Advances in immunopharmacology of asthma

A new method to evaluate anti-allergic effect of food component by measuring leukotriene B4 from a mouse mast cell line

Leukotrienes (LTs), chemical mediators produced by mast cells, play an important role in allergic symptoms such as food allergies and hay fever. We tried to construct an evaluation method for the anti-LTB₄ activity of chemical substances using a mast cell line, PB-3c. PB-3c pre-cultured with or without arachidonic acid (AA) was stimulated by calcium ionophore (A23187) for 20 min, and LTB₄ production by the cells was determined by HPLC with UV detection. LTB₄ was not detected when PB-3c was pre-cultured without AA. On the other hand, LTB₄ production by PB-3c pre-cultured with AA was detectable by HPLC, and the optimal conditions of PB-3c for LTB₄ detection were to utilize the cells pre-cultured with 50 µM AA for 48 h. MK-886 (5-lipoxygenase inhibitor) completely inhibited LTB₄ production, but AACOCF₃ (phospholipase A₂ inhibitor) slightly increased LTB₄ production, suggesting that LTB₄ was generated from exogenous free AA through 5-lipoxygenase pathway. We applied this technique to the evaluation of the anti-LTB₄ activity of food components. PB-3c pre-cultured with 50 µM AA for 48 h was stimulated with A23187 in the presence of 50 µM soybean isoflavones (daidzin, genistin, daidzein, and genistein), equol, quercetin, or kaempferol. Genistein, equol, quercetin, and kaempferol strongly inhibited LTB₄ production without cytotoxicity. These results suggest that a new assay system using PB-3c is convenient to evaluate LTB₄ inhibition activity by food components. This method could be utilized for elucidation of the mechanisms of LTB₄ release suppression by food components such as flavonoids and the structure-activity relationship.

Investigation into the mechanism of action of essential oil of Pistacia integerrima for its antiasthmatic activity

ETHNOPHARMACOLOGICAL RELEVANCE

Pistacia integerrima J.L. Stewart ex Brandis locally known as Karkatashringi is an important medicinal plant whose galls are valued in traditional medicine used in India for the treatment of asthma, chronic bronchitis, phthisis, diarrhea, fever, other ailments for the respiratory tract, and as antispasmodic, carminative, antiamoebic and anthelmintic. However, in vitro and in vivo investigations providing new insights into its pharmacological properties have not been thoroughly investigated yet. The present investigation aimed to elucidate the probable mechanism of antiasthmatic action of essential oil of Pistacia integerrima J.L. Stewart ex Brandis galls (EOPI).

METHODS

EOPI was tested using in vitro studies such as antioxidant activity, mast cell degranulation, angiogenesis, isolated guinea pig ileum preparation and soyabean lipoxidase enzyme activity. In vivo studies included lipopolysaccharide-induced bronchial inflammation in rats and airway hyperresponsiveness in ovalbumin in sensitized guinea pigs using spirometry.

RESULTS

EOPI (5-30 µg/ml) inhibits 5-lipoxidase enzyme activity with IC50 of 19.71 µg/ml and DPPH scavenging activity up to 100 µg/ml with maximum inhibition of 44.93 ± 2.53% at 100 µg/ml. Pre-treatment with EOPI inhibited erythropoietin-induced angiogenesis. It showed dose dependent (10, 30 and 100 µg/ml) anti-allergic activity by inhibiting compound 48/80 induced mast cell degranulation to an extent 19.08 ± 0.47%. The finding that essential oil induced inhibition of transient contraction of acetylcholine in calcium free medium, and relaxation of S-(-)-Bay 8644-precontracted isolated guinea pig ileum jointly suggests that the L-subtype Cav channel is involved in spasmolytic action of EOPI. Treatment with EOPI dose dependently (7.5, 15 and 30mg/kg i.p.) inhibited lipopolysaccharide-induced increase in total cell count, neutrophil count, nitrate-nitrite, total protein, albumin levels in bronchoalveolar fluid and myeloperoxidase levels in lung homogenates. Roflumilast was used as a standard. EOPI reduced the respiratory flow due to gasping in ovalbumin sensitized guinea pigs.

CONCLUSION

The study demonstrates the effectiveness of essential oil of Pistacia integerrima J.L. Stewart ex Brandis galls in bronchial asthma possibly related to its ability to inhibit L-subtype Cav channel, mast cell stabilization, antioxidant, angiostatic and through inhibition of 5-lipoxygenase enzyme.

