Effectiveness of DialBetesPlus, a self-management support system for diabetic kidney disease: Randomized controlled trial

We evaluated the effectiveness of a mobile health (mHealth) intervention for diabetic kidney disease patients by conducting a 12-month randomized controlled trial among 126 type 2 diabetes mellitus patients with moderately increased albuminuria (urinary albumin-to-creatinine ratio (UACR): 30-299 mg/g creatinine) recruited from eight clinical sites in Japan. Using a Theory of Planned Behavior (TPB) behavior change theory framework, the intervention provides patients detailed information in order to improve patient control over exercise and dietary behaviors. In addition to standard care, the intervention group received DialBetesPlus, a self-management support system allowing patients to monitor exercise, blood glucose, diet, blood pressure, and body weight via a smartphone application. The primary outcome, change in UACR after 12 months (used as a surrogate measure of renal function), was 28.8% better than the control group's change (P = 0.029). Secondary outcomes also improved in the intervention group, including a 0.32-point better change in HbA1c percentage (P = 0.041). These improvements persisted when models were adjusted to account for the impacts of coadministration of drugs targeting albuminuria (GLP-1 receptor agonists, SGLT-2 inhibitors, ACE inhibitors, and ARBs) (UACR: -32.3% [95% CI: -49.2%, -9.8%] between-group difference in change, P = 0.008). Exploratory multivariate regression analysis suggests that the improvements were primarily due to levels of exercise. This is the first trial to show that a lifestyle intervention via mHealth achieved a clinically-significant improvement in moderately increased albuminuria.

ATP2B1 gene polymorphisms associated with resistant hypertension in the Japanese population

Single-nucleotide polymorphisms (SNP) of ATP2B1 gene are associated with essential hypertension but their association with resistant hypertension (RHT) remains unexplored. The authors examined the relationship between ATP2B1 SNPs and RHT by genotyping 12 SNPs in ATP2B1 gene of 1124 Japanese individuals with lifestyle-related diseases. Patients with RHT had inadequate blood pressure (BP) control using three antihypertensive drugs or used ≥4 antihypertensive drugs. Patients with controlled hypertension had BP controlled using ≤3 antihypertensive drugs. The association between each SNP and RHT was analyzed by logistic regression. The final cohort had 888 (79.0%) and 43 (3.8%) patients with controlled hypertension and RHT, respectively. Compared with patients homozygous for the minor allele of each SNP in ATP2B1, a significantly higher number of patients carrying the major allele at 10 SNPs exhibited RHT (most significant at rs1401982: 5.8% vs. 0.8%, p = .014; least significant at rs11105378: 5.7% vs. 0.9%, p = .035; most nonsignificant at rs12817819: 5.1% vs. 10%, p = .413). After multivariate adjustment for age, sex, systolic BP, and other confounders, the association remained significant for rs2681472 and rs1401982 (OR: 7.60, p < .05 and OR: 7.62, p = .049, respectively). Additionally, rs2681472 and rs1401982 were in linkage disequilibrium with rs11105378. This study identified two ATP2B1 SNPs associated with RHT in the Japanese population. rs1401982 was most closely associated with RHT, and major allele carriers of rs1401982 required significantly more antihypertensive medications. Analysis of ATP2B1 SNPs in patients with hypertension can help in early prediction of RHT and identification of high-risk patients who are more likely to require more antihypertensive medications.

Efficacy of StepAdd, a Personalized mHealth Intervention Based on Social Cognitive Theory to Increase Physical Activity Among Patients With Type 2 Diabetes Mellitus: Protocol for a Randomized Controlled Trial

BACKGROUND

Increasing physical activity improves glycemic control in patients with type 2 diabetes (T2D). Mobile health (mHealth) interventions have been proven to increase exercise, but engagement often fades with time. As the use of health behavior theory in mHealth design can increase effectiveness, we developed StepAdd, an mHealth intervention based on the constructs of social cognitive theory (SCT). StepAdd improves exercise behavior self-efficacy and self-regulation through the use of goal-setting, barrier-identifying, and barrier-coping strategies, as well as automatic feedback functions. A single-arm pilot study of StepAdd among 33 patients with T2D showed a large increase in step count (mean change of 4714, SD 3638 daily steps or +86.7%), along with strong improvements in BMI (mean change of -0.3 kg/m2) and hemoglobin A1c level (mean change of -0.79 percentage points).

OBJECTIVE

In this study, we aim to investigate the efficacy and safety of StepAdd, an mHealth exercise support system for patients with T2D, via a large, long, and controlled follow-up to the pilot study.

METHODS

This is a randomized, open-label, multicenter study targeting 160 patients with T2D from 5 institutions in Japan with a 24-week intervention. The intervention group will record daily step counts, body weight, and blood pressure using the SCT-based mobile app, StepAdd, and receive feedback about these measurements. In addition, they will set weekly step count goals, identify personal barriers to walking, and define strategies to overcome these barriers. The control group will record daily step counts, body weight, and blood pressure using a non-SCT-based placebo app. Both groups will receive monthly consultations with a physician who will advise patients regarding lifestyle modifications and use of the app. The 24-week intervention period will be followed by a 12-week observational period to investigate the sustainability of the intervention's effects. The primary outcome is between-group difference in the change in hemoglobin A1c values at 24 weeks. The secondary outcomes include other health measures, measurements of steps, measurements of other behavior changes, and assessments of app use. The trial began in January 2023 and is intended to be completed in December 2025.

RESULTS

As of September 5, 2023, we had recruited 44 patients. We expect the trial to be completed by October 8, 2025, with the follow-up observation period being completed by December 31, 2025.

CONCLUSIONS

This trial will provide important evidence about the efficacy of an SCT-based mHealth intervention in improving physical activities and glycemic control in patients with T2D. If this study proves the intervention to be effective and safe, it could be a key step toward the integration of mHealth as part of the standard treatment received by patients with T2D in Japan.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (JRCT) jRCT2032220603; https://rctportal.niph.go.jp/en/detail?trial_id=jRCT2032220603.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/53514.

