Osteitic bone: a surrogate marker of eosinophilia in chronic rhinosinusitis

Osteitis in Eosinophilic Chronic Rhinosinusitis

OBJECTIVES

Eosinophilic chronic rhinosinusitis (ECRS) is an allergic inflammatory disease characterized by chronic inflammation of the sinus mucosa, and sometimes, osteitis. This study aimed to investigate the pattern of osteitis in ECRS and the relationship between bony thickening of the middle turbinate and recurrence of ECRS.

METHODS

A total of 246 patients with paranasal diseases were included in the study. The patients' data on bone thickening level, mucosal thickening, polyp score, clinical severity, and laboratory data were retrospectively evaluated.

RESULTS

In total, 38, 186, and 22 patients had ECRS, non-ECRS (NECRS), and odontogenic sinusitis, respectively. The Lund-Mackey (LM) score and Global Osteitis Scoring Scale (GOSS) scores in patients with ECRS were higher than those in patients with other paranasal diseases. There was a significant positive correlation between the GOSS score and ECRS clinical disease severity. Postoperative recurrence was significantly increased in patients with ECRS associated with bony thickening of the middle turbinate.

CONCLUSION

Both mucosal inflammation and osteitis were more severe in patients with ECRS than in patients with other diseases, and clinical disease severity was correlated with osteitis. Furthermore, the postoperative recurrence rate tended to increase in patients with ECRS who had bony thickening of the middle turbinate.

Clinical and immunologic implication of neo-osteogenesis in chronic rhinosinusitis

INTRODUCTION

Chronic rhinosinusitis (CRS) is a multifactorial disease characterized by long-term inflammation of the nasal and sinus passages. Neo-osteogenesis which is a major finding of recalcitrant CRS is clinically related to the disease severity and surgical outcomes of CRS.

AREAS COVERED

The immunological and molecular mechanisms underlying neo-osteogenesis of CRS remain unclear, and many recent studies have suggested the importance of inflammatory mediators secreted by immune cells. This paper provides a broader understanding of neo-osteogenesis in CRS by reviewing recent updates and evidence of the association between CRS pathophysiology and neo-osteogenesis.

EXPERT OPINION

Crosstalk between the bone and mucosa eventually results in refractory CRS. In addition, both eosinophilic and non-eosinophilic CRS cytokines can play a role in neo-osteogenesis and trigger an enhanced CRS-associated immune response. The significance of predicting neo-osteogenesis in advance or during postoperative care could be essential for effectively managing refractory CRS and enhancing the prognosis of CRS patients.

Alleviation of Surgery-Induced Osteitis in Sinonasal Cavity by Dexamethasone-Loaded Poly(lactic-co-glycolic acid) (PLGA) Microparticles with Strong Calcium-Binding Affinity

For the treatment of sinus surgery-induced osteitis in chronic rhinosinusitis (CRS), oral or intranasal administration of corticoids is generally used, although it has critical limitations and unavoidable side effects. To overcome these limitations, we designed dexamethasone (Dex)-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles with bone-specific binding affinity, which could release the encapsulated Dex in a sustained manner on the exposed bone after the surgical wound in the nasal cavity. In a previous report, we prepared poly(butyl methacrylate-co-methacryloyloxyethyl phosphate) (PBMP) with both calcium-binding phosphomonoester groups and PLGA-binding butyl groups to introduce strong calcium-binding property to PLGA particles. In this study, after successful encapsulation of Dex in the PBMP-coated PLGA particles, we applied the Dex-PLGA/PBMP to the treatment of post-operative osteitis in the sinonasal cavity. The Dex-PLGA/PBMP showed more than 5-times higher binding affinity to the hydroxyapatite (HA) surface compared to the non-coated PLGA particles, without altering the morphology and encapsulation efficiency. After establishing the neo-osteogenesis mouse model by mechanical injury of the nasal mucosa, the activity of intranasally administered Dex-PLGA/PBMP was examined to inhibit the formation of undesirable new woven bone during the wound healing process. In addition, significantly lower osteocalcin activity was observed in the group treated with Dex-PLGA/PBMP, indicating decreased activation of osteoblasts. Overall, these results demonstrate that the PLGA/PBMP microparticle strategy has great potential for the treatment of CRS-related osteitis by localized corticoid delivery on the exposed bones with minimal side effects.

