Las dificultades del aprendizaje autónomo en un contexto de ABP

Objetivos: Identificar las dificultades que experimentan los estudiantes en un proceso de aprendizaje autodirigido. Elaborar un inventario y una clasificación de las dificultades identificadas. Diagnosticar las causas de las dificultades y apuntar vías o posibilidades de superación. Evaluar el impacto de las dificultades en el producto final. Datos del análisis empírico: Participan en el estudio un total de 80 estudiantes de los dos últimos cursos de la licenciatura de Derecho. Curso académico 2006-2007. Facultad de Derecho de la Universidad de Barcelona. Metodología de trabajo: Estudio etnográfico. Resultados: Para los estudiantes que no tienen experiencia previa en ABP la mayor dificultad es la desorientación y la angustia que sufren ante la ausencia de un temario. Existen dificultades de interacción con los tutores derivadas de la divergente concepción e inteligencia de significados. Finalmente, se han detectado dificultades derivadas de la influencia del entorno (hábitos personales) y otras conectadas con los estilos de aprendizaje de cada estudiante.Objectives: To identify the difficulties that the students have in a process of selflearning. To elaborate an inventory of the identified difficulties. To diagnose the causes of the difficulties and to point routes or possibilities of overcoming. To evaluate the impact of the difficulties in the end item. Empiric analysis data: 80 students of the two last years in law studies. Academic year 2006-2007. Faculty of Law of the University of Barcelona. Methodology: Ethnografic study. Results: For students who do not have previous experience in ABP the greater difficulty is the disorientation and the anguish that suffer because of the absence of an agenda. They exist difficulties of interaction with the tutors derived from the divergent conception and intelligence of meaning. Finally, difficulties derived from the influence of the surroundings (personal habits) and connected others with the learning styles of each student have been detected

Control of HIV-1 Pathogenesis in Viremic Nonprogressors Is Independent of Gag-Specific Cytotoxic T Lymphocyte Responses

Viremic nonprogressors (VNPs) constitute a very scarce group of untreated human immunodeficiency virus type 1 (HIV-1)-infected individuals who maintain stable CD4+ T cell counts despite high levels of HIV-1 replication. The specific factors associated with this atypical control of the HIV infection have been poorly described. Since specific T cell responses seem to be one of the main causes of HIV-1 control in elite controllers, we studied whether HIV-1 Gag-specific cytotoxic T lymphocyte (CTL) responses could also modulate disease control in VNPs. We characterized the immune responses from four VNPs compared to those of five standard progressors (SPs) during the first years of HIV-1 infection. We observed no differences in the breadth and frequency of Gag-specific cellular responses. Furthermore, we obtained 217 HIV-1Gag clonal sequences in which the viral variability of Gag increased over 3 years of infection for synonymous and nonsynonymous mutations in both VNPs and SPs. VNPs evolution rates in gag were comparable to SPs. This observation is in line with a similar accumulation of CTL putative escape mutations in Gag epitopes targeted by CTL responses. Altogether, the absence of viral pathogenesis in VNP individuals seems to be independent of HIV-Gag-specific CTL responses. This novel information guides to the study of alternative mechanism of HIV-1 pathogenesis control.IMPORTANCE Control of HIV infection has been widely studied in elite controllers or long-term nonprogressor models. However, there is a less-known group of individuals, termed viremic nonprogressors (VNPs), who maintain stable CD4+ T cell counts despite high plasma viremia. The mechanisms involved in this remarkable control of HIV-1 pathogenesis clearly have implications for the development of new drugs and vaccines. We show here for the first time that VNPs have immune responses and HIV-gag evolution similar to those of standard progressors. Remarkably, we demonstrate that the mechanism of pathogenesis control in these individuals differs from some elite controllers that are reported to have improved immune control. This is noteworthy since it opens the door to new, as-yet-unknown mechanisms for HIV control. Our novel results advance the understanding of mechanisms involved in viremic nonprogression and suggest that there are alternative mechanisms to the adaptive immune responses for an effective control of viral pathogenesis.We thank the founders for support of this project. We also thank all the centers and investigators involved in CoRIS. M.S. was supported by a Sara Borrell grant (CD11/00286). The RIS cohort (CoRIS) is supported by the Instituto de Salud Carlos III through the Red Temática de Investigación Cooperativa en Sida (RD06/006 RD12/0017/0018, RD16/0025/0041) as part of the Plan Nacional R+D+I and cofinanced by ISCIII-Subdirección General de Evaluación y el Fondo Europeo de Desarrollo Regional (FEDER). This study was supported by the National Health Institute Carlos III (PI14/01058) and the Gilead Fellowship Program GLD 15/00298. J.G.P. holds a Miguel Servet II contract (CPII15/00014) funded by ISCIII. E.J.-M. is supported by Redes Temáticas de Investigación en SIDA (ISCIII RETIC RD16/0025/0041); Acción Estratégica en Salud; Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008-2011; and Instituto de Salud Carlos III, Fondos FEDER. M.S., A.G.-M., and E.J.-M. performed the experiments. J.D., P.V., and B.A. selected and designed the cohorts. M.S., B.C., J.G.P., and J.M.-P. designed the experiments and drafted the paper. P.V. and B.A. are members of CoRISpe and the HIV HGM BioBank Study Group.S

