Akitoshi Ishizaka

Role of soluble receptor for advanced glycation end products on endotoxin-induced lung injury

RATIONALE The interaction of receptor for advanced glycation end products (RAGE) and its ligands often leads to inflammatory processes or tissue injury, although the effect of the blockade of RAGE signaling on lung injury remains to be investigated. OBJECTIVES Using a murine model of lung injury induced by intratracheal lipopolysaccharide (LPS), we evaluated RAGE expression in the airspace and the effect of recombinant soluble RAGE (sRAGE) on LPS-induced lung injury. METHODS First, the expression of sRAGE in bronchoalveolar lavage (BAL) fluid was determined at 24 hours after intratracheal instillation of LPS or phosphate-buffered saline. Next, to evaluate the effect of sRAGE, BAL fluid was collected for cell counting and measurements of lung permeability and cytokine concentrations 24 hours after intratracheal LPS in the mice with or without intraperitoneal administration of sRAGE 1 hour after the instillation. In another series, lungs were sampled for histopathology and detection of apoptotic cells. The activation of nuclear factor (NF)-kappaB was analyzed 4 hours after LPS instillation. MEASUREMENTS AND MAIN RESULTS In response to LPS challenge, a RAGE isoform of 48 kD was detected in the BAL fluid. Treatment with sRAGE significantly attenuated the increases in neutrophil infiltration, lung permeability, production of inflammatory cytokines, NF-kappaB activation, and apoptotic cells in the lung as well as development of pathologic changes after LPS instillation. CONCLUSIONS RAGE plays an important role in the pathogenesis of LPS-induced lung injury in mice. It was suggested that sRAGE should be tested as a treatment modality in other models of acute lung injury.

Plasma biomarker profiles in acute exacerbation of idiopathic pulmonary fibrosis

Little is known about the pathobiology of acute exacerbation of idiopathic pulmonary fibrosis (IPF), a condition that shares clinical and histopathological features with acute lung injury. Plasma biomarkers have been well studied in acute lung injury and have provided insight into the underlying disease mechanism. The objective of this study was to determine the plasma biomarker profile of acute exacerbation of IPF and compare this profile with that of stable IPF and acute lung injury. Plasma was collected from patients with stable IPF, acute exacerbation of IPF, and acute lung injury for measurement of biomarkers of cellular activity/injury (receptor for advanced glycation endproducts, surfactant protein D, KL-6, von Willebrand factor), systemic inflammation (IL-6), and coagulation/fibrinolysis (protein C, thrombomodulin, plasminogen activator inhibitor-1). Plasma from patients with acute exacerbation of IPF showed significant elevations in markers of type II alveolar epithelial cell injury and/or proliferation, endothelial cell injury, and coagulation. This profile differed from the biomarker profile in patients with acute lung injury. These findings support the hypothesis that type II alveolar epithelial cells are centrally involved in the pathobiology of acute exacerbation of IPF. Furthermore, they suggest that acute exacerbation of IPF has a distinct plasma biomarker profile from that of acute lung injury.

Infusion of the β-adrenergic blocker esmolol attenuates myocardial dysfunction in septic rats*

Objective:Since &bgr;-blocker therapy is known to be effective in patients with an injured heart, such as infarction, we designed the present study to examine the protective effects of infusion of the &bgr;1-selective blocker esmolol on myocardial function in peritonitis-induced septic rats using an isolated working heart preparation. Design:Randomized animal study. Setting:University research laboratory. Subjects:Thirty-one rats treated with cecal ligation and perforation to evoke peritonitis. Interventions:After cecal ligation and perforation, rats were randomly allocated to the control group (normal saline 2 mL/hr, n = 11), low-dose esmolol group (10 mg/kg/hr, n = 10), or high-dose esmolol group (20 mg/kg/hr, n = 10). After obtaining blood samples for measurement of arterial lactate and tumor necrosis factor-&agr; at 24 hrs, we assessed cardiac output, myocardial oxygen consumption, and cardiac efficiency (cardiac output × peak systolic pressure/myocardial oxygen consumption) at various preloads in an isolated perfused heart preparation. Measurements and Main Results:Esmolol infusion did not cause an elevation of arterial lactate levels but reduced tumor necrosis factor-&agr; concentrations vs. the control group (p < .05). Both cardiac output and cardiac efficiency in the esmolol-treated rats were significantly higher throughout the study periods vs. the control group (p < .05). Conclusions:Esmolol infusion in sepsis improved oxygen utilization of myocardium and preserved myocardial function.

