Estrogen receptors and their roles in the immune and respiratory systems

Abstract

Estrogen is an important hormone for health in both genders. It is indispensable to glucose homeostasis, immune robustness, bone health, cardiovascular health, and neural functions. The main way that estrogen acts in the cells is through estrogen receptors (ERs). The presence of specific estrogen receptors is required for estrogen to have its characteristic ubiquitous action in almost all tissues. Estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) are the major isoforms of estrogen that are highly specific in humans and enable selective hormonal actions in different tissues. This article reviews some of the observed estrogen actions and effects in different tissues and cells through these specific receptors. This ubiquitous, almost ordinary hormone may reveal itself as a significant factor that helped us to better understand the complexity of the human immune system response against respiratory infections, including the COVID-19, and especially in the current state of this painful pandemic.

Role of estrogen receptors in health and disease

“…In addition, estrogens influence the adaptive immune response. Estrogens modulate the differentiation process and the function of neutrophils, macrophages, and natural killer cells ( 42 ).…”

Kaempferol's potential effects againstSARS‐CoV‐2 andCOVID‐19‐associated cancer progression and chemo‐resistance

“…Kaempferol as a natural flavonoids have been included in traditional medicine and used against COVID-19 and several other diseases (Firoz & Talwar, 2022). Several studies separately investigated Kaempferol, or its nanoparticles with more bioavailability and solubility, effects against different cancer types or COVID-19; however, it is not completely considered together (Millas & Duarte Barros, 2021). This is because the therapeutic strategies of kaempferol against cancer cells may have side effects on SARS-CoV-2 treatment and conversely, in patients suffering from the two diseases.…”

“…A significant effect of estrogen on immune responses occurs as an innate or acquired response, and estrogen receptors can be found throughout the body, including in the immune system. It is believed that ERs regulate cells and pathways in the innate and adaptive immune systems to significantly alter immune cell activity (Millas & Duarte Barros, 2021). In this regard, Lemes.…”

Sex hormones and immune system: Menopausal hormone therapy in the context of COVID-19 pandemic

“…The net effect of estrogens on immune functionalities is anti-inflammatory. Studies show that physiological estrogen levels in premenopausal women suppress the release of pro-inflammatory cytokines, notably interleukins IL-6 and IL-8, and tumor necrosis factor α (TNF-α) ( 38 ). By contrast, low physiological estrogen levels in postmenopausal women fail to counteract the release of pro-inflammatory cytokines.…”