The pharmacokinetic and biological activity profile of dexamethasone targeted to sinusoidal endothelial and Kupffer cells

Recent updates in applications of nanomedicine for the treatment of hepatic fibrosis

Over recent decades, nanomedicine has played an important role in the enhancement of therapeutic outcomes compared to those of conventional therapy. At the same time, nanoparticle drug delivery systems offer a significant reduction in side effects of treatments by lowering the off-target biodistribution of the active pharmaceutical ingredients. Cancer nanomedicine represents the most extensively studied nanotechnology application in the field of pharmaceutics and pharmacology since the first nanodrug for cancer treatment, liposomal doxorubicin (Doxil®), has been approved by the FDA. The advancement of cancer nanomedicine and its enormous technological success also included various other target diseases, including hepatic fibrosis. This confirms the versatility of nanomedicine for improving therapeutic activity. In this review, we summarize recent updates of nanomedicine platforms for improving therapeutic efficacy regarding liver fibrosis. We first emphasize the challenges of conventional drugs for penetrating the biological barriers of the liver. After that, we highlight design principles of nanocarriers for achieving improved drug delivery of antifibrosis drugs through passive and active targeting strategies.

Drug Targeting and Nanomedicine: Lessons Learned from Liver Targeting and Opportunities for Drug Innovation

Drug targeting and nanomedicine are different strategies for improving the delivery of drugs to their target. Several antibodies, immuno-drug conjugates and nanomedicines are already approved and used in clinics, demonstrating the potential of such approaches, including the recent examples of the DNA- and RNA-based vaccines against COVID-19 infections. Nevertheless, targeting remains a major challenge in drug delivery and different aspects of how these objects are processed at organism and cell level still remain unclear, hampering the further development of efficient targeted drugs. In this review, we compare properties and advantages of smaller targeted drug constructs on the one hand, and larger nanomedicines carrying higher drug payload on the other hand. With examples from ongoing research in our Department and experiences from drug delivery to liver fibrosis, we illustrate opportunities in drug targeting and nanomedicine and current challenges that the field needs to address in order to further improve their success.

Release of CXCL12 From Apoptotic Skeletal Cells Contributes to Bone Growth Defects Following Dexamethasone Therapy in Rats

Dexamethasone (Dex) is known to cause significant bone growth impairment in childhood. Although previous studies have suggested roles of osteocyte apoptosis in the enhanced osteoclastic recruitment and local bone loss, whether it is so in the growing bone following Dex treatment requires to be established. The current study addressed the potential roles of chemokine CXCL12 in chondroclast/osteoclast recruitment and bone defects following Dex treatment. Significant apoptosis was observed in cultured mature ATDC5 chondrocytes and IDG-SW3 osteocytes after 48 hours of 10^-6  M Dex treatment, and CXCL12 was identified to exhibit the most prominent induction in Dex-treated cells. Conditioned medium from the treated chondrocytes/osteocytes enhanced migration of RAW264.7 osteoclast precursor cells, which was significantly inhibited by the presence of the anti-CXCL12 neutralizing antibody. To investigate the roles of the induced CXCL12 in bone defects caused by Dex treatment, young rats were orally gavaged daily with saline or Dex at 1 mg/kg/day for 2 weeks, and received an intraperitoneal injection of anti-CXCL12 antibody or control IgG (1 mg/kg, three times per week). Aside from oxidative stress induction systemically, Dex treatment caused reductions in growth plate thickness, primary spongiosa height, and metaphysis trabecular bone volume, which are associated with induced chondrocyte/osteocyte apoptosis and enhanced chondroclast/osteoclast recruitment and osteoclastogenic differentiation potential. CXCL12 was induced in apoptotic growth plate chondrocytes and metaphyseal bone osteocytes. Anti-CXCL12 antibody supplementation considerably attenuated Dex-induced chondroclast/osteoclast recruitment and loss of growth plate cartilage and trabecular bone. CXCL12 neutralization did not affect bone marrow osteogenic potential, adiposity, and microvasculature. Thus, CXCL12 was identified as a potential molecular linker between Dex-induced skeletal cell apoptosis and chondroclastic/osteoclastic recruitment, as well as growth plate cartilage/bone loss, revealing a therapeutic potential of CXCL12 functional blockade in preventing bone growth defects during/after Dex treatment. © 2018 American Society for Bone and Mineral Research.

