Experimentally induced polyps in the sinus mucosa: a structural analysis of the initial stages

Biotherapy and treatment of adult primary chronic rhinosinusitis with nasal polyps: Cellular and molecular bases

The present article reviews the molecular and cellular mechanisms involved in the pathophysiology of chronic rhinosinusitis with nasal polyps (CRSwCRSwNP) and underlying the action mechanisms of biotherapies. Biotherapy uses substances naturally produced by the organism or their specific antagonists targeting a proinflammatory mechanism. CRSwCRSwNP is a form of chronic rhinosinusitis (CRS), which is classically subdivided in to 2 types according to the presence of polyps. In recent years, the concept of endotypes emerged, with a more exhaustive definition of the types of CRS according to inflammatory mechanism, with a view to developing personalized treatments. CRSwNP pathophysiology is poorly understood. Polyps arise from a primary epithelial lesion in a context of chronic local inflammation, mainly type 2 in Europe, implicating eosinophils, IgE, Th2 cytokines (IL-4/IL-13, IL-5) and T and B cells. Biotherapy seems promising in CRSwNP. The present review details the various pathophysiological pathways underlying the action mechanisms of biotherapies, and the various published studies, assessing efficacy and mode of action in the treatment of CRSwNP.

Interleukin-17A Expression Correlated with the Prognosis of Chronic Rhinosinusitis with Nasal Polyps and the Anti-Interleukin-17A Effect in a Murine Nasal Polyps Model

OBJECTIVE

To investigate the expression of interleukin-17A (IL-17A) in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and to analyze its effect on prognosis and to explore the role and mechanism of anti-IL-17A effect in vivo by establishing a murine nasal polyps (NP) model.

METHODS

Patients with CRSwNP who underwent endoscopic sinus surgery and matched control subjects were collected. We investigated IL-17A expression in human NP tissues using immunohistochemistry and analyzed their clinical features, including Lund-Mackay computed tomography scoring (LMCS) before surgery, Lund-Kennedy endoscopic scoring (LKES) before surgery (LKES B), LKES 6 months after surgery (LKES A), and reduction of LKES (LKES R). Then, after establishing the murine NP model to detect the expression and correlation of IL-17A and matrix metalloproteinase-9 (MMP-9) in nasal tissue, we studied nasal lavage fluid and serum by PCR and enzyme-linked immunosorbent assay in vivo. Anti-IL-17A treatment was administered in the murine NP model to confirm the function of IL-17A during the pathogenic processes.

RESULTS

IL-17A expression was upregulated in NP tissues from patients with CRSwNP compared with control subjects (p < 0.001). The number of IL-17A+ cells was significantly negatively correlated with LKES R in patients with CRSwNP (p < 0.01). However, there was no significant correlation between IL-17A and LMCS or LKES B (all p < 0.05). Further, IL-17A and MMP-9 were more abundant in nasal mucosa of the murine NP model compared with that of control mice (all p < 0.05), and severe polypoid lesions were apparently observed in murine NP models. Anti-IL-17A treatment downregulated the mRNA and protein expression of MMP-9 in nasal mucosa and reduced the number of polypoid lesions in the murine NP model (all p < 0.05).

CONCLUSION

Our results suggest that IL-17A plays a crucial role and may affect the prognosis of CRSwNP. Anti-IL-17A treatment may reduce the formation of polypoid lesions through inhibition of MMP-9 expression.

The Effect of Topical Corticosteroid on Basic Fibroblast Growth Factor in Nasal Polyp Tissue

Background

The etiology of nasal polyposis and pathophysiological mechanisms of polyp formation is still poorly understood. Experimental models have suggested that nasal polyp growth requires extracellular matrix formation and is associated with fibroblast proliferation. Intranasal corticosteroids appear to be useful in reducing nasal polypoid lesions and the likelihood of polyp recurrence after surgery. Basic fibroblast growth factor (bFGF) is a potent angiogenesis factor and is mitogenic for a wide range of cell types. We investigated the alteration of bFGF levels in nasal polyp tissue after administration of topical corticosteroid.

Methods

Nasal polyp tissues were obtained from 36 patients with diffuse nasal polyposis before and after topical nasal steroid treatment. As a topical nasal steroid mometasone furoate was given for 4 weeks in a dosage of 200 μg/day. The bFGF levels were measured by competitive enzyme immunoassay method.

Results

The mean levels of tissue bFGF, before and after topical nasal steroid treatment, were 1485 ± 826 ng/mg protein (range, 416–3434 ng/mg) and 1340 ± 749 ng/mg protein (range, 330–3288 ng/mg), respectively. The levels of bFGF in nasal polyps were significantly lower than those before treatment after administration of topical nasal steroid (p = 0.011).

Conclusion

Administration of topical nasal steroid decreases bFGF levels of nasal polyp. It may be suggested that one of the effects in diminishing the size of nasal polyps is by decreasing the bFGF.

Models for the study of nasal and sinus physiology in health and disease: A review of the literature

Objective

Chronic sinusitis is a very common yet poorly understood medical condition with significant morbidity. Hence, it remains an entity that is difficult to treat with unsatisfactory outcomes of current management options. This necessitates research into the etiology and pathophysiology of the condition to enhance our knowledge and the therapeutic options. Unfortunately, this kind of research is not always feasible on human subjects due to practical and ethical limitations. Therefore, an alternative model that simulates the disease had to be found in order to overcome these limitations. These models could either be in vivo or in vitro. The aim of our review is to summarize the research findings and key discoveries of both in vivo and in vitro models of chronic sinusitis that have enhanced our understanding of the condition today and have paved the way for the future research of tomorrow.

Data Sources: PubMed literature review.

Methods

A review of the literature was conducted to identify the main successful in vivo and in vitro models for chronic sinusitis.

Results

Creating a successful model for chronic sinusitis is no easy task. Over the years, both in vivo animal models and in vitro tissue culture models were proposed, with each model having its accolades and pitfalls, with the ideal model remaining elusive to this day. However, advancing three‐dimensional cell culturing techniques seems to be a promising new way to find a more accurate model.

Conclusion

None of the current models is perfect for a thorough study of chronic sinusitis. However, three‐dimensional cell cultures have the potential to bridge the gap between in vivo and in vitro studies.

Level of Evidence

NA

IL-25-induced activation of nasal fibroblast and its association with the remodeling of chronic rhinosinusitis with nasal polyposis

Background and objective

Interleukin (IL)-25 has been shown to play an important role in the pathogenesis of chronic rhinosinusitis with nasal polyps. Nasal polyps are associated with chronic inflammation of the mucous membranes in the paranasal sinuses and are involved in extracellular matrix (ECM) accumulation. The aim of this study is to evaluate the effects of IL-25 on myofibroblast differentiation, ECM production and the expression of matrix metalloproteinases in nasal polyp derived fibroblasts (NPDFs) and to determine the molecular mechanism underlying these processes.

Materials and methods

A total of 40 patients were enrolled in this study for Immunofluorescence studies. Expression of IL17 receptor B was evaluated by real time reverse transcription polymerase chain reaction (PCR) in NPDFs. NPDFs were stimulated with IL-25 for 48 h in the presence or absence of mitogen-activated protein kinase (MAPK) and NF-κB inhibitors or small interfering RNAs (siRNA). The protein levels of fibrosis active mediators were examined using western blotting. Fibroblast migration was evaluated with a scratch assay. The total collagen amount was analyzed with the Sircol collagen assay.

Results

IL-25 induced α-SMA, fibronectin, and MMP-1 and -13, which were dependent on IL-17RB. IL-25 also induced activation of NF-κB and mitogen-activated protein kinase (MAPKs). By using the specific inhibitor of ERK, p38, JNK and NF-κB (U, SB, SP and Bay), we found that IL-25-induced expressions of α-SMA, fibronectin, and MMPs was regulated by the signaling pathways of MAPKs and NF-κB. IL-25 also induces α-SMA, fibronectin, and MMPs expression through IL-17RB-dependent pathways in NPDFs. The increased migration ability induced by IL-25 was suppressed by the specific inhibitors of MAPKs and NF-κB.

Conclusion

Our data indicate that IL-25 induced myofibroblast differentiation, fibronectin production, and MMP-1 and -13 expressions through the signaling pathways of MAPKs and NF-κB. in NPDFs and increased expression of IL-25 were also involved in the pathogenesis of nasal polyposis by affecting nasal fibroblasts in chronic rhinosinusitis with nasal polyps.

