Efficacy of Aerosol Combination Therapy of 13 Cis Retinoic Acid and Captopril for Treating Covid-19 Patients Via Indirect Inhibition of Transmembrane Protease, Serine 2 (TMPRSS2)

Overview

Efficacy of Aerosol Combination Therapy of 13 Cis Retinoic Acid and Captopril for Treating Covid-19 Patients Via Indirect Inhibition of Transmembrane Protease, Serine 2 (TMPRSS2) Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) has infected over 20,000,000 people causing over 700,000 deaths. It has no currently approved treatments.Airborne SARS-CoV-2 infections in humans initiate from the virus entering nasal and airway epithelial cells through binding to angiotensin-converting enzyme 2 (ACE2). Transmembrane protease, serine 2 (TMPRSS2), a cellular protease that activates the SARS-CoV-2 spike protein, colocalizes with ACE2 and can prime SARS-CoV-2 fusion directly at the plasma membrane. Transmembrane protease, serine 2 (TMPRSS2) is an androgen receptor signaling target gene and an androgen-regulated cell-surface serine protease expressed predominantly in prostate and lung epithelial cell. TMPRSS2 is normally expressed several folds higher in the prostate relative to any other human tissue, though the normal physiological function(s) remains unknown. A study found that dihydrotestosterone (DHT) s a potent activator of TMPRSS2.On the other hand, Feily et al noted that low-dose isotretinoin (0.5 mg/kg/day for 15-20 weeks) in PCO patients with moderate to severe nodulocystic acne resulted in significant decreases in levels of serum total testosterone, prolactin, and dihydrotestosterone A study demonstrated that 13- cis -Retinoic acid competitively and reversibly inhibits dihydrotestosterone. Therefore, we suggest that 13- cis -Retinoic acid will downregulate TMPRSS2 expression thorough temporary preventing the effect of dihydrotestosterone (DHT) on the activation of TMPRSS2 gene expression. ACE inhibitors and ARBs are commonly taken by heart patients to reduce blood pressure and to treat heart failure.Earlier studies had cautioned that this class of drugs could possibly increase the risk for the novel coronavirus, SARS-CoV-2, infection and elevate COVID-19 severity. There is conflicting observational evidence about the potential clinical impact of ACE inhibitors and ARBs on patients with COVID-19. Select preclinical investigations have raised concerns about their safety in patients with COVID-19. On the other hand, Preliminary data hypothesise that angiotensin-converting enzyme (ACE) inhibitors and renin-angiotensin- aldosterone system (RAAS) inhibitors could benefit patients with COVID-19 by decreasing acute lung damage and preventing angiotensin-II-mediated pulmonary inflammation. Here in our review, we use established and emerging evidence based on the findings of previous studies and researches to propose that ACE inhibitors may benefit patients with COVID-19 via attenuating and abolishing the effect of androgenic hormones on inducing the expression of Transmembrane protease, serine 2 (TMPRSS2), even though, at the same time, ACE inhibitors cause an increase in the human cell surface receptor protein ACE2 which the novel coronavirus uses to enter and infect cells. A study on hypertensive rats demonstrated that using ACE inhibitors(captopril) abolished and attenuated the effect of dihydrotestosterone (DHT). In this study RAS inhibition exhibited beneficial effects on androgen-induced obesity and abolished the androgen-mediated increase in blood pressure (BP) observed in this model of PCOS. (83 ± 1 vs 115 ± 3 mmHg, p\<0.0001). A another study found that the angiotensin converting enzyme inhibitor captopril abolished testosterone effect and attenuates testosterone-induced benign prostatic hyperplasia in rats; a mechanistic approach. Captopril is a potent inhibitor of the angiotensin converting enzyme. These effects of testosterone were almost prevented by captopril (100 mg/kg). In conclusion, generally treatment with ACE inhibitors is associated with reduced androgen levels. Therefore,we think that Transmembrane protease, serine 2 (TMPRSS2) is an indirect target of ACE inhibitors and 13 cis retinoic acid As aresult, we hypothesize that any drug which downregulates TMPRSS2 expression through targeting AR, AR co-regulatory factors, or AR downstream transcription factors might be potentially effective against COVID-19 and is worth investigating under a clinical trial.. Keywords: COVID -19, Transmembrane protease, serine 2 (TMPRSS2), ACE inhibitors, ACE2.