Transcription factors GATA-3 and RORγt are important for determining the phenotype of allergic airway inflammation in a murine model of asthma

In refractory asthma, neutrophils, rather than eosinophils, often predominate in the airways. Neutrophilic airway inflammation appears to be resistant to steroids and may be related to the Th17, rather than the Th2, cytokine milieu. However, the role of GATA-3 and RORγt, transcription factors for Th2 and Th17 cell differentiation, respectively, in the pathogenesis of steroid-insensitive asthma remains unclear. To examine the effect of GATA-3- and RORγt-overexpression backgrounds on airway inflammation and steroid sensitivity, we generated two strains of transgenic mice overexpressing GATA-3 or RORγt. Mice were sensitized and challenged with OVA. Some OVA-sensitized/challenged mice were treated with dexamethasone, anti-IL-17 Ab, CXCR2 antagonist, or anti-IL-6R Ab to demonstrate their therapeutic effects on airway inflammation. Although Ag-specific airway inflammation and hyperresponsiveness were induced in each mouse, the phenotype of inflammation showed a distinct difference that was dependent upon the genotype. GATA-3-overexpressing mice exhibited steroid-sensitive eosinophilic inflammation with goblet cell hyperplasia and mucus hyperproduction under Th2-biased conditions, and RORγt-overexpressing mice developed steroid-insensitive neutrophilic inflammation under Th17-biased conditions. The levels of keratinocyte-derived chemokine, MIP-2, IL-6, and other neutrophil chemotaxis-related mediators were significantly elevated in OVA-exposed RORγt-overexpressing mice compared with wild-type mice. Interestingly, airway hyperresponsiveness accompanied by neutrophilic airway inflammation in RORγt-overexpressing mice was effectively suppressed by anti-IL-17 Ab, CXCR2 antagonist, or anti-IL-6R Ab administration. In conclusion, our results suggest that the expression levels of GATA-3 and RORγt may be important for determining the phenotype of asthmatic airway inflammation. Furthermore, blockade of the Th17-signaling pathway may be a treatment option for steroid-insensitive asthma.

Aggravation of bleomycin-induced pulmonary inflammation and fibrosis in mice lacking peroxiredoxin I

Oxidative stress plays an important role in the pathogenesis of acute lung injury and pulmonary fibrosis. Peroxiredoxin (Prx) I is a cellular antioxidant enzyme induced under stress conditions. In the present study, the protective effects of Prx I on the development of bleomycin-induced acute pulmonary inflammation and pulmonary fibrosis were investigated using Prx I-deficient mice. Survival of Prx I-deficient mice after bleomycin administration was significantly lower than that of wild-type mice, corresponding with enhanced acute pulmonary inflammation and fibrosis. The level of inflammatory cytokines and chemokines, such as TNF-α, macrophage inflammatory protein-2, and monocyte chemotactic protein-1, was significantly elevated in the bronchoalveolar lavage fluid of Prx I-deficient mice after bleomycin administration. Furthermore, the level of 8-isoprostane, an oxidative stress marker, and the concentration and alveolar macrophage expression of macrophage migration inhibitory factor were elevated in the lungs of Prx I-deficient mice after bleomycin administration. The exacerbation of bleomycin-induced pulmonary inflammation and fibrosis in Prx I-deficient mice was inhibited by treatment with N-acetyl-L-cysteine, a radical scavenger, or with (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester, a tautomerase inhibitor of macrophage migration inhibitory factor. These findings suggest that mice lacking Prx I are highly susceptible to bleomycin-induced pulmonary inflammation and fibrosis because of increases in pulmonary oxidant levels and macrophage migration inhibitory factor activity in response to bleomycin.

Nrf2 protects against pulmonary fibrosis by regulating the lung oxidant level and Th1/Th2 balance

Background

Pulmonary fibrosis is a progressive and lethal disorder. Although the precise mechanisms of pulmonary fibrosis are not fully understood, oxidant/antioxidant and Th1/Th2 balances may play an important role in many of the processes of inflammation and fibrosis. The transcription factor Nrf2 acts as a critical regulator for various inflammatory and immune responses by controlling oxidative stress. We therefore investigated the protective role of Nrf2 against the development of pulmonary fibrosis.

