Publications by authors named "Eric Wong"

454 Publications

Deprescribing fall-risk increasing drugs (FRIDs) for the prevention of falls and fall-related complications: a systematic review and meta-analysis.

BMJ Open 2021 Feb 10;11(2):e035978. Epub 2021 Feb 10.

Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada.

Objectives: Prevention of falls and fall-related injuries is a priority due to the substantial health and financial burden of falls on patients and healthcare systems. Deprescribing medications known as 'fall-risk increasing drugs' (FRIDs) is a common strategy to prevent falls. We conducted a systematic review to determine its efficacy for the prevention of falls and fall-related complications.

Design: Systematic review and meta-analysis.

Data Sources: MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, CINAHL and grey literature from inception to 1 August 2020.

Eligibility Criteria For Selecting Studies: Randomised controlled trials of FRID withdrawal compared with usual care evaluating the rate of falls, incidence of falls, fall-related injuries, fall-related fractures, fall-related hospitalisations or adverse effects related to the intervention in adults aged ≥65 years.

Data Extraction And Synthesis: Two reviewers independently performed citation screening, data abstraction, risk of bias assessment and certainty of evidence grading. Random-effects models were used for meta-analyses.

Results: Five trials involving 1305 participants met eligibility criteria. Deprescribing FRIDs did not change the rate of falls (rate ratio (RaR) 0.98, 95% CI 0.63 to 1.51), the incidence of falls (risk difference 0.01, 95% CI -0.06 to 0.09; relative risk 1.04, 95% CI 0.86 to 1.26) or rate of fall-related injuries (RaR 0.89, 95% CI 0.57 to 1.39) over a follow-up period of 6-12 months. No trials evaluated the impact of deprescribing FRIDs on fall-related fractures or hospitalisations.

Conclusion: There is a paucity of robust high-quality evidence to support or refute that a FRID deprescribing strategy alone is effective at preventing falls or fall-related injury in older adults. Although there may be other reasons to deprescribe FRIDs, our systematic review found that it may result in little to no difference in the rate or risk of falls as a sole falls reduction strategy.

Prospero Registration Number: CRD42016040203.
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http://dx.doi.org/10.1136/bmjopen-2019-035978DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7878138PMC
February 2021

Blunted sympathetic neurovascular transduction is associated to the severity of obstructive sleep apnea.

Clin Auton Res 2021 Feb 9. Epub 2021 Feb 9.

Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, 1-059D Li Ka Shing Centre for Health Research Innovation, Edmonton, T6G 2E1, Canada.

Purpose: Obstructive sleep apnea (OSA) is a common disorder (~ 4%) that augments sympathetic nerve activity (SNA) and elevates blood pressure. The relationship between sympathetic vasomotor outflow and vascular responsiveness, termed sympathetic neurovascular transduction (sNVT), has been sparsely characterized in patients with OSA. Therefore, we sought to quantify spontaneous sympathetic bursts and related changes in diastolic pressure.

Methods: Twelve participants with variable severities of OSA were recruited. We collected muscle sympathetic nerve activity (MSNA) (microneurography) and beat-by-beat diastolic pressure (finger photoplethysmography) during normoxia (FiO = 0.21) and hyperoxia (FiO = 1.0) to decrease MSNA burst frequency. MSNA burst sequences (i.e. singlets, doublets, triplets and quadruplets) were identified and coupled to changes in diastolic pressure over 15 cardiac cycles as an index of sNVT. sNVT slope for each individual was calculated from the slope of the relationship between peak responses in outcome plotted against normalized burst amplitude.

Results: sNVT slope was unchanged during hyperoxia compared to normoxia (normoxia 0.0024 ± 0.0011 Δ mmHg total activity [a.u.] vs. hyperoxia 0.0029 ± 0.00098 Δ mmHg total activity [a.u.]; p = 0.14). sNVT slope was inversely associated with burst frequency during hyperoxia (r = -0.58; p = 0.04), but not normoxia (r = -0.11; p = 0.71). sNVT slope was inversely associated with the apnea-hypopnea index (AHI) (r = -0.62; p = 0.030), but not after age was considered.

Conclusions: We have demonstrated that the prevailing MSNA frequency is unmatched to the level of sNVT, and this can be altered by acute hyperoxia.
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http://dx.doi.org/10.1007/s10286-021-00784-8DOI Listing
February 2021

Implementation of a multicomponent intervention sign to reduce delirium in orthopaedic inpatients (MIND-ORIENT): a quality improvement project.

BMJ Open Qual 2021 Jan;10(1)

Geriatric Education and Research in Aging Science (GERAS) Centre, McMaster University, Hamilton, Ontario, Canada

Delirium is a serious and common condition that leads to significant adverse health outcomes for hospitalised older adults. It occurs in 30%-55% of patients with hip fractures and is one of the most common postoperative complications in older adults undergoing orthopaedic surgery. Multicomponent, non-pharmacological interventions can reduce delirium incidence by up to 30% but are often challenging to implement as part of routine care. We identified a gap in the delivery of non-pharmacological interventions on an orthopaedic unit. This project aimed to implement a bedside sign on an orthopaedic unit to reduce the occurrence of delirium by prompting staff to use multicomponent evidence-based delirium prevention strategies for at-risk older adults. Quality improvement methods were used to integrate and optimise the use of a bedside 'delirium prevention' sign on an orthopaedic unit.The sign was implemented in four target rooms and sign completion rates increased from 47% to 83% (95% CI 71.7% to 94.9%; p<0.001) over a 10-month period. The sign did not have a significant impact on delirium prevalence. The mean Confusion Assessment Method (CAM)+ rate during the baseline period was 8% with an absolute increase in the intervention period to 11.4% (95% CI 7.2% to 15.8%; p=0.31). There were no significant shifts or trends in the run chart for the proportion of patients with CAM+ scores over time. The sign was well received by staff, who reported it was a worthwhile use of time and prompted use of non-pharmacological interventions. This quality improvement project successfully integrated a novel, low-cost, feasible and evidence-based approach into routine clinical care to support staff to deliver non-pharmacological interventions. Given the increased pressures on front-line staff in hospital, tools that reduce cognitive load at the bedside are important to consider when caring for a vulnerable older adult patient population.
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http://dx.doi.org/10.1136/bmjoq-2020-001186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7853031PMC
January 2021

Evaluation of risk factors for and subsequent mortality from poor graft function (PGF) post allogeneic stem cell transplantation.

Leuk Lymphoma 2021 Jan 31:1-13. Epub 2021 Jan 31.

