Induction of tolerance in murine autoimmune diabetes by transient blockade of leukocyte function-associated antigen-1/intercellular adhesion molecule-1 pathway

The present study demonstrated that a short-term administration of mAbs against leukocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) at critical periods resulted in complete protection of autoimmune diabetes in non-obese diabetic (NOD) mice. When these mAbs were administered for only 6 days at 2 wk of age, neither diabetes nor insulitis was observed at 30 wk of age. It appears that the tolerance against beta cell Ag(s) was induced by this transient blockade of the LFA-1/ICAM-1 pathway. Protective suppressor activity was not enough to prevent diabetes because co-transfer of splenocytes from female NOD mice, which had received these mAbs at 2 wk of age, resulted in only a short delay of the diabetic onset caused by adoptive transfer of splenocytes from acutely diabetic NOD mice. Transfer of these splenocytes to young NOD mice could not also abrogate the spontaneous diabetes and insulitis. Furthermore, cyclophosphamide treatment could not abrogate the protection. When splenocytes from the treated NOD mice were transferred to NOD-SCID mice, none of the recipient mice developed significant insulitis and subsequent overt diabetes, suggesting the absence or the inactivation of diabetogenic effector T cells. However, splenic T cells from the insulitis-free NOD mice that had received the mAb treatment preserved proliferative responses to both islet cells and 65-kDa glutamic acid decarboxylase (GAD65) in vitro. These results suggest that a unique peripheral tolerance was induced by the transient blockade of the LFA-1/ICAM-1 pathway in an early age of NOD mice.     

Prevention of autoimmune diabetes mellitus in NOD mice by transgenic expression of soluble tumor necrosis factor receptor p55

The non-obese diabetic (NOD) mouse represents a relevant animal model of autoimmunity for insulin-dependent diabetes mellitus. The pathogenic role of tumor necrosis factor (TNF) in insulitis and beta cell destruction observed in these mice remains controversial, since injections of TNF or of anti-TNF antibodies have been reported to exert protection or acceleration of diabetes, depending on the timing of administration. In this study, we demonstrate that, in contrast to the non-transgenic littermates, NOD mice with permanent neutralization of TNF by high blood levels of soluble TNF receptor p55-human FcIgG3-fusion molecules resulting from the expression of a transgene are protected from spontaneous diabetes. They are also protected from accelerated forms of disease caused by transfer of NOD spleen cells or cyclophosphamide injections. This protection is associated with a marked decrease in the severity and incidence of insulitis and in the expression of the adhesion molecules MAdCAM-1 and ICAM-1 on the venules of pancreatic islets. These data suggest a central role for TNF-alpha in the mediation of insulitis and of the subsequent destruction of insulin-secreting beta-cells observed in NOD mice. They may be relevant to cell-mediated autoimmune diseases in general, in which treatment with soluble TNF receptors might be beneficial.     

Spectrum of activity of soluble intercellular adhesion molecule-1 against rhinovirus reference strains and field isolates

The antiviral potency of soluble intercellular adhesion molecule-1 (ICAM-1; the major receptor for human rhinoviruses) was determined for a subset of American Type Culture Collection reference serotypes and field isolates of rhinovirus. The results indicate that soluble ICAM-1 exhibits a broad spectrum of activity against rhinoviruses and that field isolates have a sensitivity indistinguishable from that of laboratory strains.     

Observation of the nuCH Excited Vibrational Levels in the ?1A" State of HCP by IR-UV Double Resonance Spectroscopy

Expression of membrane-bound (mb) and soluble (s) forms of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) induced by tumor necrosis factor-alpha (TNF-alpha) has been measured by enzyme-linked immunosorbent assay in cultured human brain microvessel endothelial cells. Both the mb and the s forms of VCAM-1 and ICAM-1 were upregulated by TNF-alpha; however, the stimulation of the s forms was delayed in time. When piracetam, a neuroprotective drug, was added to the tissue culture medium simultaneously with TNF-alpha, the expression of mbVCAM-1 and ICAM-1 was lowered. Differential upregulation of mb and s forms of adhesion molecules and a novel effect of piracetam have been demonstrated in human brain microvessel endothelial cell cultures.     

