Functional Immunostimulating DNA Materials: The Rising Stars for Cancer Immunotherapy.

Cancer immunotherapy has risen as a promising method in clinical practice for cancer treatment and DNA-based immune intervention materials, along with DNA nanotechnology, have obtained increasing importance in this field. In this review, various immunostimulating DNA materials are introduced and the mechanisms via which they exerted an immune effect are explained. Then, representative examples in which DNA is used as the leading component for anticancer applications through immune stimulation are provided and their efficacy is evaluated. Finally, the challenges for those materials in clinical applications are discussed and suggestions for possible further research directions are also put forward.

Microsatellite polymorphism in intron 2 of human Toll-like receptor 2 gene is associated with susceptibility to acute pancreatitis in Japan.

This study evaluated the association of the polymorphisms in the Toll-like receptor (TLR)2 and TLR4 genes with acute pancreatitis (AP) in Japan. The numbers of guanine-thymine [(GT)n] repeats in intron 2 of the TLR2 gene were counted in 202 unrelated patients with AP (80 with severe and 122 with mild disease) and in 286 healthy controls, using polymerase chain reaction and Genescan analysis. The alleles were divided into three subclasses: (GT)16 or less as the S allele; between (GT)17 and (GT)22 as the M allele; and (GT)23 or more as the L allele. Asp299Gly and Thr399Ile polymorphisms in the TLR4 gene were examined by polymerase chain reaction-restriction fragment length polymorphism analysis. Patients with AP had more S alleles (p < 0.001; odds ratio = 2.37; 95% confidence interval = 1.78-3.17) and fewer M alleles (p < 0.001; odds ratio = 0.40; 95% confidence interval 0.31-0.52) than did healthy controls. Genotypes SS and SL were more common, whereas MM and ML were less common in patients with AP. In subgroup analyses, the genotypes including S alleles were more common in patients with severe AP than in controls. No Asp299Gly and Thr399Ile polymorphisms were detected. In conclusion, microsatellite polymorphism in intron 2 of the TLR2 gene was associated with susceptibility to AP and its severity in Japan.

TNF gene polymorphisms in Graves' disease: TNF-308 A/G meta-analysis.

Autoimmune thyroid diseases (AITDs), including Graves' disease (GD) and Hashimoto thyroiditis, are associated with human MHC polymorphisms. The present study analysed two polymorphisms within tumour necrosis factor (TNF) genes (TNF-308 A/G SNP and TNFb (CT)n microsatellite) in a sample of 106 GD patients and 199 controls from the Tunisian population. The present study was designed to investigate genetic association of these polymorphisms (taken separately or considered as a haplotype) with GD development. Statistical analysis confirmed the association between the TNF-308 A allele and GD (p = 0.002), previously reported in a Tunisian familial study. The data from the present study suggest that the TNF-308 A allele plays a role in GD pathogenesis in the Tunisian population. This association was further confirmed by a meta-analysis on eight published studies (p < 0.0001). Haplotype analysis with GD revealed an associated haplotype (TNFb3-TNF-308 G haplotype: chi2 = 13.16; p = 0.0003).

Dinucleotide repeat polymorphism in intron II of human Toll-like receptor 2 gene and susceptibility to rheumatoid arthritis.

Human Toll-like receptors (TLRs) participate in innate immune response and signal the activation of adaptive immunity. The presence of a functional intronic polymorphism consisting of guanine-thymine repeats in TLR2 gene was recently reported. Here, we investigated a dinucleotide repeat polymorphism in intron II of TLR2 in Korean patients with rheumatoid arthritis (RA). The numbers of guanine-thymine [(GT)(n)] repeats in intron II of the TLR 2 gene were counted in 183 patients with RA and in 148 healthy controls, using the gene scanning technique. We classified alleles into two subclasses for further analysis, 12-16 GT repeats (S allele) and 17-28 repeats (L allele). By subgroup analysis, we also examined whether the S allele is associated with the presence of shared epitope (SE), rheumatoid factor (RF), joint erosion and extra-articular complications. S-allele frequency was significantly increased in patients with RA than in healthy controls [30.3% vs. 23.0%, P = 0.03, or 1.46, 95% confidence interval (CI) 1.03-2.07], and genotypes containing S alleles were more frequent in patients with RA than in healthy controls (54.4% vs. 46.5%. P = 0.04, or 1.57, 95% CI 1.01-2.42). A skewed S-allele distribution was not found to be related to the presence of SE. Subgroup analysis showed no genotypic or allele frequency differences between patients with/without RF, joint erosion, or extra-articular complications. Genotype containing shorter GT repeats in intron II of the TLR2 gene may confer susceptibility to RA in Koreans.

