Eiko Matsui

Association between interleukin‐18 gene polymorphism 105A/C and asthma

Background IL‐18 has been shown to exert anti‐allergic or allergy‐promoting activities, but the existence of genetic polymorphisms in the coding regions of IL‐18 gene has not been demonstrated.

Reduced IFNγ production in response to IL‐12 stimulation and/or reduced IL‐12 production in atopic patients

Several studies have shown that interleukin (IL)‐4 and interferon‐gamma (IFNγ) are important for the regulation of IgE production and that IL‐12 induces IFNγ.

Leaky phenotype of X-linked agammaglobulinaemia in a Japanese family

X‐linked agammaglobulinaemia (XLA) is an inherited immunodeficiency that is caused by a block in early B‐cell differentiation. Whereas early B precursors in the bone marrow are present in substantial numbers, XLA‐affected individuals have dramatically reduced numbers of circulating mature B cells, plasma cells and immunoglobulins of all isotypes. We report on a Japanese family with 3 XLA patients, in whom the serum immunoglobulin levels and number of B cells showed a significant difference among them in spite of harbouring the same splice donor site mutation in the BTK gene. We developed concise method for detection of this mutation, which is helpful for discovering the carrier. Patient 2 showed a significant serum immunoglobulin levels of all isotypes, including allergen‐specific IgE. Expression of a normal and truncated size BTK gene was detected in patient 2′s peripheral blood mononuclear cells (PBMCs). Expression of BTK protein was also detected in some B cells. These results suggest that the leaky phenotype in patient 2 was caused in part by the expression of a normal BTK gene transcript. The increased frequency of infection with age expanded the number of B cells with normal BTK gene expression and produced the serum immunoglobulin, including IgE.

Atopy and mutations of IL-12 receptor β2 chain gene

Atopy, which is characterized by enhanced IgE responses to environmental antigens, leads to clinical disorders such as asthma, eczema and rhinitis. These atopic disorders develop due to the interactions between genetic and environmental factors. The class switch to IgE and production of IgE in B lymphocytes are regulated by cytokines [1±6]. IL-12 is one of the most important cytokines which down-regulate IgE production. In this paper, the relationship between atopy and aberrant IL-12 signal transduction, particularly mutations in the IL-12 receptor (IL-12R) chain gene is focused upon.

Expression of the BLM gene in human haematopoietic cells

Blooms syndrome (BS) is a rare autosomal recessive disorder characterized by stunted growth, sun‐sensitive erythema and immunodeficiency. Chromosomal abnormalities are often observed. Patients with BS are highly predisposed to cancers. The causative gene for BS has been identified as BLM. The former encodes a protein, which is a homologue of the RecQ DNA helicase family, a family which includes helicases such as Esherichia coli RecQ, yeast Sgs1, and human WRN. WRN is encoded by the gene that when mutated causes Werners syndrome. The function of BLM in DNA replication and repair has not yet been determined, however. To understand the function of BLM in haematopoietic cells and the cause of immunodeficiency in BS, expression of the BLM gene in various human tissues and haematopoietic cell lines was analysed and the involvement of BLM in immunoglobulin rearrangement examined. In contrast to WRN, BLM was expressed strongly in the testis and thymus. B, T, myelomonocytic and megakaryocytic cell lines also expressed BLM. All of the examined sequences at the junction of the variable (V), diversity (D) and joining (J) regions of the immunoglobulin heavy‐chain genes were in‐frame, and N‐region insertions were also present. The frequency of abnormal rearrangements of the T cell receptor was slightly elevated in the peripheral T cells of patients with BS compared with healthy individuals, whereas a higher frequency of abnormal rearrangements was observed in the cells of patients with ataxia‐telangiectasia (A‐T). In DND39 cell lines, the induction of sterile transcription, which is required for class switching of immunoglobulin heavy‐chain constant genes, was correlated with the induction of the BLM gene. Taking into consideration all these results, BLM may not be directly involved in VDJ recombination, but is apparently involved in the maintenance of the stability of DNA.

RNA editing of interleukin‐12 receptor β2, 2451 C‐to‐U (Ala 604 Val) conversion, associated with atopy

Background The production of IgE in B lymphocytes is down‐regulated by IFN‐γ. IL‐12 induces IFN‐γ production by T lymphocytes and natural killer cells by binding to its specific receptor. RNA editing is a post‐transcriptional modification.

