Urinary neutrophil gelatinase-associated lipocalin (Ngal or lipocalin 2) is a very early and sensitive biomarker of kidney injury. Here we determined the origin and time course of Ngal appearance in several experimental and clinically relevant renal diseases. Urinary Ngal levels were found to be markedly increased in lipoatrophic- and streptozotocin-induced mouse models of diabetic nephropathy. In the latter mice, the angiotensin receptor blocker candesartan dramatically decreased urinary Ngal excretion. The reabsorption of Ngal by the proximal tubule was severely reduced in streptozotocin-induced diabetic mice, but upregulation of its mRNA and protein in the kidney was negligible, compared to those of control mice, suggesting that increased urinary Ngal was mainly due to impaired renal reabsorption. In the mouse model of unilateral ureteral obstruction, Ngal protein synthesis was dramatically increased in the dilated thick ascending limb of Henle and N was found in the urine present in the swollen pelvis of the ligated kidney. Five patients with nephrotic syndrome or interstitial nephritis had markedly elevated urinary Ngal levels at presentation, but these decreased in response to treatment. Our study shows that the urinary Ngal level may be useful for monitoring the status and treatment of diverse renal diseases reflecting defects in glomerular filtration barrier, proximal tubule reabsorption, and distal nephrons.

Recent epidemiological studies indicate that obesity increases the incidence of depression. We examined the implication of leptin for obesity-associated depression. Leptin induced antidepressive behavior in normal mice in a forced swimming test (FST), and leptin-overexpressing transgenic mice with hyperleptinemia exhibited more antidepressive behavior in the FST than nontransgenic mice. In contrast, leptin-deficient ob/ob mice showed more severe depressive behavior in the FST than normal mice, and leptin administration substantially ameliorated this depressive behavior. Diet-induced obese (DIO) mice fed a high-fat diet showed more depressive behavior in the FST and in a sucrose preference test compared with mice fed a control diet (CD). In DIO mice, leptin induced neither antidepressive action nor increment of the number of c-Fos immunoreactive cells in the hippocampus. Diet substitution from high-fat diet to CD in DIO mice ameliorated the depressive behavior and restored leptin-induced antidepressive action. Brain-derived neurotrophic factor concentrations in the hippocampus were significantly lower in DIO mice than in CD mice. Leptin administration significantly increased hippocampal brain-derived neurotrophic factor concentrations in CD mice but not in DIO mice. The antidepressant activity of leptin in CD mice was significantly attenuated by treatment with K252a. These findings demonstrated that leptin induces an antidepressive state, and DIO mice, which exhibit severe depressive behavior, did not respond to leptin in both the FST and the biochemical changes in the hippocampus. Thus, depression associated with obesity is due, at least in part, to impaired leptin activity in the hippocampus.

The present study demonstrates the efficacy and safety of the long-term leptin-replacement therapy and possible mechanisms of leptin actions in patients with generalized lipodystrophy.

Aims/hypothesisWe have previously demonstrated the therapeutic usefulness of leptin in lipoatrophic diabetes and insulin-deficient diabetes in mouse models and could also demonstrate its dramatic effects on lipoatrophic diabetes in humans. The aim of the present study was to explore the therapeutic usefulness of leptin in a mouse model of type 2 diabetes with increased adiposity. Methods To generate a mouse model mimicking human type 2 diabetes with increased adiposity, we used a combination of low-dose streptozotocin (STZ, 120 μg/g body weight) and high-fat diet (HFD, 45% of energy as fat). Recombinant mouse leptin was infused chronically (20 ng [g body weight] −1 h −1 ) for 14 days using a mini-osmotic pump. The effects of leptin on food intake, body weight, metabolic variables, tissue triacylglycerol content and AMP-activated protein kinase (AMPK) activity were examined. Results Low-dose STZ injection led to a substantial reduction of plasma insulin levels and hyperglycaemia. Subsequent HFD feeding increased adiposity and induced insulin resistance and further augmentation of hyperglycaemia. In this model mouse mimicking human type 2 diabetes (STZ/HFD), continuous leptin infusion reduced food intake and body weight and improved glucose and lipid metabolism with enhancement of insulin sensitivity. Leptin also decreased liver and skeletal muscle triacylglycerol content accompanied by an increase of α2 AMPK activity in skeletal muscle. Pairfeeding experiments demonstrated that leptin improved glucose and lipid metabolism independently of the food intake reduction. Conclusions/interpretation This study demonstrates the beneficial effects of leptin on glycaemic and lipid control in a mouse model of type 2 diabetes with increased adiposity, indicating the possible clinical usefulness of leptin as a new glucose-lowering drug in humans.

