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

Increased expression of intelectin-1 in nasal polyps

BACKGROUND

Intelectin-1 is a new type of Ca(2+)-dependant soluble lectin in humans that has affinity for galactofuranose in carbohydrate chains of bacterial cell walls, indicating that intelectin-1 may play a role in immune defense against bacteria. The purpose of the current study was to determine the expression of intelectin-1 mRNA and protein and to localize intelectin-1 protein in nasal polyps and tissues from control subjects.

METHODS

Normal sphenoid sinus mucosa was obtained from 10 patients undergoing surgery for pituitary tumor. Nasal polyp samples were obtained from 10 patients undergoing endoscopic sinus surgery for chronic polypoid rhinosinusitis. Real-time polymerase chain reaction (PCR) was performed for intelectin-1 mRNA. Immunofluorescent staining was done for localization of intelectin-1 and quantitatively analyzed using computer-based image analysis. Western blot analysis was performed.

RESULTS

Real-time PCR and Western blot analysis showed that intelectin-1 expression in nasal polyps was increased compared with normal sinus mucosa. Using immunofluorescent staining, intelectin-1 was strongly stained in epithelium and submucosa of nasal polyps, and faint staining was found in normal sinus mucosa.

CONCLUSIONS

Intelectin-1 is expressed in human sinus mucosa and is increased in patients with nasal polyps. These results suggest a possible contribution for intelectin-1 in the pathophysiology of nasal polyps.

Fungicidal activity of lysozyme is inhibited in vitro by commercial sinus irrigation solutions

BACKGROUND

Lysozyme is an innate immune peptide with bactericidal and fungicidal activity (FA). Despite increased expression of lysozyme protein in chronic rhinosinusitis (CRS) sinus mucosa, CRS patients experience repeated bacterial and/or fungal infections. Commercial sinus irrigation solutions are often used to provide symptomatic relief. However, one of the mechanisms of action of lysozyme involves ionic interactions with the microbial cell wall, which may be inhibited by ionic solutions such as commercial sinus irrigation solutions.

OBJECTIVE

Determine if the FA of lysozyme is reduced in the presence of solutions with increasing ionic strength and inhibited in the presence of commercial sinus irrigation solutions.

METHODS

Using an in vitro colony-forming unit (CFU) assay, the FA of lysozyme (5 μM) was tested against a fungi commonly isolated from CRS patients, Aspergillus fumigatus, in solutions of increasing ionic strength or commercial sinus irrigation solutions. FA was presented as percent of control.

RESULTS

FA of lysozyme against A. fumigatus was 95% in a 21-mM ionic strength solution. However, with increasing ionic strength, FA decreased and was abolished in a 46-mM ionic strength solution. Commercial sinus irrigation solutions abolished the FA of lysozyme against A. fumigatus.

CONCLUSION

The in vitro FA of lysozyme is dependent on the ionic strength of the solution. The use of sinus irrigation solutions should be further evaluated with regard to maintaining functional activity of cationic antimicrobial peptides involved in sinonasal innate immunity.

Gene expression differences in nitric oxide and reactive oxygen species regulation point to an altered innate immune response in chronic rhinosinusitis

BACKGROUND

The complex interplay between host, environment, and microbe in the etiopathogenesis of chronic rhinosinusitis (CRS) remains unclear. This study focuses on the host-microbe interaction, specifically the regulation of nitric oxide (NO) and reactive oxygen species (ROS) against the pathogenic organism Staphylococcus aureus (S. aureus). NO and ROS play crucial roles in innate immunity and in the first-line defense against microbial invasion.

METHODS

Sinonasal tissue samples were harvested from CRS and control patients during surgery. CRS patients were classified S. aureus biofilm-positive (B+) or biofilm-negative (B-) using fluorescence in situ hybridization and clinically as polyp-positive (P+) or polyp-negative (P-). Samples were assessed using an NO polymerase chain reaction (PCR) array containing 84 genes involved in NO and ROS regulation, and gene expression of all subgroups were compared to each other.

RESULTS

Twenty-three samples were analyzed with 31 genes significantly changed, the greatest seen in the B+P+ CRS patients. Four genes consistently displayed differential expression between the groups including the cytoprotective oxidation resistance 1 (OXR1) and peroxiredoxin 6 (PRDX6), neutrophil cytosolic factor 2 (NCF2), and the prion protein (PRNP) genes.