Differential expression of ICAM-1 and LFA-1 versus L-selectin and VCAM-1 in autoimmune insulitis of NOD mice and association with both Th1- and Th2-type infiltrates

The infiltration of pancreatic islets by mononuclear cells is the hallmark of the development of insulin dependent diabetes mellitus (IDDM) in the NOD mouse, an animal model for human IDDM. The aim, of this study was to correlate adhesion molecule expression with the degree of islet infiltration and to compare Th1- and Th2-driven islet inflammation. Cryostat sections of NOD mouse pancreata before and after diabetes development were analysed by semiquantitative immunohistochemistry. NOD mouse islets did not show the expression of ICAM-1, LFA-1, L-selectin and VCAM-1 prior to infiltration by mononuclear cells. Furthermore, islets with early stage insulitis (grade 1, periinsular location of small infiltrates) still were devoid of adhesion molecule expression. ICAM-1 and LFA-1 were first demonstrable in islets with strong periinsular infiltrates (insulitis grade 2) while L-selectin and VCAM-1 were only seen in islets with mild or strong intraislet infiltration (grade 3-4). Adhesion molecules were demonstrable in areas of macrophage and T-lymphocyte infiltrates but not in adjacent endocrine islet tissue. Islets of all infiltration stages contained Th2 lymphocytes (positive for IL-4). Substantial numbers of Th1 cells (positive for IFN-gamma, TNF-alpha, IL-2 and/or IL-2 receptor) were observed only after acceleration of diabetes development by a single injection of cyclophosphamide (250 mg/kg i.p.). Interestingly, the adhesion molecule expression pattern in islets with "Th1' versus "Th2 insulitis' was not different. In conclusion, the expression of adhesion molecules in islets during the development of autoimmune diabetes does not precede mononuclear infiltration but probably occurs in response to the activation of initial small infiltrates. ICAM-1 and LFA-1 expression is seen prior to L-selectin and VCAM-1. However, adhesion molecule expression during Th1 versus Th2 cell infiltration is very similar, suggesting similar adhesion molecule requirements of the two Th subsets.     

The role of LFA-1 (CD11a/CD18) cytoplasmic domains in binding to intercellular adhesion molecule-1 (CD54) and in postreceptor cell spreading

We have investigated the role of the cytoplasmic domains of LFA-1 in binding to ICAM-1 and in postadhesion events. Various truncated and chimeric forms of LFA-1 alpha (CD11a) and beta (CD18) chains were generated and transfected into murine fibroblast TNR-2 cells. Transfected fibroblasts expressing wild-type LFA-1 adhered only weakly to ICAM-1 immobilized on plastic, and phorbol ester pretreatment enhanced this adhesion significantly. In contrast, transfected cells expressing LFA-1 lacking both the alpha and the beta cytoplasmic domains, the beta cytoplasmic domain alone, or GPI-anchored LFA-1 adhered to immobilized ICAM-1 without prior activation. Truncation of the alpha cytoplasmic domain alone resulted in much reduced cell adhesion which could be only weakly upregulated by PMA. The presence of manganese dramatically enhanced the binding to ICAM-1 of LFA-1 lacking the alpha cytoplasmic domain or both cytoplasmic domains, whereas it had relatively little effect on wild-type LFA-1 or the mutant lacking the beta cytoplasmic domain. Soluble LFA-1, generated by phosphatidylinositol-specific phospholipase-C treatment of GPI-anchored LFA-1, was capable of binding ICAM-1+ cells. Although doubly truncated or GPI-anchored LFA-1 mediated cell adhesion to immobilized ICAM-1, cells expressing these mutants, as well as those expressing individual alpha and beta chain truncations, failed to spread out following this adhesion, whereas the wild-type transfectants did so readily. Manganese had no effect on cell spreading. Fluorescent staining of these cells indicated no significant variation in the distribution of LFA-1 on the cell surface. From these results we conclude that (1) cells expressing LFA-1 lacking both the alpha and the beta cytoplasmic domains adhere to ICAM-1 without prior stimulation, indicating the importance of LFA-1 cytoplasmic domains in inside-out signaling, (2) truncation of the alpha cytoplasmic domain alone inhibits cell adhesion by making LFA-1 nonresponsive to inside-out signaling, and (3) both cytoplasmic domains are required for cell spreading following adhesion to immobilized ICAM-1.     

