Response to semaglutide of non-drinker subjects with type 2 diabetes.

BACKGROUND: Metabolic dysfunction-associated Steatotic Liver Disease (MASLD) displays a worse prognosis in subjects with type 2 diabetes (T2D); effective treatments are, so far, scanty. Semaglutide showed efficacy in improving steatohepatitis. We longitudinally observed a MASLD cohort of T2D subjects starting semaglutide, to detect an improvement of non-invasive surrogates of steatosis and fibro-inflammatory liver involvement, evaluating the role of mild alcohol consumption. PATIENTS AND METHODS: In 62 overweight/obese T2D subjects with MASLD (36 non-drinker and 26 mild alcohol consumers), anthropometric, bio-humoral and transient elastography (TE) data were collected before (T0) and after an average time of 6.4 month (T1) from injective semaglutide prescription. Circulating levels of hormones (GIP, GLP-1, glucagon, insulin) and inflammatory markers (TNFα, MCP-1, IL-18, IL-10) were measured. Steatotic and necro-inflammatory liver involvement was evaluated with FibroScan controlled attenuation parameter (CAP) and liver stiffness (LS), respectively. RESULTS: Significant (p < 0.006) T0-T1 reductions of BMI, waist circumference, fasting glucose, and HbA1c were observed. AST (-10 ± 3 IU/L), ALT (-18 ± 5 IU/L), GGT (-33 ± 15 IU/L), CAP (-25 ± 8 dB/m) and LS (-0.8 ± 0.4 kPa) were reduced, too. GLP-1 increased (+ 95.9 pM, p < 0.0001) and IL-18 was reduced (-46.6 pg/ml, p = 0.0002). After adjustment for confounders, CAP improving was only related to GLP-1 increase (ß=-0.437, p = 0.0122). Mild alcohol intake did not influence these relations. CONCLUSION: Use of semaglutide in subjects with T2D and MASLD is associated with a significant decline of liver steatosis and necroinflammation proxies; mild alcohol assumption did not exert any influence. An independent effect of GLP-1 raise was observed on reduction of steatosis, irrespective of alcohol consumption.

Neglected cardiometabolic risk factors and subclinical target organ damage in post-menopausal women with normal glucose tolerance.

BACKGROUND: Menopausal transition is a crucial step in the women's cardiovascular health, and the risk stratification in apparently health post-menopausal females has been rarely assessed. Heart ultrasonography, unusually performed in such subjects, would be able to detect initial signs of organ damage. We described the cardiovascular risk profile of non-diabetic post-menopausal women, evaluating how easily computed, biochemistry-derived scores were related to ultrasonographic measures of target organ damage. METHODS: We analyzed the characteristics of a cohort of two-hundred and seventy-three women consecutively referring to a prevention program of Azienda Ospedaliero-Universitaria Pisana (years 2017-2022) who underwent clinical evaluation, complete routine biochemical analyses with proxies of insulin resistance, heart and carotid ultrasonography. The cohort was further divided into four groups according to presence of isolated hypercholesterolemia (HC, 37%), isolated hypertension (HT, 5%), both HC/HT (38%), or none of them. RESULTS: In HC and HC/HT, LDL cholesterol was sharply above the recommended values (149 [134-171] mg/dL and 141 [123-159] mg/dL, respectively). E/e' ratio and left atrium size were augmented in HT women and further worsened in HT/HC, with an independent effect of hypertension (E/e' ß=0.055, P=0.013, left atrium volume ß=0.059, P=0.003). Presence of carotid plaques was independently linked to hypertension (ß=0.474, P=0.003). In HC and HC/HT, the Triglycerides-Glucose Index, a surrogate of insulin resistance, was higher than in the other classes (P=0.0013), and it was associated with E/A in HC and HT/HC, with a significative interaction (P=0.0004) with hypertension. Past hormone replacement therapy did not influence clinical, biochemical or echocardiographic parameters. CONCLUSIONS: Postmenopausal women display a high cardiovascular risk burden; a simple clinical and biochemistry screening would be advisable to identify and treat those more at risk. Cardiac ultrasonographic parameters were worse in hypertensive, hypercholesterolemic and insulin-resistant subjects, who may also deserve a deep and early instrumental characterization, especially when these conditions are associated.

