IL-17 and Synoviocyte Survival Figure 7. Severity of chronic streptococcal cell wall-induced arthritis in wild-type (WT) or IL-17R 2/2 mice (A). A representative image of haematoxylin and eosin-stained synovial knee joint sections in WT or IL-17R 2/2 mice at day 42 after 5 repeated injections of streptococcal cell wall (SCW) fragments (magnification 640). Arthritis severity and inflammatory infiltrate were scored histologically in injected joints of WT or IL-17R 2/2 mice. Arthritis severity was scored on a scale of 0–2 and synovial infiltrate on a scale of 0–3. Results are expressed as mean 6 SEM of 2 separate experiments, n = 10 mice per group per experiment, * P,0.05 compared to WT mice. Synoviolin expression is reduced in IL-17R 2/2 mice with chronic SCW-induced arthritis (B). Synoviolin expression in sections of arthritic knee joints from, a wild-type (WT) or IL-17R 2/2 mouse after 5 repeated injections of SCW fragments (magnification x 40, day 42, n = 10 mice in WT or IL-17R 2/2 groups from 2 separate experiments). Synoviolin expression was quantified in 10 high power fields, averaged and expressed as the number of synoviolin positive cells/mm2, * P,0.05 compared to WT mice. Synovial apoptosis in WT or IL-17R 2/2 mice with chronic streptococcal cell wall-induced arthritis (C). A representative image of increased TUNEL staining in IL-17R 2/2 synovium (magnification 6200.). The number of TUNEL-positive cells was quantified in 10 high power fields, PLoS ONE | www.plosone.org 11 October 2010 | Volume 5 | Issue 10 | e13416