Protective effects of nafamostat mesilate on liver injury induced by lipopolysaccharide in rats: possible involvement of CD14 and TLR-4 downregulation on Kupffer cells

Pathophysiological dynamics in the contact, coagulation, and complement systems during sepsis: Potential targets for nafamostat mesilate

Sepsis is a life-threatening syndrome resulting from a dysregulated host response to infection. It is the primary cause of death in the intensive care unit, posing a substantial challenge to human health and medical resource allocation. The pathogenesis and pathophysiology of sepsis are complex. During its onset, pro-inflammatory and anti-inflammatory mechanisms engage in intricate interactions, possibly leading to hyperinflammation, immunosuppression, and long-term immune disease. Of all critical outcomes, hyperinflammation is the main cause of early death among patients with sepsis. Therefore, early suppression of hyperinflammation may improve the prognosis of these patients. Nafamostat mesilate is a serine protease inhibitor, which can inhibit the activation of the complement system, coagulation system, and contact system. In this review, we discuss the pathophysiological changes occurring in these systems during sepsis, and describe the possible targets of the serine protease inhibitor nafamostat mesilate in the treatment of this condition.

Allogeneic Liver Transplantation and Subsequent Syngeneic Hepatocyte Transplantation in a Rat Model: Proof of Concept for in vivo Tissue Engineering

Objectives: Stable long-term functioning of liver cells after transplantation in humans is still not achieved successfully. A new approach for successful engraftment of liver cells may be the transplantation of syngeneic cells into an allogeneic liver graft. We therefore developed a new rat model for combined liver and liver cell transplantation (cLCTx) under stable immunosuppression. Materials and Methods: After inducing a mitotic block, liver grafts from female donor rats (Dark Agouti) were transplanted into female recipients (Lewis). In male Lewis rats, liver cell proliferation was induced with subsequent cell isolation and transplantation into female recipients after organ transplantation. Y-chromosome detection of the transplanted male cells was performed by quantitative polymerase chain reaction (qPCR) and fluorescence in situ hybridization (FisH) with localization of transplanted cells by immunohistochemistry. Results: Immunohistochemistry demonstrated the engraftment of transplanted cells, as confirmed by FisH, showing repopulation of the liver graft with 15.6% male cells (± 1.8 SEM) at day 90. qPCR revealed 14.15% (± 5.09 SEM) male DNA at day 90. Conclusion: Engraftment of transplanted syngeneic cells after cLCTx was achieved for up to 90 days under immunosuppression. Immunohistochemistry indicated cell proliferation, and the FisH results were partly confirmed by qPCR. This new protocol in rats appears feasible for addressing long-term functioning and eventually the induction of operational tolerance in the future.

Role of Kupffer cells in pathogenesis of sepsis-induced drug metabolizing dysfunction

The present study aimed to determine the role of Kupffer cells (KCs) in cytochrome P450 (CYP) isozyme activity and the expression of its gene during polymicrobial sepsis. For ablation of KCs, rats were pretreated with gadolinium chloride (GdCl(3)) at 48 and 24 h before cecal ligation and puncture (CLP). The depletion of KCs was confirmed by measuring the mRNA level of the KC marker gene CD163. Serum aminotransferase levels and lipid peroxidation showed an increase and hepatic glutathione content showed a decrease at 24 h after CLP. These changes were prevented by GdCl(3) pretreatment. Catalytic activities of CYP1A1, 1A2 and 2E1 showed a significant reduction at 24 h after CLP but were prevented by GdCl(3). A reduction in the levels of CYP2E1 protein and CYP2B1 and CYP2E1 mRNA expression was prevented by GdCl(3). Phosphorylation of CYP1A1/1A2 markedly increased 24 h after CLP, which was prevented by GdCl(3). The increased serum level of high mobility group box 1, hepatic level of Toll-like receptors 2 and 4, and inducible nitric oxide synthase protein expression were prevented by GdCl(3). In addition, elevated serum concentrations of tumor necrosis factor-α and interleukin-6, and increased hepatic mRNA levels of tumor necrosis factor-α and interleukin-6 were decreased by depletion of KCs. Our findings suggest that ablation of KCs protects against hepatic drug-metabolizing dysfunction by modulation of the inflammatory response.

