Ventilator-associated pneumonia due to colistin susceptible-only microorganisms

Acinetobacter spp. and Pseudomonas aeruginosa are common pathogens of ventilator-associated pneumonia (VAP). The presentation and outcome of VAP due to Acinetobacter spp. and P. aeruginosa susceptible to carbapenems (Carb-S; imipenem and/or meropenem) and to colistin only (Col-S) were compared in the present retrospective study in three intensive care units. A total of 61 episodes of VAP caused by Acinetobacter spp. or P. aeruginosa were studied, of which 30 isolates were Carb-S and 31 were Col-S. Demographics, worsening of renal function and mortality were not different. The univariate analysis showed that a later onset and a previous episode of VAP, prior antimicrobial therapy for >10 days and previous therapy with carbapenems during the present admission were more frequent in patients with Col-S strains. On multivariate analysis, prior antimicrobial therapy for >10 days and a previous episode of VAP remained significantly associated with Col-S VAP. Approximately 41% of the infections caused by Col-S isolates, but none of those due to Carb-S isolates, had received prior carbapenem therapy. Colistin-susceptible ventilator-associated pneumonia episodes can be effectively treated using colistin without significant renal dysfunction. This susceptibility pattern could be suspected in patients with a previous ventilator-associated pneumonia episode or prior antibiotic therapy for >10 days preceding the present ventilator-associated pneumonia episode.

Targeting EphA3 inhibits cancer growth by disrupting the tumor stromal microenvironment

Eph receptor tyrosine kinases are critical for cell-cell communication during normal and oncogenic tissue patterning and tumor growth. Somatic mutation profiles of several cancer genomes suggest EphA3 as a tumor suppressor, but its oncogenic expression pattern and role in tumorigenesis remain largely undefined. Here, we report unexpected EphA3 overexpression within the microenvironment of a range of human cancers and mouse tumor xenografts where its activation inhibits tumor growth. EphA3 is found on mouse bone marrow-derived cells with mesenchymal and myeloid phenotypes, and activation of EphA3(+)/CD90(+)/Sca1(+) mesenchymal/stromal cells with an EphA3 agonist leads to cell contraction, cell-cell segregation, and apoptosis. Treatment of mice with an agonistic α-EphA3 antibody inhibits tumor growth by severely disrupting the integrity and function of newly formed tumor stroma and microvasculature. Our data define EphA3 as a novel target for selective ablation of the tumor microenvironment and demonstrate the potential of EphA3 agonists for anticancer therapy.

An activated form of ADAM10 is tumor selective and regulates cancer stem-like cells and tumor growth

The transmembrane metalloprotease ADAM10 sheds a range of cell surface proteins, including ligands and receptors of the Notch, Eph, and erbB families, thereby activating signaling pathways critical for tumor initiation and maintenance. ADAM10 is thus a promising therapeutic target. Although widely expressed, its activity is normally tightly regulated. We now report prevalence of an active form of ADAM10 in tumors compared with normal tissues, in mouse models and humans, identified by our conformation-specific antibody mAb 8C7. Structure/function experiments indicate mAb 8C7 binds an active conformation dependent on disulfide isomerization and oxidative conditions, common in tumors. Moreover, this active ADAM10 form marks cancer stem-like cells with active Notch signaling, known to mediate chemoresistance. Importantly, specific targeting of active ADAM10 with 8C7 inhibits Notch activity and tumor growth in mouse models, particularly regrowth after chemotherapy. Our results indicate targeted inhibition of active ADAM10 as a potential therapy for ADAM10-dependent tumor development and drug resistance.

