Brain, behavior, and immunity
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There is a growing emphasis on the relationship between the microorganisms inhabiting the gut (gastrointestinal microbiota) and human health. The emergence of a microbiota-gut-brain axis to describe the complex networks and relationship between the gastrointestinal microbiota and host reflects the major influence this environment may have in brain health and disorders of the central nervous system (CNS). Bidirectional communication between the microbiota and the CNS occurs through autonomic, neuroendocrine, enteric, and immune system pathways. ⋯ Perturbations of the gut microbial community have already been implicated in multiple host diseases such as obesity, diabetes, and inflammation, while recent evidence suggests a potential role of the microbiota-gut-brain axis in neuropsychiatric disorders, such as depression and anxiety. Here, we review the current literature related to the influence of the gut microbial community on central nervous system function, with a specific focus on anxiety and depressive symptoms. The role of stress and stress-mediated changes in autonomic, neuroendocrine, immune, and neurotransmitter systems are examined, followed by a discussion of the role of the microbiota in novel gastrointestinal-based treatment options for the prevention and treatment of brain-based disorders such as anxiety and depression.
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Brain Behav. Immun. · Nov 2017
ReviewThe bidirectional gut-brain-microbiota axis as a potential nexus between traumatic brain injury, inflammation, and disease.
As head injuries and their sequelae have become an increasingly salient matter of public health, experts in the field have made great progress elucidating the biological processes occurring within the brain at the moment of injury and throughout the recovery thereafter. Given the extraordinary rate at which our collective knowledge of neurotrauma has grown, new insights may be revealed by examining the existing literature across disciplines with a new perspective. This article will aim to expand the scope of this rapidly evolving field of research beyond the confines of the central nervous system (CNS). ⋯ Despite this void, the proposed mechanisms emanating from a damaged gut are closely implicated in the inflammatory processes known to promote neuropathology in the brain following TBI, which suggests the gut-brain axis may be a therapeutic target to reduce the risk of Chronic Traumatic Encephalopathy and other neurodegenerative diseases following TBI. To better appreciate how various peripheral influences are implicated in the health of the CNS following TBI, this paper will also review the secondary biological injury mechanisms and the dynamic pathophysiological response to neurotrauma. Together, this review article will attempt to connect the dots to reveal novel insights into the bidirectional influence of the gut-brain axis and propose a conceptual model relevant to the recovery from TBI and subsequent risk for future neurological conditions.
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Brain Behav. Immun. · Nov 2015
ReviewMast cell activation disease: An underappreciated cause of neurologic and psychiatric symptoms and diseases.
Neurologists and psychiatrists frequently encounter patients whose central and/or peripheral neurologic and/or psychiatric symptoms (NPS) are accompanied by other symptoms for which investigation finds no unifying cause and for which empiric therapy often provides little to no benefit. Systemic mast cell activation disease (MCAD) has rarely been considered in the differential diagnosis in such situations. Traditionally, MCAD has been considered as just one rare (neoplastic) disease, mastocytosis, generally focusing on the mast cell (MC) mediators tryptase and histamine and the suggestive, blatant symptoms of flushing and anaphylaxis. ⋯ Significantly helpful treatment--including for neuropsychiatric issues--usually can be identified once MCAD is accurately diagnosed. We describe MCAD's pathogenesis, presentation (focusing on NPS), and therapy, especially vis-à-vis neuropsychotropes. Since MCAD patients often present NPS, neurologists and psychiatrists have the opportunity, in recognizing the diagnostic possibility of MCAD, to short-circuit the often decades-long delay in establishing the correct diagnosis required to identify optimal therapy.
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Brain Behav. Immun. · Mar 2015
ReviewRole of the immune system in HIV-associated neuroinflammation and neurocognitive implications.
Individuals living with HIV who are optimally treated with combination antiretroviral therapy (cART) can now lead an extended life. In spite of this remarkable survival benefit from viral suppression achieved by cART in peripheral blood, the rate of mild to moderate cognitive impairment remains high. A cognitive decline that includes impairments in attention, learning and executive function is accompanied by increased rates of mood disorders that together adversely impact the daily life of those with chronic HIV infection. ⋯ Cytokines, which are elevated in the blood of patients with HIV infection, may also contribute to brain inflammation by entering the brain from the blood. Host factors such as aging and co-morbid conditions such as cytomegalovirus co-infection and vascular pathology are important factors that affect the HIV-host immune interactions in HAND pathogenesis. By these diverse mechanisms, HIV-1 induces a neuroinflammatory response that is likely to be a major contributor to the cognitive and behavior changes seen in HIV infection.