Rana Malek

Protection from obesity and diabetes by blockade of TGF-β/Smad3 signaling

Imbalances in glucose and energy homeostasis are at the core of the worldwide epidemic of obesity and diabetes. Here, we illustrate an important role of the TGF-β/Smad3 signaling pathway in regulating glucose and energy homeostasis. Smad3-deficient mice are protected from diet-induced obesity and diabetes. Interestingly, the metabolic protection is accompanied by Smad3(-)(/-) white adipose tissue acquiring the bioenergetic and gene expression profile of brown fat/skeletal muscle. Smad3(-/-) adipocytes demonstrate a marked increase in mitochondrial biogenesis, with a corresponding increase in basal respiration, and Smad3 acts as a repressor of PGC-1α expression. We observe significant correlation between TGF-β1 levels and adiposity in rodents and humans. Further, systemic blockade of TGF-β signaling protects mice from obesity, diabetes, and hepatic steatosis. Together, these results demonstrate that TGF-β signaling regulates glucose tolerance and energy homeostasis and suggest that modulation of TGF-β activity might be an effective treatment strategy for obesity and diabetes.

Thyroid Hormone Induced Brown Adipose Tissue and Amelioration of Diabetes in a Patient with Extreme Insulin Resistance

CONTEXT Brown adipose tissue (BAT) found by positron emission/computed tomography (PET-CT) using flouro-deoxyglucose (FDG) is inducible by cold exposure in men. Factors leading to increased BAT are of great interest for its potential role in the treatment of diabetes and obesity. OBJECTIVE We tested whether thyroid hormone (TH) levels are related to the volume and activity of BAT in a patient with a mutation in the insulin receptor gene. DESIGN/SETTING/INTERVENTION: Our work was based on the case report of a patient in an observational study at the National Institutes of Health. PATIENT The patient discontinued insulin and oral antidiabetics after thyroidectomy and suppressive-dose levothyroxine therapy for thyroid cancer. PET-CT uptake in BAT was confirmed by histology and molecular analysis. OUTCOMES PET-CT studies were performed, and we measured hemoglobin A1c and resting energy expenditure before and after levothyroxine discontinuation for thyroid cancer testing. Molecular studies of BAT and white adipose samples are presented. RESULT Supraclavicular and periumbilical sc adipose tissue demonstrated molecular features of BAT including uncoupling protein-1, type 2 deiodinase, and PR domain containing 16 by quantitative PCR. Activity of type 2 deiodinase activity was increased. The discontinuation of levothyroxine resulted in decreased FDG uptake and diminished volume of BAT depots accompanied by worsening of diabetic control. CONCLUSIONS This case demonstrates the TH effect on BAT activity and volume in this patient and an association between BAT activity and glucose levels in this patient. Because the contribution of TH on skeletal muscle energy expenditure and fuel metabolism was not assessed, an association between BAT activity and glucose homeostasis can only be suggested.

Treatment of Type B Insulin Resistance: A Novel Approach to Reduce Insulin Receptor Autoantibodies

BACKGROUND Type B insulin resistance belongs to a class of diseases caused by an autoantibody to a cell surface receptor. Blockade of insulin action results in hyperglycemia, hypercatabolism, severe acanthosis nigricans, and hyperandrogenism in women. This rare autoimmune disorder has been treated with various forms of immunosuppression with mixed success. METHODS We describe 14 patients with type B insulin resistance referred to the National Institutes of Health, adding to an existing cohort of 24 patients. This report focuses on seven patients who were treated with an intensive combination protocol of rituximab, cyclophosphamide, and pulse corticosteroids aimed at control of pathogenic autoantibody production. Hematological, metabolic, and endocrine parameters, including fasting glucose, glycated hemoglobin, insulin dose, lipids, and testosterone, were monitored before and after treatment. RESULTS All seven treated patients achieved remission, defined as amelioration of hyperglycemia, discontinuation of insulin therapy, and resolution of hyperandrogenism. Glycated hemoglobin has normalized in all seven treated patients. Remission was achieved on average in 8 months from initiation of treatment. The medication regimen was well tolerated, with no serious adverse events. CONCLUSIONS In seven patients with type B insulin resistance, standardized treatment with rituximab, cyclophosphamide, and pulse steroids results in remission of the disease. Future studies will determine whether this treatment protocol can be applied to other autoantibody/cell surface receptor disease states.

