Mendelian randomization studies of depression: evidence, opportunities, and challenges.

BACKGROUND: Major depressive disorder (MDD) poses a significant social and economic burden worldwide. Identifying exposures, risk factors, and biological mechanisms that are causally connected to MDD can help build a scientific basis for disease prevention and development of novel therapeutic approaches. METHODS: In this systematic review, we assessed the evidence for causal relationships between putative causal risk factors and MDD from Mendelian randomization (MR) studies, following PRISMA. We assessed methodological quality based on key elements of the MR design: use of a full instrumental variable analysis and validation of the three key MR assumptions. RESULTS: We included methodological details and results from 52 articles. A causal link between lifestyle, metabolic, inflammatory biomarkers, particular pathological states and MDD is supported by MR investigations, although results for each category varied substantially. CONCLUSIONS: While this review shows how MR can offer useful information for examining prospective treatment targets and better understanding the pathophysiology of MDD, some methodological flaws in the existing literature limit reliability of results and probably underlie their heterogeneity. We highlight perspectives and recommendations for future works on MR in psychiatry.

Normal Anatomy, Histology, and Spontaneous Pathology of the Kidney, and Selected Renal Biomarker Reference Ranges in the Cynomolgus Monkey.

To further our understanding of the nonhuman primate kidney anatomy, histology, and incidences of spontaneous pathology, we retrospectively examined kidneys from a total of 505 control Cynomolgus monkeys (Macaca fascicularis; 264 male and 241 females) aged 2 to 6 years, from toxicity studies. Kidney weights, urinalysis, and kidney-related clinical biochemistry parameters were also evaluated. Although the functional anatomy of the monkey kidney is relatively similar to that of other laboratory animals and humans, a few differences and species-specific peculiarities exist. Unlike humans, the macaque kidney is unipapillate, with a relatively underdeveloped papilla, scarce long loops of Henle, and a near-equivalent cortical to medullary ratio. The most common spontaneous microscopic findings were interstitial infiltrates or interstitial nephritis and other tubular lesions, but several forms of glomerulopathy that may be interpreted as drug-induced were occasionally observed. Common incidental findings of little pathological significance included: papillary mineralization, epithelial pigment, multinucleate cells, cuboidal metaplasia of the Bowman's capsule, and urothelial inclusions. Kidney weights, and some clinical chemistry parameters, showed age- and sex-related variations. Taken together, these data will aid the toxicologic pathologist to better evaluate the nonhuman primate kidney and assess the species' suitability as a model for identifying and characterizing drug-induced injury.

An Immunohistochemical Investigation of Renal Phospholipidosis and Toxicity in Rats.

Immunohistochemical staining for the lysosome-associated membrane protein 2 (LAMP-2) has been proposed previously as an alternative to electron microscopy to identify hepatic phospholipidosis. This study used LAMP-2 immunohistochemistry (IHC) to diagnose phospholipidosis in rats exhibiting renal tubular injury. Rats were administered toreforant, a histamine H4 receptor antagonist by oral gavage at a dose of 3, 10, or 100 mg/kg/d for 6 months. Hematoxylin and eosin staining revealed renal tubular epithelial cell vacuolation, hypertrophy, degeneration, and luminal dilation in the 100 mg/kg/d group animals. Renal tubular injury was confirmed using kidney injury marker 1 (KIM-1) IHC. The involvement of phosopholipidosis in the renal injury was investigated by LAMP-2. Adipophilin IHC was included to differentiate phospholipidosis from lipidosis. Increased LAMP-2 staining was observed in the 100 mg/kg/d group animals when compared to vehicle group animals. Lysosome-associated membrane protein-2 staining was most prominent in the outer stripe of the outer medulla where KIM-1 staining was also most prominent. By contrast, adipophilin staining was not increased. Phospholipidosis was also confirmed by electron microscopy. These data support the use of LAMP-2 IHC as a diagnostic tool and suggest an association between phospholipidosis and the renal tubular injury caused by toreforant.

