Academy Lecture

Immune system; the key towards tackling respiratory infections

The epithelial lining of the respiratory tract is continually exposed to the external environment due to respiration; hence the lungs are a vulnerable site for infection. There are several infections globally constituting a significant disease burden. Respiratory infections are one of the leading causes of death, especially for children under 5 years. Early life respiratory infections are commonly caused by viruses, especially the rhinoviruses, influenza, etc. Those groups of infections are mainly restricted to the upper respiratory tract infection. The severity varies from mild or asymptomatic states to severe forms with wheezing, bronchiolitis, or pneumonia.


Host immune responses

The airway epithelium is the primary barrier to infection by respiratory pathogens.  The microbes must first penetrate the mucus layer. This mucus layer is the first line of defence against the pathogens. Once such fails, the innate immune system is thus stimulated and activated to fight back. Different forms of respiratory infection could occur, ranging from viral to bacterial infections. The host immune response plays a crucial role in preventing or fighting already existing respiratory infection(s).

Nearly all body cells have mechanisms to detect viruses (and other microbial pathogens) by pattern recognition receptors (PRRs). PRRs are important for detection of viruses. These receptors are activated in respiratory epithelial cells, typically among the first cell types to be infected, is critical in limiting virus spread and alerting the immune system to respond to the infection. Activation of PRRs in these cells by virus infection triggers production and release of interferons (IFNs) and other proinflammatory mediators (e.g., cytokines, chemokines, and antimicrobial peptides) which initiate the host innate and adaptive immune response.

The airway epithelial cells respond by stimulating a specific amount of interferon, which helps fight against the viral infections that may be associated with the respiratory system. There are several cytokines, chemokines, and factors that are also produced by the epithelial cells, which also helps provide protective functions against infection; however, in certain situations, this could also cause some pathological issues. Alternately virus’s activities may supersede that of the epithelial responses, which results in the release of some proinflammatory cytokines, NO, and Reactive Oxygen Species (ROS) from the epithelium and leukocytes hence increase epithelial permeability while also disrupting the integrity leading to more injury.

Alveolar macrophages contribute its role in the initiation of the host immune response, which subsequently helps in viral clearance. Neutrophils are immune cells that also arrive at the site of infection to help eliminate the infected cells (which include pathogens, dead cells, and debris).

The adaptive immune responses towards viral infections occur over time. The primary purpose is to help in complete viral clearance to assist in the final elimination of infection. This adaptive response involves humoral immune response (B-cells and CD4 helper T cells). These cells help in neutralizing opsonization and inactivation of the virions. Cell-mediated immune response CD8+ T cells are responsible for the clearance of intracellular pathogens such as viruses to eliminate infected cells. The immunopathology of respiratory virus infections provides an overview of the complex interplay between the virus, viral factors, resident respiratory cells, and the host immune system.



Supplements play a crucial role in helping to boost the host immune system by supporting the biochemical reactions that involve in the immune system. Vitamins help in providing powerful antioxidants, which also helps fight against infections. Nutrients and vitamins help in building cell structure integrity. Lack of those nutrients contributes to lowered immunity. Some supplements have an anti-inflammatory property, which also helps play a crucial role in fighting against respiratory infections. Several bacterial and viral infections have caused a lot of health issues. All that we need is to help boost our immunity for better immune response. Apart from using a medication, both innate and adaptive immune response all works together to ensure the host health. In achieving such goals, there are supplements that you need to carefully select from to give you all essential macro and micronutrients that help boost the immune system.

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