Intergenus cell fusion between L-form cells of Pseudomonas aeruginosa and Escherichia coli

Intergenus cell fusion of prokaryotic bacteria was demonstrated for the first time; namely, fusion products doubly resistant to streptomycin and tetracycline were produced by polyethylene glycol treatment of a mixture of the streptomycin-resistant L-form of Pseudomonas aeruginosa and tetracycline-resistant L-form of Escherichia coli.

Enhancement of dengue virus type 2 replication in mouse macrophage cultures by bacterial cell walls, peptidoglycans, and a polymer of peptidoglycan subunits

The effects of bacterial cell walls, peptidoglycans, and a water-soluble polymer of peptidoglycan subunits on dengue virus type 2 replication in cultured mouse peritoneal macrophages were studied. Pretreatment of macrophage cultures with all of test cell walls isolated from seven bacterial species for 3 days significantly enhanced the virus production in the cultures. Peptidoglycans prepared from four of the above cell walls also exerted the virus production-enhancing effects in a similar manner as the walls. A water-soluble polymer of peptidoglycan subunits which was prepared by treatment of Staphylococcus epidermidis wall peptidoglycan with an interpeptide bridge-splitting enzyme (endopeptidase) also definitely enhanced the virus production in macrophage cultures, although its activity was weaker than that of the original wall and peptidoglycan. Macrophage cultures from athymic nude mice, when treated with cell walls and peptidoglycans of S. epidermidis and Lactobacillus plantarum for 3 days, also showed an increased ability to support dengue virus type 2 replication. The infectious center assay demonstrated that the virus replication enhancement by S. epidermidis cell wall and peptidoglycan was primarily due to an increase in the number of virus-infected cells. This finding did not seem to be in conflict with the observation that macrophages treated with the above cell wall or peptidoglycan phagocytized more latex particles than did untreated macrophages. The conclusions based on the above experiments are that the treatment of mouse peritoneal macrophage cultures with bacterial cell walls and their components increases the take of dengue virus type 2 by macrophages and thus raises the virus production in the macrophage cultures.

Immunobiological activities of synthetic lipid A analogs and related compounds as compared with those of bacterial lipopolysaccharide, re-glycolipid, lipid A, and muramyl dipeptide

Thirteen acylated and phosphorylated derivatives of beta-1,6-linked glucosamine disaccharide (lipid A analogs), which were synthesized after the structural model of Salmonella-type lipid A, and seven similar derivatives of glucosamine monosaccharide (lipid A-related compounds) were studied for their immunobiological activities. These included mitogenicity and polyclonal B cell activation enhancement of migration of monocytes and polymorphonuclear leukocytes derived from human peripheral blood, stimulation of guinea pig peritoneal macrophages, activation of human complement, and stimulation of serum antibody production and induction of delayed-type hypersensitivity against ovalbumin in guinea pigs. Comparisons were made with lipid A, RE-glycolipid, lipopolysaccharide of natural sources, and a well-known synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine. Some of the lipid A analogs were found to manifest the mitogenic, polyclonal B cell-activating macrophage-stimulating, complement-activating, and immunostimulating activities, although the observed activities were generally far less than those of natural products in intensity and efficiency. Other immunobiological effects exhibited by most of the synthetic lipid A analogs were the enhancement of migration of monocytes and polymorphonuclear leukocytes. It is premature to draw definite conclusions on structure-activity relationships, since a few compounds which were active in some assay systems were scarcely active in other assays. However, an indisputable fact was that beta-1,6-glucosamine disaccharide 1 alpha,4'-diphosphate, which carries two amide-bound (R)-3-hydroxytetradecanoyl and three ester-bound tetradecanoyl residues, and thus has the structure most closely resembling natural lipid A among test compounds in this study, was definitely active in all of the present assay systems. However, its potency was generally much less than natural products. Some of glucosamine monosaccharide derivatives, especially N-(R)-3-[(R)-3-hydroxytetradecanoyloxy]tetradecanoyl glucosamine, also exerted all of the in vitro activities described above. This fact suggests that a glucosamine disaccharide structure may not necessarily be a prerequisite as far as the in vitro immunobiological activities tested are concerned.