Polymorphisms in the IL10 but not in the IL1beta and IL4 genes are associated with inhibitor development in patients with hemophilia A.

The aim of the Malmö International Brother Study (MIBS) is to evaluate host genetic factors associated with the development of inhibitory antibodies in patients with hemophilia. Factor VIII gene mutations and genetic polymorphisms of the IL1beta, IL4, and IL10 genes, known to influence antibody production in autoimmune diseases, were analyzed in 164 patients (124 with severe, 26 with moderate, and 14 with mild disease) in 78 unrelated families with hemophilia A. Seventy-seven (47%) patients in 54 families had a history of inhibitors (57 high responding, 20 low responding). Inversions were found in 36 families (75 patients). There was no association between the development of inhibitor and the IL1beta Taq I RFLP alleles in exon 5 or the -590 C/T single nucleotide polymorphism (SNP) in the promoter region of IL4. There was, however, a strong association between an allele with 134 bp in one of the CA repeat microsatellites, IL10G, located in the promoter region of the IL10 gene, and the development of inhibitor (odds ratio [OR], 4.4; 95% confidence interval [95% CI], 2.1-9.5; P < .001). The association was consistent in the subgroup of families with severe hemophilia and inversions. IL10 is the first gene located outside the causative factor VIII gene mutation to be associated with inhibitor development.

Linkage and association studies of STAT6 gene polymorphisms and allergic diseases.

BACKGROUND: Signal transducer and activator of transcription 6 (STAT6) is a key transcription factor involved in both interleukin-4 (IL-4) and IL-13-mediated biological responses, such as allergies. Recently, we reported that the polymorphism of the STAT6 gene exon 1 was associated with allergic diseases, while another group studied the G2964A variant of the STAT6 gene's association with atopic asthma. We undertook an association study between these variants of the STAT6 gene and allergic diseases, including atopic dermatitis, bronchial asthma, and food-related anaphylaxis in a Japanese population. METHODS: STAT6 gene polymorphisms were genotyped by polymerase chain reaction (PCR) fragment length polymorphism analysis, and PCR-SSCP analysis in 106 allergic and 66 control subjects. RESULTS: The 2964A variant was in significant linkage disequilibrium with the dinucleotide repeat polymorphism, the 13-GT repeat allele of STAT6 exon 1 (p < 0.0000000003). There was no association between the STAT6 2964A variant and allergic subjects in a Japanese population (p = 0.2724). The genotype of 13/15-GT repeat allele heterozygosity was significantly associated with allergic subjects (p = 0.0006), as previously reported. In one major genotype of the STAT6 exon 1 (15 GT repeat homozygosity), wild-type 2964G allele homozygosity was significantly associated with allergic subjects (p = 0.0382). CONCLUSIONS: Our findings indicate that in combination the dinucleotide repeat polymorphism of the STAT6 exon 1 gene and the 2964A variant may be useful markers for predicting allergic diseases in a Japanese population.

Crucial role of DNA methylation in determination of clonally distributed killer cell Ig-like receptor expression patterns in NK cells.

Human NK cells are characterized by the expression of surface receptors of the killer cell Ig-like receptor (KIR) family, which are involved in the specific recognition of pathogenic target cells. Each NK cell expresses and maintains an individual subset of inhibitory and stimulatory KIR and in this way contributes to a diversified NK cell repertoire. To date, the molecular basis for generation of clonally distributed KIR expression patterns has been elusive. Here, analyses of DNA methylation patterns of KIR genes in NK cell lines as well as in NK cells, freshly isolated from peripheral blood, demonstrated that a small CpG island surrounding the transcriptional start site of each KIR gene is consistently demethylated in expressed KIR and methylated in unexpressed KIR. DNA-demethylating treatment resulted in a rapid and stable induction of transcription and cell surface expression of all formerly unexpressed KIR in NK cell lines, NK cell clones, and freshly isolated NK cells, but not in other cell types. In vitro methylation of KIR CpG islands repressed reporter gene expression in NK cells. We conclude that clonal patterns of KIR expression are mainly epigenetically determined and maintained through DNA methylation.

Differential patterns of methylation of the IFN-gamma promoter at CpG and non-CpG sites underlie differences in IFN-gamma gene expression between human neonatal and adult CD45RO- T cells.

