Despite the global efforts and the financial investment by the government and non-governmental organisation, tuberculosis still remains a leading cause of death worldwide. According to the global report on tuberculosis as published by the world health organisation, 3.7% of the new cases and 20% of the previously treated cases of tuberculosis has now transformed in multidrug resistant (MDR) variants. This MDR is resistant to rifampicin and isoniazid. Not only MDR, the initial report as published from South Africa showed the existence of the extensively drug resistant (XDR) tuberculosis. The XDR strains are resistant to rifampicin, isoniazid, fluoroquinolones and other second-line of injectable drugs like capreomycin, amikacin and kanamycin. The countries in the Easter Europe have highest recorded cases of MDR tuberculosis around the world and the majority of the tuberculosis cases arise in the china, India, Indonesia and Philippines.The treatment of the MDR tuberculosis is toxic, lengthy and expensive. It is also associated with poor outcomes. Certain fluoroquilones, ethionamide or prothionamidehas been shown to provide effective response against MDR-TB. However, randomized trials are required to optimize the treatment. Linezoliod is used off-label to treat MDR tuberculosis in the absence of strong systematic evidence. Linezolid has strong efficacy against MDR tuberculosis but must be used with proper caution.
Aim of the Research
TB can be treated with a cocktail of antibiotics, chemotherapy and vaccines but the efficacy is limited. Therefore, there is a pressing need to the development of novel therapy for the treatment of MDR-TB. Mycobacterium tuberculosis (Mtb) invades and then replicate inside host macrophages, the novel therapy must target an approach to kill intracellular bacteria without harming the host cell. In this regards, anti-microbial peptides (AMPs) can be treated to be effective. However, AMPs are cytotoxic to mammalian cells.
The aim of this research is to genetically engineered AMPs from the marcophage and neutrophil derive proteins, which are active at low concentration (not harming host cell). The geneticalengineering will be performed via cloning the AMPs from the macrophage derivedprotein followed by PCR verification. The study will target defensins, a class of cationic peptides with microbicidal, immunomodulatory and cytotoxic activities. It also serves as an effective mediator between cellular and innate immunity. For this particular study, the main target will be human beta-defensins (HBD-3) which are secreted by the mucosal epithelial cells. They are the first line of defense against infection . The reason behind choosing HBD is, it can retain its anti-microbial activity at physiological salt concentration.Since Mtbdown regulates cationic peptides, the study will aim to introduce exogenous peptide administration or via hormonal induction of peptides.
Literature Review
XDR and MDR-TB are associated with worse treatment outcomes with the patients of TB. Recently delamandid (OPC-67683) has been discovered as a novel drug for the treatment of MDR-Tb infection. The analysis performed over the patients of TB showed positive outcome when they are treated with delamandid for 6 months at a stretch in combination with an optimized background regime. This combinational treatment has been found to reduce the mortality rate of the both XDR and MDR-TB patients.
In 2012, 450,00 cases reported to be MDR-TB globally. According to WHO, significant efforts are required to improve the present average rate of the successful treatment of patients who are suffering from MDR-TB. The current therapy that is used for the treatment of TB is arduous and long and is mainly concerned with the antiquated drugs that are bacteriostatic in nature and are associated with several side effects. Bedaquiline, a diarylquinolinehas been found to inhibit mycobacterial ATP synthase. It is considered as a first ever anti-tuberculosis drug that is combating against TB under completely new mechanism. The importance of Badaquilineis: it is bactericidal in nature. The inclusion of the bedaquiline in the TB treatment regime is associated with reduced risk of pre-extensive drug resistance along with reduced risk of other background drug resistance.
Pediatric MDR-TB is also a public health challenge. The clinical management of the pediatric TB is challenging and the recommendations are strictly based on the restricted evidence. Moreover, the treatment of the MDR is not cost effective any only a small fraction of the reported cases are treated according to the basis of the international guidelines. In India, Linezolid is used a safe and cost-effective alternative for the treatment of the MDR tuberculosis especially for the patients who are failing to afford high cost treatment.
At present, next-generation antibiotics, AMPs and proteins, popularly known as "natural antibiotics" administered alone or in conjunction with other conventional drugs are showing promising results. Out of defensins, beta-defensins can be excepted to have promising results against Mtb. Mtb infection lead to the over-expression of beta-defensins in the endothelial cells . Further results suggested that L-isoleucine lead to the over-expression of beta-defensins that promotes reducing of the viral over-load (MDR-Mtb). Beta-defensins exerts bactericidal activity on the latent phase of Mtbinfection .
Methodology
Endogeneous administration of the purified defensins (AMP) followed by the study of the intracellular killing of the bacteria via study under the fluorescence microscopy. The efficacy of AMP protein upon bactericidal activity will be studied alone and in combination of anti-Mtb drugs.The main challenge of the research is to frame effective peptide delivery system for the endogenous expression of AMP.
Ethical Consideration
The overall affect of defensinswill be studied over swiss albino mice and hence prior approval from the animal ethical committee will be taken before the initial of the animal trial in the research.
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