Microsomal triglyceride transfer protein inhibitor lomitapide-induced liver toxicity is ameliorated by Triiodothyronine treatment following improved bile homeostasis and β-oxidation

Dyslipidemia or its severe version like familial hypercholesterolemia causes a high risk for cardiovascular diseases. Lomitapide, a microsomal triglyceride transfer protein inhibitor, is approved to treat familial hypercholesterolemia, associated with liver fat accumulation. In this work, we investigated the effect of the combination of lomitapide and triiodothyronine (T3) in Zucker fatty rats. Lomitapide (1 mg/kg, PO), or T3 (13 μg/kg, PO), or their combination, were given to these rats once daily for fourteen days. Body weight and food intake were recorded once daily during the treatment period. Serum and hepatic lipids, glucose tolerance, serum aminotransferases, bile fluids, hepatic gene expression, and liver histology were assessed at the end of the treatment. Lomitapide treatment reduced body weight, food intake, glucose intolerance, and serum lipids, and elevated serum aminotransferases and liver lipids. When combined with T3, lomitapide showed an enhanced reduction in body weight, food intake, serum cholesterol, serum LDL, and glucose intolerance. The combination treatment increased bile flow rate and biliary cholesterol excretion rate. Combining T3 with lomitapide attenuated the elevation of serum aminotransferases and liver lipids. Hepatic ABCB11, ABCG5, ABCG8, CYP7A1, CPT1, and ACOX1 expressions were increased with combination treatment. Histological analysis indicated that T3 attenuated hepatic fat accumulation caused by lomitapide. These data suggests that combining lomitapide with T3 may reduce lomitapide-induced hepatic toxicity and provide additional benefits in obesity and glucose intolerance.

Effect of dual PPAR-α/γ agonist saroglitazar on diabetic retinopathy and oxygen-induced retinopathy

Diabetic retinopathy is a serious complication of diabetes, marked by retinal vascular damage, inflammation, and angiogenesis. This study's objective was to assess the potential benefits of saroglitazar, a peroxisome proliferator-activated receptor-alpha/gamma (PPAR-α/γ) agonist in diabetic retinopathy. Diabetic retinopathy was induced by streptozotocin in Sprague Dawley rats. The effect of saroglitazar was also assessed in the oxygen-induced retinopathy model in newborn rats and VEGF-induced angiogenesis in the chick chorioallantoic membrane (CAM) assay. Treatment of saroglitazar (1 and 4 mg/kg, oral) for 12 weeks significantly ameliorated retinal vascular leakage and leukostasis in the diabetic rats. Saroglitazar decreased oxidative stress, VEGF receptor signalling, NF-κBp65, and ICAM-1 in the retina of diabetic rats. The beneficial effects of saroglitazar (1 and 4 mg/kg, oral) were also observed on the neovascularization in oxygen-induced retinopathy in newborn rats. Saroglitazar also reduced VEGF-induced angiogenesis in CAM assay. This study reveals that saroglitazar has the potential to prevent the progression of retinopathy in diabetic patients.

In vivo antidiabetic activity of nimesulide due to inhibition of amino acid transport

Inhibiting the intestinal and renal neutral amino acid transporter B0AT1 by genetic means has improved insulin sensitivity in mice, but there are no antagonists available for preclinical or clinical use. Since the anti-inflammatory agent nimesulide selectively inhibited B0AT1 in vitro, we hypothesized that nimesulide exhibits in vivo potential to restrict neutral amino acid absorption and, therefore, may improve insulin sensitivity. The dose-related effect of nimesulide (10 to 100 mg/kg, PO) on intestinal absorption of neutral amino acids was estimated in C57 mice. The effect of nimesulide (50 mg/kg, PO) on renal resorption of amino acids was also assessed. The effect of chronic nimesulide (50 mg/kg, PO, BID for 14 days) was assessed in high protein diet-fed C57 mice, diet-induced obese mice and obese and diabetic db/db mice. Acute and chronic nimesulide treatment decreased absorption of neutral amino acids and increased their urinary excretion. Nimesulide treatment improved insulin sensitivity and glycemic control, increased GLP-1, decreased liver lipids and improved FGF-21 in serum. Nimesulide improved insulin sensitivity and glucose tolerance by inhibiting neutral amino acid transport in the intestine and kidneys. Thus, it can serve as a tool compound for in vivo B0AT1 inhibition.

