Production of beta-defensin antimicrobial peptides by maxillary sinus mucosa

Antimicrobial and Defense Proteins in Chronic Rhinosinusitis with Nasal Polyps

Background and Objectives: Chronic rhinosinusitis with nasal polyps (CRSwNP) presently remains a difficult disease to manage. Antimicrobial and defense proteins are important factors that could help characterize the role of microorganisms in CRSwNP pathogenesis, as the concept of microbial dysbiosis in CRS is still being considered. Our aim is to investigate the complex appearance, relative distribution and interlinks of human β defensin 2 (HBD-2), human β defensin 3 (HBD-3), human β defensin 4 (HBD-4), and cathelicidin LL 37 (LL 37) in chronic rhinosinusitis with nasal polyps (CRSwNP)-affected human nasal mucosa. Materials and Methods: The study group consisted of 48 samples from patients with CRSwNP. Samples were collected during functional endoscopic sinus surgery. The control group consisted of 17 normal healthy nasal mucosa samples gathered during routine septoplasty. β-defensin-2, β-defensin-3, β-defensin-4 and cathelicidin LL 37 in tissue were detected via immunohistochemical analysis. Results: HBD-2, HBD-3 and LL 37 were significantly decreased in epithelial cells in both primary and recurrent nasal polyp samples (p < 0.001) in comparison to control samples. HBD-2 was decreased in the subepithelial connective tissue of primary nasal polyp samples when compared to both recurrent polyp (p = 0.050) and control (p = 0.033) samples. In subepithelial connective tissue, significantly more HBD-3-positive structures were observed in primary nasal polyp samples (p = 0.049) than in control samples. In primary polyp samples, moderate correlations between connective tissue HBD-3 and connective (R = 0.584, p = 0.001) and epithelial tissue LL 37 (R = 0.556, p = 0.002) were observed. Conclusions: Decreased HBD-2, HBD-3 and LL 37 concentrations in the epithelium suggest a dysfunction of the epithelial barrier in patients with nasal polyps. Decreased subepithelial connective tissue HBD-2 suggests different responses to nasal microbiota in patients with primary nasal polyps compared to recurrent nasal polyps. Increased HBD-3 in subepithelial connective tissue suggests a possible role of this antimicrobial peptide in the pathogenesis of primary nasal polyps.

Human neutrophil peptide 1 promotes immune sterilization in vivo by reducing the virulence of multidrug-resistant Klebsiella pneumoniae and increasing the ability of macrophages

By studying the expression in patients and cell modeling in vitro, antimicrobial peptides for Klebsiella were screened. Killing curve and membrane permeability experiments are used to study the antibacterial effect of antimicrobial peptides in vitro. Cytotoxicity-related indicators including lipopolysaccharide (LPS), capsule polysaccharide (CPS), and outer membrane protein expression were measured. Intranasal inoculation of pneumoconiosis was used to construct a mouse infection model, and the survival rate and cytokine expression level were tested. Human neutrophil peptide 1 (HNP-1) showed a significant antibacterial effect, which improved the permeability of the outer membrane of K. pneumoniae. Moreover, HNP-1 decreased LPS, CPS content, and outer membrane proteins. K. pneumoniae infection decreased antimicrobial peptide, oxidative stress, and autophagy-related genes, while HNP-1 increased these genes. After coculture with macrophages, the endocytosis of macrophages is enhanced and the bacterial load is greater in the K. pneumoniae + peptide group. Besides, higher levels of pp38 and pp65 in the K. pneumoniae + peptide group. HNP-1 rescued the cytotoxicity induced by K. pneumoniae. The survival rate is significantly improved after K. pneumoniae is treated by HNP-1. All cytokines in the peptide group were significantly higher. HNP-1 promotes immune sterilization by reducing the virulence of multidrug-resistant K. pneumoniae and increasing the ability of macrophages.

Epstein-Barr Virus—Mild Acquired Immune Deficiency Syndrome (EBV—MAIDS) in Postsurgical Sinusitis

Background

Functional endoscopic sinus surgery has remarkably improved the treatment of chronic rhinosinusitis patients. Computed tomography, endoscopic optical instrumentation, powered microdebriders, and computer-assisted surgery have surmounted the technical problems of obstructive sinusitis care. Most experienced practitioners achieve reported success rates of 85–95% among their surgical patients. However, the 5–15% refractory patients reported by all rhinologic surgeons leave an exasperating and perplexing group who, despite appropriate mechanical corrections, continue to experience debilitating rhinosinusitis episodes requiring repeated oral, nebulized, or intravenous antibiotics, and in some cases, antifungal therapy.

