纳米药物递送系统在结核病治疗中的研究进展

目前,结核病防治形势仍十分严峻。然而,传统抗结核药物治疗方案存在疗程长、药物不良反应多以及患者依从性差等问题,常导致治疗失败,故亟需可以控制结核病的新药或新剂型。装载抗结核药物的纳米药物递送系统可以将抗结核药物主动或被动靶向到被感染的细胞或病灶部位内,杀菌的同时,还具有缓释给药、减少给药频率、减少剂量依赖性不良反应等优势。本文综述了纳米递药系统在结核病治疗方面的应用情况及前景。     

抗结核抗菌肽及其纳米药物递送系统的研究进展

由结核分枝杆菌复合群菌株引起的结核病是世界上最致命的传染病之一，同时由于愈发严重的耐药问题，使得对新型抗结核药物的需求更为迫切。抗菌谱广、耐药性低的抗菌肽在治疗结核病方面展现出巨大的潜力，但天然抗菌肽的低稳定性等局限使其临床应用受到限制。药物递送系统，特别是纳米药物递送载体成为解决该问题的重要途径之一。本文综述了抗结核抗菌肽的特征、作用机制和靶点，及近年来抗结核抗菌肽的生产、修饰和优化、与化疗药物联用等方面的研究现状；针对抗结核抗菌肽治疗面临的问题和抗结核药物纳米药物递送系统的发展，分析和展望了多种纳米材料作为抗结核抗菌肽递送载体的研究与应用，期望对更有效的结核病疗法的研发提供思路和指导。     

口服抗肿瘤靶向药物递送系统克服消化道黏膜屏障研究进展

抗肿瘤药物传统的给药方式主要包括静脉注射与口服,与注射给药相比,口服更具安全性与低成本等优势。但大部分口服抗肿瘤靶向药物水溶性低、胃肠道通透性差等,严重影响药物的利用率。克服消化道黏膜屏障,给口服用药的应用带来了具有较大的挑战。基于纳米技术的口服药物递送系统在抗肿瘤药物递送中具有独特的优势与良好的应用前景。笔者将探讨纳米递送系统应用与口服抗肿瘤靶向药物中克服消化道黏膜屏障的研究进展,对聚合物胶束、脂质体、无机纳米颗粒等纳米体载体在抗肿瘤药物口服递药系统的应用进行了详细的综述。     

纳米转运药物在心血管疾病诊断与治疗中的应用

纳米转运药物为心血管疾病的诊断与治疗提供了一种新型给药方式,可解决药物作用时间短、靶向特异性和靶组织浓度低等问题。纳米转运药物可利用血管通透性增加或通过巨噬细胞吞噬作用被动靶向转运至心肌组织,也可通过结合心血管疾病特异性靶点主动靶向转运至心肌组织。该文介绍纳米转运药物在动脉粥样硬化、心肌梗死、心力衰竭等疾病诊断与治疗中的应用。     

中药治疗耐多药结核病的研究进展

耐多药结核病是由耐多药结核分枝杆菌原发感染或抗结核药物用药不当产生继发耐药所致,已成为世界卫生组织2035年终止结核病流行策略的一大阻碍,目前治愈率不理想。因此,迫切需要开发新的抗结核药物或治疗方法。中医药在减轻结核病症状、联合西药治疗耐多药结核病,以及提高患者针对结核分枝杆菌的免疫水平方面已有很多研究。作者对中药抗结核治疗的体外及人体试验研究进展进行综述,以期为临床医生提供更多的有关中西医结合治疗结核病的思路和策略。     

结核分枝杆菌耐对氨基水杨酸相关基因研究进展

对氨基水杨酸(PAS)是20世纪40年代研发的有效抗结核药物之一,其对结核分枝杆菌具有良好的抑制作用,与其他抗结核药物联用有利于增强其他抗结核药物疗效并减少其他抗结核药物耐药性。目前,PAS仍是世界卫生组织(WHO)推荐的有效抗结核药物之一,主要用于治疗耐多药结核病(MDR-TB)。近年来,结核分枝杆菌对PAS耐药现象逐渐增多,但具体耐药机制尚未完全清楚。本文综述了结核分枝杆菌耐PAS相关基因,旨在为结核分枝杆菌对PAS的耐药机制研究提供参考。     

