Salivary concentration of free LL-37 in edentulism, chronic periodontitis and healthy periodontium

The Impact of Vitamin Deficiencies on Oral Manifestations in Children

Vitamins play a vital role in human health, particularly in the development and maintenance of oral health in children. These nutrients are broadly categorized into fat-soluble and water-soluble types, crucial for children's well-being. The objective of this study is to investigate the impact of vitamin deficiencies on the oral health of children, focusing on how these deficiencies contribute to various oral health issues and determining the relationship between specific vitamin shortages and oral diseases. Findings indicate that shortages in vitamins A and D lead to enamel issues and a higher susceptibility to dental diseases, vitamin E assists in treating oral mucositis, and vitamin K is essential for blood clotting in dental surgeries. Deficits in B-complex and vitamin C result in enamel hypomineralization and soft tissue ailments, including aphthous stomatitis and gingival petechiae. Additionally, a lack of vitamin B7 compromises the immune response, increasing oral candidiasis risk. Therefore, vitamin deficiencies markedly affect children's oral health, highlighting the need for joint efforts between dental professionals and caregivers for effective pediatric care. Addressing vitamin deficiencies through supplementation and tailored dental care emphasizes the significance of nutritional health in children's overall and dental well-being, advocating for a collaborative approach to achieve optimal health outcomes.

The Antimicrobial Peptide LL-37 as a Predictor Biomarker for Periodontitis with the Presence and Absence of Smoking: A Case-Control Study

Background

A major issue is finding a valid biomarker able to diagnose periodontal disease with the presence and absence of risk factors. Indeed, the association between smoking and periodontal diseases and its impact on the manifestation of antimicrobial peptides has been delineated in clinical and epidemiological investigations. The antimicrobial peptide cathelicidin (LL-37) is pivotal in preserving periodontal health.

Objectives

This investigation examines and contrasts the levels of cathelicidin in the saliva of smokers and nonsmokers of periodontitis. The study also seeks to establish this biomarker's diagnostic ability to differentiate between periodontal health and disease.

Materials and Methods

The study involved the collection of unstimulated saliva samples from 160 participants, comprising 80 patients diagnosed with periodontitis (40 of whom were smokers and 40 were nonsmokers) and 80 periodontitis-free individuals (40 smokers and 40 nonsmokers). The clinical periodontal parameters were assessed, including recording the probing pocket depth, the level of clinical attachment, and the percentage of bleeding on probing. Subsequently, enzyme-linked immunosorbent assays were conducted to quantify the protein levels of LL-37 in the saliva samples obtained from the subjects mentioned above.

Results

The highest level of salivary LL-37 was found in the nonsmoker periodontitis (NSP) patients, followed by the group of smoker periodontitis (SP) and then nonsmoker healthy (NSH) group, while the lowest level was found in the healthy smoker (HS) group. At the same time, the LL-37 seems to be a very good biomarker in differentiating periodontal health from disease with the presence and absence of smoking.

Conclusion

Periodontitis results in a significant elevation of salivary LL-37 levels in smoker and nonsmoker patients compared to healthy individuals. These levels are positively correlated with the periodontal parameter and can serve as a valuable diagnostic tool to predict periodontitis, whereas smoking significantly reduces these levels.

Host's Immunity and Candida Species Associated with Denture Stomatitis: A Narrative Review

Denture-related Candida stomatitis, which has been described clinically in the literature, is either localized or generalized inflammation of the oral mucosa in connection with a removable prosthesis. During this inflammatory process, the mycobacterial biofilm and the host’s immune response play an essential role. Among microorganisms of this mixed biofilm, the Candida species proliferates easily and changes from a commensal to an opportunistic pathogen. In this situation, the relationship between the Candida spp. and the host is influenced by the presence of the denture and conditioned both by the immune response and the oral microbiota. Specifically, this fungus is able to hijack the innate immune system of its host to cause infection. Additionally, older edentulous wearers of dentures may experience an imbalanced and decreased oral microbiome diversity. Under these conditions, the immune deficiency of these aging patients often promotes the spread of commensals and pathogens. The present narrative review aimed to analyze the innate and adaptive immune responses of patients with denture stomatitis and more particularly the involvement of Candida albicans sp. associated with this pathology.

