A Novel Small Molecule 1,2,3,4,6-penta-O-galloyl-α-D-glucopyranose Mimics the Antiplatelet Actions of Insulin

BACKGROUND: We have shown that 1,2,3,4,6-penta-O-galloyl-α-D-glucopyranose (α-PGG), an orally effective hypoglycemic small molecule, binds to insulin receptors and activates insulin-mediated glucose transport. Insulin has been shown to bind to its receptors on platelets and inhibit platelet activation. In this study we tested our hypothesis that if insulin possesses anti-platelet properties then insulin mimetic small molecules should mimic antiplatelet actions of insulin. PRINCIPAL FINDINGS: Incubation of human platelets with insulin or α-PGG induced phosphorylation of insulin receptors and IRS-1 and blocked ADP or collagen induced aggregation. Pre-treatment of platelets with α-PGG inhibited thrombin-induced release of P-selectin, secretion of ATP and aggregation. Addition of ADP or thrombin to platelets significantly decreased the basal cyclic AMP levels. Pre-incubation of platelets with α-PGG blocked ADP or thrombin induced decrease in platelet cyclic AMP levels but did not alter the basal or PGE(1) induced increase in cAMP levels. Addition of α-PGG to platelets blocked agonist induced rise in platelet cytosolic calcium and phosphorylation of Akt. Administration of α-PGG (20 mg kg(-1)) to wild type mice blocked ex vivo platelet aggregation induced by ADP or collagen. CONCLUSIONS: These data suggest that α-PGG inhibits platelet activation, at least in part, by inducing phosphorylation of insulin receptors leading to inhibition of agonist induced: (a) decrease in cyclic AMP; (b) rise in cytosolic calcium; and (c) phosphorylation of Akt. These findings taken together with our earlier reports that α-PGG mimics insulin signaling suggest that inhibition of platelet activation by α-PGG mimics antiplatelet actions of insulin

Consequences of both coxsackievirus B4 and type 1 diabetes on female non-obese diabetic mouse kidneys

Despite the 2019 Executive Order on Advancing American Kidney Health Initiative, kidney disease has moved up in rank from the 9th to the 8th leading cause of death in the United States. A recent push in the field of nephrology has been to identify molecular markers and/or molecular profiles involved in kidney disease process or injury that can help identify the cause of injury and predict patient outcomes. While these studies have had moderate success, they have not yet considered that many of the health conditions that cause kidney disease (diabetes, hypertension, etc.) can also be caused by environmental factors (such as viruses), which in and of themselves can cause kidney disease. Thus, the goal of this study was to identify molecular and phenotypic profiles that can differentiate kidney injury caused by diabetes (a health condition resulting in kidney disease) and coxsackievirus B4 (CVB4) exposure (which can cause diabetes and/or kidney disease), both alone and together. Non-obese diabetic (NOD) mice were used for this study due to their susceptibility to both type 1 diabetes (T1D)-and CVB4-mediated kidney injury, in order to glean a better understanding of how hyperglycemia and viral exposure, when occurring on their own and in combination, may alter the kidneys’ molecular and phenotypic profiles. While no changes in kidney function were observed, molecular biomarkers of kidney injury were significantly up-and downregulated based on T1D and CVB4 exposure, both alone and together, but not in a predictable pattern. By combining individual biomarkers with function and phenotypic measurements (i.e., urinary albumin creatinine ratio, serum creatinine, kidney weight, and body weight), we were able to perform an unbiased separation of injury group based on the type of injury. This study provides evidence that unique kidney injury profiles within a kidney disease health condition are identifiable, and will help us to identify the causes of kidney injury in the future

Diet Is Critical for Prolonged Glycemic Control after Short-Term Insulin Treatment in High-Fat Diet-Induced Type 2 Diabetic Male Mice

<div><p>Background</p><p>Clinical studies suggest that short-term insulin treatment in new-onset type 2 diabetes (T2DM) can promote prolonged glycemic control. The purpose of this study was to establish an animal model to examine such a “legacy” effect of early insulin therapy (EIT) in long-term glycemic control in new-onset T2DM. The objective of the study was to investigate the role of diet following onset of diabetes in the favorable outcomes of EIT.</p><p>Methodology</p><p>As such, C57BL6/J male mice were fed a high-fat diet (HFD) for 21 weeks to induce diabetes and then received 4 weeks of daily insulin glargine or sham subcutaneous injections. Subsequently, mice were either kept on the HFD or switched to a low-fat diet (LFD) for 4 additional weeks.</p><p>Principal Findings</p><p>Mice fed a HFD gained significant fat mass and displayed increased leptin levels, increasing insulin resistance (poor HOMA-IR) and worse glucose tolerance test (GTT) performance in comparison to mice fed a LFD, as expected. Insulin-treated diabetic mice but maintained on the HFD demonstrated even greater weight gain and insulin resistance compared to sham-treated mice. However, insulin-treated mice switched to the LFD exhibited a better HOMA-IR compared to those mice left on a HFD. Further, between the insulin-treated and sham control mice, in spite of similar HOMA-IR values, the insulin-treated mice switched to a LFD following insulin therapy did demonstrate significantly better HOMA-B% values than sham control and insulin-treated HFD mice.</p><p>Conclusion/Interpretation</p><p>Early insulin treatment in HFD-induced T2DM in C57BL6/J mice was only beneficial in animals that were switched to a LFD after insulin treatment which may explain why a similar legacy effect in humans is achieved clinically in only a portion of cases studied, emphasizing a vital role for diet adherence in diabetes control.</p></div

