Pathogenic role of natural killer T and natural killer cells in acetaminophen-induced liver injury in mice is dependent on the presence of dimethyl sulfoxide

Abstract

Dimethyl sulfoxide (DMSO) is commonly used in biological studies to dissolve drugs and enzyme inhibitors with low solubility. Although DMSO is generally thought of as being relatively inert, it can induce biological effects that are often overlooked. An example that highlights this potential problem is found in a recent report demonstrating a pathogenic role for natural killer T (NKT) and natural killer (NK) cells in acetaminophen-induced liver injury (AILI) in C57Bl/6 mice in which DMSO was used to facilitate acetaminophen (APAP) dissolution. We report that NKT and NK cells do not play a pathologic role in AILI in D rug-induced liver injury (DILI) is a serious, often fatal side effect of drug treatment representing a major impediment to drug development. 1,2 Attempts to identify hepatotoxic drugs early in development have been hindered in part by a poor understanding of the underlying mechanism of DILI. Current evidence suggests that reactive metabolites, drug-protein adducts, and glutathione depletion might be common events involved in the initiation of DILI; however, it is currently not possible to predict hepatotoxicity based on these criteria alone. 3 Therefore, there is a great deal of interest in studying the downstream events of these initiating factors in hope of identifying potential markers of hepatotoxicity and pathways leading to DILI. 4,5 The most extensively used model for uncovering fundamental mechanisms of DILI has been acetaminopheninduced liver injury (AILI) in mice. 4,6 In this model, the preponderance of evidence indicates that N-acetyl-p-benzoquinone imine (NAPQI), the reactive metabolite of acetaminophen (APAP); NAPQI-protein adducts; glutathione depletion; oxidative stress; and mitochondria damage all play a role in AILI. 7 More recently, evidence suggests that the innate immune system can contribute to the severity of AILI through the production of proinflammatory cytokines and other protoxicant factors subsequent to the early metabolic events initiated by NAPQI

Development of a novel mouse model of amodiaquine-induced liver injury with a delayed onset

“…The drug was started at Day 0, and injection of anti-NK1.1 antibody, IgG 1 isotype, or PBS was repeated every week to maintain suppressed NK activity (Koo et al, 1986). Administration of this anti-NK1.1 antibody has been previously shown to deplete NK and NKT cells (Masson et al, 2008). In our laboratory, injection with anti-NK1.1 antibody depletes NK and NKT cells in the liver, spleen, blood, and cervical lymph nodes; depletion of NK cells was also confirmed by staining with anti-NKP46 antibody (another cellular marker for NK cells; data not shown).…”

Diet Restriction Inhibits Apoptosis and HMGB1 Oxidation and Promotes Inflammatory Cell Recruitment during Acetaminophen Hepatotoxicity

“…The role of the innate immune response activated through APAP-induced direct hepatocyte death in animal models also remains controversial (13). Many cell types have been implicated in determin-ing the extent of organ injury or regeneration in the liver, such as Kupffer cells (14), neutrophils (15), natural-killer cells and natural-killer cells with T-cell receptor (16).…”

Protective role of c-Jun N-terminal kinase 2 in acetaminophen-induced liver injury

“…While the basis for the contradictory results in JNK2 −/− mice susceptibility to AILI is not clear, different doses of APAP were used in each study, which might affect the results, and in one case, APAP was dissolved in DMSO [21], which is known to have a profound effect on APAP metabolism [33] and innate-immune response after APAP [34]. Nevertheless, it remains to be determined whether these factors contribute to the conflicting findings.…”

“…Potential limitations of these studies, as acknowledged by the investigators [21,22] is that JNK inhibitors may not be specific and as reported can affect other signaling events that could lead to the misinterpretation of results [36][37][38][39]. Further, some of the JNK inhibitors were dissolved in vehicles containing DMSO [14,21] and polyethylene glycol [22,35], which may affect various parameters at the cellular and molecular level [34,[40][41][42][43].…”

“…Potential limitations of these studies, as acknowledged by the investigators [21,22] is that JNK inhibitors may not be specific and as reported can affect other signaling events that could lead to the misinterpretation of results [36][37][38][39]. Further, some of the JNK inhibitors were dissolved in vehicles containing DMSO [14,21] and polyethylene glycol [22,35], which may affect various parameters at the cellular and molecular level [34,[40][41][42][43].In conclusion, our findings suggest that JNK2 plays a protective role against AILI in mice at least, in part, by modulating hepatocellular regeneration and repair. Although other research in mice provides evidence for JNK having a pathologic role in AILI, we feel that it is prudent to reconsider the use of JNK inhibitors as a therapeutic intervention in AILI [21,22,35,44].…”