Renal targeted delivery of triptolide by conjugation to the fragment peptide of human serum albumin

Targeted delivery of type I TGF-β receptor-mimicking peptide to fibrotic kidney for improving kidney fibrosis therapy via enhancing the inhibition of TGF-β1/Smad and p38 MAPK pathways

Renal fibrosis is a representative pathological feature of various chronic kidney diseases, and efficient treatment is needed. Interstitial myofibroblasts are a key driver of kidney fibrosis, which is dependent on the binding of TGF-β1 to type I TGF-β receptor (TβRI) and TGF-β1-related signaling pathways. Therefore, attenuating TGF-β1 activity by competing with TGF-β1 in myofibroblasts is an ideal strategy for treating kidney fibrosis. Recently, a novel TβRI-mimicking peptide RIPΔ demonstrated a high affinity for TGF-β1. Thus, it could be speculated that RIPΔ may be used for anti-fibrosis therapy. Platelet-derived growth factor β receptor (PDGFβR) is highly expressed in fibrotic kidney. In this study, we found that target peptide Z-RIPΔ, which is RIPΔ modified with PDGFβR-specific affibody ZPDGFβR, was specifically and highly taken up by TGF-β1-activated NIH3T3 fibroblasts. Moreover, Z-RIPΔ effectively inhibited the myofibroblast proliferation, migration and fibrosis response in vitro. In vivo and ex vivo experiments showed that Z-RIPΔ specifically targeted fibrotic kidney, improved the damaged renal function, and ameliorated kidney histopathology and renal fibrosis in UUO mice. Mechanistic studies showed that Z-RIPΔ hold the stronger inhibition of the TGF-β1/Smad and TGF-β1/p38 pathways than unmodified RIPΔ in vitro and in vivo. Furthermore, systemic administration of Z-RIPΔ to UUO mice led to minimal toxicity to major organs. Taken together, RIPΔ modified with ZPDGFβR increased its therapeutic efficacy and reduced its systemic toxicity, making it a potential candidate for targeted therapy for kidney fibrosis.

Protein and peptide-based renal targeted drug delivery systems

Renal diseases have become an increasingly concerned public health problem in the world. Kidney-targeted drug delivery has profound transformative potential on increasing renal efficacy and reducing extra-renal toxicity. Protein and peptide-based kidney targeted drug delivery systems have garnered more and more attention due to its controllable synthesis, high biocompatibility and low immunogenicity. At the same time, the targeting methods based on protein/peptide are also abundant, including passive renal targeting based on macromolecular protein and active targeting mediated by renal targeting peptide. Here, we review the application and the drug loading strategy of different proteins or peptides in targeted drug delivery, including the ferritin family, albumin, low molecular weight protein (LMWP), different peptide sequence and antibodies. In addition, we summarized the factors influencing passive and active targeting in drug delivery system, the main receptors related to active targeting in different kidney diseases, and a variety of nano forms of proteins based on the controllable synthesis of proteins.

Application of nanotechnology in the treatment of glomerulonephritis: current status and future perspectives

Glomerulonephritis (GN) is the most common cause of end-stage renal failure worldwide; in most cases, it cannot be cured and can only delay the progression of the disease. At present, the main treatment methods include symptomatic therapy, immunosuppressive therapy, and renal replacement therapy. However, effective treatment of GN is hindered by issues such as steroid resistance, serious side effects, low bioavailability, and lack of precise targeting. With the widespread application of nanoparticles in medical treatment, novel methods have emerged for the treatment of kidney diseases. Targeted transportation of drugs, nucleic acids, and other substances to kidney tissues and even kidney cells through nanodrug delivery systems can reduce the systemic effects and adverse reactions of drugs and improve treatment effectiveness. The high specificity of nanoparticles enables them to bind to ion channels and block or enhance channel gating, thus improving inflammation. This review briefly introduces the characteristics of GN, describes the treatment status of GN, systematically summarizes the research achievements of nanoparticles in the treatment of primary GN, diabetic nephropathy and lupus nephritis, analyzes recent therapeutic developments, and outlines promising research directions, such as gas signaling molecule nanodrug delivery systems and ultrasmall nanoparticles. The current application of nanoparticles in GN is summarized to provide a reference for better treatment of GN in the future.