Nanotoxicity: a key obstacle to clinical translation of siRNA-based nanomedicine

siRNAs have immense therapeutic potential for the treatment of various gene-related diseases ranging from cancer, viral infections and neuropathy to autoimmune diseases. However, their bench-to-bedside translation in recent years has faced several challenges, with inefficient siRNA delivery being one of the most frequently encountered issues. In order to improve the siRNA delivery especially for systemic treatment, nanocarriers made of polymers, lipids or inorganic materials have become almost essential. The 'negative' aspects of these carriers such as their nanotoxicity and immunogenicity thus can no longer be overlooked. In this article, we will extensively review the nanotoxicity of siRNA carriers. The strategies for mitigating the risks of nanotoxicity and the methodology for evaluating these strategies will also be discussed. By addressing this often overlooked but important issue, it will help clear the way for siRNAs to fulfill their promise as a versatile class of therapeutic agents.

Targeted delivery of drugs for liver fibrosis

Liver fibrosis and its end stage disease cirrhosis are a major cause of mortality and morbidity around the world. There is no effective pharmaceutical intervention for liver fibrosis at present. Many drugs that show potent antifibrotic activities in vitro often show only minor effects in vivo because of insufficient concentrations of drugs accumulating around the target cell and their adverse effects as a result of affecting other non-target cells. Hepatic stellate cells (HSC) play a critical role in the fibrogenesis of liver, so they are the target cells of antifibrotic therapy. Several kinds of targeted delivery system that could target the receptors expressed on HSC have been designed, and have shown an attractive targeted potential in vivo. After being carried by these delivery systems, many agents showed a powerful antifibrotic effect in animal models of liver fibrosis. These targeted delivery systems provide a new pathway for the therapy of liver fibrosis. The characteristics of theses targeted carriers are reviewed in this paper.

Lipid peroxidation in the liver of mice during development of granulomatous inflammation after combined infection with C. albicans and M. tuberculosis

Activity of LPO in the liver of CBA mice during the development of granulomatous inflammation after combined infection with C. albicans and M. tuberculosis was evaluated by the levels of conjugated dienes, ketodienes, conjugated trienes, and products of interactions between intermediate LPO products and 2-TBA. The content of primary and secondary LPO products peaked on days 3 and 10 after infection by C. albicans, respectively. After M. tuberculosis infection, the maximum accumulation of TBA-active LPO products in the liver was noted on day 3, while the level of primary lipid peroxides virtually did not increase. The dynamics of primary and secondary LPO products in the liver during granulomatous inflammation development was similar to that during infection of mice with C. albicans alone. Hence, the development of granulomatous inflammation induced by C. albicans or M. tuberculosis or both these agents, was associated with increased LPO activity in the liver. The dynamics of primary and secondary LPO products depended on the infectious agent or combination of agents.

Dexamethasone alters the hepatic inflammatory cellular profile without changes in matrix degradation during liver repair following biliary decompression

BACKGROUND

Biliary atresia is characterized by extrahepatic bile duct obliteration along with persistent intrahepatic portal inflammation. Steroids are standard in the treatment of cholangitis following the Kasai portoenterostomy, and were advocated for continued suppression of the ongoing immunologic attack against intrahepatic ducts. Recent reports, however, have failed to demonstrate an improved patient outcome or difference in the need for liver transplant in postoperative patients treated with a variety of steroid regimes compared with historic controls. In the wake of progressive liver disease despite biliary decompression, steroids are hypothesized to suppress inflammation and promote bile flow without any supporting data regarding their effect on the emerging cellular and molecular mechanisms of liver repair. We have previously shown in a reversible model of cholestatic injury that repair is mediated by macrophages, neutrophils, and specific matrix metalloproteinase activity (MMP8); we questioned whether steroids would alter these intrinsic mechanisms.

