Enteric Viruses Ameliorate Gut Inflammation via Toll-like Receptor 3 and Toll-like Receptor 7-Mediated Interferon-ß Production.

Metagenomic studies show that diverse resident viruses inhabit the healthy gut; however, little is known about the role of these viruses in the maintenance of gut homeostasis. We found that mice treated with antiviral cocktail displayed more severe dextran sulfate sodium (DSS)-induced colitis compared with untreated mice. DSS-induced colitis was associated with altered enteric viral abundance and composition. When wild-type mice were reconstituted with Toll-like receptor 3 (TLR3) or TLR7 agonists or inactivated rotavirus, colitis symptoms were significantly ameliorated. Mice deficient in both TLR3 and TLR7 were more susceptible to DSS-induced experimental colitis. In humans, combined TLR3 and TLR7 genetic variations significantly influenced the severity of ulcerative colitis. Plasmacytoid dendritic cells isolated from inflamed mouse colon produced interferon-ß in a TLR3 and TLR7-dependent manner. These results imply that recognition of resident viruses by TLR3 and TLR7 is required for protective immunity during gut inflammation.

Investigation of changes in DNA methylation associated with alterations in gene expression resulting in differences between lean and obese adipogenesis.

DNA methylation (DNAm) is an important epigenetic regulator controlling various cellular activities, including cell proliferation and differentiation. In the present work, we examined alterations in DNAm associated with obesity using methylome and transcriptome data from 27 purified adipocytes (ACs) and 7 preadipocytes (preACs) in human visceral adipose tissue (VAT) samples. We identified differentially methylated probes (DMPs) using two methods: (i) DMPs that were obtained from a comparison of the DNAm levels between AC and preAC samples (AGDMPs) and (ii) DMPs that were obtained from a comparison of the DNAm levels between obese and lean AC samples (ACDMPs). These two classes of DMPs were obtained to identify a relationship between adipogenesis and obesity. We also investigated how hyper and hypomethylation of the promoter and/or gene body differentially affected changes in gene expression by estimating the odds ratios (ORs) of changes in gene expression without DMPs in the background. Interestingly, the magnitude of DNAm alterations during AC differentiation was greater under lean conditions than under obese conditions. In conclusion, several adipogenesis-related genes were affected by complicated methylation changes and ultimately cause differences in gene expression in ACs under lean and obese conditions.

Transcriptomes of the tumor-adjacent normal tissues are more informative than tumors in predicting recurrence in colorectal cancer patients.

BACKGROUND: Previous investigations of transcriptomic signatures of cancer patient survival and post-therapy relapse have focused on tumor tissue. In contrast, here we show that in colorectal cancer (CRC) transcriptomes derived from normal tissues adjacent to tumors (NATs) are better predictors of relapse. RESULTS: Using the transcriptomes of paired tumor and NAT specimens from 80 Korean CRC patients retrospectively determined to be in recurrence or nonrecurrence states, we found that, when comparing recurrent with nonrecurrent samples, NATs exhibit a greater number of differentially expressed genes (DEGs) than tumors. Training two prognostic elastic net-based machine learning models-NAT-based and tumor-based in our Samsung Medical Center (SMC) cohort, we found that NAT-based model performed better in predicting the survival when the model was applied to the tumor-derived transcriptomes of an independent cohort of 450 COAD patients in TCGA. Furthermore, compositions of tumor-infiltrating immune cells in NATs were found to have better prognostic capability than in tumors. We also confirmed through Cox regression analysis that in both SMC-CRC as well as in TCGA-COAD cohorts, a greater proportion of genes exhibited significant hazard ratio when NAT-derived transcriptome was used compared to when tumor-derived transcriptome was used. CONCLUSIONS: Taken together, our results strongly suggest that NAT-derived transcriptomes and immune cell composition of CRC are better predictors of patient survival and tumor recurrence than the primary tumor.

GSK3 Restrains Germinal Center B Cells to Form Plasma Cells.

B cells in the germinal center (GC) are programmed to form plasma cells (PCs) or memory B cells according to signals received by receptors that are translated to carry out appropriate activities of transcription factors. However, the precise mechanism underlying this process to complete the GC reaction is unclear. In this study, we show that both genetic ablation and pharmacological inhibition of glycogen synthase kinase 3 (GSK3) in GC B cells of mice facilitate the cell fate decision toward PC formation, accompanied by acquisition of dark zone B cell properties. Mechanistically, under stimulation with CD40L and IL-21, GSK3 inactivation synergistically induced the transcription factors Foxo1 and c-Myc, leading to increased levels of key transcription factors required for PC differentiation, including IRF4. This GSK3-mediated alteration of transcriptional factors in turn facilitated the dark zone transition and consequent PC fate commitment. Our study thus reveals the upstream master regulator responsible for interpreting external cues in GC B cells to form PCs mediated by key transcription factors.

