In contrast to former findings lysozyme was able to attack the cell walls of Staphylococcus aureus under acid conditions. However, experiments with 14C-labelled cell walls and ribonuclease indicated that, under these conditions, lysozyme acted less as an muralytic enzyme but more as an activator of pre-existing autolytic wall enzymes. Electron microscopic studies showed that under these acid conditions the cell walls were degraded by a new mechanism (i.e. "attack from the inside"). This attack on the cell wall started asymmetrically within the region of the cross wall and induced the formation of periodically arranged lytic sites between the cytoplasmic membrane and the cell wall proper. Subsequently, a gap between the cell wall and the cytoplasmic membrane resulted and large cell wall segments became detached and suspended in the medium. The sequence of lytic events corresponded to processes known to take place during wall regeneration and wall formation. In the final stage of lysozyme action at pH 5 no cell debris but "stabilized protoplasts" were to be seen without detectable alterations of the primary shape of the cells. At the same time long extended ribbon-like structures appeared outside the bacteria. The origin as well as the chemical nature of this material is discussed. Furthermore, immunological implications are considered.

Various polyelectrolytes were investigated regarding their capacity to inhibit the binding of human IgG to Fc-receptors on group A streptococci, type M1. Of cationic substances, protamine and arginine-rich histone inhibited significantly, while lysine-rich histone, concanavalin A, lysozyme, polymyxin B, ribonuclease and tuftsin did not. Of anionic materials, liquoid was inhibitory, in contrast to chondroitin sulphate, dextran sulphate, DNA and heparin. Washing experiments showed that the inhibition was caused by binding of the polyelectrolytes to the streptococci. The finding that heated IgG inhibited the binding of histone to the streptococci also indicated a close relation between the binding sites for these compounds. Diffusion-in-gel experiments with alkaline extract of M1 demonstrated that the substances blocking the IgG Fc-receptor were bound to polyglycerophosphate, suggesting that the inhibition of the IgG uptake was due to interaction with lipoteichoic acid. Leukocyte and platelet extracts could modify the binding of IgG, probably by an enzymatic digestion of the receptors. The arginine-rich histone was also capable of inhibiting the binding of IgG to type M15 group A streptococci and to one group G strain. However, the polyelectrolytes had no effect on the binding of IgG to Staphylococcus aureus or of IgA to type 4 group A streptococci.

Human blood leukocytes and platelets and mouse peritoneal macrophages emit very rapid and very intense Luminol-dependent chemiluminescence (CL) signals when treated with streptococci, staphylococci, or with zymosan, which have been preopsonized with arginine-rich histone, dextran sulfate or polyanetholesulfonate (liquoid). Liquoid alone at 10-30 micrograms/2 X 10(5) leukocytes also triggers intense CL responses in the absence of a carrier. Strong CL can also be triggered, and at the same levels, when the various polyelectrolytes are simply mixed with the bacteria or zymosan and added to the leukocyte suspensions. The CL responses induced by the polyelectrolyte-bacteria complexes greatly exceed those triggered in leukocytes by antibody-complement-coated particles. Liquoid also shows a unique property of markedly augmenting CL signals which have already been induced by other ligand-coated bacteria or zymosan particles. Streptococci and staphylococci were found to be much superior to zymosan, Gram-positive bacilli, or E. coli as carriers for the various polyelectrolytes in the CL reaction. Neither protamine sulfate, lysozyme, myeloperoxidase, crystalline ribonuclease (all cationic in nature), chondroitin sulfate, heparin, nor alginate sulfate acted as ligands for triggering CL, when used to opsonize bacteria or zymosan. The induction of CL in blood leukocytes by the various ligand-coated bacteria is markedly inhibited by azide, KCN catalase, aminotriazole, and EDTA, agents known to inhibit the production of oxygen radicals following stimulation of leukocytes by opsonized bacteria. Two children diagnosed for chronic granulomatous diseases (CGD) of childhood and an apparently healthy sister of one of the male patients completely failed to respond with CL either to the polyelectrolyte-bacteria complexes, liquoid or antibody-coated bacteria and zymosan. It is proposed that liquoid be employed for the rapid screening of defects in certain oxygen-dependent metabolic processes in both PMNs and macrophages. It is also suggested that polyelectrolytes like the ones described in this study may markedly enhance the bactericidal properties of leukocytes and macrophages towards both extracellular and intracellular microorganisms and may perhaps also augment the tumoricidal effects of activated macrophages.

