Adenine-induced chronic renal failure in rats decreases aortic relaxation rate and alters expression of proteins involved in vascular smooth muscle calcium handling.

AIM: Rats with adenine-induced chronic renal failure (A-CRF) develop a reduced rate of relaxation of the thoracic aorta. The aim of this study was to elucidate the mechanisms underlying this abnormality. METHODS: Male Sprague Dawley rats received either chow containing adenine or were pair-fed with normal chow (controls). After 8-14 weeks, arterial function was analysed ex vivo using wire myography and the expression of proteins involved in vascular smooth muscle excitation-contraction coupling in the thoracic aorta was analysed. RESULTS: The rate of relaxation following washout of KCl was reduced in A-CRF rats vs. controls in the thoracic aorta (P < 0.01), abdominal aorta (P < 0.05), and common carotid artery (P < 0.05), but not in the common femoral artery. Relaxation rates of thoracic aortas increased (P < 0.01), but were not normalized, in response to washout of KCl with Ca2+ -free buffer. Microarray and qRT-PCR analyses of genes involved in excitation-contraction coupling identified 10 genes, which showed significantly altered expression in A-CRF thoracic aortas. At the protein level, the α2 subunit of the Na,K-ATPase (P < 0.001) and SERCA2 (P < 0.05) was significantly downregulated, whereas stromal interaction molecule 1 and calsequestrin-1 and calsequestrin-2 were significantly upregulated (P < 0.05). CONCLUSIONS: Rats with A-CRF show a marked alteration in relaxation of larger conduit arteries localized proximal to the common femoral artery. This abnormality may be caused by reduced cytosolic Ca2+ clearance in vascular smooth muscle cells secondary to dysregulation of proteins crucially involved in this process.

Differential coexpression analysis of obesity-associated networks in human subcutaneous adipose tissue.

OBJECTIVE: To use a unique obesity-discordant sib-pair study design to combine differential expression analysis, expression quantitative trait loci (eQTLs) mapping and a coexpression regulatory network approach in subcutaneous human adipose tissue to identify genes relevant to the obese state. STUDY DESIGN: Genome-wide transcript expression in subcutaneous human adipose tissue was measured using Affymetrix U133 Plus 2.0 microarrays (Affymetrix, Santa Clara, CA, USA), and genome-wide genotyping data was obtained using an Applied Biosystems (Applied Biosystems; Life Technologies, Carlsbad, CA, USA) SNPlex linkage panel. SUBJECTS: A total of 154 Swedish families ascertained through an obese proband (body mass index (BMI) >30 kg m(-2)) with a discordant sibling (BMI>10 kg m(-2) less than proband). RESULTS: Approximately one-third of the transcripts were differentially expressed between lean and obese siblings. The cellular adhesion molecules (CAMs) KEGG grouping contained the largest number of differentially expressed genes under cis-acting genetic control. By using a novel approach to contrast CAMs coexpression networks between lean and obese siblings, a subset of differentially regulated genes was identified, with the previously GWAS obesity-associated neuronal growth regulator 1 (NEGR1) as a central hub. Independent analysis using mouse data demonstrated that this finding of NEGR1 is conserved across species. CONCLUSION: Our data suggest that in addition to its reported role in the brain, NEGR1 is also expressed in subcutaneous adipose tissue and acts as a central 'hub' in an obesity-related transcript network.

In humans the adiponectin receptor R2 is expressed predominantly in adipose tissue and linked to the adipose tissue expression of MMIF-1.

In this study, the regional adipose tissue-adiponectin (AT-ADN) and adiponectin receptor (R1 and R2) expression and their relation with metabolic parameters, circulating and AT-derived cytokine expressions were compared. Paired subcutaneous adipose tissue (SCAT) and visceral adipose tissue (VAT) were taken from 18 lean and 39 obese humans, AT-mRNA expression of adipokines analysed by RT-PCR and corresponding serum levels by enzyme-linked immunosorbent assay (ELISA). R1 and R2 adipocyte expression was compared with 17 other human tissues. ADN-gene expression was lower in VAT than SCAT [mean (SD) 1.54 (1.1) vs. 2.84 (0.87); p < 0.001], and lower in obese subjects (VAT : p = 0.01;SCAT : p < 0.001). SCAT-ADN correlated positively with serum ADN (r = 0.33;p = 0.036) but not VAT-ADN. AT expressions of ADN and macrophage migration inhibiting factor (MMIF), IL18 and cluster of differentiation factor 14 (CD14) in both depots showed inverse correlations. R1 and R2 were expressed ubiquitously and R2 highest in SCAT, and this is much higher (x100) than R1 (x100). R expression was similar in lean and obese subjects and unrelated to the metabolic syndrome, however, receptors correlated with VAT-MMIF (R 1: r = 0.4;p = 0.008;R 2: r = 0.35,p = 0.02) and SCAT-MMIF expression (R 2: r = 0.43;p = 0.004). Unlike ADN, its receptors are expressed in many human tissues. Human R2 expression is not highest in the liver but in AT where it is associated with MMIF expression. The adiponectin-dependent insulin-sensitizing action of thiazolidinediones is thus probably to differ amongst species with weaker effects on the human liver.

