Human Beta Defensins and Cancer: Contradictions and Common Ground

Human β-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 β-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 β-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 β-defensins. This review briefly introduces the biology of human β-defensins, focusing on their multistage structure and diverse functions. It also discusses several heterologous systems for producing human β-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.

Materials derived from the human elastin-like polypeptide fusion with an antimicrobial peptide strongly promote cell adhesion

Protein and peptide materials have attracted great interest in recent years, especially for biological applications, in light of their possibility to easily encode bioactivity whilst maintaining cytocompatibility and biodegradability. Heterologous recombinant expression to produce antimicrobial peptides is increasingly considered a convenient alternative for the transition from conventional methods to more sustainable production systems. The human elastin-like polypeptide (HELP) has proven to be a valuable fusion carrier, and due to its cutting-edge properties, biomimetic materials with antimicrobial capacity have been successfully developed. In this work, we have taken advantage of this platform to produce a difficult-to-synthesise sequence as that of the human β-defensin 1 (hBD1), an amphipathic cationic peptide with structural folding constraints relevant to its bioactivity. In the design of the gene, highly specific endoproteinases recognition sites were introduced to release the active forms of hBD1. After the expression and purification of the new fusion construct, its biological activity was evaluated. It was found that both the fusion biopolymer and the released active forms can inhibit the growth of Escherichia coli in redox environments. Remarkably, 2D and 3D materials derived from the biopolymer showed a strong cell adhesion-promoting activity. These results suggest that HELP represents a multitasking platform that not only facilitates the production of bioactive domains and derived materials but could also pave the way for the development of new approaches to study biological interactions at the molecular level.

Human β-defensin-1 activates autophagy in human colon cancer cells via regulation of long non-coding RNA TCONS_00014506

Macroautophagy (hereafter referred to as autophagy) is a prosurvival mechanism for the clearance of damaged cellular components, specifically related to exposure to various stressors such as starvation, excessive ethanol intake, and chemotherapy. This editorial reviews and comments on an article by Zhao et al, to be published in World J Gastrointestinal Oncology in 2024. Based on various molecular biology methodologies, they found that human β-defensin-1 reduced the proliferation of colon cancer cells, which was associated with the inhibition of the mammalian target of rapamycin, resulting in autophagy activation. The activation of autophagy is evidenced by increased levels of Beclin1 and LC3II/I proteins and mediated by the upregulation of long non-coding RNA TCONS_00014506. Our study discusses the impact of autophagy activation and mechanisms of autophagy, including autophagic flux, on cancer cells. Additionally, we emphasize the importance of describing the detailed methods for isolating long noncoding RNAs TCONS_00014506. Our review will benefit the scientific community and improve the overall clarity of the paper.

Integrating In Silico and In Vitro Approaches to Identify Natural Peptides with Selective Cytotoxicity against Cancer Cells

Anticancer peptides (ACPs) are bioactive compounds known for their selective cytotoxicity against tumor cells via various mechanisms. Recent studies have demonstrated that in silico machine learning methods are effective in predicting peptides with anticancer activity. In this study, we collected and analyzed over a thousand experimentally verified ACPs, specifically targeting peptides derived from natural sources. We developed a precise prediction model based on their sequence and structural features, and the model's evaluation results suggest its strong predictive ability for anticancer activity. To enhance reliability, we integrated the results of this model with those from other available methods. In total, we identified 176 potential ACPs, some of which were synthesized and further evaluated using the MTT colorimetric assay. All of these putative ACPs exhibited significant anticancer effects and selective cytotoxicity against specific tumor cells. In summary, we present a strategy for identifying and characterizing natural peptides with selective cytotoxicity against cancer cells, which could serve as novel therapeutic agents. Our prediction model can effectively screen new molecules for potential anticancer activity, and the results from in vitro experiments provide compelling evidence of the candidates' anticancer effects and selective cytotoxicity.

Human β-defensins and their synthetic analogs: Natural defenders and prospective new drugs of oral health

As a family of cationic host defense peptides, human β-defensins (HBDs) are ubiquitous in the oral cavity and are mainly synthesized primarily by epithelial cells, serving as the primary barrier and aiming to prevent microbial invasion, inflammation, and disease while maintaining physiological homeostasis. In recent decades, there has been great interest in their biological functions, structure-activity relationships, mechanisms of action, and therapeutic potential in oral diseases. Meanwhile, researchers are dedicated to improving the properties of HBDs for clinical application. In this review, we first describe the classification, structural characteristics, functions, and mechanisms of HBDs. Next, we cover the role of HBDs and their synthetic analogs in oral diseases, including dental caries and pulp infections, periodontitis, peri-implantitis, fungal/viral infections and oral mucosal diseases, and oral squamous cell carcinoma. Finally, we discuss the limitations and challenges of clinical translation of HBDs and their synthetic analogs, including, but not limited to, stability, bioavailability, antimicrobial activity, resistance, and toxicity. Above all, this review summarizes the biological functions, mechanisms of action, and therapeutic potential of both natural HBDs and their synthetic analogs in oral diseases, as well as the challenges associated with clinical translation, thus providing substantial insights into the laboratory development and clinical application of HBDs in oral diseases.

Change in Tissue Microbiome and Related Human Beta Defensin Levels Induced by Antibiotic Use in Bladder Carcinoma

It is now generally accepted that the success of antitumor therapy can be impaired by concurrent antibiotic therapy, the presence of certain bacteria, and elevated defensin levels around the tumor tissue. The aim of our current investigation was to identify the underlying changes in microbiome and defensin levels in the tumor tissue induced by different antibiotics, as well as the duration of this modification. The microbiome of the tumor tissues was significantly different from that of healthy volunteers. Comparing only the tumor samples, no significant difference was confirmed between the untreated group and the group treated with antibiotics more than 3 months earlier. However, antibiotic treatment within 3 months of analysis resulted in a significantly modified microbiome composition. Irrespective of whether Fosfomycin, Fluoroquinolone or Beta-lactam treatment was used, the abundance of Bacteroides decreased, and Staphylococcus abundance increased. Large amounts of the genus Acinetobacter were observed in the Fluoroquinolone-treated group. Regardless of the antibiotic treatment, hBD1 expression of the tumor cells consistently doubled. The increase in hBD2 and hBD3 expression was the highest in the Beta-lactam treated group. Apparently, antibiotic treatment within 3 months of sample analysis induced microbiome changes and defensin expression levels, depending on the identity of the applied antibiotic.

Human beta defensin 3 knockdown inhibits the proliferation and migration of airway smooth muscle cells through regulating the PI3K/AKT signaling pathway

Asthma, a common pediatric pulmonary disease, significantly affects children's healthy development. This study aimed to investigate the functions of human β defensin-3 (HBD-3) in asthma progression. For this purpose, blood samples from asthmatic and healthy children were collected. Moreover, the airway smooth muscle cells (ASMCs) were treated with platelet-derived growth factor BB (PDGF-BB) to develop an in vitro asthma model, then evaluated cell viability and migration via CCK-8 and transwell assays. The mRNA levels of interferon γ (INF-γ), interleukin 4 (IL-4), interleukin 10 (IL-10), alpha-smooth muscle actin (α-SMA), HBD-3, and the protein levels of phosphatidylinositol 3-kinase (PI3K) along with protein kinase B (AKT) were detected. Similarly, the N6-methyladenosine (m6A) content in the ASMCs and m6A levels of HBD-3 were also measured. Results indicated an upregulated HBD-3 in the asthmatic children. The ASMCs were found to be stimulated by PDGF-BB, in addition to the promotion of cell viability and migration. The INF-γ, IL-4, and α-SMA levels were reduced, while IL-10 was elevated in PDGF-BB-stimulated ASMCs. Silencing HBD-3 in PDGF-BB stimulated ASMCs was found to exert the opposite effect by inhibiting cell viability and migration, enhancing the levels of INF-γ, IL-4, and α-SMA, while the IL-10 levels were found to decline. PDGF-BB stimulation of ASMCs resulted in activation of the PI3K/AKT signaling pathway, which was blocked post HBD-3 silencing, while the role of si-hBD in PDGF-BB stimulated ASMCs was neutralized post-treatment with IGF-1. Finally, it was found that METTL3 overexpression prominently upregulated the m6A levels of HBD-3 and decreased the mRNA expression and stability of HBD-3 in the PDGF-BB-stimulated ASMCs. The study concluded that METTL3-mediated HBD-3 participates in the progression of asthma through the PI3K/AKT signaling pathway.

