Modulation of Human β-Defensin-1 Production by Viruses

Polymorphic variation of the DEFB1 gene might contribute to the development of ankylosing spondylitis: a preliminary study

BACKGROUND

Ankylosing spondylitis (AS) is an inflammatory disease that affects the spine and can cause peripheral arthritis, enthesitis, and dactylitis, as well as extra-articular manifestations such as uveitis and inflammatory bowel disease. β-Defensins are antimicrobial peptides involved in the activation and regulation of several immune cell types that may influence the inflammatory response in AS. The aim was to analyze the association and interaction of two functional variants of the DEFB1 gene in AS patients, and their role with inflammatory markers.

METHODS AND RESULTS

The rs11362 and rs1800972 variants were genotyped using TaqMan probes in Mexican AS patients and controls. C-reactive protein (CRP) levels and erythrocyte sedimentation rate (ESR) were quantified. SPSS software was used for statistical analysis and multifactor dimensionality reduction (MDR) for interactions. The AA and GG genotypes were associated with AS risk in the age- and sex-adjusted model (OR = 6.89, P = 0.008 and OR = 3.43, P = 0.046, respectively); furthermore, the A-G haplotype showed a significant association with AS risk (OR = 2.94, P = 0.012). ESR and CRP were elevated in carriers of the AA genotype compared to the GA and GG genotypes of the rs11362 variant (20.89 ± 9.78 vs. 5.63 ± 4.61 and 4.10 ± 2.65 mm/h, P < 0.0001; and 10.92 ± 14.09 vs. 2.14 ± 2.02 and 2.15 ± 2.13 mg/L, P < 0.001, respectively). Using the MDR method, strong interactions of the rs11362 variant with sex were identified in the adjusted and unadjusted models.

CONCLUSIONS

These results suggest that the DEFB1 gene may play a key role in AS pathogenesis.

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.

Proteome based analysis of circulating SARS-CoV-2 variants: approach to a universal vaccine candidate

The discovery of the first infectious variant in Wuhan, China, in December 2019, has posed concerns over global health due to the spread of COVID-19 and subsequent variants. While the majority of patients experience flu-like symptoms such as cold and fever, a small percentage, particularly those with compromised immune systems, progress from mild illness to fatality. COVID-19 is caused by a RNA virus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our approach involved utilizing immunoinformatic to identify vaccine candidates with multiple epitopes and ligand-binding regions in reported SARS-CoV-2 variants. Through analysis of the spike glycoprotein, we identified dominant epitopes for T-cells and B-cells, resulting in a vaccine construct containing two helper T-cell epitopes, six cytotoxic T-cell epitopes, and four linear B-cell epitopes. Prior to conjugation with adjuvants and linkers, all epitopes were evaluated for antigenicity, toxicity, and allergenicity. Additionally, we assessed the vaccine Toll-Like Receptors complex (2, 3, and 4). The vaccine construct demonstrated antigenicity, non-toxicity, and non-allergenicity, thereby enabling the host to generate antibodies with favorable physicochemical characteristics. Furthermore, the 3D structure of the B-cell construct exhibited a ProSA-web z-score plot with a value of -1.71, indicating the reliability of the designed structure. The Ramachandran plot analysis revealed that 99.6% of the amino acid residues in the vaccine subunit were located in the high favored observation region, further establishing its strong candidacy as a vaccination option.