Measurements of respiratory system resistance by the interrupter technique in healthy and asthmatic children

We studied respiratory system resistance by the interrupter technique (Rint) in healthy and asthmatic children, paying special attention to the effect of cheek compliance and the effects of supporting the cheeks, the influence of lung volume at which interruption was performed, the effect of direction of flow before occlusion (inspiration vs. expiration), and short-term reproducibility of this method. One hundred and thirty-two children (36 controls and 96 asthmatics) were included in the study (mean, 9.0 +/- SD 3.6 years). Rint was calculated from the ratio of the alveolar pressure (estimated from moth pressure during occlusion) to the flow prior to interruption. We observed that 1) underestimation of airway resistance due to upper airway compliance can be minimized by supporting the cheeks; Rint was significantly lower when measured without supporting the cheeks than with support of the cheeks in controls (3.9 +/- 0.9 vs. 4.7 +/- 1.2 cmH2O.L-1.s, respectively) and asthmatics (5.2 +/- 1.6 vs 6.9 +/- 2.0 cmH2O.L-1.s); the quantitative differences of Rint with and without cheek support was larger in small children and in the most obstructed children; 2) performing occlusion at mid-tidal volume accurately reflected the respiratory system resistance of the whole respiratory cycle since we observed no difference in Rint when performing occlusion at different volumes during quiet respiration or at the middle of tidal volume; 3) Rint measured during expiration was higher than Rint obtained during inspiration in controls and in asthmatics; moreover, the effect of direction of flow before occlusion was greater in the small children; 4) Rint was closely correlated to height in controls (r = -0.82; P < 0.001); and 5) short-term reproducibility (at 15 min intervals) was satisfactory in controls and asthmatics (coefficients of variation were 9% and 7%, respectively).

Antibodies binding the ADAM10 substrate recognition domain inhibit Eph function

The ADAM10 transmembrane metalloprotease cleaves a variety of cell surface proteins that are important in disease, including ligands for receptor tyrosine kinases of the erbB and Eph families. ADAM10-mediated cleavage of ephrins, the ligands for Eph receptors, is suggested to control Eph/ephrin-mediated cell-cell adhesion and segregation, important during normal developmental processes, and implicated in tumour neo-angiogenesis and metastasis. We previously identified a substrate-binding pocket in the ADAM10 C domain that binds the EphA/ephrin-A complex thereby regulating ephrin cleavage. We have now generated monoclonal antibodies specifically recognising this region of ADAM10, which inhibit ephrin cleavage and Eph/ephrin-mediated cell function, including ephrin-induced Eph receptor internalisation, phosphorylation and Eph-mediated cell segregation. Our studies confirm the important role of ADAM10 in cell-cell interactions mediated by both A- and B-type Eph receptors, and suggest antibodies against the ADAM10 substrate-recognition pocket as promising therapeutic agents, acting by inhibiting cleavage of ephrins and potentially other ADAM10 substrates.

A high-affinity human TCR-like antibody detects celiac disease gluten peptide-MHC complexes and inhibits T cell activation

Antibodies specific for peptides bound to human leukocyte antigen (HLA) molecules are valuable tools for studies of antigen presentation and may have therapeutic potential. Here, we generated human T cell receptor (TCR)-like antibodies toward the immunodominant signature gluten epitope DQ2.5-glia-α2 in celiac disease (CeD). Phage display selection combined with secondary targeted engineering was used to obtain highly specific antibodies with picomolar affinity. The crystal structure of a Fab fragment of the lead antibody 3.C11 in complex with HLA-DQ2.5:DQ2.5-glia-α2 revealed a binding geometry and interaction mode highly similar to prototypic TCRs specific for the same complex. Assessment of CeD biopsy material confirmed disease specificity and reinforced the notion that abundant plasma cells present antigen in the inflamed CeD gut. Furthermore, 3.C11 specifically inhibited activation and proliferation of gluten-specific CD4⁺ T cells in vitro and in HLA-DQ2.5 humanized mice, suggesting a potential for targeted intervention without compromising systemic immunity.