Methods

Recent studies have indicated that host immune response mechanisms may be altered in the paranasal sinus tissues of sinusitis patients. After years of observation, it was felt that these difficult patients may suffer from a common thread of significant partial immunocompromise. Drawing on military experience of treating immunoimmature populations prone to Epstein-Barr virus (EBV) infectious mononucleosis and the consequent postmononucleosis syndrome, it was sought to screen disabled refractory postsurgical sinusitis patients for this factor and treat them with long-standing military protocols for the immunoimmature populations dispatched to third-world combat conditions.

Results

Treatment of Epstein-Barr Virus-Mild Acquired Immune Deficiency Syndrome consisted of periodic intramuscular serum immune globulin injections (immunomodulator therapy), after obtaining their thorough written informed consent, which produced substantial and sustainable improvement in patient's quality of life.

Conclusion

Detection of mild-to-moderate acquired immune deficiency among postsurgical rhinosinusitis patients can lead to successful treatment and an improved quality of life.

The Effects of Fluticasone Propionate on Nasal Epithelial Potential Difference

Background

Human airway epithelium maintains homeostasis of the fluid and salt composition at the airway surface by a regulated transport of sodium and chloride ions. The volume and composition of airway surface liquid have been shown to be important in the pathogenesis of cystic fibrosis, nasal inflammatory disease, and nasal polyposis. The presence of functional epithelial sodium and chloride channels in the airway epithelium can be evaluated electrically by measuring the voltage across the nasal epithelium (Vt). Because fluticasone propionate is commonly used to treat nasal inflammatory diseases, we tested its effect on the nasal ion transport.

Methods

A single-blind prospective trial was performed on 12 healthy volunteers. Subjects were randomized to receive either fluticasone propionate or normal saline nasal spray twice daily for 2 weeks. We measured the nasal voltage at baseline, days 3 and 14, and 2 weeks after cessation of treatment. The basal voltage, the change in voltage after perfusion with amiloride (sodium channel blocker), and the change in voltage after perfusion with isoproterenol in a low-chloride buffer (chloride channel activator) were recorded. Saccharin clearance times were measured also.

Results

Two-week treatment with fluticasone propionate resulted in a significant increase in the change in Vt after perfusion with amiloride. There was no significant change in the group treated with normal saline. These findings also were observed on day 3 and were reversed completely after the 2-week washout period. The increase in amiloride-sensitive Vt did not result in a decrease in mucociliary clearance.

Conclusions

This study suggests that one effect of fluticasone propionate use on nasal mucosa in normal volunteers is increased epithelial sodium absorption.

Immunohistochemical study on the distribution of β-defensin 1 and β-defensin 2 throughout the respiratory tract of healthy rats

The distributions of β-defensin 1 and 2 in secretory host defense system throughout respiratory tract of healthy rats were immunohistochemically investigated. In the nasal epithelium, a large number of non-ciliated and non-microvillous cells (NCs) were immunopositive for both β-defensin 1 and 2, whereas a small number of goblet cells (GCs) were immunopositive only for β-defensin 1. Beta-defensin 2-immunopositive GCs were few. In the nasal glands, a small number of acinar cells and a large number of ductal epithelial cells were immunopositive for both β-defensins. In the laryngeal and tracheal epithelia, a very few NCs and GCs were immunopositive for both β-defensins. In laryngeal and tracheal glands, a very few acinar cells and a large number of ductal epithelial cells were immunopositive for both β-defensins. In the extra-pulmonary bronchus, a small number of NCs were immunopositive for both β-defensins. A small number of GCs were immunopositive for β-defensin 1, whereas few GCs were immunopositive for β-defensin 2. From the intra-pulmonary bronchus to alveoli, a very few or no epithelial cells were immunopositive for both β-defensins. In the mucus and periciliary layers, β-defensin 1 was detected from the nose to the extra-pulmonary bronchus, whereas β-defensin 2 was weakly detected only in the nose and the larynx. These findings suggest that the secretory sources of β-defensin 1 and 2 are mainly distributed in the nasal mucosa and gradually decrease toward the caudal airway in healthy rats.

