Combined Bactericidal Effect of Human Lactoferrin and Lysozyme AgainstStreptococcus mutansserotype c

Antibacterial effects of saliva substitutes containing lysozyme or lactoferrin against Streptococcus mutans

OBJECTIVE

To determine the antibacterial effects of different saliva-substitutes-containing-lysozyme(LYZ) or-lactoferrin(LF) on Streptococcus mutans(S. mutans) in comparison with human saliva.

DESIGN

In vitro wound-healing assay was performed with L929 mouse fibroblast cell line by using various concentrations of LYZ and LF to determine optimum concentrations and to confirm do not show any cytotoxicity of proteins according to cell culture studies. Antibacterial effect was assessed by determining Minimum Inhibitory Concentrations for all groups on S.mutans. Bacterial adhesion of S. mutans for 4 h on hydroxyapatite(HAP) discs after application of different saliva substitutes was evaluated. The formulations were:saliva-substitute(Group SS);saliva-substitute-containing-Lactoferrin(Group SSLF);saliva-substitute-containing-Lysozyme(Group SSLYZ). Human saliva was control group(Group HS).

RESULTS

In vitro wound healing assay results showed that, when added into the cell culture media, LYZ and LF significantly increase 48 -h scratch wound closure compared to the cell culture media(p < 0.0001). At the end of second day, samples treated with both between 2.5-100 μg/mL LF and 5-200 μg/mL LYZ were found to have significant wound healing effect(p < 001). It was observed that saliva-substitutes-containing-LYZ or-LF had antibacterial effects on S.mutans. Bacterial adhesion on HAP discs was observed significantly higher in control group than in study groups. The amount of adhered S. mutans was significantly higher in Group SS than other study groups(p < 0.0001). However, no statistically significant difference was found between the number of bacteria adhered to HAP discs between SSLYZ and SSLF groups(p > 0.05).

CONCLUSIONS

The study of cell viability and wound healing was great significance in the optimum concentrations of LYZ and LF. Among formulations, saliva-substitutes-containing-LYZ or-LF exhibited higher inhibitory effect on S.mutans.

Prophylactic effect of human lactoferrin against Streptococcus mutans bacteremia in lactoferrin knockout mice

Streptococcus mutans is the primary agent of dental caries, which is often detected in transient bacteremia. Lactoferrin is a multifunctional glycoprotein showing antibacterial activities against several Streptococcus species. We reported here the prophylactic effect of human lactoferrin (hLF) in a lactoferrin knockout mouse (LFKO-/-) bacteremic model. The hLF treatment significantly cleared S. mutans from the blood and organs of bacteremic mice when compared to the non-hLF treated mice. Further, analysis of serum cytokines, spleen and liver cytokine mRNA levels revealed that hLF prophylaxis modulates their release differently when compared to the non-hLF treated group. C-reactive protein level (P = 0.003) also decreased following hLF prophylaxis in S. mutans induced bacteremic mice. Additional quantitative RT-PCR analysis revealed that hLF prophylaxis significantly decreased the expression level of IFN-γ, TNF-α, IL-1β, IL-6, MPO and iNOS in spleen and liver. These results suggested that the hLF protects the host against S. mutans-induced experimental bacteremia.

The effects of peroxidase on the enzymatic and candidacidal activities of lysozyme

OBJECTIVE

To investigate the effects of peroxidase or the peroxidase system on the enzymatic and candidacidal activities of lysozyme.

DESIGN

The effects of peroxidase on lysozyme were examined by incubating hen egg-white lysozyme (HEWL) with bovine lactoperoxidase (bLPO). The influence of the peroxidase system on lysozyme was examined by the subsequent addition of potassium thiocyanate and hydrogen peroxide. Lysozyme activity was determined by the turbidity measurement of a Micrococcus lysodeikticus substrate suspension. Candidacidal activity was determined by comparing the colony forming units of Candida albicans ATCC 10231, ATCC 18804, and ATCC 11006. The Wilcoxon signed rank test was used to analyze the effects of variables.

RESULTS

bLPO at physiological concentrations enhanced the enzymatic activity of HEWL and its effect was dependent on bLPO concentration. The enhancement of enzymatic activity of HEWL by bLPO was affected by pH and ionic strength. The addition of potassium thiocyanate and hydrogen peroxide did not lead to an additional enhancement of the enzymatic activity of HEWL, as compared with bLPO alone. HEWL displayed candidacidal activity in all 3 strains of C. ablicans. The addition of bLPO alone did not affect the candidacidal activity of HEWL, but the bLPO system enhanced candidacidal activity of HEWL in all 3 strains of C. ablicans.

