Uremia Impedes Skeletal Myocyte Myomixer Expression and Fusogenic Activity: Implication for Uremic Sarcopenia.

In patients with chronic kidney disease (CKD), skeletal muscle mass and function are known to occasionally decline. However, the muscle regeneration and differentiation process in uremia has not been extensively studied. In mice with CKD induced by adenine-containing diet, the tibialis anterior muscle injured using a barium chloride injection method recovered poorly as compared to control mice. In the cultured murine skeletal myocytes, stimulation with indoxyl sulfate (IS), a representative uremic toxin, morphologically jeopardized the differentiation, which was counteracted by L-ascorbic acid (L-AsA) treatment. Transcriptome analysis of cultured myocytes identified a set of genes whose expression was down-regulated by IS stimulation but up-regulated by L-AsA treatment. Gene silencing of myomixer, one of the genes in the set, impaired myocyte fusion during differentiation. By contrast, lentiviral overexpression of myomixer compensated for a hypomorphic phenotype caused by IS treatment. The split-luciferase technique demonstrated that IS stimulation negatively affected early myofusion activity that was rescued by L-AsA treatment. Lastly, in mice with CKD compared with control mice, myomixer expression in the muscle tissue in addition to the muscle weight after the injury was reduced, both of which were restored with L-AsA treatment. Collectively, data showed that the uremic milieu impairs the expression of myomixer and impedes the myofusion process. Considering frequent musculoskeletal injuries in uremic patients, defective myocyte fusion followed by delayed muscle damage recovery could underlie their muscle loss and weakness.

Neutrophil Protein Kinase R Mediates Endothelial Adhesion and Migration by the Promotion of Neutrophil Actin Polymerization.

Neutrophils protect against bacterial and fungal infections, but tight regulation of cell activation is essential for avoiding tissue damage in autoimmune disorders. Protein kinase R (PKR) is a serine/threonine kinase originally characterized by its role in the defense mechanisms against viral infection. Although PKR is involved in the signaling pathways of neurodegenerative diseases and metabolic disorders, its function in neutrophils is not well delineated. In this study, we demonstrate that human neutrophil PKR mediates adhesion to endothelial cells under physiological flow conditions but does not mediate rolling on those cells. Also, neutrophil PKR activation contributes to migration toward chemoattractants. Mechanistically, neutrophil PKR mediates the cell spreading and binding to ICAM-1 in static condition. Moreover, Ab microarray reveals that calcium/calmodulin-dependent protein kinase II is phosphorylated downstream of PKR and affects actin polymerization that is a cytoskeleton rearrangement indispensable for neutrophil migration induced by fMLF. In vivo, neutrophil recruitment into the dorsal air pouch of mice is reduced by PKR inhibitor treatment. Also, in mice with nephrotoxic serum nephritis, the compound treatment suppresses neutrophil accumulation in kidney glomerulus and subsequent development of albuminuria. Thus, in vascular inflammation, neutrophil PKR plays a critical role in the recruitment process, including endothelial adhesion and migration via leukocyte actin polymerization.

Chronic kidney disease prevalence and awareness in middle age and young old: Regional comparative study in Japan.

AIM: Patients with chronic kidney disease are not aware of the illness because of its asymptomatic nature, but the association of disease progression and awareness in general population has not been sufficiently analysed on a large scale. METHODS: We analysed the nationwide annual specific health checkup covering more than a half of the overall population at aged 40-74 in Japan, approximately 29.4 million people as of 2018, in combination with parameters to represent regional characteristics. RESULTS: The rate of the examinees with kidney dysfunction, an estimated glomerular filtration rate of <45 mL/min/1.73 m2 , was 1.0%, while that of examinees with of dipstick proteinuria ≥ (+) was 3.7%. Next, we conducted a regional comparative study on 335 medical administrative areas divided in the country. The regional rate of examinees aged 65-74 over the total examinees was positively correlated with the prevalence of kidney dysfunction (r = 0.72, p < .0001). Additionally, the mean rate of examinees aware of their 'chronic kidney failure' was 0.6%, and the awareness rate was correlated with the prevalence of both kidney dysfunction (r = 0.36, p < .001) and positive dipstick proteinuria (r = 0.31, p < .001) in those aged 65-74 at the regional level. Association of nephrology care resources with the prevalence or awareness was unclear at the regional level. CONCLUSION: We found a regional association of chronic kidney disease prevalence and awareness in a recent young old population in Japan. Further studies are needed to evaluate the patient screen and referral at the individual level.

Overexpressed angiotensin-converting enzyme in neutrophils suppresses glomerular damage in crescentic glomerulonephritis.