Lacking P2X7-receptors protects substantia nigra dopaminergic neurons and hippocampal-related cognitive performance from the deleterious effects of high-fat diet exposure in adult male mice.

Background: Dietary fat consumption, involved in the pathogenesis of insulin resistance and impaired glucose metabolism, is linked with decline in cognitive functions, dementia, and development of Parkinson's disease and Alzheimer's disease. Mature IL-1ß, requiring the activation of the P2X7 receptor (P2X7R)-inflammasome complex, is an important mediator of neuroinflammation. The aim of the study was to test whether P2X7R activation might interfere with systemic and cerebral metabolic homeostasis. Methods: We treated WT and P2X7R KO mice with a high-fat diet (HFD) for 16 weeks, evaluating the effects on the Substantia Nigra and Hippocampus, target areas of damage in several forms of cognitive impairment. Results: HFD-treated WT and P2X7R KO mice showed a different brain mRNA profile of Insulin and Igf-1, with these genes and relative receptors, more expressed in KO mice. Unlike P2X7R KO mice, WT mice treated with HFD displayed a diameter reduction in dopaminergic neurons in the Substantia Nigra, accompanied by an increased IBA1 expression in this area; they also showed poor performances during Y-Maze and Morris Water Maze, tasks involving Hippocampus activity. Conversely, Parkin, whose reduction might promote neuronal cell death, was increased in the brain of P2X7R KO animals. Conclusion: We report for the first time that HFD induces damage in dopaminergic neurons of the Substantia Nigra and a Hippocampus-related worse cognitive performance, both attenuated in the absence of P2X7R. The involved mechanisms might differ in the two brain areas, with a predominant role of inflammation in the Substantia Nigra and a metabolic derangement in the Hippocampus.

MG53 does not mark cardiovascular risk and all-cause mortality in subjects with type 2 diabetes: A prospective, observational study.

AIMS: Subjects with type 2 diabetes (T2D) are characterized by a high cardiovascular morbidity and mortality. MG53, a marker of peripheral insulin resistance, has been linked with impaired ß-cell function and decreased ß-cell survival, and its circulating levels are increased in T2D. Its relationship with the cardiovascular risk profile and mortality in T2D is currently unknown. METHODS: In this longitudinal study, MG53 was measured in serum samples collected at baseline for 296 Caucasian participants in the MIND.IT study, relating its circulating levels with the cardiovascular risk profile and all-cause mortality over a 17-years follow up. RESULTS: As compared to a reference cohort of 234 healthy subjects, MG53 levels were higher in T2D individuals (p < 0.001), and higher in T2D women than in men (p = 0.001). In the whole study cohort, MG53 levels were directly related to HbA1c (r2 0.029; p = 0.006) and systolic blood pressure (r2 0.032; p = 0.004). There was no difference in baseline MG53 levels between deceased and alive participants, neither predict all-cause mortality. CONCLUSIONS: MG53 does not mark the cardiovascular risk profile neither predict long-term mortality in Caucasian T2D individuals.

Empagliflozin and Renal Sodium-Hydrogen Exchange in Healthy Subjects.

CONTEXT: Sodium glucose co-transporter-2 inhibitors exert clinically relevant cardiorenal protection. Among several mechanisms, inhibition of sodium-hydrogen exchanger-3 (NHE3) in proximal renal tubules has been proposed in rodents. Demonstration of this mechanism with the associated electrolyte and metabolic changes in humans is lacking. OBJECTIVE: The present proof-of-concept study was designed to explore the involvement of NHE3 in modulating the response to sodium glucose co-transporter-2 inhibitors in humans. METHODS: Twenty healthy male volunteers received 2 tablets of empagliflozin 25 mg during a standardized hydration scheme; freshly voided urines and blood samples were collected at timed intervals for 8 hours. Protein expression of relevant transporters was examined in exfoliated tubular cells. RESULTS: Urine pH levels increased after empagliflozin (from 5.81 ± 0.5 to 6.16 ± 0.6 at 6 hours, P = .008) as did urinary output (from median, 1.7; interquartile range [IQR, 0.6; 2.5] to 2.5 [IQR, 1.7; 3.5] mL/min-1, P = .008) and glucose (from median, 0.03 [IQR, 0.02; 0.04] to 34.8 [IQR, 31.6; 40.2] %, P < .0001), and sodium fractional excretion rates (from median, 0.48 [IQR, 0.34; 0.65] to 0.71 [IQR, 0.55; 0.85] %, P = .0001), whereas plasma glucose and insulin concentrations decreased and plasma and urinary ketones increased. Nonsignificant changes in NHE3, phosphorylated NHE3, and membrane-associated protein 17 protein expression were detected in urinary exfoliated tubular cells. In a time-control study in 6 participants, neither urine pH nor plasma and urinary parameters changed. CONCLUSIONS: In healthy young volunteers, empagliflozin acutely increases urinary pH while inducing a substrate shift toward lipid utilization and ketogenesis, without significant changes in renal NHE3 protein expression.