Nanomedicines for the management of diabetic nephropathy: present progress and prospects

Diabetic nephropathy (DN) is a serious microvascular consequence of diabetes mellitus (DM), posing an encumbrance to public health worldwide. Control over the onset and progress of DN depend heavily on early detection and effective treatment. DN is a major contributor to end-stage renal disease, and a complete cure is yet to be achieved with currently available options. Though some therapeutic molecules have exhibited promise in treating DN complications, their poor solubility profile, low bioavailability, poor permeation, high therapeutic dose and associated toxicity, and low patient compliance apprehend their clinical usefulness. Recent research has indicated nano-systems as potential theranostic platforms displaying futuristic promise in the diagnosis and treatment of DN. Early and accurate diagnosis, site-specific delivery and retention by virtue of ligand conjugation, and improved pharmacokinetic profile are amongst the major advantages of nano-platforms, defining their superiority. Thus, the emergence of nanoparticles has offered fresh approaches to the possible diagnostic and therapeutic strategies regarding DN. The present review corroborates an updated overview of different types of nanocarriers regarding potential approaches for the diagnosis and therapy of DN.

Improving the circulation time and renal therapeutic potency of extracellular vesicles using an endogenous ligand binding strategy

Kidney diseases are a serious health issue worldwide, and novel therapeutics are urgently needed. Extracellular vesicles (EVs) have emerged as potent drug delivery systems (DDSs), but their therapeutic potential is limited by short circulation times and insufficient renal retention. Here, we report that endogenous ligand (albumin, ALB) binding is an efficient modification strategy to improve the therapeutic potency of EV-based DDSs for kidney diseases. Surface albumin-binding peptide (ABP)-displayed EVs (ABP-EVs) were produced by transfecting parent cells with the ABP-Lamp2b fusion plasmid. Compared with unmodified EVs (NC-EVs), ABP-EVs showed increased binding to ALB in vitro and elevated circulation time and multiple organ retention in vivo after systemic (iv) injection. Moreover, ABP-EVs had higher renal retention than NC-EVs in mice with acute kidney injury through a complex mechanism involving microvascular injury and megalin-mediated endocytosis. As a result, delivery of small molecule drugs (e.g., curcumin) or proteins (e.g., hepatocyte growth factor) by ABP-EVs had superior therapeutic (e.g., anti-apoptotic, antioxidant, anti-inflammatory) effects in vitro and in vivo. This study highlights that ABP-EVs are versatile DDSs for kidney diseases and provides insights into the new strategies of engineering EVs for drug delivery.

Renal Proximal Tubular Cells: A New Site for Targeted Delivery Therapy of Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a major complication of diabetes mellitus (DM) and the leading cause of end-stage kidney disease (ESKD) worldwide. A significant number of drugs have been clinically investigated for the treatment of DKD. However, a large proportion of patients still develop end-stage kidney disease unstoppably. As a result, new effective therapies are urgently needed to slow down the progression of DKD. Recently, there is increasing evidence that targeted drug delivery strategies such as large molecule carriers, small molecule prodrugs, and nanoparticles can improve drug efficacy and reduce adverse side effects. There is no doubt that targeted drug delivery strategies have epoch-making significance and great application prospects for the treatment of DKD. In addition, the proximal tubule plays a very critical role in the progression of DKD. Consequently, the purpose of this paper is to summarize the current understanding of proximal tubule cell-targeted therapy, screen for optimal targeting strategies, and find new therapeutic approaches for the treatment of DKD.

Detoxification strategies of triptolide based on drug combinations and targeted delivery methods

Tripterygium wilfordii Hook f. has a long history of use in Chinese medicine. Triptolide (TP), as its main pharmacological component, has been widely explored in various diseases, including systemic lupus erythematosus, rheumatoid arthritis and cancer. However, due to its poor water solubility, limited therapeutic range and multi-organ toxicity, TP's clinical application has been greatly hampered. To improve its clinical potential, many attenuated drug combinations have been developed based on its toxicity mechanism and targeted delivery systems aimed at its water-solubility and structure. This review, conducted a systematic review of TP detoxification strategies including drug combination detoxification strategies from metabolic and toxic mechanisms, as well as drug delivery detoxification strategies from the prodrug strategy and nanotechnology. Many detoxification strategies have demonstrated promising potential in vitro and in vivo due to previous extensive studies on TP. Therefore, summarizing and discussing TP detoxification strategies for clinical problems can serve as a reference for developing novel TP detoxification strategies, and provide opportunities for future clinical applications.