Department, of Clinical Haematology, Peter MacCallum Cancer/Royal Melbourne Hospital, Parkville, Australia.

Poor Graft Function (PGF) is defined by multi-lineage cytopenias with complete donor chimerism post allogeneic transplantation, Risk factors for and subsequent mortality from PGF were assessed in our transplant cohort. Non-sibling donor [OR 1.97; 95% CI 1.02-3.70], ICU admission [OR 5.28; 95% CI 2.29-11.88] or blood culture positivity within the first 30 days [OR 1.67; 95% CI 1.07-2.62], grade III-IV acute graft vs host disease (GVHD) [OR 4.082; 95% CI 2.31-7.16] and CMV viremia [OR 2.43; 95% CI 1.53-3.88] and were significantly associated with development of PGF. PGF patients without count recovery had a 2 year OS of 6%. Severe GVHD, thrombocytopenia and anemia portended inferior survival and were used to develop a prognostic score for mortality from PGF. This analysis identifies risk factors predictive of PGF and poor survival in those without recovery.
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http://dx.doi.org/10.1080/10428194.2021.1872072DOI Listing
January 2021

A MET Targeting Antibody-Drug Conjugate Overcomes Gemcitabine Resistance in Pancreatic Cancer.

Clin Cancer Res 2021 Jan 15. Epub 2021 Jan 15.

Division of Surgical Oncology, Department of Surgery, Moores Cancer Center, University of California San Diego, La Jolla, California.

Purpose: Pancreatic cancer is an aggressive disease associated with a poor 5-year overall survival. Most patients are ineligible for surgery due to late diagnosis and are treated primarily with chemotherapy with very limited success. Pancreatic cancer is relatively insensitive to chemotherapy due to multiple factors, including reduced bioavailability of drugs to tumor cells. One strategy to improve drug efficacy with reduced toxicity is the development of antibody-drug conjugates (ADC), which have now been used successfully to treat both solid and liquid tumors. Here, we evaluate the efficacy of TR1801-ADC, a newly developed ADC composed of a MET antibody conjugated to the highly potent pyrrolobenzodiazepine toxin-linker, tesirine.

Experimental Design: We first evaluated MET expression and subcellular localization in pancreatic cancer cell lines, human tumors, and patient-derived xenografts (PDX). We then tested TR1801-ADC efficacy in pancreatic cancer cell lines. Preclinical evaluation of TR1801-ADC efficacy was conducted on PDXs selected on the basis of their MET expression level.

Results: We show that MET is highly expressed and located at the plasma membrane of pancreatic cancer cells. We found that TR1801-ADC induces a specific cytotoxicity in pancreatic cancer cell lines and a profound tumor growth inhibition, even in a gemcitabine-resistant tumor. We also noted synergism between TR1801-ADC and gemcitabine and an improved response to the combination .

Conclusions: Together, these results suggest the promise of agents such as TR1801-ADC as a novel approach to the treatment of pancreatic cancer.
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http://dx.doi.org/10.1158/1078-0432.CCR-20-3210DOI Listing
January 2021

Inhaled nitric oxide improves ventilatory efficiency and exercise capacity in patients with mild COPD: A randomized-control cross-over trial.

J Physiol 2021 Mar 25;599(5):1665-1683. Epub 2021 Jan 25.

Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.

Key Points: Patients with mild chronic obstructive pulmonary disease (COPD) have an elevated ventilatory equivalent to CO production ( / ) during exercise, secondary to increased dead space ventilation. The reason for the increased dead space is unclear, although pulmonary microvascular dysfunction and the corresponding capillary hypoperfusion is a potential mechanism. Despite emerging evidence that mild COPD is associated with pulmonary microvascular dysfunction, limited research has focused on experimentally modulating the pulmonary microvasculature during exercise in mild COPD. The present study sought to examine the effect of inhaled nitric oxide (iNO), a selective pulmonary vasodilator, on / , dyspnoea and exercise capacity in patients with mild COPD. Experimental iNO increased peak oxygen uptake in mild COPD, secondary to reduced / and dyspnoea. This is the first study to demonstrate that experimental manipulation of the pulmonary circulation alone, can positively impact dyspnoea and exercise capacity in mild COPD.

Abstract: Patients with mild chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory response to exercise, contributing to dyspnoea and exercise intolerance. Previous research in mild COPD has demonstrated an elevated ventilatory equivalent to CO production ( / ) during exercise, secondary to increased dead space ventilation. The reason for the increased dead space is unclear, although pulmonary microvascular dysfunction and the corresponding capillary hypoperfusion is a potential mechanism. The present study tested the hypothesis that inhaled nitric oxide (iNO), a selective pulmonary vasodilator, would lower / and dyspnoea, and improve exercise capacity in patients with mild COPD. In this multigroup randomized-control cross-over study, 15 patients with mild COPD (FEV = 89 ± 11% predicted) and 15 healthy controls completed symptom-limited cardiopulmonary exercise tests while breathing normoxic gas or 40 ppm iNO. Compared with placebo, iNO significantly increased peak oxygen uptake (1.80 ± 0.14 vs. 1.53 ± 0.10 L·min , P < 0.001) in COPD, whereas no effect was observed in controls. At an equivalent work rate of 60 W, iNO reduced / by 3.8 ± 4.2 units (P = 0.002) and dyspnoea by 1.1 ± 1.2 Borg units (P < 0.001) in COPD, whereas no effect was observed in controls. Operating lung volumes and oxygen saturation were unaffected by iNO in both groups. iNO increased peak oxygen uptake in COPD, secondary to reduced / and dyspnoea. These data suggest that mild COPD patients demonstrate pulmonary microvascular dysfunction that contributes to increased / , dyspnoea and exercise intolerance. This is the first study to demonstrate that experimental manipulation of the pulmonary circulation alone, can positively impact dyspnoea and exercise capacity in mild COPD.
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http://dx.doi.org/10.1113/JP280913DOI Listing
March 2021

Does spaced education improve clinical knowledge among Family Medicine residents? A cluster randomized controlled trial.

Adv Health Sci Educ Theory Pract 2021 Jan 3. Epub 2021 Jan 3.

Université Laval, Quebec City, Canada.

Spaced education is a learning strategy to improve knowledge acquisition and retention. To date, no robust evidence exists to support the utility of spaced education in the Family Medicine residency. We aimed to test whether alerts to encourage spaced education can improve clinical knowledge as measured by scores on the Canadian Family Medicine certification examination.

