Leukotriene B4 receptor 1 is differentially expressed on peripheral T cells of steroid-sensitive and -resistant asthmatics

Immuno-Enhancing Effects of Galium aparine L. in Cyclophosphamide-Induced Immunosuppressed Animal Models

This study investigates the immunomodulatory potential of Galium aparine L. (GAE) in immunodeficient animals. In this study, animals were categorized into five groups: the normal group, CYP group (cyclophosphamide intraperitoneal injection), GA5 group (cyclophosphamide + 5 μg GAE), GA50 group (cyclophosphamide + 50 μg GAE), and GA500 group (cyclophosphamide + 500 μg GAE). The CYP group exhibited significantly reduced spleen weights compared to the normal group, while the groups obtaining GAE displayed a dose-dependent increase in spleen weight. Furthermore, the GAE demonstrated dose-dependent enhancement of splenocyte proliferating activity, with significant increases observed in both LPS and ConA-induced assays. NK cell activity significantly increased in the GA50 and GA500 groups compared to the CYP group. Cytokine analysis revealed a significant increase in IL-6, TNF-α, and IFN-γ levels in ConA-induced splenocytes treated with GAE. Gene expression analysis identified 2434 DEG genes in the extract groups. Notable genes, such as Entpd1, Pgf, Thdb, Syt7, Sqor, and Rsc1al, displayed substantial differences in individual gene expression levels, suggesting their potential as target genes for immune enhancement. In conclusion, Galium aparine L. extract exhibits immunomodulatory properties. The observed gene expression changes further support the potential of Galium aparine L. extract as a natural agent for immune augmentation.

Regulation of T-Cell Immune Responses by Pro-Resolving Lipid Mediators

Both the initiation and the resolution of inflammatory responses are governed by the sequential activation, migration, and control/suppression of immune cells at the site of injury. Bioactive lipids play a major role in the fine-tuning of this dynamic process in a timely manner. During inflammation and its resolution, polymorphonuclear cells (PMNs) and macrophages switch from producing pro-inflammatory prostaglandins and leukotrienes to specialized pro-resolving lipid mediators (SPMs), namely, lipoxins, resolvins, protectins, and maresins, which are operative at the local level to limit further inflammation and tissue injury and restore homeostasis. Accumulating evidences expand now the role and actions of these lipid mediators from innate to adaptive immunity. In particular, SPMs have been shown to contribute to the control of chronic inflammation, and alterations in their production and/or function have been associated with the persistence of several pathological conditions, including autoimmunity, in human and experimental models. In this review, we focus on the impact of pro-resolving lipids on T cells through their ability to modulate T-cell responses. In particular, the effects of the different families of SPMs to restrain effector T-cell functions while promoting regulatory T cells will be reviewed, along with the underlying mechanisms. Furthermore, the emerging concept of SPMs as new biological markers for disease diagnostic and progression and as putative therapeutic tools to regulate the development and magnitude of inflammatory and autoimmune diseases is discussed.

Clinical impact and immunological alterations in asthmatic patients allergic to grass pollen subjected to high urban pollution in Madrid

BACKGROUND

The prevalence of asthma has increased in recent decades. Among the reasons for this increase is environmental pollution. Pollutants cause bronchial inflammation and introduce modifications in the pollen, making it more allergenic.

OBJECTIVE

Assess symptoms and medication requirements of asthmatic patients with grass allergies in Madrid (high urban pollution) and Ciudad Real (low pollution), and simultaneously evaluate the in vitro effects that pollen collected in both areas has on the immune cells of patients.

METHODS

During two pollen seasons, patients from both cities were included. The patients recorded their symptoms and the asthma medication they took daily. In both cities, pollen data, pollutants and meteorological variables were evaluated. The response to different cell populations from patients in both areas were analysed after "in vitro" stimulation with pollen from both cities.

RESULTS

The symptoms and medication use of the patients in Madrid was 29.94% higher. The NO₂ concentration in Madrid was triple that of Ciudad Real (33.4 vs. 9.1 µg/m³ of air). All other pollutants had very similar concentrations during the study period. Pollen from the high pollution area caused a significant enhancement of T-CD8+ and NK cells proliferation compared with pollen of low pollution area, independently of the patient's origin.

