Retinoic acid promotes fibrinolysis and may regulate polyp formation

BACKGROUND

Patients with aspirin-exacerbated respiratory disease (AERD) regularly exhibit severe nasal polyposis. Studies suggest that chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by excessive fibrin deposition associated with a profound decrease in epithelial tissue plasminogen activator (tPA). Retinoids, including vitamin A and its active metabolite retinoic acid (RA), are necessary for maintaining epithelial function and well-known inducers of tPA in endothelial cells.

OBJECTIVES

This study sought to determine whether endogenous retinoids are involved in NP pathophysiology and disease severity in patients with CRSwNP and AERD.

METHODS

NP tissue was collected from patients with AERD or CRSwNP, and concentrations of retinoids and fibrinolysis markers were measured using ELISA. Normal human bronchial epithelial cells were stimulated alone or in combination with RA and IL-13 for 24 hours.

RESULTS

This study observed lower retinoid levels in nasal polyps of patients with AERD than those with CRSwNP or healthy controls (P < .01). Levels of the fibrin-breakdown product d-dimer were the lowest in AERD polyps (P < .01), which is consistent with lower tPA expression (P < .01). In vitro, all-trans RA upregulated tPA levels in normal human bronchial epithelial cells by 15-fold and reversed the IL-13-induced attenuation of tPA expression in cultured cells (P < .01).

CONCLUSIONS

RA, a potent inducer of epithelial tPA in vitro, is reduced in tissue from patients with AERD, a finding that may potentially contribute to decreased levels of tPA and fibrinolysis in AERD. RA can induce tPA in epithelial cells and can reverse IL-13-induced tPA suppression in vitro, suggesting the potential utility of RA in treating patients with CRSwNP and/or AERD.

Anti-phospholipid antibodies are elevated and functionally active in chronic rhinosinusitis with nasal polyps

BACKGROUND

Polyps from patients with chronic rhinosinusitis with nasal polyps (CRSwNP) contain increased levels of autoreactive antibodies, B cells and fibrin deposition. Anti-phospholipid antibodies (APA) are autoantibodies known to cause thrombosis but have not been implicated in chronic rhinosinusitis (CRS).

OBJECTIVE

To compare APA levels (anti-cardiolipin, anti-phosphatidylethanolamine (anti-PE), and anti-β2 -glycoprotein (anti-B2GP)) in nasal polyp (NP) tissue with tissue from control and CRS without nasal polyp (CRSsNP) patients, we tested whether NP antibodies affect coagulation, and correlate APAs with anti-dsDNA IgG and markers of coagulation.

METHODS

Patient specimens were assayed for APA IgG, anti-dsDNA IgG and thrombin-anti-thrombin (TaT) complex by ELISA. Antibodies from a subset of specimens were tested for modified activated partial thromboplastin time (aPTT) measured on an optical-mechanical coagulometer.

RESULTS

Anti-cardiolipin IgG in NP was 5-fold higher than control tissue (p < .0001). NP antibodies prolonged aPTT compared to control tissue antibodies at 400 µg/mL (36.7 s vs. 33.8 s, p = .024) and 600 µg/mL (40.9 s vs. 34.7 s, p = .0037). Anti-PE IgG antibodies were increased in NP (p = .027), but anti-B2GP IgG was not significantly higher (p = .084). All APAs correlated with anti-dsDNA IgG levels, which were also elevated (R = .77, .71 and .54, respectively, for anti-cardiolipin, anti-PE, and anti-B2GP; all p < .001), but only anti-cardiolipin (R = .50, p = .0185) and anti-PE (R = 0.45, p = .037) correlated with TaT complex levels.

CONCLUSIONS

APA IgG antibodies are increased in NP and correlate with autoreactive tissue antibodies. NP antibodies have in vitro anti-coagulant activity similar to those observed in anti-phospholipid syndrome, suggesting that they may have pro-coagulant effects in polyp tissue.

Studies on activation and regulation of the coagulation cascade in chronic rhinosinusitis with nasal polyps

BACKGROUND

Increased activation of the coagulation cascade and diminished fibrinolysis combine to promote fibrin deposition and polyp formation in chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP). More information is needed concerning mechanisms of coagulation in CRSwNP.

OBJECTIVE

We investigated the mechanisms as well as the initiation and regulation of coagulation cascade activation in CRS.

METHODS

Samples were collected from 135 subjects with CRSwNP, 80 subjects with chronic CRS without nasal polyps (NP), and 65 control subjects. The levels of activated factor X (FXa), prothrombin fragment 1+2 (F1+2), thrombin-antithrombin complex, tissue factor (TF), and TF pathway inhibitor (TFPI) were monitored in CRS by real-time PCR, ELISA, immunohistochemistry, or immunofluorescence. Heteromeric complexes of TF with activated factor VII (FVII) and TF with activated FVII and FXa were assessed by coimmunoprecipitation and Western blotting.

RESULTS

Increased levels of FXa, F1+2, and thrombin-antithrombin complex were detected in NP tissue compared to uncinate tissue from CRS and control subjects. Although free TF protein levels were not increased in NP, immunoprecipitation of TF in NP tissue revealed increased complexes of TF with FVII. Local expression of FVII was detected in sinonasal mucosa, and the ratio of TFPI to FXa was lower in NP tissue.

CONCLUSION

The coagulation cascade is associated with NP compared to control and uncinate tissue from CRS patients, and TF and FVII are produced locally in sinonasal mucosa in patients. TF and FVII can activate the extrinsic coagulation pathway, suggesting that this pathway may activate fibrin deposition in CRSwNP. Reduced formation of the complex of FXa and TFPI in NP may reduce natural suppression of the extrinsic coagulation pathway in CRSwNP.

Studies of the role of basophils in aspirin-exacerbated respiratory disease pathogenesis

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by the triad of chronic rhinosinusitis with nasal polyps (CRSwNP), asthma, and intolerance to cyclooxygenase-1 enzyme inhibitors. The underlying mechanisms contributing to AERD pathogenesis are not fully understood, but AERD is characterized by an enhanced type 2 inflammatory phenotype. Basophils are potent type 2 effector cells, but their involvement in AERD pathophysiology remains unclear.

OBJECTIVE

We sought to characterize the systemic and local basophil responses in patients with AERD compared with patients with CRSwNP.

METHODS

Sinonasal tissues including inferior turbinate and/or nasal polyps (NPs) and peripheral blood were collected from controls, patients with AERD, and patients with CRSwNP. Expression of cell surface (CD45, FcεRI, CD203c), activation (CD63), and intracellular (2D7) markers associated with basophils was characterized using flow cytometry. Clinical data including Lund-Mackay scores and pulmonary function were obtained.