β-Defensin-1 Regulates Influenza Virus Infection in Human Bronchial Epithelial Cells through the STAT3 Signaling Pathway

Understanding the host response to influenza A virus (IAV) infection is vital for developing intervention strategies. The primary barriers for invading respiratory pathogens are the respiratory tract epithelial cells and antimicrobial proteins generated by these cells. The antimicrobial peptide, β-defensin-1, has antiviral activity against both enveloped and non-enveloped viruses. Significant downregulation of β-defensin1 gene (DEFB1) expression was observed when human bronchial epithelial cells (HBEpCs) were exposed to IAV. HBEpCs overexpressing DEFB1 caused a significant reduction in IAV, that was confirmed by IAV matrix gene analysis, plaque assay, and confocal microscopy. DEFB1 expression after transfection with two micro RNAs (miRNAs), hsa-miR-186-5p and hsa-miR-340-5p, provided evidence that DEFB1 expression could be modulated by these miRNAs and hsa-miR-186-5p had a higher binding efficiency with DEFB1. Overexpression of DEFB1 in IAV-infected HBEpCs led to increased NF-κB expression. In a PCR array analysis of 84 transcription factors, either overexpressing DEFB1 or siRNA silencing of DEFB1 expression significantly modulated the expression of signal transducer and activator of transcription 3 (STAT3). In addition, Ingenuity Pathway Analysis (IPA) integrated with PCR array data showed that the JAK1/STAT3 pathway was significantly altered in cells overexpressing DEFB1, suggesting this to be one of the pathways by which defensin regulates IAV replication in HBEpCs. In conclusion, the reduction in IAV copy number in DEFB1 overexpressing cells suggests that β-defensin-1 plays a key role in regulating IAV survival through STAT3 and is a potential target for antiviral drug development.

Antimicrobial peptides: Defending the mucosal epithelial barrier

The recent epidemic caused by aerosolized SARS-CoV-2 virus illustrates the importance and vulnerability of the mucosal epithelial barrier against infection. Antimicrobial proteins and peptides (AMPs) are key to the epithelial barrier, providing immunity against microbes. In primitive life forms, AMPs protect the integument and the gut against pathogenic microbes. AMPs have also evolved in humans and other mammals to enhance newer, complex innate and adaptive immunity to favor the persistence of commensals over pathogenic microbes. The canonical AMPs are helictical peptides that form lethal pores in microbial membranes. In higher life forms, this type of AMP is exemplified by the defensin family of AMPs. In epithelial tissues, defensins, and calprotectin (complex of S100A8 and S100A9) have evolved to work cooperatively. The mechanisms of action differ. Unlike defensins, calprotectin sequesters essential trace metals from microbes, which inhibits growth. This review focuses on defensins and calprotectin as AMPs that appear to work cooperatively to fortify the epithelial barrier against infection. The antimicrobial spectrum is broad with overlap between the two AMPs. In mice, experimental models highlight the contribution of both AMPs to candidiasis as a fungal infection and periodontitis resulting from bacterial dysbiosis. These AMPs appear to contribute to innate immunity in humans, protecting the commensal microflora and restricting the emergence of pathobionts and pathogens. A striking example in human innate immunity is that elevated serum calprotectin protects against neonatal sepsis. Calprotectin is also remarkable because of functional differences when localized in epithelial and neutrophil cytoplasm or released into the extracellular environment. In the cytoplasm, calprotectin appears to protect against invasive pathogens. Extracellularly, calprotectin can engage pathogen-recognition receptors to activate innate immune and proinflammatory mechanisms. In inflamed epithelial and other tissue spaces, calprotectin, DNA, and histones are released from degranulated neutrophils to form insoluble antimicrobial barriers termed neutrophil extracellular traps. Hence, calprotectin and other AMPs use several strategies to provide microbial control and stimulate innate immunity.

Diagnostic and Therapeutic Potential for HNP-1, HBD-1 and HBD-4 in Pregnant Women with COVID-19

