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The relationship between epigenetics and microbiota in neuropsychiatric diseases.
Lozupone, M, D'Urso, F, Piccininni, C, Montagna, M, Sardone, R, Resta, E, Dibello, V, Daniele, A, Giannelli, G, Bellomo, A, et al
Epigenomics. 2020;(17):1559-1568
Abstract
Microbiota might be considered as a pool for environmental epigenetic factors. Evidence is accumulating that environmental exposures - including microbes, diet, drugs - play a role in the pathogenesis of many neuropsychiatric disorders. Underlying mechanisms are complex, involving the sensitive interplay of genetics with epigenetics, neuroinflammation and the innate immune system. Modifications of microbiota affect neurogenesis and the maturation of microglia, influencing social behavior, stress-related responses and fear learning mechanisms. The excitatory neurons in the medial prefrontal cortex appear to play a key role. The mechanisms through which antibiotics administration may modulate microbiota and, therefore, behavior and neuropsychiatric disorders, may be influenced by several variables such as pre-existing gastrointestinal inflammation, the baseline microbiota composition, diet and stress perception. Probiotics, individualized diet, antibiotics and fecal transplantation could positively modulate the effects of epigenetic factors on neuropsychiatric disorders.
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2.
Impact of gut microbiota on neurological diseases: Diet composition and novel treatments.
Larroya-García, A, Navas-Carrillo, D, Orenes-Piñero, E
Critical reviews in food science and nutrition. 2019;(19):3102-3116
Abstract
Gut microbiota has significant effects on the structure and function of the enteric and central nervous system including human behaviour and brain regulation. Herein, we analyze the role of this intestinal ecosystem, the effects of dietary changes and the administration of nutritional supplements, such as probiotics, prebiotics, or fecal transplantation in neuropsychiatric disorders. Numerous factors have been highlighted to influence gut microbiota composition, including genetics, health status, mode of birth delivery and environment. However, diet composition and nutritional status has been repeatedly shown to be one of the most critical modifiable factors of this ecosystem. A comprehensively analysis of the microbiome-intestine-brain axis has been performed, including the impact of intestinal bacteria in alterations in the nervous, immune and endocrine systems and their metabolites. Finally, we discuss the latest literature examining the effects of diet composition, nutritional status and microbiota alterations in several neuropsychiatric disorders, such as autism, anxiety, depression, Alzheimer's disease and anorexia nervosa.
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3.
A Comprehensive Review of Celiac Disease/Gluten-Sensitive Enteropathies.
McAllister, BP, Williams, E, Clarke, K
Clinical reviews in allergy & immunology. 2019;(2):226-243
Abstract
Celiac disease is a complex immune-mediated gluten-sensitive enteropathy with protean clinical manifestations. It is manifest in genetically predisposed individuals who ingest gluten in varying amounts. In broad terms, it is thought to affect 1% of the population in the USA. More specifically, the prevalence increases drastically from 1:133 in patients not-at-risk, to 1:56 in symptomatic patients, to 1:39 in patients with a second-degree relative with the diagnosis, and to 1:22 in patients with a first-degree relative with the diagnosis. It may be associated with several immune-mediated phenomena, autoimmune diseases, and complicated by vitamin and other trace element deficiencies, bone disease, and malignancy. Our understanding of celiac disease has evolved rapidly over the past two decades. This has led to several lines of enquiry on the condition and potential treatment options. More recently, several entities including gluten intolerance, non-celiac gluten sensitivity, and seronegative celiac disease have been described. These conditions are distinct from allergies or intolerance to wheat or wheat products. There are challenges in defining some of these entities since a large number of patients self-report these conditions. The absence of confirmatory diagnostic tests poses an added dilemma in distinguishing these entities. The differences in spectrum of symptoms and highlights of the variability between the pediatric and adult populations have been studied in some detail. The role of screening for celiac disease is examined in both the general population and "at risk" populations. Diagnostic strategies including the best available serologic testing, utility of HLA haplotypes DQ2 and DQ8 which are seen in over 90% of patients with celiac disease as compared with approximately 40% of the general population, and endoscopic evaluation are also reviewed. Comprehensive nutritional management after diagnosis is key to sustained health in patients with celiac disease. Simple algorithms for care based on a comprehensive multidisciplinary approach are proposed. Refractory and non-responsive celiac diseases in the setting of a gluten-free diet are examined as are novel non-dietary therapies. Finally, the association of other disease states including psychiatric illness, infertility, lymphoproliferative malignancy, and mortality is explored with special attention paid to autoimmune and atopic disease.
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4.
Kynurenines: Tryptophan's metabolites in exercise, inflammation, and mental health.
