Skip to main content
. 2018 May 16;9:962. doi: 10.3389/fimmu.2018.00962

Figure 4.

Figure 4

ST2 deficiency enhances NO production by neutrophils and macrophages and reduces Staphylococcus aureus-induced septic arthritis. NO production was determined as nitrite concentration by Griess reagent in the culture supernatant of (A) neutrophils and (B) bone marrow-derived macrophages (BMDMs) cells from wild-type (WT) or ST2 −/− naïve mice preincubated in vitro with interferon-γ (IFN-γ) (100 IU/ml, 1 h) or medium, followed by incubation with S. aureus, or (C) in the culture supernatant of macrophages like-cells isolated from peritoneal cavity of WT or ST2−/− mice with staphylococcal arthritis and challenged with lipoteichoic acid (LTA) (10 µg/ml, a toll-like receptor 2 agonist) plus IFN-γ (100 UI/ml) for 48 h. S. aureus or saline (day 0) was injected in the femur-tibial joint of WT and ST2−/− mice and knee joint samples were collected and processed to determine: (D) the mRNA and (E) protein expression of iNOS at indicated time points post-infection by qPCR and Western Blot, respectively. WT and ST2−/− mice were treated with aminoguanidine (AMG, 30 mg/kg, s.c., 150 µl) or vehicle (saline, 150 µl) over 28 days after i.a. S. aureus [107 colony-forming unity (CFU)/10 μl/joint] injection: (F) mechanical hyperalgesia, (G) articular edema, and (H) clinical severity score were evaluated over 27 days post-bacterial infection. At the 28th day post-infection, (I) leukocyte recruitment to the articular cavity, (J) bacterial counts in knee joint cavity and (K) spleen, and (L) proteoglycan content in patella samples were determined. N = 6 per group per in vivo experiment or N = 4 per group for WB analysis and samples were pooled from 10 mice per in vitro experiment. *P < 0.05 vs WT neutrophils or BMDM group preincubated with only medium, or vs mice naïve group; #P < 0.05 vs WT and ST2−/− neutrophils or BMDM group preincubated with only medium, or vs WT mice group (A–E). *P < 0.05 vs naïve mice group; #P < 0.05 vs ST2−/− + saline mice group vs WT + saline mice group; **P < 0.05 WT + AMG mice group vs WT + saline mice group; ##P < 0.05 ST2−/− + AMG mice group vs ST2−/− + saline mice group (F–L). Representative of two independent experiments. One-way ANOVA followed by Tukey’s test.