Viral and Cellular factors leading to the Loss of CD4 Homeostasis in HIV-1 Viremic Nonprogressors

Human immunodeficiency virus type 1 (HIV-1) viremic nonprogressors (VNPs) represent a very rare HIV-1 extreme phenotype. VNPs are characterized by persistent high plasma viremia and maintenance of CD41 T-cell counts in the absence of treatment. However, the causes of nonpathogenic HIV-1 infection in VNPs remain elusive. Here, we identified for the first time two VNPs who experienced the loss of CD41 homeostasis (LoH) after more than 13 years. We characterized in deep detail viral and host factors associated with the LoH and compared with standard VNPs and healthy controls. The viral factors determined included HIV-1 coreceptor usage and replicative capacity. Changes in CD41 and CD81 T-cell activation, maturational phenotype, and expression of CCR5 and CXCR6 in CD41 T-cells were also evaluated as host-related factors. Consistently, we determined a switch in HIV-1 coreceptor use to CXCR4 concomitant with an increase in replicative capacity at the LoH for the two VNPs. Moreover, we delineated an increase in the frequency of HLA-DR1CD381 CD41 and CD81 T cells and traced the augment of naive T-cells upon polyclonal activation with LoH. Remarkably, very low and stable levels of CCR5 and CXCR6 expression in CD41 T-cells were measured over time. Overall, our results demonstrated HIV-1 evolution toward highly pathogenic CXCR4 strains in the context of very limited and stable expression of CCR5 and CXCR6 in CD41 T cells as potential drivers of LoH in VNPs. These data bring novel insights into the correlates of nonpathogenic HIV1 infection. Importance: The mechanism behind nonpathogenic human immunodeficiency virus type 1 (HIV-1) infection remains poorly understood, mainly because of the very low frequency of viremic nonprogressors (VNPs). Here, we report two cases of VNPs who experienced the loss of CD41 T-cell homeostasis (LoH) after more than 13 years of HIV-1 infection. The deep characterization of viral and host factors supports the contribution of viral and host factors to the LoH in VNPs. Thus, HIV-1 evolution toward highly replicative CXCR4 strains together with changes in T-cell activation and maturational phenotypes were found. Moreover, we measured very low and stable levels of CCR5 and CXCR6 in CD41 T-cells over time. These findings support viral evolution toward X4 strains limited by coreceptor expression to control HIV-1 pathogenesis and demonstrate the potential of host-dependent factors, yet to be fully elucidated in VNPs, to control HIV-1 pathogenesis.This research was supported by a Gilead Fellowship (grant GLD15/0298) and La Caixa Foundation (grant LCF/PR/PR16/11110026). M.C.-L. is a Beatriu de Pinós postdoctoral fellow (grant BP 00075) supported by the Government of Catalonia’s Secretariat for Universities and Research of the Ministry of Economy and Knowledge. J.G.P. was supported by the ISCIII (grant CP15/00014). E.J.-M. was funded by Redes Temáticas de Investigación en SIDA (ISCIII RETIC RD16/0025/0041); Acción Estratégica en Salud; Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008–2011; and Instituto de Salud Carlos III. E.J.-M. was cofunded by European Regional Development Fund/European Social Fund (FEDER) “Investing in your future.” J.M.-P. is supported by the Spanish Ministry of Science and Innovation (grant PID2019-109870RB-I00). J.G.P. and M.C.-L. designed the study, supervised experiments and data. J.G.P., M.C.-L., and A.K. contributed to data interpretation. M.C.-L., R.P., E.J.-M., M.P., and C.C. performed experiments, analyzed, and interpreted the data. J.D. carried out the clinical follow-up and patient identification. M.C.-L., D.O., M.P., and C.C. performed data analysis. M.C.-L., A.K., M.P., C.L.-G., B.C., J.M.-P., and J.G.P. performed manuscript writing, critical revision, and discussion. We declare no conflict of interest.S