Alteration of the glucagon axis in GPR120 (FFAR4) knockout mice: a role for GPR120 in glucagon secretion.

GPR40 (FFAR1) and GPR120 (FFAR4) are G-protein-coupled receptors (GPCRs) that are activated by long chain fatty acids (LCFAs). GPR40 is expressed at high levels in islets and mediates the ability of LCFAs to potentiate glucose-stimulated insulin secretion (GSIS). GPR120 is expressed at high levels in colon, adipose, and pituitary, and at more modest levels in pancreatic islets. The role of GPR120 in islets has not been explored extensively. Here, we confirm that saturated (e.g. palmitic acid) and unsaturated (e.g. docosahexaenoic acid (DHA)) LCFAs engage GPR120 and demonstrate that palmitate- and DHA-potentiated glucagon secretion are greatly reduced in isolated GPR120 KO islets. Remarkably, LCFA potentiated glucagon secretion is similarly reduced in GPR40 KO islets. Compensatory changes in mRNA expression of GPR120 in GPR40 KO islets, and vice versa, do not explain that LCFA potentiated glucagon secretion seemingly involves both receptors. LCFA-potentiated GSIS remains intact in GPR120 KO islets. Consistent with previous reports, GPR120 KO mice are hyperglycemic and glucose intolerant; however, our KO mice display evidence of a hyperactive counter-regulatory response rather than insulin resistance during insulin tolerance tests. An arginine stimulation test and a glucagon challenge confirmed both increases in glucagon secretion and liver glucagon sensitivity in GPR120 KO mice relative to WT mice. Our findings demonstrate that GPR120 is a nutrient sensor that is activated endogenously by both saturated and unsaturated long chain fatty acids and that an altered glucagon axis likely contributes to the impaired glucose homeostasis observed in GPR120 KO mice.

PI3Kγ kinase activity is required for optimal T-cell activation and differentiation.

Phosphatidylinositol-3-kinase gamma (PI3Kγ) is a leukocyte-specific lipid kinase with signaling function downstream of G protein-coupled receptors to regulate cell trafficking, but its role in T cells remains unclear. To investigate the requirement of PI3Kγ kinase activity in T-cell function, we studied T cells from PI3Kγ kinase-dead knock-in (PI3Kγ(KD/KD)) mice expressing the kinase-inactive PI3Kγ protein. We show that CD4(+) and CD8(+) T cells from PI3Kγ(KD/KD) mice exhibit impaired TCR/CD28-mediated activation that could not be rescued by exogenous IL-2. The defects in proliferation and cytokine production were also evident in naïve and memory T cells. Analysis of signaling events in activated PI3Kγ(KD/KD) T cells revealed a reduction in phosphorylation of protein kinase B (AKT) and ERK1/2, a decrease in lipid raft formation, and a delay in cell cycle progression. Furthermore, PI3Kγ(KD/KD) CD4(+) T cells displayed compromised differentiation toward Th1, Th2, Th17, and induced Treg cells. PI3Kγ(KD/KD) mice also exhibited an impaired response to immunization and a reduced delayed-type hypersensitivity to Ag challenge. These findings indicate that PI3Kγ kinase activity is required for optimal T-cell activation and differentiation, as well as for mounting an efficient T cell-mediated immune response. The results suggest that PI3Kγ kinase inhibitors could be beneficial in reducing the undesirable immune response in autoimmune diseases.

Antagonism of the histamine H4 receptor reduces LPS-induced TNF production in vivo.

