Detecting and exploring kidney-derived extracellular vesicles in plasma.

BACKGROUND: Extracellular vesicles (EVs) have received considerable attention as ideal biomarkers for kidney diseases. Most reports have focused on urinary EVs, that are mainly derived from the cells in the urinary tract. However, the detection and the application of kidney-derived EVs in plasma remains uncertain. METHODS: We examined the kidney-derived small EVs (sEVs) in plasma that were supposedly released from renal mesangial and glomerular endothelial cells, using clinical samples from healthy controls and patients with kidney transplants. Plasma from healthy controls underwent ultracentrifugation, followed by on-bead flow cytometry, targeting α8 integrin, an antigen-specific to mesangial cells. To confirm the presence of kidney-derived sEVs in peripheral blood, plasma from ABO-incompatible kidney transplant recipients was ultracentrifuged, followed by western blotting for donor blood type antigens. RESULTS: Immunohistochemistry and immunoelectron microscopy confirmed α8 integrin expression in kidney mesangial cells and their sEVs. The CD9-α8 integrin double-positive sEVs were successfully detected using on-bead flow cytometry. Western blot analysis further revealed transplanted kidney-derived sEVs containing blood type B antigens in non-blood type B recipients, who had received kidneys from blood type B donors. Notably, a patient experiencing graft kidney loss exhibited diminished signals of sEVs containing donor blood type antigens. CONCLUSION: Our findings demonstrate the potential usefulness of kidney-derived sEVs in plasma in future research for kidney diseases.

Low Serum Zinc Concentration Is Associated With Infection Particularly in Patients With Stage 5 Chronic Kidney Disease Medicated with Proton Pump Inhibitors.

OBJECTIVE: Zinc (Zn) plays an important role in immune function. Several studies have identified an association between a Zn deficiency and infection. Infectious diseases are major complications of chronic kidney disease (CKD). We investigated whether serum Zn concentrations are associated with risk of infection in patients with advanced CKD. DESIGN AND METHODS: We retrospectively analyzed data from 299 patients with CKD whose serum Zn values were measured to evaluate anemia between January 2013 and December 2016. Among them, 9 who were supplemented with Zn and 67 who had started urgent dialysis at the time of measurement were excluded. We analyzed infection events, length of infection-related hospitalization and infection-related and all-cause mortality in the remaining 223 patients during a median follow-up of 36 months. We assigned the patients to groups with low or high Zn values (≤50 and >50 µg/dL, respectively) based on a median value of 50 µg/dL. Data were analyzed using Kaplan-Meier curves and Cox hazards models. RESULTS: During a median follow-up of 36 months, 40 patients were hospitalized with infections. The rate of infection-related and long-term hospitalization (>10 days) due to infection was higher for patients with low, than high, Zn values (23.3% vs. 12.6%; P = .042 and 26.2% vs. 12.4%; P = .007, respectively). After adjustment in Cox hazards models, low serum Zn values remained an independent risk factor for infection-related hospitalization (Hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.01-3.71; P = .048), especially for patients on proton pump inhibitor (PPI) medications (HR, 2.66, 95%; CI, 1.22-5.81; P = .014). CONCLUSION: Patients with advanced CKD accompanied by low serum Zn concentration, and particularly those medicated with PPI, are at high risk of infection-related hospitalization, which results in long-term hospitalization.

Quality of life of elderly patients on peritoneal dialysis versus hemodialysis: a single-center study.

BACKGROUND: The number of elderly dialysis patients in Japan is dramatically increasing. Receiving therapy with better satisfaction through home care is one of the important factors in their daily lives. Thus, the quality of life of elderly patients on hemodialysis (HD) or peritoneal dialysis (PD) was evaluated. METHODS: Clinical information of patients aged ≥80 years who started dialysis at our hospital between January 2013 and December 2015 was retrospectively collected. The mortality rate, length of hospitalization, and place of death were identified to evaluate patient quality of life. RESULTS: In total, 56 patients (14 PD and 42 HD) were enrolled. The mean age of study subjects was 85.2 ± 4.0 years. The proportion of PD patients who lived with their family or have professional caregivers who could assist them in their daily life was higher than that of HD patients (100 vs. 76.2%, respectively; p = 0.044). Mortality rate was higher in PD patients than in HD patients (p = 0.003), but long-term hospitalization of >180 days was observed only in HD patients (PD vs. HD: 0.0 vs. 16.7%; p = 0.102). In patients with Barthel index scores <100, the long-term hospitalization difference was significant (PD vs. HD: 0.0 vs. 30.4%; p = 0.040). Of note, 6 of 7 deceased PD patients and 1 of 10 deceased HD patients died at home (p = 0.002). CONCLUSION: PD is a desirable home care therapy for elderly patients, but the burden on caregivers should be considered.

Successful rituximab treatment of TAFRO syndrome with pathological findings of glomerular endothelial damage.

Thrombocytopenia, anasarca, fever, renal insufficiency, and organomegaly constitute TAFRO syndrome, a variant of Castleman disease. We describe a patient with TAFRO syndrome who underwent renal biopsy. A 79-year-old woman was referred to us with fever and leg edema. She also had thrombocytopenia, pleural effusion, ascites, and acute kidney injury, and was admitted to our hospital. Her response to initial therapy with corticosteroid and cyclosporine was poor. Therefore, she received 4 doses of rituximab per week, which resulted in clinical improvement, including recovery of thrombocytopenia. A kidney biopsy thereafter showed diffuse, global glomerular endothelial injury indicating thrombotic microangiopathy (TMA). These findings suggested that TMA is associated with the thrombocytopenia and renal insufficiency of TAFRO syndrome.

Thiamine status in end-stage chronic kidney disease patients: a single-center study.

BACKGROUND: Reportedly, thiamine deficiency, resulting from malnutrition and long-term diuretic therapy, is observed in patients with chronic kidney disease (CKD). The risk of thiamine deficiency might be enhanced, especially in end-stage CKD patients. Here, we assessed thiamine status in incident dialysis patients. METHODS: This study was a single-center cross-sectional study which included 288 consecutive patients initiated into dialysis between April 2013 and March 2017 at our hospital. Thiamine status was evaluated by high-performance liquid chromatography of whole blood samples. We evaluated the association between blood thiamine concentration and other clinical parameters. RESULTS: Of the 288 patients, 21 patients receiving thiamine supplementation at the time of dialysis initiation and 26 patients without blood thiamine measurements were excluded. In 30 patients (12.4%), blood thiamine concentration was lower than the lower limit of normal (21.3 ng/mL; dotted line). Blood thiamine concentration correlated with age, body mass index, and Barthel index (BI) score (p = 0.008, 0.012 and 0.009, respectively). Stepwise multivariate regression analysis indicated that BI scores were independent risk factors for thiamine deficiency (ß coefficients = 0.169, p = 0.013). CONCLUSIONS: The proportion of end-stage CKD patients with low blood thiamine concentration is high. Low physical function (low BI score) is an independent risk factor of thiamine deficiency. Clinicians should be aware of thiamine deficiency in end-stage CKD patients, especially those with low physical function.