Investigation of the putative role of antisense transcripts as regulators of sense transcripts by correlation analysis of sense-antisense pairs in colorectal cancers.

Antisense transcription occurs widely more expected than when it was first identified in bacteria in the 1980s. However, the functional relevance of antisense transcripts in transcription remains controversial. Here, we investigated the putative role of antisense transcripts in regulating their corresponding sense transcripts by analyzing changes in correlative relationships between sense-antisense pairs under tumor and normal conditions. A total of 3469 sense-antisense gene pairs (SAGPs) downloaded from BioMart mapped to a list of sense and antisense genes in RNA-seq data derived from 80 paired colorectal cancer (CRC) samples were analyzed. As a result, cancer-related genes were significantly enriched in the significantly correlated SAGPs (SCPs). Differentially expressed genes estimated between normal and tumor conditions were also significantly more enriched in SCPs than in non-SCPs. Interestingly, using differential correlation analysis, we found that tumor samples had a significantly larger density of genes with higher correlation coefficients than normal samples, as verified by various cancer transcriptomes from The Cancer Genome Atlas (TCGA). Moreover, we found that the magnitude of the correlation between SAGPs could distinguish poor prognostic CRCs from good prognostic CRCs, showing that correlation coefficients between the SAGPs of CRCs with a poor prognosis were significantly stronger than CRCs with a good prognosis. Consistent with this finding, the Cox proportion hazards model showed that the survival rates were significantly different between patients with high and low expression of genes in the SCPs. All these results strongly support the idea that antisense transcripts are important regulators of their corresponding sense transcripts.

Analysis of changes in microbiome compositions related to the prognosis of colorectal cancer patients based on tissue-derived 16S rRNA sequences.

BACKGROUND: Comparing the microbiome compositions obtained under different physiological conditions has frequently been attempted in recent years to understand the functional influence of microbiomes in the occurrence of various human diseases. METHODS: In the present work, we analyzed 102 microbiome datasets containing tumor- and normal tissue-derived microbiomes obtained from a total of 51 Korean colorectal cancer (CRC) patients using 16S rRNA amplicon sequencing. Two types of comparisons were used: 'normal versus (vs.) tumor' comparison and 'recurrent vs. nonrecurrent' comparison, for which the prognosis of patients was retrospectively determined. RESULTS: As a result, we observed that in the 'normal vs. tumor' comparison, three phyla, Firmicutes, Actinobacteria, and Bacteroidetes, were more abundant in normal tissues, whereas some pathogenic bacteria, including Fusobacterium nucleatum and Bacteroides fragilis, were more abundant in tumor tissues. We also found that bacteria with metabolic pathways related to the production of bacterial motility proteins or bile acid secretion were more enriched in tumor tissues. In addition, the amount of these two pathogenic bacteria was positively correlated with the expression levels of host genes involved in the cell cycle and cell proliferation, confirming the association of microbiomes with tumorigenic pathway genes in the host. Surprisingly, in the 'recurrent vs. nonrecurrent' comparison, we observed that these two pathogenic bacteria were more abundant in the patients without recurrence than in the patients with recurrence. The same conclusion was drawn in the analysis of both normal and tumor-derived microbiomes. CONCLUSIONS: Taken together, it seems that understanding the composition of tissue microbiomes is useful for predicting the prognosis of CRC patients.

Putative positive role of inflammatory genes in fat deposition supported by altered gene expression in purified human adipocytes and preadipocytes from lean and obese adipose tissues.

