The process of drug discovery and drug development consumes billions of dollars to bring a new drug to the market. Drug development is time consuming and sometimes, the failure rates are high. Thus, the pharmaceutical industry is looking for a better option for new drug discovery. Drug repositioning is a good alternative technology that has demonstrated many advantages over de novo drug development, the most important one being shorter drug development timelines. In the last two decades, drug repositioning has made tremendous impact on drug development technologies. In this review, we focus on the recent advances in drug repositioning technologies and discuss the repositioned drugs used for inflammatory diseases such as sepsis, asthma, and atopic dermatitis.

Innate immunity is a first line defence system in the body which is for sensing signals of danger such as pathogenic microbes or host-derived signals of cellular stress. Pattern recognition receptors (PRR's), which present in the cell memebrane, are suspect the infection through pathogen-associated molecular patterns (PAMP), and activate innate immunity with response to promote inflammation via inflammatory cells such as macrophages and neutrophils, and cytokines. Inflammasome are protein complexes which are part of innate immunity in inflammation to remove pathogens and repair damaged tissues. What is the important role of inflammation in disease? In this review, we are focused on the action mechanism of NLRP3 inflammasome in inflammatory diseases such as asthma, atopic dermatitis, and sepsis.

Atopic dermatitis is a chronic, inflammatory skin disorder associated with defective skin barrier and epidermal hyper reactivity. AD is a Th2 mediated allergic disease. GATA3 is a transcription factor that plays an important role in Th2 differentiation. In this study we investigated the per2 gene role and the expression of per2 related genes in atopic dermatitis. We established the atopic dermatitis animal model in per2 knock out and C57BL/6 by 2,4-dinitrochlorobenzene (DNCB). A subset of mice in both per2 knock out and C57BL/6 were treated with saline as control group. The skin lesions severity score was alleviated in per2 knock out mice DNCB group than wild type group. We examined the TNF-α mRNA expression in skin samples that showed that per2 knock out mice protected from DNCB induced inflammation than wild type mice. We next examined BMAL1 mRNA expression in skin samples that showed BMAL1 functioned as anti-inflammatory molecule in per2 knock out mice and levels are high than wild type mice and GATA3 expression levels were not initiated in per2 knock out mice than wild type mice. According to these results we hypothesized per2 knock out mice protected from allergic atopic dermatitis by increasing anti-inflammatory molecule BMAL1 through supressing GATA3.

Drug repositioning is the application of known drugs and compounds to treat new diseases and is the process of identifying new uses for drugs outside the scope of their original medical indication. Our study previously revealed anti-atopic dermatitis activity of rifampicin, which is used for the treatment of tuberculosis. We herein investigated the effect of rifampicin on asthma. Asthma was induced in BALB/C mice and the mice were treated with rifampicin by oral administration. The inflammatory responses were alleviated in the rifampicin-treated group. Serum The level of inflammatory cytokines was ameliorated in bronchoalveolar lavage fluid (BALF) from mice treated with rifampicin. We next examined whether rifampicin has anti-atopic activity via suppression of mast cell activation. Rifampicin suppressed the release of β-hexosaminidase and histamine from human mast cell (HMC)-1 stimulated with compound 48/80. Treatment with rifampicin inhibited secretion of TNF-α and PGD2 in mast cells activated by compound 48/80. The mRNA expression of COX-2 was reduced in the cells treated with rifampicin. Our findings suggest that rifampicin has efficacy and could be applicable to develop potent therapeutic reagent for the treatment of asthma.