Pharmacotherapeutic Interventions in People Living With HIV Undergoing Solid Organ Transplantation: A Scoping Review.

The pharmacotherapeutic management of people living with HIV (PLWHIV) undergoing solid organ transplantation (SOT) is clinically challenging, mainly due to the frequent occurrence of complex drug-drug interactions. Although various strategies have been proposed to improve treatment outcomes in these patients, several uncertainties remain, and consensus practice guidelines are just beginning to emerge. The main objective of this scoping review was to map the extent of the literature on the pharmacotherapeutic interventions performed by healthcare professionals for PLWHIV undergoing SOT. Methods: We searched Medline, Embase, and the Cochrane databases as well as gray literature for articles published between January 2010 and February 2020. Study selection was performed by at least 2 independent reviewers. Articles describing pharmacotherapeutic interventions in PLWHIV considered for or undergoing SOT were included in the study. Results: Of the 12 599 references identified through our search strategy, 209 articles met the inclusion criteria. Results showed that the vast majority of reported pharmacotherapeutic interventions concerned the management of immunosuppressive and antimicrobial therapy, including antiretrovirals. Analysis of the data demonstrated that for several aspects of the pharmacotherapeutic management of PLWHIV undergoing SOT, there were differing practices, such as the choice of immunosuppressive induction and maintenance therapy. Other important aspects of patient management, such as patient counseling, were rarely reported. Conclusions: Our results constitute an extensive overview of current practices in the pharmacotherapeutic management of SOT in PLWHIV and identify knowledge gaps that should be addressed to help improve patient care in this specific population.

Physical Activity Program for the Survival of Elderly Patients With Lymphoma: Study Protocol for Randomized Phase 3 Trial.

BACKGROUND: The practice of regular physical activity can reduce the incidence of certain cancers (colon, breast, and prostate) and improve overall survival after treatment by reducing fatigue and the risk of relapse. This impact on survival has only been demonstrated in active patients with lymphoma before and after treatment. As poor general health status reduces the chances of survival and these patients are most likely to also have sarcopenia, it is important to be able to improve their physical function through adapted physical activity (APA) as part of supportive care management. Unfortunately, APA is often saved for patients with advanced blood cancer. As a result, there is a lack of data regarding the impact of standardized regular practice of APA and concomitant chemotherapy as first-line treatment on lymphoma survival. OBJECTIVE: This study aimed to assess the impact of a new and open rehabilitation program suitable for a frail population of patients treated for diffuse large B-cell lymphoma (DLBCL). METHODS: PHARAOM (Physical Activity Program for the Survival of Elderly Patients with Lymphoma) is a phase 3 randomized (1:1) study focusing on a frail population of patients treated for DLBCL. The study will include 186 older adult patients with DLBCL (aged >65 years) receiving rituximab and chemotherapy. Overall, 50% (93/186) of patients (investigational group) will receive APA along with chemotherapy, and they will be supervised by a dedicated qualified kinesiologist. The APA program will include endurance and resistance training at moderate intensity 3 times a week during the 6 months of chemotherapy. The primary end point of this study will be event-free survival of the patients. The secondary end points will include the overall survival, progression-free survival, prevalence of sarcopenia and undernutrition, and patients' quality of life. This study will be conducted in accordance with the principles of the Declaration of Helsinki. RESULTS: Recruitment, enrollment, and data collection began in February 2021, and 4 participants have been enrolled in the study as of July 2022. Data analysis will begin after the completion of data collection. Future outcomes will be published in peer-reviewed health-related research journals and presented at national congress, and state professional meetings. This publication is based on protocol version 1.1, August 3, 2020. CONCLUSIONS: The PHARAOM study focuses on highlighting the benefits of APA intervention on survival during the period of first-line treatment of patients with DLBCL. This study could also contribute to our understanding of how an APA program can reduce complications such as sarcopenia in patients with lymphoma and improve their quality of life. By documenting the prevalence and relationship between sarcopenia and exercise load, we might be able to help physicians plan better interventions in the care of patients with DLBCL. TRIAL REGISTRATION: ClinicalTrials.gov NCT04670029; https://clinicaltrials.gov/ct2/show/NCT04670029. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/40969.

Ceftazidime-Induced Neurotoxicity in an 80-Year-Old Female With Renal Dysfunction: A Case Report.

