Citations

Abstract A donor lung is injured during preservation and is generally thought to be further injured by reperfusion on transplantation. Donor lungs from 15 adult male Lewis rats preserved by flush perfusion with cold Marshall's solution at 4° C were examined by scanning and by quantitative transmission electron microscopy after 2, 4, or 7 h of storage at 4° C and after transplantation (syngeneic) at 4 or 12 h (six animals per time interval). During preservation of the donor lung, capillary morphology changed rapidly. Both endothelial cells and type I pneumonocytes thinned (surface/volume ratio increased by 2 h in both; P < 0.001). Pericapillary edema developed involving the blood-gas barrier. Basement membrane thickness increased significantly (P < 0.001). Occasional breakage of the endothelial cell sheet occurred after 4 h of preservation, but even after 7 h of preservation there was no evidence of irreversible cell damage. The lamellar bodies of type II pneumocytes aggregated. Changes increased in severity with increase in preservation time. After transplantation, type I and type II pneumonocytes recovered after 12 h, but it took longer for the endothelial cell morphology to recover. Edema decreased rapidly during the first 4 h, despite the number of adherent neutrophils increasing 3-fold. The pulmonary capillaries of the transplanted lung showed no structural evidence of additional reperfusion injury, indicating a satisfactory method of preservation.

Abstract Fibulin is a newly described extracellular matrix (ECM) glycoprotein whose function has not been elucidated. We have observed that cultured fetal lung fibroblasts produce fibulin and have postulated that its expression may be important during lung development. To begin to understand the potential function of fibulin in lung development, we examined its expression and distribution in cultured fetal lung fibroblasts. Immunofluorescence staining of cultured fibroblasts revealed that fibulin was distributed upon their surface in a fibrillar array resembling fibronectin (FN), another ECM glycoprotein expressed by fetal lung fibroblasts and implicated in lung and heart development. Detection of fibulin by immunofluorescence staining of nonpermeabilized cells, its immunoprecipitation from 125I-cell surface-labeled fibroblasts, pulse-chase analysis, and temperature-induced phase separation studies revealed that fibulin is an ECM peripheral membrane protein that is synthesized and secreted by cultured fetal lung fibroblasts shortly after plating and incorporated into their matrix in a divalent cation-dependent manner. Because fibulin co-distributes with both FN and the FN receptor, the integrin α5β1, we examined the possibility that fibulin was interacting with both components. Dissociation of FN receptors from FN fibers with anti-FN receptor antibodies did not affect fibulin's distribution, suggesting that fibulin binds FN and that this interaction is not affected by the state of FN receptor binding. Finally, inhibition of FN matrix assembly prevented the deposition of fibulin, providing further support for FN-fibulin interactions and suggesting that fibulin deposition is dependent on FN matrix assembly.

Abstract Adenosine 5′-triphosphate (ATP) is released from the cytoplasm under physiologic and pathophysiologic conditions and enters the extracellular space, where it acts on a group of recently cloned cell-surface receptors termed P2-purinoceptors (subtypes P2X and P2Y). We examined the effects of extracellular ATP, uridine triphosphate (UTP), the stable ATP analogues α,βmethylene-ATP (α,βmATP), β,γmethylene-ATP (β,γmATP), and 2-methylthio-ATP (2mSATP), and adenosine (10−6–10−3 M) on histamine release from human lung mast cells (HLMC) induced by anti-IgE and the calcium ionophore A23187. None of the nucleotides or adenosine directly induced histamine release. Adenosine exhibited a bimodal effect, enhancing histamine release at 10−6 to 10−4 M (P > 0.05, NS) and inhibiting it at 10−3 M (P < 0.05). ATP (10−4 M) enhanced anti-IgE–induced histamine release (10.9 ± 2.7% to 19.2 ± 2.9%, n = 20, P < 0.01), but not ionophore A23187-induced histamine release (n = 10). The adenine nucleotides consistently enhanced anti-IgE–induced histamine release; the rank order for this action was: ATP > 2mSATP > α,βmATP > β,γmATP, suggesting mediation by a P2Y-purinoceptor subtype. The selective P2X purinoceptor antagonist pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid failed to influence the effect of ATP, further supporting P2Y-purinoceptor mediation of anti-IgE–induced histamine release. UTP, an agonist at P2Y-purinoceptors, also significantly enhanced anti-IgE–induced histamine release. Application of the reverse transcription–polymerase chain reaction indicated that HLMC constitutively express the messenger RNAs encoding the P2Y1- and P2Y2-purinoceptor subtypes, and not that encoding the P2X7-purinoceptor (i.e., P2Z), a subtype implicated in ATP-induced histamine release in rodent peritoneal mast cells. The data produced in the study suggest that ATP plays an important modulatory role in histamine release from HLMC, and that it may therefore be mechanistically involved in human allergic/asthmatic reactions.