Genetic diagnosis of kidney disease by whole exome sequencing and its clinical application.

The genetic spectrum of genetic kidney diseases (GKD) and the application of genetic diagnoses to patient care were assessed by whole exome sequencing (WES) of the DNA of 172 pediatric or adult patients with various kidney diseases. WES diagnosed genetic diseases in 63 (36.6%) patients. The diagnostic yields in patients with glomerulopathy were 33.8% (25/74 pts) due to variants in 10 genes, 58.8% (20/34) in patients with tubulointerstitial disease due to variants in 18 genes, 33.3% (15/45) in patients with cystic disease/ciliopathy due to variants in 10 genes, 18.2% (2/11) in patients with congenital anomalies of the kidneys and urinary tract (CAKUT) due to variants in two genes, and 12.5% (1/8) in patients with end stage kidney disease (ESKD). The diagnosis rate was high in patients aged <1-6 years (46-50.0%), and low in patients aged ≥40 years (9.1%). Renal phenotype was reclassified in 10 (15.9%) of 63 patients and clinical management altered in 10 (15.9%) of 63 patients after genetic diagnosis. In conclusion, these findings demonstrated the diagnostic utility of WES and its effective clinical application in patients, with various kinds of kidney diseases, across the different age groups.

Post-operative recurrence of focal segmental glomerulosclerosis according to pre-transplant treatment after kidney transplantation.

BACKGROUND: Recurrent focal segmental glomerulosclerosis (FSGS) after kidney transplantation (KT) is a serious complication and a significant risk factor for graft failure. However, there is no clear evidence of the effectiveness of pre-transplant treatment using plasmapheresis (PP) or rituximab in preventing post-operative FSGS recurrence after KT. METHODS: This single-center retrospective study included 99 adult patients with biopsy-proven primary FSGS who underwent KT between 2007 and 2018. The patients were divided into the pre-treatment group (N = 53, 53.5%) and no pre-treatment group (N = 46, 46.5%). In the pre-transplant group, prophylactic PP was administered before KT in patients undergoing living donor transplantation and the day after KT in those undergoing deceased donor transplantation. RESULTS: The rate of immediate post-operative recurrence was significantly higher in the no pre-treatment group (16 [34.8%]) than in the pre-treatment group (5 [9.4%]; P = 0.002). There were three cases of graft failure due to recurrent FSGS, all of which were in the no pre-treatment group. After adjusting for possible confounding factors, age (per 10-year increase; OR = 0.61, CI, 0.42-0.90; P = 0.012) and pre-transplant treatment (vs. no pre-transplant treatment; OR = 0.17, CI, 0.05-0.54; P = 0.003) were identified as significant factors associated with FSGS recurrence. The rate of death-censored graft survival was significantly superior in the pretransplant treatment group (P = 0.042). CONCLUSION: Pre-transplant treatment with PP was associated with beneficial effects on preventing FSGS recurrence after KT.

ABO-incompatible kidney transplantation can be successfully conducted by monitoring IgM isoagglutinin titers during desensitization.

BACKGROUND: Recent advances in desensitization techniques and immunosuppressive therapy have led to improved outcomes after ABO-incompatible (ABO-i) kidney transplantation (KT). However, questions remain unanswered, particularly regarding which type of ABO isoagglutinin-immunoglobulin M (IgM) or immunoglobulin M (IgG)-is significantly involved in antibody-mediated rejection (AMR). STUDY DESIGN AND METHODS: We retrospectively analyzed data from 120 patients who underwent ABO-i KT between 2012 and 2014. Preoperative plasma exchange was performed until the IgM isoagglutinin titer was 4 or less, regardless of the IgG titer. Clinical data were compared between patient groups with pre-KT IgG isoagglutinin titer 16 or greater (high IgG; titer range, 16-256; n = 39) and 8 or less (low IgG; titer range, -8; n = 81). RESULTS: The median follow-up periods were 59 (high IgG) and 55 (low IgG) months. Patient survival at 5 years (p = 0.314) was 100% (high IgG) and 97.4% (low IgG). Graft survival at 5 years (p = 0.480) was 100% (high IgG) and 98.7% (low IgG). AMR by anti-ABO antibody occurred in only one patient in the low-IgG group. CONCLUSION: Patients with high pre-KT IgG isoagglutinin titers had equally successful outcomes as those with low IgG titers. ABO-i KT can be successfully performed by reducing the pre-KT IgM isoagglutinin titer to 4 or less, as determined by the immediate spin tube method.

