ANNUAL REVIEW master Final3a - St Vincent's University Hospital

Specific ongoing projects
(1) THERAPI Translational Medicine Group
Hypoxia and altered mitochondrial bioenergetics in the inflamed joint.
This major programme funded by a Translational Research Award from The HRB (2006-2011) to Prof Doug
Veale, Dr Ursula Fearon, Dr Jacintha O’Sullivan and Dr Cormac Taylor, hypothesizes that vascular morphology
and synovial invasiveness within the inflamed joint and response to therapy, may be dependent on activation
of mitochondria-derived, hypoxia-induced transcriptional and non-transcriptional pathways and alterations in
genome stability. By incorporating novel techniques, we are measuring for the first time the oxygen tension
directly in lining membrane of inflamed synovial joints using a special probe to measure pO2 and
temperature. We also record the macroscopic vascular changes, and we intend to measure blood flow and
glucose metabolism by dynamic imaging (MRI and PET), while parallel cellular changes in mitochondrial
respiration will be analysed. Dr Vincent Ng, clinical research fellow has successfully established a clinical
protocol to recruit patients (n=29) commencing biologic therapy to undergo arthroscopic examination and
hypoxic measures. He has demonstrated that tissue pO2 levels correlate with macroscopic synovitis and
vascularity. Currently he is examining proliferation and apoptosis markers in paired synovial tissue (Ki67 and
TUNEL) to examine correlations between tissue invasiveness, macroscopic assessments and in vivo hypoxia
measurements. In future work, Vincent is going to examine the effects of graded hypoxia on proliferation,
apoptosis and cell cycle using primary synovoa fibroblasts from patients undergoing arthroscopy. The results
will be related back to the clinical status of the patient.
In parallel, Aisling Kennedy, graduate PhD student, is examining the effect of hypoxia on the
angiopoietins/Tie2 pathway, blood vessel morphology and cell survival in the joint. Preliminary data has
demonstrated differential expression of Angiopoietin 2 and VEGF from different synovial cell types. She has
also shown strong expression of 8oxo-dG in the synovial tissue reflecting that of the in vivo environment.
Staining is mostly localised to the lining layer and peri-vascular regions but varies depending on the severity
of inflammation (Fig1A). Aisling has shown that exposure of cells to graded hypoxia induces VEGF and
MMP-1 production, in contrast Ang 2 showed minimal change. Further studies have shown that Ang2
sensitises synovial cells to TNF· induction of synovial cell proliferation and invasion, suggesting that adjuvant
therapy may be a novel future approach. Synovial fibroblast cells have been isolated from six of the patients
in this study and are currently growing. We plan to expose these cells to the same level of hypoxia as was
measured in vivo in the patient’s synovial tissue at arthroscopy. Protein and mRNA levels of growth factors
and their downstream targets NFκB, HIF1α, NOTCH and 8-oxodG will be measured.
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