Methods

To generate pulmonary fibrosis, both wild-type C57BL/6 mice and Nrf2-deficient mice of the same background were administered bleomycin intratracheally.

Results

The survival of Nrf2-deficient mice after bleomycin administration was significantly lower than that of wild-type mice. The degree of bleomycin-induced initial pulmonary inflammation and pulmonary fibrosis was much more severe in Nrf2-deficient mice than in wild-type mice. The expression of antioxidant enzymes and phase II detoxifying enzymes was significantly reduced in the lungs of Nrf2-deficient mice, concomitant with an elevation of lung 8-isoprostane level, compared with wild-type mice. The expression of Th2 cytokines, such as interleukin-4 and interleukin-13, was significantly elevated in the lungs of Nrf2-deficient mice with an increase in the number of Th2 cells that express GATA-binding protein 3.

Conclusions

The results indicated that Nrf2 protects against the development of pulmonary fibrosis by regulating the cellular redox level and lung Th1/Th2 balance. Thus, Nrf2 might be an important genetic factor in the determination of susceptibility to pulmonary fibrosis.

Intracisternal, but not intrathecal, injection of naloxone inhibits cutaneous itch-related response in mice

The present study was conducted to determine whether cutaneous itch involves mu-opioid receptors in either of the spinal cord or lower brainstem or in both regions in mice. An intraplantar injection of serotonin hydrochloride (100 nmol/site) induced biting, an itch-related behavior. The behavior was inhibited by subcutaneous (0.3-1 mg/kg) and intracisternal (1--10 nmol/site), but not intrathecal (1--10 nmol/site), injections of naloxone hydrochloride. An intradermal injection of serotonin (100 nmol/site) to the rostral back induced scratching, an itch-related behavior, which was inhibited by subcutaneous (1 mg/kg) and intracisternal (10 nmol/site) injections of naloxone. These results suggest that mu-opioid receptor in the lower brainstem, but not spinal cord, is a site of central pruritogenic action of opioids and is involved in the facilitatory regulation of itch signaling.

Pharmacological effects of imidafenacin (KRP-197/ONO-8025), a new bladder selective anti-cholinergic agent, in rats. Comparison of effects on urinary bladder capacity and contraction, salivary secretion and performance in the Morris water maze task

Imidafenacin (CAS 170105-16-5, KRP-197, ONO-8025) has been developed for the treatment of overactive bladder as a new anti-cholinergic with high affinities for muscarinic acetylcholine M3 and M1 receptors. The pharmacological profiles of imidafenacin on the urinary bladder function by determining carbamylcholine (CCh)-induced decrease in bladder capacity and distention-induced rhythmic bladder contraction in conscious rats were investigated. In addition, effects of imidafenacin on CCh-induced salivary secretion and performance in the Morris water maze task in rats were investigated to evaluate side effects, such as dry mouth and cognitive dysfunction in the central nervous system (CNS). Imidafenacin prevented the CCh-induced decrease in bladder capacity dose-dependently with an ID50 of 0.055 mg/kg. On the distention-induced rhythmic bladder contraction, imidafenacin, propiverine, tolterodine, oxybutynin and darifenacin showed inhibitory effects with ID30's of 0.17, 15, 3.0, 3.2 and 0.85 mg/kg, respectively. The rank order of inhibitory potency was: imidafenacin > darifenacin > tolterodine > or = oxybutynin > propiverine. Imidafenacin, propiverine, tolterodine, oxybutynin and darifenacin showed inhibitory effects on the CCh-stimulated salivary secretion with ID50's of 1.5, 14, 15, 4.4 and 1.2 mg/kg, respectively. The rank order of inhibitory potency was: darifenacin > or = imidafenacin > oxybutynin > propiverine > or = tolterodine. Imidafenacin at the doses of 1 and 10 mg/ kg did not affect the escape latencies in the Morris water maze task compared with those in vehicle controls. Oxybutynin at the dose of 100 mg/kg induced a significant increase in the escape latencies, but propiverine at the dose of 100 mg/kg did not induce significant changes. These results suggest that imidafenacin inhibits urinary bladder contraction to a greater extent than the salivary secretion (compared with the M3 receptor selective antagonist, darifenacin, and the non-selective antagonists, propiverine, tolterodine and oxybutynin) or the CNS functions, such as performance in the Morris water maze task (compared with oxybutynin). In conclusion, imidafenacin has organ selectivity for the bladder over the salivary gland, without influence on the central nervous system such as spatial learning and memory.