Improved survival and amelioration of nephrotoxic nephritis in intercellular adhesion molecule-1 knockout mice

Intercellular adhesion molecule-1 (ICAM-1) expression is upregulated in nephrotoxic nephritis, a model of human rapidly progressive glomerulonephritis. To evaluate the pathogenetic relevance of ICAM-1 in this model, nephrotoxic nephritis was induced in ICAM-1 knockout mice and genetic controls. Mice were preimmunized with rabbit IgG in complete Freund's adjuvant. Seven days later they received rabbit anti-mouse glomerular basement membrane IgG. The early humoral immune responses (levels of circulating mouse anti-rabbit IgG, glomerular deposition of rabbit and mouse IgG and mouse C3c) were not altered in ICAM-1 knockout mice. During 28 d of follow-up, 3 of 19 control nephritic mice and 0 of 16 ICAM-1 knockout mice died. Proteinuria was high in nephritic control mice (means 10 to 12 mg/24 h at all time points investigated) and significantly reduced in nephritic ICAM-1 knockout mice (means <4.4 mg). Mean serum creatinine rose from 29 micromol/L at day -7 to 48 micromol/L (day 28) in nephritic control mice. This increase in serum creatinine was significantly lower in ICAM-1 knockout mice: 27 (day -7) and 36 micromol/L (day 28). Histologic analysis at day 28 revealed that ICAM-1 deficiency in nephrotoxic nephritis mice led to significantly reduced glomerular crescent formation (2+/-3% in ICAM-1 knockout mice versus 13+/-8% in nephritic controls) and tubulointerstitial injury (score 0.4+/-0.4 versus 2.0+/-1.1). By immunohistochemistry, ICAM-1 deficiency in nephritic mice led to significantly reduced (peri-)glomerular and/or interstitial macrophage influx, alpha-smooth muscle actin expression, and type IV collagen accumulation. These data indicate that ICAM-1 is a central mediator of glomerular and tubulointerstitial injury in murine nephrotoxic nephritis.     

Sequence analysis of the coat protein and 3''-noncoding region for Korean and other strains of sweet potato feathery mottle virus

A murine model of asthma is described in which we examined the role of intercellular adhesion molecule-1 (ICAM-1) in the pathogenesis of airway reactivity, pulmonary eosinophilia, and inflammation. We sensitized wild-type control [C57BL/6J, (+/+)] and ICAM-1 knockout [C57BL/6J-ICAM-1, (-/-)] mice to ovalbumin (OVA), and challenged them with OVA delivered by aerosol (OVA-OVA) to induce a phenotype consistent with an asthmatic response. Bronchial responsiveness to methacholine and counts of cell numbers and measurements of eosinophil content and cytokine levels in bronchoalveolar lavage fluid (BALF) were significantly attenuated in ICAM-1(-/-) mice as compared with (+/+) mice. We also showed that the absence of ICAM-1 had no significant affects on the production of serum IgE antibody, but did have an effect on ex vivo lymphocyte proliferation. Additionally, immunohistochemistry: (1) revealed increased staining for vascular cell adhesion molecule-1 (VCAM-1) after antigen challenge in the ICAM-1(-/-) mice but not in the ICAM-1(+/+) controls; and (2) confirmed the presence of alternatively spliced forms of ICAM-1 in the lungs of ICAM-1(-/-) mice. Thus, despite the availability of alternate adhesion pathways in ICAM-1(-/-) mice, the absence of ICAM-1 prevented eosinophils from entering the airways. In summary, we found that the ICAM-1 knockout mice exhibited a significantly inhibited response to aerosol antigen challenge for most of the parameters examined, and conclude that ICAM-1 is an important ligand mediating T-cell proliferation in response to antigen, eosinophil migration into the airways, and the development of airway hyperreactivity (AHR) in allergen-sensitized and -challenged mice.     

