Soluble forms of intercellular adhesion molecule-1 inhibit insulitis and onset of autoimmune diabetes

Islet beta-cells and intercellular adhesion molecule-1 (ICAM-1): Integrating immune responses that influence autoimmunity and graft rejection

Type 1 diabetes (T1D) develops due to autoimmune targeting of the pancreatic islet β-cells. Clinical symptoms arise from reduced insulin in circulation. The molecular events and interactions between discrete immune cell populations, infiltration of such leukocytes into pancreatic and islet tissue, and selective targeting of the islet β-cells during autoimmunity and graft rejection are not entirely understood. One protein central to antigen presentation, priming of immune cells, trafficking of leukocytes, and vital for leukocyte effector function is the intercellular adhesion molecule-1 (ICAM-1). The gene encoding ICAM-1 is transcriptionally regulated and rapidly responsive (i.e., within hours) to pro-inflammatory cytokines. ICAM-1 is a transmembrane protein that can be glycosylated; its presence on the cell surface provides co-stimulatory functions for immune cell activation and stabilization of cell-cell contacts. ICAM-1 interacts with the β2-integrins, CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1), which are present on discrete immune cell populations. A whole-body ICAM-1 deletion protects NOD mice from diabetes onset, strongly implicating this protein in autoimmune responses. Since several different cell types express ICAM-1, its biology is fundamentally essential for various physiological and pathological outcomes. Herein, we review the role of ICAM-1 during both autoimmunity and islet graft rejection to understand the mechanism(s) leading to islet β-cell death and dysfunction that results in insufficient circulating quantities of insulin to control glucose homeostasis.

Altered levels of immune cell adhesion molecules are associated with memory impairment in schizophrenia and healthy controls

Increased cytokines and increased intercellular adhesion molecule-1 (ICAM1) found in the schizophrenia prefrontal cortex and in the blood may relate to cognitive deficits. Endothelial ICAM1 regulates immune cell trafficking into the brain by binding to integrins located on the surface of leukocytes. Whether the circulating levels of the main ICAM1 adhesion partners, lymphocyte-function associated antigen-1 (LFA1) and complement receptor 3 (CR3), both integrins, are altered in schizophrenia is unknown. Gene expressions of ICAM1, LFA1 and CR3 were measured in leukocytes from 86 schizophrenia patients and 77 controls. Participants were also administered cognitive testing to determine the extent to which cognitive ability was related to molecular measures of leukocyte adhesion. This cohort was previously stratified into inflammatory subgroups based on circulating cytokine mRNAs; thus, gene expressions were analysed by diagnosis and by inflammatory subgroups. Previously measured plasma ICAM1 protein was elevated in "high inflammation" schizophrenia compared to both "high" and "low inflammation" controls while ICAM1 mRNA was unchanged in leukocytes. LFA1 mRNA was decreased and CR3 mRNA was increased in leukocytes from people with schizophrenia compared to controls. LFA1 mRNA levels were positively correlated with working memory and elevated soluble ICAM1 was negatively correlated with verbal memory in schizophrenia. Altogether, some of the cognitive deficits in schizophrenia may be associated with altered expression of molecules that regulate immune cell trafficking.

The systemic immune network in recent onset type 1 diabetes: central role of interleukin-1 receptor antagonist (DIATOR Trial)

Background

The hypothesis was tested that the systemic immune milieu in recent-onset type 1 diabetes is associated with residual beta cell function and other metabolic patient characteristics.

