Human CD127 negative ILC2s show immunological memory.

ILC2s are key players in type 2 immunity and contribute to maintaining homeostasis. ILC2s are also implicated in the development of type 2 inflammation-mediated chronic disorders like asthma. While memory ILC2s have been identified in mouse, it is unknown whether human ILC2s can acquire immunological memory. Here, we demonstrate the persistence of CD45RO, a marker previously linked to inflammatory ILC2s, in resting ILC2s that have undergone prior activation. A high proportion of these cells concurrently reduce the expression of the canonical ILC marker CD127 in a tissue-specific manner. Upon isolation and in vitro stimulation of CD127-CD45RO+ ILC2s, we observed an augmented ability to proliferate and produce cytokines. CD127-CD45RO+ ILC2s are found in both healthy and inflamed tissues and display a gene signature of cell activation. Similarly, mouse memory ILC2s show reduced expression of CD127. Our findings suggest that human ILC2s can acquire innate immune memory and warrant a revision of the current strategies to identify human ILC2s.

MZB1-expressing cells are essential for local immunoglobulin production in chronic rhinosinusitis with nasal polyps.

BACKGROUND: The expression of MZB1 genes is significantly elevated in patients who have chronic rhinosinusitis with nasal polyp (CRSwNP) disease compared with healthy controls. OBJECTIVE: To characterize MZB1-positive B cells in CRSwNP and to estimate the contribution of distinct subsets of B cells to the local overproduction of immunoglobulins. METHODS: Single-cell RNA-sequencing with Cellular Indexing of Transcriptomes and Epitopes by Sequencing technology, Switching Mechanism At the 5' end of RNA Template sequencing, flow cytometry, immunohistochemistry and immunofluorescence staining, Western blot, QuantiGene Plex assay, B-cell ImmunoSpot assay, Luminex assay, and enzyme-linked immunosorbent assay were performed. RESULTS: Significantly higher mRNA expression of MZB1 and HSP90B1 was found in type 2 CRSwNP compared with controls. In CRSwNP, MZB1 expression correlated with the local production of IgE. MZB1 could be colocalized with plasma and mature B cells, especially marginal zone (MZ) B cells. Single-cell transcriptome and epitope studies revealed prominent populations of B cells in type 2 CRSwNP with unexpectedly high MZB1 gene expression. The MZ B-cell population was significantly increased in CRSwNP compared with healthy controls in both peripheral blood mononuclear cells and nasal tissue single-cell suspensions. When those single cells were cultured overnight, the MZ B-cell numbers were positively correlated with local IgE production but negatively correlated with local IgM production. In vitro, MZB1 stimulation up-regulated the mRNA expression of IgE. CONCLUSION: MZB1 was primarily expressed by plasma and mature B cells in nasal mucosa. MZB1 expression level was increased in CRSwNP compared with controls. MZB1 contributed to the local IgE production in type 2 CRSwNP.

The multi-omics single-cell landscape of sinus mucosa in uncontrolled severe chronic rhinosinusitis with nasal polyps.

Uncontrolled severe chronic rhinosinusitis with nasal polyps (CRSwNP) is associated with elevated levels of type 2 inflammatory cytokines and raised immunoglobulin concentrations in nasal polyp tissue. By using single-cell RNA sequencing, transcriptomics, surface proteomics, and T cell and B cell receptor sequencing, we found the predominant cell types in nasal polyps were shifted from epithelial and mesenchymal cells to inflammatory cells compared to nasal mucosa from healthy controls. Broad expansions of CD4 T effector memory cells, CD4 tissue-resident memory T cells, CD8 T effector memory cells and all subtypes of B cells in nasal polyp tissues. The T and B cell receptor repertoires were skewed in NP. This study highlights the deviated immune response and remodeling mechanisms that contribute to the pathogenesis of uncontrolled severe CRSwNP. CLINICAL IMPLICATIONS: We identified differences in the cellular compositions, transcriptomes, proteomes, and deviations in the immune profiles of T cell and B cell receptors as well as alterations in the intercellular communications in uncontrolled severe CRSwNP patients versus healthy controls, which might help to define potential therapeutic targets in the future.

