High-dimensional immune profiling using mass cytometry reveals IL-17A-producing γδ T cells as biomarkers in patients with T-cell-activated idiopathic severe aplastic anemia.

Severe aplastic anemia (SAA) is a bone marrow failure syndrome characterized by activated T cells. Features of T-cell activation in the pathophysiology of SAA remain unknown. To understand T cell activation states, we investigated the atlas of peripheral immune cells and the secreted cytokine network with single cell mass cytometry analysis. We found decreased γδ T-cell frequencies in all patients with SAA, together with a significantly increased proportion of interleukin (IL)-17A-producing cell subsets. Cytokine network analysis of immune cells showed significant positive relationship between IL and 17A production from immune cells and disease severity of severe aplastic anemia. On separating SAA into two distinct subgroups based on T-cell activation stage, the proportion of γδ T cells tended to decrease in the T-cell-activated SAA group compared with non-T-cell-activated group. And the proportion of IL-17A-producing γδ T cells (γδT17) within γδ T cells was newly found to be significantly higher in the T-cell-activated SAA group, implying that IL-17A production by γδ T cells was associated with T-cell activation. Overall, our study revealed a role of γδT17 cells in mediating autoreactive T-cell activation in SAA and provided a novel diagnostic indicator for monitoring autoreactive T-cell activation status during the progression of aplastic anemia in the clinic.

Lost genome segments associate with trait diversity during rice domestication.

BACKGROUND: DNA mutations of diverse types provide the raw material required for phenotypic variation and evolution. In the case of crop species, previous research aimed to elucidate the changing patterns of repetitive sequences, single-nucleotide polymorphisms (SNPs), and small InDels during domestication to explain morphological evolution and adaptation to different environments. Additionally, structural variations (SVs) encompassing larger stretches of DNA are more likely to alter gene expression levels leading to phenotypic variation affecting plant phenotypes and stress resistance. Previous studies on SVs in rice were hampered by reliance on short-read sequencing limiting the quantity and quality of SV identification, while SV data are currently only available for cultivated rice, with wild rice largely uncharacterized. Here, we generated two genome assemblies for O. rufipogon using long-read sequencing and provide insights on the evolutionary pattern and effect of SVs on morphological traits during rice domestication. RESULTS: In this study, we identified 318,589 SVs in cultivated and wild rice populations through a comprehensive analysis of 13 high-quality rice genomes and found that wild rice genomes contain 49% of unique SVs and an average of 1.76% of genes were lost during rice domestication. These SVs were further genotyped for 649 rice accessions, their evolutionary pattern during rice domestication and potential association with the diversity of important agronomic traits were examined. Genome-wide association studies between these SVs and nine agronomic traits identified 413 candidate causal variants, which together affect 361 genes. An 824-bp deletion in japonica rice, which encodes a serine carboxypeptidase family protein, is shown to be associated with grain length. CONCLUSIONS: We provide relatively accurate and complete SV datasets for cultivated and wild rice accessions, especially in TE-rich regions, by comparing long-read sequencing data for 13 representative varieties. The integrated rice SV map and the identified candidate genes and variants represent valuable resources for future genomic research and breeding in rice.

Hard versus soft selective sweeps during domestication and improvement in soybean.