Cervenka, I, Agudelo, LZ, Ruas, JL
Science (New York, N.Y.). 2017;(6349)
Abstract
Kynurenine metabolites are generated by tryptophan catabolism and regulate biological processes that include host-microbiome signaling, immune cell response, and neuronal excitability. Enzymes of the kynurenine pathway are expressed in different tissues and cell types throughout the body and are regulated by cues, including nutritional and inflammatory signals. As a consequence of this systemic metabolic integration, peripheral inflammation can contribute to accumulation of kynurenine in the brain, which has been associated with depression and schizophrenia. Conversely, kynurenine accumulation can be suppressed by activating kynurenine clearance in exercised skeletal muscle. The effect of exercise training on depression through modulation of the kynurenine pathway highlights an important mechanism of interorgan cross-talk mediated by these metabolites. Here, we discuss peripheral mechanisms of tryptophan-kynurenine metabolism and their effects on inflammatory, metabolic, oncologic, and psychiatric disorders.
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5.
Pathogens and chronic or long-term neurologic disorders.
Starakis, I, Panos, G, Koutras, A, Mazokopakis, EE
Cardiovascular & hematological disorders drug targets. 2011;(1):40-52
Abstract
Infections of the central nervous system may provoke glial and autoimmune responses but a definitive linkage between these infections and the pathogenesis of chronic neurologic disorders is still elusive. There are controversial reports implicating infectious agents in the pathogenetic mechanisms of chronic or long-term neurologic disorders, such as multiple sclerosis, amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease and autistic spectrum disorders, but the specific role of bacterial or viral infections in the pathogenesis of these medical entities has not been fully elucidated. Up till now, the evidence is distant from definite, but certain cases may be attributed to infections in the millieu of multiple toxic events such as trauma, nutritional deficits, immune dysregulation and excitotoxicity in genetically vulnerable indiniduals. There is an ongoing debate concering the direct involvement of various infectious agents in the neurodegenerative and neurobehavioral diseases pathogenesis and/or their contribution to the deterioration of the disease or co-morbidity in these patients. These patients are exceptionally difficult to be treated by using single therapeutic modalities, because their disese is multifocal and treatment is aimed to control signs and symptoms rather than the true causes of the disease and its progressive course. Furthermore, even if these causative links were indetifiable, our therapeutic interventions would come too late due to the irreversible damages at the time of the initiation of treatment. Our aim is to comprehensively review all available data suggesting that infections could be common antecedent events of progressive neurologic degenerative or behavioural diseases.
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6.
[Neurological and psychiatric aspects of some gastrointestinal diseases].
Aszalós, Z
Orvosi hetilap. 2008;(44):2079-86
Abstract
The gastrointestinal tract is controlled by the independent enteric nervous system. It is also closely connected to the central nervous system, and bi-directional communication exists between them. The communication involves neural pathways as well as immune and endocrine mechanisms. The brain-gut axis plays a prominent role in the modulation of gut functions. Signals from different sources (e.g. sound, sight, smell, somatic and visceral sensations, pain) reach the brain. These inputs are modified by memory, cognition and affective mechanisms and integrated within the neural circuits of the central nervous system, spinal cord, autonomic and enteral nervous systems. These inputs can have physiologic effects, such as changes in motility, secretion, immune function, and blood flow to the gastrointestinal tract. One of the most important neurotransmitters is serotonin that plays a key role in the pathogenesis of the most common chronic functional gastrointestinal disorder: the irritable bowel syndrome. It is a biopsychosocial disease, resulting from the dysregulation of the brain-gut axis. Endogenous pain facilitation rather than inhibition, pathologic gradation of visceral perception and reduced threshold for pain are all evident in these patients. Abuse history is common in their anamnesis. Exaggerated conscientiousness, perfectionism, oversensitivity, feeling of deficiency in effectiveness, and higher demand for social parity, neuroticism and alexithymia have been detected among their constant personality features. Females are also characterized by gender role conflict and low assertiveness. Antidepressants and psychotherapy have important roles in their treatment. Also patients with inflammatory bowel disease are characterized by neuroticism and alexithymia and altered mother-child attachment is often described in their anamnesis. Autonomic neuropathy is a frequent and early neurological complication. Reflux disease and obstructive sleep apnea mutually generate each other and their severities significantly correlate. In the celiac disease the most common neurological manifestations are ataxia, peripheral neuropathy and myopathy. Up to 85% of patients with histologically proven coeliac disease have no gastrointestinal symptoms; consequently, measurement of antigliadin antibody titre is therefore vital in all cases of idiopathic ataxia. Complete resolution of neurological symptoms is the result of gluten-free diet.