Effects of interferon-gamma liposomes targeted to platelet-derived growth factor receptor-beta on hepatic fibrosis in rats

Development of a Chimeric Protein BiPPB-mIFNγ-tTβRII for Improving the Anti-Fibrotic Activity in Vivo by Targeting Fibrotic Liver and Dual Inhibiting the TGF-β1/Smad Signaling Pathway

Excessive production of transforming growth factor β1 (TGF-β1) in activated hepatic stellate cells (aHSCs) promotes liver fibrosis by activating the TGF-β1/Smad signaling pathway. Thus, specifically inhibiting the pro-fibrotic activity of TGF-β1 in aHSCs is an ideal strategy for treating liver fibrosis. Overexpression of platelet-derived growth factor β receptor (PDGFβR) has been demonstrated on the surface of aHSCs relative to normal cells in liver fibrosis. Interferon-gamma peptidomimetic (mIFNγ) and truncated TGF-β receptor type II (tTβRII) inhibit the TGF-β1/Smad signaling pathway by different mechanisms. In this study, we designed a chimeric protein by the conjugation of (1) mIFNγ and tTβRII coupled via plasma protease-cleavable linker sequences (FNPKTP) to (2) PDGFβR-recognizing peptide (BiPPB), namely BiPPB-mIFNγ-tTβRII. This novel protein BiPPB-mIFNγ-tTβRII was effectively prepared using Escherichia coli expression system. The active components BiPPB-mIFNγ and tTβRII were slowly released from BiPPB-mIFNγ-tTβRII by hydrolysis using the plasma protease thrombin in vitro. Moreover, BiPPB-mIFNγ-tTβRII highly targeted to fibrotic liver tissues, markedly ameliorated liver morphology and fibrotic responses in chronic liver fibrosis mice by both inhibiting the phosphorylation of Smad2/3 and inducing the expression of Smad7. Meanwhile, BiPPB-mIFNγ-tTβRII markedly reduced the deposition of collagen fibrils and expression of fibrosis-related proteins in acute liver fibrosis mice. Furthermore, BiPPB-mIFNγ-tTβRII showed a good safety performance in both liver fibrosis mice. Taken together, BiPPB-mIFNγ-tTβRII improved the in vivo anti-liver fibrotic activity due to its high fibrotic liver-targeting potential and the dual inhibition of the TGF-β1/Smad signaling pathway, which may be a potential candidate for targeting therapy on liver fibrosis.

Fingolimod (FTY720) Hinders Interferon-γ-Mediated Fibrotic Scar Formation and Facilitates Neurological Recovery After Spinal Cord Injury

Following spinal cord injury (SCI), fibrotic scar inhibits axon regeneration and impairs neurological function recovery. It has been reported that T cell-derived interferon (IFN)-γ plays a pivotal role in promoting fibrotic scarring in neurodegenerative disease. However, the role of IFN-γ in fibrotic scar formation after SCI has not been declared. In this study, a spinal cord crush injury mouse was established. Western blot and immunofluorescence showed that IFN-γ was surrounded by fibroblasts at 3, 7, 14, and 28 days post-injury. Moreover, IFN-γ is mainly secreted by T cells after SCI. Further, in situ injection of IFN-γ into the normal spinal cord resulted in fibrotic scar formation and inflammation response at 7 days post-injection. After SCI, the intraperitoneal injection of fingolimod (FTY720), a sphingosine-1-phosphate receptor 1 (S1PR1) modulator and W146, an S1PR1 antagonist, significantly reduced T cell infiltration, attenuating fibrotic scarring via inhibiting IFN-γ/IFN-γR pathway, while in situ injection of IFN-γ diminished the effect of FTY720 on reducing fibrotic scarring. FTY720 treatment inhibited inflammation, decreased lesion size, and promoted neuroprotection and neurological recovery after SCI. These findings demonstrate that the inhibition of T cell-derived IFN-γ by FTY720 suppressed fibrotic scarring and contributed to neurological recovery after SCI.

RNA nanomedicine in liver diseases

The remarkable impact of RNA nanomedicine during the COVID-19 pandemic has demonstrated the expansive therapeutic potential of this field in diverse disease contexts. In recent years, RNA nanomedicine targeting the liver has been paradigm-shifting in the management of metabolic diseases such as hyperoxaluria and amyloidosis. RNA nanomedicine has significant potential in the management of liver diseases, where optimal management would benefit from targeted delivery, doses titrated to liver metabolism, and personalized therapy based on the specific site of interest. In this review, we discuss in-depth the different types of RNA and nanocarriers used for liver targeting along with their specific applications in metabolic dysfunction-associated steatotic liver disease, liver fibrosis, and liver cancers. We further highlight the strategies for cell-specific delivery and future perspectives in this field of research with the emergence of small activating RNA, circular RNA, and RNA base editing approaches.

Albumin-Based Silibinin Nanocrystals Targeting Activated Hepatic Stellate Cells for Liver Fibrosis Therapy

Activated hepatic stellate cells (aHSCs) are critical during the development and progression of liver fibrosis. Once liver fibrosis occurs, aHSCs highly express secreted protein, acidic and rich in cysteine (SPARC), a typical albumin-binding protein. We designed a nano platform, silibinin albumin nanocrystals (SLB-HSA NCs), to target aHSCs for liver fibrosis therapy. The prepared SLB-HSA NCs showed uniform particle size distribution of approximately 60 nm with PDI < 0.15 and high loading efficiency up to 49.4%. Albumin coated on the surface of nanocrystals was demonstrated to increase cellular uptake by aHSCs through SPARC-mediated endocytosis. In addition, SLB-HSA NCs significantly improved the bioavailability compared with free SLB in pharmacokinetic study. Following tail-vein injection, SLB-HSA NCs were massively accumulated in the fibrotic liver and exhibited enhanced antifibrotic effects in hepatic fibrosis mice. Overall, our findings prove the great potential of SLB-HSA NCs in the targeted treatment of liver fibrosis.

Hepatic Stellate Cell Targeting Using Peptide-Modified Biologicals

Liver diseases are a leading cause of death worldwide and are rising exponentially due to increasing prevalence of metabolic disorders. Hepatic stellate cells (HSCs) are recognized as a key therapeutic target in liver diseases as these cells, upon activation during liver damage and ongoing liver inflammation, secrete excessive amounts of extracellular matrix that leads to liver tissue scarring (fibrosis) responsible for liver dysfunction (end-stage liver disease) and desmoplasia in hepatocellular carcinoma. Targeting of HSCs to reverse fibrosis progression has been realized by several experts in the field, including us. We have developed strategies to target activated HSCs by utilizing the receptors overexpressed on the surface of activated HSCs. One well-known receptor is platelet derived growth factor receptor-beta (PDGFR-β). Using PDGFR-β recognizing peptides (cyclic PPB or bicyclic PPB), we can deliver biologicals, e.g., interferon gamma (IFNγ) or IFNγ activity domain (mimetic IFNγ), to the activated HSCs that can inhibit their activation and reverse liver fibrosis. In this chapter, we provide the detailed methods and the principles involved in the synthesis of these targeted (mimetic) IFNγ constructs. These methods can be adapted for synthesizing constructs for targeted/cell-specific delivery of peptides/proteins, drugs, and imaging agents useful for various applications including diagnosis and treatment of inflammatory and fibrotic diseases and cancer.