The Effect of Atopy on the Incidence of Osteitis in Patients with Chronic Rhinosinusitis

BACKGROUND

Atopy may not contribute directly to the pathogenesis of chronic rhinosinusitis (CRS) and could be a coexisting disease, but it may play a disease-modifying role in CRS. The aim of this study was to determine the effect of atopy on the incidence of osteitis in patients with CRS.

METHODS

A cross-sectional study at a tertiary center was conducted. Computed tomography of paranasal sinuses (CTPNS) of 75 CRS patients was analyzed. Skin prick test was used to determine the atopy among the CRS patients. The evaluation consisted of symptom score, Lund-Kennedy endoscopic score and CTPNS assessment by Lund Mackay (LM) staging system and Global Osteitis Scoring Scale (GOSS).

RESULTS

About 54.7% of CRS patients had atopy (n=41), and 64% (n=48) had osteitis changes. No significant difference (p>0.05) was found for symptom and endoscopic scores in atopic and non-atopic CRS. Atopic and non-atopic CRS patients demonstrated comparable LM and GOSS scores (both p>0.05). Logistic regression analysis revealed that gender, nasal polyps and bronchial asthma were significantly associated with the incidence of osteitis. Significant correlation was found between LM and GOSS scores in atopic CRS (r=0.81, p<0.05). Correspondingly, both scores were found to be significantly correlated in non-atopic CRS (r=0.74, p<0.05).

CONCLUSION

Atopic sensitization has no effect on the incidence and severity of osteitis in patients with CRS. The present study suggests that osteitis occurs independently from the atopic pathway.

Role of periostin in ECRS

Periostin, an extracelluar matrix protein belonging to the fasciclin family, has been reported to play a key role in the process of Th2-inflammation disease. As eoshinophilic chronic rhinosinusitis has a higher incident rate, studies show that periostin has participated in the process of inflammation and remodeling. This review mainly to summarize researches of periostin in ECRS and to investigate the clinical significance and expression of periostin.

Advances in the Knowledge of the Underlying Airway Remodeling Mechanisms in Chronic Rhinosinusitis Based on the Endotypes: A Review

Chronic rhinosinusitis (CRS) is a chronic inflammatory condition of the nasal and paranasal sinus mucosa that affects up to 10% of the population worldwide. CRS is the most representative disease of the upper respiratory tract where airway remodeling occurs, including epithelial damage, thickening of the basement membrane, fibrosis, goblet cell hyperplasia, subepithelial edema, and osteitis. CRS is divided into two phenotypes according to the presence or absence of nasal polyps: CRS with nasal polyp (CRSwNP) and CRS without nasal polyps (CRSsNP). Based on the underlying pathophysiologic mechanism, CRS is also classified as eosinophilic CRS and non-eosinophilic CRS, owing to Type 2 T helper (Th2)-based inflammation and Type 1 T helper (Th1)/Type 17 T helper (Th17) skewed immune response, respectively. Differences in tissue remodeling in CRS are suggested to be based on the clinical phenotype and endotypes; this is because fibrosis is prominent in CRSsNP, whereas edematous changes occur in CRSwNP, especially in the eosinophilic type. This review aims to summarize the latest information on the different mechanisms of airway remodeling in CRS according to distinct endotypes.

A Computed Tomographic Assessment of Osteitis of Sinus Bony Structures in Horses With Sinonasal Disorders

Background: Computed tomographic (CT) imaging has shown some horses with sinonasal diseases to have changes in their sinus bony structures. Scintigraphic and clinical evidence of sinus osteitis have also been reported. However, no study has objectively examined for the presence and degree of osteitis in equine sinonasal disease.

Objectives: To assess for the presence and extent of osteitis of sinus-related bony structures by examination of CT images of horses with clinically and sinoscopically confirmed unilateral sinonasal disease.

