Differential effects of extracellular matrix and mechanical strain on airway smooth muscle cells from ovalbumin- vs. saline-challenged Brown Norway rats

Key roles for the small leucine-rich proteoglycans in renal and pulmonary pathophysiology

BACKGROUND

Small leucine-rich proteoglycans (SLRPs) are molecules that have signaling roles in a multitude of biological processes. In this respect, SLRPs play key roles in the evolution of a variety of diseases throughout the human body.

SCOPE OF REVIEW

We will critically review current developments in the roles of SLRPs in several types of disease of the kidney and lungs. Particular emphasis will be given to the roles of decorin and biglycan, the best characterized members of the SLRP gene family.

MAJOR CONCLUSIONS

In both renal and pulmonary disorders, SLRPs are essential elements that regulate several pathophysiological processes including fibrosis, inflammation and tumor progression. Decorin has remarkable antifibrotic and antitumorigenic properties and is considered a valuable potential treatment of these diseases. Biglycan can modulate inflammatory processes in lung and renal inflammation and is a potential target in the treatment of inflammatory conditions.

GENERAL SIGNIFICANCE

SLRPs can serve as either treatment targets or as potential treatment in renal or lung disease. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

ADAM8 in asthma. Friend or foe to airway inflammation?

Airway inflammation has been suggested as the pathological basis in asthma pathogenesis. Recruitment of leukocytes from the vasculature into airway sites is essential for induction of airway inflammation, a process thought to be mediated by a disintegrin and metalloprotease 8 (ADAM8). However, there is an apparent controversy about whether ADAM8 helps or hampers transmigration of leukocytes through endothelium in airway inflammation of asthma. This review outlines the current contradictory concepts concerning the role of ADAM8 in airway inflammation, particularly focusing on the recruitment of leukocytes during asthma, and attempts to bridge the existing experimental data on the basis of the functional analysis of different domains of ADAM8 and their endogenous processing in vivo. We suggest a possible hypothesis for the specific mechanism by which ADAM8 regulates the transmigration of leukocytes to explain the disparity existing in current studies, and we also raise some questions that require future investigations.

Effects of mitochondrial ATP-sensitive K(+) channel on protein kinase C pathway and airway smooth muscle cell proliferation in asthma

The effects of ATP-sensitive mitochondrial K(+) channel (mitoK(ATP)) on mitochondrial membrane potential (Δψm), cell proliferation and protein kinase C alpha (PKCα) expression in airway smooth muscle cells (ASMCs) were investigated. Thirty-six Sprague-Dawley (SD) rats were immunized with saline (controls) or ovalbumin (OVA) with alum (asthma models). ASMCs were cultured from the lung of control and asthma rats. ASMCs were treated with diazoxide (the potent activator of mitoK(ATP)) or 5-hydroxydencanote (5-HD, the inhibitor of mitoK(ATP)). Rhodamine-123 (R-123) was used to detect Δψm. The expression of PKCα protein was examined by using Western blotting, while PKCα mRNA expression was detected by using real-time PCR. The proliferation of ASMCs was measured by MTT assay and cell cycle analysis. In diazoxide-treated normal ASMCs, the R-123 fluorescence intensity, protein and mRNA levels of PKCα, MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls. The ratio of G(0)/G(1) cells was decreased (P<0.05) in diazoxide-treated ASMCs from normal rats. However, there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group. In untreated and diazoxide-treated ASMCs of asthmatic rats, the R-123 fluorescence intensity, protein and mRNA levels of PKCα, MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group. Furthermore, in comparison to ASMCs from asthmatic rats, these values were considerably increased in asthmatic group treated with diazoxide (P<0.05). After exposure to 5-HD for 24 h, these values were decreased as compared with asthma control group (P<0.05). In ASMCs of asthma, the signal transduction pathway of PKCα may be involved in cell proliferation, which is induced by the opening of mitoK(ATP) and the depolarization of Δψm.