THU0603 IGG4-RELATED SINGLE-ORGAN DISEASE: IMMUNOSUPPRESSION NEEDED AFTER COMPLETE RESECTION? A CASE REPORT AN BRIEF LITERATURE REVIEW

Background:

IgG4-related disease (IgG4-RD) is a polymorphic autoimmune disease leading to tumourous swelling and/or fibrosis of affected organs. Riedel’s thyroiditis is – besides chronic periaortitis, Mikulicz Syndrome and many others – an organ manifestation of IgG4-RD that has been thought to be an independent disease for a long time. About 40% of patients have single organ IgG4-RD while the others suffer from multisystemic disease [1].

Objectives:

Glucocorticoids, sometimes combined with other immunosuppressives are the standard treatment of IgG4-RD, in some situations (e.g. mechanical complications or suspected malignancy) surgery may be necessary but little is known about the management of fully resected single-organ IgG4-RD [1].

Methods:

We report a case of single-organ IgG4-RD (Riedel’s thyroiditis) after complete resection and perform a brief review of the literature to guide clinical management in this situation.

Results:

A woman (51 y) with pre-existing Hashimoto’s thyroiditis (thyroid peroxidase antibody positive) developed a rapidly growing struma with very firm consistency (not allowing fine needle biopsy). Besides slightly increased C-reactive protein (5,3 mg/l) there was no laboratory sign suggestive for IgG4-RD (normal serum IgG4, complement, eosinophils and IgE). Within 4 months the patient suffered from hoarseness and progredient dyspnea. Surgical thyroidectomy was performed and histopathology revealed IgG4-related Riedel’s thyroiditis with extensive (storiform) fibrosis, a dense lymphoplasmacytic infiltrate, obliterative phlebitis, eosinophilia and 13 IgG4-positive plasma cells per high power field.

After referral to our department a comprehensive work-up showed no signs of other manifestations of IgG4-RD. Treatment with glucocorticoids is clearly recommended for patients with symptomatic IgG4-RD in an international consensus statement, whereas “watchful waiting” may be appropriate in some cases of asymptomatic or mild disease. While some highly fibrotic lesions may not respond well to glucocorticoids and may require surgical intervention, no clear guidance is available for the management of fully resected single organ IgG4-RD [2].

A brief review of the literature revealed that few cases of single-organ IgG4-RD remaining in remission after resection without medical treatment have been reported e.g. IgG4-related cholecystitis, autoimmune-pancreatitis, tumours of the intestinal tract, lung, thymus, meninges, paravertebral space and others [3–9].

After discussion of the options with the patient no systemic immunosuppression was given under close follow up without signs of relapse in clinical examinations, laboratory or imaging during the first 6 months.

Conclusion:

Limited evidence from case reports suggests that a “watchful waiting” strategy without systemic immunosuppressive treatment may be reasonable in some cases of single-organ IgG4-RD after the affected organ was completely resected (e.g. due to mechanical complications or suspected malignoma). However, close follow-up monitoring should be applied due to the risk of relapse or development of new organ manifestations.

References:

[1]Brito-Zerón et al.Best Pract. Res. Clin. Rheumatol.2016

[2]Khosroshahi et al.Arthritis Rheumatol.2015

[3]Takahashi et al.Surg. Case Rep.2015

[4]Akbari et al.ACG Case Rep. J.2018

[5]Oda et al.Thorac. Cancer2019

[6]Nambirajan et al.Childs Nerv. Syst. ChNS Off. J. Int. Soc. Pediatr. Neurosurg.2019

[7]Uchida et al.Asian J. Endosc. Surg.2018

[8]Hart et al.Mod. Pathol. Off. J. U. S. Can. Acad. Pathol. Inc2015

[9]Kim et al.Tuberc. Respir. Dis.2014

Disclosure of Interests:

Jan Schirmer: None declared, Marcus Seeger: None declared, Dominik Schulte Paid instructor for: Ferring, Speakers bureau: Amgen, Astra Zeneca, Braun, Fresenius, Ipsen, Johnson & Johnson, Lilly, MSD, Novartis, Novo Nordisk, Sanofi, Matthias Laudes Speakers bureau: Roche, Sanofi, Chugai, Stefan Schreiber Consultant of: AbbVie, Arena, BMS, Biogen, Celltrion, Celgene, IMAB, Gilead, MSD, Mylan, Pfizer, Fresenius, Janssen, Takeda, Theravance, provention Bio, Protagonist and Falk, Bimba F. Hoyer: None declared

