Role of lactoferrin and lactoferrin-derived peptides in oral and maxillofacial diseases.

The oral cavity harbors different taxonomic groups, the evolutionary coexistence of which develops the oral ecosystem. These resident microorganisms can alter the balance between the physiologic and pathologic conditions that affect the host, both locally and systemically. This highly sophisticated nature of the oral cavity poses a significant therapeutic challenge. Numerous human and animal studies have been conducted to potentiate the efficacy and competence of current treatments of pathologic conditions as well as to develop novel therapeutic modalities. One of these studies is the use of the potent antimicrobial agent lactoferrin (LF), which was originally derived from the host immune system. LF is an 80-kDa glycoprotein that has a free iron sequestration mechanism with evident antimicrobial, anti-tumor, and immunomodulatory properties. A wide range of active peptides have been isolated from the N-terminal region of LF, which possess antimicrobial activities. In this review, we discuss the role of LF and LF-derived peptides under a heterogeneous group of oral and maxillofacial conditions, including bacterial, fungal, viral infections; head and neck cancers; xerostomia; and implantology-bone-related manifestations.

Human lactoferrin protects against Streptococcus mutans-induced caries in mice.

OBJECTIVES: The objective of this study is to evaluate the importance of human lactoferrin (hLF) in an experimental caries induced by Streptococcus mutans in a lactoferrin-knockout (LFKO(-/-)) mouse model compared with C576J/BL wild-type (WT) mice. MATERIALS AND METHODS: The WT and LFKO(-/-) mice were infected with S. mutans (1 × 10(8) cells) and/or sham infection. Furthermore, the effect of hLF administration was evaluated in LFKO(-/-) mice infected with S. mutans. Mice were assessed for colonization, salivary pH, and caries development. RESULTS: The results showed that the lactoferrin-knockout infected (LFKO(-/-) I) mice had significantly higher colonization with S. mutans (P = 0.02), lower salivary pH (P = 0.01), and more carious lesions (P = 0.01) when compared to wild-type infected (WTI) mice. In addition, the administration of hLF did not show any evidence of S. mutans colonization as well as carious lesions (P = 0.001) in LFKO(-/-) I mice when compared to untreated LFKO(-/-) I mice. CONCLUSION: These results show that endogenous LF protects against S. mutans-induced caries and that exogenous hLF can exert a protective effect against caries development.

Oral lactoferrin protects against experimental candidiasis in mice.

AIMS: To determine the role of human lactoferrin (hLF) in protecting the oral cavities of mice against Candida albicans infection in lactoferrin knockout (LFKO(-/-)) mice was compared to wild-type (WT) mice. We also aim to determine the protective role of hLF in LFKO(-/-) mice. METHODS AND RESULTS: Antibiotic-treated immunosuppressed mice were inoculated with C. albicans (or sham infection) by oral swab and evaluated for the severity of infection after 7 days of infection. To determine the protective role of hLF, we added 0·3% solution of hLF to the drinking water given to some of the mice. CFU count, scoring of lesions and microscopic observations were carried out to determine the severity of infection. LFKO(-/-) I mice showed a 2 log (P = 0·001) higher CFUs of C. albicans in the oral cavity compared to the WT mice infected with C. albicans (WTI). LFKO(-/-) I mice given hLF had a 3 log (P = 0·001) reduction in CFUs in the oral cavity compared to untreated LFKO(-/-) I mice. The severity of infection, observed by light microscopy, revealed that the tongue of the LFKO(-/-) I mice showed more white patches compared to WTI and LFKO(-/-) I + hLF mice. Scanning electron microscopic observations revealed that more filiform papillae were destroyed in LFKO(-/-) I mice when compared to WTI or LFKO(-/-) I + hLF mice. CONCLUSIONS: Human LF is important in protecting mice from oral C. albicans infection. Administered hLF may be used to prevent C. albicans infection. SIGNIFICANCE AND IMPACT OF THE STUDY: Human LF, a multifunctional iron-binding glycoprotein can be used as a therapeutic active ingredient in oral healthcare products against C. albicans.

Protective effects of human lactoferrin during Aggregatibacter actinomycetemcomitans-induced bacteremia in lactoferrin-deficient mice.

Aggregatibacter actinomycetemcomitans, a periodontopathogen, has been associated with several systemic diseases. Herein, we report the protective effect of human lactoferrin (hLF) during A. actinomycetemcomitans bacteremia in lactoferrin knockout (LFKO(-/-)) mice. The prophylactic, concurrent, and therapeutic intravenous (i.v.) administrations of hLF significantly cleared the bacteria from blood and organs. Nevertheless, all modes of hLF administration significantly decreased the concentrations of serum proinflammatory cytokines, such as interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-1ß (IL-1ß), IL-6, IL-10, and IL-12p70. Additionally, hLF administration significantly decreased hepatic and splenic proinflammatory cytokine expression levels compared to those in the non-hLF-treated group. Furthermore, administration of hLF decreased the serum C-reactive protein level, inducible nitric oxide synthase (iNOS) and myeloperoxidase (MPO) gene expression levels in liver and spleen. hLF treatment has also resulted in a 6-fold decrease in spleen weight with the migration of typical inflammatory cells in infected mice as a result of decreased inflammatory response. These results reveal that hLF protects against A. actinomycetemcomitans bacteremia, as indicated by rapid bacterial clearance and decreased host proinflammatory mediators.

