Ayumi Yoshifuji

Gut Lactobacillus protects against the progression of renal damage by modulating the gut environment in rats

BACKGROUND The role of gut microbiota in the progression of chronic kidney disease (CKD) has not been fully elucidated. METHODS Renal failure was induced in 6-week-old spontaneously hypertensive rats by 5/6 nephrectomy (Nx). We analyzed the gut microbiota population to identify the relevant species potentially involved in inducing renal damage. Human colon Caco-2 cells were used to delineate the mechanism involved in the molecular changes in the gut of Nx rats. RESULTS Nx rats showed an increase in Bacteroides (Bact) and a decrease in Lactobacillus (Lact) species compared with sham-operated rats. Lact, but not Bact, populations were significantly associated with urinary protein excretion. Treatment of Nx rats with 1 × 10(10) CFU/kg/day Lact ameliorated increased urinary protein excretion and higher serum levels of the uremic toxins, indoxyl sulfate and p-cresyl sulfate, and serum urea nitrogen levels. Lact also attenuated systemic inflammation in Nx rats, as evaluated by serum lipopolysaccharide, interleukin-6 and C-reactive protein levels. Histologically, renal sclerosis in Nx rats was restored by Lact treatment. A reduction in the expression of tight junction proteins and the Toll-like receptor 2 (TLR2), a putative Lact receptor, in the colons of Nx rats were mitigated by Lact. Treatment of Caco-2 cells with indole downregulated tight junction protein expression, which was abolished by exposure to Lact. The effects of Lact were reversed by treatment with OxPAPC, a TLR inhibitor. Similarly, the increase in the permeability of the Caco-2 cell monolayer was reversed by the administration of Lact. Lact upregulated TLR2 expression in Caco-2 cells. Lact also attenuated the increase in serum indoxyl sulfate and urea levels and urinary protein excretion in Nx rats even in the pseudogerm-free environment. CONCLUSIONS Lact supplementation mitigated the systemic inflammation and proteinuria associated with renal failure, suggesting that in the gut microbiota, Lact plays a protective role against the progression of CKD.

Insulin resistance in chronic kidney disease is ameliorated by spironolactone in rats and humans

In this study, we examined the association between chronic kidney disease (CKD) and insulin resistance. In a patient cohort with nondiabetic stages 2-5 CKD, estimated glomerular filtration rate (eGFR) was negatively correlated and the plasma aldosterone concentration was independently associated with the homeostasis model assessment of insulin resistance. Treatment with the mineralocorticoid receptor blocker spironolactone ameliorated insulin resistance in patients, and impaired glucose tolerance was partially reversed in fifth/sixth nephrectomized rats. In these rats, insulin-induced signal transduction was attenuated, especially in the adipose tissue. In the adipose tissue of nephrectomized rats, nuclear mineralocorticoid receptor expression, expression of the mineralocorticoid receptor target molecule SGK-1, tissue aldosterone content, and expression of the aldosterone-producing enzyme CYP11B2 increased. Mineralocorticoid receptor activation in the adipose tissue was reversed by spironolactone. In the adipose tissue of nephrectomized rats, asymmetric dimethylarginine (ADMA; an uremic substance linking uremia and insulin resistance) increased, the expression of the ADMA-degrading enzymes DDAH1 and DDAH2 decreased, and the oxidative stress increased. All of these changes were reversed by spironolactone. In mature adipocytes, aldosterone downregulated both DDAH1 and DDAH2 expression, and ADMA inhibited the insulin-induced cellular signaling. Thus, activation of mineralocorticoid receptor and resultant ADMA accumulation in adipose tissue has, in part, a relevant role in the development of insulin resistance in CKD.