While angiotensin-converting enzyme (ACE) regulates blood pressure by producing angiotensin II as part of the renin-angiotensin system, we recently reported that elevated ACE in neutrophils promotes an effective immune response and increases resistance to infection. Here, we investigate if such neutrophils protect against renal injury in immune complex (IC)-mediated crescentic glomerulonephritis (GN) through complement. Nephrotoxic serum nephritis (NTN) was induced in wild-type and NeuACE mice that overexpress ACE in neutrophils. Glomerular injury of NTN in NeuACE mice was attenuated with much less proteinuria, milder histological injury, and reduced IC deposits, but presented with more glomerular neutrophils in the early stage of the disease. There were no significant defects in T and B cell functions in NeuACE mice. NeuACE neutrophils exhibited enhanced IC uptake with elevated surface expression of FcγRII/III and complement receptor CR1/2. IC uptake in neutrophils was enhanced by NeuACE serum containing elevated complement C3b. Given no significant complement activation by ACE, this suggests that neutrophil ACE indirectly preactivates C3 and that the C3b-CR1/2 axis and elevated FcγRII/III play a central role in IC elimination by neutrophils, resulting in reduced glomerular injury. The present study identified a novel renoprotective role of ACE in glomerulonephritis; elevated neutrophilic ACE promotes elimination of locally formed ICs in glomeruli via C3b-CR1/2 and FcγRII/III, ameliorating glomerular injury.NEW & NOTEWORTHY We studied immune complex (IC)-mediated crescentic glomerulonephritis in NeuACE mice that overexpress ACE only in neutrophils. Such mice show no significant defects in humoral immunity but strongly resist nephrotoxic serum nephritis (less proteinuria, milder histological damage, reduced IC deposits, and more glomerular neutrophils). NeuACE neutrophils enhanced IC uptake via increased surface expression of CR1/2 and FcgRII/III, as well as elevated serum complement C3b. These results suggest neutrophil ACE as a novel approach to reducing glomerulonephritis.

Lay A TRAP for myeloid cell response in diabetic kidney disease.

The functions of the renin-angiotensin system are crucial in the progression of diabetic kidney disease. ATRAP is a type 1 angiotensin II receptor-associated protein that negatively regulates intracellular angiotensin II signaling. In this issue, Haruhara et al. revealed that ATRAP deficiency of diabetic mice decreases anti-inflammatory macrophage infiltration and exacerbates albuminuria. The adoptive transfer and tubule-specific depletion of ATRAP highlight the crosstalk between glomerular injury and tubulointerstitial angiotensin II signaling and innate immunity.

Cost-Effectiveness of Dapagliflozin for Chronic Kidney Disease in Japan.

BACKGROUND: The cost-effectiveness of sodium-glucose cotransporter 2 (SGLT2) inhibitors for chronic kidney disease (CKD) has not been evaluated in Japan, so we analyzed the cost-effectiveness of dapagliflozin, an SGLT2 inhibitor, for CKD stages 3a and 3b.Methods and Results: We used the Markov model for CKD to assess the costs and benefits associated with and without dapagliflozin from a health system perspective. We estimated the incremental cost-effectiveness ratio (ICER), expressed as per quality-adjusted life-years (QALYs). An ICER <5 million Japanese yen (JPY)/QALY was judged to be cost-effective. The effect of dapagliflozin on renal and cardiovascular events was based on published clinical trials. In patients with CKD stage 3a, the ICER of dapagliflozin over standard treatment was 4.03 million JPY/QALY gained. With a cost-effectiveness threshold of 5 million JPY/QALY gained, the cost-effectiveness probability of dapagliflozin over standard treatment was 52.6%. In patients with CKD stage 3b, the ICER of dapagliflozin over standard treatment was 0.12 million JPY/QALY gained. The cost-effectiveness probability of dapagliflozin over standard treatment was 75.2%. CONCLUSIONS: The results seemed to show acceptable cost-effectiveness when dapagliflozin was used for CKD stage 3b. On the other hand, cost-effectiveness of dapagliflozin for CKD stage 3a was ambiguous, and further validation is needed.

Motion-capture technique-based interface screen displaying real-time probe position and angle in kidney ultrasonography.

