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Yong-Jun Liu

Publications and source records attributed to Yong-Jun Liu.

At least 37 records · Page 2Linked to original sources

Thymic stromal lymphopoietin in normal and pathogenic T cell development and function.

Thymic stromal lymphopoietin, a four helix-bundle cytokine, is expressed mainly by barrier epithelial cells and is a potent activator of several cell types, particularly myeloid dendritic cells. TSLP influences the outcome of interactions between dendritic cells and CD4+ thymocytes and T cells in many situations, such as the regulation of the positive selection of regulatory T cells, maintenance of peripheral CD4+ T cell homeostasis and induction of CD4+ T cell-mediated allergic inflammation.

Animals↗

Molecular genetic studies of gene identification for osteoporosis: a 2004 update.

This review summarizes comprehensively the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of December 2004. It is intended to constitute a sequential update of our previously published review covering the available data up to the end of 2002. Evidence from candidate gene association studies and genome-wide linkage studies in humans, as well as quantitative trait locus mapping animal models are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. An important extension of this update is incorporation of functional genomic studies (including DNA microarrays and proteomics) on osteogenesis and osteoporosis, in light of the rapid advances and the promising prospects of the field. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.

Animals↗

Genomic regions identified for BMD in a large sample including epistatic interactions and gender-specific effects.

UNLABELLED: A genome-wide linkage scan was conducted using a large white sample to identify QTLs for BMD. We found QTLs in the total sample and the gender-specific subgroups, as well as significant epistatic interactions underlying BMD variations. INTRODUCTION: Low BMD is an important risk factor for osteoporosis and under strong genetic control. MATERIALS AND METHODS: To identify quantitative trait loci (QTLs) for regulation of BMD, we performed a large-scale whole genome linkage scan (WGS) involving 4126 individuals from 451 families. In addition to the conventional linkage analyses in the total combined sample of males and females, we conducted epistatic interaction analyses and gender-specific linkage analyses. RESULTS: Significant linkage was detected on 5q23 for wrist BMD (LOD = 3.39) and 15q13 for female spine BMD (LOD = 4.49). For spine BMD, we revealed significant epistatic interactions between 3p25 and 2q32 (p = 0.0022) and between 3p25 and 11q23 (p = 0.0007). We replicated several genomic regions that showed linkage with BMD in previous studies by others and ours, such as 3p21, 1p36, and Xq27. CONCLUSIONS: This study highlights the importance of large sample size, incorporation of epistatic interaction, and consideration of gender-specific effects in identifying QTLs for BMD variation. The results of this study provide a foundation for the future fine mapping and gene identification in our population.

Bone Density↗

Robust and comprehensive analysis of 20 osteoporosis candidate genes by very high-density single-nucleotide polymorphism screen among 405 white nuclear families identified significant association and gene-gene interaction.

UNLABELLED: Many "novel" osteoporosis candidate genes have been proposed in recent years. To advance our knowledge of their roles in osteoporosis, we screened 20 such genes using a set of high-density SNPs in a large family-based study. Our efforts led to the prioritization of those osteoporosis genes and the detection of gene-gene interactions. INTRODUCTION: We performed large-scale family-based association analyses of 20 novel osteoporosis candidate genes using 277 single nucleotide polymorphisms (SNPs) for the quantitative trait BMD variation and the qualitative trait osteoporosis (OP) at three clinically important skeletal sites: spine, hip, and ultradistal radius (UD). MATERIALS AND METHODS: One thousand eight hundred seventy-three subjects from 405 white nuclear families were genotyped and analyzed with an average density of one SNP per 4 kb across the 20 genes. We conducted association analyses by SNP- and haplotype-based family-based association test (FBAT) and performed gene-gene interaction analyses using multianalytic approaches such as multifactor-dimensionality reduction (MDR) and conditional logistic regression. RESULTS AND CONCLUSIONS: We detected four genes (DBP, LRP5, CYP17, and RANK) that showed highly suggestive associations (10,000-permutation derived empirical global p < or = 0.01) with spine BMD/OP; four genes (CYP19, RANK, RANKL, and CYP17) highly suggestive for hip BMD/OP; and four genes (CYP19, BMP2, RANK, and TNFR2) highly suggestive for UD BMD/OP. The associations between BMP2 with UD BMD and those between RANK with OP at the spine, hip, and UD also met the experiment-wide stringent criterion (empirical global p < or = 0.0007). Sex-stratified analyses further showed that some of the significant associations in the total sample were driven by either male or female subjects. In addition, we identified and validated a two-locus gene-gene interaction model involving GCR and ESR2, for which prior biological evidence exists. Our results suggested the prioritization of osteoporosis candidate genes from among the many proposed in recent years and revealed the significant gene-gene interaction effects influencing osteoporosis risk.

