Osteitis is associated with P-glycoprotein overexpression in patients with chronic sinusitis without nasal polyps

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.

International consensus statement on allergy and rhinology: rhinosinusitis 2021

I.

EXECUTIVE SUMMARY

BACKGROUND: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICAR-RS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICAR-RS-2021 as well as updates to the original 140 topics. This executive summary consolidates the evidence-based findings of the document.

METHODS

ICAR-RS presents over 180 topics in the forms of evidence-based reviews with recommendations (EBRRs), evidence-based reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary.

RESULTS

ICAR-RS-2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidence-based management algorithm is provided.

CONCLUSION

This ICAR-RS-2021 executive summary provides a compilation of the evidence-based recommendations for medical and surgical treatment of the most common forms of RS.

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.

Characterization of constitutive ER-phagy of excess membrane proteins

Thirty percent of all cellular proteins are inserted into the endoplasmic reticulum (ER), which spans throughout the cytoplasm. Two well-established stress-induced pathways ensure quality control (QC) at the ER: ER-phagy and ER-associated degradation (ERAD), which shuttle cargo for degradation to the lysosome and proteasome, respectively. In contrast, not much is known about constitutive ER-phagy. We have previously reported that excess of integral-membrane proteins is delivered from the ER to the lysosome via autophagy during normal growth of yeast cells. Whereas endogenously expressed ER resident proteins serve as cargos at a basal level, this level can be induced by overexpression of membrane proteins that are not ER residents. Here, we characterize this pathway as constitutive ER-phagy. Constitutive and stress-induced ER-phagy share the basic macro-autophagy machinery including the conserved Atgs and Ypt1 GTPase. However, induction of stress-induced autophagy is not needed for constitutive ER-phagy to occur. Moreover, the selective receptors needed for starvation-induced ER-phagy, Atg39 and Atg40, are not required for constitutive ER-phagy and neither these receptors nor their cargos are delivered through it to the vacuole. As for ERAD, while constitutive ER-phagy recognizes cargo different from that recognized by ERAD, these two ER-QC pathways can partially substitute for each other. Because accumulation of membrane proteins is associated with disease, and constitutive ER-phagy players are conserved from yeast to mammalian cells, this process could be critical for human health.

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.

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.

Osteitis is associated with dysregulated pro-osteoblastic activity in patients with nasal polyps

OBJECTIVES/HYPOTHESIS

The overlying inflammatory mucosa plays a crucial role in the initiation of osteitis; however, the molecular mechanism is unclear. The objective of this study was to explore the bone morphogenetic protein (BMP) pathway and to correlate the expression of key signaling molecules with the degree of osteitis in patients with chronic rhinosinusitis with nasal polyps (CRSwNP).

STUDY DESIGN

Prospective experimental analysis.

METHODS

This was an institutional review board-approved study in which mucosal samples were obtained from sites of osteitis in CRSwNP and compared to nonosteitic healthy controls (n = 10/group). Protein expression of key BMP pathway was quantified by aptamer-based protein array and confirmed by a set of selected mRNA analyses. Degree of osteitis was assessed using both Kennedy Osteitis Score and Global Osteitis Score (GOS).

RESULTS

Pro-osteoblastic expression of BMP7 (fold change [FC] = -1.18, P = .017) and BMP9 (FC = -1.32, P = .023), their receptors, BMP receptor type-1A (BMPR1A) (FC = -2.56, P = .005) and BMP receptor type-2 (FC = -1.28, P = .022), and two enhancers of BMP signaling pathway, the repulsive guidance molecule domain family member B (FC = -1.13, P = .008) and the chordin-like protein 1 (FC = -1.18, P = .027), were all significantly downregulated in CRSwNP. Conversely, the pro-osteoclastic factor, tartrate-resistant acid phosphatase type 5 (ACP5) (FC = 2.36, P = .001), was significantly increased in CRSwNP. GOS was inversely correlated with levels of BMP7 (r = -0.684, P =  .005) and BMPR1A (r = -0.864, P =  .005) and positively correlated with levels of ACP5 (r = 0.815, P =  .004). The FCs among the proteins studied significantly and positively correlated with the FCs of their mRNA expression (r = 0.908, P =  .002).

