Gamma-interferon modifies guinea pig airway functions in vitro

Synergistic therapeutic effects of combined adenovirus-mediated interleukin-10 and interleukin-12 gene therapy on airway inflammation in asthmatic mice

BACKGROUND

Asthma is a chronic disease characterized by airway inflammation caused by the dysregulated production of cytokines secreted by allergen-specific type 2 T helper (Th2) cells. Although the Th1-promoting cytokine, interleukin (IL)-12, is capable of inhibiting Th2-driven allergen-induced airway changes in mice, IL-12 also aggravates the Th1-driven inflammatory pulmonary pathology. Further, IL-10 was found to exert both anti-inflammatory and immunoregulatory activities. To avoid the side-effects of IL-12, we hypothesized that the low-dose expression of IL-10 with concomitant IL-12 administration in the airway may represent a more effective therapy for allergic airway diseases. Thus, the present study explored the immunomodulatory and therapeutic effects of IL-10 combined with IL-12 in airway inflammation in allergic asthma.

METHODS

Adenovirus-expressing murine IL-10 (Ad-IL-10) and IL-12 (Ad-IL-12) were co-administrated in an established murine model of ovalbumin (OVA)-induced asthma.

RESULTS

We found that a single combined treatment of low doses of Ad-IL-10 and Ad-IL-12 efficiently inhibited the development of airway hyper-responsiveness compared to Ad-IL-10 or Ad-IL-12 treatment alone. Moreover, both Ad-IL-10 and Ad-IL-12 treatment reduced pulmonary infiltration of eosinophils and neutrophils. In addition, histological studies showed that combined treatment was able to reduce tumor necrosis factor-alpha-mediated airway inflammation induced by IL-12 treatment. Suppression of IL-4, IL-5, Keratinocyte-derived chemokine (KC) and eotaxin in bronchoalveolar lavage fluid was also noted in OVA-immunized mice with combined Ad-IL-10 and Ad-IL-12 treatment.

CONCLUSIONS

Taken together, the results obtained in the present study indicate that co-administration of IL-12 and IL-10 may have therapeutic potential for the immunomodulatory treatment of allergic asthma.

Chitosan Interferon-gamma Nanogene Therapy for Lung Disease: Modulation of T-Cell and Dendritic Cell Immune Responses

The use of chitosan nanoparticles as carriers for expression plasmids represents a major improvement in gene expression technology. We demonstrated previously that treatment with chitosan interferon-γ (IFN-γ) plasmid deoxyribonucleic acid (DNA) nanoparticles (chitosan interferon-γ nanogene [CIN]) led to in situ production of IFN-γ and a reduction in inflammation and airway reactivity in mice, but the mechanism underlying the immunomodulatory effects of CIN remains unclear. In this report, the effect of CIN treatment on the immune responses of CD8⁺ T cells and dendritic cells was examined in a BALB/c mouse model of ovalbumin (OVA)-induced allergic asthma. OT1 mice (OVA-T cell receptor [TCR] transgenic) were also used to test the effects of CIN on OVA-specific CD8⁺ T cells. CIN treatment caused a reduction in IFN-γ production in a subpopulation of OVA-specific CD8⁺ T cells cultured in vitro in the presence of OVA. CIN also reduced apoptosis of the CD8⁺ T cells. Examination of dendritic cells from lung and lymph nodes indicated that CIN treatment decreased their antigen-presenting activity, as evident from the reduction in CD80 and CD86 expression. Furthermore, CIN treatment significantly decreased the number of CD11c⁺b⁺ dendritic cells in lymph nodes, suggesting that endogenous IFN-γ expression may immunomodulate dendritic cell migration and activation. CIN therapy results in a reduction in proinflammatory CD8⁺ T cells and decreases the number and antigen-presenting activity of dendritic cells.