Adult↗

[Hemangiopoiet in modulates adhesive properties of endothelial cells].

OBJECTIVE: To explore the effect of hemangiopoietin (HAPO) on the adhesive properties of human umbilical vein endothelial cells (HUVEC). METHODS: The adhesion of HUVEC and the expressions of CD54, CD102, CD106, CD31, CD62E, and CD62P were measured by adhesion assay, flow cytometry, and semi-quantitative RT-PCR. RESULTS: HAPO enhanced the total adherence of HUVEC in a concentration-dependent manner. Flow cytometry analysis revealed that the treatment of HAPO resulted in a significantly increased expression of CD106 and CD62E on HUVEC in a time-dependent manner. When HUVEC were incubated with HAPO for 6 h, the percentage of CD106 + HUVEC and CD62E HUVEC increased about 2.10 folds and 5.84 folds, respectively, compared with control. The time-course of adhesive molecules mRNA expression indicated that the expression of CD106 and CD62E reached at the maximum 1.86 folds and 6.16 folds, respectively, compared with control. CONCLUSION: HAPO may facilitate the homing of hematopoietic stem/progenitor cells.

Cell Adhesion Molecules↗

[Expression of recombinant human hemangiopoietin and preparation of its polyclonal antibody].

AIM: To express the recombinant fusion protein of hemangiopoietin (HAPO) and prepare the rabbit-anti-human HAPO polyclonal antibody. METHODS: The sequence encoding HAPO was amplified by PCR and cloned into plasmid pET32c to construct recombinant prokaryotic expression system. The recombinant expression vectors were identified by enzyme digestion analysis and transformed into E. coli. The HAPO protein was purified by affinity chromatography. Rabbits were immunized with the HAPO protein, and the immune sera of rabbits were collected. Antibodies (IgG) obtained from the immune sera were purified. RESULTS: The purified HAPO protein was successfully obtained. The purified polyclonal antibody of rabbit-anti-human HAPO was also obtained from the immune sera of rabbits, and could response to human HAPO. CONCLUSION: A prokaryotic expression system of human HAPO has been prepared and the polyclonal antibody against HAPO has been prepared, which can be used to determine HAPO protein.

Animals↗

Plasmacytoid dendritic cells of different origins have distinct characteristics and function: studies of lymphoid progenitors versus myeloid progenitors.

Plasmacytoid dendritic cells (pDCs) play a central role in host innate and adaptive immunity and are thought to be of lymphoid origin. However, in IL-7Ralpha-/- mice, which are deficient in T and B lymphocytes, pDCs are still found in lymphoid organs, which suggests that there is a lymphoid-independent pathway for the development of pDCs. Previous work has demonstrated that pDCs originate from both lymphoid and myeloid progenitors (MPs). However, it is not clear whether the function of pDCs is different relative to their origin. In an effort to compare the characteristics and functions between pDCs generated from different progenitors, we performed adoptive transfer studies using highly enriched populations of common lymphoid progenitors (CLPs) and MPs from the bone marrow of control mice and examined their potential and developmental kinetics for the generation of pDCs. Interestingly, although CLPs were polarized to generate pDCs, MPs were polarized to generate conventional dendritic cells and the kinetics of pDC generation from MPs was reached earlier than from CLPs. Furthermore, CLPs have the potential to generate more pDCs on a per cell basis. Moreover, MP-derived pDCs produce relatively higher levels of IFN-alpha than CLP-derived pDCs following CpG stimulation. These data indicate that MPs are multipotential and have the capacity to develop into not only myeloid cells, but also pDCs, which have distinct characteristics and function compared to that of lymphoid origin and, therefore, imply a more important role for MP-derived pDCs in conditions where the function of lymphoid progenitors is impaired or compromised.