Method: We conducted a cluster randomized controlled trial to empirically and pragmatically test spaced education using two versions of the Family Medicine Study Guide mobile app. 12 residency training programs in Canada agreed to participate. At six intervention sites, we consented 335 of the 654 (51%) eligible residents. Residents in the intervention group were sent alerts through the app to encourage the answering of questions linked to clinical cases. At six control sites, 299 of 586 (51%) residents consented. Residents in the control group received the same app but with no alerts. Incidence rates of case completion between trial arms were compared using repeated measures analysis. We linked residents in both trial arms to their knowledge scores on the certification examination of the College of Family Physicians of Canada.

Results: Over 67 weeks, there was no statistically significant difference in the completion of clinical cases by participants. The difference in mean exam scores and the associated confidence interval did not exceed the pre-defined limit of 4 percentage points.

Conclusion: Further research is recommended before deploying spaced educational interventions in the Family Medicine residency to improve knowledge.
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http://dx.doi.org/10.1007/s10459-020-10020-zDOI Listing
January 2021

Molecular and phenotypic diversity of CBL-mutated juvenile myelomonocytic leukemia.

Haematologica 2020 12 30;Online ahead of print. Epub 2020 Dec 30.

Department of Pediatrics, Benioff Children's Hospital, University of California, San Francisco, San Francisco, CA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco.

Mutations in the gene CBL were first identified in adults with various myeloid malignancies. Some patients with juvenile myelomonocytic leukemia (JMML) were also noted to harbor mutations in CBL, but were found to have generally less aggressive disease courses compared to other forms of Ras pathway-mutant JMML. Importantly, and in contrast to most reports in adults, the majority of CBL mutations in JMML patients are germline with acquired uniparental disomy occurring in affected marrow cells. Here, we systematically studied a large cohort of 33 JMML patients with CBL mutations and found this disease to be highly diverse in presentation and overall outcome. Moreover, we discovered somatically-acquired CBL mutations in 15% of pediatric patients who presented with more aggressive disease. Neither clinical features nor methylation profiling were able to distinguish somatic CBL patients from germline CBL patients, highlighting the need for germline testing. Overall, we demonstrate that disease courses are quite heterogeneous even among germline CBL patients. Prospective clinical trials are warranted to find ideal treatment strategies for this diverse cohort of patients.
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http://dx.doi.org/10.3324/haematol.2020.270595DOI Listing
December 2020

Cost-effectiveness of antithrombotic agents for atrial fibrillation in older adults at risk for falls: a mathematical modelling study.

CMAJ Open 2020 Oct-Dec;8(4):E706-E714. Epub 2020 Nov 6.

Knowledge Translation Program (Wong, Straus), Li Ka Shing Knowledge Institute, St. Michael's Hospital; Institute for Health Policy Management and Evaluation (Wong, Belza, Naimark, Straus, Wijeysundera), Dalla Lana School of Public Health, Division of Nephrology (Naimark), Sunnybrook Health Sciences Centre and Division of Cardiology and Cardiac Surgery (Wijeysundera), Schulich Heart Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ont.

Background: Antithrombotic drugs decrease stroke risk in patients with atrial fibrillation, but they increase bleeding risk, particularly in older adults at high risk for falls. We aimed to determine the most cost-effective antithrombotic therapy in older adults with atrial fibrillation who are at high risk for falls.

Methods: We conducted a mathematical modelling study from July 2019 to March 2020 based on the Ontario, Canada, health care system. We derived the base-case age, sex and fall risk distribution from a published cohort of older adults at risk for falls, and the bleeding and stroke risk parameters from an atrial fibrillation trial population. Using a probabilistic microsimulation Markov decision model, we calculated quality-adjusted life years (QALYs), total cost and incremental cost-effectiveness ratios (ICERs) for each of acetylsalicylic acid (ASA), warfarin, apixaban, dabigatran, rivaroxaban and edoxaban. Cost data were adjusted for inflation to 2018 values. The analysis used the Ontario public payer perspective with a lifetime horizon.

Results: In our model, the most cost-effective antithrombotic therapy for atrial fibrillation in older patients at risk for falls was apixaban, with an ICER of $8517 per QALY gained (5.86 QALYs at $92 056) over ASA. It was a dominant strategy over warfarin and the other antithrombotic agents. There was moderate uncertainty in cost-effectiveness ranking, with apixaban as the preferred choice in 66% of model iterations (given willingness to pay of $50 000 per QALY gained); edoxaban, 30 mg, was preferred in 31% of iterations. Sensitivity analysis across ranges of age, bleeding risk and fall risk still favoured apixaban over the other medications.

Interpretation: From a public payer perspective, apixaban is the most cost-effective antithrombotic agent in older adults at high risk for falls. Health care funders should implement strategies to encourage use of the most cost-effective medication in this population.
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http://dx.doi.org/10.9778/cmajo.20200107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7661050PMC
November 2020

Leukopenia is a biomarker for effective temozolomide dosing and predicts overall survival of patients with glioblastoma.

Mol Clin Oncol 2020 Dec 1;13(6):80. Epub 2020 Oct 1.

Department of Neurology, Beth Israel Deaconess Hospital and Harvard Medical School, Boston, MA 02215, USA.

The median survival time of patients with glioblastoma is 14-16 months with a 5-year overall survival rate of 9.8%. Standard of care treatment includes radiation with concomitant temozolomide followed by cyclic temozolomide. If the patient develops myelosuppression (thrombocytopenia, leukopenia or anemia), the dose of temozolomide is reduced or stopped to avoid bleeding or infections. Recent studies have demonstrated that mild leukopenia is associated with increased overall survival in patients with glioblastoma. To confirm prior results showing that leukopenia is associated with increased overall survival as a primary outcome in patients with glioblastoma, the present study retrospectively collected complete blood counts from 141 patients with glioblastoma treated at the Beth Israel Deaconess Medical Center (Boston, USA) between January 2012 and December 2017. According to Kaplan-Meier analysis with a log-rank test, the presence of leukopenia was associated with increased overall survival (P=0.008). Furthermore, patients with grade 2 leukopenia (Common Terminology Criteria for Adverse Events version 5.0) survived longer than those without myelosuppression (P=0.024). There was no difference in overall survival between patients with grade 1, 3 or 4 leukopenia and those without myelosuppression. Leukopenia was associated with longer survival independent of age or extent of surgery in Cox proportional hazards regression modeling (P=0.00205). A possible interpretation is that grade 2 leukopenia is a biomarker of adequate temozolomide dosing in a population with diverse DNA repair function, which may be the consequence of variable O-methylguanine-DNA methyltransferase activity. A prospective dose escalation trial is necessary to determine if treatment-induced leukopenia is beneficial for all patients receiving temozolomide.
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http://dx.doi.org/10.3892/mco.2020.2150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7549395PMC
December 2020

Exploring Predictors of Response to Dacomitinib in -Amplified Recurrent Glioblastoma.