Reduced Interferon-γ Production and Mutations of the Interleukin-12 Receptor β2 Chain Gene in Atopic Subjects

Background: The atopic patient has a predisposition to selective synthesis of IgE antibodies to common environmental antigens. IgE production is upregulated by interleukin-4 (IL-4) and downregulated by interferon-γ (IFN-γ). IL-12 is a cytokine that induces IFN-γ production. The signal of IL-12 is transduced through the IL-12 receptor (IL-12R) and Stat4. Methods: We examined IFN-γ production in peripheral blood mononuclear cells (PBMCs) following stimulation with IL-12 or phytohemagglutinin (PHA) in healthy controls and atopic patients. Moreover, sequences of the IL-12R β2 chain gene were analyzed. Results: The serum IgE levels were negatively correlated (p < 0.001) with IFN-γ production. In 24 out of 75 atopic patients, IFN-γ production in PBMCs following stimulation with IL-12 was under the detection limit, but PHA stimulation elicited detectable IFN-γ production. Sequence analysis of the cDNA of IL-12R β2 revealed three kinds of distinct genetic mutations (2496 del 91, 1577 A to G and 2799 A to G) in 10 unrelated subjects of the 24 whose IFN-γ production following IL-12 stimulation was under the detection limit. PBMCs cultured with IL-12 and PHA in these 10 subjects showed decreased tyrosine phosphorylation of Stat4. Conclusions: The results of our study indicate that atopic diseases are caused, in part, by impairment of the IL-12 signal cascade, which downregulates IgE production, and that the mutation of the IL-12R β2 chain gene is one of the causative genes for atopy.

Pharmacogenetics of asthma in children

Allergic diseases such as bronchial asthma and atopic dermatitis develop by a combination of genetic and environmental factors. Several candidate causative genes of asthma and atopy have been reported as the genetic factors. The clinical features of patients and causes of diseases vary. Therefore, personalized medicine (tailor-made medicine) is necessary for the improvement of quality of life (QOL) and for asthma cure. Pharmacogenetics is very important for personalized medicine. Here, we present the genetics and pharmacogenetics of asthma in children. Finally, we show the guideline for personalized medicine for asthma, particularly in childhood, including the pharmacogenetics of anti-asthmatic drugs, preliminarily produced by the authors.

The response of bovine beta-lactoglobulin-specific T-cell clones to single amino acid substitution of T-cell core epitope

Cow’s milk is one of the most common food allergens in the first year of life, with approximately 2.5% of infants experiencing an allergic reaction to it. Beta‐lactoglobulin (BLG) is one of the major allergens in cow’s milk. Previously, we reported that four of six T‐cell clones (TCC) which were established from cow’s milk allergy patients recognized BLGp97‐117 as the core sequence and also recognized BLG in association with the human leucocyte antigen (HLA)‐DRB1*0405 allele. Using two of these four TCCs, we evaluated the T‐cell response to BLG peptides with single amino acid substitution or deletion and identified BLGp102‐112 as the minimum essential region in BLGp97‐117. In the alanine‐scan assay, the proliferative responses of TCCs to pE108A disappeared, and the proliferative responses of TCCs to pC106A decreased. In the analog peptide proliferation assay, pY102S had retained some T‐cell response to the two TCCs. Collecting these results, we propose a motif for the interaction between the HLA‐DRB1*0405 allele and antigen peptide, and suggest that BLGp105‐108 are important residues to retain the TCR/BLG‐peptide/HLA complex. pY102A and pY102S are partial agonists for the T‐cell receptor. These peptides might be considered as candidate peptides for the modification of the T‐cell response to BLG in cow’s milk allergy.

Effects of dioxins on the quantitative levels of immune components in infants

Dioxins (polychlorinated dibenzo-p-dioxin (PCDD)=polychlorinated dibenzofuran (PCDF)) and polychlorinated biphenyls (PCBs) are potentially hazardous compounds and have structural similarity with thyroid hormones. Animal studies have demonstrated that PCDDs, PCDFs and PCBs can alter immune functions. However, in humans it is not yet elucidated whether dioxins contained in breast milk have any effects on the immune functions in infants. To investigate the effects of dioxins on the immune system, we compared the quantitative levels of immune components between a breast-fed group and bottle-fed group, in which dioxin concentration is almost zero. Ratios of immune cells, such as CD4= and CD8= T-lymphocytes, as well as B-lymphocytes (CD19= and/or CD20=) and NK cells (CD16=, CD56=) in peripheral blood lymphocytes, serum immunoglobulin level, and level of specific IgE antibody to allergens in the venous blood at 12 months of age were assessed in a subgroup of 281 infants. The relationship of post-natal dioxin exposure via breast feeding with the ratio of immunological markers and the level of humoral antibodies up to 12 month of age was not demonstrated. In conclusion, it would appear that the content of dioxins in breast milk in the Japanese general population is not enough to induce any change in theses-examined immunological parameters during the first year of life, although long-term effects remain to be evaluated.