Low influenza vaccination coverage in asthmatic children in France in 2006-7

In France, annual seasonal influenza vaccination has been recommended since 2000 for patients suffering from chronic respiratory diseases, including asthma. Since 1988, each year from September to December, a free influenza vaccination voucher is sent by the French Public Health Insurance authorities to patients with chronic respiratory disease, including severe asthma. In November 2006, this measure was extended to all asthmatic patients, irrespective of asthma severity. The present paper examines the 2006-7 influenza vaccination coverage rate (VCR) in 433 asthmatic children aged 6 to 17 years (mean age: 9.5 years; male: 61%) who consulted a paediatric pulmonologist between March and September 2007 in eight hospitals throughout France. The influenza VCR was 15.7% for the 2006-7 season (13.9% for the 2005-6 season and 10.9% for the 2004-5 season). General practitioners vaccinated 72.1% of the children. "Lack of information" (42%) was the most frequently reported reason for non-vaccination. Vouchers (received by 39.6% of the children) significantly increased the VCR (31% versus 5.9%; p<0.001). In France, in 2006-7, the influenza VCR in asthmatic children was far below the national public health objective (at least 75% for the year 2008). Concerted action is needed to improve the influenza VCR in asthmatic children.

The cryo-EM structure of the endocytic receptor DEC-205

DEC-205 (CD205), a member of the macrophage mannose receptor protein family, is the prototypic endocytic receptor of dendritic cells, whose ligands include phosphorothioated cytosine-guanosine oligonucleotides, a motif often seen in bacterial or viral DNA. However, despite growing biological and clinical significance, little is known about the structural arrangement of this receptor or any of its family members. Here, we describe the 3.2 Å cryo-EM structure of human DEC-205, thereby illuminating the structure of the mannose receptor protein family. The DEC-205 monomer forms a compact structure comprising two intercalated rings of C-type lectin-like domains, where the N-terminal cysteine-rich and fibronectin domains reside at the central intersection. We establish a pH-dependent oligomerization pathway forming tetrameric DEC-205 using solution-based techniques and ultimately solved the 4.9 Å cryo-EM structure of the DEC-205 tetramer to identify the unfurling of the second lectin ring which enables tetramer formation. Furthermore, we suggest the relevance of this oligomerization pathway within a cellular setting, whereby cytosine-guanosine binding appeared to disrupt this cell-surface oligomer. Accordingly, we provide insight into the structure and oligomeric assembly of the DEC-205 receptor.

Subcutaneous fat accumulation during pregnancy in a malnourished population

1. Total skinfold thicknesses (sum of seven sites) were measured in fifty-seven pregnant women with low energy and protein intake, at weeks 24, 30 and 35 of gestation. 2. Women were classified in two groups (overweight and low weight), according to their weight-for-height at week 24 of gestation. 3. Half of the women did not increase, or even reduced the amount of subcutaneous fat during the observation period. The lowest mean value of total skinfold thickness was found in the low-weight women who showed a reduction of the subcutaneous fat. 4. This finding shows that a significant proportion of malnourished women do not follow the average pattern of subcutaneous fat accumulation seen in healthy pregnant women without food intake restriction, during the second half of pregnancy.

Hypoxia-controlled EphA3 marks a human endometrium-derived multipotent mesenchymal stromal cell that supports vascular growth

Eph and ephrin proteins are essential cell guidance cues that orchestrate cell navigation and control cell-cell interactions during developmental tissue patterning, organogenesis and vasculogenesis. They have been extensively studied in animal models of embryogenesis and adult tissue regeneration, but less is known about their expression and function during human tissue and organ regeneration. We discovered the hypoxia inducible factor (HIF)-1α-controlled expression of EphA3, an Eph family member with critical functions during human tumour progression, in the vascularised tissue of regenerating human endometrium and on isolated human endometrial multipotent mesenchymal stromal cells (eMSCs), but not in other highly vascularised human organs. EphA3 affinity-isolation from human biopsy tissue yielded multipotent CD29⁺/CD73⁺/CD90⁺/CD146⁺ eMSCs that can be clonally propagated and respond to EphA3 agonists with EphA3 phosphorylation, cell contraction, cell-cell segregation and directed cell migration. EphA3 silencing significantly inhibited the ability of transplanted eMSCs to support neovascularisation in immunocompromised mice. In accord with established roles of Eph receptors in mediating interactions between endothelial and perivascular stromal cells during mouse development, our findings suggest that HIF-1α-controlled expression of EphA3 on human MSCs functions during the hypoxia-initiated early stages of adult blood vessel formation.