The P2X7R-NLRP3 and AIM2 Inflammasome Platforms Mark the Complexity/Severity of Viral or Metabolic Liver Damage.

P2X7R-NLRP3 and AIM2 inflammasomes activate caspase-1 and the release of cytokines involved in viral-related liver disease. Little is known about their role in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steato-hepatitis (NASH). We characterized the role of inflammasomes in NAFLD, NASH, and HCV. Gene expression and subcellular localization of P2X7R/P2X4R-NLRP3 and AIM2 inflammasome components were examined in histopathological preparations of 46 patients with biopsy-proven viral and metabolic liver disease using real-time PCR and immunofluorescence. P2X7R, P2X4R, and Caspase-1 are two- to five-fold more expressed in patients with NAFLD/NASH associated with chronic HCV infection than those with metabolic damage only (p ≤ 0.01 for all comparisons). The AIM2 inflammasome is 4.4 times more expressed in patients with chronic HCV infection, regardless of coexistent metabolic abnormalities (p = 0.0006). IL-2, a cytokine playing a pivotal role during chronic HCV infection, showed a similar expression in HCV and NASH patients (p = 0.77) but was virtually absent in NAFLD. The P2X7R-NLRP3 complex prevailed in infiltrating macrophages, while AIM2 was localized in Kupffer cells. Caspase-1 expression correlated with elastography-based liver fibrosis (r = 0.35, p = 0.02), whereas P2X7R, P2X4R, NRLP3, Caspase-1, and IL-2 expression correlated with circulating markers of disease severity. P2X7R and P2X4R play a major role in liver inflammation accompanying chronic HCV infection, especially when combined with metabolic damage, while AIM2 is specifically expressed in chronic viral hepatitis. We describe for the first time the hepatic expression of IL-2 in NASH, so far considered a peculiarity of HCV-related liver damage.

Effect of empagliflozin on plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) in patients with type 2 diabetes.

AIM: Cardiovascular benefits of sodium-glucose cotrasporter-2 (SGLT2) inhibitors occur despite a modest increase in low-density lipoprotein cholesterol (LDL-c). We tested whether the effects of chronic SGLT2 inhibition on lipid profile composition are mediated by elevation in plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) levels inhibiting LDL clearance. METHODS: 78 patients with type 2 diabetes (T2D) received empagliflozin 25 mg/d in an open-label design. At enrollment and after 4-week therapy, fasting blood samples were collected for the measurement of plasma PCSK9, glucose, total and fractional cholesterol, and triglycerides. RESULTS: Plasma PCSK9 was not significantly affected by empagliflozin (-10.7 [-24.1, 2.7] ng/mL). The treatment induced a mild increase in high-density lipoprotein cholesterol (+1.7 [0.5, 3.0] mg/dL), without significant LDL-c alterations (+1.0 [-4.1, 6.0] mg/dl). Changes in LDL-c were associated with changes in fasting glucose levels (ß = 0.320, p = 0.017), but not with plasma PCSK9 (ß = 0.010, p = 0.800), after adjustment for age, sex, baseline LDL-c, and body weight change. CONCLUSION: In patients with T2D, chronic SGLT2 inhibition with empagliflozin has no potentially harmful effects on circulating PCSK9 levels. This finding does not support a pathogenetic role of plasma PCSK9 in the mild plasma lipid alterations observed during SGLT2i treatment.

P2X7 Receptor and Heart Function in a Mouse Model of Systemic Inflammation Due to High Fat Diet.

