Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome characterized by the dysfunction of cytotoxic T cells (CTLs) and natural killer (NK) cells. The status of these immune cells during persistent inflammation remains unclear. This study aimed to investigate the immune cell subsets, the exhaustion and activation status, and the cytotoxic functions of the CTLs and NK cells in adult HLH. Furthermore, the features of immune cells in patients with Epstein-Barr virus-associated HLH (EBV-HLH) before and after treatment with programmed death-1 (PD-1) inhibitors were also analyzed.
Flow cytometry was utilized to evaluate the immune cell features in 75 patients with adult HLH.
This study observed skewed immune cell subsets, along with substantial exhaustion and activation in patients with adult HLH. Significant decreases were noted in NK, natural killer T (NKT), regulatory T cells (Tregs), CD4+ central memory T (TCM), CD8+ terminal effector memory T (TEMRA), and CD56dimCD16+ NK cells, while increases were found in the CD56brightCD16- and CD56dimCD16- NK subsets. The exhaustion markers (PD-1, TIGIT, and PD-L1) were elevated in CD8+ T cells and NK cells, and the activation markers (CD69, HLA-DR, and CD163) were higher in monocytes. An impaired IFN-γ production and a reduced degranulation function were also detected in CD8+ T cells and NK cells. In EBV-HLH patients treated with PD-1 inhibitors, we observed an increase in cytotoxic CD8+ T cells and CD56dimCD16+ NK cells and a decrease in CD56brightCD16- NK cells.
These findings suggest impairments in cytotoxic immune cells along with a widespread immune exhaustion and an aberrant activation in adult HLH. The results also indicate potential differentiation defects in CD8+ T cells and NK cells. Treatment with a PD-1 inhibitor may contribute to partial functional recovery and support viral clearance in EBV-HLH, which warrant further investigation.
Copyright © 2025 Qin, Zhou, Liu, Dai, Tang, Zhong, Chen, Zhu and Liu.

Macrophage migration inhibitory factor (MIF) has been shown to promote disease progression in many malignancies, including multiple myeloma (MM). We previously reported that MIF regulates MM bone marrow homing and knockdown of MIF favors the extramedullary myeloma formation in mice. Here, based on MIF immunostaining of myeloma cells in paired intramedullary and extramedullary biopsies from 17 patients, we found lower MIF intensity in extramedullary MM (EMM) versus intramedullary MM (IMM). Flow cytometry and histology analysis in xenograft models showed a portion of inoculated human MM cells lost their MIF expression (MIFLow) in vivo. Of note, IMM had dominantly MIFHigh cells, while EMM showed a significantly increased ratio of MIFLow cells. Furthermore, we harvested the extramedullary human MM cells from a mouse and generated single-cell transcriptomic data. The developmental trajectories of MM cells from the MIFHigh to MIFLow state were indicated. The MIFHigh cells featured higher proliferation. The MIFLow ones were more quiescent and harbored abundant ribosomal protein genes. Our findings identified in vivo differential regulation of MIF expression in MM and suggested a potential pathogenic role of MIF in the extramedullary spread of disease.
Copyright © 2021 Xu, Yu, Zhao, Wang, Huang, Cui, Ding, Yang, Gao, Pan, Chang, Wu, Xiang, Gong, Shuai, Hou, Xie, Niu, Liu, Zhang, Liu, Zhang, Qu, Lin, Zhu, Zhao and Zheng.

ABSTRACT Embryonic stem cells (ESC) have the unique ability to differentiate into all three germ cell layers. ESC transition through different states of pluripotency in response to growth factor signals and environmental cues before becoming terminally differentiated. Here, we demonstrated, by a multi-omic strategy, that the deubiquitinase USP9X regulates the developmental potential of ESC, and their transition from a naive to a more developmentally advance, or primed, state of pluripotency. We show that USP9X facilitates developmental gene expression and induces modifications of the mitochondrial bioenergetics, including decreased routing of pyruvate towards its oxidation and reduced respiration. In addition, USP9X binds to the pluripotency factor ESRRB, regulates its abundance and the transcriptional levels of a subset of its target genes. Finally, under permissive culture conditions, depletion of Usp9X accelerates cell differentiation in all cell lineages. We thus identified a new regulator of naive pluripotency and show that USP9X couples ESRRB pluripotency transcriptional network and cellular metabolism, both of which are important for ESC fate and pluripotency.

Blocking programmed death-1 (PD-1) is considered to be a promising strategy to improve T cell function, and this is being explored in many ongoing clinical trials. In fact, our knowledge about PD-1 is primarily based on the results of short-term experiments or observations, but how long-lasting PD-1 blockade can affect T cell function remains unclear.
We planned to use shRNA-based gene knockdown technology to mimic long-lasting PD-1 blockade. We constructed PD-1 steadily blocked chimeric antigen receptor modified T (CAR-T) cells, and with these cells we can clearly study the effects of PD-1 knockdown on T cell function. The anti-tumor function, proliferation ability and differentiation status of PD-1 silenced CAR-T cells were studied by in vitro and animal experiments.
According to short-term in vitro results, it was reconfirmed that the resistance to programmed death-ligand 1 (PD-L1)-mediated immunosuppression could be enhanced by PD-1 blockade. However, better anti-tumor function was not presented by PD-1 blocked CAR-T cells in vitro or in vivo experiments. It was found that PD-1 knockdownmight impair the anti-tumor potential of CAR-T cells because it inhibited T cells' proliferation activity. In addition, we observed that PD-1 blockade would accelerate T cells' early differentiation and prevent effector T cells from differentiating into effect memory T cells, and this might be the reason for the limited proliferation of PD-1 silenced CAR-T cells.
These results suggest that PD-1 might play an important role in maintaining the proper proliferation and differentiation of T cells, and PD-1 silencing would impair T cells' anti-tumor function by inhibiting their proliferation activity.

Exploration and dissection of potential actions and effects of long noncoding RNA (lncRNA) in animals remain challenging. Here, using multiple knockout mouse models and single cell RNA sequencing, we demonstrate that the divergent lncRNA Hand2os1/Uph has a key complex modulatory effect on the expression of its neighboring gene HAND2 and subsequently on heart development and function. Short deletion of the Hand2os1 promoter in mouse diminishes Hand2os1 transcription to ∼8-32%, but fails to affect HAND2 expression and yields no discernable heart phenotypes. Interestingly, full-length deletion of Hand2os1 in mouse causes moderate yet prevalent upregulation of HAND2 in hundreds of cardiac cells, leading to profound biological consequences, including dysregulated cardiac gene programs, congenital heart defects and perinatal lethality. We propose that the Hand2os1 locus dampens HAND2 expression to restrain cardiomyocyte proliferation, thereby orchestrating a balanced development of cardiac cell lineages. This study highlights the regulatory complexity of the lncRNA Hand2os1 on HAND2 expression, emphasizing the need for complementary genetic and single cell approaches to delineate the function and primary molecular effects of an lncRNA in animals.
© 2019. Published by The Company of Biologists Ltd.