| Abstract |
Urinary tract infections are one of the most common bacterial infections,
historically implicating Escherichia coli as the causative pathogen.
However, it is now known that there are a variety of bacteria that exist
within the urinary tract, acting as either beneficial uroprotectives or
opportunistic uropathogens. Furthermore, there are significant gaps in our
understanding as to how these bacteria interact with the urothelium and
what role each plays in maintaining or disrupting homeostasis. Research
has shown that Toll-like receptor 4 (TLR4) signaling and Nod-like receptor
protein 3 play a role in inflammasome activation during infection,
triggering caspase-1 activation and inducing release of pyroptotic-
inducing proteins and inflammatory cytokines. However, little is known
about how this inflammatory process is induced in the urinary tract.
Urothelial cells are constantly exposed to the passage of urine and have
developed an innate immune response to combat potential pathogens in urine.
These cells express specific pattern recognition receptors (PRRs) to sense
pathogen-associated molecular patterns (PAMPs) and damage-associated
molecular patterns (DAMPs) from neighboring cells. These signals can
trigger the formation of the inflammasome complex and activate caspase-1.
Measuring this transient inflammatory response can be difficult, as
various techniques such as ELISA or Western blotting have limitations. The
purpose of this study is to develop a reporter model to screen for caspase-
1 activation and inflammatory pathways in the urinary tract in response to
urinary microbes. Using a human urothelial cell line (hURO18H7) transduced
with a caspase-1 biosensor with a circularly permuted luciferase
construct, a viable reporter line was established and used for infection
with urinary isolates. Preliminary results have shown increased luciferase
activity in response to uropathogenic bacteria such as E. coli, compared
to uroprotective bacteria such as members of certain Lactobacillus species.
Using a human cell line model expressing this biosensor, we can track
inflammatory responses induced by a wide array of suspected uropathogenic
or uroprotective bacteria, elucidating the interactions between the
protective layer of the urinary system and the bacteria that it harbors.
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