Beta-defensin index: A functional biomarker for oral cancer detection

There is an unmet clinical need for a non-invasive and cost-effective test for oral squamous cell carcinoma (OSCC) that informs clinicians when a biopsy is warranted. Human beta-defensin 3 (hBD-3), an epithelial cell-derived anti-microbial peptide, is pro-tumorigenic and overexpressed in early-stage OSCC compared to hBD-2. We validate this expression dichotomy in carcinoma in situ and OSCC lesions using immunofluorescence microscopy and flow cytometry. The proportion of hBD-3/hBD-2 levels in non-invasively collected lesional cells compared to contralateral normal cells, obtained by ELISA, generates the beta-defensin index (BDI). Proof-of-principle and blinded discovery studies demonstrate that BDI discriminates OSCC from benign lesions. A multi-center validation study shows sensitivity and specificity values of 98.2% (95% confidence interval [CI] 90.3-99.9) and 82.6% (95% CI 68.6-92.2), respectively. A proof-of-principle study shows that BDI is adaptable to a point-of-care assay using microfluidics. We propose that BDI may fulfill a major unmet need in low-socioeconomic countries where pathology services are lacking.

Acute promyelocytic leukemia with PML/RARA (bcr1, bcr2 and bcr3) transcripts in a pediatric patient

Patients with acute promyelocytic leukemia (APL) exhibit the t(15;17)(q24.1;q21.2) translocation that produces the promyelocytic leukemia (PML)/retinoic acid receptor α (RARA) fusion gene. Different PML breakpoints yield three alternative molecular transcripts, bcr1, bcr2 and bcr3. The present study reports the simultaneous presence of three PML/RARA transcripts in a pediatric female patient diagnosed with APL, according to the clinical characteristics, immunophenotype and karyotype of the patient. The simultaneous presence of the PML/RARA transcripts were detected using reverse transcription-quantitative PCR (RT-qPCR). This was confirmed with HemaVision-28N Multiplex RT-qPCR, HemaVision-28Q qualitative RT-qPCR and the AmpliSeq RNA Myeloid Panel. To the best of our knowledge, the pediatric patient described in the present study is the first case found to exhibit all three PML/RARA transcripts (bcr1, bcr2 and bcr3). Additionally, a microarray analysis was performed to determine the expression profile, potential predictive biomarkers and the implications of this uncommon finding. According to the information obtained from molecular monitoring, the results reported in the present study were associated with a good patient prognosis. In addition, upregulated genes that are rare in acute myeloid leukemia were identified, and these genes may be promising diagnostic biomarkers for further study. For example, CCL-1 is present in leukemic stem cells, causing treatment failure and relapse, and α- and β-defensins have been reported exclusively in chronic myeloid leukemia. However, the results of the present study confirmed that they may also be present in APL. Thus, these findings suggested a possible signaling pathway that involves the PML/RARA oncoprotein in APL.

Bacillus subtilis Induces Human Beta Defensin-2 Through its Lipoproteins in Human Intestinal Epithelial Cells

Human intestinal epithelial cells (IECs) play an important role in maintaining gut homeostasis by producing antimicrobial peptides (AMPs). Bacillus subtilis, a commensal bacterium, is considered a probiotic. Although its protective effects on intestinal health are widely reported, the key component of B. subtilis responsible for its beneficial effects remains elusive. In this study, we tried to identify the key molecules responsible for B. subtilis-induced AMPs and their molecular mechanisms in a human IEC line, Caco-2. B. subtilis increased human beta defensin (HBD)-2 mRNA expression in a dose- and time-dependent manner. Among the B. subtilis microbe-associated molecular patterns, lipoprotein (LPP) substantially increased the mRNA expression and protein production of HBD-2, whereas lipoteichoic acid and peptidoglycan did not show such effects. Those results were confirmed in primary human IECs. In addition, both LPP recognition and HBD-2 secretion mainly took place on the apical side of fully differentiated and polarized Caco-2 cells through Toll-like receptor 2-mediated JNK/p38 MAP kinase/AP-1 and NF-κB pathways. HBD-2 efficiently inhibited the growth of the intestinal pathogens Staphylococcus aureus and Bacillus cereus. Furthermore, LPPs pre-incubated with lipase or proteinase K decreased LPP-induced HBD-2 expression, suggesting that the lipid and protein moieties of LPP are crucial for HBD-2 expression. Q Exactive Plus mass spectrometry identified 35 B. subtilis LPP candidates within the LPP preparation, and most of them were ABC transporters. Taken together, these results suggest that B. subtilis promotes HBD-2 secretion in human IECs mainly with its LPPs, which might enhance the protection from intestinal pathogens.

Das kutane Mikrobiom bei Hautkrebs - Eine systematische Übersicht: The cutaneous microbiome in skin cancer - A systematic review

Die Hautkrebs‐Inzidenz ist über die vergangene halbe Dekade weltweit gestiegen und mit signifikanter Morbidität und Mortalität assoziiert. Jüngste Fortschritte in der molekularen Diagnostik ermöglichen ein besseres Verständnis von Mikrobiom‐Veränderungen bei diesen Erkrankungen. Allerdings ist die Literatur zum kutanen Mikrobiom bei Hautkrebs nach wie vor heterogen und spärlich. Wir führten eine systematische Überprüfung durch, um die bestehende Literatur sowie ihren Nutzen bezüglich mikrobiombasierter Biomarker zu evaluieren. Die Datenbanken (PubMed, Medline, EMBASE, GoogleScholar) wurden zwischen Juni und Juli 2022 in Übereinstimmung mit den PRISMA‐Richtlinien gesichtet.

Insgesamt wurden 1.543 Artikel ermittelt, von denen 16 in die Übersicht eingeschlossen wurden (11 Artikel zu epithelialen Hauttumoren und 5 Artikel zu Melanomen). Bei Plattenepithelkarzinomen (PEKs) und aktinischer Keratose (AK) wird im Vergleich zu gesunder Haut eine erhöhte Prävalenz von Staphylococcus (S.) aureus bei gleichzeitigem Rückgang der kommensalen Organismen festgestellt. Das Mikrobiom des Melanoms scheint sich zwar von dem der gesunden Haut zu unterscheiden, doch stehen nur wenige Daten für aussagekräftige Schlussfolgerungen zur Verfügung.

Die vorliegende Übersicht fasst die aktuellen Erkenntnisse zum Mikrobiom bei epithelialem Hautkrebs und Melanom zusammen. Sie zeigt, dass sich das Mikrobiom bei diesen Erkrankungen von dem gesunder Haut unterscheidet und dass an dieser Dysbiose sowohl pathogene als auch kommensale Organismen beteiligt sind.

The cutaneous microbiome in skin cancer - A systematic review

The overall incidence of skin cancer has risen over the past half a decade worldwide and is associated with significant morbidity and mortality. Recent advances in molecular testing have allowed us to better characterize microbiome alterations in skin cancer. However, literature specific to skin microbiome and skin cancer remain heterogenous and scattered. A systematic review was performed to identify the existing literature and its usefulness in providing microbiome-based biomarkers. A search of the databases (PubMed, Medline, EMBASE, GoogleScholar) was conducted from June to July 2022 in accordance with the PRISMA guidelines. A total of 1,543 articles were identified, of which 16 were selected for inclusion in the review (11 articles on cancer of the keratinocytes and 5 articles on melanoma). Increased Staphylococcus (S.) aureus prevalence with decline in commensal organisms is seen in squamous cell carcinoma (SCC) and actinic keratosis (AK), compared to healthy skin. While the microbiome of melanoma appears to be distinct from healthy skin, limited data is available to draw meaningful conclusions. Our review summarizes the current evidence on the microbiome of keratinocyte skin cancers and melanoma. The study establishes that the microbiome of these cancers is altered from healthy skin and that this dysbiosis involves both pathogenic and commensal organisms.

