New advances and potential therapies for the treatment of asthma

Donor-defined mesenchymal stem cell antimicrobial potency against nontuberculous mycobacterium

Chronic nontuberculous mycobacterial infections with Mycobacterium avium and Mycobacterium intracellulare complicate bronchiectasis, chronic obstructive airway disease, and the health of aging individuals. These insidious intracellular pathogens cause considerable morbidity and eventual mortality in individuals colonized with these bacteria. Current treatment regimens with antibiotic macrolides are both toxic and often inefficient at providing infection resolution. In this article, we demonstrate that human marrow‐derived mesenchymal stem cells are antimicrobial and anti‐inflammatory in vitro and in the context of an in vivo sustained infection of either M. avium and/or M. intracellulare.

Role of Autophagy in Lung Inflammation

Autophagy is a cellular recycling system found in almost all types of eukaryotic organisms. The system is made up of a variety of proteins which function to deliver intracellular cargo to lysosomes for formation of autophagosomes in which the contents are degraded. The maintenance of cellular homeostasis is key in the survival and function of a variety of human cell populations. The interconnection between metabolism and autophagy is extensive, therefore it has a role in a variety of different cell functions. The disruption or dysfunction of autophagy in these cell types have been implicated in the development of a variety of inflammatory diseases including asthma. The role of autophagy in non-immune and immune cells both lead to the pathogenesis of lung inflammation. Autophagy in pulmonary non-immune cells leads to tissue remodeling which can develop into chronic asthma cases with long term effects. The role autophagy in the lymphoid and myeloid lineages in the pathology of asthma differ in their functions. Impaired autophagy in lymphoid populations have been shown, in general, to decrease inflammation in both asthma and inflammatory disease models. Many lymphoid cells rely on autophagy for effector function and maintained inflammation. In stark contrast, autophagy deficient antigen presenting cells have been shown to have an activated inflammasome. This is largely characterized by a T_H17 response that is accompanied with a much worse prognosis including granulocyte mediated inflammation and steroid resistance. The cell specificity associated with changes in autophagic flux complicates its targeting for amelioration of asthmatic symptoms. Differing asthmatic phenotypes between T_H2 and T_H17 mediated disease may require different autophagic modulations. Therefore, treatments call for a more cell specific and personalized approach when looking at chronic asthma cases. Viral-induced lung inflammation, such as that caused by SARS-CoV-2, also may involve autophagic modulation leading to inflammation mediated by lung resident cells. In this review, we will be discussing the role of autophagy in non-immune cells, myeloid cells, and lymphoid cells for their implications into lung inflammation and asthma. Finally, we will discuss autophagy's role viral pathogenesis, immunometabolism, and asthma with insights into autophagic modulators for amelioration of lung inflammation.

Mahuang decoction mitigates airway inflammation and regulates IL-21/STAT3 signaling pathway in rat asthma model

ETHNOPHARMACOLOGICAL RELEVANCE

Nowadays, bronchial asthma is still a severe disease threatening human health, and it is incumbent upon us to seek effective therapeutic drugs. Mahuang decoction (MHD), a classic famous Chinese prescription, has been used for thousands of years to prevent phlegm from forming, stop coughing and relieve asthma, but the relevant mechanism has not been thoroughly clarified. This study aims to investigate the anti-airway inflammation effect of MHD and the possible molecular mechanism underlying IL21/STAT3 signaling pathway, so as to provide guidance for the treatment of MHD on bronchial asthma.

MATERIALS AND METHODS

Specific pathogen free SD rats were randomly divided into 6 groups: normal control group, model group, positive group (Compound methoxyphenamine), MHD-treated groups at doses of 10 ml/kg, 5 ml/kg and 2.5 ml/kg, 10 rats in each group. Except for the normal control group, rats in other groups were sensitized with ovalbumin via introperitoneal injection and challenged with ovalbumin inhalation to trigger asthma model. At 24 h after the last excitation, bronchoalveolar lavage fluid (BALF) of every rat was drawn and the number of inflammatory cells was analyzed using cell counting method. ELISA method was performed to determine the concentrations of TXB₂, 6-keto-PGF_1α, MMP-9, TIMP-1, IL-2, IL-4, IL-5 and TNF-α in rat serum. The protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in murine pulmonary tissues were assessed with western blotting analysis.

