Liposomal nanocarriers of preassembled glycocalyx restore normal venular permeability in sepsis: assessed quantitatively with a novel microchamber system.

BACKGROUND: The endothelial glycocalyx (EG), covering the luminal side of endothelial cells, regulates vascular permeability and senses wall shear stress. In sepsis, EG undergoes degradation leading to increased permeability and edema formation. We hypothesized that restoring EG integrity using liposomal nanocarriers of preassembled glycocalyx (LNPG) will restore normal venular permeability in a lipopolysaccharide (LPS)-induced sepsis model of mice. METHODS: To test this hypothesis, we designed a unique perfusion microchamber in which permeability of isolated venules could be assessed by measuring the concentration of Evans blue dye (EBD) in microliter-samples of extravascular solution (ES). RESULTS: Histamine-induced time- and dose-dependent increases in EBD in the ES could be measured, confirming the sensitivity of the microchamber system. Notably, the histamine-induced increase in permeability was significantly attenuated by histamine receptor (H1) antagonist, triprolidine hydrochloride. Subsequently, mice were treated with LPS, or LPS + LNPG. Compared to control mice, venules from LPS-treated mice showed a significant increased permeability, which was significantly reduced by LNPG administration. Moreover, in the presence of wall shear stress, intraluminal administration of LNPG significantly reduced the permeability in isolated venules from LPS-treated mice. We have found no sex differences. CONCLUSION: Our newly developed microchamber system allows us to quantitatively measure the permeability of isolated mesenteric venules. LPS-induced sepsis increases permeability of venules that is attenuated by in vivo LNPG administration, which is also reestablished endothelial responses to shear stress. Thus, LNPG presents a promising therapeutic potential for restoring EG function and thereby mitigating vasogenic edema due to increased permeability in sepsis.

Long-term efficacy of liposomal nanocarriers of preassembled glycocalyx in restoring cerebral endothelial glycocalyx in sepsis.

The endothelial glycocalyx (EG) undergoes early degradation in sepsis. Our recent work introduced a novel therapeutic approach involving liposomal nanocarriers of preassembled glycocalyx (LNPG) to restore EG in lipopolysaccharide (LPS)-induced sepsis model of mice. While short-term effects were promising, this study focuses on the long-term impact of LNPG on mouse cerebral microcirculation. Utilizing cranial window, we assessed the stability of vascular density (VD) and perfused boundary region (PBR), an index of EG thickness, over a five-day period in normal control mice. In septic groups (LPS, LPS + 1-dose LNPG, and LPS + 2-dose LNPG), the exposure of mice to LPS significantly reduced VD and increased PBR within 3 h. Without LNPG treatment, PBR returned to the normal control level by endogenous processes at 48 h, associated with the recovery of VD to the baseline level at 72 h. However, mice receiving LNPG treatment significantly reduced the increment of PBR at 3 h. The therapeutic effect of 1-dose LNPG persisted for 6 h while the 2-dose LNPG treatment further reduced PBR and significantly increased VD at 12 h compared to LPS group. This study provides valuable insights into the potential therapeutic benefits of LNPG in mitigating EG degradation in sepsis.

Liposomal nanocarriers of preassembled glycocalyx expeditiously restore endothelial glycocalyx in endotoxemia.

The endothelial glycocalyx (EG) is degraded early during sepsis, and currently available treatments are not effective in promptly restoring it. Here, we created liposomal nanocarriers of preassembled glycocalyx (LNPG) by synthesizing glycosylated syndecan-1 and inserting it into the lipid membrane of unilamellar liposomes. We hypothesized that LNPG would fuse with the endothelial cells where EG is degraded and restore EG in sepsis. We induced endotoxemia in C57BL/6J mice using lipopolysaccharides (LPS) and treated them with LNPG, saline, syndecan-1, or liposomes. LNPG significantly prolonged the survival time of LPS-treated mice compared with the other treatments. Immunostaining of en face mesenteric arteries of LPS-treated mice showed that syndecan-1 was fully restored after LNPG administration. In addition, EG height in microvasculature of mouse cremaster muscle was monitored using sidestream dark field imaging. LNPG restored the perfused boundary region (PBR), which is inversely related to EG dimensions, to the control level after LPS administration. Furthermore, flow-induced dilation in isolated mouse mesenteric arterioles was fully recovered after LNPG treatment in LPS-treated mice. In summary, our findings provide evidence of the therapeutic efficacy of LNPG in the LPS-induced mouse model of sepsis, achieved by expeditiously restoring EG through fusion of LNPG with the endothelial plasma membrane and recovery of endothelial function.NEW & NOTEWORTHY Vascular endothelial cells represent the first line of exposure to bacterial endotoxins. Here, we propose a novel therapeutic strategy using liposomes to deliver preassembled glycocalyx to vascular endothelial cell surface and consequently restore endothelial glycocalyx (EG). We tested liposomal nanocarriers of preassembled glycocalyx (LNPG) in vivo and ex vivo to establish for the first time their expeditious therapeutic efficacy in improving survival of lipopolysaccharides (LPS)-treated mice, as achieved by the restoration of EG and recovery of endothelial function.

