945 resultados para Vitamin B-12 Deficiency


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Immunoglobulin A deficiency (IgAD) is the most common primary immune deficiency disorder in both humans and dogs, characterized by recurrent mucosal tract infections and a predisposition for allergic and other immune mediated diseases. In several dog breeds, low IgA levels have been observed at a high frequency and with a clinical resemblance to human IgAD. In this study, we used genome-wide association studies (GWAS) to identify genomic regions associated with low IgA levels in dogs as a comparative model for human IgAD. We used a novel percentile groups-approach to establish breed-specific cut-offs and to perform analyses in a close to continuous manner. GWAS performed in four breeds prone to low IgA levels (German shepherd, Golden retriever, Labrador retriever and Shar-Pei) identified 35 genomic loci suggestively associated (p <0.0005) to IgA levels. In German shepherd, three genomic regions (candidate genes include KIRREL3 and SERPINA9) were genome-wide significantly associated (p <0.0002) with IgA levels. A ~20kb long haplotype on CFA28, significantly associated (p = 0.0005) to IgA levels in Shar-Pei, was positioned within the first intron of the gene SLIT1. Both KIRREL3 and SLIT1 are highly expressed in the central nervous system and in bone marrow and are potentially important during B-cell development. SERPINA9 expression is restricted to B-cells and peaks at the time-point when B-cells proliferate into antibody-producing plasma cells. The suggestively associated regions were enriched for genes in Gene Ontology gene sets involving inflammation and early immune cell development.

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The paracaspase MALT1 plays an important role in immune receptor-driven signaling pathways leading to NF-κB activation. MALT1 promotes signaling by acting as a scaffold, recruiting downstream signaling proteins, as well as by proteolytic cleavage of multiple substrates. However, the relative contributions of these two different activities to T and B cell function are not well understood. To investigate how MALT1 proteolytic activity contributes to overall immune cell regulation, we generated MALT1 protease-deficient mice (Malt1(PD/PD)) and compared their phenotype with that of MALT1 knockout animals (Malt1(-/-)). Malt1(PD/PD) mice displayed defects in multiple cell types including marginal zone B cells, B1 B cells, IL-10-producing B cells, regulatory T cells, and mature T and B cells. In general, immune defects were more pronounced in Malt1(-/-) animals. Both mouse lines showed abrogated B cell responses upon immunization with T-dependent and T-independent Ags. In vitro, inactivation of MALT1 protease activity caused reduced stimulation-induced T cell proliferation, impaired IL-2 and TNF-α production, as well as defective Th17 differentiation. Consequently, Malt1(PD/PD) mice were protected in a Th17-dependent experimental autoimmune encephalomyelitis model. Surprisingly, Malt1(PD/PD) animals developed a multiorgan inflammatory pathology, characterized by Th1 and Th2/0 responses and enhanced IgG1 and IgE levels, which was delayed by wild-type regulatory T cell reconstitution. We therefore propose that the pathology characterizing Malt1(PD/PD) animals arises from an immune imbalance featuring pathogenic Th1- and Th2/0-skewed effector responses and reduced immunosuppressive compartments. These data uncover a previously unappreciated key function of MALT1 protease activity in immune homeostasis and underline its relevance in human health and disease.

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Deficiency of the enzyme adenosine deaminase (ADA) results in severe lymphopenia in humans. Mice with an inactivating mutation in the ADA gene also exhibit profound lymphopenia, as well as pulmonary insufficiency and ribcage abnormalities. In fact, the mouse model has a phenotype that is remarkably similar to that of the human disease, making the mice valuable tools for unraveling the mechanism of lymphocyte destruction in absence of this housekeeping gene. T cell deficiency in ADA deficiency has been extensively studied by others, revealing a block in early thymocyte development. In contrast, our studies revealed that early B cell development in the bone marrow is normal. ADA-deficient mice, however, exhibit profound defects in germinal center formation, preventing antigen-dependent B cell maturation in the spleen. ADA-deficient spleen B cells display significant defects in proliferation and activation signaling, and produce more IgM than their normal counterparts, suggesting that extrafollicular plasmablasts are overrepresented. B cells from ADA-deficient mouse spleens undergo apoptosis more readily than those from normal mouse spleens. Levels of ADA's substrates, adenosine and 2′-deoxyadenosine, are elevated in both bone marrow and spleen in ADA-deficient mice. S ′-adenosyihomoeysteine hydrolase (SAH hydrolase) activity is significantly inhibited in both locales, as well. dATP levels, though, are only elevated in spleen, where B cell development is impaired, and not in bone marrow, where B cell ontogeny is normal. This finding points to dATP as the causative agent of lymphocyte death in ADA deficiency. ADA deficiency results in inhibition of the enzyme ribonucleotide reductase, thereby depleting nucleoside pools needed for DNA repair. Another mouse model that lacks a functional gene encoding a protein involved in DNA repair and/or cell cycle checkpoint regulation, p53-binding protein 1, exhibits blocks in T and B cell development that are similar to those seen in ADA-deficient mice. Unraveling the mechanisms of lymphocyte destruction in ADA deficiency may further understanding of lymphocyte biology, facilitate better chemotherapeutic treatment for lymphoproliferative diseases, and improve gene and enzyme therapy regimens attempted for ADA deficiency. ^

