Calcium Phosphate-Based Nanoformulation Selectively Abolishes Phenytoin Resistance in Epileptic Neurons for Ceasing Seizures

Phenytoin (PHT) is a first-line antiepileptic drug in clinics, which could decrease neuronal bioelectric activity by blocking the voltage-operated sodium channels. However, the intrinsically low blood–brain-barrier (BBB)-crossing capability of PHT and upregulated expression level of the efflux transporter p-glycoprotein (P-gp) coded by the gene Abcb1 in epileptic neurons limit its efficacy in vivo. Herein, a nanointegrated strategy to overcome PHT resistance mechanisms for enhanced antiepileptic efficacy is reported. Specifically, PHT is first incorporated into calcium phosphate (CaP) nanoparticles through biomineralization, followed by the surface modification of the PEGylated BBB-penetrating TAT peptide. The CaP@PHT-PEG-TAT nanoformulation could effectively cross the BBB to be taken in by epileptic neurons. Afterward, the acidic lysosomal environment would trigger their complete degradation to release Ca²⁺ and PHT into the cytosol. Ca²⁺ ions would inhibit mitochondrial oxidative phosphorylation to reverse cellular hypoxia to block hypoxia-inducible factor-1α (Hif1α)-Abcb1-axis, as well as disrupt adenosine triphosphate generation, leading to simultaneous suppression of the expression and drug efflux capacity of P-gp to enhance PHT retention. This study offers an approach for effective therapeutic intervention against drug-resistant epilepsy.     

Augmented anticancer activity of naringenin-loaded TPGS polymeric nanosuspension for drug resistive MCF-7 human breast cancer cells

Naringenin (NAR) is a naturally occurring plant flavonoid, found predominantly in citrus fruits, possesses a wide range of pharmacological properties. However, despite the therapeutic potential of NAR, its clinical development has been hindered due to low aqueous solubility and inefficient transport across biological membranes resulting in low bioavailability at tumor sites. In our previous studies, nanosuspension of naringenin (NARNS) was prepared using high pressure homogenization method using different polymers. D-α-Tocopheryl polyethylene glycol succinate 1000 (TPGS) was added as a co-stabilizer. All formulation characterization studies were performed. As a continuation of our previous research, current study has further evaluated the ability of the TPGS-coated NARNS, to reverse drug-resistance of P-gp-over expressing MCF-7 human breast adenocarcinoma cell line and animal model. MTT-based colorimetric assay revealed higher cytotoxic efficacy of NARNS than free NAR in MCF-7 cells. NARNS treatment significantly increased intracellular ROS level, mitochondrial membrane potential, caspase-3 activity, lipid peroxidation status (TBARS) and decreased GSH levels when compared to free NAR treatment in MCF-7 cells. It has been also noticed that the presence of apoptotic indices (membrane blebbing, nuclear fragmentation) in NARNS treated cancer cells. Further, NARNS exhibited dose-dependent in vitro antitumor activity with DLA cells. A significant increase in the life span and a decrease in the cancer cell number and tumor weight were noted in the tumor-induced mice after treatment with NARNS.     

药食同源类中药在P-糖蛋白介导的多药耐药中的应用

目前, 肿瘤细胞产生多药耐药(multidrug resistance, MDR)严重制约了化疗疗效, 由多药耐药基因编码的P-糖蛋白(P-glycoprotein, P-gp)的过表达是多药耐药产生的重要原因之一。我国中药资源丰富, “药食同源”历史悠久, 药食两用类中药, 安全性高, 毒副作用小, 可通过多成份, 多靶点、多途径来预防和治疗肿瘤。本文根据P-gp介导MDR机制, 介绍了部分可以抑制P-gp实现逆转MDR的“药食同源”类中药, 为肿瘤的预防和辅助治疗提供新思路。     

基于Caco-2细胞单层与大鼠小肠模型的大豆皂苷Ⅰ和Ⅱ经上皮传递的变化研究

利用Caco-2细胞单层与大鼠小肠模型研究大豆皂苷Ⅰ和Ⅱ的吸收变化与机制。在Caco-2细胞单层中,大豆皂苷Ⅰ和Ⅱ从肠腔侧到基底侧的表观渗透系数（apparent permeability coefficients,Papp）随时间的延长趋向平稳,前120 min近似线性,且随浓度增大,斜率减小,Papp值分别为（1.02×10－6～3.41×10－6）cm/s和（0.9×10－6～3.05×10－6） cm/s;传递的饱和性、双侧Papp比率＞1.5以及线粒体呼吸链抑制剂叠氮化钠的抑制作用表明了两者的主动转运机制。抑制剂维拉帕米没有提高大豆皂苷Ⅰ和Ⅱ的吸收,排除了p-糖蛋白介导的外排;吸收促进剂按照冰片＞脱氧胆酸钠＞卡波姆934P＞聚山梨酯80的强弱提高两者的吸收,壳聚糖则未能加强渗透。跨膜转运也表现出组织差异性：两者在大鼠空肠的Papp是十二指肠和回肠的2 倍多。因此,控制的传递应能提高大豆皂苷Ⅰ和Ⅱ的小肠吸收以便两者实施它们的生理功能。     

P-Glycoprotein and Drug Resistance in Systemic Autoimmune Diseases

Autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are chronic inflammatory disorders of unknown etiology characterized by a wide range of abnormalities of the immune system that may compromise the function of several organs, such as kidney, heart, joints, brain and skin. Corticosteroids (CCS), synthetic and biologic immunosuppressive agents have demonstrated the capacity to improve the course of autoimmune diseases. However, a significant number of patients do not respond or develop resistance to these therapies over time. P-glycoprotein (P-gp) is a transmembrane protein that pumps several drugs out of the cell, including CCS and immunosuppressants; thus, its over-expression or hyper-function has been proposed as a possible mechanism of drug resistance in patients with autoimmune disorders. Recently, different authors have demonstrated that P-gp inhibitors, such as cyclosporine A (CsA) and its analogue Tacrolimus, are able to reduce P-gp expression and or function in SLE, RA and PsA patients. These observations suggest that P-gp antagonists could be adopted to revert drug resistance and improve disease outcome. The complex inter-relationship among drug resistance, P-gp expression and autoimmunity still remains elusive.