HOW THE HOST CELL ACTS AGAINST SARS COV 2?

Today I am going to talk about how our body reacts to the infection of corona virus.

To know how it enters the cell and hacks it to produce its own copy click here.

So, let’s start: -

After infecting the cells and making multiple copies, these copies moves out from the cell by exocytosis. Now when the cell gets infected the cell releases certain intermediates: -

1.The Interferon α and β which goes to the healthy alveolar cells of vicinity and this results in the release of antiviral peptides (these peptides are kind of self-defense mechanism).

2.They also release Damage-associated molecular patterns (DAMPs are endogenous molecules that are released from damaged or dying cells and activate the innate immune system(macrophages) by interacting with pattern recognition receptors).

Now these macrophages activate the inflammatory mediators (Interleukin1, interleukin 6, TNF-α) so that they can be used to kill the virus.

They also move to the pulmonary capillaries which are just below the alveoli. This resulted in contraction of the pulmonary capillaries which kind of creates spaces in between the pulmonary capillaries.

This results in the release of the fluid from the pulmonary capillary to the interstitial spaces in between the capillary and alveolar surface which also moves inside the alveoli.

This makes a thick layer of fluid on the alveolar surface making it difficult for gas exchange which eventually results in the accumulation of CO2 and systemic acidosis. This also results in the less oxygen supply to the systemic circulation(hypoxia).

If the patient has a strong immune system, he or she can recover from this stage but if not, there is going to be a lot of health problems

The endothelial tissue has some protein called as vascular cell adhesion molecules. These captures the leucocytes like neutrophils. This results in the cytokine rush in the lungs.

These have 2 effects

This would affect vagal nerves and induce cough mechanism.

They induce Broncho-constriction.

In severe cases the cytokines may also move systemic and could result in clot formation which would be far more dangerous.

This is why we need ventilators as we would provide the patient with optimum oxygen levels directly into the pulmonary capillaries enabling the patient body to overcome the disease on its own.

References: -

1.https://www.ncbi.nlm.nih.gov/pubmed/15356152

2.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2812346/

3.https://www.nature.com/articles/s41418-020-0530-3/figures/1

compiled by curiosityseeker