Adoptive Transfer↗

Specialization, kinetics, and repertoire of type 1 interferon responses by human plasmacytoid predendritic cells.

Recent studies suggest plasmacytoid predendritic cells (pDCs) and myeloid dendritic cells (mDCs) have the functional plasticity to produce similar amounts of type 1 interferons (IFNs) and interleukin-12 (IL-12), challenging the concept and existence of DC subsets with distinct function. In this study, we demonstrate that previous studies showed human pDCs produce large amounts of IL-12 because of contaminating mDCs. Using highly purified human DC subsets, we found that although pDCs make 300 times more IFN-alpha than mDCs and mDCs make 13 times more IL-12 p70 than pDCs in response to all the toll-like receptor ligands and CD40 ligands, pDCs rapidly make large amounts of IFN-alpha within the first 12 hours of activation and become refractory to further stimulation. pDCs preferentially expressed the transcriptional factors critical for type 1 IFN, but not for IL-12 transcription, and they dedicated 60% of new transcriptional activity to make 19 type 1 IFN subtypes. This study provides formal proof that the plasticity of DC subsets is limited and that different DC subsets evolve to perform distinct functions in linking innate and adaptive immunity.

CD40 Ligand↗

Expression and significance of CD44s, CD44v6, and nm23 mRNA in human cancer.

AIM: To investigate the relationship between the expression levels of nm23 mRNA, CD44s, and CD44v6, and oncogenesis, development and metastasis of human gastric adenocarcinoma, colorectal adenocarcinoma, intraductal carcinoma of breast, and lung cancer. METHODS: Using tissue microarray by immuhistochemical (IHC) staining and in situ hybridization (ISH), we examined the expression levels of nm23 mRNA, CD44s, and CD44v6 in 62 specimens of human gastric adenocarcinoma and 62 specimens of colorectal adenocarcinoma; the expression of CD44s and CD44v6 in 120 specimens of intraductal carcinoma of breast and 20 specimens of normal breast tissue; the expression of nm23 mRNA in 72 specimens of human lung cancer and 23 specimens of normal tissue adjacent to cancer. RESULTS: The expression of nm23 mRNA in the tissues of gastric and colorectal adenocarcinoma was not significantly different from that in the normal tissues adjacent to cancer (P>0.05), and was not associated with the invasion of tumor and the pathology grade of adenocarcinoma (P>0.05). However, the expression of nm23 mRNA was correlated negatively to the lymph node metastasis of gastric and colorectal adenocarcinoma (r = -0.49, P<0.01; r = -4.93, P<0.01). The expression of CD44s in the tissues of gastric and colorectal adenocarcinoma was significantly different from that in the normal tissues adjacent to cancer (P<0.05; P<0.01). CD44v6 was expressed in the tissues of gastric and colorectal adenocarcinoma only, the expression of CD44v6 was significantly associated with the lymph node metastasis, invasion and pathological grade of the tumor (r = 0.47, P<0.01; r = 5.04, P<0.01). CD44s and CD44v6 were expressed in intraductal carcinoma of breast, the expression of CD44s and CD44v6 was significantly associated with lymph node metastases and invasion (P<0.01). However, neither of them was expressed in the normal breast tissue. In addition, the expression of CD44v6 was closely related to the degree of cell differentiation of intraductal carcinoma of breast (c2 = 5.68, P<0.05). The expressional level of nm23 mRNA was closely related to the degree of cell differentiation (P<0.05) and lymph node metastasis (P<0.01), but the expression of nm23 gene was not related to sex, age, and type of histological classification (P>0.05). CONCLUSION: Patients with overexpression of CD44s and CD44v6 and low expression of nm23 mRNA have a higher lymph node metastatic rate and invasion. In addition, overexpression of CD44v6 is closely related to the degree of cell differentiation. Detection of the three genes is able to provide a reliable index to evaluate the invasion and metastasis of tumor cells.

Antigens, Neoplasm↗

TSLP-activated dendritic cells induce an inflammatory T helper type 2 cell response through OX40 ligand.