Neurological toxicity is a relatively rare adverse reaction reported in elderly patients treated with cephalosporins. We present a case of ceftazidime-induced encephalopathy in the context of acute kidney injury in an 80-year-old female treated for a Pseudomonas aeruginosa prosthetic joint infection. During the course of treatment, the patient developed sudden confusion and disorientation. The patient's mental state progressively worsened, eventually leading to intubation and admission to the intensive care unit. As imaging and laboratory analyses revealed no alternative causes explaining the patient's symptoms, ceftazidime was stopped under the suspicion of drug-induced neurotoxicity. Shortly after ceftazidime discontinuation, the patient's condition drastically improved and returned to baseline within 5 days. This case reveals the potential severity of cephalosporin-induced neurotoxicity in elderly patients and highlights the importance of quickly detecting such adverse events in order to prevent dire outcomes.

Reducing low-value testing in the emergency department through cost-effective physician education and personalised audit and feedback scorecards.

OBJECTIVES: Delivery of low-value healthcare impacts patients, resources, and overall healthcare sustainability. In Canada, an estimated 30% of tests, treatments, and procedures are unnecessary. As primary decision-makers, physicians have a major influence on healthcare utilisation. Despite numerous approaches to reduce low-value testing, success has been limited. Audit and feedback strategies have demonstrated variable effects in changing physician practice and often do not consider resource requirements. The objective of this study is to evaluate a resource-effective approach to decrease low-value testing in the emergency department (ED) through online education and personalised audit and feedback scorecards for two common ED tests. METHODS: A single-centre, prospective pre-post trial of 31 ED physician's ordering rates of urine cultures and rib X-rays was conducted at an academic community hospital in Ottawa, Ontario. The study included educational interventions on appropriate ordering guidelines and personalised audit and feedback scorecards from 2019 to 2020. RESULTS: There was a 36.9 and 81.6% relative reduction in urine culture and rib X-ray ordering, respectively, between the baseline intervention and the 12-month post-scorecard period (p < 0.01). The group dispersion in ordering rates during the post-scorecard period was smaller compared to the wide dispersion at baseline. The rate of return ED visits for both tests remained unchanged. Variable cost analysis demonstrated $53,300 in cost-savings from reduced testing rates during the study period. The total study cost was $15,000. INTERPRETATION: The combination of online education and personalised audit and feedback scorecards may present a resource-effective approach to change physician practice and reduce low-value testing in the ED. Further studies are needed to examine this approach in other departments and clinical topics in Canada.

RéSUMé: OBJECTIFS: La prestation de soins de santé de faible valeur a un impact sur les patients, les ressources et la durabilité globale des soins de santé. Au Canada, on estime que 30 % des tests, des traitements et des procédures sont inutiles. En tant que principaux décideurs, les médecins ont une influence majeure sur l'utilisation des soins de santé. Malgré de nombreuses approches visant à réduire les tests de faible valeur, le succès a été limité. Les stratégies de vérification et de rétroaction ont démontré des effets variables sur l'évolution de la pratique des médecins et ne tiennent souvent pas compte des besoins en ressources. L'objectif de cette étude est d'évaluer une approche efficace en termes de ressources pour réduire les tests de faible valeur dans le service des urgences grâce à une formation en ligne et à des fiches d'audit personnalisés et de rétroaction pour deux tests courants aux urgences. MéTHODES: Un essai prospectif avant-après dans un seul centre portant sur les taux de prescription de cultures d'urine et de radiographies des côtes par trente et un médecins du service d'urgence a été mené dans un hôpital communautaire universitaire à Ottawa, en Ontario. L'étude comprenait des interventions éducatives sur les directives de commande appropriées et des fiches d'audit et de retour d'information personnalisées de 2019 à 2020. RéSULTATS: Il y avait une réduction relative de 36,9 % et 81,6 % de la culture d'urine et de la commande de radiographies des côtes respectivement, entre l'intervention de base et la période de 12 mois après la fiche de notation (p < 0,01). La dispersion des groupes dans les taux de commande au cours de la période post-bilan était plus faible par rapport à la large dispersion au départ. Le taux de retour des visites aux urgences pour les deux tests est resté inchangé. L'analyse des coûts variables a montré que la réduction des taux de dépistage pendant la période d'étude a permis de réaliser des économies de 53 300 dollars. Le coût total de l'étude s'est élevé à 15 000 dollars. INTERPRéTATION: L'association d'une formation en ligne et de fiches d'audit et de retour d'information personnalisées peut constituer une approche efficace en termes de ressources pour modifier les pratiques des médecins et réduire les tests à faible valeur dans les urgences. D'autres études sont nécessaires pour examiner cette approche dans d'autres départements et sujets cliniques au Canada.

