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

Abstract

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 6-0-acyl derivatives, only 6-0-(3-hydroxy-2-docosylhexacosanoyl)-N-acetylmuramyl-L-alanyl-D-isoglutaminyl-L-lysyl-D-alanine was found to hold a strong serotoninliberating activity. Raskova et al. (12) and Ryc and Rotta (14) reported that peptidoglycans of Streptococcus pyogenes, Streptococcus pneumoniae, and Staphylococcus aureus lysed blood platelets of rabbits and rats and liberated serotonin (5-hydroxytryptamine). In the present study, we have investigated whether or not this activity is common to bacterial cell walls or peptidoglycans in general, by use of a number of cell walls which differ in the types of peptidoglycans and a nonpeptidoglycan moiety and in some biological properties. A study was also made of serotoninreleasing activity by water-soluble enzymatic digests of Staphylococcus epidermidis peptidoglycans, synthetic muramylpeptides, and their 6-O-acyl derivatives to elucidate the chemical structure responsible for the serotonin-liberating activity of bacterial cell walls. MATERIALS AND METHODS Cell walls and peptidoglycans. Cell wall specimens employed in the present study are listed in Table 1. Among them, the cell walls of Corynebacterium betae, Corynebacterium insidiosum, and Ampullariella regularis were a gift from H. R.

Species dependency of macrophage activation by bacterial peptidoglycans

“…A monomeric subunit (SEPS-M) was produced by treatment of SEPS with M-1 endo-n-acetylmuramidase (21). Details of the preparation method and chemical properties of the above compounds were described previously (14). An LPCM-A specimen, bis-disaccharide stempeptide dimer, was prepared from an M-1 enzyme (endo-nacetylmuramidase) digest of Lactobacillus plantarum (ATCC 8014) cell walls (23).…”

Structural requirements of muramylpeptides for induction of Toll-like receptor 2-mediated NF-κB activation in CHO cells

“…5,6 In the present study, we exposed CHO reporter cells that were transfected with CD14 and human TLR2 to various cell wall components from Staphylococcus epidermidis. Peptidoglycan prepared by treatment with 10% trichloroacetic acid 7 was digested by S. aureus lytic enzyme (SALE) to cleave the pentapeptide cross-links between neighboring stem-peptide subunits (referred to as SEPS). Then, SEPS were digested with M-1 endo-Nacetylmuramidase to hydrolyze the glycan backbone (referred to as SEPS-M).…”

Analgesic effects of N-acetylmuramyl-L-alanyl-D-isoglutamine in decreasing the acetic acid-induced abdominal-writhing response

“…Kadlec et al (4) later found that the mode of this smoothmuscle stimulation involved either direct interaction with smooth muscle or indirect action via neurogenic stimulation. This agent was also shown to have antiinflammatory effects in experimental models of acute inflammation in rats and mice (16) and to liberate serotonin from rabbit blood platelets (3). In this study, we examined the analgesic effect of MDP by using the writhing test.…”