Clinical and molecular significance of flow cytometric analysis for reactive oxygen species production and residual p67phox expression in p67phox-deficient chronic granulomatous disease.

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by molecular defects in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. p67phox-CGD is an autosomal recessive CGD, which is caused by a defect in the cytosolic components of NADPH oxidase, p67phox, encoded by NCF2. We previously established a flow cytometric analysis for p67phox expression, which allows accurate assessment of residual protein expression in p67phox-CGD. We evaluated the correlation between oxidase function and p67phox expression, and assessed the relevancy to genotypes and clinical phenotypes in 11 patients with p67phox-CGD. Reactive oxygen species (ROS) production by granulocytes was evaluated using dihydrorhodamine-1,2,3 (DHR) assays. p67phox expression was evaluated in the monocyte population. DHR activity and p67phox expression were significantly correlated (r = 0.718, p < 0.0162). Additionally, DHR activity and p67phox expression were significantly higher in patients carrying one missense variant in combination with one nonsense or frameshift variant in the NCF2 gene than in patients with only null variants. The available clinical parameters of our patients (i.e., age at disease onset, number of infectious episodes, and each infection complication) were not linked with DHR activity or p67phox expression levels. In summary, our flow cytometric analysis revealed a significant correlation between residual ROS production and p67phox expression. More deleterious NCF2 genotypes were associated with lower levels of DHR activity and p67phox expression. DHR assays and protein expression analysis by using flow cytometry may be relevant strategies for predicting the genotypes of p67phox-CGD.

Immune-mediated inflammatory diseases with chronic excess of serum interleukin-18.

Review: Interleukin-18 (IL-18) is a proinflammatory cytokine that promotes various innate immune processes related to infection, inflammation, and autoimmunity. Patients with systemic juvenile idiopathic arthritis and adult-onset Still's disease exhibit chronic excess of serum IL-18, which is associated with a high incidence of macrophage activation syndrome (MAS), although the mechanisms of IL-18 regulation in such diseases remain largely unknown. Similar elevation of serum IL-18 and susceptibility to MAS/hemophagocytic lymphohistiocytosis (HLH) have been reported in monogenic diseases such as X-linked inhibitor of apoptosis deficiency (i.e., X-linked lymphoproliferative syndrome type 2) and NLRC4-associated autoinflammatory disease. Recent advances in molecular and cellular biology allow the identification of other genetic defects such as defects in CDC42, PSTPIP1, and WDR1 that result in high serum IL-18 levels and hyperinflammation. Among these diseases, chronic excess of serum IL-18 appears to be linked with severe hyperinflammation and/or predisposition to MAS/HLH. In this review, we focus on recent findings in inflammatory diseases associated with and probably attributable to chronic excess of serum IL-18 and describe the clinical and therapeutical relevance of understanding the pathology of this group of diseases.

Mesenteric abscess caused by coinfection with Bacillus Calmette-Guérin and Phialemonium sp. in chronic granulomatous disease.

Opportunistic infections are life-threatening conditions in immunocompromised patients including those with primary immunodeficiency. We describe a case of X-linked chronic granulomatous disease presenting with mesenteric abscess caused by a coinfection with Bacillus Calmette-Guérin (BCG) and Phialemonium sp. The patient received BCG vaccination at 5 months old. He developed left axillary BCG lymphadenitis at 17 months of age, and 3 months later mesenteric abscess occurred. Concomitant use of rifampicin and itraconazole at 17 months of age might have reduced serum itraconazole concentrations and led to superinfection with Phialemonium sp. in our patient, which was susceptible to itraconazole and voriconazole in vitro. The patient was successfully treated with a combination of isoniazid, rifampicin, streptomycin, ciprofloxacin, prednisolone, interferon-γ, and an increased dose of itraconazole, followed by hematopoietic stem cell transplantation. Our results suggest that clinician need to be aware of rifampicin drug interactions, and that precise detection and identification of pathogens are essential to appropriate treatment.