Differential protease content of mast cells and the processing of IL-33 in Alternaria alternata induced allergic airway inflammation in mice.

Background: Recent in vitro studies strongly implicated mast cell-derived proteases as regulators of IL-33 activity by enzymatic cleavage in its central domain. A better understanding of the role of mast cell proteases on IL-33 activity in vivo is needed. We aimed to compare the expression of mast cell proteases in C57BL/6 and BALB/c mice, their role in the cleavage of IL-33 cytokine, and their contribution to allergic airway inflammation. Results: In vitro, full-length IL-33 protein was efficiently degraded by mast cell supernatants of BALB/c mice in contrast to the mast cell supernatants from C57BL/6 mice. RNAseq analysis indicated major differences in the gene expression profiles of bone marrow-derived mast cells from C57BL/6 and BALB/c mice. In Alternaria alternata (Alt) - treated C57BL/6 mice the full-length form of IL-33 was mainly present, while in BALB/c mice, the processed shorter form of IL-33 was more prominent. The observed cleavage pattern of IL-33 was associated with a nearly complete lack of mast cells and their proteases in the lungs of C57BL/6 mice. While most inflammatory cells were similarly increased in Alt-treated C57BL/6 and BALB/c mice, C57BL/6 mice had significantly more eosinophils in the bronchoalveolar lavage fluid and IL-5 protein levels in their lungs than BALB/c mice. Conclusion: Our study demonstrates that lung mast cells differ in number and protease content between the two tested mouse strains and could affect the processing of IL-33 and inflammatory outcome of Alt -induced airway inflammation. We suggest that mast cells and their proteases play a regulatory role in IL-33-induced lung inflammation by limiting its proinflammatory effect via the IL-33/ST2 signaling pathway.

Can patient-reported outcomes and inflammatory markers define endotype 2 in chronic rhinosinusitis without nasal polyps?

BACKGROUND: Chronic rhinosinusitis (CRS) is a heterogeneous disease at the clinical phenotype level (without nasal polyp [CRSsNP] vs with nasal polyp [CRSwNP]) and at the underlying inflammatory endotype level (type 2 vs non-type 2). Whether the endotype is associated with clinical presentation in patients with CRSsNP has yet to be explored in detail. OBJECTIVE: To identify associations between endotypes and their clinical significance in patients with CRSsNP based on tissue interleukin-5 levels. METHODS: A total of 104 patients with CRSsNP who underwent functional endoscopic sinus surgery between 2013 and 2017 were endotyped. We collected immunologic and clinical parameters and evaluated whether there were associations between the endotype and clinical features using Visual Analog Scale (VAS), Sino-Nasal Outcome Test-22 (SNOT-22), Sniffin' Sticks test, Lund-Mackay CT score, and nasal endoscopy. RESULTS: Mean tissue interleukin-5 levels were used to identify type 2 inflammation (non-type 2: 3.37 vs type 2: 191.98 pg/g tissue; P < .001). There were no significant clinical differences measured by patient-reported outcome measures between patients with type 2 CRSsNP and those with non-type 2 CRSsNP preoperatively. Type 2 and non-type 2 CRSsNP did not differentiate in CT score, Sniffin' Sticks test, and nasal endoscopy. Postoperative SNOT-22 and VAS scores correlated well with each other (r = 0.75; P < .01). Postoperative VAS scores were in both groups significantly lower than before the operation (type 2: 5.07 vs 2.99; P < .01; non-type 2: 5.74 vs 3.22; P < .01), but not associated to the inflammatory subtype. CONCLUSION: The type of inflammation does not affect the symptoms, the computed tomography scan, or the postoperative results in CRSsNP in contrast to former findings in CRSwNP. TRIAL REGISTRATION: Belgian registration number (B.U.N.) No. B6702020000097.

Olfaction in nasal polyp patients after Reboot surgery: an endotype-based prospective study.