Genome scans for selection can provide an efficient way to dissect the genetic basis of domestication traits and understand mechanisms of adaptation during crop evolution. Selection involving soft sweeps (simultaneous selection for multiple alleles) is probably common in plant genomes but is under-studied, and few if any studies have systematically scanned for soft sweeps in the context of crop domestication. Using genome resequencing data from 302 wild and domesticated soybean accessions, we conducted selection scans using five widely employed statistics to identify selection candidates under classical (hard) and soft sweeps. Across the genome, inferred hard sweeps are predominant in domesticated soybean landraces and improved varieties, whereas soft sweeps are more prevalent in a representative subpopulation of the wild ancestor. Six domestication-related genes, representing both hard and soft sweeps and different stages of domestication, were used as positive controls to assess the detectability of domestication-associated sweeps. Performance of various test statistics suggests that differentiation-based (FST ) methods are robust for detecting complete hard sweeps, and that LD-based strategies perform well for identifying recent/ongoing sweeps; however, none of the test statistics detected a known soft sweep we previously documented at the domestication gene Dt1. Genome scans yielded a set of 66 candidate loci that were identified by both differentiation-based and LD-based (iHH) methods; notably, this shared set overlaps with many previously identified QTLs for soybean domestication/improvement traits. Collectively, our results will help to advance genetic characterizations of soybean domestication traits and shed light on selection modes involved in adaptation in domesticated plant species.

CXCR4 is a Novel Biomarker Correlated With Malignant Transformation and Immune Infiltrates in Gastric Precancerous Lesions.

Background: As early gastric cancer (EGC) has a far better prognosis than advanced gastric cancer (GC), early diagnosis and treatment are essential. However, understanding the mechanism of the process from gastric precancerous lesion (GPL) becoming EGC has made little advances. Besides, biomarkers that can monitor the progression of GPL-to-GC are still much insufficient. Methods: Key gene modules associated with GPL progression to EGC were identified by integrating two GPL-related data sets, GSE55696 and GSE130823, using the WGCNA method. Combining with the TCGA-STAD cohort, hub genes were identified. Immunofluorescence was conducted to validate the expression. To explore the implication of hub genes in GPL malignant transformation, a correlation test was conducted to identify their co-expression genes, co-expression cytokines, and co-expression immune cells. Least absolute shrinkage and selection operator (LASSO) Cox regression was applied to shrink CXCR4-related predictors and construct a prognostic model. Functional enrichment was applied for exploring the potential mechanism. Results: The green module in GSE55696 and the yellow module in GSE130823 were regarded as key gene modules associated with GPL progression to EGC, and 219 intersection genes from them were mainly enriched in critical immune biological processes. Combining with the TCGA-STAD cohort, CXCR4 was identified as a novel biomarker correlated with the malignant transformation of GPL, the positive rate of which was increased with GPL progression according to immunofluorescence. CXCR4 co-expression genes were found mainly involved in regulation of actin. CXCR4 co-expression cytokines were enriched in regulation of chemotaxis, cell chemotaxis, mononuclear cell migration, leukocyte chemotaxis, etc. As for co-expression immune cells, the expression level of CXCR4 was positively correlated with the abundance of macrophages but negatively correlated with that of effector memory T cells and NKT cells during GPL malignant transformation. In addition, the CXCR4-related prognostic model was able to predict the prognosis of GC and serve as an independent predictor for overall survival (OS). Conclusions: CXCR4 was a novel biomarker correlated with malignant transformation of GPL and played a vital role in the control of tumor immunity. CXCR4 is possible to serve as a therapeutic target for malignant transformation of GPL.

Prognostic role of DFNA5 in head and neck squamous cell carcinoma revealed by systematic expression analysis.

BACKGROUND: The gasdermin E gene (GSDME, also known as DFNA5) is mutated in familial aging-related hearing loss. Recent studies have also revealed that the expression of DFNA5 is suppressed in many cancer types; however, little is known about the function of DFNA5 in head and neck squamous cell carcinoma (HNSCC). Accordingly, the aim of the present study was to evaluate the expression of DFNA5 and explore its prognostic value in HNSCC. RESULT: We used a set of bioinformatics tools, including Oncomine, TIMER, TISIDB, cBioPortal, and GEPIA, to analyze the expression of DFNA5 in patients with HNSCC from public databases. Kaplan-Meier plotter was used to evaluate the potential prognostic significance of DFNA5. DFNA5 mRNA levels were significantly higher in HNSCC tissues than in normal tissues, and high DFNA5 expression was correlated with worse survival. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that DFNA5 expression has a strong positive correlation with cell adhesion and the integrin signaling pathway, whereas its expression was negatively correlated with the levels of infiltrating B cells (cor = - 0.223, P = 8.57e-07) and CD8 T cells (cor = - 0.223, P = 2.99e-07). CONCLUSION: This study demonstrates that DFNA5 expression has prognostic value for HNSCC patients. Moreover, these results suggest that regulation of lymphocyte infiltration is the mechanism underlying the function of DFNA5 in HNSCC.