Neuromuscular, Psychological, and Sleep Predictors of Cancer-Related Fatigue in Cancer Patients.

BACKGROUND: Cancer-related fatigue (CRF) is the most reported side effect of cancer and its treatments. This distressing sense of exhaustion critically impairs quality of life and can persist for years after treatment completion. Mechanisms of CRF are multidimensional (eg, physical, psychological, or behavioral), suggesting the need for a complex assessment. Nevertheless, CRF remains assessed mainly with 1-dimensional questionnaires. The purpose of this study was to test whether neuromuscular parameters enhance a model including well-known predictors of CRF. PATIENTS AND METHODS: Forty-five participants with cancer history completed self-assessment questionnaires about quality of life, CRF, sleep disturbances, and emotional symptoms. They also completed a 5-minute handgrip fatiguing test composed of 60 maximal voluntary contractions to assess neuromuscular fatigability. Hierarchical linear regression analyses were performed to determine whether the neuromuscular fatigability threshold improved the FA12 score prediction beyond that provided by anxiety/depression and sleep disturbances. RESULTS: The hierarchical linear regression analysis evidenced that a model including anxiety/depression, sleep disturbances, and neuromuscular fatigability explained 56% of CRF variance. In addition, the results suggest that the mechanisms leading to CRF may be different from one person to another. CONCLUSION: Results revealed that sleep disturbances, emotional symptoms, and neuromuscular fatigability were the most important CRF predictors in cancer patients. This information could be useful for healthcare professionals offering tailored, individual support to patients with CRF.

Sexual quality of life evaluation after treatment among women with breast cancer under 35 years old.

PURPOSE: To qualify the quality of patients sexual lives after treatment among women with breast cancer under 35 years old and compare results to the literature. METHODS: Sexual quality of life was measured for 84 women aged 20 to 35 years old at diagnosis, with two validated quality of sexual life questionnaires, Brief Index of Sexual Functioning for Women (BISF-W) and Female Sexual Function Index (FSFI), at least six months after breast cancer diagnosis. Two other questionnaires were used to allow us to understand other aspects of their life before cancer and to monitor quality of sexual life during treatment. RESULTS: Forty-three women responded to the questionnaire. The questionnaires demonstrated that more than half of them had problems with their sexuality. The mean total score was 28.08/75 for BISF-W and 25.1 for FSFI (under the cutoff score 26.55). The domain analysis showed an association between the absence of chemotherapy and scores in regard to sexual health. Only 7% had sexual disturbance detected but 49% of the patients wished to have it. CONCLUSION: Sexual dysfunction in breast cancer survivors is real, has several factors, and cannot be evaluated based only on the organic side effects induced by cancer treatment. Better monitoring and screening seems necessary in order to optimize the quality of sexual life after surviving breast cancer.

The shieldin complex mediates 53BP1-dependent DNA repair.

53BP1 is a chromatin-binding protein that regulates the repair of DNA double-strand breaks by suppressing the nucleolytic resection of DNA termini1,2. This function of 53BP1 requires interactions with PTIP3 and RIF14-9, the latter of which recruits REV7 (also known as MAD2L2) to break sites10,11. How 53BP1-pathway proteins shield DNA ends is currently unknown, but there are two models that provide the best potential explanation of their action. In one model the 53BP1 complex strengthens the nucleosomal barrier to end-resection nucleases12,13, and in the other 53BP1 recruits effector proteins with end-protection activity. Here we identify a 53BP1 effector complex, shieldin, that includes C20orf196 (also known as SHLD1), FAM35A (SHLD2), CTC-534A2.2 (SHLD3) and REV7. Shieldin localizes to double-strand-break sites in a 53BP1- and RIF1-dependent manner, and its SHLD2 subunit binds to single-stranded DNA via OB-fold domains that are analogous to those of RPA1 and POT1. Loss of shieldin impairs non-homologous end-joining, leads to defective immunoglobulin class switching and causes hyper-resection. Mutations in genes that encode shieldin subunits also cause resistance to poly(ADP-ribose) polymerase inhibition in BRCA1-deficient cells and tumours, owing to restoration of homologous recombination. Finally, we show that binding of single-stranded DNA by SHLD2 is critical for shieldin function, consistent with a model in which shieldin protects DNA ends to mediate 53BP1-dependent DNA repair.

