Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The epithelium of the gastrointestinal tract is continuously exposed to the external environment containing food antigens, microbes and other pathogens. Immunologic and nonimmunologic mechanisms contribute to the neutralization and elimination of these foreign antigens. The immune system of the intestine is the most extensive in the organism and involves diffuse populations of immune cells, lymphoid aggregates and intraepithelial lymphocytes. On the other hand, the functions of the digestive tract contribute to the overall host defense (mucus secretion, gastric acid secretion, water and electrolyte secretion and peristaltism). These functions are regulated by intrinsic and extrinsic nervous systems. It is currently recognized that the physiological and pathological responses of the intestine require an integrate neuroimmune network. Such neuroimmune regulation is based on anatomical and biochemical supports. Indeed, there are membrane-to-membrane contacts between axonal varicosities and the immune cells. Specific receptors for neurotransmitters such as substance P, vasoactive intestinal polypeptide and somatostatin have been identified in many immune cells. Nerve profile change has been described under pathological conditions such as parasitic infections and acute phase of inflammation. In addition to supporting the growth and survival of several populations of nerves the classical nerve growth factor (NGF) has been shown to affect an immune cell population by inducing mast cell hyperplasia. Furthermore the NGF can induce mast cell degranulation, acting directly on mast cell membrane NGF receptors or indirectly by NGF-mediated release of substance P by peripheral extrinsic or intrinsic nerves. Moreover, non-immune cells such as epithelial and smooth muscle cells can produce immunologic messengers under pathological conditions such as infectious diseases or inflammation. Besides the local regulation of gut functions, neuroimmune control can be exerted at extra-intestinal sites. During physiological and pathological conditions, gastrointestinal secretions and motor events are strongly regulated by the central nervous system. Moreover, infectious agents can induce cytokine and particularly interleukin-1 release by the brain astrocytes and microglial cells which have been shown to play a pivotal role in fever induction and modifications of the gastrointestinal functions. Visceral afferent fibers play a pivotal role in 'cross-communication' between central sites and immune response. Recent studies evoke, more specifically, the role of vagus as a key modulatory participant in the close relationship between the extraintestinal nerves and the immune system. Future work in this field will clarify the role of the different participants in the intimate communication between the gastrointestinal tract, immune system and central nervous system.
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PMID:Integrative neuroimmunology of the digestive tract. 882 13

A novel scientific discipline that examines the complex interdependence of the neural, endocrine and immune systems in health and disease has emerged in recent years. In health, the neuroimmunoregulatory network is fundamental to host defence and to the transfer of immunity to offspring; the network also plays important roles in intestinal physiology and in tissue regeneration, healing and reproduction. The proliferation of lymphocytes in primary lymphoid organs (bone marrow, bursa of Fabricius [in birds] and thymus) and in secondary lymphoid organs (spleen, lymph nodes and mucosal lymphoid tissue) depends on prolactin and growth hormone. These hormones allow immune cells to respond to antigen and to soluble mediators, called cytokines. Immune-derived cytokines are capable of inducing fever and of altering neuro-transmitter activity in the brain and hormone secretion by the pituitary gland. The activation of the hypothalamus-pituitary-adrenal axis by cytokines leads to immunosuppression. Lymphoid organs are innervated, and tissue mast cells respond to neurologic stimuli. In general, acetylcholine and substance P exert immunostimulatory and proinflammatory effects, whereas epinephrine and somatostatin are immunosuppressive and anti-inflammatory. In this article, the authors predict that novel approaches to immunomodulation will be possible by altering the level or efficacy of immunoregulatory hormones and neurotransmitters.
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PMID:Neuroimmune mechanisms in health and disease: 1. Health. 883 33

