Crosstalk between oxygen signaling and iron metabolism in renal interstitial fibroblasts.

To maintain the oxygen supply, the production of red blood cells (erythrocytes) is promoted under low-oxygen conditions (hypoxia). Oxygen is carried by hemoglobin in erythrocytes, in which the majority of the essential element iron in the body is contained. Because iron metabolism is strictly controlled in a semi-closed recycling system to protect cells from oxidative stress caused by iron, hypoxia-inducible erythropoiesis is closely coordinated by regulatory systems that mobilize stored iron for hemoglobin synthesis. The erythroid growth factor erythropoietin (EPO) is mainly secreted by interstitial fibroblasts in the renal cortex, which are known as renal EPO-producing (REP) cells, and promotes erythropoiesis and iron mobilization. Intriguingly, EPO production is strongly induced by hypoxia through iron-dependent pathways in REP cells. Here, we summarize recent studies on the network mechanisms linking hypoxia-inducible EPO production, erythropoiesis and iron metabolism. Additionally, we introduce disease mechanisms related to disorders in the network mediated by REP cell functions. Furthermore, we propose future studies regarding the application of renal cells derived from the urine of kidney disease patients to investigate the molecular pathology of chronic kidney disease and develop precise and personalized medicine for kidney disease.

Mizoribine halts kidney fibrosis in childhood IgA nephropathy: association with modulation of M2-type macrophages.

BACKGROUND: The immunosuppressant mizoribine (Miz) can reduce progression of childhood IgA nephropathy (IgAN). This study examined whether Miz affects CD163+ M2-type macrophages which are associated with kidney fibrosis in childhood IgAN. METHODS: A retrospective cohort of 90 children with IgAN were divided into groups treated with prednisolone (PSL) alone (P group; n = 42) or PSL plus Miz (PM group; n = 48) for a 2-year period. Normal human monocyte-derived macrophages were stimulated with dexamethasone (Dex), or Dex plus Miz, and analyzed by DNA microarray. RESULTS: Clinical and histological findings at first biopsy were equivalent between patients entering the P and PM groups. Both treatments improved proteinuria and haematuria, and maintained normal kidney function over the 2-year course. The P group exhibited increased mesangial matrix expansion, increased glomerular segmental or global sclerosis, and increased interstitial fibrosis at 2-year biopsy; however, the PM group showed no progression of kidney fibrosis. These protective effects were associated with reduced numbers of glomerular and interstitial CD163+ macrophages in the PM versus P group. In cultured human macrophages, Dex induced upregulation of cytokines and growth factors, which was prevented by Miz. Miz also inhibited Dex-induced expression of CD300E, an activating receptor which can prevent monocyte apoptosis. CD300e expression by CD163+ macrophages was evident in the P group, which was reduced by Miz treatment. CONCLUSION: Miz halted the progression of kidney fibrosis in PSL-treated pediatric IgAN. This was associated with reduced CD163+ and CD163+CD300e+ macrophage populations, plus in vitro findings that Miz can suppress steroid-induced macrophage expression of pro-fibrotic molecules. A higher resolution version of the Graphical abstract is available as Supplementary information.

An Infant Case of Transient Distal Renal Tubular Acidosis and Fanconi Syndrome Caused by Rotavirus Gastroenteritis.