Identification of LINC00665-miR-let-7b-CCNA2 competing endogenous RNA network associated with prognosis of lung adenocarcinoma.

Prognosis of patients with lung cancer remains extremely poor; thus, we sought to unearth novel competing endogenous RNA (ceRNA) networks associated with the prognosis of lung adenocarcinoma (LUAD). Aberrant mRNAs were identified from the intersection of three Gene Expression Omnibus (GEO) datasets. A protein-protein interaction (PPI) network was constructed, and miRNAs and long noncoding RNAs (lncRNAs) upstream of mRNAs were predicted. In the present study, 402 upregulated and 638 downregulated genes in lung cancer tissues were identified. Functional analysis showed significant enrichment of cancer pathways. In these top hub genes, 10 upregulated and 7 downregulated genes had substantial prognostic values in LUAD. Thirty-seven miRNAs were predicted to target 17 key genes, and only five miRNAs exhibited prognostic correlation. Through stepwise reverse prediction and validation from miRNA to lncRNA, four key lncRNAs were identified using expression and survival analysis. Ultimately, the co-expression analysis identified LINC00665-miR-let-7b-CCNA2 as the key ceRNA network associated with the prognosis of LUAD. We successfully constructed a novel ceRNA network wherein each component was significantly associated with the prognosis of LUAD. Hence, we propose that this network may provide key biomarkers or potential therapeutic targets for LUAD prognosis.

Bromodomain 4 is a potent prognostic marker associated with immune cell infiltration in breast cancer.

Bromodomain 4 (BRD4), a member of the bromodomain and extra-terminal domain protein family, has become a promising epigenetic target in cancer and inflammatory diseases; however, the detailed biological role of BRD4 in breast cancer (BRCA) remains undetermined. We analysed the BRD4 expression levels using the Oncomine and TIMER databases and evaluated the clinical impact of BRD4 on BRCA prognosis using Kaplan-Meier plot and PrognoScan. The correlation between BRD4 and tumour-infiltrating immune cells was investigated using TIMER. Furthermore, the correlation between BRD4 expression levels was also analysed using TIMER in addition to the GEPIA database for immune cell gene markers. BRD4 expression was significantly higher in BRCA tissues than in normal tissues, which was significantly correlated with poor overall survival (OS). Specifically, high BRD4 expression was correlated with worse OS and progression-free survival in patients with BRCA. In addition, BRD4 expression was correlated with levels of infiltrating monocytes (CSF1R, cor = 0.204, P = 9.19e-12), tumour-associated macrophages (CD68, cor = 0.129, P = 1.81e-05), M1/M2 macrophages and different effector T cells (including Th1/Th2/Treg) in BRCA. These findings suggest that BRD4 could be used as a prognostic biomarker for determining prognosis and immune cell infiltration levels in BRCA.

Expansion of Polymorphonuclear Myeloid-Derived Suppressor Cells in Patients With Gout.