CAT-2 amplifies the agonist-evoked force of airway smooth muscle by enhancing spermine-mediated phosphatidylinositol-(4)-phosphate-5-kinase-gamma activity

We investigated the effect the loss of the CAT-2 gene (CAT-2-/-) has on lung resistance (R(L)) and tracheal isometric tension. The R(L) of CAT-2-/- mice at a maximal dose of acetylcholine (ACh) was decreased by 33.66% (P = 0.05, n = 8) compared with that of C57BL/6 (B6) mice. The isometric tension of tracheal rings from CAT-2-/- mice showed a significant decrease in carbachol (CCh)-induced force generation (33.01%, P < 0.05, n = 8) compared with controls. The isoproterenol- or the sodium nitroprusside-induced relaxation was not affected in tracheal rings from CAT-2-/- mice. The activity of iNOS and arginase in lung tissue lysates of CAT-2-/- mice was indistinguishable from that of B6 mice. Furthermore, the expression of phospholipase-Cbeta (PLC-beta) and phosphatidylinositol-(4)-phosphate-5-kinase-gamma (PIP-5K-gamma) was examined in the lung tissue of CAT-2-/- and B6 mice. The expression of PIP-5K-gamma but not PLC-beta was significantly reduced in CAT-2-/- compared with B6 mice. The reduced airway smooth muscle (ASM) contractility to CCh seen in the CAT-2-/- tracheal rings was completely reversed by pretreating the rings with 100 muM spermine. This increase in the CAT-2-/- tracheal ring contraction upon spermine pretreatment correlated with a recovery of the expression of PIP-5K-gamma. Our data indicates that CAT-2 exerts control over ASM force development through a spermine-dependent pathway that directly correlates with the expression level of PIP-5K-gamma in the lung.

Respiratory syncytial virus replication is prolonged by a concomitant allergic response

Epidemiological studies show an association between early exposure to respiratory syncytial virus (RSV) and the development or exacerbation of asthma. This idea is supported by studies in mice that demonstrate worsened airway hyper-reactivity (AHR) when RSV-infected animals are exposed to allergen. The effect of allergen on RSV disease, however, has not been reported. Cotton rats (Sigmodon hispidus) that have been used as a model to study RSV pathogenesis were sensitized to extracts of Aspergillus fumigatus (Af), a common household mould. The allergic response to Af included eosinophilia, formation of granulomas and induction of Th2 type cytokines. RSV infection prior to allergen challenge resulted in exacerbation of the inflammatory response as well as increased airway responsiveness to methacholine. The exacerbated response was indeed dependent on virus replication. Virus replication in turn was influenced by the allergic response, with persistence in the noses for 2 days longer in animals challenged with allergen. This diminished clearance corresponded to decreased induction of mRNA for IFN-gamma, a Th1-type cytokine that is characteristic of viral infection. Treatment of RSV-infected Af-challenged animals with recombinant IFN-gamma reduced the allergic inflammatory response as well as the relative levels of Th1 and Th2 cytokine mRNA. However, this treatment did not reduce airway reactivity, showing that these pathologic and physiologic measures of exacerbated disease are independent. We speculate that the reciprocal effect of the allergic response on viral immunity may benefit the host by limiting exacerbation of physiologic responses that are IFN-gamma-dependent.

