Twohig, J. P. | bioRxiv Science

bioRxiv2024

IL-6 and IL-27 negatively regulate CRTAM-expressing CD4+ T-cells associated with lymphoid-driven synovitis.

ABSTRACT-Joint pathology in rheumatoid arthritis is heterogeneous, with histology providing evidence of fibroblast-driven, myeloid-driven, and lymphoid-driven synovitis. However, the immuno-modulatory pathways underlying their development remain unclear. Profiling synovial tissues from rheumatoid arthritis patients and mice with antigen-induced arthritis, we identified a subset of synovial infiltrating CD4+ T-cells expressing CRTAM (class-I MHC-restricted T-cell-associated molecule). In human synovial biopsies, CRTAM correlated with the expression of effector cytokines (IL21, IFNG), chemokine receptors (CXCR3, CXCR4, CCR5), granzymes (GZMA, GZMB, GZMK), and regulatory factors (TIGIT, EOMES, BATF) linked with T-cell-mediated immunity. Studies of antigen-induced arthritis showed that CRTAM+CD4+ T-cells accumulate in the inflamed synovium following disease onset. CRTAM+CD4+ T-cells were particularly abundant in synovial tissue from Il27ra-/- mice displaying ectopic lymphoid-like structures. CADM1 (cell adhesion molecule-1), the endogenous ligand for CRTAM, was also expressed in human synovitis and synovial tissues from wild-type, Il6ra-/-, and Il27ra-/- mice with antigen-induced arthritis. Cells expressing human CADM1 included synovial fibroblasts and subsets of monocytic and CD19+ cells. Considering the ex vivo regulation of CRTAM, we identified that activation of naive CD4+ T-cell increased CRTAM expression. This induction was blocked by IL-6 and IL-27, with further studies identifying a role for STAT3 in controlling the CRTAM transcriptional repressor, ZEB1. These results provide insights into the cytokine control of CRTAM on CD4+ T-cells and support the involvement of CRTAM+CD4+ T-cells in lymphoid-driven synovitis.

immunology↗

bioRxiv2023

ADAM17 targeting by human cytomegalovirus remodels the cell surface proteome to simultaneously regulate multiple immune pathways

Human cytomegalovirus (HCMV) is a major human pathogen whose life-long persistence is enabled by its remarkable capacity to systematically subvert host immune defences. In exploring the finding that HCMV infection upregulates tumor necrosis factor receptor 2 (TNFR2), a ligand for the pro-inflammatory anti-viral cytokine TNFa, we discovered the underlying mechanism was due to targeting of the protease, A Disintegrin And Metalloproteinase 17 (ADAM17). ADAM17 is the prototype sheddase, a family of proteases that cleaves other membrane-bound proteins to release biologically active ectodomains into the supernatant. HCMV impaired ADAM17 surface expression through the action of two virally-encoded proteins in its UL/b region, UL148 and UL148D. Proteomic plasma membrane profiling of cells infected with a HCMV double deletion mutant for UL148 and UL148D with restored ADAM17 expression, combined with ADAM17 functional blockade, showed that HCMV stabilized the surface expression of 114 proteins (p<0.05) in an ADAM17-dependent fashion. These included known substrates of ADAM17 with established immunological functions such as TNFR2 and Jagged1, but also numerous novel host and viral targets, such as Nectin1, UL8 and UL144. Regulation of TNF-induced cytokine responses and NK inhibition during HCMV infection were dependent on this impairment of ADAM17. We therefore identify a viral immunoregulatory mechanism in which targeting a single sheddase enables broad regulation of multiple critical surface receptors, revealing a paradigm for viral-encoded immunomodulation. Significance statementHuman cytomegalovirus (HCMV) is an important pathogen, being the commonest infectious cause of brain damage to babies and the primary reason for hospital readmissions in transplant recipients. Even though HCMV induces the strongest immune responses by any human pathogen, it evades host defences and persists for life. This study describes a novel immunoregulatory strategy through which HCMV modulates multiple immune pathways simultaneously, by targeting a single host protein. HCMV UL148 and UL148D impair the maturation of the sheddase, A Disintegrin And Metalloproteinase 17, profoundly altering surface expression of numerous immunoregulatory proteins. This is the first description of viral genes targeting this pathway. Our findings may be relevant for future viral therapies and understanding the impact of HCMV in developmental biology.

microbiology↗