RESULTS

Compared with the control group, the airway wall and airway smooth muscle of murine pulmonary tissues significantly thickened and massive inflammatory cells infiltration occurred around the bronchus in the model group, and the cell counts of WBC and EOS in BALF were also apparently increased, which indicated the rat asthma model was successfully established. MHD or Compound methoxyphenamine not only alleviated the pulmonary inflammatory pathological damages, but also down- regulated the numbers of WBC and EOS in BALF. What's more, the levels of TXB₂, MMP-9, TIMP-1, ILs-(2, 4, 5) and TNF-α in rat serum were lessened by the treatment of MHD. In western blotting analysis, treatment with 10 ml/kg or 5 ml/kg MHD markedly declined the increased protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in lung tissues of asthmatic rats to normal level.

CONCLUSION

MHD intervention demonstrated a strong inhibitory action on the secretion of inflammatory mediators as well as the inflammatory cell infiltration in pulmonary tissues of asthmatic rats, and also depressed the protein expressions of IL-21, IL-21R, STAT3 and p-STAT3 in pulmonary tissues. MHD effectively mitigates airway inflammation and regulates the IL-21/STAT3 signaling pathway in rat asthma model.

Pollen lipidomics: lipid profiling exposes a notable diversity in 22 allergenic pollen and potential biomarkers of the allergic immune response

Background/Aim

Pollen grains are the male gametophytes that deliver sperm cells to female gametophytes during sexual reproduction of higher plants. Pollen is a major source of aeroallergens and environmental antigens. The pollen coat harbors a plethora of lipids that are required for pollen hydration, germination, and penetration of the stigma by pollen tubes. In addition to proteins, pollen displays a wide array of lipids that interact with the human immune system. Prior searches for pollen allergens have focused on the identification of intracellular allergenic proteins, but have largely overlooked much of the extracellular pollen matrix, a region where the majority of lipid molecules reside. Lipid antigens have attracted attention for their potent immunoregulatory effects. By being in close proximity to allergenic proteins on the pollen surface when they interact with host cells, lipids could modify the antigenic properties of proteins.

Methodology/Principal Findings

We performed a comparative pollen lipid profiling of 22 commonly allergenic plant species by the use of gas chromatography-mass spectroscopy, followed by detailed data mining and statistical analysis. Three experiments compared pollen lipid profiles. We built a database library of the pollen lipids by matching acquired pollen-lipid mass spectra and retention times with the NIST/EPA/NIH mass-spectral library. We detected, identified, and relatively quantified more than 106 lipid molecular species including fatty acids, n-alkanes, fatty alcohols, and sterols. Pollen-derived lipids stimulation up-regulate cytokines expression of dendritic and natural killer T cells co-culture.

Conclusions/Significance

Here we report on a lipidomic analysis of pollen lipids that can serve as a database for identifying potential lipid antigens and/or novel candidate molecules involved in allergy. The database provides a resource that facilitates studies on the role of lipids in the immunopathogenesis of allergy. Pollen lipids vary greatly among allergenic species and contain many molecules that have stimulatory or regulatory effects on immune responses.

Asthma heterogeneity and therapeutic options from the clinic to the bench

PURPOSE OF REVIEW

Asthma is a chronic pulmonary inflammatory disease affecting all races, children and adults. The causative or intrinsic development of asthma is diverse, ranging from episodic exposure to environmental insults to physical induction in exercise.

RECENT FINDINGS

Asthma uniquely manifests in affected individuals as episodes of airway hyper-reactivity, chronic airway obstruction, and inflammation. The diversity in asthmatic phenotypes and the mechanisms that lead to initiation and perpetuation of the lung disease continue to make asthma a challenge to treat, classify, and manage therapeutically.

SUMMARY

This review will focus on the newest of mechanistic insights into asthma development, therapeutic innovations, and clinical applications.