Methods and Findings

All patients (n = 89, 40% female) of the Diabetes and Atorvastatin (DIATOR) Trial were analyzed at recruitment, i.e. prior to receiving the study medication. Inclusion criteria were insulin dependent diabetes for 2 weeks to 3 months, age range 18–39 years, and islet cell autoantibodies. Blood samples were analyzed for 14 immune mediators by standard methods. Concentrations of all mediators correlated with at least one other mediator (p<0.05, Spearman correlation) giving rise to a network. Interleukin 1 receptor antagonist (IL1-RA) held a central position and was associated with both pro- and anti-inflammatory mediators. Further central elements were the pro-inflammatory mediators CRP and IL-6, the soluble adhesion molecules sICAM-1 and E-selectin, and MCP-4 which held a central position in the chemokine network. The two Th1-associated mediators IFNγ and IP-10 remained outside the network but correlated with each other. All correlations were positive (r = 0.25–0.72), i.e., high levels of pro-inflammatory mediators were accompanied by increased levels of anti-inflammatory mediators. IL-1RA was the only mediator associated with fasting and liquid mixed meal stimulated C-peptide concentrations (r = 0.31 and 0.24, p = 0.003 and 0.025, after adjustment for age, sex, BMI). There were associations between the immune mediator network and BMI (IL-1RA, CRP, IL-6, MCP-4, MIP-1ß) but few or no associations with HbA1c, insulin dose, lipid parameters, age or sex.

Conclusions

In patients with recent onset type 1 diabetes, systemic acute phase proteins, cytokines, chemokines and soluble adhesion molecules form a network. Among the few central elements IL-1RA has a dominant role. IL-1RA is associated with all other groups of mediators and is the only mediator which correlates (positively) with residual beta cell function.

Trial registration

ClinicalTrials.gov registration number: NCT00974740

Elimination of T cell reactivity to pancreatic β cells and partial preservation of β cell activity by peptide blockade of LFA-1:ICAM-1 interaction in the NOD mouse model

In insulin dependent diabetes mellitus (T1D), self-reactive T cells infiltrate pancreatic islets and induce beta cell destruction and dysregulation of blood glucose. A goal is to control only the self-reactive T cells, leaving the remainder of the T cell population free to protect the host. One approach is blockade of the second signal for T cell activation while allowing the first (antigen-specific) signal to occur. This work proposes that small peptides that block interaction of second signals delivered through the counter receptors LFA-1:ICAM-1 will induce attacking T cells (receiving the antigen signal) to become anergic or undergo apoptosis. In NOD mice, the peptides eliminated T cell reactivity against pancreatic antigens and reduced cellular infiltration into islets, which retained stronger density of insulin staining at five weeks after cessation of therapy. In in vitro studies the peptides induced nonresponsiveness during activation of T cells from mice and from human peripheral blood.

Effect of soluble ICAM-1 on a Sjögren's syndrome-like phenotype in NOD mice is disease stage dependent

Introduction

Intercellular adhesion molecule-1 (ICAM-1) is involved in migration and co-stimulation of T and B cells. Membrane bound ICAM-1 is over expressed in the salivary glands (SG) of Sjögren's syndrome (SS) patients and has therefore been proposed as a potential therapeutic target. To test the utility of ICAM-1 as a therapeutic target, we used local gene therapy in Non Obese Diabetic (NOD) mice to express soluble (s)ICAM-1 to compete with membrane bound ICAM-1 for binding with its receptor. Therapy was given prior to and just after the influx of immune cells into the SG.

Methods

A recombinant serotype 2 adeno associated virus (rAAV2) encoding ICAM-1/Fc was constructed and its efficacy tested in the female NOD mice after retrograde instillation in SG at eight (early treatment) and ten (late treatment) weeks of age. SG inflammation was evaluated by focus score and immunohistochemical quantification of infiltrating cell types. Serum and SG tissue were analyzed for immunoglobulins (Ig).

Results

Early treatment with ICAM-1/Fc resulted in decreased average number of inflammatory foci without changes in T and B cell composition. In contrast, late treated mice did not show any change in focus scores, but immunohistochemical staining showed an increase in the overall number of CD4+ and CD8+ T cells. Moreover, early treated mice showed decreased IgM within the SGs, whereas late treated mice had increased IgM levels, and on average higher IgG and IgA.

Conclusions

Blocking the ICAM-1/LFA-1 interaction with sICAM-1/Fc may result in worsening of a SS like phenotype when infiltrates have already formed within the SG. As a treatment for human SS, caution should be taken targeting the ICAM-1 axis since most patients are diagnosed when inflammation is clearly present within the SG.