BACKGROUND: Obesity is a chronic low-grade inflammatory disease that is generally characterized by enhanced inflammation in obese adipose tissue (AT). Here, we investigated alterations in gene expression between lean and obese conditions using mRNA-Seq data derived from human purified adipocytes (ACs) and preadipocytes (preACs). RESULTS: Total mRNA-seq data were generated with 27 AC and 21 preAC samples purified from human visceral AT collected during resection surgery in cancer patients, where the samples were classified into lean and obese categories by BMI > 25 kg/m2. We defined four classes of differentially expressed genes (DEGs) by comparing gene expression between (1) lean and obese ACs, (2) lean and obese preACs, (3) lean ACs and lean preACs, and 4) obese ACs and obese preACs. Based on an analysis of comparison 1, numerous canonical obesity-related genes, particularly inflammatory genes including IL-6, TNF-α and IL-1ß, i.e., the genes that are expected to be upregulated in obesity conditions, were found to be expressed at significantly lower levels in obese ACs than in lean ACs. In contrast, some inflammatory genes were found to be expressed at higher levels in obese preACs than lean preACs in the analysis of comparison 2. The analysis of comparisons 3 and 4 showed that inflammatory gene classes were expressed at higher levels in differentiated ACs than undifferentiated preACs under both lean and obese conditions; however, the degree of upregulation was significantly greater for lean than for obese conditions. We validated our observations using previously published microarray transcriptome data deposited in the GEO database (GSE80654). CONCLUSIONS: Taken together, our analyses suggest that inflammatory genes are expressed at lower levels in obese ACs than in lean ACs because lean adipogenesis involves even greater enhancement of inflammatory responses than does obese adipogenesis.

Staufen1-mediated mRNA decay functions in adipogenesis.

The double-stranded RNA binding protein Staufen1 (Stau1) is involved in diverse gene expression pathways. For Stau1-mediated mRNA decay (SMD) in mammals, Stau1 binds to the 3' untranslated region of target mRNA and recruits Upf1 to elicit rapid mRNA degradation. However, the events downstream of Upf1 recruitment and the biological importance of SMD remain unclear. Here we show that SMD involves PNRC2, decapping activity, and 5'-to-3' exonucleolytic activity. In particular, Upf1 serves as an adaptor protein for the association of PNRC2 and Stau1. During adipogenesis, Stau1 and PNRC2 increase in abundance, Upf1 becomes hyperphosphorylated, and consequently SMD efficiency is enhanced. Intriguingly, downregulation of SMD components attenuates adipogenesis in a way that is rescued by downregulation of an antiadipogenic factor, Krüppel-like factor 2 (KLF2), the mRNA of which is identified as a substrate of SMD. Our data thus identify a biological role for SMD in adipogenesis.

Soluble siglec-5 is a novel salivary biomarker for primary Sjogren's syndrome.

Despite advances in the understanding of the pathogenesis, disease-specific biomarkers have not been included in the classification criteria for Primary Sjogren's syndrome (pSS). Based on a microarray of peripheral blood mononuclear cells (PBMCs) from patients with primary Sjogren's syndrome (pSS), we aimed to investigate whether soluble sialic acid-binding immunoglobulin-like lectin (siglec)-5 in saliva might be a biomarker for pSS. The concentration of siglec-5 in saliva and sera was determined by ELISA. Clinical parameters related with pSS were obtained from pSS registry and correlation with salivary siglec-5 level was evaluated. Receiver operating curve (ROC) analysis was performed to determine cut off value. A separate validation cohort consisted of subjects with suspicious pSS was evaluated to determine the performance. The level of salivary siglec-5 was significantly higher in pSS patients (n = 170) compared with HCs (n = 25), non SS sicca patients (n = 78) or patients with systemic lupus erythematosus (SLE) (n = 43) (1346.8 [202.8-4280.0] pg/mL, 6.08 [0-134.0] pg/mL, 195 [0-947.5] pg/mL, and 0 [0-238.7] pg/mL, median [interquartile range], P < 0.001). Salivary siglec-5 level negatively correlated with salivary flow rate (spearman's rho: -0.420, P < 0.001), and positively correlated with ocular surface score (rho: 0.331, P < 0.001) and serum immunoglobulin G level (rho = 0.202, P = 0.008). In ROC analysis, area under the curve was 0.774[0.724-0.826]. With a cut off value of 400 pg/mL, sensitivity and specificity was 0.69 and 0.70 respectively. In validation cohort (45 pSS patients and 45 non SS sicca patients), sensitivity and specificity of siglec-5 was 64.4% and 77.8%, respectively. In conclusion, the level of soluble siglec-5 is significantly higher in the saliva from pSS patients, which reflects the severity of hyposalivation and ocular surface damage. This novel salivary biomarker may provide benefits for pSS diagnosis.

Functional relevance of synonymous alleles reflected in allele rareness in the population.