Effect of leukocyte hydrolases on bacteria XVI. Activation by leukocyte factors and cationic substances of autolytic enzymes in Staphylococcus aureus: modulation by anionic polyelectrolytes in relation to survival of bacteria in inflammatory exudates. The mechanisms involved in the activation of autolytic enzymes in Staphylococcus aureus, by leukocyte extracts, cationic proteins, phospholipase A2, amines, and membrane-damaging agents was studied in a resting cell system as well as by growing staphylococci. The bacteria were labeled with [14C]N-acetylglucosamine and were subjected to a variety of agents either in 0.1 M acetate buffer, pH 5.0, or in phosphate buffer, pH 7.4. While intact log-phase cultures were found to undergo partial autolysis at pH 5.0 and almost complete lysis at pH 7.4, both heat-killed bacteria and bacterial cell walls were completely resistant to autolysis in buffers. Autolysis at pH 5.0 can be further activated by leukocyte extracts, nuclear histone, crystalline ribonuclease, egg-white and human lysozyme, phospholipase A2, as well as by spermine, spermidine, and polymyxins B and E. The addition of viable log-phase bacteria to radiolabeled heat-killed staphylococci or to radiolabeled cell walls which had been cleaned off autolytic enzymes resulted in degradation of the radiolabeled targets. The data suggest that the various inducers of autolysin activation caused leakage of autolytic enzymes from the intact bacteria which attacked the depolymerized the bacterial cell walls. Anionic polyelectrolytes like heparin, dextran sulfate, suramine, polyglutamic acid, and liquid (polyanethole sulfonic acid) markedly inhibited both spontaneous and induced lysis. Staphylococci which had grown in the presence of anionic polyelectrolytes became highly resistant to lysis triggered by any of the inducers of autolysis. Since inflammatory exudates are known to be rich in anionic polyelectrolytes, it is suggested that the prolonged survival of intact bacterial cells in such a milieu may be due to the inactivation of autolytic enzymes. It is also postulated that the degradation of certain bacterial species following phagocytosis or extracellular degradation may not be the result of the action of hydrolytic enzymes but rather the result of activation by leukocyte factors of autolytic enzymes which lead to bacteriolysis.

Mechanisms of biodegradation of staphylococci by leukocyte factors and its modulation by serum proteins, inflammatory exudates, polyelectrolytes, antibiotics and by lipoteichoic acid: Relation to chemotaxis and to the survival of bacteria in inflammatory sites After phagocytosis of opsonized and non-opsonized bacteria by phagocytes, there is fusion of lysosomes discharge of lysosomal factors into phagosomes and activation of metabolic pathways leading to the generation of hydrogen peroxide, singlet oxygen, and other oxygen radicals, and death of the engulfed bacteria. Although much is known today about the mechanism by which phagocytes kill bacteria following phagocytosis, very little is known about the mechanisms of biodegradation of the engulfed bacteria. Biodegradation of bacteria within PMN involves action of lysosomal enzymes, neutral protease collagenases and proteases as well as reactive oxygen radical and release of these products from phagocytes may lead to destruction of host tissue. The propagation of chronic inflammatory sequellae following infections with staphylococci may also be mediated by delayed and immediate hypersensitivity reactions. Degradation of products of microbes also may diffuse into tissue and the chemotactic properties of these exudates attracts more phagocytic cells. Inflammatory exudates induced by bacterial infections are rich in acid and neutral hydrolases of leukocyte origin as well as bacterial products. The purpose of the present communication is to summarize several years of investigation of the pathogenesis of staphylococcal lesions with emphasis on the role played by anionic and cationic polyelectrolytes and degradation products of bacteria in the modulation of leukocyte-bacteria interactions (10, 14).