Beta-Defensin-2 and Beta-Defensin-3 Reduce Intestinal Damage Caused by Salmonella typhimurium Modulating the Expression of Cytokines and Enhancing the Probiotic Activity of Enterococcus faecium

The intestinal microbiota is a major factor in human health and disease. This microbial community includes autochthonous (permanent inhabitants) and allochthonous (transient inhabitants) microorganisms that contribute to maintaining the integrity of the intestinal wall, modulating responses to pathogenic noxae and representing a key factor in the maturation of the immune system. If this healthy microbiota is disrupted by antibiotics, chemotherapy, or a change in diet, intestinal colonization by pathogenic bacteria or viruses may occur, leading to disease. To manage substantial microbial exposure, epithelial surfaces of the intestinal tract produce a diverse arsenal of antimicrobial peptides (AMPs), including, of considerable importance, the β-defensins, which directly kill or inhibit the growth of microorganisms. Based on the literature data, the purpose of this work was to create a line of intestinal epithelial cells able to stably express gene encoding human β-defensin-2 (hBD-2) and human β-defensin-3 (hBD-3), in order to test their role in S. typhimurium infections and their interaction with the bacteria of the gut microbiota.

Nasal Irrigation: An Imprecisely Defined Medical Procedure

Nasal irrigation (NI) is an old practice of upper respiratory tract care that likely originated in the Ayurvedic medical tradition. It is used alone or in association with other therapies in several conditions—including chronic rhinosinusitis and allergic rhinitis—and to treat and prevent upper respiratory tract infections, especially in children. However, despite it being largely prescribed in everyday clinical practice, NI is not included or is only briefly mentioned by experts in the guidelines for treatment of upper respiratory tract diseases. In this review, present knowledge about NI and its relevance in clinical practice is discussed to assist physicians in understanding the available evidence and the potential use of this medical intervention. Analysis of the literature showed that NI seems to be effective in the treatment of several acute and chronic sinonasal conditions. However, although in recent years several new studies have been performed, most of the studies that have evaluated NI have relevant methodologic problems. Only multicenter studies enrolling a great number of subjects can solve the problem of the real relevance of NI, and these studies are urgently needed. Methods for performing NI have to be standardized to determine which solutions, devices and durations of treatment are adequate to obtain favorable results. This seems particularly important for children that suffer a great number of sinonasal problems and might benefit significantly from an inexpensive and simple preventive and therapeutic measure such as NI.

The role of human β-defensins in allergic diseases

Antimicrobial peptides (AMPs), also referred to as host defence peptides (HDPs), comprise a large family of small molecules broadly distributed throughout the animal and plant kingdom, historically serving as natural antibiotics. In mammals, there are two major families of AMPs/HDPs, the defensins and the cathelicidins. These peptides have evolved to protect against a wide range of infections from bacteria, viruses, fungi and some parasites. However, in addition to their broad-spectrum killing activities, AMPs/HDPs also possess various biological functions. They activate a variety of cell types, such as keratinocytes, airway epithelial cells and mast cells, among others, and regulate cytokine/chemokine production, cell migration, proliferation, differentiation, angiogenesis, the wound healing process and maintenance of the skin barrier function. Recently, it has become clear that alterations in the level of AMPs/HDPs are associated with the initiation and development of various inflammatory and allergic diseases. In this review, we will discuss the regulation and functions of human β-defensins and outline the current evidence supporting the role of these peptides in the pathogenesis of allergic diseases, including atopic dermatitis, allergic rhinitis, asthma and chronic rhinosinusitis. Understanding the functions and mechanisms of human β-defensins may aid in the development of novel therapeutic strategies for allergic diseases.

Differential protein expression in the secretory fluids of maxillary sinusitis and maxillary retention cyst

