Integration of Chemical and RNAi Multiparametric Profiles Identifies Triggers of Intracellular Mycobacterial Killing

Abstract

Pharmacological modulators of host-microbial interactions can in principle be identified using highcontent screens. However, a severe limitation of this approach is the lack of insights into the mode of action of compounds selected during the primary screen. To overcome this problem, we developed a combined experimental and computational approach. We designed a quantitative multiparametric image-based assay to measure intracellular mycobacteria in primary human macrophages, screened a chemical library containing FDA-approved drugs, and validated three compounds for intracellular killing of M. tuberculosis. By integrating the multiparametric profiles of the chemicals with those of siRNAs from a genome-wide survey on endocytosis, we predicted and experimentally verified that two compounds modulate autophagy, whereas the third accelerates endosomal progression. Our findings demonstrate the value of integrating small molecules and genetic screens for identifying cellular mechanisms modulated by chemicals. Furthermore, selective pharmacological modulation of host trafficking pathways can be applied to intracellular pathogens beyond mycobacteria.

Autophagy in the Fight Against Tuberculosis

“…Gefitinib, an epidermal growth factor receptor (EGFR) inhibitor used to treat breast and other types of cancers, has also been shown to induce autophagy and to be effective in M. tuberculosis killing in a mouse model (Stanley et al, 2014). Nortriptyline and fluoxetine, currently used to treat depression, were also reported to promote autophagy and enhance mycobacteria clearance (Sundaramurthy et al, 2013;Stanley et al, 2014). While the mechanisms behind autophagy enhancement by these two drugs are currently unknown, the fluoxetine effect is related to increased TNF-a secretion (Stanley et al, 2014).…”

Autophagy in Tuberculosis

“…The enhanced effectiveness of these antibiotics in synergy with autophagy may explain the sterilizing properties of pyrazinamide. Furthermore, several compounds that can induce autophagy have been shown to inhibit M. tuberculosis (Floto et al 2007;Lam et al 2012;Sundaramurthy et al 2013), raising the possibility of host-based therapies based on autophagy-inducing drugs.…”

Small-molecule enhancers of autophagy modulate cellular disease phenotypes suggested by human genetics

“…involving modulation of proinflammatory responses in Mtb-infected macrophages (12,13). Likewise, the autophagy-inducing peptide Tat-Beclin1 enhances autophagy-dependent antiviral activity in cell and animal models (14).…”