Probiotics are nutritional supplements that can have a preventive or beneficial effect on diseases of viral origin.

The intestinal microbiota acts on systemic immunity and pulmonary defenses through the so-called intestine-lung axis preventing or decreasing the severity of respiratory infections of viral origin and preventing secondary infections.

The gastrointestinal tract and the respiratory tree share many structural and biological factors (including the mucosa). In addition, they exhibit similar microbial behavior.

Cells of the immune system travel from the intestine to the lung through the common mucosal system. Thus, the imbalance of intestinal immunity due to dysbiosis alters the pulmonary immune response.he imbalance of intestinal immunity due to dysbiosis alters the pulmonary immune response.

 

INTESTINAL MICROBIOTA

The intestinal microbiota affects the systemic inflammatory response by modulating various immune pathways and producing short-chain fatty acids with local and systemic effects.

Dysbiosis causes translocation of bacteria, endotoxins, metabolites and cytokines into the systemic circulation transporting them to systemic organs such as the lung in the same way that respiratory inflammation causes local dysbiosis and translocation of bacterial metabolites and toxins to other organs such as the intestine.

Physiological changes in the human microbiota with age lead to dysbiosis and reduced diversity in bacterial composition, which is aggravated by comorbidities (obesity, diabetes, hypertension or inflammatory bowel disease). Therefore, to re-establish eubiosis, probiotic administration, among other things, is necessary.

As discussed above, metabolites, such as short-chain fatty acids,travel from the intestine to the lung producing activation of the respiratory immune response protecting the host from the onset of respiratory infection.

The absence of bacteria produces a decrease in innate and adaptive immune response at local and systemic level causing severe viral and bacterial infections.

The interaction between the lung and intestine is bilateral and inflammation of any origin in the lung produces important changes in the intestinal microbiota.

On the other hand, if antibiotics are administered that unbalance the body's probiotic flora, infection by viruses such as influenza worsens.

 

PROBIOTICS IN CORONAVIRUS INFECTIONS

Lactobacillus and Bifidobacterium are the main probiotics that can be used to combat SARS-CoV2 infection as they have an anti-inflammatory effect.

The use of probiotics and their metabolites (SCFA) to promote immunity is recommended as an adjuvant strategy against complications in patients with COVID.

In conclusion, thanks to their anti-inflammatory effects, probiotics produce an improvement in viral infections with great efficacy.