T cell trafficking in allergic asthma: the ins and outs

Prebiotics improve parameters indicative of allergy-induced asthma in murines: a systematic review with meta-analysis

The prevalence of allergic asthma is increasing worldwide and it is important that new treatments are implemented. This study aimed to thoroughly investigate the effect of prebiotics on parameters indicative of allergic asthma induced by ovalbumin (OVA), house dust mites (HDM) and OVA + lipopolysaccharide (LPS). The review was registered in the Open Science Framework (registration ID: osf.io/du4ab). PRISMA and web-app Rayyan were used as tools for the selection of studies collected in seven databases: PubMed; ScienceDirect; Web of Science; Scielo; Scopus; EMBASE; and Google Scholar with the use of predetermined keywords and Medical Subject Heading terms of the National Library of Medicine. Eight studies involving 182 mice and rats were included in the meta-analysis. The results showed a significant reduction in the total number of inflammatory cells and in the isolated number of inflammatory cells, eosinophils, lymphocytes, macrophages and neutrophils (P < 0.05). The results also revealed a significant decrease in the concentration of interleukins 13 and 33 in lung tissue. The present study demonstrated that prebiotic supplementation in the diet of rats and mice, as preclinical models, mitigates indicative parameters, inflammatory cells and interleukins, of allergic asthma induced by OVA, HDM or OVA + LPS. These beneficial results encourage randomized clinical trials to be carried out aiming at the prevention/treatment of allergic asthma. © 2025 Society of Chemical Industry.

Innate Immunity and Asthma Exacerbations: Insights From Human Models

Asthma is a common chronic respiratory disease characterized by the presence of airway inflammation, airway hyperresponsiveness, and mucus hypersecretion. Repeated asthma exacerbations can lead to progressive airway remodeling and irreversible airflow obstruction. Thus, understanding and preventing asthma exacerbations are of paramount importance. Although multiple endotypes exist, asthma is most often driven by type 2 airway inflammation. New therapies that target specific type 2 mediators have been shown to reduce the frequency of asthma exacerbations but are incompletely effective in a significant number of asthmatics. Furthermore, it remains unknown whether current treatments lead to sustained changes in the airway or if targeting additional pathways may be necessary to achieve asthma remission. Activation of innate immunity is the initial event in the inflammatory sequence that occurs during an asthma exacerbation. However, there continue to be critical gaps in our understanding of the innate immune response to asthma exacerbating factors. In this review, we summarize the current understanding of the role of innate immunity in asthma exacerbations and the methods used to study them. We also identify potential novel therapeutic targets for asthma and future areas for investigation.

Formaldehyde exacerbates inflammation and biases T helper cell lineage commitment through IFN-γ/STAT1/T-bet pathway in asthma

The correlation between formaldehyde (FA) exposure and prevalence of asthma has been widely reported. However, the underlying mechanism is still not fully understood. FA exposure at 2.0 mg/m3 was found to exacerbate asthma in OVA-induced murine models. IFN-γ, the cytokine produced by T helper 1 (Th1) cells, was significantly induced by FA in serum and bronchoalveolar lavage fluid (BALF) of asthmatic mice, which was different from cytokines secreted by other Th cells. The observation was also confirmed by mRNA levels of Th marker genes in CD4+ T cells isolated from BALF. In addition, increased production of IFN-γ and expression of T-bet in Jurkat T cells primed with phorbol ester and phytohaemagglutinin were also observed with 100 μM FA treatment in vitro. Upregulated STAT1 phosphorylation, T-bet expression and IFN-γ production induced by FA was found to be restrained by STAT1 inhibitor fludarabine, indicating that FA promoted Th1 commitment through the autocrine IFN-γ/STAT1/T-bet pathway in asthma. This work not only revealed that FA could bias Th lineage commitment to exacerbate allergic asthma, but also identified the signaling mechanism of FA-induced Th1 differentiation, which may be utilized as the target for development of interfering strategies against FA-induced immune disorders.

Alkali injury-induced pathological lymphangiogenesis in the iris facilitates the infiltration of T cells and ocular inflammation

Inflammatory lymphangiogenesis is intimately linked to immune regulation and tissue homeostasis. However, current evidence has suggested that classic lymphatic vessels are physiologically absent in intraocular structures. Here, we show that neolymphatic vessels were induced in the iris after corneal alkali injury (CAI) in a VEGFR3-dependent manner. Cre-loxP-based lineage tracing revealed that these lymphatic endothelial cells (LECs) originate from existing Prox1+ lymphatic vessels. Notably, the ablation of iridial lymphangiogenesis via conditional deletion of VEGFR3 alleviated the ocular inflammatory response and pathological T cell infiltration. Our findings demonstrate that iridial neolymphatics actively participate in pathological immune responses following injury and suggest intraocular lymphangiogenesis as a valuable therapeutic target for the treatment of ocular inflammation.

Multiresolution 3D Optical Mapping of Immune Cell Infiltrates in Mouse Asthmatic Lung

Asthma is a chronic inflammatory airway disease driven by various infiltrating immune cell types into the lung. Optical microscopy has been used to study immune infiltrates in asthmatic lungs. Confocal laser scanning microscopy (CLSM) identifies the phenotypes and locations of individual immune cells in lung tissue sections by employing high-magnification objectives and multiplex immunofluorescence staining. In contrast, light-sheet fluorescence microscopy (LSFM) can visualize the macroscopic and mesoscopic architecture of whole-mount lung tissues in three dimensions (3D) by adopting an optical tissue-clearing method. Despite each microscopy method producing image data with unique resolution from a tissue sample, CLSM and LSFM have not been applied together because of different tissue-preparation procedures. Here, we introduce a new approach combining LSFM and CLSM into a sequential imaging pipeline. We built a new optical tissue clearing workflow in which the immersion clearing agent can be switched from an organic solvent to an aqueous sugar solution for sequential 3D LSFM and CLSM of mouse lungs. This sequential combination microscopy offered quantitative 3D spatial analyses of the distribution of immune infiltrates in the same mouse asthmatic lung tissue at the organ, tissue, and cell levels. These results show that our method facilitates multiresolution 3D fluorescence microscopy as a new imaging approach providing comprehensive spatial information for a better understanding of inflammatory lung diseases.

Crosstalk between CD4+ T Cells and Airway Smooth Muscle in Pediatric Obesity-related Asthma

Rationale: Pediatric obesity-related asthma is a nonatopic asthma phenotype with high disease burden and few effective therapies. RhoGTPase upregulation in peripheral blood T helper (Th) cells is associated with the phenotype, but the mechanisms that underlie this association are not known. Objectives: To investigate the mechanisms by which upregulation of CDC42 (Cell Division Cycle 42), a RhoGTPase, in Th cells is associated with airway smooth muscle (ASM) biology. Methods: Chemotaxis of obese asthma and healthy-weight asthma Th cells, and their adhesion to obese and healthy-weight nonasthmatic ASM, was investigated. Transcriptomics and proteomics were used to determine the differential effect of obese and healthy-weight asthma Th cell adhesion to obese or healthy-weight ASM biology. Measurements and Main Results: Chemotaxis of obese asthma Th cells with CDC42 upregulation was resistant to CDC42 inhibition. Obese asthma Th cells were more adherent to obese ASM compared with healthy-weight asthma Th cells to healthy-weight ASM. Compared with coculture with healthy-weight ASM, obese asthma Th cell coculture with obese ASM was positively enriched for genes and proteins involved in actin cytoskeleton organization, transmembrane receptor protein kinase signaling, and cell mitosis, and negatively enriched for extracellular matrix organization. Targeted gene evaluation revealed upregulation of IFNG, TNF (tumor necrosis factor), and Cluster of Differentiation 247 (CD247) among Th cell genes, and of Ak strain transforming (AKT), Ras homolog family member A (RHOA), and CD38, with downregulation of PRKCA (Protein kinase C-alpha), among smooth muscle genes. Conclusions: Obese asthma Th cells have uninhibited chemotaxis and are more adherent to obese ASM, which is associated with upregulation of genes and proteins associated with smooth muscle proliferation and reciprocal nonatopic Th cell activation.