New bronchoscopic microsample probe to measure the biochemical constituents in epithelial lining fluid of patients with acute respiratory distress syndrome

ObjectiveA noninvasive bronchoscopic microsampling (BMS) probe was developed to sample biochemical constituents of the epithelial lining fluid in small airways. DesignObservational, controlled study. SettingIntensive care unit of academic medical center. Patients and Procedure BMS was applied in a control group of seven patients who had hemoptysis or small solitary peripheral nodules but no hypoxemia or other signs of acute inflammation and in four patients with acute respiratory distress syndrome (ARDS), to test whether BMS can ascertain the presence of acute pulmonary inflammation without complications. Measurements and Results Complications, including a significant decrease in arterial oxygen saturation, were observed neither during nor after BMS. In the ARDS group, albumin, lactate dehydrogenase, interleukin-6, basic fibroblast growth factor, and neutrophil elastase concentrations in epithelial lining fluid were significantly higher (p < .0001, p = .012, p < .0001, p < .0001, and p < .0001, respectively) than in the control group. Serial BMS was safely performed in one patient with ARDS, allowing us to observe a correlation between changes in the concentration of inflammation-related biochemical markers and clinical course of the disease. ConclusionsThese results suggest that BMS is safe and useful to monitor pulmonary biochemical events in ARDS.

Roles of oxidants and redox signaling in the pathogenesis of acute respiratory distress syndrome.

The acute respiratory distress syndrome (ARDS) is a disease process that is characterized by diffuse inflammation in the lung parenchyma and resultant permeability edema. The involvement of inflammatory mediators in ARDS has been the subject of intense investigation, and oxidant-mediated tissue injury is likely to be important in the pathogenesis of ARDS. In response to various inflammatory stimuli, lung endothelial cells, alveolar cells, and airway epithelial cells, as well as alveolar macrophages, produce reactive oxygen species (ROS) and reactive nitrogen species (RNS). In addition, the therapeutic administration of oxygen can enhance the production of these toxic species. As the antioxidant defense system, various enzymes and low-molecular weight scavengers are present in the lung tissue and epithelial lining fluid. In addition to their contribution to tissue damage, ROS and RNS serve as signaling molecules for the evolution and perpetuation of the inflammatory process, which involves genetic regulation. The pattern of gene expression mediated by oxidant-sensitive transcription factors is a crucial component of the machinery that determines cellular responses to oxidative stress. This review summarizes the recent progress concerning how redox status can be modulated and how it regulates gene transcription during the development of ARDS, as well as the therapeutic implications.

High-Mobility Group Box 1 Contributes to Lethality of Endotoxemia in Heme Oxygenase-1–Deficient Mice

