Human trial of liposomal lactoferrin supplementation for periodontal disease

Exploring biological mechanisms in orthodontic tooth movement: Bridging the gap between basic research experiments and clinical applications - A comprehensive review

OBJECTIVES

The molecular mechanisms behind orthodontic tooth movements (OTM) were investigated by clarifying the role of chemical messengers released by cells.

METHODS

Using the Cochrane library, Google scholar, and PubMed databases, a literature search was conducted, and studies published from 1984 to 2024 were considered.

RESULTS

Both bone growth and remodeling may occur when a tooth is subjected to mechanical stress. These chemicals have a significant effect on the stimulation and regulation of osteoblasts, osteoclasts, and osteocytes during alveolar bone remodeling. This regulation can take place in pathological conditions, such as periodontal diseases, or during OTM alone. This comprehensive review outlines key molecular mechanisms underlying OTM and explores various clinical assumptions associated with specific molecules and their functional domains during this process. Furthermore, clinical applications of certain molecules such as relaxin, prostaglandin E (PGE), and interleukin-1β (IL-1β) in accelerating OTM have been reported. Our findings underscore the existing gap between OTM clinical applications and basic research investigations.

CONCLUSION

A comprehensive understanding of orthodontic treatment is enriched by insights into biological systems. We reported the activation of osteoblasts, osteoclast precursor cells, osteoclasts, and osteocytes in response to mechanical stress, leading to targeted cellular and molecular interventions and facilitating rapid and regulated alveolar bone remodeling during tooth movement. Despite the shortcomings of clinical studies in accelerating OTM, this review highlights the crucial role of biological agents in this process and advocates for prioritizing high-quality human studies in future research to gain further insights from clinical trials.

β-defensin 2 synthesized by a cell-free protein synthesis system and encapsulated in liposomes inhibits adhesion of Porphyromonas gingivalis to oral epithelial cells

β-defensin 2 (BD-2), an antimicrobial peptide (AMP), is expressed by oral epithelial cells and plays an important role in innate immunity of the oral cavity. Cell-free protein synthesis (CFPS) systems have been studied for the synthesis of various proteins, however, the synthesis of BD-2 by a CFPS system has not been extensively explored. Liposomes have been developed as tools for drug delivery. A delivery of liposome-encapsulated AMP to oral epithelium may be useful to prevent oral infectious diseases. In the present study, we investigated the antimicrobial activity of the BD-2 protein, artificially synthesized using a CFPS system and encapsulated in liposomes. BD-2 protein was artificially synthesized using template DNA and a reconstituted CFPS system and was identified by western blotting. Bilayer liposomes were prepared using 1,2-dioleoyl-sn-glycero-3-phospho-choline and 3-sn-phosphatidylcholine from egg yolk. The artificially synthesized BD-2 was encapsulated in liposomes, collected by ultrafiltration, and detected by western blotting. Human oral epithelial cells were cultured with the liposome-encapsulated BD-2 and the concentration of BD-2 in the cell lysate of the culture with the synthesized BD-2 was higher than that of the control cultures. The antimicrobial activity of the synthesized BD-2 was investigated by an adhesion assay of Porphyromonas gingivalis to oral epithelial cells. The artificially synthesized BD-2 and its liposome significantly inhibited adhesion of P. gingivalis to oral epithelial cells. These results suggest that artificially synthesized BD-2 and liposome-encapsulated BD-2 show antimicrobial activity and can potentially play a role in oral healthcare for periodontal diseases.

Antioxidant, anti-inflammatory and antimicrobial activity of natural products in periodontal disease: a comprehensive review

Periodontal diseases (PD) are common chronic inflammatory oral pathologies that are strongly linked to others not found in the mouth cavity. The immune system mediates the host response, which includes the upregulation of proinflammatory cytokines, metalloproteinases, and reactive oxygen species (ROS); the latter may play an important role in the establishment and progression of inflammatory diseases, particularly periodontal disease, via the development of oxidative stress (OS). Natural antioxidants have powerful anti-inflammatory properties, and some can reduce serum levels of key PD indicators such tumor necrosis factor (TNF) and interleukin IL-1. This review compiles, through a thorough literature analysis, the antioxidant, anti-inflammatory, and antibacterial effects of a variety of natural products, as well as their therapeutic potential in the treatment of PD.