Study Design: Retrospective examination of CT images of horses with confirmed, mainly chronic (>2 month duration) unilateral sinus disease of different etiologies.

Methods: Bone thickness at designated sites of the maxillary bone (n = 3), frontal bone (n = 1), infraorbital canal (n = 2), and bony nasolacrimal duct (n = 1) were measured, as were the maximal diameters of the infraorbital canal and the bony nasolacrimal duct on both affected and control sides. Maxillary bone density (in Hounsfield Units) was also assessed bilaterally. Bone thickness was compared between affected and controlled sides using paired statistical tests.

Results: Bone was significantly thicker in the affected sinuses compared to the control sides at the three maxillary bone sites (all, P < 0.001) and at both infraorbital bone sites (both, P < 0.001), but not at the two most dorsal sites examined, i.e. frontal bone (P = 0.188) and bony nasolacrimal duct (P = −0.260) sites. Infraorbital canal and bony nasolacrimal duct diameters were significantly wider in the affected as compared to the control sides (P < 0.001 and P = 0.002, respectively). Maxillary bone density did not differ significantly between the affected (mean = 1,075 HU, SD = 230.01) and control (mean = 1,100, SD = 200.71) sides (t₍₅₈₎ = −1.03, P = 0.306).

Main Limitations: Possible variation in selecting measurement sites. Variation in the severity and chronicity of sinonasal disease between horses.

Conclusions: Osteitis and enlargement of paranasal bony structures commonly occurs in horses with sinonasal disease and can explain the clinical presence of ipsilateral diffuse soft tissue facial swelling, epiphora, and scintigraphic evidence of bone inflammation in sinonasal disease.

Crosstalk Between Mucosal Inflammation and Bone Metabolism in Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a multifactorial and highly heterogeneous upper airway disease that affects approximately 12% of the general population. There is increasing evidence supporting the impact of osteitis on the pathophysiology of CRS. Osteitis is frequently observed in patients with CRS, and is associated with severe sinonasal inflammation and recalcitrant cases. The overlying inflammatory sinonasal mucosa plays a critical role in the initiation of osteitis; however, the underlying molecular mechanisms and functional significance remain unclear. Increasingly many studies have suggested that immune cells play a crucial role in the bone remodeling process in CRS. The purpose of this review is to summarize the current state of knowledge regarding the specific role of sinonasal inflammation in bone remodeling in CRS patients.

Evaluation of Neo-Osteogenesis in Eosinophilic Chronic Rhinosinusitis Using a Nasal Polyp Murine Model

Purpose

Osteitis refers to the development of new bone formation and remodeling of bone in chronic rhinosinusitis (CRS) patients; it is typically associated with eosinophilia, nasal polyps (NPs), and recalcitrant CRS. However, the roles of ossification in CRS with or without NPs remain unclear due to the lack of appropriate animal models. Thus, it is necessary to have a suitable animal model for greater advances in the understanding of CRS pathogenesis.

Methods

BALB/c mice were administered ovalbumin (OVA) and staphylococcal enterotoxin B (SEB). The numbers of osteoclasts and osteoblasts and bony changes were assessed. Micro computed tomography (micro-CT) scans were conducted to measure bone thickness. Immunofluorescence, immunohistochemistry, and quantitative polymerase chain reaction were performed to evaluate runt-related transcription factor 2 (RUNX2), osteonectin, interleukin (IL)-13, and RUNX2 downstream gene expression. Gene set enrichment analysis was performed in mucosal tissues from control and CRS patients. The effect of resveratrol was evaluated in terms of osteogenesis in a murine eosinophilic CRS NP model.

Results

The histopathologic changes showed markedly thickened bones with significant increase in osteoblast numbers in OVA/SEB-treated mice compared to the phosphate-buffered saline-treated mice. The structural changes in bone on micro-CT were consistent with the histopathological features. The expression of RUNX2 and IL-13 was increased by the administration of OVA/SEB and showed a positive correlation. RUNX2 expression mainly co-localized with osteoblasts. Bioinformatic analysis using human CRS transcriptome revealed that IL-13-induced bony changes via RUNX2. Treatment with resveratrol, a candidate drug against osteitis, diminished the expression of IL-13 and RUNX2, and the number of osteoblasts in OVA/SEB-treated mice.