The modulation of TRPM7 currents by nafamostat mesilate depends directly upon extracellular concentrations of divalent cations

Concentrations of extracellular divalent cations (Ca²⁺ and Mg²⁺) fall substantially during intensive synaptic transmission as well as during some pathophysiological conditions such as epilepsy and brain ischemia. Here we report that a synthetic serine protease inhibitor, nafamostat mesylate (NM), and several of its analogues, block recombinant TRPM7 currents expressed in HEK293T cells in inverse relationship to the concentration of extracellular divalent cations. Lowering extracellular Ca²⁺ and Mg²⁺ also evokes a divalent-sensitive non-selective cation current that is mediated by TRPM7 expression in hippocampal neurons. In cultured hippocampal neurons, NM blocked these TRPM7-mediated currents with an apparent affinity of 27 μM, as well as the paradoxical Ca²⁺ influx associated with lowering extracellular Ca²⁺. Unexpectedly, pre-exposure to NM strongly potentiated TRPM7 currents. In the presence of physiological concentrations of extracellular divalent cations, NM activates TRPM7. The stimulating effects of NM on TRPM7 currents are also inversely related to extracellular Ca²⁺ and Mg²⁺. DAPI and HSB but not netropsin, blocked and stimulated TRPM7. In contrast, mono-cationic, the metabolites of NM, p-GBA and AN, as well as protease inhibitor leupeptin and gabexate failed to substantially modulate TRPM7. NM thus provides a molecular template for the design of putative modulators of TRPM7.

Identification and confirmation of biomarkers using an integrated platform for quantitative analysis of glycoproteins and their glycosylations

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver. However, accurate diagnosis can be difficult as most of the patients who develop this tumor have symptoms similar to those caused by longstanding liver disease. Herein we developed an integrated platform to discover the glycoprotein biomarkers in early HCC. At first, lectin arrays were applied to investigate the differences in glycan structures on serum glycoproteins from HCC and cirrhosis patients. The intensity for AAL and LCA was significantly higher in HCC, indicating an elevation of fucosylation level. Then serum from 10 HCC samples and 10 cirrhosis samples were used to screen the altered fucosylated proteins by a combination of Exactag labeling, lectin extraction and LC-MS/MS. Finally, 27 HCC and 27 cirrhosis serum samples were used for lectin-antibody arrays to confirm the change of these fucosylated proteins. C3, CE, HRG, CD14 and HGF were found to be biomarker candidates for distinguishing early HCC from cirrhosis, with a sensitivity of 72% and specificity of 79%. Our work gives insight to the detection of early HCC, and the application of this comprehensive strategy has the potential to facilitate biomarker discovery on a large scale.

Heme oxygenase-1 protects donor livers from ischemia/reperfusion injury: the role of Kupffer cells

AIM

To examine whether heme oxygenase (HO)-1 overexpression would exert direct or indirect effects on Kupffer cells activation, which lead to aggravation of reperfusion injury.

METHODS

Donors were pretreated with cobalt protoporphyrin (CoPP) or zinc protoporphyrin (ZnPP), HO-1 inducer and antagonist, respectively. Livers were stored at 4 degrees C for 24 h before transplantation. Kupffer cells were isolated and cultured for 6 h after liver reperfusion.

RESULTS

Postoperatively, serum transaminases were significantly lower and associated with less liver injury when donors were pretreated with CoPP, as compared with the ZnPP group. Production of the cytokines tumor necrosis factor-alpha and interleukin-6 generated by Kupffer cells decreased in the CoPP group. The CD14 expression levels (RT-PCR/Western blots) of Kupffer cells from CoPP-pretreated liver grafts reduced.

CONCLUSION

The study suggests that the potential utility of HO-1 overexpression in preventing ischemia/reperfusion injury results from inhibition of Kupffer cells activation.

Betaine inhibits Toll-like receptor 4 expression in rats with ethanol-induced liver injury

AIM: To test whether ethanol feeding could induce Toll-like receptor 4 (TLR4) responses, assess the hepatoprotective effect of betaine and its inhibitive effect on TLR4 in animal models of alcoholic liver injury.

METHODS: Forty-eight female Sprague-Dawley rats were randomly divided into four groups as control, model, low and high dose betaine groups. Except control group, all rats were fed with high fat-containing diet plus ethanol and fish oil gavages for 8 wk. Betaine was administered intragastrically after exposure of ethanol for 4 wk. The changes of liver histology were examined. The expression of TLR4 mRNA and protein was detected by RT-PCR and Western blotting, respectively. The serum aminotransferase activity [alanine transarninase (ALT), aspartate aminotransferase (AST)], serum endotoxin, and liver inflammatory factors [tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-18 (IL-18)] were also assayed.

