Efficient Regeneration of Human Vα24+ Invariant Natural Killer T Cells and Their Anti-Tumor Activity In Vivo.

Reprogramming of antigen-specific T lymphocytes into induced pluripotent stem cells (iPSCs) and their subsequent re-differentiation has enabled expansion of functional T lymphocytes in vitro, thus opening up new approaches for immunotherapy of cancer and other diseases. In this study, we have established a robust protocol to reprogram human invariant NKT (Vα24+ iNKT) cells, which have been shown to act as cellular adjuvants and thus exert anti-tumor activity in mice and humans, and to re-differentiate the iNKT cell-derived iPSCs into functional iNKT cells. These iPSC-derived iNKT cells (iPS-Vα24+ iNKT cells) can be activated by ligand-pulsed dendritic cells (DCs) and produce a large amount of interferon-γ upon activation, as much as parental Vα24+ iNKT cells, but exhibit even better cytotoxic activity against various tumor cell lines. The iPS-Vα24+ iNKT cells possess significant anti-tumor activity in tumor-bearing mice and can activate autologous NK cells upon activation by ligand-pulsed DCs in the NOG mouse model in vivo, further extending their therapeutic potential. This study thus provides a first proof of concept for the clinical application of human iPS-Vα24+ iNKT cells for cancer immunotherapy. Stem Cells 2016;34:2852-2860.

Synthesis and biological evaluation of deoxy-hematoxylin derivatives as a novel class of anti-HIV-1 agents.

SAR studies for the exploration a novel class of anti-human immunodeficiency virus type 1 (HIV-1) agents based on the hematoxylin structure (1) are described. The systematic deoxygenations of 1 including asymmetric synthesis were conducted to obtain a compound showing high potencies for inhibiting the nuclear import and viral replication as anti-HIV-1 agent. Among all, C-3-deoxygenated analog 16 exhibited most promising biological activities as anti-HIV-1 agent such as lower cytotoxicity (16:1; >80:40 µM), stronger inhibition of nuclear import (0.5:1.3 µM), and viral replication in HIV-1-infected TZM-bl cells (24.6:100 µM), human peripheral blood mononuclear cells (PMBCs) (30.1 µM: toxic). Different spectra of inhibitory activities against infected three healthy humans macrophages with high (donor A) and low (donor B and C) amounts of virus were also observed. Thus 16 showed 10-times stronger activity than 1 (16:1; 0.1:<1.0 µM) in the case of A, while 16 and 1 showed comparable activities in the cases of B and C (>0.01 and >0.00 1µM). The comparison of the inhibition of viral p24 antigen production was clearly indicated that compound 16 is at least twofold more potent anti-viral activity than 1. Thus, structures and actions of deoxy analogs particularly 16 could provide valuable information for the development of a novel class of anti-HIV-1 agents.

Murine induced pluripotent stem cells can be derived from and differentiate into natural killer T cells.

NKT cells demonstrate antitumor activity when activated to produce Th1 cytokines by DCs loaded with alpha-galactosylceramide, the prototypic NKT cell-activating glycolipid antigen. However, most patients do not have sufficient numbers of NKT cells to induce an effective immune response in this context, indicating a need for a source of NKT cells that could be used to supplement the endogenous cell population. Induced pluripotent stem cells (iPSCs) hold tremendous potential for cell-replacement therapy, but whether it is possible to generate functionally competent NKT cells from iPSCs has not been rigorously assessed. In this study, we successfully derived iPSCs both from embryonic fibroblasts from mice harboring functional NKT cell-specific rearranged T cell receptor loci in the germline and from splenic NKT cells from WT adult mice. These iPSCs could be differentiated into NKT cells in vitro and secreted large amounts of the Th1 cytokine IFN-gamma. Importantly, iPSC-derived NKT cells recapitulated the known adjuvant effects of natural NKT cells and suppressed tumor growth in vivo. These studies demonstrate the feasibility of expanding functionally competent NKT cells via an iPSC phase, an approach that may be adapted for NKT cell-targeted therapy in humans.