The Suppressive Effect of Butyrate and Bromopyruvate on Inflammatory Cytokine Production and Short Chain Fatty Acid Receptor Expression by Blood Mononuclear Cells in Patients with Behçet's Disease

BACKGROUND: Controlling inflammation is a therapeutic goal of various autoimmune/autoinflammatory diseases including Behçet's disease (BD). The immunomodulatory effect of metabolites or metabolic analogs such as butyrate and 3-bromopyruvate has been observed in animal disease models. OBJECTIVE: We attempted to evaluate the effect of butyrate and 3-bromopyruvate on the inflammatory cytokine production by peripheral blood mononuclear cells (PBMCs) isolated from patients with mucocutaneous involvement of BD. METHODS: PBMCs isolated from 11 patients with BD and 10 healthy controls were stimulated with lipopolysaccharide in the presence of butyrate or 3-bromopyruvate. Butyrate receptor and cytokine messenger ribonucleic acid (mRNA) expression was analyzed by real-time reverse transcription polymerase chain reaction. Cytokine secretion was assessed by enzyme-linked immunosorbent assay. PBMCs survival was analyzed by flow cytometry. RESULTS: Bromopyruvate or butyrate treatment suppressed inflammatory cytokine production in PBMCs from all our subjects. Bromopyruvate also reduced PBMCs survival while butyrate did not. As the effect of butyrate was slightly greater in BD patients than in healthy controls, we analyzed butyrate receptor expression and found that lipopolysaccharide-induced free fatty acid receptor 2 mRNA level in PBMCs was higher in BD patients than in controls. CONCLUSION: We propose bromopyruvate and butyrate as supplementary therapeutic candidates to control inflammation in patients with BD.

Transcription Factors Regulating Inflammatory Cytokine Production Are Differentially Expressed in Peripheral Blood Mononuclear Cells of Behçet Disease Depending on Disease Activity

BACKGROUND: Behçet disease (BD) is a relapsing inflammatory disease with increased production of inflammatory cytokines in peripheral blood mononuclear cells (PBMCs); however, the underlying molecular mechanisms are not well known. OBJECTIVE: To analyze whether the differential expression of transcription factors is involved in the increased tumor necrosis factor (TNF)-α and interleukin (IL)-6 production by PBMCs of BD patients compared to healthy controls (HCs). METHODS: Expression of transcription factors was examined by real-time reverse transcriptase-polymerase chain reaction and western blotting. Cytokine production by CD11b+ cells transfected with siRNAs against transcription factors was measured by enzyme-linked immunosorbent assay. RESULTS: In the absence of lipopolysaccharide stimulation, the transcript level of CCAAT-enhancer-binding proteins (C/EBP) β was increased in PBMCs from patients with active BD compared to that in PBMCs from patients with stable BD. The C/EBPδ transcript level was higher in PBMCs from patients with active BD than in those from HCs. The activating transcription factor 3 (ATF3) transcript level was increased in PBMCs from patients with stable BD compared to that in PBMCs from HCs. siRNAs targeting C/EBPβ and C/EBPδ significantly reduced the production of IL-6 and TNF-α in lipopolysaccharide-stimulated CD11b+ cells from patients with BD as well as from HCs. CONCLUSION: We found differential expression of C/EBPβ, C/EBPδ, and ATF3 in PBMCs from patients with BD depending on disease activity, indicating the involvement of these molecules in BD pathogenesis.

RNA Granules and Stress Granules in Virus Systems

Viruses initiate a number of cellular stress responses and modulate gene regulation and compartmentalization of RNA upon infection to be successful parasites. Virus infections may induce or impair stress granule (SG) formation to maximize replication efficiency. SGs and processing bodies (PBs) are the RNA granules, which contain translationally inactive pool of transcripts as the mRNA silencing foci. PBs and SGs, the highly conserved macromolecular aggregates, can release mRNAs to allow their translations. Unlike constitutively existing PBs that can respond to stimuli and affect mRNA translation and decay, SGs are specifically induced upon cellular stress and can triggers a global translational silencing by several pathways, including phosphorylation of the key translation initiation factor eIF2alpha, tRNA cleavage, and sequestration of cellular components and so on. The dynamics of PBs and SGs are regulated by several signaling pathways, including histone deacetylase 6, and depend on microfilaments and microtubules, and the cognate molecular motors myosin, dynein, and kinesin. SGs share features with aggresomes and related aggregates of unfolded proteins and may play a role in the pathology. The recent advances in understanding the relationship between viruses and mRNA stress granules are summarized.