结核分枝杆菌耐环丝氨酸相关基因研究进展

耐多药结核病(MDR-TB)需采用二线抗结核药物治疗,是目前全球范围内结核病防控工作面临的主要挑战。环丝氨酸抗结核分枝杆菌作用较强,世界卫生组织(WHO)于2011年推荐环丝氨酸作为MDR-TB的二线核心口服抗结核药物之一,但近年来结核分枝杆菌对环丝氨酸耐药增多且具体耐药机制尚未完全明确。本文综述了结核分枝杆菌耐环丝氨酸相关基因,旨在为结核分枝杆菌对环丝氨酸的耐药机制研究提供参考。     

结核分枝杆菌耐利奈唑胺相关基因研究进展

耐多药结核病(MDR-TB)及耐利福平结核病(RR-TB)均需采用二线抗结核药物治疗。利奈唑胺属恶唑烷酮类抗生素,是治疗MDR-TB及RR-TB的二线核心抗结核药物之一,其抗结核作用较强,但近年来结核分枝杆菌对利奈唑胺耐药现象增多且具体耐药机制尚未完全明确。本文综述了结核分枝杆菌耐利奈唑胺相关基因,旨在为结核分枝杆菌对利奈唑胺的耐药机制研究提供参考。     

耐药结核病的流行和监测

抗结核病药物在20世纪的相继问世,使结核病的治愈成为可能,也随之出现了结核分枝杆菌的耐药性。由染色体的自发突变而导致对某一种抗结核药耐药的发生频率为10-6到10-8,由于不同药物耐药的突变位点不同,对同时使用的三种抗结核药同时耐药的频率为10-18到10-20。因此,联用三种有效的抗结核药物时,发生抗结核药物耐药的机率极少。从这一点出发,可以认为耐药的发生是结核分枝杆菌基因突变被人为放大的结果。不合理的用药、治疗管理不善、药物供应不足和质量不佳以及间断用药等,刺激结核分枝杆菌发生耐药性,称为获得性耐药(acquireddrugresistan…     

结核分枝杆菌与巨噬细胞的相互作用研究概述

结核分枝杆菌是一种胞内感染菌,巨噬细胞是其寄生场所。巨噬细胞是机体内抗菌免疫的主要效应细胞,通过直接杀伤和/或分泌多种细胞因子,对结核分枝杆菌具有抗原呈递、免疫杀伤等作用;结核分枝杆菌则可通过阻止吞噬体与溶酶体的融合逃避巨噬细胞的免疫监视和攻击。深入研究结核分枝杆菌对巨噬细胞免疫杀伤和免疫逃避机制,对研究宿主抗结核免疫机制以及设计新型结核病疫苗有深远意义。     

Human splenic macrophages as a model for in vitro infection with Mycobacterium tuberculosis

Macrophages play an important role during Mycobacterium tuberculosis (MTB) infection. In humans most of the studies on MTB-macrophage interactions have been performed using circulating monocytes and monocyte-derived macrophages. However, little research has been performed on this interaction using tissue macrophages. Herein, we used human splenic macrophages to characterize particular responses to MTB infection. Based on morphological, biochemical, and immunological markers, splenic adherent cells exhibit characteristics of tissue macrophages. They were able to efficiently phagocytose both live and heat-killed (h-k) MTB H37Rv. Upon infection with live, but not h-k MTB, an increase in secreted TNF-alpha was elicited. Splenic macrophages produced high basal levels of IL-10; however, infection with live or h-k MTB resulted in decrease IL-10 secretion. Both IL-12p40 and IL-12p70 basal levels were also decreased upon infection with live or h-k MTB; however, while the reduction for IL-12p40 levels was observed at earlier time points (4h) for both live and h-k MTB, infection with live MTB, but not h-k MTB, resulted in a time-dependent secretion of IL-12p40 at 24 and 48h after infection. IL-12p70 levels were completely reduced upon infection by either live or h-k MTB. These results support that human splenic macrophages may represent a potential useful model to study MTB-macrophage interactions in vitro.     

Anti-Mycobacterium tuberculosis activities of new fluoroquinolones in combination with other antituberculous drugs

OBJECTIVES: Studies were undertaken in order to assess the anti- Mycobacterium tuberculosis (MTB) activities of newly developed fluoroquinolones in combination with other antituberculous drugs. METHODS: A new C-8-methoxyl fluoroquinolone, gatifloxacin (GFLX), and a new C-8-chloro fluoroquinolone, sitafloxacin (STFX), in combination with other drugs were examined for their activities against extracellular growing MTB organisms and those replicating in RAW264.7 macrophages (RAW-M phis s). RESULTS: STFX but not GFLX potentiated the activities of rifampin and rifalazil against extracellular MTB. Both GFLX and STFX exhibited combined activities against intramacrophage MTB, when used in combination with rifampin, rifalazil, isoniazid, pyrazinamide, ethambutol, streptomycin, or clofazimine. CONCLUSIONS: Although the observed combined effects varied to some extent from case to case depending on drug combinations, the present findings suggest the usefulness of these new fluoroquinolones in multi-drug regimens for tuberculosis patients.     