OBJECTIVE: Antagonism of the histamine H4 receptor (H4R) has been shown to be anti-inflammatory in a number of preclinical disease models, however the exact mechanisms behind this are still being uncovered. In vitro, the receptor interacts with TLR and impacts inflammatory mediator production from a number of different cell types. Here it is shown that this interaction also occurs in vivo. MATERIALS AND METHODS: Wild-type and H4R deficient BALB/c mice received an i.p. injection of LPS in PBS in conjunction with p.o. JNJ 7777120 or JNJ 28307474 (H4R antagonists). Two hours later blood was collected and TNF was measured. RESULTS: Two different H4R antagonists inhibited LPS-induced TNF production in mice and this production was also reduced in H4R-deficient mice. The TNF mRNA analysis showed that the major source of the cytokine was the liver and not blood, and that the H4R antagonist only reduced the expression levels in the liver. Depletion or inactivation of macrophages reduced the TNF levels and eliminated the H4R sensitivity. Treatment with an H4R antagonist also reduced LPS-induced liver injury and blocked LPS-enhanced lung inflammation in mice. CONCLUSION: The data support an interaction between H4R and TLR activation in vivo that can drive inflammatory responses.

Time course of renal proximal tubule injury, reversal, and related biomarker changes in rats following cisplatin administration.

Cisplatin (CDDP) is known to produce renal proximal tubule injury. Various renal biomarkers have been related to CDDP nephrotoxicity in previous research, but the temporal and spatial relationship of these biomarkers to injury reversal has not been well defined. In this study, the progression and reversal of renal histopathology findings relative to serum and urinary biomarker changes were examined during a 4-week postdose period following single intraperitoneal administration of CDDP (1 mg/kg) or 0.9% saline. Degeneration, vacuolation, inflammation, and regeneration of the S3 segment of proximal tubules were evident 72 hours following CDDP administration. Tubular degeneration and regeneration were also observed at 1 and 1.5 weeks but at lower incidences and/or severity indicating partial reversal. Complete histologic reversal was observed by 2 weeks following CDDP administration. Urinary kidney injury molecule 1 (KIM-1), α-glutathione-S-transferase (α-GST), and albumin levels increased at 72 hours postdosing, concurrently with the earliest histologic evidence of tubule injury. Changes in urinary KIM-1 correlated with KIM-1 immunostaining in the proximal tubular epithelial cells. No significant changes in serum biomarkers occurred except for a minimal increase in urea nitrogen at 1.5 weeks postdosing. Of the novel renal biomarkers examined, urinary KIM-1, α-GST, and albumin showed excellent concordance with CDDP-induced renal injury progression and reversal; and these biomarkers were more sensitive than traditional serum biomarkers in detecting early, acute renal tubular damage confirmed by histopathology. Furthermore, urinary KIM-1, α-GST, and albumin outperformed other biomarkers in correlating with the time of maximum histologic injury.

The genetic background shapes the susceptibility to mitochondrial dysfunction and NASH progression.

Non-alcoholic steatohepatitis (NASH) is a global health concern without treatment. The challenge in finding effective therapies is due to the lack of good mouse models and the complexity of the disease, characterized by gene-environment interactions. We tested the susceptibility of seven mouse strains to develop NASH. The severity of the clinical phenotypes observed varied widely across strains. PWK/PhJ mice were the most prone to develop hepatic inflammation and the only strain to progress to NASH with extensive fibrosis, while CAST/EiJ mice were completely resistant. Levels of mitochondrial transcripts and proteins as well as mitochondrial function were robustly reduced specifically in the liver of PWK/PhJ mice, suggesting a central role of mitochondrial dysfunction in NASH progression. Importantly, the NASH gene expression profile of PWK/PhJ mice had the highest overlap with the human NASH signature. Our study exposes the limitations of using a single mouse genetic background in metabolic studies and describes a novel NASH mouse model with features of the human NASH.

Mitochondrial and NAD+ metabolism predict recovery from acute kidney injury in a diverse mouse population.