PTP-PEST controls EphA3 activation and ephrin-induced cytoskeletal remodelling

Eph receptors and their corresponding membrane-bound ephrin ligands regulate cell positioning and establish tissue patterns during embryonic and oncogenic development. Emerging evidence suggests that assembly of polymeric Eph signalling clusters relies on cytoskeletal reorganisation and underlies regulation by protein tyrosine phosphatases (PTPs). PTP-PEST (also known as PTPN12) is a central regulator of actin cytoskeletal dynamics. Here, we demonstrate that an N-terminal fragment of PTP-PEST, generated through an ephrinA5-triggered and spatially confined cleavage mediated by caspase-3, attenuates EphA3 receptor activation and its internalisation. Isolation of EphA3 receptor signalling clusters within intact plasma membrane fragments obtained by detergent-free cell fractionation reveals that stimulation of cells with ephrin triggers effective recruitment of this catalytically active truncated form of PTP-PEST together with key cytoskeletal and focal adhesion proteins. Importantly, modulation of actin polymerisation using pharmacological and dominant-negative approaches affects EphA3 phosphorylation in a similar manner to overexpression of PTP-PEST. We conclude that PTP-PEST regulates EphA3 activation both by affecting cytoskeletal remodelling and through its direct action as a PTP controlling EphA3 phosphorylation, indicating its multifaceted regulation of Eph signalling.

[Influenza vaccination coverage in asthmatic children in France in 2006-2007]

In France, an annual seasonal influenza vaccination has been recommended since 2000 for patients suffering from chronic respiratory diseases, including asthma. Each year, a free influenza vaccination voucher is sent by the French Public Health Insurance authorities to patients with chronic respiratory disease, including severe asthma. In November 2006, this measure was extended to all asthmatic patients, irrespective of asthma severity. The present paper examines the 2006-2007 influenza vaccination coverage rate in 433 asthmatic children aged six to 17 years (mean age: 9.5 years; male: 61%) who consulted a pediatric pulmonologist between March and September 2007 in eight hospitals throughout France. The influenza vaccination coverage rate was 15.7% for the 2006-2007 season (13.9% for the 2005-2006 season and 10.9% for the 2004-2005 season). General practitioners vaccinated 72.1% of the children. Lack of information (42%) was the most frequently reported reason for non-vaccination. Free vouchers (received by 39.6% of the children) significantly increased the vaccination coverage rate (31% versus 5.9%; p < 0.001). In France, in 2006-2007, the influenza vaccination coverage rate in asthmatic children was far below the national public health objective to achieve for the year 2008 (at least 75%). Concerted action is needed to improve the influenza vaccination coverage rate in asthmatic children.

Practical Application of Computer-Assisted Decision-Making in an Antenatal Clinic — A Feasibility Study

A feasibility study is described involving the use of a computer program in an antenatal clinic whose decisions were based on the observed policies of the group of obstetricians running that clinic. In 200 test cases the programme successfully detected all »at risk« cases at the first visit. Abnormalities appearing at later visits were all detected and appropriate investigations ordered by the programme. The programme ordered rather more investigations than the obstetrician and this difference has been investigated, in some detail with reference to the full blood count, glucose tolerance test and the ultrasonogram.

Since all of the basic data in the proposed clinic would be collected by the clerical staff or midwives, a comparison was made between two midwives and an obstetrician in estimating fundal height. The small number of discrepancies found was not regarded as serious from the viewpoint of the proposed clinic.

This preliminary study suggests that the technique described might play a useful part in some areas of ante-natal care by relieving the obstetricians of much of the workload associated with routine cases and enabling the midwife to play a larger role in ante-natal care.