RANTES (CCL5) regulates airway responsiveness after repeated allergen challenge

RANTES (CC chemokine ligand 5) contributes to airway inflammation through accumulation of eosinophils, but the exact role of RANTES (CCL5) is not defined. C57BL/6 mice, sensitized by injection of ovalbumin (OVA) on Days 1 and 14, were challenged with OVA on Days 28, 29, and 30 (3 challenges, short-term-challenge model) or on Days 28, 29, 30, 36, 40, 44, and 48 (7 challenges, repeated-challenge model) and evaluated 48 h later. Anti-mouse RANTES was given intravenously, and recombinant mouse RANTES or PBS was given intratracheally. These reagents were given on Days 28, 29, and 30 in the short-term-challenge study and on Days 44 and 48 in the repeated-challenge study. After short-term challenge, there were no effects after administration of anti-RANTES or RANTES. In the repeated-challenge study, although control mice showed a decrease in airway hyperresponsiveness, administration of anti-RANTES sustained and enhanced airway hyperresponsiveness and increased goblet cell numbers. In contrast, administration of RANTES normalized airway function but reduced goblet cell numbers. IL-12 and IFN-gamma levels in BAL decreased in the anti-RANTES group and increased in the RANTES group. IFN-gamma-producing CD4 T cells in lung, and IFN-gamma production from lung T cells in response to OVA in the anti-RANTES group, were significantly decreased but were increased in the RANTES group. Anti-IFN-gamma, administered with RANTES, decreased the effects of RANTES on AHR after repeated challenge. These data indicate that RANTES plays a role in the regulation of airway function after repeated allergen challenge, in part through modulation of levels of IFN-gamma and IL-12.

CD38/cyclic ADP-ribose signaling: role in the regulation of calcium homeostasis in airway smooth muscle

The contractility of airway smooth muscle cells is dependent on dynamic changes in the concentration of intracellular calcium. Signaling molecules such as inositol 1,4,5-trisphosphate and cyclic ADP-ribose play pivotal roles in the control of intracellular calcium concentration. Alterations in the processes involved in the regulation of intracellular calcium concentration contribute to the pathogenesis of airway diseases such as asthma. Recent studies have identified cyclic ADP-ribose as a calcium-mobilizing second messenger in airway smooth muscle cells, and modulation of the pathway involved in its metabolism results in altered calcium homeostasis and may contribute to airway hyperresponsiveness. In this review, we describe the basic mechanisms underlying the dynamics of calcium regulation and the role of CD38/cADPR, a novel pathway, in the context of airway smooth muscle function and its contribution to airway diseases such as asthma.

Synthetic responses in airway smooth muscle

Human airway smooth muscle (ASM) has several properties and functions that contribute to asthma pathogenesis, and increasing attention is being paid to its synthetic capabilities. ASM can promote the formation of the interstitial extracellular matrix, and in this respect, ASM from asthmatic subjects compared with normal subjects responds differently, both qualitatively and quantitatively. Thus, ASM cells are important regulating cells that potentially contribute to the known alterations within the extracellular matrix in asthma. In addition, through integrin-directed signaling, extracellular matrix components can alter the proliferative, survival, and cytoskeletal synthetic function of ASM cells. ASM also functions as a rich source of biologically active chemokines and cytokines that are capable of perpetuating airway inflammation in asthma and chronic obstructive pulmonary disease by promoting recruitment, activation, and trafficking of inflammatory cells in the airway milieu. Emerging evidence shows that airway remodeling may also be a result of the autocrine action of secreted inflammatory mediators, including T(H)2 cytokines, growth factors, and COX-2-dependent prostanoids. Finally, ASM cells contain both beta(2)-adrenergic receptors and glucocorticoid receptors and may represent a key target for beta(2)-adrenergic receptor agonist/corticosteroid interactions. Combinations of long-acting beta(2)-agonists and corticosteroids appear to have additive and/or synergistic effects in inhibiting inflammatory mediator release and the migration and proliferation of ASM cells.

Regulation of beta-adrenergic responses in airway smooth muscle

Decreased responsiveness to beta-adrenergic receptor agonists is a characteristic feature of human asthma. This review summarizes data regarding the impact of chronic beta agonist stimulation, cytokines, prostanoids and other factors on beta-adrenergic responses in human airway smooth muscle, as well as the impact of polymorphisms of the beta(2)-adrenergic receptor on these responses. Effects of beta-agonists on both airway smooth muscle relaxation and gene expression are considered. Understanding the regulation of beta-adrenergic responses in airway smooth muscle cells may prove to be an important step in improving the efficacy of beta-agonists for the treatment of asthma.