Both maxillary sinusitis (MS) and maxillary retention cyst (MRC) involve the maxillary sinus and show similar clinical features. Clinically, differentiating between MS and MRC is sometimes difficult in asymptomatic patients, despite their quite different pathogenic behaviors. To identify differential protein expressions in the secretory fluids of MS and MRC, 25 cases of asymptomatic MS and 15 cases of asymptomatic MRC were examined pathologically in this study. All patients underwent routine endoscopic sinus surgery or modified Caldwell-Luc procedure and the sinus mucosal specimens obtained during these procedures with the approval of the Institutional Review Board. Their secretory fluids were analyzed via immunoprecipitation-based high-performance liquid chromatography (IP-HPLC) using 25 types of antiserum, including inflammatory cytokines, antimicrobial proteins, and mucosal protective proteins. In the histological examinations, MS and MRC showed similar features in the secretory columnar epithelial lining and thick submucosal connective tissue, both of which contained few inflammatory cells infiltrates. The IP-HPLC analysis revealed that TNFα, IL-1, -8, MMP-3, -10, α1-antitrypsin, cathepsin C, lysozyme, lactoferrin, β-defensin-1, -3, LL-37, mucocidin, and mucin-1 were more intensely expressed in MS than in MRC; whereas IgA, cystatin A, and proline-rich proteins were more strongly expressed in MRC than in MS. These data indicate that the secretory fluid of MS is indicative of a more robust inflammatory reaction to certain bacteria compared to that of MRC, while the secretory fluid of MRC contains more abundant mucosal protective proteins compared to that of MS. Taken together, the IP-HPLC analysis of MS and MRC secretory fluid revealed that MRC showed a weaker inflammatory reaction but a stronger mucosal protective function than MS.

In vivo Cigarette Smoke Exposure Decreases CCL20, SLPI, and BD-1 Secretion by Human Primary Nasal Epithelial Cells

Smokers and individuals exposed to second-hand cigarette smoke have a higher risk of developing chronic sinus and bronchial infections. This suggests that cigarette smoke (CS) has adverse effects on immune defenses against pathogens. Epithelial cells are important in airway innate immunity and are the first line of defense against infection. Airway epithelial cells not only form a physical barrier but also respond to the presence of microbes by secreting antimicrobials, cytokines, and chemokines. These molecules can lyse infectious microorganisms and/or provide signals critical to the initiation of adaptive immune responses. We examined the effects of CS on antimicrobial secretions of primary human nasal epithelial cells (PHNECs). Compared to non-CS-exposed individuals, PHNEC from in vivo CS-exposed individuals secreted less chemokine ligand (C-C motif) 20 (CCL20), Beta-defensin 1 (BD-1), and SLPI apically, less BD-1 and SLPI basolaterally, and more CCL20 basolaterally. Cigarette smoke extract (CSE) exposure in vitro decreased the apical secretion of CCL20 and beta-defensin 1 by PHNEC from non-CS-exposed individuals. Exposing PHNEC from non-CS exposed to CSE also significantly decreased the levels of many mRNA transcripts that are involved in immune signaling. Our results show that in vivo or in vitro exposure to CS alters the secretion of key antimicrobial peptides from PHNEC, but that in vivo CS exposure is a much more important modifier of antimicrobial peptide secretion. Based on the gene expression data, it appears that CSE disrupts multiple immune signaling pathways in PHNEC. Our results provide mechanistic insight into how CS exposure alters the innate immune response and increases an individual's susceptibility to pathogen infection.

Assessment of epithelial innate antimicrobial factors in sinus tissue from patients with and without chronic rhinosinusitis

BACKGROUND

Airway secretions contain endogenous antimicrobial factors (AMFs) that contribute to the innate host defense of the respiratory tract. Antibacterial peptides as well as host-derived lipids including cholesteryl esters have been detected in maxillary lavage fluid. Sterol O-acyltransferase 1 (SOAT1) is a key enzyme in cholesteryl ester production. The purpose of this study is to determine if such intrinsic microbicidal molecules are acutely expressed within sinus tissue and to compare levels of expression between patients with and without chronic rhinosinusitis (CRS).

METHODS

Sinus tissue was obtained from subjects with (24) and without (9) a history of CRS. Six CRS patients had nasal polyposis (CRSwNP). Immunofluorescence staining for human neutrophil peptide (HNP) was done as a marker for inflammation. Real-time polymerase chain reaction (RT-PCR) following RNA extraction was used to quantify the expression of SOAT-1, the epithelial beta-defensins (HBD2 and HBD3), and the cathelicidin LL37 with ribosomal protein, large, P0 (RPLP0) as the housekeeping gene.

RESULTS

Immunofluorescence showed significant increase in HNP staining in CRS patients without nasal polyposis (CRSsNP) vs non-CRS specimens (p = 0.010), in agreement with clinical inflammation status. SOAT1 messenger RNA (mRNA) expression was also upregulated in CRSsNP compared to non-CRS (p = 0.041) and CRSwNP (p = 0.005) patients, whereas increases for HBD2 and HBD3 were less prominent. LL37 was either absent or expressed at very low levels in all samples.