Visualization system based on hierarchical targeting for diagnosis and treatment of hepatocellular carcinoma

The accuracy and enrichment rate of targeted drugs largely determine the clinical diagnosis and treatment effect. Therefore, the accuracy and enrichment rate of targeted drugs should be improved. We designed a visual diagnosis and treatment system based on hierarchical targeting. It consists of multifunctional magnetic nanoparticles and a bio magnetic material. Bio-magnet mediated primary targeting can effectively improve the drug enrichment rate in the target tissue. SNF peptide/epithelial cell adhesion molecule antibody mediated targeting liver cancer stem cells (LCSCs) (secondary target) can improve the accuracy of the treatment and its outcomes. Low intensity focused ultrasound irradiation can explode nanoparticles around LCSCs, which can cause physical damage to cells. The combination of released interferon gamma and its receptor (tertiary target) can be used to initiate chemotherapy and immunotherapy. Using the optical properties of Fe₃O₄ and the phase transformation ability of perfluoropentane, the system can enhance photoacoustic and ultrasonic molecular imaging enabling diagnosis and treatment visualization. Targeting LCSCs can accurately provide physical, chemical, and immune treatment of Hepatocellular carcinoma, making the therapeutic effect more effective and thorough. This system may provide a new method for a more accurate visual diagnosis and treatment of tumors.

Vesicular IFN-γ as a cooperative attacker to enhance anti-cancer effect of 5-fluorouracil via thymidine phosphorylase upregulation and tumor microenvironment normalization

On the basis of immuno-modulating effect and upregulating the activity of thymidine phosphorylase (TP), interferon-γ (IFN-γ) as a cooperative attacker was explored to enhance the anticancer activity of 5-fluorouracil (5-FU). We designed and prepared a self-assembled nano-vesicular system IFN-γ-EDP formulated by amphiphilic poly((polyethylene glycol)(dodecylphosphoethanolamine)phosphazene) (EDP) to entrap IFN-γ in the hydrophilic cavity. The IFN-γ-EDP vesicles allowed IFN-γ to accumulate at the tumor site and be taken up by tumor cells, resulting in significantly upregulated expression level of TP, distinct inhibition of cell growth, more cellular apoptosis and more serious cell cycle arrest when administrated combined with 5-FU. Moreover, IFN-γ-EDP could normalize the tumor microenvironment by enhancing the CD4⁺ and CD8⁺ T cell populations, promoting the IL-12 secretion and suppressing the IL-10 secretion in tumor. As a consequence, the combination therapy of IFN-γ-EDP with 5-FU achieved remarkably enhanced tumor inhibition rate of 56.9% against CT26 colorectal cancer.

Nanotechnology in Drug Delivery for Liver Fibrosis

Liver fibrosis is a reversible disease course caused by various liver injury etiologies, and it can lead to severe complications, such as liver cirrhosis, liver failure, and even liver cancer. Traditional pharmacotherapy has several limitations, such as inadequate therapeutic effect and side effects. Nanotechnology in drug delivery for liver fibrosis has exhibited great potential. Nanomedicine improves the internalization and penetration, which facilitates targeted drug delivery, combination therapy, and theranostics. Here, we focus on new targets and new mechanisms in liver fibrosis, as well as recent designs and development work of nanotechnology in delivery systems for liver fibrosis treatment.

A magnetic resonance imaging modality for non-invasively distinguishing progression of liver fibrosis by visualizing hepatic platelet-derived growth factor receptor-beta expression in mice

BACKGROUND AND AIM

Activated hepatic stellate cells (HSCs) are the most critical cells responsible for liver fibrosis, and platelet-derived growth factor (PDGF) is the most prominent mitogen for HSCs in fibrogenesis. This study aimed to explore the potential of gadolinium (Gd)-labeled cyclic peptides (pPB) targeting PDGF receptor-β (PDGFR-β) as a magnetic resonance imaging (MRI) radiotracer to identify the progression of liver fibrosis by imaging hepatic PDGFR-β expression.

METHODS

Mice treated with carbon tetrachloride (CCl₄ ) were used to mimic hepatic fibrosis in vivo. The binding activity of FITC-labeled pPB to PDGFR-β was assessed in cultured human HSCs (HSC-LX2). MRI was performed to visualize hepatic PDGFR-β expression in mice with different degrees of liver fibrosis after Gd-labeled pPB was injected.

RESULTS

Hepatic PDGFR-β expression level was correlated with the severity of liver fibrosis, and the majority of cells expressing PDGFR-β were found to be activated HSCs in fibrotic livers. Culture-activated human HSCs expressed abundant PDGFR-β, and FITC-labeled pPB could bind to these cells in a concentration-dependent and time-dependent manner. With Gd-labeled pPB as a tracer, an MRI modality demonstrated that the relative hepatic T1-weighted MRI signal value progressively increased with the severity of hepatic fibrosis and reduced with remission.

CONCLUSIONS

Hepatic PDGFR-β expression reflects the progression of hepatic fibrosis, and MRI using Gd-labeled pPB as a tracer exhibits potential for distinguishing liver fibrosis staging in mice.

Forms and Methods for Interferon's Encapsulation

Interferons (IFNs) are cytokines involved in the immune response that act on innate and adaptive immunity. These proteins are natural cell-signaling glycoproteins expressed in response to viral infections, tumors, and biological inducers and constitute the first line of defense of vertebrates against infectious agents. They have been marketed for more than 30 years with considerable impact on the global therapeutic protein market thanks to their diversity in terms of biological activities. They have been used as single agents or with combination treatment regimens, demonstrating promising clinical results, resulting in 22 different formulations approved by regulatory agencies. The 163 clinical trials with currently active IFNs reinforce their importance as therapeutics for human health. However, their application has presented difficulties due to the molecules' size, sensitivity to degradation, and rapid elimination from the bloodstream. For some years now, work has been underway to obtain new drug delivery systems to provide adequate therapeutic concentrations for these cytokines, decrease their toxicity and prolong their half-life in the circulation. Although different research groups have presented various formulations that encapsulate IFNs, to date, there is no formulation approved for use in humans. The current review exhibits an updated summary of all encapsulation forms presented in the scientific literature for IFN-α, IFN-ß, and IFN-γ, from the year 1996 to the year 2021, considering parameters such as: encapsulating matrix, route of administration, target, advantages, and disadvantages of each formulation.

Therapeutic targets, novel drugs, and delivery systems for diabetes associated NAFLD and liver fibrosis

Type 2 diabetes mellitus (T2DM) associated non-alcoholic fatty liver disease (NAFLD) is the fourth-leading cause of death. Hyperglycemia induces various complications, including nephropathy, cirrhosis and eventually hepatocellular carcinoma (HCC). There are several etiological factors leading to liver disease development, which involve insulin resistance and oxidative stress. Free fatty acid (FFA) accumulation in the liver exerts oxidative and endoplasmic reticulum (ER) stresses. Hepatocyte injury induces release of inflammatory cytokines from Kupffer cells (KCs), which are responsible for activating hepatic stellate cells (HSCs). In this review, we will discuss various molecular targets for treating chronic liver diseases, including homeostasis of FFA, lipid metabolism, and decrease in hepatocyte apoptosis, role of growth factors, and regulation of epithelial-to-mesenchymal transition (EMT) and HSC activation. This review will also critically assess different strategies to enhance drug delivery to different cell types. Targeting nanocarriers to specific liver cell types have the potential to increase efficacy and suppress off-target effects.

