Migration of fibrocytes in fibrogenic liver injury.

CD45(+) and collagen I-positive (Col(+)) fibrocytes are implicated in fibrogenesis in skin, lungs, and kidneys. Fibrocyte migration in response to liver injury was investigated using bone marrow (BM) from chimeric mice expressing luciferase (Col-Luc→wt) or green fluorescent protein (Col-GFP→wt) under control of the α1(I) collagen promoter and enhancer, respectively. Monitored by luciferase expression, recruitment of fibrocytes was detected in CCl(4)-damaged liver and in spleen.

Activation of TNFR1 ectodomain shedding by mitochondrial Ca2+ determines the severity of inflammation in mouse lung microvessels.

Shedding of the extracellular domain of cytokine receptors allows the diffusion of soluble receptors into the extracellular space; these then bind and neutralize their cytokine ligands, thus dampening inflammatory responses. The molecular mechanisms that control this process, and the extent to which shedding regulates cytokine-induced microvascular inflammation, are not well defined. Here, we used real-time confocal microscopy of mouse lung microvascular endothelium to demonstrate that mitochondria are key regulators of this process.

Paracrine purinergic signaling determines lung endothelial nitric oxide production.

Although the vascular bed is a major source of nitric oxide (NO) production, factors regulating the production remain unclear. We considered the role played by paracrine signaling. Determinations by fluorescence microscopy in isolated, blood-perfused rat and mouse lungs revealed that a brief lung expansion enhanced cytosolic Ca(2+) (Ca(2+)cyt) oscillations in alveolar epithelial (AEC) and endothelial (EC) cells, and NO production in EC.

Chloride-dependent secretion of alveolar wall liquid determined by optical-sectioning microscopy.

The liquid layer lining the pulmonary alveolar wall critically determines the lung's immune defense against inhaled pathogens, because it provides a liquid milieu in the air-filled alveolus for dispersal of immune cells and defensive surfactant proteins. However, mechanisms underlying formation of the liquid are unknown. We achieved visualization of the alveolar wall liquid (AWL) in situ in mouse lungs by means of optical-sectioning microscopy.

Real-time lung microscopy.

Although proinflammatory cell signaling in the alveolo-capillary region predisposes to acute lung injury, key cell-signaling mechanisms remain inadequately understood. Alveolo-capillary inflammation is likely to involve coordinated signaling among cells of different phenotypes. For example, migration of inflammatory cells into the alveolus might entail coordinated signaling between adjoining alveolar epithelial and microvascular endothelial cells.

Lung surfactant secretion by interalveolar Ca2+ signaling.

Although clusters of alveoli form the acinus, which is the most distal respiratory unit, it is not known whether interalveolar communication coordinates acinar surfactant secretion. To address this, we applied real-time digital imaging in conjunction with photo-excited Ca2+ uncaging in intact alveoli of the isolated, blood-perfused rat lung. We loaded alveolar cells with the Ca2+ cage o-nitrophenyl EGTA-AM (NP-EGTA-AM) together with the fluorophores, fluo 4, or LysoTracker green (LTG) to determine, respectively, the cytosolic Ca2+ concentration ([Ca2+]cyt) or type 2 cell secretion.

Effects of unfractionated heparin, low molecular weight heparin and r-hirudin on leukocyte adhesion in ischemia/reperfusion.

Activation of the coagulation cascade during myocardial ischemia and reperfusion may contribute to the post-ischemic inflammatory response, mostly via generation of thrombin. We assessed the effect of the anticoagulants unfractionated heparin (UFH), low molecular weight heparin (LMWH) and r-hirudin on leukocyte adhesion and emigration after ischemia and reperfusion in rats. The rat cremaster muscle was prepared for intravital microscopy.