CONCLUSION

Increased biosynthesis of SOAT1, a key enzyme for antimicrobial cholesteryl ester production, was observed in the sinus tissue of CRSsNP patients but not in CRSwNP patients. This further supports the novel concept of lipid-mediated innate mucosal defense and delineates CRS with and without nasal polyposis as distinct subtypes.

Bitter and sweet taste receptors regulate human upper respiratory innate immunity

Bitter taste receptors (T2Rs) in the human airway detect harmful compounds, including secreted bacterial products. Here, using human primary sinonasal air-liquid interface cultures and tissue explants, we determined that activation of a subset of airway T2Rs expressed in nasal solitary chemosensory cells activates a calcium wave that propagates through gap junctions to the surrounding respiratory epithelial cells. The T2R-dependent calcium wave stimulated robust secretion of antimicrobial peptides into the mucus that was capable of killing a variety of respiratory pathogens. Furthermore, sweet taste receptor (T1R2/3) activation suppressed T2R-mediated antimicrobial peptide secretion, suggesting that T1R2/3-mediated inhibition of T2Rs prevents full antimicrobial peptide release during times of relative health. In contrast, during acute bacterial infection, T1R2/3 is likely deactivated in response to bacterial consumption of airway surface liquid glucose, alleviating T2R inhibition and resulting in antimicrobial peptide secretion. We found that patients with chronic rhinosinusitis have elevated glucose concentrations in their nasal secretions, and other reports have shown that patients with hyperglycemia likewise have elevated nasal glucose levels. These data suggest that increased glucose in respiratory secretions in pathologic states, such as chronic rhinosinusitis or hyperglycemia, promotes tonic activation of T1R2/3 and suppresses T2R-mediated innate defense. Furthermore, targeting T1R2/3-dependent suppression of T2Rs may have therapeutic potential for upper respiratory tract infections.

Antimicrobial lipids: novel innate defense molecules are elevated in sinus secretions of patients with chronic rhinosinusitis

BACKGROUND

Airway secretions possess intrinsic antimicrobial properties that contribute to the innate host defense of the respiratory tract. These microbicidal capabilities have largely been attributed to the presence of antibacterial polypeptides. However, recent investigation has indicated that host-derived lipids including cholesteryl esters also exhibit antimicrobial properties. The purpose of this study was to determine whether sinus secretions contain such antimicrobial lipids and to compare the lipid composition in patients with and without chronic rhinosinusitis (CRS).

METHODS

Maxillary sinus fluid was obtained via antral lavage from subjects with (seven patients) and without (nine patients) a history of CRS. After specimen collection, total lipid was extracted according to Bligh and Dyer (Bligh EG and Dyer WJ, A rapid method of total lipid extraction and purification, Can J Biochem Physiol 37:911-918, 1959) and lipid profiles were obtained by reverse phase high-performance liquid chromatography on an amide-embedded C18 column. In addition, the neutrophil-specific antimicrobial peptides human neutrophil peptides 1-3 (HNP1-3) were quantified by Western immunoblotting.

RESULTS

Lipids, including cholesteryl esters, were identified in the maxillary sinus secretions of patients with and without CRS. However, levels of lipid composition differed between the two groups with CRS patients exhibiting greater amounts of all classes of lipids, reaching over 10-fold higher concentration when compared with non-CRS patients. This increase was independent of HNP1-3 content.

CONCLUSION

Sinus secretions of patients with CRS appear to show elevated levels of antimicrobial lipids compared with controls independent from neutrophil influx. This up-regulation suggests that host-derived lipids act as mediators of mucosal immunity in CRS. Further study is necessary to determine if such antimicrobial lipids function alone or synergistically with antibacterial peptides in conferring such inherent microbicidal properties.

Vitamin D, innate immunity and upper respiratory tract infection

INTRODUCTION

At the turn of the twentieth century, ultraviolet light was successfully used to treat tuberculosis of the skin. Upper respiratory tract infections had been inversely associated with sun exposure. During the last decade, basic scientific research demonstrated that vitamin D has an important anti-infective role.

METHOD

Review of the relevant literature on the influence of vitamin D on innate immunity and respiratory tract infection.

RESULTS

Vitamin D is involved in the production of defensins and cathelicidin - antimicrobial peptides that provide a natural defence against potential microbiological pathogens. Vitamin D supplementation increases cathelicidin production. Low vitamin D levels are associated with an increased incidence of upper respiratory tract infections.