RESULTS

The mean number of basophils (CD45⁺CD203c⁺FcεRI⁺CD117^-) detected in AERD NPs (147 ± 28 cells/mg tissue) was significantly elevated compared with that detected in CRSwNP NPs (69 ± 20 cells/mg tissue; P = .01). The number of circulating basophils was significantly elevated in patients with AERD (P = .04). Basophils in NPs had significantly higher CD203c and CD63 mean fluorescence intensity compared with blood in both conditions (P < .01). Basophils from AERD NPs had lower expression of the granule content marker 2D7 compared with those from matched blood (P < .01) or NPs of patients with CRSwNP (P = .06), suggesting ongoing degranulation. Basophil 2D7 mean fluorescence intensity significantly correlated with pulmonary function (r = 0.62; P = .02) and inversely correlated with sinonasal inflammation (r = -0.56; P = .004).

CONCLUSIONS

Increased basophil numbers and extent of ongoing degranulation in NPs of patients with AERD compared with patients with CRSwNP may contribute to the exaggerated disease pathogenesis and severity unique to AERD.

Anti-dsDNA specific antibody secreting cells are increased in both frequency and abundance in Chronic Rhinosinusitis with Nasal Polyps

Background

We have previously found that anti-dsDNA IgG autoantibodies are increased in Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) patients. Recent studies find that B cells with the Epstein-Barr virus-induced protein 2(EBI2), is critical to the extrafollicular response. We have described elevated numbers of EBI2+ B cells in NP and they were more frequently antibody secreting cells (ASCs). In this study we evaluate whether dsDNA-specific ASCs are increased in NP and further compared the EBI2+ and EBI2− compartments.

Methods

To investigate this problem, flow cytometry and ELISpot assays were utilized to compare the frequency of total IgG and dsDNA specific IgG ASCs and cells were sorted into EBI2+ and EBI2− B cells from human NP and tonsils.

Results

Flow cytometry results (n=10 tonsil, 4 NP) found that although tonsils had significantly more B cells than NP, a significantly smaller proportion were CD27+CD38+ plasmablasts (PB). Further ELISpot analysis found NP B cells were more frequently IgG ASCs than tonsil (0.06% and 0.43% in tonsil (n=9) and NP (n=5) respectively, p&lt;0.001). Anti-dsDNA specific ASCs were two-fold more in NP representing 0.95% of IgG ASCs compared with 0.4% in tonsil ASCs (p&lt;0.05). In analysis of ASCs sorted from tonsils (n=3) and NP (n=2), we found anti-dsDNA IgG ASCs were more frequent among EBI2+ compared to EBI2− cells with 10- and 14-fold increases in dsDNA reactivity (p&lt;0.01).

Conclusions

Although B-cells are significantly more abundant in tonsils, NP derived B-cells more frequently secrete total- and dsDNA-specific IgG. These differences appear to be driven by extrafollicular EBI2+ B-cells suggesting that EBI2+ B cells represent the major pool of autoreactive B-cells observed in CRSwNP and tonsils.

Activation of the 15-lipoxygenase pathway in aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is characterized by asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), and an intolerance of medications that inhibit cyclooxygenase-1. Patients with AERD have more severe upper and lower respiratory tract disease than do aspirin-tolerant patients with CRSwNP. A dysregulation in arachidonic acid metabolism is thought to contribute to the enhanced sinonasal inflammation in AERD.

OBJECTIVE

Our aim was to utilize an unbiased approach investigating arachidonic acid metabolic pathways in AERD.

METHODS

Single-cell RNA sequencing (10× Genomics, Pleasanton, Calif) was utilized to compare the transcriptional profile of nasal polyp (NP) cells from patients with AERD and patients with CRSwNP and map differences in the expression of select genes among identified cell types. Findings were confirmed by traditional real-time PCR. Lipid mediators in sinonasal tissue were measured by mass spectrometry. Localization of various proteins within NPs was assessed by immunofluorescence.

RESULTS

The gene encoding for 15-lipooxygenase (15-LO), ALOX15, was significantly elevated in NPs of patients with AERD compared to NPs of patients with CRSwNP (P < .05) or controls (P < .001). ALOX15 was predominantly expressed by epithelial cells. Expression levels significantly correlated with radiographic sinus disease severity (r = 0.56; P < .001) and were associated with asthma. The level of 15-oxo-eicosatetraenoic acid (15-Oxo-ETE), a downstream product of 15-LO, was significantly elevated in NPs from patients with CRSwNP (27.93 pg/mg of tissue) and NPs from patients with AERD (61.03 pg/mg of tissue) compared to inferior turbinate tissue from controls (7.17 pg/mg of tissue [P < .001]). Hydroxyprostaglandin dehydrogenase, an enzyme required for 15-Oxo-ETE synthesis, was predominantly expressed in mast cells and localized near 15-LO⁺ epithelium in NPs from patients with AERD.

CONCLUSIONS

Epithelial and mast cell interactions, leading to the synthesis of 15-Oxo-ETE, may contribute to the dysregulation of arachidonic acid metabolism via the 15-LO pathway and to the enhanced sinonasal disease severity observed in AERD.

TNF induces production of type 2 cytokines in human group 2 innate lymphoid cells

TNF receptor II is expressed on ILC2s and TNF is able to induce production of type 2 cytokines in human ILC2s. TNF may play a role in causing or amplifying type 2 immunity contributing to health and disease.

Increased thrombin-activatable fibrinolysis inhibitor levels in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous chronic inflammatory disease subdivided based on the presence or absence of nasal polyps (NPs). Histologic features of chronic rhinosinusitis with nasal polyps (CRSwNP) include inflammatory cell infiltration and excessive fibrin deposition in NPs. Thrombin-activatable fibrinolysis inhibitor (TAFI) is an enzyme that plays an antifibrinolytic role in the body. The significance of TAFI has been documented in patients with chronic inflammatory diseases, including chronic lung disease; however, it has not been evaluated in the pathogenesis of NPs.

OBJECTIVE

The objective of this study was to evaluate the potential role of TAFI in the pathogenesis of NPs.

METHODS

Nasal lavage fluid was collected from control subjects and patients with CRS. We measured levels of thrombin/anti-thrombin complex (TATc) and TAFI protein using an ELISA.

RESULTS

TATc levels in nasal lavage fluid were significantly increased in patients with CRSwNP and patients with chronic rhinosinusitis without nasal polyps (CRSsNP) compared with control subjects, and TAFI levels in nasal lavage fluid were also significantly increased in patients with CRSwNP compared with those in control subjects and patients with CRSsNP. There was a significant correlation between TATc and TAFI levels in nasal lavage fluid. Interestingly, patients with CRS and asthma showed increased TATc and TAFI levels in nasal lavage fluid compared with those in patients with CRS without asthma, especially patients with CRSwNP.

