Citocinas epiteliales

Abstract

Studies have shown that eosinophilic COPD (eCOPD) is a distinct phenotype of the disease. It is well established that innate lymphoid cells are involved in the development of eosinophilic inflammation. Interleukin(IL)-25, thymic stromal lymphopoietin (TSLP) and IL-33 are a group of cytokines produced by epithelium in response to danger signals, e.g., cigarette smoke, and potent activators of ILC2s. In the present study, we examined circulating and sputum ILC2 numbers and expression of intracellular IL-5 as well as receptors for TSLP, IL-33 and IL-25 by ILC2s in non-atopic COPD patients with and without (neCOPD) airway eosinophilic inflammation and healthy smokers. In addition, we examined the association between ILC2s and clinical indicators of COPD burden (i.e., symptom intensity and risk of exacerbations). ILC2s were enumerated in peripheral blood and induced sputum by means of flow cytometry. We noted significantly greater numbers of airway IL-5+ILC2s and TSLPR+ILC2s in eCOPD compared with neCOPD (p < 0.05 and p < 0.01, respectively) and HSs (p < 0.001 for both). In addition, we showed that IL-5+ILC2s, IL-17RB+ILC2s and ST2+ILC2s are significantly increased in the sputum of eCOPD patients compared with HSs. In all COPD patients, sputum ILC2s positively correlated with sputum eosinophil percentage (r = 0.48, p = 0.002). We did not find any significant correlations between sputum ILC2s and dyspnea intensity as measured by the modified Medical Research Council scale (mMRC) and symptom intensity measured by the COPD Assessment Test (CAT). These results suggest the involvement of epithelial alarmin-activated ILC2s in the pathobiology of eosinophilic COPD.

Abstract

The term alarmin denotes a broad class of molecules rapidly released to alert the immune system through the engagement of specific receptors on immune cells. Three alarmin cytokines-thymic stromal lymphopoietin, IL-33, and IL-25-are released from epithelial and certain stromal cells. TNF-like cytokine 1A (TL1A) is a member of the TNF cytokine superfamily, first identified in human endothelial cells. TL1A is now considered a novel alarmin expressed by human and mouse bronchial and intestinal epithelial cells. TL1A exerts its biological activities by binding to a trimeric receptor DR3 (death receptor 3), expressed on a wide spectrum of immune and structural cells, including lung fibroblasts, endothelial cells, and bronchial epithelial cells. TL1A has been implicated in experimental and human inflammatory bowel diseases as well as in airway inflammation and remodeling in severe asthma. A monoclonal antibody anti-TL1A (tulisokibart) is effective in inducing clinical remission in ulcerative colitis patients. Increasing evidence suggests that TL1A is also involved in certain autoimmune disorders, such as rheumatoid arthritis and psoriasis. These emerging findings broaden the role of TL1A in various human inflammatory conditions. Several clinical trials are currently evaluating the safety and efficacy of monoclonal antibodies targeting TL1A in asthma or inflammatory bowel disease patients.

Abstract

Thymic stromal lymphopoietin (TSLP), mainly expressed by epithelial cells, plays a central role in asthma. In humans, TSLP exists in two variants: the long form TSLP (lfTSLP) and a shorter TSLP isoform (sfTSLP). Macrophages (HLMs) and mast cells (HLMCs) are in close proximity in the human lung and play key roles in asthma. We evaluated the early proteolytic effects of tryptase and chymase released by HLMCs on TSLP by mass spectrometry. We also investigated whether TSLP and its fragments generated by these enzymes induce angiogenic factor release from HLMs. Mass spectrometry (MS) allowed the identification of TSLP cleavage sites caused by tryptase and chymase. Recombinant human TSLP treated with recombinant tryptase showed the production of 1-97 and 98-132 fragments. Recombinant chymase treatment of TSLP generated two peptides, 1-36 and 37-132. lfTSLP induced the release of VEGF-A, the most potent angiogenic factor, from HLMs. By contrast, the four TSLP fragments generated by tryptase and chymase failed to activate HLMs. Long-term TSLP incubation with furin generated two peptides devoid of activating property on HLMs. These results unveil an intricate interplay between mast cell-derived proteases and TSLP. These findings have potential relevance in understanding novel aspects of asthma pathobiology.

Abstract

BACKGROUND: Thymic stromal lymphopoietin (TSLP) is released
from the airway epithelium in response to various environmental triggers, inducing a type-2 inflammatory response, and is associated with airway inflammation, airway hyperresponsiveness (AHR), and exacerbations. TSLP may also induce AHR via a direct effect on airway smooth muscle and mast cells, independently of type-2 inflammation, although association between airway TSLP and AHR across asthma phenotypes has been described sparsely.

