Recombinant Fc fusions for treatment of uropathogenic E. coli

Urinary tract infections (UTIs) are among the most common bacterial infections, affecting 150 million
people worldwide each year. In the USA, community-acquired UTIs account for about 11 million cases each year
that cost the U.S. public health budget $5 billion annually. Uropathogenic Escherichia coli (UPEC) accounts for
up to 80% of UTIs. While UTIs are currently treated with antibiotics, the frequency of multi-drug resistance is
increasing, portending a future of untreatable UTIs. A promising alternative to antibiotics is to directly target
bacterial virulence factors that are critical for bacterial adhesion to and invasion of uroepithelial cells. These
virulence factors include the bacterial adhesin FimH, expressed by the majority of uropathogenic E. coli strains.
FimH binds to a specific glycoform, oligomannose-3, carried by an abundant membrane glycoprotein on
uroepithelial cells.We have produced a recombinant protein targeting FimH. It is a molecular fusion of human protein,
dipeptidyl peptidase 4 (DPP4) with IgG1 Fc (DPP4-Fc), carries eight mannose-containing N-glycans and binds
in a mannose-specific manner to FimH. We have shown that that DPP4-Fc promotes killing of uropathogenic E.
coli by complement. The purpose of this research project is to demonstrate the ability of DPP4-Fc to promote
activation of complement on the surface of antibiotic-resistant uropathogenic E. coli thereby leading to increased
bacterial killing by complement and polymorphonuclear cells (PMNs).We will produce three new variants of DPP4-Fc carrying different numbers of N-glycans per monomer and
different glycoforms. We will modify the Fc of DPP4-Fc to improve C1q binding and thus increase activation of
the classical complement pathway. Modifications will include point mutations and replacement of IgG1 Fc with
IgG3 Fc. We will also produce a negative control DPP4-Fc in which the Fc contains two point mutations that
abrogate C1q binding and thus has no opsonizing activity. We will test all these new DPP4-Fc variants for their
ability to: i) bind to uropathogenic E.coli, Enterobacter and Klebsiella pneumonia strains, ii) inhibit bacterial
attachment to urothelial cells, iii) promote serum mediated killing of bacteria and iv) promote opsonophagocytosis
of bacteria.We expect that DPP4-Fc can be developed into a novel treatment for uropathogenic E. coli, Enterobacter
and Klebsiella infections. Future research projects will test the activity of these molecules in animal models and
later in human clinical trials.Urinary tract infections are among the most common bacterial infections, of which up to 80%
are caused by E. coli. At increasing frequency, these pathogens are resistant to most or even all
last line antibiotics. We have devised a hybrid protein combining a protein fragment that can
block bacterial cell attachment with an immune defense-activating portion of human antibody.
We will demonstrate the ability of this hybrid to facilitate killing multi-drug resistant
uropathogenic E. coli, Enterobacter and Klebsiella pneumoniae.