Lactoferrin knockout mice demonstrates greater susceptibility to Aggregatibacter actinomycetemcomitans-induced periodontal disease.

BACKGROUND: Among the innate defense mechanisms in the oral cavity, lactoferrin (LF) is a vital antimicrobial that can modify the host response against periodontopathogens. Aggregatibacter actinomycetemcomitans is the main periodontopathogen of localized aggressive periodontitis. The aim of this study is to evaluate the role of LF during A. actinomycetemcomitans-induced periodontitis. METHODS: Differences in the expression levels of cytokines, chemokines, chemokine receptors, and bone loss markers between wild-type (WT) and LF knockout mice (LFKO(-/-)) were evaluated by real time-PCR. Serum IgG and LF levels were quantified by ELISA. Alveolar bone loss among the groups was estimated by measuring the distance from cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) at 20 molar sites. RESULTS: Oral infection with A. actinomycetemcomitans increased LF levels in periodontal tissue (P = 0.01) and saliva (P = 0.0004) of wild-type infected (WTI) mice compared to wild-type control mice. Pro-inflammatory cytokines such as interferon-γ, tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, and IL-12 were increased in the infected LF knockout (LFKO(-/-)I) mice compared to the WTI mice, whereas the anti-inflammatory cytokines IL-4 and IL-10 were decreased. Chemokines and chemokine receptors showed different expression patterns between WTI and LFKO(-/-)I mice. The LFKO(-/-)I mice developed increased bone loss (P = 0.002), in conjunction with increased expression of receptor activator of nuclear factor-κB ligand and decrease in osteoprotegerin, compared to WTI mice. CONCLUSIONS: These results demonstrate that the infected LFKO(-/-) mice were more susceptible to A. actinomycetemcomitans-induced alveolar bone loss, with different patterns of immune responses compared to those of WTI mice.

Human salivary cystatin SA exhibits antimicrobial effect against Aggregatibacter actinomycetemcomitans.

BACKGROUND AND OBJECTIVE: Healthy subjects who do not have Aggregatibacter actinomycetemcomitans in their oral cavity may possess factors in saliva that might demonstrate antibacterial activity against the bacterium. The aim of this study was to identify and purify proteins from saliva of healthy subjects that might demonstrate antibacterial activity against A. actinomycetemcomitans and test the same against the bacteria. MATERIAL AND METHODS: Saliva from 10 healthy volunteers was tested individually for its anti-A. actinomycetemcomitans activity. Among the 10 subjects, eight demonstrated anti-A. actinomycetemcomitans activity. Saliva was collected from one healthy volunteer who demonstrated the highest antimicrobial activity against A. actinomycetemcomitans. After clarifying the saliva, it was subjected to an affinity chromatography column with A. actinomycetemcomitans. The proteins bound to A. actinomycetemcomitans were eluted from the column and identified using mass spectrometry (MALDI-TOF/TOF MS). Among other proteins that bound to A. actinomycetemcomitans, which included lactoferrin, immunoglobulin A and kallikrein, cystatin SA was observed in significantly higher concentrations, and this was purified from the eluate. The purified cystatin SA was tested at different concentrations for its ability to kill A. actinomycetemcomitans in a 2 h cell killing assay. The bacteria were also treated with a proteinase inhibitor, leupeptin, to clarify whether the antimicrobial effect of cystatin SA was related to its protease inhibitory function. Cystatin SA was also tested for its ability to prevent binding of A. actinomycetemcomitans to buccal epithelial cells (BECs) in an A. actinomycetemcomitans-BEC binding assay. RESULTS: Cystatin SA (0.1 mg/mL) demonstrated a statistically significant antimicrobial activity against A. actinomycetemcomitans. The effect of cystatin SA decreased with lower concentrations, with 0.01 mg/mL showing no effect. The addition of monoclonal cystatin SA antibodies to the purified sample completely negated the antimicrobial effect. Treatment of A. actinomycetemcomitans with leupeptin resulted in no antimicrobial effect, suggesting that the antimicrobial activity of cystatin SA is independent of its protease inhibitory function. A. actinomycetemcomitans pretreated with cystatin SA showed reduced binding to BECs, suggesting a potential role for cystatin SA in decreasing the colonization of A. actinomycetemcomitans. CONCLUSION: The present study shows that cystatin SA demonstrates antimicrobial activity against the periodontopathogen A. actinomycetemcomitans, and future studies determining the mechanism of action are necessary. The study also shows the ability of cystatin SA to reduce significantly the binding of A. actinomycetemcomitans to BECs.