Reversion Mosaicism in Primary Immunodeficiency Diseases.

Reversion mosaicism has been reported in an increasing number of genetic disorders including primary immunodeficiency diseases. Several mechanisms can mediate somatic reversion of inherited mutations. Back mutations restore wild-type sequences, whereas second-site mutations result in compensatory changes. In addition, intragenic recombination, chromosomal deletions, and copy-neutral loss of heterozygosity have been demonstrated in mosaic individuals. Revertant cells that have regained wild-type function may be associated with milder disease phenotypes in some immunodeficient patients with reversion mosaicism. Revertant cells can also be responsible for immune dysregulation. Studies identifying a large variety of genetic changes in the same individual further support a frequent occurrence of reversion mosaicism in primary immunodeficiency diseases. This phenomenon also provides unique opportunities to evaluate the biological effects of restored gene expression in different cell lineages. In this paper, we review the recent findings of reversion mosaicism in primary immunodeficiency diseases and discuss its clinical implications.

Characterization of skin blister fluids from children with Epstein-Barr virus-associated lymphoproliferative disease.

Epstein-Barr virus (EBV)-associated T- or natural killer (NK)-cell lymphoproliferative disease (LPD) is a heterogeneous group of disorders characterized by chronic proliferation of EBV-infected lymphocytes. Patients may present with severe skin manifestations, including hypersensitivity to mosquito bites (HMB) and hydroa vacciniforme (HV)-like eruption, which are characterized by blister formation and necrotic ulceration. Skin biopsy specimens show inflammatory reactions comprising EBV-infected lymphocytes. However, blister fluids have not been fully assessed in patients with this disease. Blister fluids were collected from three patients with EBV-associated LPD: two with HMB and one with HV. Immunophenotyping of blister lymphocytes and measurement of tumor necrosis factor (TNF)-α in blister fluids were performed. The patients with HMB and HV exhibited markedly increased percentages of NK and γδ T cells, respectively, in both peripheral blood and blister fluids. These NK and γδ T cells strongly expressed the activation marker human leukocyte antigen-DR and were considered to be cellular targets of EBV infections. TNF-α was highly elevated in all blister fluids. Severe local skin reactions of EBV-associated LPD may be associated with infiltrating EBV-infected lymphocytes and a high TNF-α concentration in blister fluids.

Longitudinal analysis of serum interleukin-18 in patients with familial Mediterranean fever carrying MEFV mutations in exon 10.

BACKGROUND: Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by mutations in the MEFV gene. Mutations in exon 10 are associated with typical FMF phenotypes, and patients with exon 10 mutations have higher serum levels of interleukin (IL)-18 both during attacks and afebrile phases, compared to those without exon 10 mutations. However, longitudinal changes of serum IL-18 in FMF have not been fully characterized. METHODS: We serially evaluated serum levels of pro-inflammatory cytokines, including IL-18, in 12 patients with FMF carrying exon 10 mutations, all of whom showed typical FMF attacks. RESULTS: Markedly high concentrations of IL-18 were observed in all patients at diagnosis (5099±6084pg/mL). Serum IL-18 levels declined progressively after colchicine treatment in 7 patients (group A), whereas 5 patients showed continued elevation of circulating IL-18, despite declines in IL-6 and neopterin (group B). The mean follow-up times in the two groups were 4.7±3.2 and 4.8±1.5 years, respectively. The mean serum IL-18 level at the last hospital visit in group B was 4190±2610 pg/mL. There were no differences in onset age, initial IL-18 levels, and colchicine doses between the groups. FMF attacks almost disappeared in both groups, but there were trends towards more frequent subtle symptoms such as abdominal discomfort in group B. CONCLUSIONS: Sustained elevation of serum IL-18 may suggest the presence of persistent subclinical inflammation. Therefore, longitudinal examination of serum IL-18 may contribute to better follow-up of FMF patients with exon 10 mutations.