T Cell Immunoglobulin Mucin Domain (TIM)-3 Promoter Activity in a Human Mast Cell Line

T cell immunoglobulin mucin domain (TIM)-3 is an immunomodulatory molecule and upregulated in T cells by several cytokines. TIM-3 also influences mast cell function but its transcriptional regulation in mast cells has not been clarified. Therefore, we examined the transcript level and the promoter activity of TIM-3 in mast cells. The TIM-3 transcript level was assessed by real-time RT-PCR and promoter activity by luciferase reporter assay. TIM-3 mRNA levels were increased in HMC-1, a human mast cell line by TGF-beta1 stimulation but not by stimulation with interferon (IFN)-alpha, IFN-lambda, TNF-alpha, or IL-10. TIM-3 promoter -349~+144 bp region relative to the transcription start site was crucial for the basal and TGF-beta1-induced TIM-3 promoter activities in HMC-1 cells. TIM-3 promoter activity was increased by overexpression of Smad2 and Smad4, downstream molecules of TGF-beta1 signaling. Our results localize TIM-3 promoter activity to the region spanning -349 to +144 bp in resting and TGF-beta1 stimulated mast cells.

Identification of CCL1 as a Gene Differentially Expressed in CD4+ T Cells Expressing TIM-3

BACKGROUND: T cell immunoglobulin mucin containing molecule (TIM)-3 is expressed in differentiated Th1 cells and is involved in the suppression of the cytokine production by these cells. However, the regulation of the expression of other T cell genes by TIM-3 is unclear. Herein, we attempted to identify differentially expressed genes in cells abundantly expressing TIM-3 compared to cells with low expression of TIM-3. METHODS: TIM-3 overexpressing cell clones were established by transfection of Jurkat T cells with TIM-3 expression vector. For screening of differentially expressed genes, gene fishing technology based on reverse transcription-polymerase chain reaction (RT-PCR) using an annealing control primer system was used. The selected candidate genes were validated by semi quantitative and real-time RT-PCR. RESULTS: The transcription of TIMP-1, IFITM1, PAR3 and CCL1 was different between TIM-3 overexpressing cells and control cells. However, only CCL1 transcription was significantly different in cells transiently transfected with TIM3 expression vector compared with control cells. CCL1 transcription was increased in primary human CD4+ T cells abundantly expressing TIM-3 but not in cells with low expression of TIM-3. CONCLUSION: CCL1 was identified as a differentially transcribed gene in TIM-3-expressing CD4+ T cells.

Expression of Hepatitis B Virus X Protein in Hepatocytes Suppresses CD8+ T Cell Activity

BACKGROUND: CD8+ T cells contribute to the clearance of Hepatitis B virus (HBV) infection and an insufficient CD8+ T cell response may be one of the major factors leading to chronic HBV infection. Since the HBx antigen of HBV can up-regulate cellular expression of several immunomodulatory molecules, we hypothesized that HBx expression in hepatocytes might affect CD8+ T cell activity. METHODS: We analyzed the activation and apoptosis of CD8+ T cells co-cultured with primary hepatocytes rendered capable of expressing HBx by recombinant baculovirus infection. RESULTS: Expression of HBx in hepatocytes induced low production of interferon-gamma and apoptosis of CD8+ T cells, with no effect on CD8 T cell proliferation. However, transcriptional levels of H-2K, ICAM-1 and PD-1 ligand did not correlate with HBx expression in hepatocytes. CONCLUSION: Our results suggest that HBx may inhibit CD8+ T cell response by regulation of interferon-gamma production and apoptosis.