Wogonin inhibits transforming growth factor β1-induced extracellular matrix production via the p38/activator protein 1 signaling pathway in nasal polyp-derived fibroblasts

BACKGROUND

Wogonin has been shown to have antifibrotic and anti-inflammatory effects in the lower airway. The purpose of this study was to evaluate the effects of wogonin on transforming growth factor (TGF) β1-induced myofibroblast differentiation, extracellular matrix production, migration, and collagen contraction, and to determine the molecular mechanisms of wogonin in nasal polyp-derived fibroblasts (NPDF).

METHODS

NPDFs were isolated from nasal polyps from eight patients. TGF-β1-induced NPDFs were treated with wogonin. Cytotoxicity was evaluated by using a 3-(4,5- dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide assay. Fibroblast migration was evaluated with transwell and scratch migration assays. The expression levels of α-smooth muscle actin, fibronectin, phosphorylated-p38, and c-Fos were determined by Western blot and/or reverse transcription-polymerase chain reaction. The total collagen amount was analyzed with the Sircol collagen assay, and contractile activity was measured by a collagen gel contraction assay.

RESULTS

Wogonin (0-60 μM) had no significant cytotoxic effects on TGF-β1-induced NPDFs. Migration of NPDFs was significantly inhibited by wogonin treatment. The expression levels of α-smooth muscle actin and fibronectin were significantly reduced in wogonin-treated NPDFs. Collagen production and contraction were also significantly decreased by wogonin treatment. Wogonin markedly inhibited activation of the p38/activator protein 1 pathway in TGF-β1-induced NPDFs.

CONCLUSION

These results indicated that wogonin may inhibit TGF-β1-induced myofibroblast differentiation, extracellular matrix production, migration, and collagen contraction through the p38/activator protein-1 pathway in NPDFs.

Animal Models in CRS and Pathophysiologic Insights Gained: A Systematic Review

OBJECTIVE

Chronic rhinosinusitis (CRS) is a multifactorial inflammatory disease. In particular, CRS with eosinophilic features and/or nasal polyps (NPs) is often recalcitrant to current treatment; thus, appropriate animal models are mandatory to elucidate the pathogenesis of CRS and develop novel and efficient treatment modalities. The author reviewed the recently proposed animal models in CRS and discussed the pathophysiologic insights gained. Data Sources: Articles in the English language referenced in MEDLINE/PubMed from the year 2006 onward (for last 10 years). Review Methods: Review of the literature regarding animal models and related pathologic insights in CRS.

RESULTS

Mouse, rabbit, and sheep models of CRS have been used for studying the pathogenesis of CRS. Most of researchers adopted animal models of CRS to prove any molecular mechanisms or therapeutic efficacy. In vitro or human findings and related hypothesis were evaluated in vivo using these models. In addition, novel therapeutic candidates for CRS with or without NP have been applied to animal models.

CONCLUSION

Animal models have elicited insights into the pathogenesis of CRS and also have been useful in testing new treatment modalities. Although there are still clear limitations in the animal studies, newly proposed or revised animal models would be helpful to understand the exact pathophysiology of CRS.

Ischemia-modified albumin, brain natriuretic peptide, and growth differentiation factor-15 levels in patients with nasal polyps

OBJECTIVE

Nasal polyps (NP) are a chronic inflammatory disease of the nasal mucosa; their etiology is suspected to involve oxidative stress. Growth differentiation factor-15 (GDF-15), brain natriuretic peptide (BNP), and ischemia-modified albumin (IMA) are biomarkers used especially in the early diagnosis and follow-up of cardiovascular diseases. The aim of this study was to assess levels of serum GDF-15, BNP, and IMA in patients with NP and to compare them with those of healthy subjects.

METHODS

This was a prospective study enrolling 41 patients with NP and 48 healthy controls, all aged 18-65 years and referred to the Department of Otorhinolaryngology, Head and Neck Surgery, between January 2014 and February 2015. After a 12-h fast, venous blood (3mL) was drawn and centrifuged (3000rpm, 10min) to collect serum. Blood samples were drawn before endoscopic sinus surgery in the NP group. Serum GDF-15, BNP, and IMA levels were measured.

RESULTS

GDF-15, BNP, and IMA levels of patients with NP were statistically significantly higher than in controls and GDF-15 values were higher than the normal upper limit. GDF-15, BNP, and IMA levels were significantly correlated in both groups.

CONCLUSIONS

As GDF-15 is a marker of chronic inflammation and oxidative stress, our finding of increased serum GDF-15 in patients with NP supports the hypothesis that its pathogenesis involves chronic inflammation and oxidative stress.

Interleukin-17A-induced inflammation does not influence the development of nasal polyps in murine model

BACKGROUND

Nasal polyposis associated with chronic rhinosinusitis (CRS) is a chronic inflammatory disease that is characterized by infiltration of many inflammatory cells. Meanwhile, interleukin (IL)-17A is a well-known proinflammatory cytokine that induces both eosinophilic and neutrophilic inflammation. We investigated the role of IL-17A in the development of nasal polyps in the CRS murine model.

METHODS

Eosinophilic CRS with nasal polyps was induced by using ovalbumin (OVA) and Staphylococcus aureus enterotoxin B (SEB) in wild-type BALB/c and IL-17A knockout (KO) mice. Histopathologic changes of the sinonasal cavity were evaluated using hematoxylin and eosin, Periodic acid-Schiff, Sirius red, Masson's trichrome, and immunohistochemistry. The levels of total and OVA-specific immunoglobulin Es (IgEs) in sera were measured using enzyme-linked immunosorbent assay. The expression levels of IL-4, IL-5, and interferon-γ (IFN-γ) in the nasal mucosa were assessed by quantitative real-time polymerase chain reaction.

RESULTS

Under the IL-17A deficiency, total and OVA-specific IgEs in sera were reduced significantly. Infiltration of both eosinophils and neutrophils into the nasal mucosa, subepithelial fibrosis, and goblet cell count also decreased significantly in IL-17A KO mice treated with both OVA and SEB compared with those in the wild-type counterpart. However, there were no significant differences in the number of polypoid lesions among groups. Meanwhile, IL-4 increased and IFN-γ decreased in the nasal mucosa in IL-17A KO mice treated with both OVA and SEB.

CONCLUSION

This study suggests that even though IL-17A plays an important role in both nasal inflammation and remodeling, it does not influence the development of nasal polypoid lesions.

Expression of the receptor for advanced glycation end products, a target for high mobility group box 1 protein, and its role in chronic recalcitrant rhinosinusitis with nasal polyps

A receptor for advanced glycation end products (RAGE) and its ligand high mobility group box 1 (HMGB1) protein has been linked to several chronic diseases, and acts as a trigger for inflammation signaling. Here, we study RAGE and HMGB1 expression in chronic, recalcitrant rhinosinusitis with nasal polyps (CRSwNP) to determine its potential clinical significance, i.e., disease recurrence and severity. RAGE and HMGB1 expression in CRSwNP was evaluated by immunohistochemistry in epithelial cells of fresh sinonasal mucosa samples obtained from the patients diagnosed with recalcitrant CRSwNP (n = 25) and normal control mucosa (NC) (n = 26). RAGE and HMGB1 expression levels in tissues were correlated with disease severity assessed by nasal endoscopy, CT scan, number of previous sinus surgeries, allergy status and nasosinusal microbiology. RAGE and HMGB1 were moderately or strongly expressed in CRSwNP tissue. No or weak RAGE expression was found in NC. HMGB1 was equally strongly expressed in NC. We observed a strong correlation between RAGE and disease severity, recurrence, undergone operations, asthma and aspirin exacerbated respiratory disease (AERD). Elevated RAGE expression is associated with increased disease severity, as well as allergy and AERD in patients with recalcitrant CRSwNP. It is possible that the explanation for recurrent CRSwNP pathogenesis might be related to RAGE overexpression with subsequent sinus mucosa hyperproliferation, necessitating several operations.