Regulatory effects of stage-treatment with established Chinese herbal formulas on inflammatory mediators in pediatric asthma

OBJECTIVE

To explore the regulatory effects of established Chinese herbal formulas on inflammatory mediators released during asthma attacks, and to elucidate the molecular mechanism of Traditional Chinese Medicine in the treatment of asthma.

METHODS

Seventy-five asthmatic children were randomly divided into a Chinese medication group (45 cases) and a Western medication control group (30 cases). Patients in the Chinese medication group were treated with a series of established Chinese herbal formulas, whereas the Western medication control group received a leukotriene receptor antagonist and a bronchial relaxant. Real-time PCR was used to determine the mRNA expression levels of interleukin (IL)-4, cysteinyl leukotriene receptor 1 (CysLTR1), and interferon (IFN)-gamma in peripheral blood mononuclear cells before and after treatment. Enzyme-linked immunosorbent assay was used to measure the peripheral blood levels of IL-4, leukotriene (LTE)-4, and INF-gamma before and after treatment.

RESULTS

After treatment, the mRNA expression levels of IL-4 and CysLTR1 were down-regulated (P< 0.01) and the mRNA expression levels of IFN-gamma were up-regulated (P < 0.05) in the Chinese medication and Western medication groups; no significant difference was found between the two groups. In the Chinese medication group, IL-4 blood level was decreased and it was significantly different from that in the Western medication group (P < 0.05); there was also a significant increase in IFN-gamma blood levels after treatment with Chinese medication (P < 0.05). There were no significant differences in LTE-4 blood levels between the two groups before and after treatment (P > 0.05).

CONCLUSION

Chinese medication has a regulatory effect on leukotriene receptor gene expression and the imbalance of Th1/Th2 immune cells during asthma attacks in pediatric patients.

Association of 5-lipoxygenase gene polymorphisms with bronchial asthma

Leukotrienes are important pro-inflammatory mediators in bronchial asthma (BA) and are derived from arachidonic acid by the action of 5-lipoxygenase (5-LO). We investigated the association of 5-LO gene polymorphisms with BA. Thirty-six single-nucleotide polymorphisms (SNPs) of the 5-LO gene, as referenced in the dbSNP gene bank, were analyzed with sequencing and allele-specific PCR (AS-PCR) in genomic DNA from individuals with BA and controls. Of these 36 SNPs, 4 were identified in our study. The c.760 G>A (E254K) (rs2228065) was detected in 15 out of 215 BA patients and 6 out of 212 controls (P<0.05). There were no differences in the frequencies of the other three silent polymorphisms, rs2228064 (c.270 G>A), rs116961353 (c.780G>A) and rs2229136 (c.1728 A>G) between individuals with BA and controls (P>0.05). With our designed primers for AS-PCR, the detection of the 5-LO gene E254K polymorphism was clear and accurate, and the genotype was directly distinguished. Our findings contribute to the evaluation of one of the genetic risk factors for BA and we report an accurate and simple method to rapidly detect the 5-LO E254K polymorphism. It is important to further study the correlation between drug response in BA patients using 5-LO inhibitors with the E254K polymorphism in the clinic.

A potential nanomedicine consisting of heparin-loaded polysaccharide nanocarriers for the treatment of asthma

A new nanomedicine consisting of chitosan/carboxymethyl-β-cyclodextrin loaded with unfractioned or low-molecular-weight heparin is described and its potential in asthma treatment is evaluated. The nanoparticles are prepared by ionotropic gelation showing a size that between 221 and 729 nm with a positive zeta potential. The drug association efficiency is higher than 70%. Developed nanosystems are stable in Hank's balanced salt solution at pH = 6.4, releasing the drug slowly. Ex vivo assays show that nanocarriers lead to an improvement of heparin preventing mast cell degranulation. These results agree with the effective cellular internalization of the fluorescently labeled nanocarriers, and suggest these nanomedicines as promising formulations for asthma treatment.

