Defense Date

2009

Document Type

Thesis

Degree Name

Master of Science

Department

Microbiology & Immunology

First Advisor

Paul Fawcett

Abstract

Innate immunity depends on pattern recognition receptors, which recognize pathogen associated molecular patterns (PAMPS), such as Toll-like receptor 4 (TLR4), which detects the gram-negative bacterial toxin, lipopolysaccharide. Engagement of TLR4 by LPS sets off a cascade ending in the activation of pro-inflammatory cytokines and interferon-β (IFN-β) which alerts the host to the infection. However, these responses can be mal-adaptive, especially in the context of bacterial sepsis, where a "cytokine storm" results in death of the host. Pharmacological modulation of these responses may therefore be a promising treatment modality. Inhibition of classic pro-inflammatory cytokines such as IL-1β and TNF-α has been the (largely unfruitful) focus of much research. However it has recently emerged that mice with defects in type I IFN signaling are also substantially resistant to challenge with endotoxin. We therefore wish to investigate pharmacological inhibition of IFN signaling as a potential means to control sepsis. We analyzed the effects of Trichostatin A (TSA) and Suberoylanilide hydroxamic acid (SAHA) (both broad spectrum HDAC inhibitors) and ST-2-92 (HDAC6 specific inhibitor) on IFN regulation and endotoxic shock. We created an in vivo mouse model for this treatment with TSA and SAHA (which are well tolerated in mouse and human) to look for possible alteration in the survival rate following endotoxin challenge. We as well as others found that treatment with SAHA (50mg/kg) significantly improves survival rate. We also characterized in-vitro modulation of IFN responses through SAHA by mouse DNA microarray. We noticed a decreased expression of many innate immune regulated genes in the SAHA and LPS treated condition compared to the LPS treatment alone. Additionally we observed a decrease in protein levels of IFN-β IL-1β, IL-6, IL-12p40, RANTES and TNF-α in cell culture supernatants treated with SAHA or ST-2-92 and LPS compared to LPS only treatment. These results show the ability of broad spectrum HDACi through SAHA to increase mouse survival following LPS challenge as well as modulate the induction of innate immune responsive genes in vitro. Furthermore we have shown that HDAC specific inhibition through ST-2-92 can decrease pro-inflammatory transcript as well as protein levels.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

December 2009

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