We report an infant case of transient distal renal tubular acidosis and Fanconi syndrome caused by rotavirus gastroenteritis. A 10-month-old boy was admitted to the hospital because of frequent vomiting, lack of vitality, and dehydration. He was diagnosed with rotavirus gastroenteritis on account of his positive stool rotavirus antigen test. Although he presented with acidemia and severe mixed metabolic acidosis, he also had a urine pH of 6.0, indicating impaired urinary acidification. Therefore, he was diagnosed with distal renal tubular acidosis. On the third day of hospitalization, a relatively low %tubular reabsorption of phosphate level with hypophosphatemia, increased fractional excretion of uric acid with hypouricemia, and high urinary ß2-microglobulin levels were observed. Moreover, he was diagnosed with Fanconi syndrome on account of multiple proximal tubular dysfunctions. After remission of rotavirus gastroenteritis, the signs of renal tubular dysfunction improved. This was a case of rotavirus gastroenteritis-caused transient distal renal tubular acidosis and Fanconi syndrome. Severe metabolic acidosis resulted from anion-gap metabolic acidosis due to acute kidney injury by rotavirus gastroenteritis and normal anion-gap acidosis due to renal tubular acidosis. When renal tubular acidosis is associated with a disease that causes anion-gap metabolic acidosis, mixed metabolic acidosis occurs and becomes exacerbated. Furthermore, it is important to consider the complications of renal tubular acidosis in the case of severe metabolic acidosis.

Mycophenolate Mofetil after Rituximab for Childhood-Onset Complicated Frequently-Relapsing or Steroid-Dependent Nephrotic Syndrome.

BACKGROUND: Rituximab is the standard therapy for childhood-onset complicated frequently relapsing or steroid-dependent nephrotic syndrome (FRNS/SDNS). However, most patients redevelop FRNS/SDNS after peripheral B cell recovery. METHODS: We conducted a multicenter, randomized, double-blind, placebo-controlled trial to examine whether mycophenolate mofetil (MMF) administration after rituximab can prevent treatment failure (FRNS, SDNS, steroid resistance, or use of immunosuppressive agents or rituximab). In total, 39 patients (per group) were treated with rituximab, followed by either MMF or placebo until day 505 (treatment period). The primary outcome was time to treatment failure (TTF) throughout the treatment and follow-up periods (until day 505 for the last enrolled patient). RESULTS: TTFs were clinically but not statistically significantly longer among patients given MMF after rituximab than among patients receiving rituximab monotherapy (median, 784.0 versus 472.5 days, hazard ratio [HR], 0.59; 95% confidence interval [95% CI], 0.34 to 1.05, log-rank test: P=0.07). Because most patients in the MMF group presented with treatment failure after MMF discontinuation, we performed a post-hoc analysis limited to the treatment period and found that MMF after rituximab prolonged the TTF and decreased the risk of treatment failure by 80% (HR, 0.20; 95% CI, 0.08 to 0.50). Moreover, MMF after rituximab reduced the relapse rate and daily steroid dose during the treatment period by 74% and 57%, respectively. The frequency and severity of adverse events were similar in both groups. CONCLUSIONS: Administration of MMF after rituximab may sufficiently prevent the development of treatment failure and is well tolerated, although the relapse-preventing effect disappears after MMF discontinuation.

Transient Type 3 Renal Tubular Acidosis during Cyclic Vomiting Syndrome.

Type 3 renal tubular acidosis is a pathological condition characterized by the simultaneous occurrence of distal renal tubular acidosis, which causes urinary acidification disorders, and proximal renal tubular acidosis, which causes impaired reabsorption of bicarbonate ions. Type 3 renal tubular acidosis is considered rare. A 5-year-old boy was admitted to our hospital because of frequent vomiting, poor vitality, and fever. He was diagnosed with cyclic vomiting syndrome. Type 3 renal tubular acidosis was also diagnosed because of severe mixed metabolic acidosis with impaired urinary acidification, a low tubular phosphorus reabsorption rate with hypophosphatemia, low-molecular-weight proteinuria, pan-aminoaciduria, and glucosuria. Fluid infusion was performed. On the second day of hospitalization, the vomiting disappeared and the patient was able to eat and drink. He was discharged on the eighth day of hospitalization. The laboratory test abnormalities associated with the renal tubular acidosis gradually improved, and testing at discharge on the eighth day of admission showed no metabolic acidosis, hypophosphatemia, low-molecular-weight proteinuria, or glucosuria. These findings suggested that the type 3 renal tubular acidosis was transient. Severe metabolic acidosis was observed in this patient because of both normal anion gap metabolic acidosis due to type 3 renal tubular acidosis and anion gap metabolic acidosis due to cyclic vomiting syndrome. Although type 3 tubular acidosis is rare, the resultant metabolic acidosis worsens when combined with a disease that causes metabolic acidosis. Type 3 tubular acidosis should be ruled out when severe metabolic acidosis is present.