Gout is an inflammatory joint disease caused by monosodium urate (MSU) crystals; however, the mechanism underlying MSU-induced inflammation is unclear. Previous research has suggested that inflammation or cancer can drive the expansion of myeloid-derived suppressor cells (MDSCs). In this study, the role of MDSCs in MSU-induced gout inflammation was evaluated. A total of 28 patients with gout, and 20 healthy controls were recruited for the study. MDSCs, and their functions, were analyzed by flow cytometry and a T cell co-culture assay, respectively. We observed a higher frequency of PMN-MDSCs, and a stronger immunosuppressive function, in patients with gout compared to the controls. Moreover, circulating PMN-MDSCs were positively correlated with pathological indicators, including uric acid and C-reactive protein levels. We also demonstrated that MSU can induce significant PMN-MDSC expansion, using in vivo and in vitro experiments. Finally, MSU-induced PMN-MDSCs produced higher levels of IL-1ß, which mediated gout inflammatory progression. Our results demonstrate that MSU modulates the expansion and suppressive function of PMN-MDSCs, providing insights into a novel mechanism underlying the pathogenesis of MSU-induced gout. Thus, MDSCs may be useful for the development of novel therapeutic strategies for the prevention and treatment of gout.

Construction of an 11-microRNA-based signature and a prognostic nomogram to predict the overall survival of head and neck squamous cell carcinoma patients.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is a fatal malignancy owing to the lack of effective tools to predict overall survival (OS). MicroRNAs (miRNAs) play an important role in HNSCC occurrence, development, invasion and metastasis, significantly affecting the OS of patients. Thus, the construction of miRNA-based risk signatures and nomograms is desirable to predict the OS of patients with HNSCC. Accordingly, in the present study, miRNA sequencing data of 71 HNSCC and 13 normal samples downloaded from The Cancer Genome Atlas (TCGA) were screened to identify differentially expressed miRNAs (DEMs) between HNSCC patients and normal controls. Based on the exclusion criteria, the clinical information and miRNA sequencing data of 67 HNSCC samples were selected and used to establish a miRNA-based signature and a prognostic nomogram. Forty-three HNSCC samples were assigned to an internal validation cohort for verifying the credibility and accuracy of the primary cohort. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to explore the functions of 11 miRNA target genes. RESULTS: In total, 11 DEMs were successfully identified. An 11-miRNA risk signature and a prognostic nomogram were constructed based on the expression levels of these 11 DEMs and clinical information. The signature and nomogram were further validated by calculating the C-index, area under the curve (AUC) in receiver-operating characteristic curve analysis, and calibration curves, which revealed their promising performance. The results of the internal validation cohort shown the reliable predictive accuracy both of the miRNA-based signature and the prognostic nomogram. GO and KEGG analyses revealed that a mass of signal pathways participated in HNSCC proliferation and metastasis. CONCLUSION: Overall, we constructed an 11-miRNA-based signature and a prognostic nomogram with excellent accuracy for predicting the OS of patients with HNSCC.

Prognostic value of S1PR1 and its correlation with immune infiltrates in breast and lung cancers.

BACKGROUND: Sphingosine-1-phosphate receptor (S1PR1) is involved in vascular development, a key process in tumorigenesis. This study aimed to evaluate its roles in tumor development and prognosis. METHODS: S1PR1 expression levels were analyzed using TIMER and Oncomine database, and the prognostic significance of S1PR1 was assessed using PrognoScan and Kaplan-Meier plotter databases. The relationship between S1PR1 and tumor-infiltrated immune cells was analyzed using TIMER. RESULTS: S1PR1 expression was remarkably lower in breast and lung cancer tissues than in the corresponding normal tissues. Lower expression was related to poor overall survival and disease-free survival in breast invasive carcinoma (BRCA), lung adenocarcinoma (LUAD), and lung squamous cell carcinoma (LUSC). A functional network analysis confirmed the function of S1PR1 in regulating vasculogenesis. In addition, S1PR1 levels were significantly negative with regard to the tumor purity of BRCA (r = - 0.508, P = 1.76e-66), LUAD (r = - 0.353, P = 6.05e-16), and LUSC (r = - 0.402, P = - 5.20e-20). Furthermore, S1PR1 levels were significantly positive with regard to infiltrating CD8+ (r = 0.38, P = 5.91e-35) and CD4+ T cells (r = 0.335, P = 1.03e-26), macrophages (r = 0.219, P = 3.67e-12), neutrophils (r = 0.168, P = 2.03e-7), and dendritic cells (DCs) (r = 0.208, P = 9.14e-11) in BRCA; S1PR1 levels were significantly positive with regard to CD8+ T cells (r = 0.308, P = 3.61e-12), macrophages (r = 0.376, P = 1.01e-17), neutrophils (r = 0.246, P = 4.15e-8), and DCs (r = 0.207, P = 4.16e-6) in LUAD; and positive with regard to B cells (r = 0.356, P = 1.57e-15), CD8+ (r = 0.459, P = 3.83e-26) and CD4+ T cells (r = 0.338, P = 3.98e-14), macrophages (r = 0.566, P = 2.61e-45), neutrophils (r = 0.453, P = 1.79e-25), and DCs (r = 0.56, P = 2.12e-40) in LUSC. CONCLUSIONS: S1PR1 levels are positively correlated with multiple immune markers in breast and lung cancer. These observed correlations between S1PR1 and the prognosis and immune cell infiltration provide a foundation for further research on its immunomodulatory role in cancer.