CONCLUSIONS

Vitamin D appears to play an important role in the regulation of innate immunity in the upper respiratory tract. Optimal vitamin D levels and appropriate dosing schedules have yet to be determined.

Effects of an LL-37-derived antimicrobial peptide in an animal model of biofilm Pseudomonas sinusitis

BACKGROUND

LL-37, an innate immunity protein expressed within sinonasal mucosa, has in vitro antibacterial and antifungal properties as well as efficacy against preformed Pseudomonas aeruginosa biofilms. We hypothesize that a 24 amino acid peptide derivative of LL-37 will show efficacy against biofilm-forming P. aeruginosa in an established animal model of sinusitis.

METHODS

Five groups of six New Zealand rabbits were each infected with P. aeruginosa (PAO-1) and fitted with irrigating catheters 7 days later. Each group was instilled with either one of three different concentrations of peptide, a positive control of topical tobramycin, or the carrier solution without the peptide once a day for 10 days. Nasal diluent was collected throughout the irrigation period to assess for persistence or resolution of infection by determining colony-forming units (CFU). At study end, sinus mucosa was harvested for histological assessment of inflammation and SEM evaluation for ciliary integrity and presence of biofilms.

RESULTS

Topical tobramycin at 400x minimum inhibitory concentration and 2.5 mg/mL of peptide were effective in significantly lowering CFUs after 10 days of irrigation. Histological evaluation showed increased signs of inflammation in a dose-dependent manner within mucosa and bone of the groups receiving the peptide. SEM analysis showed ciliary loss in a dose-dependent manner. Biofilms were present in all groups except for the highest concentration of peptide and tobramycin.

CONCLUSION

High concentrations of LL-37-derived peptide showed in vivo ability to eradicate Pseudomonas biofilms and decrease bacterial counts. However, increasing concentrations of peptide showed proinflammatory and ciliotoxic effects on sinus mucosa.

Innate immunity in the paranasal sinuses: a review of nasal host defenses

BACKGROUND

Chronic rhinosinusitis (CRS) is a common inflammatory disorder of the paranasal sinuses. An abnormal host response to common bacterial or fungal pathogens is thought to be an important factor in the disease process. Host sinonasal epithelium plays an important role in initially recognizing the presence of microbes and responding by increasing production of antimicrobial peptides and cytokines, with recruitment of phagocytes and lymphocytes of the adaptive immune system, to eliminate the infection. Recently, the innate immune system and its complex interplay with the adaptive immune system are increasingly being recognized as important in the pathogenesis of chronic inflammatory diseases such as asthma and CRS.

METHODS

Review of recent findings on innate immunity in the pathogenesis of CRS.

RESULTS

New areas of research into potentially novel therapies for CRS are highlighted in this review, with emphasis on toll-like receptors, antimicrobial peptides (cathelicidins and defensins), and surfactant proteins.

CONCLUSION

This review provides an overview of innate immunity in the sinonasal tract and discusses potential use of innate immune peptides as treatments against fungi, biofilms, and superantigens in CRS.

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.

Topical treatment of rhinosinusitis

We reviewed current clinical evidence for the use of topical treatments in pediatric rhinosinusitis. Repeated Entrez PubMed searches were done using the template algorithm [rhinosinusitis AND (...)] with the settings: [Humans; English; All Child 0-18; Clinical trial; Last 10 yr] for the following comparators: steroid, irrigation, saline, antihistamine, decongestant, antibiotic, antimycotic, fungicide. The authors' clinical experience in the pediatric allergy unit of a university hospital was also drawn upon. Pediatric studies were retrieved but only one satisfied current evidence-based medicine standards for reporting clinical trials. Studies could not be systematized because of methodological, analytical, and interpretation biases. While saline irrigation, nasal decongestants, steroids, antibiotics, antihistamines and fungicides are all in widespread pediatric use, comparing studies from the literature for evidence of efficacy implied subjective appraisal, except in the case of topical steroids. Evidence for the efficacy of topical treatment for pediatric rhinosinusitis is narrative albeit this modality cannot be excluded from individualized patient protocols on the basis of the clinical literature alone. With the exception of topical steroids, no weighable evidence of effectiveness supports the premise that topical treatments actually serve the purpose for which they are widely prescribed in pediatrics.