Hepcidin inhibition improves iron homeostasis in ferrous sulfate and LPS treatment model in mice

BACKGROUND

Hepcidin, a liver-derived peptide, regulates the absorption, distribution, and circulation of iron in the body. Inflammation or iron overload stimulates hepcidin release, which causes the accumulation of iron in tissues. The inadequate levels of iron in circulation impair erythropoiesis. Inhibition of hepcidin may increase iron in circulation and improve efficient erythropoiesis. Activin-like kinase (ALK) inhibitors decrease hepcidin.

METHODS

In this work, we have investigated an ALK inhibitor LDN193189 for its efficacy in iron homeostasis. The effect of LDN193189 treatment was assessed in C57BL6/J mice, in which hepcidin was induced by either ferrous sulfate or lipopolysaccharide (LPS) injection.

RESULTS

After two hours of treatment, ferrous sulfate increased serum and liver iron, serum hepcidin, and liver hepcidin expression. On the other hand, LPS reduced serum iron in a dose-related manner after six hours of treatment. LDN193189 treatment increased serum iron, decreased spleen and liver iron, decreased serum hepcidin and liver hepcidin expression in ferrous sulfate-treated mice, and increased serum iron in LPS-induced hypoferremia. We observed that ferrous sulfate caused a significantly higher increase in liver iron, serum hepcidin, and liver hepcidin than turpentine oil or LPS in mice. Iron dextran (intraperitoneal or intravenous) increased serum iron, but LDN193189 did not show hyperferremia with iron dextran stimulus.

CONCLUSION

Ferrous sulfate-induced hyperferremia can be a valuable and rapid screening model for assessing the efficacy of hepcidin inhibitors.

Combination of Lorcaserin and GLP-1/glucagon Coagonist Improves Metabolic Dysfunction in Diet Induced-obese Mice

BACKGROUND

Obesity and diabetes are major metabolic disorders that progress to severe morbidity and mortality. Neuroendocrine mechanisms controlling energy balance indicate that combination therapies are needed to sustain weight loss. Lorcaserin was one of the approved therapies for the treatment of obesity, which is recently withdrawn because a safety clinical trial, shows an increased occurrence of cancer. Coagonist of glucagon-like-peptide-1 (GLP-1) and glucagon receptors is a novel investigational therapy demonstrated to have both anti-obesity and anti-diabetic effect. Here, we investigated the effect of combination of lorcaserin and a GLP-1 and glucagon receptors coagonist in diet-induced obese (DIO) mice model.

METHODS

The diet-induced obese C57BL/6J mice were used to assess acute and chronic effect of lorcaserin, coagonist of GLP-1and glucagon receptors and their combination on food intake, body weight, and biochemical parameters.

RESULTS

In acute study, combination of lorcaserin and coagonist causes synergistic reductions in food intake and body weight. Repeated treatment of combination of lorcaserin and coagonist showed enhanced body weight loss over time, which is due to reduction in fat mass (subcutaneous, retroperitoneal, mesenteric and epididymal fat pad) compared to individual therapy. Also, suppression of locomotor activity seen with lorcaserin was not evident in combination with coagonist. No additive effect was observed in glucose tolerance (intraperitoneal glucose tolerance test or insulin tolerance test), serum lipids, hepatic lipids, and energy expenditure in combination group.

CONCLUSION

These data suggest that combination of lorcaserin and coagonist could be a better combination to induce body weight loss.