Omega-3 Fatty Acids Reduce Remnant-like Lipoprotein Cholesterol and Improve the Ankle-Brachial Index of Hemodialysis Patients with Dyslipidemia: A Pilot Study

Background and Objectives: Omega-3 fatty acids have potent lipid-lowering and antiplatelet effects; however, randomized controlled trials have yet to examine the effect of high-dose omega-3 fatty acid administration on peripheral artery disease (PAD) in hemodialysis patients with dyslipidemia. Therefore, this study aimed to evaluate the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the ankle-brachial index (ABI) and remnant-like lipoprotein cholesterol (RLP-C) levels, which are indicators of PAD severity. Materials and Methods: Thirty-eight participants (mean age: 73.6 ± 12.7 years) were randomly assigned using stratified block randomization to either conventional therapy alone or conventional therapy supplemented with high-dose EPA/DHA (EPA: 1860 mg; DHA: 1500 mg) for a three-month intervention period. Patients in the conventional therapy alone group who opted to continue were provided with a low-dose EPA/DHA regimen (EPA: 930 mg; DHA: 750 mg) for an additional three months. The baseline and 3-month values for RLP-C, an atherogenic lipid parameter, and the ABI were recorded. Results: The results of the 3-month assessments revealed that the mean RLP-C changes were -3.25 ± 3.15 mg/dL and 0.44 ± 2.53 mg/dL in the EPA/DHA and control groups, respectively (p < 0.001), whereas the changes in the mean ABI values were 0.07 ± 0.11 and -0.02 ± 0.09 in the EPA/DHA and control groups, respectively (p = 0.007). In the EPA/DHA group, a significant negative correlation was found between the changes in RLP-C levels and the ABI (r = -0.475, p = 0.04). Additionally, the change in the RLP-C levels independently influenced the change in the ABI in the EPA/DHA group, even after adjusting for age, sex, and statin use (p = 0.042). Conclusions: Add-on EPA/DHA treatment improved the effectiveness of conventional therapy (such as statin treatment) for improving the ABI in hemodialysis patients with dyslipidemia by lowering RLP-C levels. Therefore, clinicians involved in dialysis should focus on RLP-C when considering residual cardiovascular disease risk in hemodialysis patients and should consider screening patients with elevated levels.

Influence on the accuracy in ChatGPT: Differences in the amount of information per medical field

OBJECTIVES

Although ChatGPT was not developed for medical use, there is growing interest in its use in medical fields. Understanding its capabilities and precautions for its use in the medical field is an urgent matter. We hypothesized that differences in the amounts of information published in different medical fields would be proportionate to the amounts of training ChatGPT receives in those fields, and hence its accuracy in providing answers.

STUDY DESIGN

A non-clinical experimental study.

METHODS

We administered the Japanese National Medical Examination to GPT-3.5 and GPT-4 to examine the rates of accuracy and consistency in their responses. We counted the total number of documents in the Web of Science Core Collection per medical field and assessed the relationship with ChatGPT's accuracy. We also performed multivariate-adjusted models to investigate the risk factors for incorrect answers.

RESULTS

For GPT-4, we confirmed an accuracy rate of 81.0 % and a consistency rate of 88.8 % on the exam; both showed improvement compared to those for GPT-3.5. A positive correlation was observed between the accuracy rate and consistency rate (R = 0.51, P < 0.001). The number of documents per medical field was significantly correlated with the accuracy rate in that medical field (R = 0.44, P < 0.05), with relatively few publications being an independent risk factor for incorrect answers.

CONCLUSIONS

Checking consistency may help identify incorrect answers when using ChatGPT. Users should be aware that the accuracy of the answers by ChatGPT may decrease when it is asked about topics with limited published information, such as new drugs and diseases.

The implication of calf circumference and grip strength in osteoporosis and bone mineral density among hemodialysis patients

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD), nutritional status, and uremia management have been emphasized for bone management in hemodialysis patients. Nevertheless, valuable data on the importance of muscle mass in bone management are limited, including whether conventional management alone can prevent osteoporosis. Thus, the importance of muscle mass and strength, independent of the conventional management in osteoporosis prevention among hemodialysis patients, was evaluated.

METHODS

Patients with a history of hemodialysis 6 months or longer were selected. We assessed the risk for osteoporosis associated with calf circumference or grip strength using multivariable adjustment for indices of CKD-MBD, nutrition, and dialysis adequacy. Moreover, the associations between bone mineral density (BMD), calf circumference, grip strength, and bone metabolic markers were also evaluated.

RESULTS

A total of 136 patients were included. The odds ratios (95% confidence interval) for osteoporosis at the femoral neck were 1.25 (1.04-1.54, P < 0.05) and 1.08 (1.00-1.18, P < 0.05) per 1 cm shorter calf circumference or 1 kg weaker grip strength, respectively. Shorter calf circumference was significantly associated with a lower BMD at the femoral neck and lumbar spine (P < 0.001). Weaker grip strength was also associated with lower BMD at the femoral neck (P < 0.01). Calf circumference or grip strength was negatively correlated with bone metabolic marker values.

CONCLUSION

Shorter calf circumference or weaker grip strength was associated with osteoporosis risk and lower BMD among hemodialysis patients, independent of the conventional therapies.

Clinical impact of left ventricular systolic dysfunction in patients undergoing dialysis access surgery

BACKGROUND

An arteriovenous fistula (AVF) is the most frequently used dialysis access for haemodialysis. However, it can cause volume loading for the heart and may induce circulatory failure when performed in patients with low cardiac function. This study aimed to characterise patients with low cardiac function when initiating dialysis and determine how cardiac function changes after the dialysis access surgery.

METHODS

We conducted a retrospective observational study at two centres incorporating 356 patients with end-stage kidney disease who underwent echocardiography before the dialysis access surgery.

RESULTS

An AVF and a subcutaneously fixed superficial artery were selected in 70.4% and 23.5% of 81 patients with reduced/mildly reduced (< 50%) left ventricular ejection fraction (LVEF), respectively, and in 94.2% and 1.1% of 275 patients with preserved (≥ 50%) LVEF (p < 0.001), respectively. Follow-up echocardiography was performed in 70.4% and 38.2% of patients with reduced/mildly reduced and preserved LVEF, respectively, which showed a significant increase in LVEF (41 ± 9-44 ± 12%, p = 0.038) in patients with reduced/mildly reduced LVEF. LVEF remained unchanged in 12 patients with reduced/mildly reduced LVEF who underwent subcutaneously fixed superficial artery (30 ± 10-32 ± 15%, p = 0.527). Patients with reduced/mildly reduced LVEF had lower survival rates after surgery than those with preserved LVEF (p = 0.021 for log-rank).

CONCLUSION

The LVEF subcategory was associated with dialysis access selection. After the dialysis access surgery, LVEF was increased in patients with reduced/mildly reduced LVEF. These results may help select dialysis access for patients initiating dialysis.