Acute kidney failure and chronic kidney disease are global health issues steadily rising in incidence and prevalence. Animal models on a single genetic background have so far failed to recapitulate the clinical presentation of human nephropathies. Here, we used a simple model of folic acid-induced kidney injury in 7 highly diverse mouse strains. We measured plasma and urine parameters, as well as renal histopathology and mRNA expression data, at 1, 2, and 6 weeks after injury, covering the early recovery and long-term remission. We observed an extensive strain-specific response ranging from complete resistance of the CAST/EiJ to high sensitivity of the C57BL/6J, DBA/2J, and PWK/PhJ strains. In susceptible strains, the severe early kidney injury was accompanied by the induction of mitochondrial stress response (MSR) genes and the attenuation of NAD+ synthesis pathways. This is associated with delayed healing and a prolonged inflammatory and adaptive immune response 6 weeks after insult, heralding a transition to chronic kidney disease. Through a thorough comparison of the transcriptomic response in mouse and human disease, we show that critical metabolic gene alterations were shared across species, and we highlight the PWK/PhJ strain as an emergent model of transition from acute kidney injury to chronic disease.

Inhibitors of TGFßR1/ALK4/JNK3/Flt1 Kinases in Cynomolgus Macaques Lead to the Rapid Induction of Renal Epithelial Tumors.

Two young cynomolgus macaques (Macaca fascicularis) given a small molecule kinase inhibitor ((S)-4-((2-(5-chloro-2-fluorophenyl)-5-isopropylpyrimidin-4-yl)amino)-N-(2-hydroxypropyl)nicotinamide [SCIO-120]) via nasogastric intubation gavage, once-daily for 21 days at 400 mg/kg/day, developed an unusual epithelial proliferative process in the renal parenchyma. Morphological and immunohistochemical characterization of the lesions confirmed an invasive malignant epithelial neoplasm (carcinoma). A similar renal neoplasm was seen in a third macaque after a 14-day exposure to a second kinase inhibitor in the same chemical series ((S) 4-((2-(5-chloro-2-fluorophenyl)-5-methoxypyrimidin-4-yl)amino)-N-cyclopropylnicotinamide [SCIO-974]). Despite remarkably short latency periods, exposure to these kinase inhibitors was likely causally associated with the induction of the renal tumors, as renal carcinomas are exceedingly rare spontaneously in macaques. Both SCIO-120 and SCIO-974 were designed as potent TGFßR1 inhibitors (IC50s 37 and 39 nM, respectively). SCIO-120 and SCIO-974 inhibited additional kinases, most notably closely related ALK4 (IC50 = 34 and 20 nM, respectively), c-Jun n-Terminal kinase 3 (JNK3, IC50 = 10 and 20 nM, respectively), and Fms-related tyrosine kinase 1 (29 and 76 nM, respectively). TGFßR1 has been specifically implicated in epithelial proliferative disorders, including neoplasia. Neither SCIO-120 nor SCIO-974 was genotoxic based on bacterial reverse mutation and/or clastogenicity screening assays. The rapid appearance of renal carcinomas in primates following short-term treatment with nongenotoxic kinase inhibitors is remarkable and suggests that the compounds had noteworthy tumor-enhancing effects, hypothetically linked to their TGFßR1 inhibition activity. These observations have implications for mechanisms of carcinogenesis and TGFßR1 biology.

Histamine H4 receptor antagonism diminishes existing airway inflammation and dysfunction via modulation of Th2 cytokines.

BACKGROUND: Airway remodeling and dysfunction are characteristic features of asthma thought to be caused by aberrant production of Th2 cytokines. Histamine H4 receptor (H4R) perturbation has previously been shown to modify acute inflammation and Th2 cytokine production in a murine model of asthma. We examined the ability of H4R antagonists to therapeutically modify the effects of Th2 cytokine production such as goblet cell hyperplasia (GCH), and collagen deposition in a sub-chronic model of asthma. In addition, effects on Th2 mediated lung dysfunction were also determined. METHODS: Mice were sensitized to ovalbumin (OVA) followed by repeated airway challenge with OVA. After inflammation was established mice were dosed with the H4R antagonist, JNJ 7777120, or anti-IL-13 antibody for comparison. Airway hyperreactivity (AHR) was measured, lungs lavaged and tissues collected for analysis. RESULTS: Therapeutic H4R antagonism inhibited T cell infiltration in to the lung and decreased Th2 cytokines IL-13 and IL-5. IL-13 dependent remodeling parameters such as GCH and lung collagen were reduced. Intervention with H4R antagonist also improved measures of central and peripheral airway dysfunction. CONCLUSIONS: These data demonstrate that therapeutic H4R antagonism can significantly ameliorate allergen induced, Th2 cytokine driven pathologies such as lung remodeling and airway dysfunction. The ability of H4R antagonists to affect these key manifestations of asthma suggests their potential as novel human therapeutics.

