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Aim: Sodium‐glucose cotransporter 2 (SGLT2) inhibitors often cause a transient decrease in glomerular filtration rate (GFR) shortly after the initiation, referred to as the 'initial drop'. However, the clinical significance of this initial drop in real‐world practice remains unclear. Materials and Methods: Using the nationwide Japan Chronic Kidney Disease Database, we examined factors that affected the initial drop, in patients with chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM). We also evaluated the effects of the initial drop on a composite kidney outcome (a decline in GFR of ≥50% or progression to end‐stage kidney disease). Results: Data from 2053 patients with CKD and T2DM newly prescribed an SGLT2 inhibitor were analysed. The follow‐up period after SGLT2 inhibitor administration was 1015 days (interquartile range: 532, 1678). Multivariate linear regression models revealed that the concomitant use of the renin‐angiotensin system inhibitors and diuretics, urinary protein levels ≥2+, and changes in GFR before the initiation of the SGLT2 inhibitor were associated with a larger initial GFR decline (β = −0.609, p =.039; β = −2.298, p <.001; β = −0.936, p =.048; β = −0.079, p <.001, respectively). Patients in the quartile with the largest initial GFR decline experienced a higher incidence of the subsequent composite kidney outcome than those in the other quartiles (p <.001). Conclusions: The concomitant use of renin‐angiotensin system inhibitors and diuretics, higher urine protein levels and pre‐treatment GFR changes were associated with a larger initial GFR decline. Of these factors, the use of a diuretic had the largest effect. Furthermore, patients with CKD and T2DM experiencing an excessive initial GFR drop might be at a higher risk of adverse kidney outcomes. [ABSTRACT FROM AUTHOR]

Tertiary lymphoid tissues (TLTs) are inducible ectopic lymphoid tissues that develop at sites of chronic inflammation in nonlymphoid organs. As with lymph nodes, TLTs initiate adaptive immune responses and coordinate local tissue immunity. Although virtually ignored for decades, TLTs have recently received a great deal of attention for their ability to influence disease severity, prognosis and response to therapy in various diseases, including cancer, autoimmune disorders and infections. TLTs are also induced in kidneys of patients with chronic kidney diseases such as immunoglobulin A nephropathy and lupus nephritis. Nevertheless, TLTs in the kidney have not been extensively investigated and their mechanism of development, functions and clinical relevance remain unknown, mainly because of the absence of adequate murine kidney TLT models and limited availability of human kidney samples containing TLTs. We recently found that aged kidneys, but not young kidneys, exhibit multiple TLTs after injury. Interestingly, although they are a minor component of TLTs, resident fibroblasts in the kidneys diversify into several distinct phenotypes that play crucial roles in TLT formation. Furthermore, the potential of TLTs as a novel kidney injury/inflammation marker as well as a novel therapeutic target for kidney diseases is also suggested. In this review article we describe the current understanding of TLTs with a focus on age-dependent TLTs in the kidney and discuss their potential as a novel therapeutic target and kidney inflammation marker. [ABSTRACT FROM AUTHOR]

Metabolic syndrome is associated with the development of chronic kidney disease (CKD). We previously demonstrated that aged kidneys are prone to developing tertiary lymphoid tissues (TLTs) and sustain inflammation after injury, leading to CKD progression; however, the relationship between renal TLT and metabolic syndrome is unknown. In this study, we demonstrated that a high-fat diet (HFD) promoted renal TLT formation and inflammation via sterol O-acyltransferase (SOAT) 1-dependent mechanism. Mice fed a HFD prior to ischemic reperfusion injury (IRI) exhibited pronounced renal TLT formation and sustained inflammation compared to the controls. Untargeted lipidomics revealed the increased levels of cholesteryl esters (CEs) in aged kidneys with TLT formation after IRI, and, consistently, the Soat1 gene expression increased. Treatment with avasimibe, a SOAT inhibitor, attenuated TLT maturation and renal inflammation in HFD-fed mice subjected to IRI. Our findings suggest the importance of SOAT1-dependent CE accumulation in the pathophysiology of CKDs associated with TLT. [ABSTRACT FROM AUTHOR]

