Human ß-defensins: The multi-functional natural peptide.

The increasing threat of antibiotic resistance among pathogenic microorganisms and the urgent demand for new antibiotics require immediate attention. Antimicrobial peptides exhibit effectiveness against microorganisms, fungi, viruses, and protozoa. The discovery of human ß-defensins represents a major milestone in biomedical research, opening new avenues for scientific investigation into the innate immune system and its resistance mechanisms against pathogenic microorganisms. Multiple defensins present a promising alternative in the context of antibiotic abuse. However, obstacles to the practical application of defensins as anti-infective therapies persist due to the unique properties of human ß-defensins themselves and serious pharmacological and technical challenges. To overcome these challenges, diverse delivery vehicles have been developed and progressively improved for the conjugation or encapsulation of human ß-defensins. This review briefly introduces the biology of human ß-defensins, focusing on their multistage structure and diverse functions. It also discusses several heterologous systems for producing human ß-defensins, various delivery systems created for these peptides, and patent applications related to their utilization, concluding with a summary of current challenges and potential solutions.

Dynamic changes of Th1/Th2/Th17 cytokines and hBD-2/3 in erosive oral lichen planus patients saliva before and after prednisone acetate treatment.

Objective: This study aimed to investigate the expression of T helper 1 (Th1)/Th2/Th17- related cytokines and human beta defensins 2 and 3 (hBD-2 and -3) in the saliva of patients with erosive oral lichen planus (EOLP) and to explore their role in the pathogenesis of EOLP and the effects of glucocorticoids on EOLP. Methods: A total of 30 patients with EOLP and 20 age- and sex-matched healthy individuals were included in this study. The patients were treated with prednisone at a dose of 0.4 mg/(kg·d) for 1 week and examined before and after treatment. Unstimulated whole saliva samples were collected to determine the levels of cytokines (interleukin 1 beta [IL-1ß], tumour necrosis factor alpha [TNF]-α, interferon gamma [IFN-γ], IL-4, IL-6, IL-10 and IL-17) by cytometric bead array and those of hBD-2 and -3 b y enzyme-linked immunosorbent assay. In addition, oral rinse samples were collected to detect Candida load. Results: The levels of salivary IL-1ß, IL-6, hBD-2 and hBD-3 were higher and the IFN-γ/IL-4 and IL-1ß/IL-6 ratios were lower in patients with EOLP than in healthy individuals. In patients with EOLP, hBD-2 levels were positively correlated with IFN-γ levels and negatively correlated with IL-17 levels, whereas hBD-3 levels were negatively correlated with IL-17 and IL-10 levels. In addition, the prevalence of EOLP was positively correlated with IL-6 levels and negatively correlated with the IFN-γ/IL-4 ratio. The levels of IL-1ß, TNF-α, IFN-γ, IL-6, hBD-2 and hBD-3 and the IFN-γ/IL-4 ratio decreased after treatment with prednisone for 1 week. The levels of IL-6, hBD-2 and hBD-3 were significantly higher in EOLP patients than in healthy individuals; while TNF-α levels and the IFN-γ/IL-4 ratio were significantly lower in EOLP patients than in healthy individuals. Furthermore, the oral counts of Candida spp. (colony forming unit [CFU]) were negatively correlated with TNF-α levels. Numerical Rating Scale(NRS) and Sign scores decreased in EOLP patients after treatment. Approximately 80 % of patients were effectively treated. Salivary TNF-α levels were significantly higher in the treatment-ineffective group than in the treatment-effective group before treatment with prednisone, and differences in salivary IL-6 levels before and after treatment were significantly higher in the treatment-effective group than in the treatment-ineffective group. Conclusions: High expression of IL-1ß, IL-6, hBD-2 and Th1/Th2 imbalance in saliva may be associated with the pathogenesis of EOLP. IFN-γ/IL-4 balance may serve as a protective factor for EOLP. Glucocorticoids significantly alleviate the symptoms of EOLP and inhibit the expression of Th1/Th2 cytokines.

Human ß-Defensin 3 Inhibits Porphyromonas Gingivalis Lipopolysaccharide-Induced Oxidative and Inflammatory Responses of Microglia by Suppression of Cathepsins B and L.

