Lysozyme in preosseous cartilage

LYSOZYME IN EPIPHYSEAL CARTILAGE : IV. Embryonic Chick Cartilage Lysozyme-Its Localization and Partial Characterization

The localization of chick embryonic lysozyme was determined by two techniques: by studying the rate of release from the tissue during sequential enzymatic digestion and by immunocytochemistry. Both techniques indicate that, in this tissue, lysozyme is primarily extra-cellular. Cartilage lysozyme was isolated and partially characterized and found to be identical with egg white lysozyme in its immunologic and enzymatic behavior. In addition, a method for the isolation of large numbers of viable chondrocytes is described.

ENZYME ACTIVITIES IN CHICK EMBRYONIC CARTILAGE : Their Subcellular Distribution in Isolated Chondrocytes

Some characteristic enzymatic activities were determined in chick embryonic cartilage and compared with the analogous activities in bone and liver. Chondrocytes were isolated, broken by sonication, and subjected to subcellular fractionation to yield a nuclear pellet, the mitochondrial, lysosomal, and microsomal fractions, and the high speed supernatant solution. It was established that these fractions are characterized by enzymatic activities usually associated with similar fractions in other tissues, but with some quantitative differences. Lysozyme, a particulate-associated enzyme in other tissues, was not detected in any subcellular fraction even by the sensitive technique of microzone electrophoresis and is therefore considered to be primarily extracellular in cartilage.

Stimulation of spreading of trypsinized human fibroblasts by lysozymes from Staphylococcus aureus, hen egg white, and human urine

The effect of lysozyme from three different sources--Staphylococcus aureus, hen egg white, and human urine--on adhesion to substrate and spreading of trypsinized human fibroblasts was studied. Several fibroblast strains were tested under various conditions. It was found that the different cell strains did not show the same capability of spreading and stably attaching to substrates when resuspended in media not containing serum. Some strains did not spread, whereas others spread even in the absence of serum. Cell spreading in these strains did not occur when the cells were pregrown for 5 weeks in media supplemented with 1% fetal bovine serum. Lysozyme from S. aureus allowed stable adhesion to substrate and spreading of all the fibroblast strains unable to elongate in nonsupplemented minimal essential medium. This enzyme accelerated and augmented spreading of the strains capable of elongating in the absence of serum. S. aureus lysozyme also allowed spreading and stable adhesion to substrates of all these strains when they were pregrown for 5 weeks in the presence of 1% fetal bovine serum. Furthermore, hen egg white lysozyme and the lysozyme purified from human urine were both capable of stimulating anchorage to substrate and spreading of trypsinized fibroblasts although their effect was less pronounced than that of the S. aureus lysozyme. Some tentative hypotheses for the mechanism of cell spreading in the presence of lysozyme are made. The possibility that lysozymes, virtually ubiquitous enzymes, may play a specific role in nature in the regulation of cell differentiation and tissue development is finally raised and discussed in light of several previous observations and findings.

Correlation of lysozyme activity with proteoglycan biosynthesis in epiphyseal cartilage

Pig epiphyseal cartilage (proximal ulna epiphysis) previously incubated into vitro in the presence of sodium [35S]sulfate or [3H]thymidine was either analyzed by autoradiography or separated into 9 morphologically defined consecutive layers and investigated for 35S-incorporation into the guanidinium chloride-extractable proteoglycans and for lysozyme activity. The lowest 35S incorporation and lysozyme activity were determined in the zone of resting cells, but there is a consecutive increase in the rate of proteoglycan synthesis and lysozyme activity toward the diaphyseal cartilage-bone junction, with the maximum at the lower columnar cell zone and a sharp reduction of both parameters at the hypertrophic zone. The maxima of 35S incorporation and [3H]thymidine incorporation do not coincide. The guanidinium chloride-soluble proteoglycans exhibit macromolecular polydispersity. Fractions excluded from as well as retarded by Sepharose 2B gel could be separated and were detected in all zones. The results indicate a correlation of proteoglycan biosynthesis and lysozyme activity in epiphyseal cartilage.

Inhibition of new blood vessel formation in mice by systemic administration of human rib cartilage extract

1 M HCl-guanidine extract of human funnel chest rib cartilage administered i.v. to mice decreased specifically vasoproliferation induced by intradermal injection of allogeneic murine lymphocytes.

[Serum lysozyme concentrations in patients with morbus Crohn before and after bowel resection (author's transl)]

Serum lysozyme (muramidase) concentrations were determined in five patients with Morbus Crohn before and after resection of inflammated bowel areas. The serum lysozyme activity which was elevated before surgical treatment in all patients fell to normal values after bowel resection within a few hours. Our findings suggest, that the elevated serum lysozyme reflects an increased lysozyme production in the inflammated bowel tissue.

