Comparison of the Effects of Papain and Vitamin a on Cartilage

Abstract

The administration of large amounts of vitamin A to rabbits has been shown to result in depletion of cartilage matrix. The normal basophilic, metachromatic, and Alcian blue staining properties of the matrix are lost, especially in articular and epiphyseal cartilage. The cartilage cells remain intact, but are reduced in size. These changes sometimes appeared as early as 48 hours after the initiation of daily injection of 1 million units of vitamin A, and were usually well established by 5 days. Some rabbits failed to show changes in cartilage, even after 5 daily injections. Increased amounts of material presumed to be chondroitin sulfate were present in the sera of vitamin A-treated rabbits, usually by 72 hours after the first injection. This was demonstrated by a turbidimetric procedure using hexamminecobaltic chloride. In rabbits given sulfur-35 (Na2S35O4) 5 days before the initiation of vitamin A treatment, it was shown that sulfur-35 was lost from articular and epiphyseal cartilage. This was associated with an increase in the non-dialyzable sulfur-35 in both serum and in the cobalt-precipitable material. These rabbits also excreted more sulfur-35 than rabbits not given vitamin A. There was a reduction in sulfur-35 activity in chondromucoprotein extracted from the ear cartilage of vitamin A-treated rabbits. The changes are interpreted as indicating that the administration of large amounts of vitamin A to rabbits results in removal of chondroitin sulfate from cartilage matrix. The administration of small amounts of crude papain causes histologic changes in cartilage that are remarkably similar to those seen in vitamin A-treated rabbits. The possibility is suggested that the changes in cartilage produced by administration of vitamin A to rabbits may be the result of activation of a proteolytic enzyme or enzymes, with properties similar to those of papain.

The glycosaminoglycans of human plasma

“…In view of the well-known effects of papain on cartilage and connective tissue (21,29), our data indicate that both "free" and "bound" GAG are present in peripheral tissues; since the latter are more abundant, they are mobilized to a greater extent and constitute a larger aliquot of the plasma GAG. The fact that the specific activities of the "free" and "bound" GAG decline almost at the same rate after papain injection indicates that both pools are being diluted equally by the newly synthesized, nonradioactive tissue GAG.…”

Studies on Lysosomes. Ii. The Effect of Cortisone on the Release of Acid Hydrolases From a Large Granule Fraction of Rabbit Liver Induced by an Excess of Vitamin A*

“…This suggested that steroids given after the initial insult to the particles could still serve to stabilize the sys- (4,8). Yet this form of the vitamin, which is eventually stored as an ester in the liver, is unable to release acid protease from rat liver particles in vitro and is similarly inactive to causing damage to embryonic cartilage in organ culture (22).…”

“…Cortisone acetate in aqueous suspension 3 was given intramuscularly, 50 mg per kg, for 3 days. On day 4, 50 mg of hydrocortisone hemisuccinate (Solu-Cortef) 4 was given intravenously 30 minutes before death of animals by air embolus. For in vitro experiments, hydrocortisone was added to the whole homogenates 30 minutes before further fractionation.…”

“…Recent studies on the dissolution of cartilage matrix by vitamin A in vivo and in vitro have indicated that the vitamin acts, at least in part, by releasing endogenous acid proteases from cartilage cells (1)(2)(3)(4)(5). Dingle (6) found that vitamin A alcohol in vitro liberated acid protease(s) from a particulate fraction of rat liver homogenized in 0.25 M sucrose.…”

The Action of Cathepsin D in Human Articular Cartilage on Proteoglycans

“…In recent years lysosomal protease rather than hyaluronidase activity became the chief suspected agent of this degradation. Thomas, McCluskey, Potter, and Weissmann (6) and the Dingle group (7,8) gave the first clear demonstration that lysosomal protease(s) play a part in the degradation of embryonal chick cartilage matrix. They demstrated in organ cultures that excess vitamin A led to the release of lysosomal protease(s) and degradation of cartilage matrix.…”