Aloperine: A Potent Modulator of Crucial Biological Mechanisms in Multiple Diseases

Aloperine is an alkaloid found in the seeds and leaves of the medicinal plant Sophora alopecuroides L. It has been used as herbal medicine in China for centuries due to its potent anti-inflammatory, antioxidant, antibacterial, and antiviral properties. Recently, aloperine has been widely investigated for its therapeutic activities. Aloperine is proven to be an effective therapeutic agent against many human pathological conditions, including cancer, viral diseases, and cardiovascular and inflammatory disorders. Aloperine is reported to exert therapeutic effects through triggering various biological processes, including cell cycle arrest, apoptosis, autophagy, suppressing cell migration, and invasion. It has also been found to be associated with the modulation of various signaling pathways in different diseases. In this review, we summarize the most recent knowledge on the modulatory effects of aloperine on various critical biological processes and signaling mechanisms, including the PI3K, Akt, NF-κB, Ras, and Nrf2 pathways. These data demonstrate that aloperine is a promising therapeutic candidate. Being a potent modulator of signaling mechanisms, aloperine can be employed in clinical settings to treat various human disorders in the future.

MicroRNA-mediated calcineurin signaling activation induces CCL2, CCL3, CCL5, IL8, and chemotactic activities in 4,4'-methylene diphenyl diisocyanate exposed macrophages

Occupational exposure to 4,4'-methylene diphenyl diisocyanate (MDI), the most widely used monomeric diisocyanate, is one of the leading causes of occupational asthma (OA). Previously, we identified microRNA (miR)-206-3p/miR-381-3p-mediated PPP3CA/calcineurin signalling regulated iNOS transcription in macrophages and bronchoalveolar lavage cells (BALCs) after acute MDI exposure; however, whether PPP3CA/calcineurin signalling participates in regulation of other asthma-associated mediators secreted by macrophages/BALCs after MDI exposure is unknown.Several asthma-associated, macrophage-secreted mediator mRNAs from MDI exposed murine BALCs and MDI-glutathione (GSH) conjugate treated differentiated THP-1 macrophages were analysed using RT-qPCR.Endogenous IL1B, TNF, CCL2, CCL3, CCL5, and TGFB1 were upregulated in MDI or MDI-GSH conjugate exposed BALCs and macrophages, respectively. Calcineurin inhibitor tacrolimus (FK506) attenuated the MDI-GSH conjugate-mediated induction of CCL2, CCL3, CCL5, and CXCL8/IL8 but not others. Transfection of either miR-inhibitor-206-3p or miR-inhibitor-381-3p in macrophages induced chemokine CCL2, CCL3, CCL5, and CXCL8 transcription, whereas FK506 attenuated the miR-inhibitor-206-3p or miR-inhibitor-381-3p-mediated effects. Finally, MDI-GSH conjugate treated macrophages showed increased chemotactic ability to various immune cells, which may be attenuated by FK506.In conclusion, these results indicate that MDI exposure to macrophages/BALCs may recruit immune cells into the airway via induction of chemokines by miR-206-3p and miR-381-3p-mediated calcineurin signalling activation.

Dihydroartemisinin: A Potential Drug for the Treatment of Malignancies and Inflammatory Diseases

Dihydroartemisinin (DHA) has been globally recognized for its efficacy and safety in the clinical treatment of malaria for decades. Recently, it has been found that DHA inhibits malignant tumor growth and regulates immune system function in addition to anti-malaria. In parasites and tumors, DHA causes severe oxidative stress by inducing excessive reactive oxygen species production. DHA also kills tumor cells by inducing programmed cell death, blocking cell cycle and enhancing anti-tumor immunity. In addition, DHA inhibits inflammation by reducing the inflammatory cells infiltration and suppressing the production of pro-inflammatory cytokines. Further, genomics, proteomics, metabolomics and network pharmacology of DHA therapy provide the basis for elucidating the pharmacological effects of DHA. This review provides a summary of the recent research progress of DHA in anti-tumor, inhibition of inflammatory diseases and the relevant pharmacological mechanisms. With further research of DHA, it is likely that DHA will become an alternative therapy in the clinical treatment of malignant tumors and inflammatory diseases.

Inflammation in Asthma Pathogenesis: Role of T cells, Macrophages, Epithelial Cells and Type 2 Inflammation

Asthma is a chronic disease with abnormal inflammatory and immunological responses. The disease initiated by antigens in subjects with genetic susceptibility. However, environmental factors play a role in the initiation and exacerbation of asthma attack. Asthma is T helper 2 (Th2)-cell-mediated disease. Recent studies indicated that asthma is not a single disease entity, but it is with multiple phenotypes and endotypes. The pathophysiological changes in asthma included a series of subsequent continuous vicious circle of cellular activation contributed to induction of chemokines and cytokines that potentiate inflammation. The heterogeneity of asthma influenced the treatment response. The asthma pathogenesis driven by varied set of cells such as eosinophils, basophils, neutrophils, mast cells, macrophages, epithelial cells and T cells. In this review the role of T cells, macrophage, and epithelial cells are discussed.

Schisandrin B Attenuates Airway Inflammation by Regulating the NF-κB/Nrf2 Signaling Pathway in Mouse Models of Asthma

Background

Asthma is a complex inflammatory disorder that plagues a large number of people. Schisandrin B is an active ingredient of the traditional Chinese herbal medicine Schisandra with various proven physiological activities such as anti-inflammatory and antioxidant activities. In this study, we explored the anti-inflammatory and antioxidant effects and provided the mechanistic insights into the activity of schisandrin B in a mouse model of ovalbumin- (OVA-) induced allergic asthma.

Methods

Male BALB/c mice were sensitized and challenged with OVA to induce asthma and treated with various doses (15 mg/kg, 30 mg/kg, and 60 mg/kg) of SCH to alleviate the features of allergic asthma, airway hyperresponsiveness, inflammatory response, OVA-specific immunoglobulin (Ig)E level, and pathological injury.

Results

Schisandrin B significantly attenuated the airway hyperresponsiveness induced by OVA. Moreover, schisandrin B administration suppressed inflammatory responses, reduced the level of IgE, and attenuated pathological injury. Mechanistically, schisandrin B treatment promoted the activation of nuclear erythroid 2-related factor 2 (Nrf2), but suppressed the stimulation of the NF-κB pathway caused by OVA.

Conclusion

Taken together, our study suggests that schisandrin B attenuates the features of asthmatic lungs by inhibiting the NF-κB pathway and activating the Nrf2 signaling pathway.

A review of epigenetic changes in asthma: methylation and acetylation

Several studies show that childhood and adulthood asthma and its symptoms can be modulated through epigenetic modifications. Epigenetic changes are inheritable modifications that can modify the gene expression without changing the DNA sequence. The most common epigenetic alternations consist of DNA methylation and histone modifications. How these changes lead to asthmatic phenotype or promote the asthma features, in particular by immune pathways regulation, is an understudied topic. Since external effects, like exposure to tobacco smoke, air pollution, and drugs, influence both asthma development and the epigenome, elucidating the role of epigenetic changes in asthma is of great importance. This review presents available evidence on the epigenetic process that drives asthma genes and pathways, with a particular focus on DNA methylation, histone methylation, and acetylation. We gathered and assessed studies conducted in this field over the past two decades. Our study examined asthma in different aspects and also shed light on the limitations and the important factors involved in the outcomes of the studies. To date, most of the studies in this area have been carried out on DNA methylation. Therefore, the need for diagnostic and therapeutic applications through this molecular process calls for more research on the histone modifications in this disease.

Osthole Attenuates Macrophage Activation in Experimental Asthma by Inhibitingthe NF-ĸB/MIF Signaling Pathway

Inhibition of activated macrophages is an alternative therapeutic strategy for asthma. We investigated whether a coumarin compound, osthole, isolated from Cnidium monnieri (L.) Cuss, alleviated macrophage activation in vivo and in vitro. Osthole could reduce expression of a marker of activated macrophages, cluster of differentiation (CD)206, in an ovalbumin-challenge model of asthma in mice. Osthole could also inhibit infiltration of inflammatory cells, collagen deposition and production of proinflammatory cytokines [interleukin (IL)-1β, tumor necrosis factor-ɑ, macrophage migration inhibitory factor (MIF)] in asthmatic mice. In vitro, expression of phosphorylated-IĸBɑ, MIF and M2 cytokines (Ym-1, Fizz-1, arginase-1) in IL-4-induced macrophages decreased upon exposure to the NF-ĸB inhibitor MG-132. In our short hairpin (sh)RNA-MIF-knockdown model, reduced expression of M2 cytokines was detected in the IL-4 + shRNA-MIF group. Osthole could attenuate the proliferation and migration of an IL-4-induced rat alveolar macrophages line (NR8383). Osthole could reduce IL-4-induced translocation of nuclear factor-kappa B (NF-ĸB) in NR8383 cells. Collectively, our results suggest that osthole ameliorates macrophage activation in asthma by suppressing the NF-ĸB/MIF signaling pathway, and might be a potential agent for treating asthma.