Connective tissue lysozyme in health and disease

As the lysozyme story continues to unfold, rheumatic disease is one area where the study of this fascinating protein will be most important. The special biochemical features of lysozyme--its hexosaminidase function, its ability to bring about transglycosylation, its homology to alpha-lactalbumin, and its cationic nature--suggest that the connective tissues may prove to be the key to the understanding of the function of lysozyme. As methods for its accurate measurement become standardized, better data on the activity of the enzyme in various tissues and body fluids, in both health and disease, will be forthcoming. As additional studies are done to ascertain which of the hypothetical functions attributed to lysozyme are of significance in vivo, it will be the student of the connective tissues and the diseases thereof who can be expected to profit most from an udnerstanding of the role of lysozyme in mammalian biology.

Secretory lysozyme of the human middle ear mucosa: immunocytochemical localization

Lysozyme was demonstrated by an immunocytochemical technique in the biopsied mucosa obtained from the promontory of the fifteen patients who had chronic middle ear effusions. Lysozyme was localized in the mucigen granules of the secretory cells, as well as in the specific granules of the polymorphonuclear neutrophilic leukobytes (PMN) and macrophages. The specimens obtained from patients with mucous effusion showed numerous secretory cells that contained lysozyme, in sharp contrast to the serous type in which only a few secretory cells could be found. The present morphological finding was in agreement with the biochemical finding which demonstrated higher lysozyme level in mucous effusions than that of the serous type. It was concluded that human middle ear mucosa provided lysozyme and that its secretion was active in serous otitis media, particularly of mucoid type.

Composition of cartilage from lysozyme-deficient rabbits

Costal and auricular cartilage obtained from mutant rabbits exhibiting lysozyme deficiency has been found to be identical to similar tissue from control animals in a variety of biochemical parameters. These data seriously question the putative role of lysozyme as a structural component of cartilage.

Effects of acute cartilaginous injury on serum and cartilage lysozyme levels

Acute cartilage degradation was produced in rabbits by the intravenous injection of crude papain. This resulted in a significant rise in serum lysozyme in 97% of the animals, as well as a fall in the residual lysozyme content of auricular and costal cartilage. The rise in serum lysozyme paralleled the rise in serum chondroitin sulfate. The source of the rise in lysozyme appeared to be the release of extracellular, nonlysosomal lysozyme from the cartilage matrix. Serum lysozyme elevation in arthritic disorders may reflect cartilage degradation.

Human cartilage lysozyme

The lysozyme content of human cartilage was measured by incubation of lyophilized, powdered cartilage in a variety of buffers and salt solutions, and the factors controlling the binding of lysozyme within cartilage were studied. Lysozyme was extracted from hyaline cartilage by buffers of pH greater than 9.0 by solutions 1 M in monovalent cations, and by solutions 0.12-0.40 M in divalent cations. The ability of cations to extract lysozyme from cartilage agreed with their known affinities for binding to chondroitin sulfate. The total extractable lysozyme content of five samples of human costal cartilage ranged from 1.45 to 3.36 mug lysozyme per mg of cartilage; for five samples of hyaline cartilage from peripheral joints the range was 0.80-3.03 mug lysozyme per mg of cartilage. Cartilage incubated in excess exogenous lysozyme could bind 0.053 equivalents of lysozyme per equivalent of chondroitin sulfate. Fibrocartilage and synovium from knee joints yielded no detectable lysozyme, despite the fact that synovium, a tissue rich in lysosomes, contained measurable quantities of beta-glucuronidase. Lysozyme extraction from cartilage was not augmented by incubation with streptolysin S. When incubation was carried out with mild extraction techniques, lysozyme extraction from cartilage tended to parallel uronic acid release, both as a function of time and from one specimen to another. The active material as lysozyme. Lysozyme occurs in human hyaline cartilage as a counterion to polyanionic glycosaminoglycans. Carextracted from cartilage met five criteria for identification tilage lysozyme appears to be extracellular and nonlysosomal. Degradation of cartilage may contribute to the increased serum and synovial fluid lysozyme levels often present in patients with rheumatoid arthritis.

Lysozyme in epiphyseal cartilage. II. The effect of egg white lysozyme on mouse embryonic femurs in organ cultures

Embryonic mouse femoral cartilage, like the epiphyseal cartilage of the calf scapula, contains large amounts of lysozyme. The addition of egg white lysozyme to organ cultures of embryonic mouse femurs induces unique alterations in the gross and microscopic morphology of the femurs. The sites of these alterations are precisely related to the natural distribution of lysozyme in calf scapula. If the exogenous lysozyme is withdrawn from the culture, the morphological changes disappear, accompanied by a resumption or derepression of growth. The effect on growth is evident only in 17-day embryos. These observations support the idea that lysozyme has a physiological role in cartilage, perhaps related to a regulatory mechanism in bone formation.