Prognostic value of soluble intercellular adhesion molecule-1 (s-ICAM-1) in HIV-infected children

ICAM-1 in HIV infection and underlying mechanisms

Intercellular adhesion molecule 1 (ICAM-1) is a glycoprotein that participates in inflammatory and immune responses. Both cell surface and soluble ICAM-1 are significantly increased during human immunodeficiency virus (HIV) infection, and ICAM-1 has important functions in promoting inflammatory responses and enhancing HIV infectivity; however, a comprehensive summary these roles has yet to be elaborated. In this review we describe the general biological characteristics of ICAM-1, its association with HIV disease progression and promotion of HIV production, mechanisms inducing upregulation of ICAM-1, and possible intervention strategies, representing important insights in the context of HIV treatment.

Significance of correlation between interferon-γ and soluble intercellular adhesion molecule-1 and interleukin-17 in hepatitis B virus-related cirrhosis

BACKGROUND AND OBJECTIVE

Hepatitis B virus (HBV)-related cirrhosis is known to be associated with chronic hepatic inflammation. The present study aimed to examine the correlation between inflammatory mediators INF-γ, IL-17, and sICAM-1 in HBV cirrhotic patients.

METHODS

The levels of sICAM-1, interleukin-17, and IFN-γ were measured with enzyme-linked immunosorbent assays in 120 cirrhotic patients with HBV and 270 sex- and age-matched healthy controls. Total bilirubin (TB) was measured and the association between TB and IFN-γ, sICAM-1, interleukin-17 were analyzed. The levels of these cytokines in serum and the association between IFN-γ and sICAM-1 as well as interleukin-17 were investigated. Relationships between these cytokines and Child-Pugh classes were analyzed in patients.

RESULTS

Age and sex were similar, but TB values were significantly different between the two groups (P<0.001). Serum levels of sICAM-1, interleukin-17, and IFN-γ were significantly higher in cirrhotic patients with HBV than in controls (P<0.001 for both). TB levels were positively correlated with IFN-γ, interleukin-17 and sICAM-1 levels. Significantly positive correlations were also found between IFN-γ and interleukin-17 as well as sICAM-1 (r=0.817 and r=0.561, respectively, P<0.01). There were significant differences between the studied cytokines (sICAM-1, interleukin-17, and IFN-γ) and Child-Pugh classes (P<0.01).

CONCLUSIONS

The increased IFN-γ level was correlated with both IL-17 and sICAM-1, and it may primarily play a role as cytokines trigger in liver injury. Both IL-17 and sICAM-1 may synergistically contribute to liver damage.

Altered frequency and phenotype of CD4+ forkhead box protein 3+ T cells and its association with autoantibody production in human immunodeficiency virus-infected paediatric patients

The association between immune dysfunction and the development of autoimmune pathology in patients with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) is not clear. The frequency and phenotype of regulatory T cells, as well as the presence of autoantibodies, were evaluated in a paediatric cohort of HIV-infected patients without clinical evidence of autoimmune disease. Lower absolute counts but higher percentages of total CD4(+) forkhead box protein 3 (FoxP3)(+) T cells were recorded in children with severe immunosuppression than in those without evidence of immunosuppression. The frequencies of classical CD4(+) CD25(+) FoxP3(+) regulatory T cells were not altered, whereas CD4(+) FoxP3(+) CD25(-) T cells were found increased significantly in patients with severe immunosuppression. Like classical regulatory T cells, CD4(+) FoxP3(+) CD25(-) T cells display higher cytotoxic T-lymphocyte antigen 4 (CTLA-4) but lower CD127 expression compared with CD4(+) FoxP3(-) CD25(+) T cells. An improvement in CD4(+) T cell counts, along with a decrease in viral load, was associated with a decrease in CD4(+) FoxP3(+) CD25(-) T cells. The majority of the patients with severe immunosuppression were positive for at least one out of seven autoantibodies tested and displayed hypergammaglobulinaemia. Conversely, HIV-infected children without evidence of immunosuppression had lower levels of autoantibodies and total immunoglobulins. A decline in CD4(+) FoxP3(+) T cell numbers or a variation in their phenotype may induce a raise in antigen exposure with polyclonal B cell activation, probably contributing to the generation of autoantibodies in the absence of clinical autoimmune disease.

Metabolic abnormalities and viral replication are associated with biomarkers of vascular dysfunction in HIV-infected children

OBJECTIVES

HIV-infected children may be at risk for premature cardiovascular disease. We compared levels of biomarkers of vascular dysfunction in HIV-infected children (with and without hyperlipidaemia) with those in HIV-exposed, uninfected (HEU) children enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS), and determined factors associated with these biomarkers.

METHODS

A prospective cohort study was carried out. Biomarkers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP1)], coagulant dysfunction (fibrinogen and P-selectin), endothelial dysfunction [soluble intracellular cell adhesion molecule-1 (sICAM), soluble vascular cell adhesion molecule-1 (sVCAM) and E-selectin], and metabolic dysfunction (adiponectin) were measured in 226 HIV-infected and 140 HEU children. Anthropometry, body composition, lipids, glucose, insulin, HIV disease severity, and antiretroviral therapy were recorded.