Mechanisms of inflammation-mediated airway smooth muscle plasticity and airways remodeling in asthma

Recent evidence points to progressive structural change in the airway wall, driven by chronic local inflammation, as a fundamental component for development of irreversible airway hyperresponsiveness. Acute and chronic inflammation is orchestrated by cytokines from recruited inflammatory cells, airway myofibroblasts and myocytes. Airway myocytes exhibit functional plasticity in their capacity for contraction, proliferation, and synthesis of matrix protein and cytokines. This confers a principal role in driving different components of the airway remodeling process, and mediating constrictor hyperresponsiveness. Functional plasticity of airway smooth muscle (ASM) is regulated by an array of environmental cues, including cytokines, which mediate their effects through receptors and a number of intracellular signaling pathways. Despite numerous studies of the cellular effects of cytokines on cultured airway myocytes, few have identified how intracellular signaling pathways modulate or induce these cellular responses. This review summarizes current understanding of these concepts and presents a model for the effects of inflammatory mediators on functional plasticity of ASM in asthma.

Inhibitory effects of interferon-gamma on the heterologous desensitization of beta-adrenoceptors by transforming growth factor-beta 1 in tracheal smooth muscle

BACKGROUND

Transforming growth factor-beta1 (TGF-beta 1) is generally considered to play an important role in the pathogenesis of chronic inflammation and fibrosis.

OBJECTIVE AND METHODS

This study was designed to determine mechanisms of reduced responsiveness of guinea-pig tracheal smooth muscle to beta-adrenoceptor agonists by TGF-beta 1, using isometric tension records and tissue cAMP measurement. Moreover, we examined the involvement of the signal transduction processes of TGF-beta superfamily in the desensitization of beta-adrenoceptors.

RESULTS

After exposure to 0.2-2000 pm TGF-beta 1 for 4-8 h, the inhibitory effects of 1 microm isoprenaline (ISO) and 10 microm forskolin on 1 microm MCh-induced contraction were markedly reduced in a concentration-dependent fashion. The desensitization by TGF-beta 1 was greater against ISO than for forskolin. The values of EC75 for the curves for ISO after exposure to the normal bathing solution and TGF-beta 1 were 0.039 +/- 0.02 and 0.38 +/- 0.28 microm, respectively. The values of EC50 for the curves for forskolin under these conditions were 0.50 +/- 0.12 and 0.89 +/- 0.21 microm, respectively. On the other hand, the inhibitory effects of phosphodiesterase inhibitors such as theophylline and rolipram were not attenuated after exposure to TGF-beta 1. Concentration-inhibition curve for ISO was shifted to the right after exposure to 2000 pm TGF-beta 1 for 8 h more than that curve for forskolin. In contrast, the curve for theophylline was not shifted to the right by TGF-beta 1. When the tissues were incubated with TGF-beta 1 in the presence of IFN-gamma, an intracellular antagonist of TGF-beta signalling, IFN-gamma inhibited the reduced response to ISO and forskolin after exposure to TGF-beta 1 in a concentration-dependent fashion. After exposure to TGF-beta 1, the effects of cAMP accumulation of ISO was significantly reduced, however, neither forskolin-nor theophylline-induced cAMP accumulation was affected. IFN-gamma had no significant effect on cAMP accumulation either to ISO or forskolin.

CONCLUSIONS

Impairment of the beta-adrenoceptors/adenylyl cyclase pathway are involved in heterologous desensitization of beta-adrenoceptors induced by TGF-beta 1 in airway smooth muscle. IFN-gamma functionally suppresses this phenomenon via cAMP-independent processes. Phosphodiesterase is still intact under this condition.