miR-135a inhibits airway inflammatory response in asthmatic mice via regulating JAK/STAT signaling pathway

The objective of this study was to investigate the inhibitory effect of miR-135a in regulating JAK/STAT signaling pathway on airway inflammation in asthmatic mice. An asthma model was established by sensitization and stimulation with ovalbumin (OVA), and the corresponding drug intervention was given from the day of stimulation by means of nasal drops. Airway hyperresponsiveness was tested. The content of miR-135a in the lung tissue of mice was detected by RT-PCR. The pathological changes of lung tissue were evaluated by HE staining. Tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-5, and eotaxin in bronchoalveolar lavage fluid (BALF) and lung tissue were detected by ELISA and immunohistochemistry, respectively. The expression of JAK/STAT signaling pathway-related protein in lung tissue was detected by western blot. To further validate the effect of miR-135a overexpression on the JAK/STAT signaling pathway, pathway activators and inhibitors were added. Compared with the OVA group, the airway hyperresponsiveness of the mice was significantly decreased after treatment with the miR-135a agonist. The expression of miR-135a was significantly increased in the lung tissue and the pathological changes of the lung tissue were alleviated. The contents of TNF-α, IL-6, IL-5, and eotaxin in BALF and lung tissues were decreased. The expression of JAK/STAT signaling pathway-related proteins p-JAK3/JAK3, p-STAT1/STAT1, and p-STAT3/STAT3 were significantly reduced in lung tissue (P<0.05). Addition of JAK inhibitor AG490 reduced airway inflammation in asthmatic mice. miR-135a agonists inhibit airway inflammation in asthmatic mice by regulating the JAK/STAT signaling pathway.

Alpinetin prevents inflammatory responses in OVA-induced allergic asthma through modulating PI3K/AKT/NF-κB and HO-1 signaling pathways in mice

Allergic asthma is the most common type of asthma which characterized by inflammatory responses of the airways. Alpinetin, a flavonoid compound derived from the ginger family of medicinal herbs, possesses various biological properties including anti-inflammatory, anti-oxidant and other medical effects. In this study, we aimed to evaluate the effects of alpinetin on OVA-induced allergic asthma, and further to examine its molecular mechanisms underlying these processes in vivo and in vitro. Mice were sensitized and challenged with OVA to build allergic asthma model in vivo. Bronchoalveolar lavage fluid (BALF) was collected for inflammatory cells analysis and lung tissues were examined for histopathological examination. The levels of IL-5, IL-13, IL-4, IgE, TNF-α, IL-6 and IL-1β were determined by the respective ELISA kits. The PI3K/AKT/NF-κB and HO-1 signaling pathways were examined by western blot analysis. The results showed that alpinetin significantly ameliorated OVA-induced pathologic changes of lungs, such as decreasing massive inflammatory cell infiltration and mucus hypersecretion, and reduced the number of inflammatory cells in BALF. Alpinetin also decreased the OVA-induced levels of IL-4, IL-5, IL-13 and IgE. Furthermore, alpinetin inhibited OVA-induced phosphorylation of p65, IκB, PI3K and AKT, and the activity of HO-1 in vivo. More importantly, these anti-inflammatory effects and molecular mechanisms of alpinetin has also been confirmed in LPS-stimulated RAW 264.7 macrophages in vitro. In conclusion, above results indicate that alpinetin exhibites a potent anti-inflammatory activity in allergic asthma through modulating PI3K/AKT/NF-κB and HO-1 signaling pathways, which would be used as a promising therapy agent for allergic asthma.

The Role of T Cells and Macrophages in Asthma Pathogenesis: A New Perspective on Mutual Crosstalk

Asthma is associated with innate and adaptive immunity mediated by immune cells. T cell or macrophage dysfunction plays a particularly significant role in asthma pathogenesis. Furthermore, crosstalk between them continuously transmits proinflammatory or anti-inflammatory signals, causing the immune cell activation or repression in the immune response. Consequently, the imbalanced immune microenvironment is the major cause of the exacerbation of asthma. Here, we discuss the role of T cells, macrophages, and their interactions in asthma pathogenesis.

Roles of PI3K pan-inhibitors and PI3K-δ inhibitors in allergic lung inflammation: a systematic review and meta-analysis

Meta-analysis can be applied to study the effectiveness of the summary estimates for experimental papers, producing objective and unbiased results. We investigated the effects of phosphoinositide-3-kinase (PI3K) on the inflammatory profile in allergic mouse models, which are currently under development in signal transduction materials. PubMed, EMBASE and Web of Science databases were searched for relevant literature using the search terms “ PI3K inhibitor” and “allergy” or “asthma”. Cochrane Review Manager and R were used for handling continuous variables. The primary outcomes of the inflammatory profile were divided into cell counts and inflammatory cytokines. We used a random effects model to draw a forest plot. Through the database search and subsequent selection, 17 articles were identified. Regarding the cell counts, both the PI3K pan-inhibitors and PI3K-δ inhibitors effectively reduced the total cell counts, eosinophils, neutrophils and lymphocytes. In contrast to PI3K-δ inhibitors, PI3K pan-inhibitors effectively reduced macrophages. Regarding the inflammatory cytokines, PI3K pan-inhibitors and PI3K-δ inhibitors effectively reduced total IgE, IL-4, IL-5, IL-13, TNF-α, IL-1β, VEGF and had no effect on IL-6. Compared to the PI3K pan-inhibitors, which block all pathways, selective PI3K-δ inhibitors are expected to be relatively less toxic. Regarding the efficacy, PI3K-δ inhibitors have at least the same or better efficacy than PI3K pan-inhibitors in effector cells and inflammatory mediators.

TSLP drives acute TH2-cell differentiation in lungs

BACKGROUND

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine that is important for the development of type 2 inflammatory responses at mucosal surfaces.

OBJECTIVE

In humans, TSLP level has been found to be elevated in the lungs of patients with asthma, and in mouse models, TSLP can promote type 2 airway inflammation, primarily through the activation of dendritic cells. However, the mechanisms underlying its role remain unclear. The objective of this study was to provide a mechanistic analysis of TSLP-mediated type 2 airway inflammation METHODS: To dissect the mechanisms of TSLP-mediated type 2 responses, mice were treated with TSLP and antigen to evaluate cellular immune responses. Flow cytometric analyses were used to follow responses in the airways, and conditional deletion of TSLP receptor and adoptive transfer were used to identify the cellular subsets involved in this inflammatory response.

RESULTS

We showed that TSLP can directly promote T_H2-cell differentiation in the lung, independent of the draining lymph nodes. We also identified a population of patrolling monocytes/interstitial macrophages (IMs) (CD11c-expressing IMs) that are both necessary and sufficient for TSLP-mediated T_H2-cell differentiation and airway inflammation. T_H2-cell-driven airway eosinophilia is attenuated by ablation of CD11c-expressing IMs or by selective deficiency of TSLP receptor signaling in these cells. More importantly, CD11c-expressing IMs are sufficient for the induction of acute T_H2-cell responses in the lungs that is independent of dendritic cells and T-cell priming in the draining lymph nodes.

CONCLUSION

These findings indicate a novel mechanistic role for TSLP and CD11c-expressing IMs in the development of acute T_H2-cell-dependent allergic airway inflammation. This work also demonstrates a new role for TSLP in promoting type 2 responses directly in the lung.