A variety of cationic polyelectrolytes opsonized group A streptococci andCandida albicans to phagocytosis by human polymorphonuclear leukocytes and by mouse peritoneal macrophages. The most potent opsonins for streptococci were specific antibodies supplemented with complement, nuclear histone, polylysine, polyarginine, ribonuclease, leukocyte lysates, leukocyte cationic protein and, to a lesser extent, lysozyme and myeloperoxidase. Histone, RNAse, leukocyte extracts, and platelet extracts also functioned as opsonins for phagocytosis of streptococci in the peritoneal cavity, where phagocytic indices, higher than those obtained for the in vitro phagocytosis, were obtained. Fresh serum, polylysine, polyarginine, and nuclear histone acted as good opsonins forCandida, but none of the other factors tested were active. In order for the cationic proteins and leukocyte extracts to function as opsonins, they must be present on the particle surface. These agents were poor opsonins when applied on the macrophages. Nuclear histone, polylysine, polyarginine, and fresh human serum also functioned as good opsonins for the uptake ofCandida by mouse fibroblasts. On the other hand, none of the other substances which opsonized streptococci were effective withCandida. The phagocytic capabilities of fibroblast polykaryons were much higher than those of ordinary spindle-shaped mouse fibroblasts. Histone also functioned as a good opsonic agent for the uptake ofCandida by human fibroblasts, HeLa cells, epithelial cells, monkey kidney cells, and rat heart cells. On the other hand, neither leukocyte extracts nor ribonuclease LCP or MPO functioned as opsonins for these mammalian cells.Candida, taken up by fibroblasts, were present within tight phagosomes, but no fusion of lysosomes with the phagosome occurred. A small proportion of the internalized yeast cells underwent partial plasmolysis, but little damage to the rigid cell walls was observed within 24–48 h of internalization. Phagocytosis of streptococci andCandida by macrophages and the uptake ofCandida by fibroblasts were both strongly inhibited by liquoid (polyanethole sulfonic acid sodium salt). This anionic polyelectrolyte also markedly inhibited the release ofN-acetylglucosaminidase from macrophages without affecting cell viability (LDH release). Hyaluronic acid, DNA, and dextran sulfate markedly inhibited the uptake of histone-coated particles by macrophages. On the other hand, hyaluronic acid and DNA enhanced the uptake ofCandida by fibroblasts. The effect of these anionic polyelectrolytes on phagocytosis of serum-opsonized particles by macrophages was not consistent. While in some experiments it blocked phagocytosis, in others it either had no effect or even enhanced the uptake of the particles. Phagocytosis of microorganisms by “nonprofessional” phagocytes like fibroblasts and the paucity in these cells of hydrolases capable of breaking down microbial cell wall components may contribute to the persistence of non-biodegradable components of bacteria in tissues and to the perpetuation of chronic inflammatory sequellae. Cationic polyelectrolytes may also prove important as “helper” opsonins and as agents capable of enhancing the penetration into cells of both viable and nonviable particles, genetic material, and drugs.

We investigated the bacteriolytic activity of gingival crevicular fluid (CF) on 14C-labeled Streptococcus faecalis, Streptococcus mutans, Staphylococcus aureus, and on whole dental plaque. CF was collected from 100 healthy donors pooled and centrifuged at 200 g. CF supernate and a frozen and thawed extract of the pellet were interacted with the different bacterial strains, while Streptococcus faecalis and Staphylococcus aureus released 60% and 75% of the radioactive label, only 38% of it was solubilized from Streptococcus mutans, following their incubation with the CF supernate. The findings agreed with results obtained by interacting bacteria with a frozen and thawed lysate of human peripheral blood leukocytes. On the other hand, extracts from frozen and thawed CF pellet were inactive. Further, lipoteichoic acid and lipopolysaccharide were released by CF from Gram-positive and Gram-negative bacteria, respectively. The role of bacteriolytic factors, present in CF, as a result of the interaction between microorganisms and leukocytes at inflammatory sites is discussed.

