Intracellular retention of hepatic serpins caused by severe hyperlipidemia

GLP-1 receptor agonists in the treatment of diabetic non-alcoholic steatohepatitis patients

INTRODUCTION

Nonalcoholic fatty liver disease (NAFLD) is the most common hepatic disease affecting almost 30% of the world population. Approximately 25% of people with NAFLD develop nonalcoholic steatohepatitis (NASH), the fulminant version of the disease. Diabetes mellitus is present in 22.5% of people with NAFLD and 44.60% of individuals with NASH. This review was undertaken to examine the current contribution of glucagon-like peptide 1 (GLP-1) receptor agonists to the pharmacotherapy of diabetic nonalcoholic steatohepatitis.

AREAS COVERED

The author analyzed the current status of GLP-1 receptor agonists for pharmacotherapy of diabetic NASH. Research data and literature reports were taken from the database and or websites of Diabetes UK, American Diabetes Association, ClinicalTrials.gov, PubMed, and Scopus. The keywords utilized included type 2 diabetes, GLP-1, NASH, NAFLD, and clinical trials.

EXPERT OPINION

Since diabetic NASH is associated with obesity, diabetes mellitus, oxidative stress and inflammation, drugs capable of mitigating all of these conditions simultaneously, are most ideal for the treatment of diabetic NASH. These drugs include (in order of relevance), GLP-1 receptor agonists, GLP-1 and GIP dual receptor agonists, sodium-glucose co-transporter-2 (SGLT2) inhibitors, and pioglitazone. The future, FDA-approved drug for diabetic NASH treatment will likely be GLP-1 agonist, which could be used as monotherapy or in combination with other drugs.

Dietary ginger polysaccharides (Gps) improve symptoms in hyperlipidemia rats via alterations in gut microbiota

The aim of this research is to investigate lipid-lowering influence of dietary ginger (Zingier officinales Rocs) polysaccharides (GP_S) on hyperlipidemia rats. Rat models with hyperlipidemia was established by high-fat food diet (HFD). Comparing to GP-negative model group, GP_S attenuated several effects of HFD feeding, including the levels of blood lipid biochemistry, serum inflammatory markers (tumor necrosis factor TNF-a, interleukin IL-6), antioxidant capacity (superoxide dismutase SOD, glutathione peroxidase GSH-Px, total antioxidant capacity T-AOC, propylene dialdehyde MDA), uric acid and immune index. 16 S rDNA gene sequencing of fecal samples showed that GP_S increased the growth of Akkermansia muciniphila and decreased the proportion of Firmicutes to Bacteroidetes; This changes in microbial community structure can help prevent diet-induced metabolic disease. These results suggest that GPs may act on the gut, changing the structure of the gut microbial community, thereby reducing intestinal and systemic inflammation, thus improved metabolic outcomes.

The influence of restrictive feeding of chickens on the microscopic structure of their liver

This paper describes the morphologic structure of chickens’ livers as a result of restrictive feeding in variable intensity. This experiment was performed on 96 chickens of two hybrids (Ross 308 and Cobb 500) of both sexes. The chickens were divided into 3 groups (control group and two groups with restricted feeding). There were 8 chickens in each group. After hatching, the control group was fed a standard mixture ad libitum. The first restricted group was fed 80% ad libitum from the age of 2 weeks. The second restricted group, from the age of 2 weeks, was fed 65% ad libitum. The experiment lasted for 5 weeks. The liver samples were obtained by necropsy, then weighed, and after this processed by standard histological methods. The slices of liver were stained with haematoxyline-eosin. The liver samples were evaluated both objectively and subjectively. In the control group, steatosis and marginal pathological acute venosis hyperaemia were found. In the group with 80% restriction, perilobular steatosis was observed. In the group with 65% restriction, centrolobular steatosis was observed. Controlled measurement of the average hepatocyte thickness in the individual sample groups was performed using an objective method. The hepatocyte diameter thickness of males was higher than the hepatocyte diameter thickness of females, which was significant (P < 0.001). This is the first work providing the possibility of morphometrical verification of the time factor including other morphological criteria.

Inhibition of proteasome by bortezomib causes intracellular aggregation of hepatic serpins and increases the latent circulating form of antithrombin

Conformational diseases include heterogeneous disorders sharing a similar pathological mechanism, leading to intracellular aggregation of proteins with toxic effects. Serpins are commonly involved in these diseases. These are structurally sensitive molecules that modify their folding under even minor genetic or environmental variations. Indeed, under normal conditions, the rate of misfolding of serpins is high and unfolded serpins must be degraded by the proteasome system. Our aim was to study the effects of bortezomib, a proteasome inhibitor, on conformationally sensitive serpins. The effects of bortezomib were analysed in patients with multiple myeloma, HepG2 cells, and Swiss mice, as well as in vitro. Levels, anti-FXa activity, heparin affinity, and conformational features of antithrombin, a relevant anticoagulant serpin, were analysed. Histological, ultrastructural features and immunohistological distribution of antithrombin and alpha1-antitrypsin (another hepatic serpin) were evaluated. We also studied the intracellular accumulation of conformationally sensitive (fibrinogen) or non-sensitive (prothrombin) hepatic proteins. The inhibition of the proteasome caused intracellular accumulation and aggregation of serpins within the endoplasmic reticulum that was associated with confronting cisternae and Mallory body formation. These effects were accompanied by a heat stress response. Bortezomib also increased the levels of intracellular fibrinogen, but has no significant effect on prothrombin. Finally, bortezomib had only minor effects on the mature circulating antithrombin, with increased amounts of latent antithrombin in plasma. These results suggest that the impairment of proteasomal activities leads to an intracellular accumulation of conformationally sensitive proteins and might facilitate the release of misfolded serpins into circulation where they adopt more stable conformations.

In vivo effects of hyperthermia on the functional and conformational characteristics of antithrombin

BACKGROUND

High temperatures produce in vitro transitions of antithrombin to its inactive latent and polymeric forms. Accordingly, high body temperatures might contribute in vivo to conformational changes in antithrombin associated with increased thrombotic risk.

METHODS

We assessed the in vivo effects of different hyperthermic stimuli on antithrombin. We studied two mouse models of hyperthermia. (i) Febrile syndrome induced by turpentine. (ii) Heat stroke generated by exposure to 42 degrees C. Body temperatures were measured. Antigen, anti-factor Xa activity and conformational features of plasma antithrombin were studied. Furthermore, structural and ultrastructural features from livers were analyzed. Intracellular retention of serpins (antithrombin and alpha1-antitrypsin) was studied by western-blotting, immunohistochemistry, and immunogold-labeling-electron microscopy.

RESULTS

Hyperthermic stimuli caused a moderate deficiency of circulating antithrombin and a slight increase in its latent form. Moreover, hyperthermia caused intracellular retention of antithrombin into aggregates within the lumen of the endoplasmic reticulum of hepatocytes. This effect was similar for alpha1-antitrypsin.

CONCLUSION

Hyperthermia causes minor conformational changes on circulating antithrombin in vivo, although it has severe consequences for intracellular antithrombin and other hepatic serpins, inducing the intracellular retention of the nascent protein. These effects may contribute to the moderate plasma deficiency of antithrombin and the increased thrombotic risk detected in hyperthermic conditions.