Interferon-γ liposome: a new system to improve drug delivery in the treatment of lung cancer

Lung cancer is one of the main causes of death worldwide. Published data show the use of interferons (IFNs) in treating lung tumours. IFNs also have potential for their antiproliferative, antiangiogenic, immunoregulatory and proapoptotic effects. IFN-γ functions as an anticancer agent against various forms of cancer. This study aimed to investigate the effect of IFN-γ liposome (nano) on peripheral lymphocytes from 20 individuals in each group: lung cancer patients compared to healthy individuals. The effectiveness of IFN-γ liposome against oxidative stress was also evaluated in this study. A concentration of 100 U·mL⁻¹ of IFN-γ liposome was used to treat the lymphocytes in the Comet and micronucleus assays based on the preliminary test for the optimal dose. The lymphocytes from lung cancer patients presented with higher DNA damage levels than those of healthy individuals. In healthy individuals, IFN-γ liposome did not cause any DNA damage in the lymphocytes. Also, it caused a significant reduction in DNA damage in the lymphocytes from lung cancer patients in both the Comet and micronucleus assays. The 100 U·mL⁻¹ of IFN-γ liposome significantly reduced the oxidative stress caused by H₂O₂ and appeared to be effective in both groups using the Comet and micronucleus assays. Results from both Comet and micronucleus assays were consistent. The data obtained indicated that IFN-γ in both forms (IFN-γ bulk and IFN-γ nanoliposome) may potentially be effective for the treatment of lung cancer and showed the ability of IFN-γ liposome to reduce DNA damage more than the bulk form.

A research article on the effect of bulk and nanoliposome interferon-γ on lymphocytes from patients with lung cancer compared to healthy controls: assessing the ability of IFN-γ liposome to reduce DNA damage more than the bulk formhttps://bit.ly/3wvfSyY

Application of TGF-β1, TIMP-1 and TIMP-2 small interfering RNAs can alleviate CCl4-induced hepatic fibrosis in rats by rebalancing Th1/Th2 cytokines

The present study aimed to investigate the effects of TGF-β1, tissue inhibitor of metalloproteinase (TIMP)-1 small interfering (si)RNA and TIMP-2 siRNA on hepatic fibrosis in rats and explore the T helper (Th)1/Th2 balance. Moreover, IFN-γ, IL-4 and IL-13 are the main cytokines associated with Th1/Th2 responses and have significant influence on the progression of hepatic fibrosis. The expression levels of IFN-γ, IL-4 and IL-13 in rats with hepatic fibrosis that were treated with siRNAs against the aforementioned molecules were measured using various techniques including immunohistochemical staining, western blotting and reverse transcription-quantitative PCR. The principal outcomes revealed the downregulation of IFN-γ and the upregulation of IL-4 and IL-13 in the model group compared with the normal group. Moreover, the expression of IFN-γ was significantly increased, while IL-4 and IL-13 demonstrated no significant difference in the TGF-β1 siRNA treatment group compared with the model group. The TIMP-1 and TIMP-2 siRNA treatment groups exhibited significantly increased expression levels of IFN-γ, but lower expression levels of IL-4 and IL-13 compared with the model group. These results indicated that TIMP-1 and TIMP-2 were improved antifibrotic targets compared with TGF-β1.

General sites of nanoparticle biodistribution as a novel opportunity for nanomedicine

The development of nanomedical devices has led to a considerable number of clinically applied nanotherapeutics. Yet, the overall poor translation of nanoparticular concepts into marketable systems has not met the initial expectations and led to increasing criticism in recent years. Most novel nano approaches thereby use highly refined formulations including a plethora of active targeting sequences, but ultimately fail to reach their target due to a generally high off-target deposition in organs such as the liver or kidney. In this context, we argue that initial nanoparticle (NP) development should not entirely become set on conventional formulation aspects. In contrast, we propose a change of focus towards a prior analysis of general sites of NP in vivo deposition and an assessment of how accumulation in these organs or tissues can be harnessed to develop therapies for site-related pathologies. We therefore give a comprehensive overview of existing nanotherapeutic targeting strategies for specific cell types within three of the usual suspects, i.e. the liver, kidney and the vascular system. We discuss the physiological surroundings and relevant pathologies of described tissues as well as the implications for NP-mediated drug delivery. Additionally, successful cell-selective NP concepts using active targeting strategies are assessed. By bringing together both (patho)physiological aspects and concepts for cell-selective NP formulations, we hope to show a novel opportunity for the development of more promising nanotherapeutic devices.

Treatment of Hepatic Fibrosis in Mice Based on Targeted Plasmonic Hyperthermia

Liver fibrosis is a major health problem with multiple associated complications, which, to date, has no effective treatment. Hepatic stellate cells are the main responsible cells for fibrosis formation; upon their activation, excess accumulation of extracellular matrix and collagen deposits occurs. The mitogen platelet-derived growth factor (PDGF) and its receptor β (PDGFRβ) play a major role in hepatic stellate cells activation and are, therefore, promising targets for antifibrotic therapies. Gold nanorods hold great potential for diseased liver treatments, since their passive hepatic accumulation enhances active targeting strategies, hence increasing therapeutic efficiency. In addition, gold nanorods have photothermal properties that, combined with specific cell delivery, can be exploited to induce localized near-infrared light-mediated thermal ablation. Here, we demonstrate that gold nanorods coated with anti-PDGFRβ specifically target activated hepatic stellate cells in vivo. Additionally, gold nanorods-PDGFRβ-mediated photothermal therapy decreases fibrosis, hepatic inflammation, and hepatocyte injury in the experimental model of CCl₄-induced liver fibrosis in mice.

Nanoparticles Dual Targeting Both Myeloma Cells and Cancer-Associated Fibroblasts Simultaneously to Improve Multiple Myeloma Treatment

Cancer-associated fibroblasts (CAFs) and myeloma cells could mutually drive myeloma progression, indicating that drug delivery to kill both CAFs and myeloma cells simultaneously could achieve better therapeutic benefits than to kill each cell type alone. Here, we designed a dual-targeting drug delivery system by conjugating paclitaxel (PTX)-loaded poly(ethylene glycol)-poly(lactic acid) nanoparticles (NPs) with a cyclic peptide (CNPs-PTX) with a special affinity with platelet-derived growth factor/platelet-derived growth factor receptor (PDGFR-β) overexpressed on both CAFs and myeloma cells. Cellular uptake experiments revealed that the cyclic peptide modification on CNPs could significantly enhance CNPs uptake by both CAFs and myeloma cells compared with unmodified NPs. Cytotoxicity tests showed that CNPs-PTX was more toxic to both CAFs and myeloma cells compared with its counterpart PTX-loaded conventional NPs (NPs-PTX). In vivo imaging and biodistribution experiments showed that CNPs could abundantly accumulate in tumors and were highly co-localized with CAFs and myeloma cells. The in vivo anti-tumor experiments confirmed that the anti-myeloma efficacy of CNPs-PTX was significantly stronger than that of NPs-PTX and free drugs. In summary, it is the first time that a dual-targeting strategy was utilized in the field of myeloma treatment through targeting both CAFs and myeloma cells simultaneously, which harbors a high potential of clinical translation for myeloma treatment.

The Epithelial-to-Mesenchymal Transition as a Possible Therapeutic Target in Fibrotic Disorders

Fibrosis is a chronic and progressive disorder characterized by excessive deposition of extracellular matrix, which leads to scarring and loss of function of the affected organ or tissue. Indeed, the fibrotic process affects a variety of organs and tissues, with specific molecular background. However, two common hallmarks are shared: the crucial role of the transforming growth factor-beta (TGF-β) and the involvement of the inflammation process, that is essential for initiating the fibrotic degeneration. TGF-β in particular but also other cytokines regulate the most common molecular mechanism at the basis of fibrosis, the Epithelial-to-Mesenchymal Transition (EMT). EMT has been extensively studied, but not yet fully explored as a possible therapeutic target for fibrosis. A deeper understanding of the crosstalk between fibrosis and EMT may represent an opportunity for the development of a broadly effective anti-fibrotic therapy. Here we report the evidences of the relationship between EMT and multi-organ fibrosis, and the possible therapeutic approaches that may be developed by exploiting this relationship.

