PTEN downregulation in adipocytes promotes inflammation of adipose tissue

Background and aims: The phosphoinositide phosphatase PTEN is a potent tumor suppressor and a regulator of insulin sensitivity in peripheral tissues. In adipocytes, experimental alterations of PTEN expression modulate the sensitivity of these cells to insulin. However, virtually nothing is known about the pathophysiological regulation of endogenous PTEN in adipose tissue. Herein, we investigated in vivo and in vitro whether alterations of PTEN expression in adipocytes are associated with the metabolic syndrome and what are the functional outcomes of dysregulated PTEN expression/activity. Materials and methods: PTEN expression was examined in vivo in adipose tissue of rats and human with the metabolic syndrome. Metabolic factors mediating dysregulation of PTEN expression in adipocytes and the subsequent effects on the physiology of these cells were investigated in vitro using human CHUB-S7 preadipocytes. Results: We demonstrated that PTEN is downregulated, both at the mRNA and protein levels, in adipose tissue of diabetic/obese ZDF rats and in subcutaneous adipose tissue of obese human patients. PTEN downregulation correlated with degradation of IκBα and hyperactivation of NF-κB, a transcription factor previously described to modulate PTEN expression. The expression of SHIP2, another PtdIns(3,4,5)P3 phosphatase involved in the control of insulin sensitivity and the development of obesity, was not altered. In vitro analyses using differentiated human CHUB-S7 preadipocytes showed that PTEN downregulation is not triggered by high concentrations of glucose or fatty acids. In contrast, the pro-inflammatory cytokines IL-1α and TNFα, significantly downregulate PTEN expression. Consistent with the IL1α-dependent PTEN downregulation, long-term incubation of CHUB-S7 cells with IL-1α potentiates insulin-induced Akt and ERK1/2 signaling. We finally showed that PTEN downregulation in CHUB-S7 preadipocytes by PTEN siRNAs induced an increased secretion of the pro-inflammatory cytokines IL-1β, IL-6 and TNFα. Conclusion: Taken together, these data indicate that PTEN expression is downregulated in adipose tissue of obese/diabetic subjects, potentially via cytokine- mediated activation of the NF-κB pathway. PTEN downregulation in adipocytes might in turn worsen adipose tissue inflammation through a vicious circle by further stimulating the secretion of pro-inflammatory cytokines.

Altering α-dystroglycan receptor affinity of LCMV pseudotyped lentivirus yields unique cell and tissue tropism.

BACKGROUND: The envelope glycoprotein of lymphocytic choriomeningitis virus (LCMV) can efficiently pseudotype lentiviral vectors. Some strains of LCMV exploit high affinity interactions with α-dystroglycan (α-DG) to bind to cell surfaces and subsequently fuse in low pH endosomes. LCMV strains with low α-DG affinity utilize an unknown receptor and display unique tissue tropisms. We pseudotyped non-primate feline immunodeficiency virus (FIV) vectors using LCMV derived glycoproteins with high or low affinity to α-DG and evaluated their properties in vitro and in vivo. METHODS: We pseudotyped FIV with the LCMV WE54 strain envelope glycoprotein and also engineered a point mutation in the WE54 envelope glycoprotein (L260F) to diminish α-DG affinity and direct binding to alternate receptors. We hypothesized that this change would alter in vivo tissue tropism and enhance gene transfer to neonatal animals. RESULTS: In mice, hepatic α- and β-DG expression was greatest at the late gestational and neonatal time points. When displayed on the surface of the FIV lentivirus the WE54 L260F mutant glycoprotein bound weakly to immobilized α-DG. Additionally, LCMV WE54 pseudotyped FIV vector transduction was neutralized by pre-incubation with soluble α-DG, while the mutant glycoprotein pseudotyped vector was not. In vivo gene transfer in adult mice with either envelope yielded low transduction efficiencies in hepatocytes following intravenous delivery. In marked contrast, neonatal gene transfer with the LCMV envelopes, and notably with the FIV-L260F vector, conferred abundant liver and lower level cardiomyocyte transduction as detected by luciferase assays, bioluminescent imaging, and β-galactosidase staining. CONCLUSIONS: These results suggest that a developmentally regulated receptor for LCMV is expressed abundantly in neonatal mice. LCMV pseudotyped vectors may have applications for neonatal gene transfer. ABBREVIATIONS: Armstrong 53b (Arm53b); baculovirus Autographa californica GP64 (GP64); charge-coupled device (CCD); dystroglycan (DG); feline immunodeficiency virus (FIV); glycoprotein precursor (GP-C); firefly luciferase (Luc); lymphocytic choriomeningitis virus (LCMV); nuclear targeted β-galactosidase (ntLacZ); optical density (OD); PBS/0.1% (w/v) Tween-20 (PBST); relative light units (RLU); Rous sarcoma virus (RSV); transducing units per milliliter (TU/ml); vesicular stomatitis virus (VSV-G); wheat germ agglutinin (WGA); 50% reduction in binding (C50).

