Biology subjects

Johansen, M. D.

Publications and source records attributed to Johansen, M. D..

3 recordsLinked to original sources

bioRxiv2018

Inhibition of thrombocyte activation restores protective immunity to mycobacterial infection

Infection-induced thrombocytosis is a clinically important complication of tuberculosis (TB). Recent studies have separately highlighted a correlation of platelet activation with TB severity and utility of aspirin as a host-directed therapy for TB that modulates the inflammatory response. Here we investigate the possibility that the beneficial effects of aspirin are related to an anti-platelet mode of action. We utilize the zebrafish-Mycobacterium marinum model to show mycobacteria drive host hemostasis through the formation of granulomas. Treatment of infected zebrafish with aspirin or platelet-specific glycoprotein IIb/IIIa inhibitors reduced mycobacterial burden demonstrating a detrimental role for infection-induced thrombocyte activation. We found platelet inhibition reduced thrombocyte-macrophage interactions and restored indices of macrophage-mediated immunity to mycobacterial infection. Pathological thrombocyte activation and granuloma formation were found to be intrinsically linked illustrating a bidirectional relationship between host hemostasis and TB pathogenesis. Our study illuminates platelet activation as an efficacious target of anti-platelets drugs including aspirin, a widely available and affordable host-directed therapy candidate for tuberculosis.\n\nKey PointsO_LIInhibition of thrombocyte activation improves control of mycobacterial infection.\nC_LIO_LIInhibition of thrombocyte activation reduces thrombocyte-macrophage interactions and improves indices of macrophage immune function against mycobacterial infection.\nC_LI

immunology↗

bioRxiv2018

Mycobacterium marinum infection drives foam cell differentiation in zebrafish infection models

Host lipid metabolism is an important target for subversion by pathogenic mycobacteria such as Mycobacterium tuberculosis. The appearance of foam cells within the granuloma are well-characterised effects of chronic tuberculosis. The zebrafish-Mycobacterium marinum infection model recapitulates many aspects of human-M. tuberculosis infection and is used as a model to investigate the structural components of the mycobacterial granuloma. Here, we demonstrate that the zebrafish-M. marinum granuloma contains foam cells and that the transdifferentiation of macrophages into foam cells is driven by the mycobacterial ESX1 pathogenicity locus. This report demonstrates conservation of an important aspect of mycobacterial infection across species.

immunology↗

bioRxiv2018

Pathogenic mycobacteria manipulate host low density lipoprotein metabolism

Changes to lipid metabolism are well-characterised consequences of human tuberculosis infection but their functional relevance are not clearly elucidated in these or other host-mycobacterial systems. The zebrafish-Mycobacterium marinum infection model is used extensively to model many aspects of human-M. tuberculosis pathogenesis but has not been widely used to study the role of infection-induced lipid metabolism. We find mammalian mycobacterial infection-induced alterations in host Low Density Lipoprotein metabolism are conserved in the zebrafish model of mycobacterial pathogenesis. Depletion of LDLR, a key lipid metabolism node, decreased M. marinum burden, and corrected infection-induced altered lipid metabolism resulting in decreased LDL and reduced the rate of macrophage transformation into foam cells. Our results demonstrate a conserved role for infection-induced alterations to host lipid metabolism, and specifically the LDL-LDLR axis, across host-mycobacterial species pairings.\n\nFundingThis work was supported by the Australian National Health and Medical Research Council (APP1099912 and APP1053407 to S.H.O.); Meat and Livestock Australia (P.PSH. 0813 to A.C.P. and K. dS); the Marie Bashir Institute for Infectious Diseases and Biosecurity (grant to S.H.O., A.C.P. and K. dS); the Kenyon Family Foundation Inflammation Award (grant to S.H.O.); the University of Sydney (fellowship to S.H.O.); Conselleria de Economia, Emprego e Industria (GAIN), Xunta de Galicia (grant IN607B 2016/12 to Institute of Marine Research (IIM-CSIC)).

immunology↗