High-mobility group box 1 (HMGB1) is a nuclear protein that has been found to be a critical mediator of lethality in endotoxemia and sepsis. During the systemic inflammatory response, circulating levels of HMGB1 are increased, but in a delayed fashion compared with early inflammatory mediators. To counteract the inflammatory response of endotoxemia, a secondary anti-inflammatory response ensues in an attempt to prevent inflammation-induced tissue injury. One such cytoprotective gene that is induced during endotoxemia is heme oxygenase (HO)-1. HO-1, and its products of heme metabolism, possess anti-inflammatory and antioxidant properties to counter the damaging effects of endotoxemia. In the present study, we wanted to determine whether tissue and circulating levels of HMGB1 are increased further in the absence of HO-1 during endotoxemia, and whether this increase may contribute to the pathobiology of endotoxemia. Lung inflammation, HMGB1 protein levels, and expression of HMGB1 in inflammatory cells were increased in HO-1(-/-) mice compared with HO-1+/+ mice. After the administration of LPS, tissue levels of HMGB1 were not increased further in HO-1(-/-) mice; however, circulating levels of HMGB1 were higher when compared with HO-1+/+ mice. HO-1(-/-) mice treated with a carbon monoxide-releasing molecule or biliverdin showed a reduction in plasma HMGB1, which was associated with a marked improvement in survival. HO-1(-/-) mice given HMGB1-neutralizing antibody showed improvement in survival compared with control antibody. These data suggest that exaggerated circulating levels of HMGB1 contribute to endotoxin-induced mortality in the absence of HO-1.

Effects of Pulmonary Exposure to Carbon Nanotubes on Lung and Systemic Inflammation with Coagulatory Disturbance Induced by Lipopolysaccharide in Mice

Despite intensive research as to the pathogenesis of lipopolysaccharide (LPS)-related inflammation with coagulatory disturbance, their exacerbating factors have not been well explored. This study examined the effects of pulmonary exposure to two types of nano-sized materials (carbon nano-tubes: CNT [single-wall: SWCNT, and multi-wall: MWCNT]) on lung inflammation and consequent systemic inflammation with coagulatory disturbance induced by pulmonary exposure to LPS in mice and their cellular mechanisms in vitro. ICR male mice were divided into 6 experimental groups that intra-tracheally received the vehicle, two types of CNT (4 mg/kg), LPS (33 μ g/kg), or LPS plus either type of CNT. Twenty-four hours after treatment, both types of CNT alone induced lung inflammation with enhanced lung expression of proinflammatory cytokines, but did not synergistically exacerbate lung inflammation elicited by LPS. SWCNT significantly induced/ enhanced pulmonary permeability and hyperfibrinogenemia and reduced activated protein C in the absence or presence of LPS, whereas MWCNT did moderately. Both CNT moderately, but not significantly, elevated circulatory levels of proinflammatory cytokines and chemokines. In the presence of LPS, CNT tended to elevate the levels of the mediators with an overall trend, which was more prominent with SWCNT than with MWCNT. In vitro study showed that both CNT amplified LPS-induced cytokine production from peripheral blood monocytes. These results suggest that CNT can facilitate systemic inflammation with coagulatory disturbance, at least in part, via the activation of mononuclear cells, which is accompanied by moderate enhancement of acute lung inflammation related to LPS.

Production and Activation of Matrix Metalloproteinase 7 (Matrilysin 1) in the Lungs of Patients With Idiopathic Pulmonary Fibrosis

CONTEXT Idiopathic pulmonary fibrosis (IPF) is characterized by diffuse interstitial inflammation and fibroblast proliferation with accelerated remodeling of extracellular matrix, which result in irreversible destruction of the lungs architecture. OBJECTIVE To elucidate the production levels, tissue localization, and activation of matrix metalloproteinase 7 (MMP-7) in the lungs of patients with IPF. DESIGN Bronchoalveolar lavage analysis was performed in 17 IPF patients and 6 healthy volunteers. Levels of MMP-7 in blood were assayed in 23 IPF patients and 20 controls. Histologic and immunohistochemical analyses were performed on paraffin sections of the lung tissues from patients with IPF, interstitial pneumonia associated with rheumatoid arthritis, or nonspecific interstitial pneumonia. RESULTS The proMMP-7 levels in bronchoalveolar lavage fluids from IPF patients were significantly higher than those from healthy controls, although there was no difference in the serum levels between the 2 groups. By immunohistochemistry, proMMP-7 was localized mainly to the hyperplastic alveolar and metaplastic bronchiolar epithelial cells in the lung tissues from IPF patients. Active MMP-7 was immunolocalized on alveolar macrophages and hyperplastic epithelial cells, which were also immunostained with antibody against CD151, a molecule associated with activation of proMMP-7. Immunoblot analysis indicated the overproduction of proMMP-7 together with a small amount of active MMP-7 in bronchoalveolar lavage fluids from IPF patients. The MMP-7 activity was detected in a cross-linked carboxymethylated transferrin film assay. CONCLUSIONS proMMP-7 is excessively produced by hyperplastic alveolar and metaplastic bronchiolar epithelial cells and activated locally in the lungs of IPF patients, suggesting that MMP-7 may contribute to the pathology of IPF.

