Cytokine profile of autologous conditioned serum for treatment of osteoarthritis, in vitro effects on cartilage metabolism and intra-articular levels after injection

Marijn Rutgers,Daniël Bf Saris,Wouter Ja Dhert,Laura B Creemers

doi:10.1186/ar3050

Marijn Rutgers, Daniël Bf Saris + Show 2 more

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https://doi.org/10.1186/ar3050

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Abstract

IntroductionIntraarticular administration of autologous conditioned serum (ACS) recently demonstrated some clinical effectiveness in treatment of osteoarthritis (OA). The current study aims to evaluate the in vitro effects of ACS on cartilage proteoglycan (PG) metabolism, its composition and the effects on synovial fluid (SF) cytokine levels following intraarticular ACS administration.MethodsThe effect of conditioned serum on PG metabolism of cultured OA cartilage explants was compared to unconditioned serum. The effect of serum conditioning on levels of interleukin-1beta (IL-1β), IL-4, IL-6, IL-10, IL-13, interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), osteoprotegerin (OPG), oncostatin M (OSM), interleukin-1 receptor (IL-1ra) and transforming growth factor beta (TGF-β) were measured by multiplex ELISA. As TNF-α levels were found to be increased in conditioned serum, the effect of TNF-α inhibition by etanercept on PG metabolism was studied in cartilage explants cultured in the presence of conditioned serum. Furthermore, cytokine levels in SF were measured three days after intraarticular ACS injection in OA patients to verify their retention time in the joint space.ResultsPG metabolism was not different in the presence of conditioned serum compared to unconditioned serum. Levels of the anti-inflammatory cytokines IL-1ra, TGF-β, IL-10 as well as of pro-inflammatory cytokines IL-1β, IL-6, TNF-α and OSM were increased. IL-4, IL-13 and IFN-γ levels remained similar, while OPG levels decreased. TNF-α inhibition did not influence PG metabolism in cartilage explant culture in the presence of condtioned serum. Although OPG levels were higher and TGF-β levels were clearly lower in ACS than in SF, intraarticular ACS injection in OA patients did not result in significant changes in these cytokine levels.ConclusionsACS for treatment of osteoarthritis contains increased levels of anti-inflammatory as well as pro-inflammatory cytokines, in particular TNF-α, but conditioned serum does not seem to have a net direct effect on cartilage metabolism, even upon inhibition of TNF-α. The fast intraarticular clearance of cytokines in the injected ACS may explain the limited effects found previously in vivo.

Highlights

Intraarticular administration of autologous conditioned serum (ACS) recently demonstrated some clinical effectiveness in treatment of osteoarthritis (OA)
A pivotal role in the progression of OA has been assigned to the pro-inflammatory cytokine interleukin1β (IL-1β), which induces a cascade of inflammatory and catabolic events including the expression of cartilage degrading matrix metalloproteinases (MMP) [3], nitric oxygen (NO) production and prostaglandin E2 (PGE2) release [4], while inhibiting proteoglycan and collagen synthesis [5,6]
The current study aims to evaluate the direct in vitro effect of conditioned serum on cartilage proteoglycan metabolism, to further evaluate the composition of ACS and to examine to what extent intraarticular injection of ACS is reflected in cytokine level changes in human osteoarthritic synovial fluid

Summary

Introduction

Intraarticular administration of autologous conditioned serum (ACS) recently demonstrated some clinical effectiveness in treatment of osteoarthritis (OA). Osteoarthritis (OA)-associated cartilage degradation is mediated in part by cytokines and growth factors, excreted into the intraarticular environment by synoviocytes, activated immune cells, or by the articular cartilage itself [1,2]. As a consequence of monocyte activation during incubation of blood, antiinflammatory cytokines such as IL-13, which was shown to inhibit the production of IL-1β and enhance production of IL-1ra [24], and osteoprotegerin (OPG) [25], which protected cartilage in a murine model of surgically induced osteoarthritis from further degeneration [26], may be upregulated. In vivo, increased IL-1ra levels were found in equine synovial fluid 35 days after the last (of four) injections with ACS [14]

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