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Table of Contents
Year : 2020  |  Volume : 6  |  Issue : 2  |  Page : 30-32

Host airway defense system

Professor, Department of Nephrology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Date of Submission17-Aug-2020
Date of Acceptance19-Aug-2020
Date of Web Publication01-Sep-2020

Correspondence Address:
Dr. Anita Saxena
Department of Nephrology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jrnm.jrnm_21_20

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How to cite this article:
Saxena A. Host airway defense system. J Renal Nutr Metab 2020;6:30-2

How to cite this URL:
Saxena A. Host airway defense system. J Renal Nutr Metab [serial online] 2020 [cited 2022 Oct 6];6:30-2. Available from: http://www.jrnm.in/text.asp?2020/6/2/30/294187

The respiratory tract is exposed to billions of particles and pathogens daily. Hippocrates was the first effort to epitomize the knowledge of respiration and lungs Viral infections constitute a class of viral diseases which have high mutation rates and high degree of dissimilarity between viruses' strains that hinder the development of broad-spectrum antiviral agents. Therefore, nature has provided human body a natural innate immune system which is designed to repel viral infections.[1] This classroom reading will identify the natural immune system's defense troops and their roles and look at simple ways to support it.

Mucus and mucins are the first line of natural defense in the host airway defense machinery. Its (mucus) fundamental importance is emphasized by its presence throughout the evolutionary pathways. Mucus is a mixture of water, ions, glycoproteins, proteins, and lipids.[2],[3],[4],[5] It plays a vital role in protecting the lungs from pathogens and toxins by forming the first line of innate defense in the respiratory tract.

Airway mucins are major components of the soluble layer and/or viscoelastic gel that comprises lung mucus in healthy airways and contributes to the mucociliary defense system that protects the lungs against pathogens and environmental toxins. Airway mucins are major components of the soluble layer and/or viscoelastic gel that comprise lung mucus in healthy airways and contribute to the mucociliary defense system that protects the lungs against pathogens and environmental toxins. Mucins are produced by epithelial tissues, and are classified into two groups (secreted and membrane bound), often performing inhibitory role. They are a family of high molecular weight, heavy glycoconjugates (glycosylated proteins) with repeat tandem domains rich in serine and threonine sites for O-glycosylation.[5],[6] These highly glycosylated proteins form a protective barrier and have a role in cell signaling by interaction with their specific receptors, the glycan-binding proteins (GBPs) on immune cells. The characteristic that attracts attention of mucins is their ability to form gel (gel-forming/secreted mucins at locus 11p15 [MUC2, MUC5AC, MUC5B, and MUC6]; membrane-bound mucins at locus 7q22, 3q, and 1q21 [MUC1, MUC3A, MUC3B, MUC4, MUC12, MUC13, and MUC17]);[6],[7],[8],[9],[10],[11],[12],[13],[14] therefore, they are a key component in most gel-like secretions, serving functions from lubrication to cell signaling to form chemical barriers. Mucins bind to pathogens as part of the immune system.

Ninety percent of the most prevalent secreted mucins are MUC5AC and MUC5B in the lungs, and only 10% are membrane-bound mucins (MUC1, MUC4, and MUC16). Recent studies utilizing RNA in situ hybridization and immunohistochemistry in normal lung show that although MUC5B is constitutively secreted throughout the conducting airway, except for the terminal bronchiole, the majority is produced in the distal airway by the secretory epithelial cells.[5],[6] MUC5AC is expressed predominantly in the proximal airway, its production being triggered by infection and cigarette smoke, as well as in allergic (type 2) inflammation.[1]

Viral infections trigger innate immune response to detect pathogen and their signaling to produce chemokines and cytokines, including type I interferon (IFN), to limit viral replication, and to spread to neighboring cells. To establish antiviral state, the Type I IFN released by infected cells binds to IFN receptor and triggers signaling pathways to induce expression of IFN-stimulated genes.

