Acute Myeloid Leukemia Causes T Cell Exhaustion and Depletion in a Humanized Graft-versus-Leukemia Model.

Allogeneic hematopoietic stem cell transplantation (alloSCT) is, in many clinical settings, the only curative treatment for acute myeloid leukemia (AML). The clinical benefit of alloSCT greatly relies on the graft-versus-leukemia (GVL) effect. However, AML relapse remains the top cause of posttransplant death; this highlights the urgent need to enhance GVL. Studies of human GVL have been hindered by the lack of optimal clinically relevant models. In this article, we report, the successful establishment of a novel (to our knowledge) humanized GVL model system by transplanting clinically paired donor PBMCs and patient AML into MHC class I/II knockout NSG mice. We observed significantly reduced leukemia growth in humanized mice compared with mice that received AML alone, demonstrating a functional GVL effect. Using this model system, we studied human GVL responses against human AML cells in vivo and discovered that AML induced T cell depletion, likely because of increased T cell apoptosis. In addition, AML caused T cell exhaustion manifested by upregulation of inhibitory receptors, increased expression of exhaustion-related transcription factors, and decreased T cell function. Importantly, combined blockade of human T cell-inhibitory pathways effectively reduced leukemia burden and reinvigorated CD8 T cell function in this model system. These data, generated in a highly clinically relevant humanized GVL model, not only demonstrate AML-induced inhibition of alloreactive T cells but also identify promising therapeutic strategies targeting T cell depletion and exhaustion for overcoming GVL failure and treating AML relapse after alloSCT.

Genetic characterization of Sus scrofa papillomavirus type 1 from domestic pigs in Guangxi Province, China.

Sus scrofa papillomatosis (SsP) is a tumour caused by Sus scrofa papillomaviruses (SsPVs). To investigate the presence of SsPVs in China, 354 domestic pig skin samples collected from Guangxi Province were examined for SsPV DNA by PCR. Three SsPV1s (GX12, GX14, and GX18) were identified with a prevalence of 0.847% (3/354). Sequence analysis showed that L1 of SsPV1/GX12 and SsPV1/GX14 had 99.7% and 99.6% nucleotide identify with the reference SsPV1a, respectively. Phylogenetic and evolutionary analyses showed that SsPV1/GX12 and SsPV1/14 clustered into SsPV1a and that SsPV1/GX18 clustered into SsPV1b. Compared with other SsPV L1 and L2 proteins, we found that the SsPV1/GX18 and SsPV1b strains shared the same unique substitutions, and SsPV1/GX12, SsPV1/GX14, and SsPV1a shared almost identical amino acid sequences. This study reports the first detection of SsPV DNA in China based on whole genome information and provides a scientific basis for the development of SsPV pathogenic biology, epidemiology, and prevention, as well as control technology research.