L-Threoascorbic acid treatment promotes S. aureus-infected primary human endothelial cells survival and function, as well as intracellular bacterial killing, and immunomodulates the release of IL-1ß and soluble ICAM-1.

BACKGROUND: Vitamin C (ascorbic acid, AscH2) has been shown to enhance immunity. Here, we studied its immunomodulatory effect on human endothelial cells (ECs) during S. aureus infection. MATERIALS AND METHODS: The ex vivo effects of AscH2 were performed on primary human umbilical vein endothelial cells (HUVECs) infected or not with S. aureus. RESULTS: AscH2 treatment induced a marked downregulation of nitric oxide (NO) production and a moderate upregulation of arginase activity in S. aureus-infected HUVECs (respectively, p < 0.05 and p > 0.05). Although the upregulated release levels of soluble intercellular adhesion molecular 1 (sICAM-1/sCD54) and sE-selectin (sCD62E) molecules were not significantly different between treated and untreated S. aureus-infected HUVECs, AscH2 treatment induced reversing effect on sICAM-1 release when comparing to uninfected control HUVECs. Moreover, AscH2 treatment appears to have a significant effect on preventing HUVEC necrosis induced by S. aureus infection (p < 0.05). Furthermore, AscH2 treatment induced a significant upregulation of cell protective redox biomarker in S. aureus-infected, as shown by superoxide dismutase (SOD) activity (p < 0.05), but not by catalase activity (p > 0.05). Additionally, S. aureus infection markedly downregulated total bound calcium ions (bCa2+) levels as compared to control HUVECs, whereas, AscH2 treatment induced a slight upregulation of bCa2+ levels in infected HUVECs as compared to infected and untreated HUVECs (p > 0.05). On the other hand, AscH2 treatment downregulated increased total cellular cholesterol content (tccCHOL) levels in HUVECs induced by S. aureus infection (p < 0.05). In addition, AscH2 treatment markedly reversed S. aureus effect on upregulation of intracellular glucose (iGLU) levels within infected HUVECs (p < 0.05). Moreover, AscH2 treatment significantly downregulated S. aureus growth (p < 0.05), and significantly upregulated bacterial internalization and intracellular killing by HUVECs (p < 0.05), as well as their cell cycle activation (p < 0.01). Finally, AscH2 treatment has a slight effect on the production of interleukin 6 (IL-6), but induced a marked downregulation of that of IL-1ß in S. aureus-infected HUVECs (respectively, p > 0.05, and p < 0.05). CONCLUSIONS: Our outcomes demonstrated that, during S. aureus infection, AscH2 treatment promotes human ECs survival and function, as well as prevents inflammatory response exacerbation, while inducing bactericidal activity.

High-density lipoprotein immunomodulates the functional activities of macrophage and cytokines produced during ex vivo macrophage-CD4+ T cell crosstalk at the recent-onset human type 1 diabetes.

BACKGROUND: Both CD4+ T cells and macrophages are mainly involved in the autoimmune-mediated ß-cells destruction in type 1 diabetes (T1D). The aim of this study was to examine the effect of HDL on functional activities of macrophage and its ability to regulate the production of cytokines in autologous mixed macrophage/CD4+ T cells at the recent-onset human type 1 diabetes. METHODS: Cell samples were isolated from volunteers with recent-onset T1D or healthy controls. RESULTS: The levels of the production of IL-1ß, IL-2, IFN-γ, nitric oxide (NO), and hydrogen peroxide (H2O2) were significantly increased in the co-culture of T1D cells when compared to that of cells from healthy controls. Similarly, those of intracellular free calcium ions (ifCa2+) were slightly, but not significantly increased (p> 0.05). Conversely, macrophage exhibited significantly decreased levels of the relative tyrosine phosphorylation of STAT6 (p-STAT6, Tyr641) in culture of T1D cells than in that of cells from healthy controls; while those of p-STAT4 (Tyr693) were significantly increased. Likewise, the levels of IL-4 and IL-10 were significantly decreased in the co-culture of T1D cells compared to co-culture of cells from healthy controls. Additionally, HDL treatment significantly down-regulated the production of IL-1ß, IL-2, IFN-γ, NO, H2O2, phagocytosis, bacterial killing, the relative tyrosine phosphorylation of macrophage-expressed STAT4 (p-STAT4, Tyr693), as well as the ratio of IL-1ß/IL-10, NO production/arginase activity, p-STAT4/p-STAT6, IFN-γ/IL-4, IFN-γ/IL-10, and the combined proinflammatory (PICs)/anti-inflammatory (AICs) cytokines. Moreover, HDL treatment significantly up-regulated the production of IL-4, IL-10, arginase activity, and p-STAT6 (Tyr641) (for all comparisons, p< 0.001). CONCLUSIONS: We show for the first time that HDL may reverse both the functional activities of macrophages and immunoinflammatory response during reciprocal macrophage-CD4+ T cell crosstalk at the beginning of T1D. These findings should open the way for therapeutic trials in the short- and medium-term.