RESULTS: Compared with control group, rats of model group developed marked liver injury, accompanied by an increase of ALT (159.41 ± 7.74 U/L vs 59.47 ± 2.34 U/L, P < 0.0001), AST (248.25 ± 1.40 U/L vs 116.89 ± 3.48 U/L, P < 0.0001), endotoxin (135.37 ± 30.17 ng/L vs 44.15 ± 7.54 ng/L, P < 0.0001), TNF-α (20.81 ± 8.58 pg/mL vs 9.34 ± 2.57 pg/mL, P = 0.0003), IFN-γ (30.18 ± 7.60 pg/mL vs 16.86 ± 9.49 pg/mL, P = 0.0039) and IL-18 (40.99 ± 8.25 pg/mL vs 19.73 ± 9.31 pg/mL, P = 0.0001). At the same time, the expression of TLR4 mRNA and protein was markedly induced in the liver after chronic ethanol consumption (1.45 ± 0.07 vs 0.44 ± 0.04, P < 0.0001; 1.83 ± 0.13 vs 0.56 ± 0.08, P < 0.0001). Compared with model group, betaine feeding resulted in significant decreases of ALT (64.93 ± 6.06 U/L vs 159.41 ± 7.74 U/L, P < 0.0001), AST (188.73 ± 1.11 U/L vs 248.25 ± 1.40 U/L, P < 0.0001), endotoxin (61.80 ± 12.56 ng/L vs 135.37 ± 30.17 ng/L, P < 0.0001), TNF-α (9.79 ± 1.32 pg/mL vs 20.81 ± 8.58 pg/mL, P = 0.0003), IFN-γ (18.02 ± 5.96 pg/mL vs 30.18 ± 7.60 pg/mL, P = 0.0008) and IL-18 (18.23 ± 7.01 pg/mL vs 40.99 ± 8.25 pg/mL, P < 0.0001). Betaine also improved liver steatosis. The expression levels of TLR4 mRNA or protein in liver tissues were significantly lowered (0.62 ± 0.04 vs 1.45 ± 0.07, P < 0.0001; and 0.65 ± 0.06 vs 1.83 ± 0.13, P < 0.0001). There was a statistical difference of TLR4 mRNA and protein expression between high- and low-dose betaine groups (0.62 ± 0.04 vs 0.73 ± 0.05, P < 0.0001, and 0.65 ± 0.06 vs 0.81 ± 0.09, P < 0.0001).

CONCLUSION: Betaine can prevent the alcohol-induced liver injury effectively and improve the liver function. The expression of TLR4 increases significantly in ethanol-fed rats and betaine administration can inhibit TLR4 expression.

Nafamostat prevents hypothermia and improves survival time after administration of lipopolysaccharide in a mouse surgical model

Lipopolysaccharide (LPS) is an endotoxin known to induce disseminated intravascular coagulation and multiple organ failure followed by septic shock in animals. Nafamostat is a synthetic protease inhibitor with anticoagulant effects. This study investigated the effect of systemic administration of nafamostat on thermogenic homeostasis and survival time in a mouse surgical model. Male C57Bl/6 mice were anesthetized with sevoflurane and implanted with intraabdominal telemetry transmitters. Following the surgery, three groups of animals were administered Escherichia coli LPS (0127: B8) subcutaneously at doses of 0.3, 1.0, or 3.0 mg kg(-1), and one group received saline without LPS. Three other groups received 3 mg.kg(-1) LPS with 1, 3, or 10 mg kg(-1) of nafamostat. In another group 10 mg kg(-1)1 of nafamostat only was administered. The times to the onset of hypothermia (body temperature < 30 degrees C) and death were determined. L LPS significantly shortened the duration of both normothermia and survival, and nafamostat prolonged the normothermic periods that were reduced b 3 mg.kg(-1) LPS. Survival time was significantly correlated with the duration of normothermia (n = 48; r (2) = 0.779; P < 0.000001). The results demonstrated the effect of systemic administration of nafamostat against LPS-induced hypothermia. Nafamostat prevented hypothermia, and the consequent normal thermoregulation may have prolonged the survival period.

Role of Kupffer cells in the pathogenesis of endotoxin-induced liver injury

Endotoxin (lipopolysaccharide, LPS)-induced liver injury was involved in the initiation and development of various liver diseases, and liver macrophages (Kupffer cells) were demonstrated to play important roles in these processes. On one hand, Kupffer cells were activated to release pro-inflammatory factors via the system of LPS-induced signal transduction, and this responsibility was also cooperated by the interaction of other liver cells to mediate liver injury. On the other hand, the activation of Kupffer cells were also inhibited by LPS tolerance and other physiological regulatory mechanisms, which prevented the liver injury mediated by Kupffer cells. Thus, Kupffer cells were simultaneously co-stimulated by factors of activation and inhibition to keep a relative balance. LPS-induced liver injury may occur once the balance is pathologically broken, whereas inhibitory intervention of Kupffer cells' activation is a key strategy to protect the LPS-induced injury.