Purpose: Low-grade inflammation contributes to heart failure in obesity or type 2 diabetes mellitus. The P2X7 receptor (P2X7R) is a key regulator of several pro-inflammatory responses in multiple tissues and organs; however, its involvement in the onset of heart dysfunction remains unclear. The study evaluated the role of P2X7R as a cardiac function regulator in C57BL/6J wild-type (WT) and P2X7R knockout (KO) mice by inducing systemic inflammation with high fat diet (HFD). Methods: Specific parameters of systolic and diastolic function and heart morphology were measured in vivo before animal sacrifice by high-frequency ultrasonographic analysis. Gene and protein expression of cardiac biomarkers associated with inflammatory-oxidative pathways were evaluated by real-time PCR and Western Blotting. Results: P2X7R-mediated up-regulation of the NLRP3-caspase-1 complex, increased expression of key oxidative stress (NOS-2, TNFα), and chemotactic (MCP-1) mediators were revealed in WT-HFD animals. In KO-HFD mice, such inflammatory-oxidative pathway was silent. Nevertheless, HFD induced in vivo a clear alteration of diastolic pattern (E/A: p < 0.03 vs WT-HFD) and a cardiac morphologic remodelling (left ventricular mass: p < 0.05 vs WT-HFD) only in P2X7R KO animals. Surprisingly, the transcriptional and protein expression of IL-1ß and IL-6, usually regulated through P2X7R activation, were significantly higher in KO-HFD than in WT-HFD mice (both p < 0.05). Furthermore, an up-regulation of miR-214 and a down-regulation of miR-126 in heart of HFD-KO mice were observed, suggesting a link between such epigenetic dysregulation and cytokine overexpression as a potential pathophysiologic mechanism concurring to the progressive cardiac dysfunction. Conclusion: These findings seem to suggest a cardioprotective role of P2X7R toward this tissue-specific inflammatory damage, likely through tissue homeostasis and organ functionality preservation.

MG53 marks poor beta cell performance and predicts onset of type 2 diabetes in subjects with different degrees of glucose tolerance.

AIM: MG53 is a myokine modulating insulin signaling in several tissues; its relationship to glucose tolerance or risk of developing type 2 diabetes mellitus (T2DM) is unknown. This observational, prospective study aimed at evaluating the relationship between MG53 and glucose tolerance, testing whether its circulating levels may be associated with disease progression in a cohort at high risk of T2DM. METHODS: Five hundred and fifteen subjects who underwent a deep characterization of their glucose tolerance in the years 2003-2005 participated in this study. MG53 levels were measured at baseline. Glucose tolerance status was available over a follow-up of 15 ± 2 years for 283 of them; their vital status as of December 2020 was also retrieved. RESULTS: MG53 levels were significantly lower in subjects with normal glucose tolerance than in subjects with impaired glucose regulation (IGR) or T2DM. Individuals in the highest MG53 levels quartile had more frequently 1h-post load glucose ≥ 155 mg/dL (54% vs 39%; p = 0.015), worse proportional control of ß-cell function (p < 0.05-0.01), as determined by mathematical modeling, and worse Disposition Index (DI) (0.0155 ± 0.0081 vs 0.0277 ± 0.0030; p < 0.0001). At follow-up, baseline MG53 levels were higher in progressors than in non-progressors (120.1 ± 76.7 vs 72.7 ± 63.2 pg/ml; p = 0.001; ROC curve area for incident diabetes of 0.704). In a multivariable regression with classic risk factors for T2DM and DI, MG53 remained independently associated with progression with T2DM. CONCLUSION: MG53 may be a novel biomarker of glucose dysregulation associated with ß-cell dysfunction, likely improving our ability to identify, among high-risk subjects, those more likely to develop T2DM.

P2X7 receptor/NLRP3 inflammasome complex and α-synuclein in peripheral blood mononuclear cells: a prospective study in neo-diagnosed, treatment-naïve Parkinson's disease.

