Circulating extracellular vesicles of patients with steroid-sensitive nephrotic syndrome have higher RAC1 and induce recapitulation of nephrotic syndrome phenotype in podocytes.

Since previous research suggests a role of a circulating factor in the pathogenesis of steroid-sensitive nephrotic syndrome (NS), we speculated that circulating plasma extracellular vesicles (EVs) are a candidate source of such a soluble mediator. Here, we aimed to characterize and try to delineate the effects of these EVs in vitro. Plasma EVs from 20 children with steroid-sensitive NS in relapse and remission, 10 healthy controls, and 6 disease controls were obtained by serial ultracentrifugation. Characterization of these EVs was performed by electron microscopy, flow cytometry, and Western blot analysis. Major proteins from plasma EVs were identified via mass spectrometry. Gene Ontology classification analysis and Ingenuity Pathway Analysis were performed on selectively expressed EV proteins during relapse. Immortalized human podocyte culture was used to detect the effects of EVs on podocytes. The protein content and particle number of plasma EVs were significantly increased during NS relapse. Relapse NS EVs selectively expressed proteins that involved actin cytoskeleton rearrangement. Among these, the level of RAC-GTP was significantly increased in relapse EVs compared with remission and disease control EVs. Relapse EVs were efficiently internalized by podocytes and induced significantly enhanced motility and albumin permeability. Moreover, relapse EVs induced significantly higher levels of RAC-GTP and phospho-p38 and decreased the levels of synaptopodin in podocytes. Circulating relapse EVs are biologically active molecules that carry active RAC1 as cargo and induce recapitulation of the NS phenotype in podocytes in vitro.NEW & NOTEWORTHY Up to now, the role of extracellular vesicles (EVs) in the pathogenesis of steroid-sensitive nephrotic syndrome (NS) has not been studied. Here, we found that relapse NS EVs contain significantly increased active RAC1, induce enhanced podocyte motility, and increase expression of RAC-GTP and phospho-p38 expression in vitro. These results suggest that plasma EVs are biologically active molecules in the pathogenesis of NS.

Response to Early Coenzyme Q10 Supplementation Is not Sustained in CoQ10 Deficiency Caused by CoQ2 Mutation.

BACKGROUND: COQ2 mutations cause a rare infantile multisystemic disease with heterogeneous clinical features. Promising results have been reported in response to Coenzyme Q10 treatment, especially for kidney involvement, but little is known about the long-term outcomes. METHODS: We report four new patients from two families with the c.437G→A (p.Ser146Asn) mutation in COQ2 and the outcomes of two patients after long-term coenzyme Q10 treatment. RESULTS: Index cases from two families presented with vomiting, nephrotic range proteinuria, and diabetes in early infancy. These patients were diagnosed with coenzyme Q10 deficiency and died shortly after diagnosis. Siblings of the index cases later presented with neonatal diabetes and proteinuria and were diagnosed at the first day of life. Coenzyme Q10 treatment was started immediately. The siblings responded dramatically to coenzyme Q10 treatment with normalized glucose and proteinuria levels, but they developed refractory focal clonic seizures beginning at three months of life that progressed to encephalopathy. CONCLUSIONS: In our cohort with CoQ10 deficiency, neurological involvement did not improve with oral coenzyme Q10 treatment despite the initial recovery from the diabetes and nephrotic syndrome.

B lymphocyte subsets and outcomes in patients with an initial diagnosis of transient hypogammaglobulinemia of infancy.