Blunted humoral immune response to the fourth dose of BNT162b2 COVID-19 vaccine in patients undergoing hemodialysis

BACKGROUND

We aimed to investigate the impact of a fourth dose of BNT162b2 vaccine (Comirnaty®, Pfizer-BioNTech) on anti-SARS-CoV-2 (anti-S IgG) antibody titers in patients receiving hemodialysis (HD) and healthcare workers (HCWs).

METHODS

A multi-institutional retrospective study at five dialysis clinics in Japan was conducted using 238 HD patients and 58 HCW controls who received four doses of the BNT162b2 mRNA vaccine. Anti-S IgG titers were measured at 1, 3, and 6 months after the second dose, at 1 and 5/6 months after the third dose, and at 1 month after the fourth dose of vaccine.

RESULTS

The log anti-S IgG titers of the HD patients after the second vaccination were significantly lower than those of the control group, but equalized 1 month after the third vaccination: 9.94 (95% CI 9.82-10.10) vs. 9.81 (95% CI 9.66-9.96), (P = 0.32). In both groups, the fold-increase in anti-S IgG titers was significantly lower after the fourth dose than after the third dose of vaccine. In addition, there was a strong negative correlation between antibody titers 1 month after the fourth vaccination and antibody titers immediately before the vaccination. In both groups, the waning rate of anti-S IgG titers from the post-vaccination peak level after the third vaccine dose was significantly slower than that after the second dose.

CONCLUSIONS

These findings suggest that the humoral immune response was blunted after the fourth dose of the conventional BNT162b2 vaccine. However, multiple vaccinations could extend the window of humoral immune protection.

Effect of the interaction between the visceral-to-subcutaneous fat ratio and aldosterone on cardiac function in patients with primary aldosteronism

Primary aldosteronism is the most frequent secondary hypertensive disease and is characterized by an elevated risk for cardiovascular disease. The current standard treatments are adrenalectomy and/or administration of mineralocorticoid receptor blockers, both of which are effective at ameliorating hypertension via intervention for hyperaldosteronism. However, both of these approaches have side effects and contraindications, and mineralocorticoid receptor blockers also have limited preventive efficacy against cardiovascular events. Recently, in vitro experiments have shown that aldosterone regulation is closely related to abdominal fat accumulation and that there is crosstalk between aldosterone and visceral fat tissue accumulation. We previously reported that this interaction was clinically significant in renal dysfunction; however, its effects on the heart remain unclear. Here, we analyzed data from 49 patients with primary aldosteronism and 29 patients with essential hypertension to examine the potential effect of the interaction between the ratio of visceral-to-subcutaneous fat tissue volume and the plasma aldosterone concentration on echocardiographic indices, including the tissue Doppler-derived E/e' ratio. A significant interaction was found in patients with primary aldosteronism (p < 0.05), indicating that patients with the combination of a high plasma aldosterone concentration and high visceral-to-subcutaneous fat ratio show an increased E/e' ratio, which is a well-known risk factor for future cardiovascular events. Our results confirm the clinical importance of the interaction between aldosterone and abdominal fat tissue, suggesting that an improvement in the visceral-to-subcutaneous fat ratio may be synergistically and complementarily effective in reducing the elevated risk of cardiovascular disease in patients with primary aldosteronism when combined with conventional therapies for reducing aldosterone activity. A significant effect of the interaction between plasma aldosterone concentration and the visceral-to-subcutaneous fat ratio on the tissue Doppler-derived E/e' ratio in patients with primary aldosteronism.

Present status of renal replacement therapy in lower-middle-income Asian countries: Cambodia, Myanmar, Laos, Vietnam, Mongolia, and Bhutan as of June 2019 (before COVID-19), from the interviews of leading doctors in every country: (duplicated English publication from “the special Japanese edition of educational lectures in the 64th annual meeting of the Japanese Society for Dialysis Therapy”)

The present status of Cambodia, Myanmar, Laos, Vietnam, Mongolia, and Bhutan as of June 2019 was reviewed from the interviews of leading doctors in every country. The timing was until just 6 months before the COVID-19 pandemic broke out. The cost per hemodialysis session was 25–70 US dollar and expensive if it is compared with average monthly income of every country. In Cambodia and Laos, patients must cover 100% of expenses for maintenance hemodialysis, in Myanmar, the government covers the cost of once-weekly dialysis sessions, in Vietnam, the government covers 80% of the cost, and in Mongolia and Bhutan, the cost is fully covered by the government. Continuous ambulatory peritoneal dialysis was widely available in Vietnam and Mongolia, which have achieved a relative standard of social infrastructure, but is far from common in any of the other countries. The number of patients on dialysis is increasing with economic development in all countries. Diabetic nephropathy is a common primary reason for dialysis. None of the countries discussed in this article had clinical engineers who could maintain hemodialysis equipment and carry out clinical tasks in dialysis centers. Hospitals were not maintaining their equipment, and damaged units were kept in storage to be used for spare parts. None of the countries had dieticians to provide patients with dietary guidance. Establishment and training of both clinical engineers and registered dietitians are major projects that must be undertaken.

SARS-CoV-2 spike protein antibody titers 6 months after SARS-CoV-2 mRNA vaccination among patients undergoing hemodialysis in Japan

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is shown to prevent severe illness and death in hemodialysis (HD) patients, but the immune response to vaccines is reduced in this population. This study compared SARS-CoV-2 spike protein antibody titers between HD patients and healthy controls in Japan for up to 6 months following vaccination.

METHODS

A multi-institutional retrospective study at five clinics in Japan was conducted using 412 HD patients and 156 healthy controls who received two doses of the BNT162b2 (Pfizer-BioNTech) mRNA vaccine. Anti-SARS-CoV-2 spike protein S1 IgG antibody titers were measured at 1, 3, and 6 months after the second dose. The attenuation speed was calculated as slope (i.e., -β) using a linear mixed-effects model toward the log-transformed antibody titers.

RESULTS

The HD group had significantly lower month 1 antibody titers (Ab-titer-1) than the controls, and these remained lower through month 6 (95% CI: 2617.1 (1296.7, 5240.8) vs. 7285.4 (4403.9, 11,000.0) AU/mL at Ab-titer-1, and 353.4 (178.4, 656.3) vs. 812.0 (498.3, 1342.7) AU/mL at Ab-titer-6 (p < 0.001, respectively)). Lower log Ab-titer-1 levels in the HD group were significantly associated with a lower log Ab-titer-6 (0.90 [0.83, 0.97], p < 0.001). The -β values in the HD patients and healthy controls were -4.7 ± 1.1 and -4.7 ± 1.4 (year-1), respectively.