PURPOSE: To report biomarkers present in the olfactory mucosa in chronic rhinosinusitis with nasal polyps (CRSwNP) in comparison with nasal polyps and to nasal mucosal tissues from control patients. To evaluate the kinetics of smell over 6 months in patients who underwent Reboot surgery. METHODS: Cohort study from May 2021 to May 2022. We collected samples of olfactory mucosa and nasal polyps from 16 CRSwNP patients and inferior turbinate samples from 20 control subjects. The study was not randomized for surgical and/or medical treatment. Samples were analyzed by Luminex and Unicap 100 to measure biomarkers of inflammation (IL1-ß, IL4, IL5, IL6, IL17, CCL3, CCL4, G-CSF, SE-IgE, total IgE and ECP). 12 of the CRSwNP patients underwent Extended Sniffin'tests at timepoints 1-4 days pre-surgery, and 1, 3 and 6 months after Reboot surgery. RESULTS: Type-2 markers were significantly elevated in OM and polyp tissue in CRSwNP (n = 16) vs. controls (n = 20), P < 0.05. TDI scores improved already 1 month (P < 0.05) after surgery and remained stable for 6 months. Type-2 inflammation in nasal polyps was associated with decreased sense of smell and taste before surgery, but improved after surgery (P = 0.048). Type-3 inflammation was present in the olfactory mucosa and was associated with a better sense of smell before surgery, but a smaller improvement of smell afterward. CONCLUSIONS: Type-2 inflammation is present in the olfactory mucosa in CRSwNP patients and is associated with smell loss. Reboot surgery, aiming to completely remove inflamed sinus mucosa, significantly improves the smell in this group of patients.

Reboot surgery for chronic rhinosinusitis with nasal polyposis: recurrence and smell kinetics.

OBJECTIVE: To evaluate the time for recovery of the sense of smell in patients with CRSwNP who underwent Reboot surgery compared to patients undergoing ESS in a long-term follow-up study. METHODS: Data were collected retrospectively from 168 patients with severe uncontrolled CRSwNP, who underwent revision surgery, either as Extended Endoscopic Sinus Surgery (Reboot, 140 patients) or as regular Endoscopic Sinus Surgery (ESS, 28 patients) between January 1, 2014, and December 31, 2015, aiming to compare the outcome of surgeries after 2 years of follow-up. Sense of smell was scored as judged by the patient using scores 0 to 3 reflecting a percentage estimate of remaining smell. RESULTS: Smell improved similarly in the Reboot and ESS groups over the first 9 months, which was maintained over 24 months in the Reboot, but not the ESS group (p = 0.007 after 18 months, p = 0.001 after 24 months). Furthermore, polyp recurrence rates were significantly lower in the Reboot group. CONCLUSION: Reboot surgery significantly improved olfactory function and significantly reduced nasal polyp recurrence rates over 2 years post-operatively. Therefore, Reboot should be considered for patients with uncontrolled severe CRSwNP, specifically when ESS failed, to offer long-term smell and a polyp-free status. LEVEL OF EVIDENCE: 3b.

Granulocyte-colony stimulating factor: Missing link for stratification of type 2-high and type 2-low chronic rhinosinusitis patients.

BACKGROUND: Chronic rhinosinusitis (CRS) is a heterogeneous disease, with patients having either a high or low type 2 inflammatory endotype. Whereas the type 2-high group is well characterized by IL-5 expression, the type 2-low group, consisting of approximately 20% of CRS with and 50% of CRS without nasal polyp patients, lacks a clear biomarker profile and thus specific therapeutic targets. OBJECTIVE: The aim was to identify underlying molecular pathways of type 2-low CRS, as stratification of patients may allow improvement of personalized treatments. METHODS: Luminex assays were performed to analyze proteins in nasal secretions and tissues of CRS patients. Immunostainings were analyzed for differences in neutrophils, granulocyte-colony stimulating factor (G-CSF), and its receptor in nasal tissue. Neutrophils were isolated from blood of healthy volunteers and stimulated with G-CSF. Effects on apoptosis and neutrophil activity were analyzed with flow cytometry. RESULTS: G-CSF was significantly upregulated in nasal tissue and secretion fluid of type 2-low CRS patients compared to type 2-high patients. In nasal polyp tissue of type 2-low patients, a large infiltration of neutrophils expressing both G-CSF and its receptor was detected, suggesting the presence of a neutrophil-intrinsic autocrine survival mechanism. In response to G-CSF, neutrophils were in an activated state and were resistant to apoptosis, possibly contributing to a chronic inflammation. Of interest, type 2-high nasal polyp patients treated with IgE-blocking omalizumab had increased G-CSF concentrations compared to before treatment. CONCLUSION: G-CSF is an important cytokine regulating neutrophils in type 2-low CRS and has potential in the diagnosis and therapy of the disease.