Pneumocystis pneumonia occurrence and prophylaxis duration in kidney transplant recipients according to perioperative treatment with rituximab.

BACKGROUND: Pneumocystis pneumonia (PCP) is a life-threatening fungal infection that can occur in kidney transplantation (KT) recipients. A growing number of KT recipients are receiving perioperative treatment with rituximab, which is associated with prolonged B-cell depletion and possible risk of PCP occurrence; however, the optimal prophylaxis duration according to rituximab treatment is yet unknown. We compared the occurrence of PCP and the duration of prophylaxis in KT recipients according to rituximab treatment. METHODS: We retrospectively analyzed 2110 patients who underwent KT between January 2009 and December 2016, who were divided into non-Rituximab group (n = 1588, 75.3%) and rituximab group (n = 522, 24.7%). RESULTS: In the rituximab group, the estimated number needed to treat (NNT) for prophylaxis prolongation from 6 to 12 months was 29.0 with a relative risk reduction of 90.0%. In the non-rituximab group, the estimated NNT value was 133.3 and the relative risk reduction was 66.4%. Rituximab treatment (hazard ratio (HR) = 3.09; P <  0.01) and acute rejection (HR = 2.19; P = 0.03) were significant risk factors for PCP in multivariate analysis. CONCLUSIONS: Our results suggest that maintaining PCP prophylaxis for 12 months may be beneficial in KT recipients treated with rituximab for desensitization or acute rejection treatment.

Glomerular crescents are associated with worse graft outcome in allograft IgA nephropathy.

The prognosis of patients with allograft IgA nephropathy (IgAN) requires further investigation. We performed a bicenter retrospective cohort study on kidney transplant recipients diagnosed with IgAN in allograft biopsy. Recipients without allograft IgAN but with known IgAN before transplantation were included as the control group. We investigated the associations between clinicopathological characteristics, including allograft crescents, and the risk of death-censored graft failure. In total, 1256 IgAN patients in both pre- and posttransplant stages were included. Among them, 559 were diagnosed with allograft IgAN, which was a time-dependent risk factor for worse prognosis (adjusted hazard ratio = 5.009 [3.610-6.951]; P < .001) during a median of 8.1 years of follow-up. Of the patients with allograft IgAN, 88 (15.9%) had glomerular crescents, including 40 patients (7.2%) with >10% crescent formation in the total biopsied glomeruli. The presence of glomerular crescents in IgAN was associated with a worse graft prognosis, and the association was still valid with the C scores of the current Oxford classification. In conclusion, allograft IgAN is a time-dependent event and is associated with worse graft outcomes. The pathological characteristics of allograft, particularly the degree of glomerular crescent formation, may represent important risk factors for a poor prognosis.

Clinical importance of the updated Oxford classification in allograft IgA nephropathy.

With the recent update to the Oxford classification for allograft IgA nephropathy (IgAN), additional investigations on the clinical significance of the updated components are warranted. We performed a retrospective cohort study at two tertiary hospitals. Kidney transplant recipients diagnosed with allograft IgAN were included in the study after additional review by specialized pathologists. We applied the updated Oxford classification and determined the MEST-C scores of the patients. The main study outcome was death-censored graft failure within 10 years after the establishment of allograft IgAN diagnosis and was assessed using the Cox regression analysis. Three hundred thirty-three allograft IgAN patients were reviewed: 100 patients with confirmed native IgAN and 233 patients with other, clinical, or unknown primary causes for end-stage renal disease (ESRD). The updated Oxford classification for allograft IgAN demonstrated prognostic value for graft failure, and patients with multiple MEST-C components had worse outcomes. M, E, S, and C were significantly associated with the prognosis of recurred IgAN and T was the only independent prognostic parameter for allograft IgAN without confirmed native IgAN. Therefore, we suggest reporting MEST-C scores in allograft biopsies and careful interpretation of the results according to the primary cause of ESRD.

