Neutrophils play a key role in the initiation of glomerular hematuria in a postinfectious igan experimental model

2 p.BACKGROUND AND AIMS: Hematuria is a common finding in patients with IgA nephropathy (IgAN), occurring mainly after upper respiratory tract infections.Hematuria can lead to acute kidney injury and chronic loss of renal function in IgAN.However, the mechanisms involved in egression of erythrocytes from the glomerular capillaries into the urinary space are unknown. To answer this question, we developed an infection with Streptococcus pneumoniae (SP) in a humanized experimental IgAN model (a1KICD89tg mice) that resembles the pathological and clinical findings of disease (IgA1 and soluble CD89 mesangial deposits, complement activation,proteinuria and hematuria).METHOD: a1KICD89tg mice (12 weeks old) received an intranasal instillation of SP(107 bacteria). Blood, urine and renal samples were obtained during 1 month after induction of respiratory infection. The presence of SP in lungs from these mice was confirmed by microbiological analysis. Hematuria was quantified in the urinary sediment and renal function was determined by biochemical analysis. Renal histological characteristics were evaluated by hematoxylin/eosin, masson’s trichrome and PAS staining. IgA glomerular deposits, activation of complement system and infiltration of proinflammatory cells was examined by immunohistochemistry or immunofluorescence. Circulating leukocyte populations were studied on a hemocytometer. Renal inflammatory cytokines, metalloproteases, as well as markers of tubular and glomerular damage were determined in kidneys by RT-PCR and western-blot. To further validate the role of neutrophils in this pathological setting, we selective depleted these cells through a single injection of anti-Ly6G mAb (200 mg/kg i.p).RESULTS: SP-intranasal instillation in a1KICD89tg mice increased hematuria,microalbuminuria and proteinuria, peaking at 48h after induction of the respiratory infection. SP instillation caused disruption of the glomerular basement membrane,with decreased expression of the slit diaphragm proteins nephrin and synaptopodin, as well as higher glomerular accumulation of IgA and proteins of complement system (C3, MBL). Hematuria intensity was positively correlated with the presence of interstitial F4/80þ macrophages, matrix metalloproteinase 9 (MMP-9), inflammatory cytokines and chemokines (IL-1b, IL-6, TNF-a, CCL-2, CCL5 and CX3CL1/CX3CR1) as well as p65 NF-jB activation. Hematuria was negatively correlated with anti inflammatory IL-10 mRNA expression, Factor H levels and collagen IV content. Notably, SP infection induced expression of the tubular injury markers N-GAL andKIM-1. Increased peripheral neutrophils levels were observed in the SP-infected a1KICD89tg mice. Mechanistically, anti-Ly6G-mediated neutrophil depletion reduced SP-mediated hematuria, proteinuria and albuminuria, prevented loss of synaptopodin and nephrin, decreased renal inflammation and MMP-9 expression in a1KICD89tg mice.CONCLUSION: In a humanized mouse model of IgAN, hematuria bouts following respiratory tract infections are caused by a neutrophil-mediated alteration of the glomerular filtration barrier (podocyte damage, complement deposits and loss of Collagen IV). These findings may help to unveil novel potential therapeutic approaches to combat one of the key elements in the progression of IgAN and related conditions.Peer reviewe

Who is the killer during sepsis ? : Inflammation or bacterial proliferation ?

Le sepsis est un problème majeur de santé publique. En effet, en 2017, la mortalité qui lui est imputable était estimée à près de 50 millions d'individus dans le monde. Mais qu'est-ce que le sepsis ? En 2016, il a été redéfini comme un « état de dysfonction d'organe mettant en jeu le pronostic vital secondaire à une dérégulation de la réponse immune à une infection». De fait, cette définition met en avant une vision immunologique du sepsis. Or, les différents traitements visant à réduire la réponse inflammatoire n'ont jamais prouvé d'efficacité en termes de survie. De plus, cette vision s'oppose à celle des pères fondateurs de l'immunologie, tels Ehrlich et Metchnikoff, qui avaient une approche bactériologique du sepsis constatant que les bactéries présentaient des facteurs de virulence importants. Ainsi, le but de cette thèse est de tenter de comprendre le déterminant le plus important dans la mortalité liée au sepsis, entre la prolifération bactérienne et la réponse inflammatoire. Une première étude à consister à évaluer le rôle de l'interaction directe du récepteur de type I à la partie constante des immunoglobulines de type A (IgA), ou CD89, avec les bactéries. En 2007, notre laboratoire de recherche avait montré que le récepteur de type III à la partie constante des immunoglobulines de type G (IgG) pouvait lier directement les bactéries sans l'intermédiaire d'IgG. Tout d'abord, nous avons montré que ce résultat était généralisable au récepteur CD89 qui lie directement, sans IgA, des bactéries telles E.coli et S.pneumoniae. Puis, ce récepteur pouvant induire deux signaux opposés, nous avons cherché à savoir si cette liaison induisait un signal pro-inflammatoire (ITAMa) ou un signal anti-inflammatoire (ITAMi). Les résultats obtenus in vitro étaient en faveur de l'induction d'un signal ITAMa, par l'interaction CD89-bactérie, avec une augmentation de la phagocytose, de la production de dérivés réactifs de l¿oxygène et de cytokines. Ensuite, nous avons montré que ces résultats étaient généralisables à l'homme, en utilisant des monocytes humains issus de patients présentant un déficit en IgG et IgA. Enfin, nous avons évalué les effets in vivo de l'interaction CD89-bactérie en utilisant des souris transgéniques pour le récepteur CD89 (les souris sauvages n'exprimant pas ce récepteur). Dans un modèle de péritonite pluribactérienne et dans un modèle de pneumopathie à S.pneumoniae, nous avons une augmentation de la réponse inflammatoire et de la clairance bactérienne à 6 heures post-infection qui étaient associées à une meilleure survie des souris transgéniques pour le récepteur CD89 comparées aux souris WT. Dans une seconde étude, la réponse inflammatoire semblant protectrice, nous avons cherché à comparer la réponse inflammatoire à la prolifération bactérienne dans des modèles de péritonites murines, différents selon : la taille de ligature du caecum, la présence d'une ponction de ce dernier et l'utilisation d'antibiotiques. Nous avons retrouvé une très forte association entre la mortalité et la prolifération bactérienne. En effet, la présence d'antibiotique améliorait la survie sans modification importante de la réponse inflammatoire. De plus, la présence d'une ligature et d'une ponction importante du caecum entrainaient une mortalité extrêmement rapide avec une prolifération bactérienne majeure et une faible production de cytokines. Puis, en cherchant à modéliser la réponse inflammatoire, nous avons montré que la production de cytokines était très associée à la quantité de bactéries, allant ainsi à l'encontre de l'hypothèse d'une dérégulation. Enfin, la quantité de bactéries était le paramètre le plus fortement associé à la dysfonction d'organes comme le rein ou le foie ; les cytokines ayant une relation logarithmique avec les paramètres biologiques. Par conséquent, l'ensemble de ces résultats est en faveur du rôle protecteur de la réponse inflammatoire et du rôle délétère de la prolifération bactérieIn 2017, the estimated sepsis mortality was nearly 50 million people worldwide, making sepsis a major public health problem. But what is sepsis? In 20167, sepsis was redefined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. This definition of sepsis refers to an immunological view of sepsis. However, all treatments that aimed at reducing the inflammatory response had never improved patient survival. This view is different of the one of the founding fathers of immunology such as Ehrlich or Metchnikoff who had a bacteriological view of sepsis based on bacteria virulence factors. The aim of this thesis is therefore to try to understand which determinant is the most important in sepsis mortality: bacterial proliferation or the inflammatory response. A first study evaluated the role of the direct interaction of the type I receptor of the constant part of type A immunoglobulins (IgA), or CD89, with bacteria. In 2007, our research laboratory showed that the constant part of type III receptor of type G immunoglobulins (IgG) could directly bind bacteria without the intermediary of IgG. We first showed that this result could be generalized to the CD89 receptor which directly binds (without IgA) bacteria such as E.coli, S. pneumoniae. We then sought to know whether this binding induced a pro-inflammatory signal (ITAMa) or an anti-inflammatory signal (ITAMi), this receptor being able to induce both of these signals. Our in vitro results were in favor of the induction of an ITAMa signal by the CD89-bacteria interaction. This signal was associated with an increase in phagocytosis, production of reactive oxygen compounds and cytokines. We then showed that these results were generalizable to humans using human monocytes from patients with IgG and IgA deficiency. Finally, we evaluated the in vivo effects of the CD89-bacteria interaction using mice transgenic for the CD89 receptor (wild mice do not express this receptor). In a model of pluribacterial peritonitis and in a model of S. pneumoniae pneumonia, we found an increased survival of mice transgenic for the CD89 receptor compared to WT mice that was associated with an increase of the inflammatory response and bacterial clearance at 6 hours post infection. As a strong inflammatory response appears to be protective, we performed a second study evaluated which parameter was the most associate with outcome in different murine peritonitis models depending on the size of the caecum ligation, the presence of a puncture of the latter and the use of antibiotics. Thus we found a very strong association between mortality and bacterial proliferation. For example, the presence of antibiotic improved survival without significantly altering the inflammatory response, or the presence of heavy ligation and puncture of the caecum resulted in extremely rapid mortality with major bacterial proliferation but with low cytokine production. Secondly, we sought to model the inflammatory response and we showed that cytokine production was very associated with the amount of bacteria, which goes against deregulation. Finally, number of bacteria was the parameter the most associated with organ dysfunction such as kidney or liver, cytokines showing a logarithmic relationship with the biological parameters. All of these results support the protective role of the inflammatory response and the deleterious role of bacterial proliferatio

Impact of Antibiotic Prophylaxis on Surgical Site Infections in Cardiac Surgery

(1) Background: Cephalosporins (CA) are the first-line antibiotic prophylaxis recommended to prevent surgical site infection (SSI) after cardiac surgery. The combination of vancomycin/gentamicin (VGA) might represent a good alternative, but few studies have evaluated its efficacy in SSI prevention. (2) Methods: A single-centre retrospective study was conducted over a 13-year period in all consecutive adult patients undergoing elective cardiac surgery. Patients were stratified according to the type of antibiotic prophylaxis. CA served as the first-line prophylaxis, and VGA was used as the second-line prophylaxis. The primary endpoint was SSI occurrence at 90 days, which was defined as the need for reoperation due to SSI. (3) Results: In total, 14,960 adult patients treated consecutively from 2006 to 2019 were included in this study, of whom 1774 (12%) received VGA and 540 (3.7%) developed SSI. VGA patients had higher severity with increased 90-day mortality. Nevertheless, the frequency of SSI was similar between CA and VGA patients. However, the microbiological aetiologies were different, with more Gram-negative bacteria noted in the VGA group. (4) Conclusions: VGA seems to be as effective as CA in preventing SSI

Co–Ru/SiC impregnated with ethanol as an effective catalyst for the Fischer–Tropsch synthesis

International audienc

Ketamine restriction correlates with reduced cholestatic liver injury and improved outcomes in critically ill patients with burn injury.

BACKGROUND & AIMS: Ketamine-associated cholestatic liver injury is reported in patients with severe burn injury, but its association with patient outcome is unclear. We investigated the relationship between ketamine exposure, cholestatic liver injury, and outcome of critically ill patients with burn injury. METHODS: In a retrospective study, patients with severe burn injury were analysed across two periods: unrestricted ketamine prescription (ketamine-liberal) and capped ketamine dosage (ketamine-restricted). The primary endpoint was cholestatic liver injury, and the secondary endpoint was 3-month mortality. Binary logistic regression models and the revised electronic causality assessment method were used to measure the strength of associations and causality assessment, respectively. RESULTS: Of 279 patients (median age 51 [IQR 31-67] years; 63.1% men; burned surface area 28.5%, IQR 20-45%), 155 (56%) were in the ketamine-liberal group, and 124 (44%) were in the ketamine-restricted group, with comparable clinical characteristics, except for ketamine exposure (median doses 265.0 [IQR 0-8,021] mg and 20 [IQR 0-105] mg, respectively; p <0.001). A dose- and time-dependent relationship was observed between ketamine exposure and cholestatic liver injury. Ketamine restriction was associated with a reduced risk of cholestatic liver injury (adjusted odds ratio 0.16, 95% CI 0.04-0.50; p = 0.003) and with a higher probability of 3-month survival (p = 0.035). The revised electronic causality assessment method indicated that ketamine was probably and possibly the cause of cholestatic liver injury for 14 and 10 patients, respectively. Cholangitis was not observed in the ketamine-restricted group. In propensity-matched patients, the risk of 3-month mortality was higher (adjusted odds ratio 9.92, 95% CI 2.76-39.05; p = 0.001) in patients with cholestatic liver injury and ketamine exposure ≥10,000 mg. Other sedative drugs were not associated with liver and patient outcome. CONCLUSIONS: In this cohort, ketamine restriction was associated with less cholestatic liver injury and reduced 3-month mortality. IMPACT AND IMPLICATIONS: In a cohort of 279 critically ill patients with burn injury, ketamine was associated with a risk of liver bile duct toxicity. The risk was found to be dependent on both the dosage and duration of ketamine use. A restriction policy of ketamine prescription was associated with a risk reduction of liver injury and 3-month mortality. These findings have implications for the analgesia and sedation of critically ill patients with ketamine, with higher doses raising safety concerns

Prolonged mechanical ventilation after lung transplantation: risks factors and consequences on recipient outcome

BackgroundRisk factors and the incidence of prolonged mechanical ventilation (PMV) after lung transplantation (LT) have been poorly described. The study assessed predictive factors of PMV after LT.MethodsThis observational, retrospective, monocentric study included all patients who received LT in Bichat Claude Bernard Hospital between January 2016 and December 2020. PMV was defined as a duration of MV > 14 days. Independent risk factors for PMV were studied using multivariate analysis. One-year survival depending on PMV was studied using Kaplan Meier and log-rank tests. A p value <0.05 was defined as significant.Results224 LT recipients were analysed. 64 (28%) of them received PMV for a median duration of 34 [26–52] days versus 2 [1–3] days without PMV. Independent risk factors for PMV were higher body mass index (BMI) (p = 0.031), diabetes mellitus of the recipient (p = 0.039), ECMO support during surgery (p = 0.029) and intraoperative transfusion >5 red blood cell units (p < 0.001). Increased mortality rates were observed at one-year in recipients who received PMV (44% versus 15%, p < 0.001).ConclusionPMV was associated with increased morbidity and mortality one-year after LT. Preoperative risk factors (BMI and diabetes mellitus) must be considered when selecting and conditioning the recipients