Healthy Immunity on Preventive Medicine for Combating COVID-19

Abstract

Immunomodulation is influenced by the consumption of nutrients, and healthy immunity is pivotal to defending an individual from a variety of pathogens. The immune system is a network of intricately regulated biological processes that is comprised of many organs, cellular structures, and signaling molecules. A balanced diet, rich in vitamins, minerals, and antioxidants, is key to a strengthened immune system and, thus, crucial to proper functioning of various physiological activities. Conversely, deficiencies of these micronutrients, involving impaired immunity, are linked to numerous health complications, along with a host of pathologies. Coronavirus disease 2019 (COVID-19) is a dangerous infectious disease caused by a β-form of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its genomic variants, which enter host cells upon binding to the angiotensin converting enzyme 2 receptors, and is associated with substantial morbidities and mortalities globally. Patients afflicted with COVID-19 display asymptomatic to severe symptoms, occurrences of which are multifactorial and include diverse immune responses, sex and gender differences, aging, and underlying medical conditions. Geriatric populations, especially men in comparison to women, regardless of their states, are most vulnerable to severe COVID-19-associated infections and complications, with fatal outcomes. Advances in genomic and proteomic technologies help one understand molecular events, including host-pathogen interactions and pathogenesis of COVID-19 and, subsequently, have developed a variety of preventive measures urgently, ranging from mask wearing to vaccination to medication. Despite these approaches, no unique strategy is available today that can effectively prevent and/or treat this hostile disease. As a consequence, the maintenance of a boosted immune system could be considered a high priority of preventive medicine for combating COVID-19. Herein, we discuss the current level of understanding underlining the contribution of healthy immunity and its relevance to COVID-19 molecular pathogenesis, and potential therapeutic strategies, in the management of this devastating disease.

Keywords: COVID-19; aging and underlying medical conditions; immune health; nutrition; therapeutic strategies; vitamins.

Figure 1

An overview of the immune system illustrating innate and adaptive immune system components. The innate immune system is composed mainly of physical and chemical barriers, and an initial inflammatory response made up of mast cells, neutrophils, macrophages, and natural killer cells. The adaptive immune response works through B- and T-lymphocytes creating a specialized and learned immune response to specific pathogens through antibodies and CD4+ and CD8+ cells. The adaptive and innate components are connected through dendritic cells that allow for the activation of the adaptive response once the innate system has recognized a threat to that organism.

Figure 2

Schematic representation of a COVID-19 virus and its different components, i.e., spike (S), membrane (M), nucleocapsid (N), envelope (E), and RNA structure (+ssRNA). Shown is a proposed mechanism of COVID-19 infection and resultant immune response, including parts from the innate and adaptive immune system. COVID-19 virus enters the body, then macrophages from the innate response are able to ingest some viruses and destroy them from phagocytosis. This releases viral components and antigens, which, in turn, activate the adaptive immune response through T- and B-lymphocytes creating specialized killer T-cells and specific antibodies to combat COVID-19 infections and kill the cells already infected with the virus.

Figure 3

A diagram illustrating the roles of various vitamins on different organ systems. All of these vitamins play important roles in the immune system, in addition to growth and development of various organs and, thus, physiological activities. Organ systems illustrated are the brain and nervous system, respiratory system, skeletal system, integumentary system, urinary system, reproductive system, immune system, digestive system, cardiovascular system, and ophthalmic system. Involvement of different vitamins to a particular organ is shown by a line pointing an arrow to the specific organ system.

Figure 4

Sex and gender differences and their connection to COVID-19. Several biological factors demonstrate a predisposition of males for higher levels of testosterone and androgen, less efficient innate immune responses, and less ability to repair damages, thus allowing for higher severe infection and mortality rates than their female counterparts. Females demonstrate certain factors such as the presence of estrogens and progesterone, more effective innate immune responses, and other conditions that limit COVID-19′s entry and subsequent infection. Independent of gender, age plays an important role in disease severity. Hormonal balances, lowered immune function, and increased comorbidity prevalence associated with age present opportunities for higher mortality rates and increased disease severity.

Figure 5

A diagrammatic representation illustrating cellular interaction of COVID-19; its replication process, assembly, release; and potential treatment options with antiviral drugs. COVID-19 virus enters the host through various means such as the inhalation of aerosol droplets. Then, the S1 subunit of the spike glycoprotein binds with the ACE-2 receptors (top left), which allows for viral ++ssRNA to be released into the host cell, where it employs cellular machinery to produce its RNA polymerase, its genetic material, and proteins needed for the viral capsule (middle-to-bottom left). Excluding the enzymatic and genomic components, other components are processed using endoplasmic reticulum and the Golgi complex (bottom middle). The viral ++ssRNA copies are then brought together and assembled with other viral components (middle bottom right). The newly produced virus exits the cell through exocytosis, where it can go on to infect more cells (top right). Antiviral drugs (top middle) such as Remdesivir, Molnupiravir, and Paxlovid are thought to disrupt this replication process, thus inhibiting disease progression.