Proteins spontaneously released by rat insulinoma (RIN) cells are anchored on cell membrane by a glycosyl-phosphatidyl-inositol link and inhibit increased RIN cell adhesion of lymphocytes from type 1 diabetic patients and non-obese diabetic mice in vitro

Our group previously reported an assay for the study of lymphocyte adhesion to insulin-producing cells in which xenogeneic rat insulinoma (RIN) cells were used as targets. The present study found an increased number of RIN-cytoadherent lymphocytes in 63 patients with Type 1 diabetes compared with 150 control subjects and in 211 NOD mice compared with 104 BALB/c mice (p < 0.001). Proteins concentrated from spontaneous RIN cell culture supernatants inhibited increased RIN-adhesion of NOD splenocytes or lymphocytes from diabetic patients (p < 0.001). In addition, increased RIN binding was dose-dependently abolished by RIN membrane extracts. The fact that RIN binding was inhibited by proteins from both membrane and the culture supernatant from RIN cells suggests that soluble inhibitory proteins were spontaneously released into the supernatant from a hydrophobic membrane-bound form. This tended to be confirmed since inhibition obtained with both preparations involved a 55-75 kDa HPLC protein fraction. The possibility that the membrane form of the inhibitory protein was anchored by a glycosylphosphatidylinositol (GPI) tail was evaluated. When RIN cells were treated with PI-PLC, their ability to bind lymphocytes from diabetic patients or NOD splenocytes decreased (p < 0.001) to control levels. Co-incubation with the 55-75 kDa fraction of proteins cleaved from RIN cells by PI-PLC also lowered the number of RIN-adherent NOD splenocytes to control levels. SDS-PAGE and IEF analyses of the 55-75 kDa inhibitory fraction from RIN cell supernatant revealed a major band with Mr 66 kDa and PI5.4, which may correspond to a protein with similar characteristics noted on 2-D electrophoresis of proteins cleaved from RIN cells by PI-PLC. Specific labelling of GPI moieties with 3H-ethanolamine, 3H-glucosamine, or 14C-glucosamine, as well as conversion of the hydrophobic Triton-X114 solubilised form into a hydrophilic form after PI-PLC treatment, confirmed the presence of a GPI anchor in this approximately 66 kDa RIN protein, which could thus be the molecule inhibiting adhesion in the system. Our data suggest that GPI-proteins from insulin-producing cells may influence the immune system both in their membrane-anchored and soluble forms. When considering the binding model, in which beta cells were tumoral and xenogeneic to diabetic lymphocytes, this potential influence of GPI-proteins suggests possible implications in situations of lymphocyte-beta cell interaction, i.e. anti-beta cell autoimmunity, immune reaction against insulinomas, and reaction against islet xenografts.     

Paracrine actions of insulin-like growth factors and IGF binding protein-1 in non-pregnant human endometrium and at the decidual-trophoblast interface

The A4VAR is a variant antigen expressed by a clonal line that binds CD36 and intercellular adhesion molecule-1, ICAM-1. We have cloned and sequenced the extracellular domain coded by the A4var gene. To probe the relationship between A4var expression and parasite adhesion to ICAM-1, var mRNA and protein expression were analyzed in an enriched population of A4 parasites that displayed higher ICAM-1 binding. By Northern analyses, A4var was the predominant var message and antisera raised against a recombinant A4VAR protein reacted with the majority of infected erythrocytes, reinforcing previous conclusions that A4VAR binds ICAM-1. A4VAR contains five Duffy-binding like (DBL) domains, and two cysteine-rich interdomain regions (CIDR) domains. DBL and CIDR domains from A4VAR were expressed in mammalian cells to determine which regions mediate binding to CD36 and ICAM-1. Using several different binding assays, the A4VAR CIDR1 was the only domain found to bind CD36. In contrast, the same assays were unable to identify the ICAM-1 binding domain in A4VAR. This is the first time that each of the DBL and CIDR domains from a Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) have been systematically expressed and tested for binding. These results confirm that CIDR1 is sufficient to bind CD36 without any apparent contribution from other domains.     

Release of soluble intercellular adhesion molecule 1 into bile and serum in murine endotoxin shock

