s31_ab4

The histopathology of early synovitis

C.A. Hitchon, H.S. El-Gabalawy

Department of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada

ABSTRACT
Early diagnosis and therapeutic intervention are needed to prevent the morbidity related to erosive arthropathies such as rheumatoid arthritis (RA), yet it is difficult to distinguish various forms of synovitis early in the disease course. The availability of synovial tissue biopsy techniques has facilitated the analysis of synovial tissue from patients with early disease. Comparison of the histopathologic features of synovial tissue in early RA, established RA, and in non-RA synovitis has shown subtle, but potentially important differences in histologic features, cytokine and protease expression patterns, and apoptosis. Ultimately, it remains to be shown definitively that analysis of the histopathological features of synovial tissue early in disease is of independent value in identifying patients destined to have persistent synovitis or erosive disease, and in turn, in allocating patients to specific therapeutic strategies.

Key words
Early synovitis, rheumatoid arthritis, arthroscopy, biopsy, histopathology.

List of abbreviations
RA: rheumatoid arthritis
OA: osteoarthritis
PsA: psoriatic arthritis
SpA: spondyloarthropathy
AS: ankylosing spondylititis
UA: undifferentiated arthritis
SLE: systemic lupus erythematosus
PMN: Polymorphonuclear cell
MIP1: macrophage inflammatory protein 1
NIH: National Institutes of Health
VEGF: vascular endothelial growth factor
ICAM1: intercellular adhesion molecule 1
VCAM1: vascular cell adhesion molecule 1
PECAM1: platelet-endothelial cell
adhesion molecule 1
VLA: very-late antigen
MCP1: monocyte chemoattractant protein
TH1, TH2: T helper cell type 1; T helper
cell type 2
TNF: tumor necrosis factor
INF: interferon
IL: interleukin
MMP: matrix metalloproteinase
TIMP: tissue inhibitor of matrix metallo
proteinase
TUNEL: Terminal deoxynucleotidyl trans
ferase mediated dUTP nick end labeling
FLICE: FADD-like interleukin 1b
converting enzyme
FADD: Fas-associated death domain
protein
FLIP: FLICE-like inhibitory protein
NFkb: nuclear factor kappa beta
RANK: receptor activator of NFkb
RANKL: receptor activator of NFkb ligand
OPG: osteoprotegerin

Please address correspondence and reprint requests to: Dr Hani El-Gabalawy, RR 149 800 Sherbrook Street, Winnipeg, Manitoba, R3A-1M4 Canada.
E-mail: elgabal@cc.umanitoba.ca