Regulation of leukocyte recruitment by fibroblast-endothelial interactions

Regulation of leukocyte recruitment by fibroblast-endothelial interactions: Understanding the stromal switch from resolution to persistent inflammation

Rheumatoid arthritis (RA) is a major cause of disability affecting ~1% of the UK population. Biological treatments that target leukocytes or their cytokine produces have improved outcomes, but they do not reverse tissue damage nor do they cure disease. During the earliest stages of disease, conventional treatments are significantly more effective, but the reasons for this are not clear. Current evidence suggests that we may be able to improve control of disease further if we can better target the unique pathological processes occurring early on.

RA synovial fibroblasts are major contributors to joint damage and disease persistence, but have yet to be targeted therapeutically. Synovial fibroblasts actively regulate leukocyte recruitment through interactions with endothelial cells (EC) that line blood vessels (McGettrick et al., 2009). We have characterised a unique phenotype of synovial fibroblasts seen in early arthritis that distinguishes acute resolving arthritis (Res) from the early stages of RA (eRA). Res fibroblasts induce an immunosuppressive response in EC that limits the magnitude of leukocytes recruited to the joint (McGettrick et al., 2014; McGettrick et al., 2015). However this capacity is lost in eRA synovial fibroblasts (McGettrick et al., 2014; McGettrick et al., 2015). This change represents a phenotypic swtich from protective to pathological synoival fibroblast-endothelial cell interactions.

Thie aim of this PhD studentship is to interrogate the molecular mechanism underpinning the cellular cross-talk between the synovial fibroblasts and EC. To achieve this the student will have access to a unique resource of cellular material from the Birmingham Early Arthritis Cohort (BEACON), which will be analysed using high throughput analysis platforms (e.g. microarrays, RNAseq, proteomics, phosphokinase arrays, metabolomics) at Novartis, by flow based adhesion assays, live whole tissue imaging platforms, and chimeric mouse models of arthritis incorporating human synovial tissue and cells available at Birmingham.

The work will generate new insights into disease pathogenesis and provide novel targets for drug development. Ultimately, we aim to test whether mimicking the actions of Res SF or inhibiting those of 'pathogenic' eRA or RA SF can reset the balance of leukocyte recruitment, thus halting disease progression.