[beta]-defensins in lung host defense

Deficient human β-defensin 1 underlies male infertility associated with poor sperm motility and genital tract infection

Genital tract infection and reduced sperm motility are considered two pivotal etiological factors for male infertility associated with leukocytospermia and asthenozoospermia, respectively. We demonstrate that the amount of human β-defensin 1 (DEFB1) in sperm from infertile men exhibiting either leukocytospermia or asthenozoospermia, both of which are associated with reduced motility and reduced bactericidal activity in sperm, is much lower compared to that in normal fertile sperm. Interference with DEFB1 function also decreases both motility and bactericidal activity in normal sperm, whereas treatment with recombinant DEFB1 markedly restores DEFB1 expression, bactericidal activity, sperm quality, and egg-penetrating ability in sperm from both asthenozoospermia and leukocytospermia patients. DEFB1 interacts with chemokine receptor type 6 (CCR6) in sperm and triggers Ca(2+) mobilization, which is important for sperm motility. Interference with CCR6 function also reduces motility and bactericidal activity of normal sperm. The present finding explains a common defect in male infertility associated with both asthenozoospermia and leukocytospermia, indicating a dual role of DEFB1 in defending male fertility. These results also suggest that the expression of DEFB1 and CCR6 may have diagnostic potential and that treatment of defective sperm with recombinant DEFB1 protein may be a feasible therapeutic approach for male infertility associated with poor sperm motility and genital tract infection.

Exposure to Cigarette Smoke Disrupts CCL20-Mediated Antimicrobial Activity in Respiratory Epithelial Cells

Cigarette smoke (CS) exposure is known to increase infection rates, but the mechanisms are not well understood. These studies tested the hypothesis that CS exposure would impair antimicrobial activity of apical conditioned media from human airway (BEAS-2B) cultures by reducing induction and release of the antimicrobial peptide CCL20. BEAS-2B cultures were exposed to CS extract and assayed for temporal and physical characteristics of release as well as for antimicrobial activity. E. coli were exposed to Beas-2B-conditioned media (BCM) and subsequent bacterial colonies were enumerated. In time course studies TLR-agonist-induced CCL20 transcription and release were rapid, of short duration and release was consistently targeted to the apical/luminal compartment. Cells treated with CS extract had diminished release of CCL20 under both constitutive and toll-like receptor (TLR) agonist stimulating conditions. Exposure of the cells to CS significantly reduced the antimicrobial activity in BCM and neutralizing antibodies to CCL20 brought antibacterial activity back to baseline levels demonstrating that antimicrobial activity in this culture system was primarily attributable to CCL20. These studies add to the understanding of CCL20 as a mucosal antimicrobial and improve insight into a likely mechanism linking infection to CS exposure.

Bovine β-defensin gene family: opportunities to improve animal health?

Recent analysis of the bovine genome revealed an expanded suite of β-defensin genes that encode what are referred to as antimicrobial or host defense peptides (HDPs). Whereas primate genomes also encode α- and θ-defensins, the bovine genome contains only the β-defensin subfamily of HDPs. β-Defensins perform diverse functions that are critical to protection against pathogens but also in regulation of the immune response and reproduction. As the most comprehensively studied subclass of HDPs, β-defensins possess the widest taxonomic distribution, found in invertebrates as well as plants, indicating an ancient point of origin. Cross-species comparison of the genomic arrangement of β-defensin gene repertoire revealed them to vary in number among species presumably due to differences in pathogenic selective pressures but also genetic drift. β-Defensin genes exist in a single cluster in birds, but four gene clusters exist in dog, rat, mouse, and cow. In humans and chimpanzees, one of these clusters is split in two as a result of a primate-specific pericentric inversion producing five gene clusters. A cluster of β-defensin genes on bovine chromosome 13 has been recently characterized, and full genome sequencing has identified extensive gene copy number variation on chromosome 27. As a result, cattle have the most diverse repertoire of β-defensin genes so far identified, where four clusters contain at least 57 genes. This expansion of β-defensin HDPs may hold significant potential for combating infectious diseases and provides opportunities to harness their immunological and reproductive functions in commercial cattle populations.

Lung epithelial cells are essential effectors of inducible resistance to pneumonia

Infectious pneumonias are the leading cause of death worldwide, particularly among immunocompromised patients. Therapeutic stimulation of the lungs' intrinsic defenses with a unique combination of inhaled Toll-like receptor (TLR) agonists broadly protects mice against otherwise lethal pneumonias. As the survival benefit persists despite cytotoxic chemotherapy-related neutropenia, the cells required for protection were investigated. The inducibility of resistance was tested in mice with deficiencies of leukocyte lineages due to genetic deletions and in wild-type mice with leukocyte populations significantly reduced by antibodies or toxins. Surprisingly, these serial reductions in leukocyte lineages did not appreciably impair inducible resistance, but targeted disruption of TLR signaling in the lung epithelium resulted in complete abrogation of the protective effect. Isolated lung epithelial cells were also induced to kill pathogens in the absence of leukocytes. Proteomic and gene expression analyses of isolated epithelial cells and whole lungs revealed highly congruent antimicrobial responses. Taken together, these data indicate that lung epithelial cells are necessary and sufficient effectors of inducible resistance. These findings challenge conventional paradigms about the role of epithelia in antimicrobial defense and offer a novel potential intervention to protect patients with impaired leukocyte-mediated immunity from fatal pneumonias.

Role of defensins in the pathogenesis of chronic lung allograft rejection

Chronic rejection predominantly manifested as bronchiolitis obliterans syndrome (BOS), still remains a major problem affecting long-term outcomes in human lung transplantation (LTx). Donor specific antibodies (DSA) and infiltration of neutrophils in the graft have been associated with the development of BOS. This study determines the role of defensins, produced by neutrophils, and its interaction with α-1-antitrypsin (AAT) towards induction of airway inflammation and fibrosis which are characteristic hallmarks of BOS. Bronchoalveolar lavage (BAL) and serum from LTx recipients, BOS+ (n=28), BOS- (n=26) and normal healthy controls (n=24) were analyzed. Our results show that BOS+ LTx recipients had higher α-defensins (HNP1-3) and β-defensin2 HBD2 concentration in BAL and serum compared to BOS-DSA-recipients and normal controls (p=0.03). BOS+ patients had significantly lower serum AAT along with higher circulating concentration of HNP-AAT complexes in BAL (p=0.05). Stimulation of primary small airway epithelial cells (SAECs) with HNPs induced expression of HBD2, adhesion molecules (ICAM and VCAM), cytokines (IL-6, IL-1β, IL-13, IL-8 and MCP-1) and growth-factor (VEGF and EGF). In contrast, anti-inflammatory cytokine, IL-10 expression decreased 2-fold (p=0.002). HNPs mediated SAEC activation was completely abrogated by AAT. In conclusion, our results demonstrates that neutrophil secretory product, α-defensins, stimulate β-defensin production by SAECs causing upregulation of pro-inflammatory and pro-fibrotic signaling molecules. Hence, chronic stimulation of airway epithelial cells by defensins can lead to inflammation and fibrosis the central events in the development of BOS following LTx.