Background The relationship between chronic kidney disease (CKD) and the gut microbiome, which interact through chronic inflammation, uraemic toxin production and immune response regulation, has gained interest in the development of CKD therapies. However, reports using shotgun metagenomic analysis of the gut microbiome are scarce, especially for early CKD. Here we characterized gut microbiome differences between non-CKD participants and ones with early CKD using metagenomic sequencing. Methods In total, 74 non-CKD participants and 37 participants with early CKD were included based on propensity score matching, controlling for various factors including dietary intake. Stool samples were collected from participants and subjected to shotgun sequencing. Bacterial and pathway abundances were profiled at the species level with MetaPhlAn2 and HUMAnN2, respectively, and overall microbiome differences were determined using Bray–Curtis dissimilarities. Diabetic and non-diabetic populations were analysed separately. Results For diabetic and non-diabetic participants, the mean estimated glomerular filtration rates of the CKD group were 53.71 [standard deviation (SD) 3.87] and 53.72 (SD 4.44), whereas those of the non-CKD group were 72.63 (SD 7.72) and 76.10 (SD 9.84), respectively. Alpha and beta diversities were not significantly different between groups. Based on taxonomic analysis, butyrate-producing species Roseburia inulinivorans , Ruminococcus torques and Ruminococcus lactaris were more abundant in the non-CKD group, whereas Bacteroides caccae and Bacteroides coprocora were more abundant in the non-diabetic CKD group. Conclusions Although gut microbiome changes in individuals with early CKD were subtle, the results suggest that changes related to producing short-chain fatty acids can already be observed in early CKD. [ABSTRACT FROM AUTHOR]

Fibroblasts reside in various organs and support tissue structure and homeostasis under physiological conditions. Phenotypic alterations of fibroblasts underlie the development of diverse pathological conditions, including organ fibrosis. Recent advances in single‐cell biology have revealed that fibroblasts comprise heterogeneous subpopulations with distinct phenotypes, which exert both beneficial and detrimental effects on the host organs in a context‐dependent manner. In the kidney, phenotypic alterations of resident fibroblasts provoke common pathological conditions of chronic kidney disease (CKD), such as renal anemia and peritubular capillary loss. Additionally, in aged injured kidneys, fibroblasts provide functional and structural supports for tertiary lymphoid tissues (TLTs), which serve as the ectopic site of acquired immune reactions in various clinical contexts. TLTs are closely associated with aging and CKD progression, and the developmental stages of TLTs reflect the severity of renal injury. In this review, we describe the current understanding of fibroblast heterogeneity both under physiological and pathological conditions, with special emphasis on fibroblast contribution to TLT formation in the kidney. Dissecting the heterogeneous characteristics of fibroblasts will provide a promising therapeutic option for fibroblast‐related pathological conditions, including TLT formation. [ABSTRACT FROM AUTHOR]

Background: Although cancer management in dialysis patients has become a commonly encountered issue, known as “onco-nephrology”, few evidence-based clinical recommendations have been proposed. Here, we examined the variation in referral behaviors adopted by dialysis physicians on encountering dialysis patients with signs/symptoms suggestive of cancer. Methods: We conducted a vignette-based study in August 2015. We sent a 14-page questionnaire to 191 dialysis physicians, including the representative dialysis facilities participating in a Japanese dialysis cohort (the Japan Dialysis Outcomes and Practice Patterns Study). Using vignette scenarios for respiratory, digestive, and urological areas, we assessed the referral behaviors (expert referral or not) adopted by dialysis physicians on encountering dialysis patients with symptoms suggestive of cancer. Each scenario contained three patient functional factors: age (60 or 75 years), performance status (PS 0 or 1), and cognitive dysfunction (absence or presence). We examined the association between physician factors, patient factors, and referral behaviors. Results: We obtained 94 replies (response rate: 49.2%). For the respiratory scenarios, 38.3% and 51.9% of physicians reported watchful waiting when encountering bilateral and unilateral pleural effusion, respectively. In digestive and urologic scenarios, most physicians (>85%) selected expert referral. We detected differences in referral behaviors between scenarios with different cancer biological factors. However, we found consistency in referral behaviors within the same scenario, even with different patient functional factors (intra-class correlation coefficients within each scenario all >0.7). Conclusions: Physicians’ referral behaviors for dialysis patients suspected of having cancer vary for different cancer biological factors (probability of having cancer). However, the referral behaviors are similar for different patient functional factors (age, PS, and cognitive dysfunction). [ABSTRACT FROM AUTHOR]