Conclusions

In the present study, we found the histopathological and radiographic evidence of osteogenesis using a previously established murine eosinophilic CRS NP model. This animal model could provide new insights into the pathophysiology of neo-osteogenesis and provide a basis for developing new therapeutics.

Computed Tomography Score an Excellent Marker: Differentiates Eosinophilic and Non-eosinophilic Variants of Chronic Rhinosinusitis with Nasal Polyp

Eosinophilic and non-eosinophilic subtypes of chronic rhinosinusitis with nasal polyp (CRSwNP) have different clinical profile and management. Currently the 2 subtypes are differentiated based on tissue eosinophilic infiltration, which is identified after surgery by histopathological examination. Hence this study was conducted to compare utility of computed tomography (CT) scans, serum IgE levels, absolute eosinophil count (AEC) and Sino-nasal Outcome Test (SNOT)-20 score for discriminating the 2 subtypes. In this prospective study of 1 year duration, patients suspected of CRSwNP were recruited. Serum IgE levels and AEC estimation were performed by ELISA and standard numerical formula respectively, along with histopathological examination of nasal polyp biopsies. CT score and ratio of CT score for ethmoid sinus and maxillary sinus (E/M ratio) were calculated. Patients were asked to fill SNOT-20 questionnaire. Receiver-operating characteristic (ROC) curve analysis was performed. Out of 52 patients studied, 38 and 14 were no. of eosinophilic and non-eosinophilic CRSwNP cases respectively on the basis of histopathological examination. E/M ratio and overall CT score were found to be highly accurate with area under ROC curve of 0.990 and 0.964 respectively, while rest 3 parameters had low accuracy. Optimal cut-off of CT score and E/M ratio for eosinophilic CRSwNP were 6 and 2.065 respectively. This study demonstrated E/M ratio and total CT score as the most useful surrogate markers for preoperative differentiation of eosinophilic and non-eosinophilic CRSwNP, and hence can be used to predetermine postoperative management before surgery.

Increased nasal matrix metalloproteinase-1 and -9 expression in smokers with chronic rhinosinusitis and asthma

A potential mechanism underlying cigarette smoke-induced airway disease is insufficient tissue repair via altered production of matrix metalloproteinases (MMPs). Osteitis is a signature feature of recalcitrant chronic rhinosinusitis (CRS) and often results in revision surgery. The present study aimed to investigate MMP expression in the nasal tissues of asthmatic patients with CRS and any association with cigarette smoking and osteitis. Thirteen smokers with CRS and asthma, 16 non-smokers with CRS and asthma, and seven non-smoker asthmatic patients without CRS were prospectively recruited. The expression of MMPs and associated immunological factors in surgically-obtained nasal tissues was evaluated via real-time PCR and western blotting. Maximal bone thickness of the anterior ethmoid (AE) partition was measured in axial sinus computed tomography (CT) sections. MMP-1 and MMP-9 expression was increased in the nasal tissues of smokers with asthma and CRS via real-time PCR and western blot. Maximal AE partition bone thickness was greater in smokers with CRS and asthma than in non-smokers with CRS and asthma. MMP-1 and MMP-9 levels were correlated with maximal AE bone thickness. Cigarette smoking was associated with the up-regulation of MMP-1 and MMP-9 in the nasal tissues of patients with airway inflammatory diseases, and with AE osteitis, and with therapeutic resistence.

Interleukin (IL)-13 and IL-17A contribute to neo-osteogenesis in chronic rhinosinusitis by inducing RUNX2

Background

There is increasing evidence supporting the impact of neoosteogenesis in the pathophysiology of chronic rhinosinusitis (CRS), especially in the recalcitrant group of patients. Runt-related transcription factor 2 (RUNX2), a member of the RUNX family, controls osteoblast differentiation and bone formation. However, the role and regulation of RUNX2 in CRS patients with neoosteogenesis remain unclear. The aim of the study is to determine the role of RUNX2 in neoosteogenesis of CRS patients.