Small dense LDL cholesterol in human subjects with different chronic inflammatory diseases

BACKGROUND AND AIMS

Chronic inflammatory diseases (CID) are associated with a profound increase in cardiovascular (CV) risk resulting in reduced life expectancy. However, LDL-cholesterol is reported to be low in CID patients which is referred to as the "LDL paradoxon". The aim of the present study was to investigate whether LDL-particles in CID exhibit an increased content of the highly atherogenic small-dense LDL subfraction (sdLDL).

METHODS AND RESULTS

In this prospective, single center, observational study we enrolled 141 patients with CID (RA n = 59, inflammatory bowel disease (IBD) n = 35, ankylosing spondylitis (SpA) n = 25, Psoriasis n = 22) in 2011 through 2013 to evaluate sdLDL levels before as well as 6 and 26 weeks after initiation of different anti-cytokine therapies (anti-TNFα, anti-IL-6R antibodies). sdLDL levels were compared to 141 healthy individuals in a case control design. Compared to healthy controls, all CID patients displayed a significantly higher sdLDL content within the LDL cholesterol fraction: RA 35.0 ± 9.2% (p < 0.001), SpA 42.5 ± 10.5% (p < 0.001), IBD 37.5 ± 7.1% (p < 0.001), Psoriasis 33.6 ± 4.6% (p < 0.01). Furthermore, the sdLDL/LDL ratio was significantly higher in male compared to female RA subjects (p < 0.05). Neither anti-TNFα nor anti-IL6R medication altered sdLDL levels despite a significant improvement of disease activity.

CONCLUSION

In several different chronic inflammatory disease entities, LDL-cholesterol is shifted toward a pro-atherogenic phenotype due to an increased sdLDL content which might in part explain the LDL paradoxon. Since premature CV disease is a major burden of affected patients, specifically targeting lipid metabolism should be considered routinely in clinical patient care.

CLINICAL TRIALS

Registration at German Clinical Trial Register (DRKS): DRKS00005285.

Duodenal intussusception of the remnant stomach after biliopancreatic diversion: a case report

Background

We present a rare case of an antegrade intussusception of the remnant stomach four years after a biliopancreatic diversion.

Case presentation

A 55-year-old female patient presented with epigastric pain in our emergency room. Laboratory parameters showed an anemia as well as elevated transaminases and hyperbilirubinemia. The CT scan showed an intussusception of the remnant stomach into the duodenum followed by cholestasis. At laparotomy the remnant stomach was resected.

Conclusion

Bowel obstruction and intussusception after bariatric surgery are a rare but often unrecognized complication. Sonography as well as a CT scan should be performed. The exploratory laparoscopy however is the most valuable diagnostic tool in patients with suspected intussusception, due to the high rate of non-specific symptoms and misinterpreted radiographic investigations.

[Robot-assisted vs laparoscopic gastric bypass : First experiences with the DaVinci system in bariatric surgery]

Conventional laparoscopy is the gold standard in bariatric surgery. Internationally, robot-assisted surgery is gaining in importance. Up to now there are only few reports from Germany on the use of the system in bariatric surgery. Since January 2017 we have been performing robot-assisted gastric bypass surgery. It remains unclear whether the use of the robotic system has advantages over the well-established laparoscopic technique. Within a period from January to early August 2017 a total of 53 gastric bypass operations were performed. Of these 16 proximal redo Roux-en-Y gastric bypass operations were performed with the DaVinci Si system versus 29 laparoscopic procedures. A retrospective analysis of the perioperative course was carried out. Body weight, body mass index (BMI), Edmonton obesity staging system (EOSS) and American Society of Anesthesiologists (ASA) classification did not show significant differences. There were also no significant differences in terms of estimated blood loss, intraoperative complications, duration of surgery, postoperative inflammatory parameters and weight loss. There was no mortality and no need for revisional surgery in either group. After laparoscopic surgery there was a delayed occurrence of a leak of the gastrojejunostomy followed by readmission and endoscopic negative pressure wound therapy. The results show that the proximal Roux-en-Y gastric bypass can be performed safely and efficiently using the DaVinci surgical system. Significant differences to the conventional laparoscopic procedure were not found. Larger randomized controlled trials are needed to define the role of the DaVinci system in bariatric surgery.

