Kynurenine monooxygenase regulates inflammation during critical illness and recovery in experimental acute pancreatitis

Kynurenine monooxygenase (KMO) blockade protects against multiple organ failure caused by acute pancreatitis (AP), but the link between KMO and systemic inflammation has eluded discovery until now. Here, we show that the KMO product 3-hydroxykynurenine primes innate immune signaling to exacerbate systemic inflammation during experimental AP. We find a tissue-specific role for KMO, where mice lacking Kmo solely in hepatocytes have elevated plasma 3-hydroxykynurenine levels that prime inflammatory gene transcription. 3-Hydroxykynurenine synergizes with interleukin-1β to cause cellular apoptosis. Critically, mice with elevated 3-hydroxykynurenine succumb fatally earlier and more readily to experimental AP. Therapeutically, blockade with the highly selective KMO inhibitor GSK898 rescues the phenotype, reducing 3-hydroxykynurenine and protecting against critical illness and death. Together, our findings establish KMO and 3-hydroxykynurenine as regulators of inflammation and the innate immune response to sterile inflammation. During critical illness, excess morbidity and death from multiple organ failure can be rescued by systemic KMO blockade.

Utilizing Whole Slide Images for the Primary Evaluation and Peer Review of a GLP-Compliant Rodent Toxicology Study

The approach undertaken to deliver a Good Laboratory Practice (GLP) validation of whole slide images (WSIs) and the associated workflow for the digital primary evaluation and peer review of a GLP-compliant rodent inhalation toxicity study is described. The contract research organization (CRO) undertook validation of the slide scanner, scanner software, and associated database software. This provided a GLP validated environment within the database software for the primary histopathologic evaluation using WSI and viewed with the database software web viewer. The CRO also validated a cloud-based digital pathology platform that supported the upload and transfer of WSI and metadata to a cache within the sponsor's local area network. The sponsor undertook a separate GLP validation of the same cloud-based digital pathology platform to cover the download and review of the WSI. The establishment of a fit-for-purpose GLP-compliant workflow for WSI and successful deployment for the digital primary evaluation and peer review of a large GLP toxicology study enabled flexibility in accelerated global working and potential future reuse of digitized data for advanced artificial intelligence and machine learning image analysis.

Historical control background incidence of spontaneous pituitary gland lesions of Han-Wistar and Sprague-Dawley rats and CD-1 mice used in 104-week carcinogenicity studies

The aim of this study was to determine the range and incidences of spontaneous microscopic lesions of the pituitary gland in control Han-Wistar and Sprague-Dawley rats and CD-1 mice from 104-week carcinogenicity studies carried out between 1998 and 2010 at Charles River Edinburgh. In both strains of rats and in CD-1 mice, non-proliferative lesions of the pituitary gland were generally uncommon, excluding cysts/pseudocysts (6.42% in Han-Wistar rats, 5.85% in Sprague-Dawley rats, and 2.08% in CD-1 mice). Primary proliferative lesions were most frequently found in the pars distalis of the pituitary gland. Adenomas and carcinomas of the pars distalis were more common in Sprague-Dawley rats (49.33% and 2.85%, respectively) than in Han-Wistar rats (27.29% and 0.21%, respectively), and adenomas in both strains of rats and CD-1 mice exhibited a marked sex predisposition, with females more commonly affected.

αv integrins on mesenchymal cells regulate skeletal and cardiac muscle fibrosis

Mesenchymal cells expressing platelet-derived growth factor receptor beta (PDGFRβ) are known to be important in fibrosis of organs such as the liver and kidney. Here we show that PDGFRβ+ cells contribute to skeletal muscle and cardiac fibrosis via a mechanism that depends on αv integrins. Mice in which αv integrin is depleted in PDGFRβ+ cells are protected from cardiotoxin and laceration-induced skeletal muscle fibrosis and angiotensin II-induced cardiac fibrosis. In addition, a small-molecule inhibitor of αv integrins attenuates fibrosis, even when pre-established, in both skeletal and cardiac muscle, and improves skeletal muscle function. αv integrin blockade also reduces TGFβ activation in primary human skeletal muscle and cardiac PDGFRβ+ cells, suggesting that αv integrin inhibitors may be effective for the treatment and prevention of a broad range of muscle fibroses.

