Demystified...adhesion molecule deficiencies

Association between the polymorphisms in intercellular adhesion molecule-1 and the risk of coronary atherosclerosis: a case-controlled study

Intercellular adhesion molecule-1 (ICAM-1), an important immune adhesion molecule, is related to the atherosclerosis. We explored the association between the polymorphisms of the ICAM-1 gene and coronary atherosclerotic stenosis to determine whether any risk factors correlate with genetic polymorphisms in Chinese patients with coronary atherosclerosis. Using the SNaPshot assay, we examined six SNPs of rs5491, rs281428, rs281432, rs5496, rs5498 and rs281437 in 604 patients diagnosed with coronary atherosclerotic stenosis by angiography and in 468 controls. We found that AG genotype of rs5498 had higher frequency in the coronary atherosclerotic stenosis patients (41.56% to 34.19%, P = 0.017, OR = 1.368,95%CI 1.057–1.770) and that the haplotype A_rs5491C_rs281428G_rs281432 had higher frequency in patients (13.8% to 12.1%, P = 0.048). When analyzing the clinical risk factors for coronary atherosclerosis, we found that the rs5498 locus was associated with the levels of apolipoprotein A (APOA) (P = 0.0002) and triglycerides (TG) (P = 0.002). Furthermore, the levels of triglycerides (TG) were also associated with rs281432 (P = 0.040). Additionally, the TT genotype of rs281437 was associated with a higher level of apolipoprotein A (APOA) (P = 0.039) and apolipoprotein B (APOB) (P = 0.003). Finally, among those with coronary atherosclerosis, we found no differences in the haplotype analysis of polymorphisms of the ICAM-1 gene from individuals with hypertension or those who smoked. According to our results, the ICAM-1 polymorphisms were associated with risk of coronary atherosclerotic stenosis in Chinese individuals.

Intercellular adhesion molecule-1 K469E and angiotensinogen T207M polymorphisms in coronary slow flow

OBJECTIVE

To investigate intercellular adhesion molecule-1 (ICAM1) and angiotensinogen (AGT) gene polymorphisms, as related to atherosclerosis and endothelial dysfunction, in coronary slow flow (CSF).

SUBJECTS AND METHODS

The participants in this study were 48 patients with CSF and 67 patients with normal coronary flow as controls. The K469E polymorphism of ICAM1 (rs5498) and the T207M polymorphism of AGT (rs4762) were determined using the polymerase chain reaction amplification method.

RESULTS

Baseline demographic parameters were similar in both groups. The mean thrombolysis in myocardial infarction frame count was significantly higher in patients with CSF (23.8 ± 5.1) compared to the controls (13.3 ± 2.6, p < 0.001). A significant association was found between the ICAM1 K allele and CSF (OR: 1.96, 95% CI: 1.15-3.35, p = 0.013). There was no difference in the frequency of AGT T207M genotypes in the patients with CSF and the control subjects.

CONCLUSION

This study showed that K469E polymorphisms of ICAM1 that play a role in atherosclerotic pathogenesis are related to CSF.

Signaling for synergistic activation of natural killer cells

Natural killer (NK) cells play a pivotal role in early surveillance against virus infection and cellular transformation, and are also implicated in the control of inflammatory response through their effector functions of direct lysis of target cells and cytokine secretion. NK cell activation toward target cell is determined by the net balance of signals transmitted from diverse activating and inhibitory receptors. A distinct feature of NK cell activation is that stimulation of resting NK cells with single activating receptor on its own cannot mount natural cytotoxicity. Instead, specific pairs of co-activation receptors are required to unleash NK cell activation via synergy-dependent mechanism. Because each co-activation receptor uses distinct signaling modules, NK cell synergy relies on the integration of such disparate signals. This explains why the study of the mechanism underlying NK cell synergy is important and necessary. Recent studies revealed that NK cell synergy depends on the integration of complementary signals converged at a critical checkpoint element but not on simple amplification of the individual signaling to overcome intrinsic activation threshold. This review focuses on the signaling events during NK cells activation and recent advances in the study of NK cell synergy.

Immunophenotypic profile and role of adhesion molecules in splenic marginal zone lymphoma with bone marrow involvement

Splenic Marginal Zone Lymphoma (SMZL), with or without villous lymphocytes (VL+/-), is a low-grade lymphoproliferative disorder with constant involvement of the bone marrow (BM). Different BM infiltration patterns, mainly intra-sinusoidal, interstitial and nodular, have been described. Adhesion molecules (AMs) constitute a heterogeneous group of antigenic receptors playing a major role in leukocyte recruitment, in lymphocyte homing and in cellular-mediated immune response. Evolution and pattern of the BM infiltrate could be influenced by a variable expression of AM on SMZL lymphocytes. The degree and pattern of BM infiltration and the immunohistochemical expression of AM (H-CAM, BL-CAM, L-selectin, PSGL-1, E-selectin, ICAM-1, VCAM-1 and Beta-1 integrin) among the different infiltration patterns were evaluated in BM biopsies of 38 patients with SMZL and graded according to a semi-quantitative score ranging from 0-4 and based on the percentage of positive cells. An intra-sinusoidal infiltration was constantly observed, alone or in conjunction with other patterns. H-CAM and BL-CAM showed a moderate-to-high degree of positivity in the intra-sinusoidal infiltrate (median expression grade-3) and were expressed in the neoplastic lymphocytes independently from the pattern. PSGL-1 was mostly expressed in the perisinusoidal region and in case of interstitial infiltration (grade-2). ICAM-1 and VCAM-1 were selectively expressed in the nodules as a reticular meshwork located in the core region (grade-2); VCAM-1 was also expressed in the perinodular endothelia. E-selectin, L-selectin and beta-1 integrin proved constantly negative. These data suggest that different expression of AM can influence the modality of BM infiltration in SMZL.