IFN-gamma is a potent pleiotropic Th1 cytokine, the production of which is tightly regulated during fetal development. Negative control of fetal/neonatal IFN-gamma production is generally attributed to the Th1-antagonistic effect of mediators produced by the placenta, but evidence exists of additional and more direct transcriptional regulation. We report that neonatal (cord blood) CD3(+)/CD45RO(-) T cells, in particular the CD4(+)/CD45RO(-) subset, are hypermethylated at CpG and non-CpG (CpA and CpT) sites within and adjacent to the IFN-gamma promoter. In contrast, CpG methylation patterns in cord blood IFN-gamma-producing CD8(+)/CD45RO(-) T cells and CD56(+)/CD16(+)/CD3(-) NK cells did not differ significantly from those in their adult counterparts. Consistent with this finding, IFN-gamma production by stimulated naive cord blood CD4(+) T cells is reduced 5- to 10-fold relative to adult CD4(+) T cells, whereas production levels in neonatal and adult CD8(+) T cells are of a similar order. Evidence of significant CpA and CpT methylation was not discovered in promoter sequence from other cytokines (IL-4, TNF-alpha, or IFN-gammaR alpha-chain). We additionally demonstrate that overexpression of DNA methyltransferase 3a in embryonic kidney carcinoma cells is accompanied by CpA methylation of the IFN-gamma promoter.

Bob1 (OCA-B/OBF-1) differential transactivation of the B cell-specific B29 (Ig beta) and mb-1 (Ig alpha) promoters.

The B29 (Igbeta) and mb-1 (Igalpha) gene products are B cell-specific essential components of the B cell receptor that are coexpressed at all stages of B cell differentiation, with the exception of plasma cells, which lack mb-1 expression. Transcription of both genes is governed by a similar cassette of interactive transcription factor-binding elements, including octamer motifs, in TATA-less promoters. In this study, we show the B cell-specific B29 gene promoter is transactivated in B and non-B cells by cotransfection with the B cell-specific octamer cofactor gene, Bob1 (OCA-B/OBF-1). The expression of Bob1 is also sufficient to override the silencing effects of the B29 silencer. This indicates that Bob1 plays a critical role in B cell-specific B29 promoter expression. In contrast, coexpression of Bob1 had no effect on mb-1 promoter activity. Bob1 transactivation only occurs with select octamer sequences that have an adenosine at position 5 (ATGCAAAT). The B29 promoter conforms to this consensus octamer motif, while the mb-1 promoter octamer motif does not. Octamer motif swapping between B29 and mb-1 promoters renders B29 unresponsive to Bob1 transactivation and makes mb-1 competent for Bob1 transactivation, thereby indicating that the B29 octamer motif is solely responsible for Bob1 interaction. Additionally, the mb-1 construct containing the B29 octamer motif is expressed in a plasmacytoma cell line, while the wild-type mb-1 promoter is not. Bob1 transactivation of B29 and the lack of this transactivation of mb-1 account for the differential expression of B29 and mb-1 in terminally differentiated plasma cells.

Interferon-gamma polymorphisms in systemic lupus erythematosus.

Interferon-gamma is a cytokine which is believed to play a role in both the susceptibility and pathogenesis of lupus. To determine whether genetic variants might influence the development of this polygenic autoimmune disease, we analyzed the gene frequency of eight different alleles in controls and patients with SLE. Ninety-nine controls and 136 patients with systemic lupus erythematosus were genotyped for a CA repeat in the first intron of the interferon-gamma gene. There were no statistically significant differences in the allele frequencies between patients and controls suggesting that these polymorphic variants do not influence susceptibility. We then examined whether any of these alleles were associated with specific clinical manifestations. Allele 1 was associated with gastrointestinal lupus while allele 6 was associated with more severe lupus. Allele 2 appeared to be protective for arthritis. This suggests that genetic variation in interferon-gamma expression might influence the disease course.

Response of porcine peripheral blood mononuclear cells to CpG-containing oligodeoxynucleotides.