Arginine vasopressin attenuates the effects of TNF-α in aortic endothelial cells by inducing ectodomain shedding of TNF receptor 1.

In septic shock, arginine vasopressin (AVP) is commonly used as a vasopressor to restore blood pressure. Exogenous AVP may have anti-inflammatory effects as well. We investigated whether AVP modulates the effects of tumor necrosis factor-α (TNF-α) in human aortic endothelial cells (HAECs). TNF-α stimulated intercellular adhesion molecule-1 expression, while AVP pretreatment attenuated this effect of TNF-α. Upon treatment with AVP, extracellular Ca2+ entered the cells rapidly through L-type calcium channels, which in turn induced cell surface translocation of a disintegrin and metalloprotease 10 (ADAM10) and ectodomain shedding of tumor necrosis factor receptor 1 (TNFR1). On the other hand, siRNA depletion of ADAM10 suppressed AVP-induced ectodomain shedding of TNFR1 and eliminated the inhibitory effect of AVP against TNF-α. Depletion of oxytocin receptor also abolished AVP-induced extracellular Ca2+ influx, AVP-induced ectodomain shedding of TNFR1 and the inhibitory effect of AVP against TNF-α. These findings suggest that AVP decreases the responsiveness of HAECs to TNF-α by inducing ADAM10-dependent ectodomain shedding of TNFR1. Extracellular Ca2+ influx through L-type calcium channels was essential for ADAM10 activation. This effect of AVP was mediated through the oxytocin receptor.

The results of HLA-incompatible kidney transplantation according to pre-transplant crossmatch tests: Donor-specific antibody as a prominent predictor of acute rejection.

BACKGROUND: Crossmatching (XM) between organ donors and recipients is correlated with clinical outcomes. This study evaluates the results of HLA-incompatible kidney transplant (HLA-i KT) according to pre-transplant XM modalities. METHODS: This study included 731 consecutive patients. HLA-i KT was defined as a transplant under conditions of complement-dependent cytotoxicity (CDC) XM positivity, flow-cytometric XM (FCXM) positivity, and/or maximal donor-specific antibody (DSA) mean fluorescence intensity (MFI) ≥5000. RESULTS: The incidence of antibody-mediated rejection (AMR) within 1 year after transplant was significantly higher in the HLA-i group than in the HLA compatible (HLA-c) group (15 vs 9 patients, 14.2% vs 1.4%; P < 0.01). Multivariate analysis indicated that a DSA MFI ≥5000 (odds ratio [OR] = 2.63; 95% confidence interval [CI], 1.00-6.98; P = 0.05) was significantly associated with acute rejection (AR), whereas CDC (OR = 2.09; 95% CI, 0.55-7.99; P = 0.28) and FCXM positivity (OR = 2.07; 95% CI, 0.73-5.87; P = 0.17) were not. Similarly, DSA MFI ≥ 5000 (OR = 4.14; P = 0.02) was the only significant factor affecting the risk of AMR. CONCLUSIONS: Of the various XM tests, DSA MFI ≥5000 was the most prominent predictor of AR in patients undergoing HLA-i KT.

Clinical Significance of Crescent Formation in IgA Nephropathy - a Multicenter Validation Study.

BACKGROUND/AIMS: Additional validation study was warranted to confirm the clinical significance of C score, which was recently added to the Oxford classification for immunoglobulin A nephropathy (IgAN). METHODS: We performed a multicenter retrospective cohort study in four hospitals in Korea. Patients who had biopsied glomeruli less than eight or inadequate follow-up information were excluded. Clinicopathologic parameters, including the degree of cellular or fibrocellular crescents, were collected and included in multivariable models for Cox regression analysis. The main outcome was a composite renal outcome, defined as a merge of progression to end-stage renal disease (ESRD) and halving of estimated glomerular filtration rate (eGFR) from baseline. RESULTS: Among included 3,380 biopsy-confirmed IgAN patients, there were 664 (19.6%) patients with C1 and 60 (1.8%) patients with C2 scores in the study population. Although C0 and C1 patients shared similar baseline characteristics, C2 patients frequently had more clinicopathologic risk factors for poor prognosis of IgAN. Both C1 [adjusted HR 1.33 (1.11-1.58), P=0.002] and C2 [adjusted HR 2.24 (1.46-3.43), P< 0.001] scores were associated with an increased risk of the composite outcome. C2 was a strong predictive parameter associated with both progression to ESRD and halving of eGFR, whereas C1 was mainly associated with the increased risk of halving of eGFR. Notably, the proportion of crescent showed a linear association with the risk of adverse renal outcome. CONCLUSION: The C score in the Oxford classification is a valid predictive parameter for IgAN prognosis. Additional clinical attention is necessary for IgAN patients with identified cellular or fibrocellular crescents.