Differences in associations between HSD11B1 gene expression and metabolic parameters in subjects with and without impaired glucose homeostasis.

AIMS: Animal studies indicate a role for 11beta-hydroxysteroid dehydrogenase type 1 (HSD11B1) in the development of obesity. The association to glucose homeostasis is less clear. We investigated the relationship between HSD11B1 mRNA levels in adipose tissue and in skeletal muscle and anthropometric and metabolic measurements in humans with and without impaired glucose homeostasis. METHODS: Twelve obese subjects with impaired glucose homeostasis (MetS+) and 12 obese controls (MetS-) received a Very Low Calorie Diet for 16 weeks and adipose tissue biopsies, blood samples and measurements were obtained. In a second cohort, skeletal muscle biopsies, blood samples and measurements were obtained from 18 subjects with type 2 diabetes (T2DM) and 17 subjects with normal glucose tolerance (NGT). Gene expression was measured by DNA microarray in both studies. RESULTS: HSD11B1 mRNA levels were reduced during diet, and anthropometric measurements and metabolic parameters were associated with HSD11B1 mRNA levels in the MetS- group. However, in the MetS+ group these associations were lost or in opposite direction. This difference was also observed in skeletal muscle between T2DM and NGT. CONCLUSIONS: HSD11B1 mRNA levels are associated with metabolic parameters and anthropometric measurements in subjects with normal glucose homeostasis but not in subjects with impaired glucose homeostasis.

DPP-IV inhibition enhances the antilipolytic action of NPY in human adipose tissue.

CONTEXT: Dipeptidyl peptidase IV (DPP-IV) inactivates the incretin hormone glucagon-like peptide. It can also affect the orexigenic hormone neuropeptide Y (NPY(1-36)) which is truncated by DPP-IV to NPY(3-36), as a consequence NPY's affinity changes from receptor Y1, which mediates the antilipolytic function of NPY, to other NPY receptors. Little is known whether DPP-IV inhibitors for the treatment of type 2 diabetic (T2DM) patients could influence these pathways. AIMS: To investigate the in vitro effects of NPY with DPP-IV inhibition in isolated abdominal subcutaneous (AbdSc) adipocytes on fat metabolism, and assessment of NPY receptor and DPP-IV expression in adipose tissue (AT). METHODS: Ex vivo human AT was taken from women undergoing elective surgery (body mass index: 27.5 (mean +/- s.d.) +/- 5 kg/m2, age: 43.7 +/- 10 years, n = 36). Isolated AbdSc adipocytes were treated with human recombinant (rh)NPY (1-100 nM) with and without DPP-IV inhibitor (1 M); glycerol release and tissue distribution of DPP-IV, Y1 and Y5 messenger RNA (mRNA) were measured and compared between lean and obese subjects. RESULTS AND CONCLUSION: rhNPY reduced glycerol release, an effect that was further enhanced by co-incubation with a DPP-IV inhibitor [control: 224 (mean +/- s.e.) +/- 37 micromol/l; NPY, 100 nM: 161 +/- 27 micromol/l**; NPY 100 nM/DPP-IV inhibitor, 1 M: 127 +/- 14 micromol/l**; **p < 0.01, n = 14]. DPP-IV was expressed in AbdSc AT and omental AT with relative DPP-IV mRNA expression lower in AbdSc AT taken from obese [77 +/- 6 signal units (SU)] vs. lean subjects (186 +/- 29 SU*, n = 10). Y1 was predominantly expressed in fat and present in all fat depots but higher in obese subjects, particularly the AbdSc AT-depot (obese: 1944 +/- 111 SU vs. lean: 711 +/- 112 SU**, n = 10). NPY appears to be regulated by AT-derived DPP-IV. DPP-IV inhibitors augment the antilipolytic effect of NPY in AT. Further studies are required to show whether this explains the lack of weight loss in T2DM patients treated with DPP-IV inhibitors.

Increased expression of aquaporin 3 in atopic eczema.