UVB-Induced Skin Inflammation and Cutaneous Tissue Injury Is Dependent on the MHC Class I-Like Protein, CD1d.

CD1d is a major histocompatibility complex class 1-like molecule that regulates the function and development of natural killer T (NKT) cells. Previously, we identified a critical role for the CD1d-NKT cell arm of innate immunity in promoting the development of UVB-induced p53 mutations, immune suppression, and skin tumors. Sunburn, an acute inflammatory response to UVB-induced cutaneous tissue injury, represents a clinical marker for non-melanoma skin cancer (NMSC) risk. However, the innate immune mechanisms controlling sunburn development are not considered relevant in NMSC etiology, and remain poorly investigated. Here we found that CD1d knockout (CD1d(-/-)) mice resist UVB-induced cutaneous tissue injury and inflammation compared with wild-type (WT) mice. This resistance was coupled with a faster epithelial tissue healing response. In contrast, the skins of UVB-irradiated invariant NKT cell-knockout (Jα18(-/-)) and NKT cell-deficient (TCRα(-/-)) mice, which express CD1d but are deficient in CD1d-dependent NKT cells, exhibited as much cutaneous tissue injury and inflammation as WT mice. In the absence of NKT cells, CD1d-deficient keratinocytes, dendritic cells, and macrophages exhibited diminished basal and stress-induced levels of pro-inflammatory mediators. Thus, our findings identify an essential role for CD1d in promoting UVB-induced cutaneous tissue injury and inflammation. They also suggest sunburn and NMSC etiologies are immunologically linked.

Apparent versus true gene expression changes of three hypoxia-related genes in autopsy derived tissue and the importance of normalisation.

The aim of our work was to show how a chosen normal-isation strategy can affect the outcome of quantitative gene expression studies. As an example, we analysed the expression of three genes known to be upregulated under hypoxic conditions: HIF1A, VEGF and SLC2A1 (GLUT1). Raw RT-qPCR data were normalised using two different strategies: a straightforward normalisation against a single reference gene, GAPDH, using the 2(-ΔΔCt) algorithm and a more complex normalisation against a normalisation factor calculated from the quantitative raw data from four previously validated reference genes. We found that the two different normalisation strategies revealed contradicting results: normalising against a validated set of reference genes revealed an upregulation of the three genes of interest in three post-mortem tissue samples (cardiac muscle, skeletal muscle and brain) under hypoxic conditions. Interestingly, we found a statistically significant difference in the relative transcript abundance of VEGF in cardiac muscle between donors who died of asphyxia versus donors who died from cardiac death. Normalisation against GAPDH alone revealed no upregulation but, in some instances, a downregulation of the genes of interest. To further analyse this discrepancy, the stability of all reference genes used were reassessed and the very low expression stability of GAPDH was found to originate from the co-regulation of this gene under hypoxic conditions. We concluded that GAPDH is not a suitable reference gene for the quantitative analysis of gene expression in hypoxia and that validation of reference genes is a crucial step for generating biologically meaningful data.

Mutations in B3GALT6, which encodes a glycosaminoglycan linker region enzyme, cause a spectrum of skeletal and connective tissue disorders.

Proteoglycans (PGs) are a major component of the extracellular matrix in many tissues and function as structural and regulatory molecules. PGs are composed of core proteins and glycosaminoglycan (GAG) side chains. The biosynthesis of GAGs starts with the linker region that consists of four sugar residues and is followed by repeating disaccharide units. By exome sequencing, we found that B3GALT6 encoding an enzyme involved in the biosynthesis of the GAG linker region is responsible for a severe skeletal dysplasia, spondyloepimetaphyseal dysplasia with joint laxity type 1 (SEMD-JL1). B3GALT6 loss-of-function mutations were found in individuals with SEMD-JL1 from seven families. In a subsequent candidate gene study based on the phenotypic similarity, we found that B3GALT6 is also responsible for a connective tissue disease, Ehlers-Danlos syndrome (progeroid form). Recessive loss-of-function mutations in B3GALT6 result in a spectrum of disorders affecting a broad range of skeletal and connective tissues characterized by lax skin, muscle hypotonia, joint dislocation, and spinal deformity. The pleiotropic phenotypes of the disorders indicate that B3GALT6 plays a critical role in a wide range of biological processes in various tissues, including skin, bone, cartilage, tendon, and ligament.