CONCLUSION

SARS-CoV-2 spike protein antibody titers were significantly lower in HD patients than in healthy controls at 1 (peak) and 6 months after the second vaccination. Low peak antibody titers contributed to low 6-month antibody titers.

The efficacy and safety of mizoribine for maintenance therapy in patients with myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis: the usefulness of serum mizoribine monitoring

BACKGROUND

The life prognosis of elderly patients with myeloperoxidase-anti-neutrophil cytoplasmic antibodies-associated vasculitis (MPO-AAV) has been improved by reducing the corticosteroid or cyclophosphamide dose to avoid opportunistic infection. However, many elderly MPO-AAV patients experience recurrence and renal death. An effective and safer maintenance treatment method is necessary to improve the renal prognosis of MPO-AAV.

METHODS

Patients with MPO-AAV who reached complete or incomplete remission after induction therapy were prospectively and randomly divided into mizoribine (MZR; n = 25) and control (n = 28) groups. The primary endpoint was relapse of MPO-AAV. The patients' serum MZR concentration was measured before (C0) and 3 h after taking the MZR. The maximum drug concentration (Cmax) and the serum MZR concentration curves were determined using population pharmacokinetics parameters. We also assessed the relationship between the MZR concentrations and adverse events. The observation period was 12 months.

RESULTS

Fifty-eight MPO-AAV patients from 16 hospitals in Japan were enrolled. Ten patients relapsed (MZR group, n = 6; control group, n = 4; a nonsignificant between-group difference). Changes in the serum MZR concentration could be estimated for 22 of the 25 MZR-treated patients: 2 of the 11 patients who reached a Cmax of 3 μg/mL relapsed, whereas 4 of the 11 patients who did not reach this Cmax relapsed. The treatment of one patient with C0 > 1 μg/mL was discontinued due to adverse events. No serious adverse events occurred.

CONCLUSION

There was no significant difference in the recurrence rate of MPO-AAV between treatment with versus without MZR.

Current status of renal replacement therapy in Cambodia and Japanese support activities in developing countries in East and Southeast Asia: a report as of June 2018 from the Non-Western World Countries Symposium at the 63rd Annual Meeting of the Japanese Society for Dialysis Therapy

Since 2015, the Committee of International Communication for Academic Research of the Japanese Society for Dialysis Therapy has held a symposium every year at the society’s Annual Congress to discuss the current status of and demand for dialysis therapy in developing countries in Asia with the aim of identifying ways to contribute to the field of dialysis therapy in these countries. The 2018 symposium opened the door further, beyond Asian countries to include all non-Western countries. Two speakers from Cambodia and Japan contributed their manuscripts to the 2018 symposium issue. In Cambodia in 2017, a study of hemodialysis data from 5 centers in Phnom Penh was conducted for the first time. This study involving 407 patients (233 men [57.2%]; mean age 52 [SD, ± 15] years) revealed that hypertension was the main cause of end-stage renal disease (46.8%), followed by concomitant hypertension and diabetes mellitus (31%), with diabetes mellitus alone accounting for only 8.1% of cases. Mean frequency of hemodialysis was 7.5 (SD, ± 2.3) sessions per month. The duration of each session was 4 h. Patients in Cambodia are required to bear the full cost for hemodialysis because the country lacks a national health insurance system. From 2007 to 2018, several Japanese societies and organizations for dialysis therapy and technology carried out activities aimed at resolving problems in dialysis medical care in developing countries in East and Southeast Asia. The role of the academic societies and their activities in this region are discussed.

LPIN1 is a new target gene for essential hypertension

BACKGROUND

We previously showed Lipin1 (LPIN1) to be a candidate gene for essential hypertension by genome-wide association studies. LPIN1 encodes the Lipin 1 protein, which contributes to the maintenance of lipid metabolism and glucose homeostasis. However, little is known about the association between LPIN1 and blood pressure (BP).

METHODS

We evaluated the BP of LPIN1-deficient [fatty liver dystrophy (fld)] mice and explored related mechanisms.

RESULTS

Fld mice have very low expression of LPIN1 and exhibit fatty liver, hypertriglyceridemia, insulin resistance and peripheral neuropathy. Fld mice had significantly elevated SBP and heart rate (HR) throughout the day as measured by a radiotelemetric method. Diurnal variation of SBP and HR was also absent in fld mice. Furthermore, urinary excretion of adrenaline and noradrenaline by fld mice was significantly higher compared with that of control mice. The BP response of fld mice to clonidine (a centrally acting α2-adrenergic receptor agonist) was greater than that of control mice. However, levels of Angiotensinogen and Renin 1 mRNA and urinary nitric oxide excretion were comparable between the two groups. The decrease in SBP at 8 weeks after fat grafting surgery was significantly greater in the transplant group compared with the sham operated group.

CONCLUSION

The elevated BP in fld mice may result from activation of the sympathetic nervous system through decreased levels of adipose cytokines. These results indicate that LPIN1 plays a crucial role in blood pressure regulation and that LPIN1 is a new target gene for essential hypertension.

Efficacy of the Self-management Support System DialBetesPlus for Diabetic Kidney Disease: Protocol for a Randomized Controlled Trial

Background

Diabetic kidney disease (DKD) is one of the main complications of type 2 diabetes mellitus (T2DM). DKD is a known risk factor for end-stage renal disease, cardiovascular disease, and all-cause death. Effective intervention for early-stage DKD is vital to slowing down the progression of kidney disease and improve prognoses. Mobile health (mHealth) is reportedly effective in supporting patients’ self-care and improving glycemic control, but the impact of mHealth on DKD has yet to be shown.

Objective

The purpose of this study is to evaluate the efficacy of standard therapy with the addition of a self-management support system, DialBetesPlus, in patients with DKD and microalbuminuria.

Methods

This study is a prospective, randomized, open-label, multicenter clinical trial. The target population consists of 160 patients diagnosed with T2DM accompanied by microalbuminuria. We randomly assigned the patients to 2 groups—the intervention group using DialBetesPlus in addition to conventional therapy and the control group using conventional therapy alone. DialBetesPlus is a smartphone application that supports patients’ self-management of T2DM. The study period was 12 months, with a follow-up survey at 18 months. The primary outcome was a change in albuminuria levels at 12 months. Secondary outcomes included changes in physical parameters, blood test results (glycemic control, renal function, and lipid metabolism), lifestyle habits, self-management scores, medication therapy, and quality of life.

