Complement regulatory proteins in glomerular diseases

Complement regulatory proteins in glomerular diseases. Complement activation plays a critical role in the pathogenesis of many forms of glomerulonephritis. Complement activation leads to tissue injury through various mechanisms including the generation of chemotactic factors and activation of the resident glomerular cells following C5b-9 insertion. Recent advances have disclosed the mechanisms of regulation of complement activation by discovery of a number of complement regulatory proteins. Decay accelerating factor (DAF), membrane cofactor protein (MCP), and complement receptor type 1 (CR1) act by inactivating C3/C5 convertase. They belong to the gene superfamily known as the regulators of complement activation (RCA), and share a common structural motif called a short consensus repeat (SCR). In contrast, CD59 works by inhibiting formation of C5b-9. The glomerulus is particularly well endowed with these membrane-bound complement regulatory proteins. DAF, MCP, and CD59 are ubiquitously expressed by all three resident glomerular cells, while CR1 is localized exclusively in podocytes. Expression of complement regulatory proteins can be changed by many factors including complement attack itself, and their expression levels are affected in various glomerular disorders. Studies utilizing cultured glomerular cells and animal models of glomerular diseases suggest important protective roles of complement regulatory proteins against immune-mediated renal injury. Recent progress in molecular biological techniques has made new therapeutic strategy feasible. Systemic administration of soluble recombinant complement regulatory proteins and local overexpression of complement regulatory proteins are promising therapeutic approaches

ジンゾウ ニオケル サンソ タイシャ イジョウ ト シンキ テイサンソ チリョウ ターゲット ノ タンサク

Chronic hypoxia in the tubulointerstitium serves as a final common pathway to end stage kidney disease in a variety of kidney diseases. Oxygen demand of the kidney is large, and the oxygen uptake efficiency of the kidney is relatively low due to arterio-venous oxygen shunt. Thus, the kidney can be hypoxic easily. In diseased kidneys, induction of hypoxia of the kidney is multifactorial. These factors include reduction of peritubular capillary blood flow due to activation of the renin-angiotensin system, increased oxygen consumption by tubular cells due to uremia, and renal anemia. Cells are endowed with the defensive mechanism against hypoxia, and hypoxia-inducible factor（HIF）serves as a master gene switch of various adaptive mechanisms, and activation of HIF induces a number of defensive responses in a coordinated manner. Many studies showed protective effects of HIF activation in experimental models of kidney disorders, and we are now performing detailed analysis of responses induced by HIF activation utilizing ChIP-Seq

Changes in Quality of Life in Older Hemodialysis Patients: A Cohort Study on Dialysis Outcomes and Practice Patterns

Background: Despite improvements in dialysis treatment, mortality rates remain high, especially among older hemodialysis patients. Quality of life (QOL) among hemodialysis patients is strongly associated with higher risk of death. This study aimed to describe the health-related QOL and its change in older maintenance hemodialysis patients and to demonstrate characteristics associated with health-related QOL. Methods: Data on 892 maintenance hemodialysis patients aged 60 years or older who were surveyed using the Kidney Disease Quality of Life Short Form at baseline and 2 years after study enrollment in phases 4 (2009–2011) and 5 (2012–2014) of the Japanese Dialysis Outcomes and Practice Patterns Study were analyzed. We categorized participants into 3 age groups (60–69, 70–79, and ≥80 years) and described baseline physical component summary (PCS) and mental component summary (MCS) scores, as well as their distribution of changes after 2 years across each category. Results: Hemodialysis patients aged 70–79 years and ≥80 years had lower PCS scores than those aged 60–69 years (median: 70–79 years = 43.1; interquartile range [IQR], 35.2–49.4; ≥80 years = 38.8; IQR, 31.6–43.8; 60–69 years = 45.4; IQR, 37.5–51.4; p < 0.001). In contrast, MCS scores did not significantly differ by age category (70–79 years = 45.6; IQR, 38.4–53.7; ≥80 years = 45.4; IQR, 36.9–55.1; 60–69 years = 46.8; IQR, 39.5–55.7; p = 0.1). As dialysis vintage lengthened, the PCS score significantly became lower, whereas no association was found with change in the MCS score. The MCS score declined over time in older patients, especially among those aged 80 years and older after 2 years’ follow-up. Conclusions: Physical QOL became worse as dialysis vintage lengthened. In contrast, mental QOL declined over time within a relatively short period among older maintenance hemodialysis patients