Atractylodes japonica Koidzumi inhibits the production of proinflammatory cytokines through inhibition of the NF-kappaB/IkappaB signal pathway in HMC-1 human mast cells

The rhizome of Atractylodes japonica Koidzumi (AJK) has been used in traditional medicine for treatment of arthritis, bronchitis and respiratory infectious disease, whereas its effects on inflammatory reactions have not been unknown recently. In this study, the effects of AJK on allergic inflammation and its signaling were investigated in the induced human mast cells and animal model. This study showed that ethanol extract of AJK interestingly suppressed the production and mRNA expression of TNF-alpha, IL-6 and IL-8, as important inflammatory cytokines. Furthermore, AJK inhibited the nuclear translocation of nuclear factor (NF)-kappaB through inhibition of the phosphorylation of IB-kappa, which was additionally elucidated by NF-kappaB promoter-mediated luciferase activity. In addition, the phosphorylation of ERK was increased in pretreatment with AJK, whereas there was no change in JNK and p38 MAPK. However, AJK showed no effects on anti-DNP IgE-mediated in vivo PCA reaction and histamine release, as key events of mast cell-mediated immediate allergic reactions. These results suggest that AJK might be involved in not early-phase but transition to late-phase reactions of allergic inflammation and could modulate through other signal pathways. Taken together, AJK could be used as a treatment for mast cell mediated late-phase/chronic allergic inflammatory reactions.

Recent findings on the pathogenesis of bronchial asthma. Part II. The role of hormonal predisposition, environmental influences and conditioning leading to bronchial asthma

In this second part of the review on the pathogenesis of asthma the hormonal factors and adverse external events are shortly reviewed which skew the balance of Th1 vs. Th2 CD4+ lymphocytes towards the latter ones and this way increase the probability of atopic diseases. Among other the role of transplacental priming, insulin, insulin-like and other growth factors, lack of the usual microbial infections in the early childhood (the so-called hygiene hypothesis), gender, diminished testosterone production, gastroesophageal reflux, adverse effects during pregnancy are discussed. A separate chapter deals with the role of central nervous system in the etiology and finally the most common allergizing and airway tissue damaging agents are listed in tabulated form.

Chitosan-hyaluronic acid nanoparticles loaded with heparin for the treatment of asthma

The purpose of this study was to produce mucoadhesive nanocarriers made from chitosan (CS) and hyaluronic acid (HA), and containing the macromolecular drug heparin, suitable for pulmonary delivery. For the first time, this drug was tested in ex vivo experiments performed in mast cells, in order to investigate the potential of the heparin-loaded nanocarriers in antiasthmatic therapy. CS and mixtures of HA with unfractionated or low-molecular-weight heparin (UFH and LMWH, respectively) were combined to form nanoparticles by the ionotropic gelation technique. The resulting nanoparticles loaded with UFH were between 162 and 217 nm in size, and those prepared with LMWH were 152 nm. The zeta potential of the nanoparticle formulations ranged from +28.1 to +34.6 mV, and in selected nanosystems both types of heparin were associated with a high degree of efficiency, which was approximately 70%. The nanosystems were stable in phosphate buffered saline (PBS), pH 7.4, for at least 24h, and released 10.8% of UFH and 79.7% of LMWH within 12h of incubation. Confocal microscopy experiments showed that fluorescent heparin-loaded CS-HA nanoparticles were effectively internalized by rat mast cells. Ex vivo experiments aimed at evaluating the capacity of heparin to prevent histamine release in rat mast cells indicated that the free or encapsulated drug exhibited the same dose-response behaviour.

Histamine affects STAT6 phosphorylation via its effects on IL-4 secretion: role of H1 receptors in the regulation of IL-4 production

Signal Transducer and Activator of Transcription (STAT)-6 is a transcriptional factor activated mainly through the cytokines IL-4 and IL-13 leading to the Th2 cell differentiation. Th2 cells play a role in the etiology and pathogenesis of allergic disease. Histamine alters the Th1/Th2 cytokine balance towards the Th2 cytokine profile and consequently plays a role in allergic diseases and asthma. This study was designed to investigate the effects of histamine on the STAT6 phosphorylation. C57/BL6 splenocytes were pretreated with different concentrations of histamine (10(-)(4) M to 10(-)(13) M) followed by stimulation with PMA+ionomycin or IL-4. The phosphorylated and total basal STAT6 levels were assessed by employing the immunoblotting technique. Histamine caused the hyper-phosphorylation of STAT6. H1 receptor antagonist pyrilamine reversed the effect of histamine on STAT6 phosphorylation. However, H2 receptor antagonist ranitidine and H3/H4 receptor antagonist thioperamide did not affect the histamine mediated hyper-phosphorylation of STAT6. Furthermore, H1 receptor agonist betahistine enhanced the phosphorylation of STAT6 whereas H2 receptor agonist amthamine did not affect the phosphorylation STAT6. Furthermore, tyrosine kinase inhibitor, tyrphostin, inhibited the histamine mediated phosphorylation of STAT6 when stimulated with PMA+ionomycin. The effects of histamine on the STAT6 phosphorylation were indirect since they were blocked either by the antibodies to IL-4 and IL-13 or in IL-4 knock out mice in the presence of IL-13 antibody. These observations suggest that histamine indirectly affected the STAT6 phosphorylation via its effects on the secretion of cytokines (IL-4) and H1 receptor played a role in this process.