We recently showed that dendritic cells (DCs) activated by thymic stromal lymphopoietin (TSLP) prime naive CD4(+) T cells to differentiate into T helper type 2 (Th2) cells that produced high amounts of tumor necrosis factor-alpha (TNF-alpha), but no interleukin (IL)-10. Here we report that TSLP induced human DCs to express OX40 ligand (OX40L) but not IL-12. TSLP-induced OX40L on DCs was required for triggering naive CD4(+) T cells to produce IL-4, -5, and -13. We further revealed the following three novel functional properties of OX40L: (a) OX40L selectively promoted TNF-alpha, but inhibited IL-10 production in developing Th2 cells; (b) OX40L lost the ability to polarize Th2 cells in the presence of IL-12; and (c) OX40L exacerbated IL-12-induced Th1 cell inflammation by promoting TNF-alpha, while inhibiting IL-10. We conclude that OX40L on TSLP-activated DCs triggers Th2 cell polarization in the absence of IL-12, and propose that OX40L can switch IL-10-producing regulatory Th cell responses into TNF-alpha-producing inflammatory Th cell responses.

Adult↗

Hassall's corpuscles instruct dendritic cells to induce CD4+CD25+ regulatory T cells in human thymus.

Hassall's corpuscles-first described in the human thymus over 150 years ago-are groups of epithelial cells within the thymic medulla. The physical nature of these structures differs between mammalian species. Although Hassall's corpuscles have been proposed to act in both the removal of apoptotic thymocytes and the maturation of developing thymocytes within the thymus, the function of Hassall's corpuscles has remained an enigma. Here we report that human Hassall's corpuscles express thymic stromal lymphopoietin (TSLP). Human TSLP activates thymic CD11c-positive dendritic cells to express high levels of CD80 and CD86. These TSLP-conditioned dendritic cells are then able to induce the proliferation and differentiation of CD4(+)CD8(-)CD25(-) thymic T cells into CD4(+)CD25(+)FOXP3(+) (forkhead box P3) regulatory T cells. This induction depends on peptide-major histocompatibility complex class II interactions, and the presence of CD80 and CD86, as well as interleukin 2. Immunohistochemistry studies reveal that CD25(+)CTLA4(+) (cytotoxic T-lymphocyte-associated protein 4) regulatory T cells associate in the thymic medulla with activated or mature dendritic cells and TSLP-expressing Hassall's corpuscles. These findings suggest that Hassall's corpuscles have a critical role in dendritic-cell-mediated secondary positive selection of medium-to-high affinity self-reactive T cells, leading to the generation of CD4(+)CD25(+) regulatory T cells within the thymus.

Adult↗

Virus overrides the propensity of human CD40L-activated plasmacytoid dendritic cells to produce Th2 mediators through synergistic induction of IFN-{gamma} and Th1 chemokine production.

Depending on the activation status, plasmacytoid dendritic cells (PDC) and myeloid DC have the ability to induce CD4 T cell development toward T helper cell type 1 (Th1) or Th2 pathways. Thus, we tested whether different activation signals could also have an impact on the profile of chemokines produced by human PDC. Signals that induce human PDC to promote a type 1 response (i.e., viruses) and a type 2 response [i.e., CD40 ligand (CD40L)] also induced PDC isolated from tonsils to secrete chemokines preferentially attracting Th1 cells [such as interferon-gamma (IFN-gamma)-inducible protein (IP)-10/CXC chemokine ligand 10 (CXCL10) and macrophage inflammatory protein-1beta/CC chemokine ligand 4 (CCL4)] or Th2 cells (such as thymus and activation-regulated chemokine/CCL17 and monocyte-derived chemokine/CCL22), respectively. Activated natural killer cells were preferentially recruited by supernatants of virus-activated PDC, and supernatants of CD40L-activated PDC attracted memory CD4(+) T cells, particularly the CD4(+)CD45RO(+)CD25(+) T cells described for their regulatory activities. It is striking that CD40L and virus synergized to trigger the production of IFN-gamma by PDC, which induces another Th1-attracting chemokine monokine-induced by IFN-gamma/CXCL9 and cooperates with endogenous type I IFN for IP-10/CXCL10 production. In conclusion, our studies reveal that PDC participate in the selective recruitment of effector cells of innate and adaptive immune responses and that virus converts the CD40L-induced Th2 chemokine patterns of PDC into a potent Th1 mediator profile through an autocrine loop of IFN-gamma.