The role of microbiome-host interactions in the development of Alzheimer´s disease

Alzheimer`s disease (AD) is the most prevalent cause of dementia. It is often assumed that AD is caused by an aggregation of extracellular beta-amyloid and intracellular tau-protein, supported by a recent study showing reduced brain amyloid levels and reduced cognitive decline under treatment with a beta-amyloid-binding antibody. Confirmation of the importance of amyloid as a therapeutic target notwithstanding, the underlying causes of beta-amyloid aggregation in the human brain, however, remain to be elucidated. Multiple lines of evidence point towards an important role of infectious agents and/or inflammatory conditions in the etiology of AD. Various microorganisms have been detected in the cerebrospinal fluid and brains of AD-patients and have thus been hypothesized to be linked to the development of AD, including Porphyromonas gingivalis (PG) and Spirochaetes. Intriguingly, these microorganisms are also found in the oral cavity under normal physiological conditions, which is often affected by multiple pathologies like caries or tooth loss in AD patients. Oral cavity pathologies are mostly accompanied by a compositional shift in the community of oral microbiota, mainly affecting commensal microorganisms and referred to as 'dysbiosis'. Oral dysbiosis seems to be at least partly mediated by key pathogens such as PG, and it is associated with a pro-inflammatory state that promotes the destruction of connective tissue in the mouth, possibly enabling the translocation of pathogenic microbiota from the oral cavity to the nervous system. It has therefore been hypothesized that dysbiosis of the oral microbiome may contribute to the development of AD. In this review, we discuss the infectious hypothesis of AD in the light of the oral microbiome and microbiome-host interactions, which may contribute to or even cause the development of AD. We discuss technical challenges relating to the detection of microorganisms in relevant body fluids and approaches for avoiding false-positives, and introduce the antibacterial protein lactoferrin as a potential link between the dysbiotic microbiome and the host inflammatory reaction.

Molecular Mechanisms of Inhibitory Effects of Bovine Lactoferrin on Invasion of Oral Squamous Cell Carcinoma

Lactoferrin (LF), an iron-binding glycoprotein, has been reported to have anticancer properties. However, the molecular mechanisms behind its anticancer effects on oral squamous cell carcinoma (OSCC) have not yet been elucidated. Therefore, we aimed to clarify the effects of LF on invasion of OSCC, and its underlying molecular mechanism. OSCC cell lines, HSC2 and HOC313, were treated with bovine LF (bLF). The effects of bLF on cell invasion were examined by a chamber migration assay, wound healing assay, and Boyden chamber method with a basement-membrane-analogue. Expression levels of MMP-1, MMP-3, and AP-1 were examined using RT-PCR, qRT-PCR, and western blotting. Roles of LRP1, a receptor of bLF, on cell invasion were analyzed using siLRP1 knockdown cells. Furthermore, to clarify the importance of LRP1 in invasion, the effects of bLF on tPA-induced invasion of OSCC cells were examined. The invasion assays showed that bLF suppressed invasion of the OSCC cells. Moreover, bLF down-regulated AP-1, and resulted in reductions of MMP-1 and MMP-3. With SiLRP1 knockdown, OSCC cells failed to induce their invasion, and bLF was not able to exert its effects on invasion. Furthermore, bLF remarkably inhibited tPA-induced cell invasion. These findings suggest the importance of LRP1 in bLF-suppressed invasion of OSCC cells via the reduction of AP-1 and MMP production.

Lactoferrin as a Component of Pharmaceutical Preparations: An Experimental Focus

Lactoferrin is an 80 kDa monomeric glycoprotein that exhibits multitask activities. Lactoferrin properties are of interest in the pharmaceutical field for the design of products with therapeutic potential, including nanoparticles and liposomes, among many others. In antimicrobial preparations, lactoferrin has been included either as a main bioactive component or as an enhancer of the activity and potency of first-line antibiotics. In some proposals based on nanoparticles, lactoferrin has been included in delivery systems to transport and protect drugs from enzymatic degradation in the intestine, favoring the bioavailability for the treatment of inflammatory bowel disease and colon cancer. Moreover, nanoparticles loaded with lactoferrin have been formulated as delivery systems to transport drugs for neurodegenerative diseases, which cannot cross the blood-brain barrier to enter the central nervous system. This manuscript is focused on pharmaceutical products either containing lactoferrin as the bioactive component or formulated with lactoferrin as the carrier considering its interaction with receptors expressed in tissues as targets of drugs delivered via parenteral or mucosal administration. We hope that this manuscript provides insights about the therapeutic possibilities of pharmaceutical Lf preparations with a sustainable approach that contributes to decreasing the resistance of antimicrobials and enhancing the bioavailability of first-line drugs for intestinal chronic inflammation and neurodegenerative diseases.

