Anti-inflammatory agents, such as glucocorticoids and VIP, can directly suppress the function of monocytes and macrophages and result in the inhibition of TLR4 ligand-induced TNF-α production.9 In contrast, GPC81–95 inhibits TLR4 ligand-induced TNF-α production by generating CD4+ T cells with anti-inflammatory properties. GPC81–95 stimulates LAP (TGF-β1) expression on only a small
fraction of primary CD4+ T cells (1–2·6%) or Jurkat T cells (3–4%). It is likely that specific receptor(s) are involved in the recognition of the identified peptide and the expression of these receptors may be up-regulated in a small population of primary CD4+ T cells. However, this hypothesis may
not Selleckchem GDC-0068 explain why only a small population of Jurkat T cells responded to the peptide stimulation. It is possible, but not proven, that up-regulation of LAP (TGF-β1) is confined Olaparib concentration to the physiological condition of cells such as a stage of cell division. The fact that only small population of CD3+ CD4+ T cells responded to anti-CD3 antibody and expressed LAP (TGF-β1) supports this notion. Although, the majority of CD4+ T cells express CD3 molecules but only a small population of CD3+ CD4+ T cells responded to anti-CD3 antibody and expressed LAP (TGF-β1). Anti-CD3 antibody is the only known ligand that induces LAP (TGF-β1) expression on CD4+ T MRIP cells and the administration of this antibody suppresses inflammatory conditions in a TGF-β1-dependent manner.3,27 Our data have shown that both GPC81–95 and anti-CD3 antibody induce LAP (TGF-β1) on primary CD4 T cells. It has been suggested that GARP (glycoprotein-A repetitions predominant) is essential for surface expression of
LAP (TGF-β1) on activated regulatory T cells.1 In our hands, no positive cells were detected in resting primary CD4 T cells using the only commercially available anti-GARP antibody (LRRC32 monoclonal antibody; Enzo Life Science, Exeter, UK) (isotype control IgG2b; Enzo Life Science). Using this antibody, no positive cells were detected in GPC81–95 or anti-CD3 antibody-induced LAP expressing primary CD4 T cells (data not shown). Therefore, we are unable to confirm or exclude the possibility that GARP may be expressed on these cells. Further studies are planned to demonstrate whether GPC81–95 can induce LAP (TGF-β1) expression and inhibit inflammation in an in vivo model. Previously self-derived synthetic peptides that exert immunoregulatory effects via induction of TGF-β1 and activation of regulatory T cells have been described. These peptides are derived from a conserved region of the MHC class II molecule and are shown to bind to the MHC and alter T-cell receptor (TCR) –MHC interaction, thereby exerting their inhibitory effect via the TCR.