BACKGROUND: Dry skin in atopic eczema depends on increased water loss. The mechanisms behind this are poorly understood. The aim of this work was to identify genes that may contribute to water loss in eczema. METHODS: Affymetrix DNA microarrays U133A were used to analyse gene expression in skin biopsies from 10 patients with atopic eczema and 10 healthy controls. RESULTS: DNA microarray analysis showed up-regulation of 262 genes and down-regulation of 129 genes in atopic eczema. The known functions of these genes were analysed using Gene Ontology to identify genes that could contribute to increased water loss. This led to identification of aquaporin 3 (AQP3), which has a key role in hydrating healthy epidermis. Increased expression of AQP3 was found in eczema compared with healthy skin. This was confirmed with real-time polymerase chain reaction (P<0.001). In healthy skin, epidermal AQP3 immunoreactivity was weak and mainly found in the stratum basale. A gradient was formed with decreasing AQP3 staining in the lower layers of the stratum spinosum. By contrast, in acute and chronic atopic eczema strong AQP3 staining was found in both the stratum basale and the stratum spinosum. CONCLUSIONS: Aquaporin 3 is the predominant aquaporin in human skin. Increased expression and altered cellular distribution of AQP3 is found in eczema and this may contribute to water loss.

A network-based analysis of allergen-challenged CD4+ T cells from patients with allergic rhinitis.

We performed a network-based analysis of DNA microarray data from allergen-challenged CD4(+) T cells from patients with seasonal allergic rhinitis. Differentially expressed genes were organized into a functionally annotated network using the Ingenuity Knowledge Database, which is based on manual review of more than 200,000 publications. The main function of this network is the regulation of lymphocyte apoptosis, a role associated with several genes of the tuber necrosis factor superfamily. The expression of TNFRSF4, one of the genes in this family, was found to be 48 times higher in allergen-challenged cells than in diluent-challenged cells. TNFRSF4 is known to inhibit apoptosis and to enhance Th2 proliferation. Examination of a different material of allergen-stimulated peripheral blood mononuclear cells showed a higher number of interleukin-4(+) type 2 CD4(+) T (Th2) cells in patients than in controls (P<0.01), as well as a higher number of non-apoptotic Th2 cells in patients (P<0.01). The number of Th2 cells expressing TNFRSF4, TNFSF7 and TNFRSF1B was also significantly higher in patients. Treatment with anti-TNFSF4 resulted in a significantly decreased number of Th2 cells (P<0.05). A logical inference from all this is that the proliferation of allergen-challenged Th2 cells is associated with a decreased apoptosis of Th2 cells and an increase in TNFRSF4 signalling.

Increased levels of acylation-stimulating protein in interleukin-6-deficient (IL-6(-/-)) mice.

IL-6-deficient (IL-6(-/-)) mice develop obesity at 6-7 months of age. To elucidate the mechanisms of this mature-onset obesity, global gene expression profiles of 3-month-old preobese IL-6(-/-) were compared with those of IL-6(+/+) mice using DNA arrays. Genes that were up-regulated in IL-6(-/-) mice included the factors transthyretin and properdin in white adipose tissue and adipsin in muscle. These factors have been shown to influence the formation of acylation-stimulating protein (ASP), a cleavage product of complement C3. ASP stimulates the synthesis of triacylglycerol in adipocytes, and ASP-deficient mice are resistant to diet-induced obesity. In line with the increases in transthyretin, properdin, and adipsin, ASP levels in serum were increased by 31-54% in IL-6(-/-) compared with IL-6(+/+) mice. Furthermore, IL-6 replacement treatment in IL-6(-/-) mice decreased ASP levels significantly by 25-60%. In conclusion, ASP levels are increased in preobese IL-6(-/-) mice. This increase may result in increased triacylglycerol formation and uptake in IL-6(-/-) adipocytes and thereby contribute to the development of obesity in IL-6(-/-) mice.

DNA microarrays to study gene expression in allergic airways.

BACKGROUND: Allergic rhinitis results from interactions between a large number of cells and mediators in different compartments of the body. DNA microarrays allow simultaneous measurement of expression of thousands of genes in the same tissue sample. OBJECTIVE: To study gene expression in nasal mucosal biopsies from patients with allergic rhinitis using DNA micro-arrays. METHODS: Nasal biopsies were obtained from 14 patients with symptomatic birch pollen-induced allergic rhinitis and five healthy controls. RNA was extracted from the biopsies and pooled into one patient pool and one control pool. These were analysed in duplicate with DNA micro-arrays containing more than 12 000 known genes. RESULTS: Approximately half of the genes were expressed in the patient and control samples. Guided by the current literature we chose 32 genes of possible relevance to allergic airway inflammation and investigated their relative expression. Among these, transcripts encoding immunoglobulins and their receptors were most abundant. The expression of cytokines and growth factors was low, whereas their corresponding receptors and cell surface markers displayed higher expression levels. IgA had the highest expression of all 12 626 genes. RT-PCR showed that IgA1 was the predominant subclass. This was confirmed by the protein level in nasal fluids. Allergen-specific IgA was significantly higher in patients than in controls and correlated significantly with eosinophil granulae proteins. CONCLUSION: DNA micro-array analysis can be used to identify genes of possible relevance to allergic airway inflammation. In this study, the expression profile in the nasal mucosa was quantitatively dominated by immunoglobulins, particularly IgA. Protein analyses in nasal fluids indicated a role for allergen-specific IgA in eosinophil degranulation.