FXR/TGR5 Dual Agonist Prevents Progression of Nephropathy in Diabetes and Obesity.

Bile acids are ligands for the nuclear hormone receptor farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5. We have shown that FXR and TGR5 have renoprotective roles in diabetes- and obesity-related kidney disease. Here, we determined whether these effects are mediated through differential or synergistic signaling pathways. We administered the FXR/TGR5 dual agonist INT-767 to DBA/2J mice with streptozotocin-induced diabetes, db/db mice with type 2 diabetes, and C57BL/6J mice with high-fat diet-induced obesity. We also examined the individual effects of the selective FXR agonist obeticholic acid (OCA) and the TGR5 agonist INT-777 in diabetic mice. The FXR agonist OCA and the TGR5 agonist INT-777 modulated distinct renal signaling pathways involved in the pathogenesis and treatment of diabetic nephropathy. Treatment of diabetic DBA/2J and db/db mice with the dual FXR/TGR5 agonist INT-767 improved proteinuria and prevented podocyte injury, mesangial expansion, and tubulointerstitial fibrosis. INT-767 exerted coordinated effects on multiple pathways, including stimulation of a signaling cascade involving AMP-activated protein kinase, sirtuin 1, PGC-1α, sirtuin 3, estrogen-related receptor-α, and Nrf-1; inhibition of endoplasmic reticulum stress; and inhibition of enhanced renal fatty acid and cholesterol metabolism. Additionally, in mice with diet-induced obesity, INT-767 prevented mitochondrial dysfunction and oxidative stress determined by fluorescence lifetime imaging of NADH and kidney fibrosis determined by second harmonic imaging microscopy. These results identify the renal signaling pathways regulated by FXR and TGR5, which may be promising targets for the treatment of nephropathy in diabetes and obesity.

SGLT2 Protein Expression Is Increased in Human Diabetic Nephropathy: SGLT2 PROTEIN INHIBITION DECREASES RENAL LIPID ACCUMULATION, INFLAMMATION, AND THE DEVELOPMENT OF NEPHROPATHY IN DIABETIC MICE.

There is very limited human renal sodium gradient-dependent glucose transporter protein (SGLT2) mRNA and protein expression data reported in the literature. The first aim of this study was to determine SGLT2 mRNA and protein levels in human and animal models of diabetic nephropathy. We have found that the expression of SGLT2 mRNA and protein is increased in renal biopsies from human subjects with diabetic nephropathy. This is in contrast to db-db mice that had no changes in renal SGLT2 protein expression. Furthermore, the effect of SGLT2 inhibition on renal lipid content and inflammation is not known. The second aim of this study was to determine the potential mechanisms of beneficial effects of SGLT2 inhibition in the progression of diabetic renal disease. We treated db/db mice with a selective SGLT2 inhibitor JNJ 39933673. We found that SGLT2 inhibition caused marked decreases in systolic blood pressure, kidney weight/body weight ratio, urinary albumin, and urinary thiobarbituric acid-reacting substances. SGLT2 inhibition prevented renal lipid accumulation via inhibition of carbohydrate-responsive element-binding protein-ß, pyruvate kinase L, SCD-1, and DGAT1, key transcriptional factors and enzymes that mediate fatty acid and triglyceride synthesis. SGLT2 inhibition also prevented inflammation via inhibition of CD68 macrophage accumulation and expression of p65, TLR4, MCP-1, and osteopontin. These effects were associated with reduced mesangial expansion, accumulation of the extracellular matrix proteins fibronectin and type IV collagen, and loss of podocyte markers WT1 and synaptopodin, as determined by immunofluorescence microscopy. In summary, our study showed that SGLT2 inhibition modulates renal lipid metabolism and inflammation and prevents the development of nephropathy in db/db mice.

G Protein-Coupled Bile Acid Receptor TGR5 Activation Inhibits Kidney Disease in Obesity and Diabetes.