Defining human mesenchymal stem cell efficacy in vivo

Allogeneic human mesenchymal stem cells (hMSCs) can suppress graft versus host disease (GvHD) and have profound anti-inflammatory and regenerative capacity in stroke, infarct, spinal cord injury, meniscus regeneration, tendinitis, acute renal failure, and heart disease in human and animal models of disease. There is significant clinical hMSC variability in efficacy and the ultimate response in vivo. The challenge in hMSC based therapy is defining the efficacy of hMSC in vivo. Models which may provide insight into hMSC bioactivity in vivo would provide a means to distinguish hMSCs for clinical utility. hMSC function has been described as both regenerative and trophic through the production of bioactive factors. The regenerative component involves the multi-potentiality of hMSC progenitor differentiation. The secreted factors generated by the hMSCs are milieu and injury specific providing unique niches for responses in vivo. These bioactive factors are anti-scarring, angiogenic, anti-apoptotic as well as regenerative. Further, from an immunological standpoint, hMSC's can avoid host immune response, providing xenographic applications. To study the in vivo immuno-regulatory effectiveness of hMSCs, we used the ovalbumin challenge model of acute asthma. This is a quick 3 week in vivo pulmonary inflammation model with readily accessible ways of measuring effectiveness of hMSCs. Our data show that there is a direct correlation between the traditional ceramic cube score to hMSCs attenuation of cellular recruitment due to ovalbumin challenge. The results from these studies verify the in vivo immuno-modulator effectiveness of hMSCs and support the potential use of the ovalbumin model as an in vivo model of hMSC potency and efficacy. Our data also support future directions toward exploring hMSCs as an alternative therapeutic for the treatment of airway inflammation associated with asthma.

Human mesenchymal stem cells suppress chronic airway inflammation in the murine ovalbumin asthma model

Allogeneic human mesenchymal stem cells (hMSCs) introduced intravenously can have profound anti-inflammatory activity resulting in suppression of graft vs. host disease as well as regenerative events in the case of stroke, infarct, spinal cord injury, meniscus regeneration, tendinitis, acute renal failure, and heart disease in human and animal models of these diseases. hMSCs produce bioactive factors that provide molecular cuing for: 1) immunosuppression of T cells; 2) antiscarring; 3) angiogenesis; 4) antiapoptosis; and 5) regeneration (i.e., mitotic for host-derived progenitor cells). Studies have shown that hMSCs have profound effects on the immune system and are well-tolerated and therapeutically active in immunocompetent rodent models of multiple sclerosis and stroke. Furthermore, intravenous administration of MSCs results in pulmonary localization. Asthma is a major debilitating pulmonary disease that impacts in excess of 150 million people in the world with uncontrolled asthma potentially leading to death. In addition, the socioeconomic impact of asthma-associated illnesses at the pediatric and adult level are in the millions of dollars in healthcare costs and lost days of work. hMSCs may provide a viable multiaction therapeutic for this inflammatory lung disease by secreting bioactive factors or directing cellular activity. Our studies show the effectiveness and specificity of the hMSCs on decreasing chronic airway inflammation associated with the murine ovalbumin model of asthma. In addition, the results from these studies verify the in vivo immunoeffectiveness of hMSCs in rodents and support the potential therapeutic use of hMSCs for the treatment of airway inflammation associated with chronic asthma.

In vitro relaxant and spasmolytic effects of constituents from Viburnum prunifolium and HPLC quantification of the bioactive isolated iridoids

ETHNOPHARMACOLOGICAL RELEVANCE

Viburnum prunifolium is a North America shrub used in ethnomedicine because of its spasmolytic, sedative, and anti-asthmatic properties.

AIM OF THE STUDY

Contrasting results were reported in past literature about the active principles of this plant. Our aim was to clarify this matter by evaluating the relaxant and spasmolytic activities of the main constituents obtained from the drug.

MATERIALS AND METHODS

The pharmacological assays were carried out on rabbit jejunum spontaneous contractions and on guinea-pig carbachol-precontracted trachea.