CONCLUSIONS

Increased TATc and TAFI levels in nasal passages of patients with CRSwNP might participate in fibrin deposition in NPs and might play a role in the pathogenesis of CRSwNP and asthma.

Pathogenic and protective roles of B cells and antibodies in patients with chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nose and sinuses that affects up to 12% of the population in Europe and the United States. This complex disease is likely driven by multiple environmental, genetic, and inflammatory mechanisms, and recent studies suggest that B cells might play a critical role in disease pathogenesis. B cells and their antibodies have undisputed roles in health and disease within the airway mucosae. Deficient or inadequate B-cell responses can lead to susceptibility to infectious disease in the nose, whereas excess antibody production, including autoantibodies, can promote damaging inflammation. Thus, patients with B-cell defects often have either chronic or recurrent acute infections, and this can be associated with nonpolypoid CRS. In contrast, many patients with CRS with nasal polyps, which is less likely to be driven by pathogens, have excess production of local immunoglobulins, including autoreactive antibodies. These B-cell responses activate complement in many patients and likely contribute to immunopathogenic responses. A better understanding of the B cell-associated mechanisms that drive disease in patients with CRS should be a high priority in the quest to understand the pathogenesis of this disease.

Oligoclonal immunoglobulin repertoire in biliary remnants of biliary atresia

Biliary atresia (BA) is a neonatal cholestatic liver disease that is the leading cause of pediatric liver transplantation, however, the mechanism of disease remains unknown. There are two major forms of BA: isolated BA (iBA) comprises the majority of cases and is thought to result from an aberrant immune response to an environmental trigger, whereas syndromic BA (BASM) has associated malformations and is thought to arise from a congenital insult. To determine whether B cells in BA biliary remnants are antigen driven, we examined the immunoglobulin (Ig) repertoire of diseased tissue from each BA group. Deep sequencing of the Ig chain DNA was performed on iBA and BASM biliary remnants and lymph nodes obtained from the Childhood Liver Disease Research Network (ChiLDReN) repository. Statistical analysis of the Ig repertoire provided measures of Ig clonality and the Ig phenotype. Our data demonstrate that B cells infiltrate diseased iBA and BASM biliary remnant tissue. The Ig repertoires of iBA and BASM disease groups were oligoclonal supporting a role for an antigen-driven immune response in both sub-types. These findings shift the current understanding of BA and suggest a role for antigen stimulation in early iBA and BASM disease pathogenesis.

Reciprocal activation of B cells and group 2 innate lymphoid cells

B cells can be activated at peripheral sites in chronic inflammatory disease, but the mechanisms that drive this, especially in humans, are unclear. We have reported elevated frequencies of Epstein-Barr virus-induced molecule 2 (EBI2) expressing B cells in tissues from patients with chronic airway inflammation. EBI2 is a marker of extrafollicular plasmablasts, which are activated antibody-secreting cells (ASC). We sought to determine the mechanisms of extrafollicular B cell activation during chronic airway inflammation. ELISpot was used to determine ASC frequency in cells from inflamed nasal tissue or control tonsil tissue. B cells, T cells, and group 2 innate lymphoid cells (ILC2) were isolated from peripheral blood, and B cells were co-cultured with group 2 innate lymphoid cells (ILC2) or T cells. EBI2 expression was assessed by flow cytometry, and gene expression changes were assessed by single cell RNA-seq. Inflamed nasal tissue had a higher frequency of ASC compared to tonsil (p&lt;0.05). The majority of the ASC were contained in the EBI2+ B cell subset in nasal and tonsil tissues. Co-culture of B cells and ILC2 significantly increased the frequency of EBI2+ B cells (p&lt;0.01). B cells co-cultured with ILC2 expressed significantly higher levels of CCL17, CCL22, and FceR2 (&gt;5 fold), compared to freshly isolated B cells, or B cells co-cultured with T cells. ILC2 co-cultured with B cells had significantly increased expression of IL-5, IL-13, and IL-2Ra (&gt;7 fold) compared to freshly isolated ILC2. Our data suggest that not only can ILC2 directly activate B cells, but B cells can also enhance ILC2 function. These findings provide new insights into mechanisms that B cells may play in chronic inflammatory disease.

Mast Cell Interactions and Crosstalk in Regulating Allergic Inflammation

PURPOSE OF REVIEW

This review summarizes recent findings on mast cell biology with a focus on IgE-independent roles of mast cells in regulating allergic responses.

RECENT FINDINGS

Recent studies have described novel mast cell-derived molecules, both secreted and membrane-bound, that facilitate cross-talk with a variety of immune effector cells to mediate type 2 inflammatory responses. Mast cells are complex and dynamic cells that are persistent in allergy and are capable of providing signals that lead to the initiation and persistence of allergic mechanisms.

Short-chain fatty acids induce tissue plasminogen activator in airway epithelial cells via GPR41&43

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous chronic inflammatory disease generally divided based on the presence or absence of nasal polyps (NPs). One of the features of NPs is excessive fibrin deposition, which is associated with down-regulation of tissue plasminogen activator (t-PA) in NPs. As t-PA is expressed in epithelial cells, and epithelium is readily accessible to topical therapies, identifying compounds that can mediate the induction of t-PA would be a potential new strategy for the treatment of NPs.

OBJECTIVE

The objective of this study was to determine whether short-chain fatty acids (SCFAs) can induce t-PA in airway epithelial cells via their known receptors GPR41 and GPR43.

METHODS

We performed immunohistochemistry (IHC) to determine whether receptors for SCFAs, known as G protein-coupled receptor 41/free fatty acid receptor 3 (GPR41/FFAR3) and GPR43/FFAR2, are expressed in nasal tissue. Primary normal human bronchial epithelial (NHBE) cells were stimulated with different concentrations of SCFAs to test induction of t-PA, which was analysed by expression of mRNA and protein. Mediation of responses by SCFA receptors was evaluated by specific receptor gene silencing with siRNA.

RESULTS

Immunohistochemistry study revealed that airway epithelial cells expressed GPR41 and GPR43. Acetic acid, propionic acid, butyric acid and valeric acid significantly induced t-PA expression from two- to tenfolds. The strongest inducer of t-PA from NHBE cells was propionic acid; cells stimulated with propionic acid released t-PA into the supernatant in its active form. Gene silencing of GPR41 and GPR43 revealed that induction of t-PA by SCFAs was dependent upon both GPR41 and GPR43.

CONCLUSIONS AND CLINICAL RELEVANCE

Short-chain fatty acids were shown to induce airway epithelial cell expression of t-PA via GPR41 and GPR43. Topical delivery of potent compounds that activate these receptors may have value by reducing fibrin deposition and shrinking nasal polyp growth.