All reported non-canonical splice site variants in GLA cause aberrant splicing.

BACKGROUND: Fabry disease is an X-linked lysosomal storage disorder caused by insufficient α-galactosidase A (GLA) activity resulting from variants in the GLA gene, which leads to glycosphingolipid accumulation and life-threatening, multi-organ complications. Approximately 50 variants have been reported that cause splicing abnormalities in GLA. Most were found within canonical splice sites, which are highly conserved GT and AG splice acceptor and donor dinucleotides, whereas one-third were located outside canonical splice sites, making it difficult to interpret their pathogenicity. In this study, we aimed to investigate the genetic pathogenicity of variants located in non-canonical splice sites within the GLA gene. METHODS: 13 variants, including four deep intronic variants, were selected from the Human Gene Variant Database Professional. We performed an in vitro splicing assay to identify splicing abnormalities in the variants. RESULTS: All candidate non-canonical splice site variants in GLA caused aberrant splicing. Additionally, all but one variant was protein-truncating. The four deep intronic variants generated abnormal transcripts, including a cryptic exon, as well as normal transcripts, with the proportion of each differing in a cell-specific manner. CONCLUSIONS: Validation of splicing effects using an in vitro splicing assay is useful for confirming pathogenicity and determining associations with clinical phenotypes.

Comprehensive genetic analysis using next-generation sequencing for the diagnosis of nephronophthisis-related ciliopathies in the Japanese population.

Nephronophthisis is an autosomal-recessive kidney disease that is caused by abnormalities in primary cilia. Nephronophthisis-related ciliopathies (NPHP-RCs) are a common cause of end-stage kidney disease (ESKD) in children and adolescents. NPHP-RCs are often accompanied by extrarenal manifestations, including intellectual disability, retinitis pigmentosa, or polydactyly. Although more than 100 causative genes have been identified, its diagnosis is difficult because the clinical features of each mutation often overlap. From September 2010 to August 2021, we performed genetic analysis, including next-generation sequencing (NGS), in 574 probands with kidney dysfunction and retrospectively studied cases genetically diagnosed with NPHP-RCs. RESULTS: We detected mutations related to NPHP-RCs in 93 patients from 83 families. Members of 60 families were diagnosed using NGS, and the mutations and the corresponding number of families are as follows: NPHP1 (24), NPHP3 (10), OFD1 (7), WDR35 (5), SDCCAG8 (4), BBS10 (3), TMEM67 (3), WDR19 (3), BBS1 (2), BBS2 (2), IFT122 (2), IFT140 (2), IQCB1 (2), MKKS (2), SCLT1 (2), TTC21B (2), ALMS1 (1), ANKS6 (1), BBS4 (1), BBS12 (1), CC2D2A (1), DYNC2H1 (1), IFT172 (1), and MAPKBP1 (1). A total of 39 cases (41.9%) progressed to ESKD at the time of genetic analysis, whereas 58 cases (62.3%) showed extrarenal manifestations, the most common being developmental delay, intellectual disability, and autism spectrum disorder in 44 patients. Comprehensive genetic analysis using NGS is useful for diagnosing patients with NPHP-RCs.

Ways and Means of Cellular Reconditioning for Kidney Regeneration.

