Erythrocyte invasion-neutralising antibodies prevent Plasmodium falciparum RH5 from binding to basigin-containing membrane protein complexes

Basigin is an essential host receptor for invasion of Plasmodium falciparum into human erythrocytes, interacting with parasite surface protein PfRH5. PfRH5 is a leading blood-stage malaria vaccine candidate and a target of growth-inhibitory antibodies. Here, we show that erythrocyte basigin is exclusively found in one of two macromolecular complexes, bound either to plasma membrane Ca2+-ATPase 1/4 (PMCA1/4) or to monocarboxylate transporter 1 (MCT1). PfRH5 binds to each of these complexes with a higher affinity than to isolated basigin ectodomain, making it likely that these are the physiological targets of PfRH5. PMCA-mediated Ca2+ export is not affected by PfRH5, making it unlikely that this is the mechanism underlying changes in calcium flux at the interface between an erythrocyte and the invading parasite. However, our studies rationalise the function of the most effective growth-inhibitory antibodies targeting PfRH5. While these antibodies do not reduce the binding of PfRH5 to monomeric basigin, they do reduce its binding to basigin-PMCA and basigin-MCT complexes. This indicates that the most effective PfRH5-targeting antibodies inhibit growth by sterically blocking the essential interaction of PfRH5 with basigin in its physiological context.

Structural and biochemical insights into His-tag-induced higher-order oligomerization of membrane proteins by cryo-EM and size exclusion chromatography

Structural and functional characterization of proteins as well as the design of targeted drugs heavily rely on recombinant protein expression and purification. The polyhistidine-tag (His-tag) is among the most prominent examples of affinity tags used for the isolation of recombinant proteins from their expression hosts. Short peptide tags are commonly considered not to interfere with the structure of the tagged protein and tag removal is frequently neglected. This study demonstrates the formation of higher-order oligomers based on the example of two His-tagged membrane proteins, the dimeric arginine-agmatine antiporter AdiC and the pentameric light-driven proton pump proteorhodopsin. Size exclusion chromatography revealed the formation of tetrameric AdiC and decameric as well as pentadecameric proteorhodopsin through specific interactions between their His-tags. In addition, single particle cryo-electron microscopy (cryo-EM) allowed structural insights into the three-dimensional arrangement of the higher-order oligomers and the underlying His-tag-mediated interactions. These results reinforce the importance of considering the length and removal of affinity purification tags and illustrate how neglect can lead to potential interference with downstream biophysical or biochemical characterization of the target protein.

Coordination régionale et suivi prospectif du traitement prophylactique et curatif de 301 patients traités par anticorps monoclonaux anti-SARS-CoV-2

Introduction

La pandémie a particulièrement mis en danger nos patients immunodéprimés et questionne notre place dans l’organisation de l’administration des anticorps monoclonaux à titre préventif et curatif. L’objectif de l’étude a été d’évaluer l’activité d’une cellule régionale mise en place pour évaluer l’indication, organiser le traitement prophylactique ou curatif par anticorps monoclonaux ou par antiviraux, quelle que soit la pathologie chronique des patients concernés.

Matériels et méthodes

La cellule « anticorps monoclonaux et traitements du COVID », composée d’un médecin coordonnateur, de médecins retraités, et d’une secrétaire médicale, a été mise en place début janvier 2022 grâce à un financement par l’ARS. Tous les médecins ont été informés par l’ARS et les URPS, des critères d’éligibilité aux anticorps monoclonaux et du rôle de la cellule dans l’évaluation de l’indication, l’aide apportée pour la demande d’accès précoce et la logistique (injections en hospitalisation de jour ou en hospitalisation à domicile (HAD)). Les structures d’HAD ont été spécifiquement formées aux formalités de prescription, à l’administration et au suivi de ces patients. Les patients ayant reçu un traitement prophylactique ont été recontactés par la cellule la semaine suivant l’injection, 3 mois et 6 mois suivant l’injection. Des questionnaires ont été adressés aux médecins généralistes pour évaluer leur perception concernant les anticorps monoclonaux et les antiviraux.

