Figure 2 | Scientific Reports

Figure 2

From: ERAP1 deficient mice have reduced Type 1 regulatory T cells and develop skeletal and intestinal features of Ankylosing Spondylitis

Figure 2

Histopathologic evaluation of ankylosed intervertebral joints. Spines from 84-week-old WT and ERAP1−/− female mice (n = 3) were harvested, fixed, and stained. (a) Representative 10x H&E image of a WT L6/S1 joint demonstrating healthy annulus fibrosus (b), and nucleus pulposus (c). (d) Representative H&E of an ERAP1−/− L6/S1 joint demonstrating disruption of the disc by a large infiltrative mass of cells (black arrow and f) and ectopic bone (white arrows and e) within the joint. (e) 60x magnification of intervertebral bone formation with black arrows demonstrating osteocytes. Spines from 14-week-old male and female mice (n = 3) were harvested, fixed, and stained with anti-IgM, IL-23, TNFα, and F4/80 antibodies. Immunohistochemistry representative images at 20X magnification demonstrating IgM + deposits (white arrows) within the nucleus pulposus of L6/S1 joint in ERAP1−/− (h), but not in WT mice (g). Some cellular infiltrates in the nucleus pulposus within the L6/S1 joints of ERAP1−/− mice stained positive for F4/80 + (white arrows), indicating macrophages (j), but not in WT mice (i). IL-23 positive staining of the L6/S1 nucleus pulposus infiltrate in ERAP1−/− (l), but not in WT (k). TNFα positive staining of the nucleus pulposus in ERAP1−/− (n) but not in WT L6/S1 joint (m).

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