Evidence for altered levels of IgD in the nasal airway mucosa of patients with chronic rhinosinusitis

BACKGROUND

IgD is an enigmatic antibody isotype best known when coexpressed with IgM on naive B cells. However, increased soluble IgD (sIgD) levels and increased IgD+IgM- B-cell populations have been described in the human upper respiratory mucosa.

OBJECTIVE

We assessed whether levels of sIgD and IgD+ B cell counts are altered in nasal tissue from patients with chronic rhinosinusitis (CRS). We further characterized IgD+ B-cell populations and explored clinical and local inflammatory factors associated with tissue sIgD levels.

METHODS

sIgD levels were measured by means of ELISA in nasal tissues, nasal lavage fluid, sera, and supernatants of dissociated nasal tissues. IgD+ cells were identified by using immunofluorescence and flow cytometry. Inflammatory mediator levels in tissues were assessed by using real-time PCR and multiplex immunoassays. Bacterial cultures from the middle meatus were performed. Underlying medical history and medicine use were obtained from medical records.

RESULTS

sIgD levels and numbers of IgD+ cells were significantly increased in uncinate tissue (UT) of patients with chronic rhinosinusitis without nasal polyps (CRSsNP) compared with that of control subjects (4-fold, P < .05). IgD+ cells were densely scattered in the periglandular regions of UT from patients with CRSsNP. We also found that IgD+CD19+CD38bright plasmablast numbers were significantly increased in tissues from patients with CRSsNP compared with control tissues (P < .05). Among numerous factors tested, IL-2 levels were increased in UT from patients with CRSsNP and were positively correlated with tissue IgD levels. Additionally, supernatants of IL-2-stimulated dissociated tissue from patients with CRSsNP had significantly increased sIgD levels compared with those in IL-2-stimulated dissociated control tissue ex vivo (P < .05). Tissue from patients with CRS with preoperative antibiotic use or those with pathogenic bacteria showed higher IgD levels compared with tissue from patients without these variables (P < .05).

CONCLUSION

sIgD levels and IgD+CD19+CD38bright plasmablast counts were increased in nasal tissue of patients with CRSsNP. IgD levels were associated with increased IL-2 levels and the presence of pathogenic bacteria. These findings suggest that IgD might contribute to enhancement mucosal immunity or inflammation or respond to bacterial infections in patients with CRS, especially CRSsNP.

Microparticles in nasal lavage fluids in chronic rhinosinusitis: Potential biomarkers for diagnosis of aspirin-exacerbated respiratory disease

BACKGROUND

Microparticles (MPs) are submicron-sized shed membrane vesicles released from activated or injured cells and are detectable by flow cytometry. MP levels have been used as biomarkers to evaluate cell injury or activation in patients with pathological conditions.

OBJECTIVE

We sought to compare MP types and levels in nasal lavage fluids (NLFs) from controls and patients with chronic rhinosinusitis without nasal polyps (CRSsNP), chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD).

METHODS

We collected NLFs from patients with CRSsNP (n = 33), CRSwNP (n = 45), and AERD (n = 31) and control (n = 24) subjects. Standardized flow cytometry methods were used to characterize the following MP types: endothelial MPs, epithelial MPs (epithelial cell adhesion molecule [EpCAM](+)MPs, E-cadherin(+)MPs), platelet MPs (CD31(+)CD41(+)MPs), eosinophil MPs (EGF-like module-containing mucin-like hormone receptor-like 1[EMR1](+)MPs), mast cell MPs (high-affinity IgE receptor [FcεRI](+)c-kit(+)MPs), and basophil MPs (CD203c(+)c-kit(-)MPs). Basophil activation was evaluated by the mean fluorescence intensity of CD203c on basophil MPs.

RESULTS

Activated mast cell MPs (CD137(+) FcεRI(+)c-kit(+)MPs) were significantly increased in NLFs of controls compared with NLFs of patients with CRSsNP (2.3-fold; P < .02), CRSwNP (2.3-fold; P < .03), and AERD (7.4-fold; P < .0001). Platelet MPs (3.5-fold; P < .01) and basophil MPs (2.5-fold; P < .05) were increased only in patients with AERD. Mean fluorescence intensity of CD203c on MPs was increased in patients with CRSwNP (P < .002) and AERD (P < .0001), but not in patients with CRSsNP. EpCAM(+)MPs in patients with CRSwNP were no different from control (P = .91) and lower than those in patients with CRSsNP (P < .02) and AERD (P < .002).

CONCLUSIONS

Based on released MPs, mast cells, platelets, and basophils were more highly activated in patients with AERD than in patients with CRS. Epithelial injury was lower in patients with CRSwNP than in patients with CRSsNP and AERD. MP analysis may help identify phenotypes of CRS, and in distinguishing AERD from CRSwNP.

Proprotein convertases generate a highly functional heterodimeric form of thymic stromal lymphopoietin in humans

RATIONALE

Thymic stromal lymphopoietin (TSLP) is known to be elevated and truncated in nasal polyps (NPs) of patients with chronic rhinosinusitis and might play a significant role in type 2 inflammation in this disease. However, neither the structure nor the role of the truncated products of TSLP has been studied.

OBJECTIVE

We sought to investigate the mechanisms of truncation of TSLP in NPs and the function of the truncated products.

METHODS

We incubated recombinant human TSLP with NP extracts, and determined the protein sequence of the truncated forms of TSLP using Edman protein sequencing and matrix-assisted laser desorption/ionization-time of flight mass spectrometry. We investigated the functional activity of truncated TSLP using a PBMC-based bioassay.

RESULTS

Edman sequencing and mass spectrometry results indicated that NP extracts generated 2 major truncated products, TSLP (residues 29-124) and TSLP (131-159). Interestingly, these 2 products remained linked with disulfide bonds and presented as a dimerized form, TSLP (29-124 + 131-159). We identified that members of the proprotein convertase were rate-limiting enzymes in the truncation of TSLP between residues 130 and 131 and generated a heterodimeric unstable metabolite TSLP (29-130 + 131-159). Carboxypeptidase N immediately digested 6 amino acids from the C terminus of the longer subunit of TSLP to generate a stable dimerized form, TSLP (29-124 + 131-159), in NPs. These truncations were homeostatic but primate-specific events. A metabolite TSLP (29-130 + 131-159) strongly activated myeloid dendritic cells and group 2 innate lymphoid cells compared with mature TSLP.

CONCLUSIONS

Posttranslational modifications control the functional activity of TSLP in humans and overproduction of TSLP may be a key trigger for the amplification of type 2 inflammation in diseases.

