Elevated numbers of antibody-secreting cells (ASCs) and anti-double-stranded DNA (anti-dsDNA) antibodies are found in nasal polyp (NP) tissue. The presence of anti-dsDNA IgG in tissue prospectively predicts recurrent NP but the characteristics of the source ASCs are unknown. Here, we investigated whether NP B cells expressing the extrafollicular marker EBI2 have increased propensity for autoantibody production and evaluated the molecular characteristics of NP ASCs. NPs showed increased frequencies of anti-dsDNA IgG and total IgG ASCs compared with tonsils, with more pronounced differences among EBI2+ cells. In NPs, EBI2+ cells were frequently double negative (IgD-CD27-) and ASCs. Single-cell RNA-Seq analysis of tonsils and NPs revealed substantial differences in B lineage composition, including differences in percentages of ASCs, germinal centers, proliferative cells, and non-ASCs. NPs exhibited higher expression of specific isotypes (IGHE, IGHA1, IGHA2, and IGHG4) and mature plasma genes, including SDC1 and XBP1, than tonsils. Gene Ontology biological processes indicated upregulated NF-κB and downregulated apoptosis pathways in NP ASCs. Together, these data indicate that NP EBI2+ ASCs secret increased total and anti-dsDNA IgG compared with those from tonsils and had molecular features of mature plasma cell differentiation.

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.

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.

The basophil activation test (BAT) may help identify food allergy. We sought to compare the use of BAT for tree nut and baked egg to standard predictors of oral food challenge (OFC) outcome.

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.

BackgroundAspirin-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.ObjectiveOur aim was to utilize an unbiased approach investigating arachidonic acid metabolic pathways in AERD.MethodsSingle-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.ResultsThe 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.ConclusionsEpithelial 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.

Objective: Local activation of B cells and antibody production are important for protective and pathogenic immune responses. Furthermore, there is evidence that local activation of B cells and antibody production are important for pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) and a severe subset of CRSwNP, aspirin-exacerbated respiratory disease (AERD). This review summarizes these findings and the potential role of B cells and antibodies in disease pathogenesis. Data Sources: Published literature from PubMed searches. Study Selections: Studies relevant to B cell development and the roles of B cells and antibodies in the pathogenesis of CRSwNP and AERD. Results: Formation of tertiary lymphoid structures plays a key role in the local activation of B cells and antibody production. This process is important for fighting infections, but it also contributes to autoimmune disease. Furthermore, there is evidence to support a role for local B cell activation and antibody production in a variety of allergic diseases. Nasal polyp tissues from patients with CRSwNP and AERD have elevated levels of activated B cell subsets and locally produced antibodies. These locally produced antibodies may contribute to disease pathogenesis in a variety of ways, including activation of innate effector cells, whereas locally activated B cells may contribute to pathogenesis through the activation of T cells. Conclusion: More studies are needed to determine the role of B cells and antibodies in driving disease in these patients. However, targeting the processes that drive local B cell activation and antibody production may provide new therapeutic approaches and could help to reduce chronic inflammation. (C) 2020 Published by Elsevier Inc. on behalf of American College of Allergy, Asthma & Immunology.

Local activation of B cells and antibody production are important for protective and pathogenic immune responses. Furthermore, there is evidence that local activation of B cells and antibody production are important for pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) and a severe subset of CRSwNP, aspirin-exacerbated respiratory disease (AERD). This review summarizes these findings and the potential role of B cells and antibodies in disease pathogenesis.Published literature from PubMed searches.Studies relevant to B cell development and the roles of B cells and antibodies in the pathogenesis of CRSwNP and AERD.Formation of tertiary lymphoid structures plays a key role in the local activation of B cells and antibody production. This process is important for fighting infections, but it also contributes to autoimmune disease. Furthermore, there is evidence to support a role for local B cell activation and antibody production in a variety of allergic diseases. Nasal polyp tissues from patients with CRSwNP and AERD have elevated levels of activated B cell subsets and locally produced antibodies. These locally produced antibodies may contribute to disease pathogenesis in a variety of ways, including activation of innate effector cells, whereas locally activated B cells may contribute to pathogenesis through the activation of T cells.More studies are needed to determine the role of B cells and antibodies in driving disease in these patients. However, targeting the processes that drive local B cell activation and antibody production may provide new therapeutic approaches and could help to reduce chronic inflammation.

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, Fc epsilon RI, 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+Fc epsilon RI+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.