CONCLUSION

Alteration in gene expression points to impaired innate immune responses differing among CRS subgroups based on S. aureus biofilm and polyp status. The consistent alteration of 4 genes among distinct groups demonstrates that S. aureus biofilms and polyps are associated with specific changes in gene expression. Further studies are required to validate these findings in a wider cohort of patients and correlate this to protein expression and disease manifestation.

Does mannose-binding lectin have a role in adult Turkish patients with nasal polyposis?

OBJECTIVE

Mannose-binding lectin is an important component of innate immunity; it initiates the lectin pathway of complement activation critical for innate immunity. Failure of local innate defenses may result in defective responses that lead to the persistent carriage of microorganisms or ongoing inflammation. This study investigated the role of mannose-binding lectin levels and the frequency of the 6 functional mannose-binding lectin polymorphisms in Turkish individuals with nasal polyposis.

STUDY DESIGN

A case-control study.

SETTING

University hospital.

SUBJECTS AND METHODS

Fifty-one patients with nasal polyposis and 53 healthy controls were enrolled. Serum mannose-binding lectin levels were obtained by enzyme-linked immunosorbent assay (ELISA) using the mannose-binding lectin oligomer ELISA kit. Mannose-binding lectin 2 genotyping was performed by isolating the genomic DNA from leukocytes.

RESULTS

Mean mannose-binding lectin levels were 1693.2 and 1887.8 in the patient and control group, respectively. Although mannose-binding lectin levels were lower in the patient group, the difference was not statistically significant (P > .05). No overall association was observed between the mannose-binding lectin genotype and susceptibility to nasal polyposis (95% confidence interval = 0.716-4.389, odds ratio = 1.773). The mutant allele frequencies of the 3 structural polymorphisms did not differ significantly between the nasal polyposis patients and the controls (P = .659).

CONCLUSIONS

Mannose-binding lectins are not involved in the pathogenesis of nasal polyposis in adult Turkish patients, but additional research is needed for further comment.

Toll- and NOD-like receptor mRNA expression in canine sino-nasal aspergillosis and idiopathic lymphoplasmacytic rhinitis

The pathogenesis of canine sino-nasal aspergillosis (SNA) and lymphoplasmacytic rhinitis (LPR) remains poorly understood. The innate immune system is implicated in the etiology of human chronic rhinosinusitis. Therefore, we hypothesized that dysfunction in innate immunity could be implicated in the pathogenesis of SNA and LPR. Expression of messenger RNA (mRNA) encoding Toll-like receptors (TLRs) 1-10 and NOD-like receptors (NODs) 1 and 2 in nasal mucosal biopsies from SNA or LPR dogs was compared with mucosa from healthy controls. Gene expression was quantified using quantitative real-time reverse transcriptase polymerase chain reaction normalized against multiple housekeeper genes. All TLR and NOD genes were quantified in all samples. SNA was associated with significantly increased expression of TLRs 1-4, 6-10; and NOD2, relative to controls. LPR was associated with significantly increased expression of TLRs 1, 2, 6-8, relative to controls. There was significantly more expression of TLRs 1, 4, 6-10 and NOD2 in SNA dogs than in LPR dogs. The significance of these differences in the pathogenesis of these diseases is yet to be determined.

Microbiome complexity and Staphylococcus aureus in chronic rhinosinusitis

OBJECTIVES/HYPOTHESIS

The aim of this study was to compare microbiological culture-based and culture-independent (16S rRNA gene sequencing) methodologies for pathogen identification in chronic rhinosinusitis (CRS) patients. We hypothesized that bacterial culture and DNA sequencing would yield largely concurrent results, although sequencing would detect greater bacterial diversity, and the sinonasal microbiomes of CRS patients would differ in composition and diversity compared with non-CRS controls.

STUDY DESIGN

Cross-sectional observational study.

METHODS

Middle meatus swabs from CRS patients collected during endoscopic sinus surgery were analyzed by both clinical culture and broad-range analysis of 16S rRNA gene pyrosequences.

RESULTS

A total of 21 swab samples from 15 CRS patients and five non-CRS controls were analyzed. One CRS patient was also swabbed 3 weeks postoperatively due to evidence of purulence during a clinical visit. All subjects had positive bacterial cultures, with a mean of 2.8 isolates per subject. The most prevalent cultivars were coagulase-negative staphylococci (15/20 specimens, 75%), Staphylococcus aureus (10/20, 50%), and Propionibacterium acnes (6/20, 30%). Among 57,407 pyrosequences generated, the most prevalent were from coagulase-negative staphylococci (21/21 specimens, 100%), Corynebacterium spp (18/21, 85.7%), P acnes (16/21, 76.2%), and S aureus (14/21, 66.7%). Bacterial diversity correlated with recent antibiotic use, asthma, prior sinus surgery, and relative abundance of S aureus.

