1,721,091 research outputs found
MR1 (in mouse and man)
No full textMR1 (major histocompatibility complex (MHC)-related protein 1) is a nonpolymorphic class Ib antigen presenting molecule recognized by the innate-like mucosal-associated invariant T cell subset. MR1 is highly conserved across all mammals, implying an essential role in host defense. It presents nonprotein antigens which include precursors and derivatives from highly conserved microbial biosynthetic pathways of riboflavin and folic acid metabolism. MR1 was identified in 1995 by degenerate PCR on human chromosome 1q25. MR1 is ubiquitously expressed across tissues, at relatively high abundance, but with virtually no detectable constitutive surface expression. MR1 has a standard MHC-I fold, with ?1 and ?2 helices forming an exposed antigen-binding cleft, held open by several bulky side chains, with a ?-sheet floor. MR1 ligands include formylpterins, naturally occurring photodegradation products of folic acid (vitamin B9), and ribityllumazines, precursors and derivatives of vitamin B2. MR1 predominantly exists in the late endoplasmic reticulum (ER), trafficking through the late endosomal and lysosomal compartments where it binds ligand, facilitated by chaperones from the MHC-II pathway: the invariant chain and HLA-DM. Diseases associated with MR1 deficiencies or polymorphisms are yet to be described, but are likely to produce predisposition to multisystem invasive infections, or chronic autoimmune inflammatory diseases
MAIT cells in autoimmunity, immune mediated diseases and airways disease
No full textMucosal associated invariant T (MAIT) cells are a novel class of innate-like T cells, expressing a semi-invariant T cell receptor and able to recognize small molecules presented on the non-polymorphic MHC-related protein 1. Their intrinsic effector-memory phenotype, enabling secretion of pro-inflammatory cytokines, and their relative abundance in humans implies a significant potential to contribute to autoimmune processes. However, as MAIT cells were unknown until recently and specific immunological tools were unavailable, to date little is known of their roles in disease. Here I review observations from clinical studies and animal models of autoimmune and immune mediated diseases including the roles of MAIT cells in systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease and airways diseases. MAIT cell deficiencies are frequently observed in peripheral blood, and at sites of disease such as the airways in asthma. However MAIT cells have a specific sensitivity to suppression by therapeutic corticosteroids that may confound many of these observations, as may the tendency of the surface marker CD161 to activation-induced down-regulation. Nonetheless the dependence on bacteria for the development of MAIT cells suggests a potentially important protective role linking the influences of early life microbial exposures and subsequent development of autoimmunity. Conversely MAIT cells could contribute to chronic inflammation either through TCR-independent activation, or potentially by TCR recognition of as-yet undiscovered ligands. Future research will be greatly facilitated by the immunological tools now available, including murine genetic models and human and murine specific tetramers
Letters to the Editor. Reduced numbers and proapoptotic features of mucosal-associated invariant T Cells as a characteristic finding in patients with inflammatory bowel disease
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"Choose to be optimistic, it feels better?" Evidence of optimism on employment utility
Full text linkIndividual’s expected wages exceed predicted market wages. Rational expectations imply the divergence should be zero. If individuals over-estimate the return from their attributes and view the paid-employment return distribution too favourably, then conditional on market wages, subsequent employment utility is likely to be low through disappointment
Steroid-induced deficiency of mucosal-associated invariant T cells in the chronic Obstructive Pulmonary Disease lung: Implications for Nontypeable <i>Haemophilus influenzae</i> Infection
Full text linkRationale: Mucosal associated invariant T (MAIT) cells are a recently-described, abundant, pro-inflammatory T cell subset with unknown roles in pulmonary immunity. Non-typeable Haemophilus influenzae (NTHi) is the leading bacterial pathogen during COPD exacerbations and a plausible target for MAIT cells.Objectives: To investigate whether MAIT cells respond to NTHi and the effects of inhaled corticosteroids on their frequency and function in COPD. Methods: 11 participants with COPD receiving inhaled corticosteroids (ICS), 8 with steroid-naïve COPD and 21 healthy controls underwent phlebotomy, sputum induction, bronchoalveolar-lavage and endobronchial biopsy. Pulmonary and monocyte-derived macrophages were cultured in vitro with NTHi. Measurements: Frequencies of Va7.2+CD161+ MAIT cells, surface expression of MHC-related protein 1 (MR1) and intracellular IFN-y expression were measured by flow cytometry.Main Results: MAIT cell frequencies were reduced in peripheral blood in ICS-treated COPD (median 0.38% (IQR, 0.25-0.96) compared with health (1.8% (IQR, 1.4-2.5), P=0.001)) or steroid-naïve COPD (1.8% (1.2-2.3), P=0.04). MAIT cells were reduced in bronchial biopsies in steroid-treated COPD (0.73% (0.46-1.3)) compared with health (4.0% (1.6-5.0), P=0.02). Co-culture of live NTHi increased macrophage surface expression of MR1 and induced IFN-? from CD4 cells and CD8 cells, but most potently from MAIT cells (median IFN-y positive frequencies 2.9%, 8.6% and 27.6% respectively). In vitro fluticasone and budesonide reduced MR1 surface expression 2-fold and decreased NTHi-induced IFN-y secretion 8-fold.Conclusions: MAIT cells are deficient in blood and bronchial tissue in steroid-treated, but not steroid-naïve COPD. NTHi constitutes a target for pulmonary MAIT cell immune responses, which are significantly impaired by corticosteroids.<br/
Phenotypic characterization of lung macrophages in asthmatic patients: overexpression of CCL17
No full textBackground: studies with monocyte-derived macrophages (MDMs) and animal models have suggested a role for alternatively activated (M2) macrophages in asthmatic inflammation, but in vivo evidence for this phenotype in human asthma is lacking.Objective: to characterize the phenotype of lung macrophages from asthmatic patients in relation to disease severity and treatment.Methods: M2 biomarkers were first identified by using MDMs exposed to T(H)2 cytokines and then used to phenotype sputum and bronchoalveolar lavage (BAL) macrophages from 12 healthy control subjects, 12 patients with mild asthma, and 14 patients with moderate asthma and to assess the effects of corticosteroids and phosphatidylinositol 3-kinase (PI3K) inhibitors.Results: sputum macrophages from asthmatic patients expressed significantly more CCL17 mRNA but less CD163 than macrophages from healthy subjects. However, none of the other M2 biomarkers were differentially expressed in asthmatic patients, and ex vivo BAL cells spontaneously produced similar amounts of M2 cytokines/chemokines (IL-10, CCL17, and CCL22). CCL17 mRNA overexpression correlated weakly but significantly with sputum eosinophilia (P = .0252) and was also observed in macrophages from patients with moderate asthma treated with inhaled steroids, suggesting relative insensitivity to inhibition by corticosteroids. The PI3K inhibitor LY294002 inhibited basal CCL17 release from BAL cells and IL-4-stimulated release from MDMs.Conclusions: this study does not support the existence in human asthma of the full M2 phenotype described to date but points to upregulation of CCL17 in both patients with mild and those with moderate asthma, providing a further source for this ligand of CCR4(+) cells that contributes to airways inflammation. CCL17 expression is corticosteroid resistant but suppressed by PI3K enzyme inhibitors<br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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