Residual beta cell function in newly diagnosed type 1 diabetes after treatment with atorvastatin: the Randomized DIATOR Trial

Background

Recent evidence suggests that the lipid-lowering agent atorvastatin is also a potent immunomodulator. The aim of this study was to investigate the possible effect of atorvastatin on the decline of residual beta cell function in recent-onset type 1 diabetes.

Methods and Findings

The randomised placebo-controlled Diabetes and Atorvastatin (DIATOR) Trial included 89 patients with newly diagnosed type 1 diabetes and islet autoantibodies (mean age 30 years, 40% females), in 12 centres in Germany. Patients received placebo or 80 mg/d atorvastatin for 18 months. As primary outcome stimulated serum C-peptide levels were determined 90 min after a standardized liquid mixed meal. An intent-to-treat analysis was performed. Fasting and stimulated C-peptide levels were not significantly different between groups at 18 months. However, median fasting serum C-peptide levels dropped from baseline to 12 and 18 months in the placebo group (from 0. 34 to 0.23 and 0.20 nmol/l, p<0.001) versus a nonsignificant decline in the atorvastatin group (from 0.34 to 0.27 and 0.30 nmol/l, ns). Median stimulated C-peptide concentrations declined between baseline and 12 months (placebo from 0.89 to 0.71 nmol/l, atorvastatin from 0.88 to 0.73 nmol/l, p<0.01 each) followed by a major loss by month 18 in the placebo group (to 0.48 nmol/l, p = 0.047) but not in the atorvastatin group (to 0.71 nmol/l, ns). Median levels of total cholesterol and C-reactive protein decreased in the atorvastatin group only (p<0.001 and p = 0.04). Metabolic control was similar between groups.

Conclusions

Atorvastatin treatment did not significantly preserve beta cell function although there may have been a slower decline of beta-cell function which merits further study.

Trial Registration

ClinicalTrials.gov NCT00974740

Novel association of ABO histo-blood group antigen with soluble ICAM-1: results of a genome-wide association study of 6,578 women

While circulating levels of soluble Intercellular Adhesion Molecule 1 (sICAM-1) have been associated with diverse conditions including myocardial infarction, stroke, malaria, and diabetes, comprehensive analysis of the common genetic determinants of sICAM-1 is not available. In a genome-wide association study conducted among 6,578 participants in the Women's Genome Health Study, we find that three SNPs at the ICAM1 (19p13.2) locus (rs1799969, rs5498 and rs281437) are non-redundantly associated with plasma sICAM-1 concentrations at a genome-wide significance level (P<5×10⁻⁸), thus extending prior results from linkage and candidate gene studies. We also find that a single SNP (rs507666, P = 5.1×10⁻²⁹) at the ABO (9q34.2) locus is highly correlated with sICAM-1 concentrations. The novel association at the ABO locus provides evidence for a previously unknown regulatory role of histo-blood group antigens in inflammatory adhesion processes.

Soluble Intercellular Adhesion Molecule 1 (sICAM-1) is an inflammatory marker that has been associated with several common diseases such as diabetes, heart disease, stroke, and malaria. While it is known that blood concentrations of sICAM-1 are at least partially genetically determined, our current knowledge of which genes mediate this effect is limited. Taking advantage of new technologies allowing us to interrogate genetic variation on a whole genome basis, we found that a variation in the ABO gene is an important determinant of sICAM-1 blood concentrations. Since the ABO gene is responsible for the ABO blood groups, this discovery sheds light on a new role for blood groups and offers novel mechanisms to explain the association between sICAM-1 blood concentrations and various common diseases.