Elevated CC Chemokine Level in Bronchoalveolar Lavage Fluid Is Predictive of a Poor Outcome of Idiopathic Pulmonary Fibrosis

Background: CC chemokines play important roles in the pathogenesis of interstitial lung diseases. Elevated CC chemokine levels have been observed in bronchoalveolar lavage (BAL) fluid of patients with idiopathic pulmonary fibrosis (IPF). Objectives:We aimed to examine whether the levels of four CC chemokines, i.e. monocyte chemoattractant protein-1 (MCP-1/CCL2), macrophage inflammatory protein-1α (MIP-1α/CCL3), thymus- and activation-regulated chemokine (TARC/CCL17), and macrophage-derived chemokine (MDC/CCL22), in BAL fluid are predictive of the prognosis of IPF patients. Methods: We compared the chemokine levels of patients alive 5 years after diagnosis and those who had died. Lung function data, CT scores, and serum markers were also compared. Results: Among 39 patients (29 males, median age, 60 years), 19 patients (48%) died within 5 years after the diagnosis. Whereas percent vital capacity was not different, percent lung diffusion capacity for carbon monoxide was significantly higher in the surviving patients than in the nonsurviving patients (p < 0.01). Median CCL2 levels of surviving and nonsurviving patients were 154.3 (interquartile range, IQR: 67.3–381.8) and 427.2 (IQR: 329.2–1184.1) pg/ml, respectively (p < 0.02). CCL3 levels in BAL fluid did not differ between the surviving and nonsurviving patients. CCL17 was detected in BAL fluid of 7 patients, 6 of whom died within 5 years. CCL22 was detectable in BAL fluid of 10 patients, only 1 of whom survived. Serum levels of KL-6 and lactate dehydrogenase did not differ between the surviving and nonsurviving patients. Conclusion: Elevated levels of CCL2, CCL17 and CCL22 in BAL fluid might be predictive of a poor outcome in patients with IPF.

Gradual Increase of High Mobility Group Protein B1 in the Lungs after the Onset of Acute Exacerbation of Idiopathic Pulmonary Fibrosis

The pathogenesis of acute exacerbation of idiopathic pulmonary fibrosis (IPF) remains to be elucidated. To evaluate the roles of inflammatory mediators in acute exacerbation, the concentrations of high mobility group protein B1 (HMGB1), a chief mediator of acute lung injury, and 18 inflammatory cytokines were measured in the bronchoalveolar lavage fluid, serially sampled from seven IPF patients after the onset of acute exacerbation. HMGB1 gradually increased in the alveolar fluid after the onset of acute exacerbation, in positive correlation with monocytes chemotactic protein-1 (MCP-1), a potent fibrogenic mediator. In the lung tissues of eight IPF patients autopsied after acute exacerbation, intense cytoplasmic staining for HMGB1 was observed in the alveolar epithelial cells in alveolar capillary augmented lesions, where the capillary endothelial cells remarkably reduced the expression of thrombomodulin, an intrinsic antagonist of HMGB1. These results suggest pathogenic roles for HMGB1 and MCP-1 in the late phase of acute exacerbation of IPF.