RESULTS

Cumulative concentration (1-100 microg/ml) of Viburnum prunifolium methanolic extract (MeOH extract), its purified fractions soluble in ethylacetate (EtOAc fraction) and in n-butanol (BuOH fraction), and the iridoid glucosides (2 x 10(-5) to 4 x 10(-4)M): 2'-O-acetyldihydropenstemide (1), 2'-O-trans-p-coumaroyldihydropenstemide (2), 2'-O-acetylpatrinoside (3), and patrinoside (4), isolated from EtOAc fraction (1 and 2) and BuOH fraction (3 and 4), induced both relaxant effect of rabbit jejunum spontaneous contractions and spasmolytic effect on guinea-pig carbachol (5.5 x 10(-7)M)-precontracted trachea. Propranolol (10(-6)M) antagonised all Viburnum prunifolium tested components relaxant and spasmolytic effects. At non-relaxing concentrations (0.5 microg/ml), MeOH extract and its fractions induced a potentiating effect of isoprenaline cumulative concentrations also in both isolated tissues.

CONCLUSION

In both tissues, the order of potency was EtOAc fraction>BuOH fraction>MeOH extract and 1>2>3>4 suggesting that the major iridoids of EtOAc fraction may be considered among the most active compounds. HPLC analysis of the bioactive iridoids indicates that 1 and 2 are present for 7.38% and 14.90% in EtOAc fraction, and 3 and 4 for 18.47% and 8.86% in BuOH fraction. By comparing the values of EC(50) of the fractions and compounds isolated from them, we may assume that the iridoids play a significant role in the biological activity of the corresponding fractions.

Asthma therapy and airway remodeling

Asthma is characterized by variable degrees of chronic inflammation and structural alterations in the airways. The most prominent abnormalities include epithelial denudation, goblet cell metaplasia, subepithelial thickening, increased airway smooth muscle mass, bronchial gland enlargement, angiogenesis, and alterations in extracellular matrix components, involving large and small airways. Chronic inflammation is thought to initiate and perpetuate cycles of tissue injury and repair in asthma, although remodeling may also occur in parallel with inflammation. In the absence of definite evidence on how different remodeling features affect lung function in asthma, the working hypothesis should be that structural alterations can lead to the development of persistent airway hyperresponsiveness and fixed airway obstruction. It is still unanswered whether and when to begin treating patients with asthma to prevent or reverse deleterious remodeling, which components of remodeling to target, and how to monitor remodeling. Consequently, efforts are being made to understand better the effects of conventional anti-inflammatory therapies, such as glucocorticosteroids, on airway structural changes. Animal models, in vitro studies, and some clinical studies have advanced present knowledge on the cellular and molecular pathways involved in airway remodeling. This has encouraged the development of biologicals aimed to target various components of airway remodeling. Progress in this area requires the explicit linking of modern structure-function analysis with innovative biopharmaceutical approaches.

The regulatory role of TGF-beta in airway remodeling in asthma

Both structural and inflammatory cells are capable of secreting transforming growth factor (TGF)-beta and expressing TGF-beta receptors. TGF-beta can induce multiple cellular responses including differentiation, apoptosis, survival and proliferation, and has been implicated in the development of several pathogenic conditions including cancer and asthma. Elevated levels of TGF-beta have been reported in the asthmatic airway. TGF-beta binds to its receptor complex and activates multiple pathways involving proteins such as Sma and Mad homologues, phosphatidylinositol-3 kinase and the mitogen-activated protein kinases, leading to the transcription of several genes. Cell type, cellular condition, and microenvironment, all play a role in determining which pathway is activated, which, in turn, is an indication of which gene is to be transcribed. TGF-beta has been shown to induce apoptosis in airway epithelial cells. A possible role for TGF-beta in the regulation of epithelial cell adhesion properties has also been reported. Enhancement of goblet cell proliferation by TGF-beta suggests a role in mucus hyper-secretion. Elevated levels of TGF-beta correlate with subepithelial fibrosis. TGF-beta induces proliferation of fibroblast cells and their differentiation into myofibroblasts and extracellular matrix (ECM) protein synthesis during the development of subepithelial fibrosis. TGF-beta also induces proliferation and survival of and ECM secretion in airway smooth muscle cells (ASMCs), suggesting a possible cause of increased thickness of airway tissues. TGF-beta also induces the production and release of vascular endothelial cell growth factor and plasminogen activator inhibitor, contributing to the vascular remodeling in the asthmatic airway. Blocking TGF-beta activity inhibits epithelial shedding, mucus hyper-secretion, angiogenesis, ASMC hypertrophy and hyperplasia in an asthmatic mouse model. Reduction of TGF-beta production and control of TGF-beta effects would be beneficial in the development of therapeutic intervention for airway remodeling in chronic asthma.