BACKGROUND: Mitochondrial, lysosomal, and peroxisomal dysfunction; defective autophagy; mitophagy; and pexophagy, as well as the loss of glycocalyx integrity are known contributors to initiation and progression of diverse kidney diseases. Those cellular organelles are tightly interactive in health, and during development of a disease, damage in one may propagate to others. By extension, it follows that restoring an individual defect may culminate in a broader restorative spectrum and improvement of cell and organ functions. SUMMARY: A novel strategy of reconditioning cellular organellar dysfunction, which we define as refurbishment of pathogenically pivotal intra- or extracellular elements, damaged in the course of disease and impeding restoration, is briefly outlined in this overview. Individual therapeutic reconditioning approaches targeting selected organelles are cataloged. We anticipate that the proposed reconditioning strategy in the future may enrich the arsenal of regenerative medicine and nephrology. KEY MESSAGE: The arsenal of regenerative medicine and nephrology consisting of organ transplantation, use of stem cells, cell-free approaches, cell reprogramming strategies, and organ engineering has been enriched by the reconditioning strategy. The latter is based on the recognition of two facts that (a) impairment of diverse cellular organelles contributes to pathogenesis of kidney disease and (b) individual organelles are functionally interactively coupled, which explains the "domino effect" leading to their dysfunction. Reconditioning takes advantage of these facts and, while initially directed to restore the function of individual cellular organelles, culminates in the propagation of a therapeutic intervention to account for improved cell and organ function. Examples of such interventions are briefly summarized along the presentation of defective cellular organelles contributing to pathogenesis of kidney disease.

Detecting pathogenic deep intronic variants in Gitelman syndrome.

Gitelman syndrome (GS) is a rare, autosomal recessive, salt-losing tubulopathy caused by loss of function in the SLC12A3 gene (NM_000339.2), which encodes the natrium chloride cotransporter. The detection of homozygous or compound heterozygous SLC12A3 variants is expected in GS, but 18%-40% of patients with clinical GS carry only one mutant allele. Previous reports identified some pathogenic deep intronic variants in SLC12A3. Here, we report the screening of SLC12A3 deep intronic variants in 13 patients with suspected GS carrying one mutated SLC12A3 allele. Variant screening used the HaloPlex Target Enrichment System Kit capturing whole introns and the promotor region of SLC12A3, followed by SureCall variant analysis. Rare intronic variants (<1% frequency) were identified, and pathogenicity evaluated by the minigene system. Deep intronic variant screening detected seven rare SLC12A3 variants from six patients. Only one variant showed pathogenicity in the minigene system (c.602-16G>A, intron 4) through activation of a cryptic acceptor site. No variants were detected in the promotor region. Deep intronic screening identified only one pathogenic variant in patients with suspected GS carrying monoallelic SLC12A3 variants. Our results suggest that deep intronic variants partially explain the cause of monoallelic variants in patients with GS.

Identification of novel OCRL isoforms associated with phenotypic differences between Dent disease-2 and Lowe syndrome.

BACKGROUND: Although Lowe syndrome and Dent disease-2 are caused by Oculocerebrorenal syndrome of Lowe (OCRL) mutations, their clinical severities differ substantially and their molecular mechanisms remain unclear. Truncating mutations in OCRL exons 1-7 lead to Dent disease-2, whereas those in exons 8-24 lead to Lowe syndrome. Herein we identified the mechanism underlying the action of novel OCRL protein isoforms. METHODS: Messenger RNA samples extracted from cultured urine-derived cells from a healthy control and a Dent disease-2 patient were examined to detect the 5' end of the OCRL isoform. For protein expression and functional analysis, vectors containing the full-length OCRL transcripts, the isoform transcripts and transcripts with truncating mutations detected in Lowe syndrome and Dent disease-2 patients were transfected into HeLa cells. RESULTS: We successfully cloned the novel isoform transcripts from OCRL exons 6-24, including the translation-initiation codons present in exon 8. In vitro protein-expression analysis detected proteins of two different sizes (105 and 80 kDa) translated from full-length OCRL, whereas only one protein (80 kDa) was found from the isoform and Dent disease-2 variants. No protein expression was observed for the Lowe syndrome variants. The isoform enzyme activity was equivalent to that of full-length OCRL; the Dent disease-2 variants retained >50% enzyme activity, whereas the Lowe syndrome variants retained <20% activity. CONCLUSIONS: We elucidated the molecular mechanism underlying the two different phenotypes in OCRL-related diseases; the functional OCRL isoform translated starting at exon 8 was associated with this mechanism.

Use of renin-angiotensin system inhibitors as initial therapy in children with Henoch-Schönlein purpura nephritis of moderate severity.