Effects of Pelargonium sidoides and Coptis Rhizoma 2 : 1 Mixed Formula (PS + CR) on Ovalbumin-Induced Asthma in Mice

Pelargonium sidoides (PS) is traditionally used to treat respiratory and gastrointestinal infections, dysmenorrhea, and hepatic disorders in South Africa. Coptis Rhizoma (CR) is used to treat gastroenteric disorders, cardiovascular diseases, and cancer in East Asia. In the present study, we intended to observe the possible beneficial antiasthma effects of PS and CR on the ovalbumin- (OVA-) induced asthma C57BL/6J mice. Asthma in mice was induced by OVA sensitization and subsequent boosting. PS + CR (300 and 1,000 mg/kg; PO) or dexamethasone (IP) was administered once a day for 16 days. The changes in the body weight and gains, lung weights and gross inspections, total and differential cell counts of leukocytes in bronchoalveolar lavage fluid (BALF), serum OVA-specific immunoglobulin E (OVA-sIgE) levels, interleukin-4 (IL-4) and IL-5 levels in BALF and lung tissue homogenate, and IL-4 and IL-5 mRNA levels in lung tissue homogenates were analyzed with lung histopathology: mean alveolar surface area (ASA), alveolar septal thickness, numbers of inflammatory cells, mast cells, and eosinophils infiltrated in the alveolar regions, respectively. Significant increases in lung weights, total and differential cell counts of leukocytes in BALF, serum OVA-sIgE levels, and IL-4 and IL-5 levels in BALF and lung tissue homogenate were observed in OVA control as compared to those of intact control. In addition, OVA control showed a significant decrease in mean ASA and increases in alveolar septal thickness, numbers of inflammatory cells, mast cells, and eosinophils infiltrated in alveolar regions. However, these allergic and inflammatory asthmatic changes were significantly inhibited by PS + CR in a dose-dependent manner. In this study, PS + CR showed dose-dependent beneficial effects on OVA-induced asthma in mice through anti-inflammatory and antiallergic activities. Therefore, it is expected that PS + CR have enough potential as a new therapeutic agent or as an ingredient of a medicinal agent for various allergic and inflammatory respiratory diseases including asthma.

Regulatory T Cells in Respiratory Health and Diseases

Respiratory diseases compromise the health of millions of people all over the world and are strongly linked to the immune dysfunction. CD4+FOXP3+ T regulatory cells, also known as Tregs, have a central role maintaining tissue homeostasis during immune responses. Their activity and clinical impact have been widely studied in different clinical conditions including autoimmune diseases, inflammatory conditions, and cancer, amongst others. Tregs express transcription factor forkhead box P3 (FOXP3), which allows regulation of the immune response through anti-inflammatory cytokines such as IL-10 or transforming growth factor beta (TGF-β) and direct cell-to-cell interaction. Maintenance of immune tolerance is achieved via modulation of effector CD4+ T helper 1, 2 or 17 (Th1, Th2, Th17) cells by Tregs. This review highlights the recent progress in the understanding of Tregs in different disorders of the respiratory system.

Cryptotanshinone attenuates allergic airway inflammation through negative regulation of NF-κB and p38 MAPK

This study is to determine the role and mechanism of cryptotanshinone (CTS) in allergic airway inflammation. Asthma induced by OVA was established in BALB/c mice. We found increased airway hyperresponsiveness (AHR), increased inflammatory cell infiltration, elevated levels of TNF-α, interleukin-1β (IL-1β), IL-4, IL-5, IL-6 and IL-13, decreased interferon gamma (IFN-γ) in lung tissue, increased content of total immunoglobulin E (IgE), OVA specific IgE, Eotaxin, ICAM-1, VCAM-1, nuclear factor-kappaB (NF-κB) and phosphorylation of p38 MAPK in lung tissue. However, the administration of CTS significantly decreased AHR in asthmatic mice, reduced inflammation around the bronchioles and inflammatory cells around airway, regulated cytokine production, reduced the total IgE and OVA-specific IgE levels, and inhibited NF-κB activation and p38 MAPK phosphorylation. In vitro experiments in 16 HBE cells revealed that CTS attenuated CAM-1 and IL-6 expression. These results indicate that CTS alleviates allergic airway inflammation by modulating p38 MAPK phosphorylation and NF-κB activation.

Blockade of CCL2/CCR2 signaling pathway prevents inflammatory monocyte recruitment and attenuates OVA-Induced allergic asthma in mice

Recent studies have reported recruitment of inflammatory monocytes by cytokines including chemokine (C-C motif) ligand 2 (CCL2) are critical in allergic responses. We aimed to investigate the role of inflammatory monocytes and CCL2 in mouse model with ovalbumin (OVA)-induced allergic asthma. Mice were sensitized with OVA to induce allergic asthma. The proportion of inflammatory cells in bronchoalveolar lavage fluid (BALF) and peritoneal lavage fluid (PLF) were measured by flow cytometry. The expression of CCL2 and CCL2 receptor (CCR2) were determined by qPCR and western blot. The concentrations of Type 1 helper T (Th1) and Type 2 helper T (Th2) cytokines in PLF were detected by ELISA. Inflammatory monocytes are recruited in PLF, and expression of CCL2 and CCR2 were elevated in OVA-induced mice. In addition, transfer of CCR2 knockdown inflammatory monocytes decreased the levels of allergic asthma biomarkers. Injection of anti-CCL2 or anti-CCR2 antibody decreased the proportion of eosinophils and inflammatory monocytes in BALF. Blockade of CCL2/CCR2 signaling pathway suppressed the allergen-induced Th2 cytokines and enhanced the levels of Th1-associated cytokines. Blockade of CCL2/CCR2 signaling pathway in sensitization-recruited inflammatory monocytes exhibits protective effects in mouse model of OVA-induced allergic asthma by inhibiting the Th2 inflammatory responses.

Therapeutic potential of andrographolide-loaded nanoparticles on a murine asthma model

Corticosteroids commonly prescribed in asthma show several side-effects. Relatively non-toxic andrographolide (AG) has an anti-asthmatic potential. But its poor bioavailability and short plasma half-life constrain its efficacy. To overcome them, we encapsulated AG in nanoparticle (AGNP) and evaluated AGNP for anti-asthmatic efficacy on murine asthma model by oral/pulmonary delivery. AGNP had 5.47% drug loading with a sustained drug release in vitro. Plasma and lung pharmacokinetic data showed predominantly improved AG-bioavailability upon AGNP administered orally/by pulmonary route. Cell numbers, IL-4, IL-5, and IL-13 levels in broncho-alveolar lavage fluid and serum IgE content were reduced significantly after administration of AGNP compared to free-AG treatment. AGNP-mediated suppression of NF-κβ was predominantly more compared to free-AG. Further, pulmonary route showed better therapeutic performance. In conclusion, AGNP effectively controlled mild and severe asthma and the pulmonary administration of AGNP was more efficacious than the oral route.

Exosomes in Allergic Airway Diseases

PURPOSE OF REVIEW

This review will cover what is known regarding exosomes and allergy, and furthermore discuss novel mechanism of exosome-mediated immune modulation and metabolic regulation via the transfer of mitochondria.

RECENT FINDINGS

Exosomes are nano-sized extracellular vesicles (EVs) derived from the endosome that play a direct role in governing physiological and pathological conditions by transferring bioactive cargo such as proteins, enzymes, nucleic acids (miRNA, mRNA, DNA), and metabolites. Recent evidence suggest that exosomes may signal in autocrine but, most importantly, in paracrine and endocrine manner, being taken up by neighboring cells or carried to distant sites. Exosomes also mediate immunogenic responses, such as antigen presentation and inflammation. In asthma and allergy, exosomes facilitate cross-talk between immune and epithelial cells, and drive site-specific inflammation through the generation of pro-inflammatory mediators like leukotrienes. Recent studies suggest that myeloid cell-generated exosomes transfer mitochondria to lymphocytes. Exosomes are nano-sized mediators of the immune system which can modulate responses through antigen presentation, and the transfer of pro- and anti-inflammatory mediators. In addition to conventional mechanisms of immune modulation, exosomes may act as a novel courier of functional mitochondria that is capable of modulating the recipient cells bioenergetics, resulting in altered cellular responses. The transfer of mitochondria and modulation of bioenergetics may result in immune activation or dampening depending on the context.

Recombinant pyrin domain protein attenuates allergic inflammation by suppressing NF-κB pathway in asthmatic mice

Pyrin domain (PYD), a subclass of protein motif known as the death fold, is frequently involved in inflammation and immune responses. PYD modulates nuclear factor-kappa B (NF-κB) signalling pathway upon various stimuli. Herein, a novel recombinant pyrin domain protein (RPYD) was generated. Its role and mechanism in inflammatory response in an ovalbumin (OVA) induced asthma model was investigated. After OVA challenge, there was inflammatory cell infiltration in the lung, as well as airway hyper-responsiveness (AHR) to inhaled methacholine. In addition, eosinophils increased in the bronchoalveolar lavage fluids, alone with the elevated levels of Th-2 type cytokines [interleukin (IL)-4, IL-5 and IL-13], eotaxin, and adhesion molecules. However, the transnasal administration of RPYD before the OVA challenge significantly inhibited these asthmatic reactions. Moreover, RPYD markedly suppressed NF-κB translocation, reduced phosphorylation of p38 MAPK, and thus attenuated the expression of intercellular adhesion molecule 1 and IL-6 in the BEAS-2B cells stimulated by proinflammatory cytokines in vitro. These findings indicate that RPYD can protect asthma host from OVA-induced airway inflammation and AHR via down-regulation of NF-κB and p38 MAPK activities. RPYD may be used as a potential medicine for the treatment of asthma in clinic.

