Serum glucose-regulated protein 78 (GRP78) levels in COVID-19-associated mucormycosis: results of a case–control study

Abstract

Background: In experimental models, the expression of glucose-regulated protein 78 (GRP78) in endothelial cells played a role in the pathogenesis of mucormycosis. However, the role of GRP78 in COVID-19-associated mucormycosis (CAM) has not been studied. We hypothesized that serum GRP78 levels are elevated in subjects with CAM. Objective: To compare the serum GRP78 levels in subjects with CAM and COVID-19 controls without mucormycosis. Design And Setting: We performed a hospital-based, case–control study between 1 April 2021 and 31 May 2021. Participants: We enrolled 24 subjects each of CAM and COVID-19 subjects without mucormycosis. We also measured serum GRP78 levels in ten healthy controls. Exposure: The primary exposure studied was serum GRP78 concentration, estimated using a commercially available ELISA kit in stored serum samples. Results: We found the mean ± standard deviation (SD) serum GRP78 levels significantly higher (p = 0.0001) among the CAM (374.3 ± 127.3 pg/mL) than the COVID-19 (246.4 ± 67.0 pg/mL) controls. The proportion of subjects with an abnormal GRP78 level (> mean [184.8 pg/mL] plus two SD [23.2 pg/mL] of GRP78 from healthy participants) was 87.5% and 45.8% in the CAM group and COVID-19 controls, respectively. Serum GRP78 level was independently associated with CAM (odds ratio 1.011; 95% confidence interval [1.002–1.019]) after adjusting for diabetes mellitus and hypoxemia during acute COVID-19. Conclusion: Serum GRP78 levels were significantly higher in CAM than in COVID-19 controls. Further studies are required to the role of GRP78 in the pathogenesis of CAM.