Interleukin (IL)-4, IL-13, and IL-17A differentially affect the profibrotic and proinflammatory functions of fibrocytes from asthmatic patients

Targeting IL-13 and IL-4 in Asthma: Therapeutic Implications on Airway Remodeling in Severe Asthma

Asthma is a chronic respiratory disorder affecting individuals across all age groups. It is characterized by airway inflammation and remodeling and leads to progressive airflow restriction. While corticosteroids remain a mainstay therapy, their efficacy is limited in severe asthma due to genetic and epigenetic alterations, as well as elevated pro-inflammatory cytokines interleukin-4 (IL-4), interleukin-13 (IL-13), and interleukin-5 (IL-5), which drive structural airway changes including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. This underscores the critical need for biologically targeted therapies. This review systematically examines the roles of IL-4 and IL-13, key drivers of type-2 inflammation, in airway remodeling and their potential as therapeutic targets. IL-4 orchestrates eosinophil recruitment, immunoglobulin class switching, and Th2 differentiation, whereas IL-13 directly modulates structural cells, including fibroblasts and epithelial cells, to promote mucus hypersecretion and extracellular matrix (ECM) deposition. Despite shared signaling pathways, IL-13 emerges as the dominant cytokine in remodeling processes including mucus hypersecretion, fibrosis and smooth muscle hypertrophy. While IL-4 primarily amplifies inflammatory cascades by driving IgE switching, promoting Th2 cell polarization that sustain cytokine release, and inducing chemokines to recruit eosinophils. In steroid-resistant severe asthma, biologics targeting IL-4/IL-13 show promise in reducing exacerbations and eosinophilic inflammation. However, their capacity to reverse established remodeling remains inconsistent, as clinical trials prioritize inflammatory biomarkers over long-term structural outcomes. This synthesis highlights critical gaps in understanding the durability of IL-4/IL-13 inhibition on airway structure and advocates for therapies combining biologics with remodeling-specific strategies. Through the integration of mechanistic insights and clinical evidence, this review emphasizes the need for long-term studies utilizing advanced imaging, histopathological techniques, and patient-reported outcomes to evaluate how IL-4/IL-13-targeted therapies alter airway remodeling and symptom burden, thereby informing more effective treatment approaches for severe, steroid-resistant asthma.

Exploring the pathogenesis and clinical implications of asthma, chronic obstructive pulmonary disease (COPD), and asthma-COPD overlap (ACO): a narrative review

The complexity and diversity of the immune response in patients with asthma, chronic obstructive pulmonary disease (COPD), and asthma-COPD overlap present significant challenges for disease management. Relying on a limited number of biomarkers and clinical data is insufficient to fully reveal the immunopathogenesis of these diseases. However, in vitro technologies such as cell analysis, cytokine investigation, and nucleic acid sequencing have provided new insights into the underlying mechanisms of these diseases, leading to the discovery of several biomarkers-including cell degranulation, cell function, secreted cytokines, and single nucleotide polymorphisms-that have potential clinical implications. This paper reviews the immunopathogenesis in asthma, chronic obstructive pulmonary disease, and asthma-COPD overlap and examines the applications of recent in vitro models to detect candidate biomarkers that could enhance diagnostic precision, predict severity, monitor treatments, and develop new treatment strategies. A deeper understanding of the immune response in these diseases, along with the integration of in vitro models into clinical practice, could greatly improve the management of these respiratory diseases, making approaches more personalized and efficient.

Exploring the molecular mechanisms of asthma across multiple datasets

BACKGROUND

Asthma, a prevalent chronic respiratory disorder, remains enigmatic, notwithstanding considerable advancements in our comprehension. Continuous efforts are crucial for discovering novel molecular targets and gaining a comprehensive understanding of its pathogenesis.

MATERIALS AND METHODS

In this study, we analyzed gene expression data from 212 individuals, including asthma patients and healthy controls, to identify 267 differentially expressed genes, among which C1orf64 and C7orf26 emerged as potential key genes in asthma pathogenesis. Various bioinformatics tools, including differential gene expression analysis, pathway enrichment, drug target prediction, and single-cell analysis, were employed to explore the potential roles of the genes.

RESULTS

Quantitative PCR demonstrated differential expression of C1orf64 and C7orf26 in the asthmatic airway epithelial tissue, implying their potential involvement in asthma pathogenesis. GSEA enrichment analysis revealed significant enrichment of these genes in signaling pathways associated with asthma progression, such as ABC transporters, cell cycle, CAMs, DNA replication, and the Notch signaling pathway. Drug target prediction, based on upregulated and downregulated differential expression, highlighted potential asthma treatments, including Tyrphostin-AG-126, Cephalin, Verrucarin-a, and Emetine. The selection of these drugs was based on their significance in the analysis and their established anti-inflammatory and antiviral invasion properties. Utilizing Seurat and Celldex packages for single-cell sequencing analysis unveiled disease-specific gene expression patterns and cell types. Expression of C1orf64 and C7orf26 in T cells, NK cells, and B cells, instrumental in promoting hallmark features of asthma, was observed, suggesting their potential influence on asthma development and progression.

CONCLUSION

This study uncovers novel genetic aspects of asthma, highlighting potential therapeutic pathways. It exemplifies the power of integrative bioinformatics in decoding complex disease patterns. However, these findings require further validation, and the precise roles of C1orf64 and C7orf26 in asthma warrant additional investigation to validate their therapeutic potential.

Immunologic aspects of asthma: from molecular mechanisms to disease pathophysiology and clinical translation

In the present review, we focused on recent translational and clinical discoveries in asthma immunology, facilitating phenotyping and stratified or personalized interventions for patients with this condition. The immune processes behind chronic inflammation in asthma exhibit marked heterogeneity, with diverse phenotypes defining discernible features and endotypes illuminating the underlying molecular mechanisms. In particular, two primary endotypes of asthma have been identified: "type 2-high," characterized by increased eosinophil levels in the airways and sputum of patients, and "type 2-low," distinguished by increased neutrophils or a pauci-granulocytic profile. Our review encompasses significant advances in both innate and adaptive immunities, with emphasis on the key cellular and molecular mediators, and delves into innovative biological and targeted therapies for all the asthma endotypes. Recognizing that the immunopathology of asthma is dynamic and continuous, exhibiting spatial and temporal variabilities, is the central theme of this review. This complexity is underscored through the innumerable interactions involved, rather than being driven by a single predominant factor. Integrated efforts to improve our understanding of the pathophysiological characteristics of asthma indicate a trend toward an approach based on disease biology, encompassing the combined examination of the clinical, cellular, and molecular dimensions of the disease to more accurately correlate clinical traits with specific disease mechanisms.

Injury From Nematode Lung Migration Induces an IL-13-Dependent Hyaluronan Matrix

A consistent feature of lung injury is a rapid and sustained accumulation of hyaluronan (HA). The rodent gut-dwelling nematode Nippostrongylus brasiliensis (Nb) induces tissue damage as it migrates through the lungs. Type 2 immune responses are essential for the repair of the lungs, hence Nb infection is a well-established model to study immune-mediated lung repair. We found that Nb infection was associated with increased HA in the lung, which peaked at d7 post-infection (p.i.). Deposition of HA in the alveolar epithelium correlated with regions of damaged tissue and the type 2 immune response, which is characterized by eosinophilia and increased type 2 cytokines such as IL-13. Consistent with the accumulation of HA, we observed increased expression of the major synthase Has2, alongside decreased expression of Hyal1, Hyal2, and Tmem2, which can degrade existing HA. Expression of Tsg6 was also increased and correlated with the presence of inter-α-inhibitor heavy chain-HA complexes (HC·HA) at d7 p.i. Using IL-13-deficient mice, we found that the accumulation of HA during Nb infection was IL-13 dependent. Our data thus provide further evidence that IL-13 is a modulator of the HA matrix during lung challenge and links IL-13-mediated HA regulation to tissue repair pathways.