Aloperine suppresses allergic airway inflammation through NF-κB, MAPK, and Nrf2/HO-1 signaling pathways in mice

To explore the effects of aloperine (ALO) on allergic airway inflammation, we investigated whether its mechanism is related with NF-κB, MAPK, and Nrf2/HO-1 signaling pathways. Histochemical staining and inflammatory cell count were used to observe lung histopathological changes in mice. ELISA was used to detect the content of inflammatory cytokines and IgE in the mouse bronchoalveolar lavage fluid (BALF). Airway hyperresponsiveness (AHR) to inhale methacholine was measured by the plethysmography in conscious mice. Immunohistochemical method was used to detect the expression levels of Nrf2 and HO-1 in lung tissues. The key proteins of MAPK, NF-κB, and Nrf2/HO-1 in lung tissues were quantitatively analyzed by Western blot. Finally, the in vitro effect of ALO on the production of pro-inflammatory mediators and cytokines by lipopolysaccharide-stimulated RAW 264.7 cells was also evaluated. In the ovalbumin (OVA)-induced asthma mouse model, ALO reduced the exudation and infiltration of inflammatory cells and suppressed goblet cell hyperplasia. ALO-treated asthmatic mice also decreased the protein levels of interleukin (IL)-4, IL-5, IL-13, IFN-γ, and IgE in BALF and attenuated AHR. Furthermore, ALO inhibited the expression of key proteins of MAPK and NF-κB pathways, and increased the expression of Nrf2/HO-1 in OVA-challenged mice. Additional in vitro study has shown that ALO abrogates the macrophage production of inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor-α, IL-6, and IL-1β. Taken together, ALO attenuated allergic airway inflammation through regulating NF-κB, MAPK, and Nrf2/HO-1 signaling pathways. The results suggest the utility of ALO as an anti-inflammatory agent for the treatment of asthma.

Influence of rutin on the effects of neonatal cigarette smoke exposure-induced exacerbated MMP-9 expression, Th17 cytokines and NF-κB/iNOS-mediated inflammatory responses in asthmatic mice model

Allergic asthma is one of the most enduring diseases of the airway. The T-helper cells and regulatory T-cells are critically involved in inflammatory responses, mucus hypersecretion, airway remodelling and in airway hyper-responsiveness. Cigarette smoke (CS) has been found to aggravate inflammatory responses in asthma. Though currently employed drugs are effective, associated side effects demand identification and development of novel drugs with negligible or no adverse effects. Rutin, plant-derived flavonoid has been found to possess antioxidant and anti-inflammatory effects. We investigated the ability of rutin to modulate T-cells and inhibit inflammation in experimentally-induced asthma in cigarette smoke exposed mice. Separate groups of neonatal mice were exposed to CS for 10 days from post-natal days 2 to 11. After 2 weeks, the mice were sensitized and challenged with ovalbumin (OVA). Treatment group were given rutin (37.5 or 75 mg/kg body weight) during OVA sensitization and challenge. Rutin treatment was found to significantly inhibit cellular infiltration in the airways and Th2 and Th17 cytokine levels as well. Flow cytometry revealed effectively raised CD4⁺CD25⁺Fox3⁺ Treg cells and supressed Th17 cell population on rutin treatment. Airway hyper-responsiveness observed following CS and OVA challenge were inhibited by rutin. NF-κB and iNOS, chief regulators of inflammatory responses robustly activated by CS and OVA were down-regulated by rutin. Rutin also inhibited the expression of matrix metalloproteinase 9, thereby aiding in prevention of airway remodelling in asthma thereby revealing to be a potent candidate in asthma therapy.

Emodin alleviates alternatively activated macrophage and asthmatic airway inflammation in a murine asthma model

Alternatively activated macrophages (AAMs) are not only associated with asthma but also lead to asthmatic airway inflammation and remodeling. Inhibition of AAMs is an alternative therapeutic strategy for treating asthma. In this study we investigated whether emodin (1,3,8-trihydroxy-6-methylanthraquinone), isolated from the rhizome of Rheum palmatum, alleviated asthmatic airway inflammation and reduced AAM polarization in a murine asthma model. Mice were sensitized with a triple allergen mix containing dust mite, ragweed and aspergillus (DRA). In mice with DRA-induced asthma, asthmatic inflammation was significantly enhanced. Intraperitoneal injection of emodin (20 mg·kg^-1·d^-1, ip) 1 h prior to DRA challenge on days 12-14 significantly decreased pulmonary eosinophil and lymphocyte infiltration, mucus secretion and serum IgE production, as well as IL-4 and IL-5 production in bronchoalveolar lavage fluid. In response to emodin treatment, activated markers of AAM Ym-1, Fizz-1 and arginase-1 in the lung tissues were remarkably decreased. In mouse bone marrow-derived macrophages (BMDMs) in vitro, emodin (2-50 μmol/L) dose-dependently inhibited IL-4-induced AAM polarization and STAT6 phosphorylation. Collectively, our results suggest that emodin effectively ameliorates asthmatic airway inflammation and AAM polarization, and it may therefore become a potential agent for the treatment of asthma.

Unique Lipid Signatures of Extracellular Vesicles from the Airways of Asthmatics

Asthma is a chronic inflammatory disease process involving the conductive airways of the human lung. The dysregulated inflammatory response in this disease process may involve multiple cell-cell interactions mediated by signaling molecules, including lipid mediators. Extracellular vesicles (EVs) are lipid membrane particles that are now recognized as critical mediators of cell-cell communication. Here, we compared the lipid composition and presence of specific lipid mediators in airway EVs purified from the bronchoalveolar lavage (BAL) fluid of healthy controls and asthmatic subjects with and without second-hand smoke (SHS) exposure. Airway exosome concentrations were increased in asthmatics, and correlated with blood eosinophilia and serum IgE levels. Frequencies of HLA-DR⁺ and CD54⁺ exosomes were also significantly higher in asthmatics. Lipidomics analysis revealed that phosphatidylglycerol, ceramide-phosphates, and ceramides were significantly reduced in exosomes from asthmatics compared to the non-exposed control groups. Sphingomyelin 34:1 was more abundant in exosomes of SHS-exposed asthmatics compared to healthy controls. Our results suggest that chronic airway inflammation may be driven by alterations in the composition of lipid mediators within airway EVs of human subjects with asthma.

β-Arrestin-2-Dependent Signaling Promotes CCR4-mediated Chemotaxis of Murine T-Helper Type 2 Cells

Allergic asthma is a complex inflammatory disease that leads to significant healthcare costs and reduction in quality of life. Although many cell types are implicated in the pathogenesis of asthma, CD4+ T-helper cell type 2 (Th2) cells are centrally involved. We previously reported that the asthma phenotype is virtually absent in ovalbumin-sensitized and -challenged mice that lack global expression of β-arrestin (β-arr)-2 and that CD4+ T cells from these mice displayed significantly reduced CCL22-mediated chemotaxis. Because CCL22-mediated activation of CCR4 plays a role in Th2 cell regulation in asthmatic inflammation, we hypothesized that CCR4-mediated migration of CD4+ Th2 cells to the lung in asthma may use β-arr-dependent signaling. To test this hypothesis, we assessed the effect of various signaling inhibitors on CCL22-induced chemotaxis using in vitro-polarized primary CD4+ Th2 cells from β-arr2-knockout and wild-type mice. Our results show, for the first time, that CCL22-induced, CCR4-mediated Th2 cell chemotaxis is dependent, in part, on a β-arr2-dependent signaling pathway. In addition, we show that this chemotactic signaling mechanism involves activation of P-p38 and Rho-associated protein kinase. These findings point to a proinflammatory role for β-arr2-dependent signaling and support β-arr2 as a novel therapeutic target in asthma.

