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.

miRNA-23b as a biomarker of culture-positive neonatal sepsis.

BACKGROUND: Neonatal sepsis remains an important cause of morbidity and mortality. The ability to quickly and accurately diagnose neonatal sepsis based on clinical assessments and laboratory blood tests remains difficult, where haemoculture is the gold standard for detecting bacterial sepsis in blood culture. It is also very difficult to study because neonatal samples are lacking. METHODS: Forty-eight newborns suspected of sepsis admitted to the Neonatology Department of the Mother-Child Specialized Hospital of Tlemcen. From each newborn, a minimum of 1-2 ml of blood was drawn by standard sterile procedures for blood culture. The miRNA-23b level in haemoculture was evaluated by RT-qPCR. RESULTS: miR-23b levels increased in premature and full-term newborns in early onset sepsis (p < 0.001 and p < 0.005 respectively), but lowered in late onset sepsis in full-term neonates (p < 0.05) compared to the respective negative controls. miR-23b levels also increased in late sepsis in the negative versus early sepsis negative controls (p < 0.05). miR-23b levels significantly lowered in the newborns who died from both sepsis types (p < 0.0001 and p < 0.05 respectively). In early sepsis, miR-23b and death strongly and negatively correlated (correlation coefficient = - 0.96, p = 0.0019). In late sepsis, miRNA-23b and number of survivors (correlation coefficient = 0.70, p = 0.506) positively correlated. CONCLUSIONS: Lowering miR-23b levels is an important factor that favours sepsis development, which would confirm their vital protective role, and strongly suggest that they act as a good marker in molecular diagnosis and patient monitoring.