Innate immunity of the sinonasal cavity and its role in chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is one of the most common health problems in the United States. Medical therapy and surgery are successful in treating the majority of patients with sinusitis; however, CRS patients recalcitrant to traditional therapy are increasingly prevalent. Although traditionally this illness could be explained by sinus ostial obstruction and persistent bacterial infection, the rhinologic literature over the years has suggested a significant underlying inflammatory component. Adaptive immune components, including lymphocytes and their associated cytokines, have been the subject of most research in chronic nasal inflammation. A recent appreciation of the importance of the innate immune system is leading to new areas of investigation regarding the pathogenesis of CRS. This review will outline our current knowledge of sinonasal innate immunity, the role of innate immunity in the pathogenesis of CRS, and potential therapeutic targets in the innate immune system.

Antimicrobial activities of human beta-defensins against Bacillus species

Natural defences in the human body function to protect us from numerous environmental toxins and exposure to potential harmful biological agents. An important frontline defence is antimicrobial peptides. These peptides occur at environmental interfaces and serve to limit bacterial invasion. There has been little work comparing specific peptides as potential antimicrobial compounds. In this study, we evaluated the antimicrobial activity of peptides from the human beta-defensin (HBD) family against four species of Bacillus, chosen as models for Bacillus anthracis, a potential bioweapon. The impact of peptide concentration, sequence and protein binding was evaluated on their biological activity. The results indicated that HBD-3 was the most biologically active against Bacillus subtilis and Bacillus licheniformis, whilst HBD-2 was found to be most active against Bacillus cereus and Bacillus thuringiensis. Moreover, the antimicrobial activity of the peptides was directly related to peptide concentration and indirectly related to albumin concentration (i.e. protein binding).

Xylitol Enhances Bacterial Killing in the Rabbit Maxillary Sinus

OBJECTIVES

Factors that alter airway surface liquid (ASL) ionic concentrations may influence the course of sinusitis. Xylitol has been shown to effect ASL ionic composition in vitro and to reduce nasal bacterial carriage, otitis media, and dental caries in vivo. We examined the effect of xylitol on experimental sinusitis in the rabbit model.

STUDY DESIGN

Prospective randomized controlled study of xylitol, saline, and Pseudomonas aeruginosa administration to the rabbit maxillary sinus.

METHODS

P. aeruginosa was administered to the sinuses of 26 New Zealand white rabbits. Saline was placed in the left maxillary sinus and xylitol in the right. The rabbits were randomly assigned to one of three groups: one, simultaneous administration of bacteria and solutions with bacterial analysis at 20 minutes, 11 rabbits; two, preadministration of solutions 1 hour before bacterial infection with analysis at 20 minutes, 11 rabbits; three, established sinusitis, 4 rabbits had daily injections of solutions for 5 days starting 7 days after P. aeruginosa administration.

RESULTS

In group 1, 6.96% of injected bacteria were retrieved on the left (saline), whereas 0.095% were retrieved on the right (xylitol) (P = .034). In group 2, 5.64% of inoculum was recovered from the left and 2.89% from the right (P = .188). Group 3 demonstrated evidence of sinusitis with recovery of noninoculate bacteria. with no difference between right and left.

CONCLUSIONS

Xylitol reduces experimental sinusitis when administered simultaneously with bacteria. Its effect in established sinusitis is less clear. A role may exist for xylitol in nasal irrigation fluid in human disease.

Refractory chronic rhinosinusitis: pathophysiology and management of chronic rhinosinusitis persisting after endoscopic sinus surgery

Refractory chronic rhinosinusitis (RCRS) is defined as persistence of signs and symptoms of chronic rhinosinusitis, despite technically adequate endoscopic sinus surgery. Rather than a simple, prolonged bout of acute sinusitis, it instead appears to be secondary to an interaction of a susceptible host with the outside environment. Inflammatory responses to colonizing bacteria appear to be responsible for a significant portion of the pathophysiology. Reduction of bacterial load and inflammation of the mucosa play an important role in controlling the disease. Novel treatment strategies, with an emphasis on topical therapies, seem to offer optimal management. In this review, current concepts on the pathophysiology and current therapies available for RCRS are outlined. A practical management strategy based on the author's personal experience draws upon these concepts, and is detailed in this review of an unusual topic.

Nasal irrigations: good or bad?