结核分枝杆菌逃逸免疫杀伤机制的研究进展

结核分枝杆菌(Mycobacterium tuberculosis, MTB)是典型的胞内致病菌,感染机体后主要寄居于宿主巨噬细胞内。巨噬细胞作为机体防御系统的第一道防线,可通过介导和调控自身及其他细胞凋亡而实现其免疫调节、免疫杀伤及清除病原菌的作用。MTB感染机体后可通过多种途径使巨噬细胞不能正常凋亡,借以逃避巨噬细胞的免疫监视及清除,继而在体内衍生繁殖。进一步探讨结核分枝杆菌逃逸宿主细胞的免疫杀伤机制,对宿主细胞抗结核免疫及人们更好地防治结核病具有深远影响。     

Mycobacterium tuberculosis (MTB)-stimulated production of nitric oxide by human alveolar macrophages and relationship of nitric oxide production to growth inhibition of MTB.

SETTING: Although nitric oxide (NO) is a major proximate mediator of microbicidal activity in murine macrophages against intracellular pathogens including mycobacteria, its production by and effector role in human macrophages is not clear. OBJECTIVE: To determine the capacity of Mycobacterium tuberculosis (MTB) to stimulate NO in human monocytes (MN) and alveolar macrophages (AM) and to assess the relationship between NO production and intracellular growth of MTB. DESIGN: NO production (measured as nitrite) by MTB (H37Ra)-infected macrophages and intracellular growth of MTB were measured in cells from 17 healthy subjects. RESULTS: MTB (5:1, MTB:cells) stimulated little to no NO by MN, but induced NO in AM at days 4 and 7 after infection. There was, however, variability in the response by AM to MTB: among seven subjects MTB-induced NO was low (4 +/- 2 microM, mean +/- SE); six subjects were moderate (56 +/- 11); four subjects were high (502 +/- 167). NO synthase inhibitors inhibited the production of NO by AM but did not significantly affect the intracellular growth of MTB, although a trend towards increased intracellular growth was seen on day 4 of culture. Intracellular growth of MTB in AM from low NO producers was significantly higher than that in AM from moderate NO producers, P < or = 0.05. Inducible NO synthase (iNOS) mRNA by RT-PCR was constitutively expressed by both MN and AM, but was further stimulated by MTB in AM > MN; MTB-induced iNOS protein was present in both MN and AM by Western blot analysis. CONCLUSION: Thus, MTB-infected human AM are capable of producing NO and NO production correlates with intracellular growth inhibition of MTB in AM suggesting that NO may serve either directly or indirectly as a mycobactericidal mediator in human tissue macrophages.     

Transglutaminase type 2 plays a key role in the pathogenesis of Mycobacterium tuberculosis infection

Background

Mycobacterium tuberculosis (MTB ), the aetiological agent of tuberculosis (TB ), is capable of interfering with the phagosome maturation pathway, by inhibiting phagosome–lysosome fusion and the autophagic process to ensure survival and replication in macrophages. Thus, it has been proposed that the modulation of autophagy may represent a therapeutic approach to reduce MTB viability by enhancing its clearance.

Objective

The aim of this study was to investigate whether transglutaminase type 2 (TG 2) is involved in the pathogenesis of MTB .

Results

We have shown that either genetic or pharmacological inhibition of TG 2 leads to a marked reduction in MTB replicative capacity. Infection of TG 2 knockout mice demonstrated that TG 2 is required for MTB intracellular survival in macrophages and host tissues. The same inhibitory effect can be reproduced in vitro using Z‐DON , a specific inhibitor of the transamidating activity of TG 2. Massive cell death observed in macrophages that properly express TG 2 is hampered by the absence of the enzyme and can be largely reduced by the treatment of wild‐type macrophages with the TG 2 inhibitor. Our data suggest that reduced MTB replication in cells lacking TG 2 is due to the impairment of LC 3/autophagy homeostasis. Finally, we have shown that treatment of MTB ‐infected murine and human primary macrophages with cystamine, a TG 2 inhibitor already tested in clinical studies, causes a reduction in intracellular colony‐forming units in human macrophages similar to that achieved by the anti‐TB drug capreomycin.

