Developmental differences in neuromodulation and synaptic properties in the lamprey spinal cord.

Functional properties in the spinal cord change during development to adapt motor outputs to differing behavioral requirements. Here, we have examined whether there are also developmental differences in spinal cord plasticity by comparing the neuromodulatory effects of substance P in the larval lamprey spinal cord with its previously characterized effects in premigratory adults. The premigratory adult effects of substance P were all significantly reduced in larvae. As the adult effects of substance P depend on the N-methyl-d-aspartate (NMDA)-dependent potentiation of glutamatergic synaptic transmission, we examined if the developmental differences in neuromodulation were associated with differences in synaptic properties. We found that the amplitude, rise time, and half-width of excitatory postsynaptic potentials (EPSPs) from excitatory network interneurons were all significantly reduced in larvae compared with adults. These differences were associated with a reduction in the NMDA component of larval EPSPs, an effect that could have contributed to the reduced modulatory effects of substance P in larvae. In contrast to glutamatergic inputs, the amplitude, rise time, and half-width of inhibitory postsynaptic potentials (IPSPs) from ipsilateral inhibitory interneurons were all significantly increased in larvae compared with adults. Substance P also potentiated larval IPSP amplitudes, an effect not seen in adults. This increase in inhibition contributed to the reduced effects of substance P in larvae, as premigratory adult-like modulation could be evoked when inhibition was blocked with strychnine. These results suggest that opposite developmental changes in excitatory and inhibitory synaptic transmission and their modulation are associated with developmental differences in spinal cord neuromodulation.

The role of CD23 on allergen-induced IgE levels, pulmonary eosinophilia and bronchial hyperresponsiveness in mice.

BACKGROUND: The role of Immunoglobulin (Ig)E in inflammation is the subject of considerable study and a number of studies have shown conflicting evidence for its role in eosinophil recruitment and bronchial hyperresponsiveness in a number of murine models. The low affinity IgE receptor, CD23, is known to act as a negative regulator of IgE production and we have used knockout mice deficient in CD23 to investigate the role of IgE in eosinophil recruitment and bronchial hyperresponsiveness in a murine model of airway inflammation. OBJECTIVE: To study the role of the low affinity FcepsilonII receptor, CD23 in IgE production, lung inflammation and bronchial hyperresponsiveness. METHODS: Wild-type and CD23 knockout C57Bl/6 mice (CD23-/-) were immunized by intraperitoneal injection with ovalbumin on days 0 and 14 and challenged with aerosolized antigen on day 21 for a period of up to 1 week. Blood samples, bronchoalveolar lavage and lung tissue samples were obtained to determine serum IgE levels and inflammatory cell numbers, respectively. Furthermore, airway resistance was measured to increasing concentrations of aerosolized 5-hydroxytryptamine in order to evaluate the effect of CD23 deficiency on bronchial hyperresponsiveness to antigen challenge. RESULTS: Sensitization of wild-type C57Bl/6 mice to ovalbumin resulted in elevated levels of total serum IgE and ovalbumin-specific IgE, which was significantly augmented in CD23 knockout C57Bl/6 mice (CD23-/-). A significant increase in the percentage of eosinophils recovered in bronchoalveolar lavage fluid from wild-type and CD23-/- mice was observed 24 h following 3 or 7 days aerosol exposure with ovalbumin (10 mg/mL). At 3 days, the increase in the percentage of eosinophils was significantly greater in CD23-/- groups. Immunohistochemical analysis of lungs sections revealed the presence of CD3+, CD4+ and CD23+ cells in wild-type mice but a lack of immunofluorescence of CD23+ cells in CD23-/- mice. In wild-type ovalbumin-immunized mice, bronchial hyperresponsiveness to aerosolized 5-hydroxytryptamine was observed following a 3-day antigen challenge, which was significantly greater in CD23-/- ovalbumin-immunized mice. CONCLUSION: These studies demonstrate that CD23-/- mice have increased capacity to produce IgE consistent with the view of a negative feedback role for membrane-bound CD23 and under such conditions, may account for the greater numbers of eosinophils recruited to the airways and bronchial hyperresponsiveness observed following acute but not chronic antigen challenge.

Effect of inhaled budesonide on lung function and airway inflammation. Assessment by various inflammatory markers in mild asthma.