[Regeneration of airway epithelium]

INTRODUCTION

Epithelial regeneration is a complex process. It can lead to the remodeling of the airway epithelium as in asthma, COPD or cystic fibrosis.

BACKGROUND

The development of in vivo and in vitro models has allowed the analysis of remodeling mechanisms and showed the role of components of extracellular matrix, proteases, cytokines and growth factors. Airway epithelial progenitors and stems cells have been studied in these models. However, their identification remains difficult.

CONCLUSION

Identification and characterization of airway epithelial progenitor/stem-cells, and a better knowledge of the regeneration process may allow the development of new therapeutic strategies for airway epithelial reconstitution.

Response of Differentiated Human Airway Epithelia to Alcohol Exposure and Klebsiella Pneumoniae Challenge

Alcohol abuse has been associated with increased susceptibility to pulmonary infection. It is not fully defined how alcohol contributes to the host defense compromise. Here primary human airway epithelial cells were cultured at an air-liquid interface to form a differentiated and polarized epithelium. This unique culture model allowed us to closely mimic lung infection in the context of alcohol abuse by basolateral alcohol exposure and apical live bacterial challenge. Application of clinically relevant concentrations of alcohol for 24 hours did not significantly alter epithelial integrity or barrier function. When apically challenged with viable Klebsiella pneumoniae, the cultured epithelia had an enhanced tightness which was unaffected by alcohol. Further, alcohol enhanced apical bacterial growth, but not bacterial binding to the cells. The cultured epithelium in the absence of any treatment or stimulation had a base-level IL-6 and IL-8 secretion. Apical bacterial challenge significantly elevated the basolateral secretion of inflammatory cytokines including IL-2, IL-4, IL-6, IL-8, IFN-γ, GM-CSF, and TNF-α. However, alcohol suppressed the observed cytokine burst in response to infection. Addition of adenosine receptor agonists negated the suppression of IL-6 and TNF-α. Thus, acute alcohol alters the epithelial cytokine response to infection, which can be partially mitigated by adenosine receptor agonists.

Recent advances in the field of antimicrobial peptides in inflammatory diseases

Antimicrobial peptides are cationic molecules, which participate in multiple aspects of the immune response including the control of inflammatory diseases, characteristic that make these molecules attractive as therapeutic tools. These peptides are produced in bacteria, insects, plants and vertebrates, and are classified together due to their capacity to directly inhibit the growth of microorganisms, and to regulate the immune response by inducing the secretion of chemokines and cytokines. Various families of antimicrobial peptides have been identified including the cathelicidins and defensins, the most investigated human antimicrobial peptides. This review will cover the main biological functions of antimicrobial and cell-penetrating peptides in inflammation, and describe the importance and utility of antimicrobial peptides as therapeutics for inflammatory diseases.

The Innate Immune System of the Perinatal Lung and Responses to Respiratory Syncytial Virus Infection

The response of the preterm and newborn lung to airborne pathogens, particles, and other insults is initially dependent on innate immune responses since adaptive responses may not fully mature and require weeks for sufficient responses to antigenic stimuli. Foreign material and microbial agents trigger soluble, cell surface, and cytoplasmic receptors that activate signaling cascades that invoke release of surfactant proteins, defensins, interferons, lactoferrin, oxidative products, and other innate immune substances that have antimicrobial activity, which can also influence adaptive responses. For viral infections such as respiratory syncytial virus (RSV), the pulmonary innate immune responses has an essential role in defense as there are no fully effective vaccines or therapies for RSV infections of humans and reinfections are common. Understanding the innate immune response by the preterm and newborn lung may lead to preventive strategies and more effective therapeutic regimens.

Copy number variation of the antimicrobial-gene, defensin beta 4, is associated with susceptibility to cervical cancer

The aim of this study was to investigate association between copy number variation of the defensin beta 4 gene (DEFB4) and susceptibility to cervical cancer in a population at high risk of persistent oncogenic human papillomavirus (HPV) infection. The study subjects comprised 204 women with cervical cancer, a population having a high risk of persistent oncogenic HPV infection (cervical cancer group), and 200 healthy women from the general population (control group). Copy number variation of DEFB4 in each test sample was determined by relative quantitation using the comparative CT ((ΔΔ)CT) method. Differences between the two groups were evaluated. The median DEFB4 copy number in the cervical cancer group was four and in the control group was five (P=2.77e-4, t-test). The odds ratio of cervical cancer in individuals with four DEFB4 copies or less was higher (odds ratio 2.02; 95% confidence interval odds ratio 1.36-3.02), compared with that in individuals with five or more copies (odds ratio 0.49; 95% confidence interval odds ratio 0.33-0.74). We found copy number variation of DEFB4 was a host genetic factor conferring susceptibility to cervical cancer. A lower DEFB4 copy number was associated with susceptibility to cervical cancer.

Pulmonary innate immunity in children with protracted bacterial bronchitis

OBJECTIVE

To determine bronchoalveolar lavage (BAL) levels of 3 innate immunity components (human β-defensin-2 [hBD2], mannose-binding lectin [MBL], and surfactant protein-A [SP-A]), the relationship with airway neutrophilia and infection, and cytokine production of stimulated BAL cells in children with current protracted bacterial bronchitis (PBB), children with resolved PBB (PBB well), and controls.

STUDY DESIGN

BAL of 102 children (mean age 2.8 years) fulfilling predefined criteria of current PBB (n = 61), PBB well (n = 20), and controls (n = 21) was cultured (quantitative bacteriology) and viruses examined by polymerase chain reaction. hBD2, MBL, and SP-A were measured, and cytokine production by lipopolysaccharide-stimulated BAL cells was determined.

RESULTS

Median hBD2 and MBL levels were significantly higher in the current PBB group (hBD2 = 164.4, IQR 0-435.5 pg/mL; MBL = 1.7, 0.4-4 ng/mL) than in the PBB well group (hBD2 = 0, IQR 0-85.2; MBL = 0.6, IQR 0.03-2.9) and controls (hBD2 = 3.6, IQR 0-126; MBL = 0.4, IQR 0.02-79). hBD2 was significantly higher in children with airway infection (n = 54; median 76.9, IQR 0-397.3) compared with those without (n = 48; 0, IQR 0-236.3), P= .04. SP-A levels and cytokine production of stimulated BAL cells were similar between groups.

CONCLUSION

In children's airways, hBD2, but not MBL and SP-A, relates to inflammation and infection. In children with PBB, mechanisms involving airway hBD2 and MBL are augmented. These pulmonary innate immunity components and the ability of BAL cells to respond to stimuli are unlikely to be deficient.