Cathelicidin LL-37 in Health and Diseases of the Oral Cavity

The mechanisms for maintaining oral cavity homeostasis are subject to the constant influence of many environmental factors, including various chemicals and microorganisms. Most of them act directly on the oral mucosa, which is the mechanical and immune barrier of the oral cavity, and such interaction might lead to the development of various oral pathologies and systemic diseases. Two important players in maintaining oral health or developing oral pathology are the oral microbiota and various immune molecules that are involved in controlling its quantitative and qualitative composition. The LL-37 peptide is an important molecule that upon release from human cathelicidin (hCAP-18) can directly perform antimicrobial action after insertion into surface structures of microorganisms and immunomodulatory function as an agonist of different cell membrane receptors. Oral LL-37 expression is an important factor in oral homeostasis that maintains the physiological microbiota but is also involved in the development of oral dysbiosis, infectious diseases (including viral, bacterial, and fungal infections), autoimmune diseases, and oral carcinomas. This peptide has also been proposed as a marker of inflammation severity and treatment outcome.

Host Defence Peptides in Diabetes Mellitus Type 2 Patients with Periodontal Disease. A Systematic Review

The aim of the study was to critically assess and review the latest evidence relating the associations between host defence peptides (HDPs), periodontal diseases (PD) and diabetes mellitus type 2 (DM2). To explore studies on HDPs, periodontal disease, and DM2, researchers utilised specific key phrases to search the electronic databases PubMed (National Library of Medicine), Embase (Ovid), Medline (EBSCO), and Dentistry and Oral Sciences (EBSCO). Quality assessment was conducted by means of the Newcastle Ottawa scale and the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool. Following a thorough screening process, a total of 12 papers (4 case-control, 6 cross-sectional, 1 animal, and 1 in vitro) fulfilled the selection criteria and were included. The majority of research found that HDPs were upregulated in DM2 patients with PD. Three investigations, however, found that HDPs were downregulated in DM2 patients with PD. HDPs play a part in the pathophysiology of PD and DM2. Nonetheless, more human, animal and laboratory investigations are needed to fully understand validation of the link, as the evidence is limited. Understanding HDPs as common moderators is critical, aimed at unlocking their potential as therapeutic and diagnostic agents.

Exogenous LL-37 but not homogenates of desquamated oral epithelial cells shows activity against Streptococcus mutans

OBJECTIVE

The antimicrobial peptide hCAP18/LL-37 is detected in desquamated epithelial cells of human whole saliva, but the functional importance of this pool of hCAP18/LL-37 is not understood. Here, we assess the impact of homogenates of desquamated oral epithelial cells and exogenous, synthetic LL-37 on two oral bacteria: S. mutans and S. gordonii.

MATERIAL AND METHODS

Desquamated epithelial cells of unstimulated whole saliva were isolated and cellular and extracellular levels of hCAP18/LL-37 analyzed by ELISA. Bacterial viability was determined by BacLight Live/Dead staining and confocal laser scanning microscopy.

RESULTS

Desquamated oral epithelial cells harboured hCAP18/LL-37, and they spontaneously released/leaked the peptide to their medium. Exogenous, synthetic LL-37 showed cytotoxic activity against S. mutans but not S gordonii, suggesting that LL-37 acts differentially on these two types of oral bacteria. Homogenates of desquamated oral epithelial cells had no effect on S. mutans viability. Treatment with exogenous, synthetic LL-37 (8 and 10 μM) reduced S. mutans viability, whereas lower concentrations (0.1 and 1 µM) of the peptide lacked effect.

CONCLUSIONS

Desquamated oral epithelial cells contain hCAP18/LL-37, but their cellular levels of hCAP18/LL-37 are too low to affect S. mutans viability, whereas exogenous, synthetic LL-37 has a strong effect on these bacteria.

