It has been reported that Chlamydophila (C.) pneumoniae is involved in the initiation and promotion of asthma and chronic obstructive pulmonary diseases (COPD). Surprisingly, the effect of C. ...pneumoniae on airway function has never been investigated.
In this study, mice were inoculated intranasally with C. pneumoniae (strain AR39) on day 0 and experiments were performed on day 2, 7, 14 and 21.
We found that from day 7, C. pneumoniae infection causes both a sustained airway hyperresponsiveness and an inflammation. Interferon-gamma (IFN-gamma) and macrophage inflammatory chemokine-2 (MIP-2) levels in bronchoalveolar lavage (BAL)-fluid were increased on all experimental days with exception of day 7 where MIP-2 concentrations dropped to control levels. In contrast, tumor necrosis factor-alpha (TNF-alpha) levels were only increased on day 7. From day 7 to 21 epithelial damage and secretory cell hypertrophy was observed. It is suggested that, the inflammatory cells/mediators, the epithelial damage and secretory cell hypertrophy contribute to initiation of airway hyperresponsiveness.
Our study demonstrates for the first time that C. pneumoniae infection can modify bronchial responsiveness. This has clinical implications, since additional changes in airway responsiveness and inflammation-status induced by this bacterium may worsen and/or provoke breathlessness in asthma and COPD.
Cigarette smoke is the major risk factor for the development of chronic obstructive pulmonary disease (COPD). Macrophages are suggested to orchestrate the chronic inflammatory response and tissue ...destruction associated with COPD by secreting interleukin (IL)-8, a major neutrophil chemoattractant. The combination of inhaled corticosteroids and long-acting β
2-adrenoceptor agonists are increasingly used as maintenance therapy in patients with COPD. The aim of this study was to determine whether combined fluticasone propionate, a corticosteroid, and salmeterol, a long-acting β
2-adrenoceptor agonist, can suppress IL-8 production by human macrophages. To mimic resident macrophages in the lung, human monocytes were cultured for 5 days in medium containing Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) and Macrophage Colony Stimulating Factor (M-CSF). In human Monocyte-Derived Macrophages, we found that cigarette smoke medium strongly enhanced IL-8 release in a time- and concentration-dependent manner. IL-8 release by cigarette smoke was significantly suppressed in a concentration-dependent manner by fluticasone and salmeterol. Coincubation of the drugs potentiated the inhibitory effect on cigarette smoke medium-induced IL-8 production and longer preincubation times resulted in more IL-8 inhibition. Interestingly, preincubation of cells with suboptimal concentration of salmeterol for 4 h before fluticasone administration for 30 min potentiates the inhibitory effect of fluticasone on IL-8 release. In conclusion, combination therapy may provide benefits over monotherapy for the treatment of COPD patients.
Inflammatory bowel disease (IBD) describes chronic inflammatory conditions of the gastrointestinal tract, and TNF-alpha plays a pivotal role in mediating the response. The proinflammatory cytokine ...TNF-alpha is rapidly released by mast cells after degranulation. In the present study, we hypothesized TNF-alpha to be an important player in our recently described mast cell-dependent murine model for IBD. The effect of neutralizing anti-TNF-alpha MAb was studied on colonic hypersensitivity in mice induced by a skin application of dinitrofluorobenzene (DNFB) followed by an intrarectal challenge with dinitrobenzene sulfonic acid. Features of the colonic hypersensitivity response included diarrhea, mast cell infiltration and activation, infiltration of inflammatory cells in the colon, colonic patch hypertrophy, and increased mast cell-derived TNF-alpha levels in the colon. Anti-TNF-alpha MAb could effectively abrogate diarrhea in DNFB-sensitized mice 72 h after the challenge. The numbers of colonic patches and total tissue damage scores were reduced by anti-TNF-alpha MAb treatment in DNFB-sensitized mice 72 h after the challenge. Mast cell infiltration and activation remained unaffected by neutralizing anti-TNF-alpha MAb. Treatment with the corticosteroid dexamethasone, a frequently used therapeutic treatment in IBD, resulted in a reduction of diarrhea, cellular infiltration, and total tissue damage scores to the same extent as anti-TNF-alpha MAb. Additionally, dexamethasone treatment could also reduce total TNF-alpha levels in the colon, mast cell numbers, and mast cell activation in both vehicle- and DNFB-sensitized mice 72 h after the challenge. These findings suggest that TNF-alpha can play an instrumental role in causing inflammatory responses in the present murine model for IBD downstream from mast cell activation.
Chronic inflammation in lung diseases contributes to lung tissue destruction leading to the formation of chemotactic collagen fragments such as N-acetylated Proline–Glycine–Proline (N-ac-PGP). In ...this study, we investigated in more detail the mechanism of action of N-ac-PGP in neutrophilic inflammation. N-ac-PGP was chemotactic for human neutrophils via pertussis toxin sensitive G protein-coupled receptors
in vitro and directly activated this cell type, which led to cytosolic calcium mobilization and release of CXCL8. Furthermore, using a selective CXCR2 antagonist confirmed that N-ac-PGP-induced neutrophil chemotaxis is mediated through CXCR2 activation. To determine whether N-ac-PGP was solely responsible for the migration and activation of human neutrophils
in vitro and not the released CXCL8 upon stimulation with N-ac-PGP, an antibody directed against CXCL8 was used. Performing chemotaxis and calcium influx assays in the presence of this antibody did not alter the effects of N-ac-PGP whereas effects of CXCL8 were attenuated. These experiments indicate that N-ac-PGP, in addition to the direct induction of chemotaxis, also directly activates neutrophils to release CXCL8.