CONCLUSION

Asthmatic patients from Madrid have a worse clinical evolution than those from Ciudad Real because of higher levels of urban pollution, and this could be driven by the higher capacity of pollen of Madrid to activate T-CD8+ and NK cells.

Repetitive aeroallergen challenges elucidate maladaptive epithelial and inflammatory traits that underpin allergic airway diseases

BACKGROUND

Signifying the 2-compartments/1-disease paradigm, allergic rhinoconjunctivitis (ARC) and asthma (AA) are prevalent, comorbid conditions triggered by environmental factors (eg, house dust mites [HDMs]). However, despite the ubiquity of triggers, progression to severe ARC/AA is infrequent, suggesting either resilience or adaptation.

OBJECTIVE

We sought to determine whether ARC/AA severity relates to maladaptive responses to disease triggers.

METHODS

Adults with HDM-associated ARC were challenged repetitively with HDMs in an aeroallergen challenge chamber. Mechanistic traits associated with disease severity were identified.

RESULTS

HDM challenges evoked maladaptive (persistently higher ARC symptoms), adaptive (progressive symptom reduction), and resilient (resistance to symptom induction) phenotypes. Symptom severity in the natural environment was an imprecise correlate of the phenotypes. Nasal airway traits, defined by low inflammation-effectual epithelial integrity, moderate inflammation-effectual epithelial integrity, and higher inflammation-ineffectual epithelial integrity, were hallmarks of the resilient, adaptive, and maladaptive evoked phenotypes, respectively. Highlighting a crosstalk mechanism, peripheral blood inflammatory tone calibrated these traits: ineffectual epithelial integrity associated with CD8⁺ T cells, whereas airway inflammation associated with both CD8⁺ T cells and eosinophils. Hallmark peripheral blood maladaptive traits were increased natural killer and CD8⁺ T cells, lower CD4⁺ mucosal-associated invariant T cells, and deficiencies along the TLR-IRF-IFN antiviral pathway. Maladaptive traits tracking HDM-associated ARC also contributed to AA risk and severity models.

CONCLUSIONS

Repetitive challenges with HDMs revealed that maladaptation to disease triggers may underpin ARC/AA disease severity. A combinatorial therapeutic approach may involve reversal of loss-of-beneficial-function traits (ineffectual epithelial integrity, TLR-IRF-IFN deficiencies), mitigation of gain-of-adverse-function traits (inflammation), and blocking of a detrimental crosstalk between the peripheral blood and airway compartments.

CD8+ Tc2 cells: underappreciated contributors to severe asthma

The complexity of asthma is underscored by the number of cell types and mediators implicated in the pathogenesis of this heterogeneous syndrome. Type 2 CD4⁺ T-cells (Th2) and more recently, type 2 innate lymphoid cells dominate current descriptions of asthma pathogenesis. However, another important source of these type 2 cytokines, especially interleukin (IL)-5 and IL-13, are CD8⁺ T-cells, which are increasingly proposed to play an important role in asthma pathogenesis, because they are abundant and are comparatively insensitive to corticosteroids. Many common triggers of asthma exacerbations are mediated via corticosteroid-resistant pathways involving neutrophils and CD8⁺ T-cells. Extensive murine data reveal the plasticity of CD8⁺ T-cells and their capacity to enhance airway inflammation and airway dysfunction. In humans, Tc2 cells are predominant in fatal asthma, while in stable state, severe eosinophilic asthma is associated with greater numbers of Tc2 than Th2 cells in blood, bronchoalveolar lavage fluid and bronchial biopsies. Tc2 cells strongly express CRTH2, the receptor for prostaglandin D2, the cysteinyl leukotriene receptor 1 and the leukotriene B4 receptor. When activated, these elicit Tc2 cell chemotaxis and production of chemokines and type 2 and other cytokines, resulting directly or indirectly in eosinophil recruitment and survival. These factors position CD8⁺ Tc2 cells as important and underappreciated effector cells contributing to asthma pathogenesis. Here, we review recent advances and new insights in understanding the pro-asthmatic functions of CD8⁺ T-cells in eosinophilic asthma, especially corticosteroid-resistant asthma, and the molecular mechanisms underlying their pathologic effector function.