The multifaceted roles of antimicrobial peptides in oral diseases

Antimicrobial peptides are naturally occurring protein molecules with antibacterial, antiviral and/or antifungal activity. Some antimicrobial peptides kill microorganisms through direct binding with negatively charged microbial surfaces. This action disrupts the cytoplasmic membrane and leads to the leakage of the cytoplasm. In addition, they are involved in the innate immune response. Antimicrobial peptides play an important role in oral health, as natural antimicrobial peptides are the first line of host defence in response to microbial infection. The level of natural antimicrobial peptides increases during severe disease conditions and play a role in promoting the healing of oral tissues. However, they are insufficient for eliminating pathogenic micro-organisms. The variability of the oral environment can markedly reduce the effect of natural antimicrobial peptides. Thus, researchers are developing synthetic antimicrobial peptides with promising stability and biocompatibility. Synthetic antimicrobial peptides are a potential alternative to traditional antimicrobial therapy. Pertinent to oral diseases, the deregulation of antimicrobial peptides is involved in the pathogenesis of dental caries, periodontal disease, mucosal disease and oral cancer, where they can kill pathogenic microorganisms, promote tissue healing, serve as biomarkers and inhibit tumor cells. This narrative review provides an overview of the multifaceted roles of antimicrobial peptides in oral diseases.

LL-37 and hBD-2 in the gingival crevicular fluid of smokers and nonsmokers with periodontitis

Abstract Introduction The association between smoking and periodontal diseases has been described in clinical and epidemiological studies. Objective The aim of this study was to compare the LL-37 and human β-defensin-2 (hBD-2) levels in crevicular fluid of patients with generalized periodontitis in smokers (S) and nonsmokers (NS). Material and method A total of 35 patients with generalized periodontitis stages III and IV, 15 NS (11 female, 4 male) and 20 S (7 female and 13 male), were included in the study. The evaluated clinical parameters were bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL). Enzyme-linked immunosorbent assays were performed to quantify the LL-37 and hBD-2 levels in the gingival crevicular fluid of these patients. The results were analyzed statistically with the level of significance set at 5%. Result In relation to periodontal clinical parameters, no statistically significant difference was observed for BOP and PD between groups S and NS. There was a higher CAL in the S group than in the NS group (p = 0.0095). There was no statistically significant difference between the levels of LL-37 and hBD-2 when comparing groups S and NS (p>0.05). Conclusion It was concluded that smokers have a higher clinical attachment loss than nonsmokers, but that smoking did not influence the levels of LL-37 and hBD-2 in the gingival crevicular fluid in periodontitis.

Mechanisms involved in regulation of periodontal ligament cell production of pro-inflammatory cytokines: Implications in periodontitis

It is well recognized that human periodontal ligament cells (PDL cells) may represent local immune cells of the periodontal tissues. However, it is unclear whether they represent “true” immune cells, since they can produce pro‐inflammatory cytokines not only after stimulation with bacterial lipopolysaccharides but also in response to other stimuli such as mechanical stress. Stimulation with bacterial lipopolysaccharides strongly enhances PDL cell production of pro‐inflammatory cytokines through activation of toll‐like receptors and NF‐κB signaling. Less information is available regarding putative modulators of cytokine production and their mechanisms of action in PDL cells. The anti‐inflammatory glucocorticoid dexamethasone reduces lipopolysaccharide‐induced PDL cell production of cytokines. Recent observations show that vitamin D and the antimicrobial peptide LL‐37 antagonize lipopolysaccharide‐stimulated PDL cell production of pro‐inflammatory cytokines. Secretory leukocyte protease inhibitor is endogenously expressed by PDL cells, and this protein negatively regulates PDL cell‐evoked cytokine production. More information and knowledge about the regulation of PDL cell production of cytokines may clarify the role of PDL cells in oral innate immunity and their importance in periodontitis.