IL-17a-producing γδT cells and NKG2D signaling mediate bacterial endotoxin-induced neonatal lung injury: implications for bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease in preterm birth survivors characterized by inflammation, impaired alveolarization and dysmorphic vasculature. Activated IL-17A+ lymphocytes are key drivers of inflammation in preterm infants. We have shown that in immature mice chronic airway exposure to lipopolysaccharide (LPS) induces pulmonary inflammation, increased IL-17a expression, and hypoalveolarization, a BPD-like phenotype. The source of IL-17a and contribution to lung pathology is unknown. The natural-killer group 2, member D (NKG2D) receptor mediates activation and IL-17a production in γδ T cells by binding to stress molecules. LPS induces NKG2D ligand expression, including Rae-1 and MULT1. We hypothesized that IL-17a+ γδ T cells and NKG2D signaling mediate neonatal LPS-induced lung injury. Immature C57BL/6J (wild type), Nkg2d-/- or Tcrd-/- (lacking γδ T cells) mice were inoculated with 3ug/10ul of LPS from E. coli O26:B6 or 10ul of PBS intranasally on day of life 3, 5, 7, and 10. Selected mice were treated with neutralizing antibodies against IL-17a, or NKG2D intraperitoneally. Lung immune cells were assessed by flow cytometry and gene expression was analyzed by qPCR. Alveolar growth was assessed by lung morphometry. We established that anti-IL-17a antibody treatment attenuated LPS-induced hypoalveolarization. We found that LPS induced the fraction of IL-17a+NKG2D+ γδ T cells, a major source of IL-17a in the neonatal lung. LPS also induced lung mRNA expression of NKG2D, Rae-1, MULT1, and the DNA damage regulator p53. Anti-NKG2D treatment attenuated the effect of LPS on γδ T cell IL-17a expression, immune cell infiltration and hypoalveolarization. LPS-induced hypoalveolarization was also attenuated in Nkg2d-/- and Tcrd-/- mice. In tracheal aspirates of preterm infants IL-17A and its upstream regulator IL-23 were higher in infants who later developed BPD. Also, human ligands of NKG2D, MICA and MICB were present in the aspirates and MICA correlated with median FiO2. Our novel findings demonstrate a central role for activated IL-17a+ γδ T cells and NKG2D signaling in neonatal LPS-induced lung injury. Future studies will determine the role of NKG2D ligands and effectors, other NKG2D+ cells in early-life endotoxin-induced lung injury and inflammation with a long-term goal to understand how inflammation contributes to BPD pathogenesis.

Serum from patients with asthma potentiates macrophage phagocytosis and human mesenchymal stromal cell therapy in experimental allergic asthma

BACKGROUND/AIMS

Although several studies have demonstrated that mesenchymal stromal cells (MSCs) exhibit beneficial immunomodulatory properties in preclinical models of allergic asthma, effects on airway remodeling have been controversial. Recent evidence has shown that MSCs modify their in vivo immunomodulatory actions depending on the specific inflammatory environment encountered. Accordingly, we assessed whether the therapeutic properties of human mesenchymal stromal cells (hMSCs) could be potentiated by conditioning these cells with serum (hMSC-serum) obtained from patients with asthma and then transplanted in an experimental model of house dust mite (HDM)-induced allergic asthma.

METHODS

hMSC and hMSC-serum were administered intratracheally 24 h after the final HDM challenge. hMSC viability and inflammatory mediator production, lung mechanics and histology, bronchoalveolar lavage fluid (BALF) cellularity and biomarker levels, mitochondrial structure and function as well as macrophage polarization and phagocytic capacity were assessed.

RESULTS

Serum preconditioning led to: (i) increased hMSC apoptosis and expression of transforming growth factor-β, interleukin (IL)-10, tumor necrosis factor-α-stimulated gene 6 protein and indoleamine 2,3-dioxygenase-1; (ii) fission and reduction of the intrinsic respiratory capacity of mitochondria; and (iii) polarization of macrophages to M2 phenotype, which may be associated with a greater percentage of hMSCs phagocytosed by macrophages. Compared with mice receiving hMSCs, administration of hMSC-serum led to further reduction of collagen fiber content, eotaxin levels, total and differential cellularity and increased IL-10 levels in BALF, improving lung mechanics. hMSC-serum promoted greater M2 macrophage polarization as well as macrophage phagocytosis, mainly of apoptotic hMSCs.

CONCLUSIONS

Serum from patients with asthma led to a greater percentage of hMSCs phagocytosed by macrophages and triggered immunomodulatory responses, resulting in further reductions in both inflammation and remodeling compared with non-preconditioned hMSCs.

IL-25 induces airway remodeling in asthma by orchestrating the phenotypic changes of epithelial cell and fibrocyte

BACKGROUND

Previous studies have shown that IL-25 levels are increased in patients with asthma with fixed airflow limitation (FAL). However, the mechanism by which IL-25 contributes to airway remodeling and FAL remains unclear. Here, we hypothesized that IL-25 facilitates pro-fibrotic phenotypic changes in bronchial epithelial cells (BECs) and circulating fibrocytes (CFs), orchestrates pathological crosstalk from BECs to CFs, and thereby contributes to airway remodeling and FAL.

METHODS

Fibrocytes from asthmatic patients with FAL and chronic asthma murine models were detected using flow cytometry, multiplex staining and multispectral imaging analysis. The effect of IL-25 on BECs and CFs and on the crosstalk between BECs and CFs was determined using cell culture and co-culture systems.

RESULTS

We found that asthmatic patients with FAL had higher numbers of IL-25 receptor (i.e., IL-17RB)+-CFs, which were negatively correlated with forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC). The number of airway IL-17RB+-fibrocytes was significantly increased in ovalbumin (OVA)- and IL-25-induced asthmatic mice versus the control subjects. BECs stimulated with IL-25 exhibited an epithelial-mesenchymal transition (EMT)-like phenotypic changes. CFs stimulated with IL-25 produced high levels of extracellular matrix (ECM) proteins and connective tissue growth factors (CTGF). These profibrotic effects of IL-25 were partially blocked by the PI3K-AKT inhibitor LY294002. In the cell co-culture system, OVA-challenged BECs facilitated the migration and expression of ECM proteins and CTGF in CFs, which were markedly blocked using an anti-IL-17RB antibody.

CONCLUSION

These results suggest that IL-25 may serve as a potential therapeutic target for asthmatic patients with FAL.

A comprehensive network map of IL-17A signaling pathway

Interleukin-17A (IL-17A) is one of the member of IL-17 family consisting of other five members (IL-17B to IL-17F). The Gamma delta (γδ) T cells and T helper 17 (Th17) cells are the major producers of IL-17A. Aberrant signaling by IL-17A has been implicated in the pathogenesis of several autoimmune diseases including idiopathic pulmonary fibrosis, acute lung injury, chronic airway diseases, and cancer. Activation of the IL-17A/IL-17 receptor A (IL-17RA) system regulates phosphoinositide 3-kinase/AKT serine/threonine kinase/mammalian target of rapamycin (PI3K/AKT/mTOR), mitogen-activated protein kinases (MAPKs) and activation of nuclear factor-κB (NF-κB) mediated signaling pathways. The IL-17RA activation orchestrates multiple downstream signaling cascades resulting in the release of pro-inflammatory cytokines such as interleukins (IL)-1β, IL-6, and IL-8, chemokines (C-X-C motif) and promotes neutrophil-mediated immune response. Considering the biomedical importance of IL-17A, we developed a pathway resource of signaling events mediated by IL-17A/IL-17RA in this study. The curation of literature data pertaining to the IL-17A system was performed manually by the NetPath criteria. Using data mined from the published literature, we describe an integrated pathway reaction map of IL-17A/IL-17RA consisting of 114 proteins and 68 reactions. That includes detailed information on IL-17A/IL-17RA mediated signaling events of 9 activation/inhibition events, 17 catalysis events, 3 molecular association events, 68 gene regulation events, 109 protein expression events, and 6 protein translocation events. The IL-17A signaling pathway map data is made freely accessible through the WikiPathways Database ( https://www.wikipathways.org/index.php/Pathway : WP5242).

Circulating and renal fibrocytes are associated with interstitial fibrosis in lupus nephritis

OBJECTIVES

Fibrocytes, the extracellular matrix-producing cells derived from bone marrow progenitors, contribute to organ fibrosis. We investigated the presence and characteristics of fibrocytes in the peripheral blood and kidney of patients with lupus nephritis (LN), and the association of the abundance of fibrocytes with renal tubular epithelial cells (RTECs) in LN fibrogenesis.

METHODS

Fibrocytes were identified with type I collagen (colI), α-smooth muscle actin (α-SMA), CD34 and CD45 using flow cytometry and confocal imaging. The associations between the levels of fibrocytes and pathological features of patients with LN were analysed. The contribution of RTECs to fibrocyte generation was determined using LN sera-treated HK-2 cells.

RESULTS

Spindle-shaped fibrocytes (colI+α-SMA+CD34+CD45+ cells) were present in the peripheral blood and their abundance was especially high in LN patients with interstitial fibrosis compared with healthy control. Renal fibrocytes (colI+α-SMA+CD45+ cells) were found in the tubulointerstitium in patients with LN, and their numbers were significantly associated with the degrees of chronicity indices including interstitial fibrosis and renal dysfunction. Stimulation of peripheral blood mononuclear cells with supernatants from LN serum-treated HK-2 cells led to a significant generation of fibrocytes, which was abrogated by the addition of IL-6 neutralizing antibody.

CONCLUSION

Fibrocytes were significantly increased in the blood and kidney tissue of patients with LN, especially those with interstitial fibrosis. Fibrocytes could be differentiated from blood cells, with an active contribution from RTECs. Our results show a possible link between fibrocytes and tubulointerstitial fibrosis, which may serve as a novel therapeutic target for LN fibrogenesis.