Streptococcal and staphylococcal arthritis: can chronic arthritis in the human be caused by highly chemotactic degradation products generated from bacteria by leukocyte enzymes and by the deactivation of leukocytes by inflammatory exudates, polyelectrolytes, leukocyte hydrolases and by cell sensitizing agents derived from bacteria?

Human polymorphonuclear leukocytes (PMN) chemotaxis was tested during exposure to leukocyte and platelet extracts, a variety of polyelectrolytes, inflammatory exudates, and bacterial products. The chemoattractants employed were either zymosan-activated serum or supernatant from autolyzed Staphylococcus aureus. Chemotaxis to both chemoattractants was markedly inhibited by leukocyte and platelet extracts; inflammatory exudates; anionic polyelectrolytes, DNA, hyaluronic acid, liquoid; and by cationic polyelectrolytes, histone, protamine base, protamine sulfate, and myeloperoxidase. Inhibition was also found with elastase, collagenase, pepstatin, and epsilon-amino-caproic acid. Bacterial products, such as lipoteichoic acid and lipopolysaccharides, and extracts of human dental plaque inhibited chemotaxis. No inhibition of chemotaxis was observed with heparin (< 10 micrograms/ml), chondroitin sulfate, phosphatidylethanolamine and phospatidylserine. Indeed, chondroitin sulfate markedly enhanced chemotaxis and antagonized the inhibitory effect of leukocyte or platelet extract. None of the agents employed was toxic to PMN as judged by trypan blue exclusion. These observations suggest that cationic polyelectrolytes and inflammatory exudates influence PMN surfaces, modifying interaction with chemoattractants. Assessment of the role of PMN chemotaxis in host defense against microbial invaders requires evaluation of the response in the presence of agents likely to be present in inflamed tissues.

Effect of leukocyte hydrolases on bacteria. XIII. Role played by leukocyte extracts, lysolecithin, phospholipase a2, lysozyme, cationic proteins, and detergents in the solubilization of lipids from Staphylococcus aureus and group A streptococci: relation to bactericidal and bacteriolytic reactions in inflammatory sites The bactericidal and bacteriolytic effects of lysolecithin (LL) and egg-white lysozyme (LYZ) on Staph. aureus and group A streptococci and the solubilization of phospholipids from the bacterial membranes by these agents was studied. Low concentrations of lysolecithin (1--10 microgrames/ml) are highly bactericidal for Steph. aureus and group A streptococci, but induce neither bacteriolysis nor solubilization of a substantial amount of membrane phospholipids. On the other hand, while LL at greater than 50 micrograms/ml causes substantial lipid release, a combination of LL and LYZ is absolutely needed to solubilize lipids from streptococci. This combination is, however, not bacteriolytic for this microrganism. The solubilization of lipids from staphylococci by LL is much faster than that induced in streptococci by LL + LYZ. The solubilization of the bulk of membrane lipids from staphylococci can also be achieved by Triton X-100 and by sodium lauryl sulfate and from group A streptococci by Triton X-100 plus LYZ. A variety of other detergents (e.g., Cetavlon, sodium taurocholate, cetyl pyrdinium chloride) have no lipid-releasing properties even in the presence of LYZ. The release of lipids by LYZ (in the presence of LL) from group A streptococci is related to its enzymatic activity, on a still unknown substrate, but not to its cationic nature as this muramidase cannot be replaced by a variety of cation substances (histone, polylysin, leukocyte cationic proteins, polymyxin B, and spermidine). The release of lipids from staphylococci by LL is not inhibited by a variety of anionic and cationic polyelectrocytes (heparin, liquoid, chondroitin sulfate, DNA histone, and polylysine) which markedly inhibit the release of lipids from group A streptococci by LL and LYZ. Streptococci that had been cultivated in the presence of subinhibitory concentrations of penicillin G lose their membrane phospholipids to a larger extent and by much smaller concentrations of LL and LYZ, as compared to controls, suggesting that the interference with the synthesis of the peptidoglycan increases the accessibility of the cell membrane to the lipid-releasing agents. The mechanism by which LL collaborates with LYZ in lipid release is still not known. The possible role of bacterial lipids and lyso compounds in the control of bacterial survival in inflammatory sites is briefly discussed.