BACKGROUND: Cases of Henoch-Schönlein purpura nephritis (HSPN) with moderate severity were demonstrated to achieve good prognosis after treatment with renin-angiotensin system (RAS) inhibitors. However, some patients required additional treatment for recurrence after remission. This study aimed to clarify the effect of RAS inhibitors in HSPN cases with moderate severity, including the proportion of cases with recurrence and their response to additional treatment. METHODS: Among 126 patients diagnosed with HSPN between 1996 and 2019, 71 patients with clinicopathologically diagnosed HSPN of moderate severity, defined as ISKDC grade II-IIIa and serum albumin ≥ 2.5 g/dL, were investigated. RESULTS: Proteinuria became negative after RAS inhibitor treatment alone in all 71 cases. However, 16 (22.5%) had recurrence. Eleven recurrent cases achieved negative proteinuria again following additional treatment. At the last follow-up (median 46.5 months; IQR, 23.2-98.2), 5 patients had persistent mild proteinuria; no patients had estimated glomerular filtration rate < 90 mL/min/1.73 m2. The pathological findings in all recurrent cases were ISKDC grade IIIa. The 16 recurrent cases had significantly higher proportions of glomeruli with global/segmental sclerosis (25.0 vs. 0%, P < 0.001) and tubular atrophy/interstitial fibrosis (37.5 vs. 12.7%, P =0.0 24) than 55 cases without recurrence. CONCLUSIONS: Japanese childhood HSPN cases with moderate severity had good outcomes without need for corticosteroids or immunosuppressants, when prescribed RAS inhibitor treatment. Even in recurrent cases, abnormal proteinuria was transient, and prognosis was excellent. A higher resolution version of the Graphical abstract is available as Supplementary information.

Efficacy of combination therapy for childhood complicated focal IgA nephropathy.

BACKGROUND: Patients with immunoglobulin A nephropathy who present with focal mesangial proliferation (focal IgAN) can have a relatively good prognosis, and renin-angiotensin system inhibitor (RAS-i) is commonly used as the initial treatment. However, there are some complicated focal IgAN cases with resistance to RAS-i treatment or nephrotic-range proteinuria. Thus, combination therapy including corticosteroids is often used. This study aimed to evaluate the efficacy of combination therapy for complicated focal IgAN cases by comparing to diffuse mesangial proliferation (diffuse IgAN). METHODS: We conducted a multicenter retrospective study on 88 children who received 2-year combination therapy. The participants were classified based on pathological severity: focal IgAN (n = 26) and diffuse IgAN (n = 62). RESULTS: In total, 26 patients with focal IgAN and 52 with diffuse IgAN achieved proteinuria disappearance within 2 years (100 vs. 83.9%, P = 0.03). Moreover, the time to proteinuria disappearance was significantly shorter in the focal IgAN group than in the diffuse IgAN group (2.9 vs. 4.2 months, P < 0.01) and all patients with focal IgAN achieved proteinuria disappearance within 8 months. At the last observation (8.6 vs. 10.4 years, P = 0.13), only patients with diffuse IgAN (n = 12) had greater than stage 2 chronic kidney disease. In terms of irreversible adverse events, one patient exhibited cataracts. CONCLUSION: Combination therapy was significantly effective in patients with complicated focal IgAN. Moreover, the long-term prognosis was good, and the duration of combination therapy for complicated focal IgAN can be decreased to reduce adverse events.

Clinical features of autosomal recessive polycystic kidney disease in the Japanese population and analysis of splicing in PKHD1 gene for determination of phenotypes.

BACKGROUND: Autosomal recessive polycystic kidney disease (ARPKD) is caused by mutations in the PKHD1 gene. The clinical spectrum is often more variable than previously considered. We aimed to analyze the clinical features of genetically diagnosed ARPKD in the Japanese population. METHODS: We conducted a genetic analysis of patients with clinically diagnosed or suspected ARPKD in Japan. Moreover, we performed a minigene assay to elucidate the mechanisms that could affect phenotypes. RESULTS: PKHD1 pathogenic variants were identified in 32 patients (0-46 years). Approximately one-third of the patients showed prenatal anomalies, and five patients died within one year after birth. Other manifestations were detected as follows: chronic kidney disease stages 1-2 in 15/26 (57.7%), Caroli disease in 9/32 (28.1%), hepatic fibrosis in 7/32 (21.9%), systemic hypertension in 13/27 (48.1%), and congenital hypothyroidism in 3 patients. There have been reported that truncating mutations in both alleles led to severe phenotypes with perinatal demise. However, one patient without a missense mutation survived the neonatal period. In the minigene assay, c.2713C > T (p.Gln905Ter) and c.6808 + 1G > A expressed a transcript that skipped exon 25 (123 bp) and exon 41 (126 bp), resulting in an in-frame mutation, which might have contributed to the milder phenotype. Missense mutations in cases of neonatal demise did not show splicing abnormalities. CONCLUSION: Clinical manifestations ranged from cases of neonatal demise to those diagnosed in adulthood. The minigene assay results indicate the importance of functional analysis, and call into question the fundamental belief that at least one non-truncating mutation is necessary for perinatal survival.