CONCLUSIONS

bLPO enhanced the enzymatic activity of HEWL, but the bLPO system did not show additional enhancement of the enzymatic activity of HEWL. The addition of bLPO did not affect the candidacidal activity of HEWL, but the bLPO system did enhance the candidacidal activity of HEWL.

Clinical applications of antimicrobial host proteins lactoperoxidase, lysozyme and lactoferrin in xerostomia: efficacy and safety

Innate human salivary defence proteins, lysozyme, lactoferrin and peroxidase, are known to exert a wide antimicrobial activity against a number of bacterial, viral and fungal pathogens in vitro. Therefore, these proteins, alone or in combinations, have been incorporated as preservatives in foods and pharmaceuticals as well as in oral health care products to restore salivas' own antimicrobial capacity in patients with dry mouth. These antimicrobials used in oral health care products, such as dentifrices, mouth-rinses, moisturizing gels and chewing gums, have been purified from bovine colostrum. In this review I critically evaluate the clinical efficacy and safety of this kind of preventive approach against various oral diseases and symptoms.

The gut's role in metabolism, mucosal barrier function, and gut immunology

The gastrointestinal tract functions not only to absorb nutrients, it also plays an important immunologic role during health and critical illness. Under experimental and certain clinical conditions, stimulating the gut attentuates the stress response and avoids mucosal atrophy and increases permeability. Gut stimulation prevents atrophy of the gut-associated lymphoid tissue, the body's major defender of moist mucosal surfaces. A better understanding of gut function and improved nutrient delivery has clinical implications in the treatment of critically ill patients.

Antimicrobial factors, sialic acid, and protein concentration in whole saliva of the elderly

Concentrations of salivary antimicrobial factors are well documented in children and young adults, but little information is available on such defense factors in healthy elderly persons. We determined the levels of total IgA, total IgG, lysozyme, lactoferrin, myeloperoxidase, salivary peroxidase, amylase, sialic acid, and total protein in a group of 71 subjects aged 76, 81, and 86 yr, as well as their correlations to paraffin-wax-stimulated salivary flow rate. Participants were either unmedicated (n = 67) or using medicines with no oral significance (n = 4). Statistically significant negative correlations existed between flow rate and total IgA, lysozyme, lactoferrin, sialic acid, and total protein. Concentrations of sialic acid and salivary peroxidase were highest in the oldest age group. Total IgA concentration was higher in women than in men, although men showed higher concentrations of sialic acid and higher sialic acid/total protein ratios. Subjects with poor gingival health had higher concentrations of total protein than did those with no need for periodontal treatment. Edentulous subjects with complete dentures showed significantly lower concentrations of IgG, lactoferrin, and myeloperoxidase than did dentate subjects. Our results suggest that, when compared with data from previous studies, concentrations of salivary antimicrobial agents do not decline with age in unmedicated elderly people. However, defense factors which are derived also from gingival crevicular fluid are decreased in the absence of teeth.

Agglutination of Streptococcus mutans serotype C cells but inhibition of Porphyromonas gingivalis autoaggregation by human lactoferrin

The ability of various forms of human lactoferrin (LF) to agglutinate oral Streptococcus mutans, Strep. sobrinus, Strep. rattus, Strep. sanguis, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans cells was studied spectrophotometrically. Fe3+ saturated LF was unable to agglutinate these bacteria, whereas iron-free LF (apo LF) effectively agglutinated Strep. mutans cells but not the other bacteria. The efficiency and rate of agglutination of Strep. mutans were somewhat lower with apo LF than with human whole saliva. However, secretory IgA, phosphate and whole saliva almost totally abolished the apo LF-mediated agglutination of Strep. mutans, suggesting binding to the same target sites on bacterial cell surfaces, or to each other. The presence of exogenous iron (Fe2+, Fe3+), lactoperoxidase or serum albumin did not affect the agglutination by apo LF. Low Ca2+ (50-100 microns) slightly enhanced the agglutination by apo LF but higher concentrations (0.5-1.0 mM) totally blocked the apo LF-mediated agglutination of Strep. mutans. Both saliva and apo LF significantly delayed the rapid autoaggregation of P. gingivalis cells. Aggregation of P. gingivalis is considered a potential virulence factor and a protective mechanism against the host's cellular defences in the gingival crevice. These findings show a novel, strain-specific antibacterial mechanism for LF against Strep. mutans and P. gingivalis and adds a new compound to the group of agglutinating proteins in human saliva.