Immunomodulatory effect of IL-2 induced bone marrow mononuclear cell therapy on control of allergic asthma

Asthma is a chronic airway disease. Allergic reactions and T helper (h)2 immune response play a key role in asthma occurrence. Cell therapy can control inflammation and remodeling responses in allergic asthma, and cytokines can change this effect. Therefore, in this study, the effect of treated cell therapy with IL-2 to control allergic asthma was studied. Bone marrow cells were extracted and co-cultured with IL-2 and the cells were used via intra-tracheal administration in allergic asthma mice. Levels of IL-4, IL-5, IL-13, Leukotriene B4 and C4, and remodeling factors were measured. At least, a histopathology test of lung tissue was done. Type2 cytokines, leukotrienes, remodeling factors, mucus secretion, goblet cell hyperplasia, peri-bronchial and peri-vascular inflammation were significantly (p˂0.05) decreased by treating with bone marrow-derived mononuclear cells (BMDMCs) and IL-2-BMDMCs. Treatment with IL-2-BMDMCs could significantly decrease IL-13, transforming growth factor (TGF)-β, HP levels, and mucus secretion (p˂0.05) compared to BMDMCs treatment. In this study, BMDMCs and IL-2-BMDMCs therapy could decrease inflammation, allergic, and remodeling factors in allergic asthma. Cell therapy with BMDMCs had a strong and notable effect on the control of allergic asthma pathophysiology when co-cultured and used with IL-2.

Potential roles of non-lymphocytic cells in the pathogenesis of IgG4-related disease

Studies have confirmed the involvement of a variety of lymphocyte subsets, including type 2 helper T lymphocytes (Th2) and IgG4+ B lymphocytes, in the pathogenesis of IgG4-related disease (IgG4-RD). Those lymphocytes contribute to the major pathogenetic features of IgG4-RD. However, they are not the only cellular components in the immunoinflammatory environment of this mysterious disease entity. Recent studies have suggested that various non-lymphocytic components, including macrophages and fibroblasts, may also play an important role in the pathogenetic process of IgG4-RD in terms of contributing to the chronic and complex progress of the disease. Therefore, the potential role of non-lymphocyte in the pathogenesis of IgG4-RD is worth discussing.

IL-23 plays a significant role in the augmentation of particulate matter-mediated allergic airway inflammation

It has been recently that particulate matter (PM) exposure increases the risk and exacerbation of allergic asthma. However, the underlying mechanisms and factors associated with increased allergic responses remain elusive. We evaluated IL-23 and IL-23R (receptor) expression, as well as changes in the asthmatic phenotype in mice administered PM and a low dose of house dust mite (HDM). Next, changes in the phenotype and immune responses were evaluated after intranasal administration of anti-IL-23 antibody during co-exposure to PM and low-dose HDM. We also performed in vitro experiments to investigate the effect of IL-23. IL-23 expression was significantly increased in Epcam+CD45- and CD11c+ cells, while that of IL-23R was increased in Epcam+CD45- cells only in mice administered PM and low-dose HDM. Administration of anti-IL-23 antibody led to decreased airway hyperresponsiveness, eosinophils, and activation of dendritic cells, reduced populations of Th2 Th17, ILC2, the level of IL-33 and granulocyte-macrophage colony-stimulating factor (GM-CSF). Inhibition of IL-23 in PM and low-dose HDM stimulated airway epithelial cell line resulted in decreased IL-33, GM-CSF and affected ILC2 and the activation of BMDCs. PM augmented the phenotypes and immunologic responses of asthma even at low doses of HDM. Interestingly, IL-23 affected immunological changes in airway epithelial cells.

Interaction Between CD34+ Fibrocytes and Airway Smooth Muscle Promotes IL-8 Production and Akt/PRAS40/mTOR Signaling in Asthma

Background

The circulating progenitor cells of fibroblasts (fibrocytes) have been shown to infiltrate the airway smooth muscle compartment of asthma patients; however, the pathological significance of this discovery has yet to be elucidated. This study established a co-culture model of airway smooth muscle cells (ASMCs) and fibrocytes from asthmatic or normal subjects to evaluate innate cytokine production, corticosteroid responses, and signaling in ASMCs.

Methods

CD34⁺ fibrocytes were purified from peripheral blood of asthmatic (Global Initiative for Asthma treatment step 4–5) and normal subjects and cultured for 5∼7 days. In a transwell plate, ASMCs were co-cultured with fibrocytes at a ratio of 2:1, ASMCs were cultured alone (control condition), and fibrocytes were cultured alone for 48 h. Measurements were obtained of interleukin-8 (IL-8), IL-6, IL-17, thymic stromal lymphopoietin, and IL-33 levels in the supernatant and IL-33 levels in the cell lysate of the co-culture. Screening for intracellular signaling in the ASMCs after stimulation was performed using condition medium from the patients’ co-culture (PtCM) or IL-8. mRNA and western blot analysis were used to analyze AKT/mTOR signaling in ASMCs stimulated via treatment with PtCM or IL-8.

Results

Compared with ASMCs cultured alone, IL-8 levels in the supernatant and IL-33 levels in the ASMCs lysate were significantly higher in samples co-cultured from asthmatics, but not in those co-cultured from normal subjects. Corticosteroid-induced suppression of IL-8 production was less pronounced in ASMCs co-cultured with fibrocytes from asthma patients than in ASMCs co-cultured from normal subjects. ASMCs stimulated using PtCM and IL-8 presented elevating activated AKT substrate PRAS40. Treatment with IL-8 and PtCM increased mRNA expression of mTOR and P70S6 kinases in ASMCs. Treatment with IL-8 and PtCM also significantly increased phosphorylation of AKT and mTOR subtract S6 ribosomal protein in ASMCs.

Conclusion

The interaction between ASMCs and fibrocytes from asthmatic patients was shown to increase IL-8 and IL-33 production and promote AKT/mTOR signaling in ASMCs. IL-8 production in the co-culture from asthmatic patients was less affected by corticosteroid than was that in the co-culture from normal subjects. Our results elucidate the novel role of fibrocytes and ASMCs in the pathogenesis of asthma.

Role of Th17 Cytokines in Airway Remodeling in Asthma and Therapy Perspectives

Airway remodeling is a frequent pathological feature of severe asthma leading to permanent airway obstruction in up to 50% of cases and to respiratory disability. Although structural changes related to airway remodeling are well-characterized, immunological processes triggering and maintaining this phenomenon are still poorly understood. As a consequence, no biotherapy targeting cytokines are currently efficient to treat airway remodeling and only bronchial thermoplasty may have an effect on bronchial nerves and smooth muscles with uncertain clinical relevance. Th17 cytokines, including interleukin (IL)-17 and IL-22, play a role in neutrophilic inflammation in severe asthma and may be involved in airway remodeling. Indeed, IL-17 is increased in sputum from severe asthmatic patients, induces the expression of "profibrotic" cytokines by epithelial, endothelial cells and fibroblasts, and provokes human airway smooth muscle cell migration in in vitro studies. IL-22 is also increased in asthmatic samples, promotes myofibroblast differentiation, epithelial-mesenchymal transition and proliferation and migration of smooth muscle cells in vitro. Accordingly, we also found high levels of IL-17 and IL-22 in a mouse model of dog-allergen induced asthma characterized by a strong airway remodeling. Clinical trials found no effect of therapy targeting IL-17 in an unselected population of asthmatic patients but showed a potential benefit in a sub-population of patients exhibiting a high level of airway reversibility, suggesting a potential role on airway remodeling. Anti-IL-22 therapies have not been evaluated in asthma yet but were demonstrated efficient in severe atopic dermatitis including an effect on skin remodeling. In this review, we will address the role of Th17 cytokines in airway remodeling through data from in vitro, in vivo and translational studies, and examine the potential place of Th17-targeting therapies in the treatment of asthma with airway remodeling.

The Role of CD4+ T Cells and Microbiota in the Pathogenesis of Asthma

Asthma, a chronic respiratory disease involving variable airflow limitations, exhibits two phenotypes: eosinophilic and neutrophilic. The asthma phenotype must be considered because the prognosis and drug responsiveness of eosinophilic and neutrophilic asthma differ. CD4+ T cells are the main determinant of asthma phenotype. Th2, Th9 and Tfh cells mediate the development of eosinophilic asthma, whereas Th1 and Th17 cells mediate the development of neutrophilic asthma. Elucidating the biological roles of CD4+ T cells is thus essential for developing effective asthma treatments and predicting a patient's prognosis. Commensal bacteria also play a key role in the pathogenesis of asthma. Beneficial bacteria within the host act to suppress asthma, whereas harmful bacteria exacerbate asthma. Recent literature indicates that imbalances between beneficial and harmful bacteria affect the differentiation of CD4+ T cells, leading to the development of asthma. Correcting bacterial imbalances using probiotics reportedly improves asthma symptoms. In this review, we investigate the effects of crosstalk between the microbiota and CD4+ T cells on the development of asthma.

