Dr Michael Johnson is responsible for light and optical imaging in the Faculty of Science at UTS. He also co-ordinates and teaches in the Advanced Microscopy and Imaging (91566) subject, that is a core requirement for the MSc (Medical Biotechnology) students.
Dr Michael Johnson has over 15 years experience in Apicomplexan parasitology, and has applied his knowledge of light and optical microscopy to many other cell types. He is highly expert in IFM, 3D imaging by confocal and widefield microscopy (with deconvolution) as well as flow cytometry. He also has expertise in image analysis.
Can supervise: YES
Subject Co-ordinator for Advanced Microscopy and Imaging (91566) in the MSc (Medical Biotechnology) stream
Lecturer in Parasitology (91532): Apicomplexan parasites: parasite transmission and imaging
Jaiswal, R, Johnson, MS, Pokharel, D, Krishnan, SR & Bebawy, M 2017, 'Microparticles shed from multidrug resistant breast cancer cells provide a parallel survival pathway through immune evasion.', BMC Cancer, vol. 17, no. 1, pp. 1-12.View/Download from: UTS OPUS or Publisher's site
BACKGROUND: Breast cancer is the most frequently diagnosed cancer in women. Resident macrophages at distant sites provide a highly responsive and immunologically dynamic innate immune response against foreign infiltrates. Despite extensive characterization of the role of macrophages and other immune cells in malignant tissues, there is very little known about the mechanisms which facilitate metastatic breast cancer spread to distant sites of immunological integrity. The mechanisms by which a key healthy defense mechanism fails to protect distant sites from infiltration by metastatic cells in cancer patients remain undefined. Breast tumors, typical of many tumor types, shed membrane vesicles called microparticles (MPs), ranging in size from 0.1-1 m in diameter. MPs serve as vectors in the intercellular transfer of functional proteins and nucleic acids and in drug sequestration. In addition, MPs are also emerging to be important players in the evasion of cancer cell immune surveillance. METHODS: A comparative analysis of effects of MPs isolated from human breast cancer cells and non-malignant human brain endothelial cells were examined on THP-1 derived macrophages in vitro. MP-mediated effects on cell phenotype and functionality was assessed by cytokine analysis, cell chemotaxis and phagocytosis, immunolabelling, flow cytometry and confocal imaging. Student's t-test or a one-way analysis of variance (ANOVA) was used for comparison and statistical analysis. RESULTS: In this paper we report on the discovery of a new cellular basis for immune evasion, which is mediated by breast cancer derived MPs. MPs shed from multidrug resistant (MDR) cells were shown to selectively polarize macrophage cells to a functionally incapacitated state and facilitate their engulfment by foreign cells. CONCLUSIONS: We propose this mechanism may serve to physically disrupt the inherent immune response prior to cancer cell colonization whilst releasing mediators required for the recruitment...
Donnelly, S, Huston, WM, Johnson, M, Tiberti, N, Saunders, B, O'Brien, B, Burke, C, Labbate, M & Combes, V 2017, 'Targeting the master regulator mTOR: a new approach to prevent the neurological of consequences of parasitic infections?', Parasites & Vectors, vol. 10, no. 1, pp. 1-6.View/Download from: UTS OPUS or Publisher's site
A systematic analysis of 240 causes of death in 2013 revealed that parasitic diseases were responsible for more than one million deaths. The vast majority of these fatalities resulted from protozoan infections presenting with neurological sequelae. In the absence of a vaccine, development of effective therapies is essential to improving global public health. In 2015, an intriguing strategy to prevent cerebral malaria was proposed by Gordon et al. 2015 mBio, 6:e00625. Their study suggested that inhibition of the mammalian target of rapamycin prevented experimental cerebral malaria by blocking the damage to the blood brain barrier and stopping the accumulation of parasitized red blood cells and T cells in the brain. Here, we hypothesize that the same therapeutic strategy could be adopted for other protozoan infections with a brain tropism, to prevent cerebral parasitosis by limiting pathogen replication and preventing immune mediated destruction of brain tissue.