Obesity and diabetes mellitus are the leading causes of renal disease. In this study, we determined the regulation and role of the G protein-coupled bile acid receptor TGR5, previously shown to be regulated by high glucose and/or fatty acids, in obesity-related glomerulopathy (ORG) and diabetic nephropathy (DN). Treatment of diabetic db/db mice with the selective TGR5 agonist INT-777 decreased proteinuria, podocyte injury, mesangial expansion, fibrosis, and CD68 macrophage infiltration in the kidney. INT-777 also induced renal expression of master regulators of mitochondrial biogenesis, inhibitors of oxidative stress, and inducers of fatty acid ß-oxidation, including sirtuin 1 (SIRT1), sirtuin 3 (SIRT3), and Nrf-1. Increased activity of SIRT3 was evidenced by normalization of the increased acetylation of mitochondrial superoxide dismutase 2 (SOD2) and isocitrate dehydrogenase 2 (IDH2) observed in untreated db/db mice. Accordingly, INT-777 decreased mitochondrial H2O2 generation and increased the activity of SOD2, which associated with decreased urinary levels of H2O2 and thiobarbituric acid reactive substances. Furthermore, INT-777 decreased renal lipid accumulation. INT-777 also prevented kidney disease in mice with diet-induced obesity. In human podocytes cultured with high glucose, INT-777 induced mitochondrial biogenesis, decreased oxidative stress, and increased fatty acid ß-oxidation. Compared with normal kidney biopsy specimens, kidney specimens from patients with established ORG or DN expressed significantly less TGR5 mRNA, and levels inversely correlated with disease progression. Our results indicate that TGR5 activation induces mitochondrial biogenesis and prevents renal oxidative stress and lipid accumulation, establishing a role for TGR5 in inhibiting kidney disease in obesity and diabetes.

Minimal change disease in graft versus host disease: a podocyte response to the graft?

Nephrotic syndrome is a rare complication of hematopoietic cell transplantation. It has been suggested that nephrotic syndrome may represent a limited form of graft-versus-host disease although the pathological link between these two entities remains unclear. In this paper, we report a case of a 61-year-old female who underwent nonmyeloablative allogenic stem cell transplantation for T-cell prolymphocytic leukemia and subsequently developed biopsy proven minimal change disease shortly after cessation of her immunosuppression therapy. Urinary CD80 was markedly elevated during active disease and disappeared following corticosteroid-induced remission. We hypothesize that alloreactive donor T cells target the kidney and induce podocyte expression of CD80 that results in proteinuria from limited 'graft versus host' disease.

Metastatic renal cell carcinoma to the prostate and seminal vesicle.

Renal cell carcinoma (RCC) a common malignancy with potential to metastasize to visceral organs. However, it uncommonly spreads to the lower genitourinary tract. We present a man with a history of RCC status post radical nephrectomy in April 2012. He presented 8 years later with obstructive lower urinary tract symptoms and an elevated prostate specific antigen (PSA). Further imaging showed a large enhancing mass with internal blood vessels posterior to the left prostate and seminal vesicle. A prostate biopsy was performed and consistent with metastatic RCC. He was ultimately treated with immunotherapy and focal stereotactic radioablation.

Tamoxifen induces pleiotrophic changes in mammary stroma resulting in extracellular matrix that suppresses transformed phenotypes.

INTRODUCTION: The functional unit of the mammary gland has been defined as the epithelial cell plus its microenvironment, a hypothesis that predicts changes in epithelial cell function will be accompanied by concurrent changes in mammary stroma. To test this hypothesis, the question was addressed of whether mammary stroma is functionally altered by the anti-oestrogen drug tamoxifen. METHODS: Forty female rats at 70 days of age were randomised to two groups of 20 and treated with 1.0 mg/kg tamoxifen or vehicle subcutaneously daily for 30 days, followed by a three-day wash out period. Mammary tissue was harvested and effects of tamoxifen on mammary epithelium and stroma determined. RESULTS: As expected, tamoxifen suppressed mammary alveolar development and mammary epithelial cell proliferation. Primary mammary fibroblasts isolated from tamoxifen-treated rats displayed a three-fold decrease in motility and incorporated less fibronectin in their substratum in comparison to control fibroblasts; attributes indicative of fibroblast quiescence. Immunohistochemistry analysis of CD68, a macrophage lysosomal marker, demonstrated a reduction in macrophage infiltration in mammary glands of tamoxifen-treated rats. Proteomic analyses by mass spectrometry identified several extracellular matrix (ECM) proteins with expression levels with tamoxifen treatment that were validated by Western blot. Mammary tissue from tamoxifen-treated rats had decreased fibronectin and increased collagen 1 levels. Further, ECM proteolysis was reduced in tamoxifen-treated rats as detected by reductions in fibronectin, laminin 1, laminin 5 and collagen 1 cleavage fragments. Consistent with suppression in ECM proteolysis with tamoxifen treatment, matrix metalloproteinase-2 levels and activity were decreased. Biochemically extracted mammary ECM from tamoxifen-treated rats suppressed in vitro macrophage motility, which was rescued by the addition of proteolysed collagen or fibronectin. Mammary ECM from tamoxifen-treated rats also suppressed breast tumour cell motility, invasion and haptotaxis, reduced organoid size in 3-dimensional culture and blocked tumour promotion in an orthotopic xenograft model; effects which could be partially reversed by the addition of exogenous fibronectin. CONCLUSIONS: These data support the hypothesis that mammary stroma responds to tamoxifen treatment in concert with the epithelium and remodels to a microenvironment inhibitory to tumour cell progression. Reduced fibronectin levels and reduced ECM turnover appear to be hallmarks of the quiescent mammary microenvironment. These data may provide insight into attributes of a mammary microenvironment that facilitate tumour dormancy.

Different ways to die: cell death modes of the unicellular chlorophyte Dunaliella viridis exposed to various environmental stresses are mediated by the caspase-like activity DEVDase.

Programmed cell death is necessary for homeostasis in multicellular organisms and it is also widely recognized to occur in unicellular organisms. However, the mechanisms through which it occurs in unicells, and the enzymes involved within the final response is still the subject of heated debate. It is shown here that exposure of the unicellular microalga Dunaliella viridis to several environmental stresses, induced different cell death morphotypes, depending on the stimulus received. Senescent cells demonstrated classical and unambiguous apoptotic-like characteristics such as chromatin condensation, DNA fragmentation, intact organelles, and blebbing of the cell membrane. Acute heat shock caused general swelling and altered plasma membrane, but the presence of chromatin clusters and DNA strand breaks suggested a necrotic-like event. UV irradiated cells presented changes typical for necrosis, together with apoptotic characteristics resembling an intermediate cell-death phenotype termed aponecrosis-like. Cells subjected to hyperosmotic shock revealed chromatin spotting without DNA fragmentation, and extensive cytoplasmic swelling and vacuolization, comparable to a paraptotic-like cell death phenotype. Nitrogen-starved cells showed pyknosis, blebbing, and cytoplasmic consumption, indicating a similarity to autophagic/vacuolar-like cell death. The caspase-like activity DEVDase was measured by using the fluorescent substrate Ac-DEVD-AMC and antibodies against the human caspase-3 active enzyme cross-reacted with bands, the intensity of which paralleled the activity. All the environmental stresses tested produced a substantial increase in both DEVDase activity and protein levels. The irreversible caspase-3 inhibitor Z-DEVD-FMK completely inhibited the enzymatic activity whereas serine and aspartyl proteases inhibitors did not. These results show that cell death in D. viridis does not conform to a single pattern and that environmental stimuli may produce different types of cell death depending on the type and intensity of the stimulus, all of which help to understand the cell death-dependent and cell death-independent functions of caspase-like proteins. Hence, these data support the theory that alternative, non-apoptotic programmed cell death (PCDs), exist either in parallel or in an independent manner with apoptosis and were already present in single-celled organisms that evolved some 1.2-1.6 billion years ago.

Caspase Inhibition During Cold Storage Improves Graft Function and Histology in a Murine Kidney Transplant Model.

BACKGROUND: Prolonged cold ischemia is a risk factor for delayed graft function of kidney transplants, and is associated with caspase-3-mediated apoptotic tubular cell death. We hypothesized that treatment of tubular cells and donor kidneys during cold storage with a caspase inhibitor before transplant would reduce tubular cell apoptosis and improve kidney function after transplant. METHODS: Mouse tubular cells were incubated with either dimethyl sulfoxide (DMSO) or Q-VD-OPh during cold storage in saline followed by rewarming in normal media. For in vivo studies, donor kidneys from C57BL/6 mice were perfused with cold saline, DMSO (vehicle), or QVD-OPh. Donor kidneys were then recovered, stored at 4°C for 60 minutes, and transplanted into syngeneic C57BL/6 recipients. RESULTS: Tubular cells treated with a caspase inhibitor had significantly reduced capsase-3 protein expression, caspase-3 activity, and apoptotic cell death compared with saline or DMSO (vehicle) in a dose-dependent manner. Treatment of donor kidneys with a caspase inhibitor significantly reduced serum creatinine and resulted in significantly less tubular cell apoptosis, BBI, tubular injury, cast formation, and tubule lumen dilation compared with DMSO and saline-treated kidneys. CONCLUSIONS: Caspase inhibition resulted in decreased tubular cell apoptosis and improved renal function after transplantation. Caspase inhibition may be a useful strategy to prevent cold ischemic injury of donor renal grafts.