Translational targeting of inflammation and fibrosis in frozen shoulder: Molecular dissection of the T cell/IL-17A axis

Frozen shoulder is a common fibroproliferative disease characterized by the insidious onset of pain and restricted range of shoulder movement with a significant socioeconomic impact. The pathophysiological mechanisms responsible for chronic inflammation and matrix remodeling in this prevalent fibrotic disorder remain unclear; however, increasing evidence implicates dysregulated immunobiology. IL-17A is a key cytokine associated with inflammation and tissue remodeling in numerous musculoskeletal diseases, and thus, we sought to determine the role of IL-17A in the immunopathogenesis of frozen shoulder. We demonstrate an immune cell landscape that switches from a predominantly macrophage population in nondiseased tissue to a T cell-rich environment in disease. Furthermore, we observed a subpopulation of IL-17A-producing T cells capable of inducing profibrotic and inflammatory responses in diseased fibroblasts through enhanced expression of the signaling receptor IL-17RA, rendering diseased cells more sensitive to IL-17A. We further established that the effects of IL-17A on diseased fibroblasts was TRAF-6/NF-κB dependent and could be inhibited by treatment with an IKKβ inhibitor or anti-IL-17A antibody. Accordingly, targeting of the IL-17A pathway may provide future therapeutic approaches to the management of this common, debilitating disease.

IL-25R+ circulating fibrocytes are increased in asthma and correlate with fixed airflow limitation

INTRODUCTION

Interleukin (IL)-25 is a T helper (Th) type-2 cytokine implicated in the pathogenesis of asthma. Fibrocytes are progenitor cells that can migrate into circulation and inflamed bronchial epithelium.

OBJECTIVES

We aim to test the hypothesis that circulating fibrocytes may be the novel cellular targets of IL-25 and the recruitment of IL-25R⁺ circulating fibrocytes may correlate with asthmatic airway obstruction.

METHODS

By using flow cytometry analysis, IL-25R⁺ fibrocytes (i.e., IL-17RB⁺ fibrocytes) in the freshly isolated peripheral blood mononuclear cells (PBMCs) from 15 control subjects and 35 patients with asthma were enumerated and compared. Enzyme-linked immunosorbent assay (ELISA) was used to detect the plasma levels of IL-25.

RESULTS

We found the percentage of total and IL-25R⁺ (IL-17RB⁺ ) fibrocytes in PBMCs was significantly increased in patients with asthma when compared with control subjects. Subgroup analysis further showed that the percentage of circulating total and IL-25R⁺ fibrocytes in PBMCs was markedly increased in asthma patients with severe-to-very severe fixed airflow limitation. Furthermore, IL-25R⁺ circulating fibrocytes in asthma patients were shown to significantly correlate with forced expiratory volume in 1 s/forced vital capacity (FEV₁ /FVC), FEV₁ % predicted, blood eosinophils, serum IgE and plasma IL-25 levels.

CONCLUSION

We concluded that circulating fibrocytes are the novel potential cellular targets of IL-25. IL-25R⁺ fibrocytes are increased in asthma patients. Increased proportions of IL-25R⁺ fibrocytes predict a distinct asthma phenotype with fixed airflow limitation. Biological therapy-targeting IL-25-fibrocytes axis may offer great promise for the control of asthma patients with severe airway remodelling and obstruction.

USP4 is pathogenic in allergic airway inflammation by inhibiting regulatory T cell response

AIMS

Asthma is characterized by chronic inflammation and airway hyperresponsiveness (AHR). It is controllable, but not curable. Ubiquitin-specific peptidase 4 (USP4) has been verified as a regulator of regulatory T (Treg) cells and Th17 cells in vitro. In this study, we aim to investigate whether USP4 could serve as a therapeutic target for asthma.

MAIN METHODS

Age-matched USP4 wild-type and knockout mice received an intraperitoneal injection of 100 μg ovalbumin (OVA) mixed in 2 mg aluminum hydroxide in 1 × PBS on days 0, 7 and 14. On days 21 to 27, the mice were challenged with aerosolized 1% OVA in 1 × PBS for 30 min. Tissue histology, ELISA and flow cytometry were applied 24 h after the last OVA challenge.

KEY FINDINGS

USP4 deficiency protected mice from OVA-induced AHR and decreased the production of several inflammatory cytokines in T cells in vivo. Compared to the lung cells isolated from WT mice, Usp4^-/- lung cells decreased secretion of IL-4, IL-13 and IL-17A upon stimulation in vitro. Meanwhile, the percentage of CD4⁺Foxp3⁺ Treg cells was elevated, with more CCR6⁺Foxp3⁺ Treg cells accumulating in the lungs of OVA-challenged USP4 deficient mice than in their wild-type counterparts. Treatment with the USP4 inhibitor, Vialinin A, reduced inflammatory cell infiltration in the lungs of OVA-challenged mice in vivo.

SIGNIFICANCE

We found USP4 deficiency contributes to attenuated airway inflammation and AHR in allergen-induced murine asthma, and Vialinin A treatment alleviates asthma pathogenesis and may serve as a promising therapeutic target for asthma.

Anti-IgE therapy inhibits chemotaxis, proliferation and transformation of circulating fibrocytes in patients with severe allergic asthma

BACKGROUND AND OBJECTIVE

Circulating fibrocytes act as precursors of myofibroblasts, contribute to airway remodelling in chronic asthma and migrate to injured tissues by expressing CXCR4 and CCR7. Anti-IgE therapy improves severe allergic asthma (SAA) control and airway remodelling in T2-high SAA. The effects of anti-IgE therapy on fibrocyte activities were investigated in this study.

METHODS

The expression of CCR7, CXCR4, ST2 and α-SMA (α-smooth muscle actin) in both circulating and cultured fibrocytes from all patients with asthma was measured, and was repeated after omalizumab treatment in SAA. Fibrocytes recruitment, proliferation and transformation were also measured in response to anti-IgE therapy.

RESULTS

Omalizumab effectively improved asthma control and pulmonary function in T2-high SAA, associated with a decline in serum levels of IL-33 and IL-13. Omalizumab down-regulates CXCR4 and CCR7 expression of fibrocytes, which could suppress fibrocyte recruitment into the lungs. Omalizumab also suppressed the increased number of fibrocytes and α-SMA⁺ fibrocytes within the cultured non-adherent non-T (NANT) cells after 3-7 days of culture. The decrease in serum levels of IL-33 by omalizumab contributed to the effectiveness in inhibiting fibrocyte recruitment, proliferation and myofibroblast transformation through IL-33/ST2 axis. The elevated IL-13 expression in SAA patients potentiated the effects of IL-33 by increasing ST2 expression.

CONCLUSION

Omalizumab reduced the number of circulating fibrocytes, cell and number of fibrocytes as well as α-SMA⁺ fibrocytes after 3-7 days of culture in SAA patients. IL-33 and IL-13 may be implicated in the effectiveness of omalizumab in inhibiting fibrocyte activation contributing partly to the clinical benefits in reducing lamina propria and basement membrane thickening.

Andrographolide Inhibition of Th17-Regulated Cytokines and JAK1/STAT3 Signaling in OVA-Stimulated Asthma in Mice

Asthma has long been considered a disease of airway inflammation. The excessive or prolonged production of inflammatory mediators can result in airway remodeling and severe clinical syndromes such as dyspnea or even apnea. Therefore, pharmaceutical intervention is required to restrain the excessive release of such inflammatory mediators in control of asthma. Novel therapeutics and mechanistic insight are sought for the management of this chronic inflammatory disease. Andrographolide (AG) is a type of diterpenoid ester compound and is reported to demonstrate multiple properties such as antioxidation and anti-inflammation. However, the anti-inflammatory capacity of AG by regulating immunologic function in airway of asthma has not been fully studied to date. Therefore, this study investigates whether AG is capable of suppressing the inflammatory response of asthma in OVA-stimulated mice and the mechanism by which this is achieved. Animals were randomly divided into 4 groups: control group, OVA model group, OVA + AG (0.1 mg/ml) group, and OVA + dimethylsulfoxide (DMSO) group. The serum, BALF, and lung tissue of the mice were collected separately for the administration of ELISA, rt-PCR, western blot and pathological section and staining. We found that AG attenuated the OVA-induced production of IL-6, IL-17A, IL-17F, and RORγt; inhibited the OVA-mediated phosphorylation of JAK 1 and STAT3; and alleviated airway remodeling and the neutrophil infiltration of lung tissue. We conclude that AG inhibits the inflammatory response of asthma in OVA-stimulated mice by blocking the activation of Th17-regulated cytokines and the JAK1/STAT3 signaling pathway.

