Heteromers and L-type calcium channels: Increasing the potency of emodepside in filarial nematode model, Brugia malayi - Project Summary Filarial nematode infections are a global concern for public health. Lymphatic filariasis, caused by filarial nematodes like Wucheria bancrofti, Brugia malayi, and Brugia timori, affect over 120 million people in tropical countries of the world. Lymphatic filariases are not usually life-threatening, but people are often ostracized from society due to distorted limbs and skin lesions. Control of these parasitic nematodes depends significantly on the mass drug administration (MDA) of anthelmintic drugs: but there are no effective macrofilaricides that kill the adult parasites in the host. There are concerns that mass drug administration of microfilaricide chemotherapy will lead to the development of resistance. Emodepside is an emerging anthelmintic that targets nematode large conductance potassium channels SLO-1 and is the only drug that can kill adult filaria. Single dose emodepside treatments could allow a major advance over existing MDA programs. However, the in vitro efficacy of emodepside varies between the different filarial species, the sex, and the life cycle stages of the same parasite species. There is also a disconnect between the in vivo and in vitro effect of emodepside on the SLO K channels. Here, we propose, Aim #1: To characterize the pharmacology of endogenous SLO-1/2 channels. We will use erg-28 mutants in C. elegans to investigate the pharmacology of the endogenous SLO-1/2 receptors for activation by emodepside. We will test for activation and potentiation of emodepside responses by other BK channel agonists like Arachidonic acid and NS11021. We will parasitize C. elegans by expressing Bma-slo-1 and Bma-slo-2 and assay the pharmacology of the endogenous filarial SLO-1/2 heteromer. Aim #2: To test the hypothesis that EGL-19 channels modulate SLO-1 responses to emodepside. We will knock down egl-19 in B. malayi and investigate the potency of emodepside inhibiting the motility of these worms. We will also evaluate the role of EGL-19 agonists and antagonists in potentiating or inhibiting the emodepside responses in worm motility. We will determine if EGL- 19 modulates SLO-1 in microdomains using cell-attached patch-clamp experiments on Brugia muscle. On completing these experiments, we will have enhanced insight into the pharmacology of the endogenous SLO-1/2 heteromeric channels and aid the development of new and more effective macrofilaricides. We will improve the efficacy of emodepside by using drug combinations that selectively increase calcium in micro-domains close to SLO-1 channels. The use of combination therapy can enhance the potency and efficacy of emodepside where bioavailability or activity against particular nematodes species may be low.