Regulation of renal lipid metabolism, lipid accumulation, and glomerulosclerosis in FVBdb/db mice with type 2 diabetes.

Diabetic kidney disease has been associated with the presence of lipid deposits, but the mechanisms for the lipid accumulation have not been fully determined. In the present study, we found that db/db mice on the FVB genetic background with loss-of-function mutation of the leptin receptor (FVB-Lepr(db) mice or FVBdb/db) develop severe diabetic nephropathy, including glomerulosclerosis, tubulointerstitial fibrosis, increased expression of type IV collagen and fibronectin, and proteinuria, which is associated with increased renal mRNA abundance of transforming growth factor-beta, plasminogen activator inhibitor-1, and vascular endothelial growth factor. Electron microscopy demonstrates increases in glomerular basement membrane thickness and foot process (podocyte) length. We found that there is a marked increase in neutral lipid deposits in glomeruli and tubules by oil red O staining and biochemical analysis for cholesterol and triglycerides. We also detected a significant increase in the renal expression of adipocyte differentiation-related protein (adipophilin), a marker of cytoplasmic lipid droplets. We examined the expression of sterol regulatory element-binding protein (SREBP)-1 and -2, transcriptional factors that play an important role in the regulation of fatty acid, triglyceride, and cholesterol synthesis. We found significant increases in SREBP-1 and -2 protein levels in nuclear extracts from the kidneys of FVBdb/db mice, with increases in the mRNA abundance of acetyl-CoA carboxylase, fatty acid synthase, and 3-hydroxy-3-methylglutaryl-CoA reductase, which mediates the increase in renal triglyceride and cholesterol content. Our results indicate that in FVBdb/db mice, renal triglyceride and cholesterol accumulation is mediated by increased activity of SREBP-1 and -2. Based on our previous results with transgenic mice overexpressing SREBP-1 in the kidney, we propose that increased expression of SREBPs plays an important role in causing renal lipid accumulation, glomerulosclerosis, tubulointerstitial fibrosis, and proteinuria in mice with type 2 diabetes.

Molecular profiling of ETS gene rearrangements in patients with prostate cancer registered in REDEEM clinical trial.

OBJECTIVE: Androgen-induced E26 transformation-specific (ETS) gene fusion-positive tumors have been associated with aggressive prostate cancer. The aim is to evaluate the ETS gene rearrangement status on initial biopsy of patients registered in the Reduction by Dutasteride of Clinical Progression Events in Expectant Management trial study and determine if gene fusion status was associated with disease progression. MATERIALS AND METHODS: Initial biopsy material from 146 men registered in Reduction by Dutasteride of Clinical Progression Events in Expectant Management trial study treated with dutasteride (73/146, 50%) and as placebo (73/146, 50%) were reviewed, and ERG and SPINK1 immunohistochemistry was performed. ERG- and SPINK1-negative cancer samples were evaluated for ETV1, ETV4, and ETV5 rearrangements by fluorescence in situ hybridization. Frequency of ETS gene aberrations in both groups was correlated with cancer progression including prostate-specific antigen progression, Gleason progression, and progression-free survival by logistic analysis, pairwise differences, and chunk likelihood ratio tests for the genotype groups. RESULTS AND CONCLUSIONS: Of the 146 patients, 99 (67.8%) (placebo, 51; dutasteride, 48) samples displayed the following Gleason patterns: 3+3 = 6 in 80 (54.8%) (placebo, 39; dutasteride, 41), 3+4 = 7 in 18 (12.3%) (placebo, 11; dutasteride, 7), and 4+4 = 8 in 1(0.68%) (placebo, 1). The remaining 47 samples showed atypical glands in 5 (3.4%) (placebo, 2; dutasteride, 3), HGPIN in 9 (6.1%) (placebo, 5; dutasteride, 4), and benign in 33 (22.6%) (placebo, 15; dutasteride, 18). Immunohistochemistry findings were positive for ERG and SPINK1 in 56 (56%) (placebo, 31; dutasteride, 25) and 9 (6.1%) (placebo, 5; dutasteride, 4) cases, respectively. ETV1 and ETV4 rearrangements were noted in 2 cases (1.4%) (placebo, 1; dutasteride, 1) and 1 (0.7%) (placebo, 1) case, respectively. No significant differences in the incidence of prostate cancer molecular aberrations between the groups were observed. There was no evidence that ETS fusion status was associated with disease progression.