Lipopolysaccharide induces pro-inflammatory cytokines and MMP production via TLR4 in nasal polyp-derived fibroblast and organ culture

Nasal polyposis is characterized by persistent inflammation and remodeling in sinonasal mucosa. Toll-like receptors (TLRs) play a role in the innate immune response to microbes in the sinonasal cavity. The aim of this study was to evaluate whether nasal polyp-derived fibroblasts (NPDFs) and organ-cultured nasal polyps can synthesize pro-inflammatory cytokines and matrix metalloproteinases (MMPs) after exposure to lipopolysaccharide (LPS), a TLR4 agonist. NPDFs and organ-cultured nasal polyps were isolated from nasal polyps of 8 patients and exposed to LPS. The mRNA and protein expression levels of TLRs, cytokines, and MMPs were determined using a gene expression microarray, real-time RT-PCR, western blot analysis, enzyme-linked immunosorbent assay, and immunofluorescence staining. The enzymatic activities of MMPs were analyzed using collagen or gelatin zymography. The protein expression level of MMP-1 increased in nasal polyp tissues compared to inferior turbinate tissues. LPS induced mRNA expression of TLR4, IL-6, IL-8, and MMP-1 and activated MAPK signaling in NPDFs. LPS promoted the release of interleukin (IL)-6 through extracellular signal-related kinase (ERK) and IL-8 through ERK and c-Jun N-terminal kinases (JNK). Production of IL-6 and IL-8 was induced by PI3K/Akt signaling in LPS-stimulated NPDFs. LPS increased the transcript and protein expression levels of MMP-1 and induced collagenase activity of MMP-1 via ERK and p38, but did not induce gelatinase activity of MMP-2 and MMP-9. LPS from Rhodobacter sphaeroides (LPS-RS) inhibited the stimulatory effects of LPS in NPDFs as well as in organ culture of nasal polyp. LPS triggers immune response via TLR 4 and activates MAPK and PI3K/Akt signaling pathway, which is involved in remodeling of nasal polyps.

Deprived TLR9 expression in apparently healthy nasal mucosa might trigger polyp-growth in chronic rhinosinusitis patients

Background

The origin of nasal polyps in chronic rhinosinusitis is unknown, but the role of viral infections in polyp growth is clinically well established. Toll-like receptors (TLRs) have recently emerged as key players in our local airway defense against microbes. Among these, TLR9 has gained special interest in viral diseases. Many studies on chronic rhinosinusitis with nasal polyps (CRSwNP) compare polyp tissue with nasal mucosa from polyp-free individuals. Knowledge about changes in the turbinate tissue bordering the polyp tissue is limited.

Objectives

To analyse the role of TLR9 mediated microbial defense in tissue bordering the polyp.

Methods

Nasal polyps and turbinate tissue from 11 patients with CRSwNP and turbinate tissue from 11 healthy controls in total were used. Five biopsies from either group were analysed immediately with flow cytometry regarding receptor expression and 6 biopsies were used for in vitro stimulation with a TLR9 agonist, CpG. Cytokine release was analysed using Luminex. Eight patients with CRSwNP in total were intranasally challenged with CpG/placebo 24 hours before surgery and the biopsies were collected and analysed as above.

Results

TLR9 expression was detected on turbinate epithelial cells from healthy controls and polyp epithelial cells from patients, whereas TLR9 was absent in turbinate epithelial cells from patients. CpG stimulation increased the percentage cells expressing TLR9 and decreased percentage cells expressing VEGFR2 in turbinate tissue from patients. After CpG stimulation the elevated levels of IL-6, G-CSF and MIP-1β in the turbinate tissue from patients were reduced towards the levels demonstrated in healthy controls.

Conclusion

Defects in the TLR9 mediated microbial defense in the mucosa adjacent to the anatomic origin of the polyp might explain virus induced polyp growth. CpG stimulation decreased VEGFR2, suggesting a role for CpG in polyp formation. The focus on turbinate tissue in patients with CRSwNP opens new perspectives in CRSwNP-research.

Metformin reduces TGF-β1-induced extracellular matrix production in nasal polyp-derived fibroblasts

BACKGROUND AND OBJECTS: Metformin is widely used to treat type 2 diabetes mellitus, and adenosine monophosphate-activated protein kinase (AMPK) is thought to be the target that mediates its effects. Recently, it has been demonstrated that metformin has antifibrotic effects beyond its antihyperglycemic action. The purposes of this study were to investigate the effect of metformin on TGF-β1-induced myofibroblast differentiation (α-smooth muscle actin [α-SMA]) and extracellular matrix (ECM) production and to determine the underlying mechanism of the action of metformin in nasal polyp-derived fibroblasts (NPDFs).

STUDY DESIGN

Basic research.

SETTING

The rhinology laboratory of Korea University Guro Hospital, Seoul, Korea.

METHODS

NPDFs from 7 patients were incubated with TGF-β1 and treated with metformin or compound C, an inhibitor of AMPK. To determine the proliferation rate of nasal fibroblasts, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was performed. The expression levels of α-SMA and fibronectin were determined by reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescent staining. Phosphorylation of AMPK and phosphorylation of Smad2/3 were evaluated by Western blot analysis.

RESULTS

In TGF-β1-induced NPDFs, metformin inhibited the expression of α-SMA and fibronectin, as confirmed by both RT-PCR and Western blot analysis. Metformin increased the phosphorylation of AMPK and the expression levels of α-SMA and fibronectin. However, compound C reversed these effects. Metformin inhibited TGF-β1-induced phosphorylation of Smad2/3.

CONCLUSIONS

This study showed that metformin inhibits TGF-β1-induced myofibroblast differentiation and ECM production in NPDFs via the Smad2/3 pathway. AMPK can be a therapeutic target for the prevention of ECM remodeling in nasal polyps.

The development of nasal polyp disease involves early nasal mucosal inflammation and remodelling

Chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by both a chronic inflammation and tissue remodelling; as indicated by extracellular matrix protein deposition, basement membrane thickening, goblet cell hyperplasia and subepithelial edema, with reduced vessels and glands. Although remodelling is generally considered to be consequence of persistent inflammation, the chronological order and relationship between inflammation and remodelling in polyp development is still not clear. The aim of our study was therefore to investigate the pathological features prevalent in the development of nasal polyps and to elucidate the chronological order and relationship between inflammation and remodelling, by comparing specific markers of inflammation and remodelling in early stage nasal polyps confined to the middle turbinate (refer to as middle turbinate CRSwNP) obtained from 5 CRSwNP patients with bilateral polyposis, mature ethmoidal polyps from 6 CRSwNP patients, and normal nasal mucosal tissue from 6 control subjects. Middle turbinate CRSwNP demonstrated significantly more severe epithelial loss compared to mature ethmoidal polyps and normal nasal mucosa. The epithelial cell junction molecules E-cadherin, ZO-1 and occludin were also expressed in significantly lower amounts in mature ethmoidal polyps compared to healthy mucosa. Middle turbinate CRSwNP were further characterized by significantly increased numbers of subepithelial eosinophils and M2 type macrophages, with a distinct lack of collagen and deposition of fibronectin in polyp part. In contrast, the turbinate area of the middle turbinate CRSwNP was characterized by an increase in TGF-β activated myofibroblasts expressing α-SMA and vimentin, an increase in the number of pSmad2 positive cells, as well as increased deposition of collagen. These findings suggest a complex network of processes in the formation of CRSwNP; including gross epithelial damage and repair reactions, eosinophil and macrophage cell infiltration, and tissue remodelling. Furthermore, remodelling appears to occur in parallel, rather than subsequent to inflammation.

Epigallocatechin-3-gallate inhibits collagen production of nasal polyp-derived fibroblasts

Nasal polyps are chronic inflammatory conditions characterized by myofibroblast differentiation and extracelluar matrix accumulation. The major catechin from green tea is (-)-epigallocatechin-3-gallate (EGCG), which has garnered attention for its potential to prevent oxidative stress-related diseases. The purpose of this study was twofold: (i) to determine the effect of EGCG on fibroblast differentiation into myofibroblasts and extracellular matrix accumulation in transforming growth factor (TGF)-β1-induced nasal polyp-derived fibroblasts (NPDFs) and (ii) to determine if the antioxidative effect of EGCG on reactive oxygen species (ROS) production in TGF-β1-induced NPDFs is involved in the aforementioned processes. TGF-β1-induced NPDFs were treated with or without EGCG. α-smooth muscle actin (α-SMA) and collagen type I mRNA were analyzed by reverse transcription-polymerase chain reaction. α-SMA protein was also detected using immunofluorescent staining. The amount of total soluble collagen was analyzed by Sircol collagen assay. ROS activity was measured by the nitroblue tetrazolium reduction assay and visualized by fluorescent microscopy. EGCG significantly inhibited expressions of α-SMA and collagen type I mRNA and reduced α-SMA and collagen protein levels at concentrations of 10-20 µg/mL. EGCG also inhibited TGF-β1-induced ROS production at the same concentrations. These results suggest the possibility that EGCG may be effective at inhibiting the development of nasal polyps through an anti-oxidant effect.

Effects of Histone Deacetylase Inhibitor on Extracellular Matrix Production in Human Nasal Polyp Organ Cultures

Background

Nasal polyposis is associated with a chronic inflammatory condition of the sinonasal mucosa and involves myofibroblast differentiation and extracellular matrix (ECM) accumulation. Epigenetic modulation by histone deacetylase (HDAC) inhibitors including trichostatin A (TSA) has been reported to have inhibitory effects on myofibroblast differentiation in lung and renal fibroblasts. The purpose of this study was to investigate the inhibitory effect of TSA on myofibroblast differentiation and ECM production in nasal polyp organ cultures.