The Efficacy of Triptolide in Preventing Diabetic Kidney Diseases: A Systematic Review and Meta-Analysis

Ethnopharmacological Relevance: Triptolide (TP), the primary biologically active ingredient of Tripterygium wilfordii Hook F (TWHF), possesses the potential to solve the shortcomings of TWHF in treating diabetic kidney disease (DKD) in the clinic. Aim of the Study: We conducted a meta-analysis to evaluate the efficacy of TP in treating DKD and offer solid evidence for further clinical applications of TP. Materials and Methods: Eight databases (CNKI, VIP, CBM, WanFang, PubMed, Web of Science, EMBASE, and Cochrane library) were electronically searched for eligible studies until October 17, 2020. We selected animal experimental studies using TP versus renin-angiotensin system inhibitors or nonfunctional liquids to treat DKD by following the inclusion and exclusion criteria. Two researchers independently extracted data from the included studies and assessed the risk of bias with the Systematic Review Centre for Laboratory Animal Experimentation Risk of Bias tool. Fixed-effects meta-analyses, subgroup analyses, and meta-regression were conducted using RevMan 5.3 software. Inplasy registration number: INPLASY2020100042. Results: Twenty-six studies were included. Meta-analysis showed that TP significantly reduced albuminuria (14 studies; standardized mean difference SMD: -1.44 [-1.65, -1.23], I2 = 87%), urine albumin/urine creatinine ratio (UACR) (8 studies; SMD: -5.03 [-5.74, -4.33], I2 = 84%), total proteinuria (4 studies; SMD: -3.12 [-3.75, -2.49], I2 = 0%), serum creatinine (18 studies; SMD: -0.30 [-0.49, -0.12], I2 = 76%), and blood urea nitrogen (12 studies; SMD: -0.40 [-0.60, -0.20], I2 value = 55%) in DKD animals, compared to the vehicle control. However, on comparing TP to the renin-angiotensin system (RAS) inhibitors in DKD treatment, there was no marked difference in ameliorating albuminuria (3 studies; SMD: -0.35 [-0.72, 0.02], I2 = 41%), serum creatinine (3 studies; SMD: -0.07 [-0.62, 0.48], I2 = 10%), and blood urea nitrogen (2 studies; SMD: -0.35 [-0.97, 0.28], I2 = 0%). Of note, TP exhibited higher capacities in reducing UACR (2 studies; SMD: -0.66 [-1.31, -0.01], I2 = 0%) and total proteinuria (2 studies; SMD: -1.18 [-1.86, -2049], I2 = 0%). Meta-regression implicated that the efficacy of TP in reducing DKD albuminuria was associated with applied dosages. In addition, publication bias has not been detected on attenuating albuminuria between TP and RAS inhibitors after the diagnosis of DKD. Systematic Review Registration: https://clinicaltrials.gov/, identifier INPLASY2020100042.

Therapeutic and delivery strategies of phytoconstituents for renal fibrosis

Chronic kidney disease (CKD) is one of the most common diseases endangering human health and life. By 2030, 14 per 100,000 people may die from CKD. Renal fibrosis (RF) is an important intermediate link and the final pathological change during CKD progression to the terminal stage. Therefore, identifying safe and effective treatment methods for RF has become an important goal. In 2018, the World Health Organization introduced traditional Chinese medicine into its effective global medical program. Various phytoconstituents that affect the RF process have been extracted from different plants. Here, we review the potential therapeutic capabilities of active phytoconstituents in RF treatment and discuss how phytoconstituents can be structurally modified or combined with other ingredients to enhance efficiency and reduce toxicity. We also summarize phytoconstituent delivery strategies to overcome renal barriers and improve bioavailability and targeting.

Novel CD44-targeting and pH/redox-dual-stimuli-responsive core-shell nanoparticles loading triptolide combats breast cancer growth and lung metastasis

Background

The toxicity and inefficient delivery of triptolide (TPL) in tumor therapy have greatly limited the clinical application. Thus, we fabricated a CD44-targeting and tumor microenvironment pH/redox-sensitive nanosystem composed of hyaluronic acid-vitamin E succinate and poly (β-amino esters) (PBAEss) polymers to enhance the TPL-mediated suppression of breast cancer proliferation and lung metastasis.

Results

The generated TPL nanoparticles (NPs) had high drug loading efficiency (94.93% ± 2.1%) and a desirable average size (191 nm). Mediated by the PBAEss core, TPL/NPs displayed a pH/redox-dual-stimuli-responsive drug release profile in vitro. Based on the hyaluronic acid coating, TPL/NPs exhibited selective tumor cellular uptake and high tumor tissue accumulation capacity by targeting CD44. Consequently, TPL/NPs induced higher suppression of cell proliferation, blockage of proapoptotic and cell cycle activities, and strong inhibition of cell migration and invasion than that induced by free TPL in MCF-7 and MDA-MB-231 cells. Importantly, TPL/NPs also showed higher efficacy in shrinking tumor size and blocking lung metastasis with decreased systemic toxicity in a 4T1 breast cancer mouse model at an equivalent or lower TPL dosage compared with that of free TPL. Histological immunofluorescence and immunohistochemical analyses in tumor and lung tissue revealed that TPL/NPs induced a high level of apoptosis and suppressed expression of matrix metalloproteinases, which contributed to inhibiting tumor growth and pulmonary metastasis.