ICAM-1 cross-linking stimulates endothelial glutathione synthesis

What mechanisms regulate endothelial glutathione (GSH) during inflammation? Addressing this question is critical in understanding mechanisms leading to endothelial dysfunction and cardiovascular disease. Herein, the authors show data that support the hypothesis that the intercellular cell adhesion molecule-1 (ICAM-1) regulates GSH. Ligating either constitutive or induced ICAM-1 on the endothelial surface, or exposing endothelial cells to soluble ICAM-1, increases GSH concentrations. ICAM-1 is important in mediating leukocyte adhesion and modulates endothelial signaling pathways important in controlling transmigration. The present data underscore a novel function for ICAM-1 in modulating GSH metabolism and raise the hypothesis that this adhesion molecule controls endothelial redox status under basal and inflammatory conditions.

Genetic influences of the intercellular adhesion molecule 1 (ICAM-1) gene polymorphisms in development of Type 1 diabetes and diabetic nephropathy

AIM

The intercellular adhesion molecule-1 (ICAM-1) gene is located on chromosome 19p13, which is linked to Type 1 diabetes (T1D). ICAM-1 expression is related to development of T1D and diabetic nephropathy. The present study aims to evaluate the genetic influence of ICAM-1 gene polymorphisms on the development of T1D and diabetic nephropathy.

METHODS

Five valid single nucleotide polymorphisms (SNPs) were genotyped in 432 T1D patients (196 patients had diabetic nephropathy) and 187 non-diabetic control subjects by using dynamic allele-specific hybridization (DASH) and pyrosequencing.

RESULTS

SNPs rs281432(C/G) and rs5498 E469K(A/G) had high heterozygous indexes. They were significantly associated with T1D [P = 0.026, OR = 1.644 (95% CI 1.138-2.376) and P < 0.001, OR = 2.456 (1.588-3.8)]. Frequencies of the C allele in SNP rs281432(C/G) and the A allele in SNP rs5498 E469K(A/G) increased stepwise from non-diabetic control subjects to T1D patients without diabetic nephropathy and T1D patients with diabetic nephropathy. Further analysis for these two SNPs indicated that T1D patients had increased frequency of the common haplotype C-A, in comparison with non-diabetic control subjects (38.1 vs. 32.1%, P = 0.035).

CONCLUSION

The present study provided evidence that SNPs rs281432(C/G) and rs5498 E469K(A/G) in the ICAM-1 gene confer susceptibility to the development of T1D and might also be associated with diabetic nephropathy in Swedish Caucasians.

Soluble adhesion molecules in young children with signs of beta-cell autoimmunity--prospective follow-up from birth

BACKGROUND

This study aimed at evaluating the relationship between the circulating concentrations of soluble intercellular adhesion molecule-1 (sICAM-1) and sL-selectin and the appearance of beta-cell autoimmunity, and at assessing whether these molecules could assist in the identification of environmental factors implicated in the immune process damaging the pancreatic beta-cells.

METHODS

Serum levels of soluble adhesion molecules were measured with enzyme-linked immunosorbent assays over the first 2 years of life in 65 children seroconverting to positivity for autoantibodies and 65 control children, all with HLA-conferred susceptibility to type 1 diabetes (T1D).

RESULTS

The total integrated concentrations of soluble adhesion molecules were comparable between the two groups. The autoantibody-positive children tended to have higher sL-selectin concentrations during the 3-month seroconversion (SC) period than did the control children during the corresponding period (P = 0.07), the difference being significant (P = 0.03) after excluding subjects with signs of a concurrent enterovirus infection. Autoantibody-positive children had higher concentrations of sL-selectin in the 3-month period when an enterovirus infection was detectable than did the control children (P = 0.018). No significant difference could, however, be seen after excluding the children with concomitant seroconversion to autoantibody positivity.

CONCLUSIONS

Elevated concentrations of sL-selectin are temporally associated with seroconversion to autoantibody positivity suggesting that leukocyte activation might coincide with the appearance of beta-cell autoimmunity. Early-onset progressive beta-cell autoimmunity, on the other hand, is not reflected in overall increased concentrations of soluble adhesion molecules in the peripheral circulation during the first 2 years of life in children carrying increased HLA-conferred disease susceptibility. Enterovirus infections (EVIs) are not independently associated with increased circulating sL-selectin concentrations in young children with enhanced HLA-conferred susceptibility to T1D.