Exosomes in Severe Asthma: Update in Their Roles and Potential in Therapy

Exosomes are nanosized vesicles and have recently been recognized as important players in cell-to-cell communication. Exosomes contain different mediators such as proteins, nucleic acids (DNA, mRNA, miRNAs, and other ncRNAs), and lipid mediators and can shuttle their exosomal content to both neighboring and distal cells. Exosomes are very effective in orchestrating immune responses in the airways and all cell types can contribute to the systemic exosome pool. Intracellular communication between the broad range of cell types within the lung is crucial in disease emphasizing the importance of exosomes. In asthma, exosomes affect the inflammatory microenvironment which ultimately determines the development or alleviation of the pathological symptoms. Recent studies in this area have provided insight into the underlying mechanisms of disease and led to interest in using exosomes as potential novel therapeutic agents.

Crucial role of OX40/OX40L signaling in a murine model of asthma

The aim of the present study was to explore the roles of OX40/OX40 ligand (OX40L) signaling and OX40⁺ T cells in ovalbumin (OVA)-induced mouse asthma model. Asthma was induced by OVA exposure and subsequent co-treatment with OX40L protein, neutralizing anti-OX40L blocking antibody, OX40⁺ T cells or PBS. The protein expression levels of interleukin (IL)-4, IL-6, IL-13, IL-17, tumor necrosis factor (TNF)-α and interferon (IFN)-γ in bronchoalveolar lavage fluid (BALF) were examined using murine cytokine-specific ELISA. Eosinophil accumulation as well as proliferation and apoptosis of T cells in BALF were detected by Cell Counting kit-8 and flow cytometric assays. Expression of the apoptosis-related protein cleaved caspase-3 was examined in OX40⁺ T cells using western blot assay. Flow cytometric analysis revealed that OVA-treated mice that were co-treated with OX40L or OX40⁺ T cells exhibited higher eosinophil infiltration compared with control mice treated only with OVA, whereas neutralizing anti-OX40L blocking antibody inhibited eosinophil infiltration. ELISA assays demonstrated that the expression of IL-4, IL-6, IL-13, IL-17, TNF-α and IFN-γ in BALF in OX40L-treated and OX40⁺ T cell-treated mice was increased compared with expression levels in control mice. Treatment with OX40L protein effectively reduced apoptosis of T cells and the expression of cleaved caspase-3 in T cells. OX40L-treated and OX40⁺ T cell-treated mice exhibited increased asthma through OX40/OX40L signaling, which probably promoted inflammatory factor expression, eosinophil infiltration and T cell proliferation.

Prevention of Asthma Exacerbation in a Mouse Model by Simultaneous Inhibition of NF-κB and STAT6 Activation Using a Chimeric Decoy Strategy

Transactivation of inflammatory and immune mediators in asthma is tightly regulated by nuclear factor κB (NF-κB) and signal transducer and activator of transcription 6 (STAT6). Therefore, we investigated the efficacy of simultaneous inhibition of NF-κB and STAT6 using a chimeric decoy strategy to prevent asthma exacerbation. The effects of decoy oligodeoxynucleotides were evaluated using an ovalbumin-induced mouse asthma model. Ovalbumin-sensitized mice received intratracheal administration of decoy oligodeoxynucleotides 3 days before ovalbumin challenge. Fluorescent-dye-labeled decoy oligodeoxynucleotides could be detected in lymphocytes and macrophages in the lung, and activation of NF-κB and STAT6 was inhibited by chimeric decoy oligodeoxynucleotide transfer. Consequently, treatment with chimeric or NF-κB decoy oligodeoxynucleotides protected against methacholine-induced airway hyperresponsiveness, whereas the effect of chimeric decoy oligodeoxynucleotides was significantly greater than that of NF-κB decoy oligodeoxynucleotides. Treatment with chimeric decoy oligodeoxynucleotides suppressed airway inflammation through inhibition of overexpression of interleukin-4 (IL-4), IL-5, and IL-13 and inflammatory infiltrates. Histamine levels in the lung were reduced via suppression of mast cell accumulation. A significant reduction in mucin secretion was observed due to suppression of MUC5AC gene expression. Interestingly, the inhibitory effects on IL-5, IL-13, and histamine secretion were achieved by transfer of chimeric decoy oligodeoxynucleotides only. This novel therapeutic approach could be useful to treat patients with various types of asthma.

Nanoparticle impact on innate immune cell pattern-recognition receptors and inflammasomes activation

Nanotechnology-based strategies can dramatically impact the treatment, prevention and diagnosis of a wide range of diseases. Despite the unprecedented success achieved with the use of nanomaterials to address unmet biomedical needs and their particular suitability for the effective application of a personalized medicine, the clinical translation of those nanoparticulate systems has still been impaired by the limited understanding on their interaction with complex biological systems. As a result, unexpected effects due to unpredicted interactions at biomaterial and biological interfaces have been underlying the biosafety concerns raised by the use of nanomaterials. This review explores the current knowledge on how nanoparticle (NP) physicochemical and surface properties determine their interactions with innate immune cells, with particular attention on the activation of pattern-recognition receptors and inflammasome. A critical perspective will additionally address the impact of biological systems on the effect of NP on immune cell activity at the molecular level. We will discuss how the understanding of the NP-innate immune cell interactions can significantly add into the clinical translation by guiding the design of nanomedicines with particular effect on targeted cells, thus improving their clinical efficacy while minimizing undesired but predictable toxicological effects.

Inhibitory effect of a new orally active cedrol-loaded nanostructured lipid carrier on compound 48/80-induced mast cell degranulation and anaphylactic shock in mice

BACKGROUND

Type I hypersensitivity is an allergic reaction characterized by the overactivity of the immune system provoked by normally harmless substances. Glucocorticoids, anti-histamines, or mast cell stabilizers are the choices of treatment for type I hypersensitivity. Even though these drugs have the anti-allergic effect, they can have several side effects in prolong use. Cedrol is the main bioactive compound of Cedrus atlantica with anti-tumor, anti-oxidative, and platelet-activating factor inhibiting properties.

METHODS

In this study, the preparation and anti-anaphylactic effect of cedrol-loaded nanostructured lipid carriers (NLCs) were evaluated. NLCs were prepared using Compritol® 888 ATO and triolein as lipid phase and vitamin E d-α-tocopherylpolyethyleneglycol 1000 succinate, soya lecithin, and sodium deoxycholate as nanoparticle stabilizers.

RESULTS

The average diameter of cedrol-NLCs (CR-NLCs) was 71.2 nm (NLC-C1) and 91.93 nm (NLC-C2). The particle had negative zeta potential values of -31.9 mV (NLC-C1) and -44.5 mV (NLC-C2). Type I anaphylactoid reaction in the animal model is significantly reduced by cedrol and cedrol-NLC. This in vivo activity of cedrol resulted that cedrol suppressed compound 48/80-induced peritoneal mast cell degranulation and histamine release from mast cells. Furthermore, compound 48/80-evoked Ca2+ uptake into mast cells was reduced in a dose-dependent manner by cedrol and cedrol-NLC. Studies confirmed that the inhibition of type I anaphylactoid response in vivo in mice and compound 48/80-induced mast cell activation in vitro are greatly enhanced by the loading of cedrol into the NLCs. The safety of cedrol and CR-NLC was evaluated as selectivity index (SI) with prednisolone and cromolyn sodium as positive control. SI of CR-NLC-C2 was found to be 11.5-fold greater than both prednisolone and cromolyn sodium.

CONCLUSION

Administration of CR-NLC 24 hours before the onset of anaphylaxis can prevent an anaphylactoid reaction. NLCs could be a promising vehicle for the oral delivery of cedrol to protect anaphylactic reactions.

New Insights Into the Relationship Between Chitinase-3-Like-1 and Asthma

PURPOSE OF REVIEW

CHI3L1 (also known as YKL-40), a member of "mammalian chitinase-like proteins," is a serum protein lacking enzymatic activity. Although the protein is highly conserved in mammals, a consensus regarding its role in human pathologies is currently lacking. In an attempt to shed light on the many physiological functions of the protein, specifically with regard to asthma, a comprehensive overview of recent studies is provided.

RECENT FINDINGS

In asthma, CHI3L1 is secreted from macrophages and airway epithelial cells through an IL-13 related mechanism. Th2-associated inflammatory responses due to allergen exposure, resulting in airway hyper-responsiveness and smooth muscle contraction, play a role in tissue remodeling. The importance of CHI3L1 in initiation and development of asthma is not limited to its involvement in highly orchestrated events of inflammatory cytokines but further research is needed for further elucidation. Levels of the protein are associated with severity for numerous pathologies, including asthma, suggesting limited specificity as a biomarker.