Integration of Murine and Human Studies for Mapping Periodontitis Susceptibility

Periodontitis is one of the most common inflammatory human diseases with a strong genetic component. Due to the limited sample size of available periodontitis cohorts and the underlying trait heterogeneity, genome-wide association studies (GWASs) of chronic periodontitis (CP) have largely been unsuccessful in identifying common susceptibility factors. A combination of quantitative trait loci (QTL) mapping in mice with association studies in humans has the potential to discover novel risk loci. To this end, we assessed alveolar bone loss in response to experimental periodontal infection in 25 lines (286 mice) from the Collaborative Cross (CC) mouse population using micro-computed tomography (µCT) analysis. The orthologous human chromosomal regions of the significant QTL were analyzed for association using imputed genotype data (OmniExpress BeadChip arrays) derived from case-control samples of aggressive periodontitis (AgP; 896 cases, 7,104 controls) and chronic periodontitis (CP; 2,746 cases, 1,864 controls) of northwest European and European American descent, respectively. In the mouse genome, QTL mapping revealed 2 significant loci (-log P = 5.3; false discovery rate = 0.06) on chromosomes 1 ( Perio3) and 14 ( Perio4). The mapping resolution ranged from ~1.5 to 3 Mb. Perio3 overlaps with a previously reported QTL associated with residual bone volume in F2 cross and includes the murine gene Ccdc121. Its human orthologue showed previously a nominal significant association with CP in humans. Use of variation data from the genomes of the CC founder strains further refined the QTL and suggested 7 candidate genes ( CAPN8, DUSP23, PCDH17, SNORA17, PCDH9, LECT1, and LECT2). We found no evidence of association of these candidates with the human orthologues. In conclusion, the CC populations enabled mapping of confined QTL that confer susceptibility to alveolar bone loss in mice and larger human phenotype-genotype samples and additional expression data from gingival tissues are likely required to identify true positive signals.

The PF4/PPBP/CXCL5 Gene Cluster Is Associated with Periodontitis

Periodontitis is a common dysbiotic inflammatory disease with an estimated heritability of 50%. Due to the limited sample size of available periodontitis cohorts and the underlying trait heterogeneity, genome-wide association studies (GWAS) of chronic periodontitis (CP) have been unsuccessful in discovering susceptibility factors. A strategy that combines agnostic GWAS with a well-powered candidate-gene approach has the potential to discover novel loci. We combined RNA-seq data from gingival tissues with quantitative trait loci (QTLs) that were identified in a F₂-cross of mice resistant and susceptible to infection with oral bacterial pathogens. Four genes, which were located within the mapped QTLs, showed differential expression. The chromosomal regions across the human orthologous were interrogated for putative periodontitis-associated variants using existing GWAS data from a German case-control sample of aggressive periodontitis (AgP; 651 cases, 4,001 controls), the most severe and early onset form of periodontitis. Two haplotype blocks, one upstream to the coding region of UGT2A1 (rs146712414, P = 9.1 × 10^-5; odds ratio [OR], 1.34; 95% confidence interval [CI], 1.16-1.56) and one downstream of the genes PF4/PPBP/CXCL5 (rs1595009, P = 1.3 × 10^-4; OR, 1.32; 95% CI, 1.15-1.52), were associated with AgP. The association of rs1595009 was validated in an independent cohort of CP of European Americans (1,961 cases and 1,864 controls; P = 0.03; OR, 1.45; 95% CI, 1.01-1.29). This association was further replicated in another sample of 399 German CP cases (disease onset <60 y of age) and 1,633 controls ( P = 0.03; OR, 1.75; 95% CI, 1.06-2.90). The combined estimates of association from all samples were P = 2.9 × 10^-5 (OR, 1.2; 95% CI, 1.1-1.3). This study shows the strength of combining QTL mapping and RNA-Seq data from a mouse model with association studies in human case-control samples to identify genetic risk variants of periodontitis.

