Evaluation of Individual Variation of d-Amino Acids in Human Plasma by a Two-Dimensional LC-MS/MS System and Application to the Early Diagnosis of Chronic Kidney Disease.

For the discovery of sensitive biomarkers of kidney function focusing on chiral amino acids, a multiple heart-cutting two-dimensional (2D) liquid chromatography-mass spectrometry (LC-MS)/MS system has been designed/developed. As the target analytes, alanine (Ala), aspartic acid, glutamic acid (Glu), leucine (Leu), lysine, methionine, phenylalanine (Phe), proline (Pro), serine (Ser), and valine were selected considering the presence of their d-forms in mammals. The 2D LC-MS/MS system consisted of the nonenantioselective reversed-phase separation of the target amino acids, the separations of the d- and l-enantiomers, and detection using MS/MS. Using the method, the plasma chiral amino acids, precolumn derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole, were isolated from other intrinsic substances, then determined without losing sensitivity by the fully automated whole-peak volume transfer operation from first to second dimension. In all of the tested plasma samples obtained from five healthy individuals and 15 patients with chronic kidney disease (CKD), the target chiral amino acids were determined without interference. In healthy individuals, the levels of all the tested d-amino acids were regulated in the low ranges. In contrast, the % d values of Glu, Leu, and Phe significantly increased with the progress of kidney dysfunction, besides the previously reported values of d-Ala, Pro, and Ser. Concerning Phe, the significant increase of the % d values (p < 0.05) was reported for the first time even in the mild CKD group compared to those of the healthy group; d-Phe might be a more sensitive marker than the previously reported d-forms. These results demonstrated the potential of these d-forms as the sensitive biomarkers of kidney function for the early diagnosis of CKD.

i-tRAP (individual tRNA acylation PCR): A convenient method for selective quantification of tRNA charging.

Each transfer RNA (tRNA) is aminoacylated (charged) with a genetic codon-specific amino acid at its 3' end. Charged tRNAs are primarily used for translation, whereas fluctuations in charged tRNA fractions are known to reflect cellular response to stress. Here we report the development of individual tRNA-acylation using PCR (i-tRAP), a convenient PCR-based method that can specifically quantify individual tRNA charging ratio. In this i-tRAP method, demethylases remove base methylations which are problematic for reverse transcription reaction, and ß-elimination reaction specifically removes the 3' end of adenine residue in uncharged tRNA. Subsequent TaqMan MGB qRT-PCR can distinguish between cDNA of charged tRNA and uncharged tRNA. By using this method, we revealed that the charging ratio of tRNAGln(CUG) was changed in response to amino acid starvation and also the charging ratio of tRNAGln(CUG) in senescent cells was lower than in young cells under starvation conditions. i-tRAP can be applicable to the quantification of charging ratio of various tRNAs, and provides a simple and convenient method for analyzing tRNA charging.

Viral entry and translation in brain endothelia provoke influenza-associated encephalopathy.

Influenza-associated encephalopathy (IAE) is extremely acute in onset, with high lethality and morbidity within a few days, while the direct pathogenesis by influenza virus in this acute phase in the brain is largely unknown. Here we show that influenza virus enters into the cerebral endothelium and thereby induces IAE. Three-weeks-old young mice were inoculated with influenza A virus (IAV). Physical and neurological scores were recorded and temporal-spatial analyses of histopathology and viral studies were performed up to 72 h post inoculation. Histopathological examinations were also performed using IAE human autopsy brains. Viral infection, proliferation and pathogenesis were analyzed in cell lines of endothelium and astrocyte. The effects of anti-influenza viral drugs were tested in the cell lines and animal models. Upon intravenous inoculation of IAV in mice, the mice developed encephalopathy with brain edema and pathological lesions represented by micro bleeding and injured astrocytic process (clasmatodendrosis) within 72 h. Histologically, massive deposits of viral nucleoprotein were observed as early as 24 h post infection in the brain endothelial cells of mouse models and the IAE patients. IAV inoculated endothelial cell lines showed deposition of viral proteins and provoked cell death, while IAV scarcely amplified. Inhibition of viral transcription and translation suppressed the endothelial cell death and the lethality of mouse models. These data suggest that the onset of encephalopathy should be induced by cerebral endothelial infection with IAV. Thus, IAV entry into the endothelium, and transcription and/or translation of viral RNA, but not viral proliferation, should be the key pathogenesis of IAE.

