A genome-wide association study identified PTPN2 as a population-specific susceptibility gene locus for primary biliary cholangitis

BACKGROUND AIMS

Previous genome-wide association studies (GWAS) have indicated the involvement of shared (population-non-specific) and non-shared (population-specific) susceptibility genes in the pathogenesis of primary biliary cholangitis (PBC) among European and East-Asian populations. Although a meta-analysis of these distinct populations has recently identified more than 20 novel PBC susceptibility loci, analyses of population-specific genetic architecture are still needed for a more comprehensive search for genetic factors in PBC.

APPROACH RESULTS

Protein tyrosine phosphatase non-receptor type 2 (PTPN2) was identified as a novel PBC susceptibility gene locus through a GWAS and subsequent genome-wide meta-analysis involving 2,181 cases and 2,699 controls from the Japanese population (GWAS-lead variant: rs8098858, p=2.6×10-8). In-silico and in-vitro functional analyses indicated that the risk allele of rs2292758, which is a primary functional variant, decreases PTPN2 expression by disrupting Sp1 binding to the PTPN2 promoter in T follicular helper cells (Tfh) and plasmacytoid dendritic cells (pDCs). Infiltration of PTPN2-positive T-cells and pDCs were confirmed in the portal area of the PBC-liver by immunohistochemistry. Furthermore, transcriptomic analysis of PBC-liver samples indicated the presence of a compromised negative feedback loop in-vivo between PTPN2 and IFNG in patients carrying the risk allele of rs2292758.

CONCLUSIONS

PTPN2, a novel susceptibility gene for PBC in the Japanese population, may be involved in the pathogenesis of PBC via an insufficient negative feedback loop caused by the PTPN2 risk allele of rs2292758 in IFN signaling. This suggests that PTPN2 could be a potential molecular target for PBC treatment.

rs10924104 in the expression enhancer motif of CD58 confers susceptibility to human autoimmune diseases

CD58 plays roles in cell adhesion and co-stimulation with antigen presentation from major histocompatibility complex class II on antigen-presenting cells to T-cell antigen receptors on naïve T cells. CD58 reportedly contributes to the development of various human autoimmune diseases. Recently, genome-wide association studies (GWASs) identified CD58 as a susceptibility locus for autoimmune diseases such as systemic lupus erythematosus (SLE), multiple sclerosis (MS), and primary biliary cholangitis (PBC). However, the primary functional variant and molecular mechanisms of susceptibility to autoimmune diseases in the CD58 locus were not clarified. Here, rs10924104, located in the ZNF35-binding motif within the gene expression regulatory motif, was identified as the primary functional variant for SLE, MS, and PBC among genetic variants showing stronger linkage disequilibrium (LD) with GWAS-lead variants in the CD58 locus. Expression-quantitative trait locus (e-QTL) data for each distinct blood cell type and in vitro functional analysis using the CRISPR/Cas9 system corroborated the functional role of rs10924104 in the upregulation of CD58 transcription by the disease-risk allele. Additionally, the strength of disease susceptibility observed in the CD58 locus could be accounted for by the strength of LD between rs10924104 and each GWAS-lead variant. In conclusion, the present study demonstrated for the first time the existence of a shared autoimmune disease-related primary functional variant (i.e., rs10924104) that regulates the expression of CD58. Clarifying the molecular mechanism of disease susceptibility derived from such a shared genetic background is important for understanding human autoimmune diseases and human immunology.

Novel HLA allele associations with susceptibility, staging, symptomatic state, autoimmune hepatitis and hepatocellular carcinoma events for primary biliary cholangitis in the Japanese population

Primary biliary cholangitis (PBC) is a rare autoimmune disease with a clear predisposition for human leukocyte antigen (HLA)-DR/DQ-associated loss of immune tolerance for the E2 component of the pyruvate dehydrogenase complex. Three-field-resolution HLA imputation of 1,670 Japanese PBC patients and 2,328 healthy controls was conducted using Japanese population-specific HLA reference panels. Eighteen previously reported Japanese PBC-associated HLA alleles were confirmed and extended to 3-field-resolution, including HLA-DRB1*08:03 to HLA-DRB1*08:03:02, HLA-DQB1*03:01 to HLA-DQB1*03:01:01, HLA-DQB1*04:01 to HLA-DQB1*04:01:01 and HLA-DQB1*06:04 to HLA-DQB1*06:04:01. In addition, additional significant novel HLA alleles were identified, including 3 novel susceptible HLA-DQA1 alleles: HLA-DQA1*03:03:01, HLA-DQA1*04:01:01, HLA-DQA1*01:04:01 and 1 novel protective HLA-DQA1 allele, HLA-DQA1*05:05:01. In addition, PBC patients carrying HLA-DRB1*15:01:01 and HLA-DQA1*03:03:01 would have a higher predisposition toward developing concomitant autoimmune hepatitis (AIH). Further, late-stage and symptomatic PBC shared the same susceptible HLA alleles of HLA-A*26:01:01, HLA-DRB1*09:01:02 and HLA-DQB1*03:03:02. Lastly, HLA-DPB1*05:01:01 was identified as a potential risk HLA allele for development of hepatocellular carcinoma (HCC) in PBC patients. In conclusion, we have extended the current knowledge of HLA allele associations to 3-field resolution and identified novel HLA allele associations with predisposition risk, staging, symptomatic state, and AIH and HCC events for Japanese PBC patients.

An international genome-wide meta-analysis of primary biliary cholangitis: Novel risk loci and candidate drugs

BACKGROUNDS & AIMS

Primary biliary cholangitis (PBC) is a chronic liver disease in which autoimmune destruction of the small intrahepatic bile ducts eventually leads to cirrhosis. Many patients have inadequate response to licensed medications, motivating the search for novel therapies. Previous genome-wide association studies (GWAS) and meta-analyses (GWMA) of PBC have identified numerous risk loci for this condition, providing insight into its aetiology. We undertook the largest GWMA of PBC to date, aiming to identify additional risk loci and prioritise candidate genes for in silico drug efficacy screening.

METHODS

We combined new and existing genotype data for 10,516 cases and 20,772 controls from 5 European and 2 East Asian cohorts.

RESULTS

We identified 56 genome-wide significant loci (20 novel) including 46 in European, 13 in Asian, and 41 in combined cohorts; and a 57th genome-wide significant locus (also novel) in conditional analysis of the European cohorts. Candidate genes at newly identified loci include FCRL3, INAVA, PRDM1, IRF7, CCR6, CD226, and IL12RB1, which each play key roles in immunity. Pathway analysis reiterated the likely importance of pattern recognition receptor and TNF signalling, JAK-STAT signalling, and differentiation of T helper (TH)1 and TH17 cells in the pathogenesis of this disease. Drug efficacy screening identified several medications predicted to be therapeutic in PBC, some of which are well-established in the treatment of other autoimmune disorders.

CONCLUSIONS

This study has identified additional risk loci for PBC, provided a hierarchy of agents that could be trialled in this condition, and emphasised the value of genetic and genomic approaches to drug discovery in complex disorders.