Genetic deletion of Fatty Acid Amide Hydrolase results in improved long-term outcome in chronic autoimmune encephalitis.

The enzyme Fatty Acid Amide Hydrolase (FAAH) is a key regulator of the endogenous levels of a family of biologically active lipid mediators, the fatty acid amides. These include anandamide, oleoyl ethanolamide and palmitoyl ethanolamide, and their effects are mediated by a variety of downstream targets including cannabinoid receptors and peroxisome proliferator-activated receptors (PPARs). Activation of both of these may have anti-inflammatory and neuroprotective effects. Levels of all three mediators are low in normal nervous tissue, but substantially elevated in mice lacking FAAH as a result of genetic deletion. There is a long anecdotal history of cannabis use by patients suffering from multiple sclerosis, and preclinical studies have indicated beneficial effects of cannabinoid receptor stimulation on both long-term outcome and acute muscle spasm in rodent models of multiple sclerosis (experimental autoimmune encephalitis; EAE). Thus far no report has appeared on the effect of inhibition of FAAH on the progression of EAE. Using a chronic mouse EAE model, we present data indicating that mice lacking FAAH experience an initial inflammatory phase of EAE similar in severity to wild type controls, but exhibited a more substantial clinical remission compared to wild type mice.

Inhibiting TGF-beta signaling restores immune surveillance in the SMA-560 glioma model.

Transforming growth factor-beta (TGF-beta) is a proinvasive and immunosuppressive cytokine that plays a major role in the malignant phenotype of gliomas. One novel strategy of disabling TGF-beta activity in gliomas is to disrupt the signaling cascade at the level of the TGF-beta receptor I (TGF-betaRI) kinase, thus abrogating TGF-beta-mediated invasiveness and immune suppression. SX-007, an orally active, small-molecule TGF-betaRI kinase inhibitor, was evaluated for its therapeutic potential in cell culture and in an in vivo glioma model. The syngeneic, orthotopic glioma model SMA-560 was used to evaluate the efficacy of SX-007. Cells were implanted into the striatum of VM/Dk mice. Dosing began three days after implantation and continued until the end of the study. Efficacy was established by assessing survival benefit. SX-007 dosed at 20 mg/kg p.o. once daily (q.d.) modulated TGF-beta signaling in the tumor and improved the median survival. Strikingly, approximately 25% of the treated animals were disease-free at the end of the study. Increasing the dose to 40 mg/kg q.d. or 20 mg/kg twice daily did not further improve efficacy. The data suggest that SX-007 can exert a therapeutic effect by reducing TGF-beta-mediated invasion and reversing immune suppression. SX-007 modulates the TGF-beta signaling pathway and is associated with improved survival in this glioma model. Survival benefit is due to reduced tumor invasion and reversal of TGF-beta-mediated immune suppression, allowing for rejection of the tumor. Together, these results suggest that treatment with a TGF-betaRI inhibitor may be useful in the treatment of glioblastoma.

Antitumor activity of TGF-beta inhibitor is dependent on the microenvironment.

