Virus de l’hépatite C chez la femme enceinte et l’enfant : diversité, réponse neutralisante et transmission verticale

Le virus de l’hépatite C peut être transmis de la mère à l’enfant pendant la grossesse ou l’accouchement. À l’heure actuelle, il n’existe aucun moyen efficace de prévenir la transmission verticale (TV) du VHC qui se produit à un taux d’environ 5 à 10%. Le VHC est un virus extrêmement hétérogène génétiquement. On le retrouve à l’intérieur de l’hôte sous forme de quasiespèce, une population de variantes distinctes mais génétiquement liées dont la composition est influencée par les pressions de sélection exercées par la réponse immunitaire de l’hôte. La grossesse est associée à des modulations immunitaires permettant l’établissement d’une tolérance envers les antigènes paternels exprimés par l’enfant. Aussi, une étude précédemment publiée par notre groupe a révélé l’existence de pressions sélectives exercées sur l’enveloppe du VHC pendant la grossesse et suggérant l’implication de la réponse neutralisante. Afin de mieux comprendre l’effet de la réponse humorale maternelle sur l’évolution du VHC pendant la grossesse, et la nature de la quasiespèce transmise lors de la TV du VHC, nous avons caractérisé la composition des populations virales par séquençage à haut débit et évalué la réponse neutralisante spécifique au VHC dans un groupe de 42 femmes enceintes infectées par le VHC seulement (n=19) ou coinfectées par le VHC et le VIH-1 (n=23) et chez 5 couples mère-enfant pour lesquels il a eu TV. À l’aide d’horloges moléculaires, nous avons aussi pu estimer le moment où la TV se produit pendant la grossesse. En général, une grande diversité de la quasiespèce a été associée à la présence d’une réponse neutralisante efficace. Ce phénotype était associé à un plus faible risque de TV chez les femmes infectées par le VHC seulement mais pas chez les patientes coinfectées. La fraction de la quasiespèce transmise de la mère à l’enfant était aussi 10 fois plus importante en cas de coinfection maternelle par le VIH-1. Finalement, nos estimés du moment de TV suggèrent qu’une transmission in utéro est très probable et pourrait se produire aussi tôt que la fin du premier trimestre de grossesse. Dans l’ensemble, les résultats démontrent que l’évolution du VHC pendant la grossesse est fortement influencée par la réponse neutralisante maternelle, laquelle est importante pour limiter la transmission du virus à l’enfant chez les femmes infectées par le VHC seulement. Ceciii suggère un mode de TV spécifique, potentiellement lié à la capacité d’attachement du VHC à des véhicules et permettant le transport spécifique de certaines variantes à travers le placenta. Chez les femmes coinfectées, l’absence d’association entre la réponse neutralisante et la TV, ainsi que la transmission d’un grand nombre de variantes du VHC de la mère à l’enfant suggèrent plutôt un mode de transmission non spécifique, potentiellement lié à une fragilisation de la barrière placentaire ou à une altération de l’immunité fœtale pouvant restreindre l’infection. Les conclusions présentées ici permettent une meilleure compréhension des mécanismes impliqués dans la TV du VHC et pourraient apporter des informations précieuses pour la prise en charge des femmes enceintes infectées par le VHC.Hepatitis C virus can be transmitted from mother to child during pregnancy and childbirth. At present, there is no effective means to prevent vertical transmission (VT) which occurs in approximately 5 to 10% of cases. HCV is highly diversified and is found as quasispecies, a swarm of closely related yet genetically distinct variants whose composition is influenced by the host immune response. Pregnancy is associated with immune modulations allowing the establishment of maternal tolerance to the fetus, bearing 50% paternal antigens. In addition, we have shown that HCV was subjected to selective pressure targeting the viral envelope during pregnancy and suggesting the involvement of the neutralizing response. To better understand the effect of the maternal humoral response on HCV evolution during pregnancy, and the nature of the quasispecies fraction that is vertically transmitted, we characterized HCV quasispecies composition by ultradeep sequencing in a group of 42 pregnant women infected with HCV alone (n=19) or coinfected with HCV and HIV-1 (n=23), et in 5 mother-child pairs for whom HCV VT occurred. Using molecular clock analysis we also estimated the moment of VT during pregnancy. Overall, a high quasispecies diversity was associated with an effective neutralizing activity. This was also associated with reduced risks of VT in women infected with HCV alone but not in coinfected patients. The fraction of the quasispecies shared between mother and child was also 10 times more important in the cases where the mother was coinfected. Finally, estimations of the moment of VT strongly suggest the incidence of early in utero transmission. Alltogether our results showed that HCV evolution during pregnancy is driven by the maternal neutralizing response, which in turn is important in limiting viral transmission to the child in pregnant women infected with HCV only. This points to a specific mode of VT, potentially related to the ability of HCV to attach to certain vehicles, allowing the transport of specific variants across the placenta. In coinfected women, the absence of association between neutralizing activity and HCV VT, and the transmission of multiple variants from the mother to the child suggest a non specific route of VT, presumably associated with weakened placental barrier or altered fetal immunity that could have restricted the infection. Our findings allow for a better understanding of the mechanisms involved in HCV VT and could inform future strategies in the management of HCV-infected pregnant women