Effect of Lactoferrin Supplementation on Inflammation, Immune Function, and Prevention of Respiratory Tract Infections in Humans: A Systematic Review and Meta-analysis

Lactoferrin (Lf) is a glycoprotein present in human and bovine milk with antimicrobial and immune-modulating properties. This review aimed to examine the evidence for the effect of Lf supplementation on inflammation, immune function, and respiratory tract infections (RTIs) in humans. Online databases were searched up to December 2020 to identify relevant, English-language articles that examined the effect of Lf supplementation in human subjects of all ages, on either inflammation, immune cell populations or activity, or the incidence, duration, or severity of respiratory illness or RTIs. Twenty-five studies (n = 20 studies in adults) were included, of which 8 of 13 studies (61%) in adults reported a decrease in at least 1 systemic inflammatory biomarker. Immune function improved in 6 of 8 studies (75%) in adults, with changes in immune cell populations in 2 of 6 studies (33%), and changes in immune cell activity in 2 of 5 studies (40%). RTI outcomes were reduced in 6 of 10 studies (60%) (n = 5 in adults, n = 5 in children), with decreased incidence in 3 of 9 studies (33%), and either decreased frequency (2/4, 50%) or duration (3/6, 50%) in 50% of studies. In adults, Lf reduced IL-6 [mean difference (MD): -24.9 pg/mL; 95% CI: -41.64, -8.08 pg/mL], but not C-reactive protein (CRP) [standardized mean difference: -0.09; 95% CI: -0.82, 0.65], or NK cell cytotoxicity [MD: 4.84%; 95% CI: -3.93, 13.60%]. RTI incidence was reduced in infants and children (OR: 0.78; 95% CI: 0.61, 0.98) but not in adults (OR: 1.00; 95% CI: 0.76, 1.32). Clinical studies on Lf supplementation are limited, although findings show 200 mg Lf/d reduces systemic inflammation, while formulas containing 35-833 mg Lf/d may reduce RTI incidence in infants and children, suggesting improved immune function. Future research is required to determine optimal supplementation strategies and populations most likely to benefit from Lf supplementation. This trial was registered at PROSPERO (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021232186) as CRD42021232186.

Circulating inflammatory cell profiling and periodontitis: A systematic review and meta-analysis

Inflammation is a key driver of common noncommunicable diseases. Among common triggers of inflammation, chronic gingival inflammation (periodontitis) triggers a consistent humoral host inflammatory response, but little is known on its impact on circulating inflammatory cell profiles. We aimed to systematically appraise all the evidence linking periodontitis and its treatment to circulating inflammatory cell profiles. From 6 databases, 157 studies were eligible for qualitative synthesis and 29 studies for meta-analysis. Our meta-analysis showed that participants with periodontitis exhibited a significant mean increase in circulating CD4⁺ , CD4⁺ CD45RO⁺ , IFNγ-expressing CD4⁺ and CD8⁺ T cells, CD19⁺ CD27⁺ and CD5⁺ B cells, CD14⁺ CD16⁺ monocytes, and CD16⁺ neutrophils but decrease in CD8⁺ T and CD14⁺⁺ CD16^- monocytes. Our qualitative synthesis revealed that peripheral blood neutrophils of patients with periodontitis consistently showed elevated production of reactive oxygen species (ROS) when compared with those of healthy controls. Some evidence suggested that the treatment of periodontitis reversed the exaggerated ROS production, but limited and inconclusive data were found on several circulating inflammatory cell profiling. We conclude that periodontitis and its treatment are associated with minor but consistent alterations in circulating inflammatory cell profiles. These changes could represent key mechanisms explaining the association of periodontitis with other comorbidities such as cardiovascular disease, diabetes, and rheumatoid arthritis.

Bovine lactoferrin inhibits alveolar bone destruction in an orthodontic rat model with periodontitis

OBJECTIVE

We aimed to evaluate the effect of bovine lactoferrin (bLF) on alveolar bone destruction and remodelling under orthodontic force (OF) in periodontitis-affected rats.