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-1β], 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-1β, IL-6, hBD-2 and hBD-3 were higher and the IFN-γ/IL-4 and IL-1β/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-1β, 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-1β, 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.

Genomic profiling and pre-clinical modelling of breast cancer leptomeningeal metastasis reveals acquisition of a lobular-like phenotype

Breast cancer leptomeningeal metastasis (BCLM), where tumour cells grow along the lining of the brain and spinal cord, is a devastating development for patients. Investigating this metastatic site is hampered by difficulty in accessing tumour material. Here, we utilise cerebrospinal fluid (CSF) cell-free DNA (cfDNA) and CSF disseminated tumour cells (DTCs) to explore the clonal evolution of BCLM and heterogeneity between leptomeningeal and extracranial metastatic sites. Somatic alterations with potential therapeutic actionability were detected in 81% (17/21) of BCLM cases, with 19% detectable in CSF cfDNA only. BCLM was enriched in genomic aberrations in adherens junction and cytoskeletal genes, revealing a lobular-like breast cancer phenotype. CSF DTCs were cultured in 3D to establish BCLM patient-derived organoids, and used for the successful generation of BCLM in vivo models. These data reveal that BCLM possess a unique genomic aberration profile and highlight potential cellular dependencies in this hard-to-treat form of metastatic disease.

A multi-omics study to investigate the progression of the Correa pathway in gastric mucosa in the context of cirrhosis

BACKGROUND

Patients with liver cirrhosis (LC) are prone to gastric mucosa damage. We investigated the alterations of gastric mucosa in LC patients and their possible mechanisms through multi-omics.

RESULTS

We observed significant gastric mucosa microbial dysbiosis in LC subjects. Gastric mucosal microbiomes of LC patients contained a higher relative abundance of Streptococcus, Neisseria, Prevotella, Veillonella, and Porphyromonas, as well as a decreased abundance in Helicobacter and Achromobacter, than control subjects. The LC patients had higher levels of bile acids (BAs) and long-chain acylcarnitines (long-chain ACs) in serum. The gastric mucosal microbiomes were associated with serum levels of BAs and long-chain ACs. Transcriptome analyses of gastric mucosa revealed an upregulation of endothelial cell specific molecule 1, serpin family E member 1, mucin 2, caudal type homeobox 2, retinol binding protein 2, and defensin alpha 5 in LC group. Besides, the bile secretion signaling pathway was significantly upregulated in the LC group.

CONCLUSIONS

The alterations in the gastric mucosal microbiome and transcriptome of LC patients were identified. The impaired energy metabolism in gastric mucosal cells and bile acids might aggravate the inflammation of gastric mucosa and even exacerbate the Correa's cascade process. The gastric mucosal cells might reduce bile acid toxicity by bile acid efflux and detoxification.

TRIAL REGISTRATION

ChiCTR2100051070.

Mechanisms and regulation of defensins in host defense

As a family of cationic host defense peptides, defensins are mainly synthesized by Paneth cells, neutrophils, and epithelial cells, contributing to host defense. Their biological functions in innate immunity, as well as their structure and activity relationships, along with their mechanisms of action and therapeutic potential, have been of great interest in recent years. To highlight the key research into the role of defensins in human and animal health, we first describe their research history, structural features, evolution, and antimicrobial mechanisms. Next, we cover the role of defensins in immune homeostasis, chemotaxis, mucosal barrier function, gut microbiota regulation, intestinal development and regulation of cell death. Further, we discuss their clinical relevance and therapeutic potential in various diseases, including infectious disease, inflammatory bowel disease, diabetes and obesity, chronic inflammatory lung disease, periodontitis and cancer. Finally, we summarize the current knowledge regarding the nutrient-dependent regulation of defensins, including fatty acids, amino acids, microelements, plant extracts, and probiotics, while considering the clinical application of such regulation. Together, the review summarizes the various biological functions, mechanism of actions and potential clinical significance of defensins, along with the challenges in developing defensins-based therapy, thus providing crucial insights into their biology and potential clinical utility.

Characterizing the key genes of COVID-19 that regulate tumor immune microenvironment and prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), a highly heterogeneous malignant tumor associated with a poor prognosis, is a common cause of cancer-related deaths worldwide, with a limited survival benefit for patients despite ongoing therapeutic breakthroughs. Coronavirus disease 2019 (COVID-19), a severe infectious disease caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), is a global pandemic and a serious threat to human health. The increased susceptibility to SARS-CoV-2 infection and a poor prognosis in patients with cancer necessitate the exploration of the potential link between the two. No studies have investigated the relationship of COVID-19 genes with the prognosis and tumor development in patients with HCC. We screened prognosis-related COVID-19 genes in HCC, performed molecular typing, developed a stable and reliable COVID-19 genes signature for predicting survival, characterized the immune microenvironment in HCC patients, and explored new molecular therapeutic targets. Datasets of HCC patients, including RNA sequencing data and clinical information, were obtained from The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium (ICGC), and Gene Expression Omnibus (GEO) databases. Prognosis-related COVID-19 genes were identified by univariate Cox analysis. Molecular typing of HCC was performed using the consensus non-negative matrix factorization method (cNMF), followed by the analysis of survival, tumor microenvironment, and pathway enrichment for each subtype. Prognostic signatures were constructed using LASSO-Cox regression models, and receiver operating characteristic (ROC) curves were used to validate the predictive performance of the signature. The same approach was used for the test and external validation sets. Seven software packages were applied to determine the abundance of immune infiltration in HCC patients and investigate its relationship with the risk scores. Gene set enrichment analysis (GSEA) was used to explore the potential mechanisms by which the COVID-19 genes affect hepatocarcinogenesis and prognosis. Three types of machine learning methods were combined to identify the most critical genes in the signature and localize their expression at the single cell level. We identified 53 prognosis-related COVID-19 genes and classified HCC into two molecular subtypes (C1, C2) by using the NMF method. The prognosis of C2 was significantly better than that of C1, and the two subtypes differed remarkably in terms of the tumor immune microenvironment and biological functions. The 17 COVID-19 genes were screened using the LASSO regression method to develop a 17 COVID-19 genes signature, which demonstrated a good predictive performance for 1-, 2- and 3-year OS of patients with HCC. The risk score as an independent prognostic factor for HCC has better predictive accuracy than traditional clinical variables. Patients in the TCGA cohort were categorized by risk score into the high- and low-risk groups, with the high-risk group mainly enriched in the immune modulation-related pathways and the low-risk group mainly enriched in the metabolism-related pathways, suggesting that the COVID-19 genes may affect disease progression and prognosis by regulating the tumor immune microenvironment and metabolism in HCC. NOL10 was identified as the most critical gene in the signature and hypothesized to be a potential therapeutic target for HCC. Objectively, the COVID-19 genes signature developed in this study, as an independent prognostic factor in HCC patients, is closely associated with the prognosis and tumor immune microenvironment of HCC patients and indicates that they may regulate the development of HCC in multiple ways, providing us with new perspectives for understanding the molecular mechanisms of HCC and finding effective therapeutic targets.

Antimicrobial peptides as drugs with double response against Mycobacterium tuberculosis coinfections in lung cancer

Tuberculosis and lung cancer are, in many cases, correlated diseases that can be confused because they have similar symptoms. Many meta-analyses have proven that there is a greater chance of developing lung cancer in patients who have active pulmonary tuberculosis. It is, therefore, important to monitor the patient for a long time after recovery and search for combined therapies that can treat both diseases, as well as face the great problem of drug resistance. Peptides are molecules derived from the breakdown of proteins, and the membranolytic class is already being studied. It has been proposed that these molecules destabilize cellular homeostasis, performing a dual antimicrobial and anticancer function and offering several possibilities of adaptation for adequate delivery and action. In this review, we focus on two important reason for the use of multifunctional peptides or peptides, namely the double activity and no harmful effects on humans. We review some of the main antimicrobial and anti-inflammatory bioactive peptides and highlight four that have anti-tuberculosis and anti-cancer activity, which may contribute to obtaining drugs with this dual functionality.

