Neural plasticity occurs in the adrenal medulla of asthmatic rats.

BACKGROUND: Airway symptoms in asthma are related to decrease of epinephrine secretion, which may be ascribed to elevated nerve growth factor (NGF) in the organism. The aim of this study was to monitor the neuroendocrine alteration in the adrenal medulla of asthmatic rats. METHODS: Sixteen rats were randomly divided into two groups (n = 8), control group and asthma group, and the asthmatic rats were sensitized and challenged with ovalbumin (OVA). The levels of NGF, epinephrine and norepinephrine in serum were detected by enzyme linked immunosorbent assay (ELISA), the NGF expression in adrenal medulla was detected by immunohistochemistry, and the changes in the ultrastructure of the adrenal medulla was observed by electron microscopy. RESULTS: The NGF expression was increased in asthmatic rats compared with control rats. Compared with control rats, the results indicated that the epinephrine level was decreased in asthmatic rats, but no significant difference was found in norepinephrine levels. We found more ganglion cells in the adrenal medulla of asthmatic rats than in control rats, with NGF immunostaining mainly located in these ganglion cells. Electron microscopic images showed the density of chromaffin granula decreased and there was shrunken nucleolemma in the adrenal medullary cells of asthmatic rats. CONCLUSION: The innervation of the adrenal medulla is changed in asthmatic rats, and it may contribute to the epinephrine decrease in asthma.

Effects of Arkadia on airway remodeling through enhancing TGF-beta signaling in allergic rats.

Upregulation of transforming growth factor-beta (TGF-beta) signaling is interrelated with the development of airway remodeling. In this study, we examined the role of two E3 ubiquitin ligases, Arkadia and Smurf2, which are critically required for TGF-beta signaling in airway remodeling. Rats were immunized with ovalbumin (OVA) and then challenged with an OVA aerosol. In in vitro experiments, normal human bronchial epithelial cells were stimulated with TGF-beta(1) with or without the preincubation of Arkadia/Smurf2 small interfering RNA (siRNA) or lactacystin (an inhibitor of proteasomal degradation). In the lungs of OVA-treated rats, a large number of inflammatory cells were present near the airways. An increased subepithelial collagen deposition was associated with high expression levels of Smad7, SnoN and Ski mRNAs, Arkadia, Smurf2, and TGF-beta type I receptor (TbetaRI), but low expression levels of Smad7, SnoN and Ski proteins. Smad7, SnoN and Ski interacted with both Arkadia and Smurf2 while TbetaRI only interacted with Smurf2 but not with Arkadia. In in vitro experiments, the inhibitory effect of TGF-beta(1) on the expression of Smad7, SnoN and Ski was reversed by Arkadia siRNA and lactacystin, whereas the stimulatory effect of TGF-beta(1) on the expression of TbetaRI protein and Smad7/SnoN/Ski mRNAs was not affected. In contrast, Smurf2 siRNA did not influence the effects of TGF-beta(1) on the expression of the above proteins. Our results suggest that Arkadia may contribute to the pathogenesis of airway remodeling through enhancing TGF-beta signaling by inducing the reduction of Smad7, SnoN and Ski proteins in OVA-sensitized and -challenged rats.

[A novel mutation of the SLC34A2 gene in a Chinese pedigree with pulmonary alveolar microlithiasis].

OBJECTIVE: To identify the mutation of solute carrier family 34 member 2 (SLC34A2) gene in a Chinese family with pulmonary alveolar microlithiasis (PAM). METHODS: Genomic DNA was extracted from the family members. DNA sequencing was carried out to confirm the mutation detected by polymerase chain reaction-single strand conformation polymorphisms (PCR-SSCP). The fragments with variation were screened in 100 healthy controls by PCR-SSCP. RESULTS: In both patients of the family, a homozygous mutation of the SLC34A2 gene was identified in exon 8 (c.A910T), resulting in a premature stop codon. In addition, a homozygous single nucleotide polymorphism (SNP) was found in intron 2 in both patients and the daughter of proband. CONCLUSION: A novel homozygous mutation in SLC34A2 gene, leading to a premature stop codon therefore a truncated protein, was probably responsible for the PAM in this family. The SNP in intron 2 needs further study.