ABSTRACT
Herein, we report two cases of tuberculosis (TB) of the central nervous system where accessing the cerebrospinal fluid for diagnostic purposes was relatively or absolutely contraindicated at presentation. The finding of mediastinal lymphadenopathy on thoracic computed tomography scans, which was not visible on plain chest radiography, allowed endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of these lymph nodes to support the diagnosis of TB in each patient and rule out other disease processes. EBUS-TBNA is a new bronchoscopic technique and in this case report appears to be a safe and useful option in the diagnosis of TB. Moreover, it proved to be so in cases where the main focus of disease was outside the thorax.
Subject(s)
Central Nervous System Diseases/diagnostic imaging , Central Nervous System Diseases/pathology , Tuberculosis/diagnostic imaging , Tuberculosis/pathology , Adult , Antitubercular Agents/therapeutic use , Biopsy, Fine-Needle , Central Nervous System Diseases/drug therapy , Endosonography , Female , Humans , Tomography, X-Ray Computed , Treatment Outcome , Tuberculosis/drug therapyABSTRACT
Respiratory syncytial virus (RSV) infection is the major cause of severe bronchiolitis in infants. Pathology of this infection is partly due to excessive proinflammatory leukocyte influx mediated by chemokines. Although direct infection of the respiratory epithelium by RSV may induce chemokine secretion, little is known about the role of cytokine networks. We investigated the effects of conditioned medium (CM) from RSV-infected monocytes (RSV-CM) on respiratory epithelial (A549) cell chemokine release. RSV-CM, but not control CM (both at a 1:5 dilution), stimulated interleukin-8 (IL-8) secretion from A549 cells within 2 h, and secretion increased over 72 h to 11,360 +/- 1,090 pg/ml without affecting cell viability. In contrast, RSV-CM had only a small effect on RANTES secretion. RSV-CM interacted with direct RSV infection to synergistically amplify IL-8 secretion from respiratory epithelial cells (levels of secretion at 48 h were as follows: RSV-CM alone, 8,140 +/- 2,160 pg/ml; RSV alone, 12,170 +/- 300 pg/ml; RSV-CM plus RSV, 27,040 +/- 5,260 pg/ml; P < 0.05). RSV-CM induced degradation of IkappaBalpha within 5 min but did not affect IkappaBbeta. RSV-CM activated transient nuclear binding of NF-kappaB within 1 h, while activation of NF-IL6 was delayed until 8 h and was still detectable at 24 h. Promoter-reporter analysis demonstrated that NF-kappaB binding was essential and that NF-IL6 was important for IL-8 promoter activity in RSV-CM-activated cells. Blocking experiments revealed that the effects of RSV-CM depended on monocyte-derived IL-1 but that tumor necrosis factor alpha was not involved in this network. In summary, RSV infection of monocytes results in and amplifies direct RSV-mediated IL-8 secretion from respiratory epithelial cells by an NF-kappaB-dependent, NF-IL6-requiring mechanism.
Subject(s)
Bronchi/virology , Epithelial Cells/pathology , Interleukin-8/metabolism , Monocytes/virology , Respiratory Syncytial Virus Infections/virology , Animals , Blotting, Northern , Blotting, Western , Bronchi/cytology , Bronchi/pathology , Cell Line , Culture Media, Conditioned , Enzyme-Linked Immunosorbent Assay , Epithelial Cells/metabolism , Humans , Interleukin-1/metabolism , Interleukin-6/metabolism , Monocytes/pathology , NF-kappa B/metabolism , Promoter Regions, Genetic , Respiratory Syncytial Virus Infections/pathologyABSTRACT
Pulmonary epithelial cells, covering a 70-m2 surface area, have not previously been considered an important source of chemokines in pulmonary tuberculosis. We analyzed IL-8 secretion from A549 cells and primary normal human bronchial epithelial cells (NHBE) infected by Mycobacterium tuberculosis. Direct infection of A549 cells by M. tuberculosis caused IL-8 secretion of 7720 +/- 1610 pg/106 cells, but no IL-8 secretion from NHBE after 24 h. In contrast, conditioned media from M. tuberculosis-infected human monocytes (CoMTB) induced a much greater IL-8 secretion of 92,635 +/- 13,180 pg/106 A549 cells and 13,416 +/- 3,529 pg/106 NHBE after 24 h. CoMTB induced rapid IL-8 mRNA accumulation, which was stable over 24 h, compared with TNF-alpha-induced transcripts. CoMTB stimulated nuclear binding of p65, p50, and c-Rel subunits of NF-kappa B to IL-8 promoter sequences. Transient transfections with IL-8 promoter reporter constructs showed NF-kappa B binding-site mutations abolished IL-8 promoter activity while NF-IL-6 binding-site mutations decreased promoter activity to 50.2 +/- 6.3% of wild-type activity. IL-1R antagonist but not neutralizing anti-TNF-alpha inhibited epithelial cell IL-8 secretion, mRNA accumulation, and NF-kappa B binding. Recombinant IL-1 beta (2 ng/ml) induced similar levels of IL-8 secretion to CoMTB in both A549 cells and NHBE. Pulmonary epithelial cells are a major source of IL-8 in the initial host response to pulmonary tuberculosis. Such IL-8 secretion is NF-kappa B dependent, NF-IL-6 requiring, and activated by an IL-1-mediated pathway as a consequence of phagocytosis of M. tuberculosis by monocytes.