OBJECTIVES: This study sought to investigate the association between AHR and levels of TSLP in serum, sputum, and bronchoalveolar lavage in patients with asthma with and without type-2 inflammation.

METHODS: A novel ultrasensitive assay was used to measure levels of TSLP in patients with asthma (serum, n=182; sputum, n=81; bronchoalveolar lavage, n=85) and healthy controls (serum, n=47). The distribution and association among airway and systemic TSLP, measures of AHR, type-2 inflammation, and severity of disease were assessed.

RESULTS: TSLP in sputum was associated with AHR independently of levels of eosinophils and fractional exhaled nitric oxide (r=0.49, P=.005). Serum TSLP was higher in both eosinophil-high and eosinophil-low asthma compared to healthy controls: geometric mean: 1600 fg/mL (95% CI: 1468-1744 fg/mL) and 1294 fg/mL (95% CI: 1167-1435 fg/mL) versus 846 fg/mL (95% CI: 661-1082 fg/mL), but did not correlate with the level of AHR. Increasing age, male sex, and eosinophils in blood were associated with higher levels of TSLP in serum, whereas lung function, inhaled corticosteroid dose, and symptom score were not.

CONCLUSIONS: The association between TSLP in sputum and AHR to mannitol irrespective of markers of type-2 inflammation further supports a role of TSLP in AHR that is partially independent of eosinophilic inflammation.

Abstract

BACKGROUND: Macrophages are the predominant immune cells in the human lung and play a central role in airway inflammation, including asthma and chronic obstructive pulmonary disease (COPD). Thymic stromal lymphopoietin (TSLP), a pleiotropic cytokine mainly expressed by bronchial epithelial cells, plays a key role in asthma and COPD pathobiology. TSLP exists in two variants: the long form (lfTSLP) and a shorter TSLP isoform (sfTSLP). We aimed to localize TSLP in human lung macrophages (HLMs) and investigate the mechanisms of its release from these cells. We also evaluated the effects of the two variants of TSLP on the release of angiogenic factor from HLMs.

METHODS: We employed immunofluorescence and Western blot to localize intracellular TSLP in HLMs purified from human lung parenchyma. HLMs were activated by T2-high (IL-4, IL-13) and T2-low (lipopolysaccharide: LPS) immunological stimuli.

RESULTS: TSLP was detected in HLMs and subcellularly localized in the cytoplasm. IL-4 and LPS induced TSLP release from HLMs. Preincubation of macrophages with brefeldin A, known to disrupt the Golgi apparatus, inhibited TSLP release induced by LPS and IL-4. lfTSLP concentration-dependently induced the release of vascular endothelial growth factor-A (VEGF-A), the most potent angiogenic factor, from HLMs. sfTSLP neither activated nor interfered with the activating property of lfTSLP on macrophages.

CONCLUSIONS: Our results highlight a novel immunologic circuit between HLMs and TSLP. Given the central role of macrophages in airway inflammation, this autocrine loop holds potential translational relevance in understanding innovative aspects of the pathobiology of asthma and chronic inflammatory lung disorders.

Abstract

This study delves into the critical role of alarmins in chronic spontaneous urticaria (CSU), focusing on their impact on disease severity and the quality of life (QoL) of patients. We investigated the alterations in alarmin levels in CSU patients and their correlations with the Urticaria Activity Score (UAS7) and the Dermatology Life Quality Index (DLQI). We analyzed serum levels of interleukin-25 (IL-25), interleukin-33 (IL-33), and thymic stromal lymphopoietin (TSLP) in 50 CSU patients, comparing these to 38 healthy controls. The study examined the relationship between alarmin levels and clinical outcomes, including disease severity and QoL. Elevated levels of IL-33 and TSLP in CSU patients (p < 0.0001) highlight their potential role in CSU pathogenesis. Although IL-25 showed higher levels in CSU patients, this did not reach statistical significance (p = 0.0823). Crucially, IL-33’s correlation with both UAS7 and DLQI scores underscores its potential as a biomarker for CSU diagnosis and severity assessment. Of the alarmins analyzed, IL-33 emerges as particularly significant for further exploration as a diagnostic and prognostic biomarker in CSU. Its substantial correlation with disease severity and impact on QoL makes it a compelling candidate for future research, potentially serving as a target for therapeutic interventions. Given these findings, IL-33 deserves additional investigation to confirm its role and effectiveness as a biomarker and therapeutic target in CSU.