Reduction in the magnitude of serum potassium elevation in combination therapy with esaxerenone (CS‐3150) and sodium–glucose cotransporter 2 inhibitor in patients with diabetic kidney disease: Subanalysis of two phase III studies

Aims/Introduction: We evaluated the effect of co-administration of esaxerenone and a sodium–glucose cotransporter 2 (SGLT2) inhibitor on the magnitude of serum potassium elevation in Japanese patients with diabetic kidney disease. Materials and Methods: We carried out a prespecified subanalysis of data from two phase III studies: a multicenter, randomized, double-blind, placebo-controlled trial in patients with type 2 diabetes and microalbuminuria (J308); and a multicenter, single-arm, open-label trial in patients with type 2 diabetes and macroalbuminuria (J309). Changes in serum potassium levels during the studies and other measures were evaluated according to SGLT2 inhibitor use. Results: In both studies, time-course changes in serum potassium levels, and incidence rates of serum potassium elevation were lower in patients with co-administration of SGLT2 inhibitor in both the placebo and esaxerenone groups than those without the inhibitor. In contrast, time-course changes and mean percentage changes from baseline in urinary albumin-to-creatinine ratio, the proportion of patients with albuminuria remission and time-course changes in blood pressure did not change with or without SGLT2 inhibitor, whereas the albumin-to-creatinine ratio and blood pressure were reduced with esaxerenone. The blood glucose-lowering effect of SGLT2 inhibitor was not affected by esaxerenone. Conclusions: In Japanese patients with type 2 diabetes and albuminuria treated with esaxerenone, concomitant use of SGLT2 inhibitor reduced the magnitude of serum potassium elevation without any change of its antihypertensive and albuminuria-suppressing effects. Co-administration of esaxerenone and SGLT2 inhibitor might be a beneficial treatment option for patients with diabetic kidney disease

Body Weight Control by a High-Carbohydrate/Low-Fat Diet Slows the Progression of Diabetic Kidney Damage in an Obese, Hypertensive, Type 2 Diabetic Rat Model

Obesity is one of several factors implicated in the genesis of diabetic nephropathy (DN). Obese, hypertensive, type 2 diabetic rats SHR/NDmcr-cp were given, for 12 weeks, either a normal, middle-carbohydrate/middle-fat diet (MC/MF group) or a high-carbohydrate/low-fat diet (HC/LF group). Daily caloric intake was the same in both groups. Nevertheless, the HC/LF group gained less weight. Despite equivalent degrees of hypertension, hyperglycemia, hyperlipidemia, hyperinsulinemia, and even a poorer glycemic control, the HC/LF group had less severe renal histological abnormalities and a reduced intrarenal advanced glycation and oxidative stress. Mediators of the renoprotection, specifically linked to obesity and body weight control, include a reduced renal inflammation and TGF-beta expression, together with an enhanced level of adiponectin. Altogether, these data identify a specific role of body weight control by a high-carbohydrate/low-fat diet in the progression of DN. Body weight control thus impacts on local intrarenal advanced glycation and oxidative stress through inflammation and adiponectin levels

Ectopic expression of Klotho in fibroblast growth factor 23 (FGF23)-producing tumors that cause tumor-induced rickets/osteomalacia (TIO)

Tumor-induced rickets/osteomalacia (TIO) is a rare paraneoplastic syndrome caused by tumors that ectopically express fibroblast growth factor 23 (FGF23). FGF23 is a bone-derived hormone that regulates serum phosphate concentrations. Patients with TIO develop hypophosphatemic rickets/osteomalacia due to FGF23 excess and suffer from symptoms such as leg deformities, bone pain, skeletal muscle myopathy, and multiple fractures/ pseudofractures. Usually, successful surgical removal of the causative tumors normalizes serum FGF23 and phosphate concentrations in patients with TIO. Most FGF23-producing tumors associated with TIO are histologically called phosphaturic mesenchymal tumor, mixed connective tissue variant (PMTMCT). The precise mechanism by which these tumors ectopically overproduce FGF23 outside of bone is yet to be clarified. Therefore, we performed an RNA sequencing analysis of a PMTMCT that was found in the left parotid gland of a patient with TIO. Among the upregulated genes, we focused on Klotho, the protein product of which is a single pass transmembrane protein that works along with an FGF receptor 1c as a receptor complex for FGF23. Subsequent histological analysis confirmed the ectopic expression of Klotho in other PMTMCTs. From these results, we assume that the ectopic expression of Klotho in PTMMCTs enables a positive feedback loop in FGF23 production via the activation of FGF receptor 1c and exacerbates disease manifestations in TIO