The wingless-related integration site-5a/secreted frizzled-related protein-5 system is dysregulated in human sepsis

Sepsis and type 2 diabetes exhibit insulin resistance as a common phenotype. In type 2 diabetes we and others have recently provided evidence that alterations of the proinflammatory wingless-related integration site (wnt)-5a/anti-inflammatory secreted frizzled-related protein (sFRP)-5 system are involved in the pathogenesis of insulin resistance. The aim of the present study was to investigate whether this novel cytokine system is dysregulated in human sepsis, which may indicate a potential mechanism linking inflammation to metabolism. In this single-centre prospective observational study, critically ill adult septic patients were examined and proinflammatory wnt5a and wnt5a inhibitor sFRP5 were measured in serum samples by enzyme-linked immunosorbent assay (ELISA) at admission to the intensive care unit (ICU) and 5 days later. Sixty sepsis patients were included, and 30 healthy individuals served as controls. Wnt5a levels were found to be increased significantly in septic patients compared to healthy controls (2·21 ± 0·33 versus 0·32 ± 0·03 ng/ml, P < 0·0001). In contrast, sFRP5 was not altered significantly in septic patients (19·72 ± 3·06 versus 17·48 ± 6·38 ng/ml, P = 0·07). On admission to the ICU, wnt5a levels exhibited a significant positive correlation with the leucocyte count (rs  = 0·3797, P = 0·004). Interestingly, in patients recovering from sepsis, wnt5a levels declined significantly within 5 days (2·17 ± 0·38-1·03 ± 0·28 ng/ml, P < 0·01). In contrast, if sepsis was worsening, wnt5a levels increased in the same time-period by trend (2·34 ± 0·59-3·25 ± 1·02 ng/ml, P > 0·05). sFRP5 levels did not change significantly throughout the study period. The wnt5a/sFRP5 system is altered in human sepsis and might therefore be of interest for future studies on molecular pathophysiology of this common human disease.

Caloric restriction increases serum testosterone concentrations in obese male subjects by two distinct mechanisms

The concentration of serum testosterone is mainly regulated by the testicular function, which is under control of the central hypothalamic-pituitary-gonadal axis. A certain amount of testosterone is converted into β-estradiol by adipose tissue. Obesity in men is often associated with decreased androgen levels. The aim of the present study was to examine the effect of caloric restriction on serum testosterone levels in obese men. Dietary intervention study was performed with a very low calorie diet (800 kcal/d) for 12 weeks. Thirteen obese human male subjects (median body mass index: 42.7 kg/m2) were included. Body composition was assessed by impedance analysis. Insulin sensitivity was estimated by leptin-to-adiponectin ratio (LAR). Testosterone (T), β-estradiol, albumin, sex hormone-binding globulin (SHBG), LH, and FSH serum concentrations were measured by enzyme immunoassays. Statistical analysis was performed on baseline and values after 3 months. Caloric restriction significantly increased total testosterone (6.97 nmol/l to 13.21 nmol/l; p=0.001) and SHBG (22.11 nmol/l to 42.12 nmol/l; p=0.001) concentrations in serum. This is caused by a significant improvement of the testicular function (LH/T: 0.36-0.20; p=0.005) and a significant reduction of the T/β-estradiol conversion rate (73.59-104.29; p=0.003). There was a significant negative correlation of improvement of testicular function and LAR (rs=-0.683 (p=0.042)). In obese men caloric restriction significantly increases the serum testosterone concentration. This is achieved by 2 distinct mechanisms, that is, improvement of testicular function and reduced conversion of testosterone to β-estradiol by aromatase activity of the adipose tissue.

Successful application of belimumab in two patients with systemic lupus erythematosus experiencing a flare during tocilizumab treatment

This case report describes two female lupus patients who both received biological treatment with tocilizumab and with belimumab. The disease course was remarkably similar in both cases. Tocilizumab resulted in a transient improvement in pleurisy and arthritis but was then followed by a clinical flare accompanied by an increase in autoantibodies and a drop in complement levels. Alike, both patients experienced a rapid and sustained improvement after institution of belimumab. The clinical benefit obtained is currently stable under ongoing belimumab therapy.

