Synthetic biology is an investigative and constructive means of understanding the complexities of biology. Substantial progress in the fields has resulted in the creation of synthetic gene circuits, which when uploaded into the appropriate nanoliposomal vehicle, can be used for a tunable response in a cell. These tunable elements can be applied to treat diseased condition for a transition to a healthy state. Though in its nascent stage of development synthetic biology is beginning to use its constructs to bring engineering approaches into biomedicine for treatment of infectious disease leishmaniasis.

With the advent of synthetic biology in medicine many synthetic or engineered proteins have made their way to therapeutics and diagnostics. In this paper, the downstream gene network of CD14-TNF-EGFR pathway in leishmaniasis, a tropical disease, is reconstructed. Network analysis showed that NFkB links the signaling and gene network, used as a point of intervention through a synthetic circuit embedded within the negative autoregulatory feedback loop. A chimeric protein kinase C (PKC) is incorporated in the synthetic circuit, under the transcriptional regulation of Lac repressor and IPTG, as an inducer. The chimeric PKC_ζα via IκKb phosphorylation activates NFκB, and modulates the gene expression from an anti-inflammatory to a pro-inflammatory phenotype in in vitro L. major infected macrophage model. This is the first ever report of a synthetic device construction in leishmania.

Cutaneous leishmaniasis is the most common form of lesihmaniasis, caused by and is spread by the bite of a sandfly This species infects the Leishmania major . macrophages and dendritic cells Due to multi-drug resistance, there is a need for a new therapeutic technique. Recently, a novel molecular motor of , Myosin XXI, was classified and characterized. In addition, the drug Leishmania resistance in this organism has been linked with the overexpression of ABC transporters. Systems biology aims to study the simulation and modeling of natural biological systems whereas synthetic biology deals with building novel and artificial biological parts and devices Together they have contributed enormously to drug discovery, vaccine design and development, infectious disease detection and diagnostics. Synthetic genetic regulatory networks with desired properties, like toggling and oscillation have been proposed to be useful for gene therapy. In this work, a nanocircuit with coupled bistable switch -repressilator has been designed, simulated in the presence and absence of inducer, using Tinker Cell. When inducer is added, the circuit has been in silico, shown to produce reporter at high levels, which will impair the activity of Myosin XXI and ABC transporters. Validation of the circuit was also performed using GRENITS and BoolNet. The influence of inducer on the working of the circuit, i.e., the type of gene expression, response time delay, the steady states formed by the circuit and the quasipotential landscape of the circuit were performed. It was found that the addition of inducer reduced the response time delay in the graded type of gene expression and removed the multiple intermediate attractors of the circuit. Thus, the inducer increased the probability of the circuit to be present in the dominant stable state with high reporter concentration and hence the designed nanocircuit may be used for the treatment of leishmaniasis.

Autophagy is a self-destructing mechanism of cell via lysosomal degradation, which helps to degrade/ destroy hazardous substances, proteins, degenerating organelles and recycling nutrient. It plays an important role in cellular homeostasis and regulates internal environment of cell, moreover, when needed causes non-apoptotic programmed death of cell. It's usually detailed with ageing and nutritional stress, but recent researches provide support for its role in innate as well as adaptive immunity. Autophagy has been observed as one of the major factors in parasite clearance in leishmaniasis. Due to intra-cellular pathogen, the cell mediated response is only alternative for adaptive immunity against Leishmania in host. T-cells have been observed as main component of cell mediated immunity in leishmaniasis. The differentiation of T-cells generates either destruction or proliferation of parasite as different kind of cytokine mediate different results. Pro-inflammatory cytokine IL12 and TNFα generate Th2 response which helps in active phagocytosis of parasite whereas an anti-inflammatory cytokine like IL10 mediate parasite promotion by blocking autophagic pathways and inhibiting phagocytic actions. TLR2/6 mediated signaling stimulated by LPG produces many pro-inflammatory cytokines like IL12, TNFα and IL6 etc. In macrophages, it is found that TNFα via autocrine signaling induce autophagy and help in parasite killing of Toxoplasma gondii via JNK phosphorylation in macrophages. The phosphorylated JNK induces Beclin by phosphorylating Bcl2, which inhibits Beclin action, thus releasing Beclin and promoting VpS34 which recruits PI3P for autophagosome formation. Recruitment of PI3P is controlled by ATG9 protein, autophagy related gene protein, which in normal condition is inhibited by mTOR via ULK/ ATG1. IL10 has been observed to inhibit autophagy via starvation induced AKT-PI3K pathway in macrophages and result in inducing mTOR. Thus, we can conclude that IL10 inhibits recruitment of PI3P via mTOR. Through systems aspect, here, we decipher that Atg9-PI3P acts as a negative feedback loop in autophagic machinery of leishmaniasis.

Stochastic variations in the transcription factor target gene network influences the dynamics of protein levels. The mathematical model built, here, is useful to study the cytokine response and the resulting dynamical patterns in leishmaniasis. The fluctuations produced affect the expression rate of its target in the regulatory synthetic circuit designed by means of a negative feedback loop insertion. Thus, the faster the response time, smaller is the fluctuation of the system observed and it can be justified that the TFTG network embedded can be understood with the recurring dynamics of the designed synthetic circuit.

Cutaneous leishmaniasis is the most common form of leishmaniasis, caused by Leishmania major and is spread by the bite of a sandfly .This species infects the macrophages and dendritic cells Due to multi-drug resistance, there is a need for a new therapeutic technique. Recently, a novel molecular motor of Leishmania, Myosin XXI, was classified and characterized. In addition, the drug resistance in this organism has been linked with the overexpression of ABC transporters. Systems biology aims to study the simulation and modeling of natural biological systems whereas synthetic biology deals with building novel and artificial biological parts and devices  Together they have contributed enormously to drug discovery, vaccine design and development, infectious disease detection and diagnostics. Synthetic genetic regulatory networks with desired properties, like toggling and oscillation have been proposed to be useful for gene therapy. In this work, a nanocircuit with coupled bistable switch – repressilator  has been designed, simulated in the presence and absence of inducer, in silico, using Tinker Cell. When inducer is added, the circuit has been shown to produce reporter at high levels, which will impair the activity of Myosin XXI and ABC transporters. Validation of the circuit was also performed using GRENITS and BoolNet. The influence of inducer on the working of the circuit, i.e., the type of gene expression, response time delay, the steady states formed by the circuit and the quasipotential landscape of the circuit were performed. It was found that the addition of inducer reduced the response time delay in the graded type of gene expression and removed the multiple intermediate attractors of the circuit. Thus, the inducer increased the probability of the circuit to be present in the dominant stable state with high reporter concentration and hence the designed nanocircuit may be used for the treatment of leishmaniasis .