SARS-CoV-2 Envelope-mediated Golgi pH dysregulation interferes with ERAAP retention in cells (preprint)

Endoplasmic reticulum (ER) aminopeptidase associated with antigen processing (ERAAP) trims peptide precursors in the ER for presentation by major histocompatibility (MHC)-I molecules to surveying CD8+T-cells. This function allows ERAAP to regulate the nature and quality of the peptide repertoire and, accordingly, the resulting immune responses. We recently showed that infection with murine cytomegalovirus leads to a dramatic loss of ERAAP levels in infected cells. In mice, this loss is associated with the activation of QFL T-cells, a subset of T-cells that monitor ERAAP integrity and eliminate cells experiencing ERAAP dysfunction. In this study, we aimed to identify host factors that regulate ERAAP expression level and determine whether these could be manipulated during viral infections. We performed a CRISPR knockout screen and identified ERp44 as a factor promoting ERAAP retention in the ER. ERp44's interaction with ERAAP is dependent on the pH gradient between the ER and Golgi. We hypothesized that viruses that disrupt the pH of the secretory pathway interfere with ERAAP retention. Here, we demonstrate that expression of the Envelope (E) protein from Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) leads to Golgi pH neutralization and consequently decrease of ERAAP intracellular levels. Furthermore, SARS-CoV-2-induced ERAAP loss correlates with its release into the extracellular environment. ERAAP's reliance on ERp44 and a functioning ER/Golgi pH gradient for proper localization and function led us to propose that ERAAP serves as a sensor of disturbances in the secretory pathway during infection and disease.

The Use of Adjuvant Therapy in Preventing Progression to Severe Pneumonia in Patients with Coronavirus Disease 2019: A Multicenter Data Analysis (preprint)

ABSTRACT IMPORTANCE Coronavirus disease 2019 (COVID-19) is a global pandemic associated with high mortality and effective treatment to prevent clinical deterioration to severe pneumonia has not yet been well clarified. OBJECTIVE To investigate the role of several adjuvant treatments in preventing severe pneumonia in patients with COVID-19. DESIGN, SETTING, AND PARTICIPANTS Multicenter, retrospective cohort study of 564 consecutively hospitalized patients with confirmed COVID-19 at Third Xiangya Hospital of Central South University, Changsha Public Health Treatment Center, First Hospital of Yueyang, Junshan People's Hospital of Yueyang, Central Hospital of Shaoyang, Central Hospital of Xiangtan, Second Hospital of Changde, Central Hospital of Loudi, and First Affiliated Hospital of University of South China in Hunan province from January 17, 2020 to February 28, 2020; The final date of follow-up was March 15, 2020. EXPOSURES Nonspecific antivirals (arbidol, lopinavir/ritonavir, and interferon ), antihypertensives, and chloroquine. MAIN OUTCOMES AND MEASURES The development of severe COVID-19 pneumonia; Demographic, epidemiological, clinical, laboratory, radiological, and treatment data were collected and analyzed. RESULTS Of 564 patients, the median age was 47 years (interquartile range, 36-58 years), and 284 (50.4%) patients were men. Sixty-nine patients (12.2%) developed severe pneumonia. Patients who developed severe pneumonia were older (median age of 59 and 45 years, respectively), and more patients had comorbidities including hypertension (30.4% and 12.3%, respectively), diabetes (17.4% and 6.7%, respectively), and cardiovascular disease (8.7% and 3.2%, respectively) and presented with fever (84.1% and 60.4%, respectively) and shortness of breath (10.1% and 3.8%, respectively) compared with those who did not. Nonspecific antiviral therapy did not prevent clinical progression to severe pneumonia, although fewer hypertensive patients on angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers (ACEI/ARB) therapy developed severe pneumonia in contrast with those on non-ACEI/ARB antihypertensive therapy (1 of 16 [6.3%] patients and 16 of 49 [32.7%] patients, respectively [difference, 26.4%; 95% CI, 1.5% to 41.3%]). Multivariate logistic regression analysis showed that hypertension without receiving ACEI/ARB therapy was an independent risk factor (odds ratio [OR], 2.07; 95% CI, 1.07 to 4.00) for developing severe pneumonia irrespective of age. Besides, none of patients treated with chloroquine developed severe pneumonia, though without significance (difference, 12.0%; 95% CI, -3.5% to 30.0%) by propensity score matching. CONCLUSIONS AND RELEVANCE Hypertensive patients on ACEI or ARB may be protective from severe pneumonia in COVID-19 and hence these therapies should not be ceased unless there is a strong indication or further epidemiological evidence. Though none of the current antiviral and immunoregulation therapy showed benefit in preventing COVID-19 progression, chloroquine deserved further investigation.