Biology subjects

Finethy, R.

Publications and source records attributed to Finethy, R..

3 recordsLinked to original sources

bioRxiv2024

Cross species modeling reveals a role for the unfolded protein response in shaping the transcriptional reaction to Mycobacterium tuberculosis infection

Numerous blood mRNA signatures have been developed to diagnose tuberculosis (TB) disease. The utility of these signatures in diverse populations depends on the inclusion of ubiquitously expressed features, such as type 1 interferon (IFN) production and innate immune cell activities. As a result, these signatures are generally insensitive to heterogeneous responses between individuals. Designing more effective therapies will require understanding the diverse mechanisms underlying pathogenesis by associating them with appropriate preclinical animal models. To address this critical animal-to-human gap, we applied a modeling framework, Translatable Components Regression, which is designed to account for biological heterogeneity by identifying multiple orthogonal axes of variation that are common to humans and animal models. Our framework was capable of distinguishing human active TB from latent TB infection using a model derived from murine data. This discrimination was based on differential expression of numerous biological pathways in addition to the common IFN and neutrophil signatures. Prominent among these predictive pathways was protein translation, which we show is a feature of the Mtb infection-induced Unfolded Protein Response (UPR) in macrophages. We show that this cellular stress pathway controls a variety of immune-related functions in Mtb-infected mouse macrophages, suggesting a possible causative role during the development of TB disease. Significance StatementDespite tuberculosis being one of the top causes of global mortality, the mechanisms that control the progression of disease are still not fully understand. Here we leverage a systems-level modeling approach that incorporates transcriptomics data across thousands of genes from both a traditional tuberculosis mouse model and human clinical samples to implicate a previously unappreciated mechanism in pathogenesis, the unfolded protein response. We validate these findings in a mouse macrophage model and pinpoint which branch of the unfolded protein response might be activated during tuberculosis infection. These insights, originally derived from our cross-species model, may allow us to better understand human tuberculosis pathogenesis and potentially identify therapeutic targets to prevent active tuberculosis.

systems biology↗

bioRxiv2020

Dynamin-related Irgm proteins modulate LPS-induced caspase-4 activation and septic shock

Inflammation associated with gram-negative bacterial infections is often instigated by the bacterial cell wall component lipopolysaccharide (LPS). LPS-induced inflammation and resulting life-threatening sepsis are mediated by the two distinct LPS receptors TLR4 and caspase-4. Whereas the regulation of TLR4 activation by extracellular and phago-endosomal LPS has been studied in great detail, auxiliary host factors that specifically modulate recognition of cytosolic LPS by caspase-4 are largely unknown. This study identifies dynamin-related membrane remodeling proteins belonging to the family of Immunity related GTPases M clade (IRGM) as negative regulators of caspase-4 activation in macrophages. Phagocytes lacking expression of mouse isoform Irgm2 aberrantly activate caspase-4-dependent inflammatory responses when exposed to extracellular LPS, bacterial outer membrane vesicles or gram-negative bacteria. Consequently, Irgm2-deficient mice display increased susceptibility to caspase-4-mediated septic shock in vivo. This Irgm2 phenotype is partly reversed by the simultaneous genetic deletion of the two additional Irgm paralogs Irgm1 and Irgm3, indicating that dysregulated Irgm isoform expression disrupts intracellular LPS processing pathways that limit LPS availability for caspase-4 activation.

immunology↗

bioRxiv2017

Detection of cytosolic Shigella flexneri via a C-terminal triple-arginine motif of GBP1 inhibits actin-based motility

Dynamin-like guanylate binding proteins (GBPs) are gamma interferon (IFN{gamma})-inducible host defense proteins that can associate with cytosol-invading bacterial pathogens. Mouse GBPs promote the lytic destruction of targeted bacteria in the host cell cytosol but the antimicrobial function of human GBPs and the mechanism by which these proteins associate with cytosolic bacteria are poorly understood. Here, we demonstrate that human GBP1 is unique amongst the seven human GBP paralogs in its ability to associate with at least two cytosolic Gram-negative bacteria, Burkholderia thailandensis and Shigella flexneri. Rough lipopolysaccharide (LPS) mutants of S. flexneri co-localize with GBP1 less frequently than wildtype S. flexneri, suggesting that host recognition of O-antigen promotes GBP1 targeting to Gram-negative bacteria. The targeting of GBP1 to cytosolic bacteria, via a unique triple-arginine motif present in its C-terminus, promotes the co-recruitment of four additional GBP paralogs (GBP2, GBP3, GBP4 and GBP6). GBP1-decorated Shigella replicate but fail to form actin tails leading to their intracellular aggregation. Consequentially, wildtype but not the triple-arginine GBP1 mutant restricts S. flexneri cell-to-cell spread. Furthermore, human-adapted S. flexneri, through the action of one its secreted effectors, IpaH9.8, is more resistant to GBP1 targeting than the non-human-adapted bacillus B. thailandensis. These studies reveal that human GBP1 uniquely functions as an intracellular glue trap inhibiting the cytosolic movement of normally actin-propelled Gram-negative bacteria. In response to this powerful human defense program S. flexneri has evolved an effective counter-defense to restrict GBP1 recruitment.\n\nImportanceSeveral pathogenic bacterial species evolved to invade, reside and replicate inside the cytosol of their host cells. One adaptation common to most cytosolic bacterial pathogens is the ability to co-opt the hosts actin polymerization machinery, in order to generate force for intracellular movement. This actin-based motility enables Gram-negative bacteria such as Shigella to propel themselves into neighboring cells thereby spreading from host cell to host cell without exiting the intracellular environment. Here, we show that the human protein GBP1 acts as a cytosolic glue trap capturing cytosolic Gram-negative bacteria through a unique protein motif and preventing disseminated infections in cell culture models. To escape from this GBP1-mediated host defense, Shigella employs a virulence factor that prevents or dislodges the association of GBP1 with cytosolic bacteria. Thus, therapeutic strategies to restore GBP1 binding to Shigella may lead to novel treatment options for shigellosis in the future.

microbiology↗