T-lymphocyte homing: an underappreciated yet critical hurdle for successful cancer immunotherapy

Advances in cancer immunotherapy have offered new hope for patients with metastatic disease. This unfolding success story has been exemplified by a growing arsenal of novel immunotherapeutics, including blocking antibodies targeting immune checkpoint pathways, cancer vaccines, and adoptive cell therapy (ACT). Nonetheless, clinical benefit remains highly variable and patient-specific, in part, because all immunotherapeutic regimens vitally hinge on the capacity of endogenous and/or adoptively transferred T-effector (T_eff) cells, including chimeric antigen receptor (CAR) T cells, to home efficiently into tumor target tissue. Thus, defects intrinsic to the multi-step T-cell homing cascade have become an obvious, though significantly underappreciated contributor to immunotherapy resistance. Conspicuous have been low intralesional frequencies of tumor-infiltrating T-lymphocytes (TILs) below clinically beneficial threshold levels, and peripheral rather than deep lesional TIL infiltration. Therefore, a T_eff cell 'homing deficit' may arguably represent a dominant factor responsible for ineffective immunotherapeutic outcomes, as tumors resistant to immune-targeted killing thrive in such permissive, immune-vacuous microenvironments. Fortunately, emerging data is shedding light into the diverse mechanisms of immune escape by which tumors restrict T_eff cell trafficking and lesional penetrance. In this review, we scrutinize evolving knowledge on the molecular determinants of T_eff cell navigation into tumors. By integrating recently described, though sporadic information of pivotal adhesive and chemokine homing signatures within the tumor microenvironment with better established paradigms of T-cell trafficking under homeostatic or infectious disease scenarios, we seek to refine currently incomplete models of T_eff cell entry into tumor tissue. We further summarize how cancers thwart homing to escape immune-mediated destruction and raise awareness of the potential impact of immune checkpoint blockers on T_eff cell homing. Finally, we speculate on innovative therapeutic opportunities for augmenting T_eff cell homing capabilities to improve immunotherapy-based tumor eradication in cancer patients, with special focus on malignant melanoma.

Bupleurum chinense extract ameliorates an OVA-induced murine allergic asthma through the reduction of the Th2 and Th17 cytokines production by inactivation of NFκB pathway

Bupleurum chinense belongs to the Bupleurum spp. family that has been used in traditional herbal medicine for over thousand years. It has been reported to have anti-inflammatory, anti-oxidant, hepato-protective, antipyretic, analgesic, anti-fibrotic and immunomodulatory effect. However, the effect of B. Chinense on allergic asthma remains unclear. This study investigated the immunomodulatory effects of B. Chinense extracts (BCE) on airway inflammation in asthmatic mice model. In the ovalbumin (OVA)-induced allergic asthma model, we evaluated the number of total cells, differential inflammatory cells and the production of proinflammatory cytokines in bronchoalveolar lavage fluid (BALF) and lung homogenate as well as histological structure. The levels of NFκB p65, IκBα, p-NFκB p65, p-IκBα and the total immunoglobulin (Ig) E, anti-OVA IgE, anti-OVA IgG were also examined. The oral administration of 200mg/kg BCE inhibited the accumulation of inflammatory cells especially eosinophils in BALF. Also, BCE regulated the imbalance of Th1, Th2 and Th17-related production, with attenuated the expression of GATA3, IL-1β, IL-4, IL-5, IL-6, TNF-α and RORγt, IL-17A in BALF and lung homogenate, meanwhile, up-regulated the secretion of INF-γ in lung homogenate. The levels of IgE, anti-OVA IgE, anti-OVA IgG1 and anti-OVA IgG2a were also suppressed by BCE treatment in serum. Futhermore, BCE inhibited the proinflammatory cytokines via inactivation of NFκB p65 phosphorylation and IκBα degradation in cytoplasm. The histological analysis showed that the infiltration of inflammatory cells, mucus hypersecretion and collagen fiber deposits were ameliorated in BCE treated mice. In addition, BCE induced the functional differentiation of naive CD4+ T cells forward to Th1 and Tr1 through producing INF-γ and IL-10. These results suggest that BCE may have therapeutic potential for treating allergic asthma through inhibiting Th2/Th17 cytokines production by inactivation of NFκB pathway.

Exosomes in immunoregulation of chronic lung diseases

Exosomes are nano-sized, membrane-bound vesicles released from cells that transport cargo including DNA, RNA, and proteins, between cells as a form of intercellular communication. In addition to their role in intercellular communication, exosomes are beginning to be appreciated as agents of immunoregulation that can modulate antigen presentation, immune activation, suppression, and surveillance. This article summarizes how these multifaceted functions of exosomes may promote development and/or progression of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis. The potential of exosomes as a novel therapeutic is also discussed.

A novel peptide ADAM8 inhibitor attenuates bronchial hyperresponsiveness and Th2 cytokine mediated inflammation of murine asthmatic models

A disintegrin and metalloproteinase 8 (ADAM8) has been identified as a signature gene associated with moderate and severe asthma. Studies in mice have demonstrated that the severity of asthma can be reduced by either transgenic knock-out or by antibodies blocking ADAM8 function, highlighting ADAM8 as potential drug target for asthma therapy. Here, we examined the therapeutic effect of an ADAM8 inhibitor peptide (BK-1361) that specifically blocks cellular ADAM8 activity in ovalbumin-sensitized and challenged Balb/c mice. We found that BK-1361 (25 μg/g body weight) attenuated airway responsiveness to methacholine stimulation by up to 42%, concomitantly reduced tissue remodeling by 50%, and decreased inflammatory cells (e.g. eosinophils down by 54%)/inflammatory factors (e.g. sCD23 down by 50%)/TH2 cytokines (e.g. IL-5 down by 70%)/ADAM8-positive eosinophils (down by 60%) in the lung. We further verified that BK-1361 specifically targets ADAM8 in vivo as the peptide caused significantly reduced levels of soluble CD23 in wild-type but not in ADAM8-deficient mice. These findings suggest that BK-1361 blocks ADAM8-dependent asthma effects in vivo by inhibiting infiltration of eosinophils and TH2 lymphocytes, thus leading to reduction of TH2-mediated inflammation, tissue remodeling and bronchial hyperresponsiveness. Taken together, pharmacological ADAM8 inhibition appears as promising novel therapeutic strategy for the treatment of asthma.

Aquaporin-3 potentiates allergic airway inflammation in ovalbumin-induced murine asthma

Oxidative stress plays a pivotal role in the pathogenesis of asthma. Aquaporin-3 (AQP3) is a small transmembrane water/glycerol channel that may facilitate the membrane uptake of hydrogen peroxide (H2O2). Here we report that AQP3 potentiates ovalbumin (OVA)-induced murine asthma by mediating both chemokine production from alveolar macrophages and T cell trafficking. AQP3 deficient (AQP3(-/-)) mice exhibited significantly reduced airway inflammation compared to wild-type mice. Adoptive transfer experiments showed reduced airway eosinophilic inflammation in mice receiving OVA-sensitized splenocytes from AQP3(-/-) mice compared with wild-type mice after OVA challenge, consistently with fewer CD4(+) T cells from AQP3(-/-) mice migrating to the lung than from wild-type mice. Additionally, in vivo and vitro experiments indicated that AQP3 induced the production of some chemokines such as CCL24 and CCL22 through regulating the amount of cellular H2O2 in M2 polarized alveolar macrophages. These results imply a critical role of AQP3 in asthma, and AQP3 may be a novel therapeutic target.

A Player and Coordinator: The Versatile Roles of Eosinophils in the Immune System

Eosinophils have traditionally been associated with allergic diseases and parasite infection. Research advances in the recent decades have brought evolutionary changes in our understanding of eosinophil biology and its roles in immunity. It is currently recognized that eosinophils play multiple roles in both innate and adaptive immunity. As effector cells in innate immunity, eosinophils exert a pro-inflammatory and destructive role in the Th2 immune response associated with allergic inflammation or parasite infection. Eosinophils can also be recruited by danger signals released by pathogen infections or tissue injury, inducing host defense against parasitic, fungal, bacterial or viral infection or promoting tissue repair and remodeling. Eosinophils also serve as nonprofessional antigen-presenting cells in response to allergen challenge or helminth infection, and, meanwhile, are known to function as a versatile coordinator that actively regulates or interacts with various immune cells including T lymphocytes and dendritic cells. More roles of eosinophils implicated in immunity have been proposed including in immune homeostasis, allograft rejection, and anti-tumor immunity. Eosinophil interactions with structural cells are also implicated in the mechanisms in allergic inflammation and in Helicobacter pylori gastritis. These multifaceted roles of eosinophils as both players and coordinators in immune system are discussed in this review.