Neutrophils Affect IL-33 Processing in Response to the Respiratory Allergen Alternaria alternata.

Future precision medicine requires further clarifying the mechanisms of inflammation in the severe endotypes of chronic airway diseases such as asthma and chronic rhinosinusitis (CRS). The presence of neutrophils in the airways is often associated with severe airway inflammation, while their precise contribution to the severe inflammation is largely unknown. We aimed to study the role of neutrophils in BALB/c and C57BL/6 mice exposed to Alternaria alternata (Alt). The mice were exposed to Alt extract for twelve hours or ten days to induce allergic airway inflammation. C57BL/6 mice exposed to Alt responded with eosinophilic infiltration and the characteristic IL-5 upregulation. In contrast, the inflammatory response to Alt extract in BALB/c mice was characterized by a neutrophilic response, high levels of G-CSF, and elastase in the lungs. The lack of neutrophils affected the processing of IL-33 in BALB/c mice, as was demonstrated by depletion of neutrophils through intraperitoneal injections of anti-Ly6G antibody. Our data identifies the key role of neutrophils in airway inflammation through IL-33 cleavage in the Alt-induced airway inflammation in mice, which could potentially underline the different endotypes in human disease.

A substantial neutrophilic inflammation as regular part of severe type 2 chronic rhinosinusitis with nasal polyps.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is generally associated with severe type 2 immune reactions in the white population. However, recent findings suggest an additional role for neutrophils in severe type 2 inflammation. OBJECTIVE: This study aimed to characterize the neutrophilic inflammation in CRSwNP and its relation to eosinophilic inflammation in severe type 2 immune reactions. METHODS: The presence and activation of neutrophils and eosinophils was analyzed in CRS without NP and CRSwNP by measuring cell and activation markers via immunohistochemistry, immunofluorescence, Luminex assay, ELISA, UniCAP, fluorescence-activated cell sorting, and PCR. Differential neutrophil migration was assessed via Boyden-chamber assay and neutrophil survival was analyzed via flow cytometry. RESULTS: Both CRS without NP and CRSwNP displayed variable degrees of eosinophilic and neutrophilic inflammation, with a profound neutrophilic infiltration and activation in type 2 CRSwNP, associated with eosinophil extracellular traps cell death and Charcot-Leyden crystals, but independent of IL-17. Neutrophil extracellular traps cell death in CRSwNP was associated with bacterial colonization, however, neutrophils were less prone to undergo neutrophil extracellular traps cell death in the tissue of patients with severe type 2 CRSwNP. Neutrophils did not show increased migration nor survival in the CRSwNP environment in vitro. CONCLUSIONS: This study demonstrated a severe neutrophilic inflammation associated with severe eosinophilic type 2 inflammatory CRSwNP, the role of which needs further study.

Unravelling the expression of interleukin-9 in chronic rhinosinusitis: A possible role for Staphylococcus aureus.

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a Th2 biased inflammation, associated with nasal colonization of Staphylococcus (S.) aureus. Interleukin (IL)-9 is a pro-inflammatory Th2 cytokine with a pivotal role in asthma, allergy and chronic obstructive pulmonary disease (COPD), but is less studied in CRSwNP. We aimed to characterize the expression and cellular source of IL-9 and examined S. aureus as potential local trigger in CRSwNP. We showed increased numbers of interleukin-9 producing neutrophils and mononuclear cells in the tissue of CRSwNP patients. This interleukin-9 production was stimulated by S. aureus and its enterotoxin B in vitro. These findings underline the contribution of S. aureus and define IL-9 as another relevant cytokine in type 2 CRSwNP.

