Effect of rosiglitazone on serum IGF-I concentrations in uncontrolled acromegalic patients under conventional medical therapy: results from a pilot phase 2 study

Treatment of acromegaly by rosiglitazone via upregulating 15-PGDH in both pituitary adenoma and liver

Rosiglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPARγ) ligand, has been reported to reduce growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in 10 patients with acromegaly. However, the mechanisms remain unknown. Here, we reveal that PPARγ directly enhances 15-hydroxyprostaglandin dehydrogenase (15-PGDH) expression, whose expression is decreased and negatively correlates with tumor size in acromegaly. Rosiglitazone decreases GH production and promotes apoptosis and autophagy in GH3 and primary somatotroph adenoma cells and suppresses hepatic GH receptor (GHR) expression and IGF-1 secretion in HepG2 cells. Activating the PGE2/cAMP/PKA pathway directly increases GHR expression. Rosiglitazone suppresses tumor growth and decreases GH and IGF-1 levels in mice inoculated subcutaneously with GH3 cells. The above effects are all dependent on 15-PGDH expression. Rosiglitazone as monotherapy effectively decreases GH and IGF-1 levels in all nineteen patients with active acromegaly. Evidence suggests that rosiglitazone may be an alternative pharmacological approach for acromegaly by targeting both pituitary adenomas and liver.

Pre-diagnostic circulating concentrations of fat-soluble vitamins and risk of glioma in three cohort studies

Few prospective studies have evaluated the relation between fat-soluble vitamins and glioma risk. Using three cohorts-UK Biobank (UKB), Nurses' Health Study (NHS), and Health Professionals Follow-Up Study (HPFS), we investigated associations of pre-diagnostic concentrations of fat-soluble vitamins D, A, and E with incident glioma. In 346,785 participants (444 cases) in UKB, associations with vitamin D (25-hydroxyvitamin D [25(OH)D]) were evaluated by Cox proportional hazards regression. In NHS (52 cases, 104 controls) and HPFS (32 cases, 64 controls), associations with 25(OH)D, vitamin A (retinol), and vitamin E (α- and γ-tocopherol) were assessed using conditional logistic regression. Our results suggested plasma concentrations of 25(OH)D and retinol were not associated with glioma risk. Comparing the highest to lowest tertile, the multivariable hazard ratio (MVHR) for 25(OH)D was 0.87 (95% confidence interval [CI] 0.68-1.11) in UKB and the multivariable risk ratio (MVRR) was 0.97 (95% CI 0.51-1.85) in NHS and HPFS. In NHS and HPFS, the MVRR for the same comparison for retinol was 1.16 (95% CI 0.56-2.38). Nonsignificant associations were observed for α-tocopherol (MVRRtertile3vs1 = 0.61, 95% CI 0.29-1.32) and γ-tocopherol (MVRR tertile3vs1 = 1.30, 95% CI 0.63-2.69) that became stronger in 4-year lagged analyses. Further investigation is warranted on a potential association between α- and γ-tocopherol and glioma risk.

Effects of maternal 25-hydroxycholecalciferol during the last week of gestation and lactation on serum parameters, intestinal morphology and microbiota in suckling piglets

This study was conducted to test the effects of maternal 25-hydroxycholecalciferol (25OHD₃) supplementation on serum parameters, intestinal morphology and microbiota in suckling piglets. The experiment started on day 107 of gestation and lasted until piglets were weaned on day 21 of lactation. Thirty-two sows were allocated randomly to two treatments (ND diet, basal diet with 2000 IU/kg of vitamin D₃; 25-D diet, basal diet with 50 μg/kg 25OHD₃). Results showed that maternal 25-D treatment increased (p < 0.05) serum 25OHD₃ concentration in the umbilical cords, which led to higher (p < 0.05) serum 25OHD₃ concentration of suckling piglets from 25-D sows. The GSH-Px activity in colostrum was higher (p < 0.05), as well as SOD and GSH-Px activities in milk, were higher (p < 0.05) in 25-D sows than ND sows. Compared with piglets suckling ND sows, piglets suckling 25-D sows had higher (p < 0.05) serum SOD activity on day 7, 14 and 21 of lactation. On day 21 of lactation, piglets form 25-D sows had greater (p < 0.05) serum levels of GH and IGF-I and lower (p < 0.05) serum DAO activity than those from ND sows. Piglets from 25-D sows had higher (p < 0.05) jejunal villus height than those from ND sows. Feeding 25OHD₃ to sows tended to increase (p < 0.10) the species richness in the colonic digesta of suckling piglets, as reflected by the α-diversity index of Chao-1. In the caecal digesta, the α-diversity for bacterial community analysis of Simpson and Shannon was lower (p < 0.05) in 25-D piglets than ND piglets. The relative abundances of colonic Alloprevotella and caecal Lactobacillus were significantly higher, while the population of caecal [Eubacterium]_coprostanoligenes_group was lower (p < 0.05) in 25-D piglets than ND piglets. In conclusion, maternal 25OHD₃ supplementation partly improved antioxidant status in sows and suckling piglets and altered gut microbiota in the hindgut of piglets.

