Effect of cytokine and antigen stimulation on peripheral blood lymphocyte syndecan-1 expression

Glycosaminoglycans located on neutrophils and monocytes impact on CXCL8- and CCL2-induced cell migration

The role of glycosaminoglycans on the surface of immune cells has so far been less studied compared to their participation in inflammatory responses as members of the endothelium and the extracellular matrix. In this study we have therefore investigated if glycosaminoglycans on immune cells act in concert with GPC receptors (i.e. both being cis-located on leukocytes) in chemokine-induced leukocyte mobilisation. For this purpose, freshly-prepared human neutrophils and monocytes were treated with heparinase III or chondroitinase ABC to digest heparan sulfate -chains or chondroitin sulfate-chains, respectively, from the leukocyte surfaces. Subsequent analysis of CXCL8- and CCL2-induced chemotaxis revealed that leukocyte migration was strongly reduced after eliminating heparan sulfate from the surface of neutrophils and monocytes. In the case of monocytes, an additional dependence of CCL2-induced chemotaxis on chondroitin sulfate was observed. We compared these results with the effect on chemotaxis of a heparan sulfate masking antibody and obtained similarly reduced migration. Following our findings, we postulate that glycosaminoglycans located on target leukocytes act synergistically with GPC receptors on immune cell migration, which is further influenced by glycosaminoglycans located on the inflamed tissue (i.e. trans with respect to the immune cell/GPC receptor). Both glycosaminoglycan localization sites seem to be important during inflammatory processes and could potentially be tackled in chemokine-related diseases.

Role of syndecan-1 in the interaction between dendritic cells and T cells

Syndecan-1 (Sdc-1) is a heparan sulfate proteoglycan that can bind cytokines and chemokines via its heparan sulfate side chains, and has immunomodulatory properties in experimental models. Sdc-1 expression has been reported on dendritic cells (DC) and T cells. The potential role of Sdc-1 in DC-T cell interaction has not been investigated yet. We postulate that Sdc-1 is involved in DC-T cell interaction and may influence graft survival in an allogeneic transplant model. Sdc-1 expression on bone marrow-derived DC and T cells was analyzed by flow cytometry. Unstimulated and LPS stimulated Sdc-1 deficient DC were evaluated in vitro for phenotype and stimulatory capacity in mixed lymphocyte reaction. Sdc-1 deficient T cells were evaluated for proliferative capacity and differentiation in a mixed lymphocyte reaction and a proliferation assay. Allograft survival was evaluated in a fully MHC mismatched heterotopic heart transplant model, with either Sdc-1 deficient donors or recipients. Sdc-1 was expressed on the cell surface of unstimulated and LPS matured DC. Sdc-1 deficiency had no effect on expression of co-stimulatory molecules, cytokine production or T cell stimulatory capacity as compared to WT DC. Sdc-1 expression was not detectable on WT T cells, although intracellular Sdc-1 expression could be demonstrated after ConA activation. Sdc-1 deficient T cells showed reduced proliferation upon DC or ConA stimulation and reduced IL-17 production upon ConA stimulation, compared to WT T cells. Sdc-1 deficiency of either allograft or recipient did not prolong allograft survival. In conclusion, Sdc-1 is expressed on the cell surface of DC, where its absence does not affect DC phenotype or T cell stimulatory capacity. Sdc-1 is intracellularly expressed in ConA activated T cells. Sdc-1 deficiency in T cells results in a reduced proliferative response in vitro, as induced by DC and ConA. Sdc-1 deficiency in donor or recipient does not affect allograft survival.

Enhanced syndecan-1 expression on neutrophils in patients with type 2 diabetes mellitus

The peripheral neutrophils are one of the main inflammatory cells and significantly influence the damage of endothelium. Type 2 diabetes is a manifestation of an ongoing low-grade inflammation. In diabetes, impairment of neutrophil adhesion to the endothelium and migration to the site of inflammation were detected, which associated closely with adhesion molecules expressed on neutrophils and endothelial cells. To detect the expression of syndecan-1 on neutrophils in patients with type 2 diabetes mellitus, we recruited 29 patients with type 2 diabetes mellitus without any diabetic complication and 24 healthy subjects (controls). Expression of syndecan-1 was determined by flow cytometry, and potential correlations between syndecan-1 and clinical characteristics were analyzed. On neutrophils, percentage of positive syndecan-1 cells was significantly higher in subjects with diabetes (10.363 ± 1.689%) than that of the controls (3.775 ± 0.634%, P = 0.001). An association between body mass index (BMI) and percentage of positive syndecan-1 neutrophils was detected (r = 0.415, P = 0.025). When BMI was categorized into subgroups of ≤25 kg/m(2) (n = 10) and >25 kg/m(2) (n = 19), the average percentages of positive syndecan-1 neutrophils in patients with diabetes were 5.733 ± 1.842% and 12.642 ± 2.251%, respectively (t = -2.137, P = 0.042). A multiple regression analysis showed that BMI (β = 0.783, P < 0.000) was a significant predictor of positive syndecan-1 neutrophils in subjects with type 2 diabetes.

Human respiratory syncytial virus infects and induces activation markers in mouse B lymphocytes

Human respiratory syncytial virus (HRSV) is the most common cause of severe respiratory infections in infants and young children, often leading to hospitalization. Although human airway epithelial cells are the main target of HRSV, it has been reported that this virus can also infect professional antigen-presenting cells such as macrophages and dendritic cells, promoting upregulation of maturation markers. Here, we report that mouse spleen B220(+) B lymphocytes were susceptible to HRSV infection in vitro, probably involving a glycosaminoglycan-dependent mechanism. In contrast, neither CD4(+) nor CD8(+) T lymphocytes were infected. In B lymphocytes, HRSV infection upregulated major histocompatibility complex (MHC) class II but not MHC class I molecules and induced the expression of the activation marker CD86.

Vascular cells contribute to atherosclerosis by cytokine- and innate-immunity-related inflammatory mechanisms

Cardiovascular diseases are the human diseases with the highest death rate and atherosclerosis is one of the major underlying causes of cardiovascular diseases. Inflammatory and innate immune mechanisms, employing monocytes, innate receptors, innate cytokines, or chemokines are suggested to be involved in atherogenesis. Among the inflammatory pathways the cytokines are central players. Plasma levels of cytokines and related proteins, such as CRP, have been investigated in cardiovascular patients, tissue mRNA expression was analyzed and correlations to vascular diseases established. Consistent with these findings the generation of cytokine-deficient animals has provided direct evidence for a role of cytokines in atherosclerosis. In vitro cell culture experiments further support the suggestion that cytokines and other innate mechanisms contribute to atherogenesis. Among the initiation pathways of atherogenesis are innate mechanisms, such as toll-like-receptors (TLRs), including the endotoxin receptor TLR4. On the other hand, innate cytokines, such as IL-1 or TNF, or even autoimmune triggers may activate the cells. Cytokines potently activate multiple functions relevant to maintain or spoil homeostasis within the vessel wall. Vascular cells, not least smooth muscle cells, can actively contribute to the inflammatory cytokine-dependent network in the blood vessel wall by: (i) production of cytokines; (ii) response to these potent cell activators; and (iii) cytokine-mediated interaction with invading cells, such as monocytes, T-cells, or mast cells. Activation of these pathways results in accumulation of cells and increased LDL- and ECM-deposition which may serve as an 'immunovascular memory' resulting in an ever-growing response to subsequent invasions. Thus, vascular cells may potently contribute to the inflammatory pathways involved in development and acceleration of atherosclerosis.