Background: The prevalence of chronic kidney disease (CKD) increases with age as with idiopathic pulmonary fibrosis (IPF). Objectives: We assessed the prevalence of CKD (stages 3-5) and investigated the relationship of CKD to clinical features and outcomes in patients with IPF. Methods: This study comprised 123 patients with IPF; 61 subjects with chronic obstructive pulmonary disease (COPD), which was reportedly associated with CKD, were also enrolled as a disease control. CKD (stages 3-5) was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m². Results: Thirty-seven patients (30%) with IPF and 14 controls (23%) with COPD were diagnosed with CKD, and these frequencies were not significantly different. The patients with IPF and CKD were older (p < 0.01) and had a higher frequency of hypertension (p = 0.048) and ischemic heart disease (p = 0.02) than those with IPF but without CKD. Furthermore, the diffusing capacity of the lung for carbon monoxide (DLCO) and the 6-min walking distance in the patients with CKD were significantly lower (40.0 ± 13.2 vs. 45.9 ± 14.4%, p = 0.04, and 416 ± 129 vs. 474 ± 84 m, p = 0.01, respectively) than in the patients without CKD. The outcome of the patients with CKD showed significantly worse survival compared with the patients without CKD (p = 0.04). Moreover, eGFR remained an independent predictor of survival after adjusting for age and pulmonary function data. Conclusion: A substantial percentage of IPF patients have CKD. CKD with a low eGFR was associated with decreased survival in IPF. [ABSTRACT FROM AUTHOR]

Epidemiological findings indicate that acute kidney injury (AKI) increases the risk for chronic kidney disease (CKD), although the molecular mechanism remains unclear. Genetic fate mapping demonstrated that nephrons, functional units in the kidney, are repaired by surviving nephrons after AKI. However, the cell population that repairs damaged nephrons and their repair capacity limitations remain controversial. To answer these questions, we generated a new transgenic mouse strain in which mature proximal tubules, the segment predominantly damaged during AKI, could be genetically labelled at desired time points. Using this strain, massive proliferation of mature proximal tubules is observed during repair, with no dilution of the genetic label after the repair process, demonstrating that proximal tubules are repaired mainly by their own proliferation. Furthermore, acute tubular injury caused significant shortening of proximal tubules associated with interstitial fibrosis, suggesting that proximal tubules have a limited capacity to repair. Understanding the mechanism of this limitation might clarify the mechanism of the AKI-to-CKD continuum. [ABSTRACT FROM AUTHOR]

Podocyte injury is the first step in the progression of glomerulosclerosis. Previous studies have demonstrated the beneficial effect of bone morphogenetic protein 7 (Bmp7) in podocyte injury and the existence of native Bmp signaling in podocytes. Local activity of Bmp7 is controlled by cell-type specific Bmp antagonists, which inhibit the binding of Bmp7 to its receptors. Here we show that the product of Twisted gastrulation (Twsg1), a Bmp antagonist, is the central negative regulator of Bmp function in podocytes and that Twsg1 null mice are resistant to podocyte injury. Twsg1 was the most abundant Bmp antagonist in murine cultured podocytes. The administration of Bmp induced podocyte differentiation through Smad signaling, whereas the simultaneous administration of Twsg1 antagonized the effect. The administration of Bmp also inhibited podocyte proliferation, whereas simultaneous administration of Twsg1 antagonized the effect. Twsg1 was expressed in the glomerular parietal cells (PECs) and distal nephron of the healthy kidney, and additionally in damaged glomerular cells in a murine model of podocyte injury. Twsg1 null mice exhibited milder hypoalbuminemia and hyperlipidemia, and milder histological changes while maintaining the expression of podocyte markers during podocyte injury model. Taken together, our results show that Twsg1 plays a critical role in the modulation of protective action of Bmp7 on podocytes, and that inhibition of Twsg1 is a promising means of development of novel treatment for podocyte injury. [ABSTRACT FROM AUTHOR]