Novel biological property of pertussis toxin: chemotactic activity on human monocytes

Pertussis toxin isolated from Bordetella pertussis phase I strain Tohama enhanced the migration of human blood monocytes in an assay with a multiwell chemotaxis assembly. The monocyte migration enhancement by pertussis toxin was abolished by heating at 100 degrees C for 30 min, which caused a complete loss of the other biological activities of pertussis toxin. Checkerboard analysis demonstrated that the increased monocyte migration caused by pertussis toxin was directed toward a positive stimulus: chemotaxis.

Stimulating effect of MDP and its adjuvant-active analogues on guinea pig fibroblasts for the production of thymocyte-activating factor

Synthetic muramyl dipeptide (MDP) could stimulate skin fibroblasts of the guinea pig to produce thymocyte-activating factor, which augments the proliferative response of thymocytes to phytohemagglutinin (PHA). Adjuvant-active analogues of MDP also stimulated fibroblasts to produce the factor, whereas adjuvant-inactive analogues failed to do so. Thus a marked parallelism was found between adjuvant activity of these compounds and the stimulating effect on fibroblasts. Thymocyte-activating factor derived from MDP-stimulated fibroblasts was found in the fraction of mol wt 30,000-60,000 by gel filtration on a Sephacryl S-200 column. Furthermore, this factor did not exhibit T cell growth factor activity.

Isolation and characterization of the serotype g carbohydrate moiety from an enzyme lysate of Streptococcus mutans 6715 cell walls

The serotype-specific carbohydrate moiety of Streptococcus mutans was isolated by mild degradation of purified cell walls with a cell-wall lytic enzyme. Cell walls of serotype g S. mutans strain 6715 were digested with M1 enzyme, an endo-N-acetylmuramidase purified from culture supernatants of Streptomyces globisporus strain 1829. The enzyme lysate of the cell walls was applied to a CM Sephadex C-25 column to remove the M1 enzyme from the cell wall lysate and then subjected to Sephadex G-100 column chromatography. Carbohydrate antigens with serotype g specificity, designated M1g, and a peptidoglycan--polysaccharide complex lacking serotype specificity (M1PG) were separated. Purified serotype g antigen was also obtained by autoclaving the S. mutans 6715 whole cells in saline at 120 C for 30 min. The extract was applied to a DEAE Sephadex A-25 column to remove nucleic acids and teichoic acids. The unbound peak fraction was concentrated and re-chromatographed on a Bio-Gel P-100 column. The void volume fraction contained serotype g carbohydrate and was designated RRg antigen. M1g and RRg antigens formed a band of identity with anti-serotype g serum by immunodiffusion. These antigens were composed mainly of galactose, glucose, and rhamnose at an approximate weight ratio of 8 : 4: 1, while constituent sugars of M1PG consisted of rhamnose and glucose, with no detectable galactose. M1g also contained peptidoglycan residues other than threonine, an interpeptide bridge component of the native cell wall peptidoglycan. Marked inhibition of the quantitative precipitin reaction between M1g and anti-serotype g serum was obtained with melibiose and galactose, which suggests that the immunodeterminant of the serotype g carbohydrate is an alpha-linked galactose-glucose terminal linkage.

Purification and quantitative chemical analysis of cell wall peptidoglycans of Leptotrichia buccalis

Peptidoglycans of Leptotrichia buccalis ATCC 14201 and ATCC 19616 were isolated by extraction with sodium dodecyl sulfate and subsequent digestion of the sodium dodecyl sulfate-insoluble residue with proteases and alpha-amylase. Cell wall fractions obtained by sodium dodecyl sulfate extraction and protease digestion were highly contaminated by a glucose polymer. The polyglucose was removed by alpha-amylase treatment, and the peptidoglycans were left behind. Analyses with amino acids and amino sugars of the cell wall fractions and peptidoglycan specimens revealed that D-glutamic acid, D-alanine, L-alanine, meso-2,6-diaminopimelic acid (A2pm), muramic acid, and glucosamine were the principal components. The dinitrophenylation method revealed that about half of the A2pm residue had a free amino group, and analysis by hydrazinolysis showed that a small part of alanine and A2pm was located at the C terminal. The above results indicate that one of the amino groups of the A2pm residue at one strand of the stem peptide subunit cross-linked to the carboxyl group of alanine of the neighboring strand. It was thus revealed that the peptidoglycans of L. buccalis belong to the A1 gamma type of the classification by Schleifer and Kandler (Bacteriol. Rev. 36:407-477).

