Dr. Lally and Ms Smith contributed equally to this work.
A novel mechanism of neutrophil recruitment in a coculture model of the rheumatoid synovium
Article first published online: 27 OCT 2005
Copyright © 2005 by the American College of Rheumatology
Arthritis & Rheumatism
Volume 52, Issue 11, pages 3460–3469, November 2005
How to Cite
Lally, F., Smith, E., Filer, A., Stone, M. A., Shaw, J. S., Nash, G. B., Buckley, C. D. and Ed Rainger, G. (2005), A novel mechanism of neutrophil recruitment in a coculture model of the rheumatoid synovium. Arthritis & Rheumatism, 52: 3460–3469. doi: 10.1002/art.21394
- Issue published online: 27 OCT 2005
- Article first published online: 27 OCT 2005
- Manuscript Accepted: 2 AUG 2005
- Manuscript Received: 16 MAY 2005
- Biotechnology and Biological Sciences Research Council. Grant Number: 02/A4/C/08602
- Arthritis Research Campaign. Grant Number: B0694
- British Heart Foundation Non-Clinical Senior Lectureship. Grant Number: BS/97001
Rheumatoid arthritis (RA) is classically thought of as a Th1, T lymphocyte–driven disease of the adaptive immune system. However, cells of the innate immune system, including neutrophils, are prevalent within the diseased joint, and accumulate in large numbers. This study was undertaken to determine whether cells of the rheumatoid stromal microenvironment could establish an inflammatory environment in which endothelial cells are conditioned in a disease-specific manner to support neutrophil recruitment.
Human umbilical vein endothelial cells (ECs) and fibroblasts isolated from the synovium or skin of RA patients were established in coculture on opposite sides of porous transwell filters. After 24 hours of EC conditioning, the membranes were incorporated into a parallel-plate, flow-based adhesion assay and levels of neutrophil adhesion to ECs were measured.
ECs cocultured with synovial, but not skin, fibroblasts could recruit neutrophils in a manner that was dependent on the number of fibroblasts. Antibody blockade of P-selectin or E-selectin reduced neutrophil adhesion, and an antibody against CD18 (the β2 integrin) abolished adhesion. Blockade of CXCR2, but not CXCR1, also greatly inhibited neutrophil recruitment. Interleukin-6 (IL-6) was detectable in coculture supernatants, and both IL-6 and neutrophil adhesion were reduced in a dose-dependent manner by hydrocortisone added to cocultures. Antibody blockade of IL-6 also effectively abolished neutrophil adhesion.
Synovial fibroblasts from the rheumatoid joint play an important role in regulating the recruitment of inflammatory leukocytes during active disease. This process may depend on a previously unsuspected route of IL-6–mediated crosstalk between fibroblasts and endothelial cells.