Antimycobacterial Effects of Everolimus in a Human Granuloma Model

Abstract

Mycobacterium tuberculosis (M. tb) has been historically and is currently a threat to global public health. First-line antibiotics have been effective but proven to be burdensome as they have many potential adverse side effects. There has been a recent increase in the number of active tuberculosis (TB) cases due to a prevalence of multidrug and extensively drug-resistant strains of M. tb, and an increasing number of highly susceptible people such as those with Type 2 Diabetes (T2DM) and human immunodeficiency virus (HIV) infection. Multidrug-resistant M. tb infection (MDR-TB) is challenging to treat with existing therapeutics, so novel therapeutics and treatment strategies must be developed. Host-Directed Therapy (HDT) has been a potential target mechanism for effective clearance of infection. Host cell autophagy plays an essential role in antibacterial defense. The mammalian target of rapamycin (mTOR) has been negatively correlated with autophagy induction. Everolimus is an mTOR inhibitor that induces autophagy, but with higher water solubility. Therefore, targeting the mTOR pathway has the potential to develop novel and more effective combination drug therapy for TB. This study tested the effect of everolimus, alone and in combination with current first-line antibiotics (isoniazid and pyrazinamide), on the inhibition of M. tb inside in vitro human granulomas. We found that M. tb-infected in vitro granulomas treated with everolimus alone resulted in significantly decreased M. tb burden compared to similar granulomas in the control group. Cells treated with everolimus doses of either 1 nM or 2 nM in conjunction with pyrazinamide (PZA) produced a significant reduction in intracellular M. tb burden. Treatment groups that received everolimus alone in either 1 nM or 2 nM doses experienced a significant reduction in oxidative stress. Additionally, samples treated with 2 nM everolimus alone were observed to have significantly higher levels of autophagy and mTOR inhibition as well. Results from this study indicate that everolimus is efficacious in controlling M. tb infection in the granulomas and has additive effects when combined with the anti-TB drugs, isoniazid and pyrazinamide. This study has shown that everolimus is a promising host-directed therapeutic in the context of in vitro granuloma M. tb infection. Further study is warranted to better characterize these effects.

Gasdermin D restricts Burkholderia cenocepacia infection in vitro and in vivo

“…Lysate, 6h www.nature.com/scientificreports/ On the other hand, mROS were shown to stimulate autophagy, which is an important macrophage defense mechanism against intracellular bacterial pathogens including B. cenocepacia 59,65,72 . The activation of autophagy promotes the clearance of B. cenocepacia 12 , Legionella pneumophila 18 , Listeria monocytogenes 73 , and Mycobacterium tuberculosis 74 . Increased mROS production which activates autophagy improves the clearance of Mycobacterium tuberculosis 75 , Streptococcus pneumoniae 76 and Listeria monocytogenes 77 .…”

Dual mTORC1/mTORC2 inhibition as a Host-Directed Therapeutic Target in Pathologically Distinct Mouse Models of Tuberculosis

“…Increased delivery of M. tuberculosis to such phagolysosomes mediated through pharmacologic induction of autophagy may be an additional means by which mTOR inhibition could augment pyrazinamide efficacy. Consistent with this, a recent study using an in vitro granuloma model found that everolimus augmented pyrazinamide activity to a more significant extent than its effects on isoniazid activity (24). While we cannot exclude the possibility that co-administration of CC214-2 reduced the exposure to one or more components of the BPaL regimen through an adverse drug-drug interaction, this is unlikely because CC214-2 is not a substrate or inducer of CYP 3A4 or P-gp and was administered separately in time from the antimicrobials to avoid interference with absorption.…”

“…The widely discrepant effects observed between the mTOR inhibitors evaluated here may be attributable to the properties and selectivity of the mTOR inhibitors. Although rapamycin and especially analogs such as everolimus have been explored (7, 12, 14, 24, 25) for use as adjunctive HDT for TB, to our knowledge, they have not been studied previously with combination chemotherapy in a mouse model of TB. Due to their effects on the AKT/mTOR pathway and autophagy, they only partially inhibit mTORC1 and do not inhibit mTORC2.…”

The Oral Delivery of Water‐Soluble Phenol TS‐13 Ameliorates Granuloma Formation in an In Vivo Model of Tuberculous Granulomatous Inflammation

“…The development of combinatorial therapeutic modalities with the involvement of additional antimycobacterial agents and conventional che-motherapy indicated a breakthrough in therapeutic interventions for tuberculosis, especially in cases of multidrugresistant tuberculosis. Among the recent drug discoveries, new "host-targeted" adjunct therapeutic strategies have emerged [1][2][3][4][5].…”