Résultats

Au total, 216 patients (dont 121 patients ayant des facteurs de risque cardiovasculaire) ont reçu un traitement prophylactique par anticorps monoclonaux (Evusheld), pour les indications suivantes : 110 patients transplantés d’organe, 95 patients traités par anti-CD20, 2 patients traités par chimiothérapie, 8 patients ayant d’autres facteurs d’immunodépression et 1 contre-indication au vaccin. Les sollicitations de la cellule dans cette indication émanaient quasi exclusivement de médecins spécialistes. Avec un suivi médian de 6 mois, aucun événement indésirable (EI) grave, y compris cardiovasculaire, n’est survenu. Des EI non graves ont été observés chez 50 patients (23 %). Trente patients (14 %) ont été infectés par le SARS-CoV-2, dont 2 ont été traités par anticorps monoclonaux à titre curatif et 2 par Paxlovid. Aucun patient n’a été hospitalisé pour COVID, aucun n’a développé de COVID sévère. Sur les 214 patients recontactés pour une ré-administration d’anticorps à visée prophylactique, 12 (5 %) l’ont refusée. Au total, 85 patients ont été traités par anticorps monoclonaux à visée curative dont 3 par Ronapreve, 68 par Xevudy, 14 par Evusheld, dont 53 (62,3 %) en HAD et 30 patients ont été traités par Paxlovid. Les sollicitations de la cellule dans cette indication émanaient le plus souvent de médecins généralistes. Aucun effet indésirable grave n’a été observé.

Conclusion

La coordination régionale pour l’aide au traitement par anticorps monoclonaux et antiviraux est utile pour faciliter la prescription de ces traitements. Le suivi prospectif confirme leur tolérance très satisfaisante. Cette coordination a également permis d’évaluer les difficultés rencontrées par les médecins généralistes, en partie liées au caractère innovant, aux difficultés logistiques ou aux contraintes administratives de ces traitements.

Synthetic Biology: Bottom-Up Assembly of Molecular Systems

The bottom-up assembly of biological and chemical components opens exciting opportunities to engineer artificial vesicular systems for applications with previously unmet requirements. The modular combination of scaffolds and functional building blocks enables the engineering of complex systems with biomimetic or new-to-nature functionalities. Inspired by the compartmentalized organization of cells and organelles, lipid or polymer vesicles are widely used as model membrane systems to investigate the translocation of solutes and the transduction of signals by membrane proteins. The bottom-up assembly and functionalization of such artificial compartments enables full control over their composition and can thus provide specifically optimized environments for synthetic biological processes. This review aims to inspire future endeavors by providing a diverse toolbox of molecular modules, engineering methodologies, and different approaches to assemble artificial vesicular systems. Important technical and practical aspects are addressed and selected applications are presented, highlighting particular achievements and limitations of the bottom-up approach. Complementing the cutting-edge technological achievements, fundamental aspects are also discussed to cater to the inherently diverse background of the target audience, which results from the interdisciplinary nature of synthetic biology. The engineering of proteins as functional modules and the use of lipids and block copolymers as scaffold modules for the assembly of functionalized vesicular systems are explored in detail. Particular emphasis is placed on ensuring the controlled assembly of these components into increasingly complex vesicular systems. Finally, all descriptions are presented in the greater context of engineering valuable synthetic biological systems for applications in biocatalysis, biosensing, bioremediation, or targeted drug delivery.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, full version]

BACKGROUND

Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated.

METHODS

Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale.

RESULTS

After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, short version]

BACKGROUND

Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated.

METHODS

Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale.

RESULTS

After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

Engineering and Production of the Light-Driven Proton Pump Bacteriorhodopsin in 2D Crystals for Basic Research and Applied Technologies

The light-driven proton pump bacteriorhodopsin (BR) from the extreme halophilic archaeon Halobacterium salinarum is a retinal-binding protein, which forms highly ordered and thermally stable 2D crystals in native membranes (termed purple membranes). BR and purple membranes (PMs) have been and are still being intensively studied by numerous researchers from different scientific disciplines. Furthermore, PMs are being successfully used in new, emerging technologies such as bioelectronics and bionanotechnology. Most published studies used the wild-type form of BR, because of the intrinsic difficulty to produce genetically modified versions in purple membranes homologously. However, modification and engineering is crucial for studies in basic research and, in particular, to tailor BR for specific applications in applied sciences. We present an extensive and detailed protocol ranging from the genetic modification and cultivation of H. salinarum to the isolation, and biochemical, biophysical and functional characterization of BR and purple membranes. Pitfalls and problems of the homologous expression of BR versions in H. salinarum are discussed and possible solutions presented. The protocol is intended to facilitate the access to genetically modified BR versions for researchers of different scientific disciplines, thus increasing the application of this versatile biomaterial.