Alongside Th2 and ILC2 cells, CD8⁺ T-cells are a cellular source of type 2 cytokines. We review recent findings and insights into the pathologic effector functions of type 2 CD8⁺ T-cells in eosinophilic asthma, especially steroid-resistant disease.http://bit.ly/2KbVGL2

Eicosanoid and Specialized Proresolving Mediator Regulation of Lymphoid Cells

Eicosanoids and specialized proresolving mediators (SPMs) regulate leukocyte function and inflammation. They are ideally positioned at the interface of the innate and adaptive immune responses when lymphocytes interact with leukocytes. Receptors for leukotriene B₄ (LTB₄), prostaglandin E₂ (PGE₂), and SPMs are expressed on lymphocytes. Evidence points toward an essential role of these lipid mediators (LMs) in direct regulation of lymphocyte functions. SPMs, which include lipoxins, demonstrate comprehensive protective actions with lymphocytes. LTB₄ and PGE₂ regulation of lymphocytes is diverse and depends on the interaction of lymphocytes with other cells. Importantly, both LTB₄ and PGE₂ are essential regulators of T cell antitumor activity. These LMs are attractive therapeutic targets to control dysregulated innate and adaptive immune responses, promote lymphocyte antitumor activity, and prevent tumor immune evasion.

Molecular Endotypes Contribute to the Heterogeneity of Asthma

Diagnosis and management of asthma is commonly implemented based on clinical assessment. Although these nonmolecular biomarkers have been useful, limited resolution of the heterogeneity among asthmatic patients and little information regarding the underlying pathobiology of disease in individuals have been provided. Molecular endotying using global transcriptome expression profiling associated with clinical features of asthma has improved our understanding of disease mechanisms, risk assessment of asthma exacerbations, and treatment responses, especially in patients with type 2 inflammation. Further advances in establishing pathobiological subgroups, bioactive pathways, and true disease endotypes hold potential for a more personalized medical approach in asthmatic patients.

Importance of the leukotriene B4-BLT1 and LTB4-BLT2 pathways in asthma

For several decades, the leukotriene pathways have been implicated as playing a central role in the pathophysiology of asthma. The presence and elevation of numerous metabolites in the blood, sputum, and bronchoalveolar lavage fluid from asthmatics or experimental animals adds support to this notion. However, targeting of the leukotriene pathways has had, in general, limited success. The single exception in asthma therapy has been targeting of the cysteinyl leukotriene receptor 1, which clinically has proven effective but only in certain clinical situations. Interference with 5-lipoxygenase has had limited success, in part due to adverse drug effects. The importance of the LTB4-BLT1 pathway in asthma pathogenesis has extensive experimental support and findings, albeit limited, from clinical samples. The LTB4-BLT1 pathway was shown to be important as a neutrophil chemoattractant. Despite observations made more than two decades ago, the LTB4-BLT1 pathway has only recently been shown to exhibit important activities on subsets of T lymphocytes, both as a chemoattractant and on lymphocyte activation, as well as on dendritic cells, the major antigen presenting cell in the lung. The role of BLT2 in asthma remains unclear. Targeting of components of the LTB4-BLT1 pathway offers innovative therapeutic opportunities especially in patients with asthma that remain uncontrolled despite intensive corticosteroid treatment.

Spectrum of T-lymphocyte activities regulating allergic lung inflammation

Despite advances in the treatment of asthma, optimization of symptom control remains an unmet need in many patients. These patients, labeled severe asthma, are responsible for a substantial fraction of the disease burden. In these patients, research is needed to define the cellular and molecular pathways contributing to disease which in large part are refractory to corticosteroid treatment. The causes of steroid-resistant asthma are multifactorial and result from complex interactions of genetics, environmental factors, and innate and adaptive immunity. Adaptive immunity, addressed here, integrates the activities of distinct T-cell subsets and by definition is dynamic and responsive to an ever-changing environment and the influences of epigenetic modifications. These T-cell subsets exhibit different susceptibilities to the actions of corticosteroids and, in some, corticosteroids enhance their functional activation. Moreover, these subsets are not fixed in lineage differentiation but can undergo transcriptional reprogramming in a bidirectional manner between protective and pathogenic effector states. Together, these factors contribute to asthma heterogeneity between patients but also in the same patient at different stages of their disease. Only by carefully defining mechanistic pathways, delineating their sensitivity to corticosteroids, and determining the balance between regulatory and effector pathways will precision medicine become a reality with selective and effective application of targeted therapies.