Role of H1 receptors in histamine-mediated up-regulation of STAT4 phosphorylation

Histamine shifts TH1/TH2 cytokine balance from TH1 to TH2 cytokines and regulates the function of lymphocytes after binding to histamine receptors. The phosphorylation of STAT factors and the translocation to the nucleus are important steps in the regulation of TH1/TH2 cytokine balance. This study was designed to investigate the effects of histamine on the phosphorylation of STAT4. C57BL/6 splenocytes were isolated and treated with histamine (10(-4) to 10(-9) M) after activation with either PMA (phorbol 12 myristate 13-acetate) plus ionomycin or IL-12. The phosphorylated STAT4 levels were analyzed by Western Blot Analysis. Unstimulated splenocytes expressed both STAT4 and phosphorylated STAT4. However, phosphorylated STAT4 gradually declined within 24 h. Histamine increased the phosphorylation of STAT4 at lower concentrations (10(-6) to 10(-9) M), and had no effect at higher concentrations (10(-4) and 10(-5) M) after the cells were stimulated with PMA + ionomycin. Histamine did not affect IL-12-induced phosphorylation of STAT4. To characterize the histamine receptor subtypes involved in the up-regulation of STAT4 phosphorylation, various H1, H2 and H3/H4 receptor antagonists and/or agonists were employed. H1 receptor agonist (betahistine), but not H2 receptor agonist (amthamine), induced phosphorylation of STAT4. H1 receptor antagonist (pyrilamine) inhibited histamine-mediated phosphorylation of STAT4. However, H2 receptor antagonist (ranitidine) and H3/H4 receptor antagonist (thioperamide) did not alter this effect. Tyrosine kinase inhibitor (tyrphostin) failed to block histamine-mediated phosphorylation of STAT4. These observations suggest that histamine up-regulated the phosphorylation of STAT4 via H1 receptors, and that the Ca2+-PKC pathway, but not the tyrosine kinase pathway, was involved in this effect.

Involvement of histamine H1 and H2 receptors in the regulation of STAT-1 phosphorylation: inverse agonism exhibited by the receptor antagonists

Signal transducer and activator of transcription-1 (STAT1) is a latent signal transducer protein which, on phosphorylation, is translocated from the cytoplasm to the nucleus and is subsequently activated. This study was designed to determine the involvement of histamine receptors in histamine-mediated effect on STAT1 phosphorylation. It is known that the actions of histamine mediated through H1 and H2 receptors are dependent on their respective downstream pathways, Ca(2+)-PKC and cAMP-PKA. In this study, we investigated the significance of PKA in STAT1 phosphorylation. C57BL/6 mouse splenocytes were isolated and treated with histamine (10(-7)-10(-4) M) and then activated with PMA (phorbol 12 myristate 13-acetate) plus ionomycin. The phosphorylated STAT1 levels were analyzed by immunoblotting. Histamine receptor agonists amthamine and betahistine, histamine receptor antagonists pyrilamine maleate, tripelennamine, ranitidine, cimetidine and thioperamide, cAMP agonists N(6), 2'-0-dibutyryladenosine-3',5'-cyclic monophosphate sodium salt (db-cAMP) and forskolin, protein kinase A inhibitors N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinoline-sulfonamide (H89) and Rp diastereomer of adenosine cyclic 3',5'-phosphorothioate (RpcAMPs) and tyrosine kinase inhibitor tyrphostin were used to identify the upstream signal transduction pathways. We observed that histamine augmented the phosphorylation of STAT1 through both H1 and H2 receptors. Furthermore, H1 and H2 receptor antagonists displayed inverse agonism. Ca(2+)-PKC-induced phosphorylation of STAT1 was completely inhibited by H89 and significantly inhibited by RpcAMPs. DbcAMP and forskolin augmented the Ca(2+)-PKC-induced STAT1 phosphorylation thus suggesting a convergent crosstalk between the two histamine receptor signaling pathways, PKA and PKC.