CD38/cyclic ADP-ribose-mediated Ca2+ signaling contributes to airway smooth muscle hyper-responsiveness

We previously demonstrated that cyclic ADP-ribose (cADPR) elicits Ca2+ release in airway smooth muscle (ASM) cells through ryanodine receptor channels. CD38 is a cell surface protein that catalyzes the synthesis and degradation of cADPR. In inflammatory diseases such as asthma, augmented Ca2+ responses and Ca2+ sensitivity contribute to increased ASM contractility in response to agonists. In this study, we investigated the regulation of CD38 expression and the role of cADPR-mediated Ca2+ release in airway inflammation. Human ASM cells in culture between the second and fifth passages were exposed to tumor necrosis factor alpha (TNF-alpha), interleukin 1beta, or interferon gamma, or bovine serum albumin (controls). CD38 expression was measured by reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, and Western blot analysis, and ADP-ribosyl cyclase activity was assayed with nicotinamide guanine dinucleotide as the substrate. Ca2+ responses to acetylcholine, bradykinin, and thrombin were measured in fura-2AM-loaded cells by fluorescence microscopy. Cytokines caused significant augmentation of CD38 expression, ADP-ribosyl cyclase activity, and Ca2+ responses to the agonists, compared with the control. TNF-alpha effects were greater than those of the other two cytokines. The cADPR antagonist 8-bromo-cADPR attenuated the Ca2+ responses to the agonists in control and cytokine-treated cells, with the magnitude of inhibition correlating with the level of CD38. This study provides the first demonstration of a role for CD38-cADPR signaling in a model of inflammatory airway disease.

Cytokine regulation of beta-adrenergic responses in airway smooth muscle

Decreased responsiveness to beta-adrenergic receptor agonists is a characteristic feature of human asthma. One explanation for this observation is that cytokines released in the asthmatic airway have direct effects on airway smooth muscle cells that reduce the ability of the cells to relax in response to beta-agonists. This review summarizes data indicating that both inflammatory cytokines, such as IL-1beta and TNF-alpha, and Th2 cytokines, such as IL-13 and IL-5, have the capacity to decrease the ability of cultured airway smooth muscle cells to relax or to generate cyclic AMP in response to beta-agonists, such as isoproterenol. These effects are observed in smooth muscle from human airways and airway smooth muscle of other species. In human airway smooth muscle, the effects of IL-1beta and TNF-alpha appear to be mediated through expression of cyclooxygenase-2, whereas the effect of IL-13 requires activation of the extracellular signal-regulated kinase-mitogen-activated protein kinase pathway. IL-1beta and TNF-alpha also inhibit the ability of beta-agonists to drive airway smooth muscle gene expression through pathways dependent on cyclic AMP response elements. Understanding the mechanistic basis for the effects of these cytokines may prove to be an important step in improving the efficacy of beta-agonists for the treatment of asthma.

Effects of cytokines on contractile and dilator responses of airway smooth muscle

1. Increased bronchoconstrictor responses to contractile agonists and decreased dilator responses to beta-adrenoceptor agonists are characteristics of human asthma. One explanation for these features of asthma is that cytokines released in the asthmatic airway have direct effects on airway smooth muscle cells that alter their phenotype. 2. The present review summarizes data indicating that inflammatory cytokines, such as interleukin (IL)-1 beta and tumour necrosis factor-alpha, T helper (h) 1 cytokines, such as interferon-gamma, and Th2 cytokines, such as IL-13 and IL-5, have the capacity to enhance contractile responses and/or decrease relaxant responses of airway smooth muscle. These effects are observed in smooth muscle from human airways and airway smooth muscle of other species. 3. Understanding the mechanistic basis for the effects of these cytokines may prove to be an important step in improving the efficacy of beta-adrenoceptor agonists for the treatment of asthma.

Cytokine-induced bronchoconstriction in precision-cut lung slices is dependent upon cyclooxygenase-2 and thromboxane receptor activation