The Genome-wide Methylation Profile of CD4+ T Cells From Individuals With Human Immunodeficiency Virus (HIV) Identifies Distinct Patterns Associated With Disease Progression

Background: Human genetic variation-mostly in the HLA and CCR5 regions-explains 25% of the variability in progression of HIV infection. However, it is also known that viral infections can modify cellular DNA methylation patterns. Therefore, changes in the methylation of CpG islands might modulate progression of HIV infection. Methods: 85 samples were analyzed: 21 elite controllers (EC), 21 HIV-infected subjects before combination antiretroviral therapy (cART) (viremic, 93,325 HIV-1 RNA copies/ml) and under suppressive cART (cART, median of 17 months, <50 HIV-1 RNA copies/ml), and 22 HIV-negative donors (HIVneg). We analyzed the methylation pattern of 485,577 CpG in DNA from peripheral CD4+ T lymphocytes. We selected the most differentially methylated gene (TNF) and analyzed its specific methylation, mRNA expression, and plasma protein levels in 5 individuals before and after initiation of cART. Results: We observed 129 methylated CpG sites (associated with 43 gene promoters) for which statistically significant differences were recorded in viremic vs HIVneg, 162 CpG sites (55 gene promoters) in viremic vs cART, 441 CpG sites (163 gene promoters) in viremic vs EC, but none in EC vs HIVneg. The TNF promoter region was hypermethylated in viremic vs HIVneg, cART, and EC. Moreover, we observed greater plasma levels of TNF in viremic individuals than in EC, cART, and HIVneg. Conclusions: Our study shows that genome methylation patterns vary depending on HIV infection status and progression profile and that these variations might have an impact on controlling HIV infection in the absence of cART

Enhancement of Antiviral CD8 + T-Cell Responses and Complete Remission of Metastatic Melanoma in an HIV-1-Infected Subject Treated with Pembrolizumab

