Activation de la voie alterne du complément dans les formes sévères de COVID-19

Introduction

Le SARS-CoV-2 est désormais responsable de plus de 4 millions de décès dans le monde. Les formes sévères de COVID-19 sont caractérisées par un état d’hyperinflammation, et l’utilisation de la corticothérapie a réduit significativement la mortalité. Des thérapies complémentaires plus spécifiques pourraient permettre d’améliorer la prise en charge des patients présentant des formes sévères. Dans ce contexte, les voies de signalisation en lien avec le système du complément semblent etre une cible idéale : on retrouve une surreprésentation des voies du compléments dans les cellules épithéliales pulmonaires, une élévation des marqueurs d’activation de la cascade du complément dans le plasma des patients atteints de COVID-19, et des déficits congénitaux dans les protéines de régulation du complément ont été associées à des formes plus sévères de la maladie. Cependant, nos connaissances des voies spécifiques activées du complément et leur lien avec la sévérité de la maladie restent limitées.

Patients et méthodes

Durant la première vague épidémique en France, nous avons recueilli les prélèvements de 32 patients COVID-19 présentant des niveaux de sévérité différents de la maladie. Nous avons déterminé l’expression ARN de 28 gènes du système du complément et les concentrations sériques de 6 protéines, représentant les trois voies du complément.

Résultats

L’expression des gènes du complément étaient régulées de façon différentielle selon la gravité de la COVID-19 : alors que la voie classique était activée chez tous les patients infectés, la forme sévère de la maladie était associée à une suractivation de la voie de la lectine et de la voie alterne, dont l’expression corrélait avec les marqueurs de l’inflammation et de coagulation. De plus, la properdine, régulateur positif majeur de la voie alterne, était exprimé à des niveaux élevés (ARN) chez les patients les plus graves, tandis que leurs niveaux protéiques étaient diminués, suggérant une consommation importante et la déposition au niveau des sites de l’activation du complément. De façon intéressante, les concentrations sériques basses de properdine étaient significativement associées au recours à la ventilation mécanique.

Conclusion

Cette étude apporte un éclairage sur le rôle potentiel de la voie alterne du complément dans les formes graves de COVID-19. Bien que des études histologiques et mécanistiques ainsi qu’une confirmation de ces résultats sur une plus grande cohorte soient nécessaires, ces résultats sont en faveur d’essais ciblant la voie alterne du complément chez les patients présentant des formes sévères de COVID-19.

[Aspergillus-related respiratory conditions and COPD: Diagnostic challenges]

INTRODUCTION

The relations between chronic obstructive pulmonary disease (COPD) and respiratory diseases due to Aspergillus spp. are not well understood.

METHODS

We analysed a retrospective series of patients hospitalized with a diagnosis of COPD and respiratory disease due to Aspergillus. Patients were identified between 2010 and 2015 from the medico-administrative database of Cochin hospital, Paris. Historical, clinical, biological, microbiological and imaging data were collected and described. Diagnoses were reclassified based on reference definitions and classifications from the literature. Patients were classified according to the type of Aspergillus-related diseases and risk factors were described.

RESULTS

Forty patients were identified. Classifiable Aspergillus-related respiratory conditions were confirmed in 26 of them including 12 allergic bronchopulmonary aspergillosis (ABPA), 8 chronic pulmonary aspergillosis (CPA), 1 invasive pulmonary aspergillosis (IPA) and 3 diagnostic associations ABPA/CPA. Other respiratory comorbidities were present in all cases of CPA and immunodepression was recorded for semi-invasive and invasive forms. Finally, 16 patients could not be classified, among whom Aspergillus related lung disease was considered as likely in one-half.

CONCLUSION

The complexity of the diagnosis of pulmonary aspergillosis is related to its multiple types with sometimes unclear distinctions. Any type of pulmonary aspergillosis can be observed in patients with COPD, depending on associated risks factors. It would be helpful to establish specific classifications adapted to patients with COPD. This will require larger, prospective, multicentre studies.

[Parosteal sarcoma of the radius in the course of etretinate therapy]

A parosteal osteosarcoma of the right radius has developed in a patient treated for a long time by etretinate (total dose: 73 g). If brachial ossifications have been reported to etretinate in 2 cases, they were benign tumours; so coincidence is possible in our case. Nevertheless, a relation between the tumour and the treatment cannot be excluded and justify the report of this observation.

[Ionized fluorine in the plasma and urine of subjects treated with organofluorine drugs prescribed in rheumatology]

The elimination of ionized urinary fluorine was studied in groups of eight subjects treated during several days with niflumic acid, flufenamic acid, sulindac, antrafenine and floctafenine. Sulindac and floctafenine do not changes this elimination. After administration of niflumic acid, flufenamic and antrafenine, the urinary elimination of ionized fluorine increase in all the subjects. This increase is manifested from the start of treatment and persists for several days after it has been stopped. The administration of three drugs also results in an elevated level of ionized plasmic fluorine the duration of treatment. The results prove the existence in the human organism of a metabolic process capable of effecting the ionization of the organic fluor contained in the drugs studied. This biotransformation causes a fluorine impregnation of endogenous origin that is permanent and relatively stable, and whose consequences are examined (risk of fluorine osteosis and possibility of therapeutic application).

[Fluorine osteosis caused by a very long-term niflumic acid treatment in 2 cases of rheumatoid arthritis]

An osteosclerosis opacifying the axial skeleton and affecting in particular all of the spine, was observed in two women aged 75 and 42 years who had been suffering from a rheumatoid arthritis developing between 15 and 26 years. It was traced to a chronic fluorine intoxication, stemming from the regular taking, for 10 years and 8 1/2 years, of a non cortisone, anti-inflammatory niflumic acid. This fluorine product has 3 atoms of fluor in its molecule (50.0 mg for a tablet of 250 mg). Its administration to control subjects proved the production of ionized fluor by way of the metabolism, and the accumulation of fluor in the organism. Rheumatoid polyarthritis and the prolonged corticotherapy (10 mg of prednisone per day for 21 years) cannot be dismissed as the origin of the severe demineralization of the limbs observed in the second patient, but the role of fluorine seems marked in the occurrence of this peripheral involvement with problems of mineralization and secondary hyperparathyroidisms. On the other hand, the absence of an intervertebral narrowing in the 2 patients, despite the very prolonged taking of cortisone (5 mg of prednisone per day for 15 years, for the 75-year-old patient) is perhaps a result of the fluorine.