Targeting Cancer Associated Fibroblasts in Liver Fibrosis and Liver Cancer Using Nanocarriers

Cancer associated fibroblasts (CAF) and the extracellular matrix (ECM) produced by them have been recognized as key players in cancer biology and emerged as important targets for cancer treatment and drug discovery. Apart from their presence in stroma rich tumors, such as biliary, pancreatic and subtypes of hepatocellular cancer (HCC), both CAF and certain ECM components are also present in cancers without an overt intra-tumoral desmoplastic reaction. They support cancer development, growth, metastasis and resistance to chemo- or checkpoint inhibitor therapy by a multitude of mechanisms, including angiogenesis, ECM remodeling and active immunosuppression by secretion of tumor promoting and immune suppressive cytokines, chemokines and growth factors. CAF resemble activated hepatic stellate cells (HSC)/myofibroblasts, expressing α-smooth muscle actin and especially fibroblast activation protein (FAP). Apart from FAP, CAF also upregulate other functional cell surface proteins like platelet-derived growth factor receptor β (PDGFRβ) or the insulin-like growth factor receptor II (IGFRII). Notably, if formulated with adequate size and zeta potential, injected nanoparticles home preferentially to the liver. Several nanoparticular formulations were tested successfully to deliver dugs to activated HSC/myofibroblasts. Thus, surface modified nanocarriers with a cyclic peptide binding to the PDGFRβ or with mannose-6-phosphate binding to the IGFRII, effectively directed drug delivery to activated HSC/CAF in vivo. Even unguided nanohydrogel particles and lipoplexes loaded with siRNA demonstrated a high in vivo uptake and functional siRNA delivery in activated HSC, indicating that liver CAF/HSC are also addressed specifically by well-devised nanocarriers with optimized physicochemical properties. Therefore, CAF have become an attractive target for the development of stroma-based cancer therapies, especially in the liver.

Impact of Reverse Micelle Loaded Lipid Nanocapsules on the Delivery of Gallic Acid into Activated Hepatic Stellate Cells: A Promising Therapeutic Approach for Hepatic Fibrosis

PURPOSE

Gallic acid (GA) is a polyphenolic compound with proven efficacy against hepatic fibrosis in experimental animals. However, it suffers from poor bioavailability and rapid clearance that hinders its clinical investigation. Accordingly, we designed and optimized reverse micelle-loaded lipid nanocapsules (RMLNC) using Box-Behnken design that can deliver GA directly into activated-hepatic stellate cells (aHSCs) aiming to suppress hepatic fibrosis progression.

METHODS

GA-RMLNC was prepared using soft energy, solvent free phase inversion temperature method. Effects of formulation variables on particle size, zeta potential, entrapment efficiency (EE%) and GA release were studied. In-vivo biodistribution of GA-RMLNC in rats and in-vitro activities on aHSCs were also explored.

RESULTS

Nano-sized GA-RMLNCs (30.35 ± 2.34 nm) were formulated with high GA-EE% (63.95 ± 2.98% w/w) and physical stability (9 months). The formulated system showed burst GA release in the first 2 h followed by sustained release profile. In-vivo biodistribution imaging revealed that RMLNC-loaded with rhodamine-B accumulated mainly in rats' livers. Relative to GA; GA-RMLNC displayed higher anti-proliferative activities, effective internalization into aHSCs, marked down-regulation in pro-fibrogenic biomarkers' expressions and elevated HSCs' apoptosis.

CONCLUSIONS

These findings emphasize the promising application of RMLNC as a delivery system in hepatic fibrosis treatment, where successful delivery of GA into aHSCs was ensured via increased cellular uptake and antifibrotic activities.

PDGFA gene rs9690350 polymorphism increases biliary atresia risk in Chinese children

Biliary atresia (BA) is a genetic and severe fibro-inflammatory obliterative cholangiopathy of neonates. Platelet-derived growth factor subunit A (PDGFA), as one of participants in liver fibrosis, the overexpression of PDGFA through DNA hypomethylation may lead to the development of BA, but the pathogenesis is still unclear. We conducted a large case-control cohort to investigate the association of genetic variants in PDGFA with BA susceptibility in the Southern Chinese population (506 cases and 1473 controls). We observed that the G allele of rs9690350(G>C) in PDGFA was significantly associated with an increased risk of BA (OR = 1.24, 95% CI = 1.04-1.49, P=0.02). Additionally, the rs9690350 G allele increased the risk of non-cystic biliary atresia (OR = 1.26, 95% CI = 1.04-1.52, P=0.02) and was a genetic biomarker of severe manifestations after surgery. These findings indicate that the rs9690350 G allele is a PDGFA polymorphism associated with the risk of BA that may confer increased disease susceptibility.

TRAIL therapy and prospective developments for cancer treatment

Tumor Necrosis Factor (TNF) Related Apoptosis-Inducing Ligand (TRAIL), an immune cytokine of TNF-family, has received much attention in late 1990s as a potential cancer therapeutics due to its selective ability to induce apoptosis in cancer cells. TRAIL binds to cell surface death receptors, TRAIL-R1 (DR4) and TRAIL-R2 (DR5) and facilitates formation of death-inducing signaling complex (DISC), eventually activating the p53-independent apoptotic cascade. This unique mechanism makes the TRAIL a potential anticancer therapeutic especially for p53-mutated tumors. However, recombinant human TRAIL protein (rhTRAIL) and TRAIL-R agonist monoclonal antibodies (mAb) failed to exert robust anticancer activities due to inherent and/or acquired resistance, poor pharmacokinetics and weak potencies for apoptosis induction. To get TRAIL back on track as a cancer therapeutic, multiple strategies including protein modification, combinatorial approach and TRAIL gene therapy are being extensively explored. These strategies aim to enhance the half-life and bioavailability of TRAIL and synergize with TRAIL action ultimately sensitizing the resistant and non-responsive cells. We summarize emerging strategies for enhanced TRAIL therapy in this review and cover a wide range of recent technologies that will provide impetus to rejuvenate the TRAIL therapeutics in the clinical realm.

Efficient drug and gene delivery to liver fibrosis: rationale, recent advances, and perspectives

Liver fibrosis results from chronic damages together with an accumulation of extracellular matrix, and no specific medical therapy is approved for that until now. Due to liver metabolic capacity for drugs, the fragility of drugs, and the presence of insurmountable physiological obstacles in the way of targeting, the development of efficient drug delivery systems for anti-fibrotics seems vital. We have explored articles with a different perspective on liver fibrosis over the two decades, then collected and summarized the information by providing corresponding in vitro and in vivo cases. We have discussed the mechanism of hepatic fibrogenesis with different ways of fibrosis induction in animals. Furthermore, the critical chemical and herbal anti-fibrotics, biological molecules such as micro-RNAs, siRNAs, and growth factors, which can affect cell division and differentiation, are mentioned. Likewise, drug and gene delivery and therapeutic systems on in vitro and in vivo models are summarized in the data tables. This review article enlightens recent advances in emerging drugs and nanocarriers and represents perspectives on targeting strategies employed in liver fibrosis treatment.

