RNAseq reveals hypervirulence-specific host responses toM. tuberculosisinfection

Abstract

The distinguishing factors that characterize the host response to infection with virulent Mycobacterium tuberculosis (M.tb) are largely confounding. We present an infection study with 2 genetically closely related M.tb strains that have vastly different pathogenic characteristics. The early host response to infection with these detergent-free cultured strains was analyzed through RNAseq in an attempt to provide information on the subtleties which may ultimately contribute to the virulent phenotype. Murine bone marrow derived macrophages (BMDMs) were infected with either a hyper- (R5527) or hypovirulent (R1507) Beijing M. tuberculosis clinical isolate. RNAseq revealed 69 differentially expressed host genes in BMDMs during comparison of these 2 transcriptomes. Pathway analysis revealed activation of the stress-induced and growth inhibitory Gadd45 signaling pathway in hypervirulent infected BMDMs. Upstream regulators of interferon activation such as and IRF3 and IRF7 were predicted to be upregulated in hypovirulent-infected BMDMs. Additional analysis of the host immune response through ELISA and qPCR included the use of human THP-1 macrophages where a robust proinflammatory response was observed after infection with the hypervirulent strain. RNAseq revealed 2 early-response genes (ier3 and saa3) and 2 host-defense genes (oasl1 and slpi) that were significantly upregulated by the hypervirulent strain. The role of these genes under M.tb infection conditions are largely unknown but here we provide validation of their presence with use of qPCR and Western blot. Further analysis into their biological role during infection with virulent M.tb is required.

Mycobacterium tuberculosisstimulates IL-1β production by macrophages in an ESAT-6 dependent manner with the involvement of serum amyloid A3

“…4A). Interestingly the majority of these genes were also expressed by macrophages upon infection with a hypervirulent Mtb strain (30, 31). The top 20 genes with the highest p values were shown with the heat map demonstrated that SAA3 is one of the most highly upregulated genes by ESAT-6 (Fig.…”

2′-5′-Oligoadenylate synthetase-like protein inhibits intracellular M. tuberculosis replication and promotes proinflammatory cytokine secretion

“…Its upregulation has also been observed in response to a number of Gram-positive and Gram –negative, and acid-fast bacteria from as early as 4 h p.i. These pathogens include Brucella abortus [9], Chlamydia trachomatis [6], Lactobacillus acidophilus [10], Chlamydia pneumoniae [7], Listeria monocytogenes [8], Mycobacterium leprae [13] and in Mycobacterium tuberculosis [11] (a previous study in our lab). Questions regarding the biological role of OASL during M. tuberculosis infection remained unanswered.…”

Global proteomic profiling of primary macrophages duringM. tuberculosisinfection identifies TAX1BP1 as a mediator of autophagy targeting

“…One of the modalities by which macrophages sense and respond to Mtb is by changing transcription 4,5 , which leads to an increased pro-inflammatory state 4,6 . However, many other cellular processes (e.g.…”