Muramyl dipeptides: prospect for cancer treatments and immunostimulation

The immunopharmacological activities of bacterial cell walls and muramyl peptides were collected in table form with a comprehensive literature. The past and present studies emphasizing the host-defense enhancing activities of muramyl peptides for antitumor immunotherapy were surveyed along three possible approaches: 1) the nonspecific enhancement of natural defense ability of host against tumor cells themselves; 2) the enhancement of nonspecific resistance of host to microbial infections which are frequently encountered and difficult to treat in the advanced stage of tumor patients; and 3) the stimulation of immunity against tumor-specific or tumor-associated immunogens. Finally, the prospects of successful antitumor immunotherapy with muramyl peptides and their derivatives was discussed.

Possible chemotaxis of human monocytes by N-acetylmuramyl-L-alanyl-D-isoglutamine

N-Acetylmuramyl-l-alanyl-d-isoglutamine (MDP) induced the chemotaxis of human blood monocytes without mediation of serum complement. Specificity (dependency on chemical structure) of the chemotactic activity of MDP was evidenced by a negligible activity of analogs lacking most of the immunomodulating activities of MDP.

Stimulation of migration of human monocytes by bacterial cell walls and muramyl peptides

Bacterial cell walls, water-soluble fragments of the wall peptidoglycan, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), and 6-O-acyl derivatives of MDP were examined for migration-stimulating activity on human peripheral blood monocytes by using a multiwell chemotaxis assembly. Cell walls isolated from 11 bacterial species caused a definite increase in monocyte migration, but the walls of Micrococcus lysodeikticus were scarely active. The migration-enhancing activity of Staphylococcus epidermidis cell walls was retained by a monomer as well as a polymer of disaccharide peptides which were prepared by digestion of the peptidoglycan with enzymes. It was finally revealed that the migration of monocytes was enhanced by MDP. 6-O-Octadecanoyl-MDP, 6-O-(2-tetradecylhexadecanoyl)-MDP, and 6-O-(3-hydroxy-2-docosylhexacosanoyl)-N-acetylmuramyl-L-seryl-D-isoglutamine were active, but to a lesser extent. A checkerboard assay demonstrated that the increased monocyte migration caused by S. epidermidis cell walls was directed toward a positive stimulus (chemotaxis).

Liberation of serotonin from rabbit blood platelets by bacterial cell walls and related compounds

A study was made on the activity of various bacterial cell walls and peptidoglycans to liberate serotonin from rabbit blood platelets. All of the test cell walls or peptidoglycans prepared from 27 strains of 21 bacterial species were shown to cause a marked release of serotonin, regardless of differences in types of peptidoglycan and non-peptidoglycan moieties and in some biological properties. The assay made with the water-soluble "digests" of Staphylococcus epidermidis cell wall peptidoglycans, which were prepared by use of appropriate enzymes, revealed that a polymer of peptidoglycan subunits (a disaccharide-stempeptide) was definitely active in the release of serotonin, but a structural unit monomer was inactive. Among a variety of synthetic muramylpeptides and their 6-O-acyl derivatives, only 6-O-(3-hydroxy-2-docosylhexacosanoyl)-N-acetylmuramyl-L-alanyl-D-isoglutaminyl- L-lysyl-D-alanine was found to hold a strong serotonin-liberating activity.

Isolation of recombinants doubly and triply drug-resistant to streptomycin, tetracycline and chloramphenicol by PEG-induced cell fusion of singly resistant staphylococcus aureus L-forms

Various combinations of four substrains of Staphylococcus aureus L-form (strain STA-EMT-1), each of which was resistant to one of the following four drugs, streptomycin (SM), tetracycline (TC), chloramphenicol (CP) and erythromycin (EM), were submitted to polyethylene glycol (PEG)-induced cell fusion. PEG-induced cell fusion followed by enrichment culture in the liquid basal medium supplemented with penicillin G resulted in development of recombinants that were doubly drug-resistant to SM and TC, SM and CP, and TC and CP, but no recombinant doubly resistant to EM and TC, was obtained by treatment of a EM-resistant and TC-resistant substrains with PEG. No recombinants resistant to SM, CP and TC could be obtained by treatment of substrains resistant to SM, CP and TC, respectively, with PEG. But recombinants triply resistant to these three drugs were produced by two-step cell fusion; that is by fusion of a recombinant doubly resistant to two of the three drugs with a substrain resistant to the third drug.

