Dextran-Methylprednisolone Succinate as a Prodrug of Methylprednisolone: Local Immunosuppressive Effects in Liver After Systemic Administration to Rats

Purpose. The purpose of this work was to study the local immunosuppressive effects of systemically administered methylprednisolone (MP) and its prodrug, dextran-methylprednisolone (DMP), in rat livers. Methods. Single 5 mg/kg (MP equivalent) doses of MP or DMP were injected intravenously to rats, and livers were isolated at different time points (0-72 h; n = 4/time point). Isolated livers were stimulated ex vivo with bacterial lipopolysaccharide, and outlet perfusate and bile samples were analyzed for their concentrations of tumor necrosis factor (TNF)- by enzyme-linked immunosorbent assay. The area under the perfusate TNF- concentration-time curve (AUC) was used as a measure of immune response. Hepatic concentrations of MP and DMP were also measured by high-performance liquid chromatography. Results. Both MP and DMP resulted in a decrease in lipopolysaccharide-induced increase in TNF- AUC. MP injection 8 h before liver isolation resulted in a maximum of 50% decrease in TNF- AUC. Compared with MP, the maximum effect of the prodrug (DMP) was both more intense (80% reduction in TNF- AUC) and delayed (maximum inhibition at 24 h). Overall, the area under the effect (% inhibition of TNF-)-time (%inhibitionh) for DMP (3680 ± 406) was approximately four times more than that for the parent drug (846 ± 114). Whereas the MP concentrations in the liver were not quantifiable after the injection of the parent drug, relatively large concentrations of DMP and regenerated MP were found in the liver of DMP-injected rats. Conclusions. After systemic administration to rats, both MP and DMP exhibit local immunosuppressive effects in the liver. The local effects of the prodrug (DMP), however, appear to be more intense and sustained than those of the parent drug (MP).     

A Modified Coumarinic Acid-Based Cyclic Prodrug of an Opioid Peptide: Its Enzymatic and Chemical Stability and Cell Permeation Characteristics

Purpose. To evaluate the chemical/enzymatic stability and the cell permeation characteristics of the modified coumarinic acid-based cyclic prodrug 2 of DADLE (H-Tyr-D-Ala-Gly-Phe-D-Leu-OH), which has an aldehyde equivalent (oxymethyl) inserted between the phenolic group of the promoiety and the carboxylic acid group of the peptide. Methods. The rates of the chemical/enzymatic conversion of the oxymethyl-modified prodrug 2 to DADLE were measured by HPLC. The cellular permeation characteristics of DADLE and its oxymethyl-modified prodrug 2 were measured by HPLC using Caco-2 cells, wild type Madin-Darby Canine Kidney cells (MDCK-WT), MDCK cells transfected with human MDR1 gene (MDCK-MDR1), and MDCK cells transfected with human MRP2 gene (MDCK-MRP2) grown onto microporous membranes. Results. The oxymethyl-modified coumarinic acid-based cyclic prodrug 2 degraded chemically to DADLE in a pH-dependent manner, i.e., rates of conversion increased with increasing pH. The prodrug 2 degraded rapidly in rat plasma (t_1/2 = 39 min) and rat liver homogenate (t_1/2 = 59.2 min), but much slower in Caco-2 cell homogenate (t_1/2 = 678.7 min) and human plasma (t_1/2 = 264.3 min). In all four cell lines used for transport studies, the flux rates of the oxymethyl prodrug 2 in the basolateral (BL)-to-apical (AP) direction (P_{app BL-to-AP}) were significantly greater than the flux rates in the AP-to-BL direction (P_{app AP-to-BL}). The P_{app BL-to-AP} /P_{app AP-to-BL} ratios were >116, 35.1, 21.2, and 12.6 in Caco-2, MDCK-MDR1, MDCK-MRP2, and MDCK-WT cells, respectively. The efflux of the modified prodrug could be inhibited by GF120918 (an inhibitor for P-gp) and cyclosporin A (an inhibitor for P-gp and MRP2). Conclusions. The oxymethyl-modified coumarinic acid-based cyclic prodrug 2 of DADLE could be converted to DADLE in both chemical and enzymatic media. However, the prodrug was a good substrate for both P-gp and MRP2 suggesting that its permeation across intestinal mucosa and blood-brain barrier would be significantly restricted.     