Group 2 innate lymphoid cells are elevated and activated in chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) is characterized by type 2 inflammation with high levels of Th2 cytokines. Although T helper cytokines are released from T cells, innate lymphoid cells (ILC) are also known to produce high levels of the same cytokines. However, the presence of various types of ILC in CRS is poorly understood.

Objective

The objective of this study was to fully characterize the presence of all ILC subsets in CRS and to identify phenotypical differences of group 2 ILC (ILC2) in CRSwNP compared to ILC2 from non‐type 2 inflamed areas.

Methods

We investigated the presence of ILC subsets in peripheral blood mononuclear cells (PBMC) from healthy subjects, tonsil tissue, ethmoid tissue from control subjects and patients with non‐polypoid CRS (CRSsNP) and CRSwNP, as well as nasal polyp (NP) tissue from CRSwNP by flow cytometry. Sorted ILC2 were cultured in the presence and absence of IL‐33 and production of IL‐5 and IL‐13 was assessed by Luminex.

Results

We found that all ILC subsets were present in NP but ILC2 were dominant and significantly elevated compared to PBMC, tonsil, CRSsNP, and normal sinus tissue. We also found that inducible T‐cell co‐stimulator (ICOS) and side scatter were increased and CD127 was down‐regulated in ILC2 from NP compared to blood or tonsil ILC2. Thymic stromal lymphopoietin, IL‐7, and IL‐33 were able to down‐regulate expression of CD127 and increase side scatter in blood ILC2. Furthermore, sorted NP ILC2 but not blood ILC2 spontaneously released type 2 cytokines including IL‐5 and IL‐13.

Conclusions and Clinical Relevance

These results suggest that ILC2 are not only elevated but also activated in CRSwNP in vivo and that ILC2 may play important roles in the type 2 inflammation in CRSwNP.

Superior turbinate eosinophilia correlates with olfactory deficit in chronic rhinosinusitis patients

OBJECTIVE

To evaluate if molecular markers of eosinophilia in olfactory-enriched mucosa are associated with olfactory dysfunction.

STUDY DESIGN

Cross-sectional study of tissue biopsies from 99 patients, and an additional 30 patients who underwent prospective olfactory testing prior to sinonasal procedures.

METHODS

Tissue biopsies were processed for analysis of inflammatory markers using quantitative real time polymerase chain reaction (qRT-PCR). Ipsilateral olfactory performance was assessed using the Sniffin' Sticks (Burghart, Wedel, Germany) threshold component and the University of Pennsylvania Smell Identification Test (Sensonics, Haddon Heights, NJ). Age-adjusted data was correlated with inflammatory marker expression and clinical measures of obstruction from computed tomography and endoscopy.

RESULTS

Gene expression of the eosinophil marker CLC (Charcot Leyden crystal protein) was elevated in superior turbinate (ST) tissue in chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) compared to ST and inferior turbinate tissue in CRS without nasal polyps (CRSsNP) and control patients (all P < 0.001, respectively). CLC in ST tissue was correlated with IL-5 and eotaxin-1 expression (all P < 0.001; P = 0.65, and 0.49, respectively). CLC expression was strongly correlated with eosinophilic cationic protein levels (P < 0.001; r = -0.76), and ST CLC expression was inversely related to olfactory threshold (P = 0.002, r = -0.57) and discrimination scores (P = 0.05, r = -0.42). In multiple linear regression of CLC gene expression, polyp status, and radiographic and endoscopic findings with olfactory threshold, CLC was the only significantly correlated variable (P < 0.05).

CONCLUSION

Markers of eosinophils are elevated in the ST of patients with CRSwNP and correlate with olfactory loss. These findings support the hypothesis that olfactory dysfunction in CRS correlates local eosinophil influx into the olfactory cleft.

LEVEL OF EVIDENCE

NA. Laryngoscope, 127:2210-2218, 2017.

Clinical Characteristics of Patients with Chronic Rhinosinusitis with Nasal Polyps, Asthma, and Aspirin-Exacerbated Respiratory Disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) comprises the triad of chronic rhinosinusitis with nasal polyps (CRSwNP), asthma, and intolerance to inhibitors of the cyclooxygenase-1 (COX-1) enzyme. The prevalence of AERD remains unclear, and few studies have compared the clinical characteristics of patients with AERD to those with CRSwNP alone, asthma alone, or both CRSwNP and asthma.

OBJECTIVE

To determine the prevalence of AERD within a tertiary care setting, and to identify unique clinical features that could distinguish these patients from those with both CRSwNP and asthma or with CRSwNP alone.

METHODS

Electronic medical records of patients at Northwestern in Chicago, Illinois, were searched by computer algorithm and then manual chart review to identify 459 patients with CRSwNP alone, 412 with both CRSwNP and asthma, 171 with AERD, and 300 with asthma only. Demographic and clinical features including sex, atopy, and sinus disease severity were characterized.

RESULTS

The prevalence of AERD among patients with CRSwNP was 16%. Patients with AERD had undergone 2-fold more sinus surgeries (P < .001) and were significantly younger at the time of their first surgery (40 ± 13 years) than were patients with CRSwNP (43 ± 14 years; P < .05). Atopy was significantly more prevalent in patients with AERD (84%) or asthma (85%) than in patients with CRSwNP (66%, P < .05). More patients with AERD (13%) had corticosteroid-dependent disease than patients with both CRSwNP and asthma (4%, P < .01) or asthma (1%, P < .001).

CONCLUSIONS

AERD is common among patients with CRSwNP; even though patients with AERD have CRSwNP and asthma, the clinical course of their disease is not the same as of patients who have CRSwNP and asthma but are tolerant to COX-1 inhibitors.

Discordant frequencies of tissue-resident and circulating CD180-negative B cells in chronic rhinosinusitis

BACKGROUND

The unconventional toll-like receptor (TLR) CD180 is implicated in chronic inflammatory diseases; however, its role in chronic rhinosinusitis (CRS) has yet to be investigated. Here we study the expression of CD180, its homologue TLR4 and myeloid differentiation factor 1 (MD1) on mucosal and systemic immune cell populations in relation to serum immunoglobulin G (IgG) levels.

METHODS

A total of 70 patients were recruited to the study. Mucosal and peripheral blood samples were prospectively collected from CRS patients and non-CRS controls without evidence of sinus disease. The expression of TLR4, MD1, and CD180 was investigated using qualitative real-time polymerase chain reaction (qRT-PCR), immunohistochemistry, and flow cytometry. Serum IgG levels were determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

CRS with nasal polyps (CRSwNP) patients had significantly increased messenger RNA (mRNA) expression of CD180 and MD1 compared to controls (5.54-fold and 2.1-fold, respectively, p < 0.01). B cells lacking CD180 were lower in CRSwNP tissue compared to CRS without nasal polyps (CRSsNP) and controls (21.07 ± 6.41 vs 41.61 ± 7.82 vs 40.06 ± 8.06; p < 0.01) but higher in blood (39.18 ± 8.3 vs 17.95 ± 7.82 and 12.49 ± 4.92; p ≤ 0.05).

