Biology subjects

Charbit, B.

Publications and source records attributed to Charbit, B..

6 recordsLinked to original sources

bioRxiv2025

Spatial proteomic mapping of the human and mouse retina using IBEX

PurposeTo generate a comparative spatial proteomic atlas of the human and mouse retina using a refined highly multiplexed immunohistochemistry technique called Iterative Bleaching Extends Multiplexity (IBEX). MethodsWe refined the IBEX workflow by integrating an antibody removal option alongside chemical bleaching. This dual strategy enabled removal of the entire antibody complex allowing for the flexible use of antibodies from the same host species across iterative cycles. Spatial proteomic data were cross-correlated to existing scRNAseq datasets. We also coupled this workflow with super-resolution imaging via deconvolution and applied it to the retina of healthy human, mouse and the Crb1rd8 mouse model. ResultsWe successfully imaged over 25 protein markers on human and mouse tissue sections, to generate spatial atlases of the major retinal cell populations. Cross-species protein expression was compared to scRNAseq datasets to identify protein and transcript disparities. Super-resolution IBEX delineated the ultrastructural features of the outer limiting membrane (OLM), identifying CD44 as a core structural component tightly co-localised with a highly organised F-actin belt within Muller glial endfeet. Using the Crb1rd8 mouse model, disruption of this complex was spatially associated with rosette formation and OLM structural failure. ConclusionSpatial proteomic atlases of the human and mouse retina were generated and correlated to transcriptional data, revealing insights into the arrangement of major retinal cell populations and OLM structure.

neuroscience↗

bioRxiv2021

A monocyte/dendritic cell molecular signature of SARS-CoV2-related multisystem inflammatory syndrome in children (MIS-C) with severe myocarditis

SARS-CoV-2 infection in children is generally milder than in adults, yet a proportion of cases result in hyperinflammatory conditions often including myocarditis. To better understand these cases, we applied a multi-parametric approach to the study of blood cells of 56 children hospitalized with suspicion of SARS-CoV-2 infection. The most severe forms of MIS-C (multisystem inflammatory syndrome in children related to SARS-CoV-2), that resulted in myocarditis, were characterized by elevated levels of pro-angiogenesis cytokines and several chemokines. Single-cell transcriptomic analyses identified a unique monocyte/dendritic cell gene signature that correlated with the occurrence of severe myocarditis, characterized by sustained NF-{kappa}B activity, TNF- signaling, associated with decreased gene expression of NF-{kappa}B inhibitors. We also found a weak response to type-I and type-II interferons, hyperinflammation and response to oxidative stress related to increased HIF-1 and VEGF signaling. These results provide potential for a better understanding of disease pathophysiology.

immunology↗

bioRxiv2020

Tuberculosis alters immune-metabolic pathways resulting in perturbed IL-1 responses

Tuberculosis (TB) remains a major public health problem with host-directed therapeutics offering potential as novel treatment strategies. However, their successful development still requires a comprehensive understanding of how Mycobacterium tuberculosis (M.tb) infection impacts immune responses. To address this challenge, we applied standardised immunomonitoring tools to compare TB antigen, BCG and IL-1{beta} induced immune responses between individuals with latent M.tb infection (LTBI) and active TB disease, at diagnosis and after cure. This revealed distinct responses between TB and LTBI groups at transcriptomic, proteomic and metabolomic levels. At baseline, we identified pregnane steroids and the PPAR{gamma} pathway as new immune-metabolic drivers of elevated plasma IL-1ra in TB. We also observed dysregulated induced IL-1 responses after BCG stimulation in TB patients. Elevated IL-1 antagonist responses were explained by upstream differences in TNF responses, while for IL-1 agonists it was due to downstream differences in granzyme mediated cleavage. Finally, the immune response to IL-1{beta} driven signalling was also dramatically perturbed in TB disease but was completely restored after successful antibiotic treatment. This systems immunology approach improves our knowledge of how immune responses are altered during TB disease, and may support design of improved diagnostic, prophylactic and therapeutic tools.

immunology↗

bioRxiv2020

Stability and dynamics of the human gut microbiome and its association with systemic immune traits

Analysis of 1,363 deeply sequenced gut microbiome samples from 946 healthy donors of the Milieu Interieur cohort provides new opportunities to discover how the gut microbiome is associated with host factors and lifestyle parameters. Using a genome-based taxonomy to achieve higher resolution analysis, we found an enrichment of Prevotella species in males, and that bacterial profiles are dynamic across five decades of life (20-69), with Bacteroidota species consistently increased with age while Actinobacteriota species, including Bifidobacterium, decreased. Longitudinal sampling revealed short-term stability exceeds inter-individual differences; however, the degree of stability was variable between donors and influenced by their baseline community composition. We then integrated the microbiome results with systemic immunophenotypes to show that host/microbe associations discovered in animal models, such as T regulatory cells and short chain fatty acids, could be validated in human data. These results will enable personalized medicine approaches for microbial therapeutics and biomarkers.