Methods

Nasal polyp tissues from 18 patients were acquired during endoscopic sinus surgery. After organ culture, nasal polyps were stimulated with TGF-beta1 and then treated with TSA. Alpha-smooth muscle actin (α-SMA), fibronectin, and collagen type I expression levels were examined by reverse transcription–polymerase chain reaction (PCR), real-time PCR, Western blot, and immunofluorescent staining. HDAC2, HDAC4, and acetylated H4 expression levels were assayed by Western blot. Cytotoxicity was analyzed by the terminal deoxynucleotidyl transferase biotin–dUTP nick end labeling assay.

Results

The expression levels of α-SMA, fibronectin, and collagen type 1 were increased in nasal polyp after transforming growth factor (TGF) beta1 treatment. TSA-inhibited TGF-beta1 induced these gene and protein expression levels. Furthermore, TSA suppressed protein expression levels of HDAC2 and HDAC4. However, TSA induced hyperacetylation of histones H4. Treatment with TGF-beta1 with or without TSA did not have cytotoxic effect.

Conclusion

These findings provide novel insights into the epigenetic regulation in myofibroblast differentiation and ECM production of nasal polyp. TSA could be a candidate of a therapeutic agent for reversing the TGF-beta1–induced ECM synthesis that leads to nasal polyp development.

Staphylococcus aureus enterotoxin B contributes to induction of nasal polypoid lesions in an allergic rhinosinusitis murine model

BACKGROUND

Studies on the pathophysiology of nasal polyps in human subjects have been limited; thus an animal model is needed. There is increasing evidence supporting the role of Staphylococcus aureus enterotoxin B (SEB) in the pathogenesis of nasal polyposis. The aim of this study was to investigate the histological and immunologic effects of SEB on the formation of nasal polypoid lesions in an allergic rhinosinusitis murine model.

METHODS

After induction of an ovalbumin (OVA)-induced allergic rhinosinusitis, OVA with SEB (5 or 500 ng) was instilled into the nasal cavity of mice for 8 weeks. Control mice did not receive SEB or OVA instillation. Histopathological changes were observed using hematoxylin and eosin, Sirius red, Giemsa, Masson's trichrome, and Alcian blue stains. The levels of interleukin (IL)-4, IL-5, IL-8, IL-13, eotaxin, interferon gamma, total IgE, and OVA-specific IgE from serum or nasal lavage fluid were measured using enzyme-linked immunosorbent assay.

RESULTS

The group treated with OVA plus 5 ng of SEB had significantly more mucosal lesions with epithelial disruption and nasal polypoid lesions than mice treated with OVA only, showing a significant increase in the infiltration of total inflammatory cells, eosinophils, and lymphocytes than the other groups. Levels of IL-5, eotaxin, and OVA-specific IgE in nasal lavage fluid were increased in the group treated with OVA plus 5 ng of SEB than in the other groups. A higher number of secretory cells in the groups treated with OVA plus SEB was observed than in other groups.

CONCLUSION

Low-dose SEB induced nasal polypoid lesions with an increased eosinophilic infiltration in an allergic rhinosinusitis murine model.

State of the art treatment of nasal polyposis

BACKGROUND

Nasal polyposis represents the end point of multiple inflammatory pathways and controversy continues as to the exact roles of medical and surgical approaches in the management of nasal polyposis.

METHODS

A combination of both is often required to manage polyps adequately with surgery and intranasal steroids remaining the mainstay of therapy.

RESULTS

Fortunately, new technological advances are making surgery safer and more efficient. In the postoperative period, debridement is effective in reducing the formation of adhesions, and topical medications may play a beneficial role in preventing polyp reformation.

CONCLUSION

Additional investigations into the optimal perioperative medical management is needed to ensure optimal surgical outcomes.

Effect of Simvastatin on Transforming Growth Factor Beta-1–Induced Myofibroblast Differentiation and Collagen Production in Nasal Polyp-Derived Fibroblasts

Background

Statins are the most commonly prescribed drugs for the treatment of hypercholesterolemia. Statins exert not only lipid-lowering but also other cellular effects, including antifibrotic properties. The purpose of this study was to determine the effect of simvastatin on transforming growth factor (TGF)-beta-1–induced myofibroblast differentiation and collagen production in nasal polyp-derived fibroblasts (NPDFs) and to verify the mechanism of the effect of simvastatin in TGF-beta-1–induced myofibroblast differentiation in NPDFs.

Methods

NPDFs were pretreated with simvastatin with or without mevalonate or Y-27643 for 2 hours before induction by TGF-beta-1. The expression of alpha-smooth muscle actin (SMA) and collagen type IV mRNA was determined by a reverse transcription-polymerase chain reaction, and the expression of alpha-SMA protein was determined by immunofluorescent cytochemical staining. Total soluble collagen production was analyzed by the SirCol collagen dye-binding assay (Biocolor, Belfast, U.K.). Phosphorylation of Smad 2/3 was evaluated by Western blot analysis.

Results

In TGF-beta-1–induced NPDFs, simvastatin significantly inhibited the expressions of α-SMA and collagen type IV mRNA and reduced alpha-SMA and collagen protein levels. Pretreatment with mevalonate reversed the effect of simvastatin. The expression of alpha-SMA mRNA and protein was significantly decreased by pretreatment with Y-27632. The TGF-beta-1–induced expression of pSmad 2/3 protein was notably decreased by pretreatment with simvastatin.

Conclusion

We showed that simvastatin inhibits TGF-beta-1–induced myofibroblast differentiation (expression of alpha-SMA) and collagen production in NPDFs and Rho/Rock and TGF-β/Smad signaling is involved as an underlying mechanism. The results of our study suggest that simvastatin is a possible candidate for the suppression of nasal polyp formation.

Increased expression of angiogenin in nasal polyps

BACKGROUND

The aim of this study was to determine the expression and distribution of angiogenin in nasal polyps and to evaluate the implication of such expression with respect to the development of nasal polyps.

METHODS

Normal inferior turbinate mucosa was obtained from 20 patients undergoing surgery for augmentation rhinoplasty. Nasal polyp samples were obtained from 20 patients undergoing endoscopic sinus surgery for chronic polypoid rhinosinusitis. A semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed for angiogenin mRNA. Sections of nasal polyps were immunostained for localization of angiogenin and quantitatively analyzed using computer-based image analysis. Western blot analysis was performed.

RESULTS

Semiquantitative RT-PCR and Western blot analysis showed that angiogenin expression in nasal polyps was increased compared with that in normal nasal mucosa. Using immunohistochemical staining, moderate-to-high levels of angiogenin were mainly localized in the infiltrating inflammatory cells of nasal polyps and faint staining was found in normal nasal mucosa.

CONCLUSION

These results suggest that angiogenin may play a role in the pathophysiology of nasal polyps.

Effect of antioxidants on the clinical outcome of patients with nasal polyposis

AIM

To investigate the therapeutic effects of antioxidants on the clinical and biochemical outcome of patients with nasal polyposis.

METHODS

Thirty-four patients with nasal polyposis were divided into two groups receiving either intranasal steroid or intranasal steroid plus per-oral vitamins A, C and E and selenium. Paranasal sinus computed tomography, endoscopy, and polyp tissue and serum sampling were conducted pre- and post-therapy. Serum levels of malondialdehyde, superoxide dismutase, nitrite and myeloperoxidase and tissue levels of malondialdehyde and superoxide dismutase were measured. Group results were compared using the Mann-Whitney U test and Wilcoxon signed-rank test.

RESULTS

Both groups had significantly lower tissue parameters, computed tomography scores and serum malondialdehyde levels, comparing pre- versus post-treatment results. Post-treatment, the steroid plus antioxidant group had significantly lower tissue malondialdehyde levels and a greater fall in tissue and serum malondialdehyde, compared with the steroid group.

CONCLUSION

Serum and tissue levels of malondialdehyde (an oxidative marker) were significantly decreased by adding antioxidants to standard therapy. This is the first report of the positive effects of adding antioxidants to steroid therapy for nasal polyposis.

Experimentally induced eosinophilic polyps in rabbit sinuses

BACKGROUND

Nasal polyps are one of the most common findings of physical examination in the otolaryngology area and the experimental model of nasal polyps in the rabbit maxillary sinus is helpful for clarifying the mechanism of polyp formation. Several protocols have been reported for this model, but most of them involved infectious polyps without eosinophil infiltration. We have attempted to establish a novel rabbit model of polyps associated with eosinophil infiltration.

