Arthropathic Properties of Peptidoglycan-Polysaccharide Complexes of Microbial Origin. In: Deicher H, Schulz L, editors. Arthritis. Berlin: Springer Berlin Heidelberg; 1981. pp. 24-38. [DOI: 10.1007/978-3-642-68106-6_3]

Bacterial interference with immunospecific defences

There are many descriptions of bacterial agents that can suppress different phases of specific immunity. Bacterial agents are frequently employed as tools to modulate the immune system in experimental models or clinical therapy. Little attention has been given to the implications of such immunoregulating properties for infectious processes or for the natural role of the microbial flora in the normal regulation of the immune system. There are very few studies attempting to investigate directly the possible role of bacterial immunosuppressant factors in acute infection. Several examples of natural and experimental chronic infections have been described in which progressive uncontrolled infection is associated with a depressed cell mediated immunity, but a causal relation is unproven. This depression is usually not antigenically specific and there is some evidence that it may be initiated and maintained by persistent cell-wall components of the microorganisms. The bacteria implicated in suppression are all facultative or obligate intracellular parasites that can multiply and survive in the monocyte/macrophage. Bacterial immunosuppressants may have a crucial role in the pathogenesis of progressive chronic inflammation that occurs after infection.

Interaction of group A streptococcal peptidoglycan polysaccharide with human polymorphonuclear leukocytes: implications for pathogenesis of chronic inflammation

Injection of sterile aqueous preparations of the peptidoglycan polysaccharide of group A streptococci produces chronic inflammation in several animal models. Accordingly, the effect of peptidoglycan and group A-specific polysaccharide (PG-APS) polymers on human polymorphonuclear neutrophil oxidative metabolism was studied with the supposition that this interaction may contribute to the inflammation observed. PG-APS in concentrations of 1.0 to 100 micrograms/ml stimulated oxygen consumption and hexose monophosphate shunt activity in the presence of 10% normal serum in a dose-related manner. Stimulation did not occur in serum-free media and was reduced in media with heat-treated serum. The stimulation of hexose monophosphate shunt activity by PG-APS opsonized with normal serum (bound complement components) and the activated supernatant from which PG-APS had been removed by centrifugation (presumably containing the soluble complement component, C5a) demonstrated 79 and 75%, respectively, of the stimulation with PG-APS in the presence of 10% normal serum. PG-APS triggered release of O2- (3.4 +/- 2.0 nmol by 10(6) human polymorphonuclear neutrophils over 30 min), which was significantly enhanced (9.6 +/- 2.9 nmol O2-) by treatment of cells with cytochalasin B. These results show that PG-APS interacts with serum in such a fashion as to activate human polymorphonuclear neutrophil metabolism and increase secretion of O2-.

Arthropathic properties related to the molecular weight of peptidoglycan-polysaccharide polymers of streptococcal cell walls

The covalently bound polymers of peptidoglycan and group-specific polysaccharide (PG-APS) were isolated from the cell walls of group A streptococci. Arthritis was induced in rats with a single intraperitoneal injection of an aqueous suspension of PG-APS fragments derived by sonication. The joint lesions induced with this polydisperse suspension followed a bimodal pattern consisting of an acute phase, which reached a peak 5 days after injection and then receded, followed by a chronic, remittent, erosive arthritis lasting several months. The relative severities of the acute and chronic phases could be manipulated by selection of the size of PG-APS fragments. The fragments of PG-APS obtained by sonic treatment were resolved on the basis of size into three major populations by sucrose gradient or differential centrifugation. Based upon light scattering and gel filtration, the average molecular weight of the largest family of fragments was estimated to be about 500 x 10(6), the intermediate fragments were 50 x 10(6) daltons, and the predominant size in the smallest population was 5.3 x 10(6) daltons. The larger fragments induced negligible acute inflammation, but chronic disease became apparent 5 to 9 weeks after injection. The smallest fragments induced the most severe acute inflammation, with relatively little late, chronic joint disease. The particles of intermediate size induced moderate acute inflammation and the most severe chronic, erosive joint lesions. A single injection of fragments of the isolated peptidoglycan moiety of the PG-APS induced only a moderate acute inflammation of joints, with no apparent capacity to maintain the injury and induce chronic disease.