RATIONALE: Aspirin Exacerbated Respiratory Disease (AERD) is defined by the triad of asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), and an intolerance to cyclooxygenase-1 inhibitors.AERD patients tend to have more severe respiratory disease than aspirin-tolerant patients with CRSwNP.The underlying mechanisms contributing to enhanced disease in AERD are not understood, but a dysregulation in arachidonic acid metabolism is important.We investigated the 15lipoxygenase (15-LO) pathway in AERD pathogenesis.METHODS: We examined expression levels of genes important for the synthesis and function of arachidonic acid metabolites in AERD and CRSwNP NP by single-cell RNA sequencing using the 10X Genomics platform and by traditional RT-PCR.Lipid mediators were measured in sinonasal tissue by mass spectrometry.Immunofluorescence was used to examine localization of specific enzymes within NP.RESULTS: ALOX15 expression was significantly elevated in AERD compared to CRSwNP NP (p<0.05) and control tissue (p<0.001) and was predominantly expressed in epithelial cells.ALOX15expression significantly correlated with radiographic sinus disease severity (r50.56,p<0.001) and was associated with comorbid asthma in CRSwNP.15oxo-ETE, a downstream product of 15-LO, was significantly elevated in CRSwNP (27.93 pg/mg tissue) and AERD (61.03 pg/mg tissue) NP compared to control (7.17 pg/mg tissue, p<0.001).Hydroxyprostaglandin dehydrogenase, an enzyme required for 15-oxo-ETE synthesis, was predominantly expressed in mast cells and, by immunofluorescence, localized near 15-LO + epithelium in AERD NP.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 as well as to the enhanced sinonasal disease severity observed in AERD.

Background: Food specific immunoglobulin E (sIgE) levels are associated with the development of allergic responses and are used in the clinical evaluation of food allergy. Food sIgG4 levels have been associated with tolerance or clinical nonresponsiveness, particularly in interventional studies. Objective: We aimed to characterize food-specific antibody responses and compare responses with different foods in food allergy. Methods: Serum sIgA, sIgG4, and sIgE to whole peanut, egg white, and wheat, along with total IgE were measured in 57 children. Children with food allergy, children with natural tolerance, and controls were studied. The Mann-Whitney test or Kruskall Wallis test with the Dunn correction were used for statistical analysis. Results: As expected, total IgE levels were highest in the subjects with food allergy compared with the subjects who were nonallergic (p < 0.001) or the subjects who were naturally tolerant (p < 0.001). Peanut sIgE levels were higher in subjects with peanut allergy compared with the subjects who were naturally tolerant (p < 0.0001) and the control subjects (p < 0.03). Interestingly, peanut sIgG4 levels were also highest in children with peanut allergy compared with subjects who were naturally tolerant and control subjects (p = 0.28 and p < 0.001, respectively). Subjects with peanut allergy alone had comparable egg white sIgE levels to children with egg white allergy. In addition, the subjects with peanut allergy alone also had higher levels of egg white and wheat sIgE compared with the control subjects (p < 0.02 and p = 0.001, respectively). In contrast, the subjects with egg white allergy did not demonstrate elevated peanut or wheat sIgE levels. Conclusion: These novel findings suggested that IgE production is dysregulated in patients with peanut allergy, who are much less likely to outgrow their allergy, and suggest that the mechanisms that drive more persistent forms of food allergy may be distinct from more transient forms of food allergy.

Although allergy to tree nuts is often considered a single entity, there is heterogeneity in patient reactivity and response to different tree nuts. We sought to characterize tree nut oral food challenges in a diverse population performed at a single center over a 12-year period. A retrospective chart review was conducted in children (0 to 18 years) who completed an unblinded oral food challenge (OFC) to a full serving of any tree nut from 2007-2019 at Lurie Children's Hospital. Challenges were performed in the course of clinical care at the discretion of the patients' primary allergy provider. Challenges were typically performed to determine tolerance. 397 of the 1042 tree nut oral food challenges were reviewed: 111 almond, 56 cashew, 61 hazelnut, 44 pecan, 46 pistachio, 52 walnut, 10 macadamia, 12 pine nut, and 5 brazil nut. The mean age at OFC was 8.3 years, 52% of patients were male, 65% were Caucasian. Overall, 75% of children passed their OFC. The median IgE of all passed OFCs was 0.62kU/l vs 1.66kU/L in failed OFCs (p<0.001). Interestingly, almost all patients passed OFC to almond (97%), hazelnut (92%) and brazil nut (100%). Pass rates for other nuts were: 61% cashew, 61% pistachio, 54% walnut, 50% pecan, 78% macadamia, 80% pine nut. Among the children that failed their OFC, 46% received epinephrine, and 37% were treated with antihistamines alone. The majority of patients pass low risk almond, hazelnut and brazil nut OFCs whereas there are lower pass rates for the other tree nuts.

Abstract 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<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<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<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.