Human β-Defensins in Diagnosis of Head and Neck Cancers

Head and neck cancers are malignant growths with high death rates, which makes the early diagnosis of the affected patients of utmost importance. Over 90% of oral cavity cancers come from squamous cells, and the tongue, oral cavity, and salivary glands are the most common locations for oral squamous cell carcinoma lesions. Human β-defensins (hBDs), which are mainly produced by epithelial cells, are cationic peptides with a wide antimicrobial spectrum. In addition to their role in antimicrobial defense, these peptides also take part in the regulation of the immune response. Recent studies produced evidence that these small antimicrobial peptides are related to the gene and protein expression profiles of tumors. While the suppression of hBDs is a common finding in head and neck cancer studies, opposite findings were also presented. In the present narrative review, the aim will be to discuss the changes in the hBD expression profile during the onset and progression of head and neck cancers. The final aim will be to discuss the use of hBDs as diagnostic markers of head and neck cancers.

Decreased salivary beta-defensin 2 in children with asthma after treatment with corticosteroid inhaler

PURPOSE

Asthma is the most common chronic disorder in childhood. Inhaled corticosteroid therapy is currently the most effective treatment for Asthma. The oral cavity complications related to this treatment may be in terms of the changes in the innate immune system of mouth. Salivary defensin has many immunomodulatory properties. The expression of beta-defensin 2 was measured before and after inhaled corticosteroid treatment in children with asthma to determine the potential impact of corticosteroids on defensin expression.

METHODS

The present study was a cohort study conducted on the patients referred to Children's Medical Center for whom a diagnosis of Asthma was confirmed, and inhaled corticosteroid therapy was prescribed. Saliva was sampled once at the stage of diagnosis and before receiving any treatment. Another salivary sample was collected 4 weeks after receiving corticosteroids. ELISA was performed to assess beta-defensin 2.

RESULTS

The beta-defensin 2 salivary level after inhaled corticosteroid therapy was significantly lower than before treatment. There is no significant difference in the salivary flow rate before and after treatment.

CONCLUSIONS

Considering the limitations of the present study, the following conclusions can be made salivary beta-defensin 2 is decreased in children with asthma after treatment with a corticosteroid inhaler. Regular dental and oral soft tissue examinations in Asthmatic children under corticosteroid therapy could be suggested.

Investigation of human β-defensins 1, 2 and 3 in human saliva by molecular dynamics

Human β-defensins present in saliva have a broad spectrum of antimicrobial activities that work against infections in oral cavity. To provide a better understanding of these molecules' properties and functions at the molecular level, we have investigated and compared the important structural properties of human β-defensin-1, -2 and -3 using molecular dynamics simulations. Our results have shown that human β-defensin-3 has a more flexible structure in water than the other two because of its high hydrophilicity, low β-sheet content and high repulsive forces between its charged residues. Moreover, we found that the location of the salt bridges is important in protein's stability in water. Molecular dynamics simulations of human β-defensins 1, 2 and 3 revealed that the hbd-3 is more flexible in water than hbd-1 and hbd-2.

Handcrafted versus non-handcrafted (self-supervised) features for the classification of antimicrobial peptides: complementary or redundant?

Antimicrobial peptides (AMPs) have received a great deal of attention given their potential to become a plausible option to fight multi-drug resistant bacteria as well as other pathogens. Quantitative sequence-activity models (QSAMs) have been helpful to discover new AMPs because they allow to explore a large universe of peptide sequences and help reduce the number of wet lab experiments. A main aspect in the building of QSAMs based on shallow learning is to determine an optimal set of protein descriptors (features) required to discriminate between sequences with different antimicrobial activities. These features are generally handcrafted from peptide sequence datasets that are labeled with specific antimicrobial activities. However, recent developments have shown that unsupervised approaches can be used to determine features that outperform human-engineered (handcrafted) features. Thus, knowing which of these two approaches contribute to a better classification of AMPs, it is a fundamental question in order to design more accurate models. Here, we present a systematic and rigorous study to compare both types of features. Experimental outcomes show that non-handcrafted features lead to achieve better performances than handcrafted features. However, the experiments also prove that an improvement in performance is achieved when both types of features are merged. A relevance analysis reveals that non-handcrafted features have higher information content than handcrafted features, while an interaction-based importance analysis reveals that handcrafted features are more important. These findings suggest that there is complementarity between both types of features. Comparisons regarding state-of-the-art deep models show that shallow models yield better performances both when fed with non-handcrafted features alone and when fed with non-handcrafted and handcrafted features together.

Human β-defensin-3 and nuclear factor-kappa B p65 synergistically promote the cell proliferation and invasion of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a usual oral cancer. Therefore, it's essential to identify targets for its early diagnosis and therapy. This research aimed to explore the roles of human β-defensin-3 (hBD-3) and nuclear factor-kappa B (NF-κB) p65 in the pathogenesis and progression of OSCC. The connection between NF-κB p65 and the carcinogenesis of oral cancer was analyzed by immunohistochemical staining. The relative expressions of hBD-3 and NF-κB p65 in OSCC cells were evaluated by qRT-PCR and Western blot. Afterward, hBD-3 was knocked down, and NF-κB p65 was overexpressed. The cell viability and invasion were tested via CCK-8 and Transwell experiment, and the expression of hBD-3, NF-κB p65, and its downstream molecules was evaluated by Western blot. The expression of NF-κB p65 was increased with the aggravation of the oral submucosal fibrosis. HBD-3 and NF-κB p65 were high-expressed in OSCC cells. The viability and invasion abilities of OSCC cells that knocked down hBD-3 were markedly decreased, while they were restored by the overexpression of NF-κB p65. The expressions of NF-κB p65 and c-myc were diminished while IκB and p21 were raised with the knockdown of hBD-3. After overexpression of NF-κB p65, the expression of hBD-3 and IκB did not change markedly, while c-myc was increased and p21 was decreased dramatically. HBD-3 and NF-κB p65 facilitate the proliferation and invasion of OSCC cells, and hBD-3 may promote this process by governing the expression of NF-κB p65 and its downstream c-myc and p21.

Roles of Antimicrobial Peptides in Gynecological Cancers

Antimicrobial peptides (AMPs) are essential components of the mucosal barrier of the female reproductive tract (FRT) and are involved in many important physiological processes, including shaping the microbiota and maintaining normal reproduction and pregnancy. Gynecological cancers seriously threaten women's health and bring a heavy burden to society so that new strategies are needed to deal with these diseases. Recent studies have suggested that AMPs also have a complex yet intriguing relationship with gynecological cancers. The expression level of AMPs changes during tumor progression and they may act as promising biomarkers in cancer detection and prognosis prediction. Although AMPs have long been considered as host protective, they actually play a "double-edged sword" role in gynecological cancers, either tumorigenic or antitumor, depending on factors such as AMP and cancer types, as well as AMP concentrations. Moreover, AMPs are associated with chemoresistance and regulation of AMPs' expression may alter sensitivity of cancer cells to chemotherapy. However, more work is needed, especially on the identification of molecular mechanisms of AMPs in the FRT, as well as the clinical application of these AMPs in detection, diagnosis and treatment of gynecological malignancies.

