Institute of Nano Science and Technology (INST), Phase-10, Sector-64, Mohali, Punjab 160062, India.
National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Tajganj, Agra 282001, India.
Int J Pharm. 2019 Mar 10;558:231-241. doi: 10.1016/j.ijpharm.2018.12.076. Epub 2019 Jan 8.
Resistance to anti-Tuberculosis (anti-TB) drugs is primarily due to unique intrinsic resistance mechanisms that mycobacterium possess. The most important determinant of resistance is a peculiar hydrophobic and multi-layered mycobacterial cell-wall structure with mycolic-acid and wax-D, which restricts permeability of both hydrophobic and hydrophilic drugs into bacteria. In this study, it was supposed that Host Defense peptides (HDP) which are known to permeabilize bacterial membranes may, therefore, help anti-TB antibiotics to target internal sites in bacteria. To test this hypothesis, we examined the effect of suboptimal concentration (10 µg/ml) of selected microencapsulated-HDP (Ub2-MS, K4-MS, and Aurein1.2-MS) with a standard anti-TB drug (Isoniazid, INH, 3 µg/ml). We also examined the combined effect of different concentrations of HDP-MS with a suboptimal concentration of anti-TB drug (INH, 1.5 µg/ml) which showed additive efficacy. A number of cationic HDP were encapsulated in inhalable microspheres (HDP-MS) and characterized for physicochemical and aerodynamic properties. These peptides were further evaluated for molecular mass by MALDI-TOF and random coil in its secondary structure as determined by circular dichroism. The anti-mycobacterial kinetics of selected HDP-MS (Ub2-MS, K4-MS, and Aurein1.2-MS) was evaluated against virulent Mycobacterium tuberculosis (Mtb), both alone and in conjunction with anti-TB drug (INH). HDP-MS exhibited up to ∼3.02 and ∼3.41-log decrease in CFU as compared to blank-MS (drug free) and untreated control group in 96 h. The combination of HDP-MS with a suboptimal concentration of INH (1.5 µg/ml) showed superior antibiotic activity against Mtb. Our findings show that the enhanced efficacy is due to augmentation of membrane permeation by HDP which expedited the entry of TB drug into apparently the impermeant mycobacterial membrane which further enhances the effective efficacy of the drug. This phenomenon can reduce the need for high dosages and represents a novel paradigm for potential clinical applications.
抗结核药物（anti-TB）耐药性主要归因于分枝杆菌所具有的独特固有耐药机制。耐药性的最重要决定因素是一种特殊的疏水性和多层分枝杆菌细胞壁结构，其中含有分枝菌酸和蜡-D，这限制了疏水性和亲水性药物进入细菌的通透性。在这项研究中，人们假设已知可透化细菌膜的宿主防御肽（HDP）可能有助于抗结核抗生素靶向细菌内部靶位。为了验证这一假设，我们研究了亚最佳浓度（10μg/ml）的选定微囊化-HDP（Ub2-MS、K4-MS 和 Aurein1.2-MS）与标准抗结核药物（异烟肼，INH，3μg/ml）联合使用的效果。我们还研究了不同浓度的 HDP-MS 与亚最佳浓度的抗结核药物（INH，1.5μg/ml）联合使用的协同效果，结果显示协同效果。许多阳离子 HDP 被包裹在可吸入微球（HDP-MS）中，并对其物理化学和空气动力学特性进行了表征。这些肽的分子量进一步通过 MALDI-TOF 进行了评估，其二级结构以随机卷曲的形式通过圆二色性进行了确定。选定的 HDP-MS（Ub2-MS、K4-MS 和 Aurein1.2-MS）对有活力的结核分枝杆菌（Mtb）的抗分枝杆菌动力学进行了评估，单独使用和与抗结核药物（INH）联合使用。与空白-MS（无药物）和未经处理的对照组相比，HDP-MS 在 96 小时内使 CFU 减少了约 3.02 和 3.41 个对数级。HDP-MS 与亚最佳浓度的 INH（1.5μg/ml）联合使用时，对 Mtb 表现出更好的抗生素活性。我们的研究结果表明，这种增强的疗效是由于 HDP 增加了膜通透性，从而加速了 TB 药物进入显然不可渗透的分枝杆菌膜，进一步增强了药物的有效疗效。这种现象可以减少对高剂量的需求，并为潜在的临床应用提供了一种新的范例。