Modulation of ovine SBD-1 expression by 17beta-estradiol in ovine oviduct epithelial cells

Background

Mucosal epithelia, including those of the oviduct, secrete antimicrobial innate immune molecules (AIIMS). These have bactericidal/bacteriostatic functions against a variety of pathogens. Among the AIIMs, sheep β-defensin-1 (SBD-1) is one of the most potent. Even though the SBD-1 is an important AIIM and it is regulated closely by estrogenic hormone, the regulation mechanism of 17β-estradiol has not been clearly established. We investigated the effects of E₂ and agonist or inhibitor on ovine oviduct epithelial cells in regard to SBD-1 expression using reverse transcription quantitative PCR (RT-qPCR). In addition, three different pathways were inhibited separately or simultaneously to confirm the effect of different inhibitors in the regulation mechanism.

Results

17beta-estradiol (E₂) induced release of SBD-1 in ovine oviduct epithelial cells. SBD-1 expression was mediated through G-protein-coupled receptor 30 (GPR30) and Estrogen Receptors (ERs) activation in ovine oviduct epithelial cell. Inhibition of gene expression of protein kinase A (PKA), protein kinase C (PKC), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) led to a decreased SBD-1 expression.

Conclusions

Taken together, E₂-induced up-regulation of SBD-1 expressions were GPR30-dependent during prophase and ERs-dependent during later-stage in ovine oviduct epithelial cells, and we assume that the effect was completed by the PKA, PKC, and NF-κB pathways simultaneous.

Epithelial antimicrobial defence of the skin and intestine

Surface tissues of the body such as the skin and intestinal tract are in direct contact with the external environment and are thus continuously exposed to large numbers of microorganisms. To cope with the substantial microbial exposure, epithelial surfaces produce a diverse arsenal of antimicrobial proteins that directly kill or inhibit the growth of microorganisms. In this Review, we highlight new advances in our understanding of how epithelial antimicrobial proteins protect against pathogens and contribute to microbiota-host homeostasis at the skin and gut mucosae. Further, we discuss recent insights into the regulatory mechanisms that control antimicrobial protein expression. Finally, we consider how impaired antimicrobial protein expression and function can contribute to disease.

Suppression of adenosine-activated chloride transport by ethanol in airway epithelia

Alcohol abuse is associated with increased lung infections. Molecular understanding of the underlying mechanisms is not complete. Airway epithelial ion transport regulates the homeostasis of airway surface liquid, essential for airway mucosal immunity and lung host defense. Here, air-liquid interface cultures of Calu-3 epithelial cells were basolaterally exposed to physiologically relevant concentrations of ethanol (0, 25, 50 and 100 mM) for 24 hours and adenosine-stimulated ion transport was measured by Ussing chamber. The ethanol exposure reduced the epithelial short-circuit currents (I(SC)) in a dose-dependent manner. The ion currents activated by adenosine were chloride conductance mediated by cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-activated chloride channel. Alloxazine, a specific inhibitor for A(2B) adenosine receptor (A(2B)AR), largely abolished the adenosine-stimulated chloride transport, suggesting that A(2B)AR is a major receptor responsible for regulating the chloride transport of the cells. Ethanol significantly reduced intracellular cAMP production upon adenosine stimulation. Moreover, ethanol-suppression of the chloride secretion was able to be restored by cAMP analogs or by inhibitors to block cAMP degradation. These results imply that ethanol exposure dysregulates CFTR-mediated chloride transport in airways by suppression of adenosine-A(2B)AR-cAMP signaling pathway, which might contribute to alcohol-associated lung infections.

The potential of antimicrobial peptides as biocides

Antimicrobial peptides constitute a diverse class of naturally occurring antimicrobial molecules which have activity against a wide range of pathogenic microorganisms. Antimicrobial peptides are exciting leads in the development of novel biocidal agents at a time when classical antibiotics are under intense pressure from emerging resistance, and the global industry in antibiotic research and development stagnates. This review will examine the potential of antimicrobial peptides, both natural and synthetic, as novel biocidal agents in the battle against multi-drug resistant pathogen infections.

A new Beta defensin from sika deer: molecular cloning and sequence characterization

The beta-defensins are small, well-characterized peptides with broad antimicrobial activities. Here we report the identification of a novel β-defensin, sika deer β-defensin-1 (siBD-1), from sika deer tissues with a pair of PCR primers according to the conserved cDNA sequences of known ruminant β-defensins. Total RNA was extracted from the tongue epithelia of a sika deer and the 418 bp cDNA encoding siBD-1 was amplified by the reverse transcription PCR (RT-PCR), 5'- and 3'-RACE. The cDNA contained an open reading frame (ORF) of 192 bases which encoded a 64 amino acid prepro-peptide. The prepro-peptide contained six invariantly spaced cysteine residues, which is the β defensin consensus sequence. The putative mature peptide of the siBD-1 contained nine positively charged residues (5 arginine-R, 3 lysine-K, and 1 histidine-H). The sequence homology shows that siBD-1 has 73.0-90.6% amino-acid identity and 74.6-90.6% cDNA identity with other ruminant beta-defensins, sharing the greatest identity with buffalo enteric β-defensin in both amino acid and nucleotide sequences.

The airway epithelium: soldier in the fight against respiratory viruses

The airway epithelium acts as a frontline defense against respiratory viruses, not only as a physical barrier and through the mucociliary apparatus but also through its immunological functions. It initiates multiple innate and adaptive immune mechanisms which are crucial for efficient antiviral responses. The interaction between respiratory viruses and airway epithelial cells results in production of antiviral substances, including type I and III interferons, lactoferrin, β-defensins, and nitric oxide, and also in production of cytokines and chemokines, which recruit inflammatory cells and influence adaptive immunity. These defense mechanisms usually result in rapid virus clearance. However, respiratory viruses elaborate strategies to evade antiviral mechanisms and immune responses. They may disrupt epithelial integrity through cytotoxic effects, increasing paracellular permeability and damaging epithelial repair mechanisms. In addition, they can interfere with immune responses by blocking interferon pathways and by subverting protective inflammatory responses toward detrimental ones. Finally, by inducing overt mucus secretion and mucostasis and by paving the way for bacterial infections, they favor lung damage and further impair host antiviral mechanisms.

