Mechanisms of Legionella pneumophila-induced interleukin-8 expression in human lung epithelial cells

<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumophila </it>is a facultative intracellular bacterium, capable of replicating within the phagosomes of macrophages and monocytes, but little is known about its interaction with human lung epithelial cells. We investigated the effect of <it>L. pneumophila </it>on the expression of interleukin-8 (IL-8) in human A549 alveolar and NCI-H292 tracheal epithelial cell lines.</p> <p>Results</p> <p>Infection of <it>L. pneumophila </it>strain, but not heat-killed strain, resulted in upregulation of IL-8. IL-8 mRNA expression was induced immediately after the infection and its signal became gradually stronger until 24 h after infection. On the other hand, IL-8 expression in A549 cells infected with <it>L. pneumophila </it>lacking a functional type IV secretion system was transient. The IL-8 expression was slightly induced at 16 h and increased at 24 h after infection with flagellin-deficient <it>Legionella</it>. Activation of the IL-8 promoter by <it>L. pneumophila </it>infection occurred through the action of nuclear factor-κB (NF-κB). Transfection of dominant negative mutants of NF-κB-inducing kinase, IκB kinase and IκB inhibited <it>L. pneumophila</it>-mediated activation of IL-8 promoter. Treatment with hsp90 inhibitor suppressed <it>L. pneumophila</it>-induced IL-8 mRNA due to deactivation of NF-κB.</p> <p>Conclusion</p> <p>Collectively, these results suggest that <it>L. pneumophila </it>induces activation of NF-κB through an intracellular signaling pathway that involves NF-κB-inducing kinase and IκB kinase, leading to IL-8 gene transcription, and that hsp90 acts as a crucial regulator in <it>L. pneumophila</it>-induced IL-8 expression, presumably contributing to immune response in <it>L. pneumophila</it>. The presence of flagellin and a type IV secretion system are critical for <it>Legionella </it>to induce IL-8 expression in lung epithelial cells.</p

A successful rechallenge with cetuximab for a case with metastatic rectal cancer

　A 55-year-old man who had been diagnosed with rectal cancer with multiple liver metastases and lymph node metastases on colonoscopy and computed tomography (CT) was referred to Okayama University Hospital for treatment. Based on the diagnosis of non-curative rectal cancer, we planned to perform systematic chemotherapy after surgical resection. We performed a low anterior resection of a 36×35 mm upper rectal moderately differentiated adenocarcinoma with wil-type KRAS. After the resection, a FOLFIRI regimen with cetuximab was given as the first-line chemotherapy. Although metastatic lesions in the liver showed shrinkage, we decided to switch regimens because of intolerable adverse events. A modified FOLFOX6 regimen with bevacizumab was administered as the second-line treatment. There were no signs of disease progression until eight months later, when positron emission tomography (PET)/CT scans revealed that the new metastatic lesions appeared. As the third-line treatment, an irinotecan with cetuximab regimen was administered, leading to a good response for over 12 months. 　We experienced a successful rechallenge with cetuximab for a case with metastatic rectal cancer. For patients with wild-type KRAS colorectal cancer, rechallenge with cetuximab-based chemotherapy can be an effective therapeutic option

Molecular characterization of Legionella pneumophila-induced interleukin-8 expression in T cells

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Legionella pneumophila infection induces programmed cell death, caspase activation, and release of high-mobility group box 1 protein in A549 alveolar epithelial cells: inhibition by methyl prednisolone

<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumophila </it>pneumonia often exacerbates acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Apoptosis of alveolar epithelial cells is considered to play an important role in the pathogenesis of ALI and ARDS. In this study, we investigated the precise mechanism by which A549 alveolar epithelial cells induced by <it>L. pneumophila </it>undergo apoptosis. We also studied the effect of methyl prednisolone on apoptosis in these cells.</p> <p>Methods</p> <p>Nuclear deoxyribonucleic acid (DNA) fragmentation and caspase activation in <it>L. pneumophila</it>-infected A549 alveolar epithelial cells were assessed using the terminal deoxyribonucleotidyl transferase-mediated triphosphate (dUTP)-biotin nick end labeling method (TUNEL method) and colorimetric caspase activity assays. The virulent <it>L. pneumophila </it>strain AA100jm and the avirulent <it>dotO </it>mutant were used and compared in this study. In addition, we investigated whether methyl prednisolone has any influence on nuclear DNA fragmentation and caspase activation in A549 alveolar epithelial cells infected with <it>L. pneumophila</it>.</p> <p>Results</p> <p>The virulent strain of <it>L. pneumophila </it>grew within A549 alveolar epithelial cells and induced subsequent cell death in a dose-dependent manner. The avirulent strain <it>dotO </it>mutant showed no such effect. The virulent strains of <it>L. pneumophila </it>induced DNA fragmentation (shown by TUNEL staining) and activation of caspases 3, 8, 9, and 1 in A549 cells, while the avirulent strain did not. High-mobility group box 1 (HMGB1) protein was released from A549 cells infected with virulent <it>Legionella</it>. Methyl prednisolone (53.4 μM) did not influence the intracellular growth of <it>L. pneumophila </it>within alveolar epithelial cells, but affected DNA fragmentation and caspase activation of infected A549 cells.</p> <p>Conclusion</p> <p>Infection of A549 alveolar epithelial cells with <it>L. pneumophila </it>caused programmed cell death, activation of various caspases, and release of HMGB1. The dot/icm system, a major virulence factor of <it>L. pneumophila</it>, is involved in the effects we measured in alveolar epithelial cells. Methyl prednisolone may modulate the interaction of <it>Legionella </it>and these cells.</p

A case of metastatic cecal cancer with mutation in the BRAF oncogene and poor survival

　A 79-year-old woman visited a previous hospital with a complaint of general fatigue. The patient was diagnosed with cecal cancer with multiple liver metastases and lymph node metastases on colonoscopy, abdominal ultrasonography and CT scan, and was referred to our division for treatment. Based on the diagnosis of non-curative colonic cancer, we planned to perform systematic chemotherapy after local surgical treatment. We performed an ileocecal resection, and the specimen showed poorly differentiated adenocarcinoma with mutation in the BRAF oncogene. After the surgical treatment, the tumor grew rapidly and the patient died from cancer on the 19th postoperative day without having the opportunity to undergo chemotherapy. 　Multiple genetic and epigenetic alterations in oncogenes and tumor suppressor genes are involved in the process of colorectal carcinogenesis. Some of the alterations have been identified as predictive and prognostic biomarkers. A mutation in the BRAF oncogene was reported to be associated with a very unfavorable prognosis in colorectal cancers. Some of the cases with rapid progression are suggested to have the BRAF oncogene mutation. According to our experience, chemotherapy before surgical treatment might improve the prognosis of cases with the BRAF mutation