Marlei Josiele Augusto

Nonalcoholic Steatohepatitis: A Search for Factual Animal Models

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis, which occurs in the absence of alcohol abuse. NAFLD can evolve into progressive liver injury and fibrosis in the form of nonalcoholic steatohepatitis (NASH). Several animal models have been developed to attempt to represent the morphological, biochemical, and clinical features of human NASH. The actual review presents a critical analysis of the most commonly used experimental models of NAFLD/NASH development. These models can be classified into genetic, nutritional, and a combination of genetic and nutritional factors. The main genetic models are ob/ob and db/db mutant mice and Zucker rats. The principal nutritional models employ methionine- and choline-deficient, high-fat, high-cholesterol and high-cholate, cafeteria, and high-fructose diets. Currently, associations between high-fructose and various compositions of high-fat diets have been widely studied. Previous studies have encountered significant difficulties in developing animal models capable of reproducing human NASH. Some models produce consistent morphological findings, but the induction method differs significantly compared with the pathophysiology of human NASH. Other models precisely represent the clinical and etiological contexts of this disease but fail to provide accurate histopathological representations mainly in the progression from steatosis to liver fibrosis.

Riboflavin (vitamin B-2) reduces hepatocellular injury following liver ischaemia and reperfusion in mice

Riboflavin has been shown to exhibit anti-inflammatory and antioxidant properties in the settings of experimental sepsis and ischaemia/reperfusion (I/R) injury. We investigated the effect of riboflavin on normothermic liver I/R injury. Mice were submitted to 60 min of ischaemia plus saline or riboflavin treatment (30 μmoles/kg BW) followed by 6 h of reperfusion. Hepatocellular injury was evaluated by aminotransferase levels, reduced glutathione (GSH) content and the histological damage score. Hepatic neutrophil accumulation was assessed using the naphthol method and by measuring myeloperoxidase activity. Hepatic oxidative/nitrosative stress was estimated by immunohistochemistry. Liver endothelial and inducible nitric oxide synthase (eNOS/iNOS) and nitric oxide (NO) amounts were assessed by immunoblotting and a chemiluminescence assay. Riboflavin significantly reduced serum and histological parameters of hepatocellular damage, neutrophil infiltration and oxidative/nitrosative stress. Furthermore, riboflavin infusion partially recovered hepatic GSH reserves and decreased the liver contents of eNOS/iNOS and NO. These data indicate that riboflavin exerts antioxidant and anti-inflammatory effects in the ischaemic liver, protecting hepatocytes against I/R injury. The mechanism of these effects appears to be related to the intrinsic antioxidant potential of riboflavin/dihydroriboflavin and to reduced hepatic expression of eNOS/iNOS and reduced NO levels, culminating in attenuation of oxidative/nitrosative stress and the acute inflammatory response.

Congenital Zika Virus Infection Induces Severe Spinal Cord Injury

We report 2 fatal cases of congenital Zika virus (ZIKV) infection. Brain anomalies, including atrophy of the cerebral cortex and brainstem, and cerebellar aplasia were observed. The spinal cord showed architectural distortion, severe neuronal loss, and microcalcifications. The ZIKV proteins and flavivirus-like particles were detected in cytoplasm of spinal neurons, and spinal cord samples were positive for ZIKV RNA.

Aflatoxin B1 residues in human livers and their relationship with markers of hepatic carcinogenesis in São Paulo, Brazil

Graphical abstract

The comparative efficacy of renin-angiotensin system blockers in schistosomal hepatic fibrosis

Schistosomiasis mansoni is involved in hepatic fibrogenesis and portal hypertension. Previous studies proved that blockade of some components of the renin-angiotensin system (RAS) reduce liver fibrogenesis. However, the effects of inhibition of early stages of RAS pathway in schistosomal fibrosis have not been studied yet. Thus, the aim of this study was to compare the role of different antihypertensive drugs on hepatic fibrosis in murine schistosomiasis. BALB/c mice (n = 50) weighing 20g were subjected to inoculation of 50 cercariae and submitted to different treatments: aliskiren, 50 mg/kg (n = 10); bradykinin, 2 μg/kg (n = 5); losartan, 10 mg/kg (n = 10); lisinopril 10 mg/kg (n = 5) and control, proportional volume vehicle (n = 5); daily for 14 weeks. Six animals were not subjected to cercariae inoculation or any type of treatment. Ultrasound, histological, immunohistochemical and proteomic analyzes were performed to evaluate markers associated with hepatic fibrogenesis. The hepatic areas stained with Sirius red and thenumber of cells marked by α-SMA in animals treated with aliskiren, bradykinin, lisinopril and losartan were diminished when compared to control group, demonstrating reduced hepatic fibrosis after RAS blockade. These results were reinforced by ultrasonography analysis and protein expression of TGFβ. These findings demonstrated the effect of RAS inhibition on hepatic fibrosis in murine schistosomiasis, with the most evident results being observed in the losartan and aliskiren treated groups. The main mechanisms underlying this process appear to involve anti-fibrogenic activity through the inhibition of collagen and TGFβ synthesis.

Effect of Gallic Acid on Regression of Murine CCL4-Induced Hepatic Cirrhosis

Hepatic cirrhosis can be induced by chronic exposure to reactive oxygen species (ROS). However, phenolic compounds, such as gallic acid (GA), appear to inhibit ROS-induced oxidative stress. We aimed to investigate the effects of GA on murine hepatic fibrogenesis. The effects of GA were evaluated on the regression of liver cirrhosis that was induced by chronic intraperitoneal CCl4 administration (20% v/v) in C57 mice for a period of 10 weeks. The animals were treated intraperitoneally and distributed in three groups, as follows: SHAM group – 8 weeks with Olive oil (CCL4 solution vehicle); C group – 8 weeks with CCL4 solution, and then 2 more weeks with deionized water (Gallic Acid solution vehicle); and C + GA group – 8 weeks with CCL4 solution, and then 2 more weeks with Gallic Acid solution (100 mg/Kg/day) on alternated days. The cirrhosis and inflammation-related factors were estimated using histological, western blotting and PCR-RT analysis. There was a significant decrease in the collagen deposition, as indicated by Sirius red staining, in the C + GA group compared to the C group (p<0.05). This improvement was accompanied by a reduction in the number of α-SMA-positive cells observed in these animals (p<0.05). The expression of the Procollagen α1(I), TGFβ1 and TIMP1 genes was also diminished by GA administration compared to the control (p<0.001). Additionally, proteomic studies revealed reduced p65 NFκB and p38 MAPK protein levels in the C + GA group. These findings reveal the effect of GA on the regression of cirrhosis. The mechanisms of this process might involve the anti-inflammatory activity of GA, which represses the TGFβ1, p65 NFκB, and p38 MAPK-mediated signaling pathways.