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Neither Lys- and DAP-type peptidoglycans stimulate mouse or human innate immune cells via Toll-like receptor 2

Marybeth Langer1, Alanson W Girton1,2, Narcis I Popescu1

  • 1The Oklahoma Medical Research Foundation, Program in Arthritis & Immunology, Oklahoma City, OK, United States of America.

Plos One
|February 24, 2018
PubMed

Insights

Highly purified peptidoglycan (PGN) from Bacillus anthracis and Staphylococcus aureus does not activate Toll-like receptor 2 (TLR2). This challenges the long-held view of TLR2 as the primary receptor for bacterial PGN, impacting innate immunity research.

Area of Science:

  • Immunology
  • Microbiology
  • Cell Biology

Background:

  • Peptidoglycan (PGN) is a key bacterial cell wall component and pathogen-associated molecular pattern (PAMP).
  • PGN triggers innate immune responses via cytokine production, crucial during infection.
  • Toll-like receptor 2 (TLR2) has been controversially identified as a PGN receptor, with other receptors also proposed.

Purpose of the Study:

  • To investigate the cellular receptor responsible for peptidoglycan (PGN) recognition.
  • To clarify the role of Toll-like receptor 2 (TLR2) in responding to purified bacterial PGN.

Main Methods:

  • Production of PGN from live Bacillus anthracis and Staphylococcus aureus cultures.
  • Systematic purification of PGN samples.
  • Testing of purified PGN for TLR2 activity to identify the point of TLR2 ligand removal.

Main Results:

  • Live B. anthracis and S. aureus express substantial TLR2 ligands.
  • Highly purified PGN from both bacterial species did not activate TLR2.
  • This indicates that TLR2 is not the sole or primary receptor for purified PGN.

Conclusions:

  • The direct recognition of highly purified peptidoglycan by TLR2 is questionable.
  • Further research is needed to identify the definitive PGN receptor(s) involved in innate immunity.
  • This finding has implications for understanding bacterial infection pathogenesis and host defense mechanisms.

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