Conclusion

Collectively, our results demonstrate that TPL/NPs, which combine tumor active targeting and pH/redox-responsive drug release with proapoptotic and antimobility effects, represent a promising candidate in halting breast cancer progression and metastasis while minimizing systemic toxicity.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00934-0.

Study of the Active Components and Molecular Mechanism of Tripterygium wilfordii in the Treatment of Diabetic Nephropathy

We aimed to explore the active ingredients and molecular mechanism of Tripterygium wilfordii (TW) in the treatment of diabetic nephropathy (DN) through network pharmacology and molecular biology. First, the active ingredients and potential targets of TW were obtained through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and related literature materials, and Cytoscape 3.7.2 software was used to construct the active ingredient-target network diagram of TW. Second, the target set of DN was obtained through the disease database, and the potential targets of TW in the treatment of DN were screened through a Venn diagram. A protein interaction network diagram (PPI) was constructed with the help of the String platform and Cytoscape 3.7.2. Third, the ClueGO plug-in tool was used to enrich the GO biological process and the KEGG metabolic pathway. Finally, molecular docking experiments and cell pathway analyses were performed. As a result, a total of 52 active ingredients of TW were screened, and 141 predicted targets and 49 target genes related to DN were identified. The biological process of GO is mediated mainly through the regulation of oxygen metabolism, endothelial cell proliferation, acute inflammation, apoptotic signal transduction pathway, fibroblast proliferation, positive regulation of cyclase activity, adipocyte differentiation and other biological processes. KEGG enrichment analysis showed that the main pathways involved were AGE-RAGE, vascular endothelial growth factor, HIF-1, IL-17, relaxin signalling pathway, TNF, Fc epsilon RI, insulin resistance and other signaling pathways. It can be concluded that TW may treat DN by reducing inflammation, reducing antioxidative stress, regulating immunity, improving vascular disease, reducing insulin resistance, delaying renal fibrosis, repairing podocytes, and reducing cell apoptosis, among others, with multicomponent, multitarget and multisystem characteristics.

Nanomedicine in the treatment of diabetic nephropathy

Globally, diabetic nephropathy (DN) is the foremost cause of end-stage renal disease. With the incidence of diabetes increasing day by day, DN's occurrence is expected to surge to pandemic proportions. Current available therapeutic interventions associated with DN emphasize blood pressure, glycemia and lipid control while ignoring DN's progression mechanism at a molecular level. This review sheds light on the molecular insights involved in DN to help understand the initiation and progression pattern. Further, we summarize novel strategies with reported applications in developing a nanomedicine-based platform for DN-targeted drug delivery to improve drug efficacy and safety.

Multiple-Coated PLGA Nanoparticles Loading Triptolide Attenuate Injury of a Cellular Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease, which is associated with extracellular deposition of amyloid-β proteins (Aβ). It has been reported that triptolide (TP), an immunosuppressive and anti-inflammatory agent extracted from a Chinese herb Tripterygium wilfordii, shows potential neuroprotective effects pertinent to AD. However, the clinical use of TP for AD could be hampered due to its high toxicity, instability, poor water solubility, and nonspecific biodistribution after administration. In this paper, we reported a kind of multiple-coated PLGA nanoparticle with the entrapment of TP and surface coated by chitosan hydrochloride, Tween-80, PEG20000, and borneol/mentholum eutectic mixture (MC-PLGA-TP-NP) as a novel nasal brain targeting preparation for the first time. The obtained MC-PLGA-TP-NP was 147.5 ± 20.7 nm with PDI of 0.263 ± 0.075, zeta potential of 14.62 ± 2.47 mV, and the entrapment efficiency and loading efficiency of 93.14% ± 4.75% and 1.17 ± 0.08%, respectively. In comparison of TP, MC-PLGA-TP-NP showed sustained-release profile and better transcellular permeability to Caco-2 cells in vitro. In addition, our data showed that MC-PLGA-TP-NP remarkably reduced the cytotoxicity, attenuated the oxidative stress, and inhibited the increase of the intracellular Ca²⁺ influx in differentiated PC12 cells induced by Aβ_1-42. Therefore, it can be concluded that MC-PLGA-TP-NP is a promising preparation of TP, which exerts a better neuroprotective activity in the AD cellular model.