Neutrophil-induced liver injury during endotoxemia is dependent on the adhesion molecules Mac-1 (CD11b/CD18) on neutrophils and its counterreceptor on endothelial cells and hepatocytes, intercellular adhesion molecule 1 (ICAM-1). To investigate a potential release of a soluble form of ICAM-1 (sICAM-1), animals received 100 micrograms/kg Salmonella abortus equi endotoxin alone or in combination with 700 mg/kg galactosamine. In endotoxin-sensitive mice (C3Heb/FeJ), injection of endotoxin did not cause liver injury but induced a time-dependent increase of sICAM-1 in serum (300%) and in bile (615%) without affecting bile flow. In galactosamine/endotoxin-treated animals, which developed liver injury, the increase in both compartments was only 97% and 104%, respectively. In either case, the increase in sICAM-1 concentrations paralleled the enhanced ICAM-1 expression in the liver. The endotoxin-resistant strain (C3H/HeJ) did not show elevated sICAM-1 levels in serum or bile after endotoxin administration. In contrast, the intravenous injection of murine tumor necrosis factor alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha) or IL-1 beta (13-23 micrograms/kg) into endotoxin-resistant mice induced a 225% to 364% increase in serum sICAM-1 and a 370% elevation of the biliary efflux of sICAM-1, again independent of changes in bile flow. These data indicate that cytokines are major inducers of sICAM-1 formation during endotoxemia in vivo. The described experimental model can be used to investigate the role of sICAM-1 in the pathophysiology of inflammatory liver disease.     

Mucosal addressin is required for the development of diabetes in nonobese diabetic mice

Immune responses are best initiated in the environment of lymphoid tissues wherein circulating lymphocytes enter by interacting with endothelial adhesion molecules. In type 1 diabetes, immune responses against pancreatic islets develop, but the environment in which this occurs remains unidentified. To determine whether lymphocyte homing to lymphoid organs is involved in the pathogenesis of diabetes in nonobese diabetic (NOD) mice, we blocked the function of the mucosal addressin cell adhesion molecule-1 (MAdCAM-1), which is a vascular addressin-mediating lymphocyte homing into mucosal lymphoid tissues, in these mice. While ineffective if started later, a blockade started at 3 wk of age reduced the incidence of diabetes from 50% to 9% (p < 0.01). This finding is associated with Peyer's patch atrophy, a marked decrease of naive (CD44(low) CD45RB(high)) T lymphocytes, and a reduction in the relative numbers of memory (CD44(high)) T lymphocytes in the spleen. The potential of these spleen cells to cause diabetes was diminished. Anti-MAdCAM-1 treatment also inhibited both lymphocyte entry into the pancreas and diabetes development in NOD/SCID recipients after the transfer of lymphocytes derived from the mesenteric lymph nodes of young, but not of diabetic, NOD donors. Therefore, MAdCAM-1 may be required during two distinct steps in an early phase of diabetes development: for the entry of naive lymphocytes into the lymphoid tissues in which diabetes-causing lymphocytes are originally primed, and for the subsequent homing of these lymphocytes into the pancreas. The role of MAdCAM-1 as a mucosal vascular addressin suggests that mucosal lymphoid tissues are involved in the initiation of pathologic immune responses in NOD mice.     

The roles of adhesion molecules, cytokines and chemokines in allergic inflammation

Recently, adhesion molecules, as well as eosinophils, have been found to play an important role in the inflammatory processes in allergic disease. We demonstrated here as below. Characteristics of adhesion molecules expression on eosinophils in asthma, namely, high-intensity expression of adhesion molecules. Induction of adhesion molecule expression by PAF and RANTES and in addition induction by the supernatant of mononuclear cells from mite-allergic asthmatic patients stimulated with mite-allergen as well as with a combination of the recombinant IL-3, GM-CSF and IL-5. Elevated soluble ICAM-1 in bronchial asthma. Moreover, the presence of a large variety of membrane receptors and the identification of cytotoxic molecules (mainly granule basic proteins) have indicated that eosinophils should be considered as effector cells. We therefore investigated the possible release of granule proteins in response to signaling from ICAM-1 and its ligands. The concentrations of eosinophil cationic protein and eosinophil-derived neurotoxin in supernatants of eosinophils were significantly greater (p < 0.05) in the presence of recombinant soluble ICAM-1 than without it. These results suggest that signaling from ICAM-1 and its ligands might induce eosinophil activation and might be involved in degranulation of eosinophil granule proteins. In addition, reactive oxygen species generated by eosinophils have also been considered capable of causing airway injury at the inflamed focus. We examined the effect of recombinant soluble ICAM-1 and its ligands on eosinophil-induced radical oxygen products. Recombinant soluble ICAM-1 augmented eosinophil oxidative metabolism. It was concluded that signaling via adhesion molecules might play an important role in the pathogenesis of allergic inflammation through activation of eosinophils, such as through an increase in oxidative metabolism or degranulation of eosinophil granule proteins.     