CONCLUSIONS

DNA pyrosequencing revealed greater biodiversity than culture, although in most cases culture results represented a subset of the abundant DNA sequence types. CRS patients were characterized by altered microbial composition (P = .02) and greater abundance of S aureus (P = .03).

Nasal nitric oxide and sinonasal disease: a systematic review of published evidence

OBJECTIVE

To critically and systematically review the data available on the sinonasal application of nasal nitric oxide measurement, particularly its use as a diagnostic, prognostic, or treatment effect indicator.

DATA SOURCES

EMBASE 1980 to February 10, 2010; Medline 1950 to February 10, 2010; Cochrane Collaboration database; NHS Evidence Health Information Resources database. Review Methods. The databases were searched using a search strategy designed to include manuscripts relevant both to nitric oxide measurement and sinus or nasal problems. A title search was carried out on these manuscripts to select those relevant to clinical or basic science aspects of nitric oxide measurement. A subsequent abstract search selected those manuscripts concerning the application of nitric oxide measurement to sinonasal problems. The manuscripts selected were subject to a full-text review to extract data sets of nasal nitric oxide readings for different patient groups.

RESULTS

Initially, 1088 manuscripts were selected. A title search found 335 manuscripts of basic scientific or clinical interest. An abstract search found 35 manuscripts directly relating to nitric oxide measurement in sinonasal disease. Full-text analysis produced 20 studies with extractable data on nasal nitric oxide levels in clearly defined patient groups. Studies did not show sufficient homogeneity to enable substantial meta-analysis of aggregated data.

CONCLUSION

Current evidence shows that nasal nitric oxide is not a clinically useful measure for sinonasal disease. Although there is some evidence that sinus surgery is associated with lowered nasal nitric oxide levels, there is no evidence that this is associated with deterioration in sinus health.

Human lysozyme has fungicidal activity against nasal fungi

BACKGROUND

The cationic antimicrobial peptide lysozyme is the most prevalent innate immune protein in nasal secretions but there is a paucity of research regarding its role in paranasal sinus disease. Lysozyme is generally regarded as an antibacterial agent; however, some data suggest activity toward yeast. This study was designed to determine if lysozyme displays fungicidal activity toward fungi commonly identified in patients with chronic rhinosinusitis (CRS) or fungal sinusitis.

METHODS

Using a colony-forming unit assay the fungicidal activity of lysozyme (0, 0.5, 5, and 50 micromolar; 0- to 7-hour treatment) was tested against strains of Aspergillus fumigatus, the yeast Candida albicans, and other fungi commonly identified in mucin of patients with CRS. Fungi cultured directly from the mucin of two CRS patients were also tested to determine if they were resistant to the fungicidal activity of lysozyme.

RESULTS

The fungicidal effect of lysozyme was both concentration and time dependent. After 7-hour treatment lysozyme (5 micromolar) had >80% fungicidal activity against A. fumigatus, Penicillium sp., Acremonium sp., C. albicans, and Candida parapsilosis. The fungicidal activity of lysozyme toward Alternaria alternata could not be determined. Lysozyme was also fungicidal toward the clinical isolates A. fumigatus and Aspergillus terreus cultured from the mucin of CRS patients.

CONCLUSION

Lysozyme displays fungicidal activity toward many fungi commonly identified in patients with CRS, as well as clinical fungi isolates cultured from the mucin of CRS patients. Additional studies are required to determine the regulation of lysozyme in CRS.

Human sinonasal epithelial cells direct dendritic function and T-cell T helper 1/T helper 2 skewing following Aspergillus exposure

BACKGROUND

In lower airway disease such as asthma, epithelial cells have been shown to be potent regulators of dendritic cell (DC) functions. However, it is unclear how human sinonasal epithelial cells (HSNECs) from patients with sinusitis regulate DC functions. Therefore, in these studies we investigated the ability of Aspergillus fumigatus exposed HSNECs to regulate DC antigen uptake, maturation, and direction of T-cell T helper 1 (Th1)/Th2 skewing.