Autocrine Communication↗

Mapping quantitative trait loci for cross-sectional geometry at the femoral neck.

UNLABELLED: A genome-wide linkage scan was performed in a sample of 79 multiplex pedigrees to identify genomic regions linked to femoral neck cross-sectional geometry. Potential quantitative trait loci were detected at several genomic regions, such as 10q26, 20p12-q12, and chromosome X. INTRODUCTION: Bone geometry is an important determinant of bone strength and osteoporotic fractures. Previous studies have shown that femoral neck cross-sectional geometric variables are under genetic controls. To identify genetic loci underlying variation in femoral neck cross-sectional geometry, we conducted a whole genome linkage scan for four femoral neck cross-sectional geometric variables in 79 multiplex white pedigrees. MATERIALS AND METHODS: A total of 1816 subjects from 79 pedigrees were genotyped with 451 microsatellite markers across the human genome. We performed linkage analyses on the entire data, as well as on men and women separately. RESULTS: Significant linkage evidence was identified at 10q26 for buckling ratio (LOD = 3.27) and Xp11 (LOD = 3.45) for cortical thickness. Chromosome region 20p12-q12 showed suggestive linkage with cross-sectional area (LOD = 2.33), cortical thickness (LOD = 2.09), and buckling ratio (LOD = 1.94). Sex-specific linkage analyses further supported the importance of 20p12-q12 for cortical thickness (LOD = 2.74 in females and LOD = 1.88 in males) and buckling ratio (LOD = 5.00 in females and LOD = 3.18 in males). CONCLUSIONS: This study is the first genome-wide linkage scan searching for quantitative trait loci underlying femoral neck cross-sectional geometry in humans. The identification of the genes responsible for bone geometric variation will improve our knowledge of bone strength and aid in development of diagnostic approaches and interventions for osteoporotic fractures.

Absorptiometry, Photon↗

Plasmacytoid predendritic cells initiate psoriasis through interferon-alpha production.

Psoriasis is one of the most common T cell-mediated autoimmune diseases in humans. Although a role for the innate immune system in driving the autoimmune T cell cascade has been proposed, its nature remains elusive. We show that plasmacytoid predendritic cells (PDCs), the natural interferon (IFN)-alpha-producing cells, infiltrate the skin of psoriatic patients and become activated to produce IFN-alpha early during disease formation. In a xenograft model of human psoriasis, we demonstrate that blocking IFN-alpha signaling or inhibiting the ability of PDCs to produce IFN-alpha prevented the T cell-dependent development of psoriasis. Furthermore, IFN-alpha reconstitution experiments demonstrated that PDC-derived IFN-alpha is essential to drive the development of psoriasis in vivo. These findings uncover a novel innate immune pathway for triggering a common human autoimmune disease and suggest that PDCs and PDC-derived IFN-alpha represent potential early targets for the treatment of psoriasis.

Animals↗

Linkage exclusion analysis of two candidate regions on chromosomes 7 and 11: leptin and UCP2/UCP3 are not QTLs for obesity in US Caucasians.

Leptin (LEP) and the uncoupling proteins 2 and 3 (UCP2/UCP3) are key molecules involved in the regulation of food intake and energy expenditure. However, their contribution to variation of obesity phenotypes in the general population remains controversial. The present study is to investigate whether chromosomal regions 7q and 11q, which contain LEP and UCP2/UCP3, respectively, can be excluded for linkage with obesity phenotypes. The obesity phenotypes include body mass index (BMI), fat mass, and percentage fat mass (PFM), with the latter two measured by dual-energy X-ray absorptiometry. We conducted exclusion linkage analyses using a variance component approach in a sample of 1816 individuals coming from 79 extended Caucasian pedigrees. In this study, we were able to exclude chromosomal region 7q containing LEP as having an effect on fat mass and PFM at effect sizes of 5% or greater, and on BMI at effect sizes of 10% or greater. We were able to exclude chromosomal region 11q containing UCP2/UCP3 as having an effect on fat mass and PFM at effect sizes of 10% or greater, and on BMI at effect sizes of 5% or greater. Our results suggest that the LEP and UCP2/UCP3 genes are unlikely to have a substantial effect on variation in obesity phenotypes in this particular US Caucasian population.