Epidemiological impact of universal varicella vaccination on consecutive emergency department visits for varicella and its economic impact among children in Kobe City, Japan.

INTRODUCTION: Previous studies reported a dramatic decline in the incidence of varicella and varicella-related deaths after implementing universal varicella vaccination (VarV). Although previous studies reported the effectiveness and economic impact of VarV, they were unknown in the emergency department (ED) setting. METHODS: To determine the effectiveness and economic impact of VarV in the ED, Kobe, Japan, we retrospectively reviewed the clinical database of consecutive patients younger than 16 years presenting to our primary ED from 2011 to 2019. RESULTS: Of the 265,191 children presenting to our ED, 3,092 patients were clinically diagnosed with varicella. The number of patients with varicella was approximately 500 annually, before introducing the universal two-dose VarV for children aged 1 to <3 years in October 2014, in the Japanese national immunization program, and decreased to approximately 200 in 2019. The number of patients with varicella younger than 1 year (ineligible for the vaccination) also decreased. Regarding the economic impact, the medical cost in our ED reduced after the introduction of VarV was JPY 4.1 million (US$ 40,049) annually. From the central data, approximately 95% of children were vaccinated after October 2014; however, a relatively large percentage of infected unvaccinated children (59.0%) presented to ED in this study. After the implementation of the universal VarV, infection was mainly observed in older children (i.e., the unvaccinated generation). CONCLUSIONS: Our data showed the effectiveness and economic impact of VarV in the ED setting. Additionally, our data suggested that the public vaccination program should include older unvaccinated children and other unvaccinated individuals.

Multivariate analysis of the impact of weather and air pollution on emergency department visits for unprovoked seizure among children: A retrospective clinical observational study.

BACKGROUND: An unprovoked seizure is a seizure or a cluster of seizures occurring within 24 h in a patient older than 1 month of age without precipitating factors. Recent studies have reported that extrinsic factors, such as meteorological conditions and air pollutants, may be important in seizure occurrence. Thus, this study aimed to examine the association between the number of visits to the emergency department (ED) by children for nighttime unprovoked seizures and exposure to multi-faceted factors, such as meteorological conditions and air pollution. METHODS: We conducted a clinical observational analysis and reviewed consecutive patients younger than 16 years of age who visited the primary ED center in Kobe City, Japan, during nighttime (7:30 p.m.-7:00 a.m.) between January 1, 2011 and December 31, 2015. We investigated the effects of meteorological factors and air pollutants on the number of patients with unprovoked seizures using multivariate analysis of Poisson regression estimates. RESULTS: In total, 151,119 children visited the ED, out of which 97 patients presented with unprovoked seizures. The mean age of the patients was 4.7 years (range, 1 month to 15.3 years), and 54.6% of them were boys. The total number of patients with unprovoked seizures showed no significant changes with the seasons; however, there were dominant peaks during the fall and fewer visits during the summer. The multivariate analysis of Poisson regression estimates revealed a significant positive relationship between the number of patients presenting with unprovoked seizures and precipitation (+1 patient/87 mm; p = 0.03) and methane (+1 patient/0.14 ppm; p = 0.03) levels and a negative relationship between the number of patients presenting with unprovoked seizures and nitrogen dioxide level (-1 patient/0.02 ppm; p = 0.04). CONCLUSIONS: The present study is the first to evaluate the association between the number of children who presented to the ED with nighttime unprovoked seizures and environmental factors after controlling for confounding factors.

X-chromosome inactivation patterns in females with Fabry disease examined by both ultra-deep RNA sequencing and methylation-dependent assay.