In vivo, this may lead in the long term to a self-maintaining situation enhanced by both N-ac-PGP and CXCL8, leading to a further increase in neutrophil infiltration and chronic inflammation.
Toluene diisocyanate (TDI) is a low-molecular-weight compound which is known to cause occupational asthma in 5 to 10% of exposed workers. Previously, we developed a murine model to investigate ...TDI-induced occupational asthma. Short-term exposure to TDI (skin sensitization twice daily on Day 0 and Day 1 and intranasal challenge on Day 8) led to a nonspecific tracheal hyperractivity 24 h after the challenge in TDI-sensitized mice when compared with nonsensitized mice whereas no TDI-specific IgE antibodies were found in the serum. Because 20% of subjects with TDI-induced occupational asthma exhibit an increase in serum IgE antibodies, we exposed mice for a longer period of time to investigate whether this procedure could induce TDI-specific antibody production in exposed mice. Long-term exposure (skin sensitization on 6 consecutive weeks followed by intranasal challenge on Week 7) resulted in the production of total IgE and IgG and TDI-specific IgE and IgG antibodies. Airway reactivity to various agonists was also measured in vitro and in vivo in long-term exposed mice. TDI-sensitized mice exhibited in vitro tracheal hyperreactivity to carbachol 3 h after the challenge when compared with the nonsensitized mice. Moreover, in vivo airway hyperresponsiveness to serotonin (5-hydroxytryptamine 5HT) was found 3 h after the challenge in TDI-sensitized mice. Interestingly, in vivo airway hyperresponsiveness was not observed at any time point in the mice exposed to TDI according to the short-term protocol. In conclusion, by altering the exposure time and/or cumulative dosage of TDI different biological reactions can be elicited in exposed mice. This important finding might be a reflection of the diversity of symptoms found in patients suffering from TDI-induced asthma. Both the short-exposure and the long-exposure model will be useful to further investigate the mechanisms of action of TDI.
Elevated levels of nerve growth factor have been linked to the onset and persistence of many pain-related disorders and asthma. Described here are the design, expression, refolding, and purification ...of a monomeric (nonstrand-swapped) form of the binding domain of the nerve growth factor receptor, designated TrkAd5. We have shown that TrkAd5 produced recombinantly binds nerve growth factor with picomolar affinity. TrkAd5 has been characterized using a variety of biophysical and biochemical assays and is shown here to be stable in both plasma and urine. The palliative effects of TrkAd5 are demonstrated in animal models of inflammatory pain and allergic asthma. We conclude that TrkAd5 will prove effective in ameliorating both acute and chronic conditions where nerve growth factor acts as a mediator and suggest a role for its application in vivo as a novel therapeutic.
The gastro-intestinal tract is highly innervated by both intrinsic and extrinsic sensory nerves and this neuronal component is thought to play a role in local inflammatory responses. This in vivo ...study was designed to determine the function of substance P and the tachykinin NK1 receptor in the pathogenesis of inflammatory bowel disease by the use of the specific antagonist RP 67580. The dinitrofluorobenzene (DNFB)-induced colonic hypersensitivity model is associated with increased levels of substance P in the colon. The tachykinin NK1 receptor antagonist RP 67580 was used to investigate the role of substance P on the development of diarrhea, mast cell infiltration and activation, colonic tissue damage, hypertrophy of colonic lymphoid structures and leukocyte infiltration. The formation of watery diarrhea could completely be abrogated by treatment with RP 67580 in DNFB-sensitized animals 72 h after challenge. Antagonizing the tachykinin NK1 receptor in these animals also resulted in significantly reduced colonic patch hypertrophy, leukocyte recruitment and tissue damage. Total levels of substance P in the colon of DNFB-sensitized mice treated with the inactive enantiomer of the tachykinin NK1 receptor antagonist were significantly higher compared to DNFB-sensitized mice treated with RP 67580 72 h after challenge. Although RP 67580 was capable of reducing the total number of mast cells present in the colon, mast cell activation was not affected by this treatment. In conclusion, in this chemically-induced immunological model for inflammatory bowel disease we demonstrated an important role for tachykinin NK1 receptors, and its ligand substance P, in the development of colitis downstream from mast cell activation.
TNF-alpha is a cytokine associated with inflammatory diseases, including asthma. Increased levels of TNF-alpha were found in the bronchoalveolar lavage fluid of mice undergoing a dinitrofluorobenzene ...(DNFB)-induced non-IgE-mediated pulmonary hypersensitivity reaction. We report in this work that TNF-alpha increases the susceptibility of sensory neurons to dinitrobenzene sulfonic acid (DNS) and capsaicin, leading to a tracheal vascular hyperpermeability response in DNFB-sensitized and DNS-challenged mice. mAb against TNF-alpha or the TNFR1 inhibited this hyperpermeability response in DNFB-sensitized and DNS-challenged mice. Furthermore, the hyperpermeability response after DNS challenge was abolished in DNFB-sensitized mast cell-deficient WBB6F(1)-W/W(V) mice. These animals showed a remarked decrease of TNF-alpha bronchoalveolar lavage fluid levels after a single DNS challenge. The hyperpermeability response after DNS challenge was regained in mast cell-deficient mice after mast cell reconstitution. These findings indicate a prominent role for TNF-alpha and its TNFR1 in the DNFB-induced tracheal hyperpermeability response. We propose that a priming effect of mast cell-derived TNF-alpha on the sensory neurons could be the mechanism of action of TNF-alpha in the vascular hyperpermeability response in tracheas of mice undergoing a pulmonary hypersensitivity reaction.
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