CONCLUSION

Changes in mucosal and peripheral CD180-expressing B cells were identified in CRSwNP patients compared to CRSsNP and controls. This suggests a role for these cells in the dysregulated immune response in these patients.

Heterogeneous inflammatory patterns in chronic rhinosinusitis without nasal polyps in Chicago, Illinois

CRSsNP is a heterogenous disease but type 2 inflammation in CRSsNP was more common than type 1 inflammation among patients in Chicago, Illinois. Distinct therapeutic strategies may be needed depending on the type of inflammation found in CRSsNP.

Chronic airway inflammation provides a unique environment for B cell activation and antibody production

BACKGROUND

B cells play many roles in health and disease. However, little is known about the mechanisms that drive B cell responses in the airways, especially in humans. Chronic rhinosinusitis (CRS) is an inflammatory disease of the upper airways that affects 10% of Europeans and Americans. A subset of CRS patients develop nasal polyps (NPs), which are characterized by type 2 inflammation, eosinophils and group 2 innate lymphoid cells (ILC2s). We have reported that NP contain elevated levels of B cells and antibodies, making NP an ideal system for studying B cells in the airways.

OBJECTIVE

We sought to determine the mechanisms that drive B cell activation and antibody production during chronic airway inflammation.

METHODS

We analysed B cells from NP or tonsil, or after ILC2 coculture, by flow cytometry. Antibody production from tissue was measured using Luminex assays and the frequency of antibody-secreting cells by ELISpot. Formation of B cell clusters was assessed using immunohistochemistry. Expression of genes associated with B cell activation and class switch recombination was measured by qRT-PCR.

RESULTS

NP contained significantly elevated frequencies of plasmablasts, especially those that expressed the extrafollicular marker Epstein-Barr virus-induced protein 2 (EBI2), but significantly fewer germinal centre (GC) B cells compared with tonsil. Antibody production and the frequency of antibody-secreting cells were significantly elevated in NP, and there was evidence for local class switch recombination in NP. Finally, ILC2s directly induced EBI2 expression on B cells in vitro.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data suggest there is a unique B cell activation environment within NP that is distinct from classic GC-mediated mechanisms. We show for the first time that ILC2s directly induce EBI2 expression on B cells, indicating that ILC2s may play an important role in B cell responses. B cell-targeted therapies may provide new treatment options for CRSwNP.

Proton pump inhibitors decrease eotaxin-3/CCL26 expression in patients with chronic rhinosinusitis with nasal polyps: Possible role of the nongastric H,K-ATPase

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is often characterized by tissue eosinophilia that is associated with poor prognosis. Recent findings that proton pump inhibitors (PPIs) directly modulate the expression of eotaxin-3, an eosinophil chemoattractant, in patients with eosinophilic diseases suggest therapeutic potential for PPIs in those with CRSwNP.

OBJECTIVE

We assessed the effect of type 2 mediators, particularly IL-13 and eotaxin-3, on tissue eosinophilia and disease severity in patients with chronic rhinosinusitis (CRS). Further investigation focused on PPI suppression of eotaxin-3 expression in vivo and in vitro, with exploration of underlying mechanisms.

METHODS

Type 2 mediator levels in nasal tissues and secretions were measured by using a multiplex immunoassay. Eotaxin-3 and other chemokines expressed in IL-13-stimulated human sinonasal epithelial cells (HNECs) and BEAS-2B cells with or without PPIs were assessed by using ELISA, Western blotting, real-time PCR, and intracellular pH imaging.

RESULTS

Nasal tissues and secretions from patients with CRSwNP had increased IL-13, eotaxin-2, and eotaxin-3 levels, and these were positively correlated with tissue eosinophil cationic protein levels and radiographic scores in patients with CRS (P < .05). IL-13 stimulation of HNECs and BEAS-2B cells dominantly induced eotaxin-3 expression, which was significantly inhibited by PPIs (P < .05). Patients with CRS taking PPIs also showed lower in vivo eotaxin-3 levels compared with those without PPIs (P < .05). Using intracellular pH imaging and altering extracellular K⁺, we found that IL-13 enhanced H⁺,K⁺-exchange, which was blocked by PPIs and the mechanistically unrelated H,K-ATPase inhibitor, SCH-28080. Furthermore, knockdown of ATP12A (gene for the nongastric H,K-ATPase) significantly attenuated IL-13-induced eotaxin-3 expression in HNECs. PPIs also had effects on accelerating IL-13-induced eotaxin-3 mRNA decay.

CONCLUSION

Our results demonstrated that PPIs reduce IL-13-induced eotaxin-3 expression by airway epithelial cells. Furthermore, mechanistic studies suggest that the nongastric H,K-ATPase is necessary for IL-13-mediated epithelial responses, and its inhibitors, including PPIs, might be of therapeutic value in patients with CRSwNP by reducing epithelial production of eotaxin-3.

B-Cells and Antibody-Mediated Pathogenesis in Chronic Rhinosinusitis with Nasal Polyps

The sinonasal mucosa forms a dynamic immune barrier where epithelial cells and the immune system interact with the inhaled environment and nasal microbiome. Recent studies suggest that B-cells, plasma cells and antibody production are highly activated locally within the nasal mucosa of patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Findings additionally suggest that polyp tissue contains elevated levels of cytokines, chemokines and complement that may drive this profound B-cell response. Currently, the data are conflicting on whether the B-cell response found in the CRSwNP nasal mucosa is antigen-specific, a superantigen response or an expansion of natural antibody responses. Indeed, investigations into the specificity of the mucosal antibody responses find increased production of class-switched antibodies that bind to aeroallergens, staphylococcus aureus as well as autoantigens. A continuation of these studies is needed to elucidate whether extrinsic factors, like the inhaled environment, or intrinsic factors, like the mucosal microbiome and host inflammatory response, are key to the pathogenesis of CRSwNP. This chapter will cover the current evidence regarding local B-cell responses in CRSwNP.