Exposure to bacterial DNA generates a "danger signal" that stimulates cellular elements of the mammalian immune system to proliferate and/or secrete cytokines. Stimulation is critically dependent on hexameric motifs that contain an unmethylated CpG dinucleotide: these are commonly found in bacterial but not vertebrate DNA. Different motifs are optimally stimulatory in different species. This work examines whether oligodeoxynucleotides (ODNs) containing CpG motifs stimulate peripheral blood mononuclear cells from pigs. Results show that pigs respond to CpG ODN by proliferating and secreting IL-6, IL-12 and TNF-alpha. By screening a large panel (>100) of ODNs, the palindromic hexamer 'ATCGAT' was identified as being optimally active in all animals examined (N=10). These findings are the first to establish the immunostimulatory activity of CpG ODN in pigs, and suggest that the therapeutic uses envisioned for these ODNs (as vaccine adjuvants and immunoprotective agents) may be applicable to husbandry animals.

Beyond danger: unmethylated CpG dinucleotides and the immunopathogenesis of disease.

Oligonucleotide sequences containing unmethylated cytidine phosphate guanosine (CpG) motifs are known to have significant immunostimulatory properties. Because of these immunostimulatory effects, unmethylated CpG oligonucleotides are thought to act as 'danger signals' that produce a favorable immune response by alerting the host to the presence of invading organisms or abnormal cells. In contrast to this concept, we review the evidence that unmethylated CpG sequences derived either from microbial agents or from endogenous CpG-rich Alu motifs promote disease progression by inducing an aberrant or autoreactive immune response. Recognition of the negative effect of unmethylated CpG dinucleotides should lead to more effective immune strategies to combat infectious, inflammatory, autoimmune and malignant diseases.

CA repeat allele polymorphism in the first intron of the human interferon-gamma gene is associated with lung allograft fibrosis.

Interferon-gamma (IFN-gamma) is an inflammatory cytokine that has been implicated in the development of fibrosis in inflamed tissues. In this study we have analysed the association between genetically-determined high IFN-gamma production and development of fibrosis in lung transplants. The human IFN-gamma gene has a variable length CA repeat in the first intron. Our previous study showed that polymorphism of this microsatellite is associated with individual variation in the levels of IFN-gamma production. In vitro production of IFN-gamma showed significant correlation with presence of allele #2 (p < 0.01). In this study allele #2 was found to be associated with allograft fibrosis defined by transbronchial biopsy. An analysis of two groups of lung transplant recipients showed a significant increase in the frequency of allele #2 in the group which developed fibrosis after transplantation compared to the group that did not (p < 0.005). We postulate that the production of IFN-gamma, which is under genetic control, can influence the development of fibrosis in lung allografts.

Novel compound tetra-, dinucleotide microsatellite polymorphism in the tumor necrosis factor/lymphotoxin locus.

A polymorphic (TGCG)n, tetranucleotide repeat was discovered juxtaposed to the (GT)n dinucleotide repeat that comprises the tumor necrosis factor a microsatellite (TNF) located telomeric to the tumor necrosis factor/lymphotoxin gene cluster. The degree of complexity of this compound tetra-,dinucleotide microsatellite consists of 16 potential alleles of combined length ranging from 24 to 54 bp. The pattern of frequencies of individual alleles belonging to the compound TNFa microsatellite was established from 52 healthy volunteers and was found to be highly heterogeneous. The data diverges significantly from previously published statistics that recognized only a simple variable dinucleotide tandem repeat. The newly recognized compound tetra-, dinucleotide TNFa microsatellite polymorphism establishes a more accurate genetic basis to explore potential linkage with disease susceptibility genes located within this region of the class III major histocompatibility complex. In addition, variable tumor necrosis factor and lymphotoxin production may reflect the more complex polymorphic nature of this microsatellite region. Finally, compound microsatellites probably exist elsewhere, throughout the human genome. Recognition of their presence may have a considerable impact on the validity of past and future microsatellite-based genetic analyses.

Human CD8+ T cell responses to EBV EBNA1: HLA class I presentation of the (Gly-Ala)-containing protein requires exogenous processing.

Epstein-Barr virus (EBV)-induced cytotoxic T lymphocyte (CTL) responses have been detected against many EBV antigens but not the nuclear antigen EBNA1; this has been attributed to the presence of a glycine-alanine repeat (GAr) domain in the protein. Here we describe the isolation of human CD8+ CTL clones recognizing EBNA1-specific peptides in the context of HLA-B35.01 and HLA-A2.03. Using these clones, we show that full-length EBNA1 is not presented when expressed endogenously in target cells, whereas the GAr-deleted form is presented efficiently. However, when supplied as an exogenous antigen, the full-length protein can be presented on HLA class I molecules by a TAP-independent pathway; this may explain how EBNA1-specific CTLs are primed in vivo.