Ichiro Yokomura

Spiral CT findings in septic pulmonary emboli

OBJECTIVES The aim of the study was to determine the characteristics of septic pulmonary emboli and their prevalence on spiral computed tomographic (CT) scans. METHODS AND MATERIALS We evaluated 65 lesions on spiral CT scans in ten patients with septic pulmonary emboli. Spiral CT scans (10-mm collimation) were obtained at 10-mm intervals from the lung apex to the diaphragm and were compared with posteroanterior chest radiographs obtained within 24 h after CT scanning. RESULTS Only 21 (32%) of the 65 lesions detected on CT scans were also detected on chest radiographs. Peripheral nodules (39 lesions (60%)) were seen in all ten patients, wedge-shaped peripheral lesions (15 lesions (23%)) in nine patients, and infiltrates (11 lesions (17%)) in four patients. Subpleural lesions (45 lesions (69%)) and feeding vessels (35 (54%)) were found in all patients, and cavitary lesions (seven lesions (11%)) were seen in four patients. Subpleural peripheral nodules and wedge-shaped peripheral lesions were seen in nine patients. Thirty-two lesions (49%) ranged in diameter from 10 to 19 mm, and 59 lesions (91%) were less than 30 mm. CONCLUSIONS Spiral CT is useful in detecting septic pulmonary emboli. On spiral CT subpleural peripheral nodules and wedge-shaped peripheral lesions less than 30 mm in diameter are often found in patients with septic pulmonary emboli.

ROLE OF INTERCELLULAR ADHESION MOLECULE 1 IN ACUTE LUNG INJURY INDUCED BY CANDIDEMIA

Candidemia, a complication often affecting immunocompromised patients, is a common cause of acute lung injury. Yeast-phase Candida albicans has been shown to express a protein that is antigenically and structurally related to Mac-1. C. albicans is reported to stimulate intercellular adhesion molecule 1 (ICAM-1)expression on endothelial cells. In this study, the authors examined the role of ICAM-1 in acute lung injury induced by candidemia. The authors cultured rat pulmonary artery endothelial cells (RPAEC)and investigated the effect of anti-ICAM-1antibodies on adhesion of C. albicans to RPAEC. In addition, the authors administered anti-ICAM-1 antibodies to rats to examine the effect of the antibodies on experimentally induced candidemia. Survival rates, lung wet-to-dry (W/D) weight ratios, bronchoalveolar lavage (BAL) fluid, histopathological findings, and colony-forming units (CFUs)of lung C. albicans were examined. The adherence of C. albicans to RPAEC was significantly decreased by anti-ICAM-1 antibodies. Anti-ICAM-1 antibodies significantly increased survival, decreased lung W/D weight ratios, decreased neutrophil counts in the BAL fluid, reduced microscopic lung injury, and decreased the quantity of lung C. albicans. These results indicate that ICAM-1plays a role in adherence of C. albicans to pulmonary vascular endothelial cells, which likely leads to invasion of lung tissue by the organism.Candidemia, a complication often affecting immunocompromised patients, is a common cause of acute lung injury. Yeast-phase Candida albicans has been shown to express a protein that is antigenically and structurally related to Mac-1. C. albicans is reported to stimulate intercellular adhesion molecule 1 (ICAM-1) expression on endothelial cells. In this study, the authors examined the role of ICAM-1 in acute lung injury induced by candidemia. The authors cultured rat pulmonary artery endothelial cells (RPAEC) and investigated the effect of anti-ICAM-1 antibodies on adhesion of C. albicans to RPAEC. In addition, the authors administered anti-ICAM-1 antibodies to rats to examine the effect of the antibodies on experimentally induced candidemia. Survival rates, lung wet-to-dry (W/D) weight ratios, bronchoalveolar lavage (BAL) fluid, histopathological findings, and colony-forming units (CFUs) of lung C. albicans were examined. The adherence of C. albicans to RPAEC was significantly decreased by anti-ICAM-1 antibodies. Anti-ICAM-1 antibodies significantly increased survival, decreased lung W/D weight ratios, decreased neutrophil counts in the BAL fluid, reduced microscopic lung injury, and decreased the quantity of lung C. albicans. These results indicate that ICAM-1 plays a role in adherence of C. albicans to pulmonary vascular endothelial cells, which likely leads to invasion of lung tissue by the organism.

Role of Alveolar Macrophages in Candida-Induced Acute Lung Injury

ABSTRACT Recent studies have shown that alveolar macrophages (AMs) not only act as phagocytes but also play a central role as potent secretory cells in various lung diseases, including pneumonia and acute respiratory distress syndrome. The behavior of AMs during disseminated candidiasis, however, is insufficiently elucidated. This study is the first to report disseminated candidiasis in AM-depleted mice and to analyze the effect of AMs on Candida-induced acute lung injury. While all AM-sufficient mice died by day 2 after infection withCandida albicans, no mortality was observed among AM-depleted mice. Unexpectedly, the CFU numbers of C. albicans isolated from the lungs of AM-depleted mice were significantly higher than those for C. albicans isolated from AM-sufficient mice. The lung wet-to-dry weight ratio was lower for AM-depleted mice than for AM-sufficient mice, although this difference was not significant. We found that bronchoalveolar lavage fluid (BALF) from AM-depleted mice in candidemia contained fewer neutrophils than BALF from AM-sufficient mice. In addition, myeloperoxidase activities in lung homogenates of AM-depleted mice were significantly lower than those in homogenates of AM-sufficient mice. A significant decrease in levels of murine macrophage inflammatory protein 2 (MIP-2), a potent chemoattractant for neutrophils, was noted in lung homogenates from AM-depleted mice compared with levels in homogenates from AM-sufficient mice. Immunohistochemical studies using anti-MIP-2 antibodies revealed that AMs were the cellular source of MIP-2 within the lung during candidemia. We observed that AM depletion decreased levels of AM-derived neutrophil chemoattractant, alleviated acute lung injury during candidemia, and prolonged the survival of mice in candidemia, even though clearance of C. albicans from the lungs was reduced.

INFLUENCE OF DEPLETION OF ALVEOLAR MACROPHAGES ON APOPTOSIS IN CANDIDA-INDUCED ACUTE LUNG INJURY

Apoptosis plays an important role in acute lung injury (ALI), and alveolar macrophages (AMs) are known to secrete proinflammatory cytokines and promote alveolar inflammation. The authors have previously reported that AMs can be depleted by inhalation of 1 mM 2-chloroadenosine (2-CA). In this study, the authors evaluated the effect of AM depletion by 2-CA inhalation on apoptosis in Candida-induced ALI. The results of in situ terminal deoxynucleotidyl transferase–mediated dUTP biotin nick end-labeling (TUNEL) and immunohistochemical studies and measurement of cytokine levels and caspase 3 activities in lung homogenates indicated that the Fas-FasL system and apoptosis of alveolar epithelial cells are suppressed by depletion of AMs by 2-CA inhalation.