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Using a Bacterial Pathogen to Probe for Cellular and Organismic-level Host Responses
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Mitogenic component in polar lipid-enriched Anaplasma phagocytophilum membranes

Kyoung-Seong Choi1, J Stephen Dumler

  • 1College of Life Sciences and Natural Resources, Department of Animal Science, Sangju National University, Sangju 742-711, Korea.

Clinical and Vaccine Immunology : CVI
|August 10, 2007
PubMed

Insights

Components within Anaplasma phagocytophilum membranes stimulate innate immune cell proliferation. Polar lipids, particularly from low-passage bacteria, significantly enhance splenocyte lymphoproliferation, suggesting a role in immune response.

Area of Science:

  • Immunology
  • Microbiology
  • Tick-borne diseases

Background:

  • Human granulocytic anaplasmosis is an emerging tick-borne disease caused by Anaplasma phagocytophilum.
  • A. phagocytophilum activates Toll-like receptor 2 signaling and NKT cells.
  • The role of membrane components in innate immune activation is unclear.

Purpose of the Study:

  • To investigate the role of A. phagocytophilum membrane components in innate immune response.
  • To determine if lipoprotein or glycolipid components trigger immune response and immunopathology.
  • To compare the mitogenic activity of membrane fractions from different bacterial passages.

Main Methods:

  • Preparation of A. phagocytophilum membrane fractions depleted of Msp2 and protein antigens.
  • Treatment of naïve mouse splenocytes with membrane fractions.
  • Assessment of splenocyte proliferation and lymphoproliferation.

Main Results:

  • Membranes depleted of Msp2 and protein antigens enhanced splenocyte proliferation compared to untreated membranes.
  • Protein-depleted and polar lipid-enriched membranes from low-passage A. phagocytophilum showed significantly greater lymphoproliferation (4.8- to > or =17.7-fold) than those from high-passage cultures.
  • Polar lipid-enriched fractions demonstrated the highest mitogenic activity.

Conclusions:

  • Components enriched in A. phagocytophilum polar lipids stimulate innate immune cell proliferation.
  • These findings support the hypothesis that membrane lipids are key triggers of the innate immune response.
  • The results suggest a potential role for NKT cell activation by these lipid components, linking innate and adaptive immunity and contributing to immunopathology.

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