Weight loss due to a very low calorie diet differentially affects insulin sensitivity and interleukin-6 serum levels in nondiabetic obese human subjects

Inflammatory mechanisms are involved in the pathogenesis of type 2 diabetes with interleukin (IL)-6 being particularly important. While long term exercise has been shown to be associated with reduction in IL-6 serum levels in several reports, the discussion on the effect of dietary intervention on IL-6 serum levels is controversial. In the present study, we aimed to investigate the effect of weight loss due to a very low calorie diet (VLCD) on insulin sensitivity and IL-6 serum levels in nondiabetic obese human individuals. 10 patients with obesity were examined during 12 weeks of a VLCD (800 kcal/d). Body composition was measured by impedance analysis. Blood samples were taken before, during, and after the dietary intervention. Leptin, adiponectin, and IL-6 serum levels were measured by ELISA. The body weight decreased significantly from 123.9±6.2-103.5±5.6 kg with a significant reduction in body fat content (43.2±2.3-36.1±3.1%). Leptin levels exhibited a significant decrease from 56.8±5.6-27.9±5.6 ng/ml while adiponectin levels increased significantly from 7.5±0.9-10.6±1.1 μg/ml. Thereby the leptin-to-adiponectin ratio, a novel marker for insulin sensitivity, significantly improved. Mean IL-6 serum concentrations were within the normal range (3.2±0.8 pg/ml) before the study and were not significantly altered by the nutritional therapy. Despite improvement of insulin sensitivity, IL-6 serum levels did not change throughout the study period, suggesting that in nondiabetic obese human subjects IL-6 might have only a minor role in the impairment of insulin sensitivity.

Adipose tissue macrophages inhibit adipogenesis of mesenchymal precursor cells via wnt-5a in humans

In patients with obesity and type 2 diabetes, adipose tissue is infiltrated by macrophages known to alter adipogenesis of mesenchymal precursor cells via secretion of proinflammatory cytokines. Recently, it has been shown that under certain conditions, immune cells can also express wnt-5a, a factor known to inhibit adipogenesis in humans. Therefore, in this study we aimed to investigate whether macrophages affect adipogenesis of mesenchymal precursor cells via wnt-5a. Wnt-5a was found to be expressed in adipose tissue macrophages in obese and type 2 diabetic human subjects in vivo by immunohistochemistry of adipose tissue biopsies. Furthermore, wnt-5a was detectable in circulating CD14(+) blood monocytes of human subjects with obesity and type 2 diabetes on RNA level by real-time PCR. Besides expression analysis in vivo, we also performed functional studies to explore the role of wnt-5a in low-grade inflammation of adipose tissue. In a cell culture experiment, macrophage-conditioned differentiation medium inhibited adipogenesis of 3T3-L1 cells. This inhibitory effect was restored by adding neutralising anti-wnt-5a antibodies. In conclusion, our data indicate that macrophages alter adipogenesis of 3T3-L1 cells not only via classical proinflammatory cytokines, but also via wnt signalling molecules.

Visfatin/PBEF/Nampt and resistin expressions in circulating blood monocytes are differentially related to obesity and type 2 diabetes in humans

Low-grade inflammation is important in the development of obesity related pathologies such as insulin resistance and type 2 diabetes, and also cardiovascular disease. Visfatin/PBEF/Nampt and resistin are proinflammatory adipokines secreted from adipocytes, monocytes, and macrophages, and have been linked to atherosclerotic plaque formation, recently. The aim of the present study was to investigate if the expression of these molecules in circulating blood monocytes is altered in obese and/or type 2 diabetic human subjects. Monocytes were isolated by CD14-antibody based magnetic cell sorting from blood samples of 17 lean controls, 20 obese nondiabetic subjects, and 19 obese patients with type 2 diabetes. FACS analysis was performed to test purity of the cell preparations. Expression of the different adipokines was measured by multiplex real-time PCR on RNA-level. Visfatin/PBEF/Nampt was found to be very strongly expressed in monocytes, whereas resistin levels were significantly lower. Furthermore, visfatin/PBEF/Nampt expression was significantly upregulated in obese type 2 diabetic patients, whereas obese nondiabetics exhibited similar levels compared to lean controls, indicating that visfatin/PBEF/Nampt levels are related to type 2 diabetes rather than to obesity. In contrast, resistin expression displayed a different pattern being significantly increased in obese subjects compared to controls but not related to type 2 diabetes. These data suggest a differential role for these two proinflammatory adipokines in linking metabolic diseases to atherosclerosis with visfatin/PBEF/Nampt being more important in patients with type 2 diabetes and resistin in obese but nondiabetic human subjects.

