Burkholderia pseudomallei induces IL-23 production in primary human monocytes
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Burkholderia pseudomallei, a gram-negative intracellular bacterium, is a causative agent of melioidosis. The bacterium has been shown to induce the innate immune response, particularly pro-inflammatory cytokine production in several of both mouse and human cell types. In the present study, we investigate host immune response in B. pseudomallei-infected primary human monocytes. We discover that wild-type B. pseudomallei is able to survive and multiply inside the primary human monocytes. In contrast, B. pseudomallei LPS mutant, a less virulent strain, is susceptible to host killing during bacterial infection. Moreover, microarray result showed that wild-type B. pseudomallei but not B. pseudomallei LPS mutant is able to activate gene expression of IL-23 as demonstrated by the up-regulation of p19 and p40 subunit expression. Consistent with gene expression analysis, the secretion of IL-23 analyzed by ELISA also showed that wild-type B. pseudomallei induces a significantly higher level of IL-23 secretion than that of B. pseudomallei LPS mutant. These results implied that IL-23 may be an important cytokine for the innate immune response during B. pseudomallei infection. The regulation of IL-23 production may drive the different host innate immune responses between patients and may relate to the severity of melioidosis.
KeywordsB. pseudomallei Human monocytes IL-23 Melioidosis
This work was supported by research grants from Thailand Research Fund (TRF, Thailand) and Faculty of Science, Mahidol University (Thailand). We thank Prof. Dr. D.E. Woods (Department of Microbiology and Infectious Diseases, the University of Calgary Health Sciences Center, Calgary, Alberta, Canada) for providing wild-type B. pseudomallei (1026b) and B. pseudomallei LPS mutant (SRM117). SD is grateful for the support of a Wellcome Trust Intermediate Clinical Fellowship award ref WT100174AIA. NC was supported by the Wellcome Trust [087769/Z/08/Z].
Compliance with ethical standards
Conflict of interest
All authors have no financial or commercial conflict of interest to declare.
For all human blood collections were conformed to the ethical standards guidelines of the Declaration of Helsinki and were approved by the human subjects committees. Ethical clearance for the human blood collection was obtained by the Ethical Committee of Ramathibodi Hospital, Mahidol University, Bangkok, Thailand (Ethical clearance number MURA 2011/607).
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