Pneumopathies récidivantes révélant une tumeur carcinoïde bronchique : à propos de deux observations

Carcinoid tumors are the most common endobronchial tumor in the pediatric population, and represent a rare cause of airway obstruction. The authors report two cases of boys aged 10 and 11 years old, who presented with a 12-month history of recurrent pneumonia. Bronchial endoscopy showed an endobronchial tumor. Chest CT-scan identified local extension and lung-associated lesions; octreoscan was performed to detect distant metastases. Histopathological study concluded in typical carcinoid tumor. The outcome after surgical conservative resection is uneventful with a follow-up of 7 and 26 months. Bronchial tumors must be considered in children with recurrent pneumonia or persistant respiratory symptoms, and require CT scan and bronchial endoscopy for their diagnosis.

[Quality criteria for the transition to adult care in French CF centers - results from the SAFETIM APP study?]

INTRODUCTION

SAFETIM-APP compiled an inventory of professional practice in the 45 French cystic fibrosis reference centres (CFRC), between February 2015 and December 2016, related to the transition of adolescents with cystic fibrosis to adult centres.

METHOD

This multicentre cross-sectional study addressed the modalities of the transition in CFRCs and proposed a list of items that could be used to establish quality criteria. Quantitative analysis of the criteria and a qualitative analysis of the transition procedure were carried out.

RESULTS

A total of 77% of the CFRCs that were contacted took part. Transition lasted 3 to 5 years and began at around 15 years of age. Nine criteria were described as fundamental, including: collaboration between teams, taking adolescence into account, having a time for adolescents to speak with the physician alone, defining a program including therapeutic education, involving the family, accompanying the parents. Seven additional criteria were noted to be important, including: re-announcing the diagnosis, identifying a common thread (caregiver) accompanying the family, scheduling adult follow-up from paediatrics onwards, visiting the adult department, organizing a formal departure/reception time, initiating the process early enough, identifying indicators to evaluate practices.

CONCLUSION

The transition processes in place in CFRCs can be improved by implementing the use of these quality criteria systematically.

CD4+ T cell-mediated recognition of a conserved cholesterol-dependent cytolysin epitope generates broad antibacterial immunity

CD4⁺ T cell-mediated immunity against Streptococcus pneumoniae (pneumococcus) can protect against recurrent bacterial colonization and invasive pneumococcal diseases (IPDs). Although such immune responses are common, the pertinent antigens have remained elusive. We identified an immunodominant CD4⁺ T cell epitope derived from pneumolysin (Ply), a member of the bacterial cholesterol-dependent cytolysins (CDCs). This epitope was broadly immunogenic as a consequence of presentation by the pervasive human leukocyte antigen (HLA) allotypes DPB1^∗02 and DPB1^∗04 and recognition via architecturally diverse T cell receptors (TCRs). Moreover, the immunogenicity of Ply_427-444 was underpinned by core residues in the conserved undecapeptide region (ECTGLAWEWWR), enabling cross-recognition of heterologous bacterial pathogens expressing CDCs. Molecular studies further showed that HLA-DP4-Ply_427-441 was engaged similarly by private and public TCRs. Collectively, these findings reveal the mechanistic determinants of near-global immune focusing on a trans-phyla bacterial epitope, which could inform ancillary strategies to combat various life-threatening infectious diseases, including IPDs.

A conceptual framework to develop a patient-reported experience questionnaire on the cystic fibrosis journey in France: the ExPaParM collaborative study

BACKGROUND

The objective of the study was to elaborate a conceptual framework related to the domains of patient experience along the cystic fibrosis (CF) journey from the patients and parents of children with CF to inform the design of a patient-reported experience questionnaire.

METHOD

A collaborative research group including patients and parents with clinicians and academic researchers was set up. They identified the situations along the CF care pathway from diagnosis to paediatric care, transition to adult care and adult follow-up, transfer to transplant centres and follow-up after transplantation. Participants were recruited by CF centres in metropolitan France and overseas departments. Semi-structured interviews were conducted, transcribed verbatim and subjected to an inductive analysis conducted in duos of researchers/co-researchers using NVivo®. The conceptual framework was discussed with the research group and presented to the CF centres during two video conferences. The protocol obtained a favourable opinion from the Ethics Evaluation Committee of INSERM (IRB00003888-no. 20-700).

