http://repub.eur.nl/res/aut/9445/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/22575/ 1996-09-11T00:00:00Z Normal flora as well as pathogenic bacteria, can induce acute and chronic inflammations in humans. Probably as a result of the therapeutic efficacy of antibiotics in the past decades there has been relatively little interest in the mechanisms underlying bacterially induced inflammation. However, because of the increase in the incidence of antibiotic resistant bacteria, the subject is gaining interest. It is important to investigate the inflammatory mechanisms in order to provide new tools for clinicians as they will have to treat the inflammatory symptoms as well as the infection. One of the major components present in Gram-positive bacteria is peptidoglycan (PG). It has been shown that PG possesses inflammatory properties similar to LPS. This suggests that PG is involved in the pathogenesis of inflammation induced by Gram-positive bacteria and possibly also Gramnegative bacteria. A description of the recent work done to test this hypothesis is given in the first part of this introduction. In the second part of this chapter special attention is given to the detection of PG in tissues. The presence of PG in tissues is a prerequisite for the induction of inflammation by PG products. The presence of PG in tissues implicates the presence of PG degrading systems, necessary to prevent the inflammation. In the last Palt of this chapter, an overview is given on the PG degrading systems available in humans. http://repub.eur.nl/res/pub/8556/ 1995-01-01T00:00:00Z In previous studies, we showed that peptidoglycan polysaccharides from anaerobic bacteria normally present in the human gut induced severe chronic joint inflammation in rats. Our hypothesis is that peptidoglycan from the gut flora is involved in perpetuation of idiopathic inflammation. However, in the literature, the presence of peptidoglycan or subunits like muramyl peptides in blood or tissues is still a matter of debate. We were able to stain red pulp macrophages in all six available human spleens by immunohistochemical techniques using a monoclonal antibody against gut flora-derived antigens. Therefore, these human spleens were extracted, and after removal of most of the protein, the carbohydrate fraction was investigated for the presence of muramic acid, an amino sugar characteristic for peptidoglycan. Using three different methods for detection of muramic acid, we found a mean of 3.3 mumol of muramic acid with high-pressure liquid chromatography, 1.9 mumol with a colorimetric method for detection of lactate, and 0.8 mumol with an enzymatic method for detection of D-lactate per spleen (D-lactate is a specific group of the muramic acid molecule). It is concluded that peptidoglycan is present in human spleen not as small muramyl peptides as were previously searched for by other investigators but as larger macromolecules probably stored in spleen macrophages.