Inhibition of the renal apical sodium dependent bile acid transporter prevents cholemic nephropathy in mice with obstructive cholestasis.

BACKGROUND & AIMS: Cholemic nephropathy (CN) is a severe complication of cholestatic liver diseases for which there is no specific treatment. We revisited its pathophysiology with the aim of identifying novel therapeutic strategies. METHODS: Cholestasis was induced by bile duct ligation (BDL) in mice. Bile flux in kidneys and livers was visualized by intravital imaging, supported by MALDI mass spectrometry imaging and liquid chromatography-tandem mass spectrometry. The effect of AS0369, a systemically bioavailable apical sodium-dependent bile acid transporter (ASBT) inhibitor, was evaluated by intravital imaging, RNA-sequencing, histological, blood, and urine analyses. Translational relevance was assessed in kidney biopsies from patients with CN, mice with a humanized bile acid (BA) spectrum, and via analysis of serum BAs and KIM-1 (kidney injury molecule 1) in patients with liver disease and hyperbilirubinemia. RESULTS: Proximal tubular epithelial cells (TECs) reabsorbed and enriched BAs, leading to oxidative stress and death of proximal TECs, casts in distal tubules and collecting ducts, peritubular capillary leakiness, and glomerular cysts. Renal ASBT inhibition by AS0369 blocked BA uptake into TECs and prevented kidney injury up to 6 weeks after BDL. Similar results were obtained in mice with humanized BA composition. In patients with advanced liver disease, serum BAs were the main determinant of KIM-1 levels. ASBT expression in TECs was preserved in biopsies from patients with CN, further highlighting the translational potential of targeting ASBT to treat CN. CONCLUSIONS: BA enrichment in proximal TECs followed by oxidative stress and cell death is a key early event in CN. Inhibiting renal ASBT and consequently BA enrichment in TECs prevents CN and systemically decreases BA concentrations. IMPACT AND IMPLICATIONS: Cholemic nephropathy (CN) is a severe complication of cholestasis and an unmet clinical need. We demonstrate that CN is triggered by the renal accumulation of bile acids (BAs) that are considerably increased in the systemic blood. Specifically, the proximal tubular epithelial cells of the kidney take up BAs via the apical sodium-dependent bile acid transporter (ASBT). We developed a therapeutic compound that blocks ASBT in the kidneys, prevents BA overload in tubular epithelial cells, and almost completely abolished all disease hallmarks in a CN mouse model. Renal ASBT inhibition represents a potential therapeutic strategy for patients with CN.

Dual covalent functionalization of single-walled carbon nanotubes for effective targeted cancer therapy.

Chemotherapy is a mainstay strategy in the management of cancer. Regrettably, current chemotherapeutic agents are cytotoxic not only to cancer cells but also to healthy cells, resulting in dose-limiting serious side effects. Therefore, many researchers are eager to develop new drug delivery systems that may help to decrease the side effects and the target delivery of chemotherapy to cancer cells. One of the epochal drug delivery systems in this field is based on carbon nanotubes technology. The aim of this work is the dual covalent functionalization of single-walled carbon nanotubes (SWCNTs) with doxorubicin (DOX) connected with acid-labile linkage and mannose (Man) as a targeting agent. The characterization of the developed nano-drug by transmission electron microscopy showed good dispersibility of the functionalized SWCNTs with diameters (6-10) nm. Moreover, the percentage of functionalization was determined by thermogravimetric analysis showing 25% of functionalization in the case of SWNCTs-NHN-DOX (7) and 51% for SWCNTs-Man-NHN-DOX (11). The in vitro release profile of Dox from SWNCTs-NHN-DOX (7) showed 45% of the loaded drug was released over 18 h at pH 7.4 and almost complete release at pH 6.4 at 37 °C. However, the in vitro release profile of Dox from SWCNTs-Man-NHN-DOX (11) showed 75% of the loaded drug was released over 5 h at pH 6.4 at 37 °C. The cytotoxic effect of the compounds was studied on liver cancer cells (HepG2) at different concentrations and different pH conditions and was compared with DOX alone. The cytotoxicity of compounds SWCNTs-NHN-DOX (7) and SWCNTs-Man-NHN-DOX (11) was enhanced at pH 6.5, where the cell viability in both test compounds was significantly reduced by almost 50% compared to the cell viability at pH 7.4 for the same test compound Moreover, the pre-incubation of cells with different concentrations of mannose reduced the cytotoxicity of compound (11) by more than 50%, suggesting that the entry of this complex could be at least in part facilitated by mannose receptors, which imparts this complex a kind of selectivity for cancer cells that overexpress this type of receptors.

