Phosphorylcholine mimics the effects of ES-62 on macrophages and dendritic cells.
Modulation of macrophage/dendritic cell (DC) cytokine production by the filarial nematode phosphorylcholine (PC)-containing product, ES-62, is mediated by Toll-like receptor (TLR) 4 and signal transduction depends on the TLR adaptor MyD88. Intriguingly, comparison of TLR4 knock-out (ko) mice with TLR4 mutant C3H/HeJ mice indicates that ES-62 cytokine responses are not dependent on the Pro712 residue of TLR4, which is crucial for the response to bacterial lipopolysaccharide (LPS). Because other immunomodulatory effects of ES-62 have been attributed to PC we have now investigated, using PC conjugated to ovalbumin (PC-Ova), whether PC is responsible for the interaction of ES-62 with TLR4. PC-Ova mimicked the modulation of interleukin (IL)-12 production by ES-62 in a TLR4- and MyD88-dependent manner and as with native ES-62, PC-Ova effects were not dependent on Pro712. Furthermore, both native ES-62 and PC-Ova suppressed Akt phosphorylation, whereas neither altered the activation of p38 or Erk MAP kinases. To rule out any role for the ES-62 protein component, we tested a PC-free recombinant ES-62 (rES-62) generated in the yeast Pichia pastoris. Surprisingly, rES-62 also modulated IL-12 production, but in a TLR4/MyD88-independent manner. Furthermore, rES-62 strongly activated both the p38 and Erk MAP kinases and Akt. However, recent biophysical analysis suggests there are differences in folding/shape between native and rES-62 and hence data obtained with the latter should be treated with caution. Nevertheless, although our study indicates that PC is likely to be primarily responsible for the modulation of cytokine production observed with native ES-62, an immunomodulatory role for the protein component cannot be ruled out.
Goodridge
H S
HS
Division of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G11, UK.
McGuiness
S
S
Houston
K M
KM
Egan
C A
CA
Al-Riyami
L
L
Alcocer
M J C
MJ
Harnett
M M
MM
Harnett
W
W
D000818:Animals; D017931:DNA Primers; D003713:Dendritic Cells / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015801:Helminth Proteins / Q000276:immunology / Q000378:metabolism*; D018664:Interleukin-12 / Q000096:biosynthesis*; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D010047:Ovalbumin; D010767:Phosphorylcholine / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D010843:Pichia; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D017931:DNA Primers; C435884:ES-62 protein, Acanthocheilonema viteae; D015801:Helminth Proteins; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D010767:Phosphorylcholine; D018664:Interleukin-12; D010047:Ovalbumin; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases