Systemic lupus erythematosus : study of the intestinal microbiota and therapeutic issues

Le lupus érythémateux systémique (LES) est une maladie auto-immune complexe et non-curative. Son traitement repose sur l’association d’une corticothérapie et des immunosuppresseurs avec des effets indésirables graves. La recherche de nouvelles stratégies thérapeutiques constitue donc un enjeu de santé majeur. L’objectif principal de cette thèse est l’amélioration de la prise en charge thérapeutique du LES. D'abord, le microbiote intestinal en tant que cible innovante potentielle a été étudié. Un protocole reproductible a été mis en place, en standardisant la phase de stabilisation de l’échantillon fécal afin d’assurer la fiabilité des analyses. Une étude longitudinale du microbiote intestinal a montré que les patients LES se classent en deux clusters en fonction de leur dysbiose et en corrélation avec le score SLEDAI de l’activité de la maladie. Un panel de biomarqueurs bactériens spécifiques du LES et de son activité a été mis en évidence et pourrait être utilisé comme outil pertinent de pronostic et cible de nouvelles thérapeutiques originales. Ensuite, le potentiel prédictif d'atteinte glomérulaire du CD11b et du CD163, deux marqueurs de macrophages a été analysé. Seul le CD163 distinguait les patients actifs des non-actifs. Il était prédictif de l’atteinte glomérulaire inflammatoire ainsi que de la réponse au traitement. A terme, le CD163 pourrait être un biomarqueur non invasif utile au suivi des patients LES et NL. Finalement, l’efficacité in vivo d’une nouvelle molécule,GNS561,a été testée. Cette derrière possède des propriétés immunomodulatrices et anti-inflammatoires et pourrait être une nouvelle piste intéressante pour le traitement du LES.Systemic lupus erythematosus (SLE) is a complex non-curative auto-immune disease. Corticosteroids and immunosuppressants are part of the standard of care for SLE patients but can cause serious side effects. The development of new therapeutic strategies is therefore a major health issue. The main objective of this thesis is the improvement of the therapeutic management of SLE. Firstly, the gut microbiota as a potential innovative target for adjuvant therapies was studied. A reproductible protocol was elaborated, by identifying the technological bias linked to the sample handling thus validating the reliability of our gut microbiota analyses. Longitudinal study was performed and showed two clusters of SLE patients that correlated with the SLEDAI activity score. A new panel of human and murine bacterial biomarkers specific to SLE and its activity was identified that could eventually be used as relevant prognostic tools and could constitute new targets of therapeutic management of SLE patients. Then, the predictif value of the urinary CD11b and CD163, two macrophages markers, in glomerulonephritis was studied. Only CD163 can distinguish active from non-active LN and was predictive of inflammatory glomerular damage as well as the response of treatment. CD163 could become a useful non-invasive biomarker for monitoring SLE and LN patients. Finally, the efficacy in vivo of a new therapeutic molecule, GNS561, was tested.GNS561 showed here its potential immunomodulatory and anti-inflammatory properties. Therefore, GNS561 could become a novel approach for SLE treatment

Gut microbiota in SLE: from animal models to clinical evidence and pharmacological perspectives

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease driven by complex interactions between genetics and environmental factors. SLE is characterised by breaking self-immune tolerance and autoantibody production that triggers inflammation and damage of multiple organs. Given the highly heterogeneous nature of SLE, the treatments currently used are still not satisfactory with considerable side effects, and the development of new therapies is a major health issue for better patient management. In this context, mouse models significantly contribute to our knowledge of the pathogenesis of SLE and are an invaluable tool for testing novel therapeutic targets. Here, we discuss the role of the most used SLE mouse models and their contribution to therapeutic improvement. Considering the complexity of developing targeted therapies for SLE, adjuvant therapies are also increasingly proposed. Indeed, murine and human studies have recently revealed that gut microbiota is a potential target and holds great promises for successful new SLE therapies. However, the mechanisms of gut microbiota dysbiosis in SLE remain unclear to date. In this review, we propose an inventory of existing studies investigating the relationship between gut microbiota dysbiosis and SLE to establish microbiome signature that may serve as a potential biomarker of the disease and its severity as well as a new potential therapy target. This approach may open new possibilities for early diagnosis, prevention and therapeutic perspectives of SLE based on gut microbiome

Gut microbiota in systemic lupus erythematosus patients and lupus mouse model: a cross species comparative analysis for biomarker discovery

International audienceAn increasing number of studies have provided strong evidence that gut microbiota interact with the immune system and stimulate various mechanisms involved in the pathogenesis of auto-immune diseases such as Systemic Lupus Erythematosus (SLE). Indeed, gut microbiota could be a source of diagnostic and prognostic biomarkers but also hold the promise to discover novel therapeutic strategies. Thus far, specific SLE microbial signatures have not yet been clearly identified with alteration patterns that may vary between human and animal studies. In this study, a comparative analysis of a clinically well-characterized cohort of adult patients with SLE showed reduced biodiversity, a lower Firmicutes/Bacteroidetes ( F/B ) ratio, and six differentially abundant taxa compared with healthy controls. An unsupervised clustering of patients with SLE patients identified a subgroup of patients with a stronger alteration of their gut microbiota. Interestingly, this clustering was strongly correlated with the disease activity assessed with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score ( p = 0.03 , odd ratio = 15) and the identification of specific alterations involving the F/B ratio and some different taxa. Then, the gut microbiota of pristane-induced lupus and control mice were analyzed for comparison with our human data. Among the six differentially abundant taxa of the human disease signature, five were common with our murine model. Finally, an exhaustive cross-species comparison between our data and previous human and murine SLE studies revealed a core-set of gut microbiome species that might constitute biomarker panels relevant for future validation studies