Clinical significance of isoagglutinin titre with the current desensitization protocol in ABO-incompatible kidney transplantation.

AIM: ABO-incompatible (ABOi) kidney transplantation (KT) has become a routine procedure with graft survival rates comparable to those of ABO-compatible KT. However, the clinical significance of the isoagglutinin titre in ABOi KT remains uncertain. Therefore, in this study, we analysed the clinical outcomes of ABOi KT according to the baseline and post-operative isoagglutinin titre. METHODS: All patients who received ABOi KT between 2009 and 2013 were reviewed and followed up until December 2016. The patients were classified according to baseline (<1:128 or ≥1:128) and post-operative rebound isoagglutinin titre (<1:16 or ≥1:16), and the clinical outcomes of KT were compared. RESULTS: Patients with a high baseline isoagglutinin titre showed a poor titre reduction rate (1.48 ± 0.41 vs 1.32 ± 0.34, P = 0.008), and more patients experienced titre rebound ≥1:16 after KT (15.0% vs 35.8%, P = 0.002). The occurrence of both T-cell-mediated rejection and antibody-mediated rejection did not show a significant difference (P = 0.805 and 0.714, respectively). The rate of rejection-free survival was not different among groups (P = 0.680, log-rank test). Furthermore, the rate of death-censored graft survival was not different among groups (P = 0.701, log-rank test). Urinary tract infection was the most frequently reported infectious complication overall. The incidence of urinary tract infection, pneumonia and viral infections (BK virus and cytomegalovirus) was not different among groups. CONCLUSION: In conclusion, high baseline isoagglutinin titre was associated with a high rebound isoagglutinin titre, low titre reduction rates and more sessions of plasmapheresis. However, the isoagglutinin titre may not be as important as it was in the past in ABOi KT if appropriate desensitization is performed.

Usefulness of mid-week hemoglobin measurement for anemia management in patients undergoing hemodialysis: a retrospective cohort study.

BACKGROUND: Short-term hemoglobin (Hb) variability related to volume status is observed in chronic kidney disease (CKD) patients receiving hemodialysis (HD). Given the lack of studies regarding outcomes according to the day of Hb sampling, the existing guidelines do not strongly recommend regarding measurement timing. Pre-dialysis mid-week sampling (Wednesday and Thursday) is preferable to minimize short-term Hb variability, although numerous HD centers perform early-week sampling (Monday and Tuesday). The different measurement days may influence the prescribed dose of erythropoiesis-stimulating agent (ESA) and related patient outcomes. We investigated changes in Hb levels and ESA doses according to the Hb measurement day among HD patients. METHODS: Starting September 2013, the day for pre-dialysis Hb measurement at the Asan Medical Center was changed from early-week days to mid-week days. This single-center retrospective study evaluated medical records of 92 patients who received maintenance HD between September 2012 and August 2014. RESULTS: There was no significant difference in the mean Hb levels between early-week days and mid-week days (10.71 ± 0.06 g/dL vs. 10.78 ± 0.47 g/dL, p = 0.105). However, the mean doses of darbepoetin-α on early-week days were higher than those on mid-week days (175.4 ± 72.5 µg/month vs. 163.7 ± 83.6 µg/month, p = 0.022). The mean doses of intravenous iron hydroxide sucrose for early-week measurements were also higher than those for mid-week measurements (623.0 ± 489.0 mg/year vs. 447.0 ± 505.2 mg/year, p = 0.001). The mean interdialytic weight gains were 2.81 ± 0.82 kg on early-week days and 1.99 ± 0.61 kg on mid-week days (p < 0.001). CONCLUSIONS: Compared with early-week measurements, mid-week pre-dialysis Hb measurements were significantly associated with lower ESA doses without a change in Hb levels.

