No abstract

The control of inflammation, which arises from complex biological responses to harmful stimuli, is an important determinant of both clinical outcomes and patient comfort. However, the side effects of many current therapies such as non-steroidal anti-inflammatory drugs mean that new safe treatments are required. We previously reported that 12.5 µg/ml hydroxytyrosol (HT) suppressed gene expression of the inducible nitric oxide (NO) synthase (iNOS) isoform and NO production, in mouse peritoneal macrophages treated with lipopolysaccharide (LPS), where nuclear factor-κB (NF-κB) gene expression was not altered. The present study evaluated the anti-inflammatory effects of various concentrations of HT in LPS-induced RAW264.7 mouse macrophages. HT suppressed NF-κB signaling and downregulated LPS-mediated expression of iNOS, cyclooxygenase-2, tumor necrosis factor alpha, and interleukin-1β at 12.5 µg/ml, resulting in reduced production of NO and prostaglandin E2. At lower concentrations, HT seemed to act via another signaling pathway to regulate the inflammatory response. In contrast, HT did not suppress LPS-induced expression of phosphorylated p44/42 mitogen-activated protein kinase. This study showed that HT had anti-inflammatory effects on LPS-stimulated RAW264.7 cells. HT is already available as a nutritional supplement and no toxic effects have been reported. Hence, HT represents a potential novel anti-inflammatory agent.

Drug-induced liver injury (DILI) is a major safety concern in drug development and clinical drug therapy. However, the underlying mechanism of DILI is little known. It is generally believed that women exhibit worse outcomes from DILI than men. Recently, we found that pretreatment of mice with estradiol attenuated halothane (HAL)-induced liver injury, whereas pretreatment with progesterone exacerbated it in female mice. To investigate the mechanism of sex difference of DILI, we focused on progesterone in this study. We found the exacerbating effect of progesterone in thioacetamide (TA), α-naphthylisothiocyanate, and dicloxacillin-induced liver injury only in female mice. Higher number of myeloperoxidase-positive mononuclear cells infiltrated into the liver and increased levels of Chemokine (C-X-C motif) ligand 1 and 2 (CXCL1 and CXCL2) and intercellular adhesion molecule-1 in the liver were observed. Interestingly, CXCL1 was slightly increased by progesterone pretreatment alone. Progesterone pretreatment increased the extracellular signal-regulated kinase (ERK) phosphorylation in HAL-induced liver injury. Pretreatment with U0126 (ERK inhibitor) significantly suppressed the exacerbating effect of progesterone and the expression of inflammatory mediators. In addition, pretreatment with gadolinium chloride (GdCl(3): inhibitor of Kupffer cells) significantly suppressed the exacerbating effect of progesterone pretreatment and the expression of inflammatory mediators. Moreover, posttreatment of RU486 (progesterone receptor antagonist) 1 h after the HAL or TA administration ameliorated the HAL- or TA-induced liver injury, respectively, in female mice. In conclusion, progesterone exacerbated the immune-mediated hepatotoxic responses in DILI via Kupffer cells and ERK pathway. The inhibition of progesterone receptor and decrease of the immune response may have important therapeutic implications in DILI.

No abstract

The chemical reactivity of acyl glucuronide (AG) has been thought to be associated with the toxic properties of drugs containing carboxylic acid moieties, but there has been no direct evidence showing that AG formation is related to the observed toxicity. In the present study, the cytotoxicity of AGs, especially that associated with the inflammatory response, was investigated. The changes in the mRNA and protein expression levels of interleukin 8 (IL-8) and monocyte chemoattractant protein (MCP)-1 induced by the treatment of human peripheral blood mononuclear cells (PBMCs) with diclofenac (Dic), probenecid (Pro), tolmetin (Tol), ibuprofen (Ibu), naproxen (Nap), and their AGs were investigated by real-time reverse transcription polymerase chain reaction, and the viabilities of CD3+, CD14+, and CD19+ cells were measured by flow cytometry. Treatment with Dic-AG, Pro-AG, and Tol-AG significantly increased the expression levels of IL-8 and MCP-1. In addition, Dic-AG, Pro-AG, and Tol-AG significantly decreased the viability of CD14+ cells. Of these three AGs, Dic-AG showed the most potent changes, followed by Tol-AG and Pro-AG. Treatment with Ibu-AG and Nap-AG affected neither the expression levels of IL-8 and MCP-1 nor the viability of CD14+ cells. None of the drugs affected the CD3+ and CD19+ cell populations. Dic-AG increased the phosphorylation of p38 mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK)1/2. The pretreatment of peripheral blood mononuclear cells (PBMCs) with SB203580 (p38 inhibitor) significantly suppressed the Dic-AG-induced expression of inflammatory factors and cytotoxicity of CD14+ cells. In conclusion, AGs induce inflammatory responses and cytotoxicity against CD14+ cells via the p38 MAPK pathway. These factors may be useful biomarkers for evaluating the toxicity of AGs.