CCR10+ ILC2s with ILC1-like properties exhibit a protective function in severe allergic asthma.

BACKGROUND: We previously showed that patients with severe allergic asthma have high numbers of circulating ILC2s expressing CCR10. METHOD: Herein, CCR10+ ILC2s were further analyzed in the blood of healthy individuals or patients with allergic and non-allergic asthma. Characteristics of human CCR10+ and CCR10- ILC2s were assessed by flow cytometry as well as single-cell multiplex RT-qPCR. The role of CCR10+ ILC2s in asthma pathophysiology was studied in allergen-treated mice. RESULTS: When compared to healthy controls, CCR10+ ILC2s are enriched in the blood of both allergic and non-allergic severe asthmatic patients, and these cells are recruited to the lungs. Plasma concentrations of the CCR10 ligand CCL27 are significantly increased in severe asthmatics when compared to non-asthmatic patients. CCR10+ ILC2s secrete little TH 2 cytokines, but exhibit ILC1-like properties, including a capacity to produce IFN-γ. Also, single-cell analysis reveals that the CCR10+ ILC2 subset is enriched in cells expressing amphiregulin. CCR10+ ILC2 depletion, as well as blocking of IFN-γ activity, exacerbates airway hyperreactivity in allergen-challenged mice, providing evidence for a protective role of these cells in allergic inflammation. CONCLUSIONS: Frequencies of circulating CCR10+ ILC2s and CCL27 plasma concentrations represent candidate markers of asthma severity. The characterization of CCR10+ ILC2s in human samples and in mouse asthma models suggests that these cells downregulate allergic inflammation through IFN-γ production.

Sialylated Fetuin-A as a candidate predictive biomarker for successful grass pollen allergen immunotherapy.

BACKGROUND: Eligibility to immunotherapy is based on the determination of IgE reactivity to a specific allergen by means of skin prick or in vitro testing. Biomarkers predicting the likelihood of clinical improvement during immunotherapy would significantly improve patient selection. METHODS: Proteins were differentially assessed by using 2-dimensional differential gel electrophoresis and label-free mass spectrometry in pretreatment sera obtained from clinical responders and nonresponders within a cohort of 82 patients with grass pollen allergy receiving sublingual immunotherapy or placebo. Functional studies of Fetuin-A (FetA) were conducted by using gene silencing in a mouse asthma model, human dendritic cell in vitro stimulation assays, and surface plasmon resonance. RESULTS: Analysis by using quantitative proteomics of pretreatment sera from patients with grass pollen allergy reveals that high levels of O-glycosylated sialylated FetA isoforms are found in patients exhibiting a strong decrease in rhinoconjunctivitis symptoms after sublingual immunotherapy. Although FetA is involved in numerous inflammatory conditions, its potential role in allergy is unknown. In vivo silencing of the FETUA gene in BALB/c mice results in a dramatic upregulation of airway hyperresponsiveness, lung resistance, and TH2 responses after allergic sensitization to ovalbumin. Both sialylated and nonsialytated FetA bind to LPS, but only the former synergizes with LPS and grass pollen or mite allergens to enhance the Toll-like receptor 4-mediated proallergic properties of human dendritic cells. CONCLUSIONS: As a reflection of the patient's inflammatory status, pretreatment levels of sialylated FetA in the blood are indicative of the likelihood of clinical responses during grass pollen immunotherapy.

Protein kinase Cθ controls type 2 innate lymphoid cell and TH2 responses to house dust mite allergen.

BACKGROUND: Protein kinase C (PKC) θ, a serine/threonine kinase, is involved in TH2 cell activation and proliferation. Type 2 innate lymphoid cells (ILC2s) resemble TH2 cells and produce the TH2 cytokines IL-5 and IL-13 but lack antigen-specific receptors. The mechanism by which PKC-θ drives innate immune cells to instruct TH2 responses in patients with allergic lung inflammation remains unknown. OBJECTIVES: We hypothesized that PKC-θ contributes to ILC2 activation and might be necessary for ILC2s to instruct the TH2 response. METHODS: PRKCQ gene expression was assessed in innate lymphoid cell subsets purified from human PBMCs and mouse lung ILC2s. ILC2 activation and eosinophil recruitment, TH2-related cytokine and chemokine production, lung histopathology, interferon regulatory factor 4 (IRF4) mRNA expression, and nuclear factor of activated T cells (NFAT1) protein expression were determined. Adoptive transfer of ILC2s from wild-type mice was performed in wild-type and PKC-θ-deficient (PKC-θ-/-) mice. RESULTS: Here we report that PKC-θ is expressed in both human and mouse ILC2s. Mice lacking PKC-θ had reduced ILC2 numbers, TH2 cell numbers and activation, airway hyperresponsiveness, and expression of the transcription factors IRF4 and NFAT1. Importantly, adoptive transfer of ILC2s restored eosinophil influx and IL-4, IL-5 and IL-13 production in lung tissue, as well as TH2 cell activation. The pharmacologic PKC-θ inhibitor (Compound 20) administered during allergen challenge reduced ILC2 numbers and activation, as well as airway inflammation and IRF4 and NFAT1 expression. CONCLUSIONS: Therefore our findings identify PKC-θ as a critical factor for ILC2 activation that contributes to TH2 cell differentiation, which is associated with IRF4 and NFAT1 expression in allergic lung inflammation.