Plasma D-asparagine and the D/L-serine ratio reflect chronic kidney diseases in children regardless of physique.

Biomarkers that accurately reflect renal function are essential in management of chronic kidney diseases (CKD). However, in children, age/physique and medication often alter established renal biomarkers. We studied whether amino acid enantiomers in body fluids correlate with renal function and whether they are influenced by physique or steroid medication during development. We conducted a prospective study of children 2 to 18 years old with and without CKD. We analyzed associations of serine/asparagine enantiomers in body fluids with major biochemical parameters as well as physique. To study consequences of kidney dysfunction and steroids on serine/asparagine enantiomers, we generated juvenile mice with uninephrectomy, ischemic reperfusion injury, or dexamethasone treatment. We obtained samples from 27 children, of which 12 had CKD due to congenital (n = 7) and perinatal (n = 5) causes. Plasma D-asparagine and the D/L-serine ratio had robust, positive linear associations with serum creatinine and cystatin C, and detected CKD with high sensitivity and specificity, uninfluenced by body size or biochemical parameters. In the animal study, kidney dysfunction increased plasma D-asparagine and the D/L-serine ratio, but dexamethasone treatment did not. Thus, plasma D-asparagine and the D/L-serine ratio can be useful markers for renal function in children.

D-Serine as a sensor and effector of the kidney.

D-Serine, a rare enantiomer of serine, is a biomarker of kidney disease and function. The level of D-serine in the human body is precisely regulated through the urinary clearance of the kidney, and its clearance serves as a new measure of glomerular filtration rate with a lower bias than creatinine clearance. D-Serine also has a direct effect on the kidneys and mediates the cellular proliferation of tubular cells via mTOR signaling and induces kidney remodeling as a compensatory reaction to the loss of kidney mass. In living kidney donors, the removal of the kidney results in an increase in blood D-serine level, which in turn accelerates kidney remodeling and augments kidney clearance, thus reducing blood levels of D-serine. This feedback system strictly controls D-serine levels in the body. The function of D-serine as a biomarker and modulator of kidney function will be the basis of precision medicine for kidney diseases.

Demographics and treatment of patients with primary membranoproliferative glomerulonephritis in Japan using a national registry of clinical personal records.

BACKGROUND: Membranoproliferative glomerulonephritis (MPGN) is a rare glomerular injury that causes nephrotic syndrome and end-stage kidney disease. The nationwide demographics and treatment of Japanese patients with primary MPGN have not yet been reported. METHODS: We collected clinical personal records of patients with primary MPGN between 2015 and 2018 from the national registry organized by the Japanese Ministry of Health, Labour, and Welfare and investigated the characteristics of primary MPGN throughout Japan. RESULTS: Of 258 patients with primary MPGN, 199 and 59 showed nephrotic and non-nephrotic syndrome, respectively. The median age at onset was higher in patients with nephrotic syndrome than in those with non-nephrotic syndrome (45 [24-63] vs. 35 [14-53] years, respectively; P = 0.010). The use of oral prednisolone was significantly higher in patients with nephrotic syndrome than in those with non-nephrotic syndrome (73.9% vs. 59.3%, respectively; P = 0.032). When patients were divided into three age groups: adolescent and young adult group (≤ 39 years; n = 80), middle adult group (40-64 years; n = 111), and older adult group (≥ 65 years; n = 67), the use of oral prednisolone, cyclosporine, and mizoribine was significantly higher in the adolescent and young adult group than in the middle adult group. The mean dosage of oral prednisolone and mizoribine showed no differences among the three age groups. CONCLUSION: The national registry of clinical personal records of primary MPGN could provide an informative insight into the characteristics, clinical features, and treatment approaches for patients with primary MPGN in Japan.

Profiling of kidney involvement in systemic lupus erythematosus by deep learning using the National Database of Designated Incurable Diseases of Japan.