METHODS

Rabbits were either untreated (group A) or sensitized with ovalbumin (OVA; groups B-D). After repeated exposure to OVA, some animals further received valine-glycine-serine-glutamine (group C) or poly-L-arginine (group D) in their maxillary sinuses for 4 weeks. Subsequently, sinus tissues were dissected and subjected to histological analysis. The changes in mRNA expression were analyzed by DNA microarray.

RESULTS

Remarkable histological changes were observed in groups C and D but not in group B in eosinophil number in the maxillary sinus mucosa, the width of the lamina propria, and polyp scoring. These changes in group D were greater than those in group C. DNA microarray analysis revealed that up-regulated genes in group D included those related to inflammation and extracellular matrix metabolism. On the other hand, down-regulated genes in group D involved those related to anti-inflammation.

CONCLUSION

Our results indicate that treatment with inflammatory agents, in combination with an antigen-dependent immune response, could induce nasal polyp formation associated with eosinophil infiltration and mucosal hypertrophy. The gene expression profile supported the clinical relevance of this model.

Surgical management of polyps in the treatment of nasal airway obstruction

In addition to their role in chronic rhinosinusitis and nasal congestion, sinonasal polyps are associated with significant nasal obstruction. Effective long-term treatments remain difficult to pinpoint. Management of these polyps is a difficult challenge for the contemporary otolaryngologist. Medical options vary and include topical and oral steroids; macrolide antibiotics; diuretic nasal washes; and intrapolyp steroid injection. Surgical options include polypectomy and functional endoscopic sinus surgery (FESS). In addition, novel treatments for polyps are introduced with some frequency. This article presents an overview of management options for sinonasal polyps, focusing on the indications, efficacy, and complications of the more common interventions.

Up-regulation of heparanase in the ethmoid sinus mucosa of patients with chronic sinusitis

BACKGROUND

Heparanase (HPA) is known to be involved in tissue remodeling of various organs with inflammatory diseases. The aim of this study was to investigate the level of expression and the pattern of distribution of HPA in normal human sinus mucosa, inflammatory sinus mucosa, and nasal polyps to evaluate the possible effect of HPA on the tissue remodeling of chronic inflammatory sinus mucosa and nasal polyps.

METHODS

Normal sinus mucosa was obtained from the ethmoid sinus during endoscopic reduction in 25 patients with blowout fractures. Inflammatory sinus mucosa and nasal polyps were obtained from 25 patients undergoing endoscopic sinus surgery for chronic sinusitis with nasal polyps. The levels of expression and the pattern of distribution of HPA were evaluated in normal human sinus mucosa, inflammatory sinus mucosa, and nasal polyps, using reverse transcriptase-polymerase chain reaction, immunohistochemical analysis, and Western blot analysis.

RESULTS

HPA mRNA and protein were detected in inflammatory sinus mucosa and nasal polyps but not in normal sinus mucosa. HPA was mainly localized in the vascular endothelium, epithelium, submucosal glands, and inflammatory cells of inflammatory sinus mucosa. In nasal polyps, inflammatory cells and vascular endothelium showed immunopositivity in the entire portion, whereas glands and epithelial cells did not show positivity.

CONCLUSION

Our results indicate that HPA is not constitutively expressed in normal sinus mucosa and is upregulated in chronic inflammatory sinus mucosa and nasal polyps, suggesting that HPA may play an important role in the tissue remodeling in chronic sinusitis.

A relationship between mast cells and alpha-smooth muscle actin-positive cells in the nasal polyps of chronic rhinosinusitis

CONCLUSION

These results suggest that mast cells (MCs) play a role in promoting nasal polyp (NP) formation and progression with alpha-smooth muscle actin (alpha-SMA)-positive cells.

OBJECTIVES

We studied the quantification and the localization of MCs and myofibroblasts in NPs.

PATIENTS AND METHODS

We examined NPs from 12 patients with chronic rhinosinusitis undergoing endoscopic sinus surgery. MCs and myofibroblasts that expressed alpha-SMA were detected immunohistochemically. The numbers of labeled cells were quantified in NPs. These cells were evaluated in the tip, central, and pedicle areas. The number of MCs was compared between low (zone 1), moderate (zone 2), and high (zone 3) zones of alpha-SMA-positive cells.

RESULTS

The number of MCs was significantly higher in pedicle areas than in tip areas of NPs. The distribution of alpha-SMA-positive cells tended to be more remarkable in pedicle areas than in tip and central areas of NPs. The number of MCs was significantly higher in zone 3 than in zone 1 of alpha-SMA-positive cells.

Developing a rabbit model of rhinogenic chronic rhinosinusitis

OBJECTIVE

The purpose of this study was to develop a rabbit model of rhinogenic chronic rhinosinusitis (CRS).

METHODS

New Zealand white rabbits were used and divided into two groups. In group A rabbits, a piece of Merocel (Medtronic-Xomed, Jacksonville, FL) was inserted into one nasal cavity and the other was left undisturbed as control. In group B rabbits, 1 microg phorbol 12-myristate 13-acetate (PMA) was injected into bilateral nasal lateral walls and then a piece of Merocel (Medtronic-Xomed) was inserted into one nasal cavity. At week 2, the Merocel (Medtronic-Xomed) was removed, and computed tomography (CT), nasoendoscopy, and cultures were performed. All examinations were repeated at week 12. Rabbits that had purulent discharge in nasal cavities and sinuses opacification shown in CT scans were diagnosed as having rhinosinusitis. Rabbits with CRS were randomly allocated to receive intravenous ceftriaxone (50 mg/kg/day) for 28 days or nothing. All rabbits with CRS received CT scans, nasoendoscopy, and cultures at week 16.

RESULTS

At week 12, CRS had developed in two controlled nasal cavities, six nasal cavities inserted with Merocel (Medtronic-Xomed), six nasal cavities injected with phorbol 12-myristate 13-acetate (PMA), and seven both PMA-injected and Merocel- (Medtronic-Xomed) inserted nasal cavities. Seven of nine treated CRS sides were clear of opacification after treatment. All non-treated CRS sides had persistent diseases at week 16. There was a significant difference in the CRS incidence (P = .00043) and culture rates (P = .027) between treated and non-treated CRS nasal cavities.

CONCLUSIONS

Our study developed a rabbit model of rhinogenic CRS. This model is easily performed and is reversible by treatment.

Role of hypoxia in inflammatory upper airway disease

PURPOSE OF REVIEW

Hypoxia is a potent stimulus for inflammation and remodeling. Hypoxia develops in chronic sinusitis as shown via tissue oxygen concentrations and colonization with obligate anaerobes. This hypoxia reflects occlusion of the sinus ostia and thereby failure of transepithelial oxygenation, nonvascularized exudates, and the tendency of inflammatory hyperplasia to exceed neovascularization.

RECENT FINDINGS

Hypoxia-induced transcription factors are responsible for transcription of numerous inflammatory cytokines and growth factors, including vascular endothelial growth factor, CXCL8, CCL11, transforming growth factor-beta, inducible nitric oxide synthase, as well as matrix remodeling proteins such as procollagen and matrix metalloproteinases.

SUMMARY

Many diseases, such as asthma, share the tendency to afflict respiratory epithelium of the lower (bronchi) and upper (sinus) airway. Although the histopathology and inflammation of asthma and its associated sinusitis share many features, aggressive fibrosis, polyp formation and intense hyperplasia are not features of asthma, a disease seldom associated with significant chronic hypoxia. In contrast, fibrosis is a cardinal feature of hypoxic diseases of the lungs such as interstitial lung diseases and primary pulmonary hypertension. Arguably, chronic sinusitis can be viewed as reflecting both 'asthma' and 'primary pulmonary hypertension' of the upper airway.

Dual action of TGF-beta1 on nasal-polyp derived fibroblasts

OBJECTIVES

Transforming growth factor beta-1 (TGF-beta1) is a known fibrogenic factor with immunosuppressive properties. We wanted to determine the effect of stimulation with TGF-beta1 on nasal polyp-derived fibroblasts and assess the role this molecule would have in polyp formation and growth.

STUDY DESIGN

Nasal-polyp derived fibroblasts were cultured with or without TGF-beta1, and proliferation and cytokine secretion were measured.

METHODS

Fibroblasts were isolated from nasal polyps following endoscopic surgery. Cells were plated and grown until confluent, after which they were split and used in assays. Cells were stimulated with TGF- beta1 and mRNA collected after 16 hours, supernatants after 72 hours, and proliferation measured after 96 hours of culture.

