Modeling of variables in cellular infection reveals CXCL10 levels are regulated by human genetic variation and the Chlamydia-encoded CPAF protease.

Abstract

Susceptibility to infectious diseases is determined by a complex interaction between host and pathogen. For infections with the obligate intracellular bacterium Chlamydia trachomatis, variation in immune activation and disease presentation are regulated by both host genetic diversity and pathogen immune evasion. Previously, we discovered a single nucleotide polymorphism (rs2869462) associated with absolute abundance of CXCL10, a pro-inflammatory T-cell chemokine. Here, we report that levels of CXCL10 change during C. trachomatis infection of cultured cells in a manner dependent on both host and pathogen. Linear modeling of cellular traits associated with CXCL10 levels identified a strong, negative correlation with bacterial burden, suggesting that C. trachomatis actively suppresses CXCL10. We identified the pathogen-encoded factor responsible for this suppression as the chlamydial protease- or proteasome-like activity factor, CPAF. Further, we applied our modeling approach to other host cytokines in response to C. trachomatis and found evidence that RANTES, another T-cell chemoattractant, is actively suppressed by Chlamydia. However, this observed suppression of RANTES is not mediated by CPAF. Overall, our results demonstrate that CPAF suppresses CXCL10 to evade the host cytokine response and that modeling of cellular infection parameters can reveal previously unrecognized facets of host-pathogen interactions.

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Published Version (Please cite this version)

10.1038/s41598-020-75129-y

Publication Info

Schott, Benjamin H, Alejandro L Antonia, Liuyang Wang, Kelly J Pittman, Barbara S Sixt, Alyson B Barnes, Raphael H Valdivia, Dennis C Ko, et al. (2020). Modeling of variables in cellular infection reveals CXCL10 levels are regulated by human genetic variation and the Chlamydia-encoded CPAF protease. Scientific reports, 10(1). p. 18269. 10.1038/s41598-020-75129-y Retrieved from https://hdl.handle.net/10161/21774.

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Scholars@Duke

Valdivia

Raphael H. Valdivia

Nanaline H. Duke Distinguished Professor of Molecular Genetics and Microbiology

My laboratory is interested in microbes that influence human health, both in the context of host-pathogen and host-commensal interactions. For many pathogens, and certainly for most commensal microbes, we have an incomplete molecular understanding of how host and microbial factors contribute to health and disease. My research group focuses on two experimental systems:

Chlamydia trachomatis infections are responsible for the bulk of sexually transmitted bacterial diseases and are the leading cause of infectious blindness (trachoma) in the world. Chlamydia  resides within a membrane bound compartment (“inclusion”). From this location, the pathogen manipulates the cytoskeleton, inhibits lysosomal recognition of the inclusion, activates signaling pathways, re-routes lipid transport, and prevents the onset of programmed cell death. Our laboratory focuses on identifying and characterizing the bacterial factors that are secreted into the host cell cytoplasm to manipulate eukaryotic cellular functions. We use a combination of cell biology, biochemistry, genetics, genomics, proteomics and molecular biology to determining the function of virulence factors that reveal novel facets of the host-pathogen interaction. Our goal is to understand how these obligate intracellular bacterial pathogens manipulate host cellular functions to replicate, disseminate and cause disease, and in the process develop strategies to ameliorate the damage caused by these infections to the female reproductive organs.

Akkermansia muciniphila is prevalent member of the gut microbiota that proliferates in the mucus layers of our lower gastrointestinal tract and contribute to nutrient homeostasis and human immunological health. My research group developed genetic tools to characterize these microbes to define the mechanisms used to colonize the human gut and identify the molecular and cellular pathways that underscore Akkermansia's impact on immune homeostasis.  In the process, we seek to engineer strains of Akkermansia that enhance their probiotic potential.

Ko

Dennis Ko

Associate Professor in Molecular Genetics and Microbiology

Using Pathogens to Decipher Genetic Variation Connecting Cell Biology and Disease Susceptibility
Despite improvements in public health, advancements in vaccines, and the development of many classes of antibiotics, infectious disease is still responsible for over a quarter of all deaths worldwide. However, even for the most devastating of pandemics, individuals demonstrate a large variability in the severity of infection. The long-term goal of the lab is to understand the genetic basis for differences in susceptibility to infection and related inflammatory disorders. We approach this question through a combination of experimental and computational approaches that combine high-throughput cell biology with quantitative human genetics. The identified genetic differences serve as the starting point for exploring new cell biology and human disease susceptibility genes.


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