Inhibitory effect of LL-37 and human lactoferricin on growth and biofilm formation of anaerobes associated with oral diseases

This study was conducted to evaluate the antimicrobial potential of the antimicrobial peptides (AMP) LL-37 and human Lactoferricin (LfcinH) on the planktonic growth and biofilm formation of oral pathogenic anaerobes related to caries and periodontitis. Multi-species bacterial suspensions of either facultative anaerobic bacteria (FAB: Streptococcus mutans, Streptococcus sanguinis, Actinomyces naeslundii) or obligate anaerobic bacteria (OAB: Veillonella parvula, Parvimonas micra, Fusobacterium nucleatum) were incubated with different concentrations of AMP solutions for 8 h. Planktonic growth was registered with an ATP-based cell viability assay for FAB and via plate counting for OAB. Biofilms were grown on ZrO₂ discs for 4 days in a mixture of the multi-species bacterial suspensions and AMP solutions. Biofilm mass was quantified using a microtiter plate biofilm assay with crystal violet staining. An overall planktonic growth inhibition and biofilm mass reduction of FAB and OAB was registered for LL-37 and LfcinH. Significant inhibitory threshold concentrations of LL-37 were observed in all experiments (p < 0.0001). No significant threshold was observed for LfcinH. Biofilm mass of OAB was barely reduced by LfcinH. The complete mechanisms of the AMPs are not fully understood yet. While LL-37 shows promising features as potential therapeutic for biofilm-associated oral diseases, LfcinH seems unsuitable for this particular indication. For clinical AMP use, further investigations will be necessary.

Salivary human beta-defensins and cathelicidin levels in relation to periodontitis and type 2 diabetes mellitus

Objective: Type 2 diabetes mellitus (T2DM) is a well-defined risk factor of periodontitis and it can affect expression of human beta-defensins (hBDs) and cathelicidin (LL-37) as well. The aim of the present study was to evaluate the impact of periodontitis and T2DM on salivary concentrations of these antimicrobial peptides.Material and methods: Unstimulated saliva samples, together with full-mouth periodontal recordings were collected from 92 individuals with periodontitis (63 with T2DM and 21 smokers) and 86 periodontally healthy controls (58 with T2DM and 21 smokers). Salivary hBD-1, -2, -3, LL-37, and advanced glycalization end products (AGE) concentrations were measured by enzyme-linked immunosorbent assay.Results: Among the periodontitis patients, T2DM group demonstrated lower levels of hBD-1 (p = .006), hBD-2 (p < .001) and hBD-3 (p < .001), and higher levels of LL-37 (p < .001) compared to systemically healthy controls. When only periodontally healthy controls were included into the analysis, higher hBD-1 (p = .002) and LL-37 (p < .001) levels were found in T2DM patients in comparison to systemically healthy controls. Salivary LL-37 levels were associated with HbA1c and periodontitis, while hBD-2, hBD-3 and levels associated only with HbA1c.Conclusion: In the limits of this study, hyperglycaemia can be proposed as a regulator of salivary hBD and cathelicidin levels. Periodontitis, on the other hand, affects only salivary LL-37 levels.

Oral manifestations of magnesium and vitamin D inadequacy

Adequate nutrition is essential for maintaining good oral health. Minerals such as magnesium, calcium, and phosphorus found in the diet constitute the main structural components of the tooth. Their inadequacy leads to absorption impairment, increased bleeding tendency, bone resorption, looseness, and premature tooth loss. Inadequacy of those essential minerals is associated with delayed tooth eruption and with enamel or dentin hypoplasia. Taking calcium without magnesium results in soft dental enamel, which cannot resist the acids causing tooth decay. In addition to magnesium, calcium, and phosphorus, adequate vitamin D is needed to maintain optimal oral health. Vitamin D exerts anti-inflammatory effects and helps in calcium absorption and bone remodeling. Moreover, adequate vitamin D status could reduce formation of dental caries by delaying its onset and progression. Here we summarize the oral manifestations of vitamin D and magnesium inadequacy.