Antagonism of IL-4 signaling by a phosphodiesterase-4 inhibitor, rolipram, in human T cells

BACKGROUND

Phosphodiesterase (PDE4) inhibitors prevent breakdown of cAMP and affect the increase in cellular levels of cAMP, which is known to regulate immune cell functions. Because IL-4 plays a causal role in the pathogenesis of allergic disorders, we were interested to study the modulatory mechanisms of a PDE4 inhibitor, rolipram, in IL-4-mediated signaling in T cells.

METHODS

Human peripheral T cells were stimulated with IL-4 in combination with rolipram, and RT-PCR was performed using primers specific for IL-5. To monitor activation of transcription factors, immunostaining was employed.

RESULTS

Rolipram or a cAMP-analogue, 8-Br-cAMP, significantly downregulated IL-4-induced expression of IL-5 mRNA. The rolipram-induced inhibition of IL-5 mRNA was mediated by activation of protein kinase A (PKA), because rolipram-downregulated mRNA expression of IL-5 was restored by PKA inhibitors. Immunostaining revealed that rolipram interfered with IL-4-induced nuclear translocation of activator protein (AP)-1 components.

CONCLUSIONS

This is the first demonstration of suppression of IL-4 signaling by PDE4 inhibitors via prevention of nuclear translocation of AP-1.

Targeting signal transduction as a strategy to treat inflammatory diseases

Inflammatory diseases are a major burden on humanity, despite recent successes with biopharmaceuticals. Lack of responsiveness and resistance to these drugs, delivery problems and cost of manufacture of biopharmaceuticals mean that the search for new anti-inflammatory agents continues. Progress in our understanding of inflammatory signalling pathways has identified new targets, notably in pathways involving NF-kappaB, p38 MAP kinase, T lymphocyte activation and JAK/STAT. Other targets such as transcription factor complexes and components of pathways activated by TNF, Toll-like receptors and Nod-like receptors also present possibilities, and might show efficacy without being limited by effects on host defence. The challenge is to place a value on one target relative to another, and to devise strategies to modulate them.

Molecular mechanisms for the release of chemokines from human leukemic mast cell line (HMC)-1 cells activated by SCF and TNF-alpha: roles of ERK, p38 MAPK, and NF-kappaB

BACKGROUND

Mast cells play pivotal roles in IgE-mediated airway inflammation and other mast cell-mediated inflammation by activation and chemoattraction of inflammatory cells.

OBJECTIVE

We investigated the intracellular signaling mechanisms regulating chemokine release from human mast cell line-1 (HMC-1) cells activated by stem cell factor (SCF) or tumor necrosis factor (TNF)-alpha.

METHODS

Chemokine gene expressions were assessed by reverse transcription-polymerase chain reaction, while the releases of chemokines were determined by flow cytometry or enzyme-linked immunosorbent assay (ELISA). To elucidate the intracellular signal transduction regulating the chemokine expression, phosphorylated-extracellular signal-regulated kinase (ERK), phosphorylated-p38 mitogen-activated protein kinase (MAPK) and nuclear translocated nuclear factor (NF)-kappaB-DNA binding were quantitatively assessed by ELISA.

RESULTS

Either SCF or TNF-alpha could induce release from HMC-1 cells of interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1, regulated upon activation normal T-cell expressed and secreted (RANTES), and I-309, while SCF and TNF-alpha induced release of macrophage inflammatory protein (MIP)-1beta and interferon-gamma-inducible protein-10 (IP-10), respectively. Using various selective inhibitors for signaling molecules, we found that the inductions of IL-8, MCP-1, and I-309 were mediated by either SCF-activated ERK or TNF-alpha-activated p38 MAPK, while the induction of IP-10 by TNF-alpha was mediated by both activated p38 MAPK and NF-kappaB. The induction of RANTES by SCF or TNF-alpha was mediated by ERK and NF-kappaB, respectively, and SCF induced MIP-1beta release was mediated by ERK.