Results

The study was approved in April 2018. We began recruiting patients in July 2018 and completed recruiting in August 2019. The final 18-month follow-up was conducted in March 2021. We recruited 159 patients and randomly allocated 70 into the intervention group and 61 into the control group, with 28 exclusions due to withdrawal of consent, refusal to continue, or ineligibility. The first results are expected to be available in 2021.

Conclusions

This is the first randomized controlled trial assessing the efficacy of mHealth on early-stage DKD. We expect that albuminuria levels will decrease significantly in the intervention group due to improved glycemic control with ameliorated self-care behaviors.

Trial Registration

UMIN-CTR UMIN000033261; https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000037924

International Registered Report Identifier (IRRID)

DERR1-10.2196/31061

Annual dialysis data report of the 2018 JSDT Renal Data Registry: dementia, performance status, and exercise habits

According to the annual survey of the Japanese Society for Dialysis Therapy Renal Data Registry (JRDR) conducted at the end of 2018, there were a total of 339,841 patients receiving dialysis (hereinafter, dialysis patients) in Japan. The survey included questions regarding the presence/absence of dementia, the performance status (PS), and the exercise habits of individual patients. The survey revealed that 10.8% of all dialysis patients had dementia (1.8% in the age group of less than 65 years, 6.8% in the age group of 65–74 years, and 22.7% in the age group of 75 years or older). These prevalences of dementia were approximately equal to those estimated from the survey conducted in 2010. Regarding PS, the percentage of patients with lower activity levels tended to be relatively high among patients who were less than 15 years old and those who were 60 years old or older. Concerning the exercise habits of dialysis patients, the percentage of patients who were classified as “not at all or hardly” in response to the question about exercise habit was the highest (60–80%) of all the exercise habit classifications in each of the age groups analyzed.

Association of aldosterone and blood pressure with the risk for cardiovascular events after treatments in primary aldosteronism

BACKGROUND AND AIMS

We used a dataset from a Japanese nationwide registry of patients with primary aldosteronism, to determine which of the parameters of hyperaldosteronism and blood pressure before or after treatments for primary aldosteronism (i.e., surgical adrenalectomy or a medication treatment) are important in terms of cardiovascular prognosis.

METHODS

We assessed whether plasma aldosterone-to-renin ratio and pulse pressure levels before treatment and 6 months after treatment were associated with composite cardiovascular disease events during the 5-year follow-up period.

RESULTS

The cohort included 1987 patients (mean age was 53.2 years, 52.0% were female, 37.2% had undergone surgical treatment, and the remainder had been treated with mineralocorticoid receptor antagonists). In the Cox proportional hazard model, the covariate-adjusted hazard ratio (95% confidence interval) for the composite cardiovascular disease events risk for each one-standard-deviation increase in the aldosterone-to-renin ratio or pulse pressure before treatment, those after treatment, or the duration of hypertension were 1.24 (1.05, 1.48), 0.74 (0.54, 1.02), and 1.07 (0.79, 1.44), 1.43 (1.07, 1.92), and 1.52 (1.19, 1.95), respectively. Patients with a high pre-treatment aldosterone-to-renin ratio of more than 603 and a large post-treatment pulse pressure of more than 49 mmHg showed approximately three-fold higher hazard ratios for cardiovascular events risk compared to those with a lower aldosterone-to-renin ratio and smaller pulse pressure.

CONCLUSIONS

Higher aldosterone-to-renin ratio before treatments, higher pulse pressure after treatments, and longer duration of hypertension were prognostic factors for cardiovascular diseases. Early intervention may be important for preventing cardiovascular disease among patients with primary aldosteronism.

Association of the ratio of visceral-to-subcutaneous fat volume with renal function among patients with primary aldosteronism

Patients with primary aldosteronism have a higher risk of chronic kidney disease. Visceral fat tissue is hypothesized to stimulate the adrenal glands to overproduce aldosterone, and aldosterone promotes visceral fat tissue to produce inflammatory cytokines. However, it is unclear whether the volume of accumulated visceral fat tissue is associated with renal impairment among patients with hyperaldosteronism. We conducted a single-center cross-sectional study to assess the association between the estimated glomerular filtration rate and the ratio of the visceral-to-subcutaneous fat volume calculated by computed tomography. One hundred eighty patients with primary aldosteronism were enrolled. The mean ± SD age was 52.7 ± 11.0 years, and 60.0% were women. The ratio of visceral-to-subcutaneous fat volume was highly correlated with the estimated glomerular filtration rate (r = 0.49, p < 0.001). In multiple linear regression models, the ratio of visceral-to-subcutaneous fat tissue volume was significantly associated with the estimated glomerular filtration rate (estimates: -4.56 mL/min/1.73 m² per 1-SD), and there was an interaction effect between the plasma aldosterone concentration and the ratio of visceral-to-subcutaneous fat volume (p < 0.05). The group with a higher plasma aldosterone concentration exhibited a steeper decline in eGFR than the lower plasma aldosterone concentration group when the ratio increased. The ratio of visceral-to-subcutaneous fat tissue volume was an independent risk factor for renal dysfunction. This association increased in the presence of a high plasma aldosterone concentration. Clinicians should pay attention to the ratio of visceral-to-subcutaneous fat tissue volume and encourage primary aldosteronism patients to improve their lifestyle in addition to treating renin-aldosterone activity.

Present status of renal replacement therapy in Asian countries as of 2017: Vietnam, Myanmar, and Cambodia

Since 2015, the Committee of International Communication on Academic Research of the Japanese Society for Dialysis Therapy has held its Asian symposium during the society’s Annual Congress to discuss the present status of and demand for dialysis therapy in Asian countries. The aim of the symposium is to identify needs and find ways to contribute in the area of dialysis therapy in these countries. Three manuscripts are presented here by participants at the 2017 Asian symposium from Vietnam, Myanmar, and Cambodia.

With economic development, hemodialysis (HD) therapy is now available worldwide. However, the cost of HD is very high compared with the average income in these three countries and, as of 2017, Cambodia and Myanmar have not yet established national health insurance systems. In Cambodia, patients must bear 100% of the cost for dialysis. In Myanmar, the government covers the cost of HD (20 USD, 40% of total cost) in public HD centers, but this service is still insufficient to meet current demand, with long waiting lists of up to 6 months at government HD centers. In contrast, in Vietnam, dialysis is almost completely covered by national health insurance. Dialyzers tend to be reused in all three countries. Continuous ambulatory peritoneal dialysis is available in Vietnam and Myanmar but not in Cambodia. Viable health insurance systems should be established as soon as possible in Cambodia and Myanmar, although this will ultimately depend on the countries’ level of economic development.