JCO Precis Oncol 2020 8;4. Epub 2020 Jun 8.

Massachusetts General Hospital and Harvard Medical School, Boston, MA.

Purpose: Despite the high frequency of genetic alterations in glioblastoma (GBM), EGFR-targeted therapies have not had success in this disease. To improve the likelihood of efficacy, we targeted adult patients with recurrent GBM enriched for gene amplification, which occurs in approximately half of GBM, with dacomitinib, a second-generation, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that penetrates the blood-brain barrier, in a multicenter phase II trial.

Patients And Methods: We retrospectively explored whether previously described extracellular domain (ECD)-sensitizing mutations in the context of gene amplification could predict response to dacomitinib, and in a predefined subset of patients, we measured post-treatment intratumoral dacomitinib levels to verify tumor penetration.

Results: We found that dacomitinib effectively penetrates contrast-enhancing GBM tumors. Among all 56 treated patients, 8 (14.3%) had a clinical benefit as defined by a duration of treatment of at least 6 months, of whom 5 (8.9%) remained progression free for at least 1 year. Presence of or ECD missense mutation was not associated with clinical benefit. We evaluated the pretreatment transcriptome in circulating extracellular vesicles (EVs) by RNA sequencing in a subset of patients and identified a signature that distinguished patients who had durable benefit versus those with rapid progression.

Conclusion: While dacomitinib was not effective in most patients with -amplified GBM, a subset experienced a durable, clinically meaningful benefit. Moreover, and ECD mutation status in archival tumors did not predict clinical benefit. RNA signatures in circulating EVs may warrant investigation as biomarkers of dacomitinib efficacy in GBM.
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http://dx.doi.org/10.1200/PO.19.00295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7446412PMC
June 2020

A Natural Flavone Tricin from Grains Can Alleviate Tumor Growth and Lung Metastasis in Colorectal Tumor Mice.

Molecules 2020 Aug 15;25(16). Epub 2020 Aug 15.

Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.

Tricin, a flavone isolated from rice bran, has been shown to be chemopreventive in a colorectal cancer (CRC) mouse model. This study aimed to illustrate the inhibitory activities of tricin in colon cancer cells and in a metastatic CRC mouse model. BALB/c mice injected with mouse Colon26-Luc cells into the rectum wall were treated with tricin (37.5 mg/kg) daily for 18 days. Orthotopic colon tumor growth and metastasis to lungs were assessed by in vivo bioluminescence imaging. Results showed that tricin suppressed Colon-Luc cells motility and downregulated phosphorylated Akt, Erk1/2 and NF-κB expressions of human colon cancer HT-29 cells. While tricin treatment suppressed tumor growth and lung metastasis as well as altered the populations of myeloid-derived suppressor cells and regulatory T cells in spleens. In summary, the tumor microenvironment modulatory and anti-metastatic effects of tricin in colon cancer mouse model were shown for the first time, suggesting the potential development of tricin-containing food supplements for CRC patients.
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http://dx.doi.org/10.3390/molecules25163730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463810PMC
August 2020

Protein-Protein Interactions Mediated by Intrinsically Disordered Protein Regions Are Enriched in Missense Mutations.

Biomolecules 2020 07 24;10(8). Epub 2020 Jul 24.

Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.

Because proteins are fundamental to most biological processes, many genetic diseases can be traced back to single nucleotide variants (SNVs) that cause changes in protein sequences. However, not all SNVs that result in amino acid substitutions cause disease as each residue is under different structural and functional constraints. Influential studies have shown that protein-protein interaction interfaces are enriched in disease-associated SNVs and depleted in SNVs that are common in the general population. These studies focus primarily on folded (globular) protein domains and overlook the prevalent class of protein interactions mediated by intrinsically disordered regions (IDRs). Therefore, we investigated the enrichment patterns of missense mutation-causing SNVs that are associated with disease and cancer, as well as those present in the healthy population, in structures of IDR-mediated interactions with comparisons to classical globular interactions. When comparing the different categories of interaction interfaces, division of the interface regions into solvent-exposed rim residues and buried core residues reveal distinctive enrichment patterns for the various types of missense mutations. Most notably, we demonstrate a strong enrichment at the interface core of interacting IDRs in disease mutations and its depletion in neutral ones, which supports the view that the disruption of IDR interactions is a mechanism underlying many diseases. Intriguingly, we also found an asymmetry across the IDR interaction interface in the enrichment of certain missense mutation types, which may hint at an increased variant tolerance and urges further investigations of IDR interactions.
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http://dx.doi.org/10.3390/biom10081097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7463635PMC
July 2020

Pooled resistance analyses of darunavir once-daily regimens and formulations across 10 clinical studies of treatment-naïve and treatment-experienced patients with human immunodeficiency virus-1 infection.

HIV Res Clin Pract 2020 Apr - Jun;21(2-3):83-89. Epub 2020 Jul 26.

Janssen Scientific Affairs, LLC, Titusville, NJ, USA.

Background: The efficacy and high barrier to resistance of darunavir have been demonstrated across diverse populations with HIV-1 infection.

Objective: To evaluate post-baseline resistance among patients in studies of once-daily (QD) darunavir-based regimens and formulations.

Methods: The analysis included treatment-naïve and virologically failing or suppressed patients from 10 phase 2/3 studies (48-192 weeks in duration) of boosted darunavir 800 mg QD-based regimens. Three were phase 3 studies of the QD darunavir/cobicistat/emtricitabine/tenofovir alafenamide (D/C/F/TAF) 800/150/200/10 mg single-tablet regimen. Post-baseline resistance was evaluated upon protocol-defined virologic failure (PDVF). Resistance-associated mutations (RAMs) were identified using International Antiviral Society-USA mutation lists. Phenotypic analyses varied across studies.