Kupffer cell‐mediated exacerbation of methimazole‐induced acute liver injury in rats

Methimazole (MTZ), an anti‐thyroid drug, is known to cause liver injury in humans. It has been demonstrated that MTZ‐induced liver injury in Balb/c mice is accompanied by T helper (Th) 2 cytokine‐mediated immune responses; however, there is little evidence for immune responses associated with MTZ‐induced liver injury in rats. To investigate species differences in MTZ‐induced liver injury, we administered MTZ with a glutathione biosynthesis inhibitor, L‐buthionine‐S,R‐sulfoximine (BSO), to F344 rats and subsequently observed an increase in plasma alanine aminotransferase (ALT) and high‐mobility group box 1 (HMGB1), which are associated with hepatic lesions. The hepatic mRNA expression of innate immune‐related genes significantly increased in BSO‐ and MTZ‐treated rats, but the change in Th2‐related genes was not much greater than the change observed in the previous mouse study. Moreover, an increase in Kupffer cells and an induction of the phosphorylation of extracellular signal‐regulated kinase (ERK)/c‐Jun N‐terminal kinase (JNK) proteins were accompanied by an increase in Toll‐like receptor 4 (TLR4) expression, indicating that Kupffer cell activation occurs through HMGB1‐TLR4 signaling. To elucidate the mechanism of liver injury in rats, gadolinium chloride, which inactivates the function of Kupffer cells, was administered before BSO and MTZ administration. The gadolinium chloride treatment significantly suppressed the increased ALT, which was accompanied by decreased hepatic mRNA expression related to innate immune responses and ERK/JNK phosphorylation. In conclusion, Kupffer cell‐mediated immune responses are crucial factors for the exacerbation of MTZ‐induced liver injury in rats, indicating apparent species differences in the immune‐mediated exacerbation of liver injury between mice and rats. Copyright © 2015 John Wiley & Sons, Ltd.     

Interaction of Differently Designed Immunoliposomes with Colon Cancer Cells and Kupffer Cells. An in Vitro Comparison

Purpose. Evaluate the effectiveness of distal-end coupling of a tumor-specific antibody to liposomal polyethylene glycol (PEG) chains to improve target binding and reduce interference by macrophage uptake. Methods. Monoclonal antibody CC52, specific for CC531 rat colon carcinoma, was coupled to the bilayer of PEG-liposomes (type I) or to the distal end of bilayer-anchored PEG-chains (type II). Uptake of both (radiolabeled)liposome types by CC531 cells and rat liver macrophages was determined. Results. With increasing antibody density, both immunoliposome types showed increased binding to target cells, but type II liposomes displayed better target recognition than type I. Uptake by macrophages increased with antibody density for both liposome types. Lowest uptake by macrophages was found for type II liposomes at low antibody densities. Unexpectedly, not only for type I but also for type II liposomes, in which the antibody is coupled via its Fc moiety, uptake by macrophages was inhibited by aggregated IgG, indicating involvement of Fc receptors. Also polyinosinic acid, an inhibitor of scavenger receptors, reduced uptake of type II liposomes. Conclusion. Although distal end coupling of antibodies to bilayer-anchored PEG chains in liposomes through the Fc moiety enhances target cell binding, it does not prevent the recognition by Fc receptors on macrophages.     