Impact of Orthodontic Forces on Plasma Levels of Markers of Bone Turnover and Inflammation in a Rat Model of Buccal Expansion

Plasma levels of protein analytes might be markers to predict and monitor the kinetics of bone and tissue remodeling, including maximization of orthodontic treatment stability. They could help predict/prevent and/or diagnose possible adverse effects such as bone dehiscences, gingival recession, or root resorption. The objective of this study was to measure plasma levels of markers of bone turnover and inflammation during orthodontic force application in a rat model of orthodontic expansion. Two different orthodontic forces for bilateral buccal expansion of the maxillary arches around second and third molars were applied in 10 rats equally distributed in low-force (LF) or conventional force (CF) groups. Four rats served as the control group. Blood samples were collected at days 0, 1, 2, 3, 6, 13, 21, and 58. Longitudinal concentrations of osteoprotegerin (OPG), soluble receptor activator of nuclear factor kappaB ligand (sRANKL), interleukin-4 (IL-4), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor α (TNF), and parathyroid hormone (PTH) were determined in blood samples by a multiplex immunoassay. CF and LF resulted in a significantly maxillary skeletal expansion while the CF group demonstrated significantly higher expansion than the LF group in the long term. Bone turnover demonstrated a two-phase response. During the “early phase” (up to 6 days of force application), LF resulted in more sRANKL expression and increased sRANKL/OPG ratio than the CF and control animals. There was a parallel increase in PTH levels in the early phase in response to LF. During the “late phase” (6–58 days), the markers of bone turnover were stable in both groups. IL-4, IL-6, and IL-10 levels did not significantly change the test groups throughout the study. These results suggest that maxillary expansion in response to different orthodontic forces follows different phases of bone turnover that may be force specific.

iTRAQ-based proteomic analysis reveals potential serum biomarkers of allergic and nonallergic asthma

BACKGROUND

Asthma is heterogeneous disease with different phenotypes, endotypes and severities. Definition of these subgroups requires the identification of biomarkers in biological samples, and serum proteomics is a useful and minimally invasive method for this purpose. Therefore, the aim of this study was to detect serum proteins whose abundance is distinctively associated with different asthma phenotypes (allergic vs nonallergic) or severities.

METHODS

For each group of donors (32 healthy controls, 43 allergic rhinitis patients and 192 asthmatics with different phenotypes and severities), we generated two pools of sera that were analysed by a shotgun MS approach based on combinatorial peptide ligand libraries and iTRAQ-LC-MS/MS.

RESULTS

MS analyses identified 18 proteins with a differential abundance. Functional/network study of these proteins identified key processes for asthma pathogenesis, such as complement activation, extracellular matrix organization, platelet activation and degranulation, or post-translational protein phosphorylation. Furthermore, our results highlighted an enrichment of the "Regulation of Insulin-like Growth Factor (IGF) transport and uptake by Insulin-like Growth Factor Binding Proteins (IGFBPs)" route in allergic asthma and the lectin pathway of complement activation in nonallergic asthma. Thus, several proteins (eg IGFALS, HSPG2, FCN2 or MASP1) displayed a differential abundance between the different groups of donors. Particularly, our results revealed IGFALS as a useful biomarker for moderate-severe allergic asthma.

CONCLUSION

Our data suggest a set of serum biomarkers, especially IGFALS, capable of differentiating allergic from nonallergic asthma. These proteins reveal different pathophysiological mechanisms and may be useful in the future for diagnosis, prognosis or targeted therapy purposes.

Fibrocyte localisation to the ASM bundle in asthma: bidirectional effects on cell phenotype and behaviour

Objectives

Airway hyper‐responsiveness and persistent airflow obstruction contribute to asthma pathogenesis and symptoms, due in part to airway smooth muscle (ASM) hypercontractility and increased ASM mass. Fibrocytes have been shown to localise to the ASM in asthma however it is not known whether fibrocytes localise to the ASM in nonasthmatic eosinophilic bronchitis (NAEB) and chronic obstructive pulmonary disease (COPD). In addition, the potential consequences of fibrocyte localisation to ASM as regards asthma pathophysiology has not been widely studied.

Methods

Fibrocytes and proliferating cells were enumerated in ASM in bronchial tissue using immunohistochemistry. The effects of primary ASM and fibrocytes upon each other in terms of phenotype and behaviour following co‐culture were investigated by assessing cell number, size, apoptotic status, phenotype and contractility in in vitro cell‐based assays.

Results

Increased fibrocyte number in the ASM was observed in asthma versus NAEB, but not NAEB and COPD versus controls, and confirmed in asthma versus controls. ASM proliferation was not detectably different in asthmatics versus healthy controls in vivo. No difference in proliferation, apoptotic status or size of ASM was seen following culture with/without fibrocytes. Following co‐culture with ASM from asthmatics versus nonasthmatics, fibrocyte smooth muscle marker expression and collagen gel contraction were greater. Following co‐culture, fibrocyte CD14 expression was restored with the potential to contribute to asthma pathogenesis via monocyte‐mediated processes dependent on the inflammatory milieu.

Conclusion

Further understanding of mechanisms of fibrocyte recruitment to and/or differentiation within the ASM may identify novel therapeutic targets to modulate ASM dysfunction in asthma.

Circulating fibrocytes as prognostic biomarkers of autoimmune interstitial lung disease

Background

Autoimmunity is a common cause of pulmonary fibrosis and can present either as a manifestation of an established connective tissue disease or as the recently described entity of interstitial pneumonia with autoimmune features. The rate of progression and responsiveness to immunosuppression in these illnesses are difficult to predict. Circulating fibrocytes are bone marrow-derived progenitor cells that home to injured tissues and contribute to lung fibrogenesis. We sought to test the hypothesis that the blood fibrocyte concentration predicts outcome and treatment responsiveness in autoimmune interstitial lung diseases.

Methods

We compared the concentration of circulating fibrocytes in 50 subjects with autoimmune interstitial lung disease and 26 matched healthy controls and assessed the relationship between serial peripheral blood fibrocyte concentrations and clinical outcomes over a median of 6.25 years.

Results

As compared to controls, subjects with autoimmune interstitial lung disease had higher circulating concentrations of total fibrocytes, the subset of activated fibrocytes, and fibrocytes with activation of PI3K/AKT/mTOR, transforming growth factor-β (TGF-β) receptor and interleukin (IL)-4/IL-13 receptor signalling pathways. Over the follow-up period, there were episodes of marked elevation in the concentration of circulating fibrocytes in subjects with autoimmune interstitial lung disease but not controls. Initiation of immunosuppressive therapy was associated with a decline in the concentration of circulating fibrocytes. For each 100 000 cells·mL⁻¹ increase in peak concentration of circulating fibrocytes, we found a 5% increase in odds of death or lung function decline.

Conclusion

In patients with autoimmune interstitial lung disease, circulating fibrocytes may represent a biomarker of outcome and treatment response.

Autoimmune diseases are common causes of pulmonary fibrosis. The blood concentration of fibrocytes, cells involved in formation of scar tissue, predicts outcomes and response to immunosuppression in these patients.https://bit.ly/35bel62

A molecular basis for the anti-inflammatory and anti-fibrosis properties of cannabidiol

Cannabidiol (CBD) is considered a non-psychoactive, antioxidant, and anti-inflammatory compound derived from the Cannabis sativa plant. There are various reports on the versatile function of CBD, including ameliorating chronic inflammation and fibrosis formation in several tissue types. However, only a hand full of studies have proposed or provided a molecular justification for the beneficial properties of this Phyto-compound. This review focused on the anti-inflammation and anti-fibrotic effects of CBD based on modulating the associated chemokines/cytokines and receptor-mediated pathways. We also highlighted the regulatory impact of CBD on reactive oxygen species (ROS) producing-NADPH oxidase (Nox), and ROS scavenging-superoxide dismutase (SOD) enzymes. Although CBD has a low affinity to Cannabinoid receptors 1 and 2 (CB₁ and CB₂ ), we reported on the activation of these receptors by other CBD analogs, and CBD on non-CBD receptors. CBD downregulates pro-inflammatory and pro-fibrotic chemokines/cytokines by acting as direct or indirect agonists of Adenosine A_2A /equilibrative nucleoside transporter receptors, Peroxisome proliferator-activated receptor gamma, and Transient receptor potential vanilloid receptors or channels, and as an antagonist of GPR55 receptors. CBD also caused the reduction and enhancement of the ROS producing, Nox and ROS-scavenging, SOD enzyme activities, respectively. This review thus recommends the continued study of CBD's molecular mechanism in treating established and emerging inflammatory and fibrosis-related diseases.