Recently, the effects of antibacterial peptides are suggested to have therapeutic potential in Alzheimer's disease. Furthermore, systemic treatment of Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) induced Alzheimer's disease-like neuropathological changes in middle-aged mice. Then, we examined whether human ß-defensins (hBDs), antimicrobial peptides produced by the oral mucosa and salivary glands, can suppress Pg LPS-induced oxidative and inflammatory responses by microglia. hBD3 (1 µM) significantly suppressed Pg LPS-induced production of nitric oxide and interleukin-6 (IL-6) by MG6 cells, a mouse microglial cell line. hBD3 (1 µM) also significantly inhibited Pg LPS-induced expression of IL-6 by HMC3 cells, a human microglial cell line. In contrast, neither hBD1, hBD2 nor hBD4 failed to inhibit their productions. Furthermore, hBD3 suppressed Pg LPS-induced p65 nuclear translocation through the IκBα degradation. Pg LPS-induced expression of IL-6 was significantly suppressed by E64d, a cysteine protease inhibitor, and CA-074Me, a known specific inhibitor for cathepsin B, but not by pepstatin A, an aspartic protease inhibitor. Interestingly, hBD3 significantly inhibited enzymatic activities of recombinant human cathepsins B and L, lysosomal cysteine proteases, and their intracellular activities in MG6 cells. Therefore, hBD3 suppressed oxidative and inflammatory responses of microglia through the inhibition of cathepsins B and L, which enzymatic activities are necessary for the NF-κB activation.

Case Report: A Case of Hereditary Gingival Fibromatosis With a High Level of Human ß Defensins in Gingival Epithelium.

Hereditary gingival fibromatosis [HGF, (MIM 135300)], a rare benign oral condition, has several adverse consequences such as aesthetic changes, malocclusion, speech impediments, and abnormal dentition. However, relatively few studies have addressed the beneficial effects of thick gingival tissues in resisting external stimuli. In this report, we present a unique case of a family affected by HGF that manifests as a 'healthy' gingiva. Human ß-defensins (hBDs) are known to play a pivotal role in the clearance and killing of various microbes, and contribute to maintaining a healthy oral environment, which is currently emerging research area. However, the expression pattern and localisation of hBDs in patients with HGF have not yet been reported. hBD-2 and hBD-3 in the pedigree we collected had relatively elevated expression. High hBD levels in the gingival tissue of patients from the family may be beneficial in protecting oral tissue from external stimuli and promoting periodontal regeneration, but their role and the mechanisms underlying HGF need to be clarified.

Antimicrobial activity and structure of a consensus human ß-defensin and its comparison to a novel putative hBD10.

The spread of multidrug resistant bacteria owing to the intensive use of antibiotics is challenging current antibiotic therapies, and making the discovery and evaluation of new antimicrobial agents a high priority. The evaluation of novel peptide sequences of predicted antimicrobial peptides from different sources is valuable approach to identify alternative antibiotic leads. Two strategies were pursued in this study to evaluate novel antimicrobial peptides from the human ß-defensin family (hBD). In the first, a 32-residue peptide was designed based on the alignment of all available hBD primary structures, while in the second a putative 35-residue peptide, hBD10, was mined from the gene DEFB110. Both hBDconsensus and hBD10 were chemically synthesized, folded and purified. They showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Mycobacterium tuberculosis, but were not hemolytic on human red blood cells. The NMR-based solution structure of hBDconsensus revealed that it adopts a classical ß-defensin fold and disulfide connectivities. Even though the mass spectrum of hBD10 confirmed the formation of three disulfide bonds, it showed limited dispersion in 1 H NMR spectra and structural studies were not pursued. The evaluation of different ß-defensin structures may identify new antimicrobial agents effective against multidrug-resistant bacterial strains.

Bacterial Virus Lambda Gpd-Fusions to Cathelicidins, α- and ß-Defensins, and Disease-Specific Epitopes Evaluated for Antimicrobial Toxicity and Ability to Support Phage Display.