LAY SUMMARY

Primary biliary cholangitis (PBC) is a chronic liver disease that eventually leads to cirrhosis. In this study, we analysed genetic information from 10,516 people with PBC and 20,772 healthy individuals recruited in Canada, China, Italy, Japan, the UK, or the USA. We identified several genetic regions associated with PBC. Each of these regions contains several genes. For each region, we used diverse sources of evidence to help us choose the gene most likely to be involved in causing PBC. We used these 'candidate genes' to help us identify medications that are currently used for treatment of other conditions, which might also be useful for treatment of PBC.

rs1944919 on chromosome 11q23.1 and its effector genes COLCA1/COLCA2 confer susceptibility to primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic, progressive cholestatic liver disease in which intrahepatic bile ducts are destroyed by an autoimmune reaction. Our previous genome-wide association study (GWAS) identified chromosome 11q23.1 as a susceptibility gene locus for PBC in the Japanese population. Here, high-density association mapping based on single nucleotide polymorphism (SNP) imputation and in silico/in vitro functional analyses identified rs1944919 as the primary functional variant. Expression-quantitative trait loci analyses showed that the PBC susceptibility allele of rs1944919 was significantly associated with increased COLCA1/COLCA2 expression levels. Additionally, the effects of rs1944919 on COLCA1/COLCA2 expression levels were confirmed using genotype knock-in versions of cell lines constructed using the CRISPR/Cas9 system and differed between rs1944919-G/G clones and -T/T clones. To our knowledge, this is the first study to demonstrate the contribution of COLCA1/COLCA2 to PBC susceptibility.

Association of soluble T cell immunoglobulin domain and mucin-3 (sTIM-3) and mac-2 binding protein glycosylation isomer (M2BPGi) in patients with autoimmune hepatitis

Background

Autoimmune hepatitis (AIH) is a disorder of unknown etiology in which immune-mediated liver injury progress to cirrhosis or hepatocellular carcinoma (HCC). The aim of the present study was to determine whether circulating soluble TIM3 (sTIM3) is elevated in patients with AIH patients and whether sTIM-3 levels are associated with clinical parameters of AIH.

Methods

We enrolled 123 Japanese patients with AIH who were identified from the National Hospital Organization–AIH-liver–network database, as well as 32 patients with chronic hepatitis C (CHC), 30 patients with primary biliary cholangitis (PBC) and healthy control subjects. Serum sTIM-3 concentrations were quantified by ELISA.

Results

Serum levels of sTIM-3 were significantly higher in AIH patients (median 4865 pg/ml; [interquartile range (IQR); 3122–7471]) compared to those in CHC (1026 pg/ml [IQR: 806–1283] p<0.001), PBC (2395 pg/ml [IQR: 2012–3422] p<0.001) or healthy controls (1285 pg/ml [IQR: 1098–1812] p<0.001). In AIH group, serum sTIM-3 were correlated with alanine aminotransferase (ALT), or total bilirubin (TB) and negatively correlated with serum levels of albumin (Alb). Serum levels of sTIM-3 were also strongly correlated with Mac-2 binding protein glycosylation isomer (M2BPGi) levels, but did not correlate with the histological grade of liver fibrosis. Steroid treatment of AIH patients significantly reduced serum sTIM-3 levels (2147±623pg/ml versus 1321±378pg/ml, p<0.001).

Conclusions

Circulating sTIM-3 levels were elevated in AIH patients and are associated with AIH disease activity and AIH-related liver damage. These findings indicate that serum sTIM-3 correlated with disease status of AIH and could be useful biomarkers to detect autoimmune-mediated liver injury. Our data suggest a possible link between the TIM-3/GAL-9 pathway and AIH severity or phenotype, and further investigations of the TIM-3 pathway and AIH pathophysiology is warranted.

Common risk variants in NPHS1 and TNFSF15 are associated with childhood steroid-sensitive nephrotic syndrome

To understand the genetics of steroid-sensitive nephrotic syndrome (SSNS), we conducted a genome-wide association study in 987 childhood SSNS patients and 3,206 healthy controls with Japanese ancestry. Beyond known associations in the HLA-DR/DQ region, common variants in NPHS1-KIRREL2 (rs56117924, P=4.94E-20, odds ratio (OR) =1.90) and TNFSF15 (rs6478109, P=2.54E-8, OR=0.72) regions achieved genome-wide significance and were replicated in Korean, South Asian and African populations. Trans-ethnic meta-analyses including Japanese, Korean, South Asian, African, European, Hispanic and Maghrebian populations confirmed the significant associations of variants in NPHS1-KIRREL2 (P_meta=6.71E-28, OR=1.88) and TNFSF15 (P_meta=5.40E-11, OR=1.33) loci. Analysis of the NPHS1 risk alleles with glomerular NPHS1 mRNA expression from the same person revealed allele specific expression with significantly lower expression of the transcript derived from the risk haplotype (Wilcox test p=9.3E-4). Because rare pathogenic variants in NPHS1 cause congenital nephrotic syndrome of the Finnish type (CNSF), the present study provides further evidence that variation along the allele frequency spectrum in the same gene can cause or contribute to both a rare monogenic disease (CNSF) and a more complex, polygenic disease (SSNS).

Integrated GWAS and mRNA Microarray Analysis Identified IFNG and CD40L as the Central Upstream Regulators in Primary Biliary Cholangitis

Genome‐wide association studies (GWASs) in European and East Asian populations have identified more than 40 disease‐susceptibility genes in primary biliary cholangitis (PBC). The aim of this study is to computationally identify disease pathways, upstream regulators, and therapeutic targets in PBC through integrated GWAS and messenger RNA (mRNA) microarray analysis. Disease pathways and upstream regulators were analyzed with ingenuity pathway analysis in data set 1 for GWASs (1,920 patients with PBC and 1,770 controls), which included 261 annotated genes derived from 6,760 single‐nucleotide polymorphisms (P < 0.00001), and data set 2 for mRNA microarray analysis of liver biopsy specimens (36 patients with PBC and 5 normal controls), which included 1,574 genes with fold change >2 versus controls (P < 0.05). Hierarchical cluster analysis and categorization of cell type–specific genes were performed for data set 2. There were 27 genes, 10 pathways, and 149 upstream regulators that overlapped between data sets 1 and 2. All 10 pathways were immune‐related. The most significant common upstream regulators associated with PBC disease susceptibility identified were interferon‐gamma (IFNG) and CD40 ligand (CD40L). Hierarchical cluster analysis of data set 2 revealed two distinct groups of patients with PBC by disease activity. The most significant upstream regulators associated with disease activity were IFNG and CD40L. Several molecules expressed in B cells, T cells, Kupffer cells, and natural killer–like cells were identified as potential therapeutic targets in PBC with reference to a recently reported list of cell type–specific gene expression in the liver. Conclusion: Our integrated analysis using GWAS and mRNA microarray data sets predicted that IFNG and CD40L are the central upstream regulators in both disease susceptibility and activity of PBC and identified potential downstream therapeutic targets.

POGLUT1, the putative effector gene driven by rs2293370 in primary biliary cholangitis susceptibility locus chromosome 3q13.33

Primary biliary cholangitis (PBC) is a chronic and cholestatic autoimmune liver disease caused by the destruction of intrahepatic small bile ducts. Our previous genome-wide association study (GWAS) identified six susceptibility loci for PBC. Here, in order to further elucidate the genetic architecture of PBC, a GWAS was performed on an additional independent sample set, then a genome-wide meta-analysis with our previous GWAS was performed based on a whole-genome single nucleotide polymorphism (SNP) imputation analysis of a total of 4,045 Japanese individuals (2,060 cases and 1,985 healthy controls). A susceptibility locus on chromosome 3q13.33 (including ARHGAP31, TMEM39A, POGLUT1, TIMMDC1, and CD80) was previously identified both in the European and Chinese populations and was replicated in the Japanese population (OR = 0.7241, P = 3.5 × 10^-9). Subsequent in silico and in vitro functional analyses identified rs2293370, previously reported as the top-hit SNP in this locus in the European population, as the primary functional SNP. Moreover, e-QTL analysis indicated that the effector gene of rs2293370 was Protein O-Glucosyltransferase 1 (POGLUT1) (P = 3.4 × 10^-8). This is the first study to demonstrate that POGLUT1 and not CD80 is the effector gene regulated by the primary functional SNP rs2293370, and that increased expression of POGLUT1 might be involved in the pathogenesis of PBC.