Cryo-electron microscopic and X-ray crystallographic analysis of the light-driven proton pump proteorhodopsin reveals a pentameric assembly

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Affinity tag-free isolation of proteorhodopsin (PR) by ion exchange and size exclusion chromatography.

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Biochemical and computational analysis indicate a single, pentameric PR population.

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Highly pure and homogeneous PR enables growth of 3D crystals.

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X-ray crystallography and cryo-electron microscopy reveal pentameric assembly of PR.

The green-light absorbing proteorhodopsin (GPR) is the prototype of bacterial light-driven proton pumps. It has been the focus of continuous research since its discovery 20 years ago and has sparked the development and application of various biophysical techniques. However, a certain controversy and ambiguity about the oligomeric assembly of GPR still remains. We present here the first tag-free purification of pentameric GPR. The combination of ion exchange and size exclusion chromatography yields homogeneous and highly pure untagged pentamers from GPR overexpressing Escherichia coli. The presented purification procedure provides native-like protein and excludes the need for affinity purification tags. Importantly, three-dimensional protein crystals of GPR were successfully grown and analyzed by X-ray crystallography. These results together with data from single particle cryo-electron microscopy provide direct evidence for the pentameric stoichiometry of purified GPR.

[Effect of surgery of pulmonary cysts related to immunoglobulin light chain deposits]

INTRODUCTION

Light chain deposition disease is a rare anatomo-clinical disorder, which rarely leads to cystic lung destruction.

CASE REPORT

We report the case of a 62years old female patient with a history of a monoclonal gammopathy of unknown significance who developed progressive dyspnea. Thoracic CT-scan demonstrated a diffuse pulmonary cystic disorder with predominance in the right lower lobe. Thoracoscopic surgical resection of that lobe led to a diagnosis of non-amyloid kappa light chain deposits. Surgery also resulted in a lung volume reduction effect with clinical and functional benefits related to improved ventilation of adjacent segments.

CONCLUSION

This report of pulmonary cystic disorder related to a light chain deposition disease highlights the potential clinical and functional benefits observed after lung volume reduction surgery.

Purification of Membrane Proteins by Affinity Chromatography with On-Column Protease Cleavage

A protocol is described for the isolation of recombinant polyhistidine-tagged membrane proteins from overexpressing Escherichia coli cells. The gene encoding a target membrane protein is cloned into an expression plasmid and then introduced into E. coli cells for overexpression. Membranes from bacterial cells are isolated and the tagged target membrane protein is solubilized in detergent and subsequently bound to an affinity matrix. Tagged proteins are commonly eluted by an excess of a solute that competes for the binding to the matrix. Alternatively, amino acid sequence-specific proteases can be used to cleave off the affinity purification tag directly on the purification column (i.e., on-column cleavage). This selectively releases the target protein and allows subsequent elution. Importantly, this step represents an additional purification step and can significantly increase the purity of the isolated protein.

Blood CD9+ B cell, a biomarker of bronchiolitis obliterans syndrome after lung transplantation

Bronchiolitis obliterans syndrome is the main limitation for long-term survival after lung transplantation. Some specific B cell populations are associated with long-term graft acceptance. We aimed to monitor the B cell profile during early development of bronchiolitis obliterans syndrome after lung transplantation. The B cell longitudinal profile was analyzed in peripheral blood mononuclear cells from patients with bronchiolitis obliterans syndrome and patients who remained stable over 3 years of follow-up. CD24^hi CD38^hi transitional B cells were increased in stable patients only, and reached a peak 24 months after transplantation, whereas they remained unchanged in patients who developed a bronchiolitis obliterans syndrome. These CD24^hi CD38^hi transitional B cells specifically secrete IL-10 and express CD9. Thus, patients with a total CD9⁺ B cell frequency below 6.6% displayed significantly higher incidence of bronchiolitis obliterans syndrome (AUC = 0.836, PPV = 0.75, NPV = 1). These data are the first to associate IL-10-secreting CD24^hi CD38^hi transitional B cells expressing CD9 with better allograft outcome in lung transplant recipients. CD9-expressing B cells appear as a contributor to a favorable environment essential for the maintenance of long-term stable graft function and as a new predictive biomarker of bronchiolitis obliterans syndrome-free survival.