Maternal 25-hydroxycholecalciferol during lactation improves intestinal calcium absorption and bone properties in sow-suckling piglet pairs

Lower maternal vitamin D status during lactation is a common health problem. The objectives of this study were to investigate the effects of maternal 25-hydroxycholecalciferol (25-OH-D₃) supplementation during lactation on maternal and neonatal bone health in a sow model. 32 Large White × Landrace sows were assigned randomly to one of two diets supplemented with 2000 IU/kg vitamin D₃ (ND) or 50 μg/kg 25-OH-D₃ (25-D). The experiment began on day 107 of gestation and continued until weaning on day 21 of lactation. Maternal 25-OH-D₃ supplementation significantly decreased milk n-6:n-3 PUFA ratio, which supported bone formation of piglets. Supplementation with 25-OH-D₃ altered bone turnover rate of sows and piglets, as evidenced by higher bone-specific alkaline phosphatase (BALP) concentration in serum. 25-D sows had significantly higher bone density and mechanical properties of tibias and femurs than ND sows. Calcium (Ca) absorption rate was higher in 25-D sows than ND sows, which was caused partially by the increased mRNA expressions of renal 1α-hydroxylase (CYP27B1) and duodenal vitamin D receptor (VDR), transient receptor potential vanilloid 6 (TRPV6), and calcium-binding protein D9k (CaBP-D9k). Maternal 25-OH-D₃ supplementation increased tibial and femoral Ca content by up-regulating Ca-related gene expression in kidney (CYP27B1), ileum (VDR and claudin-2), and colon (VDR and CaBP-D9k), thus, activating 1,25-dihydroxyvitamin D₃ [1,25-(OH)₂-D₃]-dependent Ca transport in piglets. In conclusion, improved milk fatty acids and higher mRNA expressions of calcitropic genes triggered by maternal 25-OH-D₃ supplementation would be the potential mechanism underlying the positive effects of 25-OH-D₃ on maternal and neonatal bone health.

Exploration and Development of PPAR Modulators in Health and Disease: An Update of Clinical Evidence

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that govern the expression of genes responsible for energy metabolism, cellular development, and differentiation. Their crucial biological roles dictate the significance of PPAR-targeting synthetic ligands in medical research and drug discovery. Clinical implications of PPAR agonists span across a wide range of health conditions, including metabolic diseases, chronic inflammatory diseases, infections, autoimmune diseases, neurological and psychiatric disorders, and malignancies. In this review we aim to consolidate existing clinical evidence of PPAR modulators, highlighting their clinical prospects and challenges. Findings from clinical trials revealed that different agonists of the same PPAR subtype could present different safety profiles and clinical outcomes in a disease-dependent manner. Pemafibrate, due to its high selectivity, is likely to replace other PPARα agonists for dyslipidemia and cardiovascular diseases. PPARγ agonist pioglitazone showed tremendous promises in many non-metabolic disorders like chronic kidney disease, depression, inflammation, and autoimmune diseases. The clinical niche of PPARβ/δ agonists is less well-explored. Interestingly, dual- or pan-PPAR agonists, namely chiglitazar, saroglitazar, elafibranor, and lanifibranor, are gaining momentum with their optimistic outcomes in many diseases including type 2 diabetes, dyslipidemia, non-alcoholic fatty liver disease, and primary biliary cholangitis. Notably, the preclinical and clinical development for PPAR antagonists remains unacceptably deficient. We anticipate the future design of better PPAR modulators with minimal off-target effects, high selectivity, superior bioavailability, and pharmacokinetics. This will open new possibilities for PPAR ligands in medicine.