The recombinant defensin/HSA fusion protein that inhibits NF-κb associated with intensive macropinocytosis shows potent efficacy against pancreatic cancer

KRAS mutation and NF-κB both play crucial role in pancreatic cancer; in addition, defensin, the peptide mediator in innate immunity, can inhibit NF-κB. Assuming a strategy that targets both NF-κB and concomitantly the mutated KRAS indirectly via intensive macropinocytosis, we designed and generated a recombinant protein DF2-HSA which consists of two molecules of human beta-defensin 2 (HBD2) and a moiety of human serum albumin (HSA). As shown, the recombinant protein DF2-HSA markedly down-regulated NF-κB in both KRAS mutant MIA PaCa-2 cells and wild type BxPC-3 cells. Determined by confocal microscopy, the uptake of DF2-HSA in MIA PaCa-2 cells was more intense than that in BxPC-3 cells. The uptake was blocked by the specific inhibitor EIPA, indicating that DF2-HSA internalized via macropinocytosis. DF2-HSA displayed more potent cytotoxicity to cancer cells than HBD2. DF2-HSA induced apoptosis in cancer cells. Notably, DF2-HSA inhibited tumor cell spheroid formation, an effect comparable to that of salinomycin. DF2-HSA inhibited tumor cell migration and invasion. As detected with scanning electron microscopy, DF2-HSA strongly depleted filopodia on cell surface; and salinomycin induced similar changes. By in vivo imaging, DF2-HSA displayed intense tumor-site accumulation and lasting retention for over 14 days; however, HBD2 showed much less tumor-site accumulation and a shorter retention time for only 24 h. DF2-HSA suppressed the growth of pancreatic cancer MIA PaCa-2 xenograft in athymic mice; and its combination with gemcitabine achieved higher antitumor efficacy. In summary, the recombinant defensin/HSA fusion protein that inhibits NF-κb associated with intensive macropinocytosis is highly effective against pancreatic cancer.

Host Defense Peptides at the Ocular Surface: Roles in Health and Major Diseases, and Therapeutic Potentials

Sight is arguably the most important sense in human. Being constantly exposed to the environmental stress, irritants and pathogens, the ocular surface – a specialized functional and anatomical unit composed of tear film, conjunctival and corneal epithelium, lacrimal glands, meibomian glands, and nasolacrimal drainage apparatus – serves as a crucial front-line defense of the eye. Host defense peptides (HDPs), also known as antimicrobial peptides, are evolutionarily conserved molecular components of innate immunity that are found in all classes of life. Since the first discovery of lysozyme in 1922, a wide range of HDPs have been identified at the ocular surface. In addition to their antimicrobial activity, HDPs are increasingly recognized for their wide array of biological functions, including anti-biofilm, immunomodulation, wound healing, and anti-cancer properties. In this review, we provide an updated review on: (1) spectrum and expression of HDPs at the ocular surface; (2) participation of HDPs in ocular surface diseases/conditions such as infectious keratitis, conjunctivitis, dry eye disease, keratoconus, allergic eye disease, rosacea keratitis, and post-ocular surgery; (3) HDPs that are currently in the development pipeline for treatment of ocular diseases and infections; and (4) future potential of HDP-based clinical pharmacotherapy for ocular diseases.

Do deep learning models make a difference in the identification of antimicrobial peptides?

In the last few decades, antimicrobial peptides (AMPs) have been explored as an alternative to classical antibiotics, which in turn motivated the development of machine learning models to predict antimicrobial activities in peptides. The first generation of these predictors was filled with what is now known as shallow learning-based models. These models require the computation and selection of molecular descriptors to characterize each peptide sequence and train the models. The second generation, known as deep learning-based models, which no longer requires the explicit computation and selection of those descriptors, started to be used in the prediction task of AMPs just four years ago. The superior performance claimed by deep models regarding shallow models has created a prevalent inertia to using deep learning to identify AMPs. However, methodological flaws and/or modeling biases in the building of deep models do not support such superiority. Here, we analyze the main pitfalls that led to establish biased conclusions on the leading performance of deep models. Also, we analyze whether deep models truly contribute to achieve better predictions than shallow models by performing fair studies on different state-of-the-art benchmarking datasets. The experiments reveal that deep models do not outperform shallow models in the classification of AMPs, and that both types of models codify similar chemical information since their predictions are highly similar. Thus, according to the currently available datasets, we conclude that the use of deep learning could not be the most suitable approach to develop models to identify AMPs, mainly because shallow models achieve comparable-to-superior performances and are simpler (Ockham's razor principle). Even so, we suggest the use of deep learning only when its capabilities lead to obtaining significantly better performance gains worth the additional computational cost.

Deconstructing Immune Cell Infiltration in Human Colorectal Cancer: A Systematic Spatiotemporal Evaluation

Cancer-related immunity has been identified as playing a key role in the outcome of colorectal cancer (CRC); however, the exact mechanisms are only partially understood. In this study, we evaluated a total of 242 surgical specimen of CRC patients using tissue microarrays and immunohistochemistry to evaluate tumor infiltrating immune cells (CD3, CD4, CD8, CD20, CD23, CD45 and CD56) and immune checkpoint markers (CTLA-4, PD-L1, PD-1) in systematically selected tumor regions and their corresponding lymph nodes, as well as in liver metastases. Additionally, an immune panel gene expression assay was performed on 12 primary tumors and 12 consecutive liver metastases. A higher number of natural killer cells and more mature B cells along with PD-1⁺ expressing cells were observed in the main tumor area as compared to metastases. A higher number of metastatic lymph nodes were associated with significantly lower B cell counts. With more advanced lymph node metastatic status, higher leukocyte—particularly T cell numbers—were observed. Eleven differentially expressed immune-related genes were found between primary tumors and liver metastases. Also, alterations of the innate immune response and the tumor necrosis factor superfamily pathways had been identified.

Regulatory Roles of Antimicrobial Peptides in the Nervous System: Implications for Neuronal Aging

Antimicrobial peptides (AMPs) are classically known as important effector molecules in innate immunity across all multicellular organisms. However, emerging evidence begins to suggest multifunctional properties of AMPs beyond their antimicrobial activity, surprisingly including their roles in regulating neuronal function, such as sleep and memory formation. Aging, which is fundamental to neurodegeneration in both physiological and disease conditions, interestingly affects the expression pattern of many AMPs in an infection-independent manner. While it remains unclear whether these are coincidental events, or a mechanistic relationship exists, previous studies have suggested a close link between AMPs and a few key proteins involved in neurodegenerative diseases. This review discusses recent literature and advances in understanding the crosstalk between AMPs and the nervous system at both molecular and functional levels, with the aim to explore how AMPs may relate to neuronal vulnerability in aging.

Antimicrobial and Anti-inflammatory Gallium-Defensin Surface Coatings for Implantable Devices

Emerging and re-emerging infections are a global threat driven by the development of antimicrobial resistance due to overuse of antimicrobial agents and poor infection control practices. Implantable devices are particularly susceptible to such infections due to the formation of microbial biofilms. Furthermore, the introduction of implants into the body often results in inflammation and foreign body reactions. The antimicrobial and anti-inflammatory properties of gallium (Ga) have been recognized but not yet utilized effectively to improve implantable device integration. Furthermore, defensin (De, hBD-1) has potent antimicrobial activity in vivo as part of the innate immune system; however, this has not been demonstrated as successfully when used in vitro. Here, we combined Ga and De to impart antimicrobial activity and anti-inflammatory properties to polymer-based implantable devices. We fabricated polylactic acid films, which were modified using Ga implantation and subsequently functionalized with De. Ga-ion implantation increased surface roughness and increased stiffness. Ga implantation and defensin immobilization both independently and synergistically introduced antimicrobial activity to the surfaces, significantly reducing total live bacterial biomass. We demonstrated, for the first time, that the antimicrobial effects of De were unlocked by its surface immobilization. Ga implantation of the surface also resulted in reduced foreign body giant cell formation and expression of proinflammatory cytokine IL-1β. Cumulatively, the treated surfaces were able to kill bacteria and reduce inflammation in comparison to the untreated control. These innovative surfaces have the potential to prevent biofilm formation without inducing cellular toxicity or inflammation, which is highly desired for implantable device integration.

Implications of Human Antimicrobial Peptide Defensin Beta-1 in Clinical Oral Squamous Cell Carcinoma Patients via an Integrated Bioinformatics Approach

BACKGROUND

The human antimicrobial peptide defensin beta 1 (DEFB1) has been found to play antimicrobial and anti-inflammatory roles in oral diseases; however, its tumor-regulating role in oral squamous cell carcinoma (OSCC) has not yet been researched by using an integrative bioinformatics approach.