Triptolide: reflections on two decades of research and prospects for the future

Covering: 2000 to 2020 Triptolide is a bioactive diterpene triepoxide isolated from Tripterygium wilfordii Hook F, a traditional Chinese medicinal plant whose extracts have been used as anti-inflammatory and immunosuppressive remedies for centuries. Although triptolide and its analogs exhibit potent bioactivities against various cancers, and inflammatory and autoimmune diseases, none of them has been approved to be used in the clinic. This review highlights advances in material sourcing, molecular mechanisms, clinical progress and new drug design strategies for triptolide over the past two decades, along with some prospects for the future course of development of triptolide.

Mesoscale nanoparticles encapsulated with emodin for targeting antifibrosis in animal models

The aim of this study is to explore the kidney-targeting capability of mesoscale nanoparticles (MNPs)-emodin (Em-MNPs) and its potential antifibrosis in the animal model. First, MNPs and Em-MNPs were synthesized via nanoprecipitation method, and their diameters were both ∼400 nm with the uniform size. The entrapment efficiency of MNPs was 45.1% when adding emodin at the concentration of 12 mg/mL. Moreover, cytotoxicity assay showed that Em-MNPs presented excellent biocompatibility in rat proximal tubular cells. Cellular uptake assay demonstrated that Em-MNPs had high-efficiency uptake, especially in the cytoplasm. Ex vivo organ fluorescence imaging revealed that Em-MNPs possessed specific kidney-targeting ability with relative long retention time in the kidney (∼24 h). In the renal unilateral ureteral obstruction model, Em-MNPs treatment could significantly alleviate kidney tubule injury and reduce extracellular matrix deposition compared with free MNPs. Herein, Em-MNPs with specific kidney-targeting and preferable antifibrosis effects in animal model may pave an avenue for treating renal diseases.

Self-Assembled Casein Nanoparticles Loading Triptolide for the Enhancement of Oral Bioavailability

Triptolide (TP), a broad-spectrum antitumor drug, has very poor solubility and oral bioavailability, which limits its clinical use. Compared with conventional formulations of TP, a casein (Cas)-based drug delivery system has been reported to have significant advantages for the improvement of solubility and bioavailability of insoluble drugs. In this paper, we report the successful preparation of TP-loaded Cas nanoparticles (TP-Cas) using the self-assembly characteristics of Cas in water and the optimization of the formulation by evaluation of entrapment efficiency (EE) and loading efficiency (LE). Dynamic light scattering, transmission electron microscopy, Fourier-transform infrared spectrometry, X-ray diffractometry (XRD), and differential scanning calorimetry (DSC) was adopted to characterize the TP-Cas. Results showed that the obtained TP-Cas were approximately spherical with a particle size of 128.7 ± 11.5 nm, EE of 72.7 ± 4.7 %, and LE of 8.0% ± 0.5%. Furthermore, in vitro release behavior of TP-Cas in PBS (pH = 7.4) was also evaluated, showing a sustained-release profile. Additionally, an in vivo study in rats displayed that the mean plasma concentration of TP after oral administration of TP-Cas was significantly higher than that treated with TP oral suspension. The C max value for TP-Cas (8.0 ± 4.4 μg/mL) was significantly increased compared with the free TP (0.9 ± 0.3 μg/mL). Accordingly, the area under the curve (AUC0-8) of TP-Cas was 2.8 ± 0.8 mg/L·h, 4.3-fold higher than that of TP suspension (0.6 ± 0.1 mg/L·h). Therefore, it can be concluded that TP-Cas enhanced the absorption and improved oral bioavailability of TP. Taking the good oral safety of Cas into consideration, TP-Cas should be a more promising preparation of TP for clinical application.

Advances in kidney-targeted drug delivery systems

The management and treatment of kidney diseases currently have caused a huge global burden. Although the application of nanotechnology for the therapy of kidney diseases is still at an early stages, it has profound potential of development. More and more nano-based drug delivery systems provide novel solutions for the treatment of kidney diseases. This article summarizes the physiological and anatomical properties of the kidney and the biological and physicochemical characters of drug delivery systems, which affects the ability of drug to target the kidney, and highlights the prospects, opportunities, and challenges of nanotechnology in the therapy of kidney diseases.