Pathogenesis of Hepatitis C During Pregnancy and Childhood

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Tie-Over Bolster Pressure Dressing Improves Outcomes of Skin Substitutes Xenografts on Athymic Mice

The efficacy of skin substitutes is established for the treatment of burn injuries, but its use is not limited to this condition. This technology has the potential to improve the treatment of various conditions by offering highly advanced and personalized treatments. In vivo studies are challenging but essential to move to clinical use in humans. Mice are the most widely used species in preclinical studies, but the main drawback of this model is the limited surface area of the graft in long-term transplantation studies caused by the displacement and the contraction of the graft. We improved the conventional surgical procedures by stabilizing the chamber covering the graft with intramuscular sutures and by adding a tie-over bolster dressing. The current study was therefore performed to compare outcomes of skin grafts between the conventional and optimized skin graft model. Human self-assembled skin substitutes (SASSs) were prepared and grafted to athymic mice either by the conventional method or by the new grafting method. Graft healing and complications were assessed using digital photographs on postoperative days 7, 14, and 21. Similar structure and organization were observed by histological staining. The new grafting method reduced medium and large displacement events by 1.26-fold and medium and large contraction events by 1.8-fold, leading to a 1.6-fold increase in graft surface area compared to skin substitutes grafted with the usual method. This innovation ensures better reproducibility and consistency of skin substitute transplants on mice

Vertical transmission of hepatitis C virus: A tale of multiple outcomes

Globally, hepatitis C virus (HCV) infection affects approximately 130 million people and 3 million new infections occur annually. HCV is also recognized as an important cause of chronic liver disease in children. The absence of proofreading properties of the HCV RNA polymerase leads to a highly error prone replication process, allowing HCV to escape host immune response. The adaptive nature of HCV evolution dictates the outcome of the disease in many ways. Here, we investigated the molecular evolution of HCV in three unrelated children who acquired chronic HCV infection as a result of mother-to-child transmission, two of whom were also coinfected with HIV-1. The persistence of discrete HCV variants and their population structure were assessed using median joining network and Bayesian approaches. While patterns of viral evolution clearly differed between subjects, immune system dysfunction related to HIV coinfection or persistent HCV seronegativity stand as potential mechanisms to explain the lack of molecular evolution observed in these three cases. In contrast, treatment of HCV infection with PegIFN, which did not lead to sustained virologic responses in all 3 cases, was not associated with commensurate variations in the complexity of the variant spectrum. Finally, the differences in the degree of divergence suggest that the mode of transmission of the virus was not the main factor driving viral evolution. (C) 2013 Elsevier B. V. All rights reserved

The uracil-DNA glycosylase UNG protects the fitness of normal and cancer B cells expressing AID

Abstract In B lymphocytes, the uracil N-glycosylase (UNG) excises genomic uracils made by activation-induced deaminase (AID), thus underpinning antibody gene diversification and oncogenic chromosomal translocations, but also initiating faithful DNA repair. Ung−/− mice develop B-cell lymphoma (BCL). However, since UNG has anti- and pro-oncogenic activities, its tumor suppressor relevance is unclear. Moreover, how the constant DNA damage and repair caused by the AID and UNG interplay affects B-cell fitness and thereby the dynamics of cell populations in vivo is unknown. Here, we show that UNG specifically protects the fitness of germinal center B cells, which express AID, and not of any other B-cell subset, coincident with AID-induced telomere damage activating p53-dependent checkpoints. Consistent with AID expression being detrimental in UNG-deficient B cells, Ung−/− mice develop BCL originating from activated B cells but lose AID expression in the established tumor. Accordingly, we find that UNG is rarely lost in human BCL. The fitness preservation activity of UNG contingent to AID expression was confirmed in a B-cell leukemia model. Hence, UNG, typically considered a tumor suppressor, acquires tumor-enabling activity in cancer cell populations that express AID by protecting cell fitness

Understanding the impacts of the COVID-19 pandemic on the care experiences of people with mental-physical multimorbidity : protocol for a mixed methods study

