Medical Microbiology and Immunology

, Volume 200, Issue 3, pp 177–191

Conversion of Mycobacterium smegmatis to a pathogenic phenotype via passage of epithelial cells during macrophage infection

Authors

  • Su-Young Kim
    • Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical CenterSungkyunkwan University School of Medicine
  • Hosung Sohn
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Go-Eun Choi
    • Department of Laboratory Medicine, School of Medicine and Medical Research InstitutePusan National University
  • Sang-Nae Cho
    • Department of Microbiology and Institute of Immunology and Immunological DiseasesYonsei University College of Medicine
  • Taegwon Oh
    • Department of Microbiology and Institute of Immunology and Immunological DiseasesYonsei University College of Medicine
  • Hwa-Jung Kim
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Jake Whang
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Jong-Seok Kim
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Eui-Hong Byun
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Woo Sik Kim
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Ki-Nam Min
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
  • Jin Man Kim
    • Department of Pathology, College of MedicineChungnam National University
    • Department of Microbiology and Infectious Signaling Network Research Center, Research Institute for Medical Sciences, College of MedicineChungnam National University
Original Investigation

DOI: 10.1007/s00430-011-0190-5

Cite this article as:
Kim, S., Sohn, H., Choi, G. et al. Med Microbiol Immunol (2011) 200: 177. doi:10.1007/s00430-011-0190-5

Abstract

Mycobacteria encounter many different cells during infection within their hosts. Although alveolar epithelial cells play an essential role in host defense as the first cells to be challenged upon contact with mycobacteria, they may contribute to the acquisition of mycobacterial virulence by increasing the expression of virulence or adaptation factors prior to being ingested by macrophages on the side of pathogens. From this aspect, the enhanced virulence of nonpathogenic Mycobacterium smegmatis (MSM) passed through human alveolar A549 epithelial cells (A-MSM) was compared to the direct infection of MSM (D-MSM) in THP-1 macrophages and mouse models. The intracellular growth rate and cytotoxicity of A-MSM were significantly increased in THP-1 macrophages. In addition, compared to D-MSM, A-MSM induced relatively greater interleukin (IL)-1β, IL-6, IL-8, IL-12, TNF-α, MIP-1α, and MCP-1 in THP-1 macrophages. As a next step, a more persistent A-MSM infection was observed in a murine infection model with the development of granulomatous inflammation. Finally, 58 genes induced specifically in A-MSM were partially identified by differential expression using a customized amplification library. These gene expressions were simultaneously maintained in THP-1 infection but no changes were observed in D-MSM. Bioinformatic analysis revealed that these genes are involved mainly in bacterial metabolism including energy production and conversion, carbohydrate, amino acid, and lipid transport, and metabolisms. Conclusively, alveolar epithelial cells promoted the conversion of MSM to the virulent phenotype prior to encountering macrophages by activating the genes required for intracellular survival and presenting its pathogenicity.

Keywords

Mycobacterium smegmatisEnhanced virulenceEpithelial cellPathogenicityInduced gene

Supplementary material

430_2011_190_MOESM1_ESM.ppt (870 kb)
Supplementary Fig. 1 Spot density of dot blot hybridization of PCR probes with the Mycobacterium smegmatis library. Dot blots were hybridized with radio-labeled PCR probes under various conditions. Lane 1, M. smegmatis control; lane 2, M. smegmatis from THP-1; lane 3, M. smegmatis from A549; lane 4, M. smegmatis by passing A549 in THP-1 infection. The original results of dot blot hybridization are shown in the upper panel (a). The dot blot hybridization results were analyzed using ArrayGauge software. Spot density was indicated numerically and by color. The highest and lowest levels of expression are represented by red and blue, respectively (b). (PPT 869 kb)
430_2011_190_MOESM2_ESM.doc (102 kb)
Supplementary material 2 (DOC 102 kb)

Copyright information

© Springer-Verlag 2011