Repurposing prolactin as a promising immunomodulator for the treatment of COVID-19: Are common Antiemetics the wonder drug to fight coronavirus?

Prolactin (PRL), the well-known lactogenic hormone, plays a crucial role in immune function given the fact that long term hypoprolactinemia (serum prolactin level below normal) can even lead to death from opportunistic infection. High blood PRL level is known to provide an immunological advantage in many pathological conditions (with some exceptions like autoimmune diseases) and women, because of their higher blood PRL level, get an advantage in this regard. It has been reported that by controlled enhancement of blood PRL level (within the physiological limit and in some cases a little elevated above the normal to induce mild hyperprolactinemia) using dopamine antagonists such immune-stimulatory advantage can led to survival of the patients in many critical conditions. Here it is hypothesized that through controlled augmentation of blood PRL level using dopamine antagonists like domperidone/metoclopramide, which are commonly used drugs for the treatment of nausea and vomiting, both innate and adaptive immunity can be boosted to evade or tone down COVID-19. The hypothesis is strengthened from the fact that at least seven little-understood salient observations in coronavirus patients can apparently be explained by considering the role of enhanced PRL in line with the proposed hypothesis and hence, clinical trials (both therapeutic and prophylactic) on the role of enhanced PRL on the course and outcome of coronavirus patients should be conducted accordingly.