We showed that antimicrobial polypeptides, when translated as gene fusions to the bacteriophage lambda capsid decoration protein gpD, formed highly toxic molecules within E. coli, suggesting that they can retain their antimicrobial activity conformation when fused to gpD. These include gpD-fusions to human and porcine cathelicidins LL37 and PR39, ß-defensins HBD3 and DEFB126-Δ (deleted for its many COOH-terminal glycosylation sites), and α-defensin HD5. Antimicrobial toxicity was only observed when the peptides were displayed from the COOH-terminal, and not the NH2-terminal end, of gpD. This suggests that COOH-terminal displayed polypeptides of gpD-fusions can more readily form an active-state conformation than when they are displayed from the NH2-terminal end of gpD. The high toxicity of the COOH-displayed gpD-defensins suggests either that the fused defensin peptides can be oxidized, forming three correct intramolecular disulfide bonds within the cytosol of bacterial cells, or that the versions without disulfide bonds are highly toxigenic. We showed the high efficiency of displaying single epitope 17 amino-acid fusions to gpD on LDP (lambda display particles), even when the gpD-fusion protein was toxic. The efficient formation of high display density LDP, displaying a single disease specific epitope (DSE), suggests the utility of LDP-DSE constructs for use as single epitope vaccines (SEV).

DEFB1 rs11362 Polymorphism and Risk of Chronic Periodontitis: A Meta-Analysis of Unadjusted and Adjusted Data.

Objective: Chronic periodontitis (CP) is a growing problem that affects the worldwide population, having significant impacts on people's daily lives and economic development. Genetics is an important component in the determination of individual susceptibility to periodontal diseases. Numerous studies have been performed to investigate the association between beta defensin 1 (DEFB1) rs11362 polymorphism and risk of CP, but the results are still inconclusive. Therefore, we conducted this meta-analysis to ascertain whether this variation in DEFB1 is associated with CP susceptibility. Methods: The relevant studies were searched in PubMed and Chinese National Knowledge Infrastructure (CNKI) databases up to January 9, 2018. Two independent authors selected citations and extracted the data from eligible studies. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were used to assess the strength of the association. Results: Seven case-control studies were included in this meta-analysis. Based on unadjusted data, there was no obvious association between DEFB1 rs11362 polymorphism and CP risk in all genetic models (A vs. G: OR = 0.86, 95%CI = 0.61-1.20; AA vs. GG: OR = 0.83, 95% CI = 00.50-1.39; AG vs. GG: OR = 1.01, 95%CI = 0.73-1.39; AG+AA vs. GG: OR = 0.91, 95% CI = 00.74-1.11; and AA vs. AG+GG: OR = 0.83, 95% CI = 00.57-1.21); the results of adjusted data also showed no significant relationship. Subgroup analyses based on ethnicity, participants' smoking status, HWE in controls and severity of CP all revealed similar results to that of the overall analysis. Sensitivity analysis indicated the results were robust and no evidence of publication bias was found. Conclusions: Our meta-analysis suggests that DEFB1 rs11362 polymorphism may not have an important effect on the risk of CP. Further large-scale and well-designed studies are necessary to validate our conclusion in the future.

Comment on "Effect of biofilm formation by clinical isolates of Helicobacter pylori on the efflux-mediated resistance to commonly used antibiotics".

Attaran et al[1] have recently shown that decreased susceptibility of established Helicobacter pylori (H. pylori) biofilms to specific antibiotics, was associated with the overtly enhanced transcription of two efflux pump genes, hp1165 and hefA, involved in specific resistance to tetracycline and multiple antibiotics, respectively. Apart from antibiotic exposure, secretion of multiple antimicrobial peptides, such as human ß-defensins (hßDs), by the gastric epithelium upon Hp challenge, may act as early triggering events that positively impact biofilm formation and thus, antibiotic resistance. In this regard, we undertook genomic transcriptional studies using Hp 26695 strain following exposure to sublethal, similar to those present in the gastric niche, concentrations of hßDs in an attempt to provide preliminary data regarding possible mechanisms of immune evasion and selective sensitivity of Hp. Our preliminary results indicate that hßD exposure ignites a rapid response that is largely due to the activation of several, possibly interconnected transcriptional regulatory networks - origons - that ultimately coordinate cellular processes needed to maintain homeostasis and successful adaptation of the bacterium in the gastric environment. In addition, we have shown that both antibiotic and hßD resistance are mediated by dedicated periplasmic transporters, including the aforementioned efflux pump genes hp1165 and hefA, involved in active export of antibiotics from the cell membrane and/or, as recently suggested, substrate sensing and signalling. Furthermore, it appears that sublethal doses of hßDs may enhance biofilm formation by the sustained expression of, mainly, quorum sensing-related genes. In conclusion, we provide additional data regarding the role of specific innate immune molecules in antibiotic cross-resistance mechanisms that may deepen our understanding in the context of the development of novel eradication regimens.