NFKB1 and MANBA Confer Disease Susceptibility to Primary Biliary Cholangitis via Independent Putative Primary Functional Variants

BACKGROUND & AIMS

Primary biliary cholangitis (PBC) is a chronic and cholestatic liver disease that eventually leads to cirrhosis and hepatic failure. We recently identified several susceptibility genes included NFKB1 and MANBA for PBC in the Japanese population by genome-wide association study. However, the primary functional variants in the NFKB1/MANBA region and the molecular mechanism for conferring disease susceptibility to PBC have not yet been clarified.

METHODS

We performed high-density association mapping based on a single-nucleotide polymorphism (SNP) imputation analysis, using data from a whole-genome sequence reference panel of 1070 Japanese individuals and the previous genome-wide association study (1389 PBC patients, 1508 healthy controls). Among SNPs (P < 5.0 × 10^-7) in the NFKB1/MANBA region, putative primary functional variants and the molecular mechanism for conferring disease susceptibility to PBC were identified by in silico/in vitro functional analysis.

RESULTS

Among the SNPs in the NFKB1/MANBA region, rs17032850 and rs227361, which changed the binding of transcription factors lymphoid enhancer-binding factor 1 (LEF-1) and retinoid X receptor α (RXRα), respectively, were identified as putative primary functional variants that regulate gene expression. In addition, expression-quantitative trait locus data and gene editing using a clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system supported the potential role of rs17032850 and rs227361 in regulating NFKB1 and MANBA expression, respectively.

CONCLUSIONS

We identified independent putative primary functional variants in NFKB1/MANBA and showed the distinct molecular mechanism by which each putative primary functional variant conferred susceptibility to PBC. Our approach was useful to dissect the pathogenesis not only of PBC, but also other digestive diseases in which NFKB1/MANBA has been reported as a susceptibility locus.

Increased expression and altered localization of cathepsin Z are associated with progression to jaundice stage in primary biliary cholangitis

Our recent genome-wide association study found that the NELFCD/CTSZ locus was significantly associated with progression of primary biliary cholangitis (PBC) to jaundice stage in the Japanese population. In this study, we investigated the role of cathepsin Z in the etiology and pathology of PBC. Serum cathepsin Z levels were measured using enzyme-linked immunosorbent assay. The expression and localization of cathepsin Z in liver specimens were analyzed by western blotting and immunohistochemistry. In PBC patients, serum cathepsin Z levels were significantly increased with disease progression. In addition, its levels were positively correlated with alanine transaminase, aspartate transaminase and total bilirubin, and were negatively correlated with platelet count and albumin. Cathepsin Z expression was markedly increased in hepatocytes at later stages of PBC, and its localization was altered from the peri-bile canaliculus to the cytoplasm, where a fraction was no longer colocalized with endosomal/lysosomal vesicles. Similar altered expression of cathepsin Z was observed in end-stage of other cholestatic liver diseases including sepsis, obstructive jaundice, and Alagille syndrome. Our results indicate that altered expression and localization of cathepsin Z in hepatocytes are characteristic features of PBC and other cholestatic liver diseases, and are implicated in the progression of PBC.

Genome-wide association studies identify PRKCB as a novel genetic susceptibility locus for primary biliary cholangitis in the Japanese population

A previous genome-wide association study (GWAS) performed in 963 Japanese individuals (487 primary biliary cholangitis [PBC] cases and 476 healthy controls) identified TNFSF15 (rs4979462) and POU2AF1 (rs4938534) as strong susceptibility loci for PBC. In this study, we performed GWAS in additional 1,923 Japanese individuals (894 PBC cases and 1,029 healthy controls), and combined the results with the previous data. This GWAS, together with a subsequent replication study in an independent set of 7,024 Japanese individuals (512 PBC cases and 6,512 healthy controls), identified PRKCB (rs7404928) as a novel susceptibility locus for PBC (odds ratio [OR] = 1.26, P = 4.13 × 10-9). Furthermore, a primary functional variant of PRKCB (rs35015313) was identified by genotype imputation using a phased panel of 1,070 Japanese individuals from a prospective, general population cohort study and subsequent in vitro functional analyses. These results may lead to improved understanding of the disease pathways involved in PBC, forming a basis for prevention of PBC and development of novel therapeutics.

A case of primary biliary cirrhosis in a patient with rheumatoid arthritis

The true prevalence of PBC in RA is not well known. Herein, we report an unusual case of a patient with PBC and RA, and discuss the association between these two diseases. PBC should be ruled out in the differential diagnosis of patients with RA having abnormal liver function tests.

Disease susceptibility genes shared by primary biliary cirrhosis and Crohn's disease in the Japanese population

We previously identified TNFSF15 as the most significant susceptibility gene at non-HLA loci for both primary biliary cirrhosis (PBC) and Crohn's diseases (CD) in the Japanese population. The aim of this study is to identify further disease susceptibility genes shared by PBC and CD. We selected 15 and 33 genetic variants that were significantly associated with PBC and CD, respectively, based on previously reported genome-wide association studies of the Japanese population. Next, an association study was independently performed for these genetic variants in CD (1312 CD patients and 3331 healthy controls) and PBC (1279 PBC patients and 1015 healthy controls) cohorts. Two CD susceptibility genes, ICOSLG rs2838519 and IL12B rs6556412, were also nominally associated with susceptibility to PBC (P=3.85 × 10(-2) and P=8.40 × 10(-3), respectively). Three PBC susceptibility genes, CXCR5 rs6421571, STAT4 rs7574865 and NFKB1 rs230534, were nominally associated with susceptibility to CD (P=2.82 × 10(-2), P=3.88 × 10(-2) and P=2.04 × 10(-2), respectively). The effect of ICOSLG and CXCR5 variants were concordant but the effect of STAT4, NFKB1 and IL12B variants were discordant for PBC and CD. TNFSF15 and ICOSLG-CXCR5 might constitute a shared pathogenic pathway in the development of PBC and CD in the Japanese population, whereas IL12B-STAT4-NFKB1 might constitute an opposite pathogenic pathway, reflecting the different balance between Th1 and Th17 in the two diseases.

Human primary biliary cirrhosis-susceptible allele of rs4979462 enhances TNFSF15 expression by binding NF-1

A genome-wide association study (GWAS) identified tumor necrosis factor superfamily member 15 (TNFSF15) as the strongest associated gene with susceptibility to primary biliary cirrhosis (PBC) outside the HLA loci in the Japanese population. However, causal functional variants of the TNFSF15 locus and the molecular mechanism underlying disease susceptibility have not been clarified. Here, to identify the functional causal variants of the TNFSF15 locus, integrated analysis comprising in silico analysis, a case-control association study and in vitro functional analysis was performed. Initially, 32 functional candidate single-nucleotide polymorphisms (SNPs) in the expression regulatory motifs, the coding region, or the untranslated regions (UTRs) of the TNFSF15 locus were selected by in silico analysis. By the case-control association studies using PBC patients (n = 1279) and healthy controls (n = 1091) in the Japanese population, rs4979462 [P = 1.85 × 10(-14) (our previous study)], rs56211063 (P = 2.21 × 10(-14)), and rs55768522 (r(2) = 1 with rs4979462) were likely candidates for causal variants. Among these SNPs, rs4979462 was identified as the causal variant by in vitro functional analysis using luciferase assay and electrophoretic mobility shift assay (EMSA). Super-shift assay clarified that PBC-susceptible allele of rs4979462 generated a novel NF-1 binding site. Moreover, higher endogenous TNFSF15 protein and mRNA expression levels were observed in individuals with the PBC-susceptible allele of rs4979462. This study identified the causal variant for PBC susceptibility in the TNFSF15 locus and clarified its underlying molecular mechanism. TNFSF15 and NF-1 are considered to be potential targets for the treatment of PBC.