Childhood asthma heterogeneity at the era of precision medicine: Modulating the immune response or the microbiota for the management of asthma attack

Exacerbations are a main characteristic of asthma. In childhood, the risk is increasing with severity. Exacerbations are a strong phenotypic marker, particularly of severe and therapy-resistant asthma. These early-life events may influence the evolution and be involved in lung function decline. In children, asthma attacks are facilitated by exposure to allergens and pollutants, but are mainly triggered by microbial agents. Multiple studies have assessed immune responses to viruses, and to a lesser extend bacteria, during asthma exacerbation. Research has identified impairment of innate immune responses in children, related to altered pathogen recognition, interferon release, or anti-viral response. Influence of this host-microbiota dialog on the adaptive immune response may be crucial, leading to the development of biased T helper (Th)2 inflammation. These dynamic interactions may impact the presentations of asthma attacks, and have long-term consequences. The aim of this review is to synthesize studies exploring immune mechanisms impairment against viruses and bacteria promoting asthma attacks in children. The potential influence of the nature of infectious agents and/or preexisting microbiota on the development of exacerbation is also addressed. We then discuss our understanding of how these diverse host-microbiota interactions in children may account for the heterogeneity of endotypes and clinical presentations. Finally, improving the knowledge of the pathophysiological processes induced by infections has led to offer new opportunities for the development of preventive or curative therapeutics for acute asthma. A better definition of asthma endotypes associated with precision medicine might lead to substantial progress in the management of severe childhood asthma.

The role of NTHi colonization and infection in the pathogenesis of neutrophilic asthma

Asthma is a complex heterogeneous disease. The neutrophilic subtypes of asthma are described as persistent, more severe and corticosteroid-resistant, with higher hospitalization and mortality rates, which seriously affect the lives of asthmatic patients. With the development of high-throughput sequencing technology, an increasing amount of evidence has shown that lower airway microbiome dysbiosis contributes to the exacerbation of asthma, especially neutrophilic asthma. Nontypeable Haemophilus influenzae is normally found in the upper respiratory tract of healthy adults and is one of the most common strains in the lower respiratory tract of neutrophilic asthma patients, in whom its presence is related to the occurrence of corticosteroid resistance. To understand the pathogenic mechanism by which nontypeable Haemophilus influenzae colonization leads to the progression of neutrophilic asthma, we reviewed the previous literature on nontypeable Haemophilus influenzae colonization and subsequent aggravation of neutrophilic asthma and corticosteroid resistance. We discussed nontypeable Haemophilus influenzae as a potential therapeutic target to prevent the progression of neutrophilic asthma.

Differential DNA methylation profiles of peripheral blood mononuclear cells in allergic asthmatic children following dust mite immunotherapy

BACKGROUND/PURPOSE

Allergen-specific immunotherapy (SIT) is now considered curative to allergic diseases such as asthma. Mechanistically, our previous work showed DNA hypermethylation of cytokine genes, in T-helper cells, in allergic asthmatic children treated with allergen-SIT. In this study, we extended to work to assess possible changes in the DNA methylomes of peripheral blood mononuclear cells (PBMCs), isolated from mite allergen-SIT asthmatic children, to explore further the underlying methylation changes.

METHODS

Thirteen allergic asthmatic children who received Der p-SIT, 12 non-SIT allergic asthmatic controls, and 12 healthy controls were enrolled. Bisulfite-converted DNA from Der p-stimulated PBMCs was analyzed using Human Methylation 450 k BeadChip. Pyrosequencing and quantitative real-time PCR were used to validate the DNA methylation levels and the gene expression of individual samples.

RESULTS

We identified 108 significantly differentially methylated regions (DMRs) unique to Der p-treated PBMCs, with 53 probes linked to demethylated DMRs, and 55 probes linked to methylated DMRs. Three associated genes (BCL6, HSPG2, and HSP90AA1), of selected DMRs, were subjected to bisulfite pyrosequencing. Of these, BCL6 showed significant hypomethylation, while HSPG2 and HSP90AA1 were hypermethylated in SIT group, compared to the AA group. Furthermore, SIT group had significantly higher gene expression of BCL6 and lower gene expression of HSPG2. KEGG pathway analysis further revealed DMR genes involved in ECM-receptor interactions, asthma, and antigen processing and presentation pathways.

CONCLUSIONS

Several DNA regions showed DNA methylation altered by Der p specific immunotherapy, indicating desensitization-associated methylomes. Genes belonging to these SIT-altered pathways may represent therapeutic targets for better clinical management of asthma.

Phenotypes and endotypes of adult asthma: Moving toward precision medicine

Asthma is a chronic inflammatory disease of the airways that is challenging to dissect into subgroups because of the heterogeneity present across the spectrum of the disease. Efforts to subclassify asthma using advanced computational methods have identified a number of different phenotypes that suggest that multiple pathobiologically driven clusters of disease exist. The main phenotypes that have been identified include (1) early-onset allergic asthma, (2) early-onset allergic moderate-to-severe remodeled asthma, (3) late-onset nonallergic eosinophilic asthma, and (4) late-onset nonallergic noneosinophilic asthma. Subgroups of these phenotypes also exist but have not been as consistently identified. Advances in our understanding of the diverse immunologic perturbations that drive airway inflammation are consistent with clinical traits associated with these phenotypes and their response to biologic therapies. This has improved the clinician's approach to characterizing asthmatic patients in the clinic. Being able to define asthma endotypes using clinical characteristics and biomarkers will move physicians toward even more personalized management of asthma and precision-based care in the future. Here we will review the most prominent phenotypes and immunologic advances that suggest these disease subtypes represent asthma endotypes.

Kinase inhibitors in the treatment of obstructive pulmonary diseases

Chronic pulmonary diseases, including chronic obstructive pulmonary disease (COPD) and asthma, are major causes of death and reduced quality of life. Characteristic of chronic pulmonary disease is excessive lung inflammation that occurs in response to exposure to inhaled irritants, chemicals, and allergens. Chronic inflammation leads to remodeling of the airways that includes excess mucus secretion, proliferation of smooth muscle cells, increased deposition of extracellular matrix proteins and fibrosis. Protein kinases have been implicated in mediating inflammatory signals and airway remodeling associated with reduced lung function in chronic pulmonary disease. This review will highlight the role of protein kinases in the lung during chronic inflammation and examine opportunities to use protein kinase inhibitors for the treatment of chronic pulmonary diseases.

Fibrocytes, Wound Healing, and Corneal Fibrosis

Purpose

This review highlights the roles of fibrocytes—their origin, markers, regulation and functions—including contributions to corneal wound healing and fibrosis.

Methods

Literature review.

Results

Peripheral blood fibroblast-like cells, called fibrocytes, are primarily generated as mature collagen-producing cells in the bone marrow. They are likely derived from the myeloid lineage, although the exact precursor remains unknown. Fibrocytes are identified by a combination of expressed markers, such as simultaneous expression of CD34 or CD45 or CD11b and collagen type I or collagen type III. Fibrocytes migrate into the wound from the blood where they participate in pathogen clearance, tissue regeneration, wound closure and angiogenesis. Transforming growth factor beta 1 (TGF-β₁) and adiponectin induce expression of α-smooth muscle actin and extracellular matrix proteins through activation of Smad3 and adenosine monophosphate-activated protein kinase pathways, respectively. Fibrocytes are important contributors to the cornea wound healing response and there are several mechanisms through which fibrocytes contribute to fibrosis in the cornea and other organs, such as their differentiation into myofibroblasts, production of matrix metalloproteinase, secretion of tissue inhibitor of metalloproteinase, and release of TGF-β₁. In some tissues, fibrocytes may also contribute to the basement membrane regeneration and to the resolution of fibrosis.

Conclusions

New methods that block fibrocyte generation, fibrocyte migration, and their differentiation into myofibroblasts, as well as their production of matrix metalloproteinases, tissue inhibitor of metalloproteinase, and TGF-β₁, have therapeutic potential to reduce the accumulation of collagens, maintain tissue integrity and retard or prevent the development of fibrosis.

Inflammatory mechanisms linking maternal and childhood asthma

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness, inflammation, and remodeling. Asthma often develops during childhood and causes lifelong decrements in lung function and quality of life. Risk factors for childhood asthma are numerous and include genetic, epigenetic, developmental, and environmental factors. Uncontrolled maternal asthma during pregnancy exposes the developing fetus to inflammatory insults, which further increase the risk of childhood asthma independent of genetic predisposition. This review focuses on the role of maternal asthma in the development of asthma in offspring. We will present maternal asthma as a targetable and modifiable risk factor for childhood asthma and discuss the mechanisms by which maternal inflammation increases childhood asthma risk. Topics include how exposure to maternal asthma in utero shapes structural lung development with a special emphasis on airway nerves, how maternal type-2 cytokines such as IL-5 activate the fetal immune system, and how changes in lung and immune cell development inform responses to aero-allergens later in life. Finally, we highlight emerging evidence that maternal asthma establishes a unique "asthma signature" in the airways of children, leading to novel mechanisms of airway hyperreactivity and inflammatory cell responses.

