Induction of Th1-biased cytokine production by  -carba-GalCer, a neoglycolipid ligand for NKT cells

Abstract

NKT cells are characterized by their production of both T(h)1 and T(h)2 cytokines immediately after stimulation with alpha-galactosylceramide (alpha-GalCer), which is composed of alpha-galactopyranose linked to ceramide (itself composed of sphingosine and fatty-acyl chains); the chain length of the ceramide varies and this affects the ability of alpha-GalCer to stimulate cytokine production. However, the contribution of its galactopyranose sugar moiety remains unclear. We synthesized alpha-carba-GalCer, which has an alpha-linked carba-galactosyl moiety; here, the 5a'-oxygen atom of the D-galactopyranose ring of alpha-GalCer is replaced by a methylene group. The alpha-carba-GalCer was more stable and showed higher affinity to the NKT receptor. It thus enhanced and prolonged production of IL-12 and IFN-gamma compared with alpha-GalCer, resulting in augmented NKT cell-mediated adjuvant effects in vivo. The alpha-carba-GalCer, which has an ether linkage, was more resistant to degradation by liver microsomes than was alpha-GalCer, which has an acetal bond. Modulation of the sugar moiety in glycolipids might therefore provide optimal therapeutic reagents for protective immune responses against tumor or pathogens.

Activation of natural killer T cells by α-carba-GalCer (RCAI-56), a novel synthetic glycolipid ligand, suppresses murine collagen-induced arthritis

“…Conversely, a-C-GalCer, a C-glycoside (carbon glycoside) analogue of a-GalCer, activated iNK T cells at very low concentrations and promoted Th1 responses in vivo [31]. More recently, Tashiro et al [32] synthesized a-carbaGalCer, which strongly induced NK T cell-mediated Th1 cytokines in a fashion similar to a-C-GalCer [32].…”

Structure-Activity Relationship Studies of Novel Glycosphingolipids That Stimulate Natural Killer T-Cells

“…Although its synthesis is not easy, RCAI-56 (13) can also induce potent Th1-cytokine production. 75,76,80) Recently, Yoshiga et al reported that 13 suppressed murine collagen-induced arthritis by enhancing the Th1 response. 160) RCAI-61 (14), developed by a simple modification, as shown in Fig.…”

“…As we expected, this ethereal analog 13 resisted enzymatic degradation in a liver microsome assay more than 1, and induced potent Th1-cytokine production not only in mice but also in humans, in contrast to -CGalCer (10). 80) According to the crystal structures of binary CD1d/-galactosyl ceramide complexes, 18,19) the glycosidic oxygen atom is involved in a hydrogenbonding network, and might be important in making a stable complex, especially with human CD1d. Detailed docking model study and elucidation and comparison of the crystal structure of human CD1d/13/TCR to those of 10 should clarify the differences in bioactivity between -C-GalCer (10) and RCAI-56 (13).…”

“…75,76,80) Among the cyclitol analogs synthesized by us, RCAI-59 (45) an 92 (46) were remarkably potent immunostimulants against mouse lymphocytes, producing IFN-. 76) Castaño, Llebaria, and co-workers reported that an aminocyclitol analog (HS44, 47) induced weak cytokine production and strong proliferation activity.…”

Improved proliferation of antigen-specific cytolytic T lymphocytes using a multimodal nanovaccine

“…In this in vivo cytokine study, we used similar time frame for PBS-44 as for αGalCer. 29,30 Further, considering the slow release of the NanoVac, we chose 24 hours posttreatment. As shown in Figure 4A, B, the levels of IFN-γ and IL-4 in the NanoVac-treated cohort increased …”