OBJECTIVE

To investigate the regulating mechanisms of the DEFB1 gene in OSCC in terms of its expression patterns, prognostic values, biological functions, and implication for tumor immunity.

METHODS

The DEFB1 gene expression pattern and regulatory involvement in OSCC were investigated using publically accessible data from TCGA database. R software tools and public web servers were utilized to conduct statistical analysis of data from cancer and noncancerous samples.

RESULTS

DEFB1 was found to be significantly downregulated in OSCC tumor samples compared with healthy control oral samples. The DEFB1 gene was found associated with the prognostic outcomes of OSCC, and its upregulation represented better survival outcome. Gene set enrichment analysis (GSEA) results showed that DEFB1-significantly correlated genes were mainly enriched in four signaling pathways mediating the antitumor role of DEFB1 in OSCC, including extracellular matrix-related pathway, RTK/PI3K/AKT/mTOR pathway, keratinization, and cytokine-related pathway. The gene-gene interaction network showed that DEFB1 was closely correlated with several genes, for example, CCR6 (C-C motif chemokine receptor 6), CXCL1 (C-X-C motif chemokine ligand 1), MAP4K2 (mitogen-activated protein kinase kinase kinase kinase 2), PTGER3 (prostaglandin E receptor 3), and MMP7 (matrix metallopeptidase 7). Moreover, DEFB1 was found to be involved in the tumor immunity of OSCC by regulating the function of tumor macrophage cells, mast cells, T cells, and NK cells.

CONCLUSIONS

Given the dysregulation, prognostic value, and tumor progression-related biological pathway alteration, indicating the tumor immune-modulatory role of DEFB1 in OSCC, the DEFB1 gene should be regarded as a potential therapeutic target for treating oral cancer.

Tumor-Infiltrating CD4+ Central Memory T Cells Correlated with Favorable Prognosis in Oral Squamous Cell Carcinoma

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is the most frequent oral malignancy with a poor prognosis, in which tumor-infiltrating immune cells may play a critical role. Therefore, our study aims to screen potential immune cells and immune-related genes for predicting OSCC prognosis.

METHODS

A total of 310 OSCC patients with full transcriptional data and clinical characteristics were extracted from the TCGA database. Then, we obtained their abundance of tumor-infiltrating immune cells on TIMER 2.0 and analyzed them using xCell method. Univariate and multivariate Cox regressions were applied successively to identify the immune cells associated with overall survival of OSCC patients. Furthermore, we screened the prognostic genes that related to the identified immune cells and validated their expressions by immunohistochemistry.

RESULTS

CD4+ central memory T (TCM) cell was recognized as the sole independent immune cell correlated with OSCC prognosis (p = 0.0085). A novel nomogram based on CD4+ TCM cell abundance was established for predicting the prognosis of OSCC patients, with calibration plots showing good performance for 1-, 3-, 5-year overall survival. Thirty-four related prognostic genes were screened according to the differential abundance of CD4+ TCM cell infiltration. In immunohistochemistry analysis, DEFB1 showed a significant positive relationship with the density of CD4+ TCM cells (p = 0.0075).

CONCLUSION

CD4+ central memory T cell was proposed as an independent prognostic biomarker for OSCC patients. DEFB1 might positively regulate the abundance of tumor-infiltrating CD4+ TCM cells, thus improving OSCC prognosis. Our findings may provide a new insight into better prognosis prediction and precise medicine for OSCC.

Defensins: The natural peptide antibiotic

Defensins are a family of cationic antimicrobial peptides active against a broad range of infectious microbes including bacteria, viruses and fungi, playing important roles as innate effectors and immune modulators in immunological control of microbial infection. Their antibacterial properties and unique mechanisms of action have garnered considerable interest in developing defensins into a novel class of natural antibiotic peptides to fend off pathogenic infection by bacteria, particularly those resistant to conventional antibiotics. However, serious pharmacological and technical obstacles, some of which are unique to defensins and others are common to peptide drugs in general, have hindered the development and clinical translation of defensins as anti-infective therapeutics. To overcome them, several technologies have been developed, aiming for improved functionality, prolonged circulation time, enhanced proteolytic stability and bioavailability, and efficient and controlled delivery and release of defensins to the site of infection. Additional challenges include the alleviation of potential toxicity of defensins and their cost-effective manufacturing. In this review, we briefly introduce defensin biology, focus on various transforming strategies and practical techniques developed for defensins and their derivatives as antibacterial therapeutics, and conclude with a summation of future challenges and possible solutions.

A novel smaller β-defensin-derived peptide is active against multidrug-resistant bacterial strains

Antibiotic resistance is becoming a severe obstacle in the fight against acute and chronic infectious diseases that accompany most degenerative illnesses from neoplasia to osteo-arthritis and obesity. Currently, the race is on to identify pharmaceutical molecules or combinations of molecules able to prevent or reduce the insurgence and/or progression of infectivity. Attempts to substitute antibiotics with antimicrobial peptides have, thus far, met with little success against multidrug-resistant (MDR) bacterial strains. During the last decade, we designed and studied the activity and features of human β-defensin analogs, which are salt-resistant, and hence active also under high salt concentrations as, for instance, in cystic fibrosis. Herein, we describe the design, synthesis, and major features of a new 21 aa long molecule, peptide γ2. The latter derives from the γ-core of the β-defensin natural molecules, a small fragment of these molecules still bearing high antibacterial activity. We found that peptide γ2, which contains only one disulphide bond, recapitulates most of the biological properties of natural human β-defensins and can also counteract both Gram-positive and Gram-negative MDR bacterial strains and biofilm formation. Moreover, it has great stability in human serum thereby enhancing its antibacterial presence and activity without cytotoxicity in human cells. In conclusion, peptide γ2 is a promising new weapon also in the battle against intractable infectious diseases.

Elevated serum levels of cathelicidin and β-defensin 2 are associated with basal cell carcinoma

Antimicrobial peptides (AMPs) are one of the primary mechanisms used by the skin in the early stages of immune defense. AMPs have a broad antibacterial activity and also show antifungal and antiviral attributes. Various studies have also shown that levels of antimicrobial peptides change with the development of neoplasia. The aim of this paper is to assess the associations between the presence of basal cell carcinoma (BCC) and the plasma concentrations of cathelicidin and β-defensins (HBD1-3). We examined 108 patients (56 women, 52 men). The BCC group consisted of 49 patients with mean age 69.8 ±12.3 and the control group consisted of 59 participants with mean age 62.1 ±11.1. A statistical analysis of data was performed. The median serum concentration of cathelicidin was almost 3 times higher and the median concentration of HBD-2 more than 6 times higher in BCC patients than in the control group (p < 0.001). The logistic regression model revealed in univariate analysis that patients who had a detected cathelicidin level above ~1500 pg/ml had 9.9× higher likelihood of having BCC identified in the histopathology in comparison with the control group. In patients who had a HBD-2 level above ~1.2 ng/ml the OR of having BCC identified in the histopathology was 12.6 (p < 0.001). Elevated concentrations of cathelicidin and β-defensin 2 are associated with the presence of basal cell carcinoma. Additionally, the specificity of cathelicidin and β-defensin 2 in detecting basal cell carcinoma is high. However, it should be remembered that these factors are not specific only to this condition and further studies are needed.

Dissecting the relationship between antimicrobial peptides and mesenchymal stem cells

Among the various biological properties presented by Mesenchymal Stem Cells (MSCs), their ability to control the immune response and fight pathogen infection through the production of antimicrobial peptides (AMPs) have been the subject of intense research in recent years. AMPs secreted by MSCs exhibit activity against a wide range of microorganisms, including bacteria, fungi, yeasts, and viruses. The main AMPs produced by these cells are hepcidin, cathelicidin LL-37, and β-defensin-2. In addition to acting against pathogens, those AMPs have also been shown to interact with MSCs to modulate MSC proliferation, migration, and regeneration, indicating that such peptides exert a more diverse biological effect than initially thought. In the present review, we discuss the production of AMPs by MSCs, revise the multiple functions of these peptides, including their influence over MSCs, and present an overview of clinical situations in which the antimicrobial properties of MSCs may be explored for therapy. Finally, we discuss possibilities of combining MSCs and AMPs to generate improved therapeutic strategies.