Abstract P237: Elucidation of Blood Pressure Control Function of Essential Hypertension Candidate Gene Lpin1

We have found that the LPIN1 is the candidate gene for essential hypertension (EHT) by genome-wide association analysis in 2007. Mice characterized by loss of body fat, fatty liver, insulin resistance and peripheral neuropathy were discovered in nature and named fatty liver dystrophy (fld) mice in 2000. Recently, the fld mice were shown that they exhibit few LPIN1 genes, and the LPIN1 gene was proved as the cause of phenotype of fld mice. However, the blood pressure (BP) and the alteratios of the vasoactive factors in fld mice have not yet been elucidated. Therefore, to clarify the BP and the effects of LPIN1 gene defeciency, we analyzed the BP and regulatory factors of the fld mice. Furthermore, we transplanted the fat to fld mice, and clarify the importance of adipocytokine on BP in the model mice. The BP were measured by the tail cuff method and the telemetry method. We performe fat grafting or sham surgery on fld mice, and systolic BP (SBP) was measured by tail cuff method 8 weeks after surgery. We confirmed that the SBP of fld mice were higher than that of CO by the tail cuff method( fld 134±5 vs CO 111±4 mmHg P<0.05). Furthermore, SBP of the fld mice were higher than that of CO (fld 167.7±9.8 vs CO 133.5±10.9 mmHg P<0.01) by the telemetry method. It was confirmed that the adrenalin and noradrenalin excretions in the urine of fld mice were higher than those of CO(fld 0.133±0.067 vs CO 0.038±0.013 μg/day P<0.01 )(fld 0.980 ±0.313 vs CO 0.364±0.080 μg/day P<0.001). There is no significant difference in plasma aldosterone concentration between two groups( fld 434±276.7 vs CO 781±469.5 pg/mL n.s).The SBP tended to decrease with the fat trasplantation in fld mice ( fat transplanted 103.7±4.41 vs sham 114.7±7.67 mmHg P=0.056). We confirmed that fld mouse exhibits higher SBP by both tailcuff method and telemetry method. Because the fld mice exhibit higher PR and high levels of CA concentration and excretion in urine, it was suggested that the sympathetic nervous systems of fld mice were activated. Sympathetic nervous system activity may be related to an increase in BP of fld mouse, and further research is under way. Since it showed that BP decreased by fat grafting, the visceral fat are essential for fld mice to BP control. The implications of adipokine and other fats are under consideration.

Plasma Cystine Levels and Cardiovascular and All-Cause Mortality in Hemodialysis Patients

Oxidative stress accelerates the development of cardiovascular disease. Plasma cystine, a thiol oxidative stress marker, is related to several established factors for cardiovascular disease risk and prognosis. Although a comprehensive oxidative stress index is clinically required for hemodialysis patients with high oxidative stress, there are few reports concerning thiol oxidative stress markers predicting their prognosis. We investigated the relationship between plasma amino acids including cystine levels and cardiovascular disease-related and all-cause mortality in 132 maintenance hemodialysis patients. Higher cystine levels were associated with old age, longer hemodialysis duration, hemodialysis-associated hypotension, higher cardiothoracic ratio, higher blood urea nitrogen, and lower ankle-brachial index. Multivariate Cox regression analysis revealed that high plasma cystine was independently related with both cardiovascular disease mortality and all-cause mortality. Thus, high plasma cystine levels predict the prognosis of hemodialysis patients. High cystine levels necessitate a careful investigation for the cause of oxidative stress and comorbidities like vascular injury.

Atherosclerosis of the carotid bulb is associated with the severity of orthostatic hypotension in non-diabetic adult patients: a cross-sectional study

BACKGROUND

The carotid bulb has a high density of baroreceptors that play an important role in maintaining blood pressure. We hypothesized that atherosclerosis of the carotid bulb would reflect the severity of orthostatic hypotension more accurately than would atherosclerosis of other carotid artery segments.

METHODS

This cross-sectional study included 198 non-diabetic adults. We measured the cardio-vascular ankle index as an index of arterial stiffness, intima-media thickness in each carotid artery segment (internal carotid artery, carotid bulb, distal and proximal portions, respectively, of the common carotid artery) as a measure of atherosclerosis, and heart rate variability as a measure of cardiac autonomic function. The sit-to-stand test was used to assess severity of orthostatic hypotension.

RESULTS

Intima-media thickness of the carotid bulb was correlated with orthostatic systolic blood pressure change (r = -0.218, p = 0.002), cardio-ankle vascular index (r = 0.365, p < 0.001) and heart rate variability parameters. Multivariate regression analysis revealed that among all of the segments, only intima-media thickness of the carotid bulb was an independent predictor of orthostatic systolic blood pressure change (p = 0.022).

CONCLUSION

Atherosclerosis of the carotid bulb was associated with severity of orthostatic hypotension, arterial stiffening and cardiac autonomic dysfunction than that of other carotid artery segments.

Arterial wall hypertrophy is ameliorated by α2-adrenergic receptor antagonist or aliskiren in kidneys of angiotensinogen-knockout mice

BACKGROUND

Arterial hypertrophy and interstitial fibrosis are important characteristics in kidneys of angiotensinogen-knockout (Atg ^-/-) mice. In these mice, which exhibit polyuria and hypotension, sympathetic nerve signaling is estimated to be compensatorily hyperactive. Furthermore, transforming growth factor (TGF)-β1 is overexpressed in mice kidneys. To determine whether sympathetic nerve signaling and TGF-β1 exacerbate arterial hypertrophy and interstitial fibrosis, intervention studies of such signaling are required.

METHODS

We performed renal denervation and administered the α2-adrenergic receptor (AR) antagonist, atipamezole, to Atg ^-/- mice. A renin inhibitor, aliskiren, which was preliminarily confirmed to reduce TGF-β1 gene expression in kidneys of the mice, was additionally administered to assess the effect on the arterial hypertrophy and interstitial fibrosis.

RESULTS

Norepinephrine content in kidneys of Atg ^-/- mice was three times higher than in kidneys of wild-type mice. Interventions by renal denervation and atipamezole resulted in amelioration of the histological findings. Overexpression of TGF-β1 gene in kidneys of Atg ^-/- mice was altered in a manner linked to the histological findings. Surprisingly, aliskiren reduced α2-AR gene expression, interstitial fibrosis, and arterial hypertrophy in kidneys of Atg ^-/- mice, which lack renin substrate.

