Comparative analysis of macrophage post-translational modifications during intracellular bacterial pathogen infection

Abstract

SUMMARYMacrophages activate robust antimicrobial functions upon engulfing virulent bacteria, yet a wide array of pathogens paradoxically thrive within these innate immune cells. To probe the pathogen-macrophage interface, we used proteomics to comprehensively quantify changes in post-translational modifications (PTMs) of host proteins during infection with three evolutionarily diverse intracellular pathogens: Mycobacterium tuberculosis, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes. Comparing global phosphorylation and ubiquitylation patterns identified extensive reprogramming of cellular pathways during infection, with ubiquitylation patterns revealing unique pathogen-specific molecular response signatures undetectable by transcriptional profiling. Differential PTM changes during infection with attenuated M. tuberculosis cells lacking the ESX-1 virulence determinant revealed extensive modification of phagosome dynamics and antiviral type I interferon activation. We found that M. tuberculosis-mediated activation of the antiviral OASL1-IRF7 pathway promotes bacterial replication, uncovering a new mechanism of virus-bacterial synergy. Our data reveals remarkable specificity in innate cellular responses to complex stimuli and provides a resource for deeper understanding of host-pathogen interactions.

The balance between antiviral and antibacterial responses duringM. tuberculosisinfection is regulated by the ubiquitin ligase CBL

“…Integrating the results of different studies that examined different viral response regulators suggests that the transcriptional program controlling the expression of antiviral proteins such as IFN-β is likely to be comprised of several distinct modules, as the perturbation of different regulators causes distinct Mtb-related phenotypes. For example, in isolated ex vivo macrophages, disruption of CBL, TRIM14, or IRF7 alters the expression of antiviral effectors and alters the ability of a macrophage to restrict Mtb replication (45,46,67). In contrast, perturbation of RIG-I, SP140 or IFNAR has no effect on Mtb replication in isolated macrophages but profoundly alters Mtb susceptibility in mice (25,39,40,(67)(68)(69)(70).…”

“…For example, in isolated ex vivo macrophages, disruption of CBL, TRIM14, or IRF7 alters the expression of antiviral effectors and alters the ability of a macrophage to restrict Mtb replication (45,46,67). In contrast, perturbation of RIG-I, SP140 or IFNAR has no effect on Mtb replication in isolated macrophages but profoundly alters Mtb susceptibility in mice (25,39,40,(67)(68)(69)(70). This suggests that while all these pathways regulate IFN-β signaling, they might differ in their regulation of other target genes, and that these differences drive distinct physiologic states in Mtbinfected macrophages.…”

Deficiency in Galectin-3, -8, and -9 impairs immunity to chronic Mycobacterium tuberculosis infection but not acute infection with multiple intracellular pathogens

“…Several bacteria, including Mycobacterium tuberculosis (Mtb), Salmonella enterica serovar Typhimurium (Stm), Listeria monocytogenes (Lm), Shigella flexneri, and Legionella pneumophila (Lp), inflict phagosomal membrane damage that leads to the recruitment of Gal-3, -8, and -9 [7][8][9][19][20][21]. Previously, we found that all three of these galectins are also ubiquitylated during Mtb infection [22,23]. In addition to binding host carbohydrate, some galectins can interact directly with bacteria and their cell wall glycans [24][25][26][27], including Gal-9 binding of the Mtb cell wall polysaccharide arabinogalactan [27].…”

Deficiency in Galectin-3, -8, and -9 impairs immunity to chronicMycobacterium tuberculosisinfection but not acute infection with multiple intracellular pathogens

“…During infection, galectin recruitment and signaling promote antibacterial autophagy and bacterial growth restriction [9,15,20], proinflammatory signaling [25], and recruitment of antibacterial guanylate-binding proteins [21]. In addition, we previously found that Gal-3, -8, and -9 are all ubiquitylated during Mtb infection [26, 27], although the implications of these modifications remain unclear.…”