BACKGROUND: Kidney involvement frequently occurs in systemic lupus erythematosus (SLE), and its clinical manifestations are complicated. We profiled kidney involvement in SLE patients using deep learning based on data from the National Database of Designated Incurable Diseases of Japan. METHODS: We analyzed the cross-sectional data of 1655 patients with SLE whose Personal Clinical Records were newly registered between 2015 and 2017. We trained an artificial neural network using clinical data, and the extracted characteristics were evaluated using an autoencoder. We tested the difference of population proportions to analyze the correlation between the presence or absence of kidney involvement and that of other clinical manifestations. RESULTS: Data of patients with SLE were compressed in a feature space in which the anti-double-stranded deoxyribonucleic acid (anti-dsDNA) antibody titer, antinuclear antibody titer, or white blood cell count contributed significantly to distinguishing patients. Many SLE manifestations were accompanied by kidney involvement, whereas in a subgroup of patients with high anti-dsDNA antibody titers and low antinuclear antibody titers, kidney involvement was positively and negatively correlated with hemolytic anemia and inflammatory manifestations, respectively. CONCLUSION: Although there are various combinations of SLE manifestations, our study revealed that some of them are specific to kidney involvement. SLE profiles extracted from the objective analysis will be useful for categorizing SLE manifestations.

Establishment and clinical application of SARS-CoV-2 catch column.

BACKGROUND: A certain number of patients with coronavirus disease 2019 (COVID-19), particularly those who test positive for SARS-CoV-2 in the serum, are hospitalized. Further, some even die. We examined the effect of blood adsorption therapy using columns that can eliminate SARS-CoV-2 on the improvement of the prognosis of severe COVID-19 patients. METHODS: This study enrolled seven patients receiving mechanical ventilation. The patients received viral adsorption therapy using SARS-catch column for 3 days. The SARS-catch column was developed by immobilizing a specific peptide, designed based on the sequence of human angiotensin-converting enzyme 2 (hACE2), to an endotoxin adsorption column (PMX). In total, eight types of SARS-CoV-2-catch (SCC) candidate peptides were developed. Then, a clinical study on the effects of blood adsorption therapy using the SARS-catch column in patients with severe COVID-19 was performed, and the data in the present study were compared with historical data of severe COVID-19 patients. RESULTS: Among all SCC candidate peptides, SCC-4N had the best adsorption activity against SARS-CoV-2. The SARS-catch column using SCC-4N removed 65% more SARS-CoV-2 than PMX. Compared with historical data, the weaning time from mechanical ventilation was faster in the present study. In addition, the rate of negative blood viral load in the present study was higher than that in the historical data. CONCLUSION: The timely treatment with virus adsorption therapy may eliminate serum SARS-CoV-2 and improve the prognosis of patients with severe COVID-19. However, large-scale studies must be performed in the future to further assess the finding of this study (jRCTs052200134).

Public support for patients with intractable diseases in Japan: impact on clinical indicators from nationwide registries in patients with autosomal dominant polycystic kidney disease.

BACKGROUND: Clinical practice guidelines recommend antihypertensive and tolvaptan therapies for patients with autosomal dominant polycystic kidney disease (ADPKD) in Japan. However, tolvaptan therapy may pose an economic burden. The Japanese Ministry of Health, Labour and Welfare supports patients with intractable diseases. This study aimed to confirm the impact of the intractable disease system in Japan on the clinical treatment of ADPKD. METHODS: We analyzed the data of 3768 patients with ADPKD having a medical subsidy certificate from the Japanese Ministry of Health, Labour and Welfare in 2015-2016. The following quality indicators were use: the adherence rate to the 2014 clinical practice guideline for polycystic kidney disease (prescription rates of antihypertensive agents and tolvaptan in this cohort) and the number of Japanese patients with ADPKD nationwide started on renal replacement therapy in 2014 and 2020. RESULTS: Compared with new applications from 2015 to 2016, the prescription rates of antihypertensives and tolvaptan for the indicated patients at the 2017 renewal application increased by 2.0% (odds ratio = 1.41, p = 0.008) and 47.4% (odds ratio = 10.1, p > 0.001), respectively. These quality indicators improved with antihypertensive treatment, especially in patients with chronic kidney disease stages 1-2 (odds ratio = 1.79, p = 0.013) and in those aged < 50 years (odds ratio = 1.70, p = 0.003). The number of patients with ADPKD who were started on renal replacement therapy in Japan decreased from 999 in 2014 to 884 in 2020 in the nationwide database (odds ratio = 0.83, p < 0.001). CONCLUSIONS: The Japanese public intractable disease support system contributes to improvement of ADPKD treatment.

Circulating extracellular vesicles carrying Firmicutes reflective of the local immune status may predict clinical response to pembrolizumab in urothelial carcinoma patients.