Zhao, Z, Johnson, MS, Chen, B, Grace, M, Ukath, J, Lee, VS, McRobb, LS, Sedger, LM & Stoodley, MA 2016, 'Live-cell imaging to detect phosphatidylserine externalization in brain endothelial cells exposed to ionizing radiation: implications for the treatment of brain arteriovenous malformations', Journal of Neurosurgery, pp. 1-8.View/Download from: UTS OPUS or Publisher's site
Chaiyadet, S, Sotillo, J, Smout, M, Cantacessi, C, Jones, MK, Johnson, MS, Turnbull, L, Whitchurch, CB, Potriquet, J, Laohaviroj, M, Mulvenna, J, Brindley, PJ, Bethony, JM, Laha, T, Sripa, B & Loukas, A 2015, 'Carcinogenic Liver Fluke Secretes Extracellular Vesicles That Promote Cholangiocytes to Adopt a Tumorigenic Phenotype.', The Journal of infectious diseases, vol. 212, no. 10, pp. 1636-1645.View/Download from: UTS OPUS or Publisher's site
Throughout Asia, there is an unprecedented link between cholangiocarcinoma and infection with the liver fluke Opisthorchis viverrini. Multiple processes, including chronic inflammation and secretion of parasite proteins into the biliary epithelium, drive infection toward cancer. Until now, the mechanism and effects of parasite protein entry into cholangiocytes was unknown.Various microscopy techniques were used to identify O. viverrini extracellular vesicles (EVs) and their internalization by human cholangiocytes. Using mass spectrometry we characterized the EV proteome and associated changes in cholangiocytes after EV uptake, and we detected EV proteins in bile of infected hamsters and humans. Cholangiocyte proliferation and interleukin 6 (IL-6) secretion was measured to assess the impact of EV internalization.EVs were identified in fluke culture medium and bile specimens from infected hosts. EVs internalized by cholangiocytes drove cell proliferation and IL-6 secretion and induced changes in protein expression associated with endocytosis, wound repair, and cancer. Antibodies to an O. viverrini tetraspanin blocked EV uptake and IL-6 secretion by cholangiocytes.This is the first time that EVs from a multicellular pathogen have been identified in host tissues. Our findings imply a role for O. viverrini EVs in pathogenesis and highlight an approach to vaccine development for this infectious cancer.
Chaiyadet, S, Smout, M, Johnson, M, Whitchurch, C, Turnbull, L, Kaewkes, S, Sotillo, J, Loukas, A & Sripa, B 2015, 'Excretory/secretory products of the carcinogenic liver fluke are endocytosed by human cholangiocytes and drive cell proliferation and IL6 production.', International journal for parasitology, vol. 45, no. 12, pp. 773-781.View/Download from: UTS OPUS or Publisher's site
Liver fluke infection caused by Opisthorchis viverrini remains a major public health problem in many parts of Asia including Thailand, Lao PDR, Vietnam and Cambodia, where there is a strikingly high incidence of cholangiocarcinoma (CCA - hepatic cancer of the bile duct epithelium). Among other factors, uptake of O. viverrini excretory/secretory products (OvES) by biliary epithelial cells has been postulated to be responsible for chronic inflammation and proliferation of cholangiocytes, but the mechanisms by which cells internalise O. viverrini excretory/secretory products are still unknown. Herein we incubated normal human cholangiocytes (H69), human cholangiocarcinoma cells (KKU-100, KKU-M156) and human colon cancer (Caco-2) cells with O. viverrini excretory/secretory products and analysed the effects of different endocytic inhibitors to address the mechanism of cellular uptake of ES proteins. Opisthorchis viverrini excretory/secretory products was internalised preferentially by liver cell lines, and most efficiently/rapidly by H69 cells. There was no evidence for trafficking of ES proteins to cholangiocyte organelles, and most of the fluorescence was detected in the cytoplasm. Pretreatment with clathrin inhibitors significantly reduced the uptake of O. viverrini excretory/secretory products, particularly by H69 cells. Opisthorchis viverrini excretory/secretory products induced proliferation of liver cells (H69 and CCA lines) but not intestinal (Caco-2) cells, and proliferation was blocked using inhibitors of the classical endocytic pathways (clathrin and caveolae). Opisthorchis viverrini excretory/secretory products drove IL6 secretion by H69 cells but not Caco-2 cells, and cytokine secretion was significantly reduced by endocytosis inhibitors. This the first known study to address the endocytosis of helminth ES proteins by host epithelial cells and sheds light on the pathways by which this parasite causes one of the most devastating forms of cancer in south-ea...
Smout, MJ, Sotillo, J, Laha, T, Papatpremsiri, A, Rinaldi, G, Pimenta, RN, Chan, LY, Johnson, MS, Turnbull, L, Whitchurch, CB, Giacomin, PR, Moran, CS, Golledge, J, Sripa, B, Mulvenna, JP, Brindley, PJ & Loukas, A 2015, 'Carcinogenic Parasite Secretes Growth Factor That Accelerates Wound Healing and Potentially Promotes Neoplasia', PLoS Pathogens, vol. 11, no. 10.View/Download from: UTS OPUS or Publisher's site
Infection with the human liver fluke Opisthorchis viverrini induces cancer of the bile ducts, cholangiocarcinoma (CCA). Injury from feeding activities of this parasite within the human biliary tree causes extensive lesions, wounds that undergo protracted cycles of healing, and re-injury over years of chronic infection. We show that O. viverrini secreted proteins accelerated wound resolution in human cholangiocytes, an outcome that was compromised following silencing of expression of the fluke-derived gene encoding the granulin-like growth factor, Ov-GRN-1. Recombinant Ov-GRN-1 induced angiogenesis and accelerated mouse wound healing. Ov-GRN-1 was internalized by human cholangiocytes and induced gene and protein expression changes associated with wound healing and cancer pathways. Given the notable but seemingly paradoxical properties of liver fluke granulin in promoting not only wound healing but also a carcinogenic microenvironment, Ov-GRN-1 likely holds marked potential as a therapeutic wound-healing agent and as a vaccine against an infection-induced cancer of major public health significance in the developing world.