Current insights into the role of human ß-defensins in atopic dermatitis.

Anti-microbial peptides or host defence peptides are small molecules that display both anti-microbial activities and complex immunomodulatory functions to protect against various diseases. Among these peptides, the human ß-defensins (hBDs) are localized primarily in epithelial surfaces, including those of the skin, where they contribute to protective barriers. In atopic dermatitis skin lesions, altered skin barrier and immune dysregulation are believed to be responsible for reduced hBD synthesis. Impaired hBD expression in the skin is reportedly the leading cause of increased susceptibility to bacterial and viral infection in patients with atopic dermatitis. Although hBDs have considerable beneficial effects as anti-microbial agents and immunomodulators and may ameliorate atopic dermatitis clinically, recent evidence has also suggested the negative effects of hBDs in atopic dermatitis development. In the current review, we provide an overview of the regulation of hBDs and their role in the pathogenesis of atopic dermatitis. The efforts to utilize these molecules in clinical applications are also described.

Genetic Polymorphisms in DEFB1 and miRNA202 Are Involved in Salivary Human ß-Defensin 1 Levels and Caries Experience in Children.

The antimicrobial peptides human ß-defensins (hBDs) are encoded by ß-defensin genes (DEFBs) and are possibly involved in caries susceptibility. In this study we aimed (1) to investigate the relationship between salivary hBDs and caries and (2) to evaluate the association of genetic polymorphisms in DEFB1 and microRNA202 (miRNA202) with salivary levels of hBDs and caries experience. Two data sets were available for this study, totalizing 678 Brazilian children. Dental examination and saliva collection were performed in all included children. The salivary level for hDB1, hBD2, and hBD4 was assessed by ELISA sandwich technique in 168 children. The DNA was extracted from saliva, and polymorphisms in DEFB1 and miRNA202 were analyzed by real-time PCR. Statistical analysis was performed to investigate the associations between caries experience, hBD salivary level, genotype, and allele distribution, with an alpha of 0.05. The hBD1 level was significantly higher in caries-free children (p < 0.0001). The miRNA202 was associated with a lower level of salivary hBD1 (p < 0.05). Also, the polymorphic distribution of miRNA202 was associated with caries (p = 0.006). The polymorphisms in DEFB1 were not associated with hBD salivary level and caries experience (p > 0.05). In conclusion, our results indicate that genetic polymorphism in miRNA202 is involved in hBD1 salivary level as well as caries experience in children.

Decidualization Mediated by Steroid Hormones Modulates the Innate Immunity in Response to Group B Streptococcal Infection in vitro.

BACKGROUND: Decidual cells play a role in the modulation of the innate immune response to protect pregnancy against infection. Steroid hormones regulate the innate immune response in different tissues, and they are involved in several biological processes like decidualization. The aim of this study was to assess if steroid hormones modulate the innate immunity in endometrial stromal cells (ESCs) and decidual stromal cells (DSCs) in response to group B streptococcus (GBS) infection in vitro. METHODS: Primary cultures of ESC were differentiated into DSC using 36 nM estradiol + 300 nM progesterone, and both were infected with GBS overnight. Concentrations of pro- and anti-inflammatory mediators (interleukin [IL]-1ß, IL-6, tumor necrosis factor [TNF]-α, IL-10, and TGF-ß), chemokines (IL-8 and GCP-2), and human ß-defensins (HBD-1, HBD-2, and HBD-3) were measured in the culture supernatants. RESULTS: DSCs showed a significant increase in IL-6 (p < 0.05), TNF-α (p < 0.05), IL-10 (p < 0.01), and TGF-ß (p < 0.05) secretion after GBS infection, while these changes were not observed in infected ESCs. IL-8 and GCP-2 increased after GBS infection, regardless of decidualization. ß-Defensins 1-3 decreased (p < 0.05) in ESCs after GBS infection, and hormone decidualization preserved the secretion of these antimicrobial peptides. CONCLUSIONS: Decidualization mediated by steroid hormones balance the pro- and anti-inflammatory response at the maternal-fetal interface under infection conditions.

Human papillomavirus oncogenic E6 protein regulates human ß-defensin 3 (hBD3) expression via the tumor suppressor protein p53.