G Protein-Coupled Receptors in Asthma Therapy: Pharmacology and Drug Action

Asthma is a heterogeneous inflammatory disease of the airways that is associated with airway hyperresponsiveness and airflow limitation. Although asthma was once simply categorized as atopic or nonatopic, emerging analyses over the last few decades have revealed a variety of asthma endotypes that are attributed to numerous pathophysiological mechanisms. The classification of asthma by endotype is primarily routed in different profiles of airway inflammation that contribute to bronchoconstriction. Many asthma therapeutics target G protein-coupled receptors (GPCRs), which either enhance bronchodilation or prevent bronchoconstriction. Short-acting and long-acting β 2-agonists are widely used bronchodilators that signal through the activation of the β 2-adrenergic receptor. Short-acting and long-acting antagonists of muscarinic acetylcholine receptors are used to reduce bronchoconstriction by blocking the action of acetylcholine. Leukotriene antagonists that block the signaling of cysteinyl leukotriene receptor 1 are used as an add-on therapy to reduce bronchoconstriction and inflammation induced by cysteinyl leukotrienes. A number of GPCR-targeting asthma drug candidates are also in different stages of development. Among them, antagonists of prostaglandin D2 receptor 2 have advanced into phase III clinical trials. Others, including antagonists of the adenosine A2B receptor and the histamine H4 receptor, are in early stages of clinical investigation. In the past decade, significant research advancements in pharmacology, cell biology, structural biology, and molecular physiology have greatly deepened our understanding of the therapeutic roles of GPCRs in asthma and drug action on these GPCRs. This review summarizes our current understanding of GPCR signaling and pharmacology in the context of asthma treatment. SIGNIFICANCE STATEMENT: Although current treatment methods for asthma are effective for a majority of asthma patients, there are still a large number of patients with poorly controlled asthma who may experience asthma exacerbations. This review summarizes current asthma treatment methods and our understanding of signaling and pharmacology of G protein-coupled receptors (GPCRs) in asthma therapy, and discusses controversies regarding the use of GPCR drugs and new opportunities in developing GPCR-targeting therapeutics for the treatment of asthma.

Targeting interleukin 4 receptor α: A new approach to the treatment of cutaneous autoimmune bullous diseases?

Bullous pemphigoid, mucous membrane pemphigoid, and pemphigus vulgaris are different cutaneous autoimmune blistering diseases, with complex pathogenic mechanisms. In all of them, a type-2 response is thought to have a central role. Interleukin 4 and Interleukin 13 are crucial cytokines in type-2 response. Treatment of these conditions is often challenging. Dupilumab, a recombinant fully human IgG4 monoclonal antibody with binding specificity to human interleukin-4 receptor IL-4Rα, has the potential to inhibit both IL-4 and IL-13. We propose IL-4Rα as a theoretical drug target for cutaneous autoimmune bullous diseases.

Multiple doses of adipose tissue-derived mesenchymal stromal cells induce immunosuppression in experimental asthma

In experimental house dust mite (HDM)‐induced allergic asthma, therapeutic administration of a single dose of adipose tissue‐derived mesenchymal stromal cells (MSCs) ameliorates lung inflammation but is unable to reverse remodeling. We hypothesized that multiple doses of MSCs might exert better therapeutic effects by reducing lung inflammation and remodeling but might also result in immunosuppressive effects in experimental asthma. HDM was administered intranasally in C57BL/6 mice. After the last HDM challenge, mice received two or three doses of MSCs (10⁵ cells per day) or saline intravenously. An additional cohort of mice received dexamethasone as a positive control for immunosuppression. Two and three doses of MSCs reduced lung inflammation, levels of interleukin (IL)‐4, IL‐13, and eotaxin; total leukocyte, CD4⁺ T‐cell, and eosinophil counts in bronchoalveolar lavage fluid; and total leukocyte counts in bone marrow, spleen, and mediastinal lymph nodes. Two and three doses of MSCs also reduced collagen fiber content and transforming growth factor‐β levels in lung tissue; however, the three‐dose regimen was more effective, and reduced these parameters to control levels, while also decreasing α‐actin content in lung tissue. Two and three doses of MSCs improved lung mechanics. Dexamethasone, two and three doses of MSCs similarly increased galectin levels, but only the three‐dose regimen increased CD39 levels in the thymus. Dexamethasone and the three‐dose, but not the two‐dose regimen, also increased levels of programmed death receptor‐1 and IL‐10, while reducing CD4⁺CD8^low cell percentage in the thymus. In conclusion, multiple doses of MSCs reduced lung inflammation and remodeling while causing immunosuppression in HDM‐induced allergic asthma.

Role of IL-17 in asthma pathogenesis and its implications for the clinic

Introduction: Asthma is a respiratory disorder typically characterized by T-helper type 2 (Th2) inflammation that is mediated by cytokines, including IL-4, IL-5, and IL-13. Pathophysiologically, airway inflammation involving prominent eosinophilia, elevated IgE synthesis, airway hyperresponsiveness, mucus hypersecretion, and airway remodeling manifest clinically in patients as wheezing, breathlessness, chest tightness and episodic coughing. However, the Th2 paradigm falls short in interpreting the full spectrum of asthma severity. Areas covered: Severe asthmatics represent a distinct phenotype with their mixed pattern of neutrophilic-eosinophilic infiltration and glucocorticoid insensitivity making them refractory to currently available therapies. Th17 cells and their signature cytokine, IL-17, have been implicated in the development of severe asthma. Here, we review the contribution of IL-17 in the pathological features of asthma, gathered from both human and animal studies published in Pubmed during the past 10 years, and briefly discuss the clinical implications of targeting IL-17 imbalance in asthmatic patients. Expert opinion: With advancement in our understanding of the role of IL-17 in asthma pathology, it is clear that IL-17 is a targetable pathway which may lead to improvement in clinical symptoms of asthma. However, further elucidation of the complex interactions unfurled by IL-17 is essential in the empirical development of effective therapeutic options for refractory asthmatics.

The Cytokines of Asthma

Asthma is a chronic inflammatory airway disease associated with type 2 cytokines interleukin-4 (IL-4), IL-5, and IL-13, which promote airway eosinophilia, mucus overproduction, bronchial hyperresponsiveness (BHR), and immunogloubulin E (IgE) synthesis. However, only half of asthma patients exhibit signs of an exacerbated Type 2 response. "Type 2-low" asthma has different immune features: airway neutrophilia, obesity-related systemic inflammation, or in some cases, few signs of immune activation. Here, we review the cytokine networks driving asthma, placing these in cellular context and incorporating insights from cytokine-targeting therapies in the clinic. We discuss established and emerging paradigms in the context of the growing appreciation of disease heterogeneity and argue that the development of new and improved therapeutics will require understanding the diverse mechanisms underlying the spectrum of asthma pathologies.

Effects of the serine protease inhibitor rBmTI-A in an experimental mouse model of chronic allergic pulmonary inflammation

To evaluate whether a recombinant serine protease inhibitor (rBmTI-A) modulates inflammation in an experimental model of chronic allergic lung inflammation. Balb/c mice were divided into four groups: SAL (saline), OVA (sensitized with ovalbumin), SAL + rBmTI-A (control treated with rBmTI-A) and OVA + rBmTI-A (sensitized with ovalbumin and treated with rBmTI-A). The animals received an intraperitoneal injection of saline or ovalbumin, according to the group. The groups received inhalation with saline or ovalbumin and were treated with rBmTI-A or saline by nasal instillation. After 29 days, we evaluated the respiratory mechanics; bronchoalveolar lavage fluid (BALF); cytokines; MMP-9, TIMP-1; eosinophils; collagen and elastic fibre expression in the airways; and the trypsin-like, MMP-1, and MMP-9 lung tissue proteolytic activity. Treatment with rBmTI-A reduced the trypsin-like proteolytic activity, the elastance and resistance maximum response, the polymorphonuclear cells, IL-5, IL-10, IL-13 and IL-17A in the BALF, the expression of IL-5, IL-13, IL-17, CD4+, MMP-9, TIMP-1, eosinophils, collagen and elastic fibres in the airways of the OVA + rBmTI-A group compared to the OVA group (p < 0.05). rBmTI-A attenuated bronchial hyperresponsiveness, inflammation and remodelling in this experimental model of chronic allergic pulmonary inflammation. This inhibitor may serve as a potential therapeutic tool for asthma treatment.

Regulation of IL-17A and implications for TGF-β1 comodulation of airway smooth muscle remodeling in severe asthma

Severe asthma develops as a result of heightened, persistent symptoms that generally coincide with pronounced neutrophilic airway inflammation. In individuals with severe asthma, symptoms are poorly controlled by high-dose inhaled glucocorticoids and often lead to elevated morbidity and mortality rates that underscore the necessity for novel drug target identification that overcomes limitations in disease management. Many incidences of severe asthma are mechanistically associated with T helper 17 (TH17) cell-derived cytokines and immune factors that mediate neutrophilic influx to the airways. TH17-secreted interleukin-17A (IL-17A) is an independent risk factor for severe asthma that impacts airway smooth muscle (ASM) remodeling. TH17-derived cytokines and diverse immune mediators further interact with structural cells of the airway to induce pathophysiological processes that impact ASM functionality. Transforming growth factor-β1 (TGF-β1) is a pivotal mediator involved in airway remodeling that correlates with enhanced TH17 activity in individuals with severe asthma and is essential to TH17 differentiation and IL-17A production. IL-17A can also reciprocally enhance activation of TGF-β1 signaling pathways, whereas combined TH1/TH17 or TH2/TH17 immune responses may additively impact asthma severity. This review seeks to provide a comprehensive summary of cytokine-driven T cell fate determination and TH17-mediated airway inflammation. It will further review the evidence demonstrating the extent to which IL-17A interacts with various immune factors, specifically TGF-β1, to contribute to ASM remodeling and altered function in TH17-driven endotypes of severe asthma.