Identification of Genes Involved in the Suppression of Antibody Production from Human Peripheral Blood Lymphocytes

Pretreatment with L-leucyl-L-leucine methyl ester (LLME) is a prerequisite for peripheral blood mononuclear cells (PBMCs) to produce antigen-specific antibodies when sensitized with an antigen. Little information, however, is available regarding the mechanisms involved in LLME-induced augmentation of antibody production from PBMCs that are antigen sensitized. In the present study, we attempted to identify the genes involved in the suppression of antibody production from PBMCs that was not treated with LLME, but sensitized with an antigen. Using subtractive screening, we obtained 63 independent genes, including 17 EST genes, that are specific for LLME-nontreated PBMC. Among these genes, the expression of heavy chain ferritin (H-ferritin), CC chemokine ligand 18 (CCL18), and matrix metalloproteinase 12 (MMP12) were augmented in LLME-nontreated PBMCs, suggesting that inflammatory factors might be involved in the suppression of antibody production in LLME-nontreated PBMCs.

Systemic and local expression levels of TNF-like ligand 1A and its decoy receptor 3 are increased in primary biliary cirrhosis

BACKGROUND & AIMS

Through a genome-wide association study of a Japanese population, we recently identified TNFSF15, a gene encoding TNF-like ligand 1A (TL1A), as a susceptibility gene for primary biliary cirrhosis (PBC). We investigated the clinical significance of TL1A and one of its receptors, decoy receptor 3 (DcR3), in PBC.

METHODS

We analysed the systemic and local expression of TL1A and DcR3 in 110 PBC patients and 46 healthy controls using enzyme-linked immunosorbent assay, quantitative polymerase chain reaction and immunohistochemical staining.

RESULTS

Serum TL1A levels were significantly increased in PBC patients at both early and late stages as compared with healthy controls, and its levels were significantly decreased in early-stage PBC patients after ursodeoxycholic acid (UDCA) treatment. TL1A was immunohistochemically localized to biliary epithelial cells, Kupffer cells, blood vessels and infiltrating mononuclear cells in the PBC liver. In addition, TL1A messenger RNA expression was increased in the PBC liver as compared with the non-diseased liver. Serum DcR3 levels were also significantly increased in PBC patients, and were significantly decreased after UDCA treatment in early-stage PBC patients.

CONCLUSIONS

These results indicate that TL1A and DcR3 may play an important role in the pathogenesis of PBC.

Genetic polymorphisms of OCT-1 confer susceptibility to severe progression of primary biliary cirrhosis in Japanese patients

BACKGROUND

To identify the genetic factors involved in the pathogenesis of primary biliary cirrhosis (PBC), we focused on the organic cation transporter 1 (OCT1/SLC22A1), which is closely associated with phosphatidylcholine synthesis in hepatocytes.

METHODS

We selected four (rs683369, rs2282143, rs622342 and rs1443844) OCT-1 single nucleotide polymorphisms (SNPs), and genotyped these SNPs using the TaqMan probe method in 275 Japanese PBC patients and 194 gender-matched, healthy volunteers as controls.

RESULTS

The Chi-square test revealed that the rs683369 variant allele (G) was associated with insusceptibility to PBC development [P = 0.009, odds ratio (OR) 0.60, 95 % confidence interval (CI) 0.40-0.88] in an allele model, and that the rs683369 variant allele (G) was associated with jaundice-type progression in a minor allele dominant genotype model (P = 0.032, OR 3.10, 95 % CI 1.05-9.14). The OCT-1 rs2282143 variant (T) and rs622342 variant (C) were also associated with jaundice-type progression in a minor allele recessive genotype model (P = 0.0002, OR 10.58, 95 % CI 2.36-47.54, and P = 0.006, OR 7.84, 95 % CI 1.39-44.36, respectively). Furthermore, the association of OCT-1 rs683369 and rs622342 with susceptibility to jaundice-type progression was confirmed by a replication study with a distinct set of PBC patients who underwent liver transplantation.

CONCLUSIONS

The present study is the first report on the association of OCT-1 genetic polymorphisms with the overall development and jaundice-type progression of PBC.

Suppression of immunoglobulin production in human peripheral blood mononuclear cells by monocytes via secretion of heavy-chain ferritin

In vitro antigen stimulation of peripheral blood mononuclear cells (PBMCs) does not induce immunoglobulin (Ig) production. However, pretreatment of PBMCs with l-leucyl-l-leucine methyl ester (LLME) prior to in vitro stimulation removes the suppression of Ig production. In the present study, we attempted to identify the target cells of LLME and determine the mechanisms by which Ig production in PBMCs is suppressed. We found that CD14(+) monocytes are involved in the suppression of Ig production in PBMCs. Furthermore, we confirmed that heavy-chain ferritin derived from CD14(+) monocytes suppresses Ig production in PBMCs, possibly through iron sequestration.

Commensal microbiota modulate murine behaviors in a strictly contamination-free environment confirmed by culture-based methods

BACKGROUND

There is increasing evidence suggesting the existence of an interaction between commensal microbiota, the gut and the brain. The aim of this study was to examine the influence of commensal microbiota on the host behaviors in a contamination-free environment, which was verified by culture-based methods.

METHODS

Open-field and marble-burying tests were used to analyze anxiety-like behaviors and locomotor activity in gnotobiotic BALB/c mice with a common genetic background in a sterile isolator. The monoamine levels in several regions of the brain were measured in germfree (GF) mice and commensal fecal microbiota-associated mice (EX-GF).

KEY RESULTS

A 24-h exposure to the environment outside the sterile isolators rendered GF mice less anxious than those not contaminated, while there was no change in the locomotion. EX-GF mice, the gnotobiotic mice with normal specific pathogen-free microbiota, were less anxious and active than GF mice using open-field and marble-burying tests. The norepinephrine, dopamine, and serotonin turnover rates were higher in the EX-GF mice than in the GF mice in most regions of the brain, suggesting that monoaminergic neurotransmission might increase in the EX-GF mice comparing the GF mice. Monoassociation with Brautia coccoides reduced the anxiety level, but it did not affect the locomotor activity. In contrast, colonization with Bifidobacterium infantis decreased the locomotor activity, while having little effect on the anxiety level.

CONCLUSIONS & INFERENCES

These results strongly support the current view that gut microorganisms modulate brain development and behavior.

Genome-wide association study identifies TNFSF15 and POU2AF1 as susceptibility loci for primary biliary cirrhosis in the Japanese population

For the identification of susceptibility loci for primary biliary cirrhosis (PBC), a genome-wide association study (GWAS) was performed in 963 Japanese individuals (487 PBC cases and 476 healthy controls) and in a subsequent replication study that included 1,402 other Japanese individuals (787 cases and 615 controls). In addition to the most significant susceptibility region, human leukocyte antigen (HLA), we identified two significant susceptibility loci, TNFSF15 (rs4979462) and POU2AF1 (rs4938534) (combined odds ratio [OR] = 1.56, p = 2.84 × 10(-14) for rs4979462, and combined OR = 1.39, p = 2.38 × 10(-8) for rs4938534). Among 21 non-HLA susceptibility loci for PBC identified in GWASs of individuals of European descent, three loci (IL7R, IKZF3, and CD80) showed significant associations (combined p = 3.66 × 10(-8), 3.66 × 10(-9), and 3.04 × 10(-9), respectively) and STAT4 and NFKB1 loci showed suggestive association with PBC (combined p = 1.11 × 10(-6) and 1.42 × 10(-7), respectively) in the Japanese population. These observations indicated the existence of ethnic differences in genetic susceptibility loci to PBC and the importance of TNF signaling and B cell differentiation for the development of PBC in individuals of European descent and Japanese individuals.