Inulin as carriers for renal targeting delivery of ferulic acid

Inulin (IN), as a classic diagnostic for determination of glomerular filtration rate, reached high concentration in kidney. Introducing drug into IN derivatives may be a new method to target kidney for drug delivery. To test the hypothesis, ferulic acid (FeA) was conjugated into IN by ester bond and amide bond (ethylenediamine as spacer), respectively, and the two FeA-IN conjugations, inulin ferulate (IN-FeA) and inulin ethylenediamine ferulate (IN-EDA-FeA) were obtained. NMR spectrum was involved to characterize the conjugations. The FeA in vitro release profiles were tested in mice plasma and renal homogenate. Finally, the biodistribution test was performed to evaluate their renal-targeting ability. Both IN-FeA and IN-EDA-FeA showed a higher release rate of FeA in renal homogenate than in mouse plasma suggesting the conjugates are relatively stable in plasma and more likely FeA release in kidney. The renal area under the curve (AUC) for IN-FeA and IN-EDA-FeA were 539.6 ± 107.9 and 558.5 ± 131.6 μg h/mL, respectively, which were 4.47 and 4.62 times of 120.8 ± 18.1 μg h/mL for free FeA. Meanwhile, significant smaller FeA accumulation in other organs was observed. These data indicated that IN-FeA and IN-EDA-FeA effectively targeted kidney for FeA delivery.

Understanding molecular upsets in diabetic nephropathy to identify novel targets and treatment opportunities

Diabetes and related complications are becoming a global encumbrance. Diabetic nephropathy (DN) is a major cause of end-stage renal disease (ESRD). The available therapeutic modalities related to DN do not treat DN at the molecular level, proposing further amendments in the management of DN based on the pathogenesis of DN. This manuscript discusses the concept and applications of nanomedicine for the treatment of DN that can improve renal targeting, retention and localization. This review also highlights the current issues related to targeting DN, challenges and allied opportunities toward the development of next-generation drugs and treatments for the management of DN.

Antibody Fragment F(ab')2 Targeting Caveolae-Associated Protein PV1 for Selective Kidney Targeting and Retention

Targeted strategies to deliver and retain drugs to kidneys are needed to improve drug accumulation and efficacy in a myriad of kidney diseases. These drug delivery systems show potential for improving the therapeutic windows of drugs acting in the kidney. Biodistribution of antibody-based therapeutics in vivo is governed by several factors including binding affinity, size, and valency. Investigations of how the biophysical and biochemical properties of biologics enable them to overcome biological barriers and reach kidneys are therefore of interest. Although renal accumulation of antibody fragments in cancer diagnostics and treatment has been observed, reports on effective delivery of antibody fragments to the kidneys remain scarce. Previously, we demonstrated that targeting plasmalemma vesicle-associated protein (PV1), a caveolae-associated protein, can promote accumulation of antibodies in both the lungs and the kidneys. Here, by fine-tuning the binding affinity of an antibody toward PV1, we observe that the anti-PV1 antibody with reduced binding affinity lost the capability for kidney targeting while retaining the lung targeting activity, suggesting that binding affinity is a critical factor for kidney targeting of the anti-PV1 antibody. We next use the antibody fragment F(ab')₂ targeting PV1 to assess the dual effects of rapid kidney filtration and PV1 targeting on kidney-selective targeting. Ex vivo fluorescence imaging results demonstrated that after rapidly accumulating in kidneys at 4 h, PV1-targeted F(ab')₂ was continually retained in the kidney at 24 h, whereas the isotype control F(ab')₂ underwent urinary elimination with significantly reduced signaling in the kidney. Confocal imaging studies confirmed the localization of PV1-targeted F(ab')₂ in the kidney. In addition, the monovalent antibody fragment (Fab-C4) lost the capability for kidney homing, indicating that the binding avidity of anti-PV1 F(ab')₂ is important for kidney targeting. Our findings suggest that PV1-targeted F(ab')₂ might be useful as a drug carrier for renal targeting and highlight the importance of affinity optimization for tissue targeting antibodies.

Naturally occurring anti-cancer compounds: shining from Chinese herbal medicine

Numerous natural products originated from Chinese herbal medicine exhibit anti-cancer activities, including anti-proliferative, pro-apoptotic, anti-metastatic, anti-angiogenic effects, as well as regulate autophagy, reverse multidrug resistance, balance immunity, and enhance chemotherapy in vitro and in vivo. To provide new insights into the critical path ahead, we systemically reviewed the most recent advances (reported since 2011) on the key compounds with anti-cancer effects derived from Chinese herbal medicine (curcumin, epigallocatechin gallate, berberine, artemisinin, ginsenoside Rg3, ursolic acid, silibinin, emodin, triptolide, cucurbitacin B, tanshinone I, oridonin, shikonin, gambogic acid, artesunate, wogonin, β-elemene, and cepharanthine) in scientific databases (PubMed, Web of Science, Medline, Scopus, and Clinical Trials). With a broader perspective, we focused on their recently discovered and/or investigated pharmacological effects, novel mechanism of action, relevant clinical studies, and their innovative applications in combined therapy and immunomodulation. In addition, the present review has extended to describe other promising compounds including dihydroartemisinin, ginsenoside Rh2, compound K, cucurbitacins D, E, I, tanshinone IIA and cryptotanshinone in view of their potentials in cancer therapy. Up to now, the evidence about the immunomodulatory effects and clinical trials of natural anti-cancer compounds from Chinese herbal medicine is very limited, and further research is needed to monitor their immunoregulatory effects and explore their mechanisms of action as modulators of immune checkpoints.