METHODS

Primary HSNECs were cultured from control (n = 8), chronic sinusitis without nasal polyps (CRSsNP) (n = 9), and chronic sinusitis with nasal polyps (CRSwNP) (n = 7) patients and exposed to Aspergillus. Conditioned media was placed upon monocyte-derived DCs from healthy controls. DC antigen uptake was assessed by dextran-fluorescein isothiocyanate (FITC) uptake. DC differentiation and maturation was assessed by immunostaining for CD209, CD80, and CD86 followed by flow cytometric analysis. DC direction of T-cell Th1/Th2 skewing was evaluated by immunostaining followed by intracellular flow cytometric analysis for interferon (IFN)-γ and interleukin (IL)-5.

RESULTS

Control and CRSsNP HSNECs have the capacity to stimulate DC antigen uptake, differentiation, and maturation following Aspergillus exposure. CRSwNP HSNECs stimulate DC activation independent of Aspergillus exposure. Furthermore, Aspergillus-exposed CRSwNP HSNECs skew T-cells toward a Th2 phenotype.

CONCLUSION

CRSwNP-derived HSNECs stimulate DC maturation and Th2 skewing independent of Aspergillus exposure. However, control and CRSsNP HSNECs induce DC maturation and Th2 skewing after Aspergillus exposure. These in vitro studies demonstrate that HSNECs are key regulators of DC functions in the sinus microenvironment.

Chitinolytic Activity in Nasal Polyps

Background

Chitin is a recognition element for tissue infiltration by innate cells implicated in allergy and immunity. This process can be negatively regulated by vertebrate chitinases. Both acidic mammalian chitinase (AMCase) and chitotriosidase (ChT) have chitinolytic activity. This study aimed to determine the activities of AMCase and ChT in nasal polyps (NPs), as well as their in situ localization in NP tissue.

Methods

AMCase and ChT activities in NPs were compared with those in inferior turbinate tissue samples. Tissue samples were measured for AMCase and ChT activities at a range of pHs using the fluorogenic substrate 4-methylumbelliferyl-beta-D-N,N′,N″-triacetyl-chitotriose. Double immunofluorescent staining for the localization of both AMCase and ChT was performed using NP cryosections.

Results

Both AMCase and ChT displayed markedly increased chitinolytic activity in all NPs, compared with inferior turbinate tissues. Double immunofluorescent staining revealed that CD68 highlighted monocytes in the submucosa of NP and these cells disclosed coexpression of AMCase and ChT. CD31 detected capillary endothelial cells, but did not express any AMCase and ChT.

Conclusion

The increased chitinolytic activities of AMCase and ChT in NPs may be important in NP pathogenesis, suggesting that inhibition of chitinolytic activity may be a novel therapeutic strategy for the treatment of NPs.

Innate immunity

Innate immunity is an exciting area of research in rhinology because emerging evidence suggests that abnormal local immune responses, rather than pathogen-specific adaptive immunity, may play a more important role in the pathogenesis of chronic rhinosinusitis (CRS). This article reviews important recent research regarding the innate immune system and CRS, with particular focus on the role of pattern recognition receptors, antimicrobial peptides and biofilms, epithelial ciliary function, cystic fibrosis, and cigarette smoking, and on areas for future research and therapy.

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.

Pathological mechanisms and clinical features of eosinophilic chronic rhinosinusitis in the Japanese population

The overall pathological view of paranasal sinus inflammation in the Japanese population has profoundly changed in recent years. Eosinophilic chronic rhinosinusitis (ECRS) is a clinical entity of intractable chronic sinus inflammation accompanied by numerous infiltrations of activated eosinophils in the paranasal sinus mucosa and/or nasal polyps. Several pathologic processes are considered to act in concert to promote the accumulation of eosinophils in ECRS. They include infiltration of progenitor cells, increase in local IL-3, IL-5, IL-13, GM-CSF and eotaxin production, and upregulation of adhesion molecules. The role of nasal allergen sensitization and innate immunity responses in the sinus mucosa has also been proposed in the development of ECRS. Various pathogens including TLRs ligands may trigger an abnormal immune response at the mucosal surface. The objectives of ECRS management should focus directly on inhibition of local eosinophil infiltration. Surgical procedures include widely opening the bony wall septum of every affected sinus and mechanical removal of diseased mucosal lesion. The use of local and/or systemic steroids, leukotriene receptor antagonists, and Th2 cytokine antagonists is recommended. Local administration of steroids is a potent treatment strategy for preventing relapse of nasal polyposis and is considered to be the first-line treatment for ECRS patients.