METHODS

Rats underwent biliary ductal suspension for 7 d, followed by decompression. Rats were treated with IV dexamethasone or saline at the time of decompression. Liver tissue obtained at the time of decompression or after 2 d of repair was processed for morphometric analysis, immunohistochemistry, and quantitative RT-PCR.

RESULTS

There was a dramatic effect of dexamethasone on the inflammatory component with the initiation of repair. Immunohistochemistry revealed a reduction of both ED1+ hepatic macrophages and ED2+Kupffer cells in repair compared with saline controls. Dexamethasone treatment also reduced infiltrating neutrophils by day 2. TNF-alpha expression, increased during injury in both saline and dexamethasone groups, was markedly reduced by dexamethasone during repair (day 2) whereas IL-6, IL-10, and CINC-1 remained unchanged compared with saline controls. Dexamethasone reduced both MMP8 and TIMP1 expression by day 2, whereas MMP9, 13, and 14 were unchanged compared with sham controls. Despite substantial cellular and molecular changes during repair, collagen resorption was the same in both groups

CONCLUSION

Dexamethasone has clear effects on both the hepatic macrophage populations and infiltrating neutrophils following biliary decompression. Altered MMP and TIMP gene expression might suggest that steroids have the potential to modify matrix metabolism during repair. Nevertheless, successful resorption of collagen fibrosis proceeded presumably through other MMP activating mechanisms. We conclude that steroids do not impede the rapid intrinsic repair mechanisms of matrix degradation required for successful repair.

Effect of Glucocorticoid Pretreatment on Oxidative Liver Injury and Survival in Jaundiced Rats with Endotoxin Cholangitis

INTRODUCTION

Biliary tract infection is associated with high mortality. This study investigated the effect of glucocorticoid pretreatment on lipopolysaccharide (LPS)-induced cholangitis.

METHODS

Rats undergoing either sham operation or ligation of the extrahepatic bile duct (BDL) for 2 weeks were randomly assigned to receive intravenous injections of dexamethasone (DX) or normal saline (NS) prior to infusing LPS into the biliary tract. The plasma levels of tumor necrosis factor-alpha (TNFalpha), chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) as well as liver mRNA expression of MCP-1 and MIP-2 were determined. Infiltration of monocytes, Kupffer cells, and neutrophils in rat liver were studied with immunohistochemistry. Oxidative liver injury was measured by the malondialdehyde (MDA) content.

RESULTS

Dexamethasone pretreatment resulted in significantly decreased plasma levels of TNFalpha at 1 hour, MCP-1 and MIP-2 at 2 and 3 hours, and decreased liver MCP-1 mRNA expression at 3 hours following LPS infusion in BDL-DX rats than in BDL-NS rats. The number of inflammatory cells in the liver was significantly different between sham- and BDL-treated rats but was not affected by DX pretreatment. Pretreatment with DX resulted in significantly decreased liver MDA contents in the BDL-DX group than that in the BDL-NS group. Jaundiced rats pretreated with 5 mg DX prior to infusion of 1 g of LPS were 6.8 times more likely to survive than those that were not pretreated.

CONCLUSIONS

Pretreatment of jaundiced, LPS-treated rats with a supraphysiological dose of dexamethasone may rescue their lives by suppression of chemokine expression and alleviation of oxidative liver injury.

Glucocorticoid pretreatment suppresses chemokine expression and inflammatory cell infiltration in cholestatic rats receiving biliary intervention

AIM

Biliary intervention may augment chemokine expression and inflammatory cell infiltration and aggravates liver injury in cholestatic rats. We tested the efficacy of glucocorticoid pretreatment to prevent the complications.

METHODS

A model of biliary intervention was established in rats without (sham) or with bile duct ligation (BDL). Before biliary intervention, rats were randomly assigned to receiving intravenous injection of dexamethasone (DX group) or normal saline (NS group). Plasma levels of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) were measured with enzyme-linked immunosorbent assay, and liver messenger RNA of these chemokines was quantified with real-time quantitative reverse transcriptase-polymerase chain reaction. Monocytes, Kupffer cells, and neutrophils in the rat liver were characterized with antibodies to ectodermal dysplasia 1 (ED1), ED2, and myeloperoxidase, respectively.