Addressing corticosteroid insensitivity in adults with asthma

Corticosteroids are the most effective treatment for asthma, but the therapeutic response varies markedly between individuals, with up to one third of patients showing evidence of insensitivity to corticosteroids. This article summarizes information on genetic, environmental and asthma-related factors as well as demographic and pharmacokinetic variables associated with corticosteroid insensitivity in asthma. Molecular mechanisms proposed to explain corticosteroid insensitivity are reviewed including alterations in glucocorticoid receptor subtype, binding and nuclear translocation, increased proinflammatory transcription factors and defective histone acetylation. Current therapies and future interventions that may restore corticosteroid sensitivity in asthma are discussed, including small molecule drugs and biological agents. In the future, biomarkers may be used in the clinic to predict corticosteroid sensitivity in patients with poorly controlled asthma.

1,25D3 prevents CD8(+)Tc2 skewing and asthma development through VDR binding changes to the Cyp11a1 promoter

Effector CD8⁺ T cells convert from IFN-γ⁺ (Tc1) to IL-13⁺ (Tc2) cells in the presence of IL-4. Underlying regulatory mechanisms are not fully defined. Here, we show that addition of 1,25D3, the active form of vitamin D3, during CD8⁺ T-cell differentiation prevents IL-4-induced conversion to IL-13-producers. Transfer of 1,25D3-treated CD8⁺ T cells into sensitized and challenged CD8⁺-deficient recipients fails to restore development of lung allergic responses. 1,25D3 alters vitamin D receptor (VDR) recruitment to the Cyp11a1 promoter in vitro and in vivo in the presence of IL-4. As a result, protein levels and enzymatic activity of CYP11A1, a steroidogenic enzyme regulating CD8⁺ T-cell conversion, are decreased. An epistatic effect between CYP11A1 and VDR polymorphisms may contribute to the predisposition to childhood asthma. These data identify a role for 1,25D3 in the molecular programming of CD8⁺ T-cell conversion to an IL-13-secreting phenotype through regulation of steroidogenesis, potentially governing asthma susceptibility.

Type 2 CD8⁺ T cells (Tc2) play a role in the development of experimental asthma. Here the authors show that 1,25D3, the active form of vitamin D3, can prevent conversion of CD8⁺T cells to a Tc2 phenotype, reducing asthma susceptibility.

AT-RvD1 modulates CCL-2 and CXCL-8 production and NF-κB, STAT-6, SOCS1, and SOCS3 expression on bronchial epithelial cells stimulated with IL-4

Bronchial epithelial cells represent the first line of defense against microorganisms and allergens in the airways and play an important role in chronic inflammatory processes such as asthma. In an experimental model, both RvD1 and AT-RvD1, lipid mediators of inflammation resolution, ameliorated some of the most important phenotypes of experimental asthma. Here, we extend these results and demonstrate the effect of AT-RvD1 on bronchial epithelial cells (BEAS-2B) stimulated with IL-4. AT-RvD1 (100 nM) decreased both CCL2 and CXCL-8 production, in part by decreasing STAT6 and NF-κB pathways. Furthermore, the effects of AT-RvD1 were ALX/FRP2 receptor dependent, as the antagonist of this receptor (BOC1) reversed the inhibition of these chemokines by AT-RvD1. In addition, AT-RvD1 decreased SOCS1 and increased SOCS3 expression, which play important roles in Th1 and Th17 modulation, respectively. In conclusion, AT-RvD1 demonstrated significant effects on the IL-4-induced activation of bronchial epithelial cells and consequently the potential to modulate neutrophilic and eosinophilic airway inflammation in asthma. Taken together, these findings identify AT-RvD1 as a potential proresolving therapeutic agent for allergic responses in the airways.