Defensin-barbed innate immunity: clinical associations in the pediatric population

Defensins and related antimicrobial peptides serve a central role in innate immunity in all species of plants and animals. In humans, defensins are widely expressed, including in neutrophils, skin, and mucosal epithelia. Most defensins are potent antibiotics, and some have chemotactic and toxin-neutralizing activities. Results of recent studies on the homeostatic and disease-fighting activities of human defensins point to a key relevance in several pediatric disorders. Inherited variation in defensin gene expression may contribute to susceptibility to several diseases, including psoriasis and Crohn disease. We review here the recent discoveries in innate immunity that shed light on the potential roles of defensins, and other antimicrobial molecules, in the pathophysiology of common pediatric diseases such as atopic dermatitis, necrotizing enterocolitis, cystic fibrosis, and otitis media.

Fungus: a role in pathophysiology of chronic rhinosinusitis, disease modifier, a treatment target, or no role at all?

Fungal spores, due to their ubiquitous nature, are continuously inhaled and deposited on the airway mucosa. This article focuses on the potential role of fungi in chronic rhinosinusitis (CRS). Five forms of fungal disease affecting the nose and paranasal sinuses have been recognized: (1) acute invasive fungal rhinosinusitis (including rhinocerebral mucormycosis), (2) chronic invasive fungal rhinosinusitis, (3) granulomatous invasive fungal rhinosinusitis, (4) fungal ball (mycetoma), and (5) noninvasive (allergic) fungal rhinosinusitis. There are several potential deficits in the innate and potentially also acquired immunity of CRS patients that might reduce or change their ability to react to fungi. There are not many arguments to suggest a causative role for fungi in CRS with or without nasal polyps. However, due to the intrinsic or induced change in immunity of CRS patients, fungi might have a disease-modifying role.

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.

Differential proteomic analysis of nasal polyps, chronic sinusitis, and normal nasal mucosa tissues

OBJECTIVE

To compare protein expression in nasal polyps, chronic sinusitis, and normal nasal mucosa tissues using proteomic technology.

DESIGN

Cross-sectional survey.

SUBJECTS AND METHODS

Proteins extracted from the three kinds of tissues (seven samples per group) were separated by immobilized pH4-7 gradient two-dimensional gel electrophoresis (2-DE). PDQuest software was used to analyze 2-DE images, and the differentially expressed protein spots were identified with the use of both MALDI-TOF-MS and ESI-Q-TOF-MS. Of the differentially expressed proteins, Cu/ZnSOD and PLUNC were validated with the use of immunohistochemical tests.

RESULTS

High-resolution, reproducible 2-DE patterns were obtained, and 30 differentially expressed protein spots were found. The intensity of Cu/ZnSOD and PLUNC differed significantly on immunohistochemical validation.

CONCLUSION

These differentially expressed proteins are involved in airway inflammatory reaction, immune response, oxidative stress, and metabolic reaction after exposure to irritants. In the future, several of these proteins may prove useful for exploring the pathogenesis of nasal polyps and chronic sinusitis or as objective biomarkers for quantitatively monitoring disease progression or response to therapy.

Clinical and laboratory evidence for Neisseria meningitidis biofilms

Neisseria meningitidis is the etiologic agent of meningococcal meningitis. Carriage of the organism is approximately 10% while active disease occurs at a rate of 1:100,000. Recent publications demonstrate that N. meningitidis has the ability to form biofilms on glass, plastic or cultured human bronchial epithelial cells. Microcolony-like structures are also observed in histological sections from patients with active meningococcal disease. This review investigates the possible role of meningococcal biofilms in carriage and active disease, based on the laboratory and clinical aspects of the disease.

Evidence of Association of Interleukin-1 Receptor-Like 1 Gene Polymorphisms with Chronic Rhinosinusitis

Background

Chronic rhinosinusitis (CRS) is a common complex respiratory disease, with a potential genetic component to its development. The protein encoded by the Interleukin-1 receptor-like 1 (IL1RL1) gene is an important effector molecule of T-helper type 2 responses and may potentially be involved in the persistent inflammatory process observed in CRS. We investigated whether certain polymorphisms in the IL1RL1 gene are differentially present in patients with surgery-unresponsive CRS and in control subjects.

