Preferential production of G-CSF by a protein-like Lactobacillus rhamnosus GR-1 secretory factor through activating TLR2-dependent signaling events without activation of JNKs.
BACKGROUND
Different species and strains of probiotic bacteria confer distinct immunological responses on immune cells. Lactobacillus rhamnosus GR-1 (GR-1) is a probiotic bacterial strain found in both the intestinal and urogenital tracts, and has immunomodulatory effects on several cell types including macrophages. However, detailed immunological responses and the signaling mechanism involved in the response are largely unknown.


RESULTS
We examined the production of GR-1-induced cytokines/chemokines and signaling events in macrophages. Among 84 cytokines and chemokines examined, GR-1 discretely induced granulocyte colony-stimulating factor (G-CSF) mRNA at highest levels (>60-fold) without inducing other cytokines such as IL-1α, IL-1β, IL-6 and TNF-α (<5-fold). The toll-like receptor (TLR) 2/6-agonist PAM2CSK4, TLR2/1-agonist PAM3CSK4 and TLR4-agonist lipopolysaccharide induced all of these inflammatory cytokines at high levels (>50-fold). The TLR2 ligand lipoteichoic acid activated all mitogen-activated kinases, Akt and NF-κB; whereas, GR-1 selectively activated extracellular regulated kinases and p38, NF-κB and Akt, but not c-Jun N-terminal kinases (JNKs) in a TLR2-dependent manner. Using specific inhibitors, we demonstrated that lack of JNKs activation by GR-1 caused inefficient production of pro-inflammatory cytokines but not G-CSF production. A secreted heat-labile protein-like molecule, 30-100 kDa in size, induced the preferential production of G-CSF.


CONCLUSIONS
This study elucidated unique signaling events triggered by GR-1, resulting in selective production of the immunomodulatory cytokine G-CSF in macrophages.
Department of Microbiology and Immunology and Infectious Diseases Research Group, Siebens-Drake Research Institute, Western University, London, ON, N6G 2 V4, Canada. smeshkib@uwo.ca.|Center for Human Immunology, Western University, London, ON, N6G 2 V4, Canada. smeshkib@uwo.ca.
Shahab
S
Meshkibaf
Department of Microbiology, McGill University, Montreal, QC, H3G 0B1, Canada. jorg.fritz@mcgill.ca.
Jӧrg
J
Fritz
Faculty of Veterinary Medicine, University of Montreal, St-Hyacinthe, QC, J2S 2 M2, Canada. marcelo.gottschalk@umontreal.ca.
Marcelo
M
Gottschalk
Department of Microbiology and Immunology and Infectious Diseases Research Group, Siebens-Drake Research Institute, Western University, London, ON, N6G 2 V4, Canada. sung.kim@schulich.uwo.ca.|Center for Human Immunology, Western University, London, ON, N6G 2 V4, Canada. sung.kim@schulich.uwo.ca.
Sung Ouk
SO
Kim
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D020869:Gene Expression Profiling; D016179:Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis*; D052201:Lacticaseibacillus rhamnosus / Q000276:immunology*; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology*; D008297:Male; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016133:Polymerase Chain Reaction; D015398:Signal Transduction; D051195:Toll-Like Receptor 2 / Q000378:metabolism*; D037521:Virulence Factors / Q000276:immunology* / Q000378:metabolism
C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D037521:Virulence Factors; D016179:Granulocyte Colony-Stimulating Factor