Sadatomo Tasaka

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.

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.

Pneumocystis jirovecii pneumonia in non-HIV-infected patients in the era of novel immunosuppressive therapies

In human immunodeficiency virus (HIV)-infected patients, Pneumocystis jirovecii pneumonia (PCP) is a well-known opportunistic infection, and its management has been established. However, PCP is an emerging threat to immunocompromised patients without HIV infection, such as those receiving novel immunosuppressive therapeutics for malignancy, organ transplantation, or connective tissue diseases. Clinical manifestations of PCP are quite different between patients with and without HIV infections. In patients without HIV infection, PCP rapidly progresses, is difficult to diagnose correctly, and causes severe respiratory failure with a poor prognosis. High-resolution computed tomography findings are different between PCP patients with HIV infection and those without. These differences in clinical and radiologic features are the result of severe or dysregulated inflammatory responses that are evoked by a relatively small number of Pneumocystis organisms in patients without HIV infection. In recent years, the usefulness of PCR and serum β-d-glucan assay for rapid and noninvasive diagnosis of PCP has been revealed. Although corticosteroid adjunctive to anti-Pneumocystis agents has been shown to be beneficial in some populations, the optimal dose and duration remain to be determined. Recent investigations revealed that Pneumocystis colonization is prevalent, and that asymptomatic carriers are at risk for developing PCP and can serve as the reservoir for the spread of Pneumocystis by person-to-person transmission. These findings suggest the need for chemoprophylaxis in immunocompromised patients without HIV infection, although its indication and duration are still controversial. Because a variety of novel immunosuppressive therapeutics have been emerging in medical practice, further innovations in the diagnosis and treatment of PCP are needed.

Clinical and immunoregulatory effects of roxithromycin therapy for chronic respiratory tract infection.

The clinical and immunoregulatory effects of long-term macrolide antibiotic therapy for patients with chronic lower respiratory tract infections (CLRTI) were investigated. Clinical parameters and neutrophil chemotactic mediators in the epithelial lining fluid (ELF) of CLRTI patients (n = 10) were examined before and after 3 months oral administration of roxithromycin (RXM). The in vitro effects of RXM were also examined on the release of these mediators from alveolar macrophages (AM) and neutrophils. Arterial oxygen tension (p<0.05), vital capacity (VC) (p<0.001), %VC (p<0.05) and forced expiratory volume in one second (p<0.01) were improved after RXM treatment, but airway bacteria were not eradicated. Among the mediators, the levels of interleukin (IL)-8, neutrophil elastase (NE) and leukotriene B4 (LTB4) were higher in ELF than in plasma of CLRTI patients and they decreased after RXM treatment (n = 7, p<0.05 for each). RXM concentrations were significantly increased in the bronchoalveolar lavage cells of the treated patients. In in vitro experiments, RXM showed inhibitory effects on IL-8 release from AM and neutrophils. In conclusion, interleukin-8, neutrophil elastase and leukotriene B4 contribute to the neutrophilic inflammation in the airways of chronic lower respiratory tract infection patients and the clinical effects of roxithromycin may, in part, be attributable to the suppression of excess release of the chemotactic mediators from inflammatory cells.

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.

Therapeutic Effects of Various Initial Combinations of Chemotherapy Including Clarithromycin Against Mycobacterium avium Complex Pulmonary Disease

