Secretion of the fungal toxin candidalysin is dependent on conserved precursor peptide sequences

The opportunistic fungal pathogen Candida albicans damages host cells via its peptide toxin, candidalysin. Before secretion, candidalysin is embedded in a precursor protein, Ece1, which consists of a signal peptide, the precursor of candidalysin and seven non-candidalysin Ece1 peptides (NCEPs), and is found to be conserved in clinical isolates. Here we show that the Ece1 polyprotein does not resemble the usual precursor structure of peptide toxins. C. albicans cells are not susceptible to their own toxin, and single NCEPs adjacent to candidalysin are sufficient to prevent host cell toxicity. Using a series of Ece1 mutants, mass spectrometry and anti-candidalysin nanobodies, we show that NCEPs play a role in intracellular Ece1 folding and candidalysin secretion. Removal of single NCEPs or modifications of peptide sequences cause an unfolded protein response (UPR), which in turn inhibits hypha formation and pathogenicity in vitro. Our data indicate that the Ece1 precursor is not required to block premature pore-forming toxicity, but rather to prevent intracellular auto-aggregation of candidalysin sequences.

Towards optimal use of antithrombotic therapy of people with cancer at the end of life: A research protocol for the development and implementation of the SERENITY shared decision support tool

BACKGROUND

Even though antithrombotic therapy has probably little or even negative effects on the well-being of people with cancer during their last year of life, deprescribing antithrombotic therapy at the end of life is rare in practice. It is often continued until death, possibly resulting in excess bleeding, an increased disease burden and higher healthcare costs.

METHODS

The SERENITY consortium comprises researchers and clinicians from eight European countries with specialties in different clinical fields, epidemiology and psychology. SERENITY will use a comprehensive approach combining a realist review, flash mob research, epidemiological studies, and qualitative interviews. The results of these studies will be used in a Delphi process to reach a consensus on the optimal design of the shared decision support tool. Next, the shared decision support tool will be tested in a randomised controlled trial. A targeted implementation and dissemination plan will be developed to enable the use of the SERENITY tool across Europe, as well as its incorporation in clinical guidelines and policies. The entire project is funded by Horizon Europe.

RESULTS

SERENITY will develop an information-driven shared decision support tool that will facilitate treatment decisions regarding the appropriate use of antithrombotic therapy in people with cancer at the end of life.

CONCLUSIONS

We aim to develop an intervention that guides the appropriate use of antithrombotic therapy, prevents bleeding complications, and saves healthcare costs. Hopefully, usage of the tool leads to enhanced empowerment and improved quality of life and treatment satisfaction of people with advanced cancer and their care givers.

Disruption of the Aspergillus fumigatus RNA interference machinery alters the conidial transcriptome

The RNA interference (RNAi) pathway has evolved numerous functionalities in eukaryotes, with many on display in Kingdom Fungi. RNAi can regulate gene expression, facilitate drug resistance, or even be altogether lost to improve growth potential in some fungal pathogens. In the WHO fungal priority pathogen, Aspergillus fumigatus, the RNAi system is known to be intact and functional. To extend our limited understanding of A. fumigatus RNAi, we first investigated the genetic variation in RNAi-associated genes in a collection of 217 environmental and 83 clinical genomes, where we found that RNAi components are conserved even in clinical strains. Using endogenously expressed inverted-repeat transgenes complementary to a conditionally essential gene (pabA) or a nonessential gene (pksP), we determined that a subset of the RNAi componentry is active in inverted-repeat transgene silencing in conidia and mycelium. Analysis of mRNA-seq data from RNAi double-knockout strains linked the A. fumigatus dicer-like enzymes (DclA/B) and RNA-dependent RNA polymerases (RrpA/B) to regulation of conidial ribosome biogenesis genes; however, surprisingly few endogenous small RNAs were identified in conidia that could explain this broad change. Although RNAi was not clearly linked to growth or stress response defects in the RNAi knockouts, serial passaging of RNAi knockout strains for six generations resulted in lineages with diminished spore production over time, indicating that loss of RNAi can exert a fitness cost on the fungus. Cumulatively, A. fumigatus RNAi appears to play an active role in defense against double-stranded RNA species alongside a previously unappreciated housekeeping function in regulation of conidial ribosomal biogenesis genes.