Combretastatin A4-camptothecin micelles as combination therapy for effective anticancer activity.

Cancer is a major worldwide health problem, for which chemotherapy is a common treatment option. However drug toxicity and the development of resistance to chemotherapy are two main challenges associated with the traditional anticancer drugs. Combined pharmacological therapy based on different mechanisms might be an effective strategy in cancer treatment, and could exhibit a synergistic therapeutic efficacy. Herein, we aim to combine combretastatin A4 (CA4) and camptothecin (Cpt) chemically into a codrug through two hydrophilic linkers utilizing click chemistry to improve their water solubility and anticancer activity. The synthesized amphiphilic structure could self-assemble into a micelle structure as confirmed by atomic force microscopy (AFM) and dynamic light scattering (DLS), which showed a high stability and improved water solubility at pH 7.4, with a low critical micelle concentration (CMC) value of 0.9 mM. Moreover, in vitro hydrolysis was observed upon incubation of the hybrid compound with an esterase enzyme, which suggested a complete disassembly into the starting active drugs. Finally, cytotoxicity studies on HeLa cancer cells showed that the codrug demonstrated an enhanced (five fold) cytotoxicity as compared with the free drugs. In addition the combination index (CI) was <1, which suggests a synergistic activity for the codrug. Moreover, the tested concentrations of the codrug were not significantly cytotoxic to a noncancerous fibroblast cell line. The imaging of HeLa cells treated with FITC-loaded micelles showed a rapid internalization. In conclusion, the codrug of CA4 and Cpt might be a potential novel anticancer drug as it demonstrated a synergistic cytotoxic activity that might spare noncancerous cells.

Covalent functionalization of SWCNT with combretastatin A4 for cancer therapy.

Single walled carbon nanotubes (SWCNT) are currently under intensive investigation by many labs all over the world for being promising candidates for cancer chemotherapy delivery. On the other hand, combretastatin A4 (CA4) is an anticancer drug that induces cell apoptosis by inhibiting tubulin polymerization. However, it has the disadvantage of low water solubility and the non-selective targeting. Therefore, we aim to create nano-drug from the functionalization of SWCNT covalently with CA4 through click reaction in the presence of tetraethylene glycol linker in order to improve its dispersibility. Scanning electron microscopy and transmission electron microscopy showed good dispersibility of the functionalized SWCNT with diameters of 5-15 nm. Moreover, thermogravometric analysis showed that the efficiency of SWCNT functionalization was around 45%. The in vitro release profile of CA4 at physiological conditions showed that approximately 90% of the loaded drug was released over 50 h. After that MTS test was used to determine the suitable concentration range for the in vitro investigation of the SWCNT-CA4. After that the cytotoxic activity of the SWCNT-CA4 was evaluated by flow cytometry using annexin V/propidium iodide (PI) test. In comparison with free CA4, SWCNT-CA4 treatment demonstrated a significant increase in necrotic cells (around 50%) at the expense of the proportion of the apoptotic cells. Moreover, cell cycle PI test demonstrated that free CA4 and SWCNT-CA4 caused G2/M arrest. However with CA4 treatment higher proportion of cells were in the S-phase while with SWCNT-CA4 treatment greater proportion of cells appeared to be in the G1-phase. Taken together, the provided data suggest that the novel SWCNT-CA4 has a significant anticancer activity that might be superior to that of free CA4.

Montelukast, current indications and prospective future applications.

INTRODUCTION: Montelukast is recommended for the treatment of asthma, exercise -induced bronchospasm and allergic rhinitis. Several trials demonstrated potential therapeutic effects in other respiratory conditions, and different animal-model-based studies explored potential pharmacological actions in non-respiratory conditions. AREAS COVERED: Clinical investigations on the pharmacotherapeutic effects of montelukast, in addition to in-vivo studies on animal models of non-respiratory diseases. The data discussed in this review were mainly obtained from clinical randomized trials, real-life studies, and studies based on animal models as approve of concept. As a condition, all of the discussed articles were published in journals cited by Pubmed. Expert commentary: The current clinical data are in favor of montelukast use in the management of chronic asthma as an add-on or alternative therapy to the inhaled corticosteroids. Further clinical trials are required to confirm the effectiveness and feasibility of montelukast for the treatment of conditions other than the current clinical indications.