What can we learn about functional importance of human antimicrobial peptide LL-37 in the oral environment from severe congenital neutropenia (Kostmann disease)?

The human antimicrobial peptide LL-37 is produced by neutrophils and epithelial cells, and the peptide can be detected in plasma as well as saliva. LL-37 is active against both gram-positive and gram-negative bacteria including oral pathogens such as Porphyromonas gingivalis and Streptococcus mutans. Besides its antimicrobial properties, LL-37 modulates the innate immune system, and furthermore, it also affects host cell viability. Although, both structural and functional properties of LL-37 have been extensively investigated, its physiological/pathophysiological importance in-vivo is not completely understood. In this review, Kostmann disease (morbus Kostmann) is highlighted since it may represent a LL-37 knockdown model which can provide new important information and insights about the functional role of LL-37 in the human in-vivo setting. Patients with Kostmann disease suffer from neutropenia, and although they are treated with recombinant granulocyte colony-stimulating factor (G-CSF) to normalize their levels of neutrophils, they lack or have very low levels of LL-37 in plasma, saliva and neutrophils. Interestingly, these patients suffer from severe periodontal disease, linking LL-37-deficiency to oral infections. Thus, LL-37 seems to play an important pathophysiological role in the oral environment antagonizing oral pathogens and thereby prevents oral infections.

Odontoblast-like MDPC-23 cells produce pro-inflammatory IL-6 in response to lipoteichoic acid and express the antimicrobial peptide CRAMP

Objective: Odontoblasts are thought to be involved in innate immunity but their precise role in this process is not fully understood. Here, we assess effects of lipopolysaccharide (LPS) and lipoteichoic acid (LTA), produced by Gram-negative and Gram-positive bacteria, respectively, on matrix metalloproteinase-8 (MMP-8), interleukin-6 (IL-6) and cathelin-related antimicrobial peptide (CRAMP) expression in odontoblast-like MDPC-23 cells.Material and methods: Gene activity and protein production was determined by quantitative real-time RT-PCR and ELISA, respectively. Cellular expression of CRAMP was determined by immunocytochemistry.Results: Stimulation with LTA (5 and 25 µg/ml) but not LPS (1 and 5 µg/ml) for 24 h enhanced IL-6 mRNA expression. The LTA-induced up-regulation of IL-6 mRNA levels was associated with increased IL-6 protein levels. Stimulation with either LPS or LTA for 24 h lacked effect on both MMP-8 transcript and protein expression. Immunocytochemistry disclosed that MDPC-23 cells expressed immunoreactivity for CRAMP. MDPC-23 cells showed mRNA expression for CRAMP, but stimulation with either LPS or LTA did not modulate CRAMP transcript expression.Conclusions: We show that MDPC-23 cells possess immune-like cell properties such as LTA-induced IL-6 production and expression of the antimicrobial peptide CRAMP, suggesting that odontoblasts may modulate innate immunity via these mechanisms.

Serum concentrations of antimicrobial peptide cathelicidin LL-37 in patients with bacterial lung infections

Nowadays, data indicate that antimicrobial peptides play an important role in immunological defense. Human cathelicidin LL-37 possesses a broad spectrum of antimicrobial properties against Gram-positive and Gram-negative bacteria, and is thereby an important component of defense mechanisms within the respiratory tract. In this study, we determined the LL-37 serum level in patients with pneumonia caused by different bacteria species in comparison with healthy subjects. Twenty-two patients with pneumonia caused by coccal Gram-positive bacteria (I), 16 patients with pneumonia caused by Haemophilus influenzae (II), 29 patients with pneumonia caused by members of the Enterobacteriaceae (III), 13 patients caused by non-fermenting Gram-negative bacteria (IV), and 30 healthy controls were enrolled in the study. Serum LL-37 concentration was measured using an enzyme-linked immunosorbent assay (ELISA). The mean LL-37 concentration in pneumonia patients was significantly higher in group I (p = 0.0032), group II (p = 0.0022), and group III (p = 0.019), and significantly lower in group IV (p = 0.000004) as compared with healthy volunteers. Our data suggest that LL-37 plays an important role in defense mechanisms during pneumonia. The reduced level of this peptide in subjects with pneumonia caused by opportunistic bacteria may reflect weakened immune system reactivity in these patients.