Identification of a region in the human IRS2 promoter essential for stress induced transcription depending on SP1, NFI binding and ERK activation in HepG2 cells

Recent studies have discovered changes in the insulin-/IGF1 signaling affecting glucose metabolism and the molecular pathogenesis of human hepatocellular cancer. Insulin/IGF1 receptor mediates its intracellular effects by recruitment of one out of the four different insulin receptor substrates (IRS). To investigate mechanisms of IRS2 expression, we analyzed transcriptional regulation of IRS2 in human HepG2 cells. We identified a region 688 bp upstream of the translation start codon responsible for approximately 90% of basal human IRS2 promoter activity in HepG2 cells, and confirmed binding of specificity protein 1 (also called Sp1 transcription factor, SP1) and nuclear factor 1 (NFI) in this region. Mutation of both SP1 and NFI binding sites or inhibition of extracellular signal regulated kinase (ERK) suppressed IRS2 promoter activity almost completely, revealing a major role of MAP kinases (MAPK) for IRS2 transcription. Activating this cascade with oxidative stress increased IRS2 promoter activity and endogenous IRS2 expression substantially. IRS2 promoter activity rose even more after additional inhibition of p38MAPK indicating an inhibitory effect of p38MAPK on ERK mediated IRS2 transcription. Activation of the MAPK pathway using interleukin 1, beta (IL1B) increased IRS2 promoter activity similar to oxidative stress. In contrast IL1B decreases and inhibition of the MAPK pathway increases IRS1 promoter activity revealing opposed effects of IL1B and ERK on the expression of different IRS proteins. In conclusion we discovered a specific region (-688 to -611 bp) in the IRS2 promoter essential for basal promoter activity and oxidative stress induced transcription depending on ERK activation and SP1 and NFI binding in human hepatocytes.

Human fetal adiponectin and retinol-binding protein (RBP)-4 levels in relation to birth weight and maternal obesity

Recent studies suggest that the perinatal period is a sensitive part in human development with respect to the pathogenesis of metabolic diseases in adulthood. Neonates, who are either small or large for gestational age (SGA or LGA) have a greater risk of developing obesity and insulin resistance in later life. The term "perinatal priming" is used to describe this phenomenon. Therefore, in the present study we first aimed to investigate if birth weight influences fetal adiponectin and RBP-4 metabolism. Umbilical cord blood was obtained form 40 neonates born on term+/-4 weeks and the adipokine concentrations in the serum were measured. In this analysis adiponectin but not RBP-4 levels showed a positive significant correlation to birth weight. Since maternal preconceptional obesity is associated with an increased birth weight and the risk for LGA neonates, we further aimed to investigate, if the maternal nutritional state influences fetal adiponectin and RBP-4. Therefore umbilical cord blood levels of the adipokines were correlated to maternal preconceptional BMI. In this analysis, neither adiponectin nor RBP-4 levels showed a significant correlation. Taken together, in the present study for the first time we directly compare fetal adiponectin and RBP-4 levels in respect to birth weight and maternal preconceptional BMI. Our data suggest that (1) adiponectin is more likely to have a role in perinatal priming of obesity and insulin resistance than RBP-4 and (2) that birth weight has a greater impact on fetal adipokine serum levels than maternal preconceptional obesity.