Thiazolidinedione drugs in the treatment of type 2 diabetes mellitus: past, present and future

Thiazolidinedione (TZD) drugs used in the treatment of type 2 diabetes mellitus (T2DM) have proven effective in improving insulin sensitivity, hyperglycemia, and lipid metabolism. Though well tolerated by some patients, their mechanism of action as ligands of peroxisome proliferator-activated receptors (PPARs) results in the activation of several pathways in addition to those responsible for glycemic control and lipid homeostasis. These pathways, which include those related to inflammation, bone formation, and cell proliferation, may lead to adverse health outcomes. As treatment with TZDs has been associated with adverse hepatic, cardiovascular, osteological, and carcinogenic events in some studies, the role of TZDs in the treatment of T2DM continues to be debated. At the same time, new therapeutic roles for TZDs are being investigated, with new forms and isoforms currently in the pre-clinical phase for use in the prevention and treatment of some cancers, inflammatory diseases, and other conditions. The aims of this review are to provide an overview of the mechanism(s) of action of TZDs, a review of their safety for use in the treatment of T2DM, and a perspective on their current and future therapeutic roles.

Relationship Between 25(OH)D and IGF-I in Children and Adolescents with Growth Hormone Deficiency

Recent studies have shown that vitamin D has an impact on the production and secretion of IGF-I in the liver. The aim of our study was to investigate the relationship between the concentrations of 25-hydroxy vitamin D [25(OH)D] and insulin-like growth factor I (IGF-I) in growth hormone deficient children and adolescents before recombinant human growth hormone (rhGH) treatment. The study was retrospective and included 84 children and adolescents aged 4-17. Prior to initiating rhGH therapy, concentrations of 25(OH)D and IGF-I were measured in all patients. IGF-I concentrations were normalized for bone age. The studied group was divided into two subgroups according to serum 25(OH)D levels. Significant positive correlations between 25(OH)D concentration and IGF-I SDS-normalized for bone age were observed in both studied subgroups. The results of our study suggest that vitamin D deficiency could influence IGF-I concentrations in children and adolescents with growth hormone deficiency, and vitamin D deficiency should be normalized before the measurement of IGF-I concentrations to obtain the reliable and unbiased IGF-I values.

Investigational therapies for acromegaly

INTRODUCTION

The treatment of acromegaly aims at normalizing growth hormone (GH) and insulin-like growth factor (IGF-I) levels and controlling tumor growth. The approaches to therapy are essentially three: surgery and pharmacotherapy, alone or in combination, and radiotherapy, generally used in more aggressive tumors.

AREAS COVERED

This review focuses on the novel drug formulations being developed for medical therapy of acromegaly. Even though many efficient treatments have been made available to manage acromegaly in the last two decades, a significant number of patients remain still uncontrolled. Medical therapy represents an important therapeutic option and can be used as the first-line treatment in many patients. However, roughly 25% of patients might be considered as poor responsive or resistant to conventional long-acting somatostatin analogs (SSA) treatment. Therefore, new longer-acting SSA, oral SSA formulations, new combined therapies with weekly doses of pegvisomant, combination therapy with pegvisomant (PEG) and cabergoline (CAB) or SSA and new approaches have been proposed. New molecules are currently under investigation in clinical trials, such as the SSA multi-receptor ligand, pasireotide, which represents a promising option therapy, especially in patients not adequately controlled with currently available SSA. Further, temozolomide has been suggested as an efficient drug for treating GH-aggressive pituitary tumors resistant to conventional therapy.

EXPERT OPINION

All these novel SSA formulations and new molecules implement the available options in therapies of acromegaly to improve disease control. However, further studies are needed to define the exact role of these newer agents. The predicting factors for response to these new therapies should also be determined.

Pioglitazone in acromegaly - an open-label, prospective study

OBJECTIVE

Preclinical studies demonstrate that thiazolidinediones (TZDs) decrease growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels, suggesting that they might be effective treatments for acromegaly. This study investigated the effect of pioglitazone on biochemical indices of disease activity in acromegaly.

DESIGN AND PARTICIPANTS

This was a 4-month open-label prospective study in 16 patients with active acromegaly who were attending public hospital endocrinology clinics.

METHODS

The intervention was pioglitazone 45 mg/day. The primary outcome was change in serum IGF-1; the secondary outcome was change in area under the curve of glucose-suppressed GH.

RESULTS

Serum IGF-1 did not change during treatment with pioglitazone (P = 0·95). After 4 months, the mean (95% CI) change from baseline was -1 μg/l (-51, 49). GH levels following oral glucose loading were unchanged during pioglitazone therapy. After 4 months, the mean (95% CI) change from baseline in area under curve for glucose-suppressed GH was 31 μg/l (-75, 138, P = 0·54).

CONCLUSIONS

Short-term treatment with conventional doses of pioglitazone did not improve biochemical measures of disease activity in acromegaly.