Asthma: new developments in cytokine regulation

Dendritic cell-CD4+ T cell interaction: The differential role of IL-4/IL-13 in serum IgE levels in house dust mite allergic patients

Allergic asthma is a chronic airway inflammatory disorder triggered by inhalant allergens. Interleukin (IL)-4 and IL-13 play a main role in the generation of T helper cell type 2 (Th2) immune response, induction of immunoglobulin E (IgE) synthesis and persistence of airway inflammation. The aim of the present study was to investigate the influence of Dermatophagoides pteronyssinus allergen Der p 1, the major allergen of house dust mite, on the synthesis of IL-4 and IL-13 by monocyte-derived dendritic cells (DCs) and naive CD4+ T cells cocultured with DCs, as well as their role in the production of serum IgE, in house dust mite (HDM) allergic patients. Peripheral blood mononuclear cells (PBMCs) were isolated from venous blood of patients allergic to HDM and healthy donors and incubated with granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-4 to generate immature DCs. The obtained cells were stimulated for 24 h with Der p 1 to induce DC maturation, washed, and afterwards cocultured for 24 h with autologous naive CD4+ T cells. Culture supernatants were harvested for IL-4, IL-13 and IFN-γ level measurements. DCs stimulation with Der p 1 induced higher synthesis of IL-4 and IL-13 in HDM allergic patients, compared to healthy donors. The allergic group showed significant correlation between IL-13 production by Der p 1-pulsed DCs, and total serum IgE and IL-4 production of the same cells and Der p-specific IgE. To conclude, IL-4 and IL-13 are critically related to the regulation of serum IgE production in patients with allergic asthma. The relevance of these two cytokines in the pathophysiology of Th2 asthma endotype makes them an appropriate target in its management.

β-eudesmol suppresses allergic reactions via inhibiting mast cell degranulation

The regulatory effect of β-eudesmol, which is an active constituent of Pyeongwee-San (KMP6), is evaluated for allergic reactions induced by mast cell degranulation. Phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore A23187-stimulated human mast cell line, HMC-1 cells, and compound 48/80-stimulated rat peritoneal mast cells (RPMCs) are used as the in vitro models; mice models of systemic anaphylaxis, ear swelling, and IgE-dependent passive cutaneous anaphylaxis (PCA) are used as the in vivo allergic models. The results demonstrate that β-eudesmol suppressed the histamine and tryptase releases from the PMA plus calcium ionophore A23187-stimulated HMC-1 cells. β-eudesmol inhibits the expression and activity of histidine decarboxylase in the activated HMC-1 cells. In addition, β-eudesmol inhibits the levels of histamine and tryptase released from the compound 48/80-stimulated RPMCs. Furthermore, β-eudesmol decreases the intracellular calcium level in the activated RPMCs. β-eudesmol also decreases the compound 48/80-induced mortality and ear swelling response. β-eudesmol suppresses the serum levels of histamine, IgE, interleukin (IL)-1β, IL-4, IL-5, IL-6, IL-13, and vascular endothelial growth factor (VEGF) under PCA mice as well as PCA reactions. Therefore, the results from this study indicate the potential of β-eudesmol as an anti-allergic drug with respect to its pharmacological properties against mast cell-mediated allergic reactions.

Rosmarinic Acid Attenuates Airway Inflammation and Hyperresponsiveness in a Murine Model of Asthma

Rosmarinic acid (RA) has numerous pharmacologic effects, including anti-oxidant, anti-inflammatory, and analgesic effects. This study aimed to evaluate the preventive activity of RA in a murine model of asthma and to investigate its possible molecular mechanisms. Female BALB/c mice sensitized and challenged with ovalbumin (Ova) were pretreated with RA (5, 10 or 20 mg/kg) at 1 h before Ova challenge. The results demonstrated that RA markedly inhibited increases in inflammatory cells and Th2 cytokines in the bronchoalveolar lavage fluid (BALF), significantly reduced the total IgE and Ova-specific IgE concentrations, and greatly ameliorated airway hyperresponsiveness (AHR) compared with the control Ova-induced mice. Histological analyses showed that RA substantially decreased the number of inflammatory cells and mucus hypersecretion in the airway. In addition, our results suggested that the protective effects of RA might be mediated by the suppression of ERK, JNK and p38 phosphorylation and activation of nuclear factor-κB (NF-κB). Furthermore, RA pretreatment resulted in a noticeable reduction in AMCase, CCL11, CCR3, Ym2 and E-selectin mRNA expression in lung tissues. These findings suggest that RA may effectively delay the progression of airway inflammation.