Serum amyloid A triggers the mosodium urate -mediated mature interleukin-1β production from human synovial fibroblasts

Background

Monosodium urate (MSU) has been shown to promote inflammasome activation and interleukin-1β (IL-1β) secretion in monocyte/macrophages, but the cellular pathway and nod-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome activation in synovial tissues, remain elusive. In this study, we investigated the effects of MSU on synovial fibroblasts to elucidate the process of MSU-mediated synovial inflammation.

Methods

Human synovial fibroblasts were stimulated with MSU in the presence or absence of serum amyloid A (SAA). The cellular supernatants were analyzed by immunoblotting using anti-IL-1β or anti-caspase-1 antibodies. IL-1β or NLRP3 mRNA expressions were analyzed by real-time PCR or reverse transcription-PCR (RT-PCR) method.

Results

Neither SAA nor MSU stimulation resulted in IL-1β or interleukin-1α (IL-1α) secretions and pro-IL-1β processing in synovial fibroblasts. However, in SAA-primed synovial fibroblasts, MSU stimulation resulted in the activation of caspase-1 and production of active IL-1β and IL-1α. The effect of SAA on IL-1β induction was impaired in cells by silencing NLRP3 using siRNA or treating with caspase-1 inhibitor. In addition, SAA induced the secretion of cathepsin B and NLRP3 mRNA expression in synovial fibroblasts.

Conclusions

Our data demonstrate that exposure of human synovial fibroblasts to SAA promotes MSU-mediated caspase-1 activation and IL-1β secretion in the absence of microbial stimulation. These findings provide insight into the molecular processes underlying the synovial inflammatory condition of gout.

Serum amyloid A (SAA) induces pentraxin 3 (PTX3) production in rheumatoid synoviocytes

OBJECTIVE

Pentraxin 3 (PTX3) is an acute-phase reactant that is involved in amplification of the inflammatory response and innate immunity. In the present study, we evaluated the relationship between PTX3 and serum amyloid A (SAA), another acute-phase reactant, in rheumatoid synoviocytes.

METHODS

PTX3 mRNA expression was examined by reverse transcription polymerase chain reaction, and PTX3 protein was measured by enzyme-linked immunosorbent assay.

RESULTS

SAA induced PTX3 mRNA and PTX3 protein expression in rheumatoid synoviocytes. SAA-induced PTX3 expression was attenuated when rheumatoid synoviocytes were nucleofected with N-formyl peptide receptor ligand-1 (FPRL-1)-specific siRNA, suggesting the involvement of FPRL-1. Furthermore, SAA-induced PTX3 expression was inhibited by NF-κB or mitogen-activated protein kinase-specific inhibitors. Neither soluble TNF receptor (etanercept) nor recombinant IL-1 receptor antagonist affected PTX3 production by SAA-stimulated synoviocytes, suggesting that SAA directly induces PTX3.

CONCLUSION

Our data suggest that SAA plays a role in the proinflammatory and immune responses in rheumatoid synovium by inducing PTX3. We provide the first evidence that the acute-phase reactant SAA, which is produced systemically by hepatocytes, perpetuates the rheumatoid inflammatory processes by inducing another proinflammatory molecule, PTX3, locally in rheumatoid synovial tissues.

Inhibitory effects of the JAK inhibitor CP690,550 on human CD4(+) T lymphocyte cytokine production

Background

The new JAK3 inhibitor, CP690,550, has shown efficacy in the treatment of rheumatoid arthritis. The present study was undertaken to assess the effects of CP690,550 on cytokine production and cellular signaling in human CD4⁺ T cells.

Results

CD4⁺ T cells produced IL-2, IL-4, IL-17, IL-22 and IFN-γ in following stimulation with a CD3 antibody. At the optimal concentration, CP690,550 almost completely inhibited the production of IL-4, IL-17, IL-22 and IFN-γ from these activated CD4⁺ T cells, but only had marginal effects on IL-2 production. Moreover CP690,550 inhibited anti-CD3-induced phosphorylation of STAT1, STAT3, STAT4, STAT5, and STAT6, but not the TCR-associated phosphorylation of ZAP-70.

Conclusions

Therefore, CP690,550-mediated modification of the JAK/STAT pathway may be a new immunosuppressive strategy in the treatment of autoimmune diseases.

A polymorphism in the integrin αV subunit gene affects the progression of primary biliary cirrhosis in Japanese patients

BACKGROUND

Accumulating evidence indicates that multiple genetic factors are involved in the pathogenesis of primary biliary cirrhosis (PBC). The aim of this study was to investigate whether polymorphisms of the integrin αV subunit gene (ITGAV), a component of integrin αVβ6, which plays an important role in the process of fibrosis, are associated with susceptibility to the onset and/or progression of PBC.

METHODS

In the primary study, eight tag single nucleotide polymorphisms (SNPs) in ITGAV were analyzed by polymerase chain reaction (PCR)-restriction fragment length polymorphism, direct DNA sequencing, or high-resolution melting curve analysis in 309 Japanese patients with PBC who were registered in the National Hospital Organization Study Group for Liver Disease in Japan (PBC cohort I) and 293 gender-matched healthy Japanese volunteers (control subjects). For the replication study, 35 PBC patients who progressed to end-stage hepatic failure and underwent liver transplantation (PBC cohort II) were also analyzed.

RESULTS

Three tag SNPs (rs3911238, rs10174098, and rs1448427) in ITGAV were significantly associated with the severe progression of PBC, but not with susceptibility to the onset of PBC, in the primary study (PBC cohort I). Among these SNPs, rs1448427 was also significantly associated with the severe progression to end-stage hepatic failure in the replication study of PBC patients who underwent liver transplantation (PBC cohort II).

CONCLUSIONS

ITGAV is a genetic determinant for the severe progression of PBC in Japanese patients. Genetic polymorphisms of ITGAV may be useful for identifying high-risk Japanese PBC patients, including those who will require liver transplantation, at the time of initial diagnosis.

Analysis of HLA-DRB1 polymorphisms in Japanese patients with primary biliary cirrhosis (PBC): The HLA-DRB1polymorphism determines the relative risk of antinuclear antibodies for disease progression in PBC

AIMS

Anti-gp210 and anti-centromere antibodies are different risk factors for the progression of primary biliary cirrhosis (PBC). However, the association of human leukocyte antigen (HLA) polymorphisms with these risk factors is unknown.

METHODS

We determined the HLA-DRB1 genotype in 334 Japanese PBC patients and studied their serum antibodies to gp210 and centromere during the 1-452-month observation period.