Methods

Sinonasal bone and overlying mucosa samples were obtained from CRS patients with or without neoosteogenesis (n = 67) and healthy controls (n = 11). Double immunofluorescence, immunohistochemistry, and immunoblotting were used to evaluate RUNX2 expression in CRS patients with and without neoosteogenesis. In addition, the osteogenic activity of pro-inflammatory cytokines was examined by measuring alkaline phosphatase (ALP) activity and bone mineralisation in vitro.

Findings

RUNX2 was highly expressed in osteoblasts of CRS patients with neoosteogenesis compared with tissues from control subjects and those with CRS without neoosteogenesis. Mucosal extracts from CRS patients with neoosteogenesis showed increased RUNX2 expression and ALP activity in C2C12 cells, whereas those from patients without neoosteogenesis did not. Expression of interleukin (IL)-13 and IL-17A was upregulated in CRS patients with neoosteogenesis. ALP activity and Alizarin Red staining showed IL-13 and IL-17A dose-dependent osteoblast differentiation and mineralisation in vitro.

Interpretation

These findings suggested that IL-13- or IL-17A-induced RUNX2 contributed to new bone formation in CRS patients through its effect on the activity of osteoblasts. RUNX2 may be a novel target for preventing neoosteogenesis in CRS patients.

Osteitis in Chronic Rhinosinusitis

PURPOSE OF REVIEW

Osteitis is recognized as a common factor in recalcitrant chronic rhinosinusitis (CRS). There is evidence for the association of osteitis with revision surgeries and CRS severity, in terms of higher Lund-Mackay scores. This is a narrative review on the osteitis in CRS patients.

RECENT FINDINGS

Evidence to date is inconclusive with regard to the etiology and pathogenesis of this bony thickening. Histopathology of osteitis in primary CRS is likely a process of neo-osteogenesis and bone remodeling. For better understanding, various associating factors have been studied including an inflammatory pattern of rhinosinusitis. Recent studies have associated osteitis with nasal polyps and tissue eosinophilia with the increase in periostin expression and P-glycoprotein mucosal expression. There is no association of osteitis to symptoms or quality of life. Osteitis is an outcome of neo-osteogenesis rather than inflammatory processes in CRS patients without a prior history of surgery. While CT has become a staple in osteitis assessment, the standards for grading osteitic severity remain in an experimental stage. There is no association between the presence or severity of osteitis at the time of surgery and clinical outcomes at 1 year after surgery. This review provides a comprehensive overview of the pathogenesis, epidemiology, and correlation with clinical and biological factors of osteitis in CRS patients.

Endotypes of Chronic Rhinosinusitis Across Ancestry and Geographic Regions

PURPOSE OF REVIEW

Preliminary studies have suggested differences in endotypes of chronic rhinosinusitis (CRS) across ancestry/ethnic groups. Eosinophilic CRS (ECRS) is the predominant subtype for Western/European ancestry CRS patients and non-eosinophilic CRS (nECRS) for Asian patients. This review aims to re-analyze CRS endotypes across ancestry populations using one consistent criteria to existing data.

RECENT FINDINGS

Although tissue eosinophilia is the most commonly used criterion for ECRS, various cut-off points are suggested. Surrogate markers have been extensively studied. Sixty-six cohorts with study criteria were included with a total of 8557 patients. Raw data from 11 studies 544 patients were re-analyzed using number of tissue eosinophils. At lower cut-off values of ≥ 5 and ≥ 10 cells/HPF, most patients of Asian and Western/European ancestry were classified as ECRS without difference. In contrast, at cut-off points of ≥ 70 and ≥ 120 cells/HPF, the majority of both groups became reclassified as nECRS. After applying one consistent criteria to existing data, differences across ancestry and geographic populations in endotypes of CRS were no longer evident.

A pilot study of symptom profiles from a polyp vs an eosinophilic-based classification of chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is likely a biologically heterogeneous disease process. Current guidelines propose subclassification using polyp status while others propose using mucosal eosinophilia. We hypothesized that appropriate CRS subclassification would increase homogeneity of baseline symptoms, and identify characteristic symptoms of each subtype.

