Panoramic comparison between NK cells in healthy and cancerous liver through single-cell RNA sequencing

Objective:NK cells play crucial roles in the immune defense mechanisms against viral infections and transformed cells.However,the developmental progression,transcriptomic landscape,and functional subtypes of liver NK cells are not well defined.Hepatocellular carcinoma(HCC)accounts for approximately 80%of primary liver cancer worldwide,yet the biological characteristics of NK cells in the HCC environment are unclear.Therefore,we aimed to determine these cells’roles in tumorigenesis and prognosis.Methods:We compared the single-cell RNA sequencing profiles of NK cells purified from blood(n=1),healthy liver tissues(n=3),HCC tumor tissues(n=4),and peritumor liver tissues(n=1)to identify NK cell subsets.Furthermore,we performed bioinformatics analysis by using The Cancer Genome Atlas(TCGA)data to identify prognostic biomarkers simultaneously overexpressed in the blood and tumor tissues of patients with HCC.Results:Transcriptomic analysis revealed 5 NK cell subsets(L1-NK-CD56bright,L2-NK-CD56dim,L3-NK-HLA,L4-LrNK-FCGR3A,and L5-LrNK-XCL1)in the healthy liver tissues.However,the transitional L3 subset and the CXCR6+CD16+L4 subset with strong anti-tumor activity were absent in the HCC and peritumor liver tissues.Furthermore,4 common prognosis-associated genes(RHOB,TALDO1,HLA-DPA1,and TKT)were significantly overexpressed in the paired tumor tissue and blood.Conclusions:Our study revealed 5 specific subsets of NK cells in healthy human liver tissues.However,only 3 of the 5 NK cell subsets were present in HCC and peritumor tissues.The cytotoxic NK cell subsets were absent in HCC tissues.Furthermore,we identified 4 potential non-invasive prognostic biomarkers in patients with HCC.

Influence of immunosuppressive drugs on natural killer cells in therapeutic drug exposure in liver transplantation

Background:Natural killer(NK)cells are enriched in the liver and are the main regulators in liver transplantation regarding rejection or tolerance,viral infection,or tumor recurrence.Immunosuppression consists of a triple drug standard regimen comprising tacrolimus(TAC)and corticosteroids(CS)with either mycophenolate mofetil(MMF)or sirolimus(SIR)/everolimus(EVE).The aim of this study was to evaluate the impact of trough levels of these regimens under clinical conditions and exposure on human NK-cell activity and function in order to better understand the antiviral and anti-tumor effects of mammalian target of rapamycin inhibitor(mTORI).Methods:Peripheral blood mononuclear cells(PBMCs)were collected from liver transplant recipients and healthy controls.Number and phenotypes of NK cells in vivo were analyzed by flow cytometry.In this study we simulated the immunosuppressive microenvironment in vitro.PBMCs were cultured at the clinically effective plasma concentration of drugs for 3 d to detect the effect of immunosuppressants on NK cells.Drug type and concentration:single drug[EVE,5 ng/mL;SIR,5 ng/mL;TAC,5 ng/mL;cyclosporine A(CSA),125 ng/mL;MMF,15μg/mL;CS,0.5μg/mL]and combined immunosuppressants(Group 1:TAC,5 ng/mL+MMF,15μg/mL+CS,0.5μg/mL;Group 2:TAC,5 ng/mL+SIR,5 ng/mL+CS,0.5μg/mL;Group 3:TAC,5 ng/mL+EVE,5 ng/mL+CS,0.5μg/mL).In addition,NK cells were sorted from PBMCs and treated under the above conditions to detect NK cell killing function and RNA transcription characteristics.Results:CS significantly impaired the cytolytic activity of NK cells,followed by MMF and SIR/EVE.CS and TAC/CSA significantly decreased the secretion of IFN-γand CD107a.NK cell function in liver transplant recipients was most pronouncedly inhibited by a triple immunosuppressive regimen,with CS playing the most prominent role compared with the other drugs.The MMF-containing regimen demonstrated a significant increase in the expression of suppressive genes,especially of the Siglec7/9 family.The SIR group had stronger NK cell activity compared with that of the MMF group,although liver transplantation patients have lower NK cell activity and function.Conclusions:Despite an overall comparable immunosuppressive efficiency in terms of prevention of acute rejection,a mTORIs-including regimen might be considered as having less impact on NK cell function.

The SNAPc complex mediates starvation-induced trans-splicing in Caenorhabditis elegans

Dietary restriction usually suppresses biosynthesis but activates catabolic pathways in animals.However,the short-term starvation enhances biosynthetic activities and promotes ribosomal biogenesis in adult Caenorhabditis elegans.The mechanism underlying the processes remains largely unknown.Here,we find that the short-term starvation enhances the SL1 trans-splicing of translation-related genes in adult C.elegans by transcriptome analysis.The small nuclear RNA-activating protein complex(SNAPc)promotes SL RNA production and mediates starvation-induced trans-splicing.TOFU-5,a core factor in the upstream sequence transcription complex(USTC)essential for piRNA production,is also involved in the starvationinduced trans-splicing processes.Knocking down components of the SNAPc complex and tofu-5 extends worm survival under starvation conditions.Taken together,our study highlights the importance of SL transsplicing in the nutrition response and reveals a mechanism of the survival regulation by food deprivation via SNAPc and TOFU-5.