BACKGROUND AND PURPOSE: Neuroinflammation and probably systemic inflammation, with abnormal α-synuclein deposition, participate in the development of Parkinson's disease (PD). The P2X7 receptor/NLRP3 inflammasome complex is upregulated in the brain of PD patients. By a prospective approach, the degree of systemic activation of such complex, and its regulatory mechanisms, were explored in treatment-naïve PD individuals. METHODS: The expression and functional activity of the inflammasome were measured in peripheral blood mononuclear cells of 25 newly diagnosed PD patients and 25 controls at baseline and after 12 months of pharmacological treatment, exploring the intracellular signalling involved and its epigenetic regulation. RESULTS: De novo PD patients were characterized by a systemic hyper-expression of the P2X7R/NLRP3 inflammasome platform, probably able to modulate lymphomonocyte α-synuclein, whose brain deposits represent the main pathogenetic factor of PD. A reduced c-Jun N-terminal kinase (JNK) phosphorylation might be the intracellular signalling mediating this effect. miR-7 and miR-30, implied in the pathogenesis of PD and in the post-transcriptional control of α-synuclein and NLRP3 expression, were also increased in PD. After 1 year of usual anti-Parkinson treatments, such inflammatory platform was significantly reduced. CONCLUSIONS: Mononuclear cells of newly diagnosed PD subjects display a hyper-expression of the P2X7R/NLRP3 inflammasome platform that seems to modulate cellular α-synuclein content and is reduced after PD treatment; an impaired JNK phosphorylation might be the intracellular signalling mediating this effect, undergoing an epigenetic regulation by miR-7 and miR-30.

Clinical and epigenetic determinants of edentulism in type 2 diabetic subjects referring to a tertiary center.

AIMS: Edentulism, extreme consequence of severe periodontitis, carries a high cardiovascular and all-cause death risk. The prevailing phenotype of edentulous patients with type 2 diabetes (T2D) has never been defined, neither it is known whether an epigenetic signature of such condition exists. METHODS: We collected clinical and biochemical data and administered a questionnaire on oral health in 248 consecutive T2D individuals. Vital status was checked after 17 ±â€¯7 months. miRNAs involved in periodontal inflammation were measured. RESULTS: Forty-seven patients (19%) were edentulous (ED), a higher prevalence than in the Italian general population (10.9% from ISTAT data). ED were older, with low level of instruction and higher fasting glucose vs not edentulous (noED). Participants displayed a scarce awareness of the association periodontitis-T2D. ED showed a specific epigenetic signature (lower miR214-5p and higher miR126-5p urinary levels). At the follow-up, metabolic profile similarly improved in ED and noED; death occurrence was similar. CONCLUSIONS: In this cohort of T2D, age is the only variable associated with edentulism; such condition displays an epigenetic signature, independent of the clinical phenotype; awareness of the clinical relevance and implications of periodontitis and edentulism are scarce. However, edentulism does not mark an increased rate of micro-macrovascular complications or mortality.

Normal Versus Slowly Processed Pasta and Post-Prandial Glucose Homeostasis in Healthy Subjects: A Pilot Study.

Nutritional science is gaining increasing attention due to the implicit potential to prevent cardio-metabolic diseases. It is also becoming clear that food-making process might influence the metabolic response to the meal. We have conducted a proof-of-concept study to investigate whether slowly processed pasta might positively impact glucose homeostasis. A total of 14 healthy male volunteers underwent two different mixed-meal tests in a randomized order. One meal was composed of 100 g of normally processed pasta and the other 100 g of slowly processed pasta. Each meal was completed with 10 g of olive oil and 10 g of parmesan cheese. Glucose, insulin, and incretin post-prandial responses were assessed at 15, 30, 60, 90, 120, 150, and 180 min. Glucose tolerance, insulin, and incretin response were unaffected by the two different pasta types. However, a slight difference was evident in the shape of the curve of post-prandial insulin (i.e., mildly delayed with the slowly processed pasta). Despite the common belief of a different impact of normally processed and slowly processed pasta on glucose metabolism, they show a superimposable post-prandial metabolic response after a single meal in male healthy individuals. Further studies are required to confirm these results also in chronic, real-life settings and then to translate them to metabolically impaired individuals.

PCB153 reduces apoptosis in primary cultures of murine pituitary cells through the activation of NF-κB mediated by PI3K/Akt.