An Infant Case of Streptococcus Pneumoniae-Associated Thrombotic Microangiopathy with Heterozygous CFI Mutation and CFHR3-CFHR1 Deletion.

Thrombotic microangiopathy (TMA) is a disease that causes organ damage due to microvascular hemolytic anemia, thrombocytopenia, and microvascular platelet thrombosis. Streptococcus pneumoniae-associated TMA (spTMA) is a rare complication of invasive pneumococcal infection. In addition, atypical hemolytic uremic syndrome (aHUS) is TMA associated with congenital or acquired dysregulation of complement activation. We report the case of a nine-month-old boy with refractory nephrotic syndrome complicated by spTMA in the setting of heterozygous complement factor-I (CFI) gene mutation and CFHR3-CFHR1 deletion. He repeatedly developed thrombocytopenia, anemia with schistocytes, hypocomplementemia, and abnormal coagulation triggered by infection, which manifested clinically with convulsions and an intraperitoneal hematoma. Eculizumab (a monoclonal humanized anti-C5 antibody) provided transient symptomatic benefit including improvement in thrombocytopenia; however, he developed unexplained cardiac arrest and was declared brain dead a few days later. In this report, we highlight the diagnostic challenges of this case and the causal relationship between spTMA and complement abnormalities and consider the contribution of heterozygous mutation of CFI and CFHR3-CFHR1 deletion.

Biallelic variants/mutations of IL1RAP in patients with steroid-sensitive nephrotic syndrome.

Nephrotic syndrome (NS) is a renal disease characterized by severe proteinuria and hypoproteinemia. Although several single-gene mutations have been associated with steroid-resistant NS, causative genes for steroid-sensitive NS (SSNS) have not been clarified. While seeking to identify causative genes associated with SSNS by whole-exome sequencing, we found compound heterozygous variants/mutations (c.524T>C; p.I175T and c.662G>A; p.R221H) of the interleukin-1 receptor accessory protein (IL1RAP) gene in two siblings with SSNS. The siblings' parents are healthy, and each parent carries a different heterozygous IL1RAP variant/mutation. Since IL1RAP is a critical subunit of the functional interleukin-1 receptor (IL-1R), we investigated the effect of these variants on IL-1R subunit function. When stimulated with IL-1ß, peripheral blood mononuclear cells from the siblings with SSNS produced markedly lower levels of cytokines compared with cells from healthy family members. Moreover, IL-1R with a variant IL1RAP subunit, reconstituted on a hematopoietic cell line, had impaired binding ability and low reactivity to IL-1ß. Thus, the amino acid substitutions in IL1RAP found in these NS patients are dysfunctional variants/mutations. Furthermore, in the kidney of Il1rap-/- mice, the number of myeloid-derived suppressor cells, which require IL-1ß for their differentiation, was markedly reduced although these mice did not show significantly increased proteinuria in acute nephrotic injury with lipopolysaccharide treatment. Together, these results identify two IL1RAP variants/mutations in humans for the first time and suggest that IL1RAP might be a causative gene for familial NS.

Steroid treatment promotes an M2 anti-inflammatory macrophage phenotype in childhood lupus nephritis.