PURPOSE: Transient hypogammaglobulinemia of infancy (THI) is a common immunodeficiency, but definitive diagnosis can only be made retrospectively. While the pathogenesis is still unknown, abnormalities have been reported in the B cell compartment. In this study, we analysed the B cell subsets of patients with an initial THI diagnosis (n = 20) and compared them with those of healthy age-matched Turkish children (n = 72). METHODS: Flow cytometric analyses of the B subsets were performed by staining with anti-CD27-PE, anti-CD19-PerCP, anti-IgD-FITC and anti-IgM-APC antibodies. RESULTS: During a median follow-up of 6.6 years, 13 patients whose IgG levels had normalized before they reached four years of age were diagnosed with definitive THI. The memory subsets of these patients were lower but not statistically different from the healthy controls (HC). The remaining seven patients had prolonged hypogammaglobulinemia after the age of four and had significantly lower memory B cell subsets compared to the HC. On follow-up, these patients had not experienced recurrent infections or autoimmunity. Re-evaluation of patients' B cell subsets six years later showed that the memory B cell ratios had increased to levels comparable to HC, despite the patients still having mildly low IgG levels. CONCLUSION: Patients with prolonged hypogammaglobulinemia had lower levels of memory B cells despite having a similar clinical course to patients who had been diagnosed with definitive THI. This subgroup of putative THI patients poses a diagnostic and classification dilemma. Our results suggested that these patients' memory B cells and IgG levels may recover over time.

Alteration of the microRNA expression profile in familial Mediterranean fever patients.

OBJECTIVES: Phenotypic heterogeneity in familial Mediterranean fever (FMF) disease indicated that FMF is not a simple monogenic disease. Therefore it has been suggested that epigenetic factors can be one of the reason for the variations. We undertook this study to test potential involvement of miRNAs in the pathogenesis of FMF. METHODS: miRNA array was performed on whole blood RNA samples from 6 healthy controls (-/-), 6 FMF patients (M694V/M694V), 6 carriers who displayed the disease phenotype (M694V/-) and 6 healthy carriers (M694V/-). The raw data was analysed by Multi Experiment Viewer (MeV) and candidate miRNAs were determined according to fold change (more than 2.0 or less than -2.0). The validation of differentially expressed miRNAs was done by qRT-PCR. Then we performed pathway analyses with using bioinformatics tools. RESULTS: 14 miRNAs were found to be significant among groups through the analysis with MeV. miR-20a-5p, miR-197-3p, let-7d-3p and miR-574-3p were found to be associated with inflammatory pathway related genes according to DAVID analysis. MiR-20a-5p (FDR: 0,00, FCH: 5.55) was significantly up regulated whereas miR-197-3p (FDR: 0,00, FCH: -2.27) was down regulated in homozygotes patients. Both let-7d-3p (FDR: 0.00, FCH: 28.75) and miR-574-3p (FDR: 0.00, FCH: 3.95) were up regulated in heterozygote patients group. CONCLUSIONS: We showed that there are several differentially expressed miRNAs both in homozygote and heterozygote FMF patients compared to controls and healthy carriers. Thus we suggest that these miRNAs, related with inflammatory pathways may be responsible for the expression of the disease in FMF.

Pediatric-onset Behçet disease.

PURPOSE OF REVIEW: Behçet disease has recently been classified as a variable vessel vasculitis. This disease is variable not only in the vessel type it selects, but also in its clinical presentation. In fact, the heterogeneity of the disease has been a drawback in understanding the etiopathogenesis of the disease. This review will address the recent developments in our understanding of the genetic background and pathogenesis of Behçet disease, as well as the analysis of clinical features. RECENT FINDINGS: Recent genome-wide association studies mainly confirm the association with HLA-B51 and highlight the association with IL23/IL17 pathway and IL10, and a molecule that functions in the loading of peptides to HLA Class I molecules. Immunological studies also support the role of IL17 in the disease pathogenesis. Clinical studies in Behçet disease have provided us with clearer definitions of the vascular and central nervous system involvement in Behçet disease. An international effort to delineate the characteristics of pediatric patients has shown us that we need pediatric classification criteria in children with higher sensitivity. As to the treatment of the disease, new biological drugs seem to offer promising results in resistant cases. SUMMARY: The new pathways defined in the disease will not only help us better understand the pathogenesis, but also help us in more targeted therapy. Although pediatric cases are being increasingly recognized, the heterogeneity of the disease presents an obstacle for studies. Thus, we can reach conclusive results with multicenter studies only.