic proliferation and decreased survival in the absence of ICAM-1. To determine whether the absence of ICAM-1 was directly affecting IL-15 transpresentation, IL-15 responses of isolated CD8 T cells were analyzed after culturing with DCs. IL-15-driven proliferation and STAT5 phosphorylation in memory CD8 T cells were completely abolished in cultures with ICAM-1-/- DCs or with blocking Ab against ICAM-1. Overall, this is the first report that establishes a link between ICAM-1 and IL-15 transpresentation and serves to demonstrate the importance of specific adhesion molecules in facilitating IL-15-mediated responses in memory CD8 T cells.

Entry of a heparan sulphate-binding HRV8 variant strictly depends on dynamin but not on clathrin, caveolin, and flotillin

The major group human rhinovirus type 8 can enter cells via heparan sulphate. When internalized into ICAM-1 negative rhabdomyosarcoma (RD) cells, HRV8 accumulated in the cells but caused CPE only after 3days when used at high MOI. Adaptation by three blind passages alternating between RD and HeLa cells resulted in variant HRV8v with decreased stability at acidic pH allowing for productive infection in the absence of ICAM-1. HRV8v produced CPE at 10 times lower MOI within 1day. Confocal fluorescence microscopy colocalization and the use of pharmacological and dominant negative inhibitors revealed that viral uptake is clathrin, caveolin, and flotillin independent. However, it is blocked by dynasore, amiloride, and EIPA. Furthermore, HRV8v induced FITC-dextran uptake and colocalized with this fluid phase marker. Except for the complete inhibition by dynasore, the entry pathway of HRV8v via HS is similar to that of HRV14 in RD cells that overexpress ICAM-1.

The Differential Role of L-Selectin and ICAM-1 in Th1-Type and Th2-Type Contact Hypersensitivity

Sensitization and challenge using DNFB induce contact hypersensitivity (CHS) with predominant type 1 helper (Th1) cell infiltration, whereas those using FITC generate CHS with Th2 cell infiltration. CHS results from inflammatory cell infiltration, a process that is highly regulated by the expression of multiple adhesion molecules. We attempted to determine the role of L-selectin and ICAM-1 in Th1- and Th2-type CHS induced by DNFB or FITC in mice lacking either L-selectin, ICAM-1, or both. Th1-type CHS induced by DNFB was inhibited by L-selectin and/or ICAM-1 deficiency, which was associated with reduced IFN-gamma expression. Similarly, Th2-type CHS induced by FITC was inhibited by L-selectin deficiency. However, Th2-type CHS was increased by ICAM-1 deficiency and accompanied by increased Th2 cytokine expression. Infiltration of in vitro-generated Th1 cells into the FITC-challenged skin decreased in ICAM-1-deficient mice, whereas in vitro-generated Th2 cell infiltration increased, suggesting that ICAM-1 mediates Th1 cell migration and that in the absence of ICAM-1, Th1 cell recruitment decreased, whereas relative Th2 cell migration increased. These results suggest that ICAM-1 mediates Th1 cell recruitment irrespective of DNFB or FITC and that L-selectin recruits Th1 cells in Th1-type CHS, whereas it recruits Th2 cells in Th2-type CHS.

Aberrant TGF-β signaling reduces T regulatory cells in ICAM-1-deficient mice, increasing the inflammatory response to Mycobacterium tuberculosis

Foxp3+ T regulatory cells are required to prevent autoimmune disease, but also prevent clearance of some chronic infections. While natural T regulatory cells are produced in the thymus, TGF-beta1 signaling combined with T-cell receptor signaling induces the expression of Foxp3 in CD4+ T cells in the periphery. We found that ICAM-1-/- mice have fewer T regulatory cells in the periphery than WT controls, due to a role for ICAM-1 in induction of Foxp3 expression in response to TGF-beta1. Further investigation revealed a functional deficiency in the TGF-beta1-induced translocation of phosphorylated Smad3 from the cytoplasmic compartment to the nucleus in ICAM-1-deficient mice. This impairment in the TGF-beta1 signaling pathway is most likely responsible for the decrease in T regulatory cell induction in the absence of ICAM-1. We hypothesized that in the presence of an inflammatory response, reduced production of inducible T regulatory cells would be evident in ICAM-1-/- mice. Indeed, following Mycobacterium tuberculosis infection, ICAM-1-/- mice had a pronounced reduction in T regulatory cells in the lungs compared with control mice. Consequently, the effector T-cell response and inflammation were greater in the lungs of ICAM-1-/- mice, resulting in morbidity due to overwhelming pathology.