The selectins, consisting of E-, L-, and P-selectin, are a family of single-pass transmembrane cell adhesion proteins with an outer carbohydrate recognition domain that are widely expressed on endothelium, leukocytes, and platelets. The selectins play a key role in leucocyte trafficking out of the circulation and into the tissues. Selectin ligand expression on airway mucins is during inflammation, but what is much less clear is whether there are physiological selectin ligands expressed on mucins in the healthy lung that play a role in normal lung homeostasis.[6],[15],[16],[17]

Siglecs, GBPs of lectin family, are differentially expressed on restricted subsets of immune cells. The siglecs are immunomodulatory receptors and ligand engagement usually results in reduced inflammation though immune inhibitory sequences on cytoplasmic tails. Galectin (Gal)-1 has both pro- and anti-inflammatory features and has been shown to interact with MUC16. Gal-1 agonists are therapeutic targets as anti-inflammatories, but there are no clinical studies at the moment in chronic lung disease.

Threonine, an essential amino acid, which must be obtained from diet is found in the mucous membrane. Discovered in 1936 by William Cumming Rose, it is a constituent of Vitamin B-12. In humans, the gene for threonine dehydrogenase is an inactive pseudogene (nonfunctional segments of DNA that resemble functional genes). The amino acid gets its name from threonic acid (C4H8O5) because of its similarity in structure. A balanced protein-rich diet with fortified foods or supplements of Vitamin B-12 and selenium [18],[19],[20],[21] can maintain integrity of mucus defense system.[17],[18],[19],[20],[21],[22],[23],[24],[25],[26],[27]

  From Hippocrates' Wisdom Chest Top

Hippocrates [28] left a legacy for maintaining human body in shape with nature's gifts. His medicine was humble and passive. He believed in “the healing power of nature” Vis_medicatrix_naturae”vis medicatrix naturae” in Latin. Of dozens of simple ways advised by Hippocrates on how to keep immune systems vibrant and enhance innate energy here are a few lessons which can be followed during SARS-2 COV-2 Pandemic. Hippocrates insisted on importance of diet, exercise, and thought in the maintenance of health.[23],[24],[25],[26],[27] Imbalance and stress in any of these areas weakens the immune system.

  1. Devour oxygen. Modernization has disconnect us from the natural world, depriving us from positive influence of nature. Surround yourself with nature to connect with self. Stay in or near oxygen-rich environments like running streams, greenhouses (you can create one at home) and learn to breathe deeply without exerting yourself. Eat plenty of raw, oxygen-rich green foods. Use safe oxygen products in drinking water. In view of pandemic which makes it necessary to remain indoors for most of the day, use an oxygen-producing air purifier in home and at place of work.
  2. Drink pure distilled water and keep yourself well hydrated. Body weight, body surface area, and other related factors influence the water requirements of an individual. Adults should consume 40 mL of water per kilogramme of body weight (keeping in mind country of residence and season)[29],[30],[31].
  3. Prefer vegetarian food and of which 75% (or higher) should be raw like sprouts and green vegetables which provide most balanced and nourishing diet.
  4. Drink freshly-made sprout/vegetable green drinks.
  5. Use blue-green algae daily. Blue-green algae has high amounts of protein, iron, and other minerals and has beneficial effects on the immune system, inflammation, and against viral infections. Individuals
  6. Avoid using foods and condiments that contain immune-suppressing ingredients (prefer low antigen content (LAC) diet), like salt, refined sugars and flours, dairy products, vinegars, heated oils, food preservatives and colourings.
  7. How safe are you with microwave cooking?
  8. Include moderate exercise (20-30 minutes) in daily routine. Exercise will preserve lean mass in those confined at homes.
  9. Detoxify your immune system once a week. Switch over to freshly-made juices and water
  10. A positive attitude improves mental and physical health. Try it.

Keep your defense system healthy. Keep smiling.

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Conflicts of interest

There are no conflicts of interest

  References Top

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