Induction of β-Defensin Resistance in the Oral AnaerobePorphyromonas gingivalis

Abstract

Induction of resistance of oral anaerobes to the effects of human ␤-defensin 1 (h␤D-1) to h␤D-4 was investigated by pretreating cells with either sublethal levels of defensins or environmental factors, followed by a challenge with lethal levels of defensins. Cultures of Porphyromonas gingivalis were (i) pretreated with defensins at 1 ng/ml, (ii) heated to 42°C (heat stress), (iii) exposed to normal atmosphere (oxidative stress), or (iv) exposed to 1 mM hydrogen peroxide (peroxide stress). Samples (10 l) were distributed among the wells of sterile 384-well plates containing h␤D-1 to -4 (100 g/ml). Plates were incubated at 37°C for 36 h in an anaerobe chamber. Growth inhibition was determined by a system that measures the total nucleic acid of a sample with a DNA binding dye. The MICs of the four defensins for P. gingivalis were 3 to 12 g/ml. We found that sublethal levels of the defensins and heat and peroxide stress, but not oxidative stress, induced resistance to 100 g of defensin per ml in P. gingivalis. Resistance induced by sublethal levels of h␤D-2 lasted 90 min, and the resistance induced by each defensin was effective against the other three. Multiple strains exposed to h␤D-2 all evidenced resistance induction. Defensin resistance is vital to the pathogenic potential of several human pathogens. This is the first report describing the induction of defensin resistance in the oral periodontal pathogen P. gingivalis. Such resistance may have an effect on the ability of oral pathogens to persist in the mouth and to withstand innate human immunity.

Distribution of secretory inhibitor of platelet microbicidal protein among anaerobic bacteria isolated from stool of children with diarrhea

“…Similarly, in a study of distribution of streptococcal inhibitor of complement variants in pharyngitis and invasive isolates by Hoe et al [18] , 62% of group A streptococci from patients with pharyngitis produced this extracellular protein. Collectively, our study and the results of several studies [19][20][21] suggest that the inactivation of components of innate immunity may be important for bacterial pathogens to induce and perpetuate infections of different localization by surviving or avoiding microbicidal proteins mediated clearance. Bacteria-derived proteases may contribute to mucosal surface destruction, and are likely to impair host defense by degrading antimicrobial peptides [22] .…”

Porphyromonas gingivalis Resistance to Polymyxin B Is Determined by the Lipid A 4′‐Phosphatase, PGN_0524

“…The induction of resistance against human β-defensins has been described for P. gingivalis (Shelburne et al, 2005). In addition, P. gingivalis has been reported to resist killing by the cathelicidin, LL-37, as well as β-defensin 3 which constitute important mechanisms of leukocyte and epithelial cellmediated antimicrobial host (Bals, 2000;Yang et al, 2004;Ji et al, 2007;Reddy et al, 2009).…”

The Lipid A Phosphate Position Determines Differential Host Toll-Like Receptor 4 Responses to Phylogenetically Related Symbiotic and Pathogenic Bacteria

“…Bacteroides is the most numerous microbial genus found in the human ileum and large intestine, outnumbering Escherichia coli 100 to 1 (10,24). The genus consists of anaerobic Gram-negative rods, including the important human symbiont Bacteroides thetaiotaomicron.…”