Carrier Proteins↗

TLR activation triggers the rapid differentiation of monocytes into macrophages and dendritic cells.

Leprosy enables investigation of mechanisms by which the innate immune system contributes to host defense against infection, because in one form, the disease progresses, and in the other, the infection is limited. We report that Toll-like receptor (TLR) activation of human monocytes induces rapid differentiation into two distinct subsets: DC-SIGN+ CD16+ macrophages and CD1b+ DC-SIGN- dendritic cells. DC-SIGN+ phagocytic macrophages were expanded by TLR-mediated upregulation of interleukin (IL)-15 and IL-15 receptor. CD1b+ dendritic cells were expanded by TLR-mediated upregulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) and its receptor, promoted T cell activation and secreted proinflammatory cytokines. Whereas DC-SIGN+ macrophages were detected in lesions and after TLR activation in all leprosy patients, CD1b+ dendritic cells were not detected in lesions or after TLR activation of peripheral monocytes in individuals with the progressive lepromatous form, except during reversal reactions in which bacilli were cleared by T helper type 1 (TH1) responses. In tuberculoid lepromatous lesions, DC-SIGN+ cells were positive for macrophage markers, but negative for dendritic cell markers. Thus, TLR-induced differentiation of monocytes into either macrophages or dendritic cells seems to crucially influence effective host defenses in human infectious disease.

Antigens, CD1↗

Linkage and association analyses of the UCP3 gene with obesity phenotypes in Caucasian families.

Uncoupling protein 3 (UCP3) uncouples ATP production from mitochondrial respiration, thereby dissipating energy as heat and affecting the efficiency of energy metabolism. Genetic variations in the UCP3 gene have been conceived to affect body weight in the general population. In this study, using the quantitative transmission disequilibrium test (QTDT), we assessed linkage and association between the UCP3 gene and obesity phenotypes in a large sample of 1,873 subjects from 405 United States Caucasian nuclear families. Obesity phenotypes tested include body mass index (BMI), fat mass, percent fat mass (PFM), and lean mass, with the latter three measured by dual-energy X-ray absorptiometry. We first selected five single nucleotide polymorphisms (SNPs) and then analyzed three highly polymorphic ones, namely, -55 C/T (promoter), Tyr99Tyr (exon 3), and Tyr210Tyr (exon 5), in the total sample. Significant linkage disequilibria (0.392 <or= D' <or= 0.940, P < 0.0001) were observed between pairs of SNPs. In single-locus analyses, we found statistically significant association (P = 0.034) and linkage (P = 0.031) between -55 C/T and BMI. This polymorphism explains 2.29% of BMI variation, and subjects carrying the T allele had an average of 3.5% lower BMI than those without it (P = 0.003). In haplotype analyses, we also observed evidence of linkage (P = 0.002) and association (P = 0.035) with BMI. In summary, our results suggest that UCP3 gene polymorphisms may contribute to BMI variation in this Caucasian population.

Alleles↗

CD4- plasmacytoid dendritic cells (pDCs) migrate in lymph nodes by CpG inoculation and represent a potent functional subset of pDCs.

We have recently identified two groups of plasmacytoid dendritic cells (pDCs) isolated from murine liver based on the expression of CD4 and other cell surface markers uniquely expressed by pDCs. Herein, we describe the identification of both CD4+ and CD4- pDCs that clearly exist in lymph nodes (LNs), spleen, liver, thymus, bone marrow, and lung. Normally, CD4+ pDCs are enriched in LNs. However, after in vivo systemic injection with bacterial CpG, a larger number of CD4- pDCs are recruited to the LNs and local inoculation by CpG drives CD4- pDCs migrating into local sentinel LNs, suggesting that CD4- pDCs are the main subpopulation migrating to the peripheral LNs. Furthermore, although both freshly isolated CD4+ pDCs and CD4- pDCs appear as an immature plasmacytoid cell and develop into a DC morphology following activation, the two subsets have strikingly different immune features, including differences in the production pattern of cytokines stimulated with CpG and in T cell activation.

Animals↗