Anti-adhesion molecule therapy in Theiler's murine encephalomyelitis virus-induced demyelinating disease

We examined the role of leukocyte function-associated antigen (LFA)-1 and its counter-receptor intercellular adhesion molecule (ICAM)-1, one of the most important pairs of adhesion molecules, in the development of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD). Immunohistochemical study showed hyper-expression of ICAM-1 on vascular endothelial cells and expression of LFA-1 on mononuclear infiltrating cells in the spinal cords of TMEV-infected mice. Treatment with mAb to ICAM-1 and/or LFA-1 molecules resulted in significant suppression of the development of demyelinating disease, both clinically and histologically, with down-regulation in the CNS of the respective adhesion molecules after treatment. In mice treated with these mAb, the specific delayed-type hypersensitivity and T cell proliferative responses for TMEV were decreased. The production of tumor necrosis factor-alpha and IFN-gamma in spleen cells was also decreased, but IL-4 production remained unchanged. These data suggest that ICAM-1/LFA-1 interaction is critically involved in the pathogenesis of TMEV-IDD and that antibodies to these adhesion molecules could be a novel therapeutic approach to the treatment of demyelinating diseases such as human multiple sclerosis.     

Intercellular adhesion molecule 1 is the major adhesion molecule expressed during schistosome granuloma formation

Endothelial cell adhesion molecules play a key role in inflammation by initiating leukocyte trafficking. One of the most complex inflammatory responses is the formation of a cellular granuloma. Expression of adhesion molecules during granuloma formation was investigated by using the murine host reaction to schistosome parasite eggs deposited in the liver as a model. By both immunohistochemistry and lymphocyte adhesion assays, the predominant interaction identified was between intercellular adhesion molecule 1 (ICAM-1) and its cognate integrin, leukocyte functional antigen 1 (LFA-1). ICAM-1 expression on sinusoidal endothelium was induced when eggs were first deposited in the liver, peaked in parallel with granuloma size, and was downregulated with modulation of the granuloma. Polyacrylamide beads coated with soluble parasite egg antigens could induce ICAM-1 expression on endothelial cells in vitro only in the presence of tumor necrosis factor alpha, a cytokine previously shown to be key to granuloma formation. A role for ICAM-1 in recruiting lymphocytes to the hepatic granuloma was also supported by the observation that lymphocytes preincubated with anti-LFA-1 antibody did not bind to granulomas in tissue sections. While ICAM-1 is the predominant adhesion molecule in schistosome egg granuloma formation in wild-type mice, when the ICAM-1 gene is knocked out, vascular cell adhesion molecule 1 is upregulated and granuloma formation is preserved.     

Influence of bacterial endotoxin on radiation-induced activation of human endothelial cells in vitro and in vivo: protective role of IL-10

Previous work from our group has contributed to demonstrate the role of conditioning related release of proinflammatory cytokines in induction of acute graft-versus-host disease (GVHD) following allogeneic bone marrow transplantation (BMT). In the present report we show that ionizing radiation (IR) in a clinical relevant dose upregulates intercellular adhesion molecule 1 (ICAM-1) on cultured human microvascular endothelial cells (HMEC). Bacterial endotoxin (lipopolysaccharide, LPS) in a concentration corresponding to serum levels seen during clinical endotoxemia, is capable of further enhancing ICAM-1 expression on irradiated cells. Adhesion assays with freshly isolated peripheral blood mononuclear cells (PBMC) revealed that increased ICAM-1 on IR-treated endothelial cells led to an increased adhesion of PBMC. Again, this effect could be superinduced by LPS. Recombinant human interleukin 10 (IL-10), an antagonistic cytokine known to function as an LPS antagonist, was able to counteract the LPS-mediated enhancement of IR-triggered ICAM-1 induction and PBMC adhesion. In contrast, IL-10 could not inhibit irradiation caused effects. IL-10 seemed to interfere with the translocation of preformed intracellular ICAM-1 to the cell membrane. To investigate whether this superinductive function of IR and LPS on endothelial cells is of clinical relevance, mice were treated with total body irradiation (TBI) and inoculated with a single dose of LPS. Immunohistochemical analyses of murine tissues demonstrated that LPS superinduces IR-triggered ICAM-1 also in vivo. These findings may be of clinical importance as they suggest that the endothelium is activated after radiotherapy or TBI used for conditioning in bone marrow transplantation. The activated endothelium in turn may facilitate the accumulation of effector cells at sites of inflammation.     