Mouse Strain-Dependent Difference Toward the Staphylococcus aureus Allergen Serine Protease-Like Protein D Reveals a Novel Regulator of IL-33.

Staphylococcus aureus (S. aureus) can secrete a broad range of virulence factors, among which staphylococcal serine protease-like proteins (Spls) have been identified as bacterial allergens. The S. aureus allergen serine protease-like protein D (SplD) induces allergic asthma in C57BL/6J mice through the IL-33/ST2 signaling axis. Analysis of C57BL/6J, C57BL/6N, CBA, DBA/2, and BALB/c mice treated with intratracheal applications of SplD allowed us to identify a frameshift mutation in the serine (or cysteine) peptidase inhibitor, clade A, and member 3I (Serpina3i) causing a truncated form of SERPINA3I in BALB/c, CBA, and DBA/2 mice. IL-33 is a key mediator of SplD-induced immunity and can be processed by proteases leading to its activation or degradation. Full-length SERPINA3I inhibits IL-33 degradation in vivo in the lungs of SplD-treated BALB/c mice and in vitro by direct inhibition of mMCP-4. Collectively, our results establish SERPINA3I as a regulator of IL-33 in the lungs following exposure to the bacterial allergen SplD, and that the asthma phenotypes of mouse strains may be strongly influenced by the observed frameshift mutation in Serpina3i. The analysis of this protease-serpin interaction network might help to identify predictive biomarkers for type-2 biased airway disease in individuals colonized by S. aureus.

Nasal IgE in subjects with allergic and non-allergic rhinitis.

PURPOSE: The prevalence of "ocal allergic rhinitis" within individuals suffering from perennial rhinitis remains uncertain, and patients usually are diagnosed with non-allergic rhinitis. The aim of this study was to evaluate the prevalence of a potential "local allergic rhinitis" in subjects suffering from non-allergic rhinitis in a non-selected group of young students. METHODS: 131 students (age 25.0 ± 5.1 years) with a possible allergic rhinitis and 25 non-allergic controls without rhinitis symptoms (age 22.0 ± 2.0 years) were recruited by public postings. 97 of 131 students with rhinitis were tested positive (≥3 mm) to prick testing with 17 frequent allergens at visit 1. Twenty-four 24 subjects with a house dust mite allergy, 21 subjects with a non-allergic rhinitis, and 18 non-allergic controls were further investigated at visit 2. Blood samples were taken, and nasal secretion was examined. In addition, all groups performed a nasal provocation test with house dust mite (HDM). RESULTS: In serum and nasal secretion, total IgE and house dust mite specific IgE significantly differed between HDM positive subjects and controls. However, no differences between non-allergic subjects and control subjects were quantifiable. Neither a nasal provocation test nor a nasal IgE to HDM allergens showed a measurable positive response in any of the non-allergic rhinitis subjects as well as the healthy controls, whilst being positive in 13 subjects with HDM allergy. CONCLUSIONS: Nasal IgE is present in subjects with HDM allergy, but not in non-allergic rhinitis. In the investigated non-selected population, exclusive local production of IgE is absent. By implication, therefore, our findings challenge the emerging concept of local allergic rhinitis.Study identifier at ClinicalTrials.gov: NCT02810535.

Chronic rhinosinusitis: assessment of changes in nociceptive neurons.