RESULTS

The median ages of the children were 12.3 years in the HIV-infected group and 10.1 years in the HEU group. Body mass index (BMI) z-scores, waist and hip circumferences, and percentage body fat were lower in the HIV-infected children. Total and non-high-density lipoprotein (HDL) cholesterol and triglycerides were higher in HIV-infected children. HIV-infected children also had higher MCP-1, fibrinogen, sICAM and sVCAM levels. In multivariable analyses in the HIV-infected children alone, BMI z-score was associated with higher CRP and fibrinogen, but lower MCP-1 and sVCAM. Unfavourable lipid profiles were positively associated with IL-6, MCP-1, fibrinogen, and P- and E-selectin, whereas increased HIV viral load was associated with markers of inflammation (MCP-1 and CRP) and endothelial dysfunction (sICAM and sVCAM).

CONCLUSIONS

HIV-infected children have higher levels of biomarkers of vascular dysfunction than do HEU children. Risk factors associated with higher biomarkers include unfavourable lipid levels and active HIV replication.

Increase in Adhesion Molecules in Cerebrospinal Fluid of Children with Mumps and Mumps Meningitis

Adhesion molecules play a key role in leucocyte migration into the central nervous system (CNS). Concentrations of endothelial-derived soluble intercellular adhesion molecule-1 (sICAM-1) and leucocyte-originated soluble L-selectin (sL-selectin) in cerebrospinal fluid (CSF) of children with mumps meningitis (mononuclear pleocytosis, n = 33) and mumps (absence of pleocytosis, n = 9) were compared with values from age-matched control group (n = 19). In 14 patients from the meningitis group, adhesion molecule levels together with albumin concentration were estimated in paired CSF/serum samples to calculate concentration quotients and determine molecule intrathecal release. Both sICAM-1 (median 3.44 versus 0.86 ng/ml; P < 0.0001) and sL-selectin (median 29.91 versus 8.52 ng/ml; P < 0.0001) concentrations in CSF were increased in mumps meningitis patients compared with controls. Increased levels of the selected adhesion molecules were also observed in mumps patients without CNS involvement when compared with controls (median sICAM-1: 1.14 versus 0.86 ng/ml, sL-selectin: 13.54 versus 8.52 ng/ml; P < 0.01). Additionally, the concentration of adhesion molecules was found to correlate with CSF leucocyte count. Considerable correlation of sICAM-1 and sL-selectin quotients and corresponding albumin quotients suggests that a majority of the soluble adhesion molecules originated from the bloodstream. Analysis of adhesion molecule levels demonstrated indirect evidence of brain-derived fractions. Our results suggest the involvement of adhesion molecules during the early phase of mumps meningitis.

Induction of intercellular adhesion molecule-1 on human brain endothelial cells by HIV-1 gp120: role of CD4 and chemokine coreceptors

Central nervous system dysfunction is commonly observed in children with HIV-1 infection, but the mechanisms whereby HIV-1 causes encephalopathy are not completely understood. We have previously shown that human brain microvascular endothelial cells (HBMEC) from children are responsive to gp120 derived from X4 HIV-1 by increasing expression of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule-1. However, the mechanisms involved in gp120-mediated up-regulation of cell adhesion molecule expression is unclear. In the present study, we found that gp120 derived from both X4 and R5 HIV-1 induced increased expression of ICAM-1 on HBMEC, but the degree of this up-regulation differed among the various HBMEC isolates. The up-regulation of ICAM-1 was inhibited by anti-CD4 antibodies as well as by specific antibodies directed against chemokine receptors and small-molecule coreceptor inhibitors. Anti-CD4 antibodies inhibited the increase in ICAM-1 expression mediated by gp120 derived from X4 and R5 HIV-1, whereas antibodies against chemokine receptors displayed a differential inhibition depending on the source of gp120. Both X4 and R5 gp120-induced ICAM-1 expression was sensitive to pertussis toxin and involved the nuclear factor-kB pathway. These findings indicate a direct involvement of CD4 and a differential involvement of chemokine receptors in the activation of pediatric HBMEC by X4 and R5 gp120. The activation of brain endothelium of children by HIV-1 protein gp120 by way of CD4 and chemokine receptors may have implications for the pathogenesis of HIV-1 encephalopathy in the pediatric population.

The adhesion molecule ICAM-1 and its regulation in relation with the blood-brain barrier

The blood-brain barrier (BBB) is formed by high resistance tight junctions within the capillary endothelium perfusing the vertebrate brain. Normal BBB maintains a unique microenvironment within the central nervous system (CNS). In neurodegenerative disorders (for example multiple sclerosis, MS), the BBB becomes impaired. Perivascular cells (astrocytes, macrophages and microglial cells) and brain microvascular endothelial cells (BMEC) produce various inflammatory factors that affect the BBB permeability and the expression of adhesion molecules. Indeed, cytokines can stimulate the expression of several adhesion molecules on brain microvascular endothelial cells. Among these adhesion molecules, the intercellular adhesion molecule-1 (ICAM-1) binds to its leukocyte ligands and allows activated leukocytes entry into the CNS. This review is dealing with the expression and regulation of ICAM-1 in relation with several properties of the BBB. Particularly, the role of ICAM-1 in the control of the leukocyte traffic into the CNS, as well as in cerebral malaria and in CNS infection by viruses, is discussed.