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Vitamin D is essential in maintaining the bone health and Calcium homeostasis in the body. These actions are mediated through the Vitamin D receptors (VDR) present in cells through which the activated vitamin D acts [1]. In the past, it was known that these receptors existed in the intestine and bone cell. However, recent discovery of VDR in other tissues as well, has broadened the action of Vitamin D and increased its adequate intake [1].^ In the past, Vitamin D deficiency was most common among institutionalized, elderly patients and children and thought to be extinct in the healthy population. However, recent evidence has shown that, prevalence of vitamin D deficiency is increasing into an epidemic status in the overall population of the United States, including the healthy individuals [2-3]. The increased daily-recommended requirement and other multiple factors are responsible for the re-emergence of this epidemic [4-5]. Some of these factors could be used to control the epidemic. Studies have also shown the association between vitamin D deficiency and increased risk for developing chronic diseases such as diabetes, hypertension, multiple sclerosis, arthritis, and some fatal cancers like prostate, colon and breast cancers [1, 4, 6-14]. This issue results in increased disease burden, morbidity and mortality in the community [15-20].^ Methods: The literature search was conducted using the University of Texas Health Science Center at Houston (UTHSC) and University of Texas Southwestern Medical Center (UTSW) online library. The key search terms used are “vitamin D deficiency And prevalence Or epidemiology”, “vitamin D deficiency And implication And public health” using PubMed and Mesh database and “vitamin D deficiency” using systematic reviews. The search is limited to Humans and the English language. The articles considered for the review are limited to Healthy US population to avoid health conditions that predispose the population to vitamin D deficiency. Only US population is considered to narrow down the study.^ Results: There is an increased prevalence of low levels of Vitamin D levels below the normal range in the US population regardless of age and health status. Vitamin D deficiency is also associated with increased risk of chronic illnesses and fatal cancers.^ Conclusion: This increased prevalence and the association of the deficiency with increased all-cause mortality has increased the economic burden and compromised the quality of life among the population. This necessitates the health care providers to routinely screen their patients for the Vitamin D status and counsel them to avoid the harmful effects of the Vitamin D deficiency. ^

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Hyper IgE syndrome (HIES) is a multisystem disorder resulting in bone and immune system abnormalities. It is associated with mutations in STAT3, which disrupt protein domains responsible for transcriptional function. Patients with HIES display osteoporosis and enhanced inflammatory cytokine production similar to hematopoietic Stat3-deficient mice. Since osteoclast and inflammatory cytokine genes are NFκB targets, these observations indicate a possible deregulation of NFκB signaling in both mice and humans with STAT3-deficiency. Here, we sought to examine the role of STAT3 in the regulation of NFκB-mediated gene expression through analysis of three HIES STAT3 point mutations in both hematopoietic and non- hematopoietic cells. We found that IL-6-induced tyrosine phosphorylation of STAT3 was partially or completely abrogated by HIES mutations in the transactivation domain (V713L) or SH2 domain (V637M), respectively, in both hematopoietic and non- hematopoietic cells. By contrast, IL-6-induced tyrosine phosphorylation of an HIES mutant in the STAT3 DNA-binding domain (R382W) was intact. The R382W and V713L mutants significantly reduced IL-6-dependent STAT3 transcriptional activity in reporter gene assays. Moreover, the R382W and V637M mutants significantly diminished IL-6-responsive expression of the endogenous STAT3 target gene, Socs3, as assessed by quantitative real-time PCR (qPCR) in the RAW macrophage cell line. These observations indicate the HIES mutants dominantly suppress the transcriptional activity of wild type STAT3, albeit to varying degrees. All three HIES mutants enhanced LPS-induced expression of the NFκB target genes IL6 (IL-6), Cxcl10 (IP- 10), and Tnf (TNFα) in RAW cells, as indicated by qPCR. Furthermore, overexpression of wild type STAT3 in Stat3-deficient murine embryonic fibroblasts significantlyreduced LPS-stimulated expression of IL6, Cxcl10, and IL12p35. In addition, in aprimary murine osteoclast differentiation assay, a STAT3-specific SH2 domain inhibitor led to significantly increased levels of osteoclast-specific gene expression. These results suggest that STAT3 serves as a negative regulator of NFκB-mediated gene expression, and furthermore imply that STAT3 mutations associated with HIES contribute to the osteopenia and inflammation observed in HIES patients.

