Background and Objectives Adipose-derived stem cells (ASCs) have immunomodulatory properties and are intensively studied as a potential therapeutical method to treat rheumatoid arthritis (RA). ASCs immunosuppressive function may be affected by adipocytokines released by intra-articular adipose tissue. Knowing that inflammatory conditions may alter immunoregulatory properties of ASCs, we aimed to verify if there are any differences between ASCs derived from RA and osteoarthritis (OA) patients regarding their influence on synovial fibroblasts (FLS) and peripheral blood mononuclear cells (PBMC). The effect of selected adipocytokines were also analysed.
Materials and Methods Infrapatellar fat pad and synovial membrane were obtained from RA and OA patients during total knee joint replacement surgery. PBMC were obtained from buffy coats of healthy donors. ASCs were isolated and cultured with/without: medium/high molecular weight adiponectin (MMW/HMW), TNFα or IFNγ. The influence of ASCs on FLS and PBMC was assesed in co-cultures. PBMC, RA-FLS and OA-FLS were co-cultured with RA- or OA-ASCs. 24h after ASCs stimulation, PBMC/RA-FLS/OA-FLS were added to ASCs and cultured 72h. FLS proliferation was assessed by BrdU incorporation test, MMP-3 and IL-6 concentration was measured in FLS culture supernatants (SNs). Concentration of IL-10, TGFβ and RANTES was measured in PBMC culture SNs.
Results We did not observe any differences in proliferation rate and cytokines secretion between variants of FLS co-cultures (RA-FLS + RA-ASCs vs. RA-FLS + OA-ASCs vs. OA-FLS + OA-ASCs vs. OA-FLS + RA-ASCs). FLS proliferation as well as MMP-3 and IL-6 secretion seemed to be not affected by co-culture with unstimulated/stimulated ASCs.
By contrast, PBMC co-cultured with ASCs responded by significant up-regulation of RANTES and IL-10 production (p < 0.05). ASCs themeselves secreted negligible amounts of these cytokines, except for TNF-stimulated ASCs, which increased considerably RANTES release (23 ng/ml vs. 530 ng/ml in RA-ASCs and 18 ng/ml vs. 780 ng/ml in OA-ASCs). TGFβ secretion by co-cultured cells didn't increase considerably comparing to ASCs cultured alone (600-700 ng/ml vs. 700-800 ng/ml), which may indicate that PBMC and ASCs cutlured together decrease TGFβ production.
Conclusions Analysis of ASCs influence on FLS and PBMC did not show any differences between cells derived from RA and OA. We didn't observe any strong differences regarding adipocytokines role in ASCs activity. Neverthless, we showed that ASCs from both diseases have the impact on cytokines secretion by PBMC.
Funding Grant No. 2011/01/N/NZ5/00932, National Science Center, Poland.