RESULTS

TGF-beta1 significantly (P < .02) increased proliferation of nasal-polyp derived fibroblasts. We examined the expression of inflammatory cytokines and found that TGF-beta1 decreased expression of CCL2 (MCP-1), CCL5 (RANTES), CCL11 (eotaxin), granulocyte-colony stimulating factor (G-CSF), and GM-CSF (P < .05). In contrast, incubation with TGF-beta1 increased fibronectin, procollagen, vascular endothelial growth factor (VEGF), and TGF-beta2 protein production (P < .05). For select samples, we confirmed that the increased protein production was due to increased mRNA expression.

CONCLUSION

These studies suggest that TGF-beta1 expression in polyp tissue can have dual effects. One role is to act as an anti-inflammatory agent shown by the ability to inhibit pro-inflammatory mRNA and protein production. At the same time, TGF-beta1 expression leads to increases in factors involved in fibrosis and angiogenesis, promoting remodeling and cell growth.

RKIP and BRAF aberrations in human nasal polyps and the adjacent turbinate mucosae

BACKGROUND

Little is known about the implication of BRAF and RKIP expression, or about the incidence of BRAF mutations in the formation of nasal polyposis.

OBJECTIVES

To determine the expression levels of the genes BRAF and RKIP, and to inspect the frequency of BRAF mutations in exons 11, 14 and 15 in human nasal polyps (NP).

PATIENTS AND METHODS

We analyzed 24 human NP specimens and their adjacent inferior and middle turbinates (AIT and AMT), as well as 14 control subjects [bearing 14 Control Inferior Turbinates (CIT) and 14 Control Middle Turbinates (CMT), in total]. The expression pattern of BRAF and RKIP was assessed with real-time RT-PCR. A real-time allele-specific PCR method, in combination with direct sequencing, was performed in order to inspect the frequency of the V600E mutation in exon 15, and to examine mutation status within exons 11 and 14.

RESULTS

The control mucosae presented significantly higher mRNA levels for both genes, compared to the NP and the AIT-AMT. Moreover, in NP, AIT and AMT, RKIP was found to present higher mRNA levels, in relation to the equivalent values of the BRAF gene (P=0.003 in NP; P<0.001 both in AIT and AMT). No mutation was detected in exon 14, whereas a silent mutation (A1380G, G460G) was noted for one NP sample in exon 11. Another NP sample was found to carry two mutations, one T1799A (V600E) and one A1801G (K601E). A significant co-expression of the two genes was noted in NP (P=0.012) and AIT (P=0.019).

CONCLUSION

The results of the expression levels of RKIP and BRAF, reflect the strong connection between the two genes. RKIP could play an important role in the down-regulation of wild-type BRAF, serving thus as an endogenous inhibitor of the MAPK pathway in nasal polyps and their adjacent turbinate mucosa.

Hypoxia stimulates inflammatory and fibrotic responses from nasal-polyp derived fibroblasts

OBJECTIVES/HYPOTHESIS

Chronic sinusitis is primarily an inflammatory disorder characterized by hyperplasia of immune cells and sinus tissue. Nasal mucosal swelling or polyps can occlude the sinus ostia, decreasing the level of oxygen available to the sinus tissue. Hypoxia in many diseases results in increased recruitment of inflammatory cells and release of cytokines. The role of hypoxia in chronic sinusitis is unknown. We hypothesized that hypoxia induces production of mediators that recruit cells into the sinus tissue and are involved in remodeling of the nasal mucosa.

METHODS

We compared data from unstimulated nasal-polyp derived fibroblasts with those cultured in hypoxic (10% O2) and anoxic (0% O2) environments. Changes in mRNA expression and protein levels of cytokines and chemokines were measured along with changes in cellular proliferation.

RESULTS

Hypoxic conditions did not change the proliferative capacity of fibroblasts, whereas anoxia led to a 40% reduction in cellular proliferation (P < .05). Hypoxia led to increases in secretion of many cytokines including vascular endothelial growth factor and CCL11. As a marker of remodeling, procollagen and fibronectin production were significantly increased under hypoxic conditions.

CONCLUSIONS

Hypoxic conditions present in the sinus tissue could increase production of proinflammatory and remodeling cytokines that contribute to the inflammation observed in sinusitis. Surgical intervention may help decrease inflammation by allowing reoxygenation of the sinus cavity and decrease the hypoxic induction of cytokines and remodeling factors.

[Injury and epithelial wound healing: a pathophysiologic hypothesis for nasal and sinus polyposis]

Nasal polyposis (NP), asthma, and chronic bronchitis are chronic inflammatory diseases of the upper airways. They may be caused by injury to the respiratory epithelium in a chronic inflammatory environment. Several studies show that during NP nasal epithelial cells are involved in the overexpression of cytokines and growth factors. Among these, transforming growth factor beta1 (TGF-beta1) appears to play a major role in the genesis of NP. Differentiated respiratory epithelium, obtained from in vivo or in vitro models, is used to study wound healing in inflammatory environments, to elucidate the pathophysiology of NP, and to improve understanding and management of upper airway inflammatory diseases.

Vascular endothelial growth factor and children featuring nasal polyps

BACKGROUND

The aim of this study is to explore the expression of vascular endothelial growth factor within nasal polyps, and the implication of such expression as regards the development of nasal polyps amongst children.

MATERIAL AND METHODS

Sixty children suffering from chronic rhinosinusitis were enrolled in this study. Amongst them, 30 patients featured rhinosinusitis with associated nasal polyps. A biopsy specimen was taken from the stalk or the base of the nasal polyp for nasal-polyp sufferers, and the ethmoid sinus for study participants who featured no nasal polyps. The primary lesions biopsied were immunohistochemically stained with a specific endothelial-cell marker and also stained for the presence of vascular endothelial growth factor. The specific level of vascular endothelial growth factor and the mean number of blood vessels present in a visual microscopic (biopsied-specimen) field were calculated under light microscopy (x400).

RESULTS

The number of vascular endothelial growth factor-expressing cells for the nasal-polyp group and for the sinusitis group was, respectively, 20.8+/-4.0 and 11.5+/-3.4 per visual field. Correspondingly, the mean intra-polyp blood-vessel density for the nasal-polyp group and that for the control group was, respectively, 10.5+/-2.6 and 5.0+/-1.9 per visual field. The mean intra-polyp blood-vessel density and the number of vascular endothelial growth factor-expressing cells proved to be significantly greater amongst individuals from the nasal-polyp group than was the case for their analogs from the sinusitis group (P<0.01, for both). The presence of vascular endothelial growth factor was found to be distributed predominantly within the vascular endothelium and the mast cells of polyp tissue. In addition, the level of vascular endothelial growth-factor expression and the mean blood-vessel count per field correlated significantly for nasal-polyp tissue (P<0.001). Furthermore, the relative size of nasal polyps correlated significantly with the number of (intra-polyp) vascular endothelial-cell growth factor-expressing cells and the mean blood-vessel density (P<0.05, for both).

CONCLUSION

The level of expression of vascular endothelial-cell growth factor (VEGF) and the mean blood-vessel density were shown to be significantly greater within nasal polyps than within corresponding sinusitis mucosa. Clinically, the expression of both of these parameters correlated well with the relative size of nasal polyps. Vascular endothelial growth factor participates in the formation of nasal polyps amongst children suffering from chronic rhinosinusitis (CRS).

Lipid peroxidation and some antioxidant enzymes in nasal polyp tissue

Nasal polyp (NP) is considered an inflammatory condition in nasal and paranasal sinus cavities and is frequently encountered in otolaryngology clinics. Although the pathophysiology of nasal polyps is poorly understood, it seems likely that the epithelium may play a critical role in the genesis of inflammatory nasal disease. The aim of this study was to investigate the role of free radicals and antioxidant enzymes in NP and compare these findings with concha bullosa (CB). NP and CB were obtained from 27 and 23 patients, respectively. Glutathione peroxidase (GSH-Px), catalase (CAT), xanthine oxidase (XO) total (enzymic plus non-enzymic) superoxide scavenger activity (TSSA), non-enzymic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), and MDA levels in NP and CB were measured. GSH-Px activiy was significantly lower in patients with NP than in the CB group. However, CAT, XO activities and MDA levels were significantly higher in patients with NP than in the CB group, but TSSA, NSSA and SOD activities were unchanged. Increases in the levels of tissue MDA in patients with NP compared to the CB group may indicate the presence of free radical damage in patients with nasal NP.