Current evidence indicates that the neuroendocrine system is the highest regulator of immune/inflammatory reactions. Prolactin and growth hormone stimulate the production of leukocytes, including lymphocytes, and maintain immunocompetence. The hypothalamus-pituitary-adrenal axis constitutes the most powerful circuit regulating the immune system. The neuropeptides constituting this axis, namely corticotrophin releasing factor, adrenocorticotrophic hormone, alpha-melanocyte stimulating hormone, and beta-endorphin are powerful immunoregulators, which have a direct regulatory effect on lymphoid cells, regulating immune reactions by the stimulation of immunoregulatory hormones (glucocorticoids) and also by acting on the central nervous system which in turn generates immunoregulatory nerve impulses. Peptidergic nerves are major regulators of the inflammatory response. Substance P and calcitonin gene-related peptide are pro-inflammatory mediators and somatostatin is anti-inflammatory. The neuroendocrine regulation of the inflammatory response is of major significance from the point of view of immune homeostasis. Malfunction of this circuit leads to disease and often is life-threatening. The immune system emits signals towards the neuroendocrine system by cytokine mediators which reach significant blood levels (cytokine-hormones) during systemic immune/inflammatory reactions. Interleukin-1, -6, and TNF-alpha are the major cytokine hormones mediating the acute phase response. These cytokines induce profound neuroendocrine and metabolic changes by interacting with the central nervous system and with many other organs and tissues in the body. Corticotrophin releasing factor functions under these conditions as a major co-ordinator of the response and is responsible for activating the ACTH-adrenal axis for regulating fever and for other CNS effects leading to a sympathetic outflow. Increased ACTH secretion leads to glucocorticoid production. alpha-melanocyte stimulating hormone functions under these conditions as a cytokine antagonist and an anti-pyretic hormone. The sympathetic outflow, in conjunction with increased adrenal activity. leads to the elevation of catecholamines in the bloodstream and in tissues. Current evidence suggests that neuroimmune mechanisms are essential in normal physiology, such as tissue turnover, involution, atrophy, intestinal function, and reproduction. Host defence against infection, trauma and shock relies heavily on the neuroimmunoregulatory network. Moreover, abnormalities of neuroimmunoregulation contribute to the aetiology of autoimmune disease, chronic inflammatory disease, immunodeficiency, allergy, and asthma. Finally, neuroimmune mechanisms play an important role in regeneration and healing.
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PMID:The immune effects of neuropeptides. 891 48

The number and the size of the Langerhans islets in the pancreata of most of investigated cases with diabetic foetopathy is increased (polynesia and macronesia). The B endocrine cells are immunoreactive for both insulin and IAPP, the reaction for IAPP being weaker in comparison with the controls. In one of the cases (the mother with long history of treated type 1 diabetes, who died during delivery) no presence of insulin-immunoreactive of PAF positive B cells is discovered. The reactivity for glucagon and somatostatin in the pancreata with diabetic foetopathy is found to be similar to the controls. In the vicinity of some islets lymphoid cell infiltrations are observed.
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PMID:[Immunohistochemical studies of the pancreas in newborns with diabetic fetopathy]. 896 31

Multiple communicative pathways among the nervous, endocrine and immune systems facilitate physiological immunoregulation. Spinal cord injury (SCI) patients have decreased natural (NK cell) and adaptive (T cell) immune function and reduced blood levels of cellular adhesion molecules (CAMs) that participate in immune function and wound healing. We found decreased LFA-1 and VLA-4 on peripheral blood leukocytes in SCI patients and lower levels of CAMs in SCI patients with pressure ulcers than in those without them. SCI might affect immune cells and immune responsiveness by: (1) disrupting the outflow of signals from the sympathetic nervous system to lymphoid tissues and their blood vessels as well as the returning afferent signals from these tissues to the brain; (2) immunosuppression caused by the stressors affecting SCI patients; (3) interrupting returning signals to the CNS from the periphery thereby reducing facilitation of immunoregulatory CNS neurons and decreasing their activity; or a combination of all three. SCI patients may develop dysregulation of the sympathetic nervous system that is intimately involved in immune function. Chronic stress mediates immunosuppression by corticosteroids, catecholamines, endorphins and met-enkephalin. The hypothalamus coordinates the response to stress through the release of soluble products from the sympathetic nervous system and hypothalamic-pituitary-adrenal axis. Whereas the nervous and endocrine systems are not concerned with immunological specificity, they do influence the intensity, kinetics and localization of immune responses. Products of an activated immune system may generate feedback circuits capable of inhibiting, enhancing or regulating neuronal input. Immune system cells can produce neurologically active peptides including ACTH, CRF, growth hormone, thyrotropin, prolactin, human chorionic gonadotropin, endorphin, enkephalins, substance P, somatostatin and VIP. Cytokines are likely important mediators of the HPA response to immune stimuli.
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PMID:Immune system-neuroendocrine dysregulation in spinal cord injury. 898 97