Pregnancy is characterized by significant immunological changes and a cytokine profile, as well as vitamin deficiencies that can cause problems for the correct development of a fetus. Defensins are small antimicrobial peptides that are part of the innate immune system and are involved in several biological activities. Following that, this study aims to compare the levels of various cytokines and to investigate the role of defensins between pregnant women with confirmed COVID-19 infection and pregnant women without any defined risk factor. TNF-α, TGF-β, IL-2 and IL-10, β-defensins, have been evaluated by gene expression in our population. At the same time, by ELISA assay IL-6, IL-8, defensin alpha 1, defensin beta 1 and defensin beta 4 have been measured. The data obtained show that mothers affected by COVID-19 have an increase in pro-inflammatory factors (TNF-α, TGF-β, IL-2, IL-6, IL-8) compared to controls; this increase could generate a sort of “protection of the fetus” from virus attacks. Contemporarily, we have an increase in the anti-inflammatory cytokine IL-10 and an increase in AMPs, which highlights how the mother’s body is responding to the viral attack. These results allow us to hypothesize a mechanism of “trafficking” of antimicrobial peptides from the mother to the fetus that would help the fetus to protect itself from the infection in progress.

Small Noncoding RNA (sncRNA1) within the Latency-Associated Transcript Modulates Herpes Simplex Virus 1 Virulence and the Host Immune Response during Acute but Not Latent Infection

HSV-1 latency-associated transcript (LAT) plays a major role in establishing latency and reactivation; however, the mechanism by which LAT controls these processes is largely unknown. In this study, we sought to establish the role of the small noncoding RNA1 (sncRNA1) encoded within LAT during HSV-1 ocular infection. Our results suggest that sncRNA1 has a protective role during acute ocular infection by modulating the innate immune response to infection.

Probiotics and gut microbiota: mechanistic insights into gut immune homeostasis through TLR pathway regulation

Consumption of probiotics as a useful functional food improves the host's wellbeing, and, when paired with prebiotics (indigestible dietary fibre/carbohydrate), often benefits the host through anaerobic fermentation.

Candida albicans Modulates Murine and Human Beta Defensin-1 during Vaginitis

Vulvovaginal candidiasis (VVC) and recurrent vulvovaginal candidiasis (RVVC) are two forms of a disease caused by Candida spp. β-defensin (BD) is one of the most important families of antimicrobial peptides in the female genital tract and includes molecules that exert essential local functions as antimicrobial and PMN chemoattractant peptides. However, the information on their role during murine and human VVC and RVVC is limited. Thus, we analyzed the behavior and contribution of BD1 to the local response in a VVC mice model and the local cytokine profile and human BD1 and BD3 expression in cervicovaginal lavage from patients with VVC and RVVC. We demonstrated that, in patients with RVVC BD1, mRNA and protein expression were severely diminished and that the aspartate proteinase and lipase secreted by C. albicans are involved in that decrease. This study provides novel information about the pathogenesis of VVC and describes a highly efficient C. albicans escape strategy for perpetuating the infection; these results may contribute to the development of new or combined treatment approaches.

Dealing with MDR bacteria and biofilm in the post-antibiotic era: Application of antimicrobial peptides-based nano-formulation

The rapid development of multidrug-resistant (MDR) bacteria due to the improper and overuse of antibiotics and the ineffective performance of antibiotics against the difficult-to-treat biofilm-related infections (BRIs) have urgently called for alternative antimicrobial agents and strategies in combating bacterial infections. Antimicrobial peptides (AMPs), owing to their compelling antimicrobial activity against MDR bacteria and BRIs without causing bacteria resistance, have attracted extensive attention in the research field. With the development of nanomaterial-based drug delivery strategies, AMPs-based nano-formulations have significantly improved the therapeutic effects of AMPs by ameliorating their hydrolytic stability, half-life in vivo, and solubility as well as reducing the cytotoxicity and hemolysis, etc. This review has comprehensively summarized the application AMPs-based nano-formulation in various bacterial infections models, including bloodstream infections (specifically sepsis), pulmonary infections, chronic wound infections, gastrointestinal infections, among others. The design of the nanomaterial-based drug delivery systems and the therapeutic effects of the AMPs-based nano-formulations in literature have been categorized and in details discussed. Overall, this review provides insights into the advantages and disadvantages of the current developed AMPs-based nano-formulations in literature for the treatment of bacterial infections, bringing inspirations and suggestions for their future design in the way towards clinical translation.