Dihydroartemisinin suppresses ovalbumin-induced airway inflammation in a mouse allergic asthma model

Asthma is a complex disease characterized by reversible airway obstruction, airway hyper-responsiveness (AHR) and chronic inflammation of the airways. Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin isolated from the traditional Chinese herb Artemisia annua, has been shown to possess antimalarial and antitumor activities, but whether it can be used in asthma treatment has not been investigated. In this study, we attempted to determine whether DHA regulates inflammatory mediators in the ovalbumin (OVA)-induced mouse asthma model. BALB/c mice were sensitized and challenged by OVA to induce chronic airway inflammation. The intragastrical administration of DHA at 30 mg/kg significantly decreased the number of infiltrating inflammatory cells, T-helper type 2 (Th2) cytokines, OVA-specific immunoglobulin E (IgE) and AHR. Treatment with DHA also attenuated OVA-induced mRNA expression of Muc5ac and chitinase 3-like protein 4 (Ym2) in lung tissues. In addition, lung histopathological studies revealed that DHA inhibited inflammatory cell infiltration and mucus hypersecretion. Then signal transduction studies showed that DHA significantly inhibited extracellular signal-regulated protein kinase (ERK), p38 mitogen-activated protein kinase phosphorylation. DHA also inhibited nuclear factor-κB (NF-κB) activation via the inhibition of phosphorylation of IκBα. These findings provide new insight into the immunopharmacological role of DHA in terms of its effects in a mouse model of asthma.

The immune response and its therapeutic modulation in bronchiectasis

Bronchiectasis (BC) is a chronic pulmonary disease with tremendous morbidity and significant mortality. As pathogen infection has been advocated as a triggering insult in the development of BC, a central role for the immune response in this process seems obvious. Inflammatory cells are present in both the airways as well as the lung parenchyma, and multiple mediators of immune cells including proteases and cytokines or their humoral products are increased locally or in the periphery. Interestingly, a defect in the immune system or suppression of immune response during conditions such as immunodeficiency may well predispose one to the devastating effects of BC. Thus, the outcome of an active immune response as detrimental or protective in the pathogenesis of BC may be dependent on the state of the patient's immunity, the severity of infection, and the magnitude of immune response. Here we reassess the function of the innate and acquired immunity in BC, the major sites of immune response, and the nature of the bioactive mediators. Furthermore, the potential link(s) between an ongoing immune response and structural alterations accompanying the disease and the success of therapies that can modulate the nature and extent of immune response in BC are elaborated upon.

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.

Suppression of ovalbumin-induced Th2-driven airway inflammation by β-sitosterol in a guinea pig model of asthma