Phase I of the DiaVACCS screening trial: Study design, methods, population demographics and baseline results

BACKGROUND

Human papillomavirus (HPV)-based primary screening guidelines are based on screening test performance and prevalence data generated in high-resource areas with low HIV infection rates. There is an urgent need for local data on infection and disease prevalence, as well as screening test performance, among both HIV-positive and HIV-negative South African (SA) women, in order to inform updated screening guidelines. Objectives. This study describes the baseline characteristics of participants in the cross-sectional phase of the multicentric DIAgnosis in Vaccine And Cervical Cancer Screen (DiaVACCS) screening trial. The objective was to determine the prevalence of positive screening and pre-invasive disease using different tests and strategies in the SA HIV-positive and HIV-negative population.

METHODS

A total of 1  104 women aged 25 - 65 years and eligible for screening were included, 465 HIV positive and 639 HIV negative. Visual inspection and molecular and cytological screening tests were done on self-sampled and healthcare worker-collected specimens. All participants who screened positive and 49.1% of those who screened negative were invited for colposcopy and biopsy, and those qualifying for treatment were recalled for large loop excision of the transformation zone as part of the trial. The worst histology result for each participant was used, and for untested women, multiple imputation was used to estimate verification biasadjusted histology values.

RESULTS

Visual inspection was positive in 50.4% of HIV-positive v. 20.9% of HIV-negative women, cytology (atypical squamous cells of undetermined significance) in 39.9% v. 17.0%, and high-risk HPV DNA in 41.2% v. 19.6%. Overall, high-grade squamous intraepithelial lesion-positive cytology peaked in the age group 30 - 39 years at 16.7%. After adjustment for verification bias, histological diagnosis of cervical intraepithelial neoplasia (CIN)2+ was suspected in 44.7% v. 23.5% and CIN3+ in 23.3% v. 10.2% of HIV-positive and negative women, respectively. Invasive cancer was diagnosed in 15 women (1.95% of histological studies performed), and verification bias adjustment suggested 20 cases (1.8% of the study population).

CONCLUSION

The baseline findings from the DiaVACCS trial confirm a high prevalence of HPV-related cervical pathology in the SA HIV-negative screening population, showing a clear need to reach these women with a screening programme. Among HIV-positive women, prevalence values were almost doubled. The prevalence of existing invasive cervical cancer was 1 - 2% of all women. Further analysis of the performance of single and multiple screening tests between the two subgroups will contribute to the choice of the most effective strategies to identify women at risk of developing invasive cancer.

PLB-985 Neutrophil-Like Cells as a Model To Study Aspergillus fumigatus Pathogenesis