BACKGROUND: M1-type proinflammatory macrophages (MΦ) promote glomerular injury in lupus nephritis (LN). However, whether this phenotype is altered by steroid therapy is unclear. Therefore, we investigated the effect of steroid treatment on MΦ phenotype in LN. METHODS: Patients with LN (7-18 years old) were divided into 2 groups: those with no treatment (N) before biopsy (n = 17) and those who underwent steroid (S) treatment (3-73 days) before biopsy (n = 15). MΦ number and phenotype were assessed by immunofluorescence. In vitro studies used monocyte-derived MΦ from healthy volunteers. RESULTS: Age at biopsy, urine findings, and kidney function (eGFR) were comparable between the two groups. Biopsies in N group had higher levels of active lesions such as endocapillary hypercellularity, necrosis, and cellular crescent formation (p < 0.05). The total CD68+ MΦ infiltrate was comparable between N and S groups. However, N group had more M1 MΦ (CD68+ CD86+ cells) (p < 0.05) and fewer M2 MΦ (CD68+ CD163+ cells) (p < 0.05), giving a 6-fold increase in the M2/M1 ratio in S vs. N groups. Dexamethasone treatment of cultured MΦ induced upregulation of CD163 expression, increased production of anti-inflammatory (IL-10, IL-19) and profibrotic factors (FGF-22, PDGF), and upregulated the scavenger receptor, stabilin-1. Upregulation of stabilin-1 in CD163+ M2 MΦ was confirmed in biopsies from S group. CONCLUSIONS: Initial steroid treatment induces MΦ phenotypic change from proinflammatory M1 to anti-inflammatory or profibrotic M2 in LN with acute/active lesions. Although steroid treatment is effective for resolution of M1-medated injury, promotion of fibrotic lesions via M2 MΦ is a potential downside of steroid single therapy in LN.

Management of a Preterm Infant with Renal Tubular Dysgenesis: A Case Report and Review of the Literature.

Renal tubular dysgenesis (RTD) is the absence or poor development of the renal proximal tubules caused by gene mutations in the renin-angiotensin system. Although RTD has been considered fatal, improving neonatal intensive care management has enhanced survival outcomes. However, little has been reported on the survival of extremely preterm infants. This study reports the survival of an extremely preterm infant with RTD and discusses the appropriate management of RTD by reviewing the literature. A female infant weighing 953 g was delivered at 27 weeks' gestation by Cesarean section because of oligohydramnios. She exhibited severe persistent pulmonary hypertension, severe systemic hypotension, and renal dysfunction shortly after birth. Respiratory management was successfully undertaken using nitric oxide inhalation and high-frequency oscillatory ventilation. Desmopressin was effective in maintaining her blood pressure and urinary output. She was diagnosed with RTD based on genetic testing, which revealed a compound heterozygous mutation in the angiotensin-converting enzyme gene in exon 18 (c.2689delC; p.Pro897fs) and exon 20 (c.3095dupT; p.Leu1032fs). At 2 years, she started receiving oral fludrocortisone for treating persistently high serum creatinine levels, which was attributed to nephrogenic diabetes insipidus caused by RTD. Subsequently, her urine output decreased, and renal function was successfully maintained. Currently, there is no established treatment for RTD. Considering cases reported to date, treatment with vasopressin and fludrocortisone appears to be most effective for survival and maintenance of renal function in patients with RTD. This study presents the successful management of RTD using this strategy in an extremely preterm infant.

Assessment of factors associated with mizoribine responsiveness in children with steroid-dependent nephrotic syndrome.

BACKGROUND: Several immunosuppressants have been used to treat children with steroid-dependent nephrotic syndrome (SDNS). Mizoribine (MZR) is an immunosuppressant used to maintain remission in children with SDNS, although its effectiveness for treating SDNS remains controversial. Therefore, in this study, we assessed the clinical factors associated with children having SDNS who were successfully treated with MZR. METHODS: A total of 47 children with SDNS who underwent MZR treatment were retrospectively evaluated. Clinical features including pharmacokinetics after MZR administration were compared between MZR responders and non-responders. RESULTS: The comparison of the two groups revealed no significant differences in age, body weight (BW), daily dose of MZR per BW, serum concentration 2 h after administration (C2), peak serum concentration (Cmax), and area under the concentration curve 0-4 h after administration (AUC0-4). C2/(single dose/BW), Cmax/(single dose/BW), and AUC0-4/(single dose/BW) were significantly higher in the MZR responders than in the non-responders (all p < 0.01). Receiver operating characteristic analysis revealed that the cutoff values of C2 (single dose/kg), Cmax/(single dose/BW), and AUC0-4/(single dose/BW) were 0.55, 0.58, and 1.37, respectively. CONCLUSIONS: MZR is a useful immunosuppressant for treating frequent-relapse NS in children who are susceptible to the drug. The efficacy of MZR may be associated with not only serum concentrations defined by the dosage or absorption efficiency through MZR transporters, but also the susceptibility defined by the expression level and performance of MZR transporters on the target cells.