RESULTS

By 3 hours after biliary intervention, plasma MCP-1 and MIP-2 proteins in BDL-NS rats were significantly higher than in BDL-DX. At 3 hours, liver MCP-1 and MIP-2 messenger RNA levels were significantly upregulated in BDL-NS than in BDL-DX. The amount of ED1-, ED2- and myeloperoxidase-staining cells were significantly greater in BDL-NS than in BDL-DX. Most of the changes returned to baseline levels by 24 hours.

CONCLUSION

Glucocorticoid pretreatment suppresses chemokine expression and inflammatory cell infiltration, which may consequently alleviate liver injury in cholestatic rats receiving biliary intervention.

Dose-related effects of dexamethasone on liver damage due to bile duct ligation in rats

AIM: To evaluate the effects of dexamethasone on liver damage in rats with bile duct ligation.

METHODS: A total of 40 male Sprague-Dawley rats, weighing 165-205 g, were used in this study. Group 1 (sham-control, n = 10) rats underwent laparotomy alone and the bile duct was just dissected from the surrounding tissue. Group 2 rats (untreated, n = 10) were subjected to bile duct ligation (BDL) and no drug was applied. Group 3 rats (low-dose dexa, n = 10) received a daily dose of dexamethasone by orogastric tube for 14 d after BDL. Group 4 rats (high-dose dexa, n = 10) received a daily dose of dexamethasone by orogastric tube for 14 d after BDL. At the end of the two-week period, biochemical and histological evaluations were processed.

RESULTS: The mean serum bilirubin and liver enzyme levels significantly decreased, and superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) values were significantly increased in low-dose dexa and high-dose dexa groups when compared to the untreated group. The histopathological score was significantly less in the low-dose and high-dose dexa groups compared to the untreated rats. In the low-dose dexa group, moderate liver damage was seen, while mild liver damage was observed in the high-dose dexa group.

CONCLUSION: Corticosteroids reduced liver damage produced by bile duct obstruction. However, the histopathological score was not significantly lower in the high-dose corticosteroid group as compared to the low-dose group. Thus, low-dose corticosteroid provides a significant reduction of liver damage without increased side effects, while high dose is associated not with lower fibrosis but with increased side effects.

Production of pro- and anti-fibrotic agents by rat Kupffer cells; the effect of octreotide

Kupffer cells may be involved in liver fibrogenesis through production of TGF-beta1. Their role in fibrinolysis is less clear. Octreotide, a synthetic analogue of somatostatin, is often used in cirrhotic patients. Its effect on Kupffer cells was studied. Isolated rat Kupffer cells were cultured in the presence of lipopolysaccharide and/or octreotide. TGF-beta1, leptin, collagenase (MMP-1), and urokinase-type plasminogen activator (uPA) were assessed in supernatants by ELISA, and MMP-2 and MMP-9 by zymography. Kupffer cells produced large amounts of MMP-1 and lipopolysaccharide induced a significant (P < 0.02) early increase. Octreotide and lipopolysaccharide caused a synergistic effect on MMP-1 secretion. By contrast, MMP-9 production stimulated by lipopolysaccharide was suppressed by octreotide. Kupffer cells produced a basal amount of uPA, significantly increased after lipopolysaccharide or octreotide incubation (P < 0.001). Large amounts of TGF-beta1 were produced in a time-dependent manner by unstimulated Kupffer cells. Lipopolysaccharide and octreotide, alone or in combination, induced a significant inhibition of this production (P < 0.01). Kupffer cells did not produce leptin, a recently identified mediator of liver fibrosis, or MMP-2. Kupffer cells may play a significant role in liver fibrinolysis. Octreotide, acting on TGF-beta1, uPA, and MMP-1 production, may be a useful agent for fibrosis resolution.