Secretion and localization of cathepsin D in synovial tissues removed from rheumatoid and traumatized joints. An immunohistochemical study

Abstract

The proteinase cathepsin D which degrades proteoglycan was never demonstrated in extracellular sites in tissues from patients with traumatized meniscoid cartilage, either before or after culture with an antiserum to human cathepsin D. In contrast, in synovia (but not usually cartilage) from the knees of 6 of 11 rheumatoid patients, extracellular cathepsin D was commonly detected by culturing tissues with an antiserum to this enzyme.

Cathepsin D: Cleavage of soluble collagen and crosslinked peptides

“…The ability to depolymerize crosslinked peptides, together with its known extracellular occurrence [2], make cathepsin D a strong candidate for involvement in collagen degradation in vivo. In support of this we have recently found (P.G.S.…”

“…It has been shown to occur extracellularly in connective tissues [2] where, notwithstanding its low pH optimum, it has been implicated in the destruction of proteoglycans [3]. Previous authors reported little [4] or no [5] effect on gelatin and no cleavage of the fl or y components of soluble collagens [.5].…”

Cathepsin D—Many functions of one aspartic protease

“…Endocytosed pCD undergoes further maturation into 48 kDa intermediate and 34 kDa and 14 kDa forms [26,27]. CD expression and activity was also detected in extracellular matrix and synovial fluid of cartilage during physiological and pathological conditions [28][29][30][31]. pCD and mature CD was also found in macrophage-conditioned media and extracellularly in macrophage-rich regions of atherosclerotic lesions [32].…”

Submicroscopic Structure of the Human Synovial Membrane

“…A finely granular, moderately osmiophil substance occurs frequently in the vesicles. According to literary data (Barland et al 1962, Rayns and Highton 1966, Roy 1966, Ghadially and Roy 1967b, Huth et al 1973, Klein 1974, Maldyk et al 1974, Poole et al 1976) the largely developed Golgi complex is one of the basic characteristics of A cells of the synovial membrane.…”

“…In the same year Coulter (1962) published a study about the human synovial membrane. Of all the numerous later publications we mention the studies of Rayns.and Highton (1966), Roy (1966), Roy et al (1966), Roy (1967b, 1969), Bozdech and Horn (1970), Huth et al (1973), Klein (1974), Maldyk et al (1974), Wolf (1974a, b), Poole et al (1976) and others. Not only do these authors bring new knowledge about the structure of the synovial membrane under normal conditions, but they compare its appearance and fine structure under some pathological conditions and/or under experimental conditions, or they deal with the function of the synovial membrane (Maibach 1953, Castor 1960, Hamermann et al 1961, Ball et al 1964, Cochrane et al 1965, Adam 1966, Vainio 1966, Ghadially and Roy 1967a, Luckenbill and Cohen 1967, Muirden and Senator 1968, Webb et al 1969, Bhawan et al 1973, Cchiu 1975.…”