Fungal infections remain a major global concern. Emerging fungal pathogens and increasing rates of resistance mean that additional research efforts and resources must be allocated to advancing our understanding of fungal pathogenesis and developing new therapeutic interventions. Neutrophilic granulocytes are a major cell type involved in protection against the important fungal pathogen Aspergillus fumigatus, where they employ numerous defense mechanisms, including production of antimicrobial extracellular vesicles. A major drawback to work with neutrophils is the lack of a suitable cell line system for the study of fungal pathogenesis. To address this problem, we assessed the feasibility of using differentiated PLB-985 neutrophil-like cells as an in vitro model to study A. fumigatus infection. We find that dimethylformamide-differentiated PLB-985 cells provide a useful recapitulation of many aspects of A. fumigatus interactions with primary human polymorphonuclear leukocytes. We show that differentiated PLB-985 cells phagocytose fungal conidia and acidify conidia-containing phagolysosomes similar to primary neutrophils, release neutrophil extracellular traps, and also produce antifungal extracellular vesicles in response to infection. In addition, we provide an improved method for the isolation of extracellular vesicles produced during infection by employing a size exclusion chromatography-based approach. Advanced liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomics revealed an enrichment of extracellular vesicle marker proteins and a decrease of cytoplasmic proteins in extracellular vesicles isolated using this improved method. Ultimately, we find that differentiated PLB-985 cells can serve as a genetically tractable model to study many aspects of A. fumigatus pathogenesis. IMPORTANCE Polymorphonuclear leukocytes are an important defense against human fungal pathogens, yet our model systems to study this group of cells remain very limited in scope. In this study, we established that differentiated PLB-985 cells can serve as a model to recapitulate several important aspects of human polymorphonuclear leukocyte interactions with the important human fungal pathogen Aspergillus fumigatus. The proposed addition of a cultured neutrophil-like cell line to the experimental toolbox to study fungal pathogenesis will allow for a more mechanistic description of neutrophil antifungal biology. In addition, the easier handling of the cell line compared to primary human neutrophils allowed us to use PLB-985 cells to provide an improved method for isolation of neutrophil-derived extracellular vesicles using size exclusion chromatography. Together, these results provide significant tools and a baseline knowledge for the future study of neutrophil-derived extracellular vesicles in the laboratory.

Host-derived extracellular vesicles for antimicrobial defense

Extracellular vesicles are of increasing importance in the clinic, as diagnostics for complex diseases and as potential delivery systems for therapeutics. Over the past several decades, extracellular vesicles have emerged as a widespread, conserved mechanism of intercellular and interkingdom communication. The ubiquitous distribution of extracellular vesicles across life offers at least two compelling opportunities: first a path forward in the design of targeted antimicrobial delivery systems; and second, a new way to view host pathogenesis during infection. Both avenues of research are well underway. In particular, preliminary studies showing that plant and human host-derived extracellular vesicles can deliver natural antimicrobial cargos to invading fungal and bacterial pathogens are captivating. Further, modification of host extracellular vesicle populations may ultimately lead to enhanced killing and serve as a starting point for the development of more advanced therapeutic options, especially against difficult to treat pathogens. Despite the rapid pace of growth surrounding extracellular vesicle biology, many questions remain unanswered. For example, the heterogeneity of vesicle populations continues to be a confounding factor in ascribing clear functions to a vesicular subset, and the molecular cargos responsible for specific antimicrobial actions of extracellular vesicles during infection remain especially poorly described. In this short review, we will summarize the current state of affairs surrounding the antimicrobial function, and potential, of host-derived extracellular vesicles.

Incidence of thrombotic complications and overall survival in hospitalized patients with COVID-19 in the second and first wave

INTRODUCTION

In the first wave, thrombotic complications were common in COVID-19 patients. It is unknown whether state-of-the-art treatment has resulted in less thrombotic complications in the second wave.

METHODS

We assessed the incidence of thrombotic complications and overall mortality in COVID-19 patients admitted to eight Dutch hospitals between September 1st and November 30th 2020. Follow-up ended at discharge, transfer to another hospital, when they died, or on November 30th 2020, whichever came first. Cumulative incidences were estimated, adjusted for competing risk of death. These were compared to those observed in 579 patients admitted in the first wave, between February 24th and April 26th 2020, by means of Cox regression techniques adjusted for age, sex and weight.

RESULTS

In total 947 patients with COVID-19 were included in this analysis, of whom 358 patients were admitted to the ICU; 144 patients died (15%). The adjusted cumulative incidence of all thrombotic complications after 10, 20 and 30 days was 12% (95% confidence interval (CI) 9.8-15%), 16% (13-19%) and 21% (17-25%), respectively. Patient characteristics between the first and second wave were comparable. The adjusted hazard ratio (HR) for overall mortality in the second wave versus the first wave was 0.53 (95%CI 0.41-0.70). The adjusted HR for any thrombotic complication in the second versus the first wave was 0.89 (95%CI 0.65-1.2).