Synergistic interactions of TLR2/6 and TLR9 induce a high level of resistance to lung infection in mice

Infectious pneumonias exact an unacceptable mortality burden worldwide. Efforts to protect populations from pneumonia have focused historically on antibiotic development and vaccine-enhanced adaptive immunity. However, we have reported recently that the lungs' innate defenses can be induced therapeutically by inhalation of a bacterial lysate that protects mice against otherwise lethal pneumonia. In this study, we tested in mice the hypothesis that TLRs are required for this antimicrobial phenomenon and found that resistance could not be induced in the absence of the TLR signaling adaptor protein MyD88. We then attempted to recapitulate the protection afforded by the bacterial lysate by stimulating the lung epithelium with aerosolized synthetic TLR ligands. Although most single or combination treatments yielded no protection, simultaneous treatment with ligands for TLR2/6 and TLR9 conferred robust, synergistic protection against virulent gram-positive and gram-negative pathogens. Protection was associated with rapid pathogen killing in the lungs, and pathogen killing could be induced from lung epithelial cells in isolation. Taken together, these data demonstrate the requirement for TLRs in inducible resistance against pneumonia, reveal a remarkable, unanticipated synergistic interaction of TLR2/6 and TLR9, reinforce the emerging evidence supporting the antimicrobial capacity of the lung epithelium, and may provide the basis for a novel clinical therapeutic that can protect patients against pneumonia during periods of peak vulnerability.

Suppression of interleukin (IL)-8 and human beta defensin-2 secretion in LPS-and/or IL-1β-stimulated airway epithelial A549 cells by a herbal formulation against respiratory infections (BNO 1030)

AIM OF THE STUDY

A special ethanolic-aqueous extract from seven traditional medicinal plants (BNO 1030) has been used for several decades to treat recurrent infections of the respiratory tract. Considering the potential role of interleukin-8 (IL-8) and human beta defensin-2 (hBD-2) in inflammation, we investigated the effect of BNO 1030 on lipopolysaccharide (LPS) from Pseudomonas aeruginosa or IL-1β-induced inflammatory mediators in A549 human type II alveolar epithelial cells.

MATERIALS AND METHODS

A549 cells were stimulated with LPS (100 μg/ml) or IL-1β (50 ng/ml) in the presence of the preparation and the secretion of IL-8 and hBD-2 were measured after 18 h and 24h in cell free supernatants using enzyme-linked immunosorbent assays (ELISA). Cell viability and cell growth was investigated by propidium iodide uptake and WST-1 assay, respectively.

RESULTS

BNO 1030 inhibited the secretion of IL-8 and hBD-2 at non-cytotoxic concentrations (0.1-100 μg/ml; cell growth inhibitory concentration, 50% (IC(50))=678 ± 87.6 μg/ml). Stimulation by IL-1β led to a 7-fold activation of IL-8 secretion, which was reduced by 37.7 ± 4.1% (p<0.05) after incubation with 100 μg/ml BNO 1030. Inducible hBD-2 was suppressed by 91.8 ± 15.6% (p<0.01) at the same concentration of BNO 1030 (IC(50)=0.7 ± 0.1 μg/ml). The 2-fold increase of IL-8 secretion by LPS-stimulated cells was completely abolished at concentration of 50 μg/ml BNO 1030 (IC(50)=5.7±3.6 μg/ml).

CONCLUSION

BNO 1030 suppressed the secretion of IL-8 and hBD-2 in cultured epithelial A549 cells. These results support its use as a phytotherapeutic product prepared from traditional remedies in inflammatory diseases, especially those affecting the respiratory tract.

Defensins in innate immunity

The innate immune system is the first line of defense against many common microorganisms, which can initiate adaptive immune responses to provide increased protection against subsequent re-infection by the same pathogen. As a major family of antimicrobial peptides, defensins are widely expressed in a variety of epithelial cells and sometimes in leukocytes, playing an important role in the innate immune system due to their antimicrobial, chemotactic and regulatory activities. This review introduces their structure, classification, distribution, synthesis, and focuses on their biological activities and mechanisms, as well as clinical relevance. These studies of defensins in the innate immune system have implications for the prevention and treatment of a variety of infectious diseases, including bacterial ocular disease.

Synergistic effect of antibodies to human leukocyte antigens and defensins in pathogenesis of bronchiolitis obliterans syndrome after human lung transplantation

BACKGROUND

This study aims to determine the role of antibodies to donor-mismatched human leukocyte antigen (HLA) developed during the post-transplant period in inducing defensins and their synergistic role in the pathogenesis of chronic rejection, bronchiolitis obliterans syndrome (BOS), after human lung transplantation (LTx).

METHODS

Bronchoalveolar lavage (BAL) and serum from 21 BOS+ LTx patients were assayed for β-defensins human neutrophil peptides (HNP) 1-3 (enzyme-linked immunosorbent assay [ELISA]) and anti-HLA antibodies (Luminex, Luminex Corp, Austin, TX). Human airway epithelial cells (AEC) were treated with anti-HLA antibodies, HNP-1/2, or both, and the levels of β-defensin were measured by ELISA. Using a mouse model of obliterative airway disease induced by anti-major histocompatibility (MHC) class-I antibodies, we quantitatively and qualitatively determined neutrophil infiltration by myeloperoxidase (MPO) staining and activity by MPO assay, and defensin levels in the BAL.

RESULTS

In human LTx patients, higher defensin levels correlated with presence of circulating anti-HLA antibodies (p < 0.05). AEC treated with anti-HLA antibodies or HNP-1/2, produced β-defensin with synergistic effects in combination (612 ± 06 vs 520 ± 23 pg/ml anti-HLA antibody, or 590 ± 10 pg/ml for HNP treatment; p < 0.05). Neutrophil numbers (6-fold) and activity (5.5-fold) were higher in the lungs of mice treated with anti-MHC antibodies vs control. A 2-fold increase in α-defensin and β-defensin levels was also present in BAL on Day 5 after anti-MHC administrations.

CONCLUSIONS

Anti-HLA antibodies developed during the post-transplant period and α-defensins stimulated β-defensin production by epithelial cells, leading to increased cellular infiltration and inflammation. Chronic stimulation of epithelium by antibodies to MHC and resulting increased levels of defensins induce growth factor production and epithelial proliferation contributing to the development of chronic rejection after LTx.

Cytokine networks in the infected lung

The generation of an innate immune response is essential for rapid clearance of microbes from the respiratory tract, whereas acquired immunity is required for the generation of cellular immunity necessary for the killing of certain intracellular pathogens and the development of immunological memory. Cytokines play an integral role in host defense by serving as leukocyte chemoattractants, leukocyte-activating factors or afferent signals in the induction or regulation of other effector molecules. This review assesses the contribution of cytokine networks to the generation of antimicrobial host defenses in the lung, with an emphasis on cytokines/cytokine networks that are instrumental in innate antibacterial responses, including mucosal immunity, and also introduces networks that instruct the development of adaptive immunity.

Inducible innate resistance of lung epithelium to infection

Most studies of innate immunity have focused on leukocytes such as neutrophils, macrophages, and natural killer cells. However, epithelial cells play key roles in innate defenses that include providing a mechanical barrier to microbial entry, signaling to leukocytes, and directly killing pathogens. Importantly, all these defenses are highly inducible in response to the sensing of microbial and host products. In healthy lungs, the level of innate immune epithelial function is low at baseline. This is indicated by low levels of spontaneous microbial killing and cytokine release, reflecting low constitutive stimulation in the nearly sterile lower respiratory tract when mucociliary clearance mechanisms are functioning effectively. This contrasts with the colon, where bacteria are continuously present and epithelial cells are constitutively activated. Although the surface area of the lungs presents a large target for microbial invasion, activated lung epithelial cells that are closely apposed to deposited pathogens are ideally positioned for microbial killing.

