CCL-34, a synthetic toll-like receptor 4 activator, modulates differentiation and maturation of myeloid dendritic cells

Abstract

CCL-34, a synthetic α-galactosylceramide analog, has been reported as an activator of toll-like receptor 4 (TLR4) in macrophages. TLR4 is highly expressed in dendritic cell (DC) and several TLR4 agonists are known to trigger DC maturation. We herein evaluated the effect of CCL-34 on DC maturation. Human CD14+ monocyte-derived immature DC were treated with CCL-34, its inactive structural analog CCL-44, or LPS to assess the DC maturation. CCL-34 induced DC maturation according to their characteristically dendrite-forming morphology, CD83 expression and IL-12p70 production. The allostimulatory activity of DC on proliferation of naive CD4+CD45+RA+ T cells and their secretion of interferon-γ was increased by CCL-34. Phagocytosis, an important function of immature DC, was reduced after CCL-34 treatment. All these effects related to DC maturation were evidently induced by positive control LPS but not by CCL-44 treatment. TLR4 neutralization impaired human DC maturation triggered by CCL-34. The induction of IL-12, a hallmark of DC maturation, by CCL-34 and LPS was only evident in TLR4-competent C3H/HeN, but not in TLR4-defective C3H/HeJ mice. CCL-34 could further elicit the antigen presentation capability in mice inoculated with doxorubicin-treated colorectal cancer cells. In summary, CCL-34 triggers DC maturation via a TLR4-dependent manner, which supports its potential application as an immunostimulator.

Vaccine adjuvant activity of a TLR4-activating synthetic glycolipid by promoting autophagy

“…5E), indicating that both LPMs and/or SPMs may function as the APCs in CCL-34-immunized mice. On the other hand, CCL-34 was shown to induce DC maturation ex vivo in our previous study 30 . The role of DCs in CCL-34-mediated adjuvant activity in animal model remains further investigation.…”

“…Our previous data have demonstrated that CCL-34 activates the TLR4 signaling pathway and induces cytokines related to the immune response 29,30 . In this study, we further showed that the Ag-specific T cells were was measured using ELISA.…”

“…Our previous studies found that the synthetic glycolipid, CCL-34, can activate macrophages and induce maturations of DCs in a TLR4-dependent manner [28][29][30] . CCL-34 also exhibits anticancer activity via macrophage-released NO-mediated thoc1 downregulation in cancer cells 39 .…”

“…1A) that induces the activation of macrophages and the maturation of dendritic cells in a TLR4-dependent manner. Additionally, CCL-34 exhibits anticancer activity in vitro and in vivo via TLR4-dependent activation of innate immunity [28][29][30] . Although the mRNA levels of T cell markers (CD4 and CD8) and related cytokines (IFN-γ and IL-12) have been observed to be increased in the tumor sites of CCL-34-treated mice 28 , whether CCL-34 can induce autophagy to facilitate Ag processing and thus enhance Ag-specific adaptive immunity remains unexplored.…”

Serine-/Cysteine-Based sp2-Iminoglycolipids as Novel TLR4 Agonists: Evaluation of Their Adjuvancy and Immunotherapeutic Properties in a Murine Model of Asthma

“…Compared with other known TLR4 agonists, CCL-34 has the advantages of a defined structure, easier synthesis, and less contamination with bioactive microbial components. It has been shown to modulate differentiation and maturation of myeloid DCs and to elicit anticancer immunity via TLR4. , Structure–activity relationship studies demonstrated that the sugar portion plays an essential role in the biological properties. The configurational pattern of the monosaccharide admitted substantial variability.…”