Inhibition of Lipid Oxidation Increases Glucose Metabolism and Enhances 2-Deoxy-2-[(18)F]Fluoro-D-Glucose Uptake in Prostate Cancer Mouse Xenografts.

PURPOSE: Prostate cancer (PCa) is the second most common cause of cancer-related death among men in the United States. Due to the lipid-driven metabolic phenotype of PCa, imaging with 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) is suboptimal, since tumors tend to have low avidity for glucose. PROCEDURES: We have used the fat oxidation inhibitor etomoxir (2-[6-(4-chlorophenoxy)-hexyl]oxirane-2-carboxylate) that targets carnitine-palmitoyl-transferase-1 (CPT-1) to increase glucose uptake in PCa cell lines. Small hairpin RNA specific for CPT1A was used to confirm the glycolytic switch induced by etomoxir in vitro. Systemic etomoxir treatment was used to enhance [(18)F]FDG-positron emission tomography ([(18)F]FDG-PET) imaging in PCa xenograft mouse models in 24 h. RESULTS: PCa cells significantly oxidize more of circulating fatty acids than benign cells via CPT-1 enzyme, and blocking this lipid oxidation resulted in activation of the Warburg effect and enhanced [(18)F]FDG signal in PCa mouse models. CONCLUSIONS: Inhibition of lipid oxidation plays a major role in elevating glucose metabolism of PCa cells, with potential for imaging enhancement that could also be extended to other cancers.

Renal epithelioid angiomyolipoma with a negative premelanosome marker immunoprofile: a case report and review of the literature.

INTRODUCTION: The rare variant of renal epithelioid/pleomorphic angiomyolipoma has been reported in approximately 120 cases. One of the most important characteristics to differentiate these tumors from other renal cell neoplasms is their typical reactivity to premelanosome antigens. If such a tumor does not stain for HMB-45 or Melan-A, a specific diagnosis of epithelioid pleomorphic angiomyolipoma cannot be made with certainty. CASE PRESENTATION: We present here what is, to the best of our knowledge, the first case of epithelioid/pleomorphic angiomyolipoma of the kidney in a 50-year-old Caucasian man with no history of tuberous sclerosis, and with a tumor marker profile negative for several premelanosome antigens. The tumor was composed of sheets of pleomorphic, round to polygonal epithelioid cells with prominent eosinophilic cytoplasm, large nuclei, many multinucleated, and very prominent nucleoli. There were prominent vessels and rare interspersed smooth muscle fibers, but adipocytes were not identified. A tumor marker profile showed tumor cell reactivity for CD68, calponin and focally for CD10. Intervening smooth muscle was reactive with smooth muscle actin. The tumor lacked reactivity for melanin-associated antigens HMB-45 and Melan-A, and for CD31, pan-cytokeratin (AE1/3) and desmin. Electron microscopic examination of tumor cells confirmed the presence of premelanosome-like granules. CONCLUSIONS: Based on the characteristic microscopic appearance of this tumor, and its overall tumor marker profile, we concluded this was a renal epithelioid/pleomorphic angiomyolipoma with a negative premelanosome antigen phenotype.

The value of second-opinion pathology diagnoses on prostate biopsies from patients referred for management of prostate cancer.