We provide theoretical evidence supporting the non-neutrality of synonymous alleles by investigating the rareness of synonymous alleles in the population. We find a significantly greater number of synonymous rare alleles than conventional neutral alleles derived from noncoding regions. A permutation experiment shows that the rareness of synonymous alleles is not a byproduct of random statistical noise. We then compare the frequencies of synonymous rare alleles and common alleles in various functional contexts in which synonymous alleles are known to be involved. Subsequently, we perform logistic regression analysis to elucidate the effect size of each independent factor contributing to the rareness of synonymous alleles. Additionally, we show that changes in optimality caused by synonymous mutations resulting in rare SNPs in the population tend to be biased toward optimality loss. We think that our study will contribute to the development of novel strategies for identifying functional synonymous mutations.

Methylome analysis reveals alterations in DNA methylation in the regulatory regions of left ventricle development genes in human dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is one of the main causes of heart failure (called cardiomyopathies) in adults. Alterations in epigenetic regulation (i.e., DNA methylation) have been implicated in the development of DCM. Here, we identified a total of 1828 differentially methylated probes (DMPs) using the Infinium 450K HumanMethylation Bead chip by comparing the methylomes between 18 left ventricles and 9 right ventricles. Alterations in DNA methylation levels were observed mainly in lowly methylated regions corresponding to promoter-proximal regions, which become hypermethylated in severely affected left ventricles. Subsequent mRNA microarray analysis showed that the effect of DNA methylation on gene expression regulation is not unidirectional but is controlled by the functional sub-network context. DMPs were significantly enriched in the transcription factor binding sites (TFBSs) we tested. Alterations in DNA methylation were specifically enriched in the cis-regulatory regions of cardiac development genes, the majority of which are involved in ventricular development (e.g., TBX5 and HAND1).

Transcription factor Sp1 prevents TRF2(ΔBΔM)-induced premature senescence in human diploid fibroblasts.

Telomere uncapping is thought to be the fundamental cause of replicative cellular senescence, but the cellular machineries mediating this process have not been fully understood. In the present study, we present the role of Sp1 transcription factor in the state of telomere uncapping using the TRF2(ΔBΔM)-induced senescence model in human diploid fibroblasts. We observed that the expression of Sp1 is down-regulated in the TRF2(ΔBΔM)-induced senescence, which was mediated by ATM and p38 MAPK. In addition, overexpression of Sp1 prevented the TRF2(ΔBΔM)-induced senescence. Among transcriptional targets of Sp1, expression levels of nuclear transport genes such as karyopherin α, Nup107, and Nup50 were down-regulated in the TRF2(ΔBΔM)-induced senescence, which was prevented by Sp1 overexpression. Moreover, inhibition of the nuclear transport by wheat germ agglutinin (an import inhibitor) and leptomycin B (an export inhibitor) induced premature senescence. These results suggest that Sp1 is an anti-senescence transcription factor in the telomere uncapping-induced senescence and that down-regulation of Sp1 leads to the senescence via down-regulation of the nuclear transport.

High-fat diet-induced obesity increases lymphangiogenesis and lymph node metastasis in the B16F10 melanoma allograft model: roles of adipocytes and M2-macrophages.

To examine the effects of high-fat diet (HFD) on melanoma progression, HFD-fed C57BL/6N mice were subcutaneously injected with syngeneic B16F10 melanoma cells. At 3 weeks post-injection, the tumors were resected; the mice were then sacrificed at 2 weeks post-resection. HFD stimulated melanoma growth and lymph node (LN) metastasis as well as tumor and LN lymphangiogenesis. Lipid vacuoles in the tumor and M2-macrophage (MΦ)s in the adipose and tumor tissues were increased in HFD-fed mice. CCL19 and CCL21 contents were higher in LNs than in tumors. HFD increased both CCL19 and CCL21 levels in LNs and CCR7 in tumors. Adipose tissue-conditioned media (CM) from HFD-fed mice enhanced lymphangiogenesis, and mature adipocyte (MA)/M2-MΦ co-culture CM markedly stimulated the tube formation of lymphatic endothelial cell (LEC)s and B16F10 migration. Monocyte migration was moderately stimulated by B16F10 or MA CM, but tremendously stimulated by B16F10/M2-MΦ co-culture CM, which was enhanced by MA/B16F10/M2-MΦ co-culture CM. The co-culture results revealed that MAs increased CCL2, M-CSF and CCR7 mRNAs in B16F10s; vascular endothelial growth factor (VEGF)-D mRNA in M2-MΦs; and CCL19, CCL21 and VEGF receptor (VEGFR)3 mRNA in LECs. M2-MΦs increased CCL2, M-CSF and VEGF-A mRNAs in B16F10s, whereas B16F10s increased VEGF-C mRNAs in M2-MΦs and VEGFR3 mRNA in LECs. These results indicate that in HFD-fed mice, MA-induced CCL2 and M-CSF in tumor cells increase M2-MΦs in tumor; the crosstalk between tumor cells and M2-MΦs further increases cytokines and angiogenic and lymphangiogenic factors. Additionally, MA-stimulated CCL19, CCL21/CCR7 axis contributes to increased LN metastasis in HFD-fed mice.

