Yusei Ohshima

Maturation of human neonatal CD4+ and CD8+ T lymphocytes into Th1/Th2 effectors

The increased susceptibility of neonates to infections has been ascribed to the immaturity of their immune system. More particularly, T cell-dependent responses were shown to be biased towards a Th2 phenotype. Our studies on the in vitro maturation of umbilical cord blood T cells suggest that the Th2 bias of neonatal response cannot be simply ascribed to intrinsic properties of neonatal T cells. Phenotypically, neonatal CD4+ T cells are more immature than their adult CD45RO-/RA+ naive counterparts and they contain a subset (10-20%) of CD45RO-/RA+ CD31- cells which is very low in adults and displays some unique functional features. The activation and maturation of neonatal CD4+ T cells is particularly dependent upon the strength of CD28-mediated cosignal which dictates not only the cytokine profile released upon primary activation but also the response to IL-12. Activation of adult as well as neonatal CD4+ T cells in the context of low CD28 costimulation yields to the production of low levels of only one cytokine, i.e. IL-2. In contrast, strong CD28 costimulation supports the production of high levels of type 1 (IL-2, IFN gamma and TNF beta) and low levels of type 2 (IL-4 and IL-13) cytokines by neonatal T cells. The low levels of naive T cell-derived IL-4 are sufficient to support their development into high IL-4/IL-5 producers by an autocrine pathway. The ability of IL-12 to prime neonatal CD4+ T cells for increased production of IL-4 (in addition to IFN gamma) is observed only when CD28 cosignal is minimal. Under optimal activation conditions (i.e. with anti-CD3/B7.1 or allogenic dendritic cells) the response and the maturation of neonatal and adult naive T cells are similar. Thus the Th2 bias of neonatal immune response cannot be simply ascribed to obvious intrinsic T cell defect but rather to particular conditions of Ag presentation at priming. Unlike CD4+ T cells, neonatal CD8+ T cells strictly require exogenous IL-4 to develop into IL-4/IL-5 producers. Most importantly, anti-CD3/B7-activated neonatal CD8 T cells coexpress CD4 as well as CCR5 and CXCR4 and are susceptible to HIV-1 infection in vitro.

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.

Aicardi-Goutières Syndrome Is Caused by IFIH1 Mutations

Aicardi-Goutières syndrome (AGS) is a rare, genetically determined early-onset progressive encephalopathy. To date, mutations in six genes have been identified as etiologic for AGS. Our Japanese nationwide AGS survey identified six AGS-affected individuals without a molecular diagnosis; we performed whole-exome sequencing on three of these individuals. After removal of the common polymorphisms found in SNP databases, we were able to identify IFIH1 heterozygous missense mutations in all three. In vitro functional analysis revealed that IFIH1 mutations increased type I interferon production, and the transcription of interferon-stimulated genes were elevated. IFIH1 encodes MDA5, and mutant MDA5 lacked ligand-specific responsiveness, similarly to the dominant Ifih1 mutation responsible for the SLE mouse model that results in type I interferon overproduction. This study suggests that the IFIH1 mutations are responsible for the AGS phenotype due to an excessive production of type I interferon.

Early sensitization to house dust mite is a major risk factor for subsequent development of bronchial asthma in Japanese infants with atopic dermatitis: results of a 4-year followup study

BACKGROUND Bronchial asthma (BA) often develops in children with atopic dermatitis (AD). Identification of factors that could predict the development of asthma in children with AD is useful for early intervention. OBJECTIVE We undertook a 4-year followup study to clarify the factors involved in the development of BA in infants with AD. METHODS We registered 169 infants with AD who were free of BA at registration and examined the prevalence and characteristics of the subsequent development of BA among these patients. RESULTS Among the patients followed for 4 years, approximately 45% experienced asthma-like respiratory symptoms, and 35% were diagnosed as asthmatic patients by pediatric allergologists. Patients who developed BA showed early appearance of house dust mite (HDM)-specific immunoglobulin E (IgE) and persistently high levels of food-specific IgE. Male sex, a positive family history of BA, and the appearance of HDM-specific IgE were identified as significant risk factors for the early development of BA, but the significance of these parameters decreased thereafter. A positive family history of AD, the outcome of skin lesions, and keeping furred pets were also identified as risk factors in a part of the followup period. Among the parameters examined, the early appearance of HDM-specific IgE was the most significant risk factor. CONCLUSION Appearance of HDM-specific IgE antibodies in early childhood, which seems to be mainly influenced by genetic factors, is a major risk factor for the subsequent development of BA in children with AD, but the influence decreases after longer followup.

Dysregulation of IL-13 production by cord blood CD4+ T cells is associated with the subsequent development of atopic disease in infants.

Early intervention strategies in allergic diseases will be dependent on identification of newborns at high risk for later development of atopic disease. In this cohort study of 106 neonates, we investigated whether cytokine production property and responsiveness to IL-12 of neonatal CD4+ T cells were associated with the subsequent development of atopic disease and whether a skewed cytokine production property was intrinsic to helper T cells. To exclude the effects of contaminating cells, highly purified cord blood CD4+ T cells were stimulated with anti-CD3 MAb and recombinant B7-2 molecule in the presence or absence of IL-12. Production of IL-13 and interferon-γ was determined by ELISA. The infants were assessed at 12 mo for the development of atopic diseases. CD4+ T cells of neonates who manifested allergic symptoms (atopic group) produced higher levels of IL-13 compared with those of the nonatopic group in both the presence and absence of IL-12. No significant difference was noted between the two groups with respect to interferon-γ production. Moreover, higher IL-13 production was also observed in neonates with chronic eczema than those with short-term eczema. Our data suggest that increased production of IL-13 by neonatal CD4+ T cells is a useful marker of newborns at high risk for subsequent development of atopic diseases and that an intrinsic abnormality of CD4+ T cell is associated with the pathogeneses of atopic disease, especially atopic dermatitis in infants.

