Abstract
Cytokine regulation of synovial fluid (SF) lubricants, hyaluronan (HA), and proteoglycan 4 (PRG4) is important in health, injury, and disease of synovial joints, and may also provide powerful regulation of lubricant secretion in bioreactors for articulating tissues. This study assessed lubricant secretion rates by human synoviocytes and the molecular weight (MW) of secreted lubricants in response to interleukin (IL)-1β, IL-17, IL-32, transforming growth factor-beta 1 (TGF-β1), and tumor necrosis factor-alpha (TNF-α), applied individually and in all combinations. Lubricant secretion rates were assessed using ELISA and binding assays, and lubricant MW was assessed using gel electrophoresis and Western blotting. HA secretion rates were increased ∼40-fold by IL-1β, and increased synergistically to ∼80-fold by the combination of IL-1β + TGF-β1 or TNF-α + IL-17. PRG4 secretion rates were increased ∼80-fold by TGF-β1, and this effect was counterbalanced by IL-1β and TNF-α. HA MW was predominantly <1 MDa for controls and individual cytokine stimulation, but was concentrated at >3 MDa after stimulation by IL-1β + TGF-β1 + TNF-α to resemble the distribution in human SF. PRG4 MW was unaffected by cytokines and similar to that in human SF. These results contribute to an understanding of the relationship between SF cytokine and lubricant content in health, injury, and disease, and provide approaches for using cytokines to modulate lubricant secretion rates and MW to help achieve desired lubricant composition of fluid in bioreactors.
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