Expansion of PMN-myeloid derived suppressor cells and their clinical relevance in patients with oral squamous cell carcinoma.

OBJECTIVES: Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy worldwide, with a high mortality. The prognosis of OSCC remains unsatisfactory; the dysregulated immune system plays an important role in the pathogenesis of OSCC. Myeloid-derived suppressor cells (MDSCs) have been identified as immune-suppressive cells in multiple tumor types. The aim of this study was to clarify the underlying immunoregulatory mechanism of MDSC in patients with OSCC. MATERIALS AND METHODS: Flow cytometry was used to analyze the phenotype of MDSC among peripheral blood mononuclear cells (PBMCs) from patients with OSCC and healthy control subjects. The correlation between MDSC frequency and the disease index of patients with OSCC was evaluated. T cell proliferation experiment was used to evaluate the immunosuppressive function of MDSC. RESULTS: Patients with OSCC exhibited significantly higher levels of PMN-MDSCs than did healthy controls. In the co-culture assay, T cell proliferation and IFN-γ production were abrogated by the addition of PMN-MDSCs in a dose-dependent manner. The levels of reactive oxygen species were higher for PMN-MDSCs derived from patients with OSCC than for those from normal individuals. p-STAT3 levels, a key activator of MDSCs, was higher in OSCC-related PMN-MDSCs than in those from healthy controls. Both of these effects were reversed by NAC (an ROS inhibitor) and JSI-124 (a p-STAT3 inhibitor). Finally, PMN-MDSC levels were positively related to histological differentiation, nodal metastasis, and recurrence. CONCLUSION: PMN-MDSCs were elevated in OSCC patients, with strong immune-suppressive effects via p-STAT3/reactive oxygen species, providing a new direction for therapeutic strategies.

Expansion and activation of monocytic-myeloid-derived suppressor cell via STAT3/arginase-I signaling in patients with ankylosing spondylitis.

BACKGROUND: Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease. The dysregulated immune system plays an important role in the pathogenesis of AS. Myeloid-derived suppressor cells (MDSCs) play a key immunoregulatory role in autoimmune arthritis. The aim of this study was to clarify the underlying immunoregulatory mechanism of MDSCs in patients with AS. METHODS: Flow cytometry was used to analyze the phenotype of MDSCs among peripheral blood mononuclear cells (PBMCs) from 46 patients with AS and 46 healthy control subjects. The correlation between MDSC frequency and the disease index of patients with AS was evaluated. A T cell proliferation experiment was used to evaluate the immunosuppressive function of MDSCs. RESULTS: Polymorphonuclear (PMN) and monocytic (M)-MDSCs were significantly elevated in the PBMCs of patients with AS, when compared with levels in healthy controls. Additionally, M-MDSC levels correlated positively with the clinical index of AS, including the Bath ankylosing spondylitis disease activity index (BASDAI) score, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels. M-MDSCs derived from patients with AS suppressed T cell responses, and this effect was dependent on the induction of arginase-I. Furthermore, AS-derived M-MDSCs showed high levels of phosphorylated STAT3. Stattic, a STAT3-specific inhibitor, and STAT3-targeted siRNA abrogated the immunosuppressive function of M-MDSCs. Inhibition of STAT3 signaling also resulted in decreased arginase-I activity. CONCLUSIONS: STAT3/arginase-I signaling plays an important role in both the expansion and activation of M-MDSCs in patients with AS. This information may be beneficial in developing novel therapeutic strategies for preventing AS.

