Probiotics as a biotherapeutics for the management and prevention of respiratory tract diseases

Respiratory diseases are responsible for a greater mortality rate around the world. Viral or bacterial infections in the respiratory tract have been identified as major causative agents for death and disability among the population. Respiratory tract infections (RTIs) cause severe respiratory ailments starting from coldlike symptoms, eventually affecting the lungs and other viscera, and are mainly categorized into two types depending on the affected area: upper RTIs and lower RTIs. Respiratory viruses belong to several viral families such as influenza virus, enterovirus, adenovirus, respiratory syncytial virus, and recently severe acute respiratory syndrome coronavirus 2. Studies have indicated that people with good immune functions are less prone to respiratory infections and also their recovery rate is quicker. Innate and acquired immune systems actively participate in the recognition and elimination of the pathogenic agents. In the present context, the potential of probiotics is recognized as viable microorganisms that support the balance of the beneficial microbial population in the gastrointestinal tract and promote host immunity. The probiotics have long been known to regulate bodily immune functions and have been used against general RTIs such as cough, pharyngitis, laryngitis, pneumonia, and asthma. In addition, intervention with probiotics could directly affect the composition of the gut microbiota that have been shown to palliate respiratory diseases by modulating pulmonary immune activities through the gut-lung axis, and therefore, probiotics could become an alternative therapeutic approach for RTIs.