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La adolescencia es un período de crecimiento y desarrollo crítico e importante para la adquisición de hábitos saludables, en los que tanto la alimentación como la actividad física tienen un papel destacado. Junto con el primer año de vida, los requerimientos de energía y nutrientes son mayores que en cualquier otro periodo. Dentro de la nutrición, las vitaminas se ven involucradas en múltiples procesos celulares y tisulares, y sus deficiencias se vinculan a enfermedades crónicas degenerativas en la edad adulta como las cardiovasculares, cáncer, diabetes y osteoporosis, pero cuyos factores de riesgo se establecen a edades más tempranas. Las concentraciones sanguíneas de vitaminas están influenciadas en gran medida por la ingesta dietética, pero existen otros factores del individuo, entre los que cabe citar la composición corporal, la actividad física y condición física que, junto a la genética, podrían desempeñar un papel crucial. La presente memoria de Tesis Doctoral tiene como objetivo analizar el estado en vitaminas liposolubles y su relación con diversos factores de salud, entre los que destacan la composción corporal, hábitos dietéticos, actividad física y condición física en adolescentes Europeos. El trabajo está basado en los datos del estudio HELENA (“Healthy Lifestyle in Europe by Nutrition in Adolescence”). Se han analizado un total de 1089 adolescentes procedentes de diez ciudades en nueve paises europeos. Los principales resultados de este trabajo indican; a) La existencia de un estado deficiente en vitaminas liposolubles en adolescentes Europeos, especialmente de vitamina D, que alcanza valores del 80%. b) La estación del año, la latitud, el índice de masa corporal, la condición física, la ingesta de calcio dietético, los suplementos vitamínicos y la edad son las variables más relacionadas con el estado de vitamina D. c) A su vez, la capacidad cardiorrespiratoria puede predecir los niveles de vitamina D en los chicos, mientras que la fuerza muscular y masa magra parecen influir en los niveles de vitamina D en las chicas. La grasa corporal y el índice de masa corporal se correlaccionan negativamente con los niveles de vitamina D, especialmente en chicos. d) Un estado de vitamina D óptimo provoca una mejora de la masa ósea sólo cuando se tiene un nivel adecuado de actividad física. e) Se identifica la necesidad de establecer un consenso sobre los rangos aceptables y puntos de corte para las concentraciones sanguíneas de estas vitaminas en este grupo de población, ya que los actuales están extrapolados de la población adulta ABSTRACT Adolescence is a critical period of physiological growth and development as well as for the acquisition of healthy behaviors where both diet and physical activity play a major role. Apart from the first year of life, both energy and nutrient requirements are greatest during adolescence and the way to spend this energy by movement is also crucial. Vitamins are specifically involved in multiple cellular and tissue processes, and there is increasing evidence that deficiencies at these early ages could contribute to risk factors of chronic diseases like cardiovascular and cerebrovascular disease, cancer, diabetes and osteoporosis in adulthood, regardless data are scarce for younger ages. Vitamin concentrations are largely influenced by diet but other individual factors like body composition, physical activity or fitness together with genetics could play also an important role. The current thesis analyzes the liposoluble vitamin status in European adolescents and their relation with several health related factors, like body composción, dietary intake, physical activity and fitness. The work is based on data from the HELENA study ("Healthy Lifestyle in Europe by Nutrition in Adolescence"), for which a total of 1089 adolescents from ten different cities, in nine European countries were recruited. The main outcomes of this thesis are: a) There is a high liposoluble vitamin deficiency prevalence in European adolescents, specifically for vitamin D, which is presenting almost 80% of the adolescents. b) Season, latitude, BMI, fitness, dietary calcium intake, supplements intake and age are highly related to 25(OH)D concentrations found in European adolescents. c) Cardiorespiratory fitness may predict 25(OH)D concentrations in male adolescents, whereas upper limbs muscular strength and FFM may predict 25(OH)D concentrations in young females. Fat mass and BMI are inversely related to 25(OH)D concentrations, especially in males. d) The effect of 25(OH)D concentrations on bone mineral content in adolescents depends on physical activity levels. e) There is a need to establish a consensus on acceptable ranges and cut-offs of blood concentrations of these vitamins during adolescence, as currently they are extrapolated from adults.

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Estrogen deficiency caused by ovariectomy (OVX) results in a marked bone loss due to stimulated bone resorption by osteoclasts. During our investigations of the pathogenesis of bone loss in estrogen deficiency, we found that OVX selectively stimulates B-lymphopoiesis which results in marked accumulation of B220-positive pre-B cells in mouse bone marrow. To examine the possible correlation between stimulated B-lymphopoiesis and bone loss, 8-week-old female mice were treated with interleukin (IL) 7, which stimulates B-lymphopoiesis in bone marrow. We also examined bone mass in IL-7 receptor-knockout mice that exhibit marked suppression of B-lymphopoiesis in the bone marrow. The increased B-lymphopoiesis induced by IL-7 administration resulted in marked bone loss by stimulation of osteoclastic bone resorption in mice with intact ovarian function. The changes in both B-lymphopoiesis and bone mass in IL-7-treated female mice were similar to those in age-matched OVX mice. In contrast, the trabecular bone volume of the femur was greatly increased in both female and male IL-7 receptor-knockout mice when compared with the respective wild-type and heterozygous littermates. These results show that the perturbation of B-lymphopoiesis in the bone marrow is closely linked to the change in bone mass. We propose here that the increased B-lymphopoiesis due to estrogen deficiency is involved in the mechanism of stimulated bone resorption.