ICAM1 and VCAM1 polymorphisms, coronary artery calcium, and circulating levels of soluble ICAM-1: the multi-ethnic study of atherosclerosis (MESA)

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) may be important contributors to the development and progression of atherosclerosis. Using a stratified random sample of 2880 participants of the Multi-Ethnic Study of Atherosclerosis we investigated the relationship of 12 ICAM1 and 17 VCAM1 SNPs and coronary artery calcium (CAC) and ICAM1 SNPs and circulating levels of soluble ICAM-1 (sICAM-1). There were no ICAM1 or VCAM1 SNPs significantly associated with CAC in any of the four race/ethnic groups. In a subset of 1451 subjects with sICAM-1 measurements, we observed a significant association with rs5491 in all four race/ethnic groups corroborating previous research that has shown that the T-allele of rs5491 interferes with the monoclonal antibody used to measure sICAM-1 in this study. After excluding all rs5491 T-allele carriers, several ICAM1 SNPs were significantly associated with sICAM-1 levels; rs5496 in African Americans, rs5498 and rs3093030 in European Americans, and rs1799969 in Hispanics. Our results identified ICAM1 polymorphisms that were significantly associated with sICAM-1 level but not CAC, a subclinical marker of atherosclerosis.

Activation, coactivation, and costimulation of resting human natural killer cells

Natural killer (NK) cells possess potent perforin- and interferon-gamma-dependent effector functions that are tightly regulated. Inhibitory receptors for major histocompatibility complex class I display variegated expression among NK cells, which confers specificity to individual NK cells. Specificity is also provided by engagement of an array of NK cell activation receptors. Target cells may express ligands for a multitude of activation receptors, many of which signal through different pathways. How inhibitory receptors intersect different signaling cascades is not fully understood. This review focuses on advances in understanding how activation receptors cooperate to induce cytotoxicity in resting NK cells. The role of activating receptors in determining specificity and providing redundancy of target cell recognition is discussed. Using Drosophila insect cells as targets, we have examined the contribution of individual receptors. Interestingly, the strength of activation is not determined simply by additive effects of parallel activation pathways. Combinations of signals from different receptors can have different outcomes: synergy, no enhancement over individual signals, or additive effects. Cytotoxicity requires combined signals for granule polarization and degranulation. The integrin leukocyte function-associated antigen-1 contributes a signal for polarization but not for degranulation. Conversely, CD16 alone or in synergistic combinations, such as NKG2D and 2B4, signals for phospholipase-C-gamma- and phosphatidylinositol-3-kinase-dependent degranulation.

Differential maturation of the innate immune response in human fetuses

Newborns and especially preterm infants show a unique susceptibility to severe bacterial infections that cause significant morbidity and mortality. As very few data are available on innate immune functions in human fetuses, we conducted a comprehensive study to investigate the expression of several adhesion molecules essentially involved in migration (CD11a, CD11b, CD11c, CD18, and CD62L). Furthermore, phagocytic activity, generation of respiratory burst products, and production of several proinflammatory cytokines were assessed. Various functions of the fetal innate immune system were demonstrated to be essentially different from those observed in term neonates or adults. Expression of several surface markers was significantly diminished on fetal granulocytes. Furthermore, a significantly reduced phagocytic activity of fetal granulocytes and monocytes was found, contrasted by an enhanced generation of reactive oxygen products. In addition, we demonstrate that significant numbers of fetal monocytes are capable of the production of proinflammatory cytokines in response to stimulation. However, the pattern of cytokine production is different from the more mature individuals: the number of IL-6- and tumor necrosis factor-alpha-positive monocytes were significantly diminished, whereas more IL-8-producing monocytes were found compared with adults. The results of our study add significantly to our understanding of the maturation and impairment of the innate immune response.

A novel form of integrin dysfunction involving beta1, beta2, and beta3 integrins

The adhesion receptors known as integrins perform key functions for hematopoietic cells. The platelet integrin alphaIIbbeta3 is critical in hemostasis, and the beta1 and beta2 integrins on leukocytes have many roles in cell-mediated immunity. Mutations in the beta2 subunit lead to integrin nonexpression and to an immune deficiency, leukocyte adhesion deficiency-1. Mutations in either the alpha or beta subunit of alphaIIbbeta3 usually lead to integrin nonexpression and a bleeding tendency termed Glanzmann thrombasthenia. Here we describe a unique patient with clinical features of both Glanzmann thrombasthenia and leukocyte adhesion deficiency-1. The patient has normal expression of beta1, beta2, and beta3 integrins, but all are dysfunctional. The key findings are that "inside-out" signaling pathways leading to integrin activation are defective and that this is associated with abnormal integrin clustering. The integrins themselves are intact and capable of function following extracellular stimulation. T cell motility is normal, as are the expression levels and electrophoretic characteristics of all cytoskeletal and signaling proteins tested, except PKC-alpha, which has enhanced expression in the patient's cells. To our knowledge, this is the first description of a dysfunction affecting three classes of integrins. We propose that it is caused by a lesion in an intracellular factor or signaling pathway essential for integrin activation in hematopoietic cells and results in lack of regulation of clustering, an essential component of integrin-mediated adhesion.