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Medicina, Venezuela

Cabezon R.,Fundacio Clinic per a la Recerca Biomedica | Antonio Carrera-Silva E.,Institute Medicina Experimental | Florez-Grau G.,Institute dInvestigacions Biomediques August Pi i Sunyer | Errasti A.E.,University of Buenos Aires | And 5 more authors.
Journal of Leukocyte Biology | Year: 2015

The aim of this study was to test the hypothesis whether MERTK, which is up-regulated in human DCs treated with immunosuppressive agents, is directly involved in modulating T cell activation. MERTK is a member of the TAM family and contributes to regulating innate immune response to ACs by inhibiting DC activation in animal models. However, whetherMERTK interacts directly with T cells has not been addressed. Here, we show that MERTK is highly expressed on dex-induced human tol- DCs and participates in their tolerogenic effect. Neutralization of MERTK in allogenic MLR, as well as autologous DC–T cell cultures, leads to increased T cell proliferation and IFN-γ production. Additionally, we identify a previously unrecognized noncell-autonomous regulatory function of MERTK expressed on DCs. Mer-Fc protein, used to mimic MERTK on DCs, suppresses naïve and antigen-specific memory T cell activation. This mechanism is mediated by the neutralization of the MERTK ligand PROS1. We find that MERTK and PROS1 are expressed in human T cells upon TCR activation and drive an autocrine proproliferative mechanism. Collectively, these results suggest that MERTK on DCs controls T cell activation and expansion through the competition for PROS1 interaction withMERTK in the T cells. In conclusion, this report identified MERTK as a potent suppressor of T cell response. © Society for Leukocyte Biology. Source

Boadas J.,Postgrado de Toxicologia Medica | Matos M.,University of Barcelona | Bonoli S.,University of Barcelona | Borges A.,University of Barcelona | And 9 more authors.
Boletin de Malariologia y Salud Ambiental | Year: 2012

The accidents caused by venomous animals are a global problem, especially in subtropical and tropical regions of the world. In Venezuela, they are endemic in several regions including the northeast. In order to expand and update the ecoepidemiological profile of snake bites in Monagas state, their behavior was assessed in each municipality for 5 years (2002 - 2006). There were 339 ophidian accidents (on average 68 per year). The bites occurred more frequently in young adult male farmers, while working in the field and during daytime. The incidence followed a bimodal seasonal pattern with predominance in high and low rainfall periods. Bothropic envenoming (28.6%) were the most frequent followed by Crotalic ones (14.5%), with a 2:1 ratio. 87.9% received specific serum therapy. The annual average incidence in the state was 11.30 cases per 100,000 inhabitants. Punceres (46.29), Acosta (20.91) and Bolivar (19.52) were the municipalities with the highest impact. Monagas state showed an endemicity map with municipalities having (1) very high endemicity, (2) high endemicity, (3) medium endemicity, (4) low endemicity and (5) very low endemicity. In the studied period there were no deaths from this cause in the state. The findings suggest the importance of snake accidents in Monagas, especially in the northern half of the state. Source

Maria Isabel Giacopini de Z.,Institute Medicina Experimental | Hilda Alonso V.,Institute Medicina Experimental | Garcia N.,Institute Medicina Experimental | Veliz L.,Central University of Venezuela | And 2 more authors.
Investigacion Clinica (Venezuela) | Year: 2013

We analyzed in 31 subjects, regular guests of the University food service of the Central University of Venezuela (UCVFS), in Caracas, the effects of replacing sunflower oil, commonly used in the preparation of meals, by a mix of sunflower oil and palm olein 70/30 (v/v) respectively. Plasma concentrations of total cholesterol, low and very low density lipoproteins were not changed after 40 days of the substitution. On the contrary, concentrations of high density lipoprotein and total triglycerides increased. The resistance to the oxidation of low-density lipoproteins increased considerably (p<0, 01). Today this resistance is considered as a protective factor of great importance in the prevention of the initiation of the atherogenic process. Taking into account the favorable modifications of HDL cholesterol and the clear increased resistance to the oxidation of LDL, we think that palm olein, mixed with other oils with a high ratio linoleic/palmític (sunflower, corn, soya an the likes), can be used as a healthy alternative in human nutrition. Source