Differentiated fibrocytes assume a functional mesenchymal phenotype with regenerative potential

Fibrocytes (FCs) are hematopoietic lineage cells that migrate to sites of injury, transition to a mesenchymal phenotype, and help to mediate wound repair. Despite their relevance to human fibrotic disorders, there are few data characterizing basic FC biology. Herein, using proteomic, bioenergetic, and bioengineering techniques, we conducted deep phenotypic characterization of differentiating and mature FCs. Differentiation was associated with metabolic reprogramming that favored oxidative phosphorylation. Mature FCs had distinct proteomes compared to classic mesenchymal cells, formed functional stromae that supported epithelial maturation during in vitro organotypic culture, and exhibited in vivo survival and self-tolerance as connective tissue isografts. In an in vitro scratch assay, FCs promoted fibroblast migration and wound closure by paracrine signaling via the chemokine CXCL8 (interleukin-8). These findings characterize important aspects of FC differentiation and show that, in addition to their role in wound healing, FCs hold potential as an easily isolated autologous cell source for regenerative medicine.

Why are people with asthma susceptible to pneumonia? A review of factors related to upper airway bacteria

Asthma and pneumonia are common respiratory conditions globally, affecting individuals of all ages. Streptococcus pneumoniae is the predominant bacterial cause of pneumonia, with nasopharyngeal carriage an important step towards invasive and pulmonary disease. Vaccines provide individual protection, and also prevent nasopharyngeal carriage, providing herd immunity. Asthma is associated with an increased risk of pneumonia, but there is limited information on the underlying mechanism of this predisposition. Both asthma and its treatment may conceivably alter propensity to, and density of, carriage through an altered epithelial microenvironment driven by disease-related inflammation or treatment-related immunomodulation, for example with inhaled corticosteroids. The relative importance of these factors could impact the efficacy of vaccines in this vulnerable patient population. In this review, we summarize the evidence for an increased risk of pneumonia in asthma, and discuss factors affecting nasopharyngeal carriage in the context of current guidelines for pneumococcal vaccination.

[New protagonists in asthma pathophysiology]

Asthma is often associated with a Th2-type immune response with well-known cellular and molecular actors such as eosinophils, Th2 lymphocytes and associated cytokines such as interleukin-5 or IL-4. Nevertheless, some of the asthmatic patients show clinical manifestations and characteristics that do not correspond to the current pattern of the pathophysiology of asthma. Thus, recently new cellular and molecular actors in the development of asthma have been demonstrated in animal models and in humans. Among these are components of the innate immune system such as type 2 innate lymphoid cells or adaptive immune system such as Th9 lymphocytes. At the cellular level, the role of small G proteins in asthma is also highlighted as well as the role of major cytokines like IL-17 or those derived from the epithelium. A better knowledge of the physiopathology of asthma and the taking into account of these new actors allows the identification of new therapeutic targets for different endotypes of patients.

Intestinal nematode infection exacerbates experimental visceral leishmaniasis

Leishmania donovani exposure often results in subclinical infection in immunocompetent individuals, and the factors dictating development of visceral leishmaniasis (VL) are not known. Infection with intestinal worms skew immunity towards type 2 and regulatory responses, thereby theoretically increases susceptibility to intracellular infections controlled by type 1 responses. Here we have tested how chronic infection with the intestinal nematode Heligmosomoides polygyrus affected immunity to a secondary infection with L donovani. We found that mice infected with H polygyrus displayed higher Leishmania burden in liver and spleen compared to worm-free animals. This increased infectious load was accompanied by reduced leucocyte infiltration and nos2 transcription in livers and increased il4 and il10 transcription in spleens. Collectively, these data show that chronic infection with intestinal nematodes skew immune responses in a way that may favour development of VL.

Extracellular Matrix and Fibrocyte Accumulation in BALB/c Mouse Lung upon Transient Overexpression of Oncostatin M

The accumulation of extracellular matrix in lung diseases involves numerous factors, including cytokines and chemokines that participate in cell activation in lung tissues and the circulation of fibrocytes that contribute to local fibrotic responses. The transient overexpression of the gp130 cytokine Oncostatin M can induce extracellular matrix (ECM) accumulation in mouse lungs, and here, we assess a role for IL-13 in this activity using gene deficient mice. The endotracheal administration of an adenovirus vector encoding Oncostatin M (AdOSM) caused increases in parenchymal lung collagen accumulation, neutrophil numbers, and CXCL1/KC chemokine elevation in bronchioalveolar lavage fluids. These effects were similar in IL-13-/- mice at day 7; however, the ECM matrix induced by Oncostatin M (OSM) was reduced at day 14 in the IL-13-/- mice. CD45+col1+ fibrocyte numbers were elevated at day 7 due to AdOSM whereas macrophages were not. Day 14 levels of CD45+col1+ fibrocytes were maintained in the wildtype mice treated with AdOSM but were reduced in IL-13-/- mice. The expression of the fibrocyte chemotactic factor CXCL12/SDF-1 was suppressed marginally by AdOSM in vivo and significantly in vitro in mouse lung fibroblast cell cultures. Thus, Oncostatin M can stimulate inflammation in an IL-13-independent manner in BALB/c lungs; however, the ECM remodeling and fibrocyte accumulation is reduced in IL-13 deficiency.

Chronic Rhinosinusitis without Nasal Polyps in Asian Patients Shows Mixed Inflammatory Patterns and Neutrophil-Related Disease Severity

Chronic rhinosinusitis (CRS) shows heterogeneous immunologic features. Western studies revealed that CRS without nasal polyps (CRSsNP) showed a predominantly type 1 immune response and CRS with nasal polyps (CRSwNP) was characterized by type 2 immune response; however, the detailed immunologic profile of CRSsNP in Asian patients has not been thoroughly investigated. Therefore, we investigated the inflammatory endotypes of CRSsNP in Asian patients. Patients with CRSsNP (N = 57), patients with CRSwNP (N = 13), and a control group (N = 10), who underwent endoscopic sinus surgery, were enrolled; uncinate process (UP) tissues were harvested from all patients. Homogenates were prepared from the UP of each group, and immunologic profiles were analyzed, including major cytokines (32 inflammatory mediators). When comparing the UPs between groups, CRSsNP patients showed higher levels of Th2 cytokines (IL-4 and IL-13), eosinophilic chemokines (CCL-11 and CCL-24), ECP, and total IgE expression than control subjects. In addition, several neutrophilic markers (IL-1α, IL-6, IL-8, CXCL-1, CXCL-2, and MPO), IL-17A, IL-22, and TNF-α were dominant in CRSsNP patients. Among these inflammatory mediators, IL-17A showed higher expression levels in CRSsNP patients than in the control group and CRSwNP patients. However, IFN-γ expression was not significantly elevated in CRSsNP patients. The levels of neutrophil-associated cytokines were well correlated with each other; of which, CXCL2, IL-8, and MMP-9/TIMP-1 levels were significantly correlated with disease extent (r = 0.338, r = 0.317, and r = 0.424, respectively). However, the levels of eosinophil-associated cytokines showed little correlation with each other and were not correlated with disease extent. Our study revealed that Asian CRSsNP patients showed a mixed (types 2 and 17) immune response, but neutrophil-related markers were dominant and associated with disease extent. Knowledge of this immunologic feature may help clinicians make better individual treatment decisions for Asian CRSsNP patients.

Bidirectional roles of IL-22 in the pathogenesis of allergic airway inflammation

Asthma is the most prevalent allergic disease of the airway, which is characterized by eosinophilic inflammation, mucus hyperproduction, and airway hyper-responsiveness. Although these pathognomonic features are mainly mediated by antigen-specific Th2 cells and their cytokines, such as IL-4, IL-5, and IL-13, recent studies have revealed that other inflammatory cells, including Th17 cells and innate lymphoid cells (ILCs), also play a critical role in the pathogenesis of asthma. IL-22, one of the cytokines produced by Th17 cells and type 3 ILCs, has distinct functional properties, as IL-22 exclusively acts on non-hematopoietic cells including epithelial cells of mucosal surface and exhibits a broad range of action in regeneration and host protection. In accordance with the fact that lung epithelial cells play a critical role in the pathogenesis of asthma, we and other groups have shown that IL-22 is involved in the regulation of allergic airway inflammation. In this review, we discuss recent advances in the biology of IL-22 and its involvement in the pathogenesis of allergic airway inflammation.