Results: Overall, 250 of 3635 patients in the analysis met PDVF criteria; 205 had post-baseline genotypes/phenotypes. In total, four (0.1%) patients developed (or had identified) ≥1 darunavir and/or primary protease inhibitor (PI) RAM; only one (<0.1%) patient (with prior lopinavir virologic failure) lost darunavir phenotypic susceptibility. Among 3317 patients using nucleos(t)ide reverse transcriptase inhibitors (N[t]RTIs; mostly emtricitabine and tenofovir), 13 (0.4%) had ≥1 N(t)RTI RAM (10 with M184I/V). Among patients receiving D/C/F/TAF ( = 1949), none had post-baseline darunavir, primary PI, or tenofovir RAMs; only two (0.1%) patients developed an emtricitabine RAM, M184V/I.

Conclusions: Across a large, diverse population using darunavir 800 mg QD-based regimens and formulations, resistance development remains rare. After clinical trials that span >10 years, loss of phenotypic susceptibility to darunavir was only observed once in a PI-experienced patient and has never been observed in treatment-naïve patients, treatment-experienced PI-naïve patients, or treatment-experienced virologically suppressed patients.
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http://dx.doi.org/10.1080/25787489.2020.1794439DOI Listing
July 2020

Reduced intensity conditioning for acute myeloid leukemia using melphalan- vs busulfan-based regimens: a CIBMTR report.

Blood Adv 2020 07;4(13):3180-3190

Center for International Blood and Marrow Transplant Research, Department of Medicine, and.

There is a lack of large comparative study on the outcomes of reduced intensity conditioning (RIC) in acute myeloid leukemia (AML) transplantation using fludarabine/busulfan (FB) and fludarabine/melphalan (FM) regimens. Adult AML patients from Center for International Blood and Marrow Transplant Research who received first RIC allo-transplant between 2001 and 2015 were studied. Patients were excluded if they received cord blood or identical twin transplant, total body irradiation in conditioning, or graft-versus-host disease (GVHD) prophylaxis with in vitro T-cell depletion. Primary outcome was overall survival (OS), secondary end points were leukemia-free survival (LFS), nonrelapse mortality (NRM), relapse, and GVHD. Multivariate survival model was used with adjustment for patient, leukemia, and transplant-related factors. A total of 622 patients received FM and 791 received FB RIC. Compared with FB, the FM group had fewer transplant in complete remission (CR), fewer matched sibling donors, and less usage of anti-thymocyte globulin or alemtuzumab. More patients in the FM group received marrow grafts and had transplantation before 2005. OS was significantly lower within the first 3 months posttransplant in the FM group (hazard ratio [HR] = 1.82, P < .001), but was marginally superior beyond 3 months (HR = 0.87, P = .05). LFS was better with FM compared with FB (HR = 0.89, P = .05). NRM was significantly increased in the FM group during the first 3 months of posttransplant (HR = 3.85, P < .001). Long-term relapse was lower with FM (HR = 0.65, P < .001). Analysis restricted to patients with CR showed comparable results. In conclusion, compared with FB, the FM RIC showed a marginally superior long-term OS and LFS and a lower relapse rate. A lower OS early posttransplant within 3 months was largely the result of a higher early NRM.
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http://dx.doi.org/10.1182/bloodadvances.2019001266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7362362PMC
July 2020

Defective early innate immune response to ectromelia virus in the draining lymph nodes of aged mice due to impaired dendritic cell accumulation.

Aging Cell 2020 07 12;19(7):e13170. Epub 2020 Jul 12.

Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, PA, USA.

It is known that aging decreases natural resistance to viral diseases due to dysfunctional innate and adaptive immune responses, but the nature of these dysfunctions, particularly in regard to innate immunity, is not well understood. We have previously shown that C57BL/6J (B6) mice lose their natural resistance to footpad infection with ectromelia virus (ECTV) due to impaired maturation and recruitment of natural killer (NK) cells to the draining popliteal lymph node (dLN). More recently, we have also shown that in young B6 mice infected with ECTV, the recruitment of NK cells is dependent on a complex cascade whereby migratory dendritic cells (mDCs) traffic from the skin to the dLN, where they produce CCL2 and CCL7 to recruit inflammatory monocytes (iMOs). In the dLN, mDCs also upregulate NKG2D ligands to induce interferon gamma (IFN-γ) expression by group 1 innate lymphoid cells (G1-ILCs), mostly NK in cells but also some ILC1. In response to the IFN-γ, the incoming uninfected iMOs secret CXCL9 to recruit the critical NK cells. Here, we show that in aged B6 mice, the trafficking of mDCs to the dLN in response to ECTV is decreased, resulting in impaired IFN-γ expression by G1-ILCs, reduced accumulation of iMOs, and attenuated CXCL9 production by iMOs, which likely contributes to decrease in NK cell recruitment. Together, these data indicate that defects in the mDC response to viral infection during aging result in a reduced innate immune response in the dLN and contribute to increased susceptibility to viral disease in the aged.
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http://dx.doi.org/10.1111/acel.13170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7433008PMC
July 2020

Pemetrexed in Recurrent or Progressive Central Nervous System Lymphoma: A Phase I Multicenter Clinical Trial.

Oncologist 2020 09 1;25(9):747-e1273. Epub 2020 Jul 1.

Massachusetts General Hospital, Boston, Massachusetts, USA.

Lessons Learned: The findings from this study using monotherapy with pemetrexed in a pretreated patient population are, overall, encouraging. Unlike high-dose methotrexate, which requires several days of inpatient hospitalization, pemetrexed is relatively easy to administer in the outpatient setting and remains a viable treatment option in this patient population. The maximum tolerated dose of pemetrexed administered (900 mg/m every 2 weeks) was generally well tolerated and showed activity in patients with relapsed or refractory CNSL.

Background: There is currently no standard salvage treatment for patients with relapsed/refractory central nervous system (CNS) lymphoma (CNSL). We report the results of a phase I study of pemetrexed, an antifolate drug with broader activity than methotrexate (MTX). We provide the safety, tolerability, and maximum tolerated dose (MTD) of pemetrexed in patients with recurrent CNSL.

Methods: Through October 2015, 17 patients with relapsed/refractory CNSL received pemetrexed every 2 weeks with the first cohort receiving 600 mg/m and dose escalation in increments of 300 mg/m to a maximum of 1,200 mg/m . Three patients were to enroll at each dose level with expansion to six patients in the event of dose-limiting toxicity. Patients with both primary CNS lymphoma (PCNSL) and secondary CNS lymphoma (SCNSL) could be enrolled.