CONCLUSIONS

Alpha2-AR signaling is one of the causes of persistent renal arterial hypertrophy in Atg ^-/- mice. Aliskiren also angiotensinogen-independently reduces the extent of renal arterial hypertrophy, partly thorough downregulation of α2-ARs. Although renal arterial hypertrophy in Atg ^-/- mice appears to be of multifactorial origin, TGF-β1 may play a key role in the persistence of such hypertrophy.

Monozygotic twins discordant for primary aldosteronism: a case report

This corrects the article DOI: 10.1038/jhh.2017.41.

Abstract P492: Lower Body Mass Index is Associated With Arterial Stiffening and Severity of Orthostatic Hypotension in Middle-aged and Older Patients With Abdominal Obesity

Background: Recently, patients with both sarcopenia and abdominal obesity are known to exhibit subclinical atherosclerosis and high mortality risk. Sarcopenic obesity is considered to be latent in those without increase in body mass index (BMI) despite having abdominal obesity. We aimed to investigate whether arterial stiffening and severity of orthostatic hypotension, which is the risk of cardiovascular disease, is associated with lower BMI in patients with abdominal obesity.

Methods: We studied middle-aged and older patients with normal to high BMI (BMI ≥ 18.5) and being treated with life-style related diseases. The patients were divided into 2 groups (with or without abdominal obesity) according to waist circumference (WC) (abdominal obesity: men; WC ≥ 85 cm, women; WC ≥ 90 cm). We measured cardio-vascular ankle index (CAVI) for an index of arterial stiffness. We assessed sit-to-stand test for measuring orthostatic systolic blood pressure (SBP) change.

Results: One thousand and forty-six patients were included in the study. Mean age of the patients was 68.0 ± 10.1 years (42.5% were men), hypertension dyslipidemia and diabetes mellitus was observed in 83.3%, 74.3% and 20.2% of the patients respectively. There was a significant negative correlation with BMI and CAVI in patients with abdominal obesity (r=-0.309, p<0.001, n=434), whereas no significant association was observed in patients without abdominal obesity (p=N.S., n=612). There was a significant positive correlation with BMI and orthostatic SBP change in patients with abdominal obesity (r=0.213, p<0.001) and in patients without abdominal obesity (r=0.117, P=0.004). Multivariate regression analysis revealed that BMI was an independent determinant of CAVI and orthostatic SBP change in patients with abdominal obesity (p<0.001, p<0.001, respectively), and was an independent determinant of orthostatic SBP change in patients without abdominal obesity (p=0.004).

Conclusion: In patients with abdominal obesity, lower BMI was an independent determinant of arterial stiffening and severity of orthostatic hypotension. Further investigation by evaluating body composition is necessary and now ongoing to assess the risk of lower BMI in patients with abdominal obesity.

Enhancement of intrarenal plasma membrane calcium pump isoform 1 expression in chronic angiotensin II-infused mice

Plasma membrane calcium pump isoform 1 (PMCA1) is encoded by ATPase plasma membrane Ca²⁺transporting 1 (ATP2B1), the most likely candidate gene responsible for hypertension. Although PMCA1 is highly expressed in the kidney, little is known about regulation of its renal expression in various pathological conditions in vivo. Our study was designed to elucidate regulation of renal PMCA1 expression in mice. We employed three mouse models for kidney disease. These were the unilateral ureteral obstruction (UUO), the remnant kidney using 5/6 nephrectomy, and chronic angiotensin II administration models. Mice were assessed for systolic blood pressure and renal injury in accordance with the damage induced in the specific model. Kidney PMCA1 mRNA levels were measured in all mice. The UUO model showed renal fibrosis but no changes in blood pressure or renal PMCA1 mRNA expression. Similarly, the 5/6 nephrectomy model exhibited declined renal function without changes in blood pressure or renal PMCA1 mRNA expression. In contrast, chronic angiotensin II administration increased albuminuria and blood pressure as well as significantly increasing renal PMCA1 mRNA and protein expression. These results suggest that renal PMCA1 has a role as one of the molecules involved in angiotensin II-induced hypertension and kidney injury.

Effects of tolvaptan in patients with chronic kidney disease and chronic heart failure

BACKGROUND

Tolvaptan, a vasopressin V₂ receptor blocker, has a diuretic effect for patients with heart failure. However, there were a few data concerning the effects of tolvaptan in patients with chronic kidney disease (CKD).

METHODS

We retrospectively analyzed 21 patients with chronic heart failure and CKD. Tolvaptan was co-administered with other diuretics in-use, every day. We compared clinical parameters before and after the treatments with tolvaptan. Furthermore, we examined the correlations between baseline data and the change of body weight.

RESULTS

Tolvaptan decreased the body weight and increased the urine volume (p = 0.001). The urine osmolality significantly decreased throughout the study period. Urinary Na/Cr ratio and FENa changed significantly after 4 h, and more remarkable after 8 h (p = 0.003, both). Serum creatinine increased slightly after 1 week of treatment (p = 0.012). The alteration of body weight within the study period correlated negatively with the baseline urine osmolality (r = -0.479, p = 0.038), the baseline urine volume (r = -0.48, p = 0.028), and the baseline inferior vena cava diameter (IVCD) (r = -0.622, p = 0.017). Hyponatremia was improved to the normal value, and the augmentations of the sodium concentration were negatively associated with the basal sodium levels (p = 0.01, r = -0.546).

CONCLUSIONS

Tolvaptan is effective in increasing diuresis and improved hyponatremia, even in patients with CKD. The baseline urine osmolality, urine volume, and IVCD may be useful predictors for diuretic effects of tolvaptan.

Relationship between Arterial Stiffness and Blood Pressure Drop During the Sit-to-stand Test in Patients with Diabetes Mellitus

Aim: Patients with orthostatic hypotension (OH) have high arterial stiffness. Patients with diabetes mellitus (DM) often have cardiac autonomic neuropathy that leads to OH; however, whether OH is an indicator of arterial stiffness progression is unclear. We aimed to investigate whether the cardioankle vascular index (CAVI) varies between DM patients with and without OH using the sit-to-stand test (STST).

Methods: One hundred and fifty-nine patients with DM underwent CAVI assessment and blood pressure (BP) and heart rate change evaluation during the STST. OH was defined as a decline in systolic BP (SBP) and/or diastolic BP of at least 20 mmHg or 10 mmHg, respectively, in the initial and late upright positions compared with that in the sitting position.