The role of neurotrophins in bronchial asthma: contribution of the pan-neurotrophin receptor p75

Allergic bronchial asthma is characterized by chronic inflammation of the airways, development of airway hyperreactivity and recurrent reversible airway obstruction. Target and effector cells responsible for airway hyperresponsiveness and airway obstruction include sensory and motor neurons as well as epithelial and smooth muscle cells. Although it is well established that the inflammatory process is controlled by T-helper-2 (Th2) cells, the mechanisms by which immune cells interact with neurons, epithelial cells or smooth muscle cells still remain uncertain. Due to growing evidence for extensive communication between neurons and immune cells, the mechanisms of this neuroimmune crosstalk in lung and airways of asthmatic patients are becoming the focus of asthma research. Neurotrophins represent molecules potentially responsible for regulating and controlling the crosstalk between the immune and peripheral nervous system. They are constitutively expressed by resident lung cells and produced in increasing concentrations by immune cells invading the airways under pathological conditions. Neurotrophins modify the functional activity of sensory and motor neurons, leading to enhanced and altered neuropeptide and tachykinin production. These effects are defined as neuronal plasticity. The consequences are the development of neurogenic inflammation.

Modulation of B lymphocyte function by an aqueous fraction of the ethanol extract of Cissampelos sympodialis Eichl (Menispermaceae)

Cissampelos sympodialis Eichl species are used in folk medicine for the treatment of asthma, arthritis and rheumatism. In the present study, we investigated the immunomodulatory effect of an aqueous fraction of a 70% (v/v) ethanol extract of C. sympodialis leaves on B lymphocyte function. The hydroalcoholic extract inhibited the in vitro proliferative response of resting B cells induced by LPS (IC50 = 17.2 g/ml), anti-delta-dextran (IC50 = 13.9 g/ml) and anti-IgM (IC50 = 24.3 g/ml) but did not affect the anti-MHC class II antibody-stimulated proliferative response of B cell blasts obtained by stimulation with IL-4 and anti-IgM. Incubation with the hydroalcoholic extract used at 50 g/ml induced a 700% increase in intracellular cAMP levels. IgM secretion by resting B cells (obtained from normal mice) and polyclonally activated B cells (obtained from Trypanosoma cruzi-infected animals) was inhibited by the hydroalcoholic extract. The latter were more sensitive to the hydroalcoholic extract since 6.5 g/ml induced a 20% inhibition in the response of cells from normal mice while it inhibited the response of B cells from infected animals by 75%. The present data indicate that the alcoholic extract of C. sympodialis inhibited B cell function through an increase in intracellular cAMP levels. The finding that the hydroalcoholic extract inhibited immunoglobulin secretion suggests a therapeutic use for the extract from C. sympodialis in conditions associated with unregulated B cell function and enhanced immunoglobulin secretion. Finally, the inhibitory effect of the hydroalcoholic extract on B cells may indicate an anti-inflammatory effect of this extract.

Interleukin-4 and 13 concentrations in infants at risk to develop Bronchopulmonary Dysplasia

BACKGROUND

An exaggerated inflammatory response occurs in the first few days of life in infants who subsequently develop bronchopulmonary dysplasia (BPD). The increase of inflammatory cytokines in many disease processes is generally balanced by a rise in anti-inflammatory cytokines. Interleukin-4 (IL-4) and interleukin-13 (IL-13) have been shown to inhibit production of several inflammatory cytokines important in the development of BPD.

METHODS

We sought to determine if a correlation exists between the presence or absence of IL-4 and IL-13 in tracheal aspirates (TA) during the first 3 weeks of life and the development of BPD in premature infants. Serial TAs were prospectively obtained from 36 very low birth weight infants and IL-4 and IL-13 concentrations were determined by ELISA.

