Broad humoral immunity generated in mice by a formulation composed of two antigens from the Delta variant of SARS-CoV-2.

Due to the rapid development of new variants of SARS-CoV-2 as well as the real threat of new coronavirus zoonosis events, the development of a preventive vaccine with a broader scope of functionality is highly desirable. Previously, we reported the functionality of a nasal formulation containing the nucleocapsid protein and the receptor-binding domain (RBD) of the spike protein of the Delta variant of SARS-CoV-2 combined with the ODN-39M adjuvant. This combination induced cross-reactive immunity in mucosal and systemic compartments at the sarbecovirus level. In the present study, we explored the magnitude of the immunity generated in BALB/c mice by the same formulation with alum added as an additional adjuvant, to enhance the humoral immunity against the two antigens. Animals were immunized with three doses of the bivalent formulation, administered by subcutaneous route. Humoral immunity was tested by ELISA, and the neutralizing capacity of the resulting antibodies (Abs) was evaluated using a surrogate test and a vesicular stomatitis virus (VSV) pseudovirus-based assay. Cell-mediated immunity was also investigated using an IFN-γ ELISpot assay. High levels of antibodies against both antigens (N and RBD) were obtained upon immunization. Anti-RBD Abs with neutralizing capacity reacted with the RBD of three SARS-CoV-2 variants tested, including Omicron. Abs recognizing the nucleocapsid proteins of SARS-CoV-1 and the SARS-CoV-2 Delta and Omicron variants were also detected. Taken together, these results suggest that this bivalent formulation could be an attractive component of a pancorona vaccine able to broaden the scope of humoral immunity against both antigens. This will be particularly important for the reinforcement of immunity in previously vaccinated and/or infected populations.

Wnt5a-Flt1 activation contributes to preterm altered cerebral angiogenesis after prenatal inflammation.

OBJECTIVE: Intraventricular hemorrhage (IVH) causes morbidity and mortality in preterm infants and prenatal exposure to inflammation contributes to brain injury. Moreover, prenatal exposure to severe inflammation increases the risk of IVH in preterm neonates. The current study investigated whether intrauterine exposure to inflammation affects cerebral angiogenesis and its underlying mechanisms. METHODS: Wnt5a, flt1, and vascular endothelial growth factor (VEGF)-A levels in cord blood serum (stored in a bio-bank) of the enrolled patients were measured via enzyme-linked immunosorbent assay. A preterm prenatal inflammation exposure model was established in rats by intraperitoneal injection intraperitoneally during pregnancy. Angiogenesis of cerebral tissue was analyzed using immunohistochemistry. Wnt5a, flt1, and VEGF-A expression levels were measured via immunohistochemistry, immunofluorescence, or western blotting. The correlation between Wnt5a and flt1 expression and the cerebral vessel area was also analyzed. RESULTS: The Wnt5a and flt1 levels in the cord blood serum were significantly higher in the amnionitis group than in the non-amnionitis group. The VEGF-A level in the cord blood serum was significantly lower in the amnionitis group. In the rat model, preterm rats in the prenatal inflammation group exhibited increased microglial cell infiltration and decreased vessel area and diameter in the cerebral tissue compared to the control group. Wnt5a was located in microglial cells, and Wnt5a and flt1 expression in brain tissue significantly increased after prenatal lipopolysaccharide (LPS) exposure. VEGF-A expression declined after prenatal LPS exposure. The cerebral vessel area was negatively correlated with Wnt5a and flt1 expression. CONCLUSION: Disordered cerebral angiogenesis is associated with increased Wnt5a-Flt1 activation in microglial cells after exposure to intrauterine inflammation.

Autologous cord blood mononuclear cell infusion for the prevention of bronchopulmonary dysplasia in very preterm monozygotic twins: A study protocol for a randomized, placebo-controlled, double-blinded multicenter trial.

Background: Preterm-associated complications remain the main cause of neonatal death. Survivors face the challenges of short- and long-term complications. Among all complications, bronchopulmonary dysplasia (BPD) remains the first important cause of neonatal mortality and morbidity. Current treatment does not address this main preterm complication. Cord blood is regarded as a convenient source of stem cells. The paracrine bioactive factors of stem cells contribute to tissue repair and immune modulation. Our clinical studies and those of others have shown that cord blood cell infusion is both safe and possibly effective in the prevention and treatment of BPD. The therapeutic use of cord blood has emerged as a promising therapy. However, the genetic heterogeneity between control and intervention groups may reduce the comparability especially among small sample trials. The purpose of this study protocol is to investigate the effects of autologous cord blood mononuclear cell (ACBMNC) infusion on the prevention of BPD in very preterm monozygotic twins of less than 32 gestation weeks. Methods: In this prospective, randomized, placebo-controlled, double-blinded multicenter clinical trial, 60 pairs of monozygotic twin preterm neonates of less than 32 weeks admitted to the Neonatal Intensive Care Unit are randomly assigned to receive intravenous ACBMNC infusion (targeted at 5 × 107 cells/kg) or placebo (normal saline) within 24 h after birth in a 1:1 ratio. The primary outcome will be survival without BPD at 36 weeks of postmenstrual age. The secondary outcomes will include the mortality rate, BPD severity, other common preterm complication rates, respiratory support duration, length and cost of hospitalization, and long-term respiratory and neurodevelopmental outcomes during a 2-year follow-up. Furthermore, we will perform single-cell RNA sequencing for cord blood cells and blood cells 3-10 days after intervention and detect whether reactive oxygen species and inflammatory cytokines are present. Conclusion: This will be the first randomized, placebo-controlled, double-blinded trial to evaluate the efficacy of ACBMNC infusion to prevent BPD in monozygotic twin premature infants and investigate the underlying protective mechanisms. The results of this trial will provide valuable clinical evidence for translational application of cord blood cell therapy in very preterm infants.Trial registration: ClinicalTrials.gov, NCT05087498, registered 10/09/2021, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S000BAD7&selectaction=Edit&uid=U0002PLA&ts=2&cx=qvyylv.