Pancreatic cancer is one of the deadliest forms of cancer and effective treatment remains a clinical challenge. Transforming growth factor-beta (TGF-beta) has important roles in primary tumor progression and in promoting metastasis, and has become an attractive target for therapy. Previously, we reported that treatment of pancreatic cancer cells in vitro with SD-208, a small molecule inhibitor of the TGF-beta receptor I kinase (TGF-betaRI), inhibited expression of genes associated with tumor progression and inhibited invasiveness in a cell-based assay. In a demonstration of efficacy of TGF-beta signaling inhibition in an in vivo model of pancreatic cancer, we showed significantly reduced primary tumor weight and decreased incidence of metastasis in the Panc-1 orthotopic xenograft model of established pancreatic cancer. In this report, we extend these in vivo findings to examine the mechanistic consequences of TGF-betaRI inhibition on Panc-1 primary tumors and their microenvironment in situ. In a longitudinal study of TGF-betaRI inhibition in the Panc-1 orthotopic model, we show that SD-208 treatment significantly reduced tumor growth measured as bioluminescence intensity throughout the study. Histological evaluation revealed that SD-208 treatment reduced proliferation and induced apoptosis in the primary tumors, and reduced fibrosis in the tumor microenvironment. An immune contribution (greater B-cell infiltration in SD-208-treated tumors) was also suggested by the histological analyses. SD-208 not only blocked direct TGF-beta signaling in Panc-1 primary tumors (reduced phospho SMAD2/3), but also down-regulated the expression of TGF-beta-regulated genes (PAI-1 and COL7A1). Taken together, our results indicate that a TGF-betaRI kinase inhibitor has a potential therapeutic benefit for pancreatic cancer patients.

Immunolocalization of novel corticomedullary tubule injury markers in Cynomolgus monkeys treated with amphotericin B.

Amphotericin B (AmpB) nephrotoxicity was used to assess the utility of drug­induced kidney injury (DIKI) biomarkers in an exploratory study in male cynomolgus monkeys. All animals had quantifiable levels of AmpB in plasma on days 1 and 4. There were no clinical signs of AmpB­induced toxicity in this study. The gold standard method used to confirm AmpB­induced DIKI was anatomic pathology which revealed microscopic lesions with varying grades of severity. Immunolocalization of alpha­1 microglobulin (α­1M), kidney injury molecule 1 (KIM­1), osteopontin (OPN) and neutrophil gelatinase­associated lipocalin (NGAL) proteins was evaluated in formalin­fixed, paraffin­embedded monkey kidney tissue sections. AmpB related immunoreactivities were identified in distinct nephron segments of treated monkeys including α­1M in damaged proximal tubule epithelium, KIM­1 in damaged medullary tubule epithelium, OPN mostly in the infiltrating cells of cortical tubule interstitium, and NGAL in the granular and cellular cast in dilatated cortical tubules. Variations in α­1M, KIM­1, OPN and NGAL immunolocalization appear as promising DIKI protein biomarkers when monitoring for AmpB­induced corticomedullary tubule injury in male cynomolgus monkeys.

SD-208, a novel transforming growth factor beta receptor I kinase inhibitor, inhibits growth and invasiveness and enhances immunogenicity of murine and human glioma cells in vitro and in vivo.

