Effect of colesevelam hydrochloride on glycemia and insulin sensitivity in men with the metabolic syndrome

Bile acids and microbes in metabolic disease

Bile acids (BAs) serve as physiological detergents that enable the intestinal absorption and transportation of nutrients, lipids and vitamins. BAs are primarily produced by humans to catabolize cholesterol and play crucial roles in gut metabolism, microbiota habitat regulation and cell signaling. BA-activated nuclear receptors regulate the enterohepatic circulation of BAs which play a role in energy, lipid, glucose, and drug metabolism. The gut microbiota plays an essential role in the biotransformation of BAs and regulates BAs composition and metabolism. Therefore, altered gut microbial and BAs activity can affect human metabolism and thus result in the alteration of metabolic pathways and the occurrence of metabolic diseases/syndromes, such as diabetes mellitus, obesity/hypercholesterolemia, and cardiovascular diseases. BAs and their metabolites are used to treat altered gut microbiota and metabolic diseases. This review explores the increasing body of evidence that links alterations of gut microbial activity and BAs with the pathogenesis of metabolic diseases. Moreover, we summarize existing research on gut microbes and BAs in relation to intracellular pathways pertinent to metabolic disorders. Finally, we discuss how therapeutic interventions using BAs can facilitate microbiome functioning and ease metabolic diseases.

Diabetes and Familial Hypercholesterolemia: Interplay between Lipid and Glucose Metabolism

Familial hypercholesterolemia (FH) is a genetic disease characterized by high low-density lipoprotein (LDL) cholesterol (LDL-c) concentrations that increase cardiovascular risk and cause premature death. The most frequent cause of the disease is a mutation in the LDL receptor (LDLR) gene. Diabetes is also associated with an increased risk of cardiovascular disease and mortality. People with FH seem to be protected from developing diabetes, whereas cholesterol-lowering treatments such as statins are associated with an increased risk of the disease. One of the hypotheses to explain this is based on the toxicity of LDL particles on insulin-secreting pancreatic β-cells, and their uptake by the latter, mediated by the LDLR. A healthy lifestyle and a relatively low body mass index in people with FH have also been proposed as explanations. Its association with superimposed diabetes modifies the phenotype of FH, both regarding the lipid profile and cardiovascular risk. However, findings regarding the association and interplay between these two diseases are conflicting. The present review summarizes the existing evidence and discusses knowledge gaps on the matter.

High-Intensity Statins Benefit High-Risk Patients: Why and How to Do Better

Review of the US and European literature indicates that most patients at high risk for atherosclerotic cardiovascular disease (ASCVD are not treated with high-intensity statins, despite strong clinical-trial evidence of maximal statin benefit. High-intensity statins are recommended for 2 categories of patients: those with ASCVD (secondary prevention) and high-risk patients without clinical ASCVD. Most patients with ASCVD are candidates for high-intensity statins, with a goal for low-density lipoprotein cholesterol reduction of 50% or greater. A subgroup of patients with ASCVD are at very high risk and can benefit by the addition of nonstatin drugs (ezetimibe with or without bile acid sequestrant or bempedoic acid and/or a proprotein convertase subtilisin/kexin type 9 inhibitor). High-risk primary prevention patients are those with severe hypercholesterolemia, diabetes with associated risk factors, and patients aged 40 to 75 years with a 10-year risk for ASCVD of 20% or greater. In patients with a 10-year risk of 7.5% to less than 20%, coronary artery calcium scoring is an option; if the coronary artery calcium score is 300 or more Agatston units, the patient can be up-classified to high risk. If high-intensity statin treatment is not tolerated in high-risk patients, a reasonable approach is to combine a moderate-intensity statin with ezetimibe. In very high-risk patients, proprotein convertase subtilisin/kexin type 9 inhibitors lower low-density lipoprotein cholesterol levels substantially and hence reduce risk as well.

Changes in Plasma Free Fatty Acids Associated with Type-2 Diabetes

Type 2 diabetes mellitus (T2DM) is associated with increased total plasma free fatty acid (FFA) concentrations and an elevated risk of cardiovascular disease. The exact mechanisms by which the plasma FFA profile of subjects with T2DM changes is unclear, but it is thought that dietary fats and changes to lipid metabolism are likely to contribute. Therefore, establishing the changes in concentrations of specific FFAs in an individual’s plasma is important. Each type of FFA has different effects on physiological processes, including the regulation of lipolysis and lipogenesis in adipose tissue, inflammation, endocrine signalling and the composition and properties of cellular membranes. Alterations in such processes due to altered plasma FFA concentrations/profiles can potentially result in the development of insulin resistance and coagulatory defects. Finally, fibrates and statins, lipid-regulating drugs prescribed to subjects with T2DM, are also thought to exert part of their beneficial effects by impacting on plasma FFA concentrations. Thus, it is also interesting to consider their effects on the concentration of FFAs in plasma. Collectively, we review how FFAs are altered in T2DM and explore the likely downstream physiological and pathological implications of such changes.