CONCLUSION

The above results therefore elucidated the different intracellular signaling pathways regulating the release of different chemokines from SCF and TNF-alpha-activated mast cells, thereby shedding light for the immunopathological mechanisms of mast cell-mediated diseases.

Peroxisome proliferator-activated receptor gamma agonists as therapy for chronic airway inflammation

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily. PPARgamma regulates several metabolic pathways by binding to sequence-specific PPAR response elements in the promoter region of target genes, including lipid biosynthesis and glucose metabolism. Synthetic PPARgamma agonists have been developed, such as the thiazolidinediones rosiglitazone and pioglitazone. These act as insulin sensitizers and are used in the treatment of type 2 diabetes. Recently however, PPARgamma ligands have been implicated as regulators of cellular inflammatory and immune responses. They are thought to exert anti-inflammatory effects by negatively regulating the expression of pro-inflammatory genes. Several studies have demonstrated that PPARgamma ligands possess anti-inflammatory properties and that these properties may prove helpful in the treatment of inflammatory diseases of the airways. This review will outline the anti-inflammatory effects of synthetic and endogenous PPARgamma ligands and discuss their potential therapeutic effects in animal models of inflammatory airway disease.

Agents against cytokine synthesis or receptors

Various cytokines play a critical role in pathophysiology of chronic inflammatory lung diseases including asthma and chronic obstructive pulmonary disease (COPD). The increasing evidence of the involvement of these cytokines in the development of airway inflammation raises the possibility that these cytokines may become the novel promising therapeutic targets. Studies concerning the inhibition of interleukin (IL)-4 have been discontinued despite promising early results in asthma. Although blocking antibody against IL-5 markedly reduces the infiltration of eosinophils in peripheral blood and airway, it does not seem to be effective in symptomatic asthma, while blocking IL-13 might be more effective. On the contrary, anti-inflammatory cytokines themselves such as IL-10, IL-12, IL-18, IL-23 and interferon-gamma may have a therapeutic potential. Inhibition of TNF-alpha may also be useful in severe asthma or COPD. Many chemokines are also involved in the inflammatory response of asthma and COPD through the recruitment of inflammatory cells. Several small molecule inhibitors of chemokine receptors are now in development for the treatment of asthma and COPD. Antibodies that block IL-8 reduce neutrophilic inflammation. Chemokine CC3 receptor antagonists, which block eosinophil chemotaxis, are now in clinical development for asthma therapy. As many cytokines are involved in the pathophysiology of inflammatory lung diseases, inhibitory agents of the synthesis of multiple cytokines may be more useful tools. Several such agents are now in clinical development.

Isoquercitrin from Argemone platyceras inhibits carbachol and leukotriene D4-induced contraction in guinea-pig airways

Argemone platyceras is used in Mexico as a remedy for cough, bronchitis and pneumonia. The present study was performed to investigate the pharmacological anti-asthmatic properties of Argemone platyceras on airways and to identify its active principles. Methanol extracts of leaves and flowers, subsequent organic and aqueous extraction phases, and silica gel chromatography fractions were assayed on the carbachol-induced response, and/or on ovalbumin antigenic challenge, and on leukotriene D(4)-induced response of tracheae from sensitized and non-sensitized guinea-pigs. Methanol extracts, ethyl-acetate phase, and its fractions 6 and 7 inhibited the carbachol-induced contractile response. Isoquercitrin and rutin were the main compounds found in fractions 6 and 7 respectively. Isoquercitrin (fraction 6) abolished the response to ovalbumin, and decreased the contractile response to leukotriene D(4). Because of its effect on carbachol-induced contractile response, on the late-phase response to ovalbumin, and on leukotriene D(4)-induced contractile response, isoquercitrin might be highly useful in treatment of asthma.