Human recombinant heat shock protein 70 affects the maturation pathways of dendritic cells in vitro and has an in vivo adjuvant activity

Abstract

Heat shock proteins (HSPs) are potent inducers of an antigen-specific immunological response. A role of chaperon of immunogenic peptides and a direct effect on APC activation and function have been described. However, the signal transduction events involved in the activation of human APCs are poorly characterized. We investigated, using human monocyte-derived dendritic cells (DCs), the signal transduction pathways activated by a human recombinant HSP70 (r)HSP70 purified from eukaryotic cells. rHSP70 effectively induced a partial maturation of DCs in vitro and a significant increase in the titers of antigen-specific IgG when used as a vaccine adjuvant in vivo. rHSP70 did not desensitize human DCs to LPS stimulation and retained its adjuvant properties in C3H/HeJ mice, which are LPS-resistant as a result of a mutation in TLR-4, ruling out the potential interference of LPS contamination. Effects on DC maturation and in vivo functions correlate to the ability of rHSP70 to activate IkappaB-alpha/NF-kappaB and ERK1/2 pathways in human DCs. No activation of p38 was induced in the same experimental conditions. Our data suggest that the IkappaB-alpha/NF-kappaB pathway has a critical role in the partial maturation of DCs induced by rHSP70.

Dendritic cells matured by a prostaglandin E2-containing cocktail can produce high levels of IL-12p70 and are more mature and Th1-biased than dendritic cells treated with TNF-α or LPS

“…3a). The NFB pathway has been reported to be involved in DC maturation (Lindstedt et al 2002;Ju et al 2003;Platzer et al 2004;Valentinis et al 2008). However, the increase in these transcripts was significantly higher in DCs treated by MC than DCs treated by TNF-␣ or LPS, with exception of IL-1␤, which was higher in LPS-mDCs, and CCL22, which was almost equally increased by all treatments (Fig.…”

“…PNRC1: Proline-rich nuclear receptor coactivator 1, a transcriptional regulator playing a role in signal transduction. It was also up-regulated as a result of NFB signaling in response to LPS stimulation in a monocyte cell line (Valentinis et al 2008). RELB: V-reticulo-endotheliosis viral oncogene homolog B, a member of the NFB family.…”

“…It is suggested to have a critical role in maturation of DCs (Carayol et al 2006). Its up-regulation and nuclear translocation during DC maturation is considered a hallmark for maturation (Valentinis et al 2008). PIM2: It is a protooncogene that promotes cell survival, which is dependent on NFB activation.…”

The Presence of CD14 Overcomes Evasion of Innate Immune Responses by VirulentFrancisella tularensisin Human Dendritic Cells In Vitro and Pulmonary Cells In Vivo

“…Heat shock proteins, e.g., HSP60 and HSP70, are present in both pro-and eukaryotic systems and have been widely recognized as TLR4/MD-2 and TLR2 agonists that require CD14 for efficient delivery to the TLRs (53,(59)(60)(61). Both HSP60 and HSP70 are secreted by F. tularensis into culture medium, but only HSP60 has been found to be secreted during intracellular infection (41).…”

Selection of Adjuvants for Enhanced Vaccine Potency

“…The immunogenicity enhancement can be comparable to that with Freund's adjuvant. Because HSPs can effectively induce partial maturation of DCs in vitro [273], such proteins, as free forms, can also enhance immune responses of antigens but the effect may not be as strong as other adjuvants such as CFA or LPS in mice [273]. Plasmid expressing heat shock proteins (HSPs) could achieve the same effect [274].…”