The induction of cyclooxygenase-2 (COX-2) in tissue macrophages (MØ) increases prostaglandin E 2 (PGE 2 ) release, potentially downregulating granulomatous inflammation. In response to Mycobacteria, local MØ express COX-2, which is either nuclear envelope (NE)-associated or NE-dissociated. Persistent mycobacterial pulmonary inflammation is characterized by alveolar MØ expressing NEdissociated (inactive) COX-2 without release of PGE 2 . In this study, we examined COX-2 in alveolar MØ after intranasal exposure to heat-killed Mycobacterium bovis BCG (HK-BCG). After administration, whole lungs of C57Bl/6 mice were lavaged with saline; COX-2 expression and PGE 2 release by alveolar MØ and tumor necrosis factor (TNF)-a and nitric oxide levels in the lung lavage were monitored. Normal alveolar MØ had undetectable levels of COX-2 on Western blots. However, 1 day after intranasal administration, almost all alveolar MØ had phagocytosed HK-BCG and expressed NE-dissociated COX-2 without any increase in the release of PGE 2 . At 28 days after intranasal administration, 68% of alveolar MØ still contained both BCG and the NE-dissociated form of COX-2. NEassociated (active) COX-2 was not observed in alveolar MØ. In contrast, 7 days after intraperitoneal injection of HK-BCG, peritoneal MØ containing HK-BCG were no longer detected. At 28 days after intranasal administration, TNF-a and nitrite levels in the lung lavage fluid were significantly higher than those in controls. Our results indicate that mycobacterial pulmonary inflammation is associated with suppressed PGE 2 production by alveolar MØ, with expression of COX-2 dissociated from the NE.

cellular cholesterol enhances macrophage MAPK activation by chitin microparticles but not by heat-killed Mycobacterium bovis BCG. Am J Physiol Cell Physiol 295: C341-C349, 2008. First published June 4, 2008 doi:10.1152/ajpcell.00446.2007.-When macrophages phagocytose chitin (N-acetyl-D-glucosamine polymer) microparticles, mitogen-activated protein kinases (MAPK) are immediately activated, followed by the release of Th1 cytokines, but not IL-10. To determine whether phagocytosis and macrophage activation in response to chitin microparticles are dependent on membrane cholesterol, RAW264.7 macrophages were treated with methyl-␤-cytodextrin (MBCD) and stimulated with chitin. These results were compared with the corresponding effects of bacterial components including heat-killed (HK) Mycobacterium bovis bacillus Calmette-Guèrin (BCG) and an oligodeoxynucleotide (ODN) of bacterial DNA (CpG-ODN). The MBCD treatment did not alter chitin binding or the phagocytosis of chitin particles 20 min after stimulation. At the same time, however, chitin-induced phosphorylation of cellular MAPK was accelerated and enhanced in an MBCD dose-dependent manner. The increased phosphorylation was also observed for chitin phagosome-associated p38 and ERK1/2. In contrast, CpG-ODN and HK-BCG induced activation of MAPK in MBCD-treated cells at levels comparable to, or only slightly more than, those of control cells. We also found that MBCD treatment enhanced the production of tumor necrosis factor-␣ (TNF-␣) and the expression of cyclooxygenase-2 (COX-2) in response to chitin microparticles. In neither MBCD-nor saline-treated macrophages, did chitin particles induce detectable IL-10 mRNA synthesis. CpG-ODN induced TNF-␣ production, and COX-2 expression were less sensitive to MBCD treatment. Among the agonists studied, our results indicate that macrophage activation by chitin microparticles was most sensitive to cholesterol depletion, suggesting that membrane structures integrated by cholesterol are important for physiological regulation of chitin microparticle-induced cellular activation.

No abstract

Idiopathic pulmonary fibrosis is often associated with lung cancer, but early malignant lesions mixed with fibrous lesions are not always easy to diagnose. A 78-year-old woman was referred to our hospital due to a ground-glass nodule in the left upper lobe detected on chest high resolution computed tomography during follow-up of chronic idiopathic interstitial pneumonia. Pathological examination of the resected specimen revealed that the ground-glass nodule was locally progressed usual interstitial pneumonia (UIP). It should be noted that focal progression of UIP may occur and present with ground-glass nodule mimicking lung cancer, even if lesions in other areas remain unchanged. Moreover, in such cases, recognition of nodular lesions by the gross findings on the pleural surface and palpation during surgical resection are difficult and require precise marking.

Granuloma formation is a hallmark of mycobacterial infections and represents the histological correlate of both protective immunity and inflammatory tissue destruction. PGE2 is known to regulate infections, inflammation and tissue repair, although exact mechanisms regulating COX‐2 activity, a rate‐limiting enzyme for PGE2 biosynthesis, are unclear. In this study, alveolar macrophages (MØ) were isolated from C57Bl/6 mice following intranasal administration of 0.5 mg killed Mycobacteirum bovis BCG. We found that normal alveolar MØ showed minimal (or undetectable) levels of COX‐1 and COX‐2 by western blot. However, one day after administration, almost all MØ had phagocytosed BCG and expressed significant levels of COX‐1 and COX‐2. Analysis by confocal microscopy indicated that for MØ phagocytosing BCG, COX‐1 and COX‐2 were preferentially dissociated from the nuclear envelop (NE), indicating forms catalytically inactive for PGE2 synthesis. In contrast to mice given ip BCG where peritoneal MØ containing BCG disappeared within 7 days, 28 days after intranasal administration, 68% of alveolar MØ in lung lavage fluid still contained BCG together with NE‐dissociated COX‐1 and COX‐2. Our results indicate that the lack of PGE2 production may enhance PGE2‐sensitive, MØ c‐mediated immune responses against pulmonary infections and inflammation caused by mycobacteria. [NIH HL71711 and DOD DAMD17‐03‐1‐0004]