Modulation of angiotensin converting enzyme 2 activity in human mesangial cells treated with hydroxychloroquine
Authors: Bello Marina , Magri Lucas , Yokota Rodrigo , Oliveira Lilian , Casarini Dulce 
Published: May 2023

Introduction: The occurrence of the first case caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the coronavirus disease (COVID-19), was described in Wuhan, China, by the end of 2019, and due to its high transmissibility, the virus had a fast dissemination throughout the world. One of COVID-19 complications is acute kidney injury. The SARS-CoV-2 possesses a membrane protein which interacts with a receptor on the host cell’s surface, the angiotensin converting enzyme 2 (ACE2), important for the virus internalization into the host cell. In the beginning of the pandemic, little was known about effective drugs against it, so hydroxychloroquine (HCQ) was indicated for both treatment or prophylactic measure against COVID-19, which is currently known for not having a protective action, and may affect the kidney depending on the concentration used. The kidney which is essential in maintaining the organism’s homeostasis through the renin-angiotensin-aldosterone system (RAAS), was also one of the main target organs in the COVID-19. The basic kidney unity, the nephron, possesses mesangial cells, which are part of both the glomerulus and the mesangial matrix, and synthetize some of the RAAS components. An imbalance in the RAAS may lead to arterial hypertension, one of the comorbidities that may cause the COVID-19 aggravation. Objectives: To evaluate the RAAS components modulation in immortalized human mesangial cells (IHMC) under treatment with hydroxychloroquine (HCQ), Losartan (Los) and the association of both medicines (Los+HCQ). Methods: The IHMC were treated for 4 hours with HCQ 50 μM or 150 μM, and Los 1 μM to evaluate the effects on ACE, ACE2 and renin activities. Protein quantification and cell viability with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay were assessed by absorbance. ACE, ACE2 and renin proteolytic activities were evaluated by fluorometric assays using the substrates Z-Phe-His-Leu, APK(Dnp) and ABZ-DRVYIHPFHLVIHNQ-EDDnp, respectively. Results: Cell viability decreased after treatment with both drugs, either alone or combined. The renin activity showed no significant variation in the three groups studied. The ACE2 activity was lowered by Los, Los+HCQ, but not by HCQ alone. The expression of ACE2 detected by immunofluorescence presented no significant variation compared to the control. Conclusion: The decrease in ACE2 activity in all studied groups compared to the control, despite the protein synthesis remaining similar to the control, demonstrates that fragments of Angiotensins I and II can inhibit this activity. The ACE2 expression maintained similar levels despite treatments, which favors the SARS-CoV-2 infection process. The mechanisms involved in this process must be studied, considering that inhibiting the ACE2 activity implies in a decrease of Ang 1-7 production, compromising vasodilation. (Supported by CAPES and FAPESP This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.