Microparticles (MPs) are extracellular vesicles shed from membrane of activated cells. High counts of eosinophils, mast cells and basophils are detected in nasal polyps in patients with chronic rhinosinusitis with nasal polyps (CRSwNP). Nasal lavage fluids (NLFs) were collected from 29 controls and 154 subjects with CRSwNP in 2016-2019. EMR1(+)MPs (Eosinophil MPs:EosMPs), FcεRI(+)c-kit(+)MPs (Mast cell MPs:MCMPs) and CD203c(+)c-kit(-)MPs (Basophil MPs:BasoMPs) in NLFs were measured by flow cytometry. Hierarchical cluster analysis based on EoMPs, MCMPs and BasoMPs levels classified CRSwNP subjects into 4 main clusters as follows; Cluster-1 (n=49): High BasoMPs (3.0-fold, vs. controls) /Low MCMP (0.4-fold) /Normal EosMPs (1.2-fold); Cluster-2 (n=36): Normal EosMPs (1.0-fold), MCMPs (0.6-fold) and BasoMPs (1.0-fold); Cluster-3 (n=25): High EosMPs (1.9-fold), MCMPs (2.8-fold) and BasoMPs (3.4-fold); Cluster-4 (n=44): High EosMPs (1.7-fold) and MCMPs (1.8-fold) /Normal BasoMPs (1.2-fold). The proportion of atopy (Skin test positive) was higher in Cluster-3 (91%, p<.0005) and Cluster-4 (66%, p<.004) than in Cluster-2 (47%) but not Cluster-1 (56%, p=.45). The proportion of comorbid asthma was higher in Cluster-3 (68%) than in Cluster-2 (39%, p<.03), Cluster-1 (45%, p<.06) or Cluster-4 (50%, p=.14). The proportion of history of prior surgery was higher in Cluster-1 (51%, p=.10) and Cluster-3 (66%, p<.02) than in Cluster-2 (33%), but not in Cluster-4 (28%, p=.60). Fourteen AERD subjects were distributed as follows; Cluster-1 (n=4), Cluster-2 (n=1), Cluster-3 (n=5), Cluster-4 (n=4). We identified distinct endotypes based on eosinophil, mast cell, and basophil activation within CRSwNP, and these endotypes were significantly and differentially correlated with the presence of severe Type 2 phenotypes.

Aspirin Exacerbated Respiratory Disease (AERD) is defined by the triad of asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), and an intolerance to cyclooxygenase-1 inhibitors. AERD patients tend to have more severe respiratory disease than aspirin-tolerant patients with CRSwNP. The underlying mechanisms contributing to enhanced disease in AERD are not understood, but a dysregulation in arachidonic acid metabolism is important. We investigated the 15-lipoxygenase (15-LO) pathway in AERD pathogenesis. We examined expression levels of genes important for the synthesis and function of arachidonic acid metabolites in AERD and CRSwNP NP by single-cell RNA sequencing using the 10X Genomics platform and by traditional RT-PCR. Lipid mediators were measured in sinonasal tissue by mass spectrometry. Immunofluorescence was used to examine localization of specific enzymes within NP. ALOX15 expression was significantly elevated in AERD compared to CRSwNP NP (p<0.05) and control tissue (p<0.001) and was predominantly expressed in epithelial cells. ALOX15expression significantly correlated with radiographic sinus disease severity (r=0.56, p<0.001) and was associated with comorbid asthma in CRSwNP. 15-oxo-ETE, a downstream product of 15-LO, was significantly elevated in CRSwNP (27.93 pg/mg tissue) and AERD (61.03 pg/mg tissue) NP compared to control (7.17 pg/mg tissue, p<0.001). Hydroxyprostaglandin dehydrogenase, an enzyme required for 15-oxo-ETE synthesis, was predominantly expressed in mast cells and, by immunofluorescence, localized near 15-LO+epithelium in AERD NP. 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 as well as to the enhanced sinonasal disease severity observed in AERD.

Regulatory T cells are a heterogeneous group of cells, including thymcally-derived (tTregs) and Tr1s, that are critical in the regulation of food allergy (FA). PBMCs were isolated from 44 subjects with and without FA and analyzed using flow cytometry. The frequency of Tr1s (CD4+CD45RA-Lag3+CD49b+) was compared between subjects with and without FA. RNA-seq was performed on FACS-sorted CD4+CD25+CD127lo (tTregs) and Tr1s from a subset of children with FA after in vitro stimulation with relevant and non-relevant antigens. Differentially expressed genes were identified, and pathway analysis was performed using MetaScape. The frequency of Tr1s was significantly lower in children with FA (0.82 v. 0.41, p=0.0232). In addition, healthy children had significantly more Tr1s expressing the putative gut-homing marker CCR6 than children with FA (0.315 v. 0.085, p=0.0041). RNA-seq identified 277 differentially expressed genes in Tr1s stimulated with relevant vs non-relevant antigen, while 252 genes were differentially expressed in tTregs stimulated with relevant vs non-relevant antigen. Pathway analysis of the differentially expressed genes from Tr1s revealed significant differences in genes involved in leukocyte activation and signal transduction. Similar analysis of the tTreg genes identified significant differences in genes involved in leukocyte activation, differentiation, and chemotaxis. tTregs and Tr1s from children with FA upregulate genes associated with a variety of activation pathways in an antigen-specific manner, suggesting that exposure to specific antigens may alter the function of these important regulatory cells.

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.