Effects of short-term sitagliptin treatment on immune parameters in healthy individuals, a randomized placebo-controlled study

Sitagliptin, a dipeptidyl‐peptidase 4 (DPP‐4) inhibitor, improves blood glucose control in patients with type 2 diabetes by blocking cleavage of glucagon‐like peptide 1 (GLP‐1). In type 2 diabetes patients sitagliptin use is associated with an increase in minor infections, and in new‐onset type 1 diabetes patients the ability of sitagliptin to dampen autoimmunity is currently being tested. DPP‐4, also known as CD26, is expressed on leucocytes and can inactivate many chemokines important for leucocyte migration, as well as act as a co‐stimulatory molecule on T cells. Therefore, this study was conducted to test whether sitagliptin is immunomodulatory. In this randomized, placebo‐controlled trial, healthy volunteers were given sitagliptin or placebo daily for 28 days, and blood was drawn for immune assays. No significant differences were observed in the percentage of leucocyte subsets within peripheral blood mononuclear cells (PBMCs), plasma chemokine/cytokine levels or cytokines released by stimulation of PBMCs with either lipopolysaccharide (LPS) or anti‐CD3. Individuals taking sitagliptin displayed increases in the percentage of cells expressing higher levels of CD26 at early time‐points compared to placebo controls, but these differences resolved by day 28 of treatment. Therefore, in healthy volunteers, treatment with sitagliptin daily for 28 days does not overtly alter systemic immune function.

Successful Treatment of Type B Insulin Resistance With Rituximab

Context: Type B insulin resistance is a very rare disease caused by autoantibodies against the insulin receptor. The mortality of type B insulin resistance is high (>50%), and management of this disease is not yet standardized. We report the successful treatment of a patient with type B insulin resistance with rituximab, cyclophosphamide, and prednisone. Case Description: A 45-year-old woman presented with unintended weight loss of 20 kg, unusually widespread acanthosis nigricans, and glucose levels > 500 mg/dL, which could not be controlled with up to 600 IU/d of insulin. Because of the severity of the insulin resistance combined with features of insulin deficiency, type B insulin resistance was suspected. Detection of high levels of insulin receptor autoantibodies confirmed the diagnosis. Neither immunosuppressive therapy with Ig iv nor plasmapheresis had an effect on glucose levels or insulin dose. Because the patients condition was deteriorating, we started rituximab (750 mg/m2 in two doses 2 wk apart) together with cyclophosphamide (100 mg/d orally) and dexamethasone 40 mg/d for 4 days. Two months after initiation of rituximab therapy, fasting glucose levels ranged from 80 to 110 mg/dL and could be controlled with very low insulin doses. Glycated hemoglobin decreased from 11.8 to 6.5%. Two months later, insulin therapy was stopped, and the patient showed normal blood glucose readings. Conclusion: In this patient with type B insulin resistance, Ig treatment and plasmapheresis failed to improve the condition. Finally, treatment with rituximab, cyclophosphamide, and steroids was successful in inducing a complete remission.

A gastrointestinal stromal tumor in a patient with multiple endocrine neoplasia type 2A and metastatic medullary thyroid cancer to the ovaries.

OBJECTIVE To describe the first reported case of a patient with multiple endocrine neoplasia type 2A and a gastrointestinal stromal tumor, as well as the second reported case of metastatic medullary thyroid cancer to the ovary. METHODS We present the clinical, imaging, surgical, and pathologic findings of the study patient and review the relevant literature. RESULTS A 57-year-old woman with a clinical diagnosis of multiple endocrine neoplasia type 2A presented with a new mass in the right lower quadrant. Surgical exploration identified a 5-cm pedunculated small-bowel mass approximately 25 cm from the ileocecal junction, as well as bilaterally firm ovaries. Bilateral oophorectomy revealed medullary thyroid cancer in both ovaries and fallopian tubes. Pathology of the resected mass revealed a gastrointestinal stromal tumor of uncertain malignant potential, mitotic rate of 1/50 per high-power field, with positive staining for c-kit and smooth muscle actin and negative staining for CD34 and S-100. CONCLUSIONS This case is the first description of a gastrointestinal stromal tumor in a patient with multiple endocrine neoplasia type 2A, potentially representing a new paraganglioma/gastrointestinal stromal tumor syndrome. This case also highlights the possibility of the ovary as a metastatic site for medullary thyroid cancer.