Signatures of soft sweeps across the Dt1 locus underlying determinate growth habit in soya bean [Glycine max (L.) Merr.].

Determinate growth habit is an agronomically important trait associated with domestication in soya bean. Previous studies have demonstrated that the emergence of determinacy is correlated with artificial selection on four nonsynonymous mutations in the Dt1 gene. To better understand the signatures of the soft sweeps across the Dt1 locus and track the origins of the determinate alleles, we examined patterns of nucleotide variation in Dt1 and the surrounding genomic region of approximately 800 kb. Four local, asymmetrical hard sweeps on four determinate alleles, sized approximately 660, 120, 220 and 150 kb, were identified, which constitute the soft sweeps for the adaptation. These variable-sized sweeps substantially reflected the strength and timing of selection and indicated that the selection on the alleles had been completed rapidly within half a century. Statistics of EHH, iHS, H12 and H2/H1 based on haplotype data had the power to detect the soft sweeps, revealing distinct signatures of extensive long-range LD and haplotype homozygosity, and multiple frequent adaptive haplotypes. A haplotype network constructed for Dt1 and a phylogenetic tree based on its extended haplotype block implied independent sources of the adaptive alleles through de novo mutations or rare standing variation in quick succession during the selective phase, strongly supporting multiple origins of the determinacy. We propose that the adaptation of soya bean determinacy is guided by a model of soft sweeps and that this model might be indispensable during crop domestication or evolution.

Identification of an HIV-1 replication inhibitor which rescues host restriction factor APOBEC3G in Vif-APOBEC3G complex.

HIV-1 Vif protein is one of the most crucial accessory proteins for viral replication. It efficiently counteracts the important host restriction factor APOBEC3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G, A3G) which is lethal to HIV-1 by causing G to A mutation of viral genome. Vif protein mediates degradation of APOBEC3G via the complicated protein-protein interactions of Vif, APOBEC3G, Elongin C/B and Cullin 5. The importance of Vif-APOBEC3G complex makes it a good potential target to develop new therapeutics of HIV-1. We identified a potent HIV-1 replication inhibitor (ZBMA-1, IC50 = 1.01 µM) that efficiently protected APOBEC3G protein by targeting Vif-APOBEC3G complex. The co-immunoprecipitation and docking studies indicated that compound ZBMA-1 affected the binding of Elongin C with Vif protein.

Cross talk between histone deacetylase 4 and STAT6 in the transcriptional regulation of arginase 1 during mouse dendritic cell differentiation.

l-Arginine and l-arginine-metabolizing enzymes play important roles in the biology of some types of myeloid cells, including macrophage and myeloid-derived suppressor cells. In this study, we found evidence that arginase 1 (Arg1) is required for the differentiation of mouse dendritic cells (DCs). Expression of Arg1 was robustly induced during monocyte-derived DC differentiation. Ectopic expression of Arg1 significantly promoted monocytic DC differentiation in a granulocyte-macrophage colony-stimulating factor culture system and also facilitated the differentiation of CD8α(+) conventional DCs in the presence of Flt3 ligand. Knockdown of Arg1 reversed these effects. Mechanistic studies showed that the induced expression of Arg1 in differentiating DCs was caused by enhanced recruitment of histone deacetylase 4 (HDAC4) to the Arg1 promoter region, which led to a reduction in the acetylation of both the histone 3 and STAT6 proteins and subsequent transcriptional activation of Arg1. Further investigation identified a novel STAT6 binding site within the Arg1 promoter that mediated its regulation by STAT6 and HDAC4. These observations suggest that the cross talk between HDAC4 and STAT6 is an important regulatory mechanism of Arg1 transcription in DCs. Moreover, overexpression of Arg1 clearly abrogated the ability of HDAC inhibitors to suppress DC differentiation. In conclusion, we show that Arg1 is a novel regulator of myeloid DC differentiation.