Bone mineral status in ambulatory pediatric patients on long‐term anti‐epileptic drug therapy

Background : For ambulatory pediatric outpatients, reports of abnormalities of bone metabolism associated with anti‐epileptic drugs are inconsistent and may be difficult to interpret.

Monocyte Chemoattractant Protein-1 Selectively Inhibits the Acquisition of CD40 Ligand-Dependent IL-12-Producing Capacity of Monocyte-Derived Dendritic Cells and Modulates Th1 Immune Response

Accumulating evidence indicates that monocyte chemoattractant protein-1 (MCP-1), a CC chemokine, also displays immunoregulatory functions and may be involved in Th subset differentiation. In this study, we examined the effects of MCP-1 on the cytokine-driven differentiation of monocytes into dendritic cells (DCs), the most potent APCs for naive T cells. We found that DCs generated in the presence of MCP-1 displayed a markedly reduced production of IL-12 in response to CD40 ligand but not in response to Staphylococcus aureus stimulation in the presence or absence of IFN-γ. The production of IL-10, a potent endogenous IL-12 inhibitor, was not affected by MCP-1. Whereas the inhibitory activity of MCP-1 on IL-12 production by monocytes was sensitive to pertussis toxin, its effects on DC differentiation were pertussis toxin resistant. MCP-1 did not affect the surface phenotype and T cell-stimulating activity of DCs, but most interestingly, naive T cells stimulated with MCP-1-primed DCs produced much less IFN-γ but the same levels of IL-13. Taken together, our results indicated that MCP-1 modulates the differentiation of monocytes into DCs and may thereby inhibit Th1 cell development.

A randomized study of two long-course prednisolone regimens for nephrotic syndrome in children

BACKGROUND Long-course prednisolone regimens have been shown to be more effective than short-course regimens in sustaining remission of nephrotic syndrome in children. However, the most beneficial approach among the long-course regimens remains unknown. METHODS Seventy-three children with new-onset nephrotic syndrome were allocated at random to the two long-course regimens and followed up for 2 years. Group A was administered prednisolone at a daily dose of 60 mg/m2 for 6 weeks, followed by an alternate-day dose of 40 mg/m2 for 6 weeks (the long daily regimen). Group B was administered the same daily dose for 4 weeks, followed by an alternate-day dose of 60 mg/m2 for 4 weeks, and doses were tapered by 10 mg/m2 every 4 weeks (the long alternate-day regimen). RESULTS Group B had a lower incidence of corticosteroid toxicities than group A during the initial treatment. Kaplan-Meier analysis of the sustained remission rate of the two treatment groups showed a marginally significant difference (P = 0.069) and showed a significant difference when patients were stratified for age of disease onset (P = 0.048). In a subgroup of younger children (<4 years at onset), group B had a greater rate of sustained remission (P < 0.01) and fewer children with frequent relapses (P < 0.05) than group A, whereas in older children (> or =4 years at onset), both groups had similar good sustained remission rates. CONCLUSION These findings collectively indicate that the long alternate-day regimen may be more beneficial, with less corticosteroid toxicities, than the long daily regimen, and children with younger age at disease onset may be susceptible to relapse and especially benefit from the long alternate-day regimen for sustaining remission of the disease.

Transmaternal exposure to bisphenol a modulates the development of oral tolerance

Bisphenol A (BPA) is a representative endocrine disruptor that may have adverse effects on human health. Since the development of oral tolerance during infancy may play an important role in the prevention of food allergies, we examined whether transmaternal exposure to BPA influences the development of oral tolerance. To measure antigen-specific responses, female wild-type mice mated with male ovalbumin (OVA)-specific T-cell receptor transgenic (TCR-tg) mice were fed with BPA during pregnancy and while nursing. OVA was administered to OVA-TCR-tg offspring during their weaning period. Oral administration of both high and low doses of OVA suppressed OVA-specific cell proliferation and cytokine production in both BPA-exposed and nonexposed control mice, but the OVA-mediated suppression was significantly more diminished by the BPA exposure. The accumulation of CD4+CD25+Foxp3+ T cells was diminished in the BPA-exposed offspring. Moreover, after low dose OVA administration, serum OVA-specific IgG1 and IgG2a levels were higher in the BPA-exposed offspring than in nonexposed ones. Taken together, our results indicate that transmaternal exposure to BPA seems to modulate the mechanisms underlying tolerance induction; therefore, BPA may partially interrupt the development of oral tolerance.

Serum levels of interleukin 4 and soluble CD23 in children with allergic disorders

In order to clarify the clinical significance of serum interleukin 4 (IL-4) levels, we measured serum IL-4 concentrations in allergic and non-allergic children using a highly sensitive sandwich ELISA. The limit of detection of the assay was 0.15 pg/ml in serum samples. Serum IL-4 was detected in 96.3% (53/55) of non-allergic controls, in 92.9% (183/197) of allergic children, in 70% (7/10) of cord blood samples and in 86.7% (26/30) of neonates. The IL-4 levels in sera from non-allergic controls were relatively constant during the ages examined and all samples were under 1.5 pg/ml. In allergic children, the serum levels of IL-4 were significantly elevated, particularly at age 13-24 months. The serum levels of IL-4 did not differ in children with different clinical manifestations of allergy, such as bronchial asthma, and atopic dermatitis. The serum level of soluble CD23 (sCD23) showed an age-dependent change in allergic and non-allergic children and was significantly higher in allergic than in non-allergic infants aged 7 to 12 months, but not in other age groups. There was no significant correlation among serum levels of IL-4, sCD23 and IgE.