Factors influencing the effects of murine cytomegalovirus on the pancreas

BACKGROUND: As human cytomegalovirus (HCMV) infections are implicated in insulin-dependent diabetes mellitus (IDDM), the effects of murine (M)CMV infection of inbred mice on the pancreas are of interest. RESULTS: Inflammation and periacinar oedema peaked on day 3 and were replaced by a focal inflammation, but infected cells were rare. The islets were spared in C57BL mice. Insulitis normally seen in non-obese diabetic (NOD) mice was accelerated, but infected NOD mice did not become glycosuric. Isotypes of total and autoreactive antibodies suggested a shift to a Th 1 response (IgG2a) in all MCMV-infected mice. MCMV-induced pancreatitis was not affected by MHC genes but was similar or less severe in BALB/c mice. As these lack the Cmv1 gene, which provides a protective natural killer (NK) cell response in C57BL congenic mice, the C57BL background may carry a pancreatitis susceptibility gene able to counter NK-mediated restriction of viral replication. Consistently, congenic mice expressing Cmvl on a BALB/c background did not display pancreatitis, unless depleted of NK cells. In vivo treatment with soluble cytokine receptors suggested that interleukin 1 (IL-1) and/or tumour necrosis factor alpha contribute to acinar necrosis in C57BL mice.     

IL-1 receptor antagonist inhibits recurrence of disease after syngeneic pancreatic islet transplantation to spontaneously diabetic non-obese diabetic (NOD) mice

The effect of an IL-1 receptor antagonist on recurrence of hyperglycaemia after syngeneic pancreatic islet transplantation to spontaneously diabetic female NOD mice was investigated. The transplanted animals were treated with either the receptor antagonist (8.0 mg/kg body weight per day for 12-14 days) or PBS, delivered by subcutaneously implanted osmotic pumps. In the control animals, a transient normoglycaemia was achieved, but hyperglycaemia was generally observed 6 days after islet transplantation. Administration of IL-1 receptor antagonist had a clear protective effect against recurrence of hyperglycaemia until day 14, but after cessation of drug delivery hyperglycaemia re-appeared. The results indicate that continuous administration of the IL-1 receptor antagonist can prevent recurrence of the diabetogenic process in NOD mice. IL-1 receptor antagonist may therefore become a useful adjuvant immunomodulating therapy after human islet transplantation in insulin-dependent diabetes mellitus.     

Immunosuppression preventing concordant xenogeneic islet graft rejection is not sufficient to prevent recurrence of autoimmune diabetes in nonobese diabetic mice

BACKGROUND: We and others have reported previously that the immunosuppressant, leflunomide (Lef), can prevent allogeneic and xenogeneic islet graft rejection in streptozocin (STZ)-induced diabetic animals. However, whether Lef required to prevent islet graft rejection is sufficient to prevent the recurrence of autoimmune diabetes has not been addressed. METHODS: The effect of Lef on concordant xenogeneic islet graft in STZ-induced diabetic mice and autoimmune nonobese diabetic (NOD) mice were studied. Then, whether Lef prevents the onset of spontaneous diabetes in young NOD mice and the recurrence of diabetes after major histocompatibility complex (MHC)-matched islet transplantation in diabetic NOD mice were investigated. RESULTS: In STZ-induced diabetic BALB/c mice, Lef treatment significantly prolonged rat islet graft survival. However, Lef could not significantly prolong rat islet graft survival in autoimmune diabetic NOD mice. For prevention studies, treatment with Lef at 30 mg/ kg/day from 4 weeks to 20 weeks of age significantly reduced the incidence of spontaneous diabetes in NOD mice. However, when the NOD mice were treated from 8 to 24 weeks of age, the incidence of spontaneous diabetes was not significantly reduced as compared to the incidence of diabetes in the untreated female NOD mice at 28 weeks of age. Finally, in the MHC-matched islet transplant model, Lef could not significantly prolong MHC-matched nonobese diabetes-resistant mice islet graft survival in NOD mice. CONCLUSIONS: Lef preventing concordant xenogeneic islet graft rejection is not sufficient to prevent the recurrence of autoimmune diabetes in NOD mice. We believe that controlling autoimmunity after islet transplantation will lead the way to promote successful clinical islet transplantation in the future.