Dysregulation of human beta-defensin-3 expression in the peripheral blood of patients with sepsis

Objectives:

Sepsis is a serious medical condition caused by the body’s systemic inflammatory response to infections. The antimicrobial peptides, human beta-defensins, play a key role in modulating host immune responses, and aberrant expression of human beta-defensins has been implicated in many infections and inflammatory diseases. However, little is known about the expression of human beta-defensin-3 in systemic infectious diseases.

Methods:

We investigated the gene expression and protein level of human beta-defensin-3 in peripheral whole blood from 107 participants—67 patients with sepsis and 40 healthy controls—and evaluated the feasibility of human beta-defensin-3 as an indicator for sepsis. Total RNA was extracted from peripheral blood samples, and relative mRNA expression of human beta-defensin-3 was determined by reverse transcription-quantitative polymerase chain reaction. Plasma concentration of human beta-defensin-3 was measured by enzyme-linked immunosorbent assay. Pearson’s correlation analysis was performed to assess the relationship between human beta-defensin-3 mRNA and protein levels. Receiver operating characteristic analysis was performed to evaluate the value of human beta-defensin-3 as a biomarker for sepsis.

Results:

Human beta-defensin-3 mRNA expression was significantly downregulated in sepsis patients compared to controls (p = 0.001). The mean fold change of mRNA expression (±standard error) was 0.82 ± 0.63 in sepsis patients and 1.39 ± 1.09 in controls. Plasma concentration of human beta-defensin-3 (pg/mL) was significantly lower in sepsis patients compared to healthy controls (p = 0.039). The mean protein concentration (±standard error) was 539.6 ± 39.4 in sepsis patients and 715.5 ± 53 in controls. There was a significant correlation between human beta-defensin-3 mRNA expression and the corresponding protein level in sepsis patients (r = 0.358, p = 0.04), but not in healthy controls (r = 0.124, p = 0.51). For discriminating sepsis patients from healthy controls, the area under the receiver operating characteristic curve was 0.722 (95% confidence interval: 0.597–0.847, p = 0.002) for human beta-defensin-3 mRNA and 0.689 (95% confidence interval: 0.557–0.827, p = 0.009) for human beta-defensin-3 protein.

Conclusion:

This is the first study to show the downregulation of human beta-defensin-3 gene expression and protein level in sepsis, which may contribute to the complex immunological imbalance in sepsis. The significant correlation between human beta-defensin-3 mRNA expression and protein concentration suggests that mRNA expression could be used to predict protein level. Our study also showed a potential role of human beta-defensin-3 as a blood-based biomarker for sepsis. More studies on the clinical significance of human beta-defensin-3 in sepsis could further support a biomarker development.

Alignment-Free Antimicrobial Peptide Predictors: Improving Performance by a Thorough Analysis of the Largest Available Data Set

In the last two decades, a large number of machine-learning-based predictors for the activities of antimicrobial peptides (AMPs) have been proposed. These predictors differ from one another in the learning method and in the training and testing data sets used. Unfortunately, the training data sets present several drawbacks, such as a low representativeness regarding the experimentally validated AMP space, and duplicated peptide sequences between negative and positive data sets. These limitations give a low confidence to most of the approaches to be used in prospective studies. To address these weaknesses, we propose novel modeling and assessing data sets from the largest experimentally validated nonredundant peptide data set reported to date. From these novel data sets, alignment-free quantitative sequence-activity models (AF-QSAMs) based on Random Forest are created to identify general AMPs and their antibacterial, antifungal, antiparasitic, and antiviral functional types. An applicability domain analysis is carried out to determine the reliability of the predictions obtained, which, to the best of our knowledge, is performed for the first time for AMP recognition. A benchmarking is undertaken between the models proposed and several models from the literature that are freely available in 13 programs (ClassAMP, iAMP-2L, ADAM, MLAMP, AMPScanner v2.0, AntiFP, AMPfun, PEPred-suite, AxPEP, CAMPR3, iAMPpred, APIN, and Meta-iAVP). The models proposed are those with the best performance in all of the endpoints modeled, while most of the methods from the literature have weak-to-random predictive agreements. The models proposed are also assessed through Y-scrambling and repeated k-fold cross-validation tests, demonstrating that the outcomes obtained by them are not given by chance. Three chemometric analyses also confirmed the relevance of the peptides descriptors used in the modeling. Therefore, it can be concluded that the models built by fixing the drawbacks existing in the literature contribute to identifying antibacterial, antifungal, antiparasitic, and antiviral peptides with high effectivity and reliability. Models are freely available via the AMPDiscover tool at https://biocom-ampdiscover.cicese.mx/.

The inhibitory effect of human DEFA5 in growth of gastric cancer by targeting BMI1

Defensins, a class of small cysteine‐rich cationic polypeptides across cellular life, are identified as antimicrobial compounds that display direct antimicrobial and immune signaling activities that are involved in the host defense. In addition to their roles in the innate immune system, accumulating studies have reported that some members of defensins are expressed and involved in some cancer cells, such as colon cancer, colorectal cancer, lung cancer and renal cell carcinomas. However, the roles of α‐Defensin 5 (DEFA5) in tumorigenesis and development remain unknown. In the present study, bioinformatics analysis and quantitative PCR results showed that the expression level of DEFA5 was dramatically downregulated in human gastric cancer. Overexpression of human DEFA5 in gastric cancer cell lines SGC7901 and BGC823 effectively diminished cell proliferation and reduced the colony forming ability. Moreover, DEFA5 overexpression induced cell cycle arrest by significantly increasing the number of G1‐phase cells. Consistently, in vivo tumor formation experiments in nude mice showed the suppression of the tumor growth by DEFA5 overexpression, suggesting an inhibitory effect of DEFA5 in gastric cancer. Mechanistically, DEFA5 directly binds to BMI1, which subsequently decreased its binding at the CDKN2a locus and upregulated the expression of 2 cyclin‐dependent kinase inhibitors, p16 and p19. Taken together, we concluded that DEFA5 showed an inhibitory effect in gastric cancer cell growth and may serve as a potential tumor suppressor in gastric cancer.

In silico analysis of non-synonymous single nucleotide polymorphisms of human DEFB1 gene

Background

Single nucleotide polymorphisms (SNPs) play a significant role in differences in individual’s susceptibility to diseases, and it is imperative to differentiate potentially harmful SNPs from neutral ones. Defensins are small cationic antimicrobial peptides that serve as antimicrobial and immunomodulatory molecules, and SNPs in β-defensin 1 (DEFB1 gene) have been associated with several diseases. In this study, we have determined deleterious SNPs of the DEFB1 gene that can affect the susceptibility to diseases by using different computational methods. Non-synonymous SNPs (nsSNPs) of the DEFB1 gene that have the ability to affect protein structure and functions were determined by several in silico tools—SIFT, PolyPhen v2, PROVEAN, SNAP, PhD-SNP, and SNPs&GO. Then, nsSNPs identified to be potentially deleterious were further analyzed by I-Mutant and ConSurf. Post-translational modifications mediated by nsSNPs were predicted by ModPred, and gene-gene interaction was studied by GeneMANIA. Finally, nsSNPs were submitted to Project HOPE analysis.

Results

Ten nsSNPs of the DEFB1 gene were found to be potentially deleterious: rs1800968, rs55874920, rs56270143, rs140503947, rs145468425, rs146603349, rs199581284, rs201260899, rs371897938, rs376876621. I-Mutant server showed that nsSNPs rs140503947 and rs146603349 decreased stability of the protein, and ConSurf analysis revealed that SNPs were located in conserved regions. The physiochemical properties of the polymorphic amino acid residues and their effect on structure were determined by Project HOPE.

