The microbiome as a key regulator of brain, behavior and immunity: Commentary on the 2017 named series.

The focus on the microbiome for the 2017 Named Series in Brain, Behavior, and Immunity reflects the rapidly growing interest in commensal microbes and the effects that they can have on physiological processes often studied in PsychoNeuroImmunology Research. The studies included in this Named Series show that commensal microbes can impact immune system activity, as well as brain and behavioral processes across the lifespan, and are involved in behavioral and immunological responses to social stresses. The studies also show that dietary effects on brain, behavior, and immunity often involve alterations of the gut microbiota. Thus, diet can be used therapeutically for diseases and conditions involving the brain, behavior, and immunity, as can treatment with both pre- and probiotics. While this has been widely tested in animal models, fewer studies have focused on pre- and probiotic treatment in humans. The studies in this Named Series highlight the challenges of probiotic research in human populations, but also highlight the future promise of probiotics for human health. While emotional disorders, such as anxiety and depression have been often been linked to alterations in the gut microbiota, studies in this Named Series identify new domains involving interactions between the microbiota, brain, behavior, and immunity, including schizophrenia, traumatic brain injury, and stroke. As a whole, this collection of work demonstrates the importance of the microbiome in regulating key aspects of immunity, brain, and behavior, and provides important rationale for extending the work so that findings can be translated into clinical practice.