A phase I study of multi-HLA-binding peptides derived from heat shock protein 70/glypican-3 and a novel combination adjuvant of hLAG-3Ig and Poly-ICLC for patients with metastatic gastrointestinal cancers: YNP01 trial.

BACKGROUND: This phase I study aimed to evaluate the safety, peptide-specific immune responses, and anti-tumor effects of a novel vaccination therapy comprising multi-HLA-binding heat shock protein (HSP) 70/glypican-3 (GPC3) peptides and a novel adjuvant combination of hLAG-3Ig and Poly-ICLC against metastatic gastrointestinal cancers. METHODS: HSP70/GPC3 peptides with high binding affinities for three HLA types (A*24:02, A*02:01, and A*02:06) were identified with our peptide prediction system. The peptides were intradermally administered with combined adjuvants on a weekly basis. This study was a phase I dose escalation clinical trial, which was carried out in a three patients' cohort; in total, 11 patients were enrolled for the recommended dose. RESULTS: Seventeen patients received this vaccination therapy without dose-limiting toxicity. All treatment-related adverse events were of grades 1 to 2. Peptide-specific CTL induction by HSP70 and GPC3 proteins was observed in 11 (64.7%) and 13 (76.5%) cases, respectively, regardless of the HLA type. Serum tumor marker levels were decreased in 10 cases (58.8%). Immunological analysis using PBMCs indicated that patients receiving dose level 3 presented with significantly reduced T cell immunoglobulin and mucin-domain containing-3 (TIM3)-expressing CD4 + T cells after one course of treatment. PD-1 or TIM3-expressing CD4 + T cells and T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT)-expressing CD8 + T cells in PBMCs before vaccination were negative predictive factors for survival. CONCLUSIONS: This novel peptide vaccination therapy was safe for patients with metastatic gastrointestinal cancers.

Therapeutic effects of soluble human leukocyte antigen G2 isoform in lupus-prone MRL/lpr mice.

Human leukocyte antigen (HLA)-G, a non-classical HLA class I molecule, has one of the splicing isoforms, HLA-G2, which lacks one domain (α2) and forms a non-covalent homodimer. HLA-G2 is expressed on placental cells, regulatory T cells, tumor cells, and virus-infected cells, and is involved in immunosuppression. The major isoform of HLA-G, HLA-G1, binds to leukocyte immunoglobulin (Ig)-like receptor (LILR) B1 and LILRB2, on the contrary, HLA-G2 binds to only LILRB2. We previously reported that HLA-G2 bound LILRB2 more strongly than HLA-G1 and also to paired Ig-like receptor (PIR)-B, a mouse homolog of LILRBs. Furthermore, HLA-G2 showed immunosuppressive effects in both collagen-induced arthritis (CIA) and atopic dermatitis-like model mice. In this study, we examine in vivo effects of HLA-G2 in systemic lupus erythematosus (SLE) model mice. HLA-G2 showed the suppression of the typical SLE symptoms such as serum anti-dsDNA antibody level and urinary albumin index. Furthermore, HLA-G2 tended to downregulate B-lymphocyte stimulator (BLyS) production. This is the first observation of the immunosuppressive effects of HLA-G2 isoform in SLE model mice, suggesting that HLA-G2 could be a useful therapeutic agent for SLE.

Effects of everolimus and HLA-G on cellular proliferation and neutrophil adhesion in an in vitro model of cardiac allograft vasculopathy.

Human leukocyte antigen-G (HLA-G) expression is modulated by immunosuppressant use and is associated with lower incidence of graft rejection and cardiac allograft vasculopathy (CAV). We examined whether everolimus induces HLA-G expression and inhibits human coronary artery smooth muscle cell (HCASMC) proliferation, a critical event in CAV. Also, we examined whether TNFα-stimulated neutrophil adhesion is inhibited by HLA-G on human coronary artery endothelial cells (HCAECs). HLA-G expression in HCASMCs following everolimus treatment was determined by western-blot densitometric analysis. HCASMCs proliferation following incubation with recombinant HLA-G was determined by automated cell counter detecting 2-10 µm particles. Assessment of recombinant HLA-G on neutrophil adhesion to HCAECs in response to TNF-α induced-injury was determined by nonstatic adhesion assays. HLA-G expression was upregulated in HCASMCs following everolimus exposure (1000 ng/ml; P < .05). HLA-G (500, 1000 ng/ml; both P < .05) reduced HCASMC proliferation and inhibited TNFα-stimulated neutrophil adhesion to endothelial cells at all concentrations (0.1-1 ng/ml; all P < .001). Our study reveals novel regulation of HLA-G by everolimus, by demonstrating HLA-G upregulation and subsequent inhibition of HCASMC proliferation. HLA-G is a potent inhibitor of neutrophil adhesion to HCAECs. Findings support HLA-G's importance and potential use in heart transplantation for preventative therapy or as a marker to identify patients at high risk for developing CAV.

The long-term immunosuppressive effects of disulfide-linked HLA-G dimer in mice with collagen-induced arthritis.

HLA-G, a natural immunosuppressant present in the human placenta during pregnancy, prevents fetal destruction by the maternal immune system. The immunosuppressive effect of HLA-G is mediated by the immune cell inhibitory receptors, LILRB1 and LILRB2. HLA-G forms disulfide-linked dimers by natural oxidation, and the dimer associates with LILRB1/B2 much more strongly than the monomer. Furthermore, the dimer formation remarkably enhanced the LILRB-mediated signaling. In this report, we studied the in vivo immunosuppressive effect of the HLA-G dimer, using the collagen-induced arthritis model mouse. Mice were treated with the HLA-G monomer or dimer intracutaneously at the left foot joint, once or for 5 days, and the clinical severity was evaluated daily in a double-blind study. The HLA-G monomer and dimer both produced excellent anti-inflammatory effects with a single, local administration. Notably, as compared to the monomer, the dimer exhibited significant immunosuppressive effects at lower concentrations, which persisted for about two months. In accordance with this result, a binding study revealed that the HLA-G dimer binds PIR-B, the mouse homolog of the LILRBs, with higher affinity and avidity than the monomer. The HLA-G dimer is expected to be quite useful as an anti-rheumatoid arthritis agent, in small amounts with minimal side effects.