Human rIL-22 induced marked proliferation of FLS in PsA patients. FLS were isolated from synovial tissue of patients with psoriatic arthritis (PsA, n = 5). (A) FLS (20,000 cells/well) of PsA patients were seeded in a 24-well plate in triplicate and incubated for 5 days at 37°C in presence or absence of human rIL-22 (100 ng/ml), human rTNF-α (20 ng/ml) and combination of rIL-22 (100 ng/ml) + rTNF-α (20 ng/ml). FLS used in these experiments were between 3rd and 6th passage. MTT assay was done to determine FLS proliferation and results were expressed as Mean ± SEM of OD. (B) FLS (2 × 105 cells) of PsA patients were seeded in T25 flask in triplicate, stained with CFSE (2 μM) and incubated for 5 days at 37°C in presence or absence of human rIL-22 (100 ng/ml), human rTNF-α (20 ng/ml) and combination of rIL-22 (100 ng/ml) + rTNF-α (20 ng/ml). Data were acquired in FACScalibur flow cytometer and analysis was done using FlowJo software. Proliferation was measured in terms of percent of divided cells and data were expressed as Mean ± SEM. The bar diagram represents the percent divided cells of FLS in PsA patients. (C) A representative histogram showing the proliferative effect of different treatments (rIL-22, rTNF-α, rIL-22 + rTNF-α) compared to media in FLS obtained from PsA patients. Non parametric test, Friedman's ANOVA with Dunn's multiple comparison test was done to determine statistical significance.
Mitra et al. Arthritis Research & Therapy 2012 14:R65 doi:10.1186/ar3781