Biomechanical signals and the C-type natriuretic peptide counteract catabolic activities induced by IL-1β in chondrocyte/agarose constructs

Abstract

IntroductionThe present study examined the effect of C-type natriuretic peptide (CNP) on the anabolic and catabolic activities in chondrocyte/agarose constructs subjected to dynamic compression.MethodsConstructs were cultured under free-swelling conditions or subjected to dynamic compression with low (0.1 to 100 pM) or high concentrations (1 to 1,000 nM) of CNP, interleukin-1β (IL-1β), and/or KT-5823 (inhibits cyclic GMP-dependent protein kinase II (PKGII)). Anabolic and catabolic activities were assessed as follows: nitric oxide (NO) and prostaglandin E2 (PGE2) release, and [3H]-thymidine and 35SO4 incorporation were quantified by using biochemical assays. Gene expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), aggrecan, and collagen type II were assessed with real-time quantitative PCR (qPCR). Two-way ANOVA and the post hoc Bonferroni-corrected t tests were used to examine data.ResultsCNP reduced NO and PGE2 release and partially restored [3H]-thymidine and 35SO4 incorporation in constructs cultured with IL-1β. The response was dependent on the concentration of CNP, such that 100 pM increased [3H]-thymidine incorporation (P < 0.001). This is in contrast to 35SO4 incorporation, which was enhanced with 100 or 1000 nM CNP in the presence and absence of IL-1β (P < 0.001). Stimulation by both dynamic compression and CNP and/or the PKGII inhibitor further reduced NO and PGE2 release and restored [3H]-thymidine and 35SO4 incorporation. In the presence and absence of IL-1β, the magnitude of stimulation for [3H]-thymidine and 35SO4 incorporation by dynamic compression was dependent on the concentration of CNP and the response was inhibited with the PKGII inhibitor. In addition, stimulation by CNP and/or dynamic compression reduced IL-1β-induced iNOS and COX-2 expression and restored aggrecan and collagen type II expression. The catabolic response was not further influenced with the PKGII inhibitor in IL-1β-treated constructs.ConclusionsTreatment with CNP and dynamic compression increased anabolic activities and blocked catabolic effects induced by IL-1β. The anabolic response was PKGII mediated and raises important questions about the molecular mechanisms of CNP with mechanical signals in cartilage. Therapeutic agents like CNP could be administered in conjunction with controlled exercise therapy to slow the OA disease progression and to repair damaged cartilage. The findings from this research provide the potential for developing novel agents to slow the pathophysiologic mechanisms and to treat OA in the young and old.

Tissue-engineered cartilage with inducible and tunable immunomodulatory properties

“…NT and eGFP-expressing constructs secreted MMPs in response to IL-1 exposure, similar to native cartilage or meniscus explants [46, 52] or other engineered cartilage constructs [52, 53], which likely contributed to poor matrix accumulation in these samples. At 0.1 ng/mL IL-1, the IL-1-induced increase in MMP activity was fully blocked in IL-1Ra-expressing constructs.…”

“…Unlike cartilage explants [46] or chondrocyte-based engineered cartilage constructs [53], our engineered cartilage constructs with differentiating human MSCs expressed PGE 2 during chondrogenesis in the absence of IL-1. This finding is consistent with previous studies that showed human MSCs expressing PGE 2 during chondrogenesis in pellet culture [56, 57].…”

Anti-Inflammatory Strategies in Cartilage Repair

“…Ramachandran et al reported that treatment with C-type natriuretic peptide and dynamic compression increased anabolic activities and blocked catabolic effects induced by IL-1b. 93 For cyclic loading, however, the cartilage reaction is different; low frequencies and amplitudes do not appear to affect biosynthesis rates. Some studies suggested that, above a certain threshold frequency, cyclic loading increases the synthesis of components of ECM, such as aggrecans, cartilage oligomeric matrix protein, and fibronectin.…”

Maintaining the Phenotype Stability of Chondrocytes Derived from MSCs by C-Type Natriuretic Peptide

“…Manoj Ramachandran revealed that treatment with CNP can protect the cartilage matrix by reducing the release of nitric oxide (NO) and prostaglandin E2 (PGE 2 ) and blocked catabolic effects induced by interleukin-1 β (IL-1β) in a dose-dependent manner (Ramachandran et al, 2011; Peake et al, 2013). …”