Effects of Human Mesenchymal Stem Cell Transplantation Combined with Polymer on Functional Recovery Following Spinal Cord Hemisection in Rats

The spontaneous axon regeneration of damaged neurons is limited after spinal cord injury (SCI). Recently, mesenchymal stem cell (MSC) transplantation was proposed as a potential approach for enhancing nerve regeneration that avoids the ethical issues associated with embryonic stem cell transplantation. As SCI is a complex pathological entity, the treatment of SCI requires a multipronged approach. The purpose of the present study was to investigate the functional recovery and therapeutic potential of human MSCs (hMSCs) and polymer in a spinal cord hemisection injury model. Rats were subjected to hemisection injuries and then divided into three groups. Two groups of rats underwent partial thoracic hemisection injury followed by implantation of either polymer only or polymer with hMSCs. Another hemisection-only group was used as a control. Behavioral, electrophysiological and immunohistochemical studies were performed on all rats. The functional recovery was significantly improved in the polymer with hMSC-transplanted group as compared with control at five weeks after transplantation. The results of electrophysiologic study demonstrated that the latency of somatosensory-evoked potentials (SSEPs) in the polymer with hMSC-transplanted group was significantly shorter than in the hemisection-only control group. In the results of immunohistochemical study, β-gal-positive cells were observed in the injured and adjacent sites after hMSC transplantation. Surviving hMSCs differentiated into various cell types such as neurons, astrocytes and oligodendrocytes. These data suggest that hMSC transplantation with polymer may play an important role in functional recovery and axonal regeneration after SCI, and may be a potential therapeutic strategy for SCI.     

Absorption Characteristics of Dextrans with Different Molecular Weights from the Liver Surface Membrane in Rats: Implications for Targeting to the Liver

Abstract

We examined the importance of molecular weight on the absorption from the liver surface in rats using fluorescein isothiocyanate-dextrans (FDs) with molecular weights of 4,400 (FD-4), 9,300 (FD-10), 40,500 (FD-40) or 69,000 (FD-70). After application of FDs (5 mg) to the rat liver surface employing a cylindrical glass cell (i.d. 9 mm), each FD appeared gradually in the plasma, and the in vivo behavior was explained by two-compartment model with first-order absorption. The absorption ratios of FDs from the rat liver surface at 6 h, calculated from the amount recovered from the glass cell, decreased with an increase in the molecular weight (44.5% for FD-4, 29.3% for FD-10, 5.1% for FD-40 and 2.2% for FD-70). A linear relationship was observed between the absorption rate constant and the reciprocal value with square root of molecular weight of the model compounds. The limit of absorption from the rat liver surface was extrapolated to be at a molecular weight of 70,000. Furthermore, absorbed FDs were accumulated in the liver, as high liver/plasma concentration ratio as compared with that of i.v. administration.

We clarified the molecular weight dependence of drug absorption from the liver surface in rats. Moreover, the liver surface application appeared to be a promising route with enhancing the efficacy of drug targeting to the liver.     

维生素C和维生素E单用及联用对慢性酒精性肝损伤模型大鼠的预防性保护作用

目的:观察维生素C(VC)和维生素E(VE)单用及联用对慢性酒精性肝损伤模型大鼠的预防性保护作用。方法:取60只大鼠,随机均分为对照组、模型组、VC组(150mg·kg-1)、VE组(250mg·kg-1)和同剂量联合用药组(VC+VE组),除对照组给予等量生理盐水灌胃外,其余各组连续灌胃56°白酒建立慢性酒精性肝损伤模型,同时给予相应药物,每天1次,6周后检测各组大鼠血清丙氨酸转氨酶(ALT)、天门冬氨酸转氨酶(AST),肝匀浆中超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量,并观察肝组织病理学变化,免疫组织化学法检测肝组织中Ⅰ和Ⅲ型胶原的表达情况。结果:与模型组比较,VC组、VE组、VC+VE组ALT和AST活性、MDA含量、Ⅰ和Ⅲ型胶原表达均显著性降低(P<0.05),SOD活性显著性升高(P<0.05),肝脏炎症反应和纤维化明显减轻,且单用组和联用组之间无显著性差异。结论:VC和VE可能通过清除自由基和抑制脂质过氧化过程对慢性酒精性肝损伤模型大鼠发挥预防性保护作用。     