SMG5-PNRC2 is functionally dominant compared with SMG5-SMG7 in mammalian nonsense-mediated mRNA decay.

In mammals, nonsense-mediated mRNA decay (NMD) functions in post-transcriptional gene regulation as well as mRNA surveillance. A key NMD factor, Upf1, becomes hyperphosphorylated by SMG1 kinase during the recognition of NMD substrates. Hyperphosphorylated Upf1 interacts with several factors including SMG5, SMG6, SMG7 and PNRC2 to trigger rapid mRNA degradation. However, the possible cross-talk among these factors and their selective use during NMD remain unknown. Here, we show that PNRC2 is preferentially complexed with SMG5, but not with SMG6 or SMG7, and that downregulation of PNRC2 abolishes the interaction between SMG5 and Dcp1a, a component of the decapping complex. In addition, tethering experiments reveal the function of Upf1, SMG5 and PNRC2 at the same step of NMD and the requirement of SMG6 for Upf1 for efficient mRNA degradation. Intriguingly, microarray results reveal the significant overlap of SMG5-dependent NMD substrates more with PNRC2-dependent NMD substrates than with SMG7-dependent NMD substrates, suggesting the functional dominance of SMG5-PNRC2, rather than SMG5-SMG7, under normal conditions. The results provide evidence that, to some extent, endogenous NMD substrates have their own binding preference for Upf1-interacting adaptors or effectors.

Conservation in first introns is positively associated with the number of exons within genes and the presence of regulatory epigenetic signals.

BACKGROUND: Genomes of higher eukaryotes have surprisingly long first introns and in some cases, the first introns have been shown to have higher conservation relative to other introns. However, the functional relevance of conserved regions in the first introns is poorly understood. Leveraging the recent ENCODE data, here we assess potential regulatory roles of conserved regions in the first intron of human genes. RESULTS: We first show that relative to other downstream introns, the first introns are enriched for blocks of highly conserved sequences. We also found that the first introns are enriched for several chromatin marks indicative of active regulatory regions and this enrichment of regulatory marks is correlated with enrichment of conserved blocks in the first intron; the enrichments of conservation and regulatory marks in first intron are not entirely explained by a general, albeit variable, bias for certain marks toward the 5' end of introns. Interestingly, conservation as well as proportions of active regulatory chromatin marks in the first intron of a gene correlates positively with the numbers of exons in the gene but the correlation is significantly weakened in second introns and negligible beyond the second intron. The first intron conservation is also positively correlated with the gene's expression level in several human tissues. Finally, a gene-wise analysis shows significant enrichments of active chromatin marks in conserved regions of first introns, relative to the conserved regions in other introns of the same gene. CONCLUSIONS: Taken together, our analyses strongly suggest that first introns are enriched for active transcriptional regulatory signals under purifying selection.

Robust signals of coevolution of interacting residues in mammalian proteomes identified by phylogeny-aided structural analysis.

The structure of a protein depends critically on the complex interactions among its amino acid residues. It has long been hypothesized that interacting residues might tend to coevolve, but it is not known whether such coevolution is a general phenomenon across the proteome. Here, we describe a novel methodology called phylogeny-aided structural analysis, which uncovers robust signals of interacting-residue coevolution in mammalian proteomes. Furthermore, this new method allows the magnitude of coevolution to be quantified. Finally, it facilitates a comprehensive evaluation of various factors that affect interacting-residue coevolution, such as the physicochemical properties of the interactions between residues, solvent accessibility of the residues and their secondary structure context.

Interleukin-1 promotes coagulation, which is necessary for protective immunity in the lung against Streptococcus pneumoniae infection.