Lysophosphatidic acid stimulates inflammatory cascade in airway epithelial cells

Nasal polyps are benign outgrowths originating from the anterior ethmoid and maxillary sinuses. The events leading to polyp formation are unknown but evidence points to damage of the mucousal epithelium. Lysophosphatidic acid (LPA) is a water-soluble phospholipid that has been implicated in the development of allergic inflammation. We hypothesized LPA may be an important mediator in the initiation and maintenance of the inflammatory milieu of the polyp. Data was compared from unstimulated lung epithelial and when possible nasal polyp-derived epithelial cells with LPA stimulated cells. LPA receptors 1 and 2 were constitutively expressed on lung and nasal polyp-derived epithelial cells and receptor mRNA expression was decreased upon stimulation with IL-13 and IFN-gamma. When cells were treated with LPA, cellular proliferation was stimulated 2.2 fold. Supernatants from LPA stimulated cells displayed decreases in the levels of VEGF, GM-CSF, and TNF-alpha at 24h which returned to normal or increased at 48h. Our results suggest epithelial cells undergo rapid proliferation in response to LPA resulting in a transient decrease in inflammatory cytokines followed by an upregulation of these cytokines that could lead to increased inflammation.

Distributional characteristics of sulfated glycosaminoglycans in normal human nasal mucosa and nasal polyp

The results of this study suggest that an altered expression pattern of sulfated glycosaminoglycans (GAGs) in nasal polyp may not function as a charge restriction barrier for vascular permeability, contributing to the leakage of protein and fluid. Sulfated GAGs are found on the vascular endothelial surface and in the extracellular matrix in various tissues and organs, suggesting that these materials constitute a negatively charged screen restricting the movement of circulating plasma molecules. This study was designed to elucidate the distributional characteristics of sulfated GAGs in normal human nasal mucosa and nasal polyp in order to understand their roles in the formation of nasal polyp. The expression and localization of sulfated GAGs in normal human nasal mucosa and nasal polyp were detected light microscopically with the histochemical method using poly-L-lysine-conjugated colloidal gold followed by silver enhancement. Sulfated GAGs in normal human nasal mucosa were distributed in the epithelial layer, vascular endothelial surface, submucosal gland and extracellular matrix. In nasal polyp, intense staining was also seen in the glandular structure and epithelial layer. However, the vascular endothelium and extracellular matrix exhibited either a weak reaction or no reaction.

Expression and distribution of thioredoxin and thioredoxin reductase in human nasal mucosa and nasal polyp

CONCLUSIONS

The results of this study indicate that thioredoxin (Trx) and thioredoxin reductase (TrxR) may play a role in the defense of normal human nasal mucosa against external noxious stimuli. Based on the fact that normal nasal mucosa is continuously exposed to inhaled toxicants and contains a considerable number of inflammatory cells, Trx and TrxR may be upregulated even in normal nasal mucosa and perhaps the difference in their expression levels between normal nasal mucosa and nasal polyp, if it exists at all, is small and therefore difficult to detect. Further studies will be needed to clarify the roles of Trx and TrxR in the pathogenesis of nasal polyp.

OBJECTIVES

The cellular antioxidant defense system includes thiol-containing proteins such as Trx and TrxR, which have recently attracted much attention due to their strong antioxidant radical quenching capabilities and other important biological functions related to the regulation of the cellular redox state. This study was undertaken to investigate the expression and distribution of Trx and TrxR in normal human nasal mucosa and nasal polyp, and to improve understanding of the significance of the Trx system in these conditions.

MATERIAL AND METHODS

The expression and distribution of Trx and TrxR in normal human inferior turbinate mucosa and nasal polyp were investigated using reverse transcriptase polymerase chain reaction (RT-PCR), semiquantitative RT-PCR, Western blotting and immunohistochemistry.

RESULTS

mRNAs and protein for both Trx and TrxR were detected in normal human inferior turbinate mucosa and nasal polyp. Semiquantitative RT-PCR and Western blotting revealed that there was no significant difference in the expression levels of Trx and TrxR between inferior turbinate mucosa and nasal polyp. Immunoreactivity for both Trx and TrxR was seen in nasal epithelial cells, glands and vascular endothelium of inferior turbinate mucosa and nasal polyp. Trx and TrxR immunoreactivity was also found in inflammatory infiltrating cells in inferior turbinate mucosa and nasal polyp.

Role of free radicals and antioxidants in nasal polyps

OBJECTIVES/HYPOTHESIS

The aim of this study is to determine the role of free radicals and antioxidants in nasal polyps.

STUDY DESIGN

Prospective, randomized, controlled study.

METHODS

Thirty-one patients with nasal polyposis and a control group consisting of 19 patients with septal deviation and lower turbinate hypertrophy were included in the study. Levels of the antioxidants retinol, beta-carotene, alpha-tocopherol, and ascorbic acid were measured from the sera of the patients with nasal polyposis and the control group. Plasma levels of superoxide dismutase activity (SOD), glutathione peroxidase (GSHPX) activity, and reduced glutathione (GSH) were also obtained. As a peroxidation product, the levels of the malondialdehyde-thiobarbituric acid (MDA) combination were measured from the plasma of patient and control groups. Measurements of MDA, GSH, and alpha-tocopherol levels were also taken from the polyp tissue and turbinate mucosa of the control group.

RESULTS

The blood levels of antioxidants and MDA as an oxidant were significantly different in the patient group compared with the control group (P <.01). The tissue levels of antioxidants and MDA were significantly different in the patients with polyposis compared with the control group (P <.01). The blood and tissue anti-oxidant levels were found to be decreased, and MDA levels as an oxidant increased significantly in the patient group with polyposis when compared with the control group, and there was a negative correlation between oxidative stress and antioxidants.

CONCLUSION

This study demonstrates that oxidative stress and tissue and blood antioxidants in the patients with polyposis were significantly different compared with the control group. The blood and tissue antioxidant levels decreased, and MDA levels, as an oxidant, increased significantly in the patient group with polyposis when compared with the control group. The current study demonstrates that there is strong evidence related to oxidative stress in the pathogenesis of nasal polyposis, and antioxidants can have a preventive role in free-radical-mediated tissue damage in nasal polyposis.

IL-11 and IL-17 expression in nasal polyps: relationship to collagen deposition and suppression by intranasal fluticasone propionate

OBJECTIVES/HYPOTHESIS

Chronic hyperplastic sinusitis (CHS) with nasal polyps (NP) is characterized by extensive mucosal thickening, goblet cell hyperplasia, and subepithelial fibrosis. These features are described to be part of remodeling in the lower airways. The cytokines interleukin (IL)-11 and IL-17 are believed to play a role in lower airway remodeling, but there has been very little work so far examining these cytokines and their relationship to fibrosis in CHS/NP. The aims of this study were to examine the deposition of collagens types I, III, and V in CHS/NP, evaluate the relationship of collagen deposition to expression of IL-11 and IL-17, and to examine the effect of treatment with intranasal fluticasone on these features.

STUDY DESIGN

Sixteen subjects were included in this double-blind, placebo-controlled study. NP biopsies were obtained at the baseline and after 4 weeks of treatment with intranasal fluticasone propionate (FP, Flonase) or placebo. Normal control middle turbinate biopsies from eight nonallergic subjects without sinusitis were used as a control for cytokine and collagen expression.

METHODS

Tissues were assessed for deposition of collagen types I, III, and V using immunocytochemistry. The expression of the cytokines IL-11 and IL-17 was examined by immunostaining or in situ hybridization. The pre- to posttreatment results were analyzed using paired t test, and the magnitude of changes were estimated using one-way analysis of variance (ANOVA) statistical test followed by least significance difference post hoc comparisons of means.

RESULTS

Compared with normal control nasal turbinate tissues, collagen types I, III, and V were increased in all NP tissues, with a predominance of types III and V. Collagen deposition was most abundant in the submucosal connective tissue and in the basement membrane zone. FP treatment had no significant effect on deposition of any collagen type. Expression of IL-11 and IL-17 was also greatly increased in NP compared with control nasal turbinate tissues. IL-11 expression was observed in both inflammatory cells and the epithelium, whereas IL-17 expression was primarily associated with inflammatory cells. In the pretreatment NP, a correlation was found between the presence of IL-11 and collagen type I (r = 0.59, P =.02) and also between IL-17 and both CD4+ and CD8+ T lymphocytes (r = 0.52, P =.05; r = 0.60, P =.02, respectively). Treatment with FP significantly reduced IL-11 expression in subepithelial inflammatory cells and in the epithelial compartment. In contrast, although IL-17 expression was reduced by FP, this effect did not reach statistical significance.

CONCLUSION

NP manifest an increased expression of collagen types III, V, and I and an increase in profibotic cytokines IL-11 and IL-17. A correlation exists between deposition of collagen type I and expression of IL-11, suggesting a possible role for IL-11 in NP remodeling. Collagen deposition was not reversed by FP treatment, whereas IL-11 expression was suppressed. These results are consistent with a partial insensitivity of NP to FP treatment but also suggest that longer-term treatment or perhaps earlier intervention with FP might reduce proinflammatory cytokine signals and ultimately have a beneficial effect in preventing airway remodeling in NP.