Regulation of B cell responses in allergy by histamine receptors

Histamine is a bioactive amine stored in mast cells and basophils and released upon antigen-specific IgE-dependent activation, mediating responses during allergic reactivity, including vasodilation, smooth muscle constriction and inflammatory cell recruitment. These are regulated through four receptors (H1R-H4R) that are differentially expressed on various cell types. Despite this, increasing evidence suggests that histamine can be produced during the priming phase of allergen responses, with H4R on dendritic cells being important for initiating Type 2 immunity. Here, we sought to determine the roles of these receptors in supporting antigen-specific B cell responses. Interestingly, our data demonstrates that both murine and human B cells only expressed H1R and H2R; these also showed differential expression levels on specific B cell subsets and upon activation. Using an Ovalbumin-alum (OVA-alum) model of allergic immunization, mice lacking H2R produced significantly lower levels of OVA-IgE, whereas mice lacking H1R were unaffected. Surprisingly, absence of both H1R and H2R (H1R/H2R DKO) exhibited undetectable levels of OVA-IgE. This was not due to T cell-intrinsic influences since restimulation of splenocytes from immunized H1R/H2R DKO mice showed that Th2 cytokine production was unaltered compared to WT. Instead, in vitro stimulation of B220+ B cells by αCD40 and IL-4 yielded significantly lower IgE production from H1R/H2R DKO mice than WT and defines a key requirement for these receptors in permitting B cells from generating IgE antibodies. Our data establishes a novel requirement for histamine, a molecule typically considered in regulating allergic responses, in supporting the generation of allergic sensitivity.

Proprotein convertases generate a highly functional heterodimeric form of thymic stromal lymphopoietin in chronic rhinosinusitis

Thymic stromal lymphopoietin (TSLP) is known to be elevated and truncated in nasal polyps (NPs) of chronic rhinosinusitis and might play a significant role in type 2 inflammation in this disease. However, neither the structure nor the role of the truncated products of TSLP has been studied. We investigated the mechanisms of truncation of TSLP in NPs and the function of the truncated products. We incubated recombinant full-length 15.1 KDa human TSLP (methionine + residues 29–159, referred to as M29–159) with NP extracts. SDS-PAGE revealed two major truncated products of TSLP in NP extracts. Edman sequencing and MALDI-TOF MS results indicated that the longer truncation product was TSLP (M29–124) and the smaller product was TSLP (131–159). We found that PCSK (proprotein convertase subtilisin/kexin) family proteases were rate-limiting enzymes in the truncation and generation of TSLP (M29–130) and TSLP (131–159). Carboxypeptidases further digested 6 amino acids from the C-terminus of TSLP (M29–130) to generate TSLP (M29–124) in NPs. Interestingly, recombinant TSLP (M29–124) and TSLP (131–159) did not manifest TSLP activity, but PCSK-digested TSLP had significantly higher activity than full-length TSLP on myeloid dendritic cells and group 2 innate lymphoid cells. Finally, we identified a 14.2 KDa TSLP from incubation of TSLP with NP extracts under non-reducing conditions that was significantly reduced in the presence of DTT. This indicates that the two cleaved products are dimerized with disulfide bonds and the dimerized form, TSLP (29–124 + 131–159), is an active metabolite and may contribute to the amplification of type 2 inflammation in NPs.

Analysis of cytokine production by peanut-reactive T cells identifies residual Th2 effectors in highly allergic children who received peanut oral immunotherapy

BACKGROUND

Only limited evidence is available regarding the cytokine repertoire of effector T cells associated with peanut allergy, and how these responses relate to IgE antibodies to peanut components.

OBJECTIVE

To interrogate T cell effector cytokine populations induced by Ara h 1 and Ara h 2 among peanut allergic (PA) children in the context of IgE and to evaluate their modulation during oral immunotherapy (OIT).

METHODS

Peanut-reactive effector T cells were analysed in conjunction with specific IgE profiles in PA children using intracellular staining and multiplex assay. Cytokine-expressing T cell subpopulations were visualized using SPICE.

RESULTS

Ara h 2 dominated the antibody response to peanut as judged by prevalence and quantity among a cohort of children with IgE to peanut. High IgE (> 15 kU(A)/L) was almost exclusively associated with dual sensitization to Ara h 1 and Ara h 2 and was age independent. Among PA children, IL-4-biased responses to both major allergens were induced, regardless of whether IgE antibodies to Ara h 1 were present. Among subjects receiving OIT in whom high IgE was maintained, Th2 reactivity to peanut components persisted despite clinical desensitization and modulation of allergen-specific immune parameters including augmented specific IgG4 antibodies, Th1 skewing and enhanced IL-10. The complexity of cytokine-positive subpopulations within peanut-reactive IL-4(+) and IFN-γ(+) T cells was similar to that observed in those who received no OIT, but was modified with extended therapy. Nonetheless, high Foxp3 expression was a distinguishing feature of peanut-reactive IL-4(+) T cells irrespective of OIT, and a correlate of their ability to secrete type 2 cytokines.

CONCLUSION

Although total numbers of peanut-reactive IL-4(+) and IFN-γ(+) T cells are modulated by OIT in highly allergic children, complex T cell populations with pathogenic potential persist in the presence of recognized immune markers of successful immunotherapy.

Age-related increased prevalence of asthma and nasal polyps in chronic rhinosinusitis and its association with altered IL-6 trans-signaling

We report that S100 proteins were reduced in patients with chronic rhinosinusitis (CRS). S100A8/9, which is important in epithelial barrier function, was particularly decreased in elderly patients with CRS. Epithelial expression of S100A8/9 is partly regulated by the IL-6 trans-signaling pathway. The goal of this study was to investigate whether or not age-related reduction of S100A8/9 in CRS is associated with blunting of IL-6 trans-signaling. The levels of IL-6, soluble IL-6 receptor (sIL-6R), soluble gp130 (sgp130), and S100A8/9 from control subjects (n = 10), and patients with CRS without nasal polyps (n = 13) and those with CRS with nasal polyps (CRSwNP) (n = 14), were measured by ELISA. Age-related differences in the level of each protein were investigated. Normal human bronchial epithelial cells were cultured in air-liquid interface and stimulated with IL-6/sIL-6R and tumor necrosis factor (TNF)-α with or without the addition of sgp130, a natural inhibitor of IL-6 trans-signaling. There was a significant age-related decline in S100A8/9 and an increase in sgp130 in nasal tissue samples from patients with CRSwNP, although there was no age-related difference in IL-6/sIL-6R production. Additionally, expression of the S100A8/9 gene and protein was increased significantly by IL-6/sIL-6R plus TNF-α in normal human bronchial epithelial cells. This increase was blocked by sgp130. These results suggest that increased sgp130 in older patients may inhibit IL-6 trans-signaling, impair barrier function, and decrease S1008/9 production in elderly patients with CRSwNP. Restoration of barrier function by targeting sgp130 may be a novel treatment strategy.