Possible beneficial association between renin-angiotensin-aldosterone-system blockade usage and graft prognosis in allograft IgA nephropathy: a retrospective cohort study.

BACKGROUND: Although immunoglobulin A nephropathy (IgAN) is associated with an increased risk of renal allograft failure, evidences for its treatment, including renin-angiotensin-aldosterone system blockade (RAASB) usage, remain limited. METHODS: In this bi-center retrospective cohort study, we included patients who were recently diagnosed with IgAN through allograft biopsies. We identified their 6-month antihypertensive medication prescriptions and investigated the association between the medication types, albuminuria changes, and risk of 5-year death-censored-graft-failure (DCGF). The mixed effect model and cox regression analysis were used. RESULTS: A total of 464 allograft IgAN patients were included: 272, 38, 33, and 121 patients in the no antihypertensive medication, single agent RAASB, single agent beta blocker (BB)/calcium channel blocker (CCB), and combination therapy groups, respectively. High-degree albuminuria after 6 months of allograft IgAN diagnosis was an important prognostic parameter and a partial mediator for the association between the subgroups and 5-year DCGF. The usage of single RAASB was associated with decrement of albuminuria from allograft IgAN diagnosis (P for interaction = 0.03). The single BB/CCB group demonstrated significantly worse prognosis than the single RAASB group (adjusted hazard ratio, 2.76 [1.09-6.98]; P = 0.03). CONCLUSIONS: In conclusion, RAASB may be beneficial for graft prognosis in early allograft IgAN patients who require single antihypertensive medication therapy, by means of reducing albuminuria. Further investigation of treatment strategy in allograft IgAN is warranted.

Ectodomain Shedding of RAGE and TLR4 as a Negative Feedback Regulation in High-Mobility Group Box 1-Activated Aortic Endothelial Cells.

BACKGROUND/AIMS: High-mobility group box 1 (HMGB1) elicits inflammatory responses through interactions with the receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4). We investigated how RAGE and TLR4 expressions are regulated after HMGB1 stimulation in cultured human aortic endothelial cells (HAECs). METHODS: RAGE and TLR4 expressions were analyzed by Western blot analysis and immunofluorescence staining. A disintegrin and metalloprotease 17 (ADAM17) activity was measured using a fluorogenic substrate. RESULTS: Upon treatment with HMGB1, both RAGE and TLR4 began to decrease in cell lysate and remained decreased up to 24 h. The decrease in cellular RAGE and TLR4 was accompanied by an increase of N-terminal fragment of RAGE and TLR4 in culture supernatant, indicating ectodomain shedding of the receptors. HMGB1 activated p38 mitogen-activated protein kinase (p38 MAPK) and ADAM17, while HMGB1-induced ADAM17 activation was inhibited by SB203580, a p38 MAPK inhibitor. HMGB1-induced ectodomain shedding of RAGE and TLR4 was prevented by siRNA depletion of ADAM17 as well as TAPI-2, an inhibitor of ADAM family, and SB203580. HMGB1 pretreatment abolished p38 MAPK activation in response to 2nd HMGB1 stimulation. In the cells depleted of ADAM17, HMGB1-induced p38 MAPK activation was prolonged. siRNA depletion of RAGE, but not TLR4, suppressed HMGB1-induced p38 MAPK activation. CONCLUSION: In response to HMGB1 stimulation, HAECs rapidly undergo ectodomain shedding of RAGE and TLR4, and thereby become insensitive to further HMGB1 stimulation. ADAM17, activated through RAGE-p38 MAPK pathway, is implicated in the ectodomain cleavage of the receptors.

ADAM17-Mediated Ectodomain Shedding of Toll-Like Receptor 4 as a Negative Feedback Regulation in Lipopolysaccharide-Activated Aortic Endothelial Cells.

