Eitaro Hiejima

Reduced numbers and proapoptotic features of mucosal-associated invariant T cells as a characteristic finding in patients with inflammatory bowel disease

Background:Mucosal-associated invariant T (MAIT) cells are innate-like T cells involved in the homeostasis of mucosal immunity; however, their role in inflammatory bowel disease (IBD) is unclear. Methods:Flow cytometry was used to enumerate peripheral blood MAIT cells in 88 patients with ulcerative colitis (UC), 68 with Crohns disease (CD), and in 57 healthy controls. Immunohistochemistry identified MAIT cells in intestinal tissue samples from patients with UC (n = 5) and CD (n = 10), and in control colon (n = 5) and small intestine (n = 9) samples. In addition, expression of activated caspases by MAIT cells in the peripheral blood of 14 patients with UC and 15 patients with CD, and 16 healthy controls was examined. Results:Peripheral blood analysis revealed that patients with IBD had significantly fewer MAIT cells than healthy controls (P < 0.0001). The number of MAIT cells in the inflamed intestinal mucosae of patients with UC and CD was also lower than that in control mucosae (P = 0.0079 and 0.041, respectively). The number of activated caspase-expressing MAIT cells in the peripheral blood of patients with UC and CD was higher than that in healthy controls (P = 0.0061 and 0.0075, respectively), suggesting that the reduced MAIT cell numbers in IBD are associated with an increased level of apoptosis among these cells. Conclusions:The number of MAIT cells in the peripheral blood and inflamed mucosae of patients with UC and CD was lower than that in non-IBD controls. Also, MAIT cells from patients with IBD exhibited proapoptotic features. These data suggest the pathological involvement and the potential for therapeutic manipulation of these cells in patients with IBD.

Utility of Simplified Criteria for the Diagnosis of Autoimmune Hepatitis in Children

Background and Aim: Although the diagnostic scoring system of autoimmune hepatitis (AIH) has been used, these criteria are intended mainly as research tools and are complicated to apply. To resolve these difficulties and allow quick diagnosis, a simplified scoring system was proposed in 2007. We retrospectively compared the simplified AIH scoring system with the 1999 revised original AIH scoring system in children. Patients and Methods: Twenty children (boys/girls 10/10, age 1–15 years, mean age ± SD 8.4 ± 4.4 years) who were diagnosed with AIH based on clinical, biochemical, immunological, and histological data were enrolled in this study. In addition, 36 children with non-AIH liver diseases (boys/girls 22/14, age 1–16 years, mean age ± SD 7.8 ± 4.4 years) were available for evaluation of both the simplified and the 1999 revised scoring system. Results: The sensitivity and specificity of the 1999 revised scoring system were 100% and 81%, respectively. In contrast, the sensitivity and specificity of the simplified scoring system were 55% and 86%, respectively. Of the 20 children with AIH, 9 (45%) were classified as not having AIH using the simplified scoring system. Of the 9 children, 2 and 7 were classified as having definite AIH and probable AIH using the 1999 revised scoring system, respectively. All 5 children with primary sclerosing cholangitis were graded as having AIH using the simplified AIH criteria and the 1999 revised criteria. Conclusions: Although the simplified AIH scoring system has low sensitivity for the diagnosis of AIH in children, the specificity of the simplified AIH scoring system is high. However, the simplified AIH scoring system could not differentiate between AIH and primary sclerosing cholangitis. Therefore, the simplified AIH scoring system does not seem to be a reliable diagnostic tool in children.

Source of transmission in children with chronic hepatitis B infection after the implementation of a strategy for prevention in those at high risk

Aim:  In order to clarify the sources of chronic HBV (hepatitis B virus) infection in children after the implementation of an “at‐risk” strategy in Japan, chronically infected children were assessed. In addition, chronically infected children born to HBsAg‐negative mothers and their family members were assessed to identify the sources of HBV transmission.