Polychlorinated biphenyls (PCBs) are persistent pollutants involved in human tumorigenesis. PCB153 is a ubiquitous non-dioxin-like PCB with proliferative and anti-apoptotic effects. To explore the impact of PCB153 in the survival of pituitary cells, we exposed murine pituitary primary cells to PCB153 10 µM for 24 h. Apoptosis was assessed by RT-qPCR, Western-blot, immunoprecipitation, caspase activity, and immunofluorescence. We found that PCB153 decreased pituitary apoptosis through both the extrinsic and intrinsic pathways. PCB153 reduced the level of the pro-apoptotic protein p38-MAPK. Otherwise, PCB153 activated PI3K/Akt and Erk1/2 pathways and enhanced the expression and nuclear translocation of NF-κB. Cotreatments with specific inhibitors revealed that only PI3K/Akt changed the caspase-3 expression and NF-κB activation induced by PCB153. Also, PCB153 decreased the expression of the pro-apoptotic and pro-senescent cyclins p53 and p21. In summary, exposure to PCB153 leads to a downregulation of apoptosis in the pituitary driven by a PI3K/Akt-mediated activation of NF-κB.

Effect of Treatment of Periodontitis on Incretin Axis in Obese and Nonobese Individuals: A Cohort Study.

CONTEXT: Periodontitis confers an increased risk of developing type 2 diabetes and, in patients with obesity, it might interfere with the incretin axis. The effect of periodontal treatment on glucoregulatory hormones remains unknown. OBJECTIVE: To evaluate the effect of periodontal treatment on incretin axis in obese and lean nondiabetic individuals. SETTING: King's College Dental Hospital and Institute, London, UK. PARTICIPANTS AND METHODS: The metabolic profile of obese and normal-body-mass-index individuals affected by periodontitis was studied at baseline, 2, and 6 months after intensive periodontal treatment, by measuring plasma insulin, glucagon, glucagon-like peptide-1(GLP-1), and glucose-dependent insulinotropic polypeptide (GIP) and markers of systemic inflammation and oxidative stress. MAIN OUTCOME MEASURE(S): Circulating levels of incretins and inflammatory markers. RESULTS: At baseline, periodontal parameters were worse for obese than nonobese; this was accompanied by higher levels of circulating high-sensitivity C-reactive protein (hs-CRP), insulin, and GLP-1. The response to periodontal treatment was less favorable in the obese group, without significant variations of hs-CRP or malondialdehyde. Glucoregulatory hormones changed differently after treatment: while insulin and glucagon did not vary at 2 and 6 months, GLP-1 and GIP significantly increased at 6 months in both groups. In particular, GLP-1 increased more rapidly in obese participants, while the increase of GIP followed similar trends across visits in both groups. CONCLUSIONS: Nonsurgical treatment of periodontitis is associated with increased GLP-1 and GIP levels in nonobese and obese patients; changes in GLP-1 were more rapid in obese participants. This might have positive implications for the metabolic risk of these individuals.

Divergent Effects of Dioxin- or Non-Dioxin-Like Polychlorinated Biphenyls on the Apoptosis of Primary Cell Culture from the Mouse Pituitary Gland.

Polychlorinated biphenyls (PCBs) can disrupt the endocrine function, promote neoplasms and regulate apoptosis in some tissues; however, it is unknown whether PCBs can affect the apoptosis of pituitary cells. The study evaluated the effect of PCBs on the apoptosis of normal pituitary cells and the underlying mechanisms. Primary cell cultures obtained from mouse pituitary glands were exposed to Aroclor 1254 or selected dioxin-like (PCB 77, PCB 126) or non-dioxin-like (PCB 153, PCB 180) congeners. Apoptosis was evaluated by Annexin V staining, DNA fragmentation, and TUNEL assay. Both the expression and activity of caspases were analyzed. Selective thyroid hormone receptor (TR) or aryl-hydrocarbon receptor (AhR) or CYP1A1 antagonist were used to explore the mechanisms underlying PCBs action. Our results showed that Aroclor 1254 induced the apoptosis of pituitary cells as well as the final caspase-3 level and activity through the extrinsic pathway, as shown by the increased caspase-8 level and activity. On the other hand, the intrinsic pathway evaluated by measuring caspase-9 expression was silent. The selected non-dioxin-like congeners either increased (PCB 180) or reduced (PCB 153) pituitary cell apoptosis, affecting the extrinsic pathway (PCB 180), or both the extrinsic and intrinsic pathways (PCB 153), respectively. In contrast, the dioxin-like congeners (PCB 77 and PCB 126) did not affect apoptosis. The anti-apoptotic phenotype of PCB 153 was counteracted by a TR or a CYP1A1 antagonist, whereas the pro-apoptotic effect of PCB 180 was counteracted by an AhR antagonist. The induced apoptosis of Aroclor 1254 or PCB 180 was associated with a reduction of cell proliferation, whereas the decreased apoptosis due to PCB 153 increased cell proliferation by 30%. In conclusion, our data suggest that non-dioxin-like PCBs may modulate apoptosis and the proliferation rate of pituitary cells that have either pro- or anti-apoptotic effects depending on the specific congeners. However, the impact of PCBs on the process of pituitary tumorigenesis remains to be elucidated.