Borge M.,Institute Medicina Experimental | Borge M.,University of Buenos Aires | Lenicov F.R.,CONICET | Nannini P.R.,Institute Medicina Experimental | And 13 more authors.
Journal of Immunology | Year: 2014

Chronic lymphocytic leukemia (CLL) is characterized by the progressive accumulation of clonal B lymphocytes. Proliferation occurs in lymphoid tissues upon interaction of leukemic cells with a supportive microenvironment. Therefore, the mobilization of tissue-resident CLL cells into the circulation is a useful therapeutic strategy to minimize the reservoir of tumor cells within survival niches. Because the exit of normal lymphocytes from lymphoid tissues depends on the presence of sphingosine-1 phosphate (S1P) and the regulated expression of S1P receptor-1 (S1PR1), we investigated whether the expression and function of S1PR1 can be modulated by key microenvironment signals. We found that activation of CLL cells with CXCL12, fibroblast CD40L+, BCR cross-linking, or autologous nurse-like cells reduces their S1PR1 expression and the migratory response toward S1P. Moreover, we found that S1PR1 expression was reduced in the proliferative/activated subset of leukemic cells compared with the quiescent subset from the same patient. Similarly, bone marrow-resident CLL cells expressing high levels of the activation marker CD38 showed a lower expression of S1PR1 compared with CD38lowcounterparts. Finally, given that treatment with BCRassociated kinase inhibitors induces a transient redistribution of leukemic cells from lymphoid tissues to circulation, we studied the effect of the Syk inhibitors piceatannol and R406 on S1PR1 expression and function. We found that they enhance S1PR1 expression in CLL cells and their migratory response toward S1P. Based on our results, we suggest that the regulated expression of S1PR1 might modulate the egress of the leukemic clone from lymphoid tissues. © 2014 by The American Association of Immunologists, Inc. Source

Panero J.,Institute Medicina Experimental | Stella F.,Institute Medicina Experimental | Schutz N.,Seccion Hematologia | Fantl D.B.,Seccion Hematologia | Slavutsky I.,Institute Medicina Experimental
PLoS ONE | Year: 2015

Telomerase, shelterin proteins and various interacting factors, named non-shelterin proteins, are involved in the regulation of telomere length (TL). Altered expression of any of these telomere-associated genes can lead to telomere dysfunction, causing genomic instability and disease development. In this study, we investigated the expression profile of a set of non-shelterin genes involved in essential processes such as replication (RPA1), DNA damage repair pathways (MRE11-RAD50-NBS1) and stabilization of telomerase complex (DKC1), in 35 patients with monoclonal gammopathy of undetermined significance (MGUS) and 40 cases with multiple myeloma (MM). Results were correlated with hTERT expression, TL and clinical parameters. Overall, a significant increase in DKC1, RAD50, MRE11, NBS1 and RPA1 expression along with an upregulation of hTERT in MM compared with MGUS was observed (p≤0.032). Interestingly, in both entities high mRNA levels of non-shelterin genes were associated with short TLs and increased hTERT expression. Significant differences were observed for DKC1 in MM (p ≤0.026), suggesting an important role for this gene in the maintenance of short telomeres by telomerase in myeloma plasma cells. With regard to clinical associations, we observed a significant increase in DKC1, RAD50, MRE11 and RPA1 expression in MM cases with high bone marrow infiltration (p≤0.03) and a tendency towards cases with advanced ISS stage, providing the first evidence of non-shelterin genes associated to risk factors in MM. Taken together, our findings bring new insights into the intricate mechanisms by which telomere-associated proteins collaborate in the maintenance of plasma cells immortalization and suggest a role for the upregulation of these genes in the progression of the disease. © 2015 Panero et al. Source

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