BACKGROUND: Pain is a major symptom of chronic rhinosinusitis (CRS). It is mainly associated with CRS without nasal polyps (CRSsNP) and has a major impact in the decision to move on to surgery. Patients with CRS with nasal polyps (CRSwNP) are characterized by trigeminal hypoesthesia and suffer from less pain. The aim of this study was to investigate whether CRS induces alterations in the peripheral nociceptive neurons, mainly focusing on quantitative changes. METHODS: Sinus mucosa and inferior turbinate (IT) samples were obtained from patients with CRS, and IT tissue of healthy patients served as controls. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed for neuronal markers including CNTNAP2, FAM19A1, GFRA2, NEFH, NTRK1, PLXNC1, RET, SCN10A, SCN11A, TRPV1, and PGP 9.5; enzyme-linked immunosorbent assay (ELISA) was performed for KCNK18, SCN10A, MRGPRD, and MAP2. For PGP 9.5, immunohistochemistry was additionally used to analyze tissue slides. RESULTS: We included 35 patients with CRSsNP, 47 patients with CRSwNP, and 18 control patients. No differences in expression of the neuronal markers were observed between CRSsNP, CRSwNP, and controls. SCN10A was the only marker exclusively expressed on nociceptive neurons in sinus tissue. No histological difference in nerve fibers was observed between sinus mucosa of both phenotypes. CONCLUSION: Our results indicate that the nociceptive nerve density in CRSwNP is not lower than in CRSsNP, as was assumed previously. The nociceptive neurons in sinonasal mucosa cannot be classified into subtypes due to the lack of specificity of the respective marker genes. Our findings question the generally accepted claim that nasal polyp tissue does not contain any nerves.

Type 2 inflammation in chronic rhinosinusitis without nasal polyps: Another relevant endotype.

BACKGROUND: Chronic rhinosinusitis without nasal polyps (CRSsNP) is mainly considered a type 1 mediated disease. The role and clinical significance of type 2 immune responses in CRSsNP have not been addressed sufficiently; a recent cluster analysis for CRS described the existence of a subgroup of patients with CRSsNP with a type 2 inflammation. OBJECTIVE: We aimed to characterize the underlying type 2 immune response and its clinical significance in patients with CRSsNP. METHODS: A total of 240 patients with CRSsNP were endotyped and subdivided on the basis of expression of marker cytokines. Clinical data such as recurrence, comorbid asthma and allergy, and numbers of blood eosinophils and neutrophils were collected from all patients. A selection of 15 patients was further characterized for the presence of eosinophils, neutrophils, Charcot-Leyden crystals, and eosinophil extracellular traps in the mucosae. RESULTS: A type 2 immune response with increased levels of IL-4, IL-5, eosinophil cationic protein, IgE, and Staphylococcus aureus enterotoxin-specific IgE was observed in 49% of patients with CRSsNP. Those patients showed increased numbers of blood and tissue eosinophils, and they displayed a considerable eosinophilic inflammation associated with eosinophil extracellular trap cell death and Charcot-Leyden crystals. A significantly increased prevalence of recurrence and asthma was observed in patients with type 2 CRSsNP compared with in patients with non-type 2 CRSsNP. However, only 4 of 117 patients with type 2 CRSsNP developed nasal polyps within 12 years. CONCLUSION: This study shows that type 2 immune responses in CRSsNP follow similar patterns but are less pronounced than in chronic rhinosinusitis with nasal polyps. Also CRSsNP with a moderate type 2 immune response showed a considerable eosinophilic inflammation with clinical impact.

Functional characterization of the first missense variant in CEP78, a founder allele associated with cone-rod dystrophy, hearing loss, and reduced male fertility.

Inactivating variants in the centrosomal CEP78 gene have been found in cone-rod dystrophy with hearing loss (CRDHL), a particular phenotype distinct from Usher syndrome. Here, we identified and functionally characterized the first CEP78 missense variant c.449T>C, p.(Leu150Ser) in three CRDHL families. The variant was found in a biallelic state in two Belgian families and in a compound heterozygous state-in trans with c.1462-1G>T-in a third German family. Haplotype reconstruction showed a founder effect. Homology modeling revealed a detrimental effect of p.(Leu150Ser) on protein stability, which was corroborated in patients' fibroblasts. Elongated primary cilia without clear ultrastructural abnormalities in sperm or nasal brushes suggest impaired cilia assembly. Two affected males from different families displayed sperm abnormalities causing infertility. One of these is a heterozygous carrier of a complex allele in SPAG17, a ciliary gene previously associated with autosomal recessive male infertility. Taken together, our data indicate that a missense founder allele in CEP78 underlies the same sensorineural CRDHL phenotype previously associated with inactivating variants. Interestingly, the CEP78 phenotype has been possibly expanded with male infertility. Finally, CEP78 loss-of-function variants may have an underestimated role in misdiagnosed Usher syndrome, with or without sperm abnormalities.