Soluble adhesion molecules in pre-clinical Type 1 diabetes: a prospective study

AIMS

This prospective case-control study aimed at evaluating the time course of serum concentrations of soluble adhesion molecules; intercellular adhesion molecule-1 and L-selectin in siblings with signs of pre-clinical Type 1 diabetes in order to relate these concentrations to autoantibody status and to assess whether these markers could discriminate between those siblings who progressed to clinical diabetes and those who remained non-diabetic.

METHODS

Serum levels of soluble adhesion molecules were measured with enzyme-linked immunosorbent assays in autoantibody-positive initially healthy siblings of diabetic children who progressed to clinical disease during the observation period of 10 years and in sex- and age-matched autoantibody-positive siblings who have remained unaffected.

RESULTS

The intraindividual and interindividual variability in the concentrations of soluble adhesion molecules was conspicuous both among the progressors and non-progressors. Integrated concentrations (area-under-the curve) of intercellular adhesion molecule-1 over a period of 6 to 48 months before the diagnosis was higher in the progressors ( p=0.035), the difference being most evident 18 to 24 months before diagnosis ( p=0.015). The integrated concentrations of soluble L-selectin were similar in progressors and non-progressors over the total pre-clinical period. There were no differences in the integrated concentrations of soluble adhesion molecules in relation to the initial or maximal number of autoantibodies detected during the follow-up.

CONCLUSION/INTERPRETATION

These observations suggest that the process of destructive insulitis could be initiated approximately 4 years before the manifestation of clinical diabetes, being most active about 1.5 years before diagnosis. Peripheral concentrations of soluble intercellular adhesion molecule-1 or L-selectin are not helpful in the identification of those prediabetic subjects who will progress to clinical disease over the next 10 years, since there is substantial overlapping in these concentrations between progressors and non-progressors.

Gene and cell therapies for diabetes mellitus: strategies and clinical potential

The last 5 years have witnessed an explosion in the use of genes and cells as biomedicines. While primarily aimed at cancer, gene engineering and cell therapy strategies have additionally been used for Mendelian, neurodegenerative and metabolic disorders. The main focus of gene and cell therapy strategies in metabolism has been diabetes mellitus. This disease is a disorder of glucose homeostasis, either due to the immune-mediated eradication of pancreatic beta cells in the islets of Langerhans (type 1 diabetes) or resulting from insulin resistance and obesity syndromes where the insulin-producing capability of the beta cell is ultimately exhausted in the face of insensitivity to the effects of insulin in the peripheral glucose-utilising tissues (type 2 diabetes). A significant number of animal studies have demonstrated the potential in restoring normoglycaemia by islet transplantation in the context of immunoregulation achieved by gene transfer of immunoregulatory genes to allo- and xenogeneic islets ex vivo. Additionally, gene and cell therapy has also been used to induce tolerance to auto- and alloantigens and to generate the tolerant state in autoimmune rodent animal models of type 1 diabetes or rodent recipients of allogeneic/xenogeneic islet transplants. The achievements of gene and cell therapy in type 2 diabetes are less evident, but seminal studies promise that this modality can be relevant to treat and perhaps prevent the underlying causes of the disease. Here we present an overview of the current status of gene and cell therapy for type 1 and 2 diabetes and we propose potential therapeutic options that could be clinically useful. For type 1 diabetes, transplantation of islets engineered to evade or suppress the recipient immune response is the most readily-available technology today. A number of gene delivery vectors encoding proteins that impair a variety of immune cells have already been examined and proven versatile. More challenging but, nonetheless, just over the horizon are attempts to promote tolerance to islet allografts. Type 2 diabetes will likely require a better understanding of the processes that determine insulin sensitivity in the periphery. Targeting tissues such as muscle and fat with vectors encoding genes whose products promote insulin sensitivity and glucose uptake is an approach that does not carry with it the side-effects often associated with pharmacologic agents currently in use. In the end, progress in vector design, elucidation of antigen-specific immunity and insulin sensitivity will provide the framework for gene drug use in the treatment of type 1 and type 2 diabetes.