Live Imaging of Cytotoxic Immune Synapses Reveals LFA-1-dependent Ligand Distribution and Bidirectional Vesicular Traffic (134.5)

Abstract Cytotoxic lymphocytes kill target cells by releasing the content of secretory lysosomes at the immune synapse. To obtain information on the dynamics and control of cytotoxic immune synapses we imaged primary, live natural killer cells on lipid bilayers carrying ligands of activation receptors by total internal reflection fluorescence microscopy. In the presence of the LFA-1 ligand ICAM-1, ligands of co-activation receptors 2B4 and NKG2D segregated into central and peripheral regions, respectively. Exocytosed lysosomal protein LAMP-1 accumulated in a central and stable region of the synapse, which overlapped with a site of membrane internalization. Lysosomal compartments reached the plasma membrane at focal points adjacent to centrally accumulated LAMP-1. In the absence of ICAM-1, the distribution of receptor ligands, of exocytosed LAMP-1, and of lysosomal compartment contacts with the plasma membrane was dispersed. Thus, live imaging has revealed LFA-1-dependent organization of cytotoxic immune synapses, including a central region of bidirectional vesicular traffic.

ICAM‐1 expression is required for regulatory T cell localization in the lungs of M tuberculosis infected mice

Mycobacterium tuberculosis (Mtb) is a widespread human pathogen that persists in the lungs of latently infected individuals. Formation of the granuloma, a hallmark lesion of tuberculosis, allows leukocytes to control infection with Mtb. We hypothesized that the adhesion molecule ICAM‐1 plays a role in the granuloma formation and in the cell to cell communication that takes place at the locus of infection While previous studies in ICAM‐1−/− mice have indicated that ICAM‐1 is required for long‐term control over Mtb infection, the mechanism remains unclear. In this study, ICAM‐1−/− mice infected with Mtb survived similarly to wild type controls with equivalent bacterial burden. Although granuloma formation appeared normal in the absence of ICAM‐1, higher overall lymphocytic infiltrate was observed by H&E staining and flow cytometry. Higher T cell numbers was apparently due to inhibited contraction in the absence of ICAM‐1 following primary Mtb infection. T regulatory cells were also significantly reduced in ICAM‐1−/− mice, which could play a role on T cell contraction. In this study we have both investigated the role of T regulatory cells in controlling T lymphocytes. Results suggest that ICAM‐1 expression may help to control lung pathology by supporting the function of T regulatory cells in the lungs. Future studies will attempt to elucidate the mechanism by which ICAM‐1 affects T regulatory cell recruitment to or retention in the lungs.Funding provided by NIH R01 HL71241

ICAM-1 expression is required for regulatory T cell localization in the lungs of M. tuberculosis infected mice (97.2)

Abstract Mycobacterium tuberculosis (Mtb) is a widespread human pathogen that persists in the lung of latently infected individuals. Control over Mtb infection relies upon migration of leukocytes into the granuloma. We hypothesized that the adhesion molecule ICAM-1 plays a role in the migration, retention and interaction of leukocytes during Mtb infection. While previous studies in ICAM-1−/− mice have indicated that ICAM-1 is required for long-term control over Mtb infection, the mechanism remains unclear. In this study, ICAM-1−/− mice infected with Mtb survived over 10 months post-infection and controlled bacterial burden. Although granuloma formation appeared normal, higher overall cell numbers were observed by H&E staining and flow cytometry. We observed inhibited T cell contraction in the absence of ICAM-1 following primary Mtb infection. T regulatory cells were significantly reduced in ICAM-1−/− mice, which could play a role on T cell contraction. We conclude that ICAM-1 expression helps to control lung pathology by supporting T regulatory cells. Future studies will attempt to elucidate the mechanism by which ICAM-1 affects T regulatory cell recruitment to or retention in the lungs.