In a double-blind, cross-over study, we examined the effect of inhaled budesonide (800 microgram twice daily via Turbohaler) on lung function and various markers of airway inflammation including airway responsiveness to methacholine (PC20), exhaled nitric oxide (NO), eosinophils in induced sputum, bronchoalveolar lavage (BAL), and airway biopsies from 14 patients with mild asthma needing beta2- agonist therapy only. After inhaled steroids, there was a significant increase in FEV1 and PC20, and reduction in exhaled NO. Eosinophils in induced sputum and airway biopsy sections were also significantly decreased, although BAL eosinophil counts remained unchanged. At baseline, significant correlations were observed between exhaled NO and PC20 methacholine (r = 0.64, p < 0.05), exhaled NO and peak expiratory flow rate (PEFR) variability (r = 0. 65, p < 0.05), sputum eosinophils and FEV1 (r = -0.63, p = 0.05), and sputum eosinophils and log PC20 methacholine (r = -0.67, p < 0. 05). After treatment with inhaled steroids, there was a significant correlation between eosinophils in biopsy sections, and BAL, with log PC20 methacholine. It is likely that these parameters represent different aspects of the inflammatory process, which are all inhibited by inhaled steroids.

Inducible nitric oxide synthase after sensitization and allergen challenge of Brown Norway rat lung.

1. We studied the effects of ovalbumin (OA) sensitization and challenge on inducible nitric oxide synthase (iNOS) gene and protein expression in Brown-Norway rats in vivo. 2. By use of Northern analysis, a 4.4-kb iNOS mRNA transcript was weakly observed in control rat lung but there was a 3 fold increase in lungs sensitized to OA alone (P<0.05). In sensitized rats, four hours after exposure to OA aerosol, there was a 6 fold increase in iNOS mRNA transcript (P<0.05), which returned to baseline at 24 h. 3. Immunostaining with an anti-mouse iNOS antibody revealed some patchy staining of airway epithelium in naive rats. There were no changes in sensitized rats exposed to saline, but sensitized and OA-exposed rats showed increased expression in iNOS staining in macrophages. 4. Electrophoretic mobility shift assays of lung nuclear extracts showed a marked increase in nuclear factor-kappaB (NF-kappaB)-binding activity at 2 h after allergen exposure with return to baseline at 6, 12 and 24 h. 5. We concluded that there is increased iNOS gene and protein expression associated with increased NF-kappaB DNA-binding in lungs of sensitized and challenged rats. The increase in iNOS expression may underlie the increase in exhaled NO found after allergen challenge and may contribute to the development of allergen-induced airway hyperresponsiveness.

Expression of RANTES mRNA and protein in airways of patients with mild asthma.

Chemoattractant cytokines (chemokines) such as RANTES, are potent chemoattractants for eosinophils, T lymphocytes, and monocyte/macrophages. We examined RANTES mRNA and protein expression in bronchial biopsies and bronchoalveolar lavage (BAL) cells from patients with mild asthma on beta 2-adrenergic agonist therapy only. Using quantitative polymerase chain reaction (PCR), mean RANTES starting cDNA was 110 +/- 18 fg/pg beta-actin in asthmatics compared with 33.7 +/- 11.0 fg/pg in normals (p < 0.003) but there was no significant difference in RANTES mRNA expression in BAL cells between the two groups. Immunohistochemical staining of cryostat sections of bronchial biopsies with an anti-RANTES antibody using peroxidase antiperoxidase method revealed constitutive staining in airway epithelial cells, airway smooth muscle, and subepithelial cells. However, there was no difference in the number of RANTES-staining cells between normal subjects and asthmatics despite significantly increased numbers of CD4+ T-cells, CD68+ macrophages, and MBP+ eosinophils in mucosal biopsies obtained from asthmatics. Double-staining revealed expression of RANTES in a proportion of CD3+ T lymphocytes. Thus, RANTES is constitutively expressed in the airways and RANTES mRNA is elevated in airways of patients with mild asthma, supporting a role for RANTES in normal and asthmatic airways.

Glucocorticoid receptor localization in normal and asthmatic lung.

The localization and distribution of the human glucocorticoid receptor (GR) mRNA and protein was investigated in human lung obtained from transplant donors and recipients by in situ hybridization, RNA blot analysis, immunolocalization, and Western analysis. Subjects were either nonasthmatic or had mild asthma requiring only beta(2)-agonists. No difference in amount of GR mRNA was found in total RNA isolated from nonasthmatic or asthmatic donor lung. In situ hybridization showed the highest concentration of GR mRNA in the alveolar walls and vascular endothelium and smooth muscle, with lesser amounts in the airway epithelium and smooth muscle. There was no change in the level or sites of expression of GR mRNA between normal and asthmatic subjects. Immunolocalization of GR confirmed the in situ hybridization data. There was no change in the level or sites of expression of GR, in either the lung or airway, between normal and asthmatic subjects. Immunolocalization of GR in bronchial biopsies from two normal and asthmatic subjects confirmed the localization and distribution of GR. Western analysis and mobility shift assays confirmed no differences in GR levels between the two subject groups. The localization of GR mRNA and protein to specific cell types within lung and airway will make it possible to study the cellular targets of glucocorticoid therapy in inflammatory lung diseases such as asthma.