Human ß-defensin-3 (hBD3) is an epithelial cell-derived innate immune regulatory molecule overexpressed in oral dysplastic lesions and fosters a tumor-promoting microenvironment. Expression of hBD3 is induced by the epidermal growth factor receptor signaling pathway. Here we describe a novel pathway through which the high-risk human papillomavirus type-16 (HPV-16) oncoprotein E6 induces hBD3 expression in mucosal keratinocytes. Ablation of E6 by siRNA induces the tumor suppressor p53 and diminishes hBD3 in HPV-16 positive CaSki cervical cancer cells and UM-SCC-104 head and neck cancer cells. Malignant cells in HPV-16-associated oropharyngeal cancer overexpress hBD3. HPV-16 E6 induces hBD3 mRNA expression, peptide production and gene promoter activity in mucosal keratinocytes. Reduction of cellular levels of p53 stimulates hBD3 expression, while activation of p53 by doxorubicin inhibits its expression in primary oral keratinocytes and CaSki cells, suggesting that p53 represses hBD3 expression. A p53 binding site in the hBD3 gene promoter has been identified by using electrophoretic mobility shift assays and chromatin immunoprecipitation (ChIP). In addition, the p63 protein isoform ΔNp63α, but not TAp63, stimulated transactivation of the hBD3 gene and was co-expressed with hBD3 in head and neck cancer specimens. Therefore, high-risk HPV E6 oncoproteins may stimulate hBD3 expression in tumor cells to facilitate tumorigenesis of HPV-associated head and neck cancer.

Epidermal growth factor receptor inhibitors selectively inhibit the expressions of human ß-defensins induced by Staphylococcus epidermidis.

BACKGROUND: Epidermal growth factor receptor inhibitors (EGFRIs) have developed as one of the potential treatment options for various kinds of cancers. Although a variety of dermatological adverse reactions such as follicular acneiform eruptions is commonly encountered, the mechanism of the reactions remains unclear. OBJECTIVES: We investigated the effects of EGFRIs on the expression of human ß-defensins against staphylococci to study the pathomechanism of cutaneous adverse reactions caused by EGFRIs. METHODS: We investigated the expressions of human ß-defensins 1, 2, and 3 (hBD1, 2, and 3) from staphylococci-stimulated normal human epidermal keratinocytes (NHEKs) cultured with or without the effects of two EGFRIs, gefitinib and erlotinib. We stimulated NHEKs with the supernatant of Staphylococcus aureus (S. aureus) and S. epidermidis and the live staphylococci. We measured hBDs in the culture supernatants of NHEKs by enzyme-linked immunosorbent assay (ELISA). RESULTS: EGFRIs did not suppress the expressions of hBD1 and 3 induced by S. aureus. In contrast, EGFRIs suppressed the expressions of hBD2 and 3 induced by S. epidermidis. CONCLUSION: EGFRIs may cause cutaneous adverse effects through selectively perturbing innate immune responses induced by commensal and pathogenic bacteria.

The expression of hBDs in the gingival tissue and keratinocytes from healthy subjects and periodontitis patients.

OBJECTIVE: Although the secretion of antimicrobial peptides in gingival tissue and isolated cells has been reported, the induction of human ß-defensins (hBDs) in epithelial cells from the periodontitis patients was not stated before. This study aimed to compare the secretion of hBDs in gingival epithelial cells from periodontitis patients and healthy controls. DESIGN: Firstly, gingival biopsies were obtained from chronic periodontitis patients and healthy controls and the hBDs expression level in gingival tissues was quantified. Then the epithelial cells from periodontitis patients and healthy controls were isolated and challenged with different concentrations of tumour necrosis factor-alpha (TNFα). The hBDs expression level was also quantified after induction. At last, to identify the molecular pathways involved in hBDs induction, the isolated cells were incubated with NF-kB or MAPK inhibitor before TNFα induction. RESULTS: Higher hBDs expression was found in gingival tissues from healthy controls. The in vitro experiments demonstrated that the hBD-2 expression in gingival epithelial cells from periodontitis patients can be induced by TNFα at lower dose, while the optimum expression level was much lower. The basal hBD-3 mRNA expression was much higher in cells from periodontitis patients. The molecular pathways involved in the responses to the inflammatory cytokine in patients and healthy controls were the same. CONCLUSIONS: The epithelial cells from periodontitis patients are more prone to recognize and respond to TNFα to produce hBD-2. The basal expression of hBD-3 in keratinocytes from periodontitis patients suggested that hBD-3 may play an important role in the immunological reaction against periodontitis.