We assessed whether gut microbial functional profiles predicted from 16S rRNA metagenomics differed in Japanese type 2 diabetic patients. A total of 22 Japanese subjects were recruited from our outpatient clinic in an observational study. Fecal samples were obtained from 12 control and 10 type 2 diabetic subjects. 16S rRNA metagenomic data were generated and functional profiles predicted using “Phylogenetic Investigation of Communities by Reconstruction of Unobserved States” software. We measured the parameters of glucose metabolism, gut bacterial taxonomy and functional profile, and examined the associations in a cross-sectional manner. Eleven of 288 “Kyoto Encyclopedia of Genes and Genomes” pathways were significantly enriched in diabetic patients compared with control subjects (p<0.05, q<0.1). The relative abundance of almost all pathways, including the Insulin signaling pathway and Glycolysis/Gluconeogenesis, showed strong, positive correlations with hemoglobin A1c (HbA1c) and fasting plasma glucose (FPG) levels. Bacterial taxonomic analysis showed that genus Blautia significantly differed between groups and had negative correlations with HbA1c and FPG levels. Our findings suggest a novel pathophysiological relationship between gut microbial communities and diabetes, further highlighting the significance and utility of combining prediction of functional profiles with ordinal bacterial taxonomic analysis (UMIN Clinical Trails Registry number: UMIN000026592).

ObjectiveTo investigate the association between serum soluble triggering receptor expressed on myeloid cells 2 (sTREM2), a soluble type of an innate immune receptor expressed on the microglia, and the risk of dementia.MethodsA total of 1,349 Japanese community residents aged 60 and older without dementia were followed prospectively for 10 years (2002–2012). Serum sTREM2 levels were quantified by using an enzyme‐linked immunosorbent assay and divided into quartiles. Cox proportional hazards model was used to estimate the hazard ratios (HRs) of serum sTREM2 levels on the risk of dementia.ResultsDuring the follow‐up, 300 subjects developed all‐cause dementia; 193 had Alzheimer's disease (AD), and 85 had vascular dementia (VaD). The age‐ and sex‐adjusted incidences of all‐cause dementia, AD, and VaD elevated significantly with higher serum sTREM2 levels (all p for trend < 0.012). These associations were not altered after adjustment for confounding factors, including high‐sensitive C‐reactive protein. Subjects with the highest quartile of serum sTREM2 levels had significantly higher multivariable‐adjusted risks of developing all‐cause dementia, AD, and VaD than those with the lowest quartile (HR = 2.03, 95% confidence interval [CI] = 1.39–2.97, p < 0.001 for all‐cause dementia; HR = 1.62, 95% CI = 1.02–2.55, p = 0.04 for AD; HR = 2.85, 95% CI = 1.35–6.02, p = 0.006 for VaD). No significant heterogeneity in the association of serum sTREM2 levels with the development of dementia was observed among the other risk factor subgroups (all p for heterogeneity > 0.11).InterpretationThe present findings suggest a significant association between increased serum sTREM2 levels and the risk of developing all‐cause dementia, AD, and VaD in the general elderly Japanese population. ANN NEUROL 2019;85:47–58.

No abstract

Objective: To elucidate early change of intra-abdominal fat in response to calorie restriction in patients with obesity by weekly evaluation using a dual bioelectrical impedance analysis (Dual BIA) instrument. Design and Methods: For 67 Japanese patients with obesity, diabetes, or metabolic syndrome, intraabdominal fat area (IAFA), initially with both Dual BIA and computed tomography (CT), and in subsequent weeks of calorie restriction, with Dual BIA were measured. Results: IAFA by Dual BIA (Dual BIA-IAFA) correlated well with IAFA by CT (CT-IAFA) in obese patients (r ¼ 0.821, P < .0001, n ¼ 67). Ten males and 9 females (age 49.0 6 14.4 years, BMI 33.2 6 7.3 kg/m 2 ) lost more than 5% of baseline body weight (BW) in 3 weeks, and their Dual BIA-IAFA, BW, and WC decreased by 18.9%, 5.3%, and 3.8%, respectively (P < .05, ANCOVA). Conclusion: Dual BIA instrument could detect the weekly change of Dual BIA-IAFA under calorie restriction in obese patients and demonstrated a substantially larger change of IAFA compared with changes of BW and WC in early weeks. This observation corroborates the significance of evaluating IAFA as a biomarker for obesity, and indicates the clinical usefulness of the Dual BIA instrument.