Sensitivity of Helicobacter pylori to an innate defence mechanism, the lactoperoxidase system, in buffer and in human whole saliva

Abstract

Helicobacter pylori has frequently been isolated from human dental plaque, and oral spread via saliva is thought to be one of its principal modes of transmission. Among other innate defence systems human saliva contains peroxidase enzymes and lysozyme. The sensitivity of H. pylori to physiological concentrations of lactoperoxidase and its salivary substrate thiocyanate, and different amounts of hydrogen peroxide (H 2 O 2 ) was investigated in buffer and in human whole saliva. The effect of lysozyme was also studied in saliva. All tested H. pylori strains, ATCC 43504 T and five clinical isolates, were efficiently inhibited by the peroxidase system with high concentrations of H 2 O 2 in buffer. The inhibition was stronger at lower pH. However, in human saliva these high concentrations of H 2 O 2 generated less hypothiocyanite, the antibacterial product of the peroxidase system and the effects of the peroxidase system were weaker. Physiological concentration of lysozyme was not bacteriocidal against H. pylori, nor did it enhance the effect of the peroxidase system in saliva. Thus, further studies are needed to enhance the efficacy of peroxidase systems in human saliva to make it more beneficial not only against dental but also against gastric pathogens.

Bovine lactoperoxidase – a versatile one‐ and two‐electron catalyst of high structural and thermal stability

“…Because of its broad spectrum of potential electron donors and the antimicrobial nature of its reaction products [3,25], LPO is not only of importance in unspecific immune defense reactions in mammals. Together with horseradish peroxidase (HRP) it also belongs to heme enzymes most frequently used in industrial applications [6][7][8][9][10]. The present findings together with data from literature will intensify the interest in this biocatalyst because of its conformational, thermal and enzymatic stability in a broad range of conditions.…”

“…It is also applied for protection against gum and periodontal diseases [8]. A new target is Helicobacter pylori, which causes chronic gastritis and is also associated with gastric and duodenal ulcer as well as gastric carcinoma [9]. Furthermore, the cosmetic industry uses LPO in skin care products as antimicrobial agent in a variety of products, for e.g., facial moisturizer, anti-aging cream, cleanser, acne treatment cremes, etc.Additionally, LPO is applied as an antifouling agent, paint preservative, cleaning, and disinfecting agent for medical equipment as well as in wastewater purification [10].…”

The assessment of sIgA, histatin-5, and lactoperoxidase levels in saliva of adolescents with dental caries

“…The inhibition was stronger at lower pH. However, in human saliva these high concentrations of H 2 O 2 generated less hypothiocyanite, the antibacterial product of the peroxidase system, and the effects of the peroxidase system were weaker [25]. …”

Lactoperoxidase: From catalytic mechanism to practical applications

“…A new target that is being investigated is Helicobacter pylori, that causes gastritis and gastric and duodenal ulcers, since it has been suggested that the route of transmission of H. pylori includes oral-oral pathways. In buffer H. pylori is, indeed, susceptible to lactoperoxidase (Shin, Yamauchi, Teraguchi, Hayasawa, & Imoto, 2002) at substrate concentrations that may occur under physiological conditions, but when tested in human whole saliva the results were less definitive (Haukioja, Ihalin, Loimaranta, Lenander, & Tenovuo, 2004).…”