Somatostatin (somatotropin release-inhibiting hormone; SRIH) has been demonstrated in neurons of the central nervous system (CNS) as well as in endocrine cells of the pancreas and gastrointestinal tract and can suppress various immune functions including lymphocyte proliferation, immunoglobulin synthesis, and cytokine production. Since astrocytes possess antigen-presenting activity and can secrete a wide array of immunoregulatory and inflammatory cytokines, we studied SRIH gene expression in both astrocyte cell lines and mitogen-stimulated peripheral blood mononuclear leukocytes from healthy donors. We now report by means of a complementary DNA-based reverse transcription PCR that differential levels of SRIH mRNA were expressed in 9 of 11 human astrocytoma cell lines tested but were undetectable in activated peripheral blood mononuclear leukocytes as well as in a variety of human lymphocyte and monocyte cell lines. The synthesis and secretion of SRIH protein by astrocytoma cells that expressed SRIH transcripts were confirmed by specific radioimmunoassay of cell culture fluids. These findings support the notion that SRIH gene expression occurs in human astrocytoma cells but not in mature lymphoid cells of the immune system.
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PMID:Expression of the somatostatin gene in human astrocytoma cell lines. 899 28

We report the initial characterization of rare cells within the thymus that express 'peripheral' self-antigens and are capable of inducing partial tolerance to a model protein. Mice from two transgenic families that express SV40 T antigen (Tag) in pancreatic islet beta cells under control of a rat insulin promoter (RIP) develop T cell tolerance toward this neo-self antigen. These mice express low levels of Tag mRNA in the thymus. Transplantation of thymus from tolerant RIP-Tag mice into athymic hosts is sufficient to confer tolerance by CD4+ Th cells and elicits variable tolerance by CD8+ cytotoxic T cells. Thymic medulla is shown to contain rare cells that express the endogenous insulin and somatostatin genes, and in the transgenic animals, Tag. These cells are referred to as 'peripheral antigen-expressing' (PAE) cells. Thymic cell fractionation reveals the PAE cells expressing insulin and Tag to be present in a fraction enriched for non-lymphoid, MHC class II+ cells. Notably, absence of thymic expression of the RIP-Tag gene in another transgenic family correlates with failure to establish self-tolerance and susceptibility to autoimmunity. Thus, expression of tissue-restricted genes such as insulin in PAE cells of thymic medulla may serve to limit development of potentially autoimmune T cells.
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PMID:Pancreatic gene expression in rare cells of thymic medulla: evidence for functional contribution to T cell tolerance. 931 Aug 39

