Figure 3. Inhibition of PARP-1 downregulates Th1-mediated response in CIA.

DBA1 mice with established CIA were injected i.p. either with PBS (control) or with AIQ (1.5 mg/kg) on day 25 post-immunization. A. Proliferative response and cytokine production of DLN cells isolated at day 30 from untreated (control) or AIQ-treated CIA mice were determined after in vitro stimulation with different concentrations of CII. Stimulation of DLN cells with anti-CD3 antibodies (▾, for untreated CIA mice; ▿, for AIQ-treated CIA mice) was used for assessment of nonspecific stimulation. A pool of 3 nonimmunized DBA/1 DLN cells was used for assessment of the basal response. No proliferation or cytokine production by T cells was detectable in the presence of an unrelated antigen (OVA). n = 5 mice/group. B, Number of CII-specific cytokine-producing T cells. DLN cells from untreated (control) or AIQ-treated CIA mice were restimulated in vitro with CII (10 µg/ml) and analyzed for CD4 and intracellular cytokine expression in gated CD4 T cells by flow cytometry. Dot plots show representative double staining for IFNγ/TNFα or IL-4/IL-10 expression in gated CD4 T cells. The number of IFNγ-, IL-4- and IL-10-expressing T cells relative to 10⁴ CD4 T cells is shown in the lower panel. Data shown represent pooled values from two independent experiments. C, CII-specific proliferative response and the number of cytokine-producing CD4 T cells were determined in synovial membrane cells isolated from untreated (control) or AIQ-treated CIA mice and stimulated in vitro with CII (10 µg/ml) for 48 h. Data show the results of pooled synovial cells from 3 animals per group. D. AIQ decreases titter of autoantigens in CIA mice. The levels of CII-specific IgG, IgG1 and IgG2a antibodies in sera collected at day 35 were determined by ELISA. n = 3-5 mice/group. *p<0.001 versus controls.