Preclinical Pharmacokinetics of Triptolide: A Potential Antitumor Drug

Background:

Triptolide, a bioactive component in Tripterygium wilfordii extracts, possess strong antiproliferative activity on all 60-National Cancer Institute (NCI) cancer cell lines. However, the widespread use of triptolide in the clinical practice is greatly limited for its multi-organ toxicity and narrow therapeutic window. All the toxic characteristics of triptolide are associated with the pharmacokinetics especially its distribution and accumulation in the target organ.

Methods:

The literature review was done using PubMed search, SciFinder and Google Scholar databases with specific keywords such as triptolide, pharmacokinetics, drug-drug interaction, transporters, metabolism, modification to collect the related full-length articles and abstracts from 2000 to 2018.

Results:

Oral triptolide is rapidly and highly absorbed. Grapefruit juice affects oral absorption, increasing the area under the concentration-time curve (AUC) by 153 % and the maximum concentration (Cmax) by 141 %. The AUC and the Cmax are not dose proportional. Triptolide distributes into the liver, heart, spleen, lung and kidney. Biotransformation of triptolide in rats includes hydroxylation, sulfate, glucuronide, N-acetylcysteine (NAC) and Glutathione (GSH) conjugation and combinations of these pathways. Less than 4 % of triptolide was recovered from the feces, bile and urine within 24 h. After repeating dosage, triptolide was eliminated quickly without accumulation in vivo. As a substrate of P-glycoprotein (P-gp) and CYP3A4, triptolide could have clinically significant pharmacokinetic interactions with those proteins substrates/inhibitors.

Conclusion:

The findings of this review confirm the importance of pharmacokinetic character for understanding the pharmacology and toxicology of triptolide.

Kidney-targeted triptolide-encapsulated mesoscale nanoparticles for high-efficiency treatment of kidney injury

Insolubility and toxicity of TP restrict clinical applications in renal diseases. Here, TP-encapsulated mesoscale nanoparticles offer a new therapeutic strategy for renal diseases due to good biocompability, kidney targeting and slow release.

Targeting renal fibrosis: Mechanisms and drug delivery systems

Renal fibrosis is the common outcome of many chronic kidney diseases (CKD) independent of the underlying etiology. Despite a host of promising experimental data, currently available strategies only ameliorate or delay the progression of CKD but do not reverse fibrosis. One of the major impediments of translating novel antifibrotic strategies from bench to bedside is due to the intricacies of the drug delivery process. In this review, we briefly describe mechanisms of renal fibrosis and methods of drug transfer into the kidney. Various tools used in gene therapy to administer nucleic acids in vivo are discussed. Furthermore, we review the modes of action of protein- or peptide-based drugs with target-specific antibodies and cytokines incorporated in hydrogels. Additionally, we assess an intriguing new method to deliver drugs specifically to tubular epithelial cells via conjugation with ligands binding to the megalin receptor. Finally, plant-derived compounds with antifibrotic properties are also summarized.

A Mechanistic Overview of Triptolide and Celastrol, Natural Products from Tripterygium wilfordii Hook F

Triptolide and celastrol are predominantly active natural products isolated from the medicinal plant Tripterygium wilfordii Hook F. These compounds exhibit similar pharmacological activities, including anti-cancer, anti-inflammation, anti-obesity, and anti-diabetic activities. Triptolide and celastrol also provide neuroprotection and prevent cardiovascular and metabolic diseases. However, toxicity restricts the further development of triptolide and celastrol. In this review, we comprehensively review therapeutic targets and mechanisms of action, and translational study of triptolide and celastrol. We systemically discuss the structure-activity-relationship of triptolide, celastrol, and their derivatives. Furthermore, we propose the use of structural derivatives, targeted therapy, and combination treatment as possible solutions to reduce toxicity and increase therapeutic window of these potent natural products from T. wilfordii Hook F.

The Effect of Triptolide in Rheumatoid Arthritis: From Basic Research towards Clinical Translation

Triptolide (TP), a major extract of the herb Tripterygium wilfordii Hook F (TWHF), has been shown to exert potent pharmacological effects, especially an immunosuppressive effect in the treatment of rheumatoid arthritis (RA). However, its multiorgan toxicity prevents it from being widely used in clinical practice. Recently, several attempts are being performed to reduce TP toxicity. In this review, recent progress in the use of TP for RA, including its pharmacological effects and toxicity, is summarized. Meanwhile, strategies relying on chemical structural modifications, innovative delivery systems, and drug combinations to alleviate the disadvantages of TP are also reviewed. Furthermore, we also discuss the challenges and perspectives in their clinical translation.