Tyrosine kinase inhibitors under investigation for the treatment of type II diabetes.

ABSTRACT Introduction: Type 2 diabetes is characterized by hyperglycemia that is the result of β-cell failure in the setting of peripheral insulin resistance. It is estimated that greater than 300 million individuals worldwide have diabetes. Tyrosine kinase inhibitors (TKIs), which are used to treat a variety of cancers, appear to have antihyperglycemic effects. Areas Covered: This review summarizes studies that have investigated the use of TKIs in animal models of diabetes. Additionally, the authors review case series describing the effects of TKIs on glucose levels in adults taking these drugs for FDA approved indications. Expert opinion: Given the scope and size of the worldwide diabetes epidemic, reports of amelioration or possible cure of the disease warrant special attention. TKIs appear to lower glucose levels in some, but not all individuals. Multi-center prospective studies are needed in which patient with diabetes treated with TKI undergo phenotyping to identify responders versus non responders to allow for precision medicine.

Pharmacokinetics, efficacy and safety of glyburide for treatment of gestational diabetes mellitus

ABSTRACT Introduction: Gestational diabetes mellitus (GDM) complicates 10% of all pregnancies and is defined as hyperglycemia first noted during pregnancy. Rates of GDM are rising and untreated GDM results in complications for both mother and fetus. GDM is often managed by diet and exercise but 30–40% of women will require pharmacological intervention. Insulin has traditionally been the treatment of choice but since 2007, glyburide, a second generation sulfonylurea has become the most prescribed medication for GDM. Areas covered: This review will cover the pharmacokinetics, efficacy, and safety of glyburide for the management of GDM. Expert opinion: Management of GDM is challenging secondary to the stringent glycemic goals that mimic the lower glucose levels in pregnancy. Glyburide is generally effective in treating hyperglycemia. However, several studies have raised safety concerns showing higher neonatal intensive care unit (NICU) admissions, higher rates of macrosomia, large for gestational age and pre-eclampsia in the mother. For this reason, insulin should be first-line therapy for GDM. In areas of limited resources where the self-monitoring needed for accurate insulin dosing is not possible, where access to refrigeration for insulin storage is not universal, or severe needle phobia then the benefits of glyburide (controlling hyperglycemia) outweighs the harm of NICU admissions and macrosomia.

Circulating cortisol-associated signature of glucocorticoid-related gene expression in subcutaneous fat of obese subjects.

Serum cortisol concentrations fluctuate in a circadian fashion, and glucocorticoids exert strong effects on adipose tissue and induce obesity through the glucocorticoid receptor.

GLP-1 receptor agonists in the treatment of polycystic ovary syndrome

ABSTRACT Introduction: Polycystic ovarian syndrome (PCOS) affects many women of child-bearing age and is characterized by hyperandrogenism, ovulatory and metabolic dysfunction. A primary treatment goal is weight reduction. The weight loss effects of glucagon-like peptide-1 receptor agonists (GLP-1RA), previously demonstrated in diabetic and obese non-diabetic patients, offer a unique opportunity to expand the medical options available to PCOS patients. Areas covered: Available clinical trials of glucagon-like peptide-1 receptor agonist therapy in PCOS were reviewed. Literature was searched from PubMed using appropriate search terms up to November 2016. Expert commentary: The available studies of GLP-1 RA therapy in the treatment of excess body weight in women with PCOS demonstrate that exenatide and liraglutide are effective in weight reduction either as monotherapy or in combination with metformin. A few studies showed that androgens may be modestly decreased and menstrual frequency may be increased. Eating behavior may be improved with liraglutide therapy. Glucose parameters are generally improved. GLP-1RAs were well-tolerated, with nausea being the most significant adverse side effect. Barriers to utilization may be the short duration studies, lack of familiarity of the medication, the route of administration (injection) and the variable outcomes on ovulation and hyperandrogenism.