Hyaluronan fragments activate nitric oxide synthase and the production of nitric oxide by articular chondrocytes

Abstract

Chondrocyte CD44 receptors anchor hyaluronan to the cell surface, enabling the assembly and retention of proteoglycan aggregates in the pericellular matrix. Hyaluronan-CD44 interactions also provide signaling important for maintaining cartilage homeostasis. Disruption of chondrocyte-hyaluronan contact alters CD44 occupancy, initiating alternative signaling cascades. Treatment with hyaluronan oligosaccharides is one approach to uncouple CD44 receptors from its native ligand, hyaluronan. In bovine articular chondrocytes, treatment with hyaluronan oligosaccharides or purified hyaluronan hexasaccharides induced the production of nitric oxide that mirrored nitric oxide production following interleukin-1 treatment. In contrast, 120 and 1260 kDa hyaluronan did not induce production of nitric oxide. Human chondrocytes responded similarly to treatment with hyaluronan or hyaluronan oligosaccharides. Nitric oxide production from chondrocytes was mediated by activation of the inducible nitric oxide synthase, as confirmed by mRNA expression and inhibition of nitric oxide production by diphenyleneiodonium. Cotreatment of chondrocytes with hyaluronan oligosaccharides and interleukin-1 did not demonstrate additive effects. Blocking interleukin-1 receptors with an antagonist did not abolish the production of nitric oxide induced by treatment with hyaluronan oligosaccharides. Moreover, only COS-7 following transfection with a pCD44, not the CD44-null parental cells, responded to treatment with hyaluronan oligosaccharides by releasing nitric oxide. This study demonstrates a novel signaling potential by hyaluronan fragments, in lieu of endogenous hyaluronan-chondrocyte interactions, resulting in the activation of inducible nitric oxide synthase.

Hyaluronic acid (hyaluronan): a review

“…A wide range of activities can be explained by a large number of Ha-binding receptors such as cell surface glycoprotein CD44, the receptor for hyaluronic acid-mediated motility (RHAMM), and several other receptors possessing Ha-binding motifs, for example: transmembrane protein layilin, hyaluronic acid receptor for endocytosis (HARE), lymphatic vessel endocytic receptor (LYVE-1), and also intracellular HA-binding proteins including CDC37, RHAMM/IHABP, P-32, and IHABP4 (Underhill, 1992;Forsberg et al, 1994;Pohl et al, 2000;Pure and Cuff, 2001;Toole, 2001;Weigel et al, 2002;Hascall et al, 2004;Hajjaji et al, 2005;Nawrat et al, 2005;Hill et al, 2006;Iacob and Knudson, 2006). It has been shown that the HA level is elevated in various cancer cells (Lin and Stern, 2001) and it is believed to form a less dense matrix, thus enhancing the cell's motililty as well as invasive ability into other tissues (Hill et al, 2006).…”

Hyaluronan differently modulates TLR‐4 and the inflammatory response in mouse chondrocytes

“…Studies on activated macrophages have shown that HA fragments induce the expression of chemokines such as macrophage inflammatory protein-1a/b, RANTES and monocyte chemotactic protein-1, the functions of which are crucial in initiating and maintaining the inflammatory response [16]. Furthermore, expression of hyaluronan synthase-2, aggrecan, matrix metalloproteinase-3/13, and inducible nitric oxide synthase have been stimulated by small HA fragments in various types of chondrocytes [17,18]. Short HA fragments have been reported to promote cell proliferation of chondrocytes [18], endothelial cells and fibroblasts.…”

Porphyromonas gingivalis, Gamma Interferon, and a Proapoptotic Fibronectin Matrix Form a Synergistic Trio That Induces c-Jun N-Terminal Kinase 1-Mediated Nitric Oxide Generation and Cell Death

“…In periodontal disease, PDL cell function is compromised as bacterial proteases destroy the integrity of the ECM and release fragmented adhesion molecules, including fibronectin fragments that induce apoptosis, into the inflammatory milieu. In addition, the degraded matrix molecules, like those from fibronectin and hyaluronan, may stimulate the resident cells around the sites of inflammation to produce proinflammatory cytokines and nitric oxide (6,28,30,31,34,56,67,76).…”