Fractures du calcanéum: du traumatisme aux séquelles [Fractures of the calcaneus: the injury and its sequelae]

The calcaneus gives shape to the heel. Its special position places it in direct contact with the floor, upon which rests the weight of the body. It assures the transition between the vertical skeleton and horizontal surface of the foot, thus permitting ambulation. The calcaneus is subjected to high physical stress, yet at the same time its complex articulating surfaces permit fine adaptation to the ground. Fractures of the calcaneus result from a high energy injury, usually a fall from a height. The treatment of such fractures poses difficult problems. The functional sequelae of the injury may be severe, prolonged, and frequently results in a permanent disability. This is due not only to the type of fracture, but the orthopaedic management as well. Careful evaluation of the patient, fracture pattern, soft tissue condition, and treatment modalities is obligatory to achieve the optimal result.

Ectopic lymphoid-organ development occurs through interleukin 7-mediated enhanced survival of lymphoid-tissue-inducer cells.

Development of Peyer's patches and lymph nodes requires the interaction between CD4+ CD3- IL-7Ralpha+ lymphoid-tissue inducer (LTi) and VCAM-1+ organizer cells. Here we showed that by promoting their survival, enhanced expression of interleukin-7 (IL-7) in transgenic mice resulted in accumulation of LTi cells. With increased IL-7 availability, de novo formation of VCAM-1+ Peyer's patch anlagen occurred along the entire fetal gut resulting in a 5-fold increase in Peyer's patch numbers. IL-7 overexpression also led to formation of multiple organized ectopic lymph nodes and cecal patches. After immunization, ectopic lymph nodes developed normal T cell-dependent B cell responses and germinal centers. Mice overexpressing IL-7 but lacking either RORgamma, a factor required for LTi cell generation, or lymphotoxin alpha1beta2 had neither Peyer's patches nor ectopic lymph nodes. Therefore, by controlling LTi cell numbers, IL-7 can regulate the formation of both normal and ectopic lymphoid organs.

Blockade of the renin-angiotensin system and renal tissue oxygenation as measured with BOLD-MRI in patients with type 2 diabetes.

AIM: To assess whether blockade of the renin-angiotensin system (RAS), a recognized strategy to prevent the progression of diabetic nephropathy, affects renal tissue oxygenation in type 2 diabetes mellitus (T2DM) patients. METHODS: Prospective randomized 2-way cross over study; T2DM patients with (micro)albuminuria and/or hypertension underwent blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) at baseline, after one month of enalapril (20mgqd), and after one month of candesartan (16mgqd). Each BOLD-MRI was performed before and after the administration of furosemide. The mean R2* (=1/T2*) values in the medulla and cortex were calculated, a low R2* indicating high tissue oxygenation. RESULTS: Twelve patients (mean age: 60±11 years, eGFR: 62±22ml/min/1.73m(2)) completed the study. Neither chronic enalapril nor candesartan intake modified renal cortical or medullary R2* levels. Furosemide significantly decreased cortical and medullary R2* levels suggesting a transient increase in renal oxygenation. Medullary R2* levels correlated positively with urinary sodium excretion and systemic blood pressure, suggesting lower renal oxygenation at higher dietary sodium intake and blood pressure; cortical R2* levels correlated positively with glycemia and HbA1c. CONCLUSION: RAS blockade does not seem to increase renal tissue oxygenation in T2DM hypertensive patients. The response to furosemide and the association with 24h urinary sodium excretion emphasize the crucial role of renal sodium handling as one of the main determinants of renal tissue oxygenation.

