The role of neutrophils in the pathogenesis of Salmonella
typhimurium-induced ruminant and human enteritis and diarrhea remains
incompletely understood. To address this question, the in vivo bovine ligated ileal
loop model of non-typhoidal salmonellosis was used in calves with the naturallyoccurring
Bovine Leukocyte Adhesion Deficiency (BLAD) mutation whose
neutrophils are unable to extravasate and infiltrate the extravascular matrix. Data
obtained from BLAD calves were compared to those from genetically normal
calves negative for the BLAD mutation. Morphologic studies showed that the
absence of significant tissue influx of neutrophils in intestine infected by S.
typhimurium resulted in less tissue damage, reduced luminal fluid accumulation,
and increased bacterial invasion compared to regular calves. Study of gene
expression profile of cytokines by quantitative Real-Time PCR (qRTPCR)
revealed that the massive tissue influx of neutrophils during acute infection is
mainly driven by the CXC chemokine GRO- α especially in the last stages of acute infection and to a lesser extent, IL-8. In contrast, the pro-inflammatory
cytokines IL-1 β and TNF- α were not significantly correlated with the presence or
absence of tissue neutrophils.
The precise in situ localization of gene expression of these major
cytokines and chemokines was investigated by qRTCPR from specific groups of
intestinal cells captured by Laser Capture Microdissection in S. typhimuriuminfected
ileal loops from BLAD animals. Our data confirmed that gene expression
of IL-8, GRO- α, and IL-1 β was predominantly localized to enterocytes of crypts
with less expression in enterocytes of villi tips and cells that form the domed villi
were not an important source of TNF- α gene expression. Microarray technology
was used to determine the global transcriptional profile of bovine intestinal loops
inoculated with S. typhimurium. The host samples were hybridized on a 13K
bovine-specific oligoarray and microarray data was analyzed using a suite of
gene expression analysis and modeling tools. Analysis of our data revealed that
the tissue influx of neutrophils in ileal loops greatly influenced the host gene
expression. Major differences in gene expression in relevant fields of Salmonella
research including inflammation and immune response, Toll-like receptor
signaling, cytokine profiles, apoptosis, and intracellular defense against infection
are discussed.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2607 |
| Date | 15 May 2009 |
| Creators | Nunes, Jairo Santos |
| Contributors | Adams, Leslie G. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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