METHODS

A total of 57 CRS patients undergoing surgery prospectively completed a preoperative battery of 73 questions relating to symptoms including the 22-item Sino-Nasal Outcome Test (SNOT-22) and 29-item Patient-Reported Outcomes Measurement Information System (PROMIS-29) general quality of life (QOL) measures. Eosinophilic cationic protein (ECP) levels were determined from ethmoid, uncinate, and polyp tissue homogenates using enzyme-linked immunosorbent assay (ELISA) and normalized to total protein. Patients were classified as eosinophilic (eCRS) or non-eosinophilic (neCRS) using a 95th percentile threshold established from control tissue from 82 patients without CRS. Separate pairwise comparisons were performed on patient-reported symptoms using polyp and eosinophilic status.

RESULTS

Of the 57 patients, 28 had CRS with nasal polyps (CRSwNP); 27 of 57 patients had eCRS (CRSwNP, n = 21; CRS without nasal polyps [CRSsNP], n = 6). CRSwNP patients had increased need to blow nose, frequency of nasal congestion, more severe difficulty breathing through nose, more severe nasal discharge, but less cough (p < 0.05). eCRS patients had more bothersome loss of taste/smell, ear pain, sneezing, severe difficulty breathing through nose, and severe nasal congestion compared to neCRS patients (p < 0.05).

CONCLUSION

Subclassifying CRS with symptoms alone is difficult with neither polyp status nor eosinophilia giving a distinctive clinical symptom profile. However, certain symptoms may help otolaryngologists identify CRS subtypes, which may help guide future treatments. Further validation and evaluation of prognosis following treatment is required to evaluate appropriate means of subclassifying CRS.

Osteitis and chronic rhinosinusitis: a review of the current literature

Chronic rhinosinusitis is a common debilitating condition characterized by inflammation of the nose and paranasal sinuses. Osteitis is an associated finding but it is not clear whether it is cause or effect. This review will report on studies that have examined the role of osteitis in CRS, with the ultimate aim of clarifying the definition, pathogenesis and clinical implications of this relatively new clinical entity. Literature searches of Medline, EMBASE and CENTRAL using the search terms osteitis, rhinosinusitis, sinusitis, rhinitis, chronic disease, and recurrence were performed. 21 articles were identified and reviewed. The papers highlighted key pathological features including periosteal thickening, new woven bone formation, bone resorption, fibrosis and inflammatory cell infiltration. Radiological grading systems and basic science research into the role of matrix metalloproteinases and P-glycoprotein were also identified and reviewed.

Non-Eosinophilic Nasal Polyps Shows Increased Epithelial Proliferation and Localized Disease Pattern in the Early Stage

Background

Non-eosinophilic nasal polyps (NPs) show less inflammatory changes and are less commonly associated with lower airway inflammatory disorders such as asthma, compared with eosinophilic NPs. However, the development of non-eosinophilic NPs which is a predominant subtype in Asian population still remains unclear.

Methods

A total of 81 patients (45 with non-eosinophilic NPs and 36 with eosinophilic NPs) were enrolled. Clinical information and computed tomography (CT), endoscopic, and histological findings were investigated. Tissue samples were analyzed for total IgE levels and for mRNA expression levels of interleukin (IL)-4, IL–5, IL–13, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-17A, IL–22, IL-23p19, transforming growth factor (TGF)-β1, TGF-β2, TGF-β3, and periostin. Immunostaining assessment of Ki–67 as a proliferation marker was performed.