BACKGROUND/AIMS: Lipopolysaccharide (LPS)-activated monocytes/macrophages develop endotoxin tolerance in part by reducing cell surface toll-like receptor 4 (TLR4) through cluster of differentiation 14 (CD14)-dependent endocytosis. In case of endothelial cells, CD14 is expressed in low copy numbers as compared with monocytes/macrophages. Thus, we explored how endothelial cells regulate TLR4 expression after LPS stimulation. METHODS: Cultured human aortic endothelial cells (HAECs) were treated with LPS. TLR4 expression was analyzed by Western blot analysis and immunofluorescence staining. A disintegrin and metalloprotease 17 (ADAM17) activity was measured using a fluorescent substrate. RESULTS: TLR4 in cell lysate began to decrease within 30 min of LPS treatment with a maximal reduction at 2 h, and it was accompanied by an increase of N-terminal fragment of TLR4 in culture supernatant, indicating ectodomain shedding of the receptor. LPS activated p38 mitogen-activated protein kinase (p38 MAPK) and ADAM17, while LPS-induced ADAM17 activation was inhibited by SB203580, a p38 MAPK inhibitor. LPS-induced ectodomain shedding of TLR4 was attenuated by siRNA depletion of ADAM17 as well as TAPI-2 (an inhibitor of ADAM family) and SB203580. LPS pretreatment resulted in a blunted response of p38 MAPK activation to further LPS stimulation. In the cells depleted of ADAM17, LPS-induced p38 MAPK activation was prolonged and LPS-induced intercellular adhesion molecule-1 expression was potentiated. CONCLUSION: HAECs respond to LPS by rapid shedding of the ectodomain of TLR4 and thereby reduce the responsiveness to subsequent LPS exposure. ADAM17, downstream of p38 MAPK, is implicated in the ectodomain cleavage of TLR4.

Pregnancy in women with immunoglobulin A nephropathy: are obstetrical complications associated with renal prognosis?

Background: Recent studies regarding immunoglobulin A nephropathy (IgAN) suggest no relationship between pregnancy and disease progression, although complicated pregnancies and impaired renal function are closely related. Methods: This study used a propensity-score-matched cohort analysis. Among biopsy-confirmed IgAN women in three hospitals in Korea, those who experienced pregnancy after their diagnosis were included in the study group. Renal outcome was the composite of serum creatinine doubling, estimated glomerular filtration rate (eGFR) halving and events of end-stage renal disease. Pregnancies with preterm birth, low birth weight and pre-eclampsia were defined as complicated. Results: Overall, 59 IgAN women who became pregnant after their diagnosis, and the same number of IgAN women who did not experience pregnancy were included in the control group. Although pregnancy itself did not worsen renal outcomes [adjusted hazard ratio (HR): 1.51; 95% confidence interval (CI) 0.57-4.01; P = 0.41], mothers with complicated pregnancies experienced worse renal prognosis, even after adjustment for baseline and pre-gestational characteristics (adjusted HR: 5.07; 95% CI 1.81-14.22; P = 0.002). Moreover, this relationship was only significant in mothers with decreased renal function (eGFR <60 mL/min/1.73 m2) (adjusted HR: 18.70; 95% CI 1.63-214.40; P = 0.02), baseline hypertension (adjusted HR: 4.17; 95% CI 1.13-15.33; P = 0.03) and overt proteinuria (≥1 g/day) (adjusted HR: 4.21; 95% CI 1.24-14.27; P = 0.02). In contrast, patients who experienced pregnancies without complications showed better renal outcomes than did those without post-biopsy pregnancy (P = 0.01). Conclusion: Obstetric complications in patients with high renal risk, rather than pregnancy itself, are associated with renal progression of IgAN women.

Impact of pretransplant donor-specific antibodies on kidney allograft recipients with negative flow cytometry cross-matches.