Lipoprotein lipase (LPL) is an enzyme that catalyzes the hydrolysis of circulating triglyceride and the transport of fatty acids into cells. Its activity is positively regulated by insulin, and insulin resistance is associated with low LPL activity and subsequent hypertriglyceridemia. The involvement of hypertriglyceridemia in chronic kidney disease (CKD) is still under the debate in a clinical setting. Therefore, we aimed to study the role of hypertriglyceridemia in the disease using mice with systemic or renal-specific LPL deficiency. Systemic LPL deficiency was characterized by hypertriglyceridemia, but not renal injury or dyslipidemia-related conditions, such as fatty liver. Furthermore, the LPL deficiency-induced hypertriglyceridemia was not associated with a worsening of the CKD phenotype or atherosclerosis, even when CKD was induced by 5/6 nephrectomy. Next, because LPL-mediated fatty acid uptake may be important for energy metabolism in proximal tubular epithelial cells (PTECs), the role of renal LPL in renal physiology was studied by generating mice lacking LPL specifically in PTECs. These mice showed no abnormalities in their histology or renal reabsorption of micro molecules. These findings suggest that systemic and renal lipid abnormalities caused by LPL deficiency do not cause or worsen the development of renal injury, and provide novel insight regarding the potential role of lipotoxicity in the pathogenesis of obesity-related kidney injury. • Adult mice with systemic lipoprotein lipase (LPL) deficiency were generated. • Systemic LPL deficiency causes severe hypertriglyceridemia. • Systemic LPL deficiency neither causes nor worsens kidney injury. • LPL deficiency-induced dyslipidemia is not related to atherosclerosis development. • Renal LPL is not necessary for normal renal physiology. [ABSTRACT FROM AUTHOR]

Abstract: Background: Little is known about the prognostic implications of anemia in patients undergoing elective percutaneous coronary intervention (PCI), especially when they have coexisting chronic kidney disease (CKD). Methods: We identified 7299 patients who underwent elective PCI from the CREDO-Kyoto registry cohort-2. The primary outcome was 3-year major adverse cardiac events (MACE); composite of all cause death, heart failure hospitalization, and myocardial infarction. Results: In total, 1466 patients (20.0%) had mild anemia (hemoglobin=11.0–11.9g/dL for women and 11.0–12.9g/dL for men), and 740 patients (10.1%) had moderate-to-severe anemia (hemoglobin<11.0g/dL both for women and for men). Compared to the no-anemia group, cumulative incidence of MACE was significantly higher in the mild and moderate-to-severe anemia groups (7.9%, 20.1%, and 34.2%, respectively). The adjusted hazard ratios of mild and moderate-to-severe anemia versus no-anemia for MACE were 1.77 (95% confidence interval: 1.47–2.15) and 2.53 (95% confidence interval: 2.03–3.14), respectively. In a subgroup analysis, significantly higher risk for MACE was consistently observed with mild and moderate-to-severe anemia both in patients with and without CKD. The risk for MACE showed an accretive increment with exacerbation in either the renal function or anemia (interaction p<0.001). Conclusions: Even mild anemia was associated with significantly worse 3-year clinical outcomes in patients who underwent elective PCI. Coexisting CKD additively increased the risk for MACE in these patients. [Copyright &y& Elsevier]