Acute Cardiac Failure Due to Takotsubo Cardiomyopathy Secondary to a Phone Call for Lung Transplantation: A Case Report

Lung transplantation is a therapeutic option for certain end-stage lung diseases. The phone call for lung transplantation is a major event in the life of these patients; as a result, it can generate significant stress. We herein present the case of a 58-year-old female patient with end-stage chronic obstructive pulmonary disease (COPD) who, while on the lung transplantation waiting list, received such a call. Complete transplant work-up, including cardiac tests undertaken shortly before, had revealed no contraindication to lung transplantation. She was admitted with severe acute respiratory failure, and her extensive work-up was compatible with pulmonary edema due to takotsubo cardiomyopathy. The lung transplantation was thus cancelled, owing to the patient's health condition and the poor quality of the graft as well. The patient stayed in the intensive care unit for several days, requiring noninvasive ventilation. The left ventricular function recovered completely within 10 days postdiagnosis, and the patient was discharged 13 days after her admission. The patient was transplanted 1 month thereafter, without any particular problems; she is currently, 8 months post-transplantation, in good condition. In the given case, the call for lung transplantation could have generated emotional stress severe enough to lead to takotsubo cardiomyopathy.

Directed Insertion of Light-Activated Proteorhodopsin into Asymmetric Polymersomes from an ABC Block Copolymer

Nanoscopic artificial vesicles containing functional protein transporters are fundamental for synthetic biology. Energy-providing modules, such as proton pumps, are a basis for simple nanoreactors. We report on the first insertion of a functional transmembrane protein into asymmetric polymersomes from an ABC triblock copolymer. The polymer with the composition poly(ethylene glycol)-poly(diisopropylaminoethyl methacrylate)-poly(styrenesulfonate) (PEG-PDPA-PSS) was synthesized by sequential controlled radical polymerization. PEG and PSS are two distinctively different hydrophilic blocks, allowing for a specific orientation of our protein, the light-activated proton pump proteorhodopsin (PR), into the final proteopolymersome. A very interesting aspect of the PEG-PDPA-PSS triblock copolymers is that it allowed for simultaneous vesicle formation and oriented insertion of PR simply by adjusting the pH. The intrinsic positive charge of PR's intracellular surface was enhanced by a His-tag, which aligns readily with the negative charges of the PSS on the outside of the polymersomes. The directed insertion of PR was confirmed by a light-dependent pH change of the proteopolymersome solution, indicating the intended orientation. We have hereby demonstrated the first successful oriented insertion of a proton pump into an artificial asymmetric membrane.

Design and assembly of a chemically switchable and fluorescently traceable light-driven proton pump system for bionanotechnological applications

Energy-supplying modules are essential building blocks for the assembly of functional multicomponent nanoreactors in synthetic biology. Proteorhodopsin, a light-driven proton pump, is an ideal candidate to provide the required energy in form of an electrochemical proton gradient. Here we present an advanced proteoliposome system equipped with a chemically on-off switchable proteorhodopsin variant. The proton pump was engineered to optimize the specificity and efficiency of chemical deactivation and reactivation. To optically track and characterize the proteoliposome system using fluorescence microscopy and nanoparticle tracking analysis, fluorescenlty labelled lipids were implemented. Fluorescence is a highly valuable feature that enables detection and tracking of nanoreactors in complex media. Cryo-transmission electron microscopy, and correlative atomic force and confocal microscopy revealed that our procedure yields polylamellar proteoliposomes, which exhibit enhanced mechanical stability. The combination of these features makes the presented energizing system a promising foundation for the engineering of complex nanoreactors.

Fusion Domains Guide the Oriented Insertion of Light-Driven Proton Pumps into Liposomes

One major objective of synthetic biology is the bottom-up assembly of minimalistic nanocells consisting of lipid or polymer vesicles as architectural scaffolds and of membrane and soluble proteins as functional elements. However, there is no reliable method to orient membrane proteins reconstituted into vesicles. Here, we introduce a simple approach to orient the insertion of the light-driven proton pump proteorhodopsin (PR) into liposomes. To this end, we engineered red or green fluorescent proteins to the N- or C-terminus of PR, respectively. The fluorescent proteins optically identified the PR constructs and guided the insertion of PR into liposomes with the unoccupied terminal end facing inward. Using the PR constructs, we generated proton gradients across the vesicle membrane along predefined directions such as are required to power (bio)chemical processes in nanocells. Our approach may be adapted to direct the insertion of other membrane proteins into vesicles.