microbiology↗

bioRxiv2019

Immune profiling in M. tuberculosis infection enables stratification of patients with active disease

Tuberculosis (TB) is caused by Mycobacterium tuberculosis (Mtb) infection and is a major public health problem with an estimated 1.7 billion persons infected worldwide. Clinical challenges in TB include the lack of a blood-based test for active disease, and the absence of prognostic biomarkers for early treatment response. Current blood based tests, such as QuantiFERON-TB Gold (QFT), are based on an IFN{gamma} readout following Mtb antigen stimulation. However, they do not distinguish active TB disease from asymptomatic Mtb infection. We hypothesized that the use of TruCulture, an improved immunomonitoring method for whole blood collection and immune stimulation, could improve the discrimination of active disease from latent Mtb infection. To test our hypothesis, we stimulated whole blood from active TB patients (before and after successful treatment), comparing them to asymptomatic latently infected individuals. Mtb-specific antigens (ESAT-6, CFP-10, TB7.7) and live bacillus Calmette-Guerin (BCG) were used for TruCulture stimulation conditions, with direct comparison to QFT. Protein analyses were performed on the culture supernatants using ELISA and Luminex multi-analyte profiling. TruCulture showed an ability to discriminate active TB cases from latent controls (p < 0.0001, AUC = 0.81, 95% CI: 0.69-0.93) as compared to QFT (p = 0.47 AUC = 0.56, 95% CI: 0.40-0.72), based on an IFN{gamma} readout after Mtb antigen stimulation. The stratification of the two groups could be further improved by using the Mtb Ag/BCG IFN{gamma} ratio response (p < 0.0001, AUC = 0.918, 95% CI: 0.84-0.98). We also identified additional cytokines that distinguished latent infection from TB disease; and show that the primary differences between the TruCulture and QFT systems were a result of higher levels of non-specific innate immune activation in QFT tubes, due to the lack of a buffering solution in the latter. We conclude that TruCulture offers a next-generation solution for whole blood stimulation and immunomonitoring with the possibility to discriminate active and latently infected persons.

immunology↗

bioRxiv2018

Genetic factors and age are the strongest predictors of humoral immune responses to common pathogens and vaccines

IntroductionHumoral immune responses to infectious agents or vaccination vary substantially among individuals, and many of the factors responsible for this variability remain to be defined. Current evidence suggests that human genetic variation influences (i) serum immunoglobulin levels, (ii) seroconversion rates, and (iii) intensity of antigen-specific immune responses. Here, we evaluate the impact of intrinsic (age and sex), environmental and genetic factors on the variability of humoral response to common pathogens and vaccines.\n\nMethodsWe characterized the serological response to 15 antigens from common human pathogens or vaccines, in an age- and sex-stratified cohort of 1,000 healthy individuals (Milieu Interieur cohort). Using clinical-grade serological assays, we measured total IgA, IgE, IgG and IgM levels, as well as qualitative (serostatus) and quantitative IgG responses to cytomegalovirus, Epstein-Barr virus, herpes simplex virus 1 & 2, varicella zoster virus, Helicobacter pylori, Toxoplasma gondii, influenza A virus, measles, mumps, rubella, and hepatitis B virus. Following genome-wide genotyping of single nucleotide polymorphisms and imputation, we examined associations between ~5 million genetic variants and antibody responses using single marker and gene burden tests.\n\nResults and discussionWe identified age and sex as important determinants of humoral response, with older individuals and women having higher rates of seropositivity for most antigens. Genome-wide association studies revealed significant associations between variants in the human leucocyte antigen (HLA) class II region on chromosome 6 and anti-EBV and anti-rubella IgG levels. We used HLA imputation to fine map these associations to amino acid variants in the peptide-binding groove of HLA-DR{beta}1 and HLA-DP{beta}1, respectively. We also observed significant associations for total IgA levels with two loci on chromosome 2 and with specific KIR-HLA combinations.\n\nConclusionsUsing extensive serological testing and genome-wide association analyses in a well-characterized cohort of healthy individuals, we demonstrate that age, sex and specific human genetic variants contribute to inter-individual variability in humoral response. By highlighting genes and pathways implicated in the normal antibody response to frequently encountered antigens, these findings provide a basis to better understand disease pathogenesis.

genomics↗