Professional skill is required to reproduce ultrasound images of the kidney as an optimal cross-section is easily lost with slight deviation in scanning location or angle of the probe. We developed a motion-capture technique-based interface screen that displays the real-time probe position and angle to overlap those provided beforehand. When a professional operator captured the approximate kidney image, our system recorded the relative spatial relationship between the subject and the probe. Next, an amateur operator who had no experience of clinical practice manipulated the probe only with the aid of the interface until the probe position and angle coincided with the professional ones. Eventually, amateur operators could place the probe with a deviation of distance of (x = 2.7 ± 1.2 mm, y = 3.0 ± 1.7 mm, z = 6.6 ± 1.8 mm) and angle of (Rx = 1.5 ± 0.3 degrees, Ry = 2.6 ± 1.1 degrees, Rz = 1.1 ± 0.3 degrees) from the professional goal to produce very similar cross-sectional kidney images (N = 8). Also, motion-capture technique-based evaluation of relative locations of the probe and subject body revealed difficulty in reproducing those without the interface screen navigation. In summary, our motion-capture technique-based ultrasound guide system provides operators with the opportunity to handle the probe just as another operator would beforehand. This could help in medical procedures wherein the same cross-sectional image should be repeatedly obtained. Moreover, it requires no conventional probe training for beginners and could even shift the paradigm for ultrasound probe handling.

Regional Distribution of Cardiologists and Prescription Patterns of Sodium-Glucose Transporter-2 Inhibitors in Japan.

The clinical evidence is accumulating since 2015 that anti-diabetic sodium-glucose cotransporter 2 (SGLT2) inhibitors have the beneficial effect of cardiovascular and, recently, renal protection. Although it is not well analyzed how the transfer of this new evidence into daily practice has expedited, we hypothesize that the recent usage of the drugs is positively associated with several certified cardiologists in each region.The 2016 annual and 2016-2017 increased number of SGLT2 inhibitor tablets, based on the National Database of Health Insurance Claims and Specific Health Checkups of Japan, were divided by the estimated number of patients with type 2 diabetes mellitus for each of the 47 prefectures. Then, regression analyses were performed to investigate the potential association of the number of certified cardiologists with the drug prescription.The 2016 prescription of ipragliflozin, dapagliflozin, luseogliflozin, canagliflozin, and empagliflozin was 2.7- to 4.4-fold different between prefectures. The 2016-2017 increased prescription volume also varied among prefectures by as large as 7.3-fold for ipragliflozin. Regression analysis revealed that the annual and increased prescription volume of all the SGLT2 inhibitors except luseogliflozin were higher in regions with more certified cardiologists (P < 0.05), even after adjusting for regional parameters.In conclusion, the regional number of certified cardiologists was positively associated with a 2016 annual of and 2016-2017 increase in SGLT2 inhibitor prescription amount, implying an early adopter role of clinical experts in healthcare delivery.

Renal thrombotic microangiopathy during nintedanib treatment for idiopathic pulmonary fibrosis
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Agents that block vascular endothelial growth factor (VEGF) and its downstream pathway have been reported to be associated with nephrotoxicity including hypertension, proteinuria, and renal dysfunction. Bevacizumab, a monoclonal antibody against VEGF, is known to cause thrombotic microangiopathy (TMA), while tyrosine kinase inhibitors (TKIs) that block VEGF downstream are mainly associated with minimal change disease or focal segmental glomerulosclerosis. The question regarding the source of the diverse phenotypes of nephrotoxicity associated with these agents remains enigmatic. Nintedanib, a multitargeted TKI, blocks fibroblast growth factor and platelet-derived growth factor receptor as well as VEGF receptor, and is indicated for the treatment of idiopathic pulmonary fibrosis. We describe a case of a 45-year-old male who presented with isolated proteinuria of 1.3 g/g Cr 3 years after beginning nintedanib treatment. The kidney biopsy revealed histological features consistent with renal TMA. He underwent single lung transplantation 6 months later, which enabled cessation of nintedanib, and, 1 month later, his proteinuria results were negative. Unlike other types of TKIs, the pathological findings of nintedanib-induced nephrotoxicities have been limitedly reported. This is the first case of isolated proteinuria likely caused by nintedanib-induced TMA.

Diagnostic accuracy of urine dipstick for proteinuria category in Japanese workers.

BACKGROUND: Urine dipstick tests are often used to evaluate proteinuria during health checkups. We examined the dipstick's accuracy in assessing the proteinuria levels among Japanese workers. METHODS: We assessed subjects aged ≥ 18 years who had a health checkup at the University of Tokyo in 2016 or 2017 (n = 5383). Proteinuria was stratified by urine protein-to-creatinine ratio (PCR): A1, < 150 mg/gCre; A2, 150-499 mg/gCre; and A3, ≥ 500 mg/gCre. The accuracy of a dipstick result of ± or higher to detect a PCR level of ≥ A2 was examined. We compared changes in dipstick results and PCR level in 136 subjects evaluated twice with a median interval of 119 days. RESULTS: The subjects' mean age was 40 years, and half were women. The dipstick results were - in 94.9%, ± in 4.1%, and ≥ 1 + in 1.0%. The PCR level was A1, A2, A3 in 98.6%, 1.2%, and 0.2% of the subjects, respectively. The sensitivity, specificity, and positive and negative predictive values of a ± or higher dipstick result to detect A2 or higher were 66.2%, 95.6%, 17.5%, and 99.5%, respectively. Among the 136 subjects examined twice, 134 (98.5%) had no change in PCR level (A1 in all cases) despite a decrease or increase in dipstick results. CONCLUSION: Urine dipstick results of ± or above had a high specificity but low sensitivity and positive predictive value to detect PCR proteinuria of A2 or higher. Confirmation by quantitative protein measurement should be recommended for individuals at high risk of chronic kidney disease.