Association of higher DEFB4 genomic copy number with Crohn's disease

OBJECTIVES

Human beta-defensin 2 (hBD-2 or DEFB4) is a highly inducible, antimicrobial peptide, which may have an important role in the innate immune response at epithelial surfaces. Genomic copy number of DEFB4 is polymorphic, with most individuals possessing 3-5 copies. Increased DEFB4 copy number is a susceptibility factor for psoriasis, whereas a single study in a Crohn's disease (CD) cohort reported that decreased DEFB4 copy number is associated with colonic inflammation. Here, we analyze association of DEFB4 copy number with CD in a New Zealand case-control cohort of European origin.

METHODS

DEFB4 gene copy number was determined using TaqMan quantitative PCR in 466 CD patients and 329 controls. DNA samples, independently genotyped for DEFB4 copy number by alternative methods, were used to validate the assay.

RESULTS

Increased DEFB4 genomic copy number was seen in CD patients compared with controls. Individuals with >4 copies had a significantly higher risk of developing CD than those with <4 copies (odds ratio 1.54; 95% confidence interval 1.13-2.09, P=5e-05). DEFB4 genomic copy number did not differ by disease location within the CD cohort (P=0.948), nor did analysis of CD patients who had undergone surgery detect association of decreased DEFB4 genomic copy number (<4) in colonic CD compared with ileal CD (P=0.120).

CONCLUSIONS

Our results indicate that elevated DEFB4 copy number is a risk factor for CD (irrespective of intestinal location), and challenge previous data supporting positive association of lower DEFB4 genomic copy number with colonic CD.

Staphylococcus aureus nasal carriage and its contributing factors

Staphylococcus aureus is a medically important pathogen that is often acquired from hospital settings (nosocomial) as well as from the community (community acquired). Bacteria that reside in anterior nares of hosts serve as reservoirs for both the spread of the pathogen and predispose the host to subsequent infections. Here, we will review the extent and variability of nasal carriage, and the possible causative factors--both from the host and the bacterium. We also discuss the existing molecular typing techniques used for studying variations among strains of S. aureus. Finally, we discuss the possible areas of studies that are open in this field. Given the pathogen's importance in healthcare setting, such areas of study vary vastly, from fundamental research to applied medical care and use of alternative medical regimes for control of S. aureus nasal carriage. Unsurprisingly, our conclusions also underscore the importance of making policy decisions based on local ethnic and socioeconomic population structure.

Elevated expression of Paneth cell CRS4C in ileitis-prone SAMP1/YitFc mice: regional distribution, subcellular localization, and mechanism of action

Paneth cells at the base of small intestinal crypts of Lieberkühn secrete host defense peptides and proteins, including alpha-defensins, as mediators of innate immunity. Mouse Paneth cells also express alpha-defensin-related Defcr-rs genes that code for cysteine-rich sequence 4C (CRS4C) peptides that have a unique CPX triplet repeat motif. In ileitis-prone SAMP1/YitFc mice, Paneth cell levels of CRS4C mRNAs and peptides are induced more than a 1000-fold relative to non-prone strains as early as 4 weeks of age, with the mRNA and peptide levels highest in distal ileum and below detection in duodenum. CRS4C-1 peptides are found exclusively in Paneth cells where they occur only in dense core granules and thus are secreted to function in the intestinal lumen. CRS4C bactericidal peptide activity is membrane-disruptive in that it permeabilizes Escherichia coli and induces rapid microbial cell K(+) efflux, but in a manner different from mouse alpha-defensin cryptdin-4. In in vitro studies, inactive pro-CRS4C-1 is converted to bactericidal CRS4C-1 peptide by matrix metalloproteinase-7 (MMP-7) proteolysis of the precursor proregion at the same residue positions that MMP-7 activates mouse pro-alpha-defensins. The absence of processed CRS4C in protein extracts of MMP-7-null mouse ileum demonstrates the in vivo requirement for intracellular MMP-7 in pro-CRS4C processing.

Let the sun shine in: effects of ultraviolet radiation on invasive pneumococcal disease risk in Philadelphia, Pennsylvania

Background

Streptococcus pneumoniae is a common cause of community acquired pneumonia and bacteremia. Excess wintertime mortality related to pneumonia has been noted for over a century, but the seasonality of invasive pneumococcal disease (IPD) has been described relatively recently and is poorly understood. Improved understanding of environmental influence on disease seasonality has taken on new urgency due to global climate change.

Methods

We evaluated 602 cases of IPD reported in Philadelphia County, Pennsylvania, from 2002 to 2007. Poisson regression models incorporating seasonal smoothers were used to identify associations between weekly weather patterns and case counts. Associations between acute (day-to-day) environmental fluctuations and IPD occurrence were evaluated using a case-crossover approach. Effect modification across age and sex strata was explored, and meta-regression models were created using stratum-specific estimates for effect.

Results

IPD incidence was greatest in the wintertime, and spectral decomposition revealed a peak at 51.0 weeks, consistent with annual periodicity. After adjustment for seasonality, yearly increases in reporting, and temperature, weekly incidence was found to be associated with clear-sky UV index (IRR per unit increase in index: 0.70 [95% CI 0.54-0.91]). The effect of UV index was highest among young strata and decreased with age. At shorter time scales, only an association with increases in ambient sulphur oxides was linked to disease risk (OR for highest tertile of exposure 0.75, 95% CI 0.60 to 0.93).

Conclusion

We confirmed the wintertime predominance of IPD in a major urban center. The major predictor of IPD in Philadelphia is extended periods of low UV radiation, which may explain observed wintertime seasonality. The mechanism of action of diminished light exposure on disease occurrence may be due to direct effects on pathogen survival or host immune function via altered 1,25-(OH)₂-vitamin-D metabolism. These findings may suggest less diminution in future IPD risk with climate change than would be expected if wintertime seasonality was driven by temperature.

Dual oxidases and hydrogen peroxide in a complex dialogue between host mucosae and bacteria

Among the host defense mechanisms against bacteria, leukocyte phagocytosis leads to their hydrogen peroxide (H(2)O(2))-mediated destruction. The recent discovery of dual oxidase (DUOX)-dependent H(2)O(2) generation associated with peroxidase and thiocyanate secretion at the apex of mucosal cells has been similarly interpreted as a killing mechanism. However, the rapid degradation of H(2)O(2) would be expected to reduce the efficiency of this system. It has been demonstrated that H(2)O(2) acts as a chemorepellent for bacteria, and such an effect might be sufficient to block cellular infection. Therefore, H(2)O(2) generation might represent one of the mechanisms that allows the coexistence of mucosae with potentially harmful bacteria. Here, we discuss the possible role of DUOXes and H(2)O(2) in interactions between host mucosae and bacteria to maintain mucosal homeostasis.