Frolich, S, Johnson, MS, Robinson, ML, Entzeroth, R & Wallach, M 2013, 'The Spatial Organization And Extraction Of The Wall-forming Bodies Of Eimeria Maxima', Parasitology, vol. 140, no. 7, pp. 876-887.View/Download from: UTS OPUS or Publisher's site
Eimeria maxima has been used as a model apicomplexan parasite to study sexual stage development and oocyst wall formation. A complete understanding of the wall's biochemical and biophysical properties is of great interest in research on all apicomplexan parasites. Purified gametocytes, zygotes and oocysts were analysed by three-dimensional confocal microscopy, and wide-field fluorescent microscopy was used to investigate the appearance and spatial organization of the 2 types of wall-forming bodies (WFBs). In addition, a variety of staining procedures and immunoassays were used to assess the biosynthesis, metabolic activity, intactness and molecular composition of the WFBs in situ. WFBs were extracted from gametocytes/zygotes and their composition was assessed by microscopy and SDS-PAGE analysis. It was concluded that isolated gametocytes are intact and metabolically active. Additionally, it was observed that the Type 1 WFBs are aligned at the periphery of the parasite and fuse together producing neutral lipid rich patches that appear to be inserted into the space between 2 parasite-specific membranes. Finally, it was shown that the WFBs extracted from purified gametocytes had the same shape, size and staining properties as those observed in situ, and contained the major glycoprotein antigens known to be present in these organelles.
Ivanov, IE, Boyd, CD, Newell, PD, Schwartz, ME, Turnbull, L, Johnson, MS, Whitchurch, CB, O'Toole, GA & Camesano, TA 2012, 'Atomic force and super-resolution microscopy support a role for LapA as a cell-surface biofilm adhesin of Pseudomonas fluorescens', Research in Microbiology, vol. 163, no. 9-10, pp. 685-691.View/Download from: UTS OPUS or Publisher's site
Pseudomonas fluorescence Pf0-1 requires the large repeat protein LapA for stable surface attachment. This study presents direct evidence that LapA is a cell-surface-localized adhesin. Atomic force microscopy (AFM) revealed a significant 2-fold reduction in adhesion force for mutants lacking the LapA protein on the cell surface compared to the wild-type strain. Deletion of lapG, a gene encoding a periplasmic cysteine protease that functions to release LapA from the cell surface, resulted in a 2-fold increase in the force of adhesion. Three-dimensional structured illumination microscopy (3D-SIM) revealed the presence of the LapA protein on the cell surface, consistent with its role as an adhesin. The protein is only visualized in the cytoplasm for a mutant of the ABC transporter responsible for translocating LapA to the cell surface. Together, these data highlight the power of combining the use of AFM and 3D-SIM with genetic studies to demonstrate that LapA, a member of a large group of RTX-like repeat proteins, is a cell-surface adhesin
Parameswaran, N, Thompson, RS, Sundar, N, Pan, S, Johnson, MS, Smith, NC & Grigg, M 2010, 'Non-Archetypal Type Ii-Like And Atypical Strains Of Toxoplasma Gondii Infecting Marsupials Of Australia', International Journal For Parasitology, vol. 40, no. 6, pp. 635-640.View/Download from: UTS OPUS or Publisher's site
Australia is geographically isolated and possesses a remarkable diversity of wildlife species. Marsupials are highly susceptible to infection with the cosmopolitan parasite Toxoplasma gondii. Of 46 marsupials screened for T. gondii by multilocus PCR-DNA
Johnson, MS, Broady, KW, Angelici, M & Johnson, AM 2003, 'The relationship between nucleoside triphosphate hydrolase (NTPase) isoform and Toxoplasma strain virulence in rat and human toxoplasmosis', Microbes and Infection, vol. 5, pp. 797-806.View/Download from: UTS OPUS or Publisher's site
The nucleoside triphosphate hydrolase (NTPase) of Toxoplasma gondii demonstrates an unusually high level of ATP hydrolysis, which, among the apicomplexan parasites, has only been observed in T. gondii and the closely related Neospora caninum. In T. gondii, NTPase has been shown to be highly expressed (constituting up to 8% of the tachyzoite protein) and is an immunodominant antigen in mice and humans. Two isoforms exist - NTPasel and NTPasell. NTPasel demonstrates a 4.5 fold greater activity than NTPasell with respect to ATP hydrolysis. Past studies suggest that only virulent strains possess the highly active NTPasel isoform. We have recently identified a B cell epitope (aa 484-502) on the NTPase isoforms which, despite some cross reactivity, is differentially recognised by a naturally infected human serum sample. In this study we used competitive antigen ELISAs and have identified that this serum sample reacts specifically to the NTPasel epitope, whilst the corresponding region on NTPasell isoform is the less specific cross reactive epitope. These results are consistent with the hypothesis that this patient has been infected with a virulent strain of T. gondii. Copyright© 1999, The Research Center for Protozoan Molecular Immunology.