MATERIAL AND METHODS

After establishing the periodontitis-affected rat model with lipopolysaccharides (LPS), the left maxillary first molars were moved orthodontically under a force of 0.2N. Based on saline or bLF gavage, 54 Sprague-Dawley (SD) rats were randomized into 5 groups: A (blank), P1 (LPS+OF+bLF), P2 (LPS+OF+saline), C1 (OF+bLF), and C2 (OF+saline). Animals were evaluated using micro-computed tomography (micro-CT) followed by haematoxylin and eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining, and the LF level was determined using ELISA in the gingival crevicular fluid (GCF) of the experimental teeth. Immunohistochemistry helped to detect expression changes in RANKL, OPG and COX-2.

RESULTS

Micro-CT results indicated that compared with group P2, trabecular number (Tb.N) and trabecular thickness (Tb.Th) in group P1 were higher and bone surface/bone volume (BS/BV) was lower on day 14, while trabecular separation (Tb.Sp) decreased significantly on Day 5 and Day 14 after bLF gavage (P<0.05). This was supported by changes in H&E and TRAP staining. bLF down-regulated RANKL level at both timepoints and up-regulated OPG level on Day 14 in periodontitis rats (P<0.05). The significant changes mentioned above were not observed between group C1 and C2 (P>0.05). No significant change in COX-2 levels were observed in any group (P>0.05). The lactoferrin level in GCF increased significantly after bLF gavage (P<0.05).

CONCLUSION

Bovine lactoferrin inhibited LPS-induced bone destruction, but the bone healing effect was independent of orthodontic aseptic inflammatory bone remodelling.

Lactoferrin from Bovine Milk: A Protective Companion for Life

Lactoferrin (Lf), an iron-binding multifunctional glycoprotein belonging to the transferrin family, is present in most biological secretions and reaches particularly high concentrations in colostrum and breast milk. A key function of lactoferrin is non-immune defence and it is considered to be a mediator linking innate and adaptive immune responses. Lf from bovine milk (bLf), the main Lf used in human medicine because of its easy availability, has been designated by the United States Food and Drug Administration as a food additive that is generally recognized as safe (GRAS). Among the numerous protective activities exercised by this nutraceutical protein, the most important ones demonstrated after its oral administration are: Antianemic, anti-inflammatory, antimicrobial, immunomodulatory, antioxidant and anticancer activities. All these activities underline the significance in host defence of bLf, which represents an ideal nutraceutical product both for its economic production and for its tolerance after ingestion. The purpose of this review is to summarize the most important beneficial activities demonstrated following the oral administration of bLf, trying to identify potential perspectives on its prophylactic and therapeutic applications in the future.

Lactoferrin in Bone Tissue Regeneration

Among the multiple properties exhibited by lactoferrin (Lf), its involvement in bone regeneration processes is of great interest at the present time. A series of in vitro and in vivo studies have revealed the ability of Lf to promote survival, proliferation and differentiation of osteoblast cells and to inhibit bone resorption mediated by osteoclasts. Although the mechanism underlying the action of Lf in bone cells is still not fully elucidated, it has been shown that its mode of action leading to the survival of osteoblasts is complemented by its mitogenic effect. Activation of several signalling pathways and gene expression, in an LRPdependent or independent manner, has been identified. Unlike the effects on osteoblasts, the action on osteoclasts is different, with Lf leading to a total arrest of osteoclastogenesis. Due to the positive effect of Lf on osteoblasts, the potential use of Lf alone or in combination with different biologically active compounds in bone tissue regeneration and the treatment of bone diseases is of great interest. Since the bioavailability of Lf in vivo is poor, a nanotechnology- based strategy to improve the biological properties of Lf was developed. The investigated formulations include incorporation of Lf into collagen membranes, gelatin hydrogel, liposomes, loading onto nanofibers, porous microspheres, or coating onto silica/titan based implants. Lf has also been coupled with other biologically active compounds such as biomimetic hydroxyapatite, in order to improve the efficacy of biomaterials used in the regulation of bone homeostasis. This review aims to provide an up-to-date review of research on the involvement of Lf in bone growth and healing and on its use as a potential therapeutic factor in bone tissue regeneration.