Results

We found that epithelial in-growing patterns such as pseudocysts were more frequently observed in histological and endoscopic evaluations of non-eosinophilic NPs, which was linked to increase epithelial staining of Ki–67, a proliferating marker. Eosinophilic NPs were characterized by high infiltration of inflammatory cells, compared with non-eosinophilic NPs. To investigate the developmental course of each subtype, CT was analyzed according to CT scores and subtypes. Non-eosinophilic NPs showed more localized pattern and maxillary sinus involvement, but lesser olfactory involvement in early stage whereas eosinophilic NPs were characterized by diffuse ethmoidal and olfactory involvement. In addition, high ethmoidal/maxillary (E/M) CT scores, indicating ethmoidal dominant involvement, were one of surrogate markers for eosinophilic NP. E/M CT scores was positively correlated with levels of T_H2 inflammatory markers, including IL–4, IL–5, periostin mRNA expression and total IgE levels in NPs, whereas levels of the T_H1 cytokine, IFN- γ were inversely correlated. Moreover, if the combinatorial algorithm meet the three of the four markers, including IL–5 (<2.379), periostin (<3.889), IFN-γ (>0.316), and E/M ratio (<2.167), non-eosinophilic CRSwNP are diagnosed with a sensitivity of 84.4% and a specificity of 84.8%.

Conclusion

Histologic, immunologic and clinical data suggest that non-eosinophilic NPs showed enhanced epithelial alteration and more localized maxillary involvement. Combination of cutoff value on IL–5, periostin, IFN-γ, and E/M scores may be one of surrogate markers for non-eosinophil NP subtype.

Clinical and biological markers of difficult-to-treat severe chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the upper airways of which two major phenotypes exist, CRS without nasal polyps (CRSsNP) and CRS with nasal polyps (CRSwNP). Some patients with CRS have suboptimal response to current guideline treatments. These patients remain severe and uncontrolled by treatment and have a poor quality of life. It is highly important to identify both clinical and biological markers, so-called biomarkers, in this subset of patients. The presence of nasal polyps and comorbidity with asthma and with aspirin-exacerbated respiratory disease (AERD) are the most common clinical traits that have been associated to difficult-to-treat severe CRS. In addition to clinical traits, numerous biological markers, with known etiopathogenic roles in CRS, have been associated to difficult-to-treat or recalcitrant CRS. This review summarizes the existing knowledge of the clinical and biological markers associated to difficult-to-treat or uncontrolled severe CRS.

The significance of osteitis in rhinosinusitis

Rhinosinusitis is a disease of multifactorial aetiology. As a profession our insight into this pathological process has progressed enormously over the last few decades. The contribution from environmental, host immunity, microbiology and anatomical factors is well recognised, if not completely understood. The involvement of underlying bone in rhinosinusitis was first recognised experimentally in animals and has subsequently been highlighted as a potentially significant finding in humans with CRS. In this review, the role of bone in chronic rhinosinusitis and the evidence behind that role are discussed. Both histological and radiological findings are presented and the subsequent potential clinical impact and relevance of osteitis in rhinosinusitis patients. Future pathways for research to add to the current knowledge of the impact of bony involvement are also discussed.

Clinical characteristics and surrogate markers of eosinophilic chronic rhinosinusitis in Southern China

The surrogate markers for subclassifying eosinophilic chronic rhinosinusitis (ECRS) and non-ECRS remain elusive. We herein performed a cross-sectional study to assess the clinical implication of clinical symptoms, CT findings, blood eosinophil (EOS) examination based on histological examination of tissue eosinophilia in 105 adult CRS patients (including 72 with nasal polyps and 33 without nasal polyps) in southern China. We found the mean score of smell loss was significantly higher in ECRS subgroup than those in non-ECRS subgroup (p < 0.05), whereas the average ethmoid osteitis index in non-ECRS subgroup was significantly higher than that in ECRS subgroup (p < 0.05). Moreover, we found both the mean blood EOS number and ratio were significantly higher in ECRS subgroup than those in non-ECRS subgroup (p < 0.05). By applying receiver operating characteristic (ROC) curve analysis, we found blood EOS number had a sensitivity of 84.9 % and specificity of 84.4 % [area under the curve (AUC): 0.873] at the cutoff level of 0.16 × 10(9)/L, and blood EOS ratio had a sensitivity of 89.0 % and specificity of 84.4 % (AUC: 0.863) at the cutoff level of 2.05 % in this cohort. Our findings indicated that smell loss score, ethmoid osteitis index and blood EOS number and ratio may be used for the differential diagnosis of ECRS as the surrogate markers.