The Luminex test can detect low levels of donor-specific antibody (DSA) that cannot be detected by flow-cytometric cross-matching (FCXM) in kidney transplantation (KT). This study evaluated the impact of DSA on clinical outcomes in KT recipients negative on FCXM. Of 575 consecutive patients who underwent living donor KT between January 2013 and July 2016, 494 (85.9%) were DSA-negative and 81 (14.1%) were DSA-positive. Although rates of acute cellular rejection (ACR) at 1 year were similar in the 2 groups (P = .54), the incidence of antibody-mediated rejection (ABMR) was significantly higher in the DSA-positive group (P < .01). There was no statistically significant association between rejection-free graft survival (RFGS) rates and pretransplant class I DSA. However, evaluation of pretransplant class II DSA showed that RFGS rates were significantly lower in patients with mean fluorescence intensity (MFI) >3000 than in patients with DSA-negative (P < .01). On multivariate analyses, class II DSA MFI ≥5000 was a significant risk factor for acute rejection (hazard ratio, 7.48; P < .01). These findings suggested that pretransplant DSA alone did not affect graft survival in KT recipients without desensitization. However, class II DSA MFI >5000 was an independent predictor of acute rejection in DSA-positive patients.

Metabolic Acidosis and Long-Term Clinical Outcomes in Kidney Transplant Recipients.

Metabolic acidosis (MA), indicated by low serum total CO2 (TCO2) concentration, is a risk factor for mortality and progressive renal dysfunction in CKD. However, the long-term effects of MA on kidney transplant recipients (KTRs) are unclear. We conducted a multicenter retrospective cohort study of 2318 adult KTRs, from January 1, 1997 to March 31, 2015, to evaluate the prevalence of MA and the relationships between TCO2 concentration and clinical outcomes. The prevalence of low TCO2 concentration (<22 mmol/L) began to increase in KTRs with eGFR<60 ml/min per 1.73 m2 and ranged from approximately 30% to 70% in KTRs with eGFR<30 ml/min per 1.73 m2 Multivariable Cox proportional hazards models revealed that low TCO2 concentration 3 months after transplant associated with increased risk of graft loss (hazard ratio [HR], 1.74%; 95% confidence interval [95% CI], 1.26 to 2.42) and death-censored graft failure (DCGF) (HR, 1.66; 95% CI, 1.14 to 2.42). Cox regression models using time-varying TCO2 concentration additionally demonstrated significant associations between low TCO2 concentration and graft loss (HR, 3.48; 95% CI, 2.47 to 4.90), mortality (HR, 3.16; 95% CI, 1.77 to 5.62), and DCGF (HR, 3.17; 95% CI, 2.12 to 4.73). Marginal structural Cox models adjusted for time-varying eGFR further verified significant hazards of low TCO2 concentration for graft loss, mortality, and DCGF. In conclusion, MA was frequent in KTRs despite relatively preserved renal function and may be a significant risk factor for graft failure and patient mortality, even after adjusting for eGFR.

Diosgenin, an Activator of 1,25D3-MARRS Receptor/ERp57, Attenuates the Effects of TNF-α by Causing ADAM10-Dependent Ectodomain Shedding of TNF Receptor 1.

BACKGROUND/AIMS: We investigated how diosgenin, a steroidal sapogenin, has anti-tumor necrosis factor-α (TNF-α) effects in human aortic endothelial cells (HAECs). METHODS: Tumor necrosis factor receptor 1 (TNFR1) was assessed by Western blot analysis. Intracellular Ca2+ was measured using Fluo-4 AM. Immunofluorescence staining was performed for a disintegrin and metalloprotease 10 (ADAM10). RESULTS: Diosgenin (1 ∼ 100 nM) induced ectodomain shedding of TNFR1 within 30 min and attenuated TNF-α-induced intercellular adhesion molecule-1 (ICAM-1) expression. Upon treatment with diosgenin, extracellular Ca2+ entered into the cells via L-type calcium channels, whereas diosgenin-induced ectodomain shedding of TNFR1 was almost completely inhibited by BAPTA-AM (intracellular Ca2+ chelator), verapamil (L-type calcium channel antagonist) and the absence of extracellular Ca2+. Diosgenin caused translocation of ADAM10 to the cell surface, which was mediated by extracellular Ca2+ influx. Depletion of ADAM10 prevented diosgenin-induced ectodomain shedding of TNFR1 and abolished the inhibitory effect of diosgenin on TNF-α-induced ICAM-1 expression. Diosgenin did not induce extracellular Ca2+ influx and ectodomain shedding of TNFR1 in cells depleted of 1,25D3-membrane associated rapid response steroid-binding receptor (1,25D3-MARRS receptor/ERp57). CONCLUSION: Diosgenin elicits L-type calcium channel-mediated extracellular Ca2+ influx, and thereby induces ADAM10-mediated ectodomain shedding of TNFR1. This effect of diosgenin was exerted through 1,25D3-MARRS receptor/ERp57.

