# Androgen Enhancement of E. coli Hemolysin Toxicity during Pyelonephritis.

> **NIH NIH F31** · WASHINGTON UNIVERSITY · 2024 · $35,482

## Abstract

PROJECT SUMMARY / ABSTRACT
Uropathogenic Escherichia coli (UPEC), the major causative agent of urinary tract infections, can colonize the
bladder (cystitis) and ascend the ureter leading to infection within the kidney (pyelonephritis). Though less
frequent than cystitis, pyelonephritis carries increased health risks, including hypertension, renal abscess
formation, and renal scarring. Nevertheless, the mechanisms of UPEC pathogenesis during pyelonephritis have
remained elusive due to lack of an optimal preclinical infection model. Published work from our group has
established that males exhibit an elevated susceptibility to chronic pyelonephritis and renal abscess formation.
This inherent sex bias in UTI outcomes is androgen dependent, leading us to create new published models of
ascending UTI in androgen-exposed female mice that enable investigation of UPEC virulence strategies within
the kidney.
The UPEC secreted toxin alpha-hemolysin (HlyA) elicits cell lysis and ATP release from various mammalian cell
types in vitro, but was previously shown to be dispensable during UPEC cystitis. Preliminary studies using our
updated mouse model of ascending UTI demonstrated that HlyA is required for optimal UPEC colonization and
associated with severe pathology and renal abscess formation in androgen-exposed hosts. This initial work is
congruent with epidemiologic data showing that ~80% of clinical UPEC isolated from patients with pyelonephritis
are HlyA positive, versus only 40% of cystitis isolates. Purinoreceptors (P2X) are host cell membrane channels
that open upon sensing extracellular ATP and facilitate non-selective passage of small cations. Interestingly, the
P2X4 isotype expressed ubiquitously throughout the renal tubular epithelium, is allosterically activated by direct
interactions with testosterone; modulation of P2X4 function by testosterone increases receptor affinity for ATP,
driving increased ion permeability and subsequent pore conductance. We have found that P2X receptors amplify
HlyA cytotoxicity in vitro. Specifically, exogenous testosterone significantly enhances HlyA-mediated lysