Biology subjects

Pionneau, C.

Publications and source records attributed to Pionneau, C..

3 recordsLinked to original sources

bioRxiv2022

CARD9 in Neutrophils Protects from Colitis and Controls Mitochondrial Metabolism and Cell Survival

ObjectivesInflammatory bowel disease (IBD) results from a combination of genetic predisposition, dysbiosis of the gut microbiota and environmental factors, leading to alterations in the gastrointestinal immune response and chronic inflammation. Caspase recruitment domain 9 (Card9), one of the IBD susceptibility genes, has been shown to protect against intestinal inflammation and fungal infection. However, the cell types and mechanisms involved in the CARD9 protective role against inflammation remain unknown. DesignWe used dextran sulfate sodium (DSS)-induced and adoptive transfer colitis models in total and conditional CARD9 knock-out mice to uncover which cell types play a role in the CARD9 protective phenotype. The impact of Card9 deletion on neutrophil function was assessed by an in vivo model of fungal infection and various functional assays, including endpoint dilution assay, apoptosis assay by flow cytometry, proteomics and real time bioenergetic profile analysis (Seahorse). ResultsLymphocytes are not intrinsically involved in the CARD9 protective role against colitis. CARD9 expression in neutrophils, but not in epithelial or CD11c+ cells, protects against DSS-induced colitis. In the absence of CARD9, mitochondrial dysfunction in neutrophils leads to their premature death through apoptosis, especially in oxidative environment. The decrease of fonctional neutrophils in tissues could explain the impaired containment of fungi and increased susceptibility to intestinal inflammation. ConclusionThese results provide new insight into the role of CARD9 in neutrophil mitochondrial function and its involvement in intestinal inflammation, paving the way for new therapeutic strategies targeting neutrophils. Summary boxO_LIWhat is already known about this subject? O_LIInflammatory bowel disease (IBD) results from genetic predisposition, microbiota dysbiosis and environmental factors, but the alterations of the immune response leading to chronic intestinal inflammation are still not fully understood. C_LIO_LICaspase recruitment domain 9 (Card9), one of the IBD susceptibility genes, has been shown to protect against intestinal inflammation and fungal infection. C_LIO_LIHowever, the cell types and cellular mechanisms involved in the CARD9 protective role against inflammation remain unknown. C_LI C_LIO_LIWhat are the new findings? O_LICARD9 expression in neutrophils, but not in lymphocytes, epithelial cells or CD11c+ cells, protects against DSS-induced colitis. C_LIO_LIIn the absence of CARD9, mitochondrial dysfunction in neutrophils leads to their premature death through apoptosis, especially in oxidative environment. C_LIO_LIThe decrease of fonctional neutrophils in tissues could explain the impaired containment of fungi and increased susceptibility to intestinal inflammation. C_LI C_LIO_LIHow might it impact on clinical practice in the foreseeable future? O_LIThese results provide new insight into the role of CARD9 in neutrophil mitochondrial function and its involvement in intestinal inflammation. C_LIO_LIUnderstanding the role of neutrophils in chronic inflammation could lead to innovative therapeutic strategies targeting these key immune cells for various complex diseases. C_LI C_LI

immunology↗

bioRxiv2021

The Autophagy Receptor TAX1BP1 (T6BP) is a novel player in antigen presentation by MHC-II molecules.

CD4+ T lymphocytes play a major role in the establishment and maintenance of immunity. They are activated by antigenic peptides derived from extracellular or newly synthesized (endogenous) proteins presented on the surface of antigen presenting cells (APCs) by the MHC-II molecules. The pathways leading to endogenous MHC-II presentation remain poorly characterized. We demonstrate here that the autophagy receptor, T6BP, influences both autophagy-dependent and -independent endogenous presentation of HIV- and HCMV-derived peptides. By studying the immunopeptidome of MHC-II molecules, we show that T6BP affects both the quantity and quality of peptides presented. T6BP silencing induces the mislocalization of the MHC-II-loading compartments and a rapid degradation of the invariant chain (CD74) without altering the expression and internalization kinetics of MHC-II molecules. We determined the interactome of T6BP, identified calnexin as a T6BP partner and show that CANX cytosolic tail is required for this interaction. Remarkably, calnexin silencing replicates the functional consequences of T6BP silencing: decreased CD4+ T cell activation and exacerbated CD74 degradation. Altogether, we unravel T6BP as a key player of the MHC-II-restricted endogenous presentation pathway and we propose one potential mechanism of action.

immunology↗

bioRxiv2020

In-depth proteomic analysis of Plasmodium berghei sporozoites using trapped ion mobility spectrometry with parallel accumulation-serial fragmentation

Malaria is caused by Plasmodium spp. protozoan parasites, which are transmitted by female anopheline mosquitoes in the form of sporozoites. Once deposited in the dermis during the blood meal of the mosquito, sporozoites rapidly migrate to the liver for an initial and obligatory round of replication inside hepatocytes, before exponential multiplication of the parasite in the blood and onset of the malaria disease. Sporozoites and liver stages provide attractive targets for the development of a malaria vaccine. Until now, a single antigen from Plasmodium falciparum, the deadliest species infecting humans, has been considered for subunit vaccine clinical development, with limited success so far. This emphazises the need to identify novel targets. In this context, defining the parasite proteome is important not only to guide the down-selection of potential candidate antigens, but also to allow a better understanding of the parasite biology. Previous studies have determined the total proteome of sporozoite stages from the two main human malaria parasites, P. falciparum and P. vivax, as well as P. yoelii, a parasite that infects rodents. Another murine malaria parasite, P. berghei, has been widely used to investigate the biology of Plasmodium pre-erythrocytic stages. However, a deep view of the proteome of P. berghei sporozoites is still missing. To fill this gap, we took advantage of a novel highly sensitive timsTOF PRO mass spectrometer, based on trapped ion mobility spectrometry with parallel accumulation-serial fragmentation. Combined with three alternative methods for sporozoite purification, this approach allowed us to identify the deep proteome of P. berghei sporozoites using low numbers of parasites. This study provides a reference proteome for P. berghei sporozoites, identifying a core set of proteins expressed accross species, and illustrates how the unprecedented sensitivity of the timsTOF PRO system enables deep proteomic analysis from limited sample amounts.

microbiology↗