Introduction: Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by a novel coronavirus, SARS-CoV-2. The SARS-CoV-2 virus infects the host human cells through its surface receptors human angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2). This study aims to investigate the effects of high glucose on the expression of ACE2 and TMPRSS2 receptors using macrophage (CD14+ve cells) as a biomarker in vivo and human endothelial cells in vitro.

Methods: Mononuclear cells were isolated by Ficoll density centrifuge method from whole blood. CD14 cells were isolated from MNCs by MACS kit. The migratory capacity of CD14 cells was evaluated using the CytoSelect Migration Assay kit. CFU-Hill colony formation assay was also done on MNCs. In vitro studies using HUVEC were done by culturing the cells in normal glucose (NG, 5.5mmol/L) or high glucose (HG, 20 mmol/L), followed by mRNA assays at day 3 and 7.

Results: All the COVID patients had high glucose levels (>300 mg/dl). The migratory function of CD14 cells show moderately increased migration compared to similar hematopoietic cells from nondiabetic COVID negative patients. In general, CD14 cells showed low expression of ACE2 and/or TMPRSS2 in all samples. For our in-vitro experiments using cultured HUVEC mRNA expression of ACE2 and/or TMPRSS2 receptors were higher in HG compared to NG at day 7. No expression was observed at day 3 either in NG or HG. An elevated gene expression of inflammatory marker, IL-6 and apoptosis marker, P53 were observed in HG at both days 3 and 7.

Conclusions: A low expression of SARS-CoV-2 receptors were observed on CD14 macrophage cells from patients which may indicate poor recognition of the virus particle by CD14 cells. Higher expression of the SARS-CoV-2 receptors were noted when HUVEC cells were cultured in HG for 7 days.

Conclusion: Longer exposure of human endothelial cells in high glucose condition increase the SARS-CoV-2 receptor expression.


S. Nandula: None. R. Janapala: None. S. Sen: None.


Clinical and Translational Science Institute at Children’s National

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