Effect of modified diabetic splenocytes on mice injected with multiple low-dose streptozotocin

This work reports the effects of a previous injection of mitomycin-modified splenocytes from multiple-low dose streptozotocin-treated mice (mld-sz) on autoimmune diabetes produced by mld-sz. Our work shows that a previous inoculation of modified mononuclear splenocytes from mld-sz mice prevents alterations in glycemia, in insulin secretion (IS) pattern from isolated perifused islets, and in mass of pancreatic islets. Immunohistochemistry showed an alteration in the number of beta, but not of alpha or delta cells. While a mononuclear intra-islet infiltration was observed in mld-sz mice, a predominantly polar or peri-islet infiltration was seen in vaccinated mice. Islet-associated mononuclear cells from mld-sz mice produced diabetes and induced a diminished IS when transferred to normal receptors. Those cells from previously vaccinated mld-sz mice had no effect when injected into normal receptors. In addition, they also inhibited the damage induced in normal receptors by the islet-associated mononuclear cells from mld-sz animals. Cellular death was also prevented by previous vaccination. Our results suggest that vaccination with modified splenocytes from mld-sz mice is capable of shifting the islet cells infiltration pattern from an aggressive one toward a protective one and thus preventing the beta cell destruction observed in mld-sz mice.

Long-term reversal of established autoimmunity upon transient blockade of the LFA-1/intercellular adhesion molecule-1 pathway

Transgenic models and administration of mAbs directed against the LFA-1/intercellular adhesion molecule 1 (ICAM-1) pathway have shown that these costimulatory molecules play a key role in generating effector cells mediating inflammatory responses. In this report, durable remission of recent diabetes in nonobese diabetic (NOD) mice was induced by transient expression of an immunoadhesin gene encoding the soluble form of ICAM-1 (sICAM-1/Ig). A single i.v. injection of an adenovirus vector encoding the immunoadhesin gene led to 70% diabetes remission as opposed to 0% in mice injected with a control adenovirus vector. Despite the rapid decline of sICAM-1/Ig serum levels, diabetes remission remained stable in 50% of NOD mice for >6 mo. sICAM-1/Ig expression also led to long-term protection against diabetes in prediabetic NOD mice. sICAM-1/Ig in vitro induced an agonistic effect of T cell activation in a TCR-transgenic model, increasing T cell proliferation and IL-2 secretion. Importantly, protected mice were not immunosuppressed because they rejected skin allografts normally and developed immunity against the adenovirus vector. Rather, sICAM-1/Ig induced active tolerance, as assessed by the persistence of diabetogenic T cells in protected mice and the reversal of protection by immunosuppression with cyclophosphamide.

Immunotherapy of type 1 diabetes: lessons for other autoimmune diseases

The nonobese diabetic (NOD) mouse is a well-recognised animal model of spontaneous autoimmune insulin-dependent diabetes mellitus. The disease is T-cell mediated, involving both CD4 and CD8 cells. Its progress is controlled by a variety of regulatory T cells. An unprecedented number of immunological treatments have been assessed in this mouse strain. This chapter systematically reviews most of these therapeutic manoeuvres, discussing them in the context of their significance with regard to the underlying mechanisms and the potential clinical applications. The contrast between the surprisingly high rate of success found for a multitude of treatments (more than 160) administered early in the natural history of the disease and the few treatments active at a late stage is discussed in depth. Most of the concepts and strategies derived from this model apply to other autoimmune diseases, for which no such diversified data are available.