BACKGROUND The objective of this study was to find an optimal initial combination chemotherapy that includes clarithromycin (CAM) for treatment-naive patients with Mycobacterium avium complex (MAC) pulmonary disease, as assessed by microbiological conversion using a Mycobacterium growth indicator tube (MGIT). METHODS Thirty-four patients with treatment-naive MAC pulmonary disease (determined using 1997 American Thoracic Society criteria) were evaluated retrospectively. They demonstrated a nodular and bronchiectatic pattern without cavity on high-resolution CT (HRCT) scans. The following three regimens were administered: regimen A (n = 9) consisted of CAM (400 mg/d), ethambutol (EB) [750 mg/d], and rifampicin (RFP) [450 mg/d]; regimen B (n = 12) consisted of CAM (800 mg/d), EB (750 mg/d), and RFP (450 mg/d); and regimen C (n = 13) consisted of CAM (800 mg/d), EB (1,000 mg/d), and RFP (600 mg/d) during the first 2 months followed by a reduction of the dosage of EB from 1,000 to 750 mg/d. Gender, age, BMI, and HRCT scan finding scores were not significantly different among the three groups. Chemotherapy was continued for 18 months. Sputum culture was periodically assessed by MGIT. RESULTS Culture conversion at 18 months in regimen A (55.6%), which included a daily dosage of 400 mg of CAM (9.5 mg/kg), was significantly inferior to that in regimen B (91.7%), which included daily 800 mg of CAM (17.6 mg/kg; p < 0.05), but regimen B and C (92.3%) showed no between-group difference after > 18 months of chemotherapy. CONCLUSIONS The higher dose of CAM allowed for better culture conversion. Daily combination chemotherapy that includes CAM (800 mg) seems appropriate as an initial treatment against treatment-naive patients with nodular and bronchiectatic MAC pulmonary disease.

CRTH2 Is A Critical Regulator of Neutrophil Migration and Resistance to Polymicrobial Sepsis

Although arachidonic acid cascade has been shown to be involved in sepsis, little is known about the role of PGD2 and its newly found receptor, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2), on the septic response. Severe sepsis is associated with the failure of neutrophil migration. To investigate whether CRTH2 influences neutrophil recruitment and the lethality during sepsis, sepsis was induced by cecal ligation and puncture (CLP) surgery in mice. CRTH2 knockout (CRTH2−/−) mice were highly resistant to CLP-induced sepsis, which was associated with lower bacterial load and lower production of TNF-α, IL-6, and CCL3. IL-10, an anti-inflammatory cytokine, was higher in CRTH2−/− mice, blunting CLP-induced lethality in CRTH2−/− mice. Neutrophil accumulation in the peritoneum was more pronounced after CLP in CRTH2−/− mice, which was associated with higher CXCR2 levels in circulating neutrophils. Furthermore, sepsis caused a decrease in the level of acetylation of histone H3, an activation mark, at the CXCR2 promoter in wild-type neutrophils, suggesting that CXCR2 expression levels are epigenetically regulated. Finally, both pharmacological depletion of neutrophils and inhibition of CXCR2 abrogated the survival benefit in CRTH2−/− mice. These results demonstrate that genetic ablation of CRTH2 improved impaired neutrophil migration and survival during severe sepsis, which was mechanistically associated with epigenetic-mediated CXCR2 expression. Thus, CRTH2 is a potential therapeutic target for polymicrobial sepsis.

Role of Toll-like receptor 4 in hyperoxia-induced lung inflammation in mice.

Abstract.Objective:Prolonged exposure to hyperoxia causes lung inflammation, but the role of Toll-like receptor 4 (TLR4) in hyperoxia-induced signal transduction remains unclear.Material or subjects:We evaluated neutrophil accumulation, signal transduction and cytokine production during hyperoxia, comparing TLR4 mutant (C3H/HeJ) and wild type (C3H/HeN) mice.Methods:The mice were exposed to 80% oxygen in a hyperoxic chamber for 0 (control), 48, or 96 h. After the exposure, bronchoalveolar lavage (BAL) was performed for differential cell counting and cytokine measurement. In lung homogenate, activation of NF-κB and STAT1 was also examined.Results:In C3H/HeJ mice, hyperoxia-induced neutrophil accumulation in BAL fluid was significantly decreased compared with C3H/HeN. Hyperoxia for 96 h caused NF-κB translocation in C3H/HeN mice, which was significantly attenuated in C3H/HeJ mice (p < 0.05). In contrast, STAT1 activation occurred as early as after 48 h of oxygen exposure, which did not differ between the two strains. The levels of TNF-α, IL-6, and KC in BAL fluid were increased after oxygen exposure, which was suppressed by the lack of TLR4 signaling.Conclusion:These results suggest that TLR4-dependent NF-kB activation may be an important process of the upregulation of proinflammatory mediators and subsequent neutrophil accumulation into the lung during hyperoxia.