Bayesian Markov-chain-Monte-Carlo inversion of time-lapse cross hole ground-penetrating radar data to characterize the vadose zone at the Arrenaes field site, Denmark

The ground-penetrating radar (GPR) geophysical method has the potential to provide valuable information on the hydraulic properties of the vadose zone because of its strong sensitivity to soil water content. In particular, recent evidence has suggested that the stochastic inversion of crosshole GPR traveltime data can allow for a significant reduction in uncertainty regarding subsurface van Genuchten-Mualem (VGM) parameters. Much of the previous work on the stochastic estimation of VGM parameters from crosshole GPR data has considered the case of steady-state infiltration conditions, which represent only a small fraction of practically relevant scenarios. We explored in detail the dynamic infiltration case, specifically examining to what extent time-lapse crosshole GPR traveltimes, measured during a forced infiltration experiment at the Arreneas field site in Denmark, could help to quantify VGM parameters and their uncertainties in a layered medium, as well as the corresponding soil hydraulic properties. We used a Bayesian Markov-chain-Monte-Carlo inversion approach. We first explored the advantages and limitations of this approach with regard to a realistic synthetic example before applying it to field measurements. In our analysis, we also considered different degrees of prior information. Our findings indicate that the stochastic inversion of the time-lapse GPR data does indeed allow for a substantial refinement in the inferred posterior VGM parameter distributions compared with the corresponding priors, which in turn significantly improves knowledge of soil hydraulic properties. Overall, the results obtained clearly demonstrate the value of the information contained in time-lapse GPR data for characterizing vadose zone dynamics.

The JNK inhibitor XG-102 protects from ischemic damage with delayed intravenous administration also in the presence of recombinant tissue plasminogen activator.

BACKGROUND: XG-102 (formerly D-JNKI1), a TAT-coupled dextrogyre peptide which selectively inhibits the c-Jun N-terminal kinase, is a powerful neuroprotectant in mouse models of middle cerebral artery occlusion (MCAo) with delayed intracerebroventricular injection. We aimed to determine whether this neuroprotection could also be achieved by intravenous injection of XG-102, which is a more feasible approach for future use in stroke patients. We also tested the compatibility of the compound with recombinant tissue plasminogen activator (rtPA), commonly used for intravenous thrombolysis and known to enhance excitotoxicity. METHODS: Male ICR-CD1 mice were subjected to a 30-min-suture MCAo. XG-102 was injected intravenously in a single dose, 6 h after ischemia. Hippocampal slice cultures were subjected to oxygen (5%) and glucose (1 mM) deprivation for 30 min. rtPA was added after ischemia and before XG-102 administration, both in vitro and in vivo. RESULTS: The lowest intravenous dose achieving neuroprotection was 0.0003 mg/kg, which reduced the infarct volume after 48 h from 62 +/- 19 mm(3) (n = 18) for the vehicle-treated group to 18 +/- 9 mm(3) (n = 5, p < 0.01). The behavioral outcome was also significantly improved at two doses. Addition of rtPA after ischemia enhanced the ischemic damage both in vitro and in vivo, but XG-102 was still able to induce a significant neuroprotection. CONCLUSIONS: A single intravenous administration of XG-102 several hours after ischemia induces a powerful neuroprotection. XG-102 protects from ischemic damage in the presence of rtPA. The feasibility of systemic administration of this promising compound and its compatibility with rtPA are important steps for its development as a drug candidate in ischemic stroke.

Study of the impact of tissue density heterogeneities on 3-dimensional abdominal dosimetry: comparison between dose kernel convolution and direct monte carlo methods.