Expression of beta-defensins in the canine respiratory tract and antimicrobial activity against Bordetella bronchiseptica

β-Defensins are cationic peptides which form part of the innate immune response of the respiratory epithelium. Due to their antimicrobial properties and immunostimulatory activity, β-defensins are potential tools for the treatment and prevention of respiratory disease. In dogs, infectious respiratory disease is a common problem, particularly in housed animals. This study aimed to assess the presence of four β-defensins in the canine respiratory tract and to use quantitative real-time PCR to determine mRNA levels following microbial challenge. Three β-defensins, CBD1, CBD103 and CBD108, were detected in respiratory cells. All three defensins were also readily expressed in skin samples, while their expression in lymphoid tissues and the kidney was low and inconsistent. Treatment of primary tracheal epithelial cells with lipopolysaccharide (LPS) or infection with canine respiratory coronavirus led to decreased expression of CBD103 and CBD108, while cells infected with canine parainfluenza virus had lower levels of CBD1 and CBD108. Furthermore CBD103 was demonstrated to have antimicrobial activity against the respiratory pathogen Bordetella bronchiseptica.

Identification and characterization of a novel antibacterial peptide, avian beta-defensin 2 from ducks

In this study, a novel avian beta-defensin (AvBD) was isolated from duck pancreas. The complete nucleotide sequence of the gene contained an 195 bp open reading frame encoding 64 amino acids. Homology, characterization and comparison of the gene with AvBD from other avian species confirmed that it was duck AvBD2. The mRNA expression of the gene was analyzed in 17 tissues from 21-day-old ducks. AvBD2 was highly expressed in the trachea, crop, heart, bone marrow, and pancreas; moderately expressed in the muscular stomach, small intestine, kidney, spleen, thymus, and bursa of Fabricius; and weakly expressed in skin. We produced and purified recombinant AvBD2 by expressing the gene in Escherichia coli. As expected, the recombinant peptide exhibited strong bactericidal properties against Bacillus cereus, Staphylococcus aureus, and Pasteurella multocida, and weak bactericidal properties against E. coli and Salmonella choleraesuis. In addition, the recombinant protein retained antimicrobial activity against S. aureus under different temperatures (range, -20 degrees C to 100 degrees C) and pH values (range, 3 to 12).

Mechanisms and function of DUOX in epithelia of the lung

The human lung produces considerable amounts of H(2)O(2). In the normal uninflamed epithelium of both the airways and the alveoli, mucosal release of H(2)O(2) is readily detected both in cell cultures in vitro and in the exhaled breath of humans. The dual oxidases DUOX1 and DUOX2 are the H(2)O(2)-producing isoforms of the NADPH oxidase family found in epithelial cells. The DUOXs are prominently expressed at the apical cell pole of ciliated cells in the airways and in type II cells of the alveoli. Recent studies focused on the functional consequences of H(2)O(2) release by DUOX into the lung lining fluid. In the airways, a major function of DUOX is to support lactoperoxidase (LPO) to generate bactericidal OSCN(-), and there are indications that the DUOX/LPO defense system is critically dependent on the function of the CFTR Cl(-) channel, which provides both SCN(-) (for LPO function) and HCO(3)(-) (for pH adjustment) to the airway surface liquid. Although DUOX is also functional in the alveolar epithelium, no comparable heme peroxidase is present in the alveolus, and thus DUOX-mediated H(2)O(2) release by alveolar cells may have other functions, such as cellular signaling.

Human respiratory syncytial virus A2 strain replicates and induces innate immune responses by respiratory epithelia of neonatal lambs

Human respiratory syncytial virus (hRSV) is a pneumovirus that causes significant respiratory disease in premature and full-term infants. It was our hypothesis that a common strain of RSV, strain A2, would infect, cause pulmonary pathology, and alter respiratory epithelial innate immune responses in neonatal lambs similarly to RSV infection in human neonates. Newborn lambs between 2 and 3 days of age were inoculated intrabronchially with RSV strain A2. The lambs were sacrificed at days 3, 6, and 14 days postinoculation. Pulmonary lesions in the 6-day postinoculation group were typical of RSV infection including bronchiolitis with neutrophils and mild peribronchiolar interstitial pneumonia. RSV mRNA and antigen were detected by qPCR and immunohistochemistry, respectively with peak mRNA levels and antigen at day 6. Expression of surfactant proteins A and D, sheep beta-defensin-1 and thyroid transcription factor-1 mRNA were also assessed by real-time qPCR. There was a significant increase in surfactant A and D mRNA expression in RSV-infected animals at day 6 postinoculation. There were no significant changes in sheep beta-defensin-1 and thyroid transcription factor-1 mRNA expression. This study shows that neonatal lambs can be infected with RSV strain A2 and the pulmonary pathology mimics that of RSV infection in human infants thereby making the neonatal lamb a useful animal model to study disease pathogenesis and therapeutics. RSV infection induces increased expression of surfactant proteins A and D in lambs, which may also be an important feature of infection in newborn infants.

Exogenous pentraxin 3 restores antifungal resistance and restrains inflammation in murine chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by life-threatening bacterial and fungal infections and hyperinflammation. The susceptibility to aspergillosis in experimental CGD (p47(phox-/-) mice) is associated with the failure to control the inherent inflammatory response to the fungus and to restrict the activation of inflammatory Th17 cells. We assessed whether pentraxin (PTX)3, a member of a family of multimeric pattern-recognition proteins with potent anti-Aspergillus activity, could limit pathogenic inflammation in p47(phox-/-) mice by curbing the IL-23/Th17 inflammatory axis in response to the fungus. We found that the production of PTX3 was delayed in CGD mice in infection but exogenous administration of PTX3 early in infection restored antifungal resistance and restrained the inflammatory response to the fungus. This occurred through down-regulation of IL-23 production by dendritic cells and epithelial cells which resulted in limited expansion of IL-23R+ gammadelta+ T cells producing IL-17A and the emergence of Th1/Treg responses with minimum pathology. Thus, PTX3 could be therapeutically used for the exploitation of NADPH-independent mechanism(s) of antifungal immune protection with limited immunopathology in CGD.

