Biology subjects

Lepletier, A.

Publications and source records attributed to Lepletier, A..

5 recordsLinked to original sources

bioRxiv2025

Sub-clinical exposure to Streptococcus pyogenes drives the development of immunity

Age-related decline in Streptococcus pyogenes infection rates suggests that immunity develops progressively through repeated exposure during early life. However, the intensity or duration of exposure required is unknown, as to why some individuals appear to develop immunity, despite having few or no previously detected infections. Here, drawing on samples from a human challenge model of pharyngeal S. pyogenes infection, we investigate whether symptomatic disease is required for induction of humoral and cellular immunity. Challenge with M75 S. pyogenes induced M75-specific serum IgG and IgA antibodies and memory B cell in both symptomatic and asymptomatic participants, with responses persisting for at least 6 months. Purified IgG from asymptomatic participants exhibited significantly enhanced binding to M75 S. pyogenes and were bactericidal when transferred into a murine model of pharyngeal infection. M75-specific IgG from these participants had an altered Fc glycosylation signature, indicative of enhanced effector function and ability to limit inflammation. However, S. pyogenes challenge had no impact on cellular or humoral immune responses to a conserved cryptic epitope, p*17. These findings show that asymptomatic (or sub-clinical) exposure to M75 S. pyogenes generates functional immune responses and contributes to the streptococcal immunity that emerges by adulthood.

microbiology↗

bioRxiv2024

Immunotherapeutic strategy to prevent progression and complications of acute rheumatic fever

Acute rheumatic fever (ARF) is an autoimmune disease triggered by antibodies and T-cells targeting the Group A streptococcal (GAS, Strep A) bacterium, often leading to rheumatic heart disease (RHD). Long-term antibiotic therapy is recognized as a cornerstone of public health programs to prevent reinfection and progression of ARF. However, better tools to slow disease progression, and mitigate its lifelong consequences are required. Evidence obtained in a preclinical model suggests that this can be achieved. Using the rat autoimmune valvulitis model, we explored the potential of low-dose interleukin 2 (LD-IL-2) as an immunotherapeutic intervention. In this model injection of recombinant Strep A M5 protein (rM5) to Lewis rats induce autoimmune complications, cardiac tissue inflammation and conduction abnormalities. In animals injected with rM5 and treated with LD-IL-2, no cardiac functional or histological changes were observed. LD-IL-2 therapy effectively reduced the production of cross-reactive antibodies against cardiac tissue and induced a significant increase in classical regulatory T-cells (Treg) and CD8+ Tregs in the mediastinal (heart-draining) lymph nodes. These novel findings suggest LD-IL-2 will be an effective immunotherapeutic agent for treating ARF/RHD.

immunology↗

bioRxiv2023

Disruption of IL-17 signaling in the respiratory mucosa results in invasive streptococcal infection

Streptococcus pyogenes infection of the upper respiratory tract and skin can lead to severe invasive streptococcal disease (ISD). Previous studies have demonstrated that the deficiency of IL-17 in mice (IL-17-/-) reduces mucosal immunity against S. pyogenes. However, the impact of IL-17 deficiency on the development of ISD is unknown. Here, we model single or repeated non-lethal, intranasal (IN) S. pyogenes M1 strain infections in immunocompetent and IL-17-/-mice to assess bacterial dissemination following a final IN or skin challenge. Immunocompetent mice that received a single S. pyogenes IN infection displayed long-lasting mucosal immunity and no systemic infection. However, in the absence of IL-17, a single IN infection resulted in the dissemination of S. pyogenes to the spleens, which was further exacerbated by repeated IN infections. Interestingly, immunity following skin challenge did not show a correlation with IL-17 and was instead associated with the activation of germinal center responses and the accumulation of neutrophils in the spleen. Our results highlight the critical role of IL-17 in preventing ISD following S. pyogenes infection of the respiratory mucosa.

immunology↗

bioRxiv2023

Integrative proteomics and transcriptomics of human T-cells reveals temporal metabolic reprogramming following TCR-induced activation

T-cells are critical components of the adaptive immune system. Upon activation, they acquire effector functions through a complex interplay between mRNA transcripts and proteins, the landscape of which remains to be fully elucidated. In this resource article, we present an integrative temporal proteomic and transcriptomic analysis of primary human CD4+ and CD8+ T-cells following ex vivo activation with anti-CD3/CD28 Dynabeads. Our data reveal a time-dependent dissociation between the T-cell transcriptome and proteome during activation. A transient downregulation of GLUT1, the central glucose transporter in T-cells, marked the onset of reprogramming in both CD4+ and CD8+ T-cells. At late activation, CD4+ T-cells upregulated enzymes associated with degradation of fatty acids while CD8+ T-cells preferentially upregulated enzymes in the metabolism of cofactors and vitamins. Surprisingly, we found that activated CD4+ and CD8+ T-cells became transcriptionally more divergent at the same time their proteome became more similar. In addition to the metabolic reprogramming highlighted in our analysis, this dataset provides a public resource for understanding temporal molecular changes governing the acquisition of effector functions by T-cells.

systems biology↗

bioRxiv2021

Expression of CD49f defines subsets of human regulatory T cells with divergent transcriptional landscape and function that correlate with ulcerative colitis disease activity

ObjectiveAdoptive regulatory T cell (Treg) therapy is being trialled for treatment of different autoimmune disorders, including inflammatory bowel diseases (IBD). In-depth understanding of the biological variability of Treg in the human blood may be required to improve IBD immune monitoring and treatment strategies. MethodsThrough a combination of quantitative proteomic, multiparametric flow cytometry, RNA-sequencing data analysis and functional assays on Treg enriched from the blood of ulcerative colitis (UC) patients and healthy controls, we investigated the association between CD49f expression, Treg phenotype and function, and UC disease activity. ResultsHigh-dimensional analysis and filtering defined two distinct subsets of human Treg based on the presence or absence of CD49f with divergent transcriptional landscape and functional activities. CD49f negative Treg are enriched for functional Treg markers and present significantly increased suppressive capacity. In contrast, CD49f high Treg display a pro-inflammatory Th17-like phenotype and accumulate in the blood of UC patients. Dysregulation on CD49f Treg subsets in UC patients correlate with disease activity. ConclusionOverall our findings uncover the importance of CD49f expression on Treg in physiological immunity and in pathological autoimmunity.

immunology↗