RT Journal Article
SR Electronic
T1 Bone Lineage Proteins in the Entheses of the Midfoot in Patients with Spondyloarthritis
JF The Journal of Rheumatology
JO J Rheumatol
FD The Journal of Rheumatology
SP jrheum.140218
DO 10.3899/jrheum.140218
A1 César Pacheco-Tena
A1 Ruy Pérez-Tamayo
A1 Carlos Pineda
A1 Susana A.  González-Chávez
A1 Celia Quiñonez-Flores
A1 Antonio Ugalde  Vitelly
A1 Robert D.  Inman
A1 Jane E.  Aubin
A1 Janitzia Vázquez-Mellado
A1 Rubén Burgos-Vargas
YR 2014
UL http://www.jrheum.org/content/early/2014/12/10/jrheum.140218.abstract
AB Objective Patients with juvenile-onset spondyloarthritis (SpA) may develop ankylosis of the midfoot resembling the spinal changes seen in patients with ankylosing spondylitis (AS). The study of the histopathology of the feet of patients with tarsitis could help us understand the pathogenesis of bone formation in affected structures in the SpA. The objective of our study was to describe the histopathologic characteristics of the midfoot in patients with tarsitis associated with SpA. Methods We obtained synovial sheaths, entheses, and bone samples from 20 patients with SpA with midfoot pain/tenderness and swelling. Tissue samples underwent H&E staining; immunohistochemistry for CD3, CD4, CD8, CD68, and CD20 cell identification; and immunofluorescence for bone lineage proteins, including osteocalcin, osteopontin, parathyroid hormone-related protein, bone sialoprotein, and alkaline phosphatase. Results Slight edema and hyalinization were found in some tendon sheaths, and few inflammatory cells were detected in the entheses. In bones, we found some changes suggesting osteoproliferation, including endochondral and intramembranous ossification, but no inflammatory cells. In entheses showing bone proliferation, we detected osteocalcin and osteopontin in cells with a fibroblastmesenchymal phenotype, suggesting the induction of entheseal cells toward an osteoblast phenotype. Conclusion Osteoproliferation and abnormal expression of bone lineage proteins, but no inflammatory infiltration, characterize midfoot involvement in patients with SpA. In this sense, tarsitis (or ankylosing tarsitis) resembles the involvement of the spine in patients with AS. Ossification may be in part explained by the differentiation of mesenchymal entheseal cells toward the osteoblastic lineage.