CONCLUSIONS

Downregulated pro-osteoblastic mucosal BMP signaling is strongly and significantly associated with increased osteitis in CRSwNP.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:E102-E109, 2019.

P-glycoprotein and chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogeneous definition that includes different disease states that usually are associated with abnormal inflammatory responses. Besides being prevalent, the mechanisms involved in its pathogenesis are not clear and there are few therapeutic options with tolerable side effects. P-glycoprotein (P-gp) is an efflux pump responsible of extruding xenobiotics and cellular metabolites from multiple cell types. It has been widely studied in the cancer field, due to its ability to confer resistance to chemotherapy. It also promotes Type 2 helper T-cell polarizing cytokine secretion in CRS and may represent a potential target to differentiate subtypes of CRS and personalize treatment. This state-of-the-art review explores current knowledge on the participation of P-gp in the pathogenesis of CRS, the P-gp inhibition as a novel targeted therapeutic strategy and the exosomal P-gp test, a non-invasive biomarker that can represent an important advance in the field of rhinology.

Intact soluble P-glycoprotein is secreted by sinonasal epithelial cells

BACKGROUND

P-glycoprotein (P-gp) is a 170 kDa transmembrane efflux pump, which is upregulated in chronic rhinosinusitis. Studies of leukemia demonstrated that P-gp may also be secreted in an intact soluble form. The purpose of this study was to explore whether sinonasal epithelial cells were capable of secreting soluble P-gp and whether P-gp has any functional role.

METHODS

Soluble and cytoplasmic P-gp were quantified in vehicle and lipopolysaccharide exposed cultures by enzyme-linked immunosorbent assay. The molecular weight of the soluble P-gp was determined by Western blot. Naive cultures were exposed to recombinant human P-gp at 0-2000 ng/mL. The degree of membranous interpolation was determined by quantitative fluorescent immunocytochemistry and function was determined by a calcein acetoxymethyl ester assay.

RESULTS

Soluble P-gp was secreted intact at 170 kDa. Mean (standard deviation) secretion was detected within vehicle wells at 55.43 ± 26.26 ng/mL, which significantly increased to 333.27 ± 305.98 ng/mL (p < 0.001) after lipopolysaccharide stimulation. Soluble P-gp strongly and significantly correlated with cytoplasmic P-gp (r = 0.57, p = 0.000001). Exposure to 2000 ng/mL of recombinant P-gp significantly increased corrected total cell fluorescence (1.34 ± 1.85) relative to vehicle control 0.29 ± 0.26 (p = 0.01) and significantly reduced calcein acetoxymethyl ester fluorescence (82.03 ± 43.69) relative to 100 ng/mL recombinant P-gp exposed cells (123.11 ± 42.16, p = 0.001).

CONCLUSION

Cultured sinonasal epithelial cells were able to both secrete intact P-gp and could functionally interpolate soluble P-gp into their cell membrane. These in vitro findings indicated that soluble P-gp may be present in nasal mucus as a biomarker and could participate in the maintenance of P-gp overexpression in chronic rhinosinusitis and associated inflammation.

The radiologic evaluation of osteitis type and formation in chronic rhinosinusitis with and without nasal polyposis

OBJECTIVE

To evaluate the amount and type of osteitis observed in chronic rhinosinusitis with nasal polyposis (CRSwNP) and compare it with that of chronic rhinosinusitis without nasal polyposis (CRSnNP).

SETTING

Sisli Etfal Research and Education Hospital, Istanbul, Turkey.

STUDY DESIGN

Prospective, single-blind, cohort study.

METHODS

Three different patient groups, designated as the CRSwNP, CRSnNP, and control groups, were included in the study. Forty patients who had CRSnNP and/or CRSwNP confirmed with a paranasal sinus computerized tomography (CT) study were included for the study group, and 20 individuals were included in the control group. Paranasal sinus CTs were evaluated and compared for osteitis.