Management of patients with severe Epstein syndrome: Review of four patients who received living-donor renal transplantation.

AIM: Epstein syndrome is a hereditary disease characterized by macrothrombocytopaenia and progressive nephritis. The abnormality of the MYH9 gene has a strong relationship to the severity of the disease. Severe Epstein syndrome progresses to end-stage renal disease rapidly after adolescence. There is no established therapy. We sought to clarify appropriate management of Epstein syndrome nephropathy. METHODS: Epstein syndrome patients who underwent renal transplantation at our institution between March 2009 and March 2017 were enrolled. Epstein syndrome was diagnosed based on clinical features and genetic testing. Patient medical records were reviewed retrospectively. RESULTS: Four male patients with Epstein syndrome, all with severe MYH9 gene mutations (p.R702C in three and p.S96L in one), were enrolled. Despite treatment with renin-angiotensin system blockers, nephropathy was refractory and progressed rapidly, and the patients required dialysis or renal transplantation after adolescence. Early preparation for treatment based on early and accurate diagnosis of Epstein syndrome enabled two patients to undergo pre-emptive renal transplantation. For these patients, we kept the platelet count above 100 × 109 /L until day 7 after renal transplantation with platelet transfusions for macrothrombocytopaenia, and no postoperative bleeding episodes occurred. CONCLUSION: Epstein syndrome nephropathy due to a severe MYH9 gene mutation can be refractory and progress rapidly; therefore, early and accurate diagnosis is important for safer therapeutic options including pre-emptive renal transplantation. By keeping the platelet count above 100 × 109 /L during the perioperative period, renal transplantation can be a safe treatment option for severe Epstein syndrome nephropathy.

Strong Association of the HLA-DR/DQ Locus with Childhood Steroid-Sensitive Nephrotic Syndrome in the Japanese Population.

Background Nephrotic syndrome is the most common cause of chronic glomerular disease in children. Most of these patients develop steroid-sensitive nephrotic syndrome (SSNS), but the loci conferring susceptibility to childhood SSNS are mainly unknown.Methods We conducted a genome-wide association study (GWAS) in the Japanese population; 224 patients with childhood SSNS and 419 adult healthy controls were genotyped using the Affymetrix Japonica Array in the discovery stage. Imputation for six HLA genes (HLA-A, -C, -B, -DRB1, -DQB1, and -DPB1) was conducted on the basis of Japanese-specific references. We performed genotyping for HLA-DRB1/-DQB1 using a sequence-specific oligonucleotide-probing method on a Luminex platform. Whole-genome imputation was conducted using a phased reference panel of 2049 healthy Japanese individuals. Replication was performed in an independent Japanese sample set including 216 patients and 719 healthy controls. We genotyped candidate single-nucleotide polymorphisms using the DigiTag2 assay.Results The most significant association was detected in the HLA-DR/DQ region and replicated (rs4642516 [minor allele G], combined Pallelic=7.84×10-23; odds ratio [OR], 0.33; 95% confidence interval [95% CI], 0.26 to 0.41; rs3134996 [minor allele A], combined Pallelic=1.72×10-25; OR, 0.29; 95% CI, 0.23 to 0.37). HLA-DRB1*08:02 (Pc=1.82×10-9; OR, 2.62; 95% CI, 1.94 to 3.54) and HLA-DQB1*06:04 (Pc=2.09×10-12; OR, 0.10; 95% CI, 0.05 to 0.21) were considered primary HLA alleles associated with childhood SSNS. HLA-DRB1*08:02-DQB1*03:02 (Pc=7.01×10-11; OR, 3.60; 95% CI, 2.46 to 5.29) was identified as the most significant genetic susceptibility factor.Conclusions The most significant association with childhood SSNS was detected in the HLA-DR/DQ region. Further HLA allele/haplotype analyses should enhance our understanding of molecular mechanisms underlying SSNS.