Influence of an Adapted Physical Activity Program on Self-Esteem and Quality of Life of Breast Cancer Patients after Mastectomy.

This study aimed to assess the influence of an adapted physical activity program on self-esteem and quality of life in breast cancer patients. Twenty-three women diagnosed with breast cancer and treated by mastectomy formed 2 groups. The experimental group practiced adapted physical activity for 12 weeks, while the control group did not. All participants answered questionnaires regarding their self-esteem and quality of life at the beginning of the program and 6 and 12 weeks after that. Self-esteem, physical self-perception, quality of life, global health status, pain, and breast symptoms were improved only in the group which practiced adapted physical activity.

Therapeutic drug monitoring in treatment-experienced HIV-infected patients receiving darunavir-based salvage regimens: A case series.

Therapeutic drug monitoring (TDM) constitutes a compelling approach for the optimization of antiretroviral therapy in treatment-experienced HIV-1 patients. While various inhibitory indices have been proposed to predict virologic outcome, there is a lack of consensus on the clinical value of TDM. Here, we report the comparative results of TDM in 14 HIV-1-infected patients who had previously received at least two different PI-based regimens and who initiated darunavir (DRV)-based salvage therapy. Pharmacokinetic/pharmacodynamics (PK/PD) parameters were calculated for each subject. Seventy-nine percent of subjects had a viral load <50 copies/mL at 48 weeks. The only subject with two consecutive viral loads >50 copies/mL at the end of the study period was the patient with the lowest instantaneous inhibitory potential (IIP). The sample size was insufficient to show an association between any of the PK/PD parameters and virologic response. Based on our observations, we suggest that the utility of IIP for antiretroviral combinations for the prediction of virologic outcome in HIV-1 drug-experienced patients should be studied further.

Personalizing antiplatelet therapies: What have we learned from recent trials?

Dual antiplatelet therapy with aspirin and a P2Y12 receptor antagonist is currently the standard of care for the prevention of ischemic events in patients with acute coronary syndrome or undergoing percutaneous coronary intervention. Several studies have shown that not all patients benefit from the treatment to the same degree and demonstrated that high on-treatment platelet reactivity may be associated with an increased risk of thrombotic events, while low on-treatment platelet reactivity may be linked to a higher risk of bleeding. Personalized antiplatelet treatment strategies based on platelet function monitoring and genetic testing constitute a promising tool for the prevention of both stent thrombosis and bleeding events, but conclusive evidence that such approaches can improve clinical outcomes is lacking. This review presents the most recent studies on tailored antiplatelet therapy in the management of coronary heart disease, with a focus on the prognosis value of platelet function testing.

Randomized Trial Comparing a Web-Mediated Follow-up With Routine Surveillance in Lung Cancer Patients.

Background: The use of web-based monitoring for lung cancer patients is growing in interest because of promising recent results suggesting improvement in cancer and resource utilization outcomes. It remains an open question whether the overall survival (OS) in these patients could be improved by using a web-mediated follow-up rather than classical scheduled follow-up and imaging. Methods: Advanced-stage lung cancer patients without evidence of disease progression after or during initial treatment were randomly assigned in a multicenter phase III trial to compare a web-mediated follow-up algorithm (experimental arm), based on weekly self-scored patient symptoms, with routine follow-up with CT scans scheduled every three to six months according to the disease stage (control arm). In the experimental arm, an alert email was automatically sent to the oncologist when self-scored symptoms matched predefined criteria. The primary outcome was OS. Results: From June 2014 to January 2016, 133 patients were enrolled and 121 were retained in the intent-to-treat analysis; 12 deemed ineligible after random assignment were not subsequently followed. Most of the patients (95.1%) had stage III or IV disease. The median follow-up was nine months. The median OS was 19.0 months (95% confidence interval [CI] = 12.5 to noncalculable) in the experimental and 12.0 months (95% CI = 8.6 to 16.4) in the control arm (one-sided P = .001) (hazard ratio = 0.32, 95% CI = 0.15 to 0.67, one-sided P = .002). The performance status at first detected relapse was 0 to 1 for 75.9% of the patients in the experimental arm and for 32.5% of those in the control arm (two-sided P < .001). Optimal treatment was initiated in 72.4% of the patients in the experimental arm and in 32.5% of those in the control arm (two-sided P < .001). Conclusions: A web-mediated follow-up algorithm based on self-reported symptoms improved OS due to early relapse detection and better performance status at relapse.