CONCLUSIONS

Mortality was reduced by 47% in the second wave, but the thrombotic complication rate remained high, and comparable to the first wave. Careful attention to provision of adequate thromboprophylaxis is invariably warranted.

Comparative performance of dairy cows in low-input smallholder and high-input production systems in South Africa

The aim of this study was to benchmark the performance of dairy cows in the low-input smallholder system against their counterparts in the high-input system, in South Africa. Data comprised of cow performance records from the national dairy recording scheme. Performance measures included production (305-day yields of milk, fat, and protein), lactation length, somatic cell count (SCC), and reproductive traits, represented by age at first calving (AFC) and calving interval (CI). Least squares means of each trait were compared between the two systems, and lactation curves for production traits and SCC were plotted for each production system. Mean yields of milk, fat, and protein were significantly (P < 0.05) lower in the smallholder (4097 ± 165, 174 ± 5.1, and 141 ± 4.5 respectively) compared to the high-input system (6921 ± 141, 298 ± 4.7, and 245 ± 4.1 respectively). Mean lactation length was significantly (P < 0.05) shorter for the smallholder (308 ± 15.1) than the high-input system (346 ± 12.8). Log-transformed somatic cell count (SCS) was, however, significantly (P < 0.05) higher in the smallholder (2.41 ± 0.01) relative to the high-input system (2.27 ± 0.01). Cows in high-input herds showed typical lactation curves, in contrast to the flat and low peaking curves obtained for the smallholder system. Cows on smallholder herds had their first calving significantly (P < 0.05) older (30 ± 0.5) than those in the high-input system (27 ± 0.5). There was, however, no significant difference (P < 0.05) in CI between the two systems. These results highlight large room for improvement of dairy cow performance in the smallholder system and could assist in decision-making aimed at improving the productivity of the South African dairy industry.

A survey analysis of indigenous goat production in communal farming systems of Botswana

A total of 153 communal farmers in four agro-ecological regions of Botswana were interviewed using a structured questionnaire. The aims of the survey were to characterise existing communal goat production systems, evaluate the importance of goats to farmers and identify breeding practices and constraints encountered in goat production in Botswana. Data was collected on socio-economic parameters, general and breeding management practices and major constraints limiting goat production in Botswana. All respondents were small-scale communal farmers with 63% respondents practising mixed crop-livestock farming and 37% keeping livestock as their primary activity. The majority (33%) of respondents were older than 60 years. Over 80% of the farmers kept goats for cash required for tuition, school uniforms and household commodities as well as re-stocking of animals. Most farmers (62%) kept indigenous crossed genotypes. Generally, uncontrolled mating was practised with the majority of farmers (41%) using on-farm reared bucks for more than two years of breeding and communal bucks (36%) as an alternative. The major constraints limiting goat productivity in communal areas included uncontrolled breeding, predators, theft and diseases. Issues raised by farmers should be considered in designing and implementing effective breeding programs for goats to improve their overall productivity and contribution to poverty alleviation in these communities.

Ross River virus disease in two Dutch travellers returning from Australia, February to April 2015

We report two cases of Ross River virus (RRV) infection in Dutch travellers who visited Australia during February to April 2015. These cases coincided with the largest recorded outbreak of RRV disease in Australia since 1996. This report serves to create awareness among physicians to consider travel-related RRV disease in differential diagnosis of patients with fever, arthralgia and/or rash returning from the South Pacific area, and to promote awareness among professionals advising travellers to this region.

Community treatment orders: clinical and social outcomes, and a subgroup analysis from the OCTET RCT

OBJECTIVE

Despite widespread use internationally, there is no convincing evidence that community treatment orders (CTO) (legal regimes making out-patient treatment compulsory), reduce readmission rates or have wider patient benefit. The primary and secondary outcomes of the Oxford Community Treatment Order Evaluation Trial (OCTET) (hospitalisation) showed no benefit. This article will, first, test the effect of community compulsion on wider clinical and social outcomes and on patients' experiences of services and the use of treatment pressure and second, explore differential effects in different groups of patients.