RESULTS

Hounsfield units obtained from the right and left agger nasi walls and the medial maxillary sinus wall in the control group were significantly different from the entire group. Similarly, values for the anterior ethmoid wall were statistically significant for the CRSwNP group compared with all the subjects. When the groups were compared to one another, there were significant differences in both the right and left agger nasi walls and the frontal sinus wall.

CONCLUSION

Differentiating and acknowledging osteitis induced by CRSwNP rather than CRSnNP may aid in preoperative planning and indicate where to be more aggressive when excising bony structures. This may help in reducing recurrence and in increasing quality of life.

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.

Differing roles for TGF-β/Smad signaling in osteitis in chronic rhinosinusitis with and without nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP) and with nasal polyps (CRSwNP) is reported to involve different inflammatory processes in sinonasal mucosa and bone tissue, and these processes remain uncharacterized.

OBJECTIVE

We aimed to investigate the molecular mechanisms of osteitis in Chinese patients with CRS to better understand the pathogenesis of CRS.

METHODS

The study included 10 controls, 16 patients with CRSsNP, and 23 patients with CRSwNP. Ethmoid bone tissue samples were evaluated by histologic examination. Quantitative real-time reverse transcription polymerase chain reaction was used to assess expression of transforming growth factor (TGF) β1, TGF-β receptor I and II, Smad2, and Smad3. Immunohistochemical examination of osteoblast expression of TGF-β1, TGF-β receptor I and II, phosphorylated (p) Smad2, and p-Smad3 in ethmoid bone tissue was also performed.

RESULTS

The histopathologic evaluation of ethmoid sinus bone tissue showed that eosinophils had infiltrated the periosteum and induced TGF-β1 expression, periosteal thickening, increased osteoblast activity, and neo-osteogenesis. Messenger RNA levels of TGF-β1, TGF-β receptor I, and Smad3 in CRSwNP ethmoid bone tissues were significantly higher than those in ethmoid bone tissues of patients with CRSsNP and the controls. Immunohistochemical staining showed that TGF-β1, TGF-β receptor I, p-Smad2, and p-Smad3 protein expression was upregulated in patients with CRSwNP, consistent with the corresponding messenger RNA levels.

CONCLUSION

Different signaling pathways are involved in osteitis in CRS and are activated by the TGF-β/Smad signaling pathway in CRSwNP versus the TGF-β/Smad-independent signaling pathway in CRSsNP. Eosinophil infiltration of the periosteum, along with TGF-β1 expression, in CRSwNP indicates that eosinophils may play an important role in the bone remodeling process in CRSwNP.

A Role for Macro-ER-Phagy in ER Quality Control

The endoplasmic-reticulum quality-control (ERQC) system shuttles misfolded proteins for degradation by the proteasome through the well-defined ER-associated degradation (ERAD) pathway. In contrast, very little is known about the role of autophagy in ERQC. Macro-autophagy, a collection of pathways that deliver proteins through autophagosomes (APs) for degradation in the lysosome (vacuole in yeast), is mediated by autophagy-specific proteins, Atgs, and regulated by Ypt/Rab GTPases. Until recently, the term ER-phagy was used to describe degradation of ER membrane and proteins in the lysosome under stress: either ER stress induced by drugs or whole-cell stress induced by starvation. These two types of stresses induce micro-ER-phagy, which does not use autophagic organelles and machinery, and non-selective autophagy. Here, we characterize the macro-ER-phagy pathway and uncover its role in ERQC. This pathway delivers 20-50% of certain ER-resident membrane proteins to the vacuole and is further induced to >90% by overexpression of a single integral-membrane protein. Even though such overexpression in cells defective in macro-ER-phagy induces the unfolded-protein response (UPR), UPR is not needed for macro-ER-phagy. We show that macro-ER-phagy is dependent on Atgs and Ypt GTPases and its cargo passes through APs. Moreover, for the first time the role of Atg9, the only integral-membrane core Atg, is uncoupled from that of other core Atgs. Finally, three sequential steps of this pathway are delineated: Atg9-dependent exit from the ER en route to autophagy, Ypt1- and core Atgs-mediated pre-autophagsomal-structure organization, and Ypt51-mediated delivery of APs to the vacuole.