cord-factors and Hemorrhage

The biologic effects of the mycobacterial glycolipid trehalose-6,6'-dimycolate (TDM) include granuloma formation and macrophage activation and are dependent on physical conformation. In mice, the group II CD1 surface molecule CD1d has been implicated in glycolipid presentation. The importance of CD1d interactions in pathology has yet to be established. We hypothesized that mice lacking CD1d (CD1D(-/-)) would demonstrate dysregulated granulomatous response to TDM, compared with CD1D(+/-) heterozygous controls. Mice were intravenously injected with TDM-coated polystyrene-divinylbenzene beads and examined for histologic response and for changes in inflammatory cytokine and chemokine mRNA. Control CD1D heterozygous mice demonstrated a granulomatous response, which peaked at day 5. Increased mRNA for tumor necrosis factor-alpha (TNF-alpha) and macrophage inflammatory protein-1alpha (MIP-1alpha) correlated with development of granulomas, with very little change in interleukin-1beta (IL-1beta) and monocyte chemoattractant protein-1 (MCP-1). In contrast, the CD1D(-/-) mice revealed markedly different responses. Five days after administration, severe pulmonary hemorrhage was induced. The relative size of inflammation surrounding coated bead in the CD1D(-/-) mice was nearly double that induced in the CD1D(+/-) mice. CD1D(-/-) mice also demonstrated elevated mRNA for both inflammatory cytokines and chemokines by day 1 after administration, significantly earlier than responses seen in the heterozygous controls.

Topics: Animals; Antigens, CD1; Antigens, CD1d; Chemokines; Cord Factors; Cytokines; Granuloma, Respiratory Tract; Hemorrhage; Lung Diseases; Mice; Mice, Knockout; Mycobacterium; Pneumonia; RNA, Messenger

Trehalose dimycolate (TDM) is a glycolipid contained in the cell walls of Mycobacteria, Nocardia and Corynebacteria. An intraperitoneal injection of TDM into mice has been known to produce hemorrhagic pneumonia without affecting any other organs. Thus, it provides a unique experimental model for studies of the mechanisms of alveolar hemorrhagic syndrome, including idiopathic pulmonary hemosiderosis. It has been reported that T lymphocytes are essential for the production of TDM-induced hemorrhagic pneumonia, however, the overall cellular mechanism is not yet clear. The purpose of this study is to re-examine and clarify the role of T lymphocytes in the pathogenesis of TDM-induced hemorrhagic pneumonia. To achieve it we considered 1) the dynamics of infiltrating lymphocytes to find out if there is a certain T lymphocyte subpopulation infiltrating predominantly into the lung, 2) the effect of in vivo depletion of T lymphocyte subpopulation by monoclonal antibodies, and 3) the effect of transfer of T lymphocytes into nude mice. The analysis of the dynamic change of the number of lymphocytes showed that the number of L3T4+ cells as well as Lyt2+ cells decreased on day 2 or 3 after TDM injection, thereafter increased, however, neither subpopulation infiltrated predominantly into the lung. Alveolar hemorrhages occurred in L3T4+ cell-depleted and/or Lyt2+ cell-depleted mice, and hemorrhages were enhanced in Lyt2+ cell-deplete mice. Alveolar hemorrhages occurred even in nude mice, and the intensity of hemorrhages or the cell numbers in the lung did not differ from those in T lymphocyte-reconstituted nude mice, however, hemorrhages were enhanced in L3T4+ cell-reconstituted nude mice. These results suggested that T lymphocytes are not primarily involved in the cellular mechanisms of the pathogenesis of TDM-induced hemorrhagic pneumonia, however, L3T4+ cells modify the process of the production of hemorrhagic pneumonia secondarily and enhance it.

Topics: Animals; Cord Factors; Disease Models, Animal; Female; Glycolipids; Hemorrhage; Male; Mice; Pneumonia; T-Lymphocytes

Trehalose dimycolate, a glycolipid component of the cell walls of mycobacteria, induces interstitial pneumonitis and alveolar hemorrhages in C57BL/6 and C57BL/10 mice. Homozygous nude (nu/nu) mice of these backgrounds are not susceptible to this form of pulmonary injury. However, after administration of T-lymphocyte-enriched spleen cell preparations from syngeneic donors, homozygous nude mice become susceptible to trehalose dimycolate. The observations suggest that production of pulmonary lesions by this mycobacterial component is dependent on T lymphocytes. While the mechanisms are still under study, we propose that trehalose dimycolate can function as an activator of T lymphocytes and that products of activated T cells are responsible for production of the pulmonary lesions.

Topics: Animals; Cord Factors; Female; Glycolipids; Hemorrhage; Immunity, Innate; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Nude; Pulmonary Alveoli; Pulmonary Fibrosis; Spleen; T-Lymphocytes

Intraperitoneal injections of cord factor (trehalose dimycolate, TDM) provides a model for interstitial and hemorrhagic lung disease that is produced by a chemically defined substance. A single injection of 10 micrograms of TDM, in light mineral oil or hexadecane, into C57BL/6 mice produces interstitial and hemorrhagic pneumonitis. Following injection of TDM the pulmonary lesions increase gradually and become maximal by the seventh to ninth day, at which time 70% of the mice show both gross hemorrhages and dense mononuclear infiltrates; an additional 20% of the mice show only microscopic lesions. From day 14 onward the incidence and severity of the lesions decrease, and by day 28 the lungs are normal by both gross and light-microscopy examination. Only 5% of the mice succumb. Except for peritonitis other organs are not affected. Doses of 3.3 and 10 micrograms of TDM are equally effective in producing the lesions, but a dose of 1.0 microgram of TDM causes only mild interstitial inflammation and lesser doses do not induce lesions. A single subcutaneous injection of 10 micrograms of TDM causes lesions in only 20% of mice. Vehicle-injected mice do not develop lesions. Electron microscopy revealed that the majority of the infiltrating cells are monocytes and macrophages and that extensive interstitial damage is produced. The mechanism of the effects of TDM are unknown and is currently under study. Our preliminary data suggests that the phenomenon is dependent upon T-lymphocytes.

Topics: Animals; Cord Factors; Glycolipids; Hemorrhage; Injections, Intraperitoneal; Lung; Macrophages; Male; Mice; Mice, Inbred C57BL; Microscopy, Electron; Monocytes; Mycobacterium tuberculosis; Peritonitis; Pneumonia; T-Lymphocytes; Time Factors