Background: Pembrolizumab is an immune checkpoint inhibitor against programmed cell death protein-1 (PD-1) approved for therapy in metastatic melanoma. PD-1 expression is associated with a diminished functionality in HIV-1 specific-CD8 + T cells. It is thought that PD-1 blockade could contribute to reinvigorate antiviral immunity and reduce the HIV-1 reservoir. Methods: Upon metastatic melanoma diagnosis, an HIV-1-infected individual on stable suppressive antiretroviral regimen was treated with pembrolizumab. A PET-CT was performed before and one year after pembrolizumab initiation. We monitored changes in the immunophenotype and HIV-1 specific-CD8 + T-cell responses during 36 weeks of treatment. Furthermore, we assessed changes in the viral reservoir by total HIV-1 DNA, cell-associated HIV-1 RNA, and ultrasensitive plasma viral load. Results: Complete metabolic response was achieved after pembrolizumab treatment of metastatic melanoma. Activated CD8 + T-cells expressing HLA-DR + /CD38 + transiently increased over the first nine weeks of treatment. Concomitantly, there was an augmented response of HIV-1 specific-CD8 + T cells with TNF production and poly-functionality, transitioning from TNF to an IL-2 profile. Furthermore, a transient reduction of 24% and 32% in total HIV-1 DNA was observed at weeks 3 and 27, respectively, without changes in other markers of viral persistence. Conclusions: These data demonstrate that pembrolizumab may enhance the HIV-1 specific-CD8 + T-cell response, marginally affecting the HIV-1 reservoir. A transient increase of CD8 + T-cell activation, TNF production, and poly-functionality resulted from PD-1 blockade. However, the lack of sustained changes in the viral reservoir suggests that viral reactivation is needed concomitantly with HIV-1-specific immune enhancement

HIV-1 immune activation induces Siglec-1 expression and enhances viral trans-infection in blood and tissue myeloid cells

Background: Myeloid cells are key players in the recognition and response of the host against invading viruses. Paradoxically, upon HIV-1 infection, myeloid cells might also promote viral pathogenesis through trans-infection, a mechanism that promotes HIV-1 transmission to target cells via viral capture and storage. The receptor Siglec-1 (CD169) potently enhances HIV-1 trans-infection and is regulated by immune activating signals present throughout the course of HIV-1 infection, such as interferon α (IFNα). Results: Here we show that IFNα-activated dendritic cells, monocytes and macrophages have an enhanced ability to capture and trans-infect HIV-1 via Siglec-1 recognition of viral membrane gangliosides. Monocytes from untreated HIV-1-infected individuals trans-infect HIV-1 via Siglec-1, but this capacity diminishes after effective antiretroviral treatment. Furthermore, Siglec-1 is expressed on myeloid cells residing in lymphoid tissues, where it can mediate viral trans-infection. Conclusions: Siglec-1 on myeloid cells could fuel novel CD4+ T-cell infections and contribute to HIV-1 dissemination in vivo

Altered T-cell subset distribution in the viral reservoir in HIV-1-infected individuals with extremely low proviral DNA (LoViReTs)

HIV cure strategies aim to eliminate viral reservoirs that persist despite successful antiretroviral therapy (ART). We have previously described that 9% of HIV-infected individuals who receive ART harbor low levels of provirus (LoViReTs). We selected 22 LoViReTs matched with 22 controls ART suppressed for more than 3 years with fewer than 100 and more than 100 HIV-DNA copies/10 6 CD4 + T cells, respectively. We measured HIV reservoirs in blood and host genetic factors. Fourteen LoViReTs underwent leukapheresis to analyze replication-competent virus, and HIV-DNA in CD4 + T-cell subpopulations. Additionally, we measured HIV-DNA in rectum and/or lymph node biopsies from nine of them. We found that LoViReTs harbored not only lower levels of total HIV-DNA, but also significantly lower intact HIV-DNA, cell-associated HIV-RNA, and ultrasensitive viral load than controls. The proportion of intact versus total proviruses was similar in both groups. We found no differences in the percentage of host factors. In peripheral blood, 71% of LoViReTs had undetectable replication-competent virus. Minimum levels of total HIV-DNA were found in rectal and lymph node biopsies compared with HIV-infected individuals receiving ART. The main contributors to the reservoir were short-lived transitional memory and effector memory T cells (47% and 29%, respectively), indicating an altered distribution of the HIV reservoir in the peripheral T-cell subpopulations of LoViReTs. In conclusion, LoViReTs are characterized by low levels of viral reservoir in peripheral blood and secondary lymphoid tissues, which might be explained by an altered distribution of the proviral HIV-DNA towards more short-lived memory T cells. LoViReTs can be considered exceptional candidates for future interventions aimed at curing HIV