APOBEC3A damages the cellular genome during DNA replication.

The human APOBEC3 family of DNA-cytosine deaminases comprises 7 members (A3A-A3H) that act on single-stranded DNA (ssDNA). The APOBEC3 proteins function within the innate immune system by mutating DNA of viral genomes and retroelements to restrict infection and retrotransposition. Recent evidence suggests that APOBEC3 enzymes can also cause damage to the cellular genome. Mutational patterns consistent with APOBEC3 activity have been identified by bioinformatic analysis of tumor genome sequences. These mutational signatures include clusters of base substitutions that are proposed to occur due to APOBEC3 deamination. It has been suggested that transiently exposed ssDNA segments provide substrate for APOBEC3 deamination leading to mutation signatures within the genome. However, the mechanisms that produce single-stranded substrates for APOBEC3 deamination in mammalian cells have not been demonstrated. We investigated ssDNA at replication forks as a substrate for APOBEC3 deamination. We found that APOBEC3A (A3A) expression leads to DNA damage in replicating cells but this is reduced in quiescent cells. Upon A3A expression, cycling cells activate the DNA replication checkpoint and undergo cell cycle arrest. Additionally, we find that replication stress leaves cells vulnerable to A3A-induced DNA damage. We propose a model to explain A3A-induced damage to the cellular genome in which cytosine deamination at replication forks and other ssDNA substrates results in mutations and DNA breaks. This model highlights the risk of mutagenesis by A3A expression in replicating progenitor cells, and supports the emerging hypothesis that APOBEC3 enzymes contribute to genome instability in human tumors.

A mechanism for the suppression of homologous recombination in G1 cells.

DNA repair by homologous recombination is highly suppressed in G1 cells to ensure that mitotic recombination occurs solely between sister chromatids. Although many homologous recombination factors are cell-cycle regulated, the identity of the events that are both necessary and sufficient to suppress recombination in G1 cells is unknown. Here we report that the cell cycle controls the interaction of BRCA1 with PALB2-BRCA2 to constrain BRCA2 function to the S/G2 phases in human cells. We found that the BRCA1-interaction site on PALB2 is targeted by an E3 ubiquitin ligase composed of KEAP1, a PALB2-interacting protein, in complex with cullin-3 (CUL3)-RBX1 (ref. 6). PALB2 ubiquitylation suppresses its interaction with BRCA1 and is counteracted by the deubiquitylase USP11, which is itself under cell cycle control. Restoration of the BRCA1-PALB2 interaction combined with the activation of DNA-end resection is sufficient to induce homologous recombination in G1, as measured by RAD51 recruitment, unscheduled DNA synthesis and a CRISPR-Cas9-based gene-targeting assay. We conclude that the mechanism prohibiting homologous recombination in G1 minimally consists of the suppression of DNA-end resection coupled with a multi-step block of the recruitment of BRCA2 to DNA damage sites that involves the inhibition of BRCA1-PALB2-BRCA2 complex assembly. We speculate that the ability to induce homologous recombination in G1 cells with defined factors could spur the development of gene-targeting applications in non-dividing cells.

Analysis of the Histone H3.1 Interactome: A Suitable Chaperone for the Right Event.

