Acute seizures after a severe brain insult can often lead to epilepsy and cognitive impairment. Aberrant hippocampal neurogenesis follows the insult but the role of adult-generated neurons in the development of chronic seizures or associated cognitive deficits remains to be determined. Here we show that ablation of adult neurogenesis prior to pilocarpine-induced acute seizures in mice leads to a reduction in chronic seizure frequency. We also show that ablation of neurogenesis normalizes epilepsy-associated cognitive deficits. Remarkably, the effect of ablating adult neurogenesis prior to acute seizures is long-lasting as it suppresses chronic seizure frequency for nearly one year. These findings establish a key role of neurogenesis in chronic seizure development and associated memory impairment and suggest that targeting aberrant hippocampal neurogenesis may reduce recurrent seizures and restore cognitive function following a pro-epileptic brain insult.

Purpose Infusion of interleukin-12 (IL-12) can mediate anti-tumor immunity in animal models, yet its systemic administration to patients with cancer results in minimal efficacy and severe toxicity. Here, we evaluated the anti-tumor activity of adoptively transferred human tumor infiltrating lymphocytes (TIL) genetically engineered to secrete single-chain IL-12 selectively at the tumor site. Experimental design Thirty-three patients with metastatic melanoma were treated in a cell-dose escalation trial of autologous TIL transduced with a gene encoding a single chain IL-12 driven by a nuclear factor of activated T cells promoter (NFAT.IL12). No IL-2 was administered. Results The administration of 0.001-0.1 X 109 NFAT.IL12 transduced TIL to 17 patients resulted in a single objective response (5.9%). However, at doses between 0.3-3 X 109 cells, 10 of 16 patients (63%) exhibited objective clinical responses. The responses tended to be short and the administered IL-12 producing cells rarely persisted at one month. Increasing cell doses were associated with high serum levels of IL-12 and gamma-interferon as well as clinical toxicities including liver dysfunction, high fevers and sporadic life threatening hemodynamic instability. Conclusions In this first-in-man trial, administration of TIL transduced with an inducible IL-12 gene mediated tumor responses in the absence of IL-2 administration using cell doses 10-100 fold lower than conventional TIL. However, due to toxicities, likely attributable to the secreted IL-12, further refinement will be necessary before this approach can be safely utilized in the treatment of cancer patients.

Interleukin-12 (IL-12) is an important immunostimulatory cytokine, yet its clinical application has been limited by the systemic toxicity associated with its administration. In this work, we developed a strategy to selectively deliver IL-12 to the tumor environment using genetically engineered lymphocytes. However, peripheral blood lymphocytes (PBLs) transduced with a γ-retroviral vector, which constitutively expressed IL-12, failed to expand in culture due to apoptosis. To circumvent this problem, a vector was designed where IL-12 expression was directed by a composite promoter-containing binding motifs for nuclear factor of activated T-cells (NFAT.hIL12.PA2). The NFAT-responsive promoter was activated to drive IL-12 expression upon the recognition of tumor-specific antigen mediated by a T cell receptor (TCR) that was engineered into the same lymphocytes. We tested the efficacy of the inducible IL-12 vector in vivo in a murine melanoma model. Adoptive transfer of pmel-1 T cells genetically engineered with NFAT-murineIL12 (NFAT.mIL12.PA2) significantly enhanced regression of large established B16 melanoma. Notably, this targeted and controlled IL-12 treatment was without toxicity. Taken together, our results suggest that using the NFAT.hIL12.PA2 vector might be a promising approach to enhance adoptive cancer immunotherapy.