The Ischemia-Responsive Protein 94 (Irp94) Activates Dendritic Cells through NK Cell Receptor Protein-2/NK Group 2 Member D (NKR-P2/NKG2D) Leading to Their Maturation

Abstract

Tumor recognition and killing, the uptake of released immunogenic substrate, and the generation of immunity are crucial aspects of dendritic cell (DC)-mediated antitumor immune response. In the context of direct tumoricidal activity, we have recently shown NK cell receptor protein-2 (NKR-P2)/NK group 2 member D (NKG2D) as a potent activation receptor on rat DCs. The activation of DCs with agonistic anti-NKR-P2 mAb, the binding of soluble NKR-P2 to the AK-5 tumor, and DC maturation with fixed AK-5 cells led us to identify a putative NKR-P2 ligand on the AK-5 cell surface. In this study we have shown that the AK-5 tumor-derived ischemia-responsive protein-94 (Irp94, a 110 kDa Hsp family member) acts as a functional ligand for NKR-P2 on DCs and enhances Irp94-NKR-P2 interaction-dependent tumor cell apoptosis via NO. Surface expression of Irp94 was also found on tumors of diverse origin in addition to AK-5. Furthermore, the Th1-polarizing cytokine IL-12, produced from Irp94-ligated BMDCs, augments NK cell cytotoxicity. Irp94-NKR-P2 interaction drives the maturation of BMDCs by up-regulating MHC class II, CD86, and CD1a and also induces autologous T cell proliferation, which displays a crucial state of DCs for adaptive antitumor immune response. These functional properties of Irp94 reside in the COOH terminus subdomain but not in the NH2 terminus ATPase domain of Irp94. We also show the involvement of PI3K, ERK, protein kinase C, phosphatases, and NF-κB translocation as downstream mediators of DCs activation upon NKR-P2 ligation with Irp94. Our studies demonstrate for the first time a novel role of a 110-kDa heat shock protein (Irp94) as a ligand for NKR-P2 on DCs, which in turn executes both innate and adaptive immunity.

Heat shock protein 110 improves the anti-tumor effects of the cytotoxic T lymphocyte epitope E7 in mice

“…To evaluate the formation of mHSP110-E7 [49][50][51][52][53][54][55][56][57] complex, the purified mHSP110 and FITC labeled E7 [49][50][51][52][53][54][55][56][57] were mixed in a 1:50 molar ratio and incubated in the binding buffer at 55°C for 30 min, followed by incubation at room temperature for 30 min. The complex was then subjected to 10% non-denaturing PAGE analysis.…”

“…here, we investigated mhsp110 as a chaperone immunoadjuvant to enhance the immune response to hpV16 oncoprotein e7-derived CTL epitope e7 [49][50][51][52][53][54][55][56][57] in a mouse model. We developed the hsp110-e7 [49][50][51][52][53][54][55][56][57] complex and demonstrated that mhsp110 could form complexes with peptide e7 [49][50][51][52][53][54][55][56][57] using FITC-labeled e7 [49][50][51][52][53][54][55][56][57] as the tracer. Inoculation of the mhsp110-e7 [49][50][51][52][53][54][55][56][57] complex was capable of priming strong epitope-specific immune response as determined by its ability to elicit an epitope-specific splenocytes proliferation and a cytotoxic T-cell response, and IFNγ production in splenocytes.…”

“…Inoculation of the mhsp110-e7 [49][50][51][52][53][54][55][56][57] complex was capable of priming strong epitope-specific immune response as determined by its ability to elicit an epitope-specific splenocytes proliferation and a cytotoxic T-cell response, and IFNγ production in splenocytes. Results also showed that immunization with the mhsp110-e7 [49][50][51][52][53][54][55][56][57] complex completely protected mice against subsequent challenge with tumor cells. More importantly, immunization of this complex also significantly inhibited the growth of established tumors and prolonged the survival time of the tumor-bearing animals.…”

“…More importantly, immunization of this complex also significantly inhibited the growth of established tumors and prolonged the survival time of the tumor-bearing animals. Thus, mhsp110-e7 [49][50][51][52][53][54][55][56][57] complex vaccine represents a potentially powerful approach for use in the immunotherapy of cervical cancer associated with hpV16 infection. More importantly, the multi-epitopes derived from e7 and other e proteins can be applied to the strategy described in this study to form a multi-antigenic vaccine to induce an improved antitumor immune response to cervical cancer in the future.…”

“…Heat shock protein 110 improves the antitumor effects of the cytotoxic T lymphocyte epitope E7 [49][50][51][52][53][54][55][56][57] …”