Lectin-Dependent Enhancement of Ebola Virus Infection via Soluble and Transmembrane C-type Lectin Receptors

Mannose-binding lectin (MBL) is a key soluble effector of the innate immune system that recognizes pathogen-specific surface glycans. Surprisingly, low-producing MBL genetic variants that may predispose children and immunocompromised individuals to infectious diseases are more common than would be expected in human populations. Since certain immune defense molecules, such as immunoglobulins, can be exploited by invasive pathogens, we hypothesized that MBL might also enhance infections in some circumstances. Consequently, the low and intermediate MBL levels commonly found in human populations might be the result of balancing selection. Using model infection systems with pseudotyped and authentic glycosylated viruses, we demonstrated that MBL indeed enhances infection of Ebola, Hendra, Nipah and West Nile viruses in low complement conditions. Mechanistic studies with Ebola virus (EBOV) glycoprotein pseudotyped lentiviruses confirmed that MBL binds to N-linked glycan epitopes on viral surfaces in a specific manner via the MBL carbohydrate recognition domain, which is necessary for enhanced infection. MBL mediates lipid-raft-dependent macropinocytosis of EBOV via a pathway that appears to require less actin or early endosomal processing compared with the filovirus canonical endocytic pathway. Using a validated RNA interference screen, we identified C1QBP (gC1qR) as a candidate surface receptor that mediates MBL-dependent enhancement of EBOV infection. We also identified dectin-2 (CLEC6A) as a potentially novel candidate attachment factor for EBOV. Our findings support the concept of an innate immune haplotype that represents critical interactions between MBL and complement component C4 genes and that may modify susceptibility or resistance to certain glycosylated pathogens. Therefore, higher levels of native or exogenous MBL could be deleterious in the setting of relative hypocomplementemia which can occur genetically or because of immunodepletion during active infections. Our findings confirm our hypothesis that the pressure of infectious diseases may have contributed in part to evolutionary selection of MBL mutant haplotypes

A Comparison of Survival Analysis, Threshold Regression and Linear Mixed Models in a Longitudinal Diabetes Clinic Study (2009 – 2013) at Kalafong Hospital with Nephropathy as Outcome

Background: This study compares three methodologies appropriate for the analysis of longitudinal time-to-event data. The Cox model is well researched and frequently used. Threshold regression, however, is relatively new and there are few articles describing its application in biomedical statistics. A linear mixed model provides an alternative interpretation of a continuous outcome rather than time to an event. A longitudinal study of the time to onset of diabetic nephropathy, a common complication of Diabetes Mellitus, is used to compare the three models with respect to their explanatory and predictive abilities and utilitarian value to researchers. Methods: The study entails a secondary data analysis of 1160 retrospective patient records, collected at a diabetic clinic at Kalafong Hospital, Pretoria. Model selection was based on current literature, backward elimination of insignificant variables (p>0.2) and the Akaike and Bayesian Information Criterion. Survival and hazard functions and ratios were determined for the survival data. Risk categories in the Cox model evaluated discrimination, while threshold regression predicted survival probabilities for specific patient profiles. The linear mixed model predicted albumin-creatinine ratio values, a marker for the diagnosis of diabetic nephropathy. Results: The Cox model, stratified by glucose control, gender, hypertension, type of diabetes and smoking status, had an AIC of 81 and was the most parsimonious model. Threshold regression, with an AIC of 1428, indicated duration of diabetes as a significant factor in the process of health deterioration. Individual variation in weight and total cholesterol amongst patients was accounted for by the linear mixed model, with an AIC of 3755. Conclusion: All three regression models provided valuable insight into underlying risk factors of diabetic nephropathy and should form part of a multi-faceted approach to analysing longitudinal survival data.Dissertation (MSc)--University of Pretoria, 2014.lk2014School of Health Systems and Public Health (SHSPH)MScUnrestricte

The effect of voice disorders on lexical tone variation : exploratory study in an African language