电针足三里对重度失血性休克大鼠肝脏损伤的影响

目的:探讨电针足三里对于重度失血性休克大鼠肝损伤的影响及可能的机制。方法:取60只SD大鼠随机分为对照组(C组)、休克组(S组、SEN组)、复苏组(LR组、LREN1组、LREN2组),采用改良wigger's法复制重度失血性休克模型,检测各组大鼠血浆AST、ALT含量,肝组织TNF-α和MIP-2蛋白表达,MPO活性,电镜下观察肝组织病理学变化。结果:与休克组比较,各复苏组血浆AST、ALT含量,肝组织TNF-α和MIP-2蛋白表达增加,MPO活性降低,肝组织超微结构受损明显;与LR组比较,LREN1组及LREN2组以上损伤减轻,其中LREN2组以上指标降低显著(P<0.05),肝组织病理损伤较轻。结论:休克期电针刺激双侧足三里能减轻重度失血性休克再灌注后肝脏损伤,其机制与降低肝组织TNF-α、MIP-2产生,降低MPO活性有关。     

Impact of e-cigarette refill liquid with or without nicotine on liver function in adult rats

This study was conducted to evaluate the effects of e-cigarette refill liquid administration alone or with nicotine on the antioxidant defense status, functional and histopathological changes in adult rat liver tissue. For this purpose, 32 rats were treated for 28 days as follows: control group was injected intra-peritoneally with physiological saline; e-cigarette 0% treated group received an intra-peritoneal injection of e-liquid without nicotine diluted in physiological saline, e-cigarette-treated group received an intra-peritoneal injection of e-liquid containing 0.5?mg of nicotine/kg of body weight/day diluted in physiological saline and nicotine-treated group received an intra-peritoneal injection of 0.5?mg of nicotine/kg of body weight/day diluted in physiological saline. In e-liquid without nicotine-exposed group, activities of the liver biomarkers aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and lactate dehydrogenase increase. Interestingly, oxidative stress indicators showed decreased total protein content, associated with a reduction in the antioxidant enzymes activities superoxide dismutase, catalase and glutathione-S-transferase, and an elevation in malondialdehyde content, highlighting the promotion of lipid peroxidation and oxidative stress. Histological studies identified inflammatory cells infiltration and cell death. Thus, e-liquid seems to promote oxidative tissue injuries, which in turn lead to the observed histopathological finding. In comparison, nicotine alone induced less oxidative stress and less histopathological disorders, whereas e-liquid with nicotine gave rise to more histopathological injuries. Thereby, e-liquid, per se, is able to induce hepatotoxicity and supplementation with nicotine worsens this state.     

昆藻调脂胶囊对实验性高脂血症性脂肪肝大鼠肝细胞增殖的影响

目的:探讨昆藻调脂胶囊治疗高脂血症性脂肪肝的作用机制。方法:取59只大鼠随机分为正常对照组(n=10)、模型组(n=11)、阳性对照组(n=10)及昆藻调脂胶囊高、中、低剂量组(n=9、9、10),除正常对照组外,其余各组采用高脂饲料及30%乙醇方法复制脂肪肝模型,同时给予相应溶剂或药物,10wk后运用流式细胞术观察各组大鼠肝细胞DNA的S期细胞比例(SPF)及增殖指数(PI)。结果:与正常对照组比较,造模后大鼠PI、SPF值明显升高(P<0.05);昆藻调脂胶囊能降低造模后大鼠PI、SPF值(P<0.05),尤其对♀大鼠的作用更为显著(P<0.01)。结论:昆藻调脂胶囊通过抑制高血脂大鼠特别是♀大鼠肝细胞的增殖而发挥抗肝纤维化作用。     