RESULTS

The analysis led to a conceptual framework composed of domains of the CF journey, each divided into several items. 1. CF care: Management of care by the CF centre team; in-hospital care; quality of care in the community; therapeutic education and self-management support; at-home care; new therapies and research; procreation; 2. Transplant care: management of transplant and CF care; coordination with other specialties; education and self-management support; at-home care; procreation; new therapies and research; 3. Turning points along the journey: diagnosis of CF, transition to adult care, transfer to transplantation; 4. Social life with CF: housing, employment and education, social relations, social welfare and family finances. The number of patients included and the diversity of situations made it possible to achieve a sufficient richness and saturation of codes by domain to develop patient experience questionnaires.

CONCLUSION

This conceptual framework, resulting from the participants' experience, will inform the design of a patient-reported experience tool, whose construct will be tested during the next phase of the ExPaParM project to assess its fidelity, intelligibility, and ability to report patient experience of the CF journey.

[Screening and management of glucose metabolism disorders in cystic fibrosis patients. Practices survey in 4 French reference centers]

OBJECTIVE

Glucose metabolism disorders are a new point of interest in cystic fibrosis (CF) management. Cystic fibrosis-related diabetes mellitus (CFRD) increases alteration of pulmonary function as well as patients' morbidity and mortality. In France, CF patients are exclusively followed up in reference centers. We conducted a practices survey on screening and diagnosis of glucose metabolism disorders at 4 French CF centers. The objective of this study was to assess adherence to practice guidelines developed in 2002 at these centers.

METHODS

This study was conducted in 2 sessions: 60 medical records were randomly selected in 2005 and in 2007 for patients aged over 10 years followed up at 4 CF centers. A questionnaire survey was completed for each patient with questions on CFRD screening, diagnosis, monitoring and treatment. Our guidelines recommend random blood glucose (RBG) at each standard biological test, annual glycosylated haemoglobin and an oral glucose tolerance test (OGTT) at 10, 15 and 18 years of age, then every 2 or 3 years.

RESULTS

An annual RBG was performed in 82% of patients in 2005 and 91.5% in 2007. HbA1c screening was performed annually for 77% of patients in the 1st session and for 90% of patients for the 2nd session (p<0.10). Adherence to OGTT guidelines was better for adults than children: 96% had an OGTT during the 3 years of the first session and 79% during the second session, while fewer than 50% of children had their OGTT at 15 and 18 years of age. Taking the OGTT at 10 years of age could not be assessed because no patients were 10 years old during the study period. Screening for neurological complications of CFRD was assessed in the majority of diabetic patients, while half or less than half had annual fundus oculi or microalbuminuria dosage.

DISCUSSION

There was an improvement in screening for CFRD and glucose metabolism disorders between 2005 and 2007, even though practices could still be improved. This shows that clinical guidelines can be implemented and followed. However, screening and management criteria for glucose metabolism disorders must be consensus-based with higher evidence in order to limit the variability of practices and prevent CFRD-related complications.

Crystal structure of the human LAG-3-HLA-DR1-peptide complex

T cell activity is governed by T cell receptor (TCR) signaling and constrained by immune checkpoint molecules, including programmed cell death protein 1 (PD-1), cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and lymphocyte activation gene 3 (LAG-3). The basis for how LAG-3 binds to human leukocyte antigen class II molecules (HLA-II) remains unknown. Here, we present the 3.4-angstrom crystal structure of a LAG-3-peptide-HLA-II complex and probe the energetics of the complex interface. Coincident with the HLA-II binding site of the ancestrally related, monomeric CD4 receptor, the LAG-3 homodimer laterally engages two HLA-II molecules via distal D1 domain surfaces, imposing a 38° angular offset. The LAG-3-HLA-II interface is discontinuous and lacks involvement of the D1 extra loop, a binding site for anti-LAG-3 therapeutic monoclonal antibodies. Upon HLA-II binding, intrinsically mobile loops of the LAG-3 molecule become ordered, with contact residues highly conserved across HLA-DR, DQ, and DP allomorphs. Our data provide a structural foundation for development of immunomodulatory approaches targeting LAG-3.