Immune regulation of the gut-brain axis and lung-brain axis involved in ischemic stroke

Local ischemia often causes a series of inflammatory reactions when both brain immune cells and the peripheral immune response are activated.In the human body,the gut and lung are regarded as the key reactional targets that are initiated by brain ischemic attacks.Mucosal microorganisms play an important role in immune regulation and metabolism and affect blood-brain barrier permeability.In addition to the relationship between peripheral organs and central areas and the intestine and lung also interact among each other.Here,we review the molecular and cellular immune mechanisms involved in the pathways of inflammation across the gut-brain axis and lung-brain axis.We found that abnormal intestinal flora,the intestinal microenvironment,lung infection,chronic diseases,and mechanical ventilation can worsen the outcome of ischemic stroke.This review also introduces the influence of the brain on the gut and lungs after stroke,highlighting the bidirectional feedback effect among the gut,lungs,and brain.

Cell proliferation and apoptosis in optic nerve and brain integration centers of adult trout Oncorhynchus mykiss after optic nerve injury

Fishes have remarkable ability to effectively rebuild the structure of nerve cells and nerve fibers after central nervous system injury.However,the underlying mechanism is poorly understood.In order to address this issue,we investigated the proliferation and apoptosis of cells in contralateral and ipsilateral optic nerves,after stab wound injury to the eye of an adult trout Oncorhynchus mykiss.Heterogenous population of proliferating cells was investigated at 1 week after injury.TUNEL labeling gave a qualitative and quantitative assessment of apoptosis in the cells of optic nerve of trout 2 days after injury.After optic nerve injury,apoptotic response was investigated,and mass patterns of cell migration were found.The maximal concentration of apoptotic bodies was detected in the areas of mass clumps of cells.It is probably indicative of massive cell death in the area of high phagocytic activity of macrophages/microglia.At 1 week after optic nerve injury,we observed nerve cell proliferation in the trout brain integration centers：the cerebellum and the optic tectum.In the optic tectum,proliferating cell nuclear antigen（PCNA）-immunopositive radial glia-like cells were identified.Proliferative activity of nerve cells was detected in the dorsal proliferative（matrix） area of the cerebellum and in parenchymal cells of the molecular and granular layers whereas local clusters of undifferentiated cells which formed neurogenic niches were observed in both the optic tectum and cerebellum after optic nerve injury.In vitro analysis of brain cells of trout showed that suspension cells compared with monolayer cells retain higher proliferative activity,as evidenced by PCNA immunolabeling.Phase contrast observation showed mitosis in individual cells and the formation of neurospheres which gradually increased during 1–4 days of culture.The present findings suggest that trout can be used as a novel model for studying neuronal regeneration.

Effects of LW-AFC on anxiety-like behavior and immune function in corticosterone-induced mice

OBJECTIVE Chronic stress is one of the important factors in the development of many mental and neurological diseases,and cause damage to the central nervous system,affect animal emotions and damage the immune function of the body.The purpose of this study was to investigate the effects of LW-AFC which extracting from traditional Chinese medicine prescription Liuwei Dihuang decoctionon the anxiety-like behaviorand immune dysfunction abnormalities caused by chronic stress,and whether immune intervention affect the action of LW-AFC.METHODS Male BALB/c mice were subcutaneously injected with corticosterone(25 mg·kg^-1)for 28 d to establish a chronic stress model.Cyclophos⁃phamide(Cy,80 mg·kg^-1)was injected continuously for the initial three days,followed by once a week,LW-AFC(1.6 g·kg^-1)was given continuously for 28 d.Then investigate the emotion changes by open field and elevated plus maze tests,and detected the lymphocyte proliferation,lymphocyte subsets in peripheral blood,microglia and astrocyte expression,and inflammatory cytokines in peripheral blood and brain tissue.RESULTS The mice showed obvious depressive-like behaviorafter 28 d of continuous corticosterone injection.LW-AFC could significantly improve the anxietybehavior induced by corticosterone injection,but LW-AFC could not improve the anxietybehavior of mice by Cy intervention.The expression of glial cells in hippocampus of corticosterone-induced mice showed an upward trend,and the activation of microglia and astrocytes have significantly increase in corticosterone and Cy injected mice.LW-AFC significantly decreased the activation of microglia and astrocytes in corticosterone-induced mice with Cy intervention.This suggested that LW-AFC can reduce the damage of stress on the immune function of central nervous system under immunosuppres⁃sive state.Furthermore,LW-AFC could significantly up-regulate the proliferation of splenic lymphocyte stimulated by LPS and ConA,up-regulate the proportion of CD3+CD8+cells,reduce the proportion of CD4+/CD8+cells,decrease the secretion of inflammatory factors IL-6 and MCP-1 in plasma,and increase the level of anti-inflammatory factor IL-10 in plasma of mice induced by chronic corticosteroneinjection.While LW-AFC could promote the inflammatory factors TNF-α and IL-6in plasma,inhibit the secretion of anti-inflammatory factor IL-10 and inflammatory cytokine MCP-1 in hippocampus of corticosterone-induced mice with Cy intervention.CONCLUSION LW-AFC can improve anxiety-likebehavior induced by chronic stress,the Cy intervention affects the alleviation of anxiety-like behavior by LW-AFC as well as the regulation of immune function.The regulation of immune function might be the main way for LW-AFC to improve the function of central nervous system.