Abstract
In human primary dendritic cells (DC) rapamycin—an autophagy inducer and protein synthesis inhibitor—overcomes the autophagy block induced by Mycobacterium tuberculosis (Mtb) and promotes a Th1 response via IL-12 secretion. Here, the immunostimulatory activity of rapamycin in Mtb-infected DC was further investigated by analyzing both transcriptome and translatome gene profiles. Hundreds of differentially expressed genes (DEGs) were identified by transcriptome and translatome analyses of Mtb-infected DC, and some of these genes were found further modulated by rapamycin. The majority of transcriptome-associated DEGs overlapped with those present in the translatome, suggesting that transcriptionally stimulated mRNAs are also actively translated. In silico analysis of DEGs revealed significant changes in intracellular cascades related to cytokine production, cytokine-induced signaling and immune response to pathogens. In particular, rapamycin treatment of Mtb-infected DC caused an enrichment of IFN-β, IFN-λ and IFN-stimulated gene transcripts in the polysome-associated RNA fraction. In addition, rapamycin led to an increase of IL-12, IL-23, IL-1β, IL-6, and TNF-α but to a reduction of IL-10. Interestingly, upon silencing or pharmacological inhibition of GSK-3β, the rapamycin-driven modulation of the pro- and anti-inflammatory cytokine balance was lost, indicating that, in Mtb-infected DC, GSK-3β acts as molecular switch for the regulation of the cytokine milieu. In conclusion, our study sheds light on the molecular mechanism by which autophagy induction contributes to DC activation during Mtb infection and points to rapamycin and GSK-3β modulators as promising compounds for host-directed therapy in the control of Mtb infection.
Highlights
As reported by World Health Organization, millions of people in the world continue to fall ill each year with tuberculosis (TB), one of the top killer infectious disease caused by Mycobacterium tuberculosis (Mtb) [1]
We have previously shown that in human primary dendritic cells (DC) the autophagy inducer rapamycin overcomes the block exerted by Mtb on autophagosome/lysosome fusion, and enhances interleukin 12 (IL-12) secretion driving a protective Th1 response [9]
Total and polysome-associated RNA samples were prepared from uninfected DC or DC infected for 16 h with live H37Rv Mtb alone or in combination with rapamycin
Summary
As reported by World Health Organization, millions of people in the world continue to fall ill each year with tuberculosis (TB), one of the top killer infectious disease caused by Mycobacterium tuberculosis (Mtb) [1]. The reasons behind Mtb capacity to maintain this sad primacy must be sought in the different strategies employed by this pathogen to survive inside the host, ranging from the establishment of a latent infection to several mechanisms for evading the immune response [2]. In this context, the host innate immune system and its plethora of defense mechanisms critically influence the fate of the infection [2]. Treatment with rapamycin leads to increased expression of interferon-b (IFN-b) and increased production of the pro-Th1 cytokine, interleukin 12 (IL-12) [9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
