Related Experiment Videos
Effects of Porphyromonas gingivalis culture products on human polymorphonuclear leukocyte function
J M Wilton1, T J Hurst, R J Carman
1Medical Research Council Dental Research Unit, London Hospital, U.K.
Abstract:
Porphyromonas gingivalis culture supernate was found to induce homotypic agglutination of human polymorphonuclear leukocytes (PMN). Pretreatment of PMN with P. gingivalis supernate inhibited both the rate and the degree of agglutination induced by the secretagogues PMA and FMLP. Lipopolysaccharide from P. gingivalis upregulated the CR3 (Mac-1, CD11b) receptors on PMN. Treatment of glass-adherent PMN with P. gingivalis supernate did not alter their phagocytic capacity for P. gingivalis cells but when PMN were pretreated in suspension the cells adhered less well to glass and phagocytosis of those PMN that did adhere was reduced. P. gingivalis supernate treatment of PMN induced lysozyme release but the amount released during phagocytosis when supernate was present did not change. Neither P. gingivalis supernate nor LPS were cytotoxic for PMN. The data suggest that P. gingivalis factors could interfere with PMN elimination of this organism at the site of infection by inappropriately stimulating PMN, depressing phagocytosis and causing enhanced CR3 expression. The consequent agglutination or enhanced adherence could also lead to decreased phagocytic capacity of the adherent or agglutinated cells.
Insights
Porphyromonas gingivalis impairs human immune cells called polymorphonuclear leukocytes (PMN) by causing them to clump and reducing their ability to engulf bacteria. This may hinder the body's defense against this specific oral pathogen.
Area of Science:
- Immunology
- Microbiology
- Periodontal disease research
Background:
- Porphyromonas gingivalis is a key pathogen in periodontitis.
- Polymorphonuclear leukocytes (PMN) are crucial for innate immunity against bacterial infections.
Purpose of the Study:
- To investigate the effects of P. gingivalis culture supernatant on human PMN function.
- To understand how P. gingivalis may evade the host immune response.
Main Methods:
- Incubation of human PMN with P. gingivalis culture supernatant and lipopolysaccharide (LPS).
- Assessment of PMN agglutination, adherence, phagocytosis, and lysozyme release.
- Flow cytometry to analyze CR3 receptor expression on PMN.
Main Results:
- P. gingivalis supernatant induced PMN agglutination and inhibited secretagogue-induced agglutination.
- P. gingivalis LPS upregulated CR3 receptors on PMN.
- PMN pretreated with supernatant showed reduced adherence and phagocytosis of P. gingivalis.
- Lysozyme release was induced, but not altered during phagocytosis in the presence of supernatant.
Conclusions:
- P. gingivalis factors interfere with PMN's ability to clear the bacteria.
- Mechanisms include inappropriate PMN stimulation, reduced phagocytosis, and enhanced CR3 expression.
- Agglutination and altered adherence may further decrease phagocytic capacity, aiding bacterial survival.