MicroRNA-196b promotes cell proliferation and suppress cell differentiation in vitro.

MicroRNA-196b (miR-196b) is frequently amplified and aberrantly overexpressed in acute leukemias. To investigate the role of miR-196b in acute leukemias, it has been observed that forced expression of this miRNA increases proliferation and inhibits apoptosis in human cell lines. More importantly, we show that this miRNA can significantly increase the colony-forming capacity of mouse normal bone marrow progenitor cells alone, as well as partially blocking the cells from differentiation. Taken together, our studies suggest that miRNA-196b may play an essential role in the development of MLL-associated leukemias through inhibiting cell differentiation and apoptosis, while promoting cell proliferation.

Ribavirin enhances myeloid-derived suppressor cell differentiation through CXCL9/10 downregulation.

Elevation of myeloid-derived suppressor cells (MDSCs) was observed in some viral infectious diseases. In this study, we studied whether ribavirin, a widely used clinical antiviral drug, could impact the differentiation of human MDSCs in vitro. Flow cytometric analysis showed that ribavirin treatment (5-20 µg/ml) significantly enhanced the differentiation of monocytic MDSCs in a dose-dependent manner. The ribavirin-generated MDSCs were immune-suppressive toward autologous T cells. The mRNA expression of some cytokines was further examined by quantitative reverse transcription polymerase chain reaction. We observed a significant down-regulation of chemokine (C-X-C motif) ligand 9 (CXCL9) and CXCL10 mRNA in ribavirin-generated MDSCs, when compared with control. Peripheral blood mononuclear cells from clinical chronic hepatitis C patients subjected to ribavirin therapy also displayed a similar suppression in CXCL9/10 mRNA expression. Administration of recombinant CXCL9/10 proteins clearly counteracted the effect of ribavirin on MDSCs. In summary, this study showed that ribavirin enhanced human MDSCs differentiation in vitro, which may be attribute to the down-regulation of CXCL9/10 expression.

Liver X receptor regulates mouse GM-CSF-derived dendritic cell differentiation in vitro.

Liver X receptors (LXRs) are nuclear receptors that play an essential role in lipid and cholesterol metabolism. Emerging studies indicate a potential function for LXRs in regulating dendritic cell (DC)-dependent immune responses; however, the role of LXRs in DC differentiation is largely unknown. Here, we report that LXRα regulates the differentiation of mouse GM-CSF-derived DCs. Activation or overexpression of LXRα significantly enhanced myeloid DC differentiation from mouse bone marrow (BM) cells, while siRNA-mediated knockdown of LXRα suppressed DC differentiation. In addition, we demonstrated that LXR agonist-programmed DCs showed an increased capacity for stimulating T-cell proliferation. Mechanistic studies showed that activation of LXR could inhibit the phosphorylation of STAT3 and downregulate the expression of its target, S100A9, an important negative regulator of myeloid DC differentiation. We also found that Histone deacetylase (HDAC) inhibition interfered with the effect of LXR on STAT3 signaling via acetylation of STAT3. Chromatin immunoprecipitation assays confirmed that LXR activation and HDAC inhibition balanced the recruitment of STAT3 to the S100A9 promoter, which involved distinct post-translational modifications of STAT3. In conclusion, our observations demonstrated a novel role for LXRα in GM-CSF-derived DC differentiation and revealed the underlying mechanism.