Gut microbiota in systemic lupus erythematosus patients and lupus mouse model: a cross species comparative analysis for biomarker discovery

International audienceAn increasing number of studies have provided strong evidence that gut microbiota interact with the immune system and stimulate various mechanisms involved in the pathogenesis of auto-immune diseases such as Systemic Lupus Erythematosus (SLE). Indeed, gut microbiota could be a source of diagnostic and prognostic biomarkers but also hold the promise to discover novel therapeutic strategies. Thus far, specific SLE microbial signatures have not yet been clearly identified with alteration patterns that may vary between human and animal studies. In this study, a comparative analysis of a clinically well-characterized cohort of adult patients with SLE showed reduced biodiversity, a lower Firmicutes/Bacteroidetes ( F/B ) ratio, and six differentially abundant taxa compared with healthy controls. An unsupervised clustering of patients with SLE patients identified a subgroup of patients with a stronger alteration of their gut microbiota. Interestingly, this clustering was strongly correlated with the disease activity assessed with the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score ( p = 0.03 , odd ratio = 15) and the identification of specific alterations involving the F/B ratio and some different taxa. Then, the gut microbiota of pristane-induced lupus and control mice were analyzed for comparison with our human data. Among the six differentially abundant taxa of the human disease signature, five were common with our murine model. Finally, an exhaustive cross-species comparison between our data and previous human and murine SLE studies revealed a core-set of gut microbiome species that might constitute biomarker panels relevant for future validation studies

Human Stool Preservation Impacts Taxonomic Profiles in 16S Metagenomics Studies

International audienceMicrobiotas play critical roles in human health, yet in most cases scientists lack standardized and reproducible methods from collection and preservation of samples, as well as the choice of omic analysis, up to the data processing. To date, stool sample preservation remains a source of technological bias in metagenomic sequencing, despite newly developed storage solutions. Here, we conducted a comparative study of 10 storage methods for human stool over a 14-day period of storage at fluctuating temperatures. We first compared the performance of each stabilizer with observed bacterial composition variation within the same specimen. Then, we identified the nature of the observed variations to determine which bacterial populations were more impacted by the stabilizer. We found that DNA stabilizers display various stabilizing efficacies and affect the recovered bacterial profiles thus highlighting that some solutions are more performant in preserving the true gut microbial community. Furthermore, our results showed that the bias associated with the stabilizers can be linked to the phenotypical traits of the bacterial populations present in the studied samples. Although newly developed storage solutions have improved our capacity to stabilize stool microbial content over time, they are nevertheless not devoid of biases hence requiring the implantation of standard operating procedures. Acknowledging the biases and limitations of the implemented method is key to better interpret and support true associated microbiome patterns that will then lead us towards personalized medicine, in which the microbiota profile could constitute a reliable tool for clinical practice

Resource utilization and preparedness within the COVID-19 pandemic in Tunisian medical intensive care units: A nationwide retrospective multicentre observational study

Background: The worldwide SARS-CoV-2 pandemic represents the most recent global healthcare crisis. While all healthcare systems suffered facing the immense burden of critically-ill COVID-19 patients, the levels of preparedness and adaptability differed highly between countries. Aim: to describe resource mobilization throughout the COVID-19 waves in Tunisian University Medical Intensive Care Units (MICUs) and to identify discrepancies in preparedness between the provided and required resource. Methods: This is a longitudinal retrospective multicentre observational study conducted between March 2020 and May 2022 analyzing data from eight University MICUs. Data were collected at baseline and at each bed expansion period in relation to the nation’s four COVID-19 waves. Data collected included epidemiological, organizational and management trends and outcomes of COVID-19 and non-COVID-19 admissions. Results: MICU-beds increased from 66 to a maximum of 117 beds. This was possible thanks to equipping pre-existing non-functional MICU beds (n = 20) and creating surge ICU-beds in medical wards (n = 24). MICU nurses increased from 53 to 200 of which 99 non-ICU nurses, by deployment from other departments and temporary recruitment. The nurse-to-MICU-bed ratio increased from 1:1 to around 1·8:1. Only 55% of beds were single rooms, 80% were equipped with ICU ventilators. These MICUs managed to admit a total of 3368 critically-ill patients (15% of hospital admissions). 33·2% of COVID-19-related intra-hospital deaths occurred within the MICUs. Conclusion: Despite a substantial increase in resource mobilization during the COVID-19 pandemic, the current study identified significant persisting discrepancies between supplied and required resource, at least partially explaining the poor overall prognosis of critically-ill COVID-19 patients