Polipose nasossinusal: doença inflamatória crônica evolutiva?

INTRODUÇÃO: A polipose nasossinusal é uma doença degenerativa da mucosa onde há formação de múltiplas estruturas polipóides nas cavidades nasais e seios paranasais e cujos mecanismos fisiopatológicos ainda não são bem compreendidos. FORMA DE ESTUDO: Clínico prospectivo. OBJETIVO E MATERIAL e MÉTODO: Objetivando colaborar na compreensão dos fatores envolvidos na patogênese dos pólipos nasais, decidimos estudar a histologia e a ultraestrutura dos pólipos em dezessete pacientes portadores de polipose. Os pacientes foram divididos em 2 grupos: alérgicos (5 pacientes) e não alérgicos (12 pacientes). RESULTADOS: Mucosa respiratória normal cobrindo a superfície do epitélio foi encontrada em oito casos; metaplasia escamosa em quatro casos; diferentes tipos epiteliais em três casos; epitélio respiratório atípico em um caso e ausência de mucosa em um caso. Foram observados quatorze casos de pólipo tipo fibro-inflamatório, um caso de hiperplasia de glândulas seromucinosas e dois casos de pólipos fibróticos. CONCLUSÕES: Os pacientes apresentaram índices de testes cutâneos positivos iguais ou maiores que a população geral, entretanto, não houve diferenças histológicas ou ultraestruturais entre os pólipos de pacientes alérgicos e dos não alérgicos, sugerindo ser a alergia um fator contribuinte mas não causal na fisiopatologia da polipose nasossinusal.

The new histologic classification of chronic rhinosinusitis

Two histologic patterns of disease are found in chronic rhinosinusitis. The first is dominated by eosinophilia and polypoid changes. Glandular hyperplasia and hypertrophy characterize the second. We present the evidence supporting the existence of these two patterns of disease and link these histologic patterns to the larger pathophysiologic processes that drive them. This histologic classification should be acknowledged both in the clinical setting and in laboratory research of chronic rhinosinusitis.

Nasal polyposis: from cytokines to growth

Nasal polyposis (NP) is a chronic inflammatory condition that is mostly characterized by an infiltration of eosinophils. How this eosinophilic inflammation leads to polyp formation remains largely unclear. In order to identify the most important factors in polyp growth, first we report the histologic features of two early stage manifestations of eosinophilic nasal polyps compared to their surrounding normal mucosa and mature polyps from the same patients. Histomorphologic analysis of these early stage manifestations of NP showed the presence of eosinophils, forming a subepithelial cap over a pseudocyst area that was filled with albumin. In mature NP, a large pseudocyst area containing albumin was surrounded by subepithelial eosinophilia. Second, in an approach to quantify and to study possible relations between eosinophilic inflammation and changes in extracellular tissue components we measured interleukin-5 (IL-5), eotaxin, eosinophil cationic protein (ECP), leukotrienes (LTC4/D4/E4), transforming growth factor-beta 1 (TGF-beta 1), fibronectin, hyaluronic acid, and albumin in nasal tissue homogenates of 31 subjects. Nasal polyp samples (n = 16) were obtained during routine endonasal sinus surgery, whereas control non-polyp samples (n = 15) from subjects with (6) and without (9) allergic rhinitis were obtained from the inferior turbinate during septum surgery. In the group of polyp patients 11 received no treatment, whereas 5 were treated with oral glucocorticoids (GCS) within 4 weeks before surgery. IL-5 was measurable in 8 of 11 untreated NP, whereas IL-5 could not be detected in all 15 controls nor in 4 of 5 oral corticoid-treated polyps. The comparison between the untreated polyp group and controls showed significantly higher concentrations of IL-5, eotaxin, ECP, and albumin in polyp supernatants, whereas TGF-beta 1 was significantly lower. In the oral GCS-treated group, ECP and albumin were significantly reduced compared to untreated nasal polyps. The same tendency, but not reaching significance, was seen for eotaxin and fibronectin, while no difference was found for LTC4/D4/E4 and hyaluronic acid between the groups. Our observations suggest a deposition of albumin (and possibly other plasma proteins) and extracellular matrix proteins, which may be regulated by the subepithelial eosinophilic inflammation, as a possible pathogenic principle of polyp formation and growth. IL-5 and eotaxin are found to be key factors for eosinophilic accumulation and activation in NP. Oral corticoid treatment may lead to the shrinkage of NP by downregulation of the eosinophilic inflammation and reduction of the extravasation and deposition of albumin in NP.

The relationship of nasal polyps, infection, and inflammation

The role of infection as cause or effect in nasal polyps is debated. In experimentally induced sinusitis in rabbits, polyps are frequent. The initial polyp formation sequence involves multiple epithelial disruptions with proliferating granulation tissue. Regenerating epithelial branches spread into the underlying connective tissue, where intraepithelial microcavities give rise to a polyp body from the adjacent mucosa. Clinical as well as experimental studies indicate that nasal polyp formation and growth are activated and perpetuated by an integrated process of mucosal epithelium, matrix, and inflammatory cells, which in turn may be initiated by both infectious and noninfectious inflammation. The complexity of the pathophysiologic events in nasal polyposis is reinforced by the finding that epithelial desquamation, combined with infection or inflammation, will initiate polyp formation. Systemic glucocorticosteroids inhibit polyp formation as well as growth of pathogenic bacteria in the sinuses of rabbits with experimental infection. Therapeutic use of corticosteroids in polyp disease, combined with antibiotics or surgery, should be modified in relation to long-term progression, intensity variations, and predisposing conditions.

Interaction between fibronectin and eosinophils in the growth of nasal polyps

OBJECTIVES

The aim of this study was to determine roles of fibronectin and eosinophils in the etiology of nasal polyposis.

STUDY DESIGN

We designed a cohort study of cases with nasal polyposis. Sampled nasal polyps were differentiated by their histopathologic characteristics, and compared by size and computed tomography (CT) stage.

METHODS

The size of nasal polyps was determined on the basis of the endoscopic findings, and the extent of sinusitis was evaluated by CT staging. Nasal polyp samples were taken from 82 patients during ethmoidectomy and differentiated by morphologic characteristics, infiltration cell types, or fibronectin positivity. Then their sizes and CT stages were compared. In addition, correlation among these histological characteristics was analyzed.

RESULTS

Nasal polyps showing edematous morphology, eosinophil infiltration, or fibronectin expression were significantly large in size. Concerning CT stages, only the infiltration cell type showed a significant difference. Significant correlation among edematous morphology, eosinophil infiltration, and fibronectin expression was also recognized.

CONCLUSIONS

These findings suggest that interaction between eosinophils and fibronectin may play a role in edema formation, which contributes to the growth of nasal polyps.

Changes in nasal epithelium in patients with severe chronic sinusitis: a clinicopathologic and electron microscopic study

OBJECTIVE

Defective ciliary ultrastructure and impaired mucociliary clearance play an important role in the development of respiratory disease and sinusitis. Changes in the ciliary ultrastructure of the sinonasal epithelium have been documented in patients with primary ciliary dyskinesia. However, secondary ciliary dyskinesias and epithelial cytopathologic changes have been underappreciated as a consequence of respiratory dysfunction and chronic sinusitis.

STUDY DESIGN

Thirty-two patients with severe chronic sinusitis were evaluated for ciliary and epithelial abnormalities.

MATERIALS AND METHODS

Fourteen patients (44%) were children who underwent full allergy, sweat, and immunologic workups. Eighteen patients (56%) were adults who had severe refractory sinusitis and had failed previous sinus surgery. All patients underwent nasal epithelium biopsies of the middle turbinate and evaluation by light and transmission electron microscopy.

RESULTS

Ciliated cells were found in 23 patients (72%) with 9 patients (28%) having no cilia. Foci of normal ciliated epithelium were found in only 19% of the patients, often in epithelial invaginations. Variable numbers (usually a minor population) of cilia in 20 cases (87%) exhibited ultrastructural defects including compound cilia and microtubule and dynein arm defects. All of the patients showed variable loss of differentiated epithelial cells ranging from denuded epithelium to basal cell hyperplasia often associated with squamous metaplasia, secondary to chronic sinonasal disease. The lamina propria was often edematous with dilated capillaries, plasma cells, lymphocytes, and hyperplastic seromucous glands.

CONCLUSIONS

This study demonstrates that ciliary dyskinesias are primarily the result rather than the cause of chronic sinusitis. Patients with chronic sinusitis of uncertain origin exhibit a prominent loss of differentiated epithelial cells, as well as ciliary defects, most of which are likely to be secondary to the chronic disease process. These changes slow down mucociliary clearance and lead to a vicious cycle leading to chronicity.