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CTLA-4 pathway is instrumental in Giant Cell Arteritis

ABSTRACT: BACKGROUND: Giant Cell Arteritis (GCA) causes severe inflammation of the aorta and its branches and is characterized by intense effector T cells infiltration. The roles that immune checkpoints play in pathogenesis of GCA are still unclear.Our aim was to study the immune checkpoints interplay in GCA. METHODS: First, we used VigiBase, the WHO international pharmacovigilance database, to evaluate the relationship between GCA occurrence and immune checkpoint inhibitors (ICI) treatments. We then further dissected the role of ICI in the pathogenesis of GCA, using immunohistochemistry, immunofluorescence, transcriptomics and flow cytometry on peripheral blood mononuclear cells (PBMCs) and aortic tissues of GCA patients and appropriated controls. RESULTS: Using VigiBase, we identified GCA as a significant immune related adverse event associated with anti-CTLA-4 (Cytotoxic T-lymphocyte-associated-protein-4) but not anti-PD-1/PD-L1 treatment. We further dissected a critical role for CTLA-4 pathway in GCA by identification of the dysregulation of CTLA-4-derived gene pathways and proteins in CD4+ T cells (and specifically Tregs) present in blood and aorta of GCA patients versus controls. While Tregs were less abundant and activated/suppressive in blood and aorta of GCA versus controls, they still specifically upregulated CTLA-4. Activated and proliferating CTLA-4+ Ki-67+ Tregs from GCA were more sensitive to anti-CTLA-4 (Ipilimumab)-mediated in vitro depletion versus controls. CONCLUSIONS: We highlighted the instrumental role of CTLA-4 immune checkpoint in GCA which provides a strong rationale for targeting this pathway.

ORGANISM(S): Homo sapiens

PROVIDER: GSE236367 | GEO | 2023/07/03

REPOSITORIES: GEO

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Project description:Immune memory cells are poised to rapidly expand and elaborate effector functions upon reinfection. However, despite heightened readiness to respond, memory cells exist in a functionally quiescent state. The paradigm is that memory cells remain inactive due to lack of TCR stimuli. Here we report a unique role of Tregs in orchestrating memory quiescence by inhibiting effector and proliferation programs through CTLA-4. Loss of Tregs resulted in activation of genome-wide transcriptional programs characteristic of potent effectors, and both developing and established memory quickly reverted to a terminally differentiated (KLRG-1hi/IL-7R±lo/GzmBhi) phenotype, with compromised metabolic fitness, longevity, polyfunctionality and protective efficacy. CTLA-4, an inhibitory receptor overexpressed on Tregs, functionally replaced Tregs in trans to rescue Treg-less memory defects and restore homeostasis of secondary mediators as well. These studies present CD28-CTLA-4-CD80/CD86 axis as a novel target to potentially accelerate vaccine-induced immunity and improve T-cell memory quality in current cancer immunotherapies proposing transient Treg-depletion. We used microarray analysis to detail the global programming of gene expression in LCMV GP33-specific CD8 T cells differentiated in the presence or absence of regulatory T cells Differentiation of memory CD8 T cells entails a progressive transition of highly activated effector program to a quiescent memory program. A key question in the field is to understand the factors that aid in the differentiation of memory cells from effector cells. It is a generally accepted paradigm that effector cells transition to a memory state by default after antigen clearance, since TCR stimuli is the key driver of effector programs in CD8 T cells. We hypothesized that the effector to memory transition of CD8 T cells involves active immunological brakes through regulatory T cells (Tregs) that allow the highly activated effector cells to convert into quiescent memory cells. To address this hypothesis, we used FoxP3-DTR mice to deplete Tregs during the window following antigen clearance, during which the effector CD8 T cells convert to long-lived memory cells. To get a deeper understanding of the global transcriptome of CD8 T cells as they transition from an effector to a memory state, we isolated and arrayed the antigen-specific CD8 T cells at day 16 post-infection that have experienced the transitional environment with and without the presence of Tregs.

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CTLA-4 pathway is instrumental in Giant Cell Arteritis

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