Application of Muse Cell Therapy for Kidney Diseases.

The kidney plays an essential role in the maintenance of homeostasis in healthy individuals, e.g., by regulating the amount of water and concentration of electrolyte in the body. Owing to the structural complexity, renal dysfunction is caused by a myriad of diseases and conditions, and in severe cases, it progresses to end-stage renal disease in which patients require renal replacement therapy, i.e., maintenance dialysis or kidney transplantation. The currently available therapeutic modalities, with the exception of renal transplantation, cannot recover severely deteriorated renal function. Thus, regenerative medicine holds considerable promise as a potential means for developing next-generation renal therapeutics. Mesenchymal stem cell (MSC) transplantation has been investigated in acute kidney injury and chronic kidney disease models, and clinical studies have already been started for some kinds of kidney diseases. However, most of these studies concluded that the main underlying mechanism of therapeutic effect of MSC transplantation was paracrine. Recently, we reported that Muse cell therapy in a murine model of chronic kidney disease resulted in differentiation of intravenously injected Muse cells into glomerular cells after preferential homing to damaged glomerulus and improvement in renal function. The result suggested the potentiality of Muse cell therapy for glomerular regeneration. Muse cells are a promising cell source for regenerative therapy for kidney diseases.

Beneficial Effects of Systemically Administered Human Muse Cells in Adriamycin Nephropathy.

Multilineage-differentiating stress-enduring (Muse) cells are nontumorigenic endogenous pluripotent-like stem cells that can be collected from various organs. Intravenously administered Muse cells have been shown to spontaneously migrate to damaged tissue and replenish lost cells, but the effect in FSGS is unknown. We systemically administered human bone marrow-derived Muse cells without concurrent administration of immunosuppressants to severe combined immune-deficient (SCID) and BALB/c mouse models with adriamycin-induced FSGS (FSGS-SCID and FSGS-BALB/c, respectively). In FSGS-SCID mice, human Muse cells preferentially integrated into the damaged glomeruli and spontaneously differentiated into cells expressing markers of podocytes (podocin; 31%), mesangial cells (megsin; 13%), and endothelial cells (CD31; 41%) without fusing to the host cells; attenuated glomerular sclerosis and interstitial fibrosis; and induced the recovery of creatinine clearance at 7 weeks. Human Muse cells induced similar effects in FSGS-BALB/c mice at 5 weeks, despite xenotransplant without concurrent immunosuppressant administration, and led to improvement in urine protein, creatinine clearance, and plasma creatinine levels more impressive than that in the FSGS-SCID mice at 5 weeks. However, functional recovery in FSGS-BALB/c mice was impaired at 7 weeks due to immunorejection, suggesting the importance of Muse cell survival as glomerular cells in the FSGS kidney for tissue repair and functional recovery. In conclusion, Muse cells are unique reparative stem cells that preferentially home to damaged glomeruli and spontaneously differentiate into glomerular cells after systemic administration. Introduction of genes to induce differentiation is not required before Muse cell administration; thus, Muse cells may be a feasible therapeutic strategy in FSGS.

Early RAAS Blockade Exerts Renoprotective Effects in Autosomal Recessive Alport Syndrome.