Lipid nanoparticles for nucleic acid delivery: Current perspectives

Nucleic Acid (NA) based therapeutics are poised to disrupt modern medicine and augment traditional pharmaceutics in a meaningful way. However, a key challenge to advancing NA therapies into the clinical setting and on to the market is the safe and effective delivery to the target tissue and cell. Lipid Nanoparticles (LNP) have been extensively investigated and are currently the most advanced vector for the delivery of NA drugs, as evidenced by the approval of Onpattro for treatment of Amyloidosis in the US and EU in 2018. This article provides a comprehensive review of the state-of-the-art for LNP technology. We discuss key advances in the design and development of LNP, leading to a broad range of therapeutic applications. Finally, the current status of this technology in clinical trials and its future prospects are discussed.

Hyperbranched lipoid-based lipid nanoparticles for bidirectional regulation of collagen accumulation in liver fibrosis

Liver fibrosis leads to over one million deaths annually worldwide. Hepatic stellate cells (HSCs) have been identified as the main executors of liver fibrosis. Unfortunately, no drug has yet been approved for clinical use against liver fibrosis, largely because the tested drugs have been unable to access HSCs and efficiently remove the collagen accumulation involved in fibrogenesis. Here, we designed an efficient HSC-targeting lipid delivery system that carried dual siRNAs intended to both inhibit collagen synthesis and promote collagen degradation, with the goal of realizing enhanced anti-liver fibrosis by bidirectional regulation of collagen accumulation. The delivery system was constructed by using amphiphilic cationic hyperbranched lipoids (C₁₅-PA) for siRNA complexation and helper lipoids (cholesterol-polyethylene glycol-vitamin A, Chol-PEG-VA) for HSCs targeting. The generated vitamin A-decorated and hyperbranched lipoid-based lipid nanoparticles (VLNPs) showed excellent gene-binding ability and transfection efficiency, and enhanced the delivery of siRNAs to HSCs. Fibrotic mice treated with dual siRNA-loaded VLNPs showed a great reduction in the collagen accumulation seen in this model; the enhanced effect of bidirectional regulation reduced the collagen accumulation level in treated mice to almost that seen in normal mice. There was no notable sign of toxicity or tissue inflammation in mice exposed to repeated intravenous administration of the dual siRNA-loaded VLNPs. In conclusion, our results indicate that biocompatible VLNPs designed to exploit precise targeting and an effective bidirectional regulation strategy hold promise for treating liver fibrosis.

Nanoscale dynamic chemical, biological sensor material designs for control monitoring and early detection of advanced diseases

Early detection and easy continuous monitoring of emerging or re-emerging infectious, contagious or other diseases are of particular interest for controlling healthcare advances and developing effective medical treatments to reduce the high global cost burden of diseases in the backdrop of lack of awareness regarding advancing diseases. Under an ever-increasing demand for biosensor design reliability for early stage recognition of infectious agents or contagious diseases and potential proteins, nanoscale manufacturing designs had developed effective nanodynamic sensing assays and compact wearable devices. Dynamic developments of biosensor technology are also vital to detect and monitor advanced diseases, such as human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), diabetes, cancers, liver diseases, cardiovascular diseases (CVDs), tuberculosis, and central nervous system (CNS) disorders. In particular, nanoscale biosensor designs have indispensable contribution to improvement of health concerns by early detection of disease, monitoring ecological and therapeutic agents, and maintaining high safety level in food and cosmetics. This review reports an overview of biosensor designs and their feasibility for early investigation, detection, and quantitative determination of many advanced diseases. Biosensor strategies are highlighted to demonstrate the influence of nanocompact and lightweight designs on accurate analyses and inexpensive sensing assays. To date, the effective and foremost developments in various nanodynamic designs associated with simple analytical facilities and procedures remain challenging. Given the wide evolution of biosensor market requirements and the growing demand in the creation of early stage and real-time monitoring assays, precise output signals, and easy-to-wear and self-regulating analyses of diseases, innovations in biosensor designs based on novel fabrication of nanostructured platforms with active surface functionalities would produce ​remarkable biosensor devices. This review offers evidence for researchers and inventors to focus on biosensor challenge and improve fabrication of nanobiosensors to revolutionize consumer and healthcare markets.

Lipid-based nanoparticle technologies for liver targeting

Liver diseases such as hepatitis, cirrhosis, and hepatocellular carcinoma are global health problems accounting for approximately 800 million cases and over 2 million deaths per year worldwide. Major drawbacks of standard pharmacological therapies are the inability to deliver a sufficient concentration of a therapeutic agent to the diseased liver, and nonspecific drug delivery leading to undesirable systemic side effects. Additionally, depending on the specific liver disease, drug delivery to a subset of liver cells is required. In recent years, lipid nanoparticles have been developed to passively and actively target drugs to the liver. The success of this approach has been highlighted by the FDA-approval of the first liver-targeting lipid nanoparticle, ONPATTRO, in 2018 and many other promising candidate technologies are expected to follow. This review summarizes recent developments of various lipid-based liver-targeting technologies, namely solid-lipid nanoparticles, liposomes, niosomes and micelles, and discusses the challenges and future perspectives in this field.

An integrin-based nanoparticle that targets activated hepatic stellate cells and alleviates liver fibrosis

Activation of hepatic stellate cells (HSCs) contributes to the development of liver fibrosis. Because of a relatively small population of HSCs in the liver and the lack of specific membrane targeting proteins, HSC-targeted therapy remains a major clinical challenge. Here we first showed that a hallmark of activated HSC (aHSC) is their increased expression of integrin αvβ3. Thus we established sterically stable liposomes that contain the cyclic peptides (cRGDyK) with a high affinity to αvβ3 to achieve aHSC-specific delivery. Our results showed that the cRGDyK-guided liposomes were preferentially internalized by activated HSCs in vitro and in vivo, and the internalization was abolished by excess free cRGDyK or knockdown of αvβ3. In contrast, quiescent HSCs, hepatocytes, Kupffer cells, sinusoidal endothelial cells, or biliary cells showed minimal uptake of the cRGDyK-guided liposomes. When loaded with the hedgehog inhibitor vismodegib, the cRGDyK-guided liposomes inhibited hedgehog pathway signaling specifically in activated HSCs. Moreover, treatment of mice with vismodegib-loaded cRGDyK-liposomes markedly inhibited the fibrogenic phenotype in bile duct ligation- or thioacetamide-treated mice. We conclude that the cRGDyK-guided liposomes can specifically target the activated HSCs, but not quiescent HSCs. This nanoparticle system showed great promise to deliver therapeutic agents to aHSC to treat liver fibrosis.

Targeted Drug Delivery to Hepatic Stellate Cells for the Treatment of Liver Fibrosis

Liver fibrosis is caused by excessive accumulation of extracellular matrix during chronic liver injuries. Although clinical evidence suggests that liver fibrosis can be reversed, there is no standard therapy for liver fibrosis. Moreover, there is a lack of diagnostic tools to detect early-stage liver fibrosis. Activation of hepatic stellate cells (HSCs) is the key step during liver fibrogenesis, and its mechanism has been extensively studied by various cell culture and animal models. Targeted delivery of therapeutic agents to activated HSCs is therefore critical for the successful treatment of liver fibrosis. A number of protein markers have been found to be overexpressed in activated HSCs, and their ligands have been used to specifically deliver various antifibrotic agents. In this review, we summarize these HSC-specific protein markers and their ligands for targeted delivery of antifibrotic agents.