先天性心脏病不停跳与停跳手术对心肌特异性蛋白的影响

目的探讨常见先天性心脏病矫治术中心脏不停跳与停跳两种术式,对血清心型脂肪酸结合蛋白（H-FABP）和心肌肌钙蛋白Ⅰ（cTnI）浓度的影响,并比较两种蛋白在反映心肌损伤中的不同特点。方法30例行先天性心脏病矫治术患者随机分为心脏不停跳组（组Ⅰ）和冷晶体停跳组（组Ⅱ）,每组15例。术前至主动脉开放后共8个时间点测定血清H-FABP和cTnI浓度。结果两组术后血清H-FABP、cTnI水平均不同程度升高,多时点差异有显著性。结论常见先天性心脏病矫治术中心脏不停跳可明显减轻心肌缺血、缺氧及再灌注损伤,减少H-FABP、cTnI的释放,有良好的心肌保护作用;H-FABP变化快速,有更早的峰值浓度出现,是一项早期、敏感判断心肌损伤的指标。     

复方茵柏颗粒对四氯化碳肝损伤模型大鼠氧化应激的影响

目的:研究复方茵柏颗粒对四氯化碳(CCl4)肝损伤模型大鼠氧化应激的影响。方法:48只SD大鼠随机分为正常对照(等容生理盐水)组、模型(等容生理盐水)组、复方茵柏合剂(8.65 g/kg)组与复方茵柏颗粒高、中、低剂量(8.64、4.32、2.16 g/kg)组。灌胃给药,每天1次,连续3周。末次给药2 h后一次性腹腔注射40%CCl4的玉米油以复制大鼠急性肝损伤模型。测定大鼠血清中丙氨酸氨基转移酶(ALT)、天冬氨酸氨基转移酶(AST)和乳酸脱氢酶(LDH)的活性,总胆红素(TBIL)、直接胆红素(DBIL)的含量;酶联免疫吸附(ELISA)法检测大鼠肝组织匀浆中丙二醛(MDA)和还原型谷胱甘肽(GSH)含量;并对大鼠肝组织作病理学检测。结果:与正常对照组比较,模型组大鼠血清ALT、AST、LDH活性显著增强,TBIL、DBIL含量显著增加,MDA含量显著增加,GSH活性显著减弱(P<0.01);与模型组比较,复方茵柏颗粒高、中、低剂量组大鼠血清ALT、AST、LDH活性显著减弱,TBIL、DBIL含量显著减少,MDA含量显著减少,GSH活性显著增强(P<0.01或P<0.05)。正常对照组大鼠肝小叶结构清晰,肝细胞索排列规则,肝细胞结构及形态正常,核大而圆,居中,核膜清晰;模型组大鼠大部分肝细胞明显水肿,气球样变,肝细胞索排列紊乱,肝小叶内中央静脉和汇管区出现弥漫性的炎细胞浸润;而复方茵柏颗粒高、中、低剂量组大鼠大部分肝细胞结构完整,排列整齐,肝细胞水肿、气球样变及炎细胞浸润均明显减轻。结论:复方茵柏颗粒对CCl4所致的大鼠急性肝损伤有一定的保护作用,其机制可能与其清除自由基、抑制脂质过氧化有关。     

Effects of transient overexpression or knockdown of cytochrome P450 reductase on reactive oxygen species generation and hypoxia reoxygenation injury in liver cells