Effects of imidafenacin (KRP-197/ONO-8025), a new anti-cholinergic agent, on muscarinic acetylcholine receptors. High affinities for M3 and M1 receptor subtypes and selectivity for urinary bladder over salivary gland

Imidafenacin (CAS 170105-16-5, KRP-197, ONO-8025) is an antagonist for the muscarinic acetylcholine (ACh) receptor currently under development for the treatment of overactive bladder. Affinities of imidafenacin and other drugs for muscarinic ACh receptor subtypes were investigated by examining inhibitory effects on ACh release in the rat urinary bladder and K+ efflux in the rat salivary gland in functional and binding assays. In the functional assay, imidafenacin had higher affnities for M3 and M1 receptors than for the M2 receptor. In contrast, metabolites of imidafenacin (M-2, M-4 and M-9) had low affinities for muscarinic ACh receptor subtypes. Darifenacin had selectivity for the M3 receptor, while propiverine, tolterodine and oxybutynin had no selectivity for muscarinic ACh receptors. In carbamylcholine (CCh)-induced contraction in the urinary bladder, imidafenacin, propiverine, tolterodine and oxybutynin had affinities similar to those for the M3 receptor in the ileum. In the binding assay for human muscarinic ACh receptor subtypes, imidafenacin had higher affinities for m3 and m1 receptors than for m2 receptor, but tolterodine had no selectivity for m1, m2 and m3 receptors. In ACh release in the urinary bladder, inhibitory effects of imidafenacin, tolterodine, oxybutynin and darifenacin seemed to be partially mediated by the M1 receptor. In ACh-induced and electrical stimulation-induced K+ efflux from the salivary gland, inhibitory effects (IC50) of imidafenacin, propiverine, tolterodine, oxybutynin and darifenacin might be closely related to those for the M3 receptor in the ileum. These results suggest that imidafenacin more strongly antagonizes cholinomimetics on M3 and M1 receptors than on the M2 receptor. Moreover, imidafenacin seems to inhibit the contraction of the bladder smooth muscle by mediating antagonism to the M3 receptor and to regulate ACh release by mediating prejunctional facilitatory M1 receptor. Imidafenacin also inhibited K+ efflux from the salivary gland mainly by mediating the M3 receptor. Therefore, imidafenacin will have higher affinities for M3 and M1 receptors and higher selectivity for the urinary bladder than for the salivary gland.

Intradermal nociceptin elicits itch-associated responses through leukotriene B(4) in mice

Nociceptin, the endogenous peptide ligand for opioid receptor like-1 (ORL1) receptor, has been implicated in the inflammation and pain in the skin. We examined whether nociceptin is a pruritogen in mice. Intradermal injections of nociceptin (1-100 nmol per site) concentration dependently increased scratching in ICR mice; the effect started within 1 min, peaked at 10-20 min, and almost subsided by 30 min. The nociceptin action was absent in ORL1 receptor-deficient (ORL1(-/-)) mice. Systemic, but not local, treatment with naloxone significantly inhibited scratching induced by nociceptin. The action of nociceptin was inhibited by the leukotriene B(4) receptor antagonist ONO-4057 and azelastine, which inhibits the action and production of leukotriene B(4) in the skin. Prepronociceptin and ORL1 receptor mRNAs were substantially expressed in the skin, whereas their expression levels were very low in the dorsal root ganglia. In the skin, nociceptin- and ORL1 receptor-like immunoreactivities were localized in the epidermis. Administration of nociceptin to primary cultures of keratinocytes from ICR and C57BL/6 (ORL1(+/+)) mice, but not ORL1(-/-) mice, produced leukotriene B(4). The results suggest that nociceptin acts on ORL1 receptor on the keratinocytes to produce leukotriene B(4), which induces itch-associated responses in mice.