Acute lung injury (ALI), which is associated with a mortality of 30-40%, is attributable to inflammation that develops rapidly across the lung's vast vascular surface, involving an entire lung or even both lungs. No specific mechanism explains this extensive inflammatory spread, probably because of the lack of approaches for detecting signal conduction in lung capillaries. Here, we addressed this question by applying the photolytic uncaging approach to induce focal increases in Ca 2+ levels in targeted endothelial cells of alveolar capillaries. Uncaging caused Ca 2+ levels to increase not only in the targeted cell, but also in vascular locations up to 150 mm from the target site, indicating that Ca 2+ was conducted from the capillary to adjacent vessels. No such conduction was evident in mouse lungs lacking endothelial connexin 43 (Cx43), or in rat lungs in which we pretreated vessels with peptide inhibitors of Cx43. These findings provide the first direct evidence to our knowledge that interendothelial Ca 2+ conduction occurs in the lung capillary bed and that Cx43-containing gap junctions mediate the conduction. A proinflammatory effect was evident in that induction of increases in Ca 2+ levels in the capillary activated expression of the leukocyte adherence receptor P-selectin in venules. Further, peptide inhibitors of Cx43 completely blocked thrombin-induced microvascular permeability increases. Together, our findings reveal a novel role for Cx43-mediated gap junctions, namely as conduits for the spread of proinflammatory signals in the lung capillary bed. Gap junctional mechanisms require further consideration in the understanding of ALI.

One of the grant numbers in the Acknowledgments section was incorrect.The correct Acknowledgments section follows.For initial studies, gap peptides were provided by Scott Boitano, University of Arizona. This project was supported by NIH grants HL75503 to K. Parthasarathi and HL57556 and HL36024 to J. Bhattacharya.The authors regret this error.

Alveolar type 2 (AT2) cells secrete surfactant that forms a protective layer on the lung's alveolar epithelium. Vesicles called lamellar bodies (LBs) store surfactant. Failure of surfactant secretion, which causes severe lung disease, relates to the manner in which LBs undergo exocytosis during the secretion. However, the dynamics of LBs during the secretion process are not known in intact alveoli. Here, we addressed this question through real-time confocal microscopy of single AT2 cells in live alveoli of mouse lungs. Using a combination of phospholipid and aqueous fluorophores that localize to LBs, we induced surfactant secretion by transiently hyperinflating the lung, and we quantified the secretion in terms of loss of bulk LB fluorescence. In addition, we quantified inter-LB phospholipid flow through determinations of fluorescence recovery after photobleaching. Furthermore, we determined the role of F-actin in surfactant secretion through expression of the fluorescent F-actin probe Lifeact. Our findings indicate that, in AT2 cells in situ, LBs are held in an F-actin scaffold. Although F-actin transiently decreases during surfactant secretion, the LBs remain stationary, forming a chain of vesicles connected by intervesicular channels that convey surfactant to the secretion site on the plasma membrane. This is the first instance of a secretory process in which the secretory vesicles are immobile, but form a conduit for the secretory material.

Westphalen K, Monma E, Islam MN, Bhattacharya J. Acid contact in the rodent pulmonary alveolus causes proinflammatory signaling by membrane pore formation. Am J Physiol Lung Cell Mol Physiol 303: L107-L116, 2012. First published May 4, 2012 doi:10.1152/ajplung.00206.2011Although gastric acid aspiration causes rapid lung inflammation and acute lung injury, the initiating mechanisms are not known. To determine alveolar epithelial responses to acid, we viewed live alveoli of the isolated lung by fluorescence microscopy, then we microinjected the alveoli with HCl at pH of 1.5. The microinjection caused an immediate but transient formation of molecule-scale pores in the apical alveolar membrane, resulting in loss of cytosolic dye. However, the membrane rapidly resealed. There was no cell damage and no further dye loss despite continuous HCl injection. Concomitantly, reactive oxygen species (ROS) increased in the adjacent perialveolar microvascular endothelium in a Ca 2ϩ -dependent manner. By contrast, ROS did not increase in wild-type mice in which we gave intraalveolar injections of polyethylene glycol (PEG)-catalase, in mice overexpressing alveolar catalase, or in mice lacking functional NADPH oxidase (Nox2). Together, our findings indicate the presence of an unusual proinflammatory mechanism in which alveolar contact with acid caused membrane pore formation. The effect, although transient, was nevertheless sufficient to induce Ca 2ϩ entry and Nox2-dependent H2O2 release from the alveolar epithelium. These responses identify alveolar H2O2 release as the signaling mechanism responsible for lung inflammation induced by acid and suggest that intra-alveolar PEG-catalase might be therapeutic in acid-induced lung injury.calcium; hydrogen peroxide; nitric oxide synthase 2; nitric oxide; reactive oxygen species; catalase; flash photolysis; resealing; clodronate THE GASTRIC AND THE PULMONARY epithelial surfaces are potentially exposed to highly concentrated HCl. The gastric epithelium secretes the acid at pH 1-2; the pulmonary epithelium encounters the acid following aspiration of gastric contents. Although a 200-m-thick mucus layer protects the gastric epithelium from acid injury (4), the much thinner layer of surfactant (6) is likely to provide relatively little protection to alveoli. Large aspirations cause severe lung inflammation, leading to acute lung injury (ALI) that associates with high mortality and morbidity (21). Mild aspirations prime the lung for secondary pneumonitis (30,34). No specific treatment is available for acid-induced ALI.An unsolved problem in the understanding of acid-induced ALI relates to the question of how the injury initiates following the first contact of acid with the alveolar membrane. Particularly lacking is the absence of studies defining the immediate alveolar response to the acid contact. Although animal studies confirm that airway instillation of highly concentrated acid (pH Ͻ2) causes ALI, these studies have largely focused on lung responses occurring well after the injury has alread...

BackgroundAlthough recent trends in laparoscopic procedures have been toward minimizing the number of incisions, four or five ports are normally required to complete laparoscopic gastrectomy because of the complexity of this procedure. Multi-channel ports, such as the SILS port (Covidien, JAPAN), are now available and are crucial for performing single-incision laparoscopic surgery (SILS) or reduced port surgery (RPS). We carried out reduced port distal gastrectomy (RPDG) using a dual-port method with a SILS port.MethodsTen patients who were diagnosed as early stage gastric cancer were offered the RPDG. Mean age and body mass index (BMI) were 68.1 and 21.4, respectively. No distant metastasis or regional lymph node swelling was seen in any case. A 5-mm flexible scope (Olympus, JAPAN) and SILS port were used and a nylon ligature with a straight needle, instead of a surgical instrument, was available to raise the gastric wall.ResultsThe average operative time was 266.9 ± 38.3 min and blood loss was 37.8 ± 56.8 ml. Patients recovered well and experienced no complications after surgery. All patients could tolerate soft meals on the first day after surgery and the average hospital stay was 8.1 days. Past conventional LAG cases were evaluated to compare the short-term outcome and no difference was seen in the mean operative time or operative blood loss. The length of hospital stay after surgery was shorter for the RPDG group than the conventional operation group (p < 0.0001). Interestingly, the trend of serum CRP elevation after surgery was lower in the RPDG group than the conventional LAG group (p = 0.053).Conclusions Although the benefits of RPS have not been established, this type of surgery may be expected to have some advantages. Cosmetic benefits and shorter hospital stays are clear advantages. Less invasiveness can be expected according to the trend of serum CRP elevation after RPDG.