Alpha-defensins in enteric innate immunity: functional Paneth cell alpha-defensins in mouse colonic lumen

Paneth cells are a secretory epithelial lineage that release dense core granules rich in host defense peptides and proteins from the base of small intestinal crypts. Enteric alpha-defensins, termed cryptdins (Crps) in mice, are highly abundant in Paneth cell secretions and inherently resistant to proteolysis. Accordingly, we tested the hypothesis that enteric alpha-defensins of Paneth cell origin persist in a functional state in the mouse large bowel lumen. To test this idea, putative Crps purified from mouse distal colonic lumen were characterized biochemically and assayed in vitro for bactericidal peptide activities. The peptides comigrated with cryptdin control peptides in acid-urea-PAGE and SDS-PAGE, providing identification as putative Crps. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry experiments showed that the molecular masses of the putative alpha-defensins matched those of the six most abundant known Crps, as well as N-terminally truncated forms of each, and that the peptides contain six Cys residues, consistent with identities as alpha-defensins. N-terminal sequencing definitively revealed peptides with N termini corresponding to full-length, (des-Leu)-truncated, and (des-Leu-Arg)-truncated N termini of Crps 1-4 and 6. Crps from mouse large bowel lumen were bactericidal in the low micromolar range. Thus, Paneth cell alpha-defensins secreted into the small intestinal lumen persist as intact and functional forms throughout the intestinal tract, suggesting that the peptides may mediate enteric innate immunity in the colonic lumen, far from their upstream point of secretion in small intestinal crypts.

Expression of antiviral molecular genes in nasal polyp-derived cultured epithelial cells

CONCLUSION

The results of the present study indicate the existence of natural immunity mechanisms via which viruses are eliminated from nasal and paranasal sinus mucosa.

OBJECTIVES

Acute sinusitis and acute aggravation of chronic sinusitis are often caused by bacteria, which are secondary to viral infection of the nose. Antiviral molecules are considered to be expressed and protect the host after viral infection. We investigated the expression of antiviral molecules after viral infection of the nose.

MATERIALS AND METHODS

We assessed the expression of antiviral molecules, defensin and interferon mRNA, by the real-time polymerase chain reaction (PCR) technique after stimulating cultured nasal polyp cells with polyinosine-polycytidylic acid (poly(I:C)), which is an analog of double-stranded (ds) RNA.

RESULTS

The expression of beta-defensin mRNA significantly increased after the stimulation. On the other hand, expression of both interferon-alpha mRNA and interferon-beta mRNA was recognized, but only the expression of interferon-beta mRNA increased after the stimulation.

Characterization of two isoforms of Japanese spiny lobster Panulirus japonicus defensin cDNA

Antimicrobial peptides (AMPs) are components of the innate immune responses that form the first line of host defense against pathogens. In this study, cDNAs of two new isoforms of defensin (designated PJD1 and PJD2) from a Japanese spiny lobster Panulirus japonicus haemocytes cDNA library were cloned and sequenced. PJD1 and PJD2 consist of 656 and 673 nucleotides encoding putative proteins of 66 and 64 amino acids, respectively. The isoforms share 74.2% amino acid identity. In a phylogenetic analysis, the peptides clustered with vertebrate defensins and were closely mostly related to chicken beta-defensin. PJD1 and PJD2 were detected in all tissues examined including heart, nerves, intestine, haemocytes, gills and hepatopancreas.

Role of antimicrobial peptides in host defense against mycobacterial infections

Worldwide, tuberculosis remains the most important infectious disease causing morbidity and death. Currently, at least one-third of the world's population is infected with Mycobacterium tuberculosis. In addition, the World Health Organization estimates that about 8-10 million new tuberculosis cases occur annually worldwide and this incidence is currently increasing. Moreover, multidrug-resistant tuberculosis has been increasing in incidence in many areas during the past decade. These situations underscore the importance of the development of new therapeutic agents against mycobacterial infectious diseases. In this article, it is review current progress in the understanding of antimicrobial peptides as potential candidates to develop an alternative/adjunct therapeutic strategy against tuberculosis. This immunoadjunctive therapy might be evaluated in the context of possible drug resistance. This review also summarizes the knowledge about the functions of antimicrobial peptides in the pulmonary innate host defense system and their role in mycobacterial infection, and at the same time outlines recent advances in our understanding of the combined effect of antimicrobial peptides and anti-tuberculosis drugs against intracellular mycobacteria. A concerted effort should now focus on the clinical application of antimicrobial peptides for their practical use.

Induction of beta defensin 2 by NTHi requires TLR2 mediated MyD88 and IRAK-TRAF6-p38MAPK signaling pathway in human middle ear epithelial cells

Background

All mucosal epithelia, including those of the tubotympanium, are secreting a variety of antimicrobial innate immune molecules (AIIMs). In our previous study, we showed the bactericidal/bacteriostatic functions of AIIMs against various otitis media pathogens. Among the AIIMs, human β-defensin 2 is the most potent molecule and is inducible by exposure to inflammatory stimuli such as bacterial components or proinflammatory cytokines. Even though the β-defensin 2 is an important AIIM, the induction mechanism of this molecule has not been clearly established. We believe that this report is the first attempt to elucidate NTHi induced β-defensin expression in airway mucosa, which includes the middle ear.

Methods

Monoclonal antibody blocking method was employed in monitoring the TLR-dependent NTHi response. Two gene knock down methods – dominant negative (DN) plasmid and small interfering RNA (siRNA) – were employed to detect and confirm the involvement of several key genes in the signaling cascade resulting from the NTHi stimulated β-defensin 2 expression in human middle ear epithelial cell (HMEEC-1). The student's t-test was used for the statistical analysis of the data.

Results

The experimental results showed that the major NTHi-specific receptor in HMEEC-1 is the Toll-like receptor 2 (TLR2). Furthermore, recognition of NTHi component(s)/ligand(s) by TLR2, activated the Toll/IL-1 receptor (TIR)-MyD88-IRAK1-TRAF6-MKK3/6-p38 MAPK signal transduction pathway, ultimately leading to the induction of β-defensin 2.

Conclusion

This study found that the induction of β-defensin 2 is highest in whole cell lysate (WCL) preparations of NTHi, suggesting that the ligand(s) responsible for this up-regulation may be soluble macromolecule(s). We also found that this induction takes place through the TLR2 dependent MyD88-IRAK1-TRAF6-p38 MAPK pathway, with the primary response occurring within the first hour of stimulation. In combination with our previous studies showing that IL-1α-induced β-defensin 2 expression takes place through a MyD88-independent Raf-MEK1/2-ERK MAPK pathway, we found that both signaling cascades act synergistically to up-regulate β-defensin 2 levels. We propose that this confers an essential evolutionary advantage to the cells in coping with infections and may serve to amplify the innate immune response through paracrine signaling.