Polyfunctionality of the CXCR4/CXCL12 axis in health and disease: Implications for therapeutic interventions in cancer and immune-mediated diseases

Historically the chemokine receptor CXCR4 and its canonical ligand CXCL12 are associated with the bone marrow niche and hematopoiesis. However, CXCL12 exhibits broad tissue expression including brain, thymus, heart, lung, liver, kidney, spleen, and bone marrow. CXCR4 can be considered as a node which is integrating and transducing inputs from a range of ligand-receptor interactions into a responsive and divergent network of intracellular signaling pathways that impact multiple cellular processes such as proliferation, migration, and stress resistance. Dysregulation of the CXCR4/CXCL12 axis and consequent fundamental cellular processes, are associated with a panoply of disease. This review frames the polyfunctionality of the receptor at a molecular, physiological, and pathophysiological levels. Transitioning our perspective of this axis from a single gene/protein:single function model to a polyfunctional signaling cascade highlights the potential for finer therapeutic intervention and cautions against a reductionist approach.

Expression and Functional Characterization of a Novel Antimicrobial Peptide: Human Beta-Defensin 118

Purpose

β-Defensin 118 (DEFB118) is a novel host defense peptide (HDP) identified in humans. To evaluate its potentials for future utilization, the DEFB118 gene was expressed in Escherichia coli (E. coli) and the recombinant protein was fully characterized.

Methods

The DEFB118 protein was obtained by heterologous expression using E. coli Rosetta (DE3). Antibacterial activity of DEFB118 was determined by using various bacterial strains. IPEC-J cells challenged by E. coli K88 were used to determine its influences on inflammatory responses.

Results

The E. coli transformants yielded more than 250 μg/mL DEFB118 protein after 4 h induction by 1.0 mM IPTG. The DEFB118 was estimated by SDS-PAGE to be 30 kDa, and MALDI-TOF analysis verified that it is a human β-defensin 118. Importantly, the DEFB118 showed antimicrobial activities against both Gram-negative bacteria (E. coli K88 and E. coli DH5α) and Gram-positive bacteria (S. aureus and B. subtilis), with a minimum inhibitory concentration (MIC) of 4 μg/mL. Hemolytic assays showed that DEFB118 had no detrimental impact on cell viability. Additionally, DEFB118 was found to elevate the viability of IPEC-J2 cells upon E. coli K88 challenge. Moreover, DEFB118 significantly decreased cell apoptosis in the late apoptosis phase and downregulated the expression of inflammatory cytokines such as IL-1β and TNF-α in IPEC-J2 cell exposure to E. coli K88.

Conclusions

These results suggested a novel function of the mammalian defensins, and the antibacterial and anti-inflammatory properties of DEFB118 may allow it as a potential substitute for conventionally used antibiotics or drugs.

A Novel Immunocompetent Mouse Model for Testing Antifungal Drugs Against Invasive Candida albicans Infection

Disseminated infection by Candida species represents a common, often life-threatening condition. Increased resistance to current antifungal drugs has led to an urgent need to develop new antifungal drugs to treat this pathogen. However, in vivo screening of candidate antifungal compounds requires large numbers of animals and using immunosuppressive agents to allow for fungal dissemination. To increase the efficiency of screening, to use fewer mice, and to remove the need for immunosuppressive agents, which may interfere with the drug candidates, we tested the potential for a novel approach using in vivo imaging of a fluorescent strain of Candida albicans, in a mouse strain deficient in the host defense peptide, murine β-defensin 1 (mBD-1). We developed a strain of C. albicans that expresses red fluorescent protein (RFP), which exhibits similar infectivity to the non-fluorescent parent strain. When this strain was injected into immunocompetent mBD-1-deficient mice, we observed a non-lethal disseminated infection. Further, we could quantify its dissemination in real time, and observe the activity of an antifungal peptide mimetic drug by in vivo imaging. This novel method will allow for the rapid in vivo screening of antifungal drugs, using fewer mice, and increase the efficiency of testing new antifungal agents.