Sensitisation to staphylococcal enterotoxins and asthma severity: a longitudinal study in the EGEA cohort.

INTRODUCTION: Evidence is accumulating that Staphylococcus aureus plays an important role as disease modifier in upper and lower airway diseases. Sensitisation to S. aureus enterotoxins (SEs) was associated with an increased risk of severe asthma in previous cross-sectional studies, but evidence from longitudinal studies is lacking. We aimed to assess associations between SE-sensitisation and the subsequent risk for asthma severity and exacerbations. METHODS: This is a nested case-control study from the 20-year Epidemiological Study of the Genetics and Environment of Asthma (EGEA) cohort, including 225 adults (75 without asthma, 76 with mild asthma and 74 with severe asthma) in EGEA2 (2003-2007). For 173 of these individuals, SE-sensitisation was measured on samples collected 11 years earlier (EGEA1). Cross-sectional associations were conducted for EGEA1 and EGEA2. Longitudinal analyses estimated the association between SE-sensitisation in EGEA1 and the risk of severe asthma and asthma exacerbations assessed in the follow-up. Models were adjusted for sex, age, smoking, parental asthma/allergy and skin-prick test to house dust mite. RESULTS: SE-sensitisation varied between 39% in controls to 58% and 76% in mild and severe asthma, respectively, in EGEA1. An adjusted cross-sectional association showed that SE-sensitisation was associated with an increased risk of severe, but not for mild asthma. SE-sensitisation in EGEA1 was associated with severe asthma (adjusted OR 2.69, 95% CI 1.18-6.15) and asthma exacerbations (adjusted OR 4.59, 95% CI 1.40-15.07) assessed 10-20 years later. CONCLUSION: For the first time, this study shows that being sensitised to SEs is associated with an increased subsequent risk of severe asthma and asthma exacerbations.

Immunologic mechanisms of a short-course of Lolium perenne peptide immunotherapy: A randomized, double-blind, placebo-controlled trial.

BACKGROUND: A 3-week short-course of adjuvant-free hydrolysates of Lolium perenne peptide (LPP) immunotherapy for rhinoconjunctivitis with or without asthma over 4 physician visits is safe, well tolerated, and effective. OBJECTIVE: We sought to investigate immunologic mechanisms of LPP immunotherapy in a subset of patients who participated in a phase III, multicenter, randomized, double-blind, placebo-controlled trial (clinical.govNCT02560948). METHODS: Participants were randomized to receive LPP (n = 21) or placebo (n = 11) for 3 weeks over 4 visits. Grass pollen-induced basophil, T-cell, and B-cell responses were evaluated before treatment (visit [V] 2), at the end of treatment (V6), and after the pollen season (V8). RESULTS: Combined symptom and rescue medication scores (CSMS) were lower during the peak pollen season (-35.1%, P = .03) and throughout the pollen season (-53.7%, P = .03) in the LPP-treated group compared with those in the placebo-treated group. Proportions of CD63+ and CD203cbrightCRTH2+ basophils were decreased following LPP treatment at V6 (10 ng/mL, P < .0001) and V8 (10 ng/mL, P < .001) compared to V2. No change in the placebo-treated group was observed. Blunting of seasonal increases in levels of grass pollen-specific IgE was observed in LPP-treated but not placebo-treated group. LPP immunotherapy, but not placebo, was associated with a reduction in proportions of IL-4+ TH2 (V6, P = .02), IL-4+ (V6, P = .003; V8, P = .004), and IL-21+ (V6, P = .003; V8, P = .002) follicular helper T cells. Induction of FoxP3+, follicular regulatory T, and IL-10+ regulatory B cells were observed at V6 (all P < .05) and V8 (all P < .05) in LPP-treated group. Induction of regulatory B cells was associated with allergen-neutralizing IgG4-blocking antibodies. CONCLUSION: For the first time, we demonstrate that the immunologic mechanisms of LPP immunotherapy are underscored by immune modulation in the T- and B-cell compartments, which is necessary for its effect.