Results: Seventeen patients were evaluable with a median age of 63.7 years. Main adverse events included fatigue (82.4%), anemia (82.4%), and neutropenia (70.6%). The MTD was established at 900 mg/m . Dose-limiting toxicities were recorded in one patient in the 600 mg/m cohort and in two patients in the 1,200 mg/m cohort. Fourteen patients were evaluable for response assessment; 21.4% achieved a complete response, 35.7% had a partial response, 14.3% had stable disease, and 28.6% had progressive disease. The median progression-free survival was 4.2 months. The median overall survival was 44.5 months. In the original study protocol, the plan was to add an expansion cohort of six patients at MTD level. However, the first phase of the study was characterized by slow recruitment. Therefore, after achieving the primary objective of the study and establishing the MTD, the investigators decided to amend the protocol and to close the study.

Conclusion: Pemetrexed administered at 900 mg/m every 2 weeks exhibits single-agent activity in patients with recurrent CNSL; it is well tolerated, and side effects are manageable.
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http://dx.doi.org/10.1634/theoncologist.2020-0489DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7485351PMC
September 2020

Voltage-dependent structural models of the human Hv1 proton channel from long-timescale molecular dynamics simulations.

Proc Natl Acad Sci U S A 2020 06 27;117(24):13490-13498. Epub 2020 May 27.

Department of Chemistry, University of California, Irvine, CA 92697;

The voltage-gated Hv1 proton channel is a ubiquitous membrane protein that has roles in a variety of cellular processes, including proton extrusion, pH regulation, production of reactive oxygen species, proliferation of cancer cells, and increased brain damage during ischemic stroke. A crystal structure of an Hv1 construct in a putative closed state has been reported, and structural models for the channel open state have been proposed, but a complete characterization of the Hv1 conformational dynamics under an applied membrane potential has been elusive. We report structural models of the Hv1 voltage-sensing domain (VSD), both in a hyperpolarized state and a depolarized state resulting from voltage-dependent conformational changes during a 10-μs-timescale atomistic molecular dynamics simulation in an explicit membrane environment. In response to a depolarizing membrane potential, the S4 helix undergoes an outward displacement, leading to changes in the VSD internal salt-bridge network, resulting in a reshaping of the permeation pathway and a significant increase in hydrogen bond connectivity throughout the channel. The total gating charge displacement associated with this transition is consistent with experimental estimates. Molecular docking calculations confirm the proposed mechanism for the inhibitory action of 2-guanidinobenzimidazole (2GBI) derived from electrophysiological measurements and mutagenesis. The depolarized structural model is also consistent with the formation of a metal bridge between residues located in the core of the VSD. Taken together, our results suggest that these structural models are representative of the closed and open states of the Hv1 channel.
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http://dx.doi.org/10.1073/pnas.1920943117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306757PMC
June 2020

STING Sensing of Murine Cytomegalovirus Alters the Tumor Microenvironment to Promote Antitumor Immunity.

J Immunol 2020 06 13;204(11):2961-2972. Epub 2020 Apr 13.

Department of Microbiology and Immunology, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107

CMV has been proposed to play a role in cancer progression and invasiveness. However, CMV has been increasingly studied as a cancer vaccine vector, and multiple groups, including ours, have reported that the virus can drive antitumor immunity in certain models. Our previous work revealed that intratumoral injections of wild-type murine CMV (MCMV) into B16-F0 melanomas caused tumor growth delay in part by using a viral chemokine to recruit macrophages that were subsequently infected. We now show that MCMV acts as a STING agonist in the tumor. MCMV infection of tumors in STING-deficient mice resulted in normal recruitment of macrophages to the tumor, but poor recruitment of CD8 T cells, reduced production of inflammatory cytokines and chemokines, and no delay in tumor growth. In vitro, expression of type I IFN was dependent on both STING and the type I IFNR. Moreover, type I IFN alone was sufficient to induce cytokine and chemokine production by macrophages and B16 tumor cells, suggesting that the major role for STING activation was to produce type I IFN. Critically, viral infection of wild-type macrophages alone was sufficient to restore tumor growth delay in STING-deficient animals. Overall, these data show that MCMV infection and sensing in tumor-associated macrophages through STING signaling is sufficient to promote antitumor immune responses in the B16-F0 melanoma model.
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http://dx.doi.org/10.4049/jimmunol.1901136DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7323848PMC
June 2020

The Effect of Carotid Chemoreceptor Inhibition on Exercise Tolerance in Chronic Heart Failure.

Front Physiol 2020 12;11:195. Epub 2020 Mar 12.

Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.

Purpose: Chronic heart failure (CHF) is characterized by heightened sympathetic nervous activity, carotid chemoreceptor (CC) sensitivity, marked exercise intolerance and an exaggerated ventilatory response to exercise. The purpose of this study was to determine the effect of CC inhibition on exercise cardiovascular and ventilatory function, and exercise tolerance in health and CHF.

Methods: Twelve clinically stable, optimally treated patients with CHF (mean ejection fraction: 43 ± 2.5%) and 12 age- and sex-matched healthy controls were recruited. Participants completed two time-to-symptom-limitation (TLIM) constant load cycling exercise tests at 75% peak power output with either intravenous saline or low-dose dopamine (2 μg⋅kg⋅min; order randomized). Ventilation was measured using expired gas data and operating lung volume data were determined during exercise by inspiratory capacity maneuvers. Cardiac output was estimated using impedance cardiography, and vascular conductance was calculated as cardiac output/mean arterial pressure.

Results: There was no change in TLIM in either group with dopamine (CHF: saline 13.1 ± 2.4 vs. dopamine 13.5 ± 1.6 min, = 0.78; Control: saline 10.3 ± 1.2 vs. dopamine 11.5 ± 1.3 min, = 0.16). In CHF patients, dopamine increased cardiac output ( = 0.03), vascular conductance ( = 0.01) and oxygen delivery ( = 0.04) at TLIM, while ventilatory parameters were unaffected ( = 0.76). In controls, dopamine improved vascular conductance at TLIM ( = 0.03), but no other effects were observed.

Conclusion: Our findings suggest that the CC contributes to cardiovascular regulation during full-body exercise in patients with CHF, however, CC inhibition does not improve exercise tolerance.
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http://dx.doi.org/10.3389/fphys.2020.00195DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7080702PMC
March 2020

Tissue-, age- and dose-dependent changes in avian β-defensin and LEAP2 mRNA abundance in the intestines of Typhimurium challenged broilers.

Anim Biotechnol 2020 Mar 18:1-9. Epub 2020 Mar 18.

Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA, USA.

is a pathogen normally found in the gastrointestinal tract of poultry. The objective of this study was to determine changes in avian β-defensin (AvBD) and liver-enriched antimicrobial peptide 2 (LEAP2) mRNA following challenge. Day of hatch chicks were challenged with 10, 10 or 10 colony-forming units (cfu) of . There were dose-, tissue- and age-specific changes in AvBD and LEAP2 mRNA. At 1-day post-infection (dpi) there was a transient upregulation of AvBD1, 8, 10 and 12 mRNA in the 10 cfu group. At 5 dpi, all seven AvBD mRNA were downregulated in the ileum, while only AvBD1, 6, 10 and 11 mRNA were downregulated in the jejunum and AvBD6, 8, 10, 12 and 13 were downregulated in the cecum. At 7 dpi, there was downregulation of all seven AvBD mRNA in the duodenum and downregulation of selected AvBD in the jejunum, ileum and cecum. LEAP2 mRNA was downregulated at all doses of in the cecum at 1 dpi and in the ileum at 5 dpi. In summary, infection caused an initial upregulation followed by a downregulation of AvBD mRNA.
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http://dx.doi.org/10.1080/10495398.2020.1738449DOI Listing
March 2020

Tumor treating fields in neuro-oncology: integration of alternating electric fields therapy into promising treatment strategies.

Chin Clin Oncol 2020 Feb 29. Epub 2020 Feb 29.

Brain Tumor Center & Neuro-Oncology Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.

As the most recent innovation in cancer therapy that utilizes properties of the electromagnetic spectrum, tumor treating fields (TTFields) are non-invasive alternating electrical fields that target rapidly dividing tumor cells. In the patient, TTFields are delivered as regional treatment via two pairs of orthogonally positioned transducer arrays applied to the head or elsewhere on the body surface. Side effects are primarily localized to the skin. Since the initial proof-of-concept study published in 2007, the use of TTFields has become integrated into the standard-of-care multi-modality treatment of glioblastoma (GBM). In this review, we summarize the theory behind TTFields and describe how key mechanistic data helped guide pivotal clinical trials. We also highlight potential future applications.
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http://dx.doi.org/10.21037/cco.2020.02.04DOI Listing
February 2020

Therapeutic targeting of preleukemia cells in a mouse model of mutant acute myeloid leukemia.

Science 2020 01;367(6477):586-590

Department of Pediatric Oncology, Dana-Farber Cancer Institute, and Division of Hematology/Oncology, Boston, MA, USA.

The initiating mutations that contribute to cancer development are sometimes present in premalignant cells. Whether therapies targeting these mutations can eradicate premalignant cells is unclear. Acute myeloid leukemia (AML) is an attractive system for investigating the effect of preventative treatment because this disease is often preceded by a premalignant state (clonal hematopoiesis or myelodysplastic syndrome). In mutant knock-in mice, a model of AML development, leukemia is preceded by a period of extended myeloid progenitor cell proliferation and self-renewal. We found that this self-renewal can be reversed by oral administration of a small molecule (VTP-50469) that targets the MLL1-Menin chromatin complex. These preclinical results support the hypothesis that individuals at high risk of developing AML might benefit from targeted epigenetic therapy in a preventative setting.
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http://dx.doi.org/10.1126/science.aax5863DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7754791PMC
January 2020

Finite element analysis of Tumor Treating Fields in a patient with posterior fossa glioblastoma.

J Neurooncol 2020 Mar 27;147(1):125-133. Epub 2020 Jan 27.

Brain Tumor Center & Neuro-Oncology Unit, Harvard Medical School, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA, 02215, USA.

Introduction: Tumor Treating Fields (TTFields) are alternating electric fields at 200 kHz that disrupt tumor cells as they undergo mitosis. Patient survival benefit has been demonstrated in randomized clinical trials but much of the data are available only for supratentorial glioblastomas. We investigated a series of alternative array configurations for the posterior fossa to determine the electric field coverage of a cerebellar glioblastoma.

Methods: Semi-automated segmentation of neuro-anatomical structures was performed while the gross tumor volume (GTV) was manually delineated. A three-dimensional finite-element mesh was generated and then solved for field distribution.

Results: Compared to the supratentorial array configuration, the alternative array configurations consist of posterior displacement the 2 lateral opposing arrays and inferior displacement of the posteroanterior array, resulting in an average increase of 46.6% electric field coverage of the GTV as measured by the area under the curve of the electric field-volume histogram (E). Hotspots, or regions of interest with the highest 5% of TTFields intensity (E), had an average increase of 95.6%. Of the 6 posterior fossa configurations modeled, the PA arrangement provided the greatest field coverage at the GTV when the posteroanterior array was placed centrally along the patient's posterior neck and horizontally parallel, along the longer axis, to the coronal plane of the patient's head. Varying the arrays also produced hotspots proportional to TTFields coverage.

Conclusions: Our finite element modeling showed that the alternative array configurations offer an improved TTFields coverage to the cerebellar tumor compared to the conventional supratentorial configuration.
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http://dx.doi.org/10.1007/s11060-020-03406-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7076058PMC
March 2020

Severity of mucositis during allogeneic transplantation impacts post-transplant cyclosporin absorption.

Bone Marrow Transplant 2020 09 21;55(9):1857-1859. Epub 2020 Jan 21.

Bone Marrow Transplant Service, Clinical Haematology, Peter MacCallum Cancer Centre and Royal Melbourne Hospital, Melbourne, VIC, Australia.

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http://dx.doi.org/10.1038/s41409-020-0795-7DOI Listing
September 2020

Resistance to ectromelia virus infection requires cGAS in bone marrow-derived cells which can be bypassed with cGAMP therapy.

PLoS Pathog 2019 12 26;15(12):e1008239. Epub 2019 Dec 26.

Thomas Jefferson University, Department of Microbiology and Immunology, Philadelphia, Pennsylvania, United States of America.

Cells sensing infection produce Type I interferons (IFN-I) to stimulate Interferon Stimulated Genes (ISGs) that confer resistance to viruses. During lympho-hematogenous spread of the mouse pathogen ectromelia virus (ECTV), the adaptor STING and the transcription factor IRF7 are required for IFN-I and ISG induction and resistance to ECTV. However, it is unknown which cells sense ECTV and which pathogen recognition receptor (PRR) upstream of STING is required for IFN-I and ISG induction. We found that cyclic-GMP-AMP (cGAMP) synthase (cGAS), a DNA-sensing PRR, is required in bone marrow-derived (BMD) but not in other cells for IFN-I and ISG induction and for resistance to lethal mousepox. Also, local administration of cGAMP, the product of cGAS that activates STING, rescues cGAS but not IRF7 or IFN-I receptor deficient mice from mousepox. Thus, sensing of infection by BMD cells via cGAS and IRF7 is critical for resistance to a lethal viral disease in a natural host.
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http://dx.doi.org/10.1371/journal.ppat.1008239DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974301PMC
December 2019

Loss of Resistance to Mousepox during Chronic Lymphocytic Choriomeningitis Virus Infection Is Associated with Impaired T-Cell Responses and Can Be Rescued by Immunization.