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.

Antiviral Activities of Human Host Defense Peptides

Peptides with broad-spectrum antimicrobial activity are found widely expressed throughout nature. As they participate in a number of different aspects of innate immunity in mammals, they have been termed Host Defense Peptides (HDPs). Due to their common structural features, including an amphipathic structure and cationic charge, they have been widely shown to interact with and disrupt microbial membranes. Thus, it is not surprising that human HDPs have activity against enveloped viruses as well as bacteria and fungi. However, these peptides also exhibit activity against a wide range of non-enveloped viruses as well, acting at a number of different steps in viral infection. This review focuses on the activity of human host defense peptides, including alpha- and beta-defensins and the sole human cathelicidin, LL-37, against both enveloped and non-enveloped viruses. The broad spectrum of antiviral activity of these peptides, both in vitro and in vivo suggest that they play an important role in the innate antiviral defense against viral infections. Furthermore, the literature suggests that they may be developed into antiviral therapeutic agents.

Unusual interplay of contrasting selective pressures on β-defensin genes implicated in male fertility of the Buffalo (Bubalus bubalis)

BACKGROUND

The buffalo, despite its superior milk-producing ability, suffers from reproductive limitations that constrain its lifetime productivity. Male sub-fertility, manifested as low conception rates (CRs), is a major concern in buffaloes. The epididymal sperm surface-binding proteins which participate in the sperm surface remodelling (SSR) events affect the survival and performance of the spermatozoa in the female reproductive tract (FRT). A mutation in an epididymal secreted protein, beta-defensin 126 (DEFB-126/BD-126), a class-A beta-defensin (CA-BD), resulted in decreased CRs in human cohorts across the globe. To better understand the role of CA-BDs in buffalo reproduction, this study aimed to identify the BD genes for characterization of the selection pressure(s) acting on them, and to identify the most abundant CA-BD transcript in the buffalo male reproductive tract (MRT) for predicting its reproductive functional significance.

RESULTS

Despite the low protein sequence homology with their orthologs, the CA-BDs have maintained the molecular framework and the structural core vital to their biological functions. Their coding-sequences in ruminants revealed evidence of pervasive purifying and episodic diversifying selection pressures. The buffalo CA-BD genes were expressed in the major reproductive and non-reproductive tissues exhibiting spatial variations. The Buffalo BD-129 (BuBD-129) was the most abundant and the longest CA-BD in the distal-MRT segments and was predicted to be heavily O-glycosylated.

CONCLUSIONS

The maintenance of the structural core, despite the sequence divergence, indicated the conservation of the molecular functions of the CA-BDs. The expression of the buffalo CA-BDs in both the distal-MRT segments and non-reproductive tissues indicate the retention the primordial microbicidal activity, which was also predicted by in silico sequence analyses. However, the observed spatial variations in their expression across the MRT hint at their region-specific roles. Their comparison across mammalian species revealed a pattern in which the various CA-BDs appeared to follow dissimilar evolutionary paths. This pattern appears to maintain only the highly efficacious CA-BD alleles and diversify their functional repertoire in the ruminants. Our preliminary results and analyses indicated that BuBD-129 could be the functional ortholog of the primate DEFB-126. Further studies are warranted to assess its molecular functions to elucidate its role in immunity, reproduction and fertility.