RESULTS

Anti-gp210 (odds ratio [OR] 46.56, 95% confidence interval [CI], 9.20-850.1) and anti-centromere antibodies (OR, 2.36, 95% CI, 1.28-4.35) were significant risk factors for jaundice- and nonjaundice-type progression, respectively. HLA-DRB1*0405 and *0803 predisposed patients to anti-gp210 (OR, 1.61, 95% CI, 1.08-2.39) and anti-centromere (OR, 2.30, 95% CI, 1.41-3.73) antibody production, respectively. HLA-DRB1*1502 and *0901 patients were predisposed to nonjaundice-type progression (OR, 1.98, 95% CI, 1.13-3.40 and OR, 1.78, 95% CI, 1.02-3.03), while HLA-DRB1*0803 and *0405 patients were predisposed to disease development (OR, 2.24, 95% CI, 1.48-3.41 and OR, 1.53, 95% CI, 1.11-2.11, respectively). Stratifying patients by HLA-DRB1 alleles revealed that anti-gp210 antibodies was a strong risk factor, regardless of the HLA-DRB1 alleles for jaundice-type progression, while anti-centromere antibodies was a significant risk factor for nonjaundice-type progression in patients with HLA-DRB1*0405 (OR, 6.89, 95% CI, 2.18-26.56) and -DRB1*0803 (OR, 5.42, 95% CI, 1.47-24.62) but not other HLA-DRB1 alleles.

CONCLUSIONS

HLA-DRB1 polymorphisms are significantly associated with not only disease development and progression but also antinuclear antibody production and the determination of the relative risk of antinuclear antibodies that contribute to PBC disease progression.

Serum amyloid A protein stimulates CCL20 production in rheumatoid synoviocytes

OBJECTIVE

Although serum amyloid A (SAA) has been used as a marker of inflammation, its role in leucocyte recruitment and angiogenesis has not been well established in RA. CCL20 is a chemokine involved in the migration of CCR6-expressing Th17 cells. To study the contribution of SAA to the recruitment of Th17 cells, we investigated the effects of SAA on CCL20 production by RA synoviotytes.

METHODS

Synoviocytes isolated from RA patients were stimulated with recombinant SAA and cellular supernatants were analysed by CCL20-specific ELISA. CCL-20 mRNA expression was analysed by RT-PCR.

RESULTS

SAA is a most potent inducer of CCL20 secretion in RA synoviocytes compared with other inflammatory cytokines (IL-1beta, TNF-alpha and IL-17A). SAA stimulation induced CCL20 mRNA expression in RA synoviocytes, which was not affected by polymyxin B pre-treatment. SAA-induced CCL20 production was down-regulated by NF-kappaB inhibition and partially by c-jun N-terminal kinase (JNK) inhibition. SAA-induced CCL20 production was also suppressed by dexamethasone or FK506.

CONCLUSION

These findings suggest that SAA may be implicated in the recruitment of lymphocytes, including CCR6-expressing Th17 cells, in RA synovium by up-regulating CCL20 production in synoviocytes.

Potentiation of glucocorticoid receptor (GR)-mediated signaling by the immunosuppressant tacrolimus in rheumatoid synoviocytes

OBJECTIVE

The immunosuppressant tacrolimus is known to enhance many aspects of glucocorticoid. In this study, we investigated the effects of tacrolimus on glucocorticoid receptor (GR) signaling using rheumatoid fibroblast-like synoviocytes (RA-FLS).

METHODS

The nuclear translocation of GR was analyzed by immunocytochemistry. The DNA binding activity of p65 was assayed by a functional ELISA kit using nuclear extracts. GR-associated FK506-binding protein-51 (FKBP-51) was analyzed by Western blotting following immunoprecipitation of glucocorticoid receptor (GR) complexes.

RESULTS

High concentrations (10-7M) of Dexamethasone (Dex) induced GR translocation to the nucleus in RA-FLS. However, the nuclear GR translocation did not occur with low concentrations of Dex (10-9M). Tacrolimus treatment of RA-FLS results in potentiation of GR translocation to the nucleus even in the presence of a low concentration of Dex (10-9M). GR-associated FKBP-51 decreased after tacrolimus treatment. Furthermore, tacrolimus also decreased the IL-1Beta-induced DNA binding activity of p65, a subunit of NF-KappaB, in the presence of 10-9 M of Dex.

CONCLUSION

These data suggest that tacrolimus exerts anti-inflammatory properties by potentiating the GR signaling through the GR-immunosuppressant-binding proteins (immunophilins) interaction and its nuclear transport in rheumatoid synovium.

Single-nucleotide polymorphism analysis of the multidrug resistance protein 3 gene for the detection of clinical progression in Japanese patients with primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a multifactorial disease in which genetic factors rather than environmental factors may predominantly contribute to the pathogenesis. In order to identify the genetic determinants of the disease severity and progression of PBC, we examined an association of seven tag single-nucleotide polymorphisms (SNPs) in the multidrug resistance protein 3 (MDR3/ABCB4) gene in 148 Japanese PBC patients and 150 age- and sex-matched healthy control subjects. SNPs were detected via polymerase chain reaction (PCR) restriction fragment length polymorphism and PCR direct DNA sequencing methods. Subsequently, haplotypes were constructed from three tag SNPs (rs31658, rs31672, and rs1149222) that were significantly associated with progression of PBC. Logistic regression analyses revealed that a Hap 2 haplotype and its homozygous diplotype, Hap 2/Hap 2, in MDR3 were closely associated with the susceptibility to jaundice-type progression of PBC [P = 0.004, odds ratio (OR) 3.93, 95% confidence interval (CI) 1.56-9.90 and P = 0.0003, OR 17.73, 95% CI 3.77-83.42, respectively]. Conversely, another haplotype, Hap 1, and its homozygous diplotype, Hap 1/Hap 1, were associated with the insusceptibility to the progression to late-stage PBC (P = 0.021, OR 0.55, 95% CI 0.33-0.91 and P = 0.011, OR 0.24, 95% CI 0.08-0.71, respectively).

CONCLUSION

The present study is the first report of an association of MDR3 haplotypes and diplotypes with progression of PBC. The Hap 2/Hap 2 diplotype in MDR3 could therefore be potentially applied to DNA-based diagnosis in Japanese patients with PBC as a strong genetic biomarker for predicting the progression and prognosis of PBC.

Effect of intestinal microbiota on the induction of regulatory CD25+ CD4+ T cells

When oral tolerance was induced in either specific pathogen-free (SPF) or germ-free (GF) mice, ovalbumin (OVA) feeding before immunization induced oral tolerance successfully in SPF mice. On the other hand, OVA-specific immunoglobulin G1 (IgG1) and IgE titres in OVA-fed GF mice were comparable to those in phosphate-buffered saline-fed GF mice, thus demonstrating that oral tolerance could not be induced in GF mice. The frequencies of CD25(+) CD4(+)/CD4(+) cells in the mesenteric lymph node (MLN) and the absolute number of CD25(+) CD4(+) cells in the Peyer's patches and MLN of naive GF mice were significantly lower than those in naive SPF mice. In an in vitro assay, the CD25(+) CD4(+) cells from the naive SPF mice suppressed more effectively the proliferation of responder cells in a dose-dependent manner than those from the GF mice. In addition, the CD25(+) CD4(+) regulatory T (T(reg)) cells from the naive SPF mice produced higher amounts of interleukin (IL)-10 and transforming growth factor (TGF)-beta than those from the GF mice. When anti-TGF-beta neutralizing antibody, but not anti-IL-10 neutralizing antibody, was added to the in vitro proliferation assay, the suppressive effect of the CD25(+) CD4(+) T(reg) cells from the SPF mice was attenuated to the same level as that of the CD25(+) CD4(+) cells from the GF mice. In conclusion, the TGF-beta-producing CD25(+) CD4(+) T(reg) cells from the MLN of SPF mice played a major role in oral tolerance induction. In addition, as the regulatory function of the CD25(+) CD4(+) cells from the naive GF mice was much lower than that of the CD25(+) CD4(+) T(reg) cells from the SPF mice, indigenous microbiota are thus considered to contribute to the induction and maintenance of CD25(+) CD4(+) T(reg) cells.