The cytokine transforming growth factor (TGF)-beta, by virtue of its immunosuppressive and promigratory properties, has become a major target for the experimental treatment of human malignant gliomas. Here we characterize the effects of a novel TGF-beta receptor (TGF-betaR) I kinase inhibitor, SD-208, on the growth and immunogenicity of murine SMA-560 and human LN-308 glioma cells in vitro and the growth of and immune response to intracranial SMA-560 gliomas in syngeneic VM/Dk mice in vivo. SD-208 inhibits the growth inhibition of TGF-beta-sensitive CCL64 cells mediated by recombinant TGF-beta1 or TGF-beta2 or of TGF-beta-containing glioma cell supernatant at an EC(50) of 0.1 mumol/L. SD-208 blocks autocrine and paracrine TGF-beta signaling in glioma cells as detected by the phosphorylation of Smad2 or TGF-beta reporter assays and strongly inhibits constitutive and TGF-beta-evoked migration and invasion, but not viability or proliferation. Peripheral blood lymphocytes or purified T cells, cocultured with TGF-beta-releasing LN-308 glioma cells in the presence of SD-208, exhibit enhanced lytic activity against LN-308 targets. The release of interferon gamma and tumor necrosis factor alpha by these immune effector cells is enhanced by SD-208, whereas the release of interleukin 10 is reduced. SD-208 restores the lytic activity of polyclonal natural killer cells against glioma cells in the presence of recombinant TGF-beta or of TGF-beta-containing glioma cell supernatant. The oral bioavailability of SD-208 was verified by demonstrating the inhibition of TGF-beta-induced Smad phosphorylation in spleen and brain. Systemic SD-208 treatment initiated 3 days after the implantation of SMA-560 cells into the brains of syngeneic VM/Dk mice prolongs their median survival from 18.6 to 25.1 days. Histologic analysis revealed no difference in blood vessel formation, proliferation, or apoptosis. However, animals responding to SD-208 showed an increased tumor infiltration by natural killer cells, CD8 T cells, and macrophages. These data define TGF-beta receptor I kinase inhibitors such as SD-208 as promising novel agents for the treatment of human malignant glioma and other conditions associated with pathological TGF-beta activity.

Acute biomarker panel changes associated with amphotericin B nephrotoxicity in female Sprague-Dawley rats.

To date, eight next­generation urinary protein kidney safety biomarkers have been qualified to enable monitoring for subclinical drug­induced kidney injury (DIKI) in rat preclinical studies; however, most DIKI biomarker studies have included only male rats. The objective of this study was to assess the utility of novel DIKI biomarkers, including but not limited to urinary total protein, albumin, cystatin C and osteopontin in female Sprague­Dawley rats (8/group) that received repeated intravenous injections of amphotericin B (AmpB, 3 mg/kg/day) or vehicle for 10 consecutive days. Serial serum/urine samples were collected on study day (D)4, D8, and D11. Surviving animals were necropsied on D11. The AmpB­induced kidney histopathology findings were characterized by cortical and medullary tubular alterations, interstitial inflammation, intratubular granular and inflammatory cell casts, acute pelvic inflammation and tubular mineralization. Significant elevations in urinary clusterin on D4, D8 and D11 (3.5 fold, 2.2 fold and 3.3 fold respectively) were observed (versus concurrent controls) following repeated injections of AmpB. In addition, significantly elevated (fold changes) in biomarkers, neutrophil gelatinase­associated lipocalin (14.6 fold), albumin (13.5 fold), cystatin C (13.5 fold), total protein (3.5 fold), kidney injury molecule 1 (3.0 fold) and osteopontin (2.3 fold) were detected in urine as early as D4. These findings demonstrate the value of early elevations in nephron­specific DIKI biomarkers for detecting subclinical AmpB nephrotoxicity in female Sprague­Dawley rats. These findings are anticipated to provide the basis for inclusion of female rats on a case­by­case basis in preclinical toxicology studies designed to detect DIKI.

Prolyl hydroxylase inhibition corrects functional iron deficiency and inflammation-induced anaemia in rats.

BACKGROUND AND PURPOSE: Small-molecule inhibitors of prolyl hydroxylase (PHD) enzymes are a novel target for the treatment of anaemia and functional iron deficiency (FID). Other than being orally bioavailable, the differentiation of PHD inhibitors from recombinant human erythropoietin (rhEPO) has not been demonstrated. EXPERIMENTAL APPROACH: JNJ-42905343 was identified and characterized as a novel inhibitor of PHD and its action was compared with rhEPO in healthy rats and in a rat model of inflammation-induced anaemia and FID [peptidoglycan-polysaccharide (PGPS) model]. KEY RESULTS: Oral administration of JNJ-42905343 to healthy rats increased the gene expression of cytochrome b (DcytB) and divalent metal-ion transporter 1 (DMT1) in the duodenum, and increased plasma EPO. Repeated administration of JNJ-42905343 for 28 days increased blood haemoglobin, mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV). The serum iron concentration was increased with low doses (0.3 mg·kg(-1) ) but reduced at high doses (6 mg·kg(-1) ). In PGPS-treated rats, administration of JNJ-42905343 for 28 days corrected FID and anaemia, as reflected by increased blood haemoglobin, MCH and MCV. Increased expression of DcytB and DMT1 genes in the duodenum resulting in increased iron availability was defined as the mechanism for these effects. rhEPO did not affect DcytB and DMT1 and was not effective in PGPS-treated rats. CONCLUSIONS AND IMPLICATIONS: PHD inhibition has a beneficial effect on iron metabolism in addition to stimulating the release of EPO. Small-molecule inhibitors of PHD such as JNJ-42905343 represent a mechanism distinct from rhEPO to treat anaemia and FID.

