Inflammation is a biological response to the activation of the immune system by various infectious or non-infectious agents, which may lead to tissue damage and various diseases. Gut commensal bacteria maintain a symbiotic relationship with the host and display a critical function in the homeostasis of the host immune system. Disturbance to the gut microbiota leads to immune dysfunction both locally and at distant sites, which causes inflammatory conditions not only in the intestine but also in the other organs such as lungs and brain, and may induce a disease state. Probiotics are well known to reinforce immunity and counteract inflammation by restoring symbiosis within the gut microbiota. As a result, probiotics protect against various diseases, including respiratory infections and neuroinflammatory disorders. A growing body of research supports the beneficial role of probiotics in lung and mental health through modulating the gut-lung and gut-brain axes. In the current paper, we discuss the potential role of probiotics in the treatment of viral respiratory infections, including the COVID-19 disease, as major public health crisis in 2020, and influenza virus infection, as well as treatment of neurological disorders like multiple sclerosis and other mental illnesses.

Puberty/adolescence is a critical phase during neurodevelopment with numerous structural, neurochemical, and molecular changes occurring in response to genetic and environmental signals. A consequence of this major neuronal reorganizing and remodeling is a heightened level of vulnerability to stressors and immune challenges. The gut microbiota is a fundamental modulator of stress and immune responses and has been found to play a role in mental health conditions and neurodegenerative disorders. Environmental insults (stress, infection, neuroinflammation, and use of antibiotics) during adolescence can result in dysbiosis subsidizing the development of brain disorders later in life. Also, pubertal neuroinflammatory insults can alter neurodevelopment, impact brain functioning in an enduring manner, and contribute to neurological disorders related to brain aging, such as Alzheimer’s disease, Parkinson’s disease, and depression. Exposure to probiotics during puberty can mitigate inflammation, reverse dysbiosis, and decrease vulnerabilities to brain disorders later in life. The goal of this review is to reveal the consequences of pubertal exposure to stress and immune challenges on the gut microbiota, immune reactivity within the brain, and the risk or resilience to stress-induced mental illnesses and neurodegenerative disorders. We propose that the consumption of probiotics during adolescence contribute to the prevention of brain pathologies in adulthood.