Microbial Immunopathology Laboratory
Laboratory Heads
Dr. John Emmins (Department of Immunology)
Associate Professor Richard Boyd (Monash Immunology and Stem Cell Laboratories)
Research Assistant
Lauren Young
The Immunopathology of Clostridium perfringens and Clostridium septicum mediated gas gangrene
Gas gangrene, also known as clostridial myonecrosis, is a disease of humans characterized by a rapidly progressing growth of bacteria in an anaerobic environment, with the production of extracellular toxins. These extracellular toxins can lead to massive tissue destruction, systemic shock, and if left untreated, death. With such an acute infection the innate rather than the adaptive arm of the immune system would have to be rapidly enlisted and mobilised. Granulocytes (predominantly neutrophils) and monocytes would have to be recruited to the site of infection to be at all effective in combating and limiting the spread of the infection. However, a most intriguing characteristic feature of gas gangrene is the absence of leukocytes in the necrotic tissue. We have demonstrated by immunohistological examination of Clostridium perfringens infected tissues that the leukocytes do not reach the site of infection and accumulate in nearby blood vessels. Our recent investigation of experimental Clostridium septicum-mediated cases also indicates a paucity of leukocytes in the infected tissue. To further examine the specific roles played by these Clostridial toxins in the apparent inhibition of leukocyte infiltration, a set of genetically-manipulated bacterial strains has been constructed in Professor Julian Rood's Laboratory (Bacterial Pathogenesis Research Group, Department of Microbiology, Monash University), which are deficient in production of the main toxins involved in the pathology of gas gangrene. These are the phospholipase C (alpha-toxin) and perfringolysin O (theta-toxin) of C. perfringens, and the alpha-toxin of C. septicum (the alpha-toxin of C. septicum differs from the C. perfringens alpha-toxin, in that it does not have phospholipase C activity). Future projects in our laboratory will seek to further investigate the molecular basis of this apparent immunomodulation of the immune response by clostridial toxins and endeavour to elucidate if there are different mechanisms in the immunopathogenesis of C. perfringens verses C. septicum mediated gas gangrene. Methods used in the course of these studies will include immunohistology, immunofluorescent three-colour confocal microscopy, flow cytometry, and in vitro leukocyte migration assays. In addition we have an ongoing collaborative research into in vivo studies of clostridial toxins using intravital microscopy in Dr. Michael Hickey’s laboratory at the Monash Medical Centre.
Recent theses, presentations and publications
Ellemor, D, Baird R, Awad M, Rood J, Emmins J and Boyd, R.L. (1999) Use of genetically manipulated strains of Clostridium perfringens reveals both alpha-toxin and theta toxin are required for vascular leukostasis to occur in experimental gas gangrene Infection and Immunity. 1999; 67: 4902-4907.
Awad MM, Ellemor DM, Bryant AE, Matsushita O, Boyd RL, Stevens DL, Emmins JJ and Rood JI. Construction and Virulence testing of a Collagenase Mutant of Clostridium perfringens. Microbial Pathogenesis. 2000; 28: 107-117.
Awad MM, Ellemor DM, Boyd RL, Emmins JJ, Rood JI. Synergistic effects of alpha-toxin and perfringolysin O in Clostridium perfringens-mediated gas gangrene. Infection and Immunity. 2001; 69(12): 7904-10.
Whittington RJ, Connolly J, Obendorf D, Emmins J, Grant TR and Handasyde K. Serological responses against the pathogenic dimorphic fungus Mucor amphibiorum in populations of platypus Ornithorhynchus anatinus with and without ulcerative dermatitis. In Veterinary Conservation Biology, Wildlife Health and Management in Australasia. Proceedings of the International Joint Conference. Sydney, 2-6 July, 2001.
Young L, Kennedy C, Krejany S, O'Connor J, Awad, M, Lyras D, Rood J, Boyd R, and Emmins J. A comparative Immunopathological Study of Clostridium perfringens and Clostridium septicum mediated gas gangrene. Proceedings Mini Back Path 2 Conference. Melbourne, June, 2002.
Rood JI, Awad MM, Ellemor DM, Boyd RL and Emmins JJ. Role of Alpha-toxin and perfringolysin O in Clostridium perfringens-mediated gas gangrene. 6th Asia-pacific Congress on Animal, Plant and Microbial Toxins. Cairns, Queensland, July, 2002.
Whittington RJ, Connolly JH, Obendorf DL, Emmins J, Grant TR and Handasyde KA. Serological responses against the pathogenic dimorphic fungus Mucor amphibiorum in populations of platypus (Ornithorhynchus anatinus) with and without ulcerative mycotic dermatitis. Veterinary Microbiology. 2002; 87(1): 59-71.
Young L. The Immunopathology of Clostridial Myonecrosis. 2002. BSc (Hons) Thesis (H1).
Porter J. The mechanism of leukostasis in Clostridium perfringens mediated myonecrosis. 2003. BSc (Hons) Thesis (H1).
Young L, Porter J, Awad M, Boyd R, Emmins J, Hickey M and Rood J. Examination of the impaired inflammatory response in Clostridium perfringens-mediated gas gangrene by intravital microscopy. Twelfth Annual Conference of the Immunology Group of Victoria. Beechworth, Victoria, 2004.
Rood J, Awad M, Lyras D, Kennedy C, Krejany S, O’Connor J,Farrow K, Young L, Boyd R and Emmins J. Application of genetic methods for the analysis of the pathogenic clostridia. Abstracts of the Australian Society for Microbiology Scientific Meeting. Sydney, NSW, 2004.
Kennedy C, Krejany E, Young L, O’Conner J, Awad M, Boyd R, Emmins J, Lyras D and Rood J. The alpha toxin of Clostridium septicum is essential for virulence. Molecular Microbiology. 2005; 57(5): 1357-1363.
Rood J, Young L, Kennedy C, Krejany E, Awad M, O’Conner J, Lyras D, Boyd R, Emmins J, Kwan R and Hickey M. Extracellular toxins of Histo toxic Clostridia. Australian Society of Microbiology Symposium, Australia, 2005.
Young L, Porter J, Awad M, Boyd R, Emmins J, Hickey M and Rood J. Intravital studies of the effects of Clostridium perfringens-derived PLC in the in vivo mouse model. NH&MRC Bacterial Pathogenesis Program Grant Scientific Meeting. Melbourne, Victoria, 2004.
Kennedy CL, Krejany S, Young L, Boyd R, Emmins J, Lyras D and Rood J. The alpha-toxin of Clostridium septicum is essential for virulence. Abstracts of Gordon Conference on Microbial Toxins and Pathogenesis. Andover, USA, 2004.
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