The role of adipose tissue asymmetric dimethylarginine/dimethylarginine dimethylaminohydrolase pathway in adipose tissue phenotype and metabolic abnormalities in subtotally nephrectomized rats

BACKGROUND The lipodystrophy-like phenotype has been suggested in early chronic kidney disease (CKD). It includes adipose tissue atrophy, systemic insulin resistance (IR), dyslipidemia and ectopic lipid accumulation. To elucidate its pathogenesis, we investigated the role of two uremic toxins that affect insulin sensitivity: an endogenous nitric oxide synthase inhibitor, and asymmetric dimethylarginine (ADMA) and indoxyl sulfate (IS). METHODS Six-week-old Sprague-Dawley rats were rendered CKD by subtotal nephrectomy (Nx) and compared with sham-operated rats. Cultured 3T3-L1 fibroblasts were differentiated into mature adipocytes with or without ADMA. Transgenic (Tg) mice overexpressing each isoform of ADMA degrading enzyme, dimethylarginine dimethylaminohydrolase 1 (DDAH1) and DDAH2 were subject to Nx and their phenotypes were investigated. RESULTS In Nx rats, IR was evident and insulin stimulation failed to activate insulin signaling in adipose tissues. Adipose tissue weight, adipocyte size and adipocyte differentiation marker expressions decreased as a consequence of IR in Nx. Tissue lipid content in the liver and muscle increased in Nx rats. Tissue levels of ADMA, IS and oxidative stress increased in the adipose tissue of Nx rats. Both DDAH1 and DDAH2 expressions decreased, and a putative IS receptor, aryl hydrocarbon receptor, expression increased in the adipose tissue of Nx rats. ADMA inhibited adipocyte differentiation, triglyceride accumulation and insulin signaling, which were reversed by pretreatment with cGMP. In each type of Tg mice overexpressing DDAH1 or DDAH2, all lipodystrophy-like phenotypes induced by Nx were reversed. CONCLUSIONS In mild CKD, dysregulation of the ADMA/DDAH pathway in adipose tissue triggers lipodystrophy-like phenotype changes, including ectopic fat depositions.

PS 11-09 EVALUATION OF DAY-BY-DAY BLOOD PRESSURE VARIABILITY IN CLINIC

Objective: To evaluate the usefulness of maximum-minimum difference (MMD) of BP in a month compared to standard deviation (SD), as an index of BP variability. Design and Method: Study-1: Twelve patients (age 65.9 ± 12.1 y/o) were enrolled. Measurements of home systolic (S) BP were required in the morning. The 12 months consecutive data and at least 3 times measurements a month were required for including. (Mean 29.0 ± 4.5 times/month in the morning). We checked the correlation between MMD and SD. Study-2: Six hemodialized patients monitored with i-TECHO system (J of Hypertens 2007: 25: 2353–2358) for longer than one year were analyzed. As in study-1, we analyzed the correlation between SD and MMD of SBP. Measurements: 17.4 ± 11.9 times per month. Study-3: The data from our previous study (FUJIYAM study Clin. Exp Hypertens 2014: 36:508–16) were extracted. 1524 patient-month morning BP data were calculated as in study-1. Picking up data measuring more than 24 times a month, 517 patient-month BP data were analyzed. We compared the ratio to 25 times measured data of SD and MMD, in the setting 5, 10, 15, 20 times measured data. Results: Study-1: In SBP, DBP, pulse, MMD were correlated very well to SD (p < 0.0001, R = 0.923 in SBP). Equation of SBPSD = 1.275 + 0.208xMMD. Study-2: R = 0.884 (P < 0.0001) SBPSD = 2.17 + 0.22xMMD. Study-3: If data were extracted (measurements >24 times), correlation was 0.927 (P < 0.0001). The equation of SBPSD = 1.520 + 0.201xMMD. As in study 1, the correlations between MMD and SD were very strong either in SBP, BP, pulse. The ratios of SD to 25 times were as follows; 0.956 in 5 times, 0.956 in 10, 0.979 in 15, 0.991 in 20 times. The ratios of MMD to 25 times were as follows; 0.558 in 5, 0.761 in 10, 0.874 in 15, 0.944 in 20. Conclusions: SD is easily assumed by MMD as an index of day-by-day BP variability of a month.