Perivascular Mesenchymal Stem Cells in Sheep: Characterization and Autologous Transplantation in a Model of Articular Cartilage Repair

Previous research has indicated that purified perivascular stem cells (PSCs) have increased chondrogenic potential compared to conventional mesenchymal stem cells (MSCs) derived in culture. This study aimed to develop an autologous large animal model for PSC transplantation and to specifically determine if implanted cells are retained in articular cartilage defects. Immunohistochemistry and fluorescence-activated cell sorting were used to ascertain the reactivity of anti-human and anti-ovine antibodies, which were combined and used to identify and isolate pericytes (CD34^-CD45^-CD146⁺) and adventitial cells (CD34⁺CD45^-CD146^-). The purified cells demonstrated osteogenic, adipogenic, and chondrogenic potential in culture. Autologous ovine PSCs (oPSCs) were isolated, cultured, and efficiently transfected using a green fluorescence protein (GFP) encoding lentivirus. The cells were implanted into articular cartilage defects on the medial femoral condyle using hydrogel and collagen membranes. Four weeks following implantation, the condyle was explanted and confocal laser scanning microscopy demonstrated the presence of oPSCs in the defect repaired with the hydrogel. These data suggest the testability in a large animal of native MSC autologous grafting, thus avoiding possible biases associated with xenotransplantation. Such a setting will be used in priority for indications in orthopedics, at first to model articular cartilage repair.

Concurrent Transitional Meningioma and Ceruminous Gland Adenocarcinoma in a Scottish Wildcat Hybrid (Felis silvestris)

The Scottish wildcat (Felis silvestris) is an iconic and endangered subpopulation of the European wildcat (F. silvestris silvestris). There is much research devoted to the ecology, genetics and conservation of this animal, but little published information on pathology and disease. The investigation and reporting of such information is vital to furthering understanding of the effects of hybridization, a factor that is crucial if we are to secure a future for the Scottish wildcat. This report describes the clinical presentation, gross post-mortem and histological findings in an elderly Scottish wildcat hybrid with concurrent transitional meningioma and ceruminous gland adenocarcinoma.

Early-life perturbations in glucocorticoid activity impacts on the structure, function and molecular composition of the adult zebrafish (Danio rerio) heart

BACKGROUND

Transient early-life perturbations in glucocorticoids (GC) are linked with cardiovascular disease risk in later life. Here the impact of early life manipulations of GC on adult heart structure, function and gene expression were assessed.

METHODS AND RESULTS

Zebrafish embryos were incubated in dexamethasone (Dex) or injected with targeted glucocorticoid receptor (GR) morpholino knockdown (GR Mo) over the first 120 h post fertilisation (hpf); surviving embryos (>90%) were maintained until adulthood under normal conditions. Cardiac function, heart histology and cardiac genes were assessed in embryonic (120 hpf) and adult (120 days post fertilisation (dpf)) hearts. GR Mo embryos (120 hpf) had smaller hearts with fewer cardiomyocytes, less mature striation pattern, reduced cardiac function and reduced levels of vmhc and igf mRNA compared with controls. GR Mo adult hearts were smaller with diminished trabecular network pattern, reduced expression of vmhc and altered echocardiographic Doppler flow compared to controls. Dex embryos had larger hearts at 120 hpf (Dex 107.2 ± 3.1 vs. controls 90.2 ± 1.1 μm, p < 0.001) with a more mature trabecular network and larger cardiomyocytes (1.62 ± 0.13 cells/μm vs control 2.18 ± 0.13 cells/μm, p < 0.05) and enhanced cardiac performance compared to controls. Adult hearts were larger (1.02 ± 0.07 μg/mg vs controls 0.63 ± 0.06 μg/mg, p = 0.0007), had increased vmhc and gr mRNA levels.

CONCLUSION

Perturbations in GR activity during embryonic development results in short and long-term alterations in the heart.

Deducing the stage of origin of Wilms' tumours from a developmental series of Wt1-mutant mice

Wilms' tumours, paediatric kidney cancers, are the archetypal example of tumours caused through the disruption of normal development. The genetically best-defined subgroup of Wilms' tumours is the group caused by biallelic loss of the WT1 tumour suppressor gene. Here, we describe a developmental series of mouse models with conditional loss of Wt1 in different stages of nephron development before and after the mesenchymal-to-epithelial transition (MET). We demonstrate that Wt1 is essential for normal development at all kidney developmental stages under study. Comparison of genome-wide expression data from the mutant mouse models with human tumour material of mutant or wild-type WT1 datasets identified the stage of origin of human WT1-mutant tumours, and emphasizes fundamental differences between the two human tumour groups due to different developmental stages of origin.