Cytokines play an essential role in the regulation of inflammatory responses. The effects of cytokines on lung functions are less well known and their study in vivo is complicated by the attraction of leukocytes to the inflamed sites. Recently the model of precision-cut lung slices was developed, where viable lung slices with an intact microanatomy are taken into culture and where bronchoconstriction can be followed by observing single airways under the microscope. We used this model to study the direct effects of cytokines on airway tonus in the absence of blood-derived leukocytes. Incubation of precision-cut lung slices with a mixture of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and interferon (IFN)-gamma resulted in contraction of airways, which was accompanied by expression of cyclooxygenase (Cox)-2 and thromboxane release into the supernatant. The thromboxane receptor antagonist SQ29548 completely prevented the cytokine-induced bronchoconstriction, whereas the 5-lipoxygenase inhibitor AA681 had no effect on cytokine-induced bronchoconstriction. Preventing the expression of Cox-2 by dexamethasone or blocking Cox-2 activity with the selective Cox-2 inhibitor NS398 attenuated both thromboxane formation and bronchoconstriction. Incubation of lung slices with each of the cytokines alone caused no bronchoconstriction; in fact, IL-1 alone rather dilated the airways. However, simultaneous incubation with TNF and IL-1beta caused a bronchoconstriction that was not further enhanced by IFN-gamma. We conclude that TNF-alpha and IL-1beta synergistically cause bronchoconstriction by induction of Cox-2 and subsequent activation of the thromboxane receptor. Our study raises the possibility that TNF and IL-1 may contribute to bronchospasm during inflammatory lung diseases.

IL-10 reduces Th2 cytokine production and eosinophilia but augments airway reactivity in allergic mice

We investigated the effects of interleukin (IL)-10 administration on allergen-induced Th2 cytokine production, eosinophilic inflammation, and airway reactivity. Mice were sensitized by intraperitoneal injection of ragweed (RW) adsorbed to Alum and challenged by intratracheal instillation of the allergen. Sensitization and challenge with RW increased concentrations of IL-10 in bronchoalveolar lavage (BAL) fluid from undetectable levels to 60 pg/ml over 72 h. Intratracheal instillation of 25 ng of recombinant murine IL-10 at the time of RW challenge further elevated BAL fluid IL-10 concentration to 440 pg/ml but decreased BAL fluid IL-4, IL-5, and interferon-gamma levels by 40-85% and eosinophil numbers by 70% (P < 0.0001). Unexpectedly, the same IL-10 treatment increased airway reactivity to methacholine in spontaneously breathing mice that had been sensitized and challenged with RW (P < 0.001). IL-10 treatment in naive animals or RW-sensitized mice challenged with PBS failed to increase airway reactivity, demonstrating that IL-10 induces an increase in airway reactivity only when it is administered in conjunction with allergic sensitization and challenge. The results demonstrate that IL-10 reduces Th2 cytokine levels and eosinophilic inflammation but augments airway hyperreactivity. Thus, despite its potent anti-inflammatory activity, IL-10 could contribute to the decline in pulmonary function observed in asthma.

Interleukin-1 beta decreases sensitivity of guinea-pig airway to potassium chloride and isoproterenol by an epithelium-dependent mechanism

Airway inflammation may cause alteration of airway responses in chronic airway diseases, such as bronchial asthma. The objective of this study was to examine whether interleukin-1beta (IL-1beta) [corrected], one of the pro-inflammatory cytokines, has a direct effect on airway functions. The effects of IL-1beta on carbachol, KCl and isoproterenol (ISO) responses of isolated guinea-pig tracheal strips were examined by measuring isometric tension in tissue bath. Responses of tracheal strips with or without epithelium to each agonist were compared before and after incubation with IL-1beta (25 ng or 250 ng/mL). Both 1 h and 5 h incubation of the strips with 250 ng/mL IL-1beta significantly decreased the sensitivity not only to KCl (P < 0.05; P < 0.01, respectively), but also to ISO (both P < 0.05) without affecting maximum contraction or relaxation. Response to carbachol was not affected by IL-1beta. Epithelial denudation abolished the effects of IL-1beta on KCl and ISO responses. Indomethacin (2 micromol/L) [corrected] reversed the effects of IL-1beta both on KCl and on ISO. These results suggest that IL-1 beta decreases the sensitivity of airway strips to KCl and ISO, possibly by stimulating prostaglandin production from the airway epithelium [corrected].