Immune Mechanisms of Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a common inflammatory disease that results in a significant decrease in patient quality of life and a large economic burden. However, the lack of population-based epidemiologic studies and robust model systems has made it difficult to fully elucidate the key inflammatory pathways that drive the chronic inflammatory responses observed in CRS. This review will highlight the wide variety of factors that likely contribute to CRS disease pathogenesis. Defects in the innate immune function of the airway epithelium, including decreases in barrier function, mucociliary clearance, and production of antimicrobial peptides, all likely play a role in the initial inflammatory response. Subsequent recruitment and activation of eosinophils, mast cells, and innate lymphoid cells (ILCs) further contributes to the chronic inflammatory response and directly activates adaptive immune cells, including T and B cells. However, development of new tools and model systems is still needed to further understand the chronicity of this inflammatory response and which specific factors are necessary or sufficient to drive CRS pathogenesis. Such studies will be critical for the development of improved therapeutic strategies aimed at treating this highly prevalent and costly disease.

Cytokines in Chronic Rhinosinusitis. Role in Eosinophilia and Aspirin-exacerbated Respiratory Disease

RATIONALE

The mechanisms that underlie the pathogenesis of chronic rhinosinusitis without nasal polyps (CRSsNP), chronic rhinosinusitis with nasal polyps (CRSwNP), and aspirin-exacerbated respiratory disease (AERD) are not clear.

OBJECTIVES

To first evaluate the inflammatory profiles of CRSsNP and CRSwNP tissues and then to investigate whether clinical differences observed between CRSwNP and AERD are in part secondary to differences in inflammatory mediator expression within nasal polyp (NP) tissues.

METHODS

Expression levels of numerous inflammatory mediators were determined by quantitative real-time polymerase chain reaction, ELISA, and multiplex immunoassay.

MEASUREMENTS AND MAIN RESULTS

CRSwNP NP had increased levels of type 2 mediators, including IL-5 (P < 0.001), IL-13 (P < 0.001), eotaxin-2 (P < 0.001), and monocyte chemoattractant protein (MCP)-4 (P < 0.01), compared with sinonasal tissue from subjects with CRSsNP and control subjects. Expression of IFN-γ messenger RNA or protein was low and not different among the chronic rhinosinusitis subtypes examined. Compared with CRSwNP, AERD NP had elevated protein levels of eosinophil cationic protein (ECP) (P < 0.001), granulocyte-macrophage colony-stimulating factor (GM-CSF) (P < 0.01), and MCP-1 (P = 0.01), as well as decreased gene expression of tissue plasminogen activator (tPA) (P = 0.02). Despite the higher eosinophilia in AERD, there was no associated increase in type 2 mediator protein levels observed.

CONCLUSIONS

CRSwNP was characterized by a predominant type 2 inflammatory environment, whereas CRSsNP did not reflect a classic type 1 milieu, as has been suggested previously. AERD can be distinguished from CRSwNP by elevated ECP levels, but this enhanced eosinophilia is not associated with elevations in traditional type 2 inflammatory mediators associated with eosinophil proliferation and recruitment. However, other factors, including GM-CSF, MCP-1, and tPA, may be important contributors to AERD pathogenesis.

Pathogenesis of nasal polyposis

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory condition that affects a large proportion of the population world-wide and is associated with high cost of management and significant morbidity. Yet, there is a lack of population-based epidemiologic studies using current definitions of CRSwNP, and the mechanisms that drive pathogenesis in this disease remain unclear. In this review, we summarize the current evidence for the plethora of factors that likely contribute to CRSwNP pathogenesis. Defects in the innate function of the airway epithelial barrier, including diminished expression of antimicrobial products and loss of barrier integrity, combined with colonization by fungi and bacteria likely play a critical role in the development of chronic inflammation in CRSwNP. This chronic inflammation is characterized by elevated expression of many key inflammatory cytokines and chemokines, including IL-5, thymic stromal lymphopoietin and CCL11, that help to initiate and perpetuate this chronic inflammatory response. Together, these factors likely combine to drive the influx of a variety of immune cells, including eosinophils, mast cells, group 2 innate lymphoid cells and lymphocytes, which participate in the chronic inflammatory response within the nasal polyps. Importantly, however, future studies are needed to demonstrate the necessity and sufficiency of these potential drivers of disease in CRSwNP. In addition to the development of new tools and models to aid mechanistic studies, the field of CRSwNP research also needs the type of robust epidemiologic data that has served the asthma community so well. Given the high prevalence, costs and morbidity, there is a great need for continued research into CRS that could facilitate the development of novel therapeutic strategies to improve treatment for patients who suffer from this disease.

Elevated presence of myeloid dendritic cells in nasal polyps of patients with chronic rhinosinusitis

BACKGROUND

Although chronic rhinosinusitis with nasal polyps (CRSwNP) is characterized by Th2 inflammation, the mechanism underlying the onset and amplification of this inflammation has not been fully elucidated. Dendritic cells (DCs) are major antigen-presenting cells, central inducers of adaptive immunity and critical regulators of many inflammatory diseases. However, the presence of DCs in CRS, especially in nasal polyps (NPs), has not been extensively studied.

OBJECTIVE

The objective of this study was to characterize DC subsets in CRS.

METHODS

We used real-time PCR to assess the expression of mRNA for markers of myeloid DCs (mDCs; CD1c), plasmacytoid DCs (pDCs; CD303) and Langerhans cells (LCs; CD1a, CD207) in uncinate tissue (UT) from controls and patients with CRS as well as in NP. We assayed the presence of DCs by immunohistochemistry and flow cytometry.

RESULTS

Compared to UT from control subjects (n = 15) and patients with CRS without NP (CRSsNP) (n = 16) and CRSwNP (n = 17), mRNAs for CD1a and CD1c were significantly elevated in NPs (n = 29). In contrast, CD207 mRNA was not elevated in NPs. Immunohistochemistry showed that CD1c(+) cells but not CD303(+) cells were significantly elevated in NPs compared to control subjects or patients with CRSsNP. Flow cytometric analysis showed that CD1a(+) cells in NPs might be a subset of mDC1s and that CD45(+) CD19(-) CD1c(+) CD11c(+) CD141(-) CD303(-) HLA-DR(+) mDC1s and CD45(+) CD19(-) CD11c(+) CD1c(-) CD141(high) HLA-DR(+) mDC2s were significantly elevated in NPs compared to UT from controls and CRSsNP, but CD45(+) CD11c(-) CD303(+) HLA-DR(+) pDCs were only elevated in NPs compared to control UT.

CONCLUSION AND CLINICAL RELEVANCE

Myeloid DCs are elevated in CRSwNP, especially in NPs. Myeloid DCs thus may indirectly contribute to the inflammation observed in CRSwNP.