Zeng et al. (2023) found that gut microbiota of old mice worsens neurological outcome after brain ischemia via increased valeric acid and IL-17 in the blood. Medina-Rodriguez et al. (2023) found that the microbial effect was dependent on the presence of Th17 cells in the recipient, which plays a key role in regulating behavioral changes induced by the microbiome of depressed patients. Zhu et al. (2023) reported that specific Lactobacillus species affected stress-induced social-avoidance behavior by involving in T cell differentiation mediated immune response. This evidence concerns the gene IL17A and brain ischemia.