1. Literature data suggest that the electron-donating enzyme, cytochrome P450 reductase (CPR), might act as a source of reactive oxygen species (ROS). However, the role of CPR in pathophysiological conditions associated with oxidative stress is unknown. The aim of the present study was to study the role of CPR in the generation of ROS and cellular injury under basal conditions, and after simulated in vitro ischaemia-reperfusion (IR). 2. Plasmid DNA or siRNA approaches were used to transiently overexpress or knockdown the human CPR gene in rat liver epithelial (WB-F344) or human hepatoblastoma (HepG2) cells, respectively. The generation of ROS and/or cellular injury was then studied under the basal conditions and after simulated IR (4 h of ischaemia plus 30 min of reoxygenation). 3. Under the basal conditions, transient overexpression of CPR protein in WB-F344 cells caused a 90% increase in the CPR activity, which was associated with a 100% increase in the ROS production. In contrast, after simulated IR, a 2.5-fold higher CPR activity did not significantly affect the magnitude of ROS generation or cell death. Similarly, although the knockdown of CPR protein resulted in a significant reduction (～30%) in the CPR activity, the ROS production was not substantially altered after simulated IR in HepG2 cells. 4. Our data suggest that CPR plays a major role in the ROS generation by liver cells under the basal conditions. However, the role of CPR in the ROS generation during simulated in vitro IR injury in these cells is minimal, if any.     

The role of damage associated molecular pattern molecules in acetaminophen-induced liver injury in mice

The idiosyncratic nature, severity and poor diagnosis of drug-induced liver injury (DILI) make these reactions a major safety issue during drug development, as well as the most common cause for the withdrawal of drugs from the pharmaceutical market. Elucidation of the underlying mechanism(s) is necessary for identifying predisposing factors and developing strategies in the treatment and prevention of DILI. Acetaminophen (APAP) is a widely used over the counter therapeutic that is known to be effective and safe at therapeutic doses. However, in overdose situations fatal and non-fatal hepatic necrosis can result. Evidence suggests that the chemically reactive metabolite of the drug initiates hepatocyte damage and that inflammatory innate immune responses also occur within the liver, leading to the exacerbation and progression of tissue injury. Here we investigate whether following APAP-induced liver injury (AILI) damaged hepatocytes release “danger” signals or damage associated molecular pattern (DAMP) molecules, which induce pro-inflammatory activation of hepatic macrophages, further contributing to the progression of liver injury. Our study demonstrated a clear activation of Kupffer cells following early exposure to APAP (1 h). Activation of a murine macrophage cell line, RAW cells, was also observed following treatment with liver perfusate from APAP-treated mice, or with culture supernatant of APAP-challenged hepatocytes. Moreover, in these media, the DAMP molecules, heat-shock protein-70 (HSP-70) and high mobility group box-1 (HMGB1) were detected. Overall, these findings reveal that DAMP molecules released from damaged and necrotic hepatocytes may serve as a crucial link between the initial hepatocyte damage and the activation of innate immune cells following APAP-exposure, and that DAMPs may represent a potential therapeutic target for AILI.     

Involvement of natural killer T cells in halothane-induced liver injury in mice

Drug-induced liver injury (DILI) causes significant patient morbidity and mortality, and is the most common reason for drug withdrawals. It is imperative to gain a thorough understanding of the underlying mechanisms of DILI to effectively predict and prevent these reactions. We have recently developed a murine model of halothane-induced liver injury (HILI). The aim of the present study was to investigate the role of hepatic natural killer T (NKT) cells in the pathogenesis of HILI. The degrees of HILI were compared between WT and CD1d^−/− mice, which are deficient in NKT cells. The data revealed that CD1d^−/− mice were resistant in developing HILI. This resistance appeared to be a direct result of NKT cell depletion rather than an indirect one due to the absence of cross-talk between NKT cells and other hepatic innate immune cells. Compared with WT mice, CD1d^−/− mice exhibited a significantly lower number of hepatic infiltrating neutrophils upon halothane challenge (470,000 ± 100,000/liver in WT vs. 120,000 ± 31,500/liver in CD1d^−/− mice). This result in conjunction with our previous finding of an indispensable role of neutrophils in HILI strongly suggests that NKT cells play a critical role in regulating neutrophil recruitment, thereby contributing to the development of HILI. Collectively, the current study and published reports indicate that this murine model of HILI provides an experimental system for the investigation of the underlying mechanisms of DILI. In addition, this model may yield the discovery of susceptibility factors that may control the development of liver injury in patients treated with halothane and potentially other drugs.