Bacterial flora has clinical significance for the host. The metabolic environment created by this flora influences immunotherapy in urothelial carcinoma. However, there are no reports on the clinical significance of bacterial flora in the host bloodstream. We aimed to clarify the correlation between extracellular vesicle (EV)-derived blood microflora information and tumor immunological status in urothelial carcinoma (UC) patients. Serum samples were collected from 20 healthy donors, 50 patients with localized UC, and 31 patients with metastatic UC (mUC) who had undergone pembrolizumab treatment. Bacterial DNA in EVs was extracted from each sample. Metagenomic sequencing was performed after amplification of the V1-V2 region of the bacterial 16S rRNA gene. Using the matched tumor tissue and serum samples, we revealed that the smaller amount of peripheral EVs carrying Firmicutes DNA was significantly correlated with the higher number of infiltrating T cells within tumor tissues (CD3; p = 0.015, CD4; p = 0.039, CD8; p = 0.0084) and the higher expression of activation markers on their surface (ICOS on both CD4; p = 0.0013 and CD8 T cells; p = 0.016 and 4-1BB on CD4 T cells; p = 0.016). In terms of circulating metabolic information, L-Ser and L-Pro levels, which play important roles in T cell expansion and proliferation, were significantly higher in the Firmicutes-low group (p = 0.010). All of the patients with higher Firmicutes abundance had disease progression without any clinical response (p = 0.026) and significantly inferior prognosis for pembrolizumab therapy (p = 0.035). This is the first study on the importance of peripheral bacterial EVs in cancer patients treated with cancer immunotherapy.

Deep learning analysis of clinical course of primary nephrotic syndrome: Japan Nephrotic Syndrome Cohort Study (JNSCS).

BACKGROUND: Prognosis of nephrotic syndrome has been evaluated based on pathological diagnosis, whereas its clinical course is monitored using objective items and the treatment strategy is largely the same. We examined whether the entire natural history of nephrotic syndrome could be evaluated using objective common clinical items. METHODS: Machine learning clustering was performed on 205 cases from the Japan Nephrotic Syndrome Cohort Study, whose clinical parameters, serum creatinine, serum albumin, dipstick hematuria, and proteinuria were traceable after kidney biopsy at 5 measured points up to 2 years. The clinical patterns of time-series data were learned using long short-term memory (LSTM)-encoder-decoder architecture, an unsupervised machine learning classifier. Clinical clusters were defined as Gaussian mixture distributions in a two-dimensional scatter plot based on the highest log-likelihood. RESULTS: Time-series data of nephrotic syndrome were classified into four clusters. Patients in the fourth cluster showed the increase in serum creatinine in the later part of the follow-up period. Patients in both the third and fourth clusters were initially high in both hematuria and proteinuria, whereas a lack of decline in the urinary protein level preceded the worsening of kidney function in fourth cluster. The original diseases of fourth cluster included all the disease studied in this cohort. CONCLUSIONS: Four kinds of clinical courses were identified in nephrotic syndrome. This classified clinical course may help objectively grasp the actual condition or treatment resistance of individual patients with nephrotic syndrome.

Effect of matcha consumption on gut microbiota in healthy Japanese individuals: study protocol for a double-blind crossover interventional study.

This study compares and clarifies the changes in intestinal flora resulting from the continuous consumption of two types of matcha. Healthy adults will consume two types of matcha tea for four weeks, and differences in the intestinal microflora before and after drinking will be compared. Gut microbiota will be identified using next-generation sequencing. Phylogenetic classification of the enterobacteria will be performed based on sequence similarities. The relative proportions of the classified enterobacteria to the total nucleotide sequences will be compared between the samples obtained from the two groups consuming different matcha. The continuous consumption of matcha may improve dysbiosis and prevent atherosclerosis. The effects may vary according to the type of matcha used. Trial registration: The study was registered with university hospital medical information network (UMIN) (UMIN000040303), and all participants gave their written informed consent. Registered 1 November 2020, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000045982.

Dedicated SNAREs and specialized TRIM cargo receptors mediate secretory autophagy.

Autophagy is a process delivering cytoplasmic components to lysosomes for degradation. Autophagy may, however, play a role in unconventional secretion of leaderless cytosolic proteins. How secretory autophagy diverges from degradative autophagy remains unclear. Here we show that in response to lysosomal damage, the prototypical cytosolic secretory autophagy cargo IL-1ß is recognized by specialized secretory autophagy cargo receptor TRIM16 and that this receptor interacts with the R-SNARE Sec22b to recruit cargo to the LC3-II+ sequestration membranes. Cargo secretion is unaffected by downregulation of syntaxin 17, a SNARE promoting autophagosome-lysosome fusion and cargo degradation. Instead, Sec22b in combination with plasma membrane syntaxin 3 and syntaxin 4 as well as SNAP-23 and SNAP-29 completes cargo secretion. Thus, secretory autophagy utilizes a specialized cytosolic cargo receptor and a dedicated SNARE system. Other unconventionally secreted cargo, such as ferritin, is secreted via the same pathway.