METHOD

OCTET is a RCT of CTO effectiveness. Three hundred and thirty-six patients were randomised and data for the 333 eligible patients were collected from interviews and medical records at baseline, 6 and 12 months.

RESULTS

There was no significant difference at 12 months between the two arms in any of the reported outcomes, except a small difference in patients' view of the effectiveness of treatment pressure, which is unlikely to be clinically meaningful. Two statistically significant interactions were found in the subgroup analysis: symptoms interacted with age and with education, but no pattern was demonstrated.

CONCLUSION

CTOs do not have benefit on any of the tested outcomes, or for any subgroup of patients. Their continued use should be carefully reconsidered.

Cell proliferation and apoptosis in the exocrine pancreas of azaserine-treated rats and N-nitrosobis(2-oxopropyl)amine-treated hamsters

Altered cell proliferation is an important characteristic of neoplastic development, hence the quantitation of cell growth in normal and (pre)neoplastic pancreatic tissue will provide useful information on the process (and modulation) of pancreatic tumour promotion in experimental animals. Cell proliferation was estimated by means of BrdU-incorporation in normal pancreatic tissue and in putative preneoplastic pancreatic tissue of azaserine-treated rats and of N-nitrosobis(2-oxopropyl)amine (BOP)-treated hamsters at 2, 6, 12, 26 and 52 weeks post-treatment. Furthermore, the effects of diets high in vegetable oil or fish oil on the BrdU labeling index, the Ki-67 labeling index as well as the apoptotic labeling index were determined in azaserine-induced atypical acinar cell foci (AACF) in the pancreas of rats. In saline- and azaserine-treated rats, the BrdU labeling index (LI) in normal pancreatic acinar cells showed a similar time-related decrease. In azaserine-treated rats, the BrdU-LI in AACF was significantly higher than in normal acinar tissue. The BrdU, Ki-67 and apoptotic labeling indices in pancreatic AACF of rats fed diets high in vegetable oil versus fish oil were 24.8+/-1.7 vs 15.5+/-1.2 (BrdU; P<0.05), 9.9+/-0.8 vs 6.5+/-0.5 (Ki-67; P<0.001) and 1.31+/-0.12 vs 0.97+/-0.11 (apoptosis; P<0.05), respectively. In hamsters, up to 26 weeks after BOP-treatment the BrdU-LI in acinar cells was significantly higher than in saline-treated animals. In BOP-treated hamsters, ductal cells showed a significantly increased LI 2 weeks post-treatment, whereas the LI in centroacinar cells had significantly increased 2 and 26 weeks post-treatment. In hamster pancreas the LI was significantly higher in tubular ductal complexes than in cystic ductal complexes and was highest in borderline lesions. It is concluded that (i) determination of BrdU-LI provides a reliable parameter to discriminate between putative preneoplastic lesions with a high or low growth potential, hence with a high or low potential to develop into ultimate carcinomas, (ii) BOP causes increased DNA synthesis in normal acinar cells, leading to increased risk of additional DNA damage, implicating the acinar cell to be putatively involved in the development of ductular adenocarcinomas in the hamster pancreas and (iii) quantitation of cell proliferation and apoptosis may be useful to determine the enhancing or inhibitory effects of life-style factors on pancreatic carcinogenesis.

Chlamydophila psittaci infections in The Netherlands

Psittacosis, caused by Chlamydophila psittaci, is a well described but sporadically occurring clinical entity, which mainly presents as community-acquired pneumonia. Diagnosis used to be relatively difficult. However, new molecular techniques, such as real-time polymerase chain reaction, increased detection of cases. Furthermore, genotyping of the ompA gene can be used as a tool to trace the possible source of an outbreak or to link a specific bird to a particular patient.