J Virol 2020 02 14;94(5). Epub 2020 Feb 14.

Department of Microbiology and Immunology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA

It is well established that chronic viral infections can cause immune suppression, resulting in increased susceptibility to other infectious diseases. However, the effects of chronic viral infection on T-cell responses and vaccination against highly pathogenic viruses are not well understood. We have recently shown that C57BL/6 (B6) mice lose their natural resistance to wild-type (WT) ectromelia virus (ECTV) when chronically infected with lymphocytic choriomeningitis virus (LCMV) clone 13 (CL13). Here we compared the T-cell response to ECTV in previously immunologically naive mice that were chronically infected with CL13 or that were convalescent from acute infection with the Armstrong (Arm) strain of LCMV. Our results show that mice that were chronically infected with CL13 but not those that had recovered from Arm infection have highly defective ECTV-specific CD8 and CD4 T-cell responses to WT ECTV. These defects are at least partly due to the chronic infection environment. In contrast to mice infected with WT ECTV, mice chronically infected with CL13 survived without signs of disease when infected with ECTV-Δ036, a mutant ECTV strain that is highly attenuated. Strikingly, mice chronically infected with CL13 mounted a strong CD8 T-cell response to ECTV-Δ036 and survived without signs of disease after a subsequent challenge with WT ECTV. Our work suggests that enhanced susceptibility to acute viral infections in chronically infected individuals can be partly due to poor T-cell responses but that sufficient T-cell function can be recovered and resistance to acute infection can be restored by immunization with highly attenuated vaccines. Chronic viral infections may result in immunosuppression and enhanced susceptibility to infections with other pathogens. For example, we have recently shown that mice chronically infected with lymphocytic choriomeningitis virus (LCMV) clone 13 (CL13) are highly susceptible to mousepox, a disease that is caused by ectromelia virus and that is the mouse homolog of human smallpox. Here we show chronic CL13 infection severely disrupts the expansion, proliferation, activation, and cytotoxicity of T cells in response due at least in part to the suppressive effects of the chronic infection milieu. Notably, despite this profound immunodeficiency, mice chronically infected with CL13 could be protected by vaccination with a highly attenuated variant of ECTV. These results demonstrate that protective vaccination of immunosuppressed individuals is possible, provided that proper immunization tools are used.
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http://dx.doi.org/10.1128/JVI.01832-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7022357PMC
February 2020

Human αB-crystallin discriminates between aggregation-prone and function-preserving variants of a client protein.

Biochim Biophys Acta Gen Subj 2020 03 5;1864(3):129502. Epub 2019 Dec 5.

Department of Chemistry, UC Irvine, Irvine, CA 92697-2025, United States of America; Department of Molecular Biology and Biochemistry, UC Irvine, Irvine, CA 92697, United States of America. Electronic address:

Background: The eye lens crystallins are highly soluble proteins that are required to last the lifespan of an organism due to low protein turnover in the lens. Crystallin aggregation leads to formation of light-scattering aggregates known as cataract. The G18V mutation of human γS-crystallin (γS-G18V), which is associated with childhood-onset cataract, causes structural changes throughout the N-terminal domain and increases aggregation propensity. The holdase chaperone protein αB-crystallin does not interact with wild-type γS-crystallin, but does bind its G18V variant. The specific molecular determinants of αB-crystallin binding to client proteins is incompletely charcterized. Here, a new variant of γS, γS-G18A, was created to test the limits of αB-crystallin selectivity.

Methods: Molecular dynamics simulations were used to investigate the structure and dynamics of γS-G18A. The overall fold of γS-G18A was assessed by circular dichroism (CD) spectroscopy and intrinsic tryptophan fluorescence. Its thermal unfolding temperature and aggregation propensity were characterized by CD and DLS, respectively. Solution-state NMR was used to characterize interactions between αB-crystallin and γS-G18A.

Results: γS-G18A exhibits minimal structural changes, but has compromised thermal stability relative to γS-WT. The placement of alanine, rather than valine, at this highly conserved glycine position produces minor changes in hydrophobic surface exposure. However, human αB-crystallin does not bind the G18A variant, in contrast to previous observations for γS-G18V, which aggregates at physiological temperature.

Conclusions: αB-crystallin is capable of distinguishing between aggregation-prone and function-preserving variants, and recognizing the transient unfolding or minor conformers that lead to aggregation in the disease-related variant.

General Significance: Human αB-crystallin distinguishes between highly similar variants of a structural crystallin, binding the cataract-related γS-G18V variant, but not the function-preserving γS-G18A variant, which is monomeric at physiological temperature.
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http://dx.doi.org/10.1016/j.bbagen.2019.129502DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7434982PMC
March 2020

Langerhans Cells Orchestrate the Protective Antiviral Innate Immune Response in the Lymph Node.

Cell Rep 2019 12;29(10):3047-3059.e3

Department of Microbiology and Immunology, Thomas Jefferson University, BLSB 709 233 South 10(th) Street, Philadelphia, PA 19107, USA. Electronic address:

During disseminating viral infections, a swift innate immune response (IIR) in the draining lymph node (dLN) that restricts systemic viral spread is critical for optimal resistance to disease. However, it is unclear how this IIR is orchestrated. We show that after footpad infection of mice with ectromelia virus, dendritic cells (DCs) highly expressing major histocompatibility complex class II (MHC class II DCs), including CD207 epidermal Langerhans cells (LCs), CD103CD207 double-positive dermal DCs (DP-DCs), and CD103CD207 double-negative dermal DCs (DN-DCs) migrate to the dLN from the skin carrying virus. MHC class II DCs, predominantly LCs and DP-DCs, are the first cells upregulating IIR cytokines in the dLN. Preventing MHC class II DC migration or depletion of LCs, but not DP-DC deficiency, suppresses the IIR in the dLN and results in high viral lethality. Therefore, LCs are the architects of an early IIR in the dLN that is critical for optimal resistance to a disseminating viral infection.
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http://dx.doi.org/10.1016/j.celrep.2019.10.118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6927544PMC
December 2019