In the present study, the efficacy of β-sitosterol isolated from an n-butanol extract of the seeds of the plant Moringa oleifera (Moringaceae) was examined against ovalbumin-induced airway inflammation in guinea pigs. All animals (except group I) were sensitized subcutaneously and challenged with aerosolized 0.5% ovalbumin. The test drugs, β-sitosterol (2.5mg/kg) or dexamethasone (2.5mg/kg), were administered to the animals (p.o.) prior to challenge with ovalbumin. During the experimental period (on days 18, 21, 24 and 29), a bronchoconstriction test (0.25% acetylcholine for 30s) was performed and lung function parameters (tidal volume and respiration rate) were measured for each animal. On day 30, blood and bronchoalveolar lavaged fluid were collected to assess cellular content, and serum was collected for cytokine assays. Lung tissue was utilized for a histamine assay and for histopathology. β-sitosterol significantly increased the tidal volume (V(t)) and decreased the respiration rate (f) of sensitized and challenged guinea pigs to the level of non-sensitized control guinea pigs and lowered both the total and differential cell counts, particularly eosinophils and neutrophils, in blood and bronchoalveolar lavaged fluid. Furthermore, β-sitosterol treatment suppressed the increase in cytokine levels (TNFα, IL-4 and IL-5), with the exception of IL-6, in serum and in bronchoalveolar lavaged fluid detected in model control animals. Moreover, treatment with β-sitosterol protected against airway inflammation in lung tissue histopathology. β-sitosterol possesses anti-asthmatic actions that might be mediated by inhibiting the cellular responses and subsequent release/synthesis of Th2 cytokines. This compound may have therapeutic potential in allergic asthma.

Role played by Th2 type cytokines in IgE mediated allergy and asthma

OBJECTIVE

Recent evidence suggest that allergen type 2 helper T cells (Th2) play a triggering role in the activation/recruitment of IgE antibody producing B cells, mast cells and eosinophils. Reduced microbial exposure in early life is responsible for a shift of Th1/Th2 balance in the immune system towards the pre-allergic Th2 response. The Th1 predominantly produce IFNgamma and delayed type hypersensitivity while Th2 secrete IL-4, IL-5, IL-6, IL-13 and regulate B cell and eosinophil mediated responses. To assess regulatory changes in the immune system, in patients with allergy and asthma, we studied the cytokine profile in serum in comparison with normal healthy controls.

PATIENTS AND METHODS

A total of 170 patients with various allergies and asthmatic conditions were studied, for cytokines in the serum by ELISA using kits from Immunotech, and analyzed to identify the triggering factors or main contributors towards allergy and asthma.

RESULTS

Our study showed increase in the levels of IL-4, IL-5 and IL-6 in all groups which were non- significant. But the levels of IL-10, IL-13 and TNF alpha were highly significant. Besides, we found correlation of GM-CSF with IL-10. Significant correlation with different cytokines was observed. Most of these patients showed increase in IgE levels.

CONCLUSIONS

This study gives a better understanding of how cytokines are the mediators of balance of Th1 and Th2 immune responses and IgE synthesis is controlled by cytokines. Further studies will eventually lead to improved treatment strategies in the clinical management of IgE mediated allergy.

Effects of umbelliferone in a murine model of allergic airway inflammation

The therapeutic effects of umbelliferone (30, 60 and 90 mg/kg), a coumarin isolated from Typha domingensis (Typhaceae) were investigated in a mouse model of bronchial asthma. BALB/c mice were immunized and challenged by nasal administration of ovalbumin. Treatment with umbelliferone (60 and 90 mg/kg) caused a marked reduction of cellularity and eosinophil numbers in bronchoalveolar lavage fluids from asthmatic mice. In addition, a decrease in mucus production and lung inflammation were observed in mice treated with umbelliferone. A reduction of IL-4, IL-5, and IL-13, but not of IFN-gamma, was found in bronchoalveolar lavage fluids of mice treated with umbelliferone, similar to that observed with dexamethasone. The levels of ovalbumin-specific IgE were not significantly altered after treatment with umbelliferone. In conclusion, our results demonstrate that umbelliferone attenuates the alteration characteristics of allergic airway inflammation. The investigation of the mechanisms of action of this molecule may contribute for the development of new drugs for the treatment of asthma.

The triterpenoid lupeol attenuates allergic airway inflammation in a murine model

Asthma is a chronic inflammatory disease of the airways associated with a Th2 immune response. Despite their side effects, corticosteroids are the most used and effective drugs for treatment of asthma. In this work we investigated the efficacy of lupeol, a triterpenoid isolated from Lonchocarpus araripensis [corrected] Benth. (Fabaceae), in the treatment of bronchial asthma in BALB/c mice immunized with ovalbumin. Administration of lupeol caused the reduction of cellularity and eosinophils in the bronchoalveolar lavage fluid. Treatment with lupeol also reduced the production of mucus and overall inflammation in the lung. Levels of Type II cytokines IL-4, IL-5 and IL-13 were significantly reduced in mice treated with lupeol, an effect that was similar to that observed in dexamethasone-treated mice. In contrast, IgE production was not significantly altered after treatment with lupeol. In conclusion, our results demonstrate that lupeol attenuates the alterations' characteristics of allergic airway inflammation. The investigation of the mechanisms of action of this molecule may contribute for the development of new drugs for the treatment of asthma.