Laboratory parameters identify familial haemophagocytic lymphohistiocytosis from other forms of paediatric haemophagocytosis

Haemophagocytic lymphohistiocytosis (HLH) is a life‐threatening syndrome of immune dysregulation and is classified as primary or secondary according to the underlying aetiology. The treatment strategies recommended for these two groups differ substantially; however, it is thought to be impossible to predict the underlying causes of HLH using conventional laboratory tests. Recent studies show that serum levels of soluble interleukin‐2 receptor (sIL2R) and ferritin are useful for differentiating some forms of HLH. The present study reports that combinations of common laboratory parameters, such as the percentage of total lymphocytes within the peripheral blood leucocyte population, serum levels of lactate dehydrogenase and the sIL2R/ferritin ratio, are useful for identifying patients with familial haemophagocytic lymphohistiocytosis and for differentiating the underlying aetiology of paediatric HLH during the early course of the disease. These findings suggest that the pathogenesis of HLH differs greatly in terms of innate and adaptive immunity depending on the aetiology and may provide a new approach to unravelling the complex pathophysiology underlying this syndrome.

Cellular immunity in children with successful immunoprophylactic treatment for mother-to-child transmission of hepatitis B virus

BackgroundThe administration of hepatitis B immunoglobulin followed by hepatitis B vaccine can result in a protective efficacy of almost 90% in mother-to-child transmission of hepatitis B virus (HBV). However, little is known about immunity against HBV infection in children after immunoprophylactic treatment. We tried to assess the association between T-cell responses and viremia in children after successful prophylactic treatment.MethodsThirteen children and their 8 HBV carrier mothers (8 families), who were positive for human leukocyte antigen (HLA)-A24, were enrolled in this study. All of the 13 children received immunoprophylactic treatment and became negative for hepatitis B surface antigen (HBsAg) after birth. HBV-specific cytotoxic T lymphocyte (CTL) responses were evaluated using IFNγ - enzyme-linked immunosorbent spot (ELISPOT) and major histocompatibility complex class I peptide pentamer assays. Serum HBV DNA was measured by real-time PCR.ResultsSignificant HBV-specific T-cell responses were detected in 2 (15%) of the 13 children by ELISPOT. However, the frequency of HLA-A24-HBV-specific CTLs was very low in both HBV carrier mothers and children using pentamers. Of the 13 children, 4 (31%) were positive for serum HBV DNA. However, the levels of serum HBV DNA were 100 copies/ml or less. One of the 2 children in whom significant HBV-specific CTL responses were detectable was positive for serum HBV DNA.ConclusionsHBV core and polymerase-specific T-cell responses were detected and a low-dose viremia was observed in children after successful immunoprophylaxis treatment. Although the presence of viremia was not related to HBV-specific T-cell responses, CTLs might play a role in the control of HBV infection in children born to HBsAg-positive mothers after immunoprophylactic treatment.

Fatty liver and anti-oxidant enzyme activities along with peroxisome proliferator-activated receptors γ and α expressions in the liver of Wilson's disease

BACKGROUND The mechanisms of liver damage and steatosis in Wilsons disease (WD) presenting accumulation of copper generating oxidants remain unclear. Recent studies have shown that peroxisome proliferator-activated receptors (PPARs), in particular PPARs α and γ, regulate fat content of the liver together with the anti-oxidant and anti-inflammation systems. However, such PPARs have never been studied in WD. METHODS We examined PPARs along with the liver damage and steatosis of WD using liver specimens from affected patients exhibiting mild liver damage (group I, n = 5), moderate or greater liver damage (group II, n = 10) and fulminant hepatic failure (group III, n = 5), and from asymptomatic carriers (group H, n = 4). RESULTS PPAR α expression was increased over the control levels in groups H and I but was decreased in groups II and III in parallel with the progression of liver damage (group H = I>II>III). PPAR γ expression was inversely increased (group H<I<II<III). Mn-dependent superoxide dismutase (Mn-SOD), CuZn-SOD, and catalase activities were decreased in the affected three groups, and were increased in group H. Among group II exhibiting substantial inter-individual variances in parameters, the severity of steatosis showed a significant positive correlation with PPAR γ expression (p<0.001) but not PPAR α expression. CuZn-SOD activity was positively correlated with PPARα expression (p<0.05) but not PPAR γ expression. CONCLUSION These results suggest that changes of PPARs γ and α are associated with the steatosis and the impairment of anti-oxidant system in the liver of WD.