The ability of T cells to adhere to and interact with components of the blood vessel walls and the extracellular matrix is essential for their extravasation and migration into inflamed sites. We have found that the beta1 integrin-mediated adhesion of resting human T cells to fibronectin, a major glycoprotein component of the extracellular matrix, is induced by physiologic concentrations of three neuropeptides: calcitonin gene-related protein (CGRP), neuropeptide Y, and somatostatin; each acts via its own specific receptor on the T cell membrane. In contrast, substance P (SP), which coexists with CGRP in the majority of peripheral endings of sensory nerves, including those innervating the lymphoid organs, blocks T cell adhesion to fibronectin when induced by CGRP, neuropeptide Y, somatostatin, macrophage inflammatory protein-1beta, and PMA. Inhibition of T cell adhesion was obtained both by the intact SP peptide and by its 1-4 N-terminal and its 4-11, 5-11, and 6-11 C-terminal fragments, used at similar nanomolar concentrations. The inhibitory effects of the parent SP peptide and its fragments were abrogated by an SP NK-1 receptor antagonist, suggesting they all act through the same SP NK-1 receptor. These findings suggest that neuropeptides, by activating their specific T cell-expressed receptors, can provide the T cells with both positive (proadhesive) and negative (antiadhesive) signals and thereby regulate their function. Thus, neuropeptides may influence diverse physiologic processes involving integrins, including leukocyte-mediated migration and inflammation.
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PMID:Neuropeptides, via specific receptors, regulate T cell adhesion to fibronectin. 955 39

An autosomal recessive murine mutation, coined "aly/aly" or "alymphoplasia," was recently reported. Homozygotes for aly are defective in both humoral and cell-mediated immune function and have diffuse lymphoid cell infiltration of various tissues, particularly around the conduit ducts of the pancreas and salivary glands. In pilot studies in our laboratories, aly/aly mice were found to have peculiar biliary tract lesions, which were analyzed histologically and immunohistochemically in the present study. The livers of aly/aly mice older than 8 weeks consistently showed a variable lymphoid cell infiltration with lymph follicle formation in portal tracts; intrahepatic biliary epithelial cells showed various types of damage including pseudopyloric gland metaplasia and proliferative changes. In addition, the extrahepatic bile duct and intrahepatic large bile duct were found to contain an acidophilic substance in their epithelial cytoplasm. In the lumen and occasionally in the cytoplasm of these bile ducts, acidophilic crystals were also seen. Ultrastructurally, the intracytoplasmic acidophilic substances consisted of membrane-bound intracytoplasmic inclusions with homogeneous electron density, likely derived from rough endoplasmic reticulum (ER). Immunohistochemically, the cytoplasmic acidophilic substances were simultaneously positive for cystatin C, gastrin, serotonin, and somatostatin. In contrast, the acidophilic crystals did not react with any of these antibodies. These findings suggest that the intracytoplasmic acidophilic substances may contain a precursor of the peptide hormones, possibly because of defective secretion or intracellular transport. We believe that the aly/aly mouse is a useful model for the analysis of biliary metabolic events, and for studies of the interaction of the immune system and biliary destruction.
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PMID:aly/aly mice: a unique model of biliary disease. 962 Mar 19

Mice infected with the LP-BM5 murine leukemia virus (MuLV) develop an immune deficiency syndrome together with an encephalopathy characterized by impairments in spatial learning and memory. These cognitive deficits are evident before the appearance of neuron loss and lymphoid cell invasion of the brain. Nonetheless, a prominent gliosis and a variety of neurochemical changes precede the development of cognitive deficits. The neurochemical abnormalities include significant decreases in striatal Met-enkephalin and substance P (but not somatostatin), increases in concentrations of quinolinic acid and platelet-activating factor, and alterations in brain fyn kinase. At this stage of the infection, some of these neurochemical changes can be reversed by glutamate receptor antagonists, cytokine inhibitors, and anti-retroviral agents. In later stages of the infection, however, the infected mice develop irreversible neuronal loss, invasion of hematopoietic cells, and increased viral burden in the CNS. In addition, motor-neuron dysfunction (hindlimb paralysis, weakness, and ataxia) and seizures are sometimes observed during the late stages of infection. Thus, the LP-BM5 MuLV-infected mouse is a useful model for studying the chronology of neurodegenerative changes, ranging from reversible neuron dysfunction to irreversible neuron loss, that are associated with retrovirus-induced immunodeficiency.
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PMID:The encephalopathy associated with murine acquired immunodeficiency syndrome. 962 8


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