The protection of hepatocyte cells from the effects of oxidative stress by treatment with vitamin E in conjunction with DTT

Hepatocyte Thorns, A Novel Drug-Induced Stress Response in Human and Mouse Liver Spheroids

The in vivo-relevant phenotype of 3D liver spheroids allows for long-term studies of, e.g., novel mechanisms of chronic drug-induced liver toxicity. Using this system, we present a novel drug-induced stress response in human and murine hepatocyte spheroids, wherein long slender filaments form after chronic treatment with four different drugs, of which three are PPARα antagonists. The morphology of the thorns varies between donors and the compounds used. They are mainly composed of diverse protein fibres, which are glycosylated. Their formation is inhibited by treatment with fatty acids or antioxidants. Treatment of mice with GW6471 revealed changes in gene and protein expression, such as those in the spheroids. In addition, similar changes in keratin expression were seen following the treatment of hepatotoxic drugs, including aflatoxin B1, paracetamol, chlorpromazine, cyclosporine, and ketoconazole. We suggest that thorn formation may be indicative of hepatocyte metaplasia in response to toxicity and that more focus should be placed on alterations of ECM-derived protein expression as biomarkers of liver disease and chronic drug-induced hepatotoxicity, changes that can be studied in stable in vivo-like hepatic cell systems, such as the spheroids.

Relationship between redox status and cell fate in immunity and autoimmunity

SIGNIFICANCE

The signaling function of redox molecules is essential for an efficient and proper execution of a large number of cellular processes, contributing to the maintenance of cell homeostasis. Excessive oxidative stress is considered as playing an important role in the pathogenesis of autoimmune diseases by enhancing inflammation and breaking down the immunological tolerance through protein structural modifications that induce the appearance of neo/cryptic epitopes.

RECENT ADVANCES

There is a complex reciprocal relationship between oxidative stress and both apoptosis and autophagy, which is essential to determine cell fate. This is especially relevant in the context of autoimmune disorders in which apoptosis and autophagy play a crucial pathogenic role.

CRITICAL ISSUES

In this review, we describe the latest developments with regard to the involvement of redox molecules in the initiation and progression of autoimmune disorders, focusing on their role in cell fate regulation. We also discuss new therapeutic approaches that target oxidative stress in the treatment of these disorders. The administration of antioxidants is scarcely studied in autoimmunity, and future analyses are needed to assess its beneficial effects in preventing or ameliorating these diseases.

FUTURE DIRECTIONS

Deciphering the intricate relationships between oxidative stress and both apoptosis and autophagy in the context of autoimmunity could be critical in elucidating key pathogenic mechanisms and could lead to novel interventions for the clinical management of autoimmune diseases.

Reactive oxygen species in health and disease

During the past decades, it became obvious that reactive oxygen species (ROS) exert a multitude of biological effects covering a wide spectrum that ranges from physiological regulatory functions to damaging alterations participating in the pathogenesis of increasing number of diseases. This review summarizes the key roles played by the ROS in both health and disease. ROS are metabolic products arising from various cells; two cellular organelles are intimately involved in their production and metabolism, namely, the endoplasmic reticulum and the mitochondria. Updates on research that tremendously aided in confirming the fundamental roles of both organelles in redox regulation will be discussed as well. Although not comprehensive, this review will provide brief perspective on some of the current research conducted in this area for better understanding of the ROS actions in various conditions of health and disease.

Treatment with aqueous extract from Croton cajucara Benth reduces hepatic oxidative stress in streptozotocin-diabetic rats

Croton cajucara Benth is a plant found in Amazonia, Brazil and the bark and leaf infusion of this plant have been popularly used to treat diabetes and hepatic disorders. The present study was designed to evaluate the oxidative stress as well as the therapeutic effect of Croton cajucara Benth (1.5 mL of the C. cajucara extract i.g.) in rats with streptozotocin-induced diabetes. Croton cajucara Benth was tested as an aqueous extract for its phytochemical composition, and its antioxidant activity in vitro was also evaluated. Lipid peroxidation and superoxide dismutase, catalase, and glutathione reductase activities were measured in the hepatic tissue, as well as the presence activation of p65 (NF-κB), through western blot. Phytochemical screening of Croton cajucara Benth detected the presence of flavonoids, coumarins and alkaloids. The extract exhibited a significant antioxidant activity in the DPPH-scavenging and the hypoxanthine/xanthine oxidase assays. Liver lipid peroxidation increased in diabetic animals followed by a reduction in the Croton-cajucara-Benth-treated group. There was activation of p65 nuclear expression in the diabetic animals, which was attenuated in the animals receiving the Croton cajucara Benth aqueous extract. The liver tissue in diabetic rats showed oxidative alterations related to the streptozotocin treatment. In conclusion the Croton cajucara Benth aqueus extract treatment effectively reduced the oxidative stress and contributed to tissue recovery.

Sphingosine-1-phosphate rapidly increases cortisol biosynthesis and the expression of genes involved in cholesterol uptake and transport in H295R adrenocortical cells

In the acute phase of adrenocortical steroidogenesis, adrenocorticotrophin (ACTH) activates a cAMP/PKA-signaling pathway that promotes the transport of free cholesterol to the inner mitochondrial membrane. We have previously shown that ACTH rapidly stimulates the metabolism of sphingolipids and the secretion of sphingosine-1-phosphate (S1P) in H295R cells. In this study, we examined the effect of S1P on genes involved in the acute phase of steroidogenesis. We show that S1P increases the expression of steroidogenic acute regulatory protein (StAR), 18-kDa translocator protein (TSPO), low-density lipoprotein receptor (LDLR), and scavenger receptor class B type I (SR-BI). S1P-induced StAR mRNA expression requires Gα(i) signaling, phospholipase C (PLC), Ca(2+)/calmodulin-dependent kinase II (CamKII), and ERK1/2 activation. S1P also increases intracellular Ca(2+), the phosphorylation of hormone sensitive lipase (HSL) at Ser(563), and cortisol secretion. Collectively, these findings identify multiple roles for S1P in the regulation of glucocorticoid biosynthesis.