Synergistic MicroRNA Therapy in Liver Fibrotic Rat Using MRI-Visible Nanocarrier Targeting Hepatic Stellate Cells

Liver fibrosis, as one of the leading causes of liver-related morbidity and mortality, has no Food and Drug Administration (FDA)-approved antifibrotic therapy yet. Although microRNA-29b (miRNA-29b) and microRNA-122 (miRNA-122) have great potential in treating liver fibrosis via regulating profibrotic genes in hepatic stellate cells (HSCs), it is still a challenge to achieve a HSC-targeted and meanwhile noninvasively trackable delivery of miRNAs in vivo. Herein, a pH-sensitive and vitamin A (VA)-conjugated copolymer VA-polyethylene glycol-polyethyleneimine-poly(N-(N',N'-diisopropylaminoethyl)-co-benzylamino) aspartamide (T-PBP) is synthesized and assembled into superparamagnetic iron oxide (SPIO)-decorated cationic micelle for miRNA delivery. The T-PBP micelle efficiently transports the miRNA-29b and miRNA-122 to HSC in a magnetic resonance imaging-visible manner, resulting in a synergistic antifibrosis effect via downregulating the expression of fibrosis-related genes, including collagen type I alpha 1, α-smooth muscle actin, and tissue inhibitor of metalloproteinase 1. Consequently, the HSC-targeted combination therapy with miRNA-29b and miRNA-122 demonstrates a prominent antifibrotic efficacy in terms of improving liver function and relieving hepatic fibrosis.

Chemically modified liposomes carrying TRAIL target activated hepatic stellate cells and ameliorate hepatic fibrosis in vitro and in vivo

At present, no satisfactory anti-liver fibrosis drugs have been used clinically due to the poor targeting ability and short half-life period. This study aimed to explore the effects of a new TRAIL (TNF-related apoptosis-inducing ligand) preparation that can target aHSCs (activated hepatic stellate cells) on liver fibrosis and explain the possible underlying mechanism. Using our self-made drug carrier pPB-SSL that specifically targets aHSCs, recombinant human TRAIL (rhTRAIL) protein was embedded in (named as pPB-SSL-TRAIL) and applied to treat liver fibrotic mice as well as 3T3 fibroblast cells and aHSCs. Through in vitro and in vivo experiments, we found that, compared with the groups treated with TRAIL (free rhTRAIL) and SSL-TRAIL (rhTRAIL capsulated within unmodified liposome), the group treated with pPB-SSL-TRAIL nanoparticles showed significantly lower cell viability and higher cell apoptosis in vitro. The targeting delivering system pPB-SSL also significantly enhanced the anti-fibrotic effect, apoptosis induction and long circulation of rhTRAIL. After the treatment with pPB-SSL-TRAIL, apoptosis of aHSCs was notably increased and hepatic fibrosis in mice was remarkably alleviated. In vitro, pPB-SSL-TRAIL nanoparticles were mainly transported and located on membrane or into cytoplasm, but the particles were distributed mainly in mouse fibrotic liver and most on the cell membrane of aHSCs. In conclusion, rhTRAIL carried by pPB-SSL delivering system has prolonged circulation in blood, be able to target aHSCs specifically, and alleviate fibrosis both in vitro and in vivo. It presents promising prospect in the therapy of liver fibrosis, and it is worthwhile for us to develop it for clinical use.

P311, Friend, or Foe of Tissue Fibrosis?

P311 was first identified by the group of Studler et al. (1993) in the developing brain. In healthy, but mainly in pathological tissues, P311 is implicated in cell migration and proliferation. Furthermore, evidence in models of tissue fibrosis points to the colocalization with and the stimulation of transforming growth factor β1 by P311. This review provides a comprehensive overview on P311 and discusses its potential as an anti-fibrotic target.

Enhanced efficacy of curcumin with phosphatidylserine-decorated nanoparticles in the treatment of hepatic fibrosis

Hepatic macrophages have been considered as a therapeutic target for liver fibrosis treatment, and phosphatidylserine (PS)-containing nanoparticles are commonly used to mimic apoptotic cells that can specifically regulate macrophage functions, resulting in anti-inflammatory effects. This study was designed to test the efficacy of PS-modified nanostructured lipid carriers (mNLCs) containing curcumin (Cur) (Cur-mNLCs) in the treatment of liver fibrosis in a rat model. Carbon tetrachloride-induced liver fibrosis in rats was used as an experimental model, and the severity of the disease was examined by both biochemical and histological methods. Here, we showed that mNLCs were spherical nanoparticles with decreased negative zeta potentials due to PS decoration, and significantly increased both mean residence time and area under the curve of Cur. In the rats with liver fibrosis, PS-modification of NLCs enhanced the nanoparticles targeting to the diseased liver, which was evidenced by their highest accumulation in the liver. As compared to all the controls, Cur-mNLCs were significantly more effective at reducing the liver damage and fibrosis, which were indicated by in Cur-mNLCs-treated rats the least increase in liver enzymes and pro-inflammatory cytokines in the circulation, along with the least increase in collagen fibers and alpha smooth muscle actin and the most increased hepatocyte growth factors (HGF) and matrix metalloprotease (MMP) two in the livers. In conclusion, PS-modified NLCs nanoparticles prolonged the retention time of Cur, and enhanced its bioavailability and delivery efficiency to the livers, resulting in reduced liver fibrosis and up-regulating hepatic expression of HGF and MMP-2.

pPB Peptide-Mediated siRNA-Loaded Stable Nucleic Acid Lipid Nanoparticles on Targeting Therapy of Hepatic Fibrosis

Hepatic fibrosis is a necessary process in the development of liver diseases such as hepatic cirrhosis and its complications, which has become a serious threat to human health. Currently, antifibrotic drug treatment is ineffective, and one reason should be the lack of liver targeting ability. In this report, polypeptide pPB-modified stable nucleic acid lipid nanoparticles (pPB-SNALPs) were prepared to selectively deliver siRNAs against heat shock protein 47 to the liver for targeted therapy of hepatic fibrosis. First, siRNA sequences with high silencing efficiency were screened based on siRNA transfection efficacy. Then, pPB-SNALPs were prepared, which showed a narrow size distribution with a diameter in the range of 110-130 nm and a neutral z-potential of 0 mV. As evidenced by the in vitro and in vivo targeting study, compared with unmodified SNALP, pPB-SNALP showed increased uptake by LX-2 cells and primary hepatic stellate cells (HSC) of mice in vitro and showed increased liver distribution and HSC uptake in vivo. In addition, pPB-SNALP also exhibited an enhanced inhibitory effect on TAA-induced hepatic fibrosis mice with high gp46 mRNA expression in vivo. In summary, our results demonstrated that pPB-SNALP is an effective liver-targeted delivery system. This study could lay a good foundation for the targeted gene therapy of hepatic fibrosis.

Drug targeting to myofibroblasts: Implications for fibrosis and cancer

Myofibroblasts are the key players in extracellular matrix remodeling, a core phenomenon in numerous devastating fibrotic diseases. Not only in organ fibrosis, but also the pivotal role of myofibroblasts in tumor progression, invasion and metastasis has recently been highlighted. Myofibroblast targeting has gained tremendous attention in order to inhibit the progression of incurable fibrotic diseases, or to limit the myofibroblast-induced tumor progression and metastasis. In this review, we outline the origin of myofibroblasts, their general characteristics and functions during fibrosis progression in three major organs: liver, kidneys and lungs as well as in cancer. We will then discuss the state-of-the art drug targeting technologies to myofibroblasts in context of the above-mentioned organs and tumor microenvironment. The overall objective of this review is therefore to advance our understanding in drug targeting to myofibroblasts, and concurrently identify opportunities and challenges for designing new strategies to develop novel diagnostics and therapeutics against fibrosis and cancer.