Alport syndrome is a progressive renal disease caused by mutations in COL4A3, COL4A4, and COL4A5 genes that encode collagen type IV alpha 3, alpha 4, and alpha 5 chains, respectively. Because of abnormal collagen chain, glomerular basement membrane becomes fragile and most of the patients progress to end-stage renal disease in early adulthood. COL4A5 mutation causes X-linked form of Alport syndrome, and two mutations in either COL4A3 or COL4A4 causes an autosomal recessive Alport syndrome. Recently, renin-angiotensin-aldosterone system (RAAS) blockade has been shown to attenuate effectively disease progression in Alport syndrome. Here we present three Japanese siblings and their father all diagnosed with autosomal recessive Alport syndrome and with different clinical courses, suggesting the importance of the early initiation of RAAS blockade. The father was diagnosed with Alport syndrome. His consanguineous parents and his wife were healthy. All three siblings showed hematuria since infancy. Genetic analysis revealed that they shared the same gene mutations in COL4A3 in a compound heterozygous state: c.2330G>A (p.Gly777Ala) from the mother and c.4354A>T (p.Ser1452Cys) from the father. Although RAAS blockade was initiated for the older sister and brother when their renal function was already impaired, it did not attenuate disease progression. In the youngest brother, RAAS blockade was initiated during normal renal function stage. After the initiation, his renal function has been normal with the very mild proteinuria to date at the age of 17 years. We propose that in Alport syndrome, RAAS blockade should be initiated earlier than renal function is impaired.

Development of enzyme-linked immunosorbent assays for urinary thiazide-sensitive Na-Cl cotransporter measurement.

The Na-Cl cotransporter (NCC) in the distal convoluted tubules in kidney is known to be excreted in urine. However, its clinical significance has not been established because of the lack of quantitative data on urinary NCC. We developed highly sensitive enzyme-linked immunosorbent assays (ELISAs) for urinary total NCC (tNCC) and its active form, phosphorylated NCC (pNCC). We first measured the excretion of tNCC and pT55-NCC in urinary exosomes in pseudohypoaldosteronism type II (PHAII) patients since PHAII is caused by NCC activation. Highly increased excretion of tNCC and pNCC was observed in PHAII patients. In contrast, the levels of tNCC and pNCC in the urine of patients with Gitelman's syndrome were not detectable or very low, indicating that both assays could specifically detect the changes in urinary NCC excretion caused by the changes of NCC activity in the kidney. Then, to test whether these assays could be feasible for a more general patient population, we measured tNCC and pNCC in the urine of outpatients with different clinical backgrounds. Although urinary protein levels >30 mg/dl interfered with our ELISA, we could measure urinary pNCC in all patients without proteinuria. Thus we established highly sensitive and quantitative assays for urinary NCC, which could be valuable tools for estimating NCC activity in vivo.

Urinary fractalkine and monocyte chemoattractant protein-1 as possible predictors of disease activity of childhood glomerulonephritis.

Renal biopsy is the gold standard for confirmation of disease severity and diagnosis of glomerulonephritis (GN), but its procedure is invasive with a risk of complications. Thus, a non-invasive monitoring method is desirable especially in pediatric patients. Fractalkine and monocyte chemoattractant protein-1 (MCP-1) are proinflammatory chemokines, and both have been reported to be involved in the pathogenesis of immunocomplex-mediated GN. Recently, it has been reported that urinary fractalkine and MCP-1 may serve as possible predictors of disease activity of adult patients with GN. We, therefore, examined whether urinary levels of fractalkine and MCP-1 correlate with clinical and histologic parameters. Twenty-six consecutive children with various types of GN were enrolled in this study, including lupus nephritis, IgA nephropathy, membranous nephropathy, acute GN, and thin basement membrane disease (served as a non-inflammatory control). Urinary fractalkine and MCP-1 concentrations in the first morning urine samples obtained at the time of renal biopsy were measured by enzyme-linked immunosorbent assay, and standardized for urinary creatinine concentrations. Urinary fractalkine concentration differed significantly among the disease categories. Urinary concentrations of fractalkine and MCP-1 showed a significant positive correlation with the degree of occult blood in urine and a significant inverse correlation with the estimated glomerular filtration rate. Furthermore, the urinary MCP-1 concentration was significantly correlated with histological chronicity indices in patients with lupus nephritis and IgA nephropathy. Measurement of urinary fractalkine and MCP-1 concentrations may be useful as a non-invasive method for predicting the disease activity of GN in children.