Conclusion

These results suggest that inhibition of TG 2 activity is a potential novel approach for the treatment of TB .

     

Efflux pump as alternate mechanism for drug resistance in Mycobacterium tuberculosis

Tuberculosis (TB) remains an important global public health issue with an approximate prevalence of 10 million people with TB worldwide in 2015. Since antibiotic treatment is one of the foremost tools for TB control, knowledge of Mycobacterium tuberculosis (MTB) drug resistance is an important component for disease control. Although gene mutations in specific loci of the MTB genomes are reported as the primary basis for drug resistance, additional mechanisms conferring resistance to MTB are thought to exist. Efflux is a ubiquitous mechanism responsible for innate and acquired drug resistance in prokaryotic and eukaryotic cells. MTB presents a large number of putative drug efflux pumps compared to its genome size. Bioinformatics-based evidence has shown an association between drug efflux and innate or acquired resistance in MTB. This review describes the recent understanding of drug efflux in MTB.     

CRISPR-Cas系统在结核分枝杆菌研究中的应用进展

成簇的规律间隔短回文重复序列(clustered regularly interspaced short palindromic repeats,CRISPR)和他们相关的蛋白(Cas)组成了一个新的分布于结核分枝杆菌(MTB)的获得性免疫防御系统。此外,CRISPR-Cas系统与MTB的毒力、耐药以及定向基因编辑方面可能存在重要的关系。笔者主要通过对CRISPR-Cas系统在MTB的免疫作用及其相关研究进展进行综述,以期为进一步研究MTB致病性和抗结核治疗提供一种新思路。     

Expression of CCR5 is increased in human monocyte-derived macrophages and alveolar macrophages in the course of in vivo and in vitro Mycobacterium tuberculosis infection.

Human immunodeficiency virus (HIV) replicates more efficiently in Mycobacterium tuberculosis (MTB)-infected macrophages than in uninfected controls. We investigated whether this may be partly explained by changes in expression of CCR5 in the course of mycobacterial infection, as this molecule has been shown to be a coreceptor for HIV entry. Since the lung is the preferential organ of HIV replication in the course of tuberculosis, we preliminarily analyzed beta-chemokine receptor expression in alveolar macrophages from patients with active tuberculosis, using flow cytometry based on an MIP-1alpha ligand-biotin/avidin-FITC detection system. Increased MIP-1alpha receptor (MIP-1alphaR) expression in alveolar macrophages from infected patients was observed whereas no detectable expression could be revealed in uninfected controls. Since MIP-la can also bind CCR1 and CCR4, the presence of CCR5 mRNA was investigated in bronchoalveolar lavage (BAL) cells and detected in alveolar macrophages from tuberculosis patients only. The study was then extended to in vitro MTB-infected macrophages. Monocyte-derived macrophages (MDMs) were left to differentiate for 7 days before MTB H37Rv infection, and CCR5 expression was monitored, by using a specific monoclonal antibody, on days 1, 6, and 11 after infection. Increased CCR5 expression in MTB-infected macrophages was observed, with a peak on day 6 (64% in MTB-infected versus 33% in control cultures) and a decrease by day 11 (25% in MTB infected versus 13% in control cultures). These results show that CCR5 expression is enhanced in the course of in vitro MTB infection and during active pulmonary tuberculosis.     

Genome-wide requirements for Mycobacterium tuberculosis adaptation and survival in macrophages

Macrophages are central to host defense against microbes, but intracellular pathogens have evolved to evade their antimicrobial functions. Mycobacterium tuberculosis (MTB) has successfully exploited macrophages as its primary niche in vivo, but the bacterial genome-wide requirements that promote its intracellular survival remain undefined. Here we comprehensively identify the MTB genes required for survival by screening for transposon mutants that fail to grow within primary macrophages. We identify mutants showing decreased growth in macrophage environments that model stages of the host immune response. By systematically analyzing several biologically relevant data sets, we have been able to identify putative pathways that could not be predicted by genome organization alone. In one example, phosphate transport, requiring physically unlinked genes, was found to be critical for MTB growth in macrophages and important for establishing persistent infection in lungs. Remarkably, the majority of MTB genes found by this analysis to be required for survival are constitutively expressed rather than regulated by macrophages, revealing the host-adapted lifestyle of an evolutionarily selected intracellular pathogen.