Soluble adhesion molecules in preclinical type 1 diabetes. The Childhood Diabetes in Finland Study Group

We measured the concentrations of the soluble forms of the intercellular adhesion molecule-1 (sICAM-1) and L-selectin in 95 autoantibody-positive siblings of children with type 1 diabetes and 95 sex- and age-matched siblings testing negative for diabetes-associated autoantibodies to assess the possible role of soluble adhesion molecules as markers of progressive ss-cell destruction in preclinical diabetes and their ability to discriminate between those siblings who progress to clinical disease and those who remain nondiabetic. We observed an inverse correlation between age and the levels of both sICAM-1 (r = -0.31, p < 0.001) and sL-selectin (r = -0.27, p < 0.001) in the control siblings but no association with HLA-DR phenotypes. There was no difference in the circulating levels of soluble adhesion molecules between the antibody-positive and negative siblings. Among the antibody-positive siblings, those with at least three autoantibodies had higher sICAM-1 levels (p < 0.01) than those testing positive for only one, and siblings with three autoantibodies or more had higher concentrations of sL-selectin (p < 0.01) than those with two autoantibodies. Siblings with an islet cell antibody level of 20 Juvenile Diabetes Foundation units or more had higher sICAM-1 concentrations than those with a level below 20 (p < 0.001), and those testing positive for antibodies to the protein tyrosine phosphatase-related IA-2 antigen had increased levels of both sICAM-1 (p = 0.03) and sL-selectin (p = 0.02) compared with siblings who tested negative. The antibody-positive siblings who progressed to clinical type 1 diabetes were significantly younger than the nonprogressors (p < 0.001) and had higher levels of sICAM-1 initially (p < 0.001). The difference in sICAM-1 concentrations remained significant (p = 0.03) after age adjustment. Our results indicate that concentrations of soluble adhesion molecules are increased in the autoantibody-positive siblings who have the highest risk of developing clinical diabetes, suggesting that ss-cell destruction is reflected in increased circulating levels of these molecules. This is supported by the observation of elevated sICAM-1 concentrations in the 29 siblings who actually progressed to clinical type 1 diabetes. Peripheral levels of soluble adhesion molecules are not able to discriminate between progressors and nonprogressors, however, due to substantial overlapping between these two groups.

Intercellular adhesion molecule-1 (ICAM-1) K469E polymorphism: no association with type 1 diabetes among Finns

The intercellular adhesion molecule-1 (ICAM-1) has an important role in the process of lymphocyte migration and activation, and is supposed to be involved in the pathogenesis of type 1 diabetes. We studied A/G (K469E) polymorphism of the ICAM-1 gene in 218 type 1 diabetes patients and 212 controls from Finland and found no association. We then studied transmission of the ICAM-1 alleles in 102 Finnish families using a transmission disequilibrium test (TDT). Alleles A and G were transmitted to the affected offspring in 50% each. Stratification by the HLA-DQB1-DQA1 genotypes, sex and age at onset did not reveal association. Our data demonstrate that in the Finnish population K469E polymorphism of the ICAM-1 gene is not associated with type 1 diabetes.

Circulating forms of intercellular adhesion molecule (ICAM)-1 in mice lacking membranous ICAM-1

Mice deficient in intercellular adhesion molecule-1 (ICAM-1), lacking membranous ICAM-1, show a normal development but abnormalities of inflammatory and immune functions. Although the membrane-bound form of ICAM-1 is not detectable in the mutant strain, circulating ICAM-1 (cICAM) is present in serum from ICAM-1-deficient mice in similar amounts as in serum from wild-type mice. These findings were confirmed in vitro by flow cytometric analysis of lipopolysaccharide-stimulated spleen cells, and cICAM-enzyme-linked immunosorbent assay analysis of supernatants of cultured spleen cells. To analyze for the source of cICAM-1, spleen cell RNA was isolated and ICAM-1 RNA was amplified by reverse transcriptase-polymerase chain reaction using primers binding in the 5′ and 3′ untranslated regions. Different fragments were cloned and sequenced. In wild-type RNA the common 5 domain form of ICAM-1 was identified. In RNA from ICAM-1 mutant mice only 3 smaller fragments were found. Sequencing these fragments identified 3 alternatively spliced isoforms of ICAM-1, lacking 2 or 3 extracellular domains. However, in all spliced fragments the transmembrane domain was included. Therefore, we postulate that circulating forms of ICAM-1 are generated by proteolytic cleavage of membranous ICAM-1. The data indicate that the expression of membranous ICAM-1 and the appearance of circulating forms in serum are independently regulated mechanisms.

