IFN-γ and IL-5 whole blood response directed against mycolactone polyketide synthase domains in patients with Mycobacterium ulcerans infection

PeerJ

Kabiru M. Abass¹  Sacha Pidot²  Timothy P. Stinear²  Mark Wansbrough-Jones³  Justice K. Boakye-Appiah³  Richard O. Phillips⁴  Michael Frimpong⁴  Bernadette Agbavor⁴  Mabel Sarpong Duah⁴  Aloysius D. Loglo⁴  Francisca N. Sarpong⁴  Margaret Frempong⁵  Fred Sarfo⁵  Virginie Roupie⁶  Kris Huygen⁶  Mathias Dongyele⁷ 

[1] Agogo Presbyterian Hospital, Agogo, Ghana;Department of Microbiology and Immunology, Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC, Australia;Institute of Infection and Immunity, St George’s University of London, London, UK;Kumasi Centre for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana;School of Medical Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana;Service Immunology, Scientific Institute of Public Health, Brussels, Belgium;Tepa Government Hospital, Tepa, Ghana;

关键词: Mycobacterium ulcerans;    Immune response;    Polyketide synthase domains;    Buruli ulcer;   

DOI  :  10.7717/peerj.5294

来源: DOAJ

【 摘 要 】

Background Buruli ulcer is a disease of the skin and soft tissues caused by infection with a slow growing pathogen, Mycobacterium ulcerans. A vaccine for this disease is not available but M. ulcerans possesses a giant plasmid pMUM001 that harbours the polyketide synthase (PKS) genes encoding a multi-enzyme complex needed for the production of its unique lipid toxin called mycolactone, which is central to the pathogenesis of Buruli ulcer. We have studied the immunogenicity of enzymatic domains in humans with M. ulcerans disease, their contacts, as well as non-endemic areas controls. Methods Between March 2013 and August 2015, heparinized whole blood was obtained from patients confirmed with Buruli ulcer. The blood samples were diluted 1 in 10 in Roswell Park Memorial Institute (RPMI) medium and incubated for 5 days with recombinant mycolactone PKS domains and mycolyltransferase antigen 85A (Ag85A). Blood samples were obtained before and at completion of antibiotic treatment for 8 weeks and again 8 weeks after completion of treatment. Supernatants were assayed for interferon-γ (IFN-γ) and interleukin-5 (IL-5) by enzyme-linked immunosorbent assay. Responses were compared with those of contacts and non-endemic controls. Results More than 80% of patients and contacts from endemic areas produced IFN-γ in response to all the antigens except acyl carrier protein type 3 (ACP3) to which only 47% of active Buruli ulcer cases and 71% of contacts responded. The highest proportion of responders in cases and contacts was to load module ketosynthase domain (Ksalt) (100%) and enoylreductase (100%). Lower IL-5 responses were induced in a smaller proportion of patients ranging from 54% after ketoreductase type B stimulation to only 21% with ketosynthase type C (KS C). Among endemic area contacts, the, highest proportion was 73% responding to KS C and the lowest was 40% responding to acyltransferase with acetate specificity type 2. Contacts of Buruli ulcer patients produced significantly higher IFN-γ and IL-5 responses compared with those of patients to PKS domain antigens and to mycolyltransferase Ag85A of M. ulcerans. There was low or no response to all the antigens in non-endemic areas controls. IFN-γ and IL-5 responses of patients improved after treatment when compared to baseline results. Discussion The major response to PKS antigen stimulation was IFN-γ and the strongest responses were observed in healthy contacts of patients living in areas endemic for Buruli ulcer. Patients elicited lower responses than healthy contacts, possibly due to the immunosuppressive effect of mycolactone, but the responses were enhanced after antibiotic treatment. A vaccine made up of the most immunogenic PKS domains combined with the mycolyltransferase Ag85A warrants further investigation.

【 授权许可】

Unknown