Long-term tacrolimus-based immunosuppressive treatment for young patients with lupus nephritis: a prospective study in daily clinical practice.

BACKGROUND: The optimal long-term treatment for lupus nephritis (LN) in pubertal patients remains to be determined. Tacrolimus (Tac) inhibits T cell activation, and is therefore expected to be effective in patients with LN. However, little has been published about the long-term efficacy and safety of Tac-based immunosuppressive treatment of young patients with LN in daily clinical practice. METHODS: Nineteen consecutive patients with biopsy-proven LN were recruited for an open-label, prospective, long-term Tac-based treatment regimen. Tac was administered once daily at a dose of 3 mg as induction- or reinduction-maintenance treatment. Four patients (21%) with new-onset LN received mizoribine at a dose of 150 mg once daily in addition to Tac. Treatment outcomes were defined by the European Consensus Lupus Activity Measurement (ECLAM) index, urinary protein/creatinine ratio (Up/cr), serum creatinine and serological lupus markers (complement C3, complement hemolytic activity, CH50, and anti-dsDNA antibody titer). Data on these parameters were collected prospectively. The median follow-up was 42 months. RESULTS: Baseline characteristics of the patients were as follows: mean age, 18 years; Up/cr, 0.89 ± 1.17; serum C3, 68.1 ± 23.2 mg/dl (normal, 79-152 mg/dl); serum CH50, 26.4 ± 10.5 U/ml (normal, 23-46 U/ml); serum anti-dsDNA antibody titer, 69.3 ± 67.5 IU/ml (normal, <12.0 IU/ml); serum creatinine, 0.55 ± 0.18 mg/dl, and ECLAM index, 4.6 ± 1.9. Despite gradually tapering the dose of concomitantly administered prednisolone, a marked improvement compared with baseline values was observed in all outcome measures as early as 3 months after the initiation of treatment, and the favorable changes persisted throughout the treatment period in most of the patients. Sustained improvements in the outcome measures compared with the baseline values were confirmed after a mean of 42 months of treatment: ECLAM index, 1.1 ± 1.1; serum CH50, 36.0 ± 12.8 U/ml, anti-dsDNA antibody titer, 22.5 ± 26.5 IU/ml (all p < 0.01); Up/cr ratio, 0.35 ± 0.58, and serum C3 level, 79.7 ± 17.6 mg/dl (both p < 0.05). Serum creatinine level remained within the normal range in all the study participants. Complete response was achieved in 12 patients (63%), and a partial response was achieved in 5 patients (26%). The remaining 2 patients showed no response. No serious adverse effects were observed. CONCLUSION: The data suggest that long-term, relatively low-dose Tac-based immunosuppressive treatment is beneficial and has low cytotoxicity, and therefore represents an attractive option for the treatment of young patients with LN in daily clinical practice. Further studies involving a larger number of patients are needed to confirm these results.

A novel COL4A5 splicing variant causing X-linked Alport syndrome: A case report.

Alport syndrome is a hereditary disorder characterized by renal impairment, hearing loss, and ocular symptoms and is caused by COL4A3, COL4A4, and COL4A5 mutations. Here, we report the case of 3-year-old boy with isolated hematuria detected in routine preventative urinary screening conducted in 3-year-old children. He carried a novel variant, NM_033380.3:c. 1032 + 1 G > A, which caused a splicing abnormality in COL4A5. He was diagnosed with X-linked Alport syndrome.