Background: Primary care and other health services have been disrupted during the COVID-19 pandemic, yet the consequences of these service disruptions on patients’ care experiences remain largely unstudied. People with mental-physical multimorbidity are vulnerable to the effects of the pandemic, and to sudden service disruptions. It is thus essential to better understand how their care experiences have been impacted by the current pandemic. This study aims to improve understanding of the care experiences of people with mental-physical multimorbidity during the pandemic and identify strategies to enhance these experiences. Methods: We will conduct a mixed-methods study with multi-phase approach involving four distinct phases. Phase 1 will be a qualitative descriptive study in which we interview individuals with mental-physical multimorbidity and health professionals in order to explore the impacts of the pandemic on care experiences, as well as their perspectives on how care can be improved. The results of this phase will inform the design of study phases 2 and 3. Phase 2 will involve journey mapping exercises with a sub-group of participants with mental-physical multimorbidity to visually map out their care interactions and experiences over time and the critical moments that shaped their experiences. Phase 3 will involve an online, cross-sectional survey of care experiences administered to a larger group of people with mental disorders and/or chronic physical conditions. In phase 4, deliberative dialogues will be held with key partners to discuss and plan strategies for improving the delivery of care to people with mental-physical multimorbidity. Pre-dialogue workshops will enable us to synthesize an prepare the results from the previous three study phases. Discussion: Our study results will generate much needed evidence of the positive and negative impacts of the COVID-19 pandemic on the care experiences of people with mental-physical multimorbidity and shed light on strategies that could improve care quality and experiences.Applied Science, Faculty ofNon UBCNursing, School ofReviewedFacultyResearcherOthe

Understanding the impacts of the COVID-19 pandemic on the care experiences of people with mental-physical multimorbidity: protocol for a mixed methods study

Background: Primary care and other health services have been disrupted during the COVID-19 pandemic, yet the consequences of these service disruptions on patients' care experiences remain largely unstudied. People with mental-physical multimorbidity are vulnerable to the effects of the pandemic, and to sudden service disruptions. It is thus essential to better understand how their care experiences have been impacted by the current pandemic. This study aims to improve understanding of the care experiences of people with mental-physical multimorbidity during the pandemic and identify strategies to enhance these experiences. Methods: We will conduct a mixed-methods study with multi-phase approach involving four distinct phases. Phase 1 will be a qualitative descriptive study in which we interview individuals with mental-physical multimorbidity and health professionals in order to explore the impacts of the pandemic on care experiences, as well as their perspectives on how care can be improved. The results of this phase will inform the design of study phases 2 and 3. Phase 2 will involve journey mapping exercises with a sub-group of participants with mental-physical multimorbidity to visually map out their care interactions and experiences over time and the critical moments that shaped their experiences. Phase 3 will involve an online, cross-sectional survey of care experiences administered to a larger group of people with mental disorders and/or chronic physical conditions. In phase 4, deliberative dialogues will be held with key partners to discuss and plan strategies for improving the delivery of care to people with mental-physical multimorbidity. Pre-dialogue workshops will enable us to synthesize an prepare the results from the previous three study phases. Discussion: Our study results will generate much needed evidence of the positive and negative impacts of the COVID-19 pandemic on the care experiences of people with mental-physical multimorbidity and shed light on strategies that could improve care quality and experiences.</p

Functional repair assay for the diagnosis of constitutional mismatch repair deficiency from non-neoplastic tissue

Purpose: Constitutional mismatch repair deficiency (CMMRD) is a highly penetrant cancer predisposition syndrome caused by biallelic mutations in mismatch repair (MMR) genes. As several cancer syndromes are clinically similar, accurate diagnosis is critical to cancer screening and treatment. As genetic diagnosis is confounded by 15 or more pseudogenes and variants of uncertain significance, a robust diagnostic assay is urgently needed. We sought to determine whether an assay that directly measures MMR activity could accurately diagnose CMMRD.Patients and Methods: In vitro MMR activity was quantified using a 3\u27-nicked G-T mismatched DNA substrate, which requires MSH2-MSH6 and MLH1-PMS2 for repair. We quantified MMR activity from 20 Epstein-Barr virus-transformed lymphoblastoid cell lines from patients with confirmed CMMRD. We also tested 20 lymphoblastoid cell lines from patients who were suspected for CMMRD. We also characterized MMR activity from patients with neurofibromatosis type 1, Li-Fraumeni syndrome, polymerase proofreading-associated cancer syndrome, and Lynch syndrome.Results: All CMMRD cell lines had low MMR activity (n = 20; mean, 4.14 ± 1.56%) relative to controls (n = 6; mean, 44.00 ± 8.65%; P \u3c .001). Repair was restored by complementation with the missing protein, which confirmed MMR deficiency. All cases of patients with suspected CMMRD were accurately diagnosed. Individuals with Lynch syndrome (n = 28), neurofibromatosis type 1 (n = 5), Li-Fraumeni syndrome (n = 5), and polymerase proofreading-associated cancer syndrome (n = 3) had MMR activity that was comparable to controls. To accelerate testing, we measured MMR activity directly from fresh lymphocytes, which yielded results in 8 days.Conclusion: On the basis of the current data set, the in vitro G-T repair assay was able to diagnose CMMRD with 100% specificity and sensitivity. Rapid diagnosis before surgery in non-neoplastic tissues could speed proper therapeutic management