Growth hormone is necessary for the p53-mediated, obesity-induced insulin resistance in male C57BL/6J x CBA mice.

Insulin resistance is a key marker of both obesity and GH excess. The purpose of the study was to assess the role of GH on p53-mediated insulin resistance of male mice with obesity due to a high-fat diet. C57BL/6J × CBA male mice fed on a high-fat diet (Obe) were studied; male mice fed a normal diet (Lean) or transgenic mice for bovine GH under the same genetic background (Acro) served as controls. The convergence of p53 and GH pathways was evaluated by Western blot. Obe mice had insulin resistance, which was sustained by a selective increased expression of p53 in adipose tissue. Normal insulin sensitivity was restored, and adipose p53 expression normalized when the GH pathway was blocked. Only the adipose p53 expression was sensitive to the GH blockage, which occurred through the p38 pathway. Adipose tissue of Obe mice had a coordinate overexpression of suppressors of cytokine signal 1-3 and signal transducers and activators of transcription-1, -3, and -5b, not different from that of Acro mice, suggesting an increased sensitivity of adipose tissue to GH. On the contrary, Lean mice were unaffected by changes of GH action. GH seems to be necessary for the increased adipose p53 expression and for insulin resistance of obese mice.

Cardiac extrinsic apoptotic pathway is silent in young but activated in elder mice overexpressing bovine GH: interplay with the intrinsic pathway.

Apoptosis may occur through the mitochondrial (intrinsic) pathway and activation of death receptors (extrinsic pathway). Young acromegalic mice have reduced cardiac apoptosis whereas elder animals have increased cardiac apoptosis. Multiple intrinsic apoptotic pathways have been shown to be modulated by GH and other stimuli in the heart of acromegalic mice. However, the role of the extrinsic apoptotic pathways in acromegalic hearts is currently unknown. In young (3-month-old) acromegalic mice, expression of proteins of the extrinsic apoptotic pathway did not differ from that of wild-type animals, suggesting that this mechanism did not participate in the lower cardiac apoptosis levels observed at this age. On the contrary, the extrinsic pathway was active in elder (9-month-old) animals (as shown by increased expression of TRAIL, FADD, TRADD and increased activation of death inducing signaling complex) leading to increased levels of active caspase 8. It is worth noting that changes of some pro-apoptotic proteins were induced by GH, which seemed to have, in this context, pro-apoptotic effects. The extrinsic pathway influenced the intrinsic pathway by modulating t-Bid, the cellular levels of which were reduced in young and increased in elder animals. However, in young animals this effect was due to reduced levels of Bid regulated by the extrinsic pathway, whereas in elder animals the increased levels of t-Bid were due to the increased levels of active caspase 8. In conclusion, the extrinsic pathway participates in the cardiac pro-apoptotic phenotype of elder acromegalic animals either directly, enhancing caspase 8 levels or indirectly, increasing t-Bid levels and conveying death signals to the intrinsic pathway.

Regulation of cardiac fatty acids metabolism in transgenic mice overexpressing bovine GH.