1-Methyl-L-tryptophan promotes the apoptosis of hepatic stellate cells arrested by interferon-γ by increasing the expression of IFN-γRβ, IRF-1 and FAS

Liver fibrosis, a precursor to cirrhosis, is the result of the deposition of extracellular matrix (ECM) proteins and is mediated primarily by activated hepatic stellate cells (HSCs). In this study, we investigated the anti-fibrotic effects of interferon (IFN)-γ in activated HSCs in vitro and whether cell viability would be decreased by the inhibition of indoleamine 2,3-dioxygemase (IDO), which is responsible for cell cycle arrest. Following treatment with IFN-γ, cell signaling pathways and DNA content were analyzed to assess the inactivation of HSCs or the decrease in HSC proliferation. The IDO inhibitor, 1-methyl-L-tryptophan (1-MT), was used to determine whether IDO plays a key role in the regulation of activated HSCs, as IFN-γ increases the expression of IDO. IFN-γ significantly inhibited the growth of HSCs and downregulated the expression of α-smooth muscle actin (α-SMA) in the HSCs. IDO expression was markedly increased by IFN-γ through signal transducer and activator of transcription 1 (STAT1) activation and resulted in the depletion of tryptophan. This depletion induced G1 cell cycle arrest. When the cells were released from IFN-γ-mediated G1 cell cycle arrest by treatment with 1-MT, the apoptosis of the HSCs was markedly increased through the induction of IFN-γRβ, interferon regulatory factor (IRF-1) and FAS. Our results thus suggest that the inhibition of IDO enhances the suppression of activated HSCs, and therefore co-treatment with IFN-γ and 1-MT may be applied to ameliorate liver fibrosis.

Highly Selective Targeting of Hepatic Stellate Cells for Liver Fibrosis Treatment Using a d-Enantiomeric Peptide Ligand of Fn14 Identified by Mirror-Image mRNA Display

Although liver fibrosis is a major public health issue, there is still no effective drug therapy in the clinic. Fibroblast growth factor-inducible 14 (Fn14), a membrane receptor highly specifically expressed in activated hepatic stellate cells (HSCs), is the key driver of liver fibrosis, and thus, it has a great potential as a novel target for the development of effective treatment. Here, we identified a d-enantiomeric peptide ligand of Fn14 through mirror-image mRNA display. This included the chemical synthesis of a d-enantiomer of the target protein (extracellular domain of Fn14), identification of an l-peptide ligand of d-Fn14 using a constructed mRNA peptide library, and identification of a d-enantiomer of the l-peptide, which is a ligand of the natural Fn14 for reasons of symmetry. The obtained d-peptide ligand showed strong binding to Fn14 while maintaining high proteolytic resistance. As a targeting moiety, this d-peptide successfully mediated high selectivity of activated HSCs for liposomal vehicles compared to that of other major cell types in the liver and significantly enhanced the accumulation of liposomes in the liver fibrosis region of a carbon tetrachloride-induced mouse model. Moreover, in combination with curcumin as an encapsulated load, a liposomal formulation conjugated with this d-peptide showed powerful inhibition of the proliferation of activated HSCs and reduced the liver fibrosis to a significant extent in vivo. This Fn14-targeting strategy may represent a promising approach to targeted drug delivery for liver fibrosis treatment. Meanwhile, the mirror-image mRNA display can provide a new arsenal for the development of d-peptide-based therapeutics against a variety of human diseases.

A Proof-of-Concept for Epigenetic Therapy of Tissue Fibrosis: Inhibition of Liver Fibrosis Progression by 3-Deazaneplanocin A

The progression of fibrosis in chronic liver disease is dependent upon hepatic stellate cells (HSCs) transdifferentiating to a myofibroblast-like phenotype. This pivotal process is controlled by enzymes that regulate histone methylation and chromatin structure, which may be targets for developing anti-fibrotics. There is limited pre-clinical experimental support for the potential to therapeutically manipulate epigenetic regulators in fibrosis. In order to learn if epigenetic treatment can halt the progression of pre-established liver fibrosis, we treated mice with the histone methyltransferase inhibitor 3-deazaneplanocin A (DZNep) in a naked form or by selectively targeting HSC-derived myofibroblasts via an antibody-liposome-DZNep targeting vehicle. We discovered that DZNep treatment inhibited multiple histone methylation modifications, indicative of a broader specificity than previously reported. This broad epigenetic repression was associated with the suppression of fibrosis progression as assessed both histologically and biochemically. The anti-fibrotic effect of DZNep was reproduced when the drug was selectively targeted to HSC-derived myofibroblasts. Therefore, the in vivo modulation of HSC histone methylation is sufficient to halt progression of fibrosis in the context of continuous liver damage. This discovery and our novel HSC-targeting vehicle, which avoids the unwanted effects of epigenetic drugs on parenchymal liver cells, represents an important proof-of-concept for epigenetic treatment of liver fibrosis.

Clinical Advancements in the Targeted Therapies against Liver Fibrosis

Hepatic fibrosis, characterized by excessive accumulation of extracellular matrix (ECM) proteins leading to liver dysfunction, is a growing cause of mortality worldwide. Hepatocellular damage owing to liver injury leads to the release of profibrotic factors from infiltrating inflammatory cells that results in the activation of hepatic stellate cells (HSCs). Upon activation, HSCs undergo characteristic morphological and functional changes and are transformed into proliferative and contractile ECM-producing myofibroblasts. Over recent years, a number of therapeutic strategies have been developed to inhibit hepatocyte apoptosis, inflammatory responses, and HSCs proliferation and activation. Preclinical studies have yielded numerous targets for the development of antifibrotic therapies, some of which have entered clinical trials and showed improved therapeutic efficacy and desirable safety profiles. Furthermore, advancements have been made in the development of noninvasive markers and techniques for the accurate disease assessment and therapy responses. Here, we focus on the clinical developments attained in the field of targeted antifibrotics for the treatment of liver fibrosis, for example, small molecule drugs, antibodies, and targeted drug conjugate. We further briefly highlight different noninvasive diagnostic technologies and will provide an overview about different therapeutic targets, clinical trials, endpoints, and translational efforts that have been made to halt or reverse the progression of liver fibrosis.

Glucocorticoids Have Opposing Effects on Liver Fibrosis in Hepatic Stellate and Immune Cells

Liver fibrosis is a reversible wound-healing process that is protective in the short term, but prolonged fibrotic responses lead to excessive accumulation of extracellular matrix components that suppresses hepatocyte regeneration, resulting in permanent liver damage. Upon liver damage, nonparenchymal cells including immune cells and hepatic stellate cells (HSCs) have crucial roles in the progression and regression of liver fibrosis. Here, we report differential roles of the glucocorticoid receptor (GR), acting in immune cells and HSCs, in liver fibrosis. In the carbon tetrachloride hepatotoxin-induced fibrosis model, both steroidal and nonsteroidal GR ligands suppressed expression of fibrotic genes and decreased extracellular matrix deposition but also inhibited immune cell infiltration and exacerbated liver injury. These counteracting effects of GR ligands were dissociated in mice with conditional GR knockout in immune cells (GR(LysM)) or HSC (GR(hGFAP)): the impacts of dexamethasone on immune cell infiltration and liver injury were totally blunted in GR(LysM) mice, whereas the suppression of fibrotic gene expression was diminished in GR(hGFAP) mice. The effect of GR activation in HSC was further confirmed in the LX-2 HSC cell line, in which antifibrotic effects were mediated by GR ligand inhibition of Sma and mad-related protein 3 (SMAD3) expression. We conclude that GR has differential roles in immune cells and HSCs to modulate liver injury and liver fibrosis. Specific activation of HSC-GR without alteration of GR activity in immune cells provides a potential therapeutic approach to treatment of hepatic fibrosis.