Regional variance in the use of urine dipstick test for outpatients in Japan.

AIM: The urine dipstick is a simple diagnostic module for detecting proteinuria, haematuria and glycosuria and is favourably accepted in East Asia despite debates regarding its accuracy and target population, claiming that quantitative tests for a high-risk cohort should be more cost-effective. However, the current status of utilizing this test in these countries is not widely known due to lack of extensive data. We aimed to clarify the current nationwide and regional status of utilization of the urine dipstick test in an outpatient care setting and to determine the regional factors associated with adoption of this method. METHODS: This cross-sectional study used openly accessible data from the national claim database that included the health insurance claims data of the Japanese population in 2017. RESULTS: In total, 67 125 386 urine dipstick tests were performed compared with 1 862 700 quantitative urine protein tests and 17 544 949 urine sediment microscopy tests. Dipstick tests were employed principally for those who are >65 years old (60.3%) and, although the male population (52.5%) is generally larger, the female population is larger in age of 15 to 39 years and >85 years. Multivariate analysis with several regional parameters revealed that the test was performed more commonly in the areas that accommodate greater elderly population (P < .01). CONCLUSION: Despite a heated dispute, the urine dipstick test is performed even more frequently than the quantitative biochemical or microscopic sediment tests, especially in regions holding the larger elderly population, which suggests that the test forms a part of geriatric medical care.

Porcupine's dilemma in kidney fibrosis.

Aberrant activation of Wnt/ß-catenin signaling, an activity that is critically modulated by porcupine, a membrane-bound O-acyltransferase, is profibrotic. Previously, the Crowley laboratory demonstrated that oral administration of porcupine inhibitor attenuated experimental mouse kidney fibrosis. Now Lu et al., from that laboratory, using conditional knockout lineages, have shown that porcupine in the renal tubule accelerated fibrosis and Wnt generation, whereas myeloid cell porcupine counteracted the effect. Thus, porcupine has been attracting both positive and negative attention.

Neutrophils in lupus nephritis.

PURPOSE OF REVIEW: Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease characterized by IgG-autoantibodies to nuclear antigens that can deposit in the kidney and trigger lupus nephritis. Neutrophils accumulate in the kidneys of patients with proliferative LUPUS NEPHRITIS and neutrophil products and a subset of granulocytes, called low-density granulocytes (LDG) may contribute to lupus nephritis pathogenesis. Here, we will discuss recent studies implicating neutrophils in the pathogenesis of human SLE nephritis and then examine studies that provide mechanistic insights into how these cells are recruited to the glomerulus following immune complex deposition and how their products may promote lupus nephritis. RECENT FINDINGS: SLE patients display unique blood transcriptional signatures linked to Type I interferon and myeloblast differentiation, which could help stratify lupus nephritis progression. Multiphoton intravital microscopy of kidney glomerular capillaries revealed a role for neutrophil FcγRs in the rapid capture of neutrophils following immune complex deposition. The view that reduced degradation of neutrophil extracellular traps (NETS) contributes to lupus nephritis progression, is now challenged by experimental data in lupus-prone mice that genetically fail to produce NETS but still are afflicted. SUMMARY: A greater understanding of the neutrophil dependent mechanisms that promote lupus nephritis may potentially inform on newer therapeutic options that target neutrophil accumulation and reactivity in the nephritic kidney.

Regional variance in patterns of prescriptions for chronic kidney disease in Japan.

