Immunohistochemical analysis of hip arthritis in ankylosing spondylitis: Evaluation of the bone–cartilage interface and subchondral bone marrow

Abstract

Objective. Previous histopathologic and magnetic resonance imaging studies suggest that the subchondral bone marrow might be the primary site of inflammation in patients with ankylosing spondylitis (AS) and that this might be reflected by inflammation found in hip joints. The aim of this study was to conduct an immunohistologic assessment of the bone-cartilage interface and subchondral bone marrow in AS patients with hip arthritis.Methods. We collected femoral heads from patients with AS, osteoarthritis (OA), and rheumatoid arthritis (RA) who were undergoing hip replacement. The subchondral bone marrow and bone-cartilage interface were assessed immunohistochemically by evaluating infiltrating T cells, microvessel density, and osteoclasts. Areas of the femoral head surface with and without cartilage were assessed separately.Results. At sites with surface cartilage, we found subchondral infiltration of CD3؉ T cell aggregates at significantly higher numbers in AS patients as compared with OA patients, but not RA patients. At sites of complete cartilage destruction, the frequency of CD3؉ T cell aggregates was significantly reduced as compared with sites with cartilage on the surface in AS patients, but not in RA patients. Similar differences were found for CD4؉ and CD8؉ T cells. Only at sites with surface cartilage, but not those without, angiogenesis and osteoclastic foci in the subchondral bone marrow in AS patients were significantly increased as compared with RA patients and with OA patients.Conclusion. These findings suggest that the subchondral bone marrow and bone-cartilage interface are primary sites of inflammation in AS and that cartilage might be necessary for the induction of inflammation.

Critical appraisal of assessment of structural damage in ankylosing spondylitis: Implications for treatment outcomes

“…It has been effectively shown by earlier studies and also by more recent studies that the inflammation in the axial skeleton of patients with AS is initially dominated by mononuclear cell infiltrates and also by an increased number of osteoclasts (19)(20)(21)(22) (Figure 1). Similar to these findings, bone resorption markers have been found to be increased in AS, especially in patients with active disease (23,24), which most likely is a reflection of trabecular bone loss as the basis of osteoporosis and increased fracture risk in AS.…”

Histomorphologic and Histomorphometric Characteristics of Zygapophyseal Joint Remodeling in Ankylosing Spondylitis

“…Its appearance in the joints of AS patients has previously been described by other investigators (3,21). In fact, in a recent study by Gong et al (23), it was considered a major hallmark for defining "pathologic" sacroiliitis according to the histologic evaluation of needle biopsy samples acquired from sacroiliac joints.…”

Treatment of bone marrow lesions (bone marrow edema)

“…15 Similar observations were reported in patients with ankylosing spondylitis. 16 Impaired microcirculation causing increased intrasosseous pressure has also been invoked as a possible mechanism involved in the formation of BMLs, especially after renal transplantation. 17 Thus, the histological and biochemical marker profiles summarised above suggest that BMLs constitute a local area of high bone turnover with increased expression of cytokines and angiogenic factors.…”