PURPOSE : The aim was to determine if the presence of a voice disorder in speakers of Setswana, an African tone language, will negatively impact the accuracy of identification by typical first language judges of words belonging to tonal minimal pairs. METHOD : A quasi-experimental between-group comparison and individual case studies were conducted. Five participants with different types and degrees of voice disorders and nine control participants produced 10 tonal minimal word pairs. Five judges had to identify which of a pair was produced. RESULT : The mean scores of the control and experimental speakers as groups differed, but the difference was not statistically significant. Control participants scored between 19.6/20 and 14.2/20 words correctly identified. Individual data revealed that four of the nine control participants attained at least one perfect score across judges and six had mean scores of 18.0/20 and higher. The highest scoring experimental participant, presenting with a mild voice disorder, attained a mean of 18.0/20. The lowest scoring participant, presenting with the most severe dysphonia, had a mean of 12.2/20 words correctly identified. CONCLUSION : These preliminary results appear to suggest that a severe voice disorder could compromise lexical tone variation and by implication the intelligibility of a message.http://www.tandfonline.com/toc/iasl202020-04-23hj2020Speech-Language Pathology and Audiolog

Reduction of daily maintenance inhaled corticosteroids in patients with severe eosinophilic asthma treated with benralizumab (SHAMAL): a randomised, multicentre, open-label, phase 4 study

Stepwise intensification of inhaled corticosteroids (ICS) is routine for severe eosinophilic asthma, despite some poor responses to high-dose ICS. Dose reductions are recommended in patients responding to biologics, but little supporting safety evidence exists. SHAMAL was a phase 4, randomised, open-label, active-controlled study done at 22 study sites in four countries. Eligible participants were adults (aged ≥18 years) with severe eosinophilic asthma and a five-item Asthma Control Questionnaire score below 1·5 and who received at least three consecutive doses of benralizumab before screening. We randomly assigned patients (3:1) to taper their high-dose ICS to a medium-dose, low-dose, and as-needed dose (reduction group) or continue (reference group) their ICS-formoterol therapy for 32 weeks, followed by a 16-week maintenance period. The primary endpoint was the proportion of patients reducing their ICS-formoterol dose by week 32. The primary outcome was assessed in the reduction group, and safety analyses included all randomly assigned patients receiving study treatment. This study is registered at ClinicalTrials.gov, NCT04159519. Between Nov 12, 2019, and Feb 16, 2023, we screened and enrolled in the run-in period 208 patients. We randomly assigned 168 (81%) to the reduction (n=125 [74%]) and reference arms (n=43 [26%]). Overall, 110 (92%) patients reduced their ICS-formoterol dose: 18 (15%) to medium-dose, 20 (17%) to low-dose, and 72 (61%) to as-needed only. In 113 (96%) patients, reductions were maintained to week 48; 114 (91%) of patients in the reduction group had zero exacerbations during tapering. Rates of adverse events were similar between groups. 91 (73%) patients had adverse events in the reduction group and 35 (83%) in the reference group. 17 patients had serious adverse events in the study: 12 (10%) in the reduction group and five (12%) in the reference group. No deaths occurred during the study. These findings show that patients controlled on benralizumab can have meaningful reductions in ICS therapy while maintaining asthma control. AstraZeneca

Impact of patient support programmes among patients with severe asthma treated with biological therapies: a systematic literature review and indirect treatment comparison