Despite minimal disparity at the sequence level, mammalian H3 variants bind to distinct sets of polypeptides. Although histone H3.1 predominates in cycling cells, our knowledge of the soluble complexes that it forms en route to deposition or following eviction from chromatin remains limited. Here, we provide a comprehensive analysis of the H3.1-binding proteome, with emphasis on its interactions with histone chaperones and components of the replication fork. Quantitative mass spectrometry revealed 170 protein interactions, whereas a large-scale biochemical fractionation of H3.1 and associated enzymatic activities uncovered over twenty stable protein complexes in dividing human cells. The sNASP and ASF1 chaperones play pivotal roles in the processing of soluble histones but do not associate with the active CDC45/MCM2-7/GINS (CMG) replicative helicase. We also find TONSL-MMS22L to function as a H3-H4 histone chaperone. It associates with the regulatory MCM5 subunit of the replicative helicase.

Detection of the HIV-1 minus-strand-encoded antisense protein and its association with autophagy.

HIV-1 proteins are synthesized from a single transcript in an unspliced form or following splicing, but the existence of an antisense protein (ASP) expressed from an antisense polyadenylated transcript has been suggested. Difficulties linked to the detection of this protein in mammalian cells led us to codon optimize its cDNA. Codon-optimized ASP was indeed efficiently detected in various transfected cell lines following flow cytometry and confocal microscopy analyses. Western blot analyses also led to the detection of optimized ASP in transfected cells but also provided evidence of its instability and high multimerization potential. ASP was mainly distributed in the cytoplasm in a punctate manner, which was reminiscent of autophagosomes. In agreement with this observation, a significant increase in ASP-positive cells and loss of its punctate distribution was observed in transfected cells when autophagy was inhibited at early steps. Induction of autophagy was confirmed by Western blot analyses that showed an ASP-mediated increase in levels of LC3b-II and Beclin 1, as well as colocalization and interaction between ASP and LC3. Interestingly, Myc-tagged ASP was detected in the context of proviral DNA following autophagy inhibition with a concomitant increase in the level and punctate distribution of LC3b-II. Finally, 3-methyladenine treatment of transfected or infected U937 cells decreased extracellular p24 levels in wild-type proviral DNA and to a much lesser extent in ASP-mutated proviral DNA. This study provides the first detection of ASP in mammalian cells by Western blotting. ASP-induced autophagy might explain the inherent difficulty in detecting this viral protein and might justify its presumed low abundance in infected cells.

Codon-usage-based inhibition of HIV protein synthesis by human schlafen 11.

In mammals, one of the most pronounced consequences of viral infection is the induction of type I interferons, cytokines with potent antiviral activity. Schlafen (Slfn) genes are a subset of interferon-stimulated early response genes (ISGs) that are also induced directly by pathogens via the interferon regulatory factor 3 (IRF3) pathway. However, many ISGs are of unknown or incompletely understood function. Here we show that human SLFN11 potently and specifically abrogates the production of retroviruses such as human immunodeficiency virus 1 (HIV-1). Our study revealed that SLFN11 has no effect on the early steps of the retroviral infection cycle, including reverse transcription, integration and transcription. Rather, SLFN11 acts at the late stage of virus production by selectively inhibiting the expression of viral proteins in a codon-usage-dependent manner. We further find that SLFN11 binds transfer RNA, and counteracts changes in the tRNA pool elicited by the presence of HIV. Our studies identified a novel antiviral mechanism within the innate immune response, in which SLFN11 selectively inhibits viral protein synthesis in HIV-infected cells by means of codon-bias discrimination.

Viral E3 ubiquitin ligase-mediated degradation of a cellular E3: viral mimicry of a cellular phosphorylation mark targets the RNF8 FHA domain.

Viral hijacking of cellular processes relies on the ability to mimic the structure or function of cellular proteins. Many viruses encode ubiquitin ligases to facilitate infection, although the mechanisms by which they select their substrates are often unknown. The Herpes Simplex Virus type-1-encoded E3 ubiquitin ligase, ICP0, promotes infection through degradation of cellular proteins, including the DNA damage response E3 ligases RNF8 and RNF168. Here we describe a mechanism by which this viral E3 hijacks a cellular phosphorylation-based targeting strategy to degrade RNF8. By mimicking a cellular phosphosite, ICP0 binds RNF8 via the RNF8 forkhead associated (FHA) domain. Phosphorylation of ICP0 T67 by CK1 recruits RNF8 for degradation and thereby promotes viral transcription, replication, and progeny production. We demonstrate that this mechanism may constitute a broader viral strategy to target other cellular factors, highlighting the importance of this region of the ICP0 protein in countering intrinsic antiviral defenses.