Summary: The comparison of different nephron-specific Wt1-knockout mouse models identifies the stage of origin of human WT1-mutant Wilms' tumours.

Heart on a plate: histological and functional assessment of isolated adult zebrafish hearts maintained in culture

The zebrafish is increasingly used for cardiovascular genetic and functional studies. We present a novel protocol to maintain and monitor whole isolated beating adult zebrafish hearts in culture for long-term experiments. Excised whole adult zebrafish hearts were transferred directly into culture dishes containing optimized L-15 Leibovitz growth medium and maintained for 5 days. Hearts were assessed daily using video-edge analysis of ventricle function using low power microscopy images. High-throughput histology techniques were used to assess changes in myocardial architecture and cell viability. Mean spontaneous Heart rate (HR, min⁻¹) declined significantly between day 0 and day 1 in culture (96.7±19.5 to 45.2±8.2 min⁻¹, mean±SD, p = 0.001), and thereafter declined more slowly to 27.6±7.2 min⁻¹ on day 5. Ventricle wall motion amplitude (WMA) did not change until day 4 in culture (day 0, 46.7±13.0 µm vs day 4, 16.9±1.9 µm, p = 0.08). Contraction velocity (CV) declined between day 0 and day 3 (35.6±14.8 vs 15.2±5.3 µms⁻¹, respectively, p = 0.012) while relaxation velocity (RV) declined quite rapidly (day 0, 72.5±11.9 vs day 1, 29.5±5.8 µms⁻¹, p = 0.03). HR and WMA responded consistently to isoproterenol from day 0 to day 5 in culture while CV and RV showed less consistent responses to beta-agonist. Cellular architecture and cross-striation pattern of cardiomyocytes remained unchanged up to day 3 in culture and thereafter showed significant deterioration with loss of striation pattern, pyknotic nuclei and cell swelling. Apoptotic markers within the myocardium became increasingly frequent by day 3 in culture. Whole adult zebrafish hearts can be maintained in culture-medium for up to 3 days. However, after day-3 there is significant deterioration in ventricle function and heart rate accompanied by significant histological changes consistent with cell death and loss of cardiomyocyte cell integrity. Further studies are needed to assess whether this preparation can be optimised for longer term survival.

Laser-targeted ablation of the zebrafish embryonic ventricle: a novel model of cardiac injury and repair

Background

While the adult zebrafish (Danio rerio) heart demonstrates a remarkable capacity for self-renewal following apical resection little is known about the response to injury in the embryonic heart.

Methods

Injury to the beating zebrafish embryo heart was induced by laser using a transgenic zebrafish expressing cardiomyocyte specific green fluorescent protein. Changes in ejection fraction (EF), heart rate (HR), and caudal vein blood flow (CVBF) assessed by video capture techniques were assessed at 2, 24 and 48 h post-laser. Change in total and mitotic ventricular cardiomyocyte number following laser injury was also assessed by counting respectively DAPI (VCt) and Phospho-histone H3 (VCm) positive nuclei in isolated hearts using confocal microscopy.

Results

Laser injury to the ventricle resulted in bradycardia and mild bleeding into the pericardium. At 2 h post-laser injury, there was a significant reduction in cardiac performance in lasered-hearts compared with controls (HR 117 ± 11 vs 167 ± 9 bpm, p ≤ 0.001; EF 14.1 ± 1.8 vs 20.1 ± 1.3%, p ≤ 0.001; CVBF 103 ± 15 vs 316 ± 13μms^− 1, p ≤ 0.001, respectively). Isolated hearts showed a significant reduction in VCt at 2 h post-laser compared to controls (195 ± 15 vs 238 ± 15, p ≤ 0.05). Histology showed necrosis and apoptosis (TUNEL assay) at the site of laser injury. At 24 h post-laser cardiac performance and VCt had recovered fully to control levels. Pretreatment with the cell-cycle inhibitor, aphidicolin, significantly inhibited functional recovery of the ventricle accompanied by a significant inhibition of cardiomyocyte proliferation.

Conclusions

Laser-targeted injury of the zebrafish embryonic heart is a novel and reproducible model of cardiac injury and repair suitable for pharmacological and molecular studies.