Cathelicidin LL-37 Affects Surface and Intracellular Toll-Like Receptor Expression in Tissue Mast Cells

Undoubtedly, mast cells take part in host defense against microorganisms as they are numerous at the portal of infection, they release many proinflammatory and antimicrobial mediators, and they express pattern recognition receptors, such as TLRs. These receptors play a key role in recognition and binding molecules associated with microorganisms and molecules associated with damage. Cathelicidins exhibit direct antimicrobial activities against a broad spectrum of microbes by perturbing their cell membranes. Accumulating evidence suggests a role for these molecules in supporting cell activation. We examined the impact of human cathelicidin LL-37 on tissue mast cell TLR expression and distribution. Depending on context, we show that LL-37 stimulation resulted in minor to major effects on TLR2, TLR3, TLR4, TLR5, TLR7, and TLR9 expression. Confocal microscopy analysis showed that, upon stimulation, TLRs may translocate from the cell interior to the surface and conversely. FPR2 and EGFR inhibitors reduced the increase in expression of selected receptors. We also established that LL-37 acts as a powerful inducer of CCL3 and ROS generation. These results showed that in response to LL-37, mast cells enhance the capability to detect invading pathogens by modulation of TLR expression in what may be involved FPR2 or EGFR molecules.

The host defense peptide LL-37 is detected in human parotid and submandibular/sublingual saliva and expressed in glandular neutrophils

The human host defense peptide, LL-37, is an important player in the first line of defense against invading microorganisms. LL-37 and its precursor, hCAP18, have been detected in unstimulated whole saliva but no reports showing hCAP18/LL-37 in isolated, parotid, and/or submandibular/sublingual saliva have been presented. Here, we measured the levels of hCAP18/LL-37 in human parotid and submandibular/sublingual saliva and investigated the expression of hCAP18/LL-37 in parotid and submandibular gland tissue. Parotid and submandibular/sublingual saliva was collected from healthy volunteers, and the levels of hCAP18/LL-37 in saliva were analyzed by dot blot, ELISA, and western blotting. Cellular expression of hCAP18/LL-37 in human parotid and submandibular glands was investigated by immunohistochemistry. Immunoreactivity for hCAP18/LL-37 was detected in both parotid and submandibular/sublingual saliva of all individuals. The concentration of hCAP18/LL-37 was similar in parotid and submandibular/sublingual saliva, and was determined by densitometric scanning of each dot and normalization to the total protein concentration of each sample, and by ELISA. Double immunohistochemistry revealed that intravascular neutrophils of both parotid and submandibular glands express hCAP18/LL-37. For the first time, we demonstrate hCAP18/LL-37 in isolated human parotid and submandibular/sublingual saliva and expression of hCAP18/LL-37 in glandular intravascular neutrophils, indicating that neutrophils of the major salivary glands contribute to the LL-37 content of whole saliva.

Significance and Diagnostic Role of Antimicrobial Cathelicidins (LL-37) Peptides in Oral Health

Cathelicidins are a group of oral antimicrobial peptides that play multiple vital roles in the human body, such as their antimicrobial (broad spectrum) role against oral microbes, wound healing, and angiogenesis, with recent evidences about their role in cancer regulation. Cathelicidins are present in humans and other mammals as well. By complex interactions with the microenvironment, it results in pro-inflammatory effects. Many in vitro and in vivo experiments have been conducted to ultimately conclude that these unique peptides play an essential role in innate immunity. Peptides are released in the precursor form (defensins), which after cleavage results in cathelicidins formation. Living in the era where the major focus is on non-invasive and nanotechnology, this ultimately leads to further advancements in the field of salivaomics. Based on current spotlight innovations, we have highlighted the biochemistry, mode of action, and the importance of cathelicidins in the oral cavity.