PURPOSE OF REVIEW

Nasal irrigations are often mentioned as adjunctive measures in treating many sinonasal conditions. Despite their widespread use, much mystique and uncertainty exist about the indications and therapeutic mechanisms of nasal irrigations. Anecdotal evidence and poorly controlled studies add to the confusion. Recent evidence challenges some of the assumptions underlying the use of nasal irrigations.

RECENT FINDINGS

Studies of nasal irrigations continue to report the benefits in managing sinonasal complaints. Apart from improved patient symptomatology, prescription medication use is often decreased. When nasal irrigations are combined with other medical modalities, patients with chronic sinusitis may not require surgical intervention as often. In particular, patients using hypertonic saline nasal irrigations reported better outcomes. Different devices and techniques exist. Positive-pressure and negative-pressure methods are probably more effective than nebulizers. Furthermore, the popular belief that nasal irrigations need to be sterile is in question.

SUMMARY

Nasal irrigations should no longer be considered merely adjunctive measures in managing sinonasal conditions. They are effective and underutilized. Some of the persisting unanswered questions will only be answered by further research.

Atypical Sinusitis in Adults Must Lead to Looking for Cystic Fibrosis and Primary Ciliary Dyskinesia

HYPOTHESES/OBJECTIVES:: In adults, purulent pansinusitis or nasal polyposis starting early in life or that is permanently infected or associated either with chronic bronchial infection, infertility, or situs inversus are uncommon. In these atypical cases of chronic sinusitis (ACS), a primary dysfunction of the mucociliary clearance can be suspected. Adult patients with ACS were therefore investigated to detect primary ciliary dyskinesia (PCD) or cystic fibrosis (CF).

STUDY DESIGN

Open, prospective study.

PATIENTS AND METHODS

Forty-two patients with ACS were investigated with ciliary beat frequency and ultrastructure analysis in nasal cells and cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation analysis in blood leukocytes.

RESULTS

The diagnosis of PCD was confirmed in seven (17%) patients. At least one CFTR gene mutation was detected in 16 (38%) patients. The diagnosis of CF was suggested in three (7%) compound heterozygous patients. Another 13 (31%) patients were heterozygous for a CFTR gene mutation or a complex allele. Comparison of clinical features of ACS showed that only a family history of chronic sinusitis (P <.01) or chronic bronchitis (P <.02) and the presence of diffuse bronchiectasis (P <.0001) or serous otitis media (P <.0001) were significantly more frequent in PCD patients than in patients carrying CFTR gene mutations or those without PCD or CFTR gene mutations.

CONCLUSIONS

ACS should be considered a remarkable entity in which congenital abnormalities of epithelial cells are frequently detected (55% of patients). The higher frequency of mutations in ACS patients compared with the general population suggests that heterozygoty for CFTR gene mutation could be a sinusitis-causing status.

Expression of human beta-defensin 2 in human nasal mucosa

Human beta-defensin (HBD)-2, an antimicrobial peptide, has been discovered to be produced by a number of epithelial cells. It is identified as a key element in the innate host defense mechanism. Because little is known about the expression of HBD-2 in the human sinonasal tract, we conducted this study to investigate the expression of the HBD-2 mRNA gene by the reverse transcription polymerase chain reaction (RT-PCR) and localization of HBD-2 peptide by immunohistochemistry in human nasal inferior turbinates and nasal polyps. RT-PCR showed significantly higher expression of HBD-2 mRNA in nasal polyps than in inferior turbinates. Using immunohistochemistry, HBD-2 peptide was predominantly localized in surface epithelial cells. Thus, it is feasible that HBD-2 is expressed in nasal mucosa and is upregulated in a condition of chronic inflammation.

Endogenous production of antimicrobial peptides in innate immunity and human disease

Antimicrobial peptides are diverse and evolutionarily ancient molecules produced by all living organisms. Peptides belonging to the cathelicidin and defensin gene families exhibit an immune strategy as they defend against infection by inhibiting microbial survival, and modify hosts through triggering tissue-specific defense and repair events. A variety of processes have evolved in microbes to evade the action of antimicrobial peptides, including the ability to degrade or inactivate antimicrobial peptides, or suppress host production of the peptide in response to infection. Animal models and clinical investigations have shown that an absence of cathelicidin or defensin antimicrobials can lead to disease. In this article, we review important recent advances in understanding the biology of antimicrobial peptides and their role in normal immunity and human disease.