Associations between Bovine β-Defensin 4 Genotypes and Production Traits of Polish Holstein-Friesian Dairy Cattle

Simple Summary

Mastitis negatively affects dairy cattle, causing inferior milk quality and premature animal culling, which leads to economic losses. Therefore, selection based on genetic markers (i.g., marker-assisted selection) should also include functional traits with low heritability, such as resistance to udder inflammation. Single nucleotide polymorphisms (SNPs) identified in genes involved in the immune system, such as defensins with antibacterial properties, could be valuable markers. We chose two SNPs within the bovine neutrophil beta-defensin 4 (BNBD4) gene analyzed in a previous study related to milk production and udder health. Since these SNPs are located very close to each other in the gene intron, it is useful to analyze their association with production traits as a combined genotype. The results showed that these genotypes are indeed associated with productivity, as well as functional traits (milk, fat, and protein yields, fat, protein, lactose, and dry matter contents, and somatic cell count). The differences between the results based on the phenotypic data and the breeding values of studied traits may confirm the results of simulation studies that indicate a high rate of false-positives in genome-wide association study (GWAS) based on classically calculated estimated breeding values (EBVs) using best linear unbiased prediction (BLUP) methodology.

Abstract

This study analyzed the associations between two single-nucleotide polymorphisms (C2239T and A1674C), used together as a genotype located in BNBD4, and milk traits and breeding values of productivity traits of Polish Holstein-Friesian dairy cows. The research was carried out on 322 cows, with 7070 milk parameter and somatic cell count records in daily milking, as well as 897 records covering data on whole lactations, and 2209 breeding value records for productivity traits. The DMU statistical package with a one-trait repeatability test-day animal model was used to estimate the associations. The differences between the genotype effects were analyzed using Duncan’s post-hoc tests. The CC/AA and CT/AC genotypes had the highest frequencies (0.62 and 0.23, respectively). For use in marker-assisted selection, the CC/AC genotype is the most promising as an indicator of high-yielding cows potentially resistant to mastitis, because it was associated with the lowest somatic cell count (SCC), highest milk, fat, and protein yields in daily milking, as well as with milk yield in the whole lactation. The studied genotypes were also related to the breeding values of all the investigated production traits. However, some simulation studies have indicated a high rate of false-positives in GWAS based on classically calculated EBVs.

Integrated Transcriptomic and Proteomic Analysis of Red Blood Cells from Rainbow Trout Challenged with VHSV Point Towards Novel Immunomodulant Targets

Teleost red blood cells (RBCs) are nucleated and therefore can propagate cellular responses to exogenous stimuli. RBCs can mount an immune response against a variety of fish viruses, including the viral septicemia hemorrhagic virus (VHSV), which is one of the most prevalent fish viruses resulting in aquaculture losses. In this work, RBCs from blood and head kidney samples of rainbow trout challenged with VHSV were analyzed via transcriptomic and proteomic analyses. We detected an overrepresentation of differentially expressed genes (DEGs) related to the type I interferon response and signaling in RBCs from the head kidney and related to complement activation in RBCs from blood. Antigen processing and presentation of peptide antigen was overrepresented in RBCs from both tissues. DEGs shared by both tissues showed an opposite expression profile. In summary, this work has demonstrated that teleost RBCs can modulate the immune response during an in vivo viral infection, thus implicating RBCs as cell targets for the development of novel immunomodulants.