Recombinant fimbriae protein of Porphyromonas gingivalis induces an inflammatory response via the TLR4/NF‑κB signaling pathway in human peripheral blood mononuclear cells

Porphyromonas gingivalis (P. gingivalis) is a periodontal pathogen that may accumulate with other organisms in subgingival plaque biofilms and is associated with periodontal disease. P. gingivalis fimbriae (FimA) is a filamentous structure on the surface of bacteria that is closely associated with bacterial adhesion to and colonization of host tissues, and serves an essential role in biofilm formation. The present study aimed to construct P. gingivalis FimA prokaryotic expression plasmids, purify a FimA fusion protein and explore the effect of a recombinant FimA protein on the inflammatory response in human peripheral blood mononuclear cells (PBMCs). P. gingivalis FimA prokaryotic expression plasmids were constructed by gene cloning and recombination technology. SDS-PAGE was used to evaluate the purified recombinant FimA protein. The cell proliferation rate and inflammatory cytokine expression of PBMCs treated with the FimA fusion protein with or without transfection with toll-like receptor 4 (TLR4) small interfering (si)RNA were detected by CCK-8 assays and ELISAs, respectively. The expression levels of TLR4, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and myeloid differentiation primary response 88 (MyD88) in PBMCs were detected by western blot analysis and reverse transcription quantitative polymerase chain reaction. A FimA fusion protein with high purity was obtained. FimA fusion protein treatment significantly increased PBMC proliferation and promoted the release of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, matrix metalloproteinase (MMP)-8 and MMP-9 in PBMCs. TLR4 interference reversed the effects of the FimA fusion protein on PBMC proliferation and inflammatory cytokine release. The expression levels of TLR4, NF-κB and MyD88 in PBMCs were significantly increased following treatment with the FimA fusion protein, while the expression levels of these genes at the mRNA and protein levels decreased significantly in PBMCs following FimA fusion protein treatment and TLR4 interference. The FimA fusion protein increased PBMC proliferation and promoted the release of the inflammatory cytokines TNF-α, IL-6, MMP-8 and MMP-9 via the TLR4/NF-κB signaling pathway. FimA may serve as a promising therapeutic strategy for periodontal disease.

Oral lactoferrin influences psychological stress in humans: A single-dose administration crossover study

Lactoferrin is a secretory protein with various physiological functions. Bovine lactoferrin has been demonstrated to alleviate psychological stresses in rats, but this effect in humans has not yet been assessed. The present study aimed to investigate the changes in psychological stress markers following a calculation task, with either lactoferrin or a placebo orally administered prior to the task. A total of 16 healthy female college students visited Juntendo University, Inzai, Japan following an overnight fast. Subjects were quietly seated for 15 min to stabilize the respiratory rate at 0.25 Hz (one breath every 4 sec). Then, subjects provided saliva, ingested either lactoferrin (800 mg of lactoferrin + soy milk) or a placebo (soy milk), remained seated for another 15 min with respiration rate at 0.25 Hz, and performed a calculation task. The task comprised two sets of 15-min calculations, with a 5-min interval between sets. Each calculation set consisted of various multiplications and divisions using pairs of three-digit numbers. Following the calculation task, saliva was collected again. Heart rate was also monitored to identify the frequency domain of heart-rate variability. The calculation task resulted in increased activity of salivary amylase, and decreased concentration of chromogranin A for both lactoferrin (P=0.028 and P<0.001, respectively) and placebo (P=0.003 and P<0.001, respectively) treatments. The degrees of changes in these salivary markers were similar between the two treatments. Heart rate variability exhibited an increase in the high-frequency (HF) component (P=0.022) and a decrease in low-frequency (LF)/HF and LF/(LF+HF) ratios (both P<0.001) following the calculation task under the placebo condition, demonstrating an upregulation of parasympathetic and a downregulation of sympathetic nervous activities. These changes in parasympathetic (HF) and sympathetic (LF/HF) activities, however, were alleviated by lactoferrin compared with the placebo (P=0.007 and P=0.026, respectively). Collectively these results suggest that oral lactoferrin may mitigate psychological stress in humans.

Lactoferrin, a Pleiotropic Protein in Health and Disease

SIGNIFICANCE

Lactoferrin (Lf) is a nonheme iron-binding glycoprotein strongly expressed in human and bovine milk and it plays many functions during infancy such as iron homeostasis and defense against microorganisms. In humans, Lf is mainly expressed in mucosal epithelial and immune cells. Growing evidence suggests multiple physiological roles for Lf after weaning.