Increased expression of Toll-like receptor 3 in intrahepatic biliary epithelial cells at sites of ductular reaction in diseased livers

Background Toll-like receptors (TLRs) may play active roles in both innate and adaptive immune responses in human intrahepatic biliary epithelial cells (HIBECs). The role of TLR3 expressed by HIBECs, however, remains unclear. Methods We determined the in vivo expression of TLRs in biopsy specimens derived from diseased livers immunohistochemically using a panel of monoclonal antibodies against human TLRs. We then examined the response of cultured HIBECs to a TLR3 ligand, polyinosinic-polycytidylic acid (polyI:C). Using siRNAs specific for Toll-IL-1R homology domain-containing adaptor molecule 1 (TICAM-1) and mitochondrial antiviral signaling protein (MAVS), we studied signaling pathways inducing IFN-beta expression. Results The expression of TLR3 was markedly increased in biliary epithelial cells at sites of ductular reaction in diseased livers, including primary biliary cirrhosis (PBC), autoimmune hepatitis (AIH), and chronic viral hepatitis (CH) as compared to nondiseased livers. Although cultured HIBECs constitutively expressed TLR3 at both the protein and mRNA levels in vitro, the addition of polyI:C to culture media induced only minimal increases in IFN-beta mRNA. In contrast, transfection of HIBECs with polyI:C induced a marked increase in mRNAs encoding a variety of chemokines/cytokines, including IFN-beta, IL-6, and TNF-alpha. The induction of IFN-beta mRNA was efficiently inhibited by an siRNA against MAVS but not against TICAM-1, indicating that the main signaling pathway for IFN-beta induction following polyI:C transfection is via retinoic acid-inducible gene I (RIG-I)/melanoma differentiation-associated gene 5 (MDA5) in HIBECs. Conclusions TLR3 expression by biliary epithelial cells increased at sites of ductular reaction in diseased livers; further study will be necessary to characterize it's in vivo physiological role.

Serum amyloid A-induced IL-6 production by rheumatoid synoviocytes

In this study, we investigated the role of serum amyloid A protein (SAA) in the production of interleukin-6 (IL-6) using rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS). Recombinant SAA stimulation induced the production of pro-inflammatory cytokine, IL-6, from RA-FLS. The signaling events induced by SAA included the activation of the mitogen-activated protein kineases, p38 and JNK1/2 and the activation of nuclear factor-kappa B (NF-kappaB). Inhibitor studies have shown SAA-induced IL-6 production to be down-regulated by NF-kappaB inhibition and partially inhibited by p38 or JNK inhibitors. Our findings demonstrate that SAA is a significant inducer of IL-6, which is critically involved in RA pathogenesis.

A minimally hypomorphic mutation in Btk resulting in reduced B cell numbers but no clinical disease

Reduced B cell numbers and a mutation in Btk are considered sufficient to make the diagnosis of X-linked agammaglobulinaemia. In the process of conducting family studies, we identified a 58-year-old healthy man with an amino acid substitution, Y418H, in the adenosine-5'-triphosphate binding site of Btk. Immunofluorescence studies showed that this man had 0.85% CD19+ B cells (normal 4-18%) in the peripheral circulation and his monocytes were positive for Btk. He had borderline low serum immunoglobulins but normal titres to tetanus toxoid and multiple pneumococcal serotypes. To determine the functional consequences of the amino acid substitution, a Btk- chicken B cell line, DT40, was transfected with expression vectors producing wild-type Btk or Y418H Btk. The transfected cells were stimulated with anti-IgM and calcium flux and inositol triphosphate (IP3) production were measured. Cells bearing the mutant protein demonstrated consistently a 15-20% decrease in both calcium flux and IP3 production. These findings indicate that even a modest decrease in Btk function can impair B cell proliferation or survival. However, a mutation in Btk and reduced numbers of B cells are not always associated with clinical disease.

Predictive role of anti-gp210 and anticentromere antibodies in long-term outcome of primary biliary cirrhosis

Because some of the autoreactive T-cell clones specific for human PDC-E2 cross-react to mimicry peptides having an EIExDK motif derived from nuclear antigens such as human gp210 and sp100, we studied the clinical significance of antinuclear antibodies (ANA) in primary biliary cirrhosis (PBC) patients registered to the National Hospital Organization Study Group for Liver Disease in Japan (NHOSLJ). We found that there are two different types of progression in PBC; one is a hepatic failure-type progression which is represented by positive anti-gp210 antibodies and the other is a portalhypertension-type progression which is represented by positive anticentromere antibodies. We discuss the predictive role of these ANA in the long-term outcome of PBC and the mechanisms by which two different PBC progression types occur based on molecular mimicry and aberrant expression of nuclear antigens.

In vitro immunization can elicit the expansion of diverse repertoire of B cells from peripheral blood mononuclear cells

We previously developed an in vitro immunization (IVI) protocol of human peripheral blood mononuclear cells (PBMC) for generating antigen-specific human antibodies. In order to clarify whether IVI protocolinduces antigen-specific B cell responses in PBMC, we analyzed family gene usage and sequence of the variable region gene of immunoglobulin heavy chain (VH gene) of the antibody produced from the in vitro immunized PBMC. Sequence homology analyses of VH gene demonstrated that a larger repertoire of B cells can be sensitized with mite-extract than with cholera toxin B subunit and rice allergen. Further, antigen-specific B cells were efficiently expanded by using CpG oligodeoxynucleotide as adjuvant. These results suggest that appropriate combination of sensitizing antigen and adjuvant is primarily important for expansion of antigen-specific B cells in IVI protocol.

IL-10 augments antibody production in in vitro immunized lymphocytes by inducing a Th2-type response and B cell maturation

An in vitro immunization (IVI) protocol enables antigen specific antibody production from L-Leucyl-L-Leucine methyl ester (LLME)-treated human peripheral blood lymphocytes (PBL) upon antigen stimulation in the presence of IL-2, IL-4, and muramyl dipeptide. In the course of our studies, we have found that IL-10 added at the antigen sensitization significantly augmented antibody production level from the LLME-treated PBL. In the present study, we tried to demonstrate the role of IL-10 in the augmentation of antibody production in an IVI protocol by clarifying the cytokine expression profiles in CD4(+) and CD8(+) T cells. The results showed that IL-10 skewed the Th1/Th2 balance to Th2-type responses by suppressing Th1-type cytokine production and augmenting Th2-type cytokine production in CD4(+) and CD8(+) T cells, as well as in CD19(+) B cells. Furthermore, IL-10 augmented the expression of CD38, an antigen marker of plasma cells, on B cells, which clearly indicates that IL-10 promoted differentiation and maturation of B cells in an IVI protocol. These results indicate that IL-10 plays an important role in setting the cellular milieu to produce antibodies in an IVI protocol.

Different individual immune responses elicited by in vitro immunization

We have previously demonstrated that the addition of muramyl dipeptide (MDP), interleukin-2 (IL-2) and IL-4 effectively raises antibody production from L-Leucyl-L-leucine methyl ester (LLME)-treated human peripheral blood lymphocytes (PBLs) against specific soluble antigen when immunized in vitro. However, PBLs from individual donors were separate optimal conditions regarding concentrations for IL-2 and IL-4, which in turn required us to optimize each individual PBLs to effectively produce antigen specific human antibody by in vitro immunization. These individual differences in the requirement for IL-2 and IL-4 reflects the differences in individual immune responses against a specific soluble antigen, which can be elicited by in vitro immunization. In the present study, we investigated these individual differences in the requirement for IL-2 and IL-4 to induce antibody productionin vitro in the PBLs of 12 volunteers (9 healthy donors and 3 allergenic patients). IL-2 requirements for antibody production varied dependent upon each donor, while higher amounts of IL-4 inhibited IgM and IgG production in all of the healthy donors. However, some of the characteristic features for PBLs donated from allergenic included lowered IgM production compared to PBLs derived from healthy donors, and very high IgE production in the absence of cytokines and allergen. These results demonstrate that the sensitivity of PBLs against antigen sensitization differs between healthy donors and atopic patients, which suggests that the frequency of antigen sensitization might be reflected in differing activation states and/or differing subpopulations of lymphocytes in vivo.