Phenylmethimazole abrogates diet-induced inflammation, glucose intolerance and NAFLD

© 2018 Society for Endocrinology. Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of both metabolic and inflammatory diseases and has become the leading chronic liver disease worldwide. High-fat (HF) diets promote an increased uptake and storage of free fatty acids (FFAs) and triglycerides (TGs) in hepatocytes, which initiates steatosis and induces lipotoxicity, inflammation and insulin resistance. Activation and signaling of Toll-like receptor 4 (TLR4) by FFAs induces inflammation evident in NAFLD and insulin resistance. Currently, there are no effective treatments to specifically target inflammation associated with this disease. We have established the efficacy of phenylmethimazole (C10) to prevent lipopolysaccharide and palmitate-induced TLR4 signaling. Because TLR4 is a key mediator in pro-inflammatory responses, it is a potential therapeutic target for NAFLD. Here, we show that treatment with C10 inhibits HF diet-induced inflammation in both liver and mesenteric adipose tissue measured by a decrease in mRNA levels of pro-inflammatory cytokines. Additionally, C10 treatment improves glucose tolerance and hepatic steatosis despite the development of obesity due to HF diet feeding. Administration of C10 after 16 weeks of HF diet feeding reversed glucose intolerance, hepatic inflammation, and improved hepatic steatosis. Thus, our findings establish C10 as a potential therapeutic for the treatment of NAFLD

Schematic design of experiments.

<p>4 week-old mice were fed a HFD (H) or a LFD (L) for 21 weeks and then received either daily subcutaneously-injected insulin Glargine (HI) or sham phosphate-buffered saline (HS) for 4 weeks. Mice were then kept on a HFD (HHI or HHS) or switched to a LFD (HLI or HLS) for 4 more weeks before being killed. Another group of mice fed a LFD throughout the study received sham treatment and served as controls (LS). A schematic diagram illustrating the different treatment groups is shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0117556#pone.0117556.g001" target="_blank">Fig. 1</a>.</p

Changes in body weight, composition, blood C-peptide/insulin, and Leptin levels in different groups of mice (A) Mice fed a HFD gained significant body weight when compared to that of LFD mice (***p<0.001, H vs. L).

<p>After the treatment period, insulin-treated HFD mice were significantly heavier, when compared to sham-treated HFD mice (*p<0.05, HI vs. HS). At the end of the experiment, mice that were switched to a LFD were lighter than HFD mice (**p<0.01, HLS vs. HHS and HLI vs. HHI). (B) Body composition was determined by a benchtop nuclear magnetic resonance analyzer. Before initiating and after terminating treatment, mice fed a HFD were fatter (fat mass in white), compared with that of LFD fed mice (***p<0.001, L vs. H and LS vs. HS and HI). At the end of the experiment, mice that switched to the LFD lost more fat mass, when compared to mice kept on a HFD (***p<0.001, HLI vs. HHI; **p<0.01 HLS vs. HHS). (C) Prior to treatment, blood C-peptide/insulin levels were significantly greater in HFD fed mice, in comparison to that in LFD controls (***p<0.001, H vs. L). In the end of experimental period, Sham treated control mice that were kept on HFD displayed increased plasma insulin levels than those switched to LFD after treatment (*p<0.05, HLS vs. HHS) (n = 6–8 per group). (D) Prior to treatment, mice fed a HFD demonstrated higher blood levels of leptin than LFD fed mice (***p<0.001, H vs. L). At the end of the experiment, mice that were kept on the HFD continued to show high levels of leptin compared to mice switched to the LFD regardless of therapy (**p<0.01, HHI vs. HLI; *p<0.05, HHS vs. HLS).</p

Changes in HOMA-IR and HOMA-B values after insulin therapy.

<p>Changes in HOMA-IR and HOMA-B values after insulin therapy. Prior to treatment, HOMA-IR values (A)and HOMA-B (B) were significantly greater in HFD fed mice, in comparison to that in LFD controls (***p<0.001, H vs. L). At the end of the experiment, the insulin-treated mice that were kept on the HFD after treatment displayed worse HOMA-IR levels (A) in comparison to mice switched to the LFD after treatment (***p<0.001, **p<0.01, *p<0.05, HHI vs. HLI). Moreover, the latter demonstrated a significantly improved HOMA-B value than that of sham controls (*p<0.05, HLI vs. HLS) despite similar HOMA-IR values.</p

Effect of short-term insulin therapy on glycemic control.

<p>(A) and (B) Mice fed a HFD showed worse GTT performance, when compared to that of mice fed a LFD (***p<0.001, and *p<0.05, H vs. L). (C) and (D) Insulin therapy significantly enhanced GTT performance in HFD mice, in comparison to that of sham controls (***p<0.001, **p<0.01, and *p<0.05, HI vs. HS). (E) and (F) At the end of the experiment, insulin-treated mice that switched to a LFD after treatment demonstrated significantly better GTT performance, in comparison to that of sham controls (*p<0.05, HLI vs. HLS at 15 and 30 min). Conversely, insulin-treated mice that were kept on a HFD until the end of the experiment exhibited much worse GTT performance, in comparison to that of mice switched to the LFD (**p<0.01, and *p<0.05, HHI vs. HLI).</p

Effect of insulin therapy on islet inflammation and apoptosis.

<p>Whilst no apoptosis was identified in islets from LFD controls (A), TUNEL-positive cells were found in pancreatic tissues from HFD fed mice (B-E), but were not different between treatment groups (F). Of note, special attention was paid to assess peri-insulitis and none was identified. Scale bar = 10 μm.</p