Fluoride Inhibits the Antimicrobial Peroxidase Systems in Human Whole Saliva

Hannuksela, S.; Tenovuo, Jorma; Roger, Valérie; Lenander-Lumikari, M.; Ekstrand, Jan

doi:10.1159/000262016

Cited by 12 publications

(10 citation statements)

References 4 publications

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“…It is noteworthy that SPO was found to have lower pH optima relative to LPO, but it also was inhibited by F -at sufficiently low pH (Thibodeau et al, 1985). A similar inhibitory effect of F -on peroxidase activity has been observed in whole saliva (Thibodeau et al, 1985;Hannuksela et al, 1994;van den Abbeele et al, 1995). These observations suggest that F -in dental plaque may inhibit the peroxidase defense system.…”

Section: Fluoridementioning

confidence: 57%

Inorganic Chemistry of Defensive Peroxidases in the Human Oral Cavity

Ashby

2008

J Dent Res

102

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The innate host response system is comprised of various mechanisms for orchestrating host response to microbial infection of the oral cavity. The heterogeneity of the oral cavity and the associated microenvironments that are produced give rise to different chemistries that affect the innate defense system. One focus of this review is on how these spatial differences influence the two major defensive peroxidases of the oral cavity, salivary peroxidase (SPO) and myeloperoxidase (MPO). With hydrogen peroxide (H2O2) as an oxidant, the defensive peroxidases use inorganic ions to produce antimicrobials that are generally more effective than H2O2 itself. The concentrations of the inorganic substrates are different in saliva vs. gingival crevicular fluid (GCF). Thus, in the supragingival regime, SPO and MPO work in unison for the exclusive production of hypothiocyanite (OSCN−, a reactive inorganic species), which constantly bathes nascent plaques. In contrast, MPO is introduced to the GCF during inflammatory response, and in that environment it is capable of producing hypochlorite (OCl−), a chemically more powerful oxidant that is implicated in host tissue damage. A second focus of this review is on inter-person variation that may contribute to different peroxidase function. Many of these differences are attributed to dietary or smoking practices that alter the concentrations of relevant inorganic species in the oral cavity ( e.g.: fluoride, F−; cyanide, CN−; cyanate, OCN−; thiocyanate, SCN−; and nitrate, NO3−). Because of the complexity of the host and microflora biology and the associated chemistry, it is difficult to establish the significance of the human peroxidase systems during the pathogenesis of oral diseases. The problem is particularly complex with respect to the gingival sulcus and periodontal pockets (where the very different defensive stratagems of GCF and saliva co-mingle). Despite this complexity, intriguing in vitro and in vivo studies are reviewed here that reveal the interplay between peroxidase function and associated inorganic chemistry.

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Section: Fluoridementioning

confidence: 57%

Inorganic Chemistry of Defensive Peroxidases in the Human Oral Cavity

Ashby

2008

J Dent Res

102

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“…Some years ago, Thibodeau et al ( 18) found that under acid conditions, such as those in dental plaque, fluoride is inhibitory for lactoperoxidase and salivary peroxidases. These findings have subsequently been confirmed and extended ( 9, 21). Thibodeau & Keefe ( 19) showed also that fluoride could inhibit the heme catalase of A. viscosus under acid conditions but found only minor enhancement by fluoride of peroxide killing of the organism.…”

supporting

confidence: 53%

Selective sensitization of bacteria to peroxide damage associated with fluoride inhibition of catalase and pseudocatalase

Phan¹,

Kirsch²,

Marquis³

2001

Oral Microbiology and Immunology

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Fluoride and sulfide are known inhibitors of heme catalases in acid environments. Staphylococcus aureus H cells were found to be sensitized by fluoride or sulfide to H2O2 killing at acid pH values in the range of 3.5 to 4.0, and catalase activity was reduced concomitantly. In contrast, fluoride had little effect on H2O2 killing of Streptococcus mutans GS-5, which has fluoride-insensitive peroxidase activity, but still is more sensitive to H2O2 than is S. aureus in the absence of fluoride. Fluoride but not sulfide was inhibitory also for the Mn-containing, non-heme pseudocatalase of Lactobacillus plantarum ATCC 14431 over a wide pH range, and this inhibitory effect was reflected in enhanced H2O2 killing in the presence of fluoride. In addition, we found that catalase-positive S. aureus or Neisseria sicca could protect catalase-negative S. mutans against killing by H2O2 in mixed suspensions, but protection was compromised by fluoride or sulfide under acid conditions. Thus, catalase-positive organisms could protect a catalase-negative organism against peroxide damage, but inhibition of catalase reduced protection. These findings are pertinent to the widespread use of fluoride and peroxide in oral health care products.

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“…Therefore, fluoride inhibition of peroxidases is not likely to be very important in saliva but could be important in plaque where acidification occurs regularly, especially in cariogenic plaque in which fluoride is concentrated. van den Abbeele et al (1992) and Hannuksela et al (1994) more recently reinvestigated the inhibitory effects of fluoride on salivary peroxidases with an orientation to fluoride acting to inhibit the known antimicrobial actions of the enzymes, especially in conjunction with thiocyanate, which is abundant in saliva.…”

Section: Catalasementioning

confidence: 99%

Antimicrobial actions of fluoride for oral bacteria

Marquis¹

1995

Can. J. Microbiol.

243

170

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Fluoride is widely used as a highly effective anticaries agent. Although it is felt that its anticaries action is related mainly to effects on mineral phases of teeth and on the process of remineralization, fluoride also has important effects on the bacteria of dental plaque, which are responsible for the acidification of plaque that results in demineralization. The results of recent studies have shown that fluoride can affect bacterial metabolism through a set of actions with fundamentally different mechanisms. It can act directly as an enzyme inhibitor, for example for the glycolytic enzyme enolase, which is inhibited in a quasi-irreversible manner. Direct action seems also to occur in inhibition of heme-based peroxidases with binding of fluoride to heme. The flavin-based peroxidases of many oral bacteria are insensitive to fluoride. Another mode of action involves formation of metal-fluoride complexes, most commonly AlF4-. These complexes are responsible for fluoride inhibition of proton-translocating F-ATPases and are thought to act by mimicking phosphate to form complexes with ADP at reaction centers of the enzymes. However, the actions of fluoride that are most pertinent to reducing the cariogenicity of dental plaque are those related to its weak-acid character. Fluoride acts to enhance membrane permeabilities to protons and compromises the functioning of F-ATPases in exporting protons, thereby inducing cytoplasmic acidification and acid inhibition of glycolytic enzymes. Basically, fluoride acts to reduce the acid tolerance of the bacteria. It is most effective at acid pH values. In the acidic conditions of cariogenic plaque, fluoride at levels as low as 0.1 mM can cause complete arrest of glycolysis by intact cells of Streptococcus mutans. Overall, the anticaries actions of fluoride appear to be complex, involving effects both on bacteria and on mineral phases. The antibacterial actions of fluoride appear themselves to be complex but to be dominated by weak-acid effects.

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Fluoride Inhibits the Antimicrobial Peroxidase Systems in Human Whole Saliva

Cited by 12 publications

References 4 publications

Inorganic Chemistry of Defensive Peroxidases in the Human Oral Cavity

Inorganic Chemistry of Defensive Peroxidases in the Human Oral Cavity

Selective sensitization of bacteria to peroxide damage associated with fluoride inhibition of catalase and pseudocatalase

Antimicrobial actions of fluoride for oral bacteria

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