1,25-Dihydroxyvitamin D3 Attenuates the Effects of Lipopolysaccharide by Causing ADAM10-Dependent Ectodomain Shedding of Toll-Like Receptor 4.

BACKGROUND/AIMS: We investigated how 1,25-dihydroxyvitamin D3 (1,25D3) inhibits the effects of lipopolysaccharide (LPS) in human aortic endothelial cells. METHODS: Cellular signaling was explored by determination of protein abundance with Western blot, measurement of cytosolic Ca2+ concentration and immunofluorescence staining for a disintegrin and metalloprotease 10 (ADAM10). RESULTS: LPS stimulated the expression of intercellular adhesion molecule 1 (ICAM-1) through toll-like receptor 4 (TLR4) and subsequent activation of p38 mitogen-activated protein kinase (p38 MAPK). Pretreatment with 1,25D3 attenuated LPS-induced p38 MAPK activation and ICAM-1 expression by causing ectodomain shedding of TLR4. This effect of 1,25D3 depended on its ability to induce a rapid extracellular Ca2+ influx through L-type calcium channels because the ectodomain shedding was prevented by the absence of extracellular Ca2+ or the presence of verapamil. TLR4 ectodomain shedding was also induced by Bay K8644 (L-type calcium channel agonist). Both 1,25D3 and Bay K8644 caused extracellular Ca2+ influx-dependent ADAM10 translocation to the cell surface. Depletion of ADAM10 by siRNA transfection prevented 1,25D3- and Bay K8644-induced ectodomain shedding of TLR4, and abolished the inhibitory effect of 1,25D3 on LPS-induced ICAM-1 expression. CONCLUSION: 1,25D3 causes ectodomain shedding of TLR4 and thereby decreases the responsiveness of cells to LPS. ADAM10, activated by extracellular Ca2+ influx, was implicated in the ectodomain cleavage of TLR4.

Risk factors and long-term outcomes of parvovirus B19 infection in kidney transplant patients.

BACKGROUND: Parvovirus B19 is a small, non-enveloped, single-stranded DNA virus with a special affinity for the erythroid progenitor cells of the bone marrow. The first case of parvovirus B19 infection in a kidney transplant recipient (KTR) was reported in 1986. Data on the risk factors and specific clinical characteristics of parvovirus B19 infection remain insufficient. METHODS: We screened 602 KTRs for parvovirus B19 infection using parvovirus B19 polymerase chain reaction (PCR) from January 1990 to April 2016, and the clinical characteristics of patients with positive results were compared to those of age- and gender-matched patients with negative PCR results. RESULTS: A total of 39 KTRs tested positive for parvovirus B19, and they were compared to 78 age- and gender-matched patients among 563 KTRs who had negative PCR results. In all, 89.7% of positive cases were reported within the first year after kidney transplantation. In multivariate analyses, deceased-donor kidney transplantation (odds ratio [OR] 9.067, 95% confidence interval [CI] 1.668-49.275, P = .011), use of tacrolimus (OR 3.607, 95% CI 1.024-12.706, P = .046), PCR test within 1 year of kidney transplantation (OR 12.456, 95% CI 2.674-58.036, P = .001), and hemoglobin levels (OR 0.559, 95% CI 0.351-0.889, P = .014) showed significant correlations with parvovirus B19 infection. Graft survival did not differ between the two groups during the follow-up period of 111.68 ± 54.54 months (P = .685 by log-rank test). CONCLUSION: The identification of factors related to positive parvovirus B19 PCR results may promote the early detection of parvovirus B19 infection. Further studies are needed to elucidate the characteristics of parvovirus B19 infection in kidney transplantation.