Methods

DNA extracted from an existing population of 206 adult patients with surgery-unresponsive CRS and 196 postal-code-matched controls was used. A set of 15 tagging single nucleotide polymorphisms (SNPs) was selected from the HapMap data set and genotyped. DNA sequencing was performed in a subgroup of 15 CRS patients.

Results

Statistically significant allelic associations with CRS were noted for 5 SNPs (rs10204137, p = 0.04; rs10208293, p = 0.03; rs13431828, p = 0.008; rs2160203, p = 0.03, and rs4988957, p = 0.03). The analysis showed a consistent significant protective effect against CRS for all the SNPs, yielding an odds ratio (OR) ranging from 0.56 to 0.72. The loci rs13431828 showed the highest association with CRS (p = 0.008; OR = 0.56; 95% CI, 0.36–0.86). A subanalysis revealed that the observed associations were stronger among patients with more severe disease. Sequencing identified five additional known nonsynonymous coding SNPs in linkage disequilibrium with genotyped SNPs.

Conclusion

Pending replication of these results, this study suggests that polymorphisms within the IL1RL1 gene may be associated with CRS, conferring a protective effect, particularly among those with severe disease.

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.

Proinflammatory impact of Staphylococcus aureus enterotoxin B on human nasal epithelial cells and inhibition by dexamethasone

BACKGROUND

The pathophysiology and etiology of chronic rhinosinusitis with nasal polyps (CRSwNP) are poorly understood. Although a potential role of staphylococcal enterotoxins (SE) in the pathogenesis of CRSwNP has been detected, additional studies are needed on the impact of SE on nasal epithelial cells. The purpose of this study was to evaluate the impact of Staphylococcus aureus enterotoxin B (SEB) on proinflammatory cytokine/chemokine releases in primary human nasal epithelial cells (HNEC) of subjects with and without CRSwNP and the inhibitory effect of glucocorticoid on it.

METHODS

Epithelial cells of NP and inferior turbinate (IT) were cultured serum free under stimulus of SEB, and interleukin (IL)-1beta, respectively. Furthermore, the inhibitory effect of glucocorticoid on the proinflammatory response was investigated by addition of dexamethasone. In situ hybridization and Western immunoblot assays were used to investigate the proinflammatory impact of SEB on IL-5 and granulocyte macrophage colony-stimulating factor (GM-CSF) mRNA levels and protein production in HNEC.

RESULTS

Results indicate (1) stimulation of HNEC with SEB resulted in increased IL-5 and GM-CSF expression, which could be suppressed by dexamethasone (p < 0.05), and SEB at concentrations of 1-100 ng/mL effectively promoted IL-5 and GM-CSF release by HNEC (p < 0.05); (2) patients with CRSwNP showed a significantly increased expression of IL-5 and GM-CSF in HNEC than patients without CRSwNP (p < 0.05); and (3) the expression of IL-5 and GM-CSF was significantly up-regulated under the stimulus of SEB compared with IL-1beta (p < 0.05).

CONCLUSION

SEB acts as a superantigen and exhibits a dramatic proinflammatory impact on HNEC, which can be inhibited by the addition of glucocorticoid.

Perspectives on the etiology of chronic rhinosinusitis: an immune barrier hypothesis

BACKGROUND

Chronic rhinosinusitis (CRS) has been defined as persistent symptomatic inflammation of the nasal and sinus mucosa resulting from the interaction of multiple host and environmental factors. Recent studies have implicated Alternaria fungi or toxigenic Staphylococcus aureus as critical agents in CRS pathogenesis. The emphasis on environmental agents in CRS etiology has focused interest toward elimination of those agents as the prime mechanism of therapy. This viewpoint is in marked contrast to the current perspective on some other chronic inflammatory epithelial disorders that afflict the skin, lungs, and gut, wherein host factors are believed to predispose to disease expression in the presence of ubiquitous environmental agents.

METHODS

The current review evaluates CRS etiology from this perspective and considers that CRS develops, in part, as an outcome of a dysfunctional host response. Specifically, evidence from our laboratory and others will be reviewed indicating that CRS is associated with a failure of the mechanical and immunologic barriers across the nasal mucosa. The hypothesis would further propose that genetic and epigenetic variation predisposes susceptible individuals to barrier failure in the presence of environmental stress leading to CRS.

RESULTS

From this unifying perspective, bacteria and fungi are seen as disease modifiers rather than primary etiologic agents.

CONCLUSION

The goal is to place concepts of CRS pathophysiology in a framework consistent with a current understanding of chronic inflammation in general and epithelial disease in particular.