Introduction: Effective treatment of severe asthma requires patient adherence to inhaled and biological medications. Previous work has shown that patient support programmes (PSP) can improve adherence in patients with chronic diseases, but the impact of PSPs in patients with severe asthma treated with biologics has not been thoroughly investigated. Methods: We conducted a systematic literature review to understand the impact of PSPs on treatment adherence, asthma control and health-related quality of life (HRQoL) in patients with severe asthma. Embase, MEDLINE and EconLit databases were searched for studies published from 2003 (the year of the first biological approval for severe asthma) to June 2023 that described PSP participation among patients with severe asthma on biological treatment. Direct pooling of outcomes was not possible due to the heterogeneity across studies, so an indirect treatment comparison (ITC) was performed to determine the effect of PSP participation on treatment discontinuation. The ITC used patient-level data from patients treated with benralizumab either enrolled in a PSP (VOICE study, Connect 360 PSP) or not enrolled in a PSP (Benralizumab Patient Access Programme study) in the UK. Findings: 25 records of 21 studies were selected. Six studies investigated the impact of PSPs on treatment adherence, asthma control or HRQoL. All six studies reported positive outcomes for patients enrolled in PSPs; the benefits of each PSP were closely linked to the services provided. The ITC showed that patients in the Connect 360 PSP group were less likely to discontinue treatment compared with the non-PSP group (OR 0.26, 95% CI 0.11 to 0.57,

MBL mediates HIV-EBOV GP infection via the canonical macropinocytosis pathway for EBOV but with less dependence on actin.

<p>We preincubated HEK293F cells with (A) EIPA (5-(<i>N</i>-Ethyl-<i>N</i>-isopropyl)amiloride, a potent and specific inhibitor of Na⁺/H⁺ exchanger activity), (B) methyl-β-cyclodextrin (extracts or sequesters cholesterol from the plasma membrane), (C) latrunculin B (blocks actin polymerization), (D) cytochalasin D (inhibits actin microfilament function), (E) nocodazole (disrupts microtubules), or (F) jasplakinolide (disrupts microtubules) in 5% MBL-deficient serum in the absence or presence of rhMBL at 37°C for 1 hour. We then infected cells with HIV-EBOV-GP virion-like particles (1200 pg p24/100 µl). Percentages of infected cells are relative to DMSO controls. Luciferase values were adjusted for cell viability. Experiments were performed twice in quadruplicate. Significant differences are shown. (G) Absorbance values of an ELISA assay are shown indicating the difference in amount of rhMBL within the physiological range that binds to immobilized mannan or FITC-dextran (1 µg/100 µl). (H) We preincubated FITC-dextran with various concentrations of rhMBL at 37°C for 30 minutes and then added the products to PMA-stimulated (10 ng/ml), IL-4-supplemented (100 ng/ml) THP-1 cells at 37°C for 1 hour. We measured FITC-dextran uptake by flow cytometry and reported the results as mean fluorescence intensity (geometric mean fluorescence × percentage of cells). Experiments were performed twice in triplicate.</p

MBL enhances HIV-EBOV GP infection of THP-1 cells and human monocyte-derived macrophages.

<p>(A) We stimulated 5×10⁴ THP-1 cells with PMA (10 ng/ml) and supplemented the cells with IL-4 (100 ng/ml) for 72 hours. We preincubated HIV-EBOV GP or HIV-<i>env</i> negative virion-like particles (1200 pg p24/100 µl) with or without rhMBL before infecting differentiated adherent THP-1 cells cultivated in 5% MBL-deficient serum. (B) We cultivated 2.5×10⁵ PBMC derived from human single-donor buffy coat samples in RPMI-1640 with 10% FBS and stimulated the cells with M-CSF (50 ng/ml) to induce differentiation of monocyte-derived macrophages. We infected cells with HIV-EBOV GP (WT), HIV-EBOV-ΔGP NTDL6 (NTDL6, mutated GP lacks 217 amino acids in the heavily glycosylated mucin-rich region) or HIV-<i>env</i> negative (env neg) in the presence or absence of rhMBL. The box plot represents outliers (dots), 10^th and 90^th percentiles (whiskers), 25^th and 75^th percentiles (box) and median values (line). Significant differences in infection rates are shown. Luciferase values were adjusted for cell viability using alamarBlue (resazurin reduction assay) for all the above experiments, which were performed twice in quadruplicate.</p