β-Defensins Coordinate In Vivo to Inhibit Bacterial Infections of the Trachea

β-defensins are predicted to play an important role in innate immunity against bacterial infections in the airway. We previously observed that a type III-secretion product of Bordetella bronchiseptica inhibits the NF-κB-mediated induction of a β-defensin in airway epithelial cells in vitro. To confirm this in vivo and to examine the relative roles of other β-defensins in the airway, we infected wild-type C57BL/6 mice and mice with a deletion of the mBD-1 gene with B. bronchiseptica wild-type strain, RB50 and its mutant strain lacking the type III-secretion system, WD3. The bacteria were quantified in the trachea and the nasal tissue and mRNA levels of mouse β-defensin-3 (mBD-3) were assessed after 24 h. Infection with the wild-type bacterial strain resulted in lower mBD-3 mRNA levels in the trachea than in mice infected with the type III-deficient strain. Furthermore, we observed an increase in bacterial numbers of RB50 only in the tracheas of mBD-1-deficient mice. Neutrophils were also more abundant on the trachea in RB50 infected WT mice but not in the bronchiolar lavage fluid (BAL), compared with WD3 infected WT and mBD-1^−/− mice, indicating that the coordination of β-defensin chemotactic effects may be confined to tracheal epithelial cells (TEC). RB50 decreased the ability of mice to mount an early specific antibody response, seven days after infection in both WT and mBD-1^−/− mice but there were no differences in titers between RB50-infected WT and mBD-1^−/− mice or between WD3-infected WT and mBD-1^−/− mice, indicating mBD-1 was not involved in induction of the humoral immune response to the B. bronchiseptica. Challenge of primary mouse TEC in vitro with RB50 and WD3, along with IL-1β, further corroborated the in vivo studies. The results demonstrate that at least two β-defensins can coordinate early in an infection to limit the growth of bacteria in the trachea.

LL-37 disrupts the Kaposi's sarcoma-associated herpesvirus envelope and inhibits infection in oral epithelial cells

Oral epithelial cells (OECs) represent the first line of defense against viruses that are spread via saliva, including Kaposi's sarcoma-associated herpesvirus (KSHV). Infection of humans by KSHV and viral pathogenesis begins by infecting OECs. One method OECs use to limit viral infections in the oral cavity is the production of antimicrobial peptides (AMPs), or host defense peptides (HDPs). However, no studies have investigated the antiviral activities of any HDP against KSHV. The goal of this study was to determine the antiviral activity of one HDP, LL-37, against KSHV in the context of infecting OECs. Our results show that LL-37 significantly decreased KSHV's ability to infect OECs in both a structure- and dose-dependent manner. However, this activity does not stem from affecting OECs, but instead the virions themselves. We found that LL-37 exerts its antiviral activity against KSHV by disrupting the viral envelope, which can inhibit viral entry into OECs. Our data suggest that LL-37 exhibits a marked antiviral activity against KSHV during infection of oral epithelial cells, which can play an important role in host defense against oral KSHV infection. Thus, we propose that inducing LL-37 expression endogenously in oral epithelial cells, or potentially introducing as a therapy, may help restrict oral KSHV infection and ultimately KSHV-associated diseases.

DEFB1 polymorphisms and HIV-1 mother-to-child transmission in Zambian population

Introduction: Human Beta Defensin-1 (hBD-1) is a component of the innate immune system, the first line of defence against pathogens, already reported as involved in the susceptibility to HIV-1 infection and HIV-1 mother-to-child transmission (MTCT) in different populations. We investigated the role of DEFB1 gene (encoding for hBD-1) functional polymorphisms in the susceptibility to HIV-1 MTCT in a population from Zambia. Methods: Four selected polymorphisms within DEFB1 gene, three at the 5' untranslated region (UTR), namely -52G > A (rs1799946), -44C > G (rs1800972) and -20G > A (rs11362) and one in the 3'UTR, c.*87A > G (rs1800972), were genotyped in 101 HIV-1 positive mothers (26 transmitters -27% and 75 not transmitters -73%) and 331 infants born to HIV-1 infected mothers (85 HIV-1 positive -26% and 246 exposed but not infected -74%). Results: DEFB1 c.*87-A allele was more frequent among HIV- children with respect to HIV+ (with intrauterine MTCT). Concerning DEFB1 haplotypes, GCGA haplotype resulted more represented in HIV- than HIV+ infants and DEFB1 ACGG haplotype presented increased frequency in HIV- children respect to HIV+ (with intra-partum MTCT) (p = .02, p = .002 and p = .006, respectively). Conclusions: DEFB1 polymorphisms were significantly associated with decreased risk of HIV-1 infection acquisition in the studied Zambian population suggesting that they may play a role in HIV-1 MTCT.