Treatment of accidental hypothermia with cardiopulmonary bypass: a case report

This case report describes the successful treatment of severe accidental hypothermia of a 40-year-old woman. At arrival in the operating theatre her rectal temperature was 23 degrees C, her nasal temperature 21 degrees C and her periferal temperature 14 degrees C. The patient presented with a severe respiratory and metabolic acidosis which was corrected during cardiopulmonary bypass (CPB). She was rewarmed to obtain a rectal and nasal temperature of 34 degrees C. After 272 minutes, the patient was weaned successfully from CPB. The patient remained at mild hypothermia (34 degrees C) for 24 hours in the intensive care unit (ICU). The chest X-ray showed some signs of acute respiratory distress syndrome (ARDS) in spite of normal blood gas values. This improved within a few days and, after five days, she was transferred to the nursing department. On the seventh day, the patient was discharged from hospital without physical or neurological complaints.

Emergency operation on the dissected ascending aorta of an adolescent with aortic coarctation

This case report describes the successful repair of an acute dissection of the ascending aorta in a 16-year-old girl. The dissection appeared to be related to the presence of an aortic coarctation. Furthermore, a bicuspid aortic valve was found. Echocardiography was helpful for quick pre-operative diagnosis. A computed tomography (CT) scan was used post-operatively to confirm these results. At the onset of extracorporeal circulation, active drainage was applied at the femoral vein by means of a routinely built-in shunt bypassing the venous reservoir. The practical implementation of this shunt is described in this report. One femoral artery and one femoral vein were cannulated, resulting in a blood flow index of 2.21.min(-l).m(-2) which proved to be sufficient for blood supply to both the lower and the upper parts of the body. Successful percutaneous dilatation of the coarctation was performed five months after the first operation.

Hyperammonemia in generalized Mycobacterium genavense infection after renal transplantation

After solid organ transplantation, patients are susceptible to infection caused by uncommon pathogens due the immunosuppressive drug therapy. Here, we report the first case of disseminated Mycobacterium genavense infection in a HIV seronegative renal transplant patient. The most striking clinical feature was a decreased consciousness. Blood results revealed hyperammonemia with otherwise normal liver function. Occurrence of hyperammonemia and massive M. genavense infection has not been reported before.

The influence of fluticasone inhalation on premalignant lesions in the bronchial epithelium of a high risk population: A double blind placebo-controlled randomised phase II study

7200

Background: Bronchial epithelium exposed to cigarette smoke undergoes a series of histological changes that may ultimately lead to invasive cancer. In rats exposed to cigarette smoke inhaled corticosteroids reduce the number of lung tumors. We studied the effect of fluticasone on premalignant lesions in volunteers with a smoking history of ≥10 pack-years and patients cured of head and neck cancer or lung cancer. Methods: Participants were screened for premalignant lesions by bronchoscopy. At least 3 standard locations and suspicious lesions (if present) were biopsied. Use of systemic corticosteroids in the past 12 months or serious comorbidity precluded participation. Biopsies were classifed using WHO criteria. In case of a metaplasia index > 15%, participants were randomised to receive a powder inhalation device containing either fluticasone 500 μg or a placebo. Compliance and side effects were monitored monthly. After 6 months, biopsies were taken from the same locations as previously sampled. Efficacy of treatment was assessed by reversal of metaplasia/dysplasia; secondary end-points were reversal of increased p53 immunoreactivity and hTERT expression. CT-scans were obtained at baseline and after intervention. Results: From February 2002 until October 2004, 201 subjects were screened. Two were excluded because of lung cancer detected during screening. Of the 108 volunteers included, 74 were male, mean age was 53 years (35–71), mean number of pack-years 48 (18–99), mean metaplasia index 48%, 32% had some degree of dysplasia at baseline. There were no significant differences between these characteristics in the intervention and placebo groups. Outcome: there was no significant difference with respect to reversal of metaplasia/dysplasia. Additional molecular studies will be performed to assess possible changes at a molecular level. Results will be presented at the ASCO annual meeting 2006. Conclusions: Fluticasone does not alter the natural course of premalignant lesions in the central airways when standard histological criteria are applied.

No significant financial relationships to disclose.