BACKGROUND: This study aims to describe the regional variance in prescriptions for chronic kidney disease (CKD) medications and to analyze regional characteristics to identify the sources of these differences by utilizing the National Database of Health Insurance Claims, which provides more than 95% of nationwide claim information for Japan. METHODS: Data regarding the total claimed amount for phosphate binders (PBs), erythropoiesis-stimulating agents (ESAs), carbonaceous adsorbents, and potassium-lowering agents in fiscal year 2015 were obtained. Correlation coefficients were calculated for the claimed amount of these drugs per CKD patient and social and medical variables, including the percentage of the population aged ≥ 65 years and the numbers of hospital beds and certified nephrologists. Subsequent multiple regression analysis was performed using explanatory factors affecting the amount of PB or ESA prescriptions per CKD patient. RESULTS: The total claimed amounts were 585,485,115 for PBs and 2,373,777 for ESAs. Variations in the claimed amount per CKD patient among 47 prefectures were 4.9-, 6.1-, 6.6-, and 6.0-fold for PBs, ESAs, carbonaceous adsorbents and potassium-lowering agents, respectively. The number of nephrologists per CKD patient was positively correlated with the prescribed amount for PBs and ESAs per CKD patient, and independently associated with the prescribed amount also in regression analysis. CONCLUSION: Substantial regional variation in CKD-related drug prescriptions exists even within a uniform health care system. The number of certified nephrologists was associated with the prescribed amount for PBs and ESAs. Further studies are needed to clarify whether geographic distribution of certified nephrologist may affect clinical practice pattern.

A Cenozoic record of the equatorial Pacific carbonate compensation depth.

Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.

Angiopoietin-like protein 2 and kidney fibrosis: lessons from knockout mice.

The angiopoietin-like protein (ANGPTL) family is homologous to angiopoietins but does not bind to the Tie2 receptor. The function of ANGPTLs has been elucidated largely in the context of angiogenesis and lipid metabolism. Morinaga et al. demonstrated that genetic depletion of Angptl2 confers amelioration of the mouse kidney fibrosis induced by a unilateral ureteral obstruction, implicating that ANGPTL2, predominantly in the renal tubular compartments, activates the transforming growth factor-ß signaling and vice versa through miR-221.

Endocytosis of soluble immune complexes leads to their clearance by FcγRIIIB but induces neutrophil extracellular traps via FcγRIIA in vivo.

Soluble immune complexes (ICs) are abundant in autoimmune diseases, yet neutrophil responses to these soluble humoral factors remain uncharacterized. Moreover, the individual role of the uniquely human FcγRIIA and glycophosphatidylinositol (GPI)-linked FcγRIIIB in IC-mediated inflammation is still debated. Here we exploited mice and cell lines expressing these human neutrophil FcγRs to demonstrate that FcγRIIIB alone, in the absence of its known signaling partners FcγRIIA and the integrin Mac-1, internalizes soluble ICs through a mechanism used by GPI-anchored receptors and fluid-phase endocytosis. FcγRIIA also uses this pathway. As shown by intravital microscopy, FcγRIIA but not FcγRIIIB-mediated neutrophil interactions with extravascular soluble ICs results in the formation of neutrophil extracellular traps (NETs) in tissues. Unexpectedly, in wild-type mice, IC-induced NETosis does not rely on the NADPH oxidase, myeloperoxidase, or neutrophil elastase. In the context of soluble ICs present primarily within vessels, FcγRIIIB-mediated neutrophil recruitment requires Mac-1 and is associated with the removal of intravascular IC deposits. Collectively, our studies assign a new role for FcγRIIIB in the removal of soluble ICs within the vasculature that may serve to maintain homeostasis, whereas FcγRIIA engagement of tissue soluble ICs generates NETs, a proinflammatory process linked to autoimmunity.

Human lupus serum induces neutrophil-mediated organ damage in mice that is enabled by Mac-1 deficiency.

Systemic lupus erythematosus (SLE) is a chronic, multiorgan inflammatory autoimmune disorder associated with high levels of circulating autoantibodies and immune complexes. We report that passive transfer of human SLE sera into mice expressing the uniquely human FcγRIIA and FcγRIIIB on neutrophils induces lupus nephritis and in some cases arthritis only when the mice additionally lack the CD18 integrin, Mac-1. The prevailing view is that Mac-1 on macrophages is responsible for immune complex clearance. However, disease permitted by the absence of Mac-1 is not related to enhanced renal immune complex deposition or in situ C1q/C3 complement activation and proceeds even in the absence of macrophages. Instead, disease is associated with increased FcγRIIA-induced neutrophil accumulation that is enabled by Mac-1 deficiency. Intravital microscopy in the cremasteric vasculature reveals that Mac-1 mitigates FcγRIIA-dependent neutrophil recruitment in response to deposited immune complexes. Our results provide direct evidence that human SLE immune complexes are pathogenic, demonstrate that neutrophils are primary mediators of end organ damage in a novel humanized lupus mouse model, and identify Mac-1 regulation of FcγRIIA-mediated neutrophil recruitment as a key step in development of target organ damage.