Poster Presentation Australasian Society for Immunology Annual Scientific Meeting 2014

Regulatory T cell trafficking in human health and immuno-inflammatory disease (#293)

Suzanne Asad 1 , Wolfgang Weninger 1 , Diana Chessman 2 , Barbara Fazekas de St Groth 1
  1. Centenary Institute, Camperdown, NSW, Australia
  2. Concord Repatriation General Hospital, Concord, NSW, Australia

Abnormalities in CD4+CD25+CD127loFoxP3+ regulatory T-cells (Tregs) have been implicated in susceptibility to human immuno-inflammatory conditions.

To better understand Treg trafficking and to define functional Treg subsets implicated in the pathogenesis of diseases localised to different tissues, we used flow-cytometry to measure the expression of a range of chemokine receptors and integrins in the peripheral blood of patients with psoriasis (n=24), rheumatoid arthritis (n=34) and healthy individuals (n=31).

We showed that the skin homing integrin CLA and the skin associated chemokine receptor CCR4 are expressed on a higher proportion of Tregs than conventional cells in healthy adults. A significantly lower proportion of Tregs express the gut homing α4β7 integrin.

Total Treg frequency was found to be unchanged in rheumatoid arthritis (RA). However, RA patients had significantly lower levels of CXCR3, CCR5, CCR4 and CCR6 on their effector/memory Tregs.

In psoriasis, Treg frequency was increased in untreated patients. Furthermore, a larger proportion of these Tregs expressed the Th17-associated receptor CCR6. Interestingly, subsets of Tregs expressing the inflammatory gut homing receptors α4 (CD49d) and β7 were reduced. Bioinformatic analysis software was used to simultaneously draw unsupervised, automated comparisons between 220 T-cell and Treg subsets in psoriasis patients and controls. This analysis revealed significant clustering of controls vs patients.

In the literature, there is an increasing use of chemokine receptors to identify Th1 (“CXCR3+”), Th2 (“CXCR3-CCR6-CCR4+”) and Th17 (“CXCR3-CCR6+CCR4+”) cell subsets in the conventional CD4 T cell and Treg compartment. We have designed flow cytometric panels to allow for the simultaneous detection of the chemokine receptors CXCR3, CCR4 and CCR6 in combination with the transcription factors T-bet, RORgt and GATA-3. We have shown that 85% of CXCR3+ cells in PB are in fact Tbet-negative and 75% of CXCR3-CCR6+CCR4+ are RORgt-negative (n=3). Thus the use of chemokine receptors to define functional CD4 and Treg subsets may not be valid. We plan to extend the use of these panels to evaluate a larger patient cohort.