APOBEC3 proteins and genomic stability: the high cost of a good defense.

The human APOBEC3 family of cytidine deaminases constitutes a cellular intrinsic defense mechanism that is effective against a range of viruses and retro-elements. While it is well established that these enzymes are powerful mutators of viral DNA, the possibility that their activity could threaten the integrity of the host genome has only recently begun to be investigated. Here, we discuss the implications of new evidence suggesting that APOBEC3 proteins can mediate the deamination of cellular DNA. The maintenance of genomic integrity in the face of this potential off-target activity must require high fidelity DNA repair and strict regulation of APOBEC3 gene expression and enzyme activity. Conversely, the ability of specific members of the APOBEC3 family to activate DNA damage signaling pathways might also reflect another way that these proteins contribute to the host immune response.

Activation of LTRs from different human endogenous retrovirus (HERV) families by the HTLV-1 tax protein and T-cell activators.

Human endogenous retroviruses (HERVs) represent approximately 8% of our genome. HERVs influence cellular gene expression and contribute to normal physiological processes such as cellular differentiation and morphogenesis. HERVs have also been associated with certain pathological conditions, including cancer and neurodegenerative diseases. As HTLV-1 causes adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and has been shown to modulate host gene expression mainly through the expression of the powerful Tax transactivator, herein we were interested in looking at the potential modulation capacity of HTLV-1 Tax on HERV expression. In order to evaluate the promoter activity of different HERV LTRs, pHERV-LTR-luc constructs were co-transfected in Jurkat T-cells with a Tax expression vector. Tax expression potently increased the LTR activity of HERV-W8 and HERV-H (MC16). In parallel, Jurkat cells were also stimulated with different T-cell-activating agents and HERV LTRs were observed to respond to different combination of Forskolin, bpV[pic] a protein tyrosine phosphatase inhibitor, and PMA. Transfection of expression vectors for different Tax mutants in Jurkat cells showed that several transcription factors including CREB appeared to be important for HERV-W8 LTR activation. Deletion mutants were derived from the HERV-W8 LTR and the region from -137 to -123 was found to be important for LTR response following Tax expression in Jurkat cells, while a different region was shown to be required in cells treated with activators. Our results thus demonstrated that HTLV-1 Tax activates several HERV LTRs. This raises the possibility that upregulated HERV expression could be involved in diseases associated with HTLV-1 infection.

Polarized expression of the membrane ASP protein derived from HIV-1 antisense transcription in T cells.

BACKGROUND: Retroviral gene expression generally depends on a full-length transcript that initiates in the 5' LTR, which is either left unspliced or alternatively spliced. We and others have demonstrated the existence of antisense transcription initiating in the 3' LTR in human lymphotropic retroviruses, including HTLV-1, HTLV-2, and HIV-1. Such transcripts have been postulated to encode antisense proteins important for the establishment of viral infections. The antisense strand of the HIV-1 proviral DNA contains an ORF termed asp, coding for a highly hydrophobic protein. However, although anti-ASP antibodies have been described to be present in HIV-1-infected patients, its in vivo expression requires further support. The objective of this present study was to clearly demonstrate that ASP is effectively expressed in infected T cells and to provide a better characterization of its subcellular localization. RESULTS: We first investigated the subcellular localization of ASP by transfecting Jurkat T cells with vectors expressing ASP tagged with the Flag epitope to its N-terminus. Using immunofluorescence microscopy, we found that ASP localized to the plasma membrane in transfected Jurkat T cells, but with different staining patterns. In addition to an entire distribution to the plasma membrane, ASP showed an asymmetric localization and could also be detected in membrane connections between two cells. We then infected Jurkat T cells with NL4.3 virus coding for ASP tagged with the Flag epitope at its C-terminal end. By this approach, we were capable of showing that ASP is effectively expressed from the HIV-1 3' LTR in infected T cells, with an asymmetric localization of the viral protein at the plasma membrane. CONCLUSION: These results demonstrate for the first time that ASP can be detected when expressed from full-length HIV-1 proviral DNA and that its localization is consistent with Jurkat T cells overexpressing ASP.