{
  "id": 18034700,
  "title": "CTLA-4 checkpoint signalling modulates germinal centre dynamics and antibody avidity during Borrelia burgdorferi infection in mice.",
  "url": "https://urgent.news/2026/11/03/ctla-4-checkpoint-signalling-modulates-germinal-centre-dynamics-and",
  "topic": "science",
  "section": "Science",
  "published": "2026-11-03T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.30.763258v1?rss=1"
  },
  "original_language": "en",
  "account": "The research investigates the role of CTLA-4 checkpoint signalling in the immune response to Borrelia burgdorferi, the bacterium responsible for Lyme borreliosis. The study used single-cell RNA sequencing to examine lymph node cells from mice infected with Borrelia at different time points, comparing their transcriptional profiles to those from mice that received heat-killed Borrelia or potent germinal centre-inducing protein immunisation. The findings suggest that while Borrelia infection triggers a rapid germinal centre response, B cells in the light zone display impaired positive selection, characterized by reduced expression of co-stimulatory and T-B cell interaction molecules while retaining core germinal centre identity markers. Notably, T follicular helper cells upregulate inhibitory checkpoint receptor genes, particularly Ctla4, concurrent with an active germinal centre engagement programme. Additionally, regulatory T cells express genes associated with follicular-homing and suppressive function, including those implicated in CTLA-4-mediated trans-endocytosis. The researchers tested whether inhibitory signalling contributes to the defective humoral response by administering an anti-CTLA-4 blocking antibody to infected mice. The results indicate that CTLA-4 blockade significantly elevates plasma cell numbers and enhances both the magnitude and avidity of Borrelia-specific IgG responses. This includes the induction of complement-fixing IgG2a, suggesting that CTLA-4-dependent inhibitory signalling plays a crucial role in defective antibody quality during Borrelia infection. The study provides insight into a mechanism whereby dysregulated T cell responses may facilitate impaired humoral control of a persistent spirochaetal pathogen.",
  "summary": "Borrelia burgdorferi, the causative agent of Lyme borreliosis, persists in mammalian hosts despite robust activation of innate and adaptive immunity. A hallmark of murine infection is the production of low-avidity antibodies, yet the immunological mechanisms underlying this defective humoral response remain poorly understood. Here, we used single-cell RNA sequencing of draining lymph node cells…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}