Dysregulation of hydrogen sulfide producing enzyme cystathionine γ-lyase contributes to maternal hypertension and placental abnormalities in preeclampsia

BACKGROUND

The exact etiology of preeclampsia is unknown, but there is growing evidence of an imbalance in angiogenic growth factors and abnormal placentation. Hydrogen sulfide (H2S), a gaseous messenger produced mainly by cystathionine γ-lyase (CSE), is a proangiogenic vasodilator. We hypothesized that a reduction in CSE activity may alter the angiogenic balance in pregnancy and induce abnormal placentation and maternal hypertension.

METHODS AND RESULTS

Plasma levels of H2S were significantly decreased in women with preeclampsia (P<0.01), which was associated with reduced placental CSE expression as determined by real-time polymerase chain reaction and immunohistochemistry. Inhibition of CSE activity by DL-propargylglycine reduced placental growth factorproduction from first-trimester (8-12 weeks gestation) human placental explants and inhibited trophoblast invasion in vitro. Knockdown of CSE in human umbilical vein endothelial cells by small-interfering RNA increased the release of soluble fms-like tyrosine kinase-1 and soluble endoglin, as assessed by enzyme-linked immunosorbent assay, whereas adenoviral-mediated CSE overexpression in human umbilical vein endothelial cells inhibited their release. Administration of DL-propargylglycine to pregnant mice induced hypertension and liver damage, promoted abnormal labyrinth vascularization in the placenta, and decreased fetal growth. Finally, a slow-releasing H2S-generating compound, GYY4137, inhibited circulating soluble fms-like tyrosine kinase-1 and soluble endoglin levels and restored fetal growth in mice that was compromised by DL-propargylglycine treatment, demonstrating that the effect of CSE inhibitor was attributable to inhibition of H2S production.

CONCLUSIONS

These results imply that endogenous H2S is required for healthy placental vasculature and that a decrease in CSE/H2S activity may contribute to the pathogenesis of preeclampsia.

Epithelial-mesenchymal transition (EMT) of renal tubular cells in canine glomerulonephritis

Tubulo-interstitial fibrosis in dogs may result from primary injury to the interstitium or develop secondary to other renal diseases. As in human renal pathology, tubular epithelial cells (TEC) are believed to actively participate in the mechanisms of renal fibrosis. In this study, we examined the changes in the tubular epithelial component in two specific canine diseases. Immunohistochemistry showed the expression of the epithelial marker cytokeratin, the smooth muscle marker alpha-SMA, the mesenchymal marker vimentin and PCNA in 20 dogs with membranous glomerulonephritis and membrano-proliferative glomerulonephritis. Results showed that the loss of the epithelial marker in TEC was directly correlated to the grade of tubulo-interstitial disease present and independent of the type of glomerulonephritis. Varying degrees of vimentin positivity were detected in tubular epithelium in areas of inflammation, and low numbers of scattered alpha-SMA-positive cells were also observed. Immunohistochemistry showed that epithelial tubular cells lose their cytokeratin staining characteristics and transdifferentiate into cells exhibiting key mesenchymal immunophenotypic feature of vimentin-positive staining in both diseases investigated. The integrity of the tubular basement membrane is likely to be fundamental in maintaining the epithelial phenotype of TEC. Animal models provide opportunities for investigating the pathogenesis of renal fibrosis in humans.

Morphological and functional effects of 16,16-dimethyl-prostaglandin-E2 on mucosal adaptation after massive distal small bowel resection in the rat

The ability of 16,16-dimethyl-prostaglandin-E2 (PGE) to augment mucosal adaptation 14 days after a 70% distal small bowel resection in the rat was evaluated. In resected (R) and sham operated (S) animals, subcutaneous PGE 75 mg/kg, 2 X/day, induced significant (p less than 0.05) increases in mucosal protein, DNA, and disaccharidase concentrations per centimetre of bowel. The respective per cent increases in the residual proximal small intestine compared with their respective untreated controls were: protein, R = 60%, S = 66%; DNA, R = 69%, S = 29%; maltase, R = 57%, S = 5%. The uptake of leucine by intestinal rings was significantly higher (50%) in the PGE treated group at a concentration of 2 mmol/l of substrate, while the uptake of glucose was similar in all groups. The drug appears to be an effective agent in stimulating morphological and functional adaptation after massive distal small bowel resection.