Purification of Human and Mammalian Membrane Proteins Expressed in Xenopus laevis Frog Oocytes for Structural Studies

This protocol describes the isolation of recombinant human and mammalian membrane proteins expressed in Xenopus laevis frog oocytes for structural studies. The cDNA-derived cRNA of the desired genes is injected into several hundreds of oocytes, which are incubated for several days to allow protein expression. Recombinant proteins are then purified via affinity chromatography. The novelty of this method comes from the design of a plasmid that produces multi-tagged proteins and, most importantly, the development of a protocol for efficiently discarding lipids, phospholipids, and lipoproteins from the oocyte egg yolk, which represent the major contaminants in protein purifications. Thus, the high protein purity and good yield obtained from this method allows protein structure determination by transmission electron microscopy of single detergent-solubilized protein particles and of 2D crystals of membrane protein embedded in lipid bilayers. Additionally, a radiotracer assay for functional analysis of the expressed target proteins in oocytes is described. Overall, this method is a valuable option for structural studies of mammalian and particularly human proteins, for which other expression systems often fail.

Engineering a Chemical Switch into the Light-driven Proton Pump Proteorhodopsin by Cysteine Mutagenesis and Thiol Modification

For applications in synthetic biology, for example, the bottom-up assembly of biomolecular nanofactories, modules of specific and controllable functionalities are essential. Of fundamental importance in such systems are energizing modules, which are able to establish an electrochemical gradient across a vesicular membrane as an energy source for powering other modules. Light-driven proton pumps like proteorhodopsin (PR) are excellent candidates for efficient energy conversion. We have extended the versatility of PR by implementing an on/off switch based on reversible chemical modification of a site-specifically introduced cysteine residue. The position of this cysteine residue in PR was identified by structure-based cysteine mutagenesis combined with a proton-pumping assay using E. coli cells overexpressing PR and PR proteoliposomes. The identified PR mutant represents the first light-driven proton pump that can be chemically switched on/off depending on the requirements of the molecular system.

Clinical usefulness of oral immunoglobulins in lung transplant recipients with norovirus gastroenteritis: a case series

Viral gastroenteritis causing diarrhea is a common complication observed in lung transplant recipients. Differently from the mild and typically self-limited disease seen in immunocompetent subjects, immunocompromised patients frequently have a more severe course. Norovirus and rotavirus are among the leading causes of severe gastroenteritis in transplant recipients. Specific treatment is unavailable, although good supportive treatment can significantly reduce morbidity. Previous studies have suggested that oral immunoglobulins may be used for the treatment of acute viral gastroenteritis after solid-organ transplantation. Herein, we conducted a retrospective chart review of 12 lung transplant recipients with norovirus-induced gastroenteritis who were treated with oral immunoglobulins for 2 days. Eleven patients were successfully treated, whereas 1 subject was only mildly improved. Four patients had at least 1 recurrence. No significant adverse effects were observed. We conclude that oral immunoglobulins may be clinically useful for lung transplant recipients with norovirus-induced gastroenteritis.

[The Overlap Syndrome: association of COPD and Obstructive Sleep Apnoea]

Chronic obstructive pulmonary disease (COPD) and the obstructive sleep apnoea-hypopnoea syndrome (OSAHS) are both common diseases affecting respectively 10 and 5% of the adult population over 40 years of age. Their coexistence, which is denominated "Overlap Syndrome", can be expected to occur in about 0.5% of this population. Two recent epidemiologic studies have shown that the prevalence of OSAHS is not higher in COPD than in the general population, and that the coexistence of the two conditions is due to chance and not through a pathophysiological linkage. Patients with "overlap" have a higher risk of sleep-related O(2) desaturation than do patients with COPD alone and the same degree of bronchial obstruction. They have an increased risk of developing hypercapnic respiratory failure and pulmonary hypertension when compared with patients with OSAHS alone and with patients with "usual" COPD. In patients with overlap, hypoxaemia, hypercapnia, and pulmonary hypertension can be observed in the presence of mild to moderate bronchial obstruction, which is different from "usual" COPD. Treatment of the overlap syndrome consists of nasal continuous positive airway pressure or nocturnal non-invasive ventilation (NIV), with or without nocturnal O(2). Patients who are markedly hypoxaemic during the daytime (PaO(2)<55-60 mmHg) should be given conventional long-term O(2) therapy in addition to nocturnal ventilation.