Chlamydia trachomatis genital infection is a major cause of pelvic inflammatory disease (PID), resulting in ectopic pregnancy and infertility among women. PID is caused by an overt inflammatory response in the upper genital tract. The specific immune mechanisms and effectors that trigger this often-devastating condition are poorly defined. The mouse model is a useful tool to study these inflammatory responses in the oviduct. Using this model, we have shown that signaling from the host receptors IFNAR (IFNa/b receptor) and IL-1R (IL-1 receptor) leads to oviduct pathology during genital chlamydial infection. However, the exact mechanisms by which chlamydiae initiate these responses, and the host molecules engaged, are unknown. The central hypothesis of this application is that type I IFN and IL-1 signaling synergistically drive oviduct damage during infection by activating cell death pathways and increasing PMN infiltration. Our overall objectives are to (1) delineate the upstream activators and downstream effectors of IFN and IL-1R signaling which lead to pathology, and (2) therapeutically block the downstream mediators of IL-1R signaling-induced oviduct damage, using the mouse model. To test our hypothesis and achieve our objectives, we will identify the specific molecular interaction between host DNA sensor and chlamydial effector that initiate IFNb expression during infection (Aim 1). We will test the hypothesis that caspase-11 mediated cell death activation is a major player in pathology and type I IFN signaling results in caspase-11 activation during infection (Aim 2). We will explore the role of damage associated molecular patterns (DAMPs), such as HMGB-1 and IL-1a present in genital secretions of infected mice, in oviduct pathology (Aim 3). We also propose to specifically target the damaging arm of IL-1R signaling using inhibitors in ex vivo Fallopian tube explants and in the mouse model to protect from pathology (Aim 4). The central theme of this application is that these signaling events likely evolved to reduce pathogen load in the oviduct, but lead to cell death and tissue damage, thereby come at an expense of adverse reproductive health in women. Delineating the innate immune pathways to segregate the damaging and protective constituents, facilitates therapeutic targeting to prevent disease without affecting resolution of infection. Specific outcomes of the proposed study include identification of host molecules involved in amplification of the inflammatory response during infection, which would serve as biomarkers and therapeutic targets to prevent reproductive sequelae in women infected with Chlamydia.

Public Health Relevance

This study will provide a direct link of key host molecules involved in oviduct pathology during genital chlamydial infection and provide therapeutic targets to ameliorate disease in the mouse model. These studies can be extended to provide potential diagnostic tools for identifying infected women with greater risk of developing PID and identify novel therapeutics that could be co-administered with antibiotic therapy to reduce the risk of long term reproductive sequelae.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Host Interactions with Bacterial Pathogens Study Section (HIBP)
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Hiltke, Thomas J
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University of North Carolina Chapel Hill
Schools of Medicine
Chapel Hill
United States
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Nagarajan, Uma M; Tripathy, Manoj; Kollipara, Avinash et al. (2018) Differential signaling pathways are initiated in macrophages during infection depending on the intracellular fate of Chlamydia spp. Immunol Cell Biol 96:246-256
Zhang, Yugen; Yeruva, Laxmi; Marinov, Anthony et al. (2014) The DNA sensor, cyclic GMP-AMP synthase, is essential for induction of IFN-? during Chlamydia trachomatis infection. J Immunol 193:2394-404
Pokrovskaya, I D; Szwedo, J W; Goodwin, A et al. (2012) Chlamydia trachomatis hijacks intra-Golgi COG complex-dependent vesicle trafficking pathway. Cell Microbiol 14:656-68
Nagarajan, Uma M; Sikes, James D; Yeruva, Laxmi et al. (2012) Significant role of IL-1 signaling, but limited role of inflammasome activation, in oviduct pathology during Chlamydia muridarum genital infection. J Immunol 188:2866-75
Prantner, Daniel; Sikes, James D; Hennings, Leah et al. (2011) Interferon regulatory transcription factor 3 protects mice from uterine horn pathology during Chlamydia muridarum genital infection. Infect Immun 79:3922-33
Nagarajan, Uma (2011) Induction and function of IFN? during viral and bacterial infection. Crit Rev Immunol 31:459-74
Nagarajan, Uma M; Sikes, James; Prantner, Daniel et al. (2011) MyD88 deficiency leads to decreased NK cell gamma interferon production and T cell recruitment during Chlamydia muridarum genital tract infection, but a predominant Th1 response and enhanced monocytic inflammation are associated with infection resolution. Infect Immun 79:486-98
Prantner, Daniel; Darville, Toni; Nagarajan, Uma M (2010) Stimulator of IFN gene is critical for induction of IFN-beta during Chlamydia muridarum infection. J Immunol 184:2551-60
Rank, Roger G; Lacy, H Marie; Goodwin, Anna et al. (2010) Host chemokine and cytokine response in the endocervix within the first developmental cycle of Chlamydia muridarum. Infect Immun 78:536-44
Prantner, Daniel; Nagarajan, Uma M (2009) Role for the chlamydial type III secretion apparatus in host cytokine expression. Infect Immun 77:76-84

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