Carbohydrate malabsorption mechanism for tumor formation in rats treated with the SGLT2 inhibitor canagliflozin.

Canagliflozin is an SGLT2 inhibitor used for the treatment of type 2 diabetes mellitus. Studies were conducted to investigate the mechanism responsible for renal tubular tumors and pheochromocytomas observed at the high dose in a 2-year carcinogenicity study in rats. At the high dose (100mg/kg) in rats, canagliflozin caused carbohydrate malabsorption evidenced by inhibition of intestinal glucose uptake, decreased intestinal pH and increased urinary calcium excretion. In a 6-month mechanistic study utilization of a glucose-free diet prevented carbohydrate malabsorption and its sequelae, including increased calcium absorption and urinary calcium excretion, and hyperostosis. Cell proliferation in the kidney and adrenal medulla was increased in rats maintained on standard diet and administered canagliflozin (100mg/kg), and in addition an increase in the renal injury biomarker KIM-1 was observed. Increased cell proliferation is considered as a proximal event in carcinogenesis. Effects on cell proliferation, KIM-1 and calcium excretion were inhibited in rats maintained on the glucose-free diet, indicating they are secondary to carbohydrate malabsorption and are not direct effects of canagliflozin.

Topical alpha-selective p38 MAP kinase inhibition reduces acute skin inflammation in guinea pig.

Certain skin pathologies, including psoriasis, are thought to be immune-mediated inflammatory diseases. Available literature clearly indicates the involvement of inflammatory cells (neutrophils, T cells, and macrophages), their cytokines, and the p38 mitogen-activated protein kinase (MAPK) signaling pathway in the pathophysiology of psoriasis. Neutrophils play an important role in the formation of acute inflammatory changes in psoriasis. Acute inflammation or acute flares in psoriasis remain poorly addressed in clinical medicine. In this communication, we first establish a simple and reproducible model for studying neutrophil-mediated acute skin inflammation. Using the hairless guinea pig, due to the similarity of skin architecture to that of human, acute inflammation was induced with an intradermal injection of 50 µg/mL lipopolysaccharide (LPS) in 50 µL solution. Myeloperoxidase (MPO) activity was measured by MPO-positive neutrophils and shown to increase for 24-hours post-injection. Simultaneously, the level of phosphorylated p38 MAPK was documented for 48-hours post-LPS injection in the skin. Next, we used this model to examine the therapeutic potential of an α-selective p38 MAPK inhibitor, SCIO-469. A comparison of topical application of SCIO-469 at 5 mg/mL or 15 mg/mL to vehicle revealed that SCIO-469 dose-dependently reduces acute skin inflammation and that this effect is statistically significant at the higher dose. Further examination of tissues that received this dose also revealed statistically significant reduction of MPO activity, phosphorylated p38 MAPK, interleukin-6, and cyclooxygenase-2. These data suggest that the α-selective p38 MAPK inhibitor, SCIO-469, acts as a topical anti-inflammatory agent via the p38 MAPK pathway to reduce neutrophil induced acute inflammation in the skin. These observations suggest that α-selective p38 MAPK inhibition may be an effective therapeutic strategy to manage acute skin inflammation.