BACKGROUND: Fabry disease is an X-linked inherited lysosomal storage disorder caused by mutations in the gene encoding α-galactosidase A. Males are usually severely affected, while females have a wide range of disease severity. This variability has been assumed to be derived from organ-dependent skewed X-chromosome inactivation (XCI) patterns in each female patient. Previous studies examined this correlation using the classical methylation-dependent method; however, conflicting results were obtained. This study was established to ascertain the existence of skewed XCI in nine females with heterozygous pathogenic variants in the GLA gene and its relationship to the phenotypes. METHODS: We present five female patients from one family and four individual female patients with Fabry disease. In all cases, heterozygous pathogenic variants in the GLA gene were detected. The X-chromosome inactivation patterns in peripheral blood leukocytes and cells of urine sediment were determined by both classical methylation-dependent HUMARA assay and ultra-deep RNA sequencing. Fabry Stabilization Index was used to determine the clinical severity. RESULTS: Skewed XCI resulting in predominant inactivation of the normal allele was observed only in one individual case with low ⍺-galactosidase A activity. In the remaining cases, no skewing was observed, even in the case with the highest total severity score (99.2%). CONCLUSION: We conclude that skewed XCI could not explain the severity of female Fabry disease and is not the main factor in the onset of various clinical symptoms in females with Fabry disease.

Utility of glomerular Gd-IgA1 staining for indistinguishable cases of IgA nephropathy or Alport syndrome.

BACKGROUND: Pathological findings in Alport syndrome frequently show mesangial proliferation and sometimes incidental IgA deposition, in addition to unique glomerular basement membrane (GBM) changes including thin basement membrane and/or lamellation. However, similar GBM abnormalities are also often observed in IgA nephropathy. Both diseases are also known to show hematuria, proteinuria, and sometimes macrohematuria when associated with viral infection. Therefore, it can be difficult to make a differential diagnosis, even based on clinical and pathological findings. Some recent articles demonstrated that galactose-deficient IgA1 (Gd-IgA1)-specific monoclonal antibody (KM55) could potentially enable incidental IgA deposition to be distinguished from IgA nephropathy. METHODS: We performed comprehensive gene screening and glomerular Gd-IgA1 and type IV collagen α5 chain immunostaining for five cases with both IgA deposition and GBM changes to confirm that Gd-IgA1 can help to distinguish these two diseases. RESULTS: Four of the cases were genetically diagnosed with Alport syndrome (Cases 1-4) and one was IgA nephropathy with massive GBM changes, which had a negative gene test result (Case 5). In Cases 1-4, glomerular Gd-IgA1 deposition was not detected, although there was positivity for IgA in the mesangial area. In Case 5, glomerular Gd-IgA1 deposition was observed. CONCLUSION: Gd-IgA1 expression analysis could clearly differentiate these two disorders. This approach can be applied to identify these two diseases showing identical clinical and pathological findings.

Genotype-phenotype correlations influence the response to angiotensin-targeting drugs in Japanese patients with male X-linked Alport syndrome.

Early kidney failure in the hereditary type IV collagen disease, Alport syndrome, can be delayed by renin-angiotensin inhibitors. However, whether all patients and all different genotypes respond equally well to this kidney-protective therapy remains unclear. Here, we performed a retrospective study on 430 patients with male X-linked Alport syndrome to examine the relationships among kidney prognosis, genotype, and treatment effect in a large cohort of Japanese patients. We analyzed the clinical features, genotype-phenotype correlation, and kidney survival period for patients treated with or without renin-angiotensin inhibitors. As a result, the median kidney survival period of patients in this cohort was found to be at 35 years with a strong genotype-phenotype correlation. The median age at the onset of end stage kidney disease (ESKD) significantly differed between patients treated with and without renin-angiotensin inhibitors (over 50 years versus 28 years, respectively). Moreover, these drugs delayed the onset of ESKD in patients with truncating variants for 12 years, extending the median age from 16 years to 28 years. Thus, our results confirmed a strong genotype-phenotype correlation in patients with male X-linked Alport syndrome. Additionally, it was suggested that renin-angiotensin inhibitors could significantly delay ESKD progression. Despite these therapies, patients with truncating variants developed ESKD at the median age of 28 years.

Comparison of clinical and genetic characteristics between Dent disease 1 and Dent disease 2.