Gleason score (GS) (sum of primary plus secondary grades) is used to predict patients' clinical outcome and to customize treatment strategies for prostate cancer (PC). However, due in part to pathologist misreading, there is significant discrepancy of GS between needle-core biopsies (NCB) and radical prostatectomy specimens. We assessed the requirement for re-evaluating NCB diagnosed by outside pathologists in patients referred to our institution for management of PC. In 100 patients, we reviewed both their original "outside" and second-opinion ("in-house") diagnoses of the same NCB specimens, and compared them with the diagnoses of the whole-mount radical prostatectomy (WMRP) specimens (gold standard for analysis). We found that both outside and in-house biopsy GS vary significantly from the WMRP diagnoses, with GS undergrading substantially predominating above overgrading. Statistical analysis demonstrated that the main diagnostic discrepancy was in the differentiation between primary and secondary Gleason grades (mainly 3 and 4) and that outside NCB GS was significantly less accurate with respect to the WMRP specimens than the in-house NCB GS. In addition, in a different cohort of 65 NCB cases, we found that in 5 out of 11 patients, outside pathologists failed to report the presence of extraprostatic extension, an important feature for diagnosis of a higher pathology stage (pT3a). Since histopathological evaluation is a critical factor for appropriate treatment selection, we recommend that a re-evaluation by in-house urologic pathologists should be performed in all outside NCB specimens before patients are admitted for treatment in any given institution.

Serum oxidized protein and prostate cancer risk within the Prostate Cancer Prevention Trial.

To evaluate the role of oxidative stress in prostate cancer risk, we analyzed serum levels of protein carbonyl groups in 1,808 prostate cancer cases and 1,805 controls, nested in the Prostate Cancer Prevention Trial, a randomized, placebo-controlled trial that found finasteride decreased prostate cancer risk. There were no significant differences in protein carbonyl levels in baseline samples between those later diagnosed with prostate cancer and those without at the end of study biopsy. Adjusted odds ratios and 95% confidence intervals (95% CI) for the 4th quartile of protein carbonyl level for the combined, placebo, and finasteride arms were 1.03 (95% CI, 0.85-1.24), 0.88 (95% CI, 0.69-1.12), and 1.27 (95% CI, 0.94-1.71), respectively. There were no significant associations between carbonyl level and risk when analyzing high-grade and low-grade disease separately, nor did finasteride affect protein oxidation levels. The results of this large nested case-control study do not support the hypothesis that oxidative stress, at least as measured by protein carbonyl level, plays a role in prostate cancer.

Role of leptin deficiency in early acute renal failure during endotoxemia in ob/ob mice.

It is known that, among human patients with sepsis, acute renal failure (ARF) dramatically increases mortality rates to 50 to 80%. However, the pathogenesis of septic ARF is not fully understood. An increase in endotoxin-induced mortality rates for leptin-deficient ob/ob mice was recently demonstrated. In comparison with ob/ob mice, db/db mice, which are deficient in the long isoforms of leptin receptors (Ob/Rb), demonstrate lower mortality rates after exposure to the endotoxin LPS. In db/db mice, mRNA for the short isoforms of leptin receptors is constitutively expressed in the kidney, lung, liver, and macrophages. It is known that plasma leptin levels increase in rodents after exposure to LPS, and this was demonstrated for db/db mice. Because ob/ob and db/db mice are both obese, factors other than obesity must be involved in the increased mortality rates for ob/ob mice. In this study, the hypothesis that the short forms of leptin receptors might offer protection against endotoxin-induced lethality at least in part by providing protection against ARF was examined. Serum leptin levels were significantly increased with LPS treatment in wild-type and db/db mice but not ob/ob mice. GFR decreased significantly 16 h after the homozygous ob/ob mice received intraperitoneal injections of 0.3 mg/kg LPS (0.37 +/- 0.04 ml/min per g kidney versus 0.83 +/- 0.06 ml/min per g kidney, n = 6, P < 0.01); the mean arterial pressure (MAP) remained unchanged. For ob/ob littermates (+/?ob), there was no significant change in either MAP or GFR when the mice were challenged with the same time interval (16 h) and dose of LPS. In contrast to ob/ob mice, there was no significant change in GFR or MAP when homozygous db/db mice or their littermates received injections of an even higher dose of LPS (0.4 mg/kg). Mouse recombinant leptin had no effect on GFR when ob/ob mice received 0.3 mg/kg LPS injections. However, renal function (serum creatinine levels, 0.4 +/- 0.1 mg/dl versus 0.9 +/- 0.1 mg/dl, P < 0.01) and MAP (68 +/- 4 mmHg versus 51 +/- 2 mmHg, n = 6, P < 0.01) were significantly improved with leptin replacement when the ob/ob mice developed hypotensive ARF with a higher dose of LPS (0.5 mg/kg). In summary, the previously reported increased susceptibility to LPS of ob/ob mice, compared with db/db mice, may be attributable at least in part to increased susceptibility to ARF.