RESULTS

Infants who developed BPD (n = 19) were less mature (25.3 +/- 0.02 wks vs. 27.8 +/- 0.05 wks; p < 0.001), and had lower birth weights (739 +/- 27 g vs.1052 +/- 41 g; p < 0.001). IL-4 and IL-13 were detectable in only 27 of 132 and 9 of 132 samples assayed respectively. Furthermore, the levels detected for IL-4 and IL-13 were very low and did not correlate with the development of BPD.

CONCLUSIONS

TA concentrations of IL-4 and IL-13 do not increase significantly during acute lung injury in premature infants.

3D-QSAR studies on thieno[3,2-d]pyrimidines as phosphodiesterase IV inhibitors

Cyclic nucleotide phosphodiesterase IV (PDE IV) inhibitors find utility in asthma and Chronic Obstructive Pulmonary Disease (COPD) therapy. A series of 29 thieno[3,2-d]pyrimidines with affinity for PDE IV was subjected to three dimensional quantitative structure activity relationship (3D-QSAR) studies using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Both CoMFA and CoMSIA provided statistically valid models with good correlative and predictive power. The incorporation of hydrophobic, hydrogen bond donor and hydrogen bond acceptor fields showed insignificant improvement in CoMSIA model. The 3D-QSAR models provide information for predicting the affinity of related compounds and designing more potent inhibitors.

What's in the pipeline? Prospects for monoclonal antibodies (mAbs) as therapies for lung diseases

The striking clinical results from recent studies with Remicade (infliximab, a monoclonal anti-TNFalpha antibody) in rheumatoid arthritis, Crohn's disease and psoriasis demonstrate the disease-altering potential of monoclonal antibodies (mAbs) in chronic inflammation. Chronic obstructive pulmonary disease (COPD) and asthma represent two major chronic pulmonary inflammatory diseases with substantial unmet medical needs. Most of the cells and mediators implicated in the pathophysiology of COPD and asthma are excellent targets for mAb intervention. Indeed, clinical trials with mAbs directed against IL-5, IgE, and CD4 yielded results that are critical in dissecting the pathophysiology of asthma, and reinforce the potential for mAbs as therapeutic agents in treating pulmonary diseases. Furthermore, fundamental advances in the discovery, manufacture and safety of mAbs underscore the enormous therapeutic value of these agents for chronic pulmonary diseases. Indeed, a large number of mAbs are in pre-clinical and clinical development for treating these conditions. In this review, we discuss the scientific rationale for generating mAb therapies directed specifically toward COPD and asthma. We believe that as a therapeutic class, mAbs offer the opportunity to alter symptoms, progression and outcome of chronic pulmonary diseases.

Antiinflammatory effects of genistein, a tyrosine kinase inhibitor, on a guinea pig model of asthma

Protein tyrosine kinase signaling cascade plays a pivotal role in the activation of inflammatory cells. The purpose of this study was to investigate the effects of genistein, a broad-spectrum protein tyrosine kinase inhibitor, on airway inflammation in an in vivo guinea pig model of asthma. Guinea pigs were actively sensitized by intraperitoneal injections of ovalbumin. Aerosolized ovalbumin induced acute bronchoconstriction in conscious animals in a dose-dependent manner. Genistein (15 mg/kg given intraperitoneally) markedly inhibited ovalbumin-induced, but not histamine- and methacholine-induced, acute bronchoconstriction. In addition, genistein significantly reduced ovalbumin-induced increases in total cell counts and eosinophils recovered in bronchoalveolar lavage fluid, airway eosinophilia, and eosinophil peroxidase activity in cell-free bronchoalveolar lavage fluid and markedly attenuated ovalbumin-induced airway hyperresponsiveness to inhaled methacholine. Immunoblot analysis of lung lysates isolated from genistein-pretreated animals showed that epidermal growth factor-induced tyrosine phosphorylation in lung tissues was inhibited by genistein. These results implicate that inhibition of tyrosine kinase signaling cascade may have therapeutic potential for allergic airway inflammation.