Dose kernel convolution (DK) methods have been proposed to speed up absorbed dose calculations in molecular radionuclide therapy. Our aim was to evaluate the impact of tissue density heterogeneities (TDH) on dosimetry when using a DK method and to propose a simple density-correction method. METHODS: This study has been conducted on 3 clinical cases: case 1, non-Hodgkin lymphoma treated with (131)I-tositumomab; case 2, a neuroendocrine tumor treatment simulated with (177)Lu-peptides; and case 3, hepatocellular carcinoma treated with (90)Y-microspheres. Absorbed dose calculations were performed using a direct Monte Carlo approach accounting for TDH (3D-RD), and a DK approach (VoxelDose, or VD). For each individual voxel, the VD absorbed dose, D(VD), calculated assuming uniform density, was corrected for density, giving D(VDd). The average 3D-RD absorbed dose values, D(3DRD), were compared with D(VD) and D(VDd), using the relative difference Δ(VD/3DRD). At the voxel level, density-binned Δ(VD/3DRD) and Δ(VDd/3DRD) were plotted against ρ and fitted with a linear regression. RESULTS: The D(VD) calculations showed a good agreement with D(3DRD). Δ(VD/3DRD) was less than 3.5%, except for the tumor of case 1 (5.9%) and the renal cortex of case 2 (5.6%). At the voxel level, the Δ(VD/3DRD) range was 0%-14% for cases 1 and 2, and -3% to 7% for case 3. All 3 cases showed a linear relationship between voxel bin-averaged Δ(VD/3DRD) and density, ρ: case 1 (Δ = -0.56ρ + 0.62, R(2) = 0.93), case 2 (Δ = -0.91ρ + 0.96, R(2) = 0.99), and case 3 (Δ = -0.69ρ + 0.72, R(2) = 0.91). The density correction improved the agreement of the DK method with the Monte Carlo approach (Δ(VDd/3DRD) < 1.1%), but with a lesser extent for the tumor of case 1 (3.1%). At the voxel level, the Δ(VDd/3DRD) range decreased for the 3 clinical cases (case 1, -1% to 4%; case 2, -0.5% to 1.5%, and -1.5% to 2%). No more linear regression existed for cases 2 and 3, contrary to case 1 (Δ = 0.41ρ - 0.38, R(2) = 0.88) although the slope in case 1 was less pronounced. CONCLUSION: This study shows a small influence of TDH in the abdominal region for 3 representative clinical cases. A simple density-correction method was proposed and improved the comparison in the absorbed dose calculations when using our voxel S value implementation.

Tissue-specific opposing functions of the inflammasome adaptor ASC in the regulation of epithelial skin carcinogenesis.

A chronic inflammatory microenvironment favors tumor progression through molecular mechanisms that are still incompletely defined. In inflammation-induced skin cancers, IL-1 receptor- or caspase-1-deficient mice, or mice specifically deficient for the inflammasome adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD) in myeloid cells, had reduced tumor incidence, pointing to a role for IL-1 signaling and inflammasome activation in tumor development. However, mice fully deficient for ASC were not protected, and mice specifically deficient for ASC in keratinocytes developed more tumors than controls, suggesting that, in contrast to its proinflammatory role in myeloid cells, ASC acts as a tumor-suppressor in keratinocytes. Accordingly, ASC protein expression was lost in human cutaneous squamous cell carcinoma, but not in psoriatic skin lesions. Stimulation of primary mouse keratinocytes or the human keratinocyte cell line HaCaT with UVB induced an ASC-dependent phosphorylation of p53 and expression of p53 target genes. In HaCaT cells, ASC interacted with p53 at the endogenous level upon UVB irradiation. Thus, ASC in different tissues may influence tumor growth in opposite directions: it has a proinflammatory role in infiltrating cells that favors tumor development, but it also limits keratinocyte proliferation in response to noxious stimuli, possibly through p53 activation, which helps suppressing tumors.

Tissue oxygenation and hemodynamic response to NO synthase inhibition in septic shock.

The objective of the study was to evaluate the tissue oxygenation and hemodynamic effects of NOS inhibition in clinical severe septic shock. Eight patients with septic shock refractory to volume loading and high level of adrenergic support were prospectively enrolled in the study. Increasing doses of NOS inhibitors [N(G)-nitro-L-arginine-methyl ester (L-NAME) or N(G)-monomethyl-L-arginine (L-NMMA)] were administered as i.v. bolus until a peak effect = 10 mmHg on mean blood pressure was obtained or until side effects occurred. If deemed clinically appropriate, a continuous infusion of L-NAME was instituted and adrenergic support weaning attempted. The bolus administration of NOS inhibitors transiently increased mean blood pressure by 10 mm Hg in all patients. Seven out of eight patients received an L-NAME infusion, associated over 24 h with a progressive decline in cardiac index (P < 0.001) and an increase in systemic vascular resistance (P < 0.01). Partial or total adrenergic support weaning was rapidly possible in 6/8 patients. Oxygen transport decreased (P < 0.001), but oxygen consumption remained unchanged in those patients in whom it could be measured by indirect calorimetry (5/8). Blood lactate and the difference between tonometric gastric and arterial PCO2 remained unchanged. There were 4/8 ICU survivors. We conclude that nitric oxide synthase inhibition in severe septic shock was followed with a progressive correction of the vasoplegic hemodynamic disturbances with finally normalization of cardiac output and systemic vascular resistances without any demonstrable deterioration in tissue oxygenation.