New Signaling Pathway for Gut-Brain Interactions

Potential effects of antibiotic-induced gut microbiome alteration on blood-brain barrier permeability compromise in rhesus monkeys

The blood-brain barrier (BBB) contributes to the maintenance of brain homeostasis. Gut microbiome composition affects BBB development and expression of tight junction proteins in rodents. However, we still do not know if there is any direct effect of gut microbial composition on BBB permeability and function in normal adult animals. In the current study, we determined temporal and spatial changes in BBB permeability of rhesus monkeys receiving amoxicillin-clavulanic acid (AC) by monitoring the cerebrospinal fluid/serum albumin ratio and the volume transfer constant (K_trans ). We showed that oral, but not intravenous, AC was associated with subsequent significant alteration in gut microbial composition and an increase in BBB permeability in all monkeys, especially in the thalamus area. Acetic and propionic acids might play a pivotal role in this newly found communication between the gut and the central nervous system. Antibiotic-induced gut microbial composition change, especially the decrease in acetic acid- and propionic acid-producing phyla and genera, might have a potential effect on the increase in BBB permeability, which may contribute to a variety of neurological and psychological diseases.

Modeling Human Brain Circuitry Using Pluripotent Stem Cell Platforms

Neural circuits are the underlying functional units of the human brain that govern complex behavior and higher-order cognitive processes. Disruptions in neural circuit development have been implicated in the pathogenesis of multiple neurodevelopmental disorders such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and schizophrenia. Until recently, major efforts utilizing neurological disease modeling platforms based on human induced pluripotent stem cells (hiPSCs), investigated disease phenotypes primarily at the single cell level. However, recent advances in brain organoid systems, microfluidic devices, and advanced optical and electrical interfaces, now allow more complex hiPSC-based systems to model neuronal connectivity and investigate the specific brain circuitry implicated in neurodevelopmental disorders. Here we review emerging research advances in studying brain circuitry using in vitro and in vivo disease modeling platforms including microfluidic devices, enhanced functional recording interfaces, and brain organoid systems. Research efforts in these areas have already yielded critical insights into pathophysiological mechanisms and will continue to stimulate innovation in this promising area of translational research.