New model of a synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine- induced arthritis: clinical and histologic studies in athymic nude and euthymic rats

A synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), induced severe polyarthritis in euthymic rnu/+ rats. The rnu/+ rats were the most susceptible to MDP-induced arthritis among various rat strains tested, whereas congenitally athymic nude rats (rnu/rnu), males or females, did not develop the disease. This disease was clinically and histologically indistinguishable from classic adjuvant-induced arthritis in terms of clinical course, clinical signs, and histologic features such as (1) an initial acute exudative reaction observed primarily in stroma of the synovial membrane, periarticular tissue, about the tendons, tendon sheath, along the periosteum, between muscle bundles and in the subcutaneous tissue; (2) hypertrophy of the synovial villi, hyperplasia of the synovial lining cells; (3) the very active periosteal new bone formation; and (4) granulation tissue growth either in the articular tissues or in liver, lymph nodes, and capsule of the spleen. Thus, it is postulated that MDP-induced arthritis is basically the same disease as classic adjuvant-induced arthritis. The thymus may play an important role in promoting the development of the disease, possibly through some immune mechanisms to undetermined antigen(s). We believe that nonimmune mechanisms may also be involved in some part of acute and chronic inflammatory reactions to MDP molecules. This new model of MDP-induced arthritis will be a very useful tool to elucidate the underlying mechanisms of adjuvant-induced arthritis.

Immunological activities of Capnocytophaga cellular components

Whole cells of a clinical isolate (strain S-3) of the genus Capnocytophaga were divided into cell envelope (CE) and cytoplasm (CP) fractions by mechanical disintegration followed by differential centrifugation, and a part of the CE fraction was further fractionated by sodium dodecyl sulfate (SDS) treatment into the peptidoglycan and SDS-supernatant fractions. The other part of the CE was extracted with butanol-water or hot phenol-water to isolate butanol-lipopolysaccharide and phenol-lipopolysaccharide, respectively. All of the test fractions except CP exhibited multifold immunomodulating activities, namely, the adjuvant activities to cellular as well as humoral immune responses against ovalbumin in guinea pigs, the mitogenicity on splenocytes of guinea pigs and BALB/c mice (but not on their thymocytes), the stimulation of guinea pig peritoneal macrophages (in terms of increased glucosamine uptake), and the activation of the human complement system through alternative as well as classical pathways. In addition, the test fractions other than the CP evoked dermatoxic reactions on rabbit skin with characteristic variations among them. The immunomodulating activities of SDS-supernatant were noteworthy in view of the fact that this fraction was essentially free of muramic acid and diaminopimelic acid and did not cause the gelation of horseshoe crab amoebocyte lysate except when it was used at the very high dose, suggesting that there was practically no contamination by peptidoglycans and lipopolysaccharides in the SDS-supernatant.

Contractile effects of bacterial cell walls, their enzymatic digests, and muramyl dipeptides on ileal strips from guinea pigs

Cell walls isolated from four bacterial species (Streptococcus pyogenes, Lactobacillus plantarum, Streptomyces gardneri, and Nocardia corynebacteriodes), which exhibited the adjuvant effect of stimulating cellular and humoral immune responses against ovalbumin in guinea pigs, caused the slow-starting and long-lasting contraction of guinea pig ileal strips suspended in Tyrode solution. In contrast to these cell walls active in immunoadjuvancy, those isolated from five bacterial species (Micrococcus lysodeikticus, Staphylococcus epidermidis, Arthrobacter atrocyaneus, Corynebacterium insidiosum, and Ampullariella regularis), which lacked immunoadjuvancy at least in intact walls, caused no or very weak contraction of the ileal strips. Further study demonstrated that both a monomer and a polymer of disaccharide-stem peptides, which were obtained by enzymatic degradation of S. epidermis cell wall peptidoglycans, displayed similar contractile effects. It was finally revealed that guinea pig ileum strips showed a definite contractile response to N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) and 6-O-stearoyl- and 6-O-(2-tetradecylhexadecanoyl)-MDPs, but not to their analogs, whose C-terminal amino acid was L-isoglutamine or D-isoasparagine in place of D-isoglutamine and which lacked adjuvancy. 6-O-(3-Hydroxy-2-docosylhexacosanoyl)-MDP, on the other hand, caused a slow and lasting relaxation of the ileum strips, but its L-isoglutamine and D-isoasparagine analogs did not.