The Binding Properties of Glycosylated and Non-Glycosylated Tim-3 Molecules on CD4+CD25+ T Cells

BACKGROUND: T cell immunoglobulin and mucin domain containing 3 protein (Tim-3) expressed on terminally differentiated Th1 cells plays a suppressive role in Th1-mediated immune responses. Recently, it has been shown that N-glycosylation affects the binding activity of the Tim-3-Ig fusion protein to its ligand, galectin-9, but the binding properties of non-glycosylated Tim-3 on CD4+CD25+ T cells has not been fully examined. In this study, we produced recombinant Tim-3-Ig fusion proteins in different cellular sources and its N-glycosylation mutant forms to evaluate their binding activities to CD4+CD25+ T cells. METHODS: We isolated and cloned Tim-3 cDNA from BALB/C mouse splenocytes. Then, we constructed a mammalian expression vector and a prokaryotic expression vector for the Tim-3-Ig fusion protein. Using a site directed mutagenesis method, plasmid vectors for Tim-3-Ig N-glycosylation mutant expression were produced. The recombinant protein was purified by protein A sepharose column chromatography. The binding activity of Tim-3-Ig fusion protein to CD4+CD25+ T cells was analyzed using flow cytometry. RESULTS: We found that the nonglycosylated Tim-3-Ig fusion proteins expressed in bacteria bound to CD4+CD25+ T cells similarly to the glycosylated Tim-3-Ig protein produced in CHO cells. Further, three N-glycosylation mutant forms (N53Q, N100Q, N53/100Q) of Tim-3-Ig showed similar binding activities to those of wild type glycosylated Tim-3-Ig. CONCLUSION: Our results suggest that N-glycosylation of Tim-3 may not affect its binding activity to ligands expressed on CD4+CD25+ T cells.

Secretion of Biologically Active Recombinant Human Granulocyte-Macrophage Colony-Stimulating Factor by Transduced Gastric Cancer Cells

PURPOSE: Gastric cancer has the highest incidence rate among cancers in Asia. The advanced type of signet ring cell carcinoma has poor prognosis compared to other types of gastric cancer. The immuno-gene therapy with cytokine-based tumor vaccines has not yet been investigated for gastric cancer. The granulocyte macrophage colony-stimulating factor (GM-CSF)-based tumor vaccine has been demonstrated as the most potent stimulator for specific and long-lasting systemic tumor immunity. MATERIALS AND METHODS: In the present study, KATO III cells, the human signet ring cell gastric carcinoma cell line, were genetically modified by the transduction with the human GM-CSF cDNA or the modified hGM-CSF in replication-deficient retroviruses. The genomic integrations and mRNA expressions of the transgenes were determined by Southern and Northern blot analyses. RESULTS: Wild type (wt) or modified hGM-CSF was integrated into the genome of KATO III cells. The modified hGM-CSF mRNA was more stable than that of wt. The KATO III cells with the modified hGM-CSF produced higher level of hGM-CSF (12.4-19 ng/10(6)cells/48hrs) than that with wt hGM-CSF, when determined by enzyme-linked immunosorbent assay (ELISA). The secreted recombinant hGM-CSF could support the proliferation of the GM-CSF-dependent cell line, indicating that the hGM-CSF secreted by the transduced KATO III cells has biological activities. Irradiated, transduced KATO III cells continued to secret hGM-CSF without proliferation. CONCLUSION: Our results suggest that GM-CSF secreting KATO III cells could be tested for the treatment of gastric cancer as an allogeneic tumor vaccine as a part of immunotherapeutic treatment.

Intracellular Antibody Fragment Against Hepatitis B Virus X Protein Does Not Inhibit Viral Replication

Replication of the hepatitis B virus is suppressed by deficiency of the X protein. Although several molecules that block cellular targets of X protein reduce the production of hepatitis B virus progeny, the effect of a specific inhibitor of X protein on viral replication has not been investigated. To block X protein specifically, we adopted an intracellular expression approach using H7 single chain variable fragment (H7scFv), an antibody fragment against X protein. We previously demonstrated that cytoplasmic expression of H7scFv inhibits X protein-induced tumorigenicity and transactivation. In this study, intracellular H7scFv expression inhibits reporter gene transactivation but not viral replication determined by endogenous hepatitis B virus polymerase activity assay and real-time PCR. Our findings imply that intracellular expression of antibody fragment against X protein may not be an alternative therapeutic modality for inhibition of hepatitis B virus replication.