Table 1.
Clinical characteristics of RA patients in serum cohort.
Figure 1.
ANGPTL4 is expressed by osteoclasts in RA.
(A) ANGPTL4 is strongly expressed by osteoclasts (arrows) in the RA synovium. Inset: Representative isotype control image. (B) Resorbing osteoclasts adjacent to bone (starred) express ANGPTL4. (C) ANGPTL4 (red) expression co-localises with cathepsin K-positive (green) osteoclasts. Representative images from n = 3 cases. (D) Cathepsin K-positive (green) osteoclasts in the OA synovium do not express detectable ANGPTL4 (red). All scale bars represent 100 µM.
Figure 2.
HIF-1α is expressed by osteoclasts in RA.
(A) HIF-1α expression by osteoclasts in the RA synovium (arrows). Representative image from n = 3 cases. (B) HIF-1α (green) and ANGPTL4 (red) expression co-localises in 2 bone-apposing osteoclasts (arrows). All scale bars represent 100 µM. (C) ANGPTL4 (solid lines) and SLC2A1 (Glut-1; dashed lines) mRNA expression in monocyte-derived osteoclasts from RA patients following 24 h exposure to normoxia or hypoxia (2% O2). Hypoxic fold-change in mRNA expression; *, p<0.05.
Figure 3.
ANGPTL4 and HIF-1α are expressed in RA synovial tissue.
(A) The RA synovium is strongly positive for ANGPTL4, as are adjacent blood vessels and surrounding stromal cells; (B) normal synovium shows weak, heterogeneous expression of ANGPTL4. (C) RA synovium is strongly positive for HIF-1α, as are adjacent blood vessels; (D) normal synovium generally does not express HIF-1α. (E) Synovial lining cells and stromal cells adjacent to lymphoid aggregates express ANGPTL4. Inset: ANGPTL4-positive plasma cells. (F) ANGPTL4 (red) is not expressed by B cells (CD20, green). (G) ANGPTL4 (red) is expressed by CD68-positive (green) macrophages adjacent to a lymphoid aggregate. (H) The OA synovium expresses elevated levels of both ANGPTL4 (left panel) and HIF-1α (right panel) compared with the normal synovium. Scale bars (A–F, H) represent 100 µM, scale bar (G) represents 50 µM.
Figure 4.
Serum and synovial fluid ANGPTL4 concentrations are elevated in RA.
(A) Synovial fluid from RA patients contains more ANGPTL4 (203.3±264.8 ng/ml, range 68.7–847.3 ng/ml) than that from patients with non-inflammatory OA (64.4±13.6 ng/ml, range 50.4–82.2 ng/ml). *, p<0.05. (B) Serum from RA patients contains more ANGPTL4 (363.4±138.7 ng/ml, range 24.0–2235.0) than that from OA patients (39.0±3.4 ng/ml, range 11.9–100.5 ng/ml) or normal controls (45.8±6.7 ng/ml, range 6.5–154.7 ng/ml). **, p<0.01. (C) Serum from ‘high ANGPTL4’ RA patients is more likely to have detectable RANKL (black shading; RANKL-positive) than either serum from ‘low ANGPTL4’ RA patients or controls. White shading; RANKL-negative. *, p<0.05.