Efficacy and safety of Tripterygium wilfordii Hook F for CKD in Mainland China: A systematic review and meta-analysis

Tripterygium wilfordii Hook F (TwHF) is a promising Chinese traditional medicine used to significantly reduce proteinuria and improve renal function. However, its efficacy and safety in treatment of chronic kidney disease need to be further explored in order to promote its application in clinics. This review compared the efficacy and safety of TwHF with the placebo, conventional Western medicine and other immunosuppressive medicine in a range of kidney disorders. One hundred three randomized controlled trials were included. TwHF therapy decreased 24-hr proteinuria by 0.59 g/day (95% confidence interval [CI; -0.68, -0.50]), serum creatinine level by 1.93 μmol/L (95% CI [-3.69, -0.17]), and blood urea nitrogen level by 0.24 mmol/L (95% CI [-0.41, -0.07]); increased the total effective rate by 27% (95% CI [1.24, 1.30]); and decreased the incidence of adverse reactions by 19% (95% CI [0.68, 0.96]) overall. Meta regression results showed that the duration of therapy and mean age of participants were the major sources of high heterogeneity. Sensitivity analysis demonstrated that our statistic results were relatively stable and credible. The present findings suggested that TwHF possibly has nephroprotective effects by decreasing proteinuria, serum creatinine level, and blood urea nitrogen level and no more adverse reactions compared with control group in most kidney disorders. However, these findings still need to be further confirmed by high-quality trials.

Renal-targeted delivery of triptolide by entrapment in pegylated TRX-20-modified liposomes

Previously, 3,5-dipentadecyloxybenzamidine hydrochloride (TRX-20)-modified liposomes were reported to specifically target mesangial cells (MCs) in glomeruli. To further gain a better understanding of the characteristics and potential application for glomerular diseases of TRX-20-modified liposomes, we synthesized TRX-20 and prepared TRX-20-modified liposomes (TRX-LPs) with different molar ratios - 6% (6%-TRX-LP), 11% (11%-TRX-LP), and 14% (14%-TRX-LP) - of TRX-20 to total lipid in the present study. All TRX-LPs exhibited concentration-dependent toxicity against the MCs at a lipid concentration ranging from 0.01 to 1.0 mg/mL with IC50 values of 3.45, 1.13, and 0.55 mg/mL, respectively. Comparison of the cell viability of TRX-LPs indicated that high levels of TRX-20 caused severe cell mortality, with 11%-TRX-LP showing the higher cytoplasmic accumulation in the MCs. Triptolide (TP) as a model drug was first loaded into 11%-TRX-LP and the liposomes were further modified with PEG5000 (PEG-TRX-TP-LP) in an attempt to prolong their circulation in blood and enhance TP-mediated immune suppression. Due to specific binding to MCs, PEG-TRX-TP-LP undoubtedly showed better anti-inflammatory action in vitro, evidenced by the inhibition of release of nitric oxide (NO) and tumor necrosis factor-α from lipopolysaccharide-stimulated MCs, compared with free TP at the same dose. In vivo, the PEG-TRX-TP-LP effectively attenuated the symptoms of membranous nephropathic (MN) rats and improved biochemical markers including proteinuria, serum cholesterol, and albumin. Therefore, it can be concluded that the TRX-modified liposome is an effective platform to target the delivery of TP to glomeruli for the treatment of MN.

Hemocompatibility evaluation for peptide fragments of human serum albumin cleaved by cyanogens bromide

We have previously demonstrated that peptide fragments of human serum albumin can be developed into potential renal targeting drug carriers. However, the interactions of these peptide fragments with red blood cells and plasma components are not evaluated well and there is yet no report on the evaluation of the hemocompatibility of peptide fragments. In this study, three kinds of peptide fragments were prepared and identified by amino acid analysis, and the blood compatibility of the peptide fragments was investigated by measuring blood coagulation, platelet and complement activation and hemolysis activity. Results indicated that all the peptide fragments prepared were highly hemocompatible without causing any clot formation, red blood cell aggregation or immune response. In addition, data from the cytotoxicity assay using HeLa cells and Madin-Darby canine kidney cells suggested that these peptide fragments do not induce toxicity towards either cell lines at concentrations up to 5 mg/ml. Therefore, it can be concluded that peptide fragments exhibit good hemocompatibility with no unwanted effect on the viability of renal cells, preliminarily demonstrating that it is safe to use peptide fragments as renal targeting drug carriers.