TGF-beta1-induced expression of alphaE(CD103)beta7 integrin on Ag-specific tumor-infiltrating T lymphocytes promotes killing of E-cadherin-bearing tumor cells by triggering polarized cytotoxic granule exocytosis (50.22)

Abstract Interaction of intercellular adhesion molecule (ICAM)-1 with lymphocyte function-associated antigen (LFA)-1 enhances target cell-T cell adhesion and thus promotes TCR-mediated killing. In the absence of ICAM-1, frequently lost during tumor cell dissemination, we demonstrate that the interaction of the epithelial cell marker E-cadherin with αE(CD103)/1 _7 integrin, often expressed by tumor-infiltrating T lymphocytes (TIL), plays a major role for an effective cancer cell lysis. Indeed, while tumor-specific CD103+ TIL are able to kill E-cadherin+/ICAM− autologous tumor cells, CD103− PBL-derived counterparts are inefficient. Furthermore, tumor cell killing by TIL is abrogated by anti-CD103 mAb and RNA interference targeting E-cadherin. Confocal microscopy analysis demonstrated that αEβ7 is recruited at the immunological synapse and that its interaction with E-cadherin is essential for cytolytic granule polarization and subsequent exocytosis. Interestingly, pre-incubation of PBL-derived T cells with anti-CD3 mAb and TGF-β1 induced CD103 expression resulting in a dramatic potentiation of anti-tumor effector function. Thus, CD8+/CD103+ tumor-reactive T cells infiltrating epithelial tumors most likely play a major role in anti-cancer CTL response.

The role of cytokines and adhesion molecules in axon degeneration after peripheral nerve axotomy: a study in different knockout mice

The loss of axons and axonal dysfunction has become of outstanding interest with respect to degenerative and inflammatory diseases of the central and peripheral nervous system. In particular in terms of demyelinating diseases such as multiple sclerosis it is important to know the mechanisms which are responsible for the degeneration and destruction of axons. Here we focused on the loss or preservation of axons after induction of Wallerian degeneration in transected mouse sciatic nerves. We examined the distal transected nerve segments of different knockout mice (ICAM-1; TNF-α; iNOS; IL-6) 6 days after axotomy. Despite a distinct number of invading macrophages which phagocytosed most of the myelin and axonal debris, we were able to demonstrate, that animals which are deficient for the cell adhesion molecule ICAM-1 and the cytokine TNF-α showed a significantly higher number of preserved axons within the degenerating distal nerve stump. Since macrophage invasion is known to be impaired in the absence of ICAM-1, these data indicate an essential role of these cells and their secreted factors, namely TNF-α, but not nitric oxide or IL-6 in the destruction of the axonal cytoskeleton in the peripheral nervous system.

ICAM-1 Is Required for Resistance to Herpes Simplex Virus Type 1 but Not Interferon-α1 Transgene Efficacy

The purpose of this study was to determine the role of ICAM-1 in ocular herpes simplex virus type 1 (HSV-1) infection. Wild-type and ICAM-1 knockout mice were assessed for resistance to ocular HSV-1 infection in the presence of naked DNA plasmid vector or plasmid DNA encoding interferon-α1 topically applied to the cornea of the mice. Wild-type mice showed greater resistance to HSV-1 infection compared to ICAM-1 knockout mice as measured by cumulative survival. The absence of ICAM-1 did not affect the efficacy of the interferon-α1 transgene against ocular HSV-1. Both ICAM-1 and wild-type mice treated with the transgene showed a reduction in viral load and antigen expression in the trigeminal ganglion compared to the plasmid vector-treated counterparts. In contrast, the presence of the transgene reduced the number of infiltrating cells into the cornea in comparison to plasmid vector DNA controls in the wild-type mice but not in the ICAM-1 knockout mice. Collectively, these results suggest that the IFN-α1 transgene can restore resistance against HSV-1 infection in ICAM-1-deficient mice.

The Dependence for Leukocyte Function-Associated Antigen-1/ICAM-1 Interactions in T Cell Activation Cannot Be Overcome by Expression of High Density TCR Ligand

The leukocyte-specific integrin, LFA-1, can enhance T cell activation. However, it is unclear whether the binding of LFA-1 to its ligand, ICAM-1, functions through intercellular adhesion alone, resulting in an augmentation of the TCR signal, or involves an additional LFA-1-mediated cellular signal transduction pathway. We have previously shown that naive CD4+ lymph node T cells, isolated from DO11.10 TCR transgenic mice, are activated by increasing doses of exogenous OVA peptide presented by transfectants expressing both class II and ICAM-1, but not by cells expressing class II alone. To determine whether LFA-1/ICAM-1 interactions were simply enhancing the presentation of low concentrations of specific MHC/peptide complexes generated from exogenously added peptide, we transfected cells with class II that is covalently coupled to peptide, alone or in combination with ICAM-1. These cells express 100-fold more specific class II/peptide complexes than can be loaded onto class II-positive cells at maximum concentrations of exogenous peptide. Despite this high density of TCR ligand, activation of naive CD4+ T cells still requires the coexpression of ICAM-1. LFA-1/ICAM-1 interactions are not required for effective conjugate formation and TCR engagement because presentation of class II/peptide complexes in the absence of ICAM-1 does induce up-regulation of CD25 and CD69. Thus, high numbers of engaged TCR cannot compensate for the lack of LFA-1/ICAM-1 interactions in the activation of naive CD4+ T cells.

