Suppression of fibroblast proliferation by oral spirochetes

Abstract

Soluble sonic extracts of several strains of Treponema denticola and Treponema vincentii were examined for their abilities to alter proliferation of both murine and human fibroblasts. We found that sonic extracts of all tested strains of T. denticola caused a dose-dependent inhibition of murine and human fibroblast proliferation when assessed by both DNA synthesis ([3H]thymidine incorporation) and direct cell counts. T. vincentii had only a minimal inhibitory effect at comparable doses. No inhibition was observed when sonic extracts were added simultaneously with [3H]thymidine, indicating that suppression was not due to the presence of excessive amounts of cold thymidine in the extract, nonspecific effects on thymidine utilization by the cells (transport and incorporation), or degradation of label. RNA ([3H]uridine incorporation) and protein ([3H]leucine incorporation) synthesis were similarly altered after exposure to the T. denticola sonic extracts. There was no effect on cell viability as measured by trypan blue exclusion. Inhibition could be reversed by extensive washing of the cells within the first few hours of exposure to sonic extracts. Preliminary characterization and purification indicated that the inhibitory factor(s) is not endotoxin since it is heat labile, and elutes in a single, well-defined peak on a Sephadex G-150 chromatography column corresponding to a molecular weight of approximately 50,000. Since oral spirochetes have been implicated in the pathogenesis of periodontal disorders, it is possible that they contribute to the disease process by inhibition of fibroblast growth and therefore may, at least in part, account for the loss of collagen seen in diseased tissue.

Common and specific antigens of several treponemes detected by polyclonal antisera against major cellular proteins

“…The polypeptide proteins detected on the outer envelopes of treponemes may contribute to adherence to specific or non-specific substrates present on host cells (5,6,9,25,26,33), tissue damage of hosts (3,22) or antibody production tn vivo (10,12,30). Recently we reported that 77 dentieota ATCC 33520 possessed several fibronectin-binding polypeptides, including 3 main polypeptides P9, PI 1 and P16, suggesting that fibronectin on host cells can mediate cytoadherence of this microorganism by its binding to the outer envelopes or the exposed axial flagella (31).…”

Ribotyping on small‐sized spirochetes isolated from subgingival plaque

“…Small-sized spiroehetes are among the most frequently found bacteria in periodontal pockets and are among the suspected periodontal pathogens (14), as they produce tissue-destroying enzymes, such as trypsin and hyaluronidase, and cytotoxic metabolic products, such as indole and hydrogen sulfide (7,13). Furthermore, these bacteria are able to evade normal host responsiveness by inhibiting polymorphonuclear leukocyte functions and fibroblast proliferation (3,4).…”

Nutrient and environmental growth factors for eight small‐sized oral spirochetes

“…Treponema denticola, have shown that spirochetes may contribute to the inflammatory process, as these strains could ferment glucose and some amino acids to cytotoxic products (8,9). Furthermore, in recent studies it has been observed that spirochetes interact with some host cells in supressing fibroblast growth and inhibiting the function of neutrophil granulocytes (10)(11)(12). However, better cultivation methods are needed to gain further information about the pathogenic effect of spirochetes on periodontal disease.…”