Single-cell sequencing reveals clonal expansions of pro-inflammatory synovial CD8 T cells expressing tissue-homing receptors in psoriatic arthritis.

Psoriatic arthritis (PsA) is a debilitating immune-mediated inflammatory arthritis of unknown pathogenesis commonly affecting patients with skin psoriasis. Here we use complementary single-cell approaches to study leukocytes from PsA joints. Mass cytometry demonstrates a 3-fold expansion of memory CD8 T cells in the joints of PsA patients compared to peripheral blood. Meanwhile, droplet-based and plate-based single-cell RNA sequencing of paired T cell receptor alpha and beta chain sequences show pronounced CD8 T cell clonal expansions within the joints. Transcriptome analyses find these expanded synovial CD8 T cells to express cycling, activation, tissue-homing and tissue residency markers. T cell receptor sequence comparison between patients identifies clonal convergence. Finally, chemokine receptor CXCR3 is upregulated in the expanded synovial CD8 T cells, while two CXCR3 ligands, CXCL9 and CXCL10, are elevated in PsA synovial fluid. Our data thus provide a quantitative molecular insight into the cellular immune landscape of psoriatic arthritis

Single-cell sequencing reveals clonal expansions of pro-inflammatory synovial CD8 T cells expressing tissue-homing receptors in psoriatic arthritis

Psoriatic arthritis (PsA) is a debilitating immune-mediated inflammatory arthritis of unknown pathogenesis commonly affecting patients with skin psoriasis. Here we use complementary single-cell approaches to study leukocytes from PsA joints. Mass cytometry demonstrates a 3-fold expansion of memory CD8 T cells in the joints of PsA patients compared to peripheral blood. Meanwhile, droplet-based and plate-based single-cell RNA sequencing of paired T cell receptor alpha and beta chain sequences show pronounced CD8 T cell clonal expansions within the joints. Transcriptome analyses find these expanded synovial CD8 T cells to express cycling, activation, tissue-homing and tissue residency markers. T cell receptor sequence comparison between patients identifies clonal convergence. Finally, chemokine receptor CXCR3 is upregulated in the expanded synovial CD8 T cells, while two CXCR3 ligands, CXCL9 and CXCL10, are elevated in PsA synovial fluid. Our data thus provide a quantitative molecular insight into the cellular immune landscape of psoriatic arthritis

Single-cell sequencing reveals clonal expansions of pro-inflammatory synovial CD8 T cells expressing tissue-homing receptors in psoriatic arthritis

Funder: Kennedy Trust studentshipFunder: Oxford-UCB Prize FellowshipFunder: National Institute of Health Research (NIHR) Newcastle Biomedical Research Centre at Newcastle Hospitals Foundation Trust and Newcastle University and Versus Arthritis Research into Inflammatory Arthritis Centre; ref. 22072).Funder: NIHR Birmingham BRC at the University Hospitals Birmingham NHS Foundation Trust and the University of BirminghamFunder: Wellcome Trust (Wellcome); doi: https://doi.org/10.13039/100004440Funder: National Institute for Health Research (NIHR) Oxford Biomedical Research CentreFunder: St Baldrick’s FoundationAbstract: Psoriatic arthritis (PsA) is a debilitating immune-mediated inflammatory arthritis of unknown pathogenesis commonly affecting patients with skin psoriasis. Here we use complementary single-cell approaches to study leukocytes from PsA joints. Mass cytometry demonstrates a 3-fold expansion of memory CD8 T cells in the joints of PsA patients compared to peripheral blood. Meanwhile, droplet-based and plate-based single-cell RNA sequencing of paired T cell receptor alpha and beta chain sequences show pronounced CD8 T cell clonal expansions within the joints. Transcriptome analyses find these expanded synovial CD8 T cells to express cycling, activation, tissue-homing and tissue residency markers. T cell receptor sequence comparison between patients identifies clonal convergence. Finally, chemokine receptor CXCR3 is upregulated in the expanded synovial CD8 T cells, while two CXCR3 ligands, CXCL9 and CXCL10, are elevated in PsA synovial fluid. Our data thus provide a quantitative molecular insight into the cellular immune landscape of psoriatic arthritis

Pathogenic immune responses in Spondyloarthritis

Immune dysfunction in spondyloarthritis (SpA) causes significant morbidity to a large number of patients. An understanding of the underlying pathological processes involved in causing the disease is essential for the development and better targeting of therapies. I have shown for the first time in patients with SpA an overall expansion of peripheral blood and synovial fluid T cells producing GM-CSF and an expansion of GM-CSF positive Th17 cells. In addition, I have shown GM-CSF to be a major effector cytokine of joint-derived innate lymphoid cells. Surface phenotyping and transcriptional analysis of the IL-17A/GM-CSF double positive cells showed that whilst they are related to classic Th17 cells, they also have a uniquely activated transcriptional profile. Additionally, I have shown IL-7 to be a promoter of GM-CSF production by CD4 T lymphocytes in vitro. However, my data shows that polymorphisms of the IL7R, which have been shown to be associated with AS in genome-wide association studies, play a functional role through cell surface expression of the IL7R on CD14 monocytes. This genotypic expression of the IL7R on monocytes is only seen after activation with LPS or TNF&alpha;. I further show CD14 monocytes expressing IL7R to be present in SpA joints. My data shows that RORγt, the master transcription factor of Th17 cells, can be therapeutically targeted using small molecule inhibitors in-vitro. These inhibitors lead to a specific suppression of both polyfunctional and IL-17A single positive Th17 cells. The work in this thesis has highlighted several areas of novel immune biology with potential therapeutic applications in SpA and across the spectrum of related inflammatory diseases. </p

Inhibiting ex-vivo Th17 responses in Ankylosing Spondylitis by targeting Janus kinases.

Treatment options for Ankylosing Spondylitis (AS) are still limited. The T helper cell 17 (Th17) pathway has emerged as a major driver of disease pathogenesis and a good treatment target. Janus kinases (JAK) are key transducers of cytokine signals in Th17 cells and therefore promising targets for the treatment of AS. Here we investigate the therapeutic potential of four different JAK inhibitors on cells derived from AS patients and healthy controls, cultured in-vitro under Th17-promoting conditions. Levels of IL-17A, IL-17F, IL-22, GM-CSF and IFNγ were assessed by ELISA and inhibitory effects were investigated with Phosphoflow. JAK1/2/3 and TYK2 were silenced in CD4+ T cells with siRNA and effects analyzed by ELISA (IL-17A, IL-17F and IL-22), Western Blot, qPCR and Phosphoflow. In-vitro inhibition of CD4+ T lymphocyte production of multiple Th17 cytokines (IL-17A, IL-17F and IL-22) was achieved with JAK inhibitors of differing specificity, as well as by silencing of JAK1-3 and Tyk2, without impacting on cell viability or proliferation. Our preclinical data suggest JAK inhibitors as promising candidates for therapeutic trials in AS, since they can inhibit multiple Th17 cytokines simultaneously. Improved targeting of TYK2 or other JAK isoforms may confer tailored effects on Th17 responses in AS