Inflammatory process of CD8+ CD28- T cells in induced sputum from asthmatic patients

Previously unreported CD8⁺CD28⁻ and CD8⁺CD28⁺ T-cell subsets occur in healthy individuals and expand in patients suffering from autoimmune disease. Here we studied, for the first time, the expression of CD8⁺CD28⁺, CD8⁺CD28⁻, and CD8⁺CD56⁺ subpopulations in induced sputum from asthmatics. Using sputum samples, purified CD8⁺ T cells were stained for surface antigen CD28, CD56, FITC-conjugated anti-perforin, and anti-IFN-γ. Cytotoxic activity was evaluated in a chromium releasing test. Induced sputum CD8⁺CD28⁻ T cells were found to be more expanded and expressed low levels of IFN-γ in severe asthmatics than mild asthma and age-matched healthy controls. The predominance of CD8⁺CD28⁻ T cells can be in part explained by the expansion of CD8⁺CD56⁺. CD8⁺CD28⁻ T cells from severe asthmatics produced high intracytoplasmic perforin and exerted a potent cytotoxic activity. Considering their phenotyping and functional properties, the CD8⁺CD28⁻ T-cell subset may constitute an intermediate phenotype in the process of CD8⁺ T-cell differentiation of effector-type cells in severe asthmatics. Functional studies showed that CD8⁺CD28⁻ T cells had cytotoxic function.

Complement components (C3, C4) in childhood asthma

OBJECTIVE

To assess the involvement of complements (C3, C4) in the pathophysiology of bronchial asthma.

METHODS

Selection of patients (n = 64) were made according to the recommended international criteria for diagnosis and classification of asthma. Serum levels of complement components (C3, C4) were measured by radial immunodiffusion technique in 64 Libyan children (age: 1-12 years, sex: 39 males, 25 females) with mild to moderately severe asthma (Group A). Among these patients, 35 had active disease (AA) and 29 had inactive disease (NA). According to age range, 20, 21 and 23 patients were between 1-3 years (A1), > 3-5 years (A2) and > 5-12 years (A3) respectively. A1 had 9 and 11 patients with active (AA1) and inactive (NA1) disease; A2 had 10 and 11 patients with active (AA2) and inactive (NA2) disease; A3 had 16 and 7 patients with active (AA3) and inactive (NA3) disease respectively. Age matched comparisons were made with 57 healthy children (age: 1-12 years; sex: 30 males, 27 females) (Group B). Among the controls, 15, 19 and 23 children were between 1-3 years (B1), > 3-5 years (B2) and > 5-12 years (B3) respectively.

RESULTS

Mean C3 level was significantly elevated in patients, while C4 level was normal (A vs B --> C3: P < 0.2, C4: P > 0.2). Serum C3 level was significantly higher in patients with active disease only, while it was normal in patients with inactive disease (AA, NA, B --> P = 0.045); AA vs NA --> P < 0.05, AA vs B --> P < 0.02, NA vs B --> P > 0.05) and C4 levels were normal in both the groups (AA, NA, B --> P = 0.354). Further, C3 levels were significantly elevated in all the age groups, but in patients with active disease only (AA1, NA1, B1 --> P = 0.0024; AA2, NA2, B2 --> P = 0.0411; AA3, NA3, B3 --> P = 0.0102).

CONCLUSION

The elevated C3 level was possibly due to induction by pro-inflammatory cytokines such as tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1). The probable mechanisms of C3 involvement in the pathophysiology of bronchial asthma were discussed.