RECENT ADVANCES

The aim of this review is to highlight the recent advances concerning multifunctional Lf activities.

CRITICAL ISSUES

First, we will provide an overview of the mechanisms related to Lf intrinsic synthesis or intestinal absorption as well as its interaction with a wide spectrum of mammalian receptors and distribution in organs and cell types. Second, we will discuss the large variety of its physiological functions such as iron homeostasis, transportation, immune regulation, oxidative stress, inflammation, and apoptosis while specifying the mechanisms of action. Third, we will focus on its recent physiopathology implication in metabolic disorders, including obesity, type 2 diabetes, and cardiovascular diseases. Additional efforts are necessary before suggesting the potential use of Lf as a diagnostic marker or as a therapeutic tool.

FUTURE DIRECTIONS

The main sources of Lf in human cardiometabolic disorders should be clarified to identify new perspectives for future research and develop new strategies using Lf in therapeutics. Antioxid. Redox Signal. 24, 813-836.

A high-fiber, low-fat diet improves periodontal disease markers in high-risk subjects: a pilot study

Periodontal disease is related to aging, smoking habits, diabetes mellitus, and systemic inflammation. However, there remains limited evidence about causality from intervention studies. An effective diet for prevention of periodontal disease has not been well established. The current study was an intervention study examining the effects of a high-fiber, low-fat diet on periodontal disease markers in high-risk subjects. Forty-seven volunteers were interviewed for recruitment into the study. Twenty-one volunteers with a body mass index of at least 25.0 kg/m(2) or with impaired glucose tolerance were enrolled in the study. After a 2- to 3-week run-in period, subjects were provided with a test meal consisting of high fiber and low fat (30 kcal/kg of ideal body weight) 3 times a day for 8 weeks and followed by a regular diet for 24 weeks. Four hundred twenty-five teeth from 17 subjects were analyzed. Periodontal disease markers assessed as probing depth (2.28 vs 2.21 vs 2.13 mm; P < .0001), clinical attachment loss (6.11 vs 6.06 vs 5.98 mm; P < .0001), and bleeding on probing (16.2 vs 13.2 vs 14.6 %; P = .005) showed significant reductions after the test-meal period, and these improvements persisted until the follow-up period. Body weight (P < .0001), HbA1c (P < .0001), and high-sensitivity C-reactive protein (P = .038) levels showed improvement after the test-meal period; they returned to baseline levels after the follow-up period. In conclusion, treatment with a high-fiber, low-fat diet for 8 weeks effectively improved periodontal disease markers as well as metabolic profiles, at least in part, by effects other than the reduction of total energy intake.

A review of therapeutic prospects of non-viral gene therapy in the retinal pigment epithelium

Ocular gene therapy has been extensively explored in recent years as a therapeutic avenue to target diseases of the cornea, retina and retinal pigment epithelium (RPE). Adeno-associated virus (AAV)-mediated gene therapy has shown promise in several RPE clinical trials but AAVs have limited payload capacity and potential immunogenicity. Traditionally however, non-viral alternatives have been plagued by low transfection efficiency, short-term expression and low expression levels. Recently, these drawbacks have begun to be overcome by the use of specialty carriers such as polylysine, liposomes, or polyethyleneimines, and by inclusion of suitable DNA elements to enhance gene expression and longevity. Recent advancements in the field have yielded non-viral vectors that have favorable safety profiles, lack immunogenicity, exhibit long-term elevated gene expression, and show efficient transfection in the retina and RPE, making them poised to transition to clinical applications. Here we discuss the advancements in nanotechnology and vector engineering that have improved the prospects for clinical application of non-viral gene therapy in the RPE.

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)-1β, 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.

LF immunomodulatory strategies: mastering bacterial endotoxin1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal's usual peer review process

Lactoferrin (LF), an iron-binding glycoprotein expressed in most biological fluids, represents a major component of mammalian innate immune system. The multiple activities of LF rely not only on its capacity to bind iron but also to interact with molecular and cellular components of both the host and pathogens. LF can bind and sequester lipopolysaccharide thus preventing proinflammatory pathway activation, sepsis, and tissue damage. However, the interplay between LF and lipopolysaccharide is complex and may lead to different outcomes including both the suppression of inflammatory response and immune activation. Understanding the molecular basis and the functional consequences of this complex interaction is critically relevant in the development of LF-based therapeutic interventions in humans.