A novel analytical approach towards in-vitro bile acid binding studies to Colesevelam Hydrochloride tablets: An ultra-high performance liquid chromatography tandem mass spectrometric method

Colesevelam hydrochloride is a bile acid sequestrant used as a low density lipoprotein (LDL) reducing agent in hyperlipidemia with an additional advantage to improve glycemic control in type 2 diabetes patients. The objective of the study was to develop and validate a liquid chromatography tandem mass spectroscopic method for the simultaneous in-vitro estimation of bile acid salts of Glycocholic acid (GC), Glycochenodeoxycholic acid (GCDC) and Taurodeoxycholic acid (TDC) and its application in performing in-vitro binding study with Colesevelam Hydrochloride tablets. The method was developed using C-18 (50 x 4.6 mm, 3 μm) column with detection on negative ion mode and acquisition time of 3.5 min. The calibration range was linear from 0.0002 mM to 0.0065 mM for GC, 0.0002 mM to 0.0065 mM for GCDC and 0.0001 mM to 0.0021 mM for TDC. The precision was less than 3.0% and accuracy was found well within the range of 85 to 115%. The validated method was further applied to conduct in-vitro equilibrium binding study. The data was subjected to Langmuir isotherm and affinity constant (k₁) and capacity constant (k₂) were calculated.

Evidence connecting old, new and neglected glucose-lowering drugs to bile acid-induced GLP-1 secretion: A review

Bile acids are amphipathic water-soluble steroid-based molecules best known for their important lipid-solubilizing role in the assimilation of fat. Recently, bile acids have emerged as metabolic integrators with glucose-lowering potential. Among a variety of gluco-metabolic effects, bile acids have been demonstrated to modulate the secretion of the gut-derived incretin hormone glucagon-like peptide-1 (GLP-1), possibly via the transmembrane receptor Takeda G-protein-coupled receptor 5 and the nuclear farnesoid X receptor, in intestinal L cells. The present article critically reviews current evidence connecting established glucose-lowering drugs to bile acid-induced GLP-1 secretion, and discusses whether bile acid-induced GLP-1 secretion may constitute a new basis for understanding how metformin, inhibitors of the apical sodium-dependent bile acids transporter, and bile acid sequestrants - old, new and neglected glucose-lowering drugs - improve glucose metabolism.

Glucose-lowering effects of intestinal bile acid sequestration through enhancement of splanchnic glucose utilization

Intestinal bile acid (BA) sequestration efficiently lowers plasma glucose concentrations in type 2 diabetes (T2D) patients. Because BAs act as signaling molecules via receptors, including the G protein-coupled receptor TGR5 and the nuclear receptor FXR (farnesoid X receptor), to regulate glucose homeostasis, BA sequestration, which interrupts the entero-hepatic circulation of BAs, constitutes a plausible action mechanism of BA sequestrants. An increase of intestinal L-cell glucagon-like peptide-1 (GLP-1) secretion upon TGR5 activation is the most commonly proposed mechanism, but recent studies also argue for a direct entero-hepatic action to enhance glucose utilization. We discuss here recent findings on the mechanisms of sequestrant-mediated glucose lowering via an increase of splanchnic glucose utilization through entero-hepatic FXR signaling.

Atypical mechanism of glucose modulation by colesevelam in patients with type 2 diabetes

Colesevelam's glucose-lowering mechanism of action is not completely understood. Clinical trials of colesevelam suggest that its mechanism, and often adverse effects, differ from those of other oral antidiabetes drugs. Colesevelam does not affect insulin sensitivity (unlike thiazolidinediones), insulin secretion (unlike sulfonylureas and meglitinides), or early insulin response or glucagon (unlike dipeptidyl peptidase-4 inhibitors). Colesevelam may have some effect on glucose absorption, but likely via a different mechanism than α-glucosidase inhibitors. Colesevelam and metformin have similarities regarding hepatic glucose production, but divergent effects on gluconeogenesis versus glycogenolysis, suggesting differing mechanisms of drug action for improving glycemic control. Colesevelam is thought to be a portal glucagon-like peptide-1 (GLP-1) secretagogue with primarily hepatic effects. Bile acid binding by colesevelam leads to TGR5 activation, increased secretion of GLP-1 or other incretins, and inhibition of hepatic glycogenolysis. Colesevelam's mechanism of action appears to be atypical of other antidiabetes medications, making it a potentially suitable component of many combination regimens in the treatment of type 2 diabetes.

