A Role for IFITM Proteins in Restriction of Mycobacterium tuberculosis Infection

Abstract

SUMMARY The interferon (IFN)-induced transmembrane (IFITM) proteins are critical mediators of the host antiviral response. Here, we expand the role of IFITM proteins to host defense against intracellular bacterial infection by demonstrating that they restrict Mycobacterium tuberculosis (MTb) intracellular growth. Simultaneous knockdown of IFITM1, IFITM2, and IFITM3 by RNAi significantly enhances MTb growth in human monocytic and alveolar/epithelial cells, whereas individual overexpression of each IFITM impairs MTb growth in these cell types. Furthermore, MTb infection, Toll-like receptor 2 and 4 ligands, and several proinflammatory cytokines induce IFITM1–3 gene expression in human myeloid cells. We find that IFITM3 co-localizes with early and, in particular, late MTb phagosomes, and overexpression of IFITM3 enhances endosomal acidification in MTb-infected monocytic cells. These findings provide evidence that the antiviral IFITMs participate in the restriction of mycobacterial growth, and they implicate IFITM-mediated endosomal maturation in its antimycobacterial activity.

Imaging flow cytometry analysis of intracellular pathogens

“…4B, Table ). The percentage of infected cells was comparable to results of flow cytometry analysis performed previously [90]. IFITM shRNA cell cultures presented significantly higher infected cells with H37Rv-mCherry compared to the control (see Figure 4A based on data presented in Ranjbar et al [90]).…”

“…This feature as well as IFC use of Rd value – shift in the statistical distribution between two populations (eg. “treated” vs. “untreated”) described in details by Maguire et al [90]. This multi-parametric multi-color approach is actively pursued in parallel with IFC by high-content microscopy, generally using 10× and 20× magnification [91–92].…”

“…Recently, Ranjbar et al demonstrated that the interferon (IFN)-induced transmembrane (IFITM) proteins, particularly IFITM3 is a host restriction factor for MTb [90]. As part of this study, the group used IS-X Mark II (Amnis-Merck, USA) and performed a quantitative analysis investigating the impact of knockdown of IFITM1–3, or the impact of overexpression of IFITM3 on MTb growth.…”

Early diagnosis and effective treatment regimens are the keys to tackle antimicrobial resistance in tuberculosis (TB): A report from Euroscicon's international TB Summit 2016

“…IFITM3 was seen to co-localize with mycobacterial cells in alveolar epithelial cells and overexpression of the protein enhanced endosomal acidification thereby limiting the infection. 67 Bringing the discussion from receptors to signaling molecules, Maria Regina D'Imperio Lima (Universidade de São Paulo, Brazil) spoke about the role of purines, especially extracellular ATP (eATP) in the immune response to severe TB. Hypervirulent mycobacterial strains show varying degrees of pathogenicity.…”

Dual-linker gold nanoparticles as adjuvanting carriers for multivalent display of recombinant influenza hemagglutinin trimers and flagellin improve the immunological responses in vivo and in vitro

“…21 Briefly, JAWS II cells were seeded on a small coverslip in six-well plates and treated with Alexa Fluor 488 (Thermo Fisher Scientific)-conjugated AuNPs-HA/FliC (the final concentration of HA and FliC was 5 µg/mL and 0.5 µg/mL, respectively) through primary amines of proteins and the N-hydroxysuccinimide (NHS) ester moiety of the Alexa Fluor 488 dye. After incubation for 2 h at 37°C, the cells were washed with PBS three times, and then the slides were mounted in mounting media containing 4′,6-diamidino-2-phenylindole (DAPI).…”