A method for quantifying the unstable and highly polar drug nafamostat mesilate in human plasma with optimized solid-phase extraction and ESI-MS detection: more accurate evaluation for pharmacokinetic study

An advanced quantification method was developed with solid-phase extraction (SPE) and mass spectrometry (MS) determination for nafamostat, an unstable and highly polar drug, in human plasma. For unstable drugs with an ester group, the main analytical challenge is how to avoid the ester hydrolysis, and strong acid or alkaline conditions should be excluded during sample preparation. Considering that, we developed a relatively mild method with SPE for sample preparation without strong acid and alkaline treatment, which was optimized with different pHs and salt concentrations in phosphate-buffered saline treatment. The results indicated that pH 5 gave the most efficient extraction and 0.1 M salt concentration enhanced the extraction the most, with a minor effect on MS monitoring. The extraction method effectively avoided drug hydrolysis and achieved good drug enrichment over 82.2%. The linear range of quantification was 1.25-160 ng mL(-1). The stability of the drug in sample treatment was fully validated according to the sample processing procedure, including the stability in fresh blood, mobile phase, plasma and acidic methanol, and the results indicated that the drug remained stable during the whole sample preparation. Compared with a previous isotope-labeling method, more accurate and specific quantification of plasma concentration was achieved with liquid chromatography-electrospray ionization MS determination. With use of our method, nafamostat mesilate pharmacokinetics in 30 Chinese healthy volunteers was investigated with three doses via intravenous-drip infusion. The pharmacokinetic parameters were also estimated and compared with those of Japanese volunteers (slightly lower plasma concentration and longer terminal elimination half-life for Chinese volunteers). The difference in the pharmacokinetics may be ascribed to the quantification method, because previous isotope labeling may have overestimated the parent drug.

Up-regulation of IRAK-M is essential for endotoxin tolerance induced by a low dose of lipopolysaccharide in Kupffer cells

BACKGROUND

Endotoxin tolerance (ET) is an important mechanism to maintain the homeostasis of Kupffer cells (KCs), because KCs are continually exposed to various pathogen-associated molecular patterns including lipopolysaccharide (LPS). ET involves multiple changes in cell signal transduction pathways; however, not all signaling pathways are down-regulated and some proteins are up-regulated. The latter proteins may be counter regulatory, including interleukin-1 receptor-associated kinase M (IRAK-M) expression. The aim of this study is to clarify weather or not IRAK-M is involved in the mechanisms of ET in KCs through dampening nuclear factor-kappa B (NF-kappaB) mediated pathway.

MATERIALS AND METHODS

KCs isolated from male C57BL/6J mice were seeded in 24-well plates at 1 x 10(6) cells/well and cultured overnight prior to transfection, were randomly divided into two groups: the pIRAK-M-short hairpin RNA (shRNA) group (transfected with IRAK-M shRNA) and the control group (transfected with control vector); 24 h after transfection, the two groups were further randomly divided into two subgroups: non-endotoxin pretreatment group (incubation in Dulbecco's modified Eagle's medium [Invitrogen, Carlsbad, CA] with 10% fetal bovine serum) and endotoxin pretreatment group (incubation in the same medium containing 10 ng/mL LPS), named pIRAK-M-EP, pIRAK-M-NEP, pCV-EP, and pCV-NEP, respectively. Each subgroup contained 6 wells; 24 h later, fresh media containing LPS (100 ng/mL) was added to each subgroup and incubated for an additional 3 h. The expression of IRAK-M gene and protein level were determined by reverse transcription-polymerase chain reaction and Western blot, the activities of NF-kappaB were estimated by electrophoretic mobility shift assay and enzyme-linked immunosorbent assay, and the supernatant tumor necrosis factor-alpha levels were analyzed by enzyme-linked immunosorbent assay.

RESULTS

The recombinant plasmid of pIRAK-M-shRNA specifically inhibited IRAK-M expression after it was transfected into KCs. At 3 h after 100 ng/mL LPS was added to the medium, IRAK-M expression was significantly induced in pCV-EP than that in pCV-NEP; however, there was no difference between pIRAK-M-NEP and pIRAK-M-EP, accompanied with lowest level of NF-kappaB activation and tumor necrosis factor-alpha levels in pCV-EP, and a dramatic enhancement in the other three groups (P < 0.01).

CONCLUSIONS

Although a primary low dose of LPS stimulation obviously attenuated KCs response to the second LPS stimulation, the inhibitive influences were partly refracted in pIRAK-M-EP than in pCV-EP, indicating that the absence of IRAK-M caused abnormal enhancement of inflammatory effects. IRAK-M negatively regulates toll-like receptors signaling and involves in the mechanisms of ET in KCs through dampening NF-kappaB mediated pathway; therefore it may be a key component of this important control system, and a new target for the clinical treatment of sepsis.