Urine cytology and the diagnosis of renal allograft rejection. II. Studies using immunostaining.

Urine immunocytology may provide a noninvasive method of investigating the antigens expressed by renal tubular cells. In previous investigations of patients with acute renal allograft rejection (AR), we showed that the adhesion molecule ICAM-1 is expressed by voided tubular cells. The up-regulation of ICAM-1, in turn, may be due to high circulating levels of interferon-gamma and/or TNF-alpha. We investigated the regulation of receptors for these cytokines and found a correlation between their expression and clinical events. For 10 patients who received transplants consecutively, freshly voided aliquots of urine were obtained on each hospital day and on each outpatient visit for a mean of 52.8 +/- 26.2 (SD) days. After cytocentrifugation, the samples were prepared by the avidin-biotin-immunoperoxidase technique in order to detect the presence or absence of ICAM-1, interferon-gamma receptor and TNF-alpha receptor (p 80) on the tubular cells. In nonrejecting patients, the tubular cells expressed the interferon-gamma receptor but not ICAM-1 or the TNF-alpha receptor. In patients with AR, the pattern was different. The tubular cells expressed ICAM-1 and the TNF-alpha receptor but not the interferon-gamma receptor. Urine immunocytochemistry may be useful to demonstrate the expression of cytokine receptors by renal epithelia.

An immunohistochemical study of immunological phenomena in minor salivary glands in patients with Sjögren's syndrome

Using different monoclonal antibodies, we performed an immunofluorescent technique on labial salivary glands in order to investigate the immunological phenomena involved in Sjögren's syndrome (SS). An aberrant expression of HLA-DR molecules was detected on cytoplasm of epithelial labial salivary cells in 9 out of 19 (47%) patients, with SS. No such expression was found in 8 patients without SS or in 3 normal controls. HLA-DQ molecules were demonstrated also in two out of ten SS patients without HLA-DR. A lymphocytic infiltration was not correlated with the expression of class II molecules. T cells bearing gamma delta receptors were not detected. The intracellular adhesion molecules (ICAM-1) and lymphocyte function associated antigen-1 (LFA-1) were not found on epithelial glandular salivary cells of patients and controls. In conclusion, these data suggested that the absence of ICAM-1 and LFA-1 in salivary cells and the absence of infiltrating T cells bearing gamma delta receptors exclude their immunopathogenetic role in SS; moreover, these data demonstrated that the aberrant expression of HLA class II molecules on epithelial salivary cells of patients with SS is not a phenomenon correlated with the lymphocytic infiltration.

The absence of constitutive and induced expression of critical cell-adhesion molecules on human cardiac myocytes. Its role in transplant rejection.

Fetal human cardiac myocytes (FHCM) and a cell line derived from FHCM, termed W1, constitutively express low levels of MHC class I antigens and significant levels of ICAM-1 (CD54), and LFA-3 (CD58) but do not express LFA-1 alpha (CD11a), LFA-1 beta (CD18), GMP-140 (CD62), BB1-B7, VCAM-1, and ELAM-1. In vitro incubation of FHCM or the W-1 cell line for varying periods with varying concentrations of IFN-gamma, TNF-alpha, Poly IC, LPS, IL-alpha, IL-1 beta, PMA, PDBu, and supernatant fluids from Con A-activated PBMC or allogeneic MLR cultures failed to induce cell adhesion molecules (CAMs) or costimulatory molecules that are not constitutively expressed on these cells except for MHC class II antigens. In addition, IFN-gamma, Con A, and MLR supernatant fluids (in order of biological activity) not only induced MHC class II antigens but also markedly increased the mean density of expression per cell of MHC class I and ICAM-1. Analysis of the stability of MHC class I/II molecules using agents like brefeldin-A and Western blot analysis of MHC class II molecules suggest that these ligands are very stably expressed on myocytes. Our previous studies have documented the failure of MHC-expressing FHCM to induce an alloproliferative response. The results of the present studies show that this failure is not secondary to the absence of ICAM-1 or LFA-3 or the presence of unstable MHC molecules but is most likely due to the absence of other CAMs/costimulatory molecules that are critically required for inducing allogeneic activation.