Serum levels of peptide cathelicidin LL-37 in elderly patients with depression

Cathelicidin LL-37 is a small cationic that plays an important role in antimicrobial defense, as it kills a broad spectrum of infectious agents by disrupting their membranes, including gram-positive and gram-negative bacteria, some viruses and fungi; and it neutralizes activity of bacterial endotoxins. Moreover, cathelicidin LL-37 exerts proinflammatory effect, while numerous reports indicate the role of inflammation in the development of depression. The purpose of this study was to evaluate the circulating levels of cathelicidin LL-37 in elderly depressed patients. Thirty-nine elderly (age ≥ 60 years) women with major depressive disorder and thirty-eight non-depressed elderly (age ≥ 60 years) women were included into the study. The mean serum cathelicidin LL-37 concentration in patients with depression and in healthy subjects were 2.40 ± 3.00ng/mL and 1.17 ± 3.04ng/mL, respectively, and the difference was statistically significant. No significant differences between mean serum CRP level and WBC count in MDD patients and control group were documented. There were no correlations between LL-37 level and age, BMI, GDS score, CRP level or WBC count. It can be assumed that elevated serum LL-37 levels in depressed patients may reflect inflammatory activation associated with depression.

Endogenous antimicrobial factors in the treatment of infectious diseases

Nowadays, a number of antibiotic-resistant bacteria strains is increasing. It is a serious clinical problem and poses a threat to the effectiveness of conventional antibiotic therapy. Thus, scientists are constantly seeking new alternatives for treatment of infectious diseases. There are some natural endogenous factors, which possess antimicrobial activities against a large number of microorganisms, including both Gram-positive and Gram-negative bacteria, viruses and fungi. These factors are present in all eukaryotic organisms and constitute an essential element of their immune system. A large number of in vitro and in vivo models have been used to show the activity of antimicrobial factors, and only few studies have been conducted on people. Results indicate that administration of these molecules is therapeutically beneficial. This review summarizes knowledge of selected endogenous antimicrobial agents, such as cathelicidins, defensins, histatins, lysozyme and lactoferrin. We also discuss potential uses of these factors in the treatment of infectious diseases.

The Oral Microbiome of Denture Wearers Is Influenced by Levels of Natural Dentition

Objectives

The composition of dental plaque has been well defined, whereas currently there is limited understanding of the composition of denture plaque and how it directly influences denture related stomatitis (DS). The aims of this study were to compare the microbiomes of denture wearers, and to understand the implications of these towards inter-kingdom and host-pathogen interactions within the oral cavity.

Methods

Swab samples were obtained from 123 participants wearing either a complete or partial denture; the bacterial composition of each sample was determined using bar-coded illumina MiSeq sequencing of the bacterial hypervariable V4 region of 16S rDNA. Sequencing data processing was undertaken using QIIME, clustered in Operational Taxonomic Units (OTUs) and assigned to taxonomy. The dentures were sonicated to remove the microbial flora residing on the prosthesis, sonicate was then cultured using diagnostic colorex Candida media. Samples of unstimulated saliva were obtained and antimicrobial peptides (AMP) levels were measured by ELISA.

Results

We have shown that dental and denture plaques are significantly distinct both in composition and diversity and that the oral microbiome composition of a denture wearer is variable and is influenced by the location within the mouth. Dentures and mucosa were predominantly made up of Bacilli and Actinobacteria. Moreover, the presence of natural teeth has a significant impact on the overall microbial composition, when compared to the fully edentulous. Furthermore, increasing levels of Candida spp. positively correlate with Lactobacillus spp. AMPs were quantified, though showed no specific correlations.