Exon skipping causes atypical phenotypes associated with a loss-of-function mutation in FLNA by restoring its protein function

Loss-of-function mutations in filamin A (FLNA) cause an X-linked dominant disorder with multiple organ involvement. Affected females present with periventricular nodular heterotopia (PVNH), cardiovascular complications, thrombocytopenia and Ehlers–Danlos syndrome. These mutations are typically lethal to males, and rare male survivors suffer from failure to thrive, PVNH, and severe cardiovascular and gastrointestinal complications. Here we report two surviving male siblings with a loss-of-function mutation in FLNA. They presented with multiple complications, including valvulopathy, intestinal malrotation and chronic intestinal pseudo-obstruction (CIPO). However, these siblings had atypical clinical courses, such as a lack of PVNH and a spontaneous improvement of CIPO. Trio-based whole-exome sequencing revealed a 4-bp deletion in exon 40 that was predicted to cause a lethal premature protein truncation. However, molecular investigations revealed that the mutation induced in-frame skipping of the mutated exon, which led to the translation of a mutant FLNA missing an internal region of 41 amino acids. Functional analyses of the mutant protein suggested that its binding affinity to integrin, as well as its capacity to induce focal adhesions, were comparable to those of the wild-type protein. These results suggested that exon skipping of FLNA partially restored its protein function, which could contribute to amelioration of the siblings’ clinical courses. This study expands the diversity of the phenotypes associated with loss-of-function mutations in FLNA.

Haploinsufficiency of A20 causes autoinflammatory and autoimmune disorders

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Diagnostic accuracy of endoscopic features of pediatric acute gastrointestinal graft‐versus‐host disease

Acute gastrointestinal graft‐versus‐host disease (GI‐GVHD) is a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HSCT). There are very few studies on specific endoscopic findings in pediatric acute GI‐GVHD. The aim of this retrospective case–control study was to elucidate the characteristic endoscopic findings in pediatric acute GI‐GVHD that improve the diagnostic accuracy of endoscopy.

A CD57+ CTL Degranulation Assay Effectively Identifies Familial Hemophagocytic Lymphohistiocytosis Type 3 Patients

PurposeFamilial hemophagocytic lymphohistiocytosis type 3 (FHL3) is a genetic disorder that results in immune dysregulation. It requires prompt and accurate diagnosis. A natural killer (NK) cell degranulation assay is often used to screen for FHL3 patients. However, we recently encountered two cases of late-onset FHL3 carrying novel UNC13D missense mutations: in these cases, the degranulation assays using freshly isolated and interleukin (IL)-2-activated NK cells yielded contradictory results. Since the defective degranulation of CD57+ cytotoxic T lymphocytes (CTLs) in these cases was helpful for making the diagnosis, we assessed whether the CD57+ CTL degranulation assay more effectively identified FHL3 patients than the NK cell assays.MethodsForty additional patients with hemophagocytic lymphohistiocytosis were prospectively screened for FHL3 by measuring the perforin expression in NK cells and the expression of Munc13-4, syntaxin-11, and Munc18-2 in platelets and by performing NK cell and CTL degranulation assays. The results were confirmed by genetic analysis.ResultsThe freshly isolated NK cell degranulation assay detected FHL3 patients with high sensitivity (100%) but low specificity (71%). The IL-2-stimulated NK cell assay had improved specificity, but 3 out of the 31 non-FHL3 patients still showed degranulation below the threshold level. The CD57+ CTL degranulation assay identified FHL3 patients with high sensitivity and specificity (both 100%).ConclusionsThe CD57+ CTL degranulation assay more effectively identified FHL3 patients than the NK cell-based assays.