Leukocyte extracts, trypsin, and lysozyme are all capable of releasing the bulk of the LPS from S. typhi, S. typhimurium, and E. coli. Bacteria which have been killed by heat, ultraviolet irradiation, or by a variety of metabolic inhibitors and antibiotics which affect protein, DNA, RNA, and cell wall synthesis no longer yield soluble LPS following treatment with the releasing agents. On the other hand, bacteria which are resistant to certain of the antibiotics yield nearly the full amount of soluble LPS following treatment, suggesting that certain heatlabile endogenous metabolic pathways collaborate with the releasing agents in the release of LPS from the bacteria. It is suggested that some of the beneficial effects of antibiotics on infections with gram-negative bacteria may be the prevention of massive release of endotoxin by leukocyte enzymes in inflammatory sites.

Normal sera and plasma, derived from humans, calves, rats, rabbits, horses, human synovial fluids, inflammatory exudates, and leukocyte extracts, when sufficiently diluted are highly bacteriolytic for Staph, aureus, Strep. faecalis, B. sutilis and to a variety of gram-negative rods. On the other hand, concentrated serum or the other body fluids are usually not bacteriolytic for these bacterial species. While the lysis of Staph, aureus and B. subtilis by diluted serum is not lysozyme dependent, lysis of Strep. faecalis is absolutely dependent on the concentration of lysozyme. The lytic factor in human serum is present in Cohn's fractions III, IV, and V. It is nondialyzable, resistant to heating for 75 degrees C and 20 min, and acts optimally at pH 5.0. Like leukocyte extracts, synovial fluids, and inflammatory exudates, it lyses only young staphylococci. The inability of concentrated serum to lyse Staph. aureus and Strep. faecalis is due to the presence in the gamma globulin fraction of a potent inhibitor, which can be partly removed by dilution of by adsorption upon the homologous bacteria. Lysis of the bacteria is also strongly inhibited by Cohn's fraction II (gamma globulin) by high-molecular-weight DNA, heparin, liquoid, and histone. The possible role played by serum globulin in the protection of bacteria against degradation by leukocyte is discussed.

Severe inflammatory lesions were induced in the periodontal tissues of the rat following the intragingival injection of lipoteichoic acid (LTA) from Streptococcus mutans. There was no difference in the severity and distribution of the lesions between nonimmunized rats and animals immunized against LTA after antigenic challenge. The lesions are characterized by the occurrence of granulation tissue, massive infiltration of PMNs, abscess formation, bone resorption, and new bone formation. Deacylated LTA and saline caused relatively mild inflammation, and no significant bone resorption or new bone formation was evident. The peak response was reached after 3 intragingival infections. The mechanisms by which LTA caused the pathological alterations in the rat periodontium and the possible relations of this experimental model to periodontal disease in the human are discussed.

The effect of leukocyte hydrolases on bacteria - XII. The release of lipopolysaccharide (LPS) from Salmonella typhi by leukocyte extracts, lysozyme, inflammatory exudates and by serum and synovial fluid and the modulation by anionic and cationic polyelectrolytes of LPS release and the sensitization of erythrocytes

A Staph, aureus mutant (52A5) which is deficient in wall teichoic acid (TA) was found to be highly susceptible to lysis by leukocyte extracts (ENZ) and by myeloperoxidase (MPO) when harvested from the stationary phase of growth, On the other hand, a staphylococcus mutant, which is deficient in N-acetyl glucosamine in its TA (52A2), the parent strain SH and a protein A rich strain Cowen I, could be lysed by the leukocyte factors only when harvested from the logarithmic phase of growth.