Pharmacological Intervention in Hepatic Stellate Cell Activation and Hepatic Fibrosis

The activation and transdifferentiation of hepatic stellate cells (HSCs) into contractile, matrix-producing myofibroblasts (MFBs) are central events in hepatic fibrogenesis. These processes are driven by autocrine- and paracrine-acting soluble factors (i.e., cytokines and chemokines). Proof-of-concept studies of the last decades have shown that both the deactivation and removal of hepatic MFBs as well as antagonizing profibrogenic factors are in principle suitable to attenuate ongoing hepatic fibrosis. Although several drugs show potent antifibrotic activities in experimental models of hepatic fibrosis, there is presently no effective pharmaceutical intervention specifically approved for the treatment of liver fibrosis. Pharmaceutical interventions are generally hampered by insufficient supply of drugs to the diseased liver tissue and/or by adverse effects as a result of affecting non-target cells. Therefore, targeted delivery systems that bind specifically to receptors solely expressed on activated HSCs or transdifferentiated MFBs and delivery systems that can improve drug distribution to the liver in general are urgently needed. In this review, we summarize current strategies for targeted delivery of drugs to the liver and in particular to pro-fibrogenic liver cells. The applicability and efficacy of sequestering molecules, selective protein carriers, lipid-based drug vehicles, viral vectors, transcriptional targeting approaches, therapeutic liver- and HSC-specific nanoparticles, and miRNA-based strategies are discussed. Some of these delivery systems that had already been successfully tested in experimental animal models of ongoing hepatic fibrogenesis are expected to translate into clinically useful therapeutics specifically targeting HSCs.

Nanoparticle-liver interactions: Cellular uptake and hepatobiliary elimination

30-99% of administered nanoparticles will accumulate and sequester in the liver after administration into the body. This results in reduced delivery to the targeted diseased tissue and potentially leads to increased toxicity at the hepatic cellular level. This review article focuses on the inter- and intra-cellular interaction between nanoparticles and hepatic cells, the elimination mechanism of nanoparticles through the hepatobiliary system, and current strategies to manipulate liver sequestration. The ability to solve the "nanoparticle-liver" interaction is critical to the clinical translation of nanotechnology for diagnosing and treating cancer, diabetes, cardiovascular disorders, and other diseases.

Targeting activated hepatic stellate cells (aHSCs) for liver fibrosis imaging

Following injurious stimuli, quiescent hepatic stellate cells (qHSCs) transdifferentiate into activated HSCs (aHSCs). aHSCs play pivotal roles in the onset and progression of liver fibrosis. Therefore, molecular imaging of aHSCs in liver fibrosis will facilitate early diagnosis, prognosis prediction, and instruction and evaluation of aHSC-targeted treatment. To date, several receptors, such as integrin αvβ3, mannose 6-phosphate/insulin-like growth factor II receptor (M6P/IGF-IIR), collagen type VI receptor (CVIR), platelet-derived growth factor receptor-β (PDGFR-β), vimentin, and desmin, have been identified as biomarkers of aHSCs. Corresponding ligands to these receptors have also been developed. This review will discuss strategies for developing aHSC-targeted imaging in liver fibrosis.

Targeted Therapies in Liver Fibrosis: Combining the Best Parts of Platelet-Derived Growth Factor BB and Interferon Gamma

Cytokines, growth factors, and other locally produced mediators play key roles in the regulation of disease progression. During liver fibrosis, these mediators orchestrate the balance between pro- and antifibrotic activities as exerted by the hepatic cells. Two important players in this respect are the profibrotic mediator platelet-derived growth factor BB (PDGF-BB) and the antifibrotic cytokine interferon gamma (IFNγ). PDGF-BB, produced by many resident and infiltrating cells, causes extensive proliferation, migration, and contraction of hepatic stellate cells (HSCs) and myofibroblasts. These cells are the extracellular matrix-producing hepatic cells and they highly express the PDGFβ receptor. On the other hand, IFNγ is produced by natural killer cells in fibrotic livers and is endowed with proinflammatory, antiviral, and antifibrotic activities. This cytokine attracted much attention as a possible therapeutic compound in fibrosis. However, clinical trials yielded disappointing results because of low efficacy and adverse effects, most likely related to the dual role of IFNγ in fibrosis. In our studies, we targeted the antifibrotic IFNγ to the liver myofibroblasts. For that, we altered the cell binding properties of IFNγ, by delivery of the IFNγ-nuclear localization sequence to the highly expressed PDGFβ receptor using a PDGFβ receptor recognizing peptide, thereby creating a construct referred to as “Fibroferon” (i.e., fibroblast-targeted interferon γ). In recent years, we demonstrated that HSC-specific delivery of IFNγ increased its antifibrotic potency and improved its general safety profile in vivo, making Fibroferon highly suitable for the treatment of (fibrotic) diseases associated with elevated PDGFβ receptor expression. The present review summarizes the knowledge on these two key mediators, PDGF-BB and IFNγ, and outlines how we used this knowledge to create the cell-specific antifibrotic compound Fibroferon containing parts of both of these mediators.

Diagnostic imaging and therapeutic application of nanoparticles targeting the liver

Liver diseases, particularly viral hepatitis, cirrhosis and hepatocellular carcinoma, are common in clinical practice with high morbidity and mortality worldwide. Many substances for diagnostic imaging and therapy of liver diseases may have either severe adverse effects or insufficient effectiveness in vivo because of their nonspecific uptake. Therefore, by targeting the delivery of drugs into the liver or specific liver cells, drug efficiency may be largely improved. This review summarizes the up-to-date research progress focusing on nanoparticles targeting the liver for both diagnostic and therapeutic purposes. Targeting strategies, mechanisms of enhanced effects, and clinical applications of nanoparticles are discussed specifically. We believe that new targeting nanotechnology such as nanoprobes for multi-modality imaging and multifunctional nanoparticles would facilitate significant advancements in this active research area in the near future.

Therapeutic targeting of liver inflammation and fibrosis by nanomedicine

Nanomedicine constitutes the emerging field of medical applications for nanotechnology such as nanomaterial-based drug delivery systems. This technology may hold exceptional potential for novel therapeutic approaches to liver diseases. The specific and unspecific targeting of macrophages, hepatic stellate cells (HSC), hepatocytes, and liver sinusoidal endothelial cells (LSEC) using nanomedicine has been developed and tested in preclinical settings. These four major cell types in the liver are crucially involved in the complex sequence of events that occurs during the initiation and maintenance of liver inflammation and fibrosis. Targeting different cell types can be based on their capacity to ingest surrounding material, endocytosis, and specificity for a single cell type can be achieved by targeting characteristic structures such as receptors, sugar moieties or peptide sequences. Macrophages and especially the liver-resident Kupffer cells are in the focus of nanomedicine due to their highly efficient and unspecific uptake of most nanomaterials as well as due to their critical pathogenic functions during inflammation and fibrogenesis. The mannose receptor enables targeting macrophages in liver disease, but macrophages can also become activated by certain nanomaterials, such as peptide-modified gold nanorods (AuNRs) that render them proinflammatory. HSC, the main collagen-producing cells during fibrosis, are currently targeted using nanoconstructs that recognize the mannose 6-phosphate and insulin-like growth factor II, peroxisome proliferator activated receptor 1, platelet-derived growth factor (PDGF) receptor β, or integrins. Targeting of the major liver parenchymal cell, the hepatocyte, has only recently been achieved with high specificity by mimicking apolipoproteins, naturally occurring nanoparticles of the body. LSEC were found to be targeted most efficiently using carboxy-modified micelles and their integrin receptors. This review will summarize important functions of these cell types in healthy and diseased livers and discuss current strategies of cell-specific targeting for liver diseases by nanomedicine.