Interleukin (IL)-1 is a well-known cytokine for the initiation of innate immunity in bacterial infection. However, the underlying mechanism of IL-1 on the respiratory infection is not fully elucidated. We studied how IL-1 contributes to the host defense against Streptococcus pneumoniae. IL-1R(-/-) mice showed high mortality, local cytokine storm, and substantial infiltrates in the lower respiratory tract after intratracheal challenge with S. pneumoniae. The IL-1-deficient condition did not suppress the propagation of bacteria in the lung, although the recruitment and the bacteria-killing ability of neutrophils (CD11b(+)Ly6C(+)Ly6G(+)) were not defective compared with wild-type mice. Unexpectedly, we found that the transcription of fibrinogen alpha and gamma genes were highly activated in the lungs of wild-type mice after the infection, whereas no significant changes were found in IL-1R(-/-) mice. Of note, synthesis of fibrinogen was dependent on the IL-1-IL-6-Stat3 cascade. Treatment with recombinant fibrinogen improved survival and bacterial propagation in the IL-1R(-/-) mice and blockade of the coagulation increased the susceptibility of wild-type mice to pneumococcal pneumonia. Our findings suggest that IL-1 signaling leads to the synthesis of fibrinogen in the lung after pneumococcus infection and is followed by coagulation, which contributes to the control of bacterial infection in the pulmonary tract.

Gut microbiome-derived butyrate inhibits the immunosuppressive factors PD-L1 and IL-10 in tumor-associated macrophages in gastric cancer.

Early detection and surgical treatment are essential to achieve a good outcome in gastric cancer (GC). Stage IV and recurrent GC have a poor prognosis. Therefore, new treatments for GC are needed. We investigated the intestinal microbiome of GC patients and attempted to reverse the immunosuppression of the immune and cancer cells of GC patients through the modulation of microbiome metabolites. We evaluated the levels of programmed death-ligand 1 (PD-L1) and interleukin (IL)-10 in the peripheral blood immunocytes of GC patients. Cancer tissues were obtained from patients who underwent surgical resection of GC, and stained sections of cancer tissues were visualized via confocal microscopy. The intestinal microbiome was analyzed using stool samples of healthy individuals and GC patients. Patient-derived avatar model was developed by injecting peripheral blood mononuclear cells (PBMCs) from advanced GC (AGC) patients into NSG mice, followed by injection of AGS cells. PD-L1 and IL-10 had higher expression levels in immune cells of GC patients than in those of healthy controls. The levels of immunosuppressive factors were increased in the immune and tumor cells of tumor tissues of GC patients. The abundances of Faecalibacterium and Bifidobacterium in the intestinal flora were lower in GC patients than in healthy individuals. Butyrate, a representative microbiome metabolite, suppressed the expression levels of PD-L1 and IL-10 in immune cells. In addition, the PBMCs of AGC patients showed increased levels of immunosuppressive factors in the avatar mouse model. Butyrate inhibited tumor growth in mice. Restoration of the intestinal microbiome and its metabolic functions inhibit tumor growth and reverse the immunosuppression due to increased PD-L1 and IL-10 levels in PBMCs and tumor cells of GC patients.

IL-7-primed bystander CD8 tumor-infiltrating lymphocytes optimize the antitumor efficacy of T cell engager immunotherapy.

Bispecific T cell engagers (TCEs) show promising clinical efficacy in blood tumors, but their application to solid tumors remains challenging. Here, we show that Fc-fused IL-7 (rhIL-7-hyFc) changes the intratumoral CD8 T cell landscape, enhancing the efficacy of TCE immunotherapy. rhIL-7-hyFc induces a dramatic increase in CD8 tumor-infiltrating lymphocytes (TILs) in various solid tumors, but the majority of these cells are PD-1-negative tumor non-responsive bystander T cells. However, they are non-exhausted and central memory-phenotype CD8 T cells with high T cell receptor (TCR)-recall capacity that can be triggered by tumor antigen-specific TCEs to acquire tumoricidal activity. Single-cell transcriptome analysis reveals that rhIL-7-hyFc-induced bystander CD8 TILs transform into cycling transitional T cells by TCE redirection with decreased memory markers and increased cytotoxic molecules. Notably, TCE treatment has no major effect on tumor-reactive CD8 TILs. Our results suggest that rhIL-7-hyFc treatment promotes the antitumor efficacy of TCE immunotherapy by increasing TCE-sensitive bystander CD8 TILs in solid tumors.