Cardiac energy metabolism depends mainly on fatty acid (FA) oxidation; however, regulation of FA metabolism in acromegalic (Acro) heart is unknown. The aim of the study was to evaluate cardiac expression of key proteins of FA metabolism in young and elder transgenic mice overexpressing bovine GH Acro. Expression of proteins regulating FA entry into the cells, their uptake by mitochondria and beta-oxidation were evaluated by western blot, while FA content by Fourier transform infrared microspectrometry. Regulatory mechanisms of key steps of FA metabolism were also studied. The expression of plasma-membrane FA carriers (fatty acid-binding protein and fatty acid transport protein-1) and acylCoA synthetase was higher in young and lower in elder Acro than in corresponding controls; likewise, expression of cytoplasm to mitochondria-1 (CPT-1), the key enzyme of mitochondrial FA uptake, and that of medium-chain acyl-CoA dehydrogenase and long-chain acyl-CoA dehydrogenase, two regulatory beta-oxidation dehydrogenases, followed a similar pattern. FA content was lower in young and higher in elder Acro than in wild-type, suggesting an increased utilisation in young animals. GH regulated expression of key proteins of FA metabolism through changes in peroxisome proliferator-activated receptor alpha (PPARalpha) expression, which varied accordingly. GH effect was confirmed by treatment of Acro mice with a receptor antagonist, which abolished changes in key proteins of FA metabolism in young Acro. GH increased phosphorylation of AMP-activated protein kinase and anti-acetyl-CoA-carboxylase, two regulatory kinases, leading to lower CPT-1 inhibition by malonyl-CoA, and intervened in regulating PPARalpha expression through the ERK 1/2 pathway. In conclusion, chronic GH excess increased FA metabolism in the young age, whereas its action was overwhelmed in elder ages likely by GH-independent mechanisms, leading to reduced expression of key enzyme of FA metabolism.

Reduced colonic apoptosis in mice overexpressing bovine growth hormone occurs through changes in several kinase pathways.

OBJECTIVE: Growth hormone (GH) has antiapoptotic effects in several cell lines, including human colonic adenocarcinoma cells. In addition, it has been reported that patients with acromegaly have reduced apoptosis in colonic mucosa. The aim of the study was to investigate colonic apoptosis and underlying molecular mechanisms in transgenic mice overexpressing bovine GH (Acro) aged 3 months (young) or 9 months (elder). DESIGN AND METHODS: Apoptosis in colonic epithelial cells was evaluated by TUNEL and Annexin V; expression of pro- and anti-apoptotic proteins was assessed by Western blot. GH action was blocked treating Acro with a selective GH receptor antagonist. RESULTS: Young and elder Acro had lower colonic apoptosis [driven by GH through p38, p44/42 and PI3 kinase pathways], than littermate controls; changes were abolished by treating Acro with a selective GH receptor antagonist. The effects of GH were consistent with an anti-apoptotic phenotype (reduced cytosolic cytochrome-c, Bad and Bax and increased Bcl-2, and Bcl-XL level) leading to lower activation of caspase-9 and caspase-3. Changes in apoptotic proteins reversed after treatment with a GH receptor antagonist, suggesting a direct effect of GH. In addition, antiapoptotic phenotype of Acro had a protective role against doxorubicin-induced apoptosis. CONCLUSIONS: Our results suggest that GH leads to increased and reduced levels of anti- and pro-apoptotic proteins, respectively, lowering apoptosis in either young or elder transgenic animals through activation of several kinase pathways.

Changes in the expression of suppressor of cytokine signalling (SOCS) 2 in the colonic mucosa of acromegalic patients are associated with hyperplastic polyps.

BACKGROUND: Acromegalic patients have increased prevalence of colonic polyps. Development of hyperplastic polyps was related to suppressor of cytokine signalling (SOCS) 2 haploinsufficiency in animal models of acromegaly. OBJECTIVE AND PATIENTS: To evaluate whether variations in SOCS2 expression in the colonic mucosa of acromegalic patients might be associated to hyperplastic polyps, patients with active acromegaly or disease in remission with or without hyperplastic polyps were studied; controls were non-acromegalic subjects age- and sex- matched with or without polyps. MEASUREMENTS: Expression of SOCS1-3 was evaluated by RT-PCR, immunofluorescence and Western blot in the colonic mucosa. Coimmunoprecipatiton was used to evaluate multimeric protein complexes. RESULTS: Acromegalic patients with active disease and hyperplastic polyps had higher levels of SOCS2 transcripts; on the contrary, SOCS1 and SOCS3 transcripts did not differ among the study groups. While the expression of SOCS2 and SOCS3 protein was indistinguishable with that of the corresponding transcripts, SOCS1 protein expression was reduced in active acromegalic patients with polyps. SOCS1 protein was reduced owing to its increased proteasome degradation mediated by SOCS2. The increased SOCS2 and reduced SOCS1 led to increased STAT5b expression, suggesting a higher GH signalling transduction. CONCLUSIONS: Acromegalic patients with active disease and hyperplastic polyps have high levels of SOCS2 and increased SOCS1 degradation, leading to reduced negative feedback on GH signalling, likely favouring a hyperplastic polyps phenotype.