CD11a expression and soluble ICAM-1 levels in peripheral blood in high-risk and overt type 1 diabetes subjects

A pair of correspondent adhesion molecules: LFA-1 (CD11aCD18) and ICAM-1 (CD54) was shown to be involved in autoimmune insulitis in animal models. Anti-LFA-1 or anti-ICAM-1 monoclonal antibodies administered in vivo had a very strong preventive effect on the development of spontaneous diabetes with a marked reduction of insulitis. On the other hand elevated levels of the soluble form of ICAM-1 (sICAM-1) were documented in subjects at risk for type 1 diabetes. Recently sICAM-1 was shown to play an immunoregulatory role as an inhibitor of islet insulitis. The aim of the present study was to evaluate CD11a + mononuclear cells (lymphocytes and monocytes) and soluble sICAM-1 levels in the peripheral blood of subjects with preclinical and overt type 1 diabetes to assess their role in the development of the autoimmune process and their possible associations with the humoral autoimmune markers. The study was carried out in three groups of subjects: 26 first degree relatives of type 1 diabetes patients (prediabetics) with the combinations of autoantibodies against pancreatic B cells (ICA, GADA, IA-2A, IAA), 22 patients with a recent onset of type 1 diabetes and age and sex-matched 24 healthy volunteers (control group). We observed an increased fluorescence intensity of CD11a on mononuclear cells in overt diabetes subjects and a positive correlation between CD11a fluorescence intensity on monocytes and ICA titre. The highest sICAM-1 levels we obtained in the peripheral blood in the prediabetics in comparison to patients with clinical diabetes and the healthy controls. We found a positive correlation between slCAM-1 and values of ICA, GADA and a total number of antibodies present. In conclusion our study suggests that LFA-1 and sCAM-1 play an important role in the pathogenesis of type 1 diabetes. The assessment of the CD11a bearing monocytes and sICAM-1 levels are potential markers of the preclinical stage of the autoimmune diabetes, but further prospective studies in high risk diabetes type 1 subjects are needed.

Gammadelta T-cells alterations in the peripheral blood of high risk diabetes type 1 subjects with subclinical pancreatic B-cells impairment

There is increasing evidence that CD3 + cells bearing gammadelta T-cell receptor (represent the minor subpopulation of the T-cells in the peripheral blood in humans) are involved in autoimmunity development. Gammadelta T-cell receptor (TCR)+ /CD8+ T-cells have been recently found to play a critical role in the pathogenesis and prevention of autoimmune diabetes in the animal model. The aim of the present study was the estimation the gammadelta T-cell subpopulation levels in the peripheral blood of subjects with preclinical and overt type 1 diabetes and their possible associations with the humoral immunity, metabolic parameters and pancreatic B-cells function. The study was carried out in three groups of subjects: 26 first degree relatives of type 1 diabetes patients (prediabetics) with the combinations of autoantibodies against pancreatic B-cells (ICA, GADA, IA-2A, IAA), 22 patients with a recent onset of type 1 diabetes and age and sex-matched 24 healthy volunteers (control group). A decrease was observed in the absolute numbers and percentages of gammadelta+ /CD8+ and gammadelta+ /CD8- T-cell subpopulations in peripheral blood in the prediabetics with the impaired first phase of insulin secretion in comparison to relatives with autoantibodies but still with normal B-cells function, patients with clinical diabetes and healthy controls. In conclusion, the study suggests that the gammadelta T-cells play an important role in the development of insulin-dependent diabetes mellitus (IDDM). It is possible that their levels in the peripheral blood could be an additional marker of preclinical detection of the disease, but further prospective studies in high risk of IDDM subjects are needed.