Overexpression of IL-4 alters the homeostasis in the skin

IL-4 has been implicated to play an important role in the pathogenesis of many inflammatory diseases including skin diseases such as atopic dermatitis. Because it is not clear which pathologic features of atopic dermatitis are dependent on IL-4, we assessed the consequences of IL-4 overexpression in the skin, using transgenic mice overexpressing IL-4 ubiquitously. Although transgenic mice display no clinical signs of skin inflammation, IL-4 induced a wide spectrum of pathologies including an increased number of mast cells and Langerhans cells in dermis and epidermis, respectively, focal deposition of collagen and a considerably reduced adipocyte layer in the dermis as well as an increased mitotic activity of keratinocytes, reflected in acanthosis and hyperkeratosis. The increase in Langerhans cell number may be explained in part by the substantially reduced Langerhans cell emigration from the epidermis in transgenic mice. The molecular mechanism behind this phenomenon remains to be clarified. Under in vitro culture conditions, Langerhans cells from transgenic mice undergo a maturation process similar to that of Langerhans cells from control mice, and their immunostimulatory capacity is also comparable. In contrast, transgenic Langerhans cells are superior to control Langerhans cells in their antigen-processing capacity. We conclude that the overexpression of IL-4 in the skin is, by itself, not sufficient for the induction of a full-blown atopic dermatitis phenotype, but several changes seen in the skin of transgenic mice mirror the cardinal pathologic manifestations of this disease.

IL-13 fusion cytotoxin ameliorates chronic fungal-induced allergic airway disease in mice

IL-13 has emerged as a major contributor to allergic and asthmatic responses, and as such it represents an attractive target in these diseases. In this study, IL-13-responsive cells in the lung were targeted via the intranasal administration of IL-13-PE38QQR (IL-13-PE), comprised of human IL-13 and a derivative of Pseudomonas exotoxin, to Aspergillus fumigatus-sensitized mice challenged with A. fumigatus spores, or conidia. Mice received 50, 100, or 200 ng of IL-13-PE or diluent alone (i.e., control group) on alternate days from day 14 to day 28 after the conidia challenge. The control group of mice exhibited significant airway hyperreactivity, goblet cell hyperplasia, and peribronchial fibrosis at day 28 after conidia. Although the two lower doses of IL-13-PE had limited therapeutic effects in mice with fungal-induced allergic airway disease, the highest dose of IL-13-PE tested significantly reduced all features of airway disease compared with the control group. Whole lung mRNA expression of IL-4Ralpha and IL-13Ralpha1 was markedly reduced, whereas bronchoalveolar lavage and whole lung levels of IFN-gamma were significantly elevated in mice treated with 200 ng of IL-13-PE compared with the control group. This study demonstrates that a therapy designed to target IL-13-responsive cells in the lung ameliorates established fungal-induced allergic airway disease in mice.

The role of neurotrophins in bronchial asthma

Allergic bronchial asthma is characterized by chronic inflammation of the airways, development of airway hyperreactivity and recurrent reversible airway obstruction. Target and effector cells responsible for airway hyperresponsiveness and airway obstruction include sensory and motor neurons as well as epithelial and smooth muscle cells. Although it is well established that the inflammatory process is controlled by T-helper (Th) 2 cells and the Th2-derived cytokines interleukin-4, airway hyperresponsiveness-5 and interleukin-13, the mechanisms by which immune cells interact with neurons, epithelial cells or smooth muscle cells still remain uncertain. Since there is growing evidence for extensive communication between neurons and immune cells, the mechanisms of this neuro-immune crosstalk in lung and airways of asthmatic patients are recently becoming the focus of asthma research. Neurotrophins represent candidate molecules regulating and controlling this crosstalk between the immune and peripheral nervous system. They are constitutively expressed by resident lung cells and produced in increasing concentrations by immune cells invading the airways under pathological conditions. They modify the functional activity of sensory and motor neurons, leading to enhanced and altered neuropeptide and tachykinin production. These effects are defined as "neuronal plasticity". The consequences are the development of "neurogenic inflammation" due to neuropeptide and tachykinin activities.

Treatment strategies for bronchial asthma: an update

Advances in understanding the biomolecular basis of the disease's inflammatory and remodeling responses are offering new therapeutic choices--and sometimes new drug-delivery systems--in categories such as beta-agonists, glucocorticoids, and leukotriene blockers. Meanwhile, researchers are exploring novel targets, including intercellular signals and cell-adhesion and gene-activating molecules.

Asthma: where beyond steroids?

The prevalence of asthma is increasing dramatically despite major changes in monitoring and treatment of this disease. Currently available bronchodilators and anti-inflammatory drugs are effective in most patients, although these can have side effects and are mainly symptomatic. Many drugs are now in development for the treatment of asthma. Most of these new therapies are aimed at inhibition of the inflammatory components, with better safety profiles than steroids.