1,25-dihydroxyvitamin D3 down-modulates the production of proinflammatory cytokines and nitric oxide and enhances the phosphorylation of monocyte-expressed STAT6 at the recent-onset type 1 diabetes.

BACKGROUND: Type 1 diabetes (T1D) is associated with an imbalance between inflammation and repair. Recently, the biologically active form of vitamin D3, i.e. 1,25(OH)2D3, has been reported to have potent immunomodulatory effects on both innate and adaptive immune cells, as well as on the production of their specific cytokines. METHODS: We examined the effect of 1,25(OH)2D3 on the production of proinflammatory Th1/Th17 and anti-inflammatory Th2/Treg related cytokines, as well as on the phosphorylation of monocyte-expressed STAT4 and STAT6 at the recent-onset human T1D. RESULTS: The levels of IFN-γ, IL-17 and nitric oxide (NO) production were significantly increased in peripheral blood mononuclear cells (PBMCs) from patients with T1D compared to controls. Similarly, STAT4 tyrosine phosphorylation (p-STAT4, Tyr693) levels were significantly increased in monocytes from patients when compared to controls. Conversely, the levels of IL-4, IL-10 and p-STAT6 (Tyr641) were significantly decreased in type 1 diabetic patients than in controls. Treatment with 1,25(OH)2D3 resulted in significant up-regulation of IL-4, IL-10, arginase activity, and p-STAT6 and, conversely, down-regulation of IFN-γ, IL-17 and NO production levels, as well as p-STAT4. Additionally, 1,25(OH)2D3 significantly enhanced Treg-to-Th17 ratio, and induced a significant decrease in Th1-to-Th2, NO production-to-arginase activity and p-STAT4-to-p-STAT6 ratios. CONCLUSIONS: Our study suggests that the biologically active form of vitamin D can reverse the activation of inflammatory pathways at the onset of T1D. Additionally, its immunomodulation properties may vary depending on the overall patterns of cytokines. From a therapeutic point of view, vitamin D may potentially be suggested as an immunological adjuvant and a potential anti-inflammatory agent in individuals at risk of T1D.

Vitamin D3 enhances bactericidal activity of macrophage against Pseudomonas aeruginosa.

BACKGROUND: The bioactive form of vitamin D3, i.e.1,25-dihydroxyvitamin D3 (1,25(OH)2D3) vitamin D has been shown to modulate monocytes/macrophages physiology and its response against bacterial infections. Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterial pathogen that can most frequently be fatal in immunocompromised infected people. METHODS: We investigated the ex vivo effect of 1,25(OH)2D3 on monocyte-derived macrophages function against P. aeruginosa infection. RESULTS: Relative vitamin D receptor (VDR) mRNA expression was significantly increased in infected and 1,25(OH)2D3-treated macrophages compared to controls (p<0.01). Treatment with 1,25(OH)2D3 markedly resulted in up-regulation of nitric oxide (NO) and IL-1ß production and down-regulation of IL-10 levels (respectively, p=0.029, p=0.048 and p=0.008). Additionally, 1,25(OH)2D3 significantly increased M1/M2 macrophage ratio (p<0.05) and slightly reduced intracellular bacterial development. Furthermore, the arginase activity, P. aeruginosa phagocytosis and killing were significantly increased in cells that were both infected and 1,25(OH)2D3-treated compared to the infected, but not 1,25(OH)2D3-treated macrophages (respectively, p<0.001, p<0.01 and p<0.001). CONCLUSIONS: We show in this study that bioactive from of vitamin D [1,25-dihydroxyvitamin D3 (1,25D3)] can enhance M1 macrophage polarization and their bactericidal protective activity against P. aeruginosa. Future works would involve improving the treatment response through dose-dependent effect studies, both in ex vivo and in vivo models.