Recommendations for the use of the acetaminophen hepatotoxicity model for mechanistic studies and how to avoid common pitfalls

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug, which is safe at therapeutic doses but can cause severe liver injury and even liver failure after overdoses. The mouse model of APAP hepatotoxicity recapitulates closely the human pathophysiology. As a result, this clinically relevant model is frequently used to study mechanisms of drug-induced liver injury and even more so to test potential therapeutic interventions. However, the complexity of the model requires a thorough understanding of the pathophysiology to obtain valid results and mechanistic information that is translatable to the clinic. However, many studies using this model are flawed, which jeopardizes the scientific and clinical relevance. The purpose of this review is to provide a framework of the model where mechanistically sound and clinically relevant data can be obtained. The discussion provides insight into the injury mechanisms and how to study it including the critical roles of drug metabolism, mitochondrial dysfunction, necrotic cell death, autophagy and the sterile inflammatory response. In addition, the most frequently made mistakes when using this model are discussed. Thus, considering these recommendations when studying APAP hepatotoxicity will facilitate the discovery of more clinically relevant interventions.

Solute carrier transporters: the metabolic gatekeepers of immune cells

Solute carrier (SLC) transporters meditate many essential physiological functions, including nutrient uptake, ion influx/efflux, and waste disposal. In its protective role against tumors and infections, the mammalian immune system coordinates complex signals to support the proliferation, differentiation, and effector function of individual cell subsets. Recent research in this area has yielded surprising findings on the roles of solute carrier transporters, which were discovered to regulate lymphocyte signaling and control their differentiation, function, and fate by modulating diverse metabolic pathways and balanced levels of different metabolites. In this review, we present current information mainly on glucose transporters, amino-acid transporters, and metal ion transporters, which are critically important for mediating immune cell homeostasis in many different pathological conditions.

Ameliorating effects of traditional Chinese medicine preparation, Chinese materia medica and active compounds on ischemia/reperfusion-induced cerebral microcirculatory disturbances and neuron damage

Ischemic stroke and ischemia/reperfusion (I/R) injury induced by thrombolytic therapy are conditions with high mortality and serious long-term physical and cognitive disabilities. They have a major impact on global public health. These disorders are associated with multiple insults to the cerebral microcirculation, including reactive oxygen species (ROS) overproduction, leukocyte adhesion and infiltration, brain blood barrier (BBB) disruption, and capillary hypoperfusion, ultimately resulting in tissue edema, hemorrhage, brain injury and delayed neuron damage. Traditional Chinese medicine (TCM) has been used in China, Korea, Japan and other Asian countries for treatment of a wide range of diseases. In China, the usage of compound TCM preparation to treat cerebrovascular diseases dates back to the Han Dynasty. Even thousands of years earlier, the medical formulary recorded many classical prescriptions for treating cerebral I/R-related diseases. This review summarizes current information and underlying mechanisms regarding the ameliorating effects of compound TCM preparation, Chinese materia medica, and active components on I/R-induced cerebral microcirculatory disturbances, brain injury and neuron damage.

Changes of Apoptosis Inducing Factor in the Rat Brain with Ischemic Injury Induced by Middle Cerebral Artery Occlusion / 체질인류학회지

It is well known that cerebral ischemia induces apoptotic neuronal cell death along with necrosis. Apoptosis is characterized by several morphological nuclear changes including chromatin condensation and nuclear fragmentation. These changes are triggered by the activation of members of caspase family, caspase activated DNase, and several novel proteins. A novel gene, the product of which caused chromatin condensation and DNA fragmentation, was recently identified, cloned, and designated apoptosis inducing factor (AIF). AIF is a mitochondrial flavoprotein (prosthetic group: flavin adenine dinucleotide) with significant homology to plant ascorbate reductase and bacterial NADH oxidase, and is normally confined to the mitochondrial space. In a variety of different apoptosis-inducing conditions, AIF translocates through the outer mitochondrial membrane to the cytosol and the nucleus. Thus, similar to cytochrome c, AIF is a phylogenetically old, bifunctional protein with an oxidoreductase function and a second apoptogenic function. In this study, to investigate changes of AIF expression levels in the rat brain during various time periods (6, 12, 18, 24 hrs) of ischemic insults, we performed permanent middle cerebral artery (MCA) occlusion model using male SD rats and the extent of ischemic injury was measured by 2% TTC (2, 3, 5-triphenyl tetrazolium chloride) staining. There were numerous TUNEL-positive neuronal cell nuclei, which implies apoptotic cell death in the areas with ischemic insult. Western blot analysis was performed with separate samples (cytosolic fraction & mitochondrial fraction). This method was designed to investigate if the expression of AIF is really increased during ischemic injury, or the increased AIF activity is caused by its release from the mitochondrial inter-membrane space to cytosol. In the immunohistochemical study using polyclonal anti-AIF antibody revealed overall distribution of AIF in the rat brain including cerebral cortex, basal ganglia and also in hippocampus that is especially sensitive to ischemia. There was apparently increased AIF immunoreactivity in the nucleus accumbens of ischemia-induced hemisphere compared to contralateral control hemisphere. Our results seem to be the first evidence on the involvement of AIF in the apoptotic neuronal cell loss with ischemic insult and will provide some clues to the pathophysiology of neuronal apoptosis induced by ischemic insult. Further researches will reveal functional relationship between AIF and other factors involved in chromatin condensation and degradation and whether AIF itself will be useful as a caspase-independent, Bcl-2-independent death inducer.