Role of human beta-defensin-2 during tumor necrosis factor-alpha/NF-kappaB-mediated innate antiviral response against human respiratory syncytial virus

Human respiratory syncytial virus (RSV) constitutes a highly pathogenic virus that infects lung epithelial cells to cause a wide spectrum of respiratory diseases. Our recent studies have revealed the existence of an interferon-alpha/beta-independent, innate antiviral response against RSV that was dependent on activation of NF-kappaB. We demonstrated that NF-kappaB inducing pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF) confers potent antiviral function against RSV in an NF-kappaB-dependent fashion, independent of interferon-alpha/beta. During our efforts to study this pathway, we identified HBD2 (human beta-defensin-2), a soluble secreted cationic protein as an antiviral factor induced during NF-kappaB-dependent innate antiviral activity in human lung epithelial cells. Our results demonstrated that HBD2 is induced by TNF and RSV in an NF-kappaB-dependent manner. Induction of HBD2 in infected cells was mediated by the paracrine/autocrine action of TNF produced upon RSV infection. HBD2 plays a critical role during host defense, because purified HBD2 drastically inhibited RSV infection. We also show that the antiviral mechanism of HBD2 involves blocking of viral cellular entry possibly because of destabilization/disintegration of the viral envelope. The important role of HBD2 in the innate response was also evident from loss of antiviral activity of TNF upon HBD2 silencing by short interfering RNA. The in vivo physiological relevance of HBD2 in host defense was apparent from induction of murine beta-defensin-4 (murine counterpart of HBD2) in lung tissues of RSV-infected mice. Thus, HBD2 functions as an antiviral molecule during NF-kappaB-dependent innate antiviral immunity mediated by the autocrine/paracrine action of TNF.

Structural variation of the human genome

There is growing appreciation that the human genome contains significant numbers of structural rearrangements, such as insertions, deletions, inversions, and large tandem repeats. Recent studies have defined approximately 5% of the human genome as structurally variant in the normal population, involving more than 800 independent genes. We present a detailed review of the various structural rearrangements identified to date in humans, with particular reference to their influence on human phenotypic variation. Our current knowledge of the extent of human structural variation shows that the human genome is a highly dynamic structure that shows significant large-scale variation from the currently published genome reference sequence.

On the epidemiology of influenza

The epidemiology of influenza swarms with incongruities, incongruities exhaustively detailed by the late British epidemiologist, Edgar Hope-Simpson. He was the first to propose a parsimonious theory explaining why influenza is, as Gregg said, "seemingly unmindful of traditional infectious disease behavioral patterns." Recent discoveries indicate vitamin D upregulates the endogenous antibiotics of innate immunity and suggest that the incongruities explored by Hope-Simpson may be secondary to the epidemiology of vitamin D deficiency. We identify – and attempt to explain – nine influenza conundrums: (1) Why is influenza both seasonal and ubiquitous and where is the virus between epidemics? (2) Why are the epidemics so explosive? (3) Why do they end so abruptly? (4) What explains the frequent coincidental timing of epidemics in countries of similar latitude? (5) Why is the serial interval obscure? (6) Why is the secondary attack rate so low? (7) Why did epidemics in previous ages spread so rapidly, despite the lack of modern transport? (8) Why does experimental inoculation of seronegative humans fail to cause illness in all the volunteers? (9) Why has influenza mortality of the aged not declined as their vaccination rates increased? We review recent discoveries about vitamin D's effects on innate immunity, human studies attempting sick-to-well transmission, naturalistic reports of human transmission, studies of serial interval, secondary attack rates, and relevant animal studies. We hypothesize that two factors explain the nine conundrums: vitamin D's seasonal and population effects on innate immunity, and the presence of a subpopulation of "good infectors." If true, our revision of Edgar Hope-Simpson's theory has profound implications for the prevention of influenza.

Reduction of TLR2 gene expression in allergic and nonallergic rhinitis

BACKGROUND

Immunomodulators, including toll-like receptors (TLRs) and defensins, produced in response to pathogenic stimuli, can direct the developing immune system toward a T(H)1 nonallergic phenotype. Increased human beta-defensin (HBD) 4 expression is associated with infection.

OBJECTIVE

To determine whether reduced mucosal levels of TLRs and defensins contribute to the inflammation seen in chronic allergic and nonallergic rhinitis.

METHODS

Real-time polymerase chain reaction was used to determine gene expression levels of HBDs 1 through 4 and TLRs 2 and 4. Immunohistochemical analysis was used to study the localization and distribution of protein for alpha-defensins 1 through 3, HBD2, neutrophil elastase, and TLR2 in sections of nasal turbinate tissue from adults with persistent allergic and idiopathic rhinitis, healthy nasal mucosa, and tonsil tissue.

RESULTS

Allergic mucosa showed a significant (P = .02) reduction in TLR2 messenger RNA expression compared with control mucosa and generally reduced expression for TLR4 and HBDs. Although not significant, the nonallergic group also showed reduced expression for TLRs and HBDs. With the exception of HBD4, increased target gene levels were seen in tonsil tissue. Protein expression of HBD2 and TLR2 was localized in lining and submucosal glandular epithelium but insignificant differences were seen for HBDs, TLRs, neutrophils, and a-defensin between the rhinitic and control patient groups.

CONCLUSIONS

Subjects with allergic and nonallergic rhinitis show reduced TLR and HBD gene expression. The significant reduction in TLR2 gene expression in allergic adults supports the concept that increased TLR2 protects against the development of allergy. The low levels of HBD4 detected in both rhinitis groups suggest lack of an underlying infection pathophysiological feature.

Diagnosis and treatment of vitamin D deficiency

The recent discovery--in a randomised, controlled trial--that daily ingestion of 1100 IU of colecalciferol (vitamin D) over a 4-year period dramatically reduced the incidence of non-skin cancers makes it difficult to overstate the potential medical, social and economic implications of treating vitamin D deficiency. Not only are such deficiencies common, probably the rule, vitamin D deficiency stands implicated in a host of diseases other than cancer. The metabolic product of vitamin D is a potent, pleiotropic, repair and maintenance, secosteroid hormone that targets > 200 human genes in a wide variety of tissues, meaning it has as many mechanisms of action as genes it targets. A common misconception is that government agencies designed present intake recommendations to prevent or treat vitamin D deficiency. They did not. Instead, they are guidelines to prevent particular metabolic bone diseases. Official recommendations were never designed and are not effective in preventing or treating vitamin D deficiency and in no way limit the freedom of the physician--or responsibility--to do so. At this time, assessing serum 25-hydroxy-vitamin D is the only way to make the diagnosis and to assure that treatment is adequate and safe. The authors believe that treatment should be sufficient to maintain levels found in humans living naturally in a sun-rich environment, that is, > 40 ng/ml, year around. Three treatment modalities exist: sunlight, artificial ultraviolet B radiation or supplementation. All treatment modalities have their potential risks and benefits. Benefits of all treatment modalities outweigh potential risks and greatly outweigh the risk of no treatment. As a prolonged 'vitamin D winter', centred on the winter solstice, occurs at many temperate latitudes, < or = 5000 IU (125 microg) of vitamin D/day may be required in obese, aged and/or dark-skinned patients to maintain adequate levels during the winter, a dose that makes many physicians uncomfortable.