Adjuvant Therapeutic Effects of Melatonin Agonist on Hospitalized Patients With Confirmed or Suspected COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) pandemic, also denominated Coronavirus Disease 2019 (COVID-19), is currently challenging health systems in Brazil and worldwide. The mortality rate of confirmed cases of COVID-19 in Brazil seems to be close to twice that of countries like Germany and Canada. (1-3) The resulted viral interstitial pneumonia can lead to severe hypoxemic respiratory failure, overcrowded intensive care units (ICUs), shortages of equipment and personnel, and increased mortality. (4-6)

Some reasons for higher mortality risk in Brazil can be related to an increased propensity of clinical worsening in hospitalized patients. Consequently, reducing the risk of clinical deterioration and prolonged disease duration in hospitalized patients with mild-to-moderate COVID-19 has become a priority to reduce the burden of such pandemic and the admission to ICUs. However, to our knowledge, few and complex specific interventions have been tested targeting outcomes related to a reduction of the immediate risk of severe disease and prolonged hospitalization in inpatients with mild-to-moderate clinical signs and symptoms.

Melatonin (N-acetyl-5-methoxytryptamine) is a hormone synthesized mainly by the pineal gland and also by other nonendocrine organs, including the immune system. Among its multiple properties, melatonin has demonstrated antiapoptotic, antioxidative, and anti-inflammatory roles exerted via both receptor-dependent and receptor-independent signalling cascades. (7,8) It has been suggested that melatonin receptors activation protects against organ injuries. (9-10). Additionally, melatonin receptors can mediate lower mortality rates after polymicrobial sepsis in animal models. (11)

Melatonin potentially modulates immune response by enhancing the secretion of anti-inflammatory cytokines including IL-10, which is involved in the Th2-like immune response. (12) IL-10 has effects on a myriad of cell types and, in lung cells under damaging circumstances, its production turns undermined. (13) Recent findings indicated that melatonin receptors are modulators of protective effects against acute lung injury induced by the ventilator in rats through the up-regulation of IL-10 production. (14) This evidence upsurged testing the effects of ramelteon, a potent and highly selective agonist of high-affinity melatonin receptors 1 (MT1) and MT2, which further displays antioxidative and anti-inflammatory properties. (15-17) Melatonin agonism may play a clinical role in individuals with acute lung injuries, including those induced by SARS-CoV-2 infection, which has not yet been investigated. The investigators designed a clinical trial testing standard care versus ramelteon 8mg under diverse clinical and laboratory outcomes related to the COVID-19 in hospitalized patients with this condition.

References