Conclusion

This study has determined high-risk deleterious nsSNPs of β-defensin 1 and could increase the knowledge of nsSNPs towards the impact of mutations on structure and functions mediated by β-defensin 1 protein.

Genome‑wide copy number analysis of circulating tumor cells in breast cancer patients with liver metastasis

The genome‑wide copy number analysis of circulating tumor cells (CTCs) provides a promising prognostic biomarker for survival in breast cancer liver metastasis (BCLM) patients. The present study aimed to confirm the prognostic value of the presence of CTCs in BCLM patients. We previously developed an assay for the genome‑wide pattern differences in copy number variations (CNVs) as an adjunct test for the routine imaging and histopathologic diagnosis methods to distinguish newly diagnosed liver metastases and recurrent liver metastases. Forty‑three breast cancer patients were selected for this study in which 23 newly diagnosed and 20 recurrent liver metastases were diagnosed by histopathology and 18F‑FDG PET/CT imaging. CTCs were counted from all patients using the CellSearch system and were confirmed by cytomorphology and three‑color immunocytochemistry. Genomic DNA of single CTCs was amplified using multiple annealing and looping based amplification cycles (MALBAC). Then, we compared the CTC numbers of newly diagnosed and recurrent BCLM patients using Illumina platforms. A high CTC frequency (>15 CTCs/7.5 ml blood) was found to be correlated with disease severity and metastatic progression, which suggests the value for CTCs in the diagnosis of BCLM in comparison with pathohistology and PET/CT imaging (P>0.05). Moreover, CTCs isolated from BCLM patients remained an independent prognostic detection factor associated with overall survival (P=0.0041). Comparison between newly diagnosed and recurrent liver metastases revealed different frequencies of CNVs (P>0.05). Notably, the CNV pattern of isolated CTCs of recurrent BCLM patients was similar to recurrent liver metastases (nearly 82% of the gain/loss regions). Functional enrichment analysis identified 25 genes as a CNV signature of BCLM. Among them, were defensin and β‑defensin genes, which are significantly associated with anti‑angiogenesis and immunomodulation signaling pathways. High CTC frequencies are effective in the evaluation and differentiation between newly diagnosed liver metastases from recurrent liver metastases. Future clinical studies will be necessary to fully determine the prognostic potential of CTC cluster signatures in patients with BCLM.

The Dichotomous Responses Driven by β-Defensins

Defensins are short, rapidly evolving, cationic antimicrobial host defence peptides with a repertoire of functions, still incompletely realised, that extends beyond direct microbial killing. They are released or secreted at epithelial surfaces, and in some cases, from immune cells in response to infection and inflammation. Defensins have been described as endogenous alarmins, alerting the body to danger and responding to inflammatory signals by promoting both local innate and adaptive systemic immune responses. However, there is now increasing evidence that they exert variable control on the response to danger; creating a dichotomous response that can suppress inflammation in some circumstances but exacerbate the response to danger and damage in others and, at higher levels, lead to a cytotoxic effect. Focussing in this review on human β-defensins, we discuss the evidence for their functions as proinflammatory, immune activators amplifying the response to infection or damage signals and/or as mediators of resolution of damage, contributing to a return to homeostasis. Finally, we consider their involvement in the development of autoimmune diseases.

Defensins: A Double-Edged Sword in Host Immunity

Defensins are a major family of host defense peptides expressed predominantly in neutrophils and epithelial cells. Their broad antimicrobial activities and multifaceted immunomodulatory functions have been extensively studied, cementing their role in innate immunity as a core host-protective component against bacterial, viral and fungal infections. More recent studies, however, paint defensins in a bad light such that they are "alleged" to promote viral and bacterial infections in certain biological settings. This mini review summarizes the latest findings on the potential pathogenic properties of defensins against the backdrop of their protective roles in antiviral and antibacterial immunity. Further, a succinct description of both tumor-proliferative and -suppressive activities of defensins is also given to highlight their functional and mechanistic complexity in antitumor immunity. We posit that given an enabling environment defensins, widely heralded as the "Swiss army knife," can function as a "double-edged sword" in host immunity.

Molecular Profiling of Keratinocyte Skin Tumors Links Staphylococcus aureus Overabundance and Increased Human β-Defensin-2 Expression to Growth Promotion of Squamous Cell Carcinoma

The skin microbiota plays a prominent role in health and disease; however, its contribution to skin tumorigenesis is not well understood. We comparatively assessed the microbial community compositions from excision specimens of the main human non-melanoma skin cancers, actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Keratinocyte skin tumors are characterized by significantly different microbial community compositions, wherein AK and SCC are more similar to each other than to BCC. Notably, in SCC, which represents the advanced tumor entity and frequently develops from AK, overabundance of Staphylococcus aureus, a known skin pathogen, was noted. Moreover, S. aureus overabundance was significantly associated with increased human β-defensin-2 (hBD-2) expression in SCC. By challenging human SCC cell lines with S. aureus, a specific induction of hBD-2 expression and increased tumor cell growth was seen. Increased proliferation was also induced by directly challenging SCC cells with hBD-2. Together, our data indicate that a changed microbial community composition in SCC, specified by S. aureus overabundance, might promote tumor cell growth via modulation of hBD-2 expression.

Acute Exposure to Zearalenone Disturbs Intestinal Homeostasis by Modulating the Wnt/β-Catenin Signaling Pathway

The mycotoxin zearalenone (ZEN), which frequently contaminates cereal-based human food and animal feed, is known to have an estrogenic effect. The biological response associated with exposure to ZEN has rarely been reported in organs other than the reproductive system. In the intestine, several studies suggested that ZEN might stimulate molecular changes related to the activation of early carcinogenesis, but the molecular mechanisms behind these events are not yet known. In this study, we investigated gene expression and changes in protein abundance induced by acute exposure to ZEN in the jejunum of castrated male pigs using an explant model. Our results indicate that ZEN induces the accumulation of ERα but not ERβ, modulates Wnt/β-catenin and TGF-β signaling pathways, and induces molecular changes linked with energy sensing and the antimicrobial activity without inducing inflammation. Our results confirm that the intestine is a target for ZEN, inducing changes that promote cellular proliferation and could contribute to the onset of intestinal pathologies.

HBD3 Induces PD-L1 Expression on Head and Neck Squamous Cell Carcinoma Cell Lines

Human β-defensin 3 (HBD3) is an antimicrobial peptide up-regulated in the oral tissues of individuals with head and neck squamous cell carcinomas (HNSCC) and oral squamous cell carcinomas (SCC) and present in high concentrations in their saliva. In this study, we determined if HBD3 contributes to HNSCC pathogenesis by inducing programmed death-ligand 1 (PD-L1) expression on HNSCC cell lines. For this, SCC cell lines SCC4, SCC15, SCC19, SCC25, and SCC99 (5.0 × 10⁴ viable cells) were used. Cells were incubated with IFNγ (0.6 µM) and HBD3 (0.2, 2.0, or 20.0 µM) for 24 h. Cells alone served as controls. Cells were then treated with anti-human APC-CD274 (PD-L1) and Live/Dead Fixable Green Dead Cell Stain. Cells treated with an isotype antibody and cells alone served as controls. All cell suspensions were analyzed in a LSR II Violet Flow Cytometer. Cytometric data was analyzed using FlowJo software. Treatment with IFNγ (0.6 µM) increased the number of cells expressing PD-L1 (p < 0.05) with respect to controls. Treatment with HBD3 (20.0 µM) also increased the number of cells expressing PD-L1 (p < 0.05) with respect to controls. However, treatment with IFNγ (0.6 µM) was not significantly different from treatment with HBD3 (20.0 µM) and the numbers of cells expressing PD-L1 were similar (p = 1). Thus, HBD3 increases the number of cells expressing PD-L1. This is a novel concept, but the role HBD3 contributes to HNSCC pathogenesis by inducing PD-L1 expression in tumors will have to be determined.