Results: OH was diagnosed in 42 patients (26.4%). DM patients with OH had significantly higher CAVI (9.36 ± 1.15 versus 8.89 ± 1.18, p = 0.026) than those without OH. CAVI was significantly inversely correlated with systolic and diastolic BP changes (R = −0.347, p <0.001 and R = −0.314, p <0.001, respectively) in the initial upright position. Multivariate regression analysis revealed that age, SBP changes, and low frequency component in the initial upright position were independent determinants of CAVI.

Conclusion: Patients with DM having large BP drops occurring when moving from sitting to standing have high arterial stiffness. A significant BP drop during the STST necessitates careful evaluation of advanced arterial stiffness in patient with DM.

Relation between circadian blood pressure rhythm and serum albumin level in non-diabetic patients with proteinuria

It remains unclear whether the abnormal circadian blood pressure (BP) rhythm in non-diabetic chronic kidney disease (CKD) is related to hypoalbuminemia. We evaluated relationships between circadian BP rhythm and serum albumin concentration (SAC) and also examined autonomic nervous activities. Non-diabetic CKD patients with proteinuria (n = 197; 105 men, 92 women; aged 47.0 ± 13.3 years; estimated glomerular filtration rate ≥30 ml/min) were divided into nephrotic syndrome (NS: n = 46, SAC ≤ 30 g/l), hypoalbuminemia (n = 65, 30 < SAC < 40 g/l) and normoalbuminemia (n = 86, SAC ≥ 40 g/l) groups. Non-proteinuria subjects (n = 97, urinary protein/creatinine ratio < 30 mg/g creatinine) were enrolled as the non-proteinuria group. Ambulatory 24 h BP monitoring was conducted in all subjects. Simultaneously, power spectral analysis of heart rate was performed to evaluate the sympathovagal balance. Waking BP was lower in the hypoalbuminemia and NS groups than the other groups. Sleeping/waking mean BP ratio was not different between non-proteinuria (0.87 ± 0.07) and normoalbuminemia (0.89 ± 0.08) groups, but increased significantly (p < 0.05) in the hypoalbuminemia (0.92 ± 0.08) and NS groups (0.96 ± 0.08). Significant reverse correlations were observed between SAC and sleeping/waking mean BP ratio (r = -0.274, p < 0.001) in all patients. Multivariate regression analysis identified SAC and sympathovagal balance as predictors of increased sleeping/waking BP ratios as the dependent variable. In non-diabetic CKD patients with proteinuria, disturbed circadian BP rhythms were related to SAC and 24 h sympathovagal imbalance.

Genome-wide association study of IgA nephropathy using 23 465 microsatellite markers in a Japanese population

Immunoglobulin A nephropathy (IgAN) is the most common form of primary glomerulonephritis in many parts of the world. Although previous genome-wide association studies (GWAS) identified the major susceptibility loci for IgAN, the causal genes currently remain unknown. We performed a GWAS using 23 465 microsatellite (MS) markers to identify genes related to IgAN in a Japanese population. A pooled sample analysis was conducted in three-stage screenings of three independent case-control populations, and after the final step of individual typing, 11 markers survived. Of these, we focused on two regions on 6p21 and 12q21 because they (i) showed the strongest relationship with IgAN, and (ii) appeared to be highly relevant to IgAN in view of several previous studies. These regions contained the HLA, TSPAN8 and PTPRR genes. This study on GWAS, using >20 000 MS markers, provides a new approach regarding susceptible genes for IgAN for investigators seeking new tools for the prevention and treatment of IgAN.

Acceleration of iron utilization after intravenous iron administration during activated erythropoiesis in hemodialysis patients: a randomized study

This study aimed to evaluate the effect of different timings of iron administration during erythropoiesis activated by continuous erythropoietin receptor activator (CERA) on reticulocyte iron uptake in hemodialysis patients. In total, 110 patients were randomized to receive 40 mg intravenous elemental iron doses at all three hemodialysis sessions in the first week (IW1 group: n = 57) or in the third week (IW3 group: n = 53) after CERA administration. Following CERA administration at day 0, reticulocyte count increased, peaking at day 7. At days 7 and 14, the observed changes in Ret-He were higher in the IW1 group than in the IW3 group. Increases in total reticulocyte hemoglobin at day 7 were higher in the IW1 group than in the IW3 group. In contrast, there was only tendency toward greater total reticulocyte hemoglobin after iron administration in the third week in the IW3 group. Intravenous iron supplementation in the first week of CERA administration increases reticulocyte iron uptake; however, iron supplementation in the third week does not. The findings indicate that iron should be intravenously administered to increase the efficacy of CERA within 1 week of CERA administration during highly active erythropoiesis.

Kidney Diseases Enhance Expression of Tetraspanin-8: A Possible Protective Effect against Tubular Injury

Background/Aims

TSPAN8 encoding tetraspanin-8 was identified as a candidate gene for immunoglobulin A nephropathy (IgAN) by a genome-wide association study using microsatellites in the Japanese population. Tetraspanin-8 is a cell surface protein that contributes to the migration and invasion of epithelial cells.

Methods

We performed immunohistochemistry for tetraspanin-8 on human renal biopsy specimens associated with IgAN, antineutrophil cytoplasmic antibody-associated nephropathy and interstitial nephritis, as well as normal renal tissue. Furthermore, to study the potential function of tetraspanin-8, we performed cell migration and invasion assays using human renal tubule cells transfected with tetraspanin-8.

Results

Tetraspanin-8 was often expressed in vascular smooth muscle cells and occasionally in tubule cells in normal kidney. In the kidneys of all types of nephropathy, tetraspanin-8 staining in the arteries was unaffected, but that in the tubules was enhanced. The degree of tubular staining negatively correlated with the estimated glomerular filtration rate, independently of the type of nephropathy. Tetraspanin-8-expressing tubule cells were found predominantly in distal and collecting tubules, identified by cytokeratin 7 or aquaporin 2 staining. In vitro studies using cultured tubule cells revealed that tetraspanin-8 promoted migration by 2.7-fold without laminin, by 2.8-fold with laminin and invasion into Matrigel by 3.5-fold, suggesting that enhanced tetraspanin-8 may be involved in the repair of tubules.

Conclusion

The obtained findings indicate that tetraspanin-8 expression is enhanced in injured distal tubules, which may be involved in the repair of tubules by facilitating migration and invasion.