Intra-body dynamics of D-serine reflects the origin of kidney diseases.

INTRODUCTION: D-Serine, present only in trace amounts in humans, is now recognized as a biomarker of chronic kidney disease (CKD). CKD is heterogeneous in its original kidney diseases, whose diagnoses require kidney biopsy. In this study, we examined whether the intra-body dynamics of D-serine, indexed by its blood and urinary levels, reflects the origin of kidney diseases. METHODS: Patients with six kinds of kidney disease undergoing kidney biopsy were enrolled in a single center. Levels of D- and L-serine were measured using two-dimensional high-performance liquid chromatography. The associations between the origin of kidney diseases and the intra-body dynamics of D-serine were examined using multivariate cluster analyses. RESULTS: Unlike the non-CKD profile, patients with CKD showed broadly-distributed profiles of intra-body dynamics of D-serine. The plasma level of D-serine plays a key role in the detection of kidney diseases, whereas a combination of plasma and urinary levels of D-serine distinguished the origin of CKD, especially lupus nephritis. CONCLUSION: Intra-body dynamics of D-serine have the potential to predict the origin of kidney diseases. Monitoring of D-serine may guide specific treatments for the origin of kidney diseases.

Immune modulating effects of additional supplementation of estradiol combined with testosterone in murine testosterone-deficient NAFLD model.

Nonalcoholic fatty liver disease (NAFLD) is associated with testosterone deficiency. However, NAFLD patients generally do not respond to treatment with testosterone alone. We investigated the innate immune mechanisms underlying the effects of treatment with testosterone alone, estrogen alone, or combined testosterone and estrogen on high-fat diet (HFD)-induced NAFLD due to testosterone deficiency. Orchiectomized (OCX) male Rag2-/- mice were used as a model of testosterone deficiency. To assess NAFLD severity, NAFLD activity score (NAS) is adopted. Moreover, immunological change was analyzed by multicolor flow cytometry. Treatment with both testosterone and estrogen significantly decreased body weight to that of the sham mice/normal diet (ND). NAS and liver fibrosis in OCX-HFD mice were significantly deteriorated, and treatment with testosterone and estrogen improved same as sham-ND mice. HFD increased the ratio of both type 2 and 3 innate lymphoid cells (ILC2s and ILC3s) to CD45-positive cells in the liver. Treatment with testosterone alone decreased the ratio of ILC2 to CD45 but not the ILC3-to-CD45 ratio. Addition of estrogen to the treatment reduced the ratios of ILC2-to-CD45 and ILC3-to-CD45 to the same level observed in sham-HFD mice. Moreover, OCX-HFD mice had a decreased proportion of M2 macrophages compared with sham-ND mice. Treatment with testosterone alone did not restore the proportion of M2 macrophages; however, combination treatment with both estrogen and testosterone increased that to the same level as that in sham-HFD mice. Treatment with both testosterone and estrogen improves liver fibrosis and decreases ILC3 and increases M2 macrophage abundance in the liver.NEW & NOTEWORTHY The progression of nonalcoholic fatty liver disease (NAFLD) is associated with testosterone deficiency. NAFLD patients generally do not respond to treatment with testosterone alone. In animal studies, treatment with testosterone and estrogen reduced the ratios of ILC2:CD45 and ILC3:CD45 and increased M2 macrophages in liver. Our study suggests, based on our immunological data, that a combination of estrogen and testosterone may be clinically relevant for the treatment of NAFLD in patients with male menopause.

D-Amino acids and kidney diseases.

D-Amino acids are the recently detected enantiomers of L-amino acids. Accumulating evidence points their potential in solving the long-standing critical problems associated with the management of both chronic and acute kidney diseases. This includes estimating kidney function, early diagnosis and prognosis of chronic kidney disease, and disease monitoring. Among the D-amino acids, D-serine levels in the blood are strongly correlated with the glomerular filtration rate and are useful for estimating the function of the kidney. Urinary D-serine also reflects other conditions. The kidney proximal tubule reabsorbs serine with chiral-selectivity, with D-serine being reabsorbed much less efficiently than L-serine, and urinary excretion of D-serine is sensitive to the presence of kidney diseases. Therefore, assessing the intra-body dynamics of D-serine by measuring its level in blood and urinary excretion can be used to detect kidney diseases and assess pathophysiology. This new concept, the intra-body dynamics of D-serine, can be useful in the comprehensive management of kidney disease.