Expression of the thermogenic nuclear hormone receptor coactivator PGC-1alpha is reduced in the adipose tissue of morbidly obese subjects

Peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC1alpha) is an accessory protein which can potentiate the transcriptional activation function of many nuclear hormone receptors. Its tissue distribution and physiological studies suggest that its principal in vivo roles are to promote cold-induced thermogenesis, mitochondrial biogenesis, hepatic gluconeogenesis, and fatty acid beta-oxidation. It is expressed in the white adipose tissue of both humans and rodents, and in rodents it has been suggested to mediate in part the leptin-induced conversion of white adipocytes from fat storing to fat oxidising cells. In this study, quantitative real-time PCR has been used in human tissue to demonstrate that (1) PGC1alpha mRNA levels in subcutaneous fat are three-fold lower in morbidly obese than in slim subjects; (2) there are no differences in PGC1alpha mRNA between omental and subcutaneous mature adipocytes; (3) there is a robust induction of PGC1alpha expression during subcutaneous human preadipocyte differentiation ex vivo. Whether low PGC1alpha expression is a prelude to the development of obesity, or a consequence of that obesity, attempts to upregulate endogenous white adipose tissue expression may prove a valuable new avenue to explore in obesity therapy.

Suppressed levels of serum cortisol following high-dose oral dexamethasone administration differ between healthy postmenopausal females and patients with established primary vertebral osteoporosis

Hypercortisolism and glucocorticoid treatment, even in a low dose or administered topically, may influence bone metabolism. It was the aim of this study to investigate whether there might be differences in the regulation of endogenous cortisol secretion between patients with established primary vertebral osteoporosis and healthy controls. Suppressed morning serum cortisol concentrations in a 3 mg dexamethasone overnight suppression test were compared in well-defined healthy postmenopausal women (n = 149) and osteoporotic patients classified as having established primary vertebral osteoporosis with no clinical features of hypercortisolism (n = 78). Suppressed cortisol in the healthy controls was 1.08 +/- 0.44 microg/dl and in the primary osteoporotics 1.58 +/- 1.42 microg/dl (p < 0.0001). Of the investigated primary osteoporotics 15.4% (n = 12) had suppressed cortisol levels above the 97.5th percentile (1.96 microg/dl) of the healthy controls. Subgroup analysis regarding the influence of gonadal steroid hormone replacement in both groups and gender in the osteoporotic group did not change the results. Four of the 12 patients with incomplete suppressive cortisol underwent adrenal endosonography, unilateral adrenal nodular hyperplasia being detected in three cases. In two patients the diagnosis was confirmed by histology and normalisation of a dexamethasone suppression test following endoscopic adrenalectomy. These data yield evidence for a difference in the regulation of cortisol secretion following high-dose dexamethasone administration between healthy subjects and a subgroup of patients with primary osteoporosis. This might be due to a relevant amount of autonomous cortisol secretion in some of these patients; however, even cortisol resistance has to be taken into account.

Insulin-regulated transcription factors: molecular link between insulin resistance and cardiovascular risk factors

Patients with insulin resistance and/or type 2 diabetes have a 5-fold increase in cardiovascular mortality rate. Therefore, it is a current issue of discussion that arterial hypertension, lipid disorders as well as visceral obesity are coronary risk factors, which might belong to a syndrome that is caused by decreased insulin sensitivity. Concerning a possible molecular link between insulin resistance, atherosclerosis and obesity, we focus in our research on questions looking for a molecular link between lipid metabolism, insulin action, and obesity at a gene regulatory level. Alterations in the structure, function and regulation of transcription factors appear to be such signalling steps which might play an essential role in the pathogenesis and therapy of cardiovascular risk factors associated with insulin resistance, eg the so called metabolic syndrome. Recent examples are members of the nuclear hormone receptor superfamily, eg peroxisome proliferator-activated receptor (PPAR) isoforms and sterol regulatory element-binding proteins (SREBPs). Beside their regulation by different metabolites, these transcription factors are also targets of hormones, like insulin and leptin, growth factors, and inflammatory signals. Therefore, they appear to be a point of signalling convergence at a gene regulatory level. Major signalling pathways coupling receptors at the cell surface for hormones, growth factors as well as cytokines to gene regulatory events in the nucleus are the MAP-kinase cascades. We have recently defined different postreceptor defects in these pathways in patients with clinical phenotypes corresponding to congenital lipoatrophy. Therefore, these studies may identify novel pathways which play a role in the control of body weight, insulin sensitivity and cardiovascular risk.