Colesevelam hydrochloride: evidence for its use in the treatment of hypercholesterolemia and type 2 diabetes mellitus with insights into mechanism of action

Colesevelam hydrochloride is a molecularly engineered, second-generation bile acid sequestrant demonstrating enhanced specificity for bile acids which has been approved for use as adjunctive therapy to diet and exercise as monotherapy or in combination with a β-hydroxymethylglutaryl-coenzyme A reductase inhibitor for the reduction of elevated low-density lipoprotein cholesterol in patients with primary hypercholesterolemia. It is also the only lipid-lowering agent currently available in the United States which has been approved for use as adjunctive therapy in patients with type 2 diabetes mellitus whose glycemia remains inadequately controlled on therapy with metformin, sulfonylurea, or insulin. With the recent emphasis upon drug safety by the Food and Drug Administration and various consumer agencies, it is fitting that the role of nonsystemic lipid-lowering therapies such as bile acid sequestrants – with nearly 90 years of in-class, clinically safe experience – should be reexamined. This paper presents information on the major pharmacologic effects of colesevelam, including a discussion of recent data derived from both in vitro and in vivo rodent and human studies, which shed light on the putative mechanisms involved.

Effects of sevelamer on HbA1c, inflammation, and advanced glycation end products in diabetic kidney disease

BACKGROUND AND OBJECTIVES

Increased inflammation and oxidative stress may be caused by proteins and lipids modified by cytotoxic advanced glycation end products (AGEs) in food. Restricting food containing elevated AGEs improves these risk factors in diabetic CKD. Because diet adherence can be problematic, this study aimed to remove cytotoxic AGEs from food already ingested and to determine whether sevelamer carbonate sequesters cytotoxic AGEs in the gut, preventing their uptake and thereby reducing AGE-induced abnormalities.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This single-center, randomized, 2-month, open-label, intention-to-treat, crossover study compared sevelamer carbonate with calcium carbonate treatment in stage 2-4 diabetic CKD. Participants received 2 months of treatment with one drug, had a 1-week washout, and then received the opposite drug for 2 months.

RESULTS

Sevelamer carbonate reduced HbA1c, serum methylglyoxal, serum (ε)N-carboxymethyl-lysine, triglycerides, and 8-isoprostanes. Total cholesterol and fibroblast growth factor 23 were reduced by sevelamer carbonate, relative to calcium carbonate. AGE receptor 1 and sirtuin 1 mRNA were increased and PMNC TNFα levels were decreased by sevelamer carbonate, but not calcium carbonate. Medications and caloric and AGE intake remained unchanged. Sevelamer carbonate reversibly bound AGE-BSA at intestinal, but not stomach, pH.

CONCLUSIONS

Sevelamer carbonate significantly reduces HbA1c, fibroblast growth factor 23, lipids, and markers of inflammation and oxidative stress, and markedly increases antioxidant markers, independently of phosphorus in patients with diabetes and early kidney disease. These novel actions of sevelamer carbonate on metabolic and inflammatory abnormalities in type 2 diabetes mellitus may affect progression of early diabetic CKD.

Bile acid receptors as targets for the treatment of dyslipidemia and cardiovascular disease

Dyslipidemia is an important risk factor for cardiovascular disease (CVD) and atherosclerosis. When dyslipidemia coincides with other metabolic disorders such as obesity, hypertension, and glucose intolerance, defined as the metabolic syndrome (MS), individuals present an elevated risk to develop type 2 diabetes (T2D) as well as CVD. Because the MS epidemic represents a growing public health problem worldwide, the development of therapies remains a major challenge. Alterations of bile acid pool regulation in T2D have revealed a link between bile acid and metabolic homeostasis. The bile acid receptors farnesoid X receptor (FXR) and TGR5 both regulate lipid, glucose, and energy metabolism, rendering them potential pharmacological targets for MS therapy. This review discusses the mechanisms of metabolic regulation by FXR and TGR5 and the utility relevance of natural and synthetic modulators of FXR and TGR5 activity, including bile acid sequestrants, in the treatment of the MS.