An oral introduction of intestinal bacteria prevents the development of a long-term Th2-skewed immunological memory induced by neonatal antibiotic treatment in mice

BACKGROUND

Recent epidemiological studies indicate that antibiotic use in infancy may be associated with an increased risk of developing atopy. Our previous work on animals demonstrated that kanamycin use during infancy promotes a shift in the Th1/Th2 balance towards a Th2-dominant immunity.

OBJECTIVE

The first purpose of this study is to clarify whether or not the supplementation of intestinal bacteria can reverse such a Th2-skewed response induced by neonatal antibiotic use. The second objective is to elucidate the contribution of genetic factors to antibiotic-induced immune-deviation.

METHODS

BALB/c or C57BL/6 mice at 3 weeks of age were orally administered 600 microg/day of kanamycin sulphate for seven consecutive days. Thereafter, the mice were inoculated with one type of intestinal bacterial species: Enterococcus faecalis, Lactobacillus acidophilus or Bacteroides vulgatus. Blood samples were collected 10 weeks after the cessation of kanamycin treatment, and the effect of the kanamycin treatment on Th1/Th2 balance was evaluated based on in vivo antibody levels.

RESULTS

A kanamycin-induced elevation of the serum IgE levels was reversed by the supplementation with Enterococcus faecalis, and to a lesser extent by that with Lactobacillus acidophilus. The IgE/IgG2a ratio in the mice supplemented with Enterococcus faecalis significantly decreased in comparison with that in the kanamycin-treated mice without any bacterial supplementation, while such a ratio was enhanced in the mice inoculated with Bacteroides vulgatus. No antibiotic-induced Th2-skewed response was seen in C57BL/6 mice that are genetically biased towards Th1-dominant immunity.

CONCLUSION

These results suggest that adequate probiotic intervention after antibiotic treatment may improve the intestinal ecosystem, and thereby prevent the Th2-shifted immunity induced by neonatal antibiotic use. In addition, the difference of genetic backgrounds also contributes to such an antibiotic-induced Th2-skewed response.

The failure of oral tolerance induction is functionally coupled to the absence of T cells in Peyer's patches under germfree conditions

Although intestinal bacterial flora has been thought to play a role in the induction of oral tolerance, the mechanism has yet to be elucidated. We therefore examined the bacterial flora-dependent acquisition of susceptibility to oral tolerance induction using a gnotobiotic murine model. Germ-free (GF) mice exhibited a significant shortage of T cells in the PPs in comparison to SPF mice. A recovery in the number of such T cells was accomplished in the gnotobiotic mice associated with Bifidobacterium infantis or Escherichia coli but not in the gnotobiotic mice with Clostridium perfringens or Staphylococcus aureus. To examine the susceptibility to oral tolerance induction, these mice were orally given ovalbumin (OVA) as a tolerogen and then injected i.p. with the Ag. The Ag-specific IgG1 in the serum remained at a low level in both SPF and those gnotobiotic mice groups containing a sufficient number of T cells in the PPs. However, no such unresponsiveness in the Ab response was observed in GF or the other gnotobiotic mice groups containing only a few T cells in the tissues. Adoptive cell transfer analysis clearly showed that a sufficient number of T cells in the PPs is required for the induction of oral tolerance. Furthermore, the reduced expression of SLC (secondary lymphoid-tissue chemokine), which is responsible for T-cell migration to lymphoid organs, was observed in the PPs of GF mice, resulting in a shortage of T cells in the tissues. However, the reduced expression of SLC was restored even in the GF mice after conventionalization, thus suggesting that the failure of oral tolerance induction is functionally coupled to the innate absence of T cells under the GF condition.

Total synthesis and antifungal activity of 9-methoxystrobilurin L as the originally proposed 1,4-benzodioxan structure

Total synthesis of both enantiomers of 9-methoxystrobilurin L as the originally proposed 1,4-benzodioxan structure was successfully achieved. The 1H and 13C NMR spectra of synthesized 9-methoxystrobilurin L were compared with those of a naturally-occurring sample. It was strongly indicated that naturally-occurring 9-methoxystrobilurin L has not the originally reported 1,4-benzodioxan structure but a 1,5-benzodioxepin structure, the same as previously reported 9-methoxystrobilurin K. Antifungal activities of the synthesized compounds toward several typical fungi were also examined, and they were less active than 9-methoxystrobilurin K.

Restraint stress elevates the plasma interleukin-6 levels in germ-free mice

Several recent reports demonstrated that restraint stress elevates plasma IL-6 levels; however, the precise mechanism whereby stress stimuli trigger the production of IL-6 remains to be clarified. In this study, in order to elucidate whether or not the intestinal microflora contribute to the stress-induced IL-6 elevation, the plasma IL-6 response of germ-free (GF) mice, which are indeed devoid of indigenous microflora, was compared to that of specific pathogen-free (SPF) mice. The plasma IL-6 level increased after 1 h of restraint stress and thereafter gradually decreased in GF mice as well as in SPF mice. In addition, such a stress-induced IL-6 elevation was also found in the mice reconstituted with SPF feces. The expression levels of IL-6 mRNA in the liver increased after 1 h of stress in both GF and SPF mice based on the findings of a semiquantitative RT-PCR method, although no such increase was observed in the spleen and kidney of both groups of mice. These results thus indicate that restraint stress is capable of elevating the plasma IL-6 levels independently of the intestinal microflora and the liver is one of the main sources responsible for the increased plasma IL-6 during stress.

Role of nitric oxide synthase type 2 in acute infection with murine cytomegalovirus

Whether or not NO plays a critical role in murine CMV (MCMV) infection has yet to be elucidated. In this study, we examined the role of NO in acute infection with MCMV using NO synthase type 2 (NOS2)-deficient mice. NOS2(-/-) mice were more susceptible to lethal infection with MCMV than NOS2(+/+) mice and generated a much higher peak virus titer in the salivary gland after acute infection. A moderate increase in the MCMV titer was also observed in other organs of NOS2(-/-) mice such as the spleen, lung, and liver. The immune responses to MCMV infection including NK cell cytotoxicity and CTL response in NOS2(-/-) mice were comparable with those of NOS2(+/+) mice. Moreover, the ability to produce IFN-gamma is not impaired in NOS2(-/-) mice after MCMV infection. The peritoneal macrophages from NOS2(-/-) mice, however, exhibited a lower antiviral activity than those from NOS2(+/+) mice, resulting in an enhanced viral replication in macrophages themselves. Treatment of these cells from NOS2(+/+) mice with a selective NOS2 inhibitor decreased the antiviral activity to a level below that obtained with NOS2(-/-) mice. In addition, the absence of NOS2 and NOS2-mediated antiviral activity of macrophages resulted in not only an enhanced MCMV replication and a high mortality but also a consequent risk of the latency. It was thus concluded that the NOS2-mediated antiviral activity of macrophages via NO plays a protective role against MCMV infection at an early and late stage of the infection.