Extremely low viral reservoir in treated chronically HIV-1-infected individuals

Altres ajuts: This research was sponsored in part by Grifols and by Merck Sharp & Dohme España, S.A. (IISP 54925). The funding organizations had no input in the design of the study; in the collection, analyses, or interpretation of the data; writing of the manuscript; or in the decision to submit the study for publication. NH received a post-doctoral grant from the Jaqueline Beytout Foundation. FG received the support of "José María Segovia de Arana" contracts (2019) and MMT from the NIH (R01AI143457).Small viral reservoirs are found predominantly in HIV-1 controllers and individuals treated during acute/early HIV-1 infection. However, other HIV + individuals could naturally also harbour low viral reservoirs. We screened 451 HIV-1-infected treated-individuals with suppressed plasma viremia for at least 3 years and stored cryopreserved peripheral blood mononuclear cells (PBMCs). Total HIV-DNA was analysed in PBMCs with ddPCR. Individuals with 50 HIV-DNA copies/10 6 PBMCs) to analyse total HIV-DNA, T-cell and NK-cell populations, HIV-1 specific antibodies, and plasma inflammation markers. We found that 9.3% of the individuals screened had <50 HIV-DNA copies/10 6 PBMCs. At least 66% initiated cART during the chronic phase of HIV-1 infection (cp-LoViReT). Cp-LoViReT harboured lower levels of HIV-DNA before cART and after treatment introduction the decays were greater compared to controls. They displayed a marked decline in quantity and avidity in HIV-specific antibodies after initiation of cART. Cp-LoViReT had fewer CD8 + T and T in the absence of cART, and higher CD8 + T after 18 months on therapy. Treated chronically HIV-1-infected LoViReT represent a new phenotype of individuals characterized by an intrinsically reduced viral reservoir, less impaired CD8 + T-cell compartment before cART, and low circulating HIV-1 antigens despite being treated in the chronic phase of infection. The identification of this unique group of individuals is of great interest for the design of future eradication studies. MSD Spai

HIV-1 Tropism Testing in Subjects Achieving Undetectable HIV-1 RNA : Diagnostic Accuracy, Viral Evolution and Compartmentalization

Technically, HIV-1 tropism can be evaluated in plasma or peripheral blood mononuclear cells (PBMCs). However, only tropism testing of plasma HIV-1 has been validated as a tool to predict virological response to CCR5 antagonists in clinical trials. The preferable tropism testing strategy in subjects with undetectable HIV-1 viremia, in whom plasma tropism testing is not feasible, remains uncertain. We designed a proof-of-concept study including 30 chronically HIV-1-infected individuals who achieved HIV-1 RNA <50 copies/mL during at least 2 years after first-line ART initiation. First, we determined the diagnostic accuracy of 454 and population sequencing of gp120 V3-loops in plasma and PBMCs, as well as of MT-2 assays before ART initiation. The Enhanced Sensitivity Trofile Assay (ESTA) was used as the technical reference standard. 454 sequencing of plasma viruses provided the highest agreement with ESTA. The accuracy of 454 sequencing decreased in PBMCs due to reduced specificity. Population sequencing in plasma and PBMCs was slightly less accurate than plasma 454 sequencing, being less sensitive but more specific. MT-2 assays had low sensitivity but 100% specificity. Then, we used optimized 454 sequence data to investigate viral evolution in PBMCs during viremia suppression and only found evolution of R5 viruses in one subject. No de novo CXCR4-using HIV-1 production was observed over time. Finally, Slatkin-Maddison tests suggested that plasma and cell-associated V3 forms were sometimes compartmentalized. The absence of tropism shifts during viremia suppression suggests that, when available, testing of stored plasma samples is generally safe and informative, provided that HIV-1 suppression is maintained. Tropism testing in PBMCs may not necessarily produce equivalent biological results to plasma, because the structure of viral populations and the diagnostic performance of tropism assays may sometimes vary between compartments. Thereby, proviral DNA tropism testing should be specifically validated in clinical trials before it can be applied to routine clinical decision-making