Activation of dengue virus-specific T cells modulates vascular endothelial growth factor receptor 2 expression

VEGF-A enhances the cytotoxic function of CD4+ cytotoxic T cells via the VEGF-receptor 1/VEGF-receptor 2/AKT/mTOR pathway

BACKGROUND

CD4⁺ cytotoxic T cells (CD4 CTLs) are CD4⁺ T cells with major histocompatibility complex-II-restricted cytotoxic function. Under pathologic conditions, CD4 CTLs hasten the development of autoimmune disease or viral infection by enhancing cytotoxicity. However, the regulators of the cytotoxicity of CD4 CTLs are not fully understood.

METHODS

To explore the potential regulators of the cytotoxicity of CD4 CTLs, bulk RNA and single-cell RNA sequencing (scRNA-seq), enzyme-linked immunosorbent assay, flow cytometry, quantitative PCR, and in-vitro stimulation and inhibition assays were performed.

RESULTS

In this study, we found that VEGF-A promoted the cytotoxicity of CD4 CTLs through scRNA-seq and flow cytometry. Regarding the specific VEGF receptor (R) involved, VEGF-R1/R2 signaling was activated in CD4 CTLs with increased cytotoxicity, and the VEGF-A effects were inhibited when anti-VEGF-R1/R2 neutralizing antibodies were applied. Mechanistically, VEGF-A treatment activated the AKT/mTOR pathway in CD4 CTLs, and the increases of cytotoxic molecules induced by VEGF-A were significantly reduced when the AKT/mTOR pathway was inhibited.

CONCLUSION

In conclusion, VEGF-A enhances the cytotoxicity of CD4 CTLs through the VEGF-R1/VEGF-R2/AKT/mTOR pathway, providing insights for the development of novel treatments for disorders associated with CD4 CTLs.

[Value of sTREM-1 in serum and bronchoalveolar lavage fluid, APACHE II score, and SOFA score in evaluating the conditions and prognosis of children with severe pneumonia]

OBJECTIVE

To study the significance of the level of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in serum and bronchoalveolar lavage fluid (BALF), Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and Sequential Organ Failure Assessment (SOFA) score in evaluating the conditions and prognosis of children with severe pneumonia.

METHODS

A total of 76 children with severe pneumonia who were admitted from August 2017 to October 2019 were enrolled as the severe pneumonia group. According to the treatment outcome, they were divided into a non-response group with 34 children and a response group with 42 children. Ninety-four children with common pneumonia who were admitted during the same period of time were enrolled as the common pneumonia group. One hundred healthy children who underwent physical examination in the outpatient service during the same period of time were enrolled as the control group. The serum level of sTREM-1, APACHE II score, and SOFA score were measured for each group, and the level of sTREM-1 in BALF was measured for children with severe pneumonia. The correlation of the above indices with the severity and prognosis of severe pneumonia in children was analyzed.

RESULTS

The severe pneumonia group had significantly higher serum sTREM-1 level, APACHEII score, and SOFA score than the common pneumonia group and the control group (P<0.05). For the children with severe pneumonia, the non-response group had significant increases in the levels of sTREM-1 in serum and BALF and SOFA score on day 7 after admission, while the response group had significant reductions in these indices, and there were significant differences between the two groups (P<0.05). Positive correlation was found between any two of serum sTREM-1, BALF sTREM-1, and SOFA score (P<0.05). APACHE II score was not correlated with serum sTREM-1, BALF sTREM-1, and SOFA score (P>0.05).

CONCLUSIONS

The level of sTREM-1 in serum and BALF and SOFA score can be used to evaluate the severity and prognosis of severe pneumonia in children.

In vitro and in silico Models to Study Mosquito-Borne Flavivirus Neuropathogenesis, Prevention, and Treatment

Mosquito-borne flaviviruses can cause disease in the nervous system, resulting in a significant burden of morbidity and mortality. Disease models are necessary to understand neuropathogenesis and identify potential therapeutics and vaccines. Non-human primates have been used extensively but present major challenges. Advances have also been made toward the development of humanized mouse models, but these models still do not fully represent human pathophysiology. Recent developments in stem cell technology and cell culture techniques have allowed the development of more physiologically relevant human cell-based models. In silico modeling has also allowed researchers to identify and predict transmission patterns and discover potential vaccine and therapeutic candidates. This review summarizes the research on in vitro and in silico models used to study three mosquito-borne flaviviruses that cause neurological disease in humans: West Nile, Dengue, and Zika. We also propose a roadmap for 21st century research on mosquito-borne flavivirus neuropathogenesis, prevention, and treatment.