Conclusions

This is the first study to provide a detailed understanding of the oral microbiome of denture wearers and has provided evidence that DS development is more complex than simply a candidal infection. Both fungal and bacterial kingdoms clearly play a role in defining the progression of DS, though we were unable to show a defined role for AMPs.

Cathelicidin impact on inflammatory cells

Cathelicidins, like other antimicrobial peptides, exhibit direct antimicrobial activities against a broad spectrum of microbes, including both Gram-positive and Gram-negative bacteria, enveloped viruses, and fungi. These host-derived peptides kill the invaded pathogens by perturbing their cell membranes and can neutralize biological activities of endotoxin. Nowadays, more and more data indicate that these peptides, in addition to their antimicrobial properties, possess various immunomodulatory activities. Cathelicidins have the potential to influence and modulate, both directly and indirectly, the activity of various cell populations involved in inflammatory processes and in host defense against invading pathogens. They induce migration of neutrophils, monocytes/macrophages, eosinophils, and mast cells and prolong the lifespan of neutrophils. These peptides directly activate inflammatory cells to production and release of different pro-inflammatory and immunoregulatory mediators, cytokines, and chemokines, however cathelicidins might mediate the generation of anti-inflammatory cytokines as well. Cathelicidins also modulate epithelial cell/keratinocyte responses to infecting pathogens. What is more, they affect activity of monocytes, dendritic cells, keratinocytes, or epithelial cells acting in synergy with cytokines or β-defensins. In addition, these peptides indirectly balance TLR-mediated responses of monocytes, macrophages, dendritic cells, epithelial cells, and keratinocytes. This review discusses the role and significance of cathelicidins in inflammation and innate immunity against pathogens.

Human-derived cathelicidin LL-37 directly activates mast cells to proinflammatory mediator synthesis and migratory response

Cathelicidins, a family of antimicrobial peptides, are well known for their role in host defense, particularly against bacteria. Apart from direct killing of microbes through the membrane disruption, cathelicidins can also exert immunomodulatory effects on cells involved in inflammatory processes. Considering the important role of mast cells in inflammation, the aim of this study was to determine whether LL-37, human-derived cathelicidin, can induce mast cell activation. We have observed that LL-37 directly stimulates mast cell to degranulation and production of some proinflammatory cytokines, but fails to induce cysteinyl leukotriene generation and release. We have also documented that LL-37 acts as a strong mast cell chemoattractant. In intracellular signaling in mast cells activated by LL-37 participates PLC/A2 and, in part, MAPKs, and PI3K. In conclusion, our results indicate that cathelicidins may enhance antibacterial inflammatory response via attracting mast cell to pathogen entry site and via induction of mast cell-derived mediator release.

Salivary concentration of the antimicrobial peptide LL-37 in patients with oral lichen planus

Background

The antimicrobial peptide LL-37 is a significant molecule of innate immunity and recent studies indicate that it plays an important role in maintaining oral health. Yet limited knowledge exists on its role in oral diseases and oral lichen planus (OLP) in particular.

Objective

The study aimed to examine: 1) the salivary concentration of LL-37 in patients with OLP and healthy subjects, 2) the relation between the type (reticular or erosive) and size of OLP lesions and LL-37 concentration, and 3) the effect of the therapeutic modalities on LL-37 levels.

Design

The salivary peptide concentration in samples from 20 patients and 30 healthy subjects at the same age range was determined by ELISA.

Results

Despite the wide variation in peptide concentration found in both groups, the healthy subjects exhibited significantly lower levels than patients. Patients with the erosive form had significantly higher peptide concentrations than patients with the reticular form. Systemic treatment with corticosteroids resulted in a significant decrease of the salivary peptide concentration, while other treatment modalities, such as administration of vitamins A and E or local application of corticosteroids had no effect. Improved clinical appearance of the lesions was followed by a decrease in the salivary LL-37 level.

Conclusions

Salivary concentration of LL-37 correlates to the manifestation of mucosa lesions in OLP patients, the highest levels being observed in the most severe cases. This increase in peptide levels may protect against lesion infection and promote a quick wound healing.