Genetic Deletion of β-Arrestin-2 and the Mitigation of Established Airway Hyperresponsiveness in a Murine Asthma Model

β-Arrestin-2 (βarr2) is a ubiquitously expressed cytosolic protein that terminates G protein-coupled receptor signaling and transduces G protein-independent signaling. We previously showed that mice lacking βarr2 do not develop an asthma phenotype when sensitized to, and challenged with, allergens. The current study evaluates if an established asthma phenotype can be mitigated by deletion of βarr2 using an inducible Cre recombinase. We sensitized and challenged mice to ovalbumin (OVA) and demonstrated that on Day (d) 24 the allergic asthma phenotype was apparent in uninduced βarr2 and wild-type (WT) mice. In a second group of OVA-treated mice, tamoxifen was injected on d24 to d28 to activate Cre recombinase, and OVA aerosol challenge was continued through d44. The asthma phenotype was assessed using lung mechanics measurements, bronchoalveolar lavage cell analysis, and histological assessment of mucin and airway inflammation. Compared with their respective saline-treated controls, OVA-treated WT mice and mice expressing the inducible Cre recombinase displayed a significant asthma phenotype at d45. Whereas tamoxifen treatment had no significant effect on the asthma phenotype in WT mice, it inhibited βarr2 expression and caused a significant reduction in airway hyper-responsiveness (AHR) in Cre-inducible mice. These findings suggest that βarr2 is actively required for perpetuation of the AHR component of the allergic asthma phenotype. Our finding that βarr2 participates in the perpetuation of AHR in an asthma model means that targeting βarr2 may provide immediate and potentially long-term relief from daily asthma symptoms due to AHR irrespective of inflammation.

Differential Gene Expression Profiles and Selected Cytokine Protein Analysis of Mediastinal Lymph Nodes of Horses with Chronic Recurrent Airway Obstruction (RAO) Support an Interleukin-17 Immune Response

Recurrent airway obstruction (RAO) is a pulmonary inflammatory condition that afflicts certain mature horses exposed to organic dust particulates in hay. Its clinical and pathological features, manifested by reversible bronchoconstriction, excessive mucus production and airway neutrophilia, resemble the pulmonary alterations that occur in agricultural workers with occupational asthma. The immunological basis of RAO remains uncertain although its chronicity, its localization to a mucosal surface and its domination by a neutrophilic, non-septic inflammatory response, suggest involvement of Interleukin-17 (IL-17). We examined global gene expression profiles in mediastinal (pulmonary-draining) lymph nodes isolated from RAO-affected and control horses. Differential expression of > 200 genes, coupled with network analysis, supports an IL-17 response centered about NF-κB. Immunohistochemical analysis of mediastinal lymph node sections demonstrated increased IL-17 staining intensity in diseased horses. This result, along with the finding of increased IL-17 concentrations in lymph node homogenates from RAO-affected horses (P = 0.1) and a down-regulation of IL-4 gene and protein expression, provides additional evidence of the involvement of IL-17 in the chronic stages of RAO. Additional investigations are needed to ascertain the cellular source of IL-17 in this equine model of occupational asthma. Understanding the immunopathogenesis of this disorder likely will enhance the development of therapeutic interventions beneficial to human and animal pulmonary health.

Usefulness of targeting lymphocyte Kv1.3-channels in the treatment of respiratory diseases

T lymphocytes predominantly express delayed rectifier K(+)-channels (Kv1.3) in their plasma membranes. Patch-clamp studies revealed that the channels play crucial roles in facilitating the calcium influx necessary to trigger lymphocyte activation and proliferation. Using selective channel inhibitors in experimental animal models, in vivo studies further revealed the clinically relevant relationship between the channel expression and the development of chronic respiratory diseases, in which chronic inflammation or the overstimulation of cellular immunity in the airways is responsible for the pathogenesis. In chronic respiratory diseases, such as chronic obstructive pulmonary disease, asthma, diffuse panbronchiolitis and cystic fibrosis, in addition to the supportive management for the symptoms, the anti-inflammatory effects of macrolide antibiotics were shown to be effective against the over-activation or proliferation of T lymphocytes. Recently, we provided physiological and pharmacological evidence that macrolide antibiotics, together with calcium channel blockers, HMG-CoA reductase inhibitors, and nonsteroidal anti-inflammatory drugs, effectively suppress the Kv1.3-channel currents in lymphocytes, and thus exert anti-inflammatory or immunomodulatory effects. In this review article, based on the findings obtained from recent in vivo and in vitro studies, we address the novel therapeutic implications of targeting the lymphocyte Kv1.3-channels for the treatment of chronic or acute respiratory diseases.

Natural killer cells in the development of asthma

Asthma is an immune-mediated disease of the airways characterized by reversible airway obstruction, bronchial eosinophilic inflammation, and airway hyperresponsiveness (AHR). The immune dysregulation in asthma has been attributed to the involvement of diverse immune cells that contribute to the immunopathology of the disease. Natural killer (NK) cells play critical roles in host defense against viruses and various cancers. Accumulating evidence demonstrates additional important roles for these cells in T cell priming, dendritic cell maturation, and the development of inflammation, all of which have the potential to enhance or dampen allergic responses. The ability of NK cells to produce Th2-type cytokines and their pivotal role in combating respiratory infections which cause airway dysfunction in asthmatics further suggest that they may directly contribute to the immunopathogenesis of allergic airway disease. In this review, we examine emerging evidence and discuss the putative roles of NK cells in the sensitization, progression, and resolution of asthma.

IL-13 overexpression in mouse lungs triggers systemic genotoxicity in peripheral blood

Asthma is a common heterogeneous disease with both genetic and environmental factors that affects millions of individuals worldwide. Activated type 2 helper T cells secrete a panel of cytokines, including IL-13, a central immune regulator of many of the hallmark type 2 disease characteristics found in asthma. IL-13 has been directly implicated as a potent stimulator of asthma induced airway remodeling. Although IL-13 is known to play a major role in the development and persistence of asthma, the complex combination of environmental and genetic origin of the disease obfuscate the solitary role of IL-13 in the disease. We therefore, used a genetically modified mouse model which conditionally overexpresses IL-13 in the lungs to study the independent role of IL-13 in the progression of asthma. Our results demonstrate IL-13 is associated with a systemic induction of genotoxic parameters such as oxidative DNA damage, single and double DNA strand breaks, micronucleus formation, and protein nitration. Furthermore we show that inflammation induced genotoxicity found in asthma extends beyond the primary site of the lung to circulating leukocytes and erythroblasts in the bone marrow eliciting systemic effects driven by IL-13 over-expression.

Re-defining the unique roles for eosinophils in allergic respiratory inflammation

The role of eosinophils in the progression and resolution of allergic respiratory inflammation is poorly defined despite the commonality of their presence and in some cases their use as a biomarker for disease severity and/or symptom control. However, this ambiguity belies the wealth of insights that have recently been gained through the use of eosinophil-deficient/attenuated strains of mice that have demonstrated novel immunoregulatory and remodelling/repair functions for these cells in the lung following allergen provocation. Specifically, studies of eosinophil-deficient mice suggest that eosinophils contribute to events occurring in the lungs following allergen provocation at several key moments: (i) the initiating phase of events leading to Th2-polarized pulmonary inflammation, (ii) the suppression Th1/Th17 pathways in lung-draining lymph nodes, (iii) the recruitment of effector Th2 T cells to the lung, and finally, (iv) mechanisms of inflammatory resolution that re-establish pulmonary homoeostasis. These suggested functions have recently been confirmed and expanded upon using allergen provocation of an inducible eosinophil-deficient strain of mice (iPHIL) that demonstrated an eosinophil-dependent mechanism(s) leading to Th2 dominated immune responses in the presence of eosinophils in contrast to neutrophilic as well as mixed Th1/Th17/Th2 variant phenotypes in the absence of eosinophils. These findings highlighted that eosinophils are not exclusively downstream mediators controlled by T cells, dendritic cells (DC) and/or innate lymphocytic cells (ILC2). Instead, eosinophils appear to be more aptly described as significant contributors in complex interrelated pathways that lead to pulmonary inflammation and subsequently promote resolution and the re-establishment of homoeostatic baseline. In this review, we summarize and put into the context the evolving hypotheses that are now expanding our understanding of the roles eosinophils likely have in the lung following allergen provocation.