Adherence of Streptococcus sanguis clinical isolates to smooth surfaces and interactions of the isolates with Streptococcus mutans glucosyltransferase

Streptococcus sanguis isolated from human dental plaque were grown in Todd-Hewitt broth. Cells were collected by centrifugation and lyophilized after extensive washing with water. The cell-associated glucosyltransferase (GTase) activities of S. sanguis strains were assayed with [14C]sucrose. Strain differences in GTase activity were significant within the same serotype or biotype or both. The ability of S. sanguis cells to adhere to smooth glass surfaces was generally weak, irrespective of significant cell-associated GTase activity synthesizing water-insoluble, gel-like glucans. Resting cells of most S. sanguis strains bound extracellular GTase from Streptococcus mutans strain B13 (serotype d), resulting in the strong adherence of the S. sanguis cells to smooth glass surfaces in the presence of sucrose. Conversely, S. mutans B13 cells also could bind extracellular GTase from some strains of S. sanguis examined. The sucrose-dependent adherence of S. mutans cells was not altered, although S. sanguis strains from which the extracellular GTases were obtained did not produce significant adherence in the presence of sucrose. In view of these findings, it was suggested that S. mutans GTase could affect the adherence of S. sanguis to smooth tooth surfaces in the oral cavity.

Susceptibility of rats, hamsters, and mice to carious infection by Streptococcus mutans serotype c and d organisms

Susceptibility of rats, hamsters, and mice to carious infection by S. mutans serotypes c and d was compared. S. mutans serotype c induced a similar level of carious lesions at experimental periods of 68, 82, and 98 d in rats, hamsters, and mice, respectively. On the other hand, S. mutans serotype d developed a high level of caries at those experimental periods in rats and hamsters, whereas in mice it showed weak caries activity.

Mitogenic effect of cytoplasmic membranes and a cytoplasmic fraction of Staphylococcus aureus L-forms on human peripheral blood lymphocytes

The cytoplasmic membranes and a cytoplasmic fraction of Staphylococcus aureus L-forms increased the incorporation of [3H]thymidine by human lymphocytes in the presence of fetal bovine serum. Both fractions stimulated cord blood lymphocytes as well as adult peripheral lymphocytes, suggesting the possibility that the observed effect was not due to an antigen-specific reaction, but to an immunologically nonspecific action. The membrane mitogen(s) was resistant to trypsin, although it was partially solubilized by trypsin treatment. The mitogen(s) could not be extracted with a chloroform-methanol mixture (2:1, v/v), although the chloroform-methanol soluble fraction was strongly mitogenic to murine splenocytes. Human serum which was added to the assay system in place of fetal bovine serum definitely suppressed the mitogenic effect of both cytoplasmic membranes and the cytoplasmic fraction, especially the latter.

beta-Lactam resistance in Serratia marcescens: comparison of action of benzylpenicillin, Apalcillin, Cefazolin, and ceftizoxime

The intrinsic mechanisms of resistance to beta-lactam antibiotics in Serratia marcescens IFO 12648 were investigated, comparing the action of benzylpenicillin, apalcillin, cefazolin, and ceftizoxime. The minimal inhibitory concentrations for this strain were 1,600, 3.13, 6,400, and 0.05 microgram/ml, respectively. The addition of ethylenediaminetetraacetic acid markedly reduced the minimal inhibitory concentrations of benzylpenicillin and cefazolin, whereas those of apalcillin and ceftizoxime were not influenced. S. marcescens IFO 12648 produced only a low level of beta-lactamase activity constitutively, and the production was considerably increased by the addition of benzylpenicillin. Cefazolin was hydrolyzed rapidly by beta-lactamase activity, whereas benzylpenicillin, apalcillin, and ceftizoxime were poorly hydrolyzed. Peptidoglycan synthesis in ether-treated strain IFO 12646 cells was inhibited by a concentration of ceftizoxime markedly lower than that of cefazolin and by a concentration of apalcillin moderately lower than that of benzylpenicillin.