Type II and VI collagen in nasal and articular cartilage and the effect of IL-1α on the distribution of these collagens

Abstract

The distribution of type II and VI collagen was immunocytochemically investigated in bovine articular and nasal cartilage. Cartilage explants were used either fresh or cultured for up to 4 weeks with or without interleukin 1α (IL-1α). Sections of the explants were incubated with antibodies for both types of collagen. Microscopic analyses revealed that type II collagen was preferentially localized in the interchondron matrix whereas type VI collagen was primarily found in the direct vicinity of the chondrocytes. Treatment of the sections with hyaluronidase greatly enhanced the signal for both types of collagen. Also in sections of explants cultured with IL-1α a higher level of labeling of the collagens was found. This was apparent without any pre-treatment with hyaluronidase. Under the influence of IL-1α the area positive for type VI collagen that surrounded the chondrocytes broadened. Although the two collagens in both types of cartilage were distributed similarly, a remarkable difference was the higher degree of staining of type VI collagen in articular cartilage. Concomitantly we noted that digestion of this type of cartilage hardly occurred in the presence of IL-1α whereas nasal cartilage was almost completely degraded within 18 days of culture. Since type VI collagen is known to be relatively resistant to proteolysis we speculate that the higher level of type VI collagen in articular cartilage is important in protecting cartilage from digestion.

High resistance of the mechanical properties of the chondrocyte pericellular matrix to proteoglycan digestion by chondroitinase, aggrecanase, or hyaluronidase

“…With regard to HA, no discernible change in PCM morphology or PG content was observed following up to 10 hours of digestion with ovine testicular hyaluronidase (Poole et al, 1985), which has demonstrated activity toward both HA and chondroitin derivatives (Menzel and Farr, 1998). Similarly, other studies have shown little effect of Hyal or interleukin 1a treatment on collagen VI distribution of PCM architecture in articular cartilage (Jansen et al, 2010). However, collagenase digestion of articular cartilage completely degrades the ECM but leaves the chondron (chondrocyte and its PCM) intact, although the mechanical properties of the PCM are greatly reduced in this case (Guilak et al, 1999) as compared to the in situ properties (Darling et al, 2010) and those of mechanically isolated chondrons (Guilak et al, 2005).…”

Conversion of Carbon Dioxide into Methanol with Silanes over N‐Heterocyclic Carbene Catalysts

“…[21,22] More recently, Pitter and co-workers described the hydrosilylation of CO 2 catalyzed by ruthenium-acetonitrile complexes, yielding formoxysilanes. [23][24][25] Matsuo and Kawaguchi reported the homogeneous reduction of CO 2 with hydrosilanes catalyzed by zirconium-borane complexes, yielding methane. [26] The practicality of applications of these different systems was limited by their sensitivity to air and moisture, as well as the low activities of the organometallic catalysts.…”

“…In contrast, a zirconium catalyst [26] was reported to have TON and TOF values of only 92 and 0.54 h À1 , respectively, and ruthenium catalysts achieved values of 78-400 and 2.8-17 h À1 , respectively, at elevated temperatures and high CO 2 pressures (40 atm). [23][24][25] The reaction with the [Ir(CN)(CO)(dppe)] catalyst (dppe = (1,2-bis(diphenylphosphanyl)ethane)) produced a similar SiOMe end product with very low efficiency (TON = 2.28, TOF = 0.007 h À1 ). [22] These results demonstrate that nucleophilic NHC acts as an excellent CO 2 activator.…”

WISP‐2, an upregulated gene in hip cartilage from the DDH model rats, induces chondrocyte apoptosis through PPARγ in vitro

“…CD44 is a glycoprotein and able to bind to matrix molecules such as hyaluronic acid and laminin in the extracellular matrix . Type II collagen is the main component of the hyaline matrix of hyaline cartilage . In our work, chondrocytes were isolated from the acetabular cartilage complex and identified by immunofluorescence with CD44 antibody and collagen II antibody (Figure S2A) .…”

“…21,22 Type II collagen is the main component of the hyaline matrix of hyaline cartilage. 23,24 In our work, chondrocytes were isolated from the acetabular cartilage complex and identified by immunofluorescence with CD44 antibody and collagen II antibody ( Figure S2A). 25 To explore the effect of WISP-2 on chondrocyte apoptosis, the WISP-2 was overexpressed and knocked down in chondrocytes by 72 hours lentivirus infection.…”