BACKGROUND: Dent disease is associated with low molecular weight proteinuria and hypercalciuria and caused by pathogenic variants in either of two genes: CLCN5 (Dent disease 1) and OCRL (Dent disease 2). It is generally not accompanied by extrarenal manifestations and it is difficult to distinguish Dent disease 1 from Dent disease 2 without gene testing. We retrospectively compared the characteristics of these two diseases using one of the largest cohorts to date. METHODS: We performed gene testing for clinically suspected Dent disease, leading to the genetic diagnosis of 85 males: 72 with Dent disease 1 and 13 with Dent disease 2. A retrospective review of the clinical findings and laboratory data obtained from questionnaires submitted in association with the gene testing was conducted for these cases. RESULTS: The following variables had significantly higher levels in Dent disease 2 than in Dent disease 1: height standard deviation score (height SDS), serum creatinine-based estimated GFR (Cr-eGFR) (median: 84 vs. 127 mL/min/1.73 m2, p < 0.01), serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), serum lactate dehydrogenase (LDH), serum creatine phosphokinase (CK), serum potassium, serum inorganic phosphorus, serum uric acid, urine protein/creatinine ratio (median: 3.5 vs. 1.6 mg/mg, p < 0.01), and urine calcium/creatinine ratio. There were no significant differences in serum sodium, serum calcium, alkaline phosphatase (ALP), urine ß2-microglobulin, incidence of nephrocalcinosis, and prevalence of intellectual disability or autism spectrum disorder. CONCLUSIONS: The clinical and laboratory features of Dent disease 1 and Dent disease 2 were shown in this study. Notably, patients with Dent disease 2 showed kidney dysfunction at a younger age, which should provide a clue for the differential diagnosis of these diseases.

Functional analysis of suspected splicing variants in CLCN5 gene in Dent disease 1.

BACKGROUND: In recent years, the elucidation of splicing abnormalities as a cause of hereditary diseases has progressed. However, there are no comprehensive reports of suspected splicing variants in the CLCN5 gene in Dent disease cases. We reproduced gene mutations by mutagenesis, inserted the mutated genes into minigene vectors, and investigated the pathogenicity and onset mechanisms of these variants. METHODS: We conducted functional splicing assays using a hybrid minigene for six suspected splicing variants (c.105G>A, c.105+5G>C, c.106-17T>G, c.393+4A>G, c.517-8A>G, c.517-3C>A) in CLCN5. We extracted information on these variants from the Human Gene Mutation Database. We reproduced minigene vectors with the insertion of relevant exons with suspected splicing variants. We then transfected these minigene vectors into cultured cells and extracted and analyzed the mRNA. In addition, we conducted in silico analysis to confirm our minigene assay results. RESULTS: We successfully determined that five of these six variants are pathogenic via the production of splicing abnormalities. One showed only normal transcript production and was thus suspected of not being pathogenic (c.106-17T>G). CONCLUSION: We found that five CLCN5 variants disrupted the original splice site, resulting in aberrant splicing. It is sometimes difficult to obtain mRNA from patient samples because of the fragility of mRNA or its low expression level in peripheral leukocytes. Our in vitro system can be used as an alternative to in vivo assays to determine the pathogenicity of suspected splicing variants.

Retrospective analysis of high-dose chemotherapy followed by autologous stem cell transplantation for high-risk pediatric osteosarcoma.

The outcomes of osteosarcoma with poor prognostic factors, such as poor responders, metastatic disease at diagnosis, and relapsed or refractory disease, are poor. We reviewed the clinical records of the patients diagnosed with osteosarcoma at our institute between 2004 and 2018 who received high-dose chemotherapy followed by autologous stem cell transplantation (ASCT) in our institute. Ten patients of osteosarcoma with poor responder, refractory status, and metastatic disease at diagnosis received high-dose chemotherapy followed by ASCT. Four patients underwent high-dose chemotherapy followed by ASCT with the conditioning regimen consisted of thiotepa and melphalan (MEL). Five patients underwent high-dose chemotherapy followed by ASCT with the conditioning regimen consisted of intravenous busulfan (BU) and MEL. One patient underwent tandem high-dose chemotherapy followed by ASCT with BU and MEL followed by carboplatin and etoposide. None of the ten patients died of regimen related toxicities. None of the five patients with poor responders who underwent high-dose chemotherapy followed by ASCT as part of consolidation therapy died of disease after ASCT. High-dose chemotherapy followed by ASCT might be effective for poor responders in osteosarcoma.