Three-Dimensional High-Performance Liquid Chromatographic Determination of Asn, Ser, Ala, and Pro Enantiomers in the Plasma of Patients with Chronic Kidney Disease.

The concentrations of several d-amino acids have been reported to significantly increase in the plasma of patients with chronic kidney disease (CKD). However, the amounts of these d-amino acids are low (around 1% of the l-form or lower), and their analyses were complicated by various interfering compounds in many clinical samples. A highly selective analytical method is thus required to perform the accurate and precise determination of these d-amino acids in the plasma of CKD patients. In the present study, a selective 3D-HPLC system equipped with reversed-phase, anion-exchange, and enantioselective columns has been designed and developed for the determination of the asparagine, serine, alanine and proline enantiomers. For the sensitive analysis, amino acids were precolumn derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole and detected by their fluorescence. The system was validated by using human plasma in addition to the standard amino acids, and results with a sufficient linearity, precision, and accuracy were obtained. The 3D-HPLC system was applied to the plasma of patients with different stages of CKD and all of the target d-amino acids were clearly observed without interferences for all 25 tested patients. Good correlations were shown between the kidney function of the patients and the %d values of the target analytes, especially d-Asn and d-Ser, indicating that the present 3D-HPLC method is useful for the sensitive diagnosis of CKD.

Reverse translational research of autophagy and metabolism in kidney disease: Oshima Award Address 2018.

The management of chronic kidney disease (CKD) has been a great challenge. Focusing on the difficulty to predict the prognosis of CKD, we initially conducted a series of observational studies, and evaluated the prognostic impacts of cardiac, diabetic, kidney, as well as senescent profiles, on CKD. Aiming to protect tubular inflammatory lesions, we studied the roles of autophagy, a process of auto-degradation for cellular homeostasis, in kidney diseases. After having determined its protective role, the proceedings of our autophagy studies are now revealing the mechanisms whereby autophagy protects kidney; autophagy protects kidney from DNA damage, and oxidative and metabolic stress. These emerging roles of autophagy converged on the concept that quality control of organelles (mitochondria and lysosomes), as well as the regulation of metabolism, are the key to protect kidney from diseases, ranging from CKD, acute kidney injury (AKI) to aging kidney. To broaden the clinical potential of autophagy, some cellular and molecular studies were followed up to identify the specific targets of autophagy. Having encountered the critical roles of metabolism in kidney diseases, we conducted a subset of clinical studies, and found that D-amino acids, the chiral derivatives of L-amino acids, can predict the prognosis of CKD. D-Amino acids, normally present in only trace amounts in humans, would be potential candidates for the biomarkers in CKD. The intersections between clinical and basic research provided us a potential approach for the better kidney management, reconfirming the aspects that the reverse translational study is an excellent method for the kidney research.

Effects of dietary salt restriction on home blood pressure in diabetic patients with excessive salt intake: a pilot study.

The aim of the present study was to examine whether dietary salt restriction guidance is beneficial for dietary salt restriction and lowering of home blood pressure in patients with diabetes with excessive salt intake. We performed an intervention trial of 37 people with type 2 diabetes and excessive salt intake. National registered dietitians provided dietary salt restriction guidance to each patient at the start of the study. All participants were instructed to perform triplicate morning and evening home blood pressure measurements using home blood pressure telemonitoring system. Daily salt intake at 2 months and 6 months was significantly lower than that at baseline; the difference was 0.8 [95% confidence interval (CI): 0.2-1.4, p = 0.009] g and 0.7 (95% CI: 0.1-1.3, p = 0.009) g, respectively. Morning systolic blood pressure at 2 months and 6 months was significantly lower than that at baseline; the difference was 2.7 (95% CI: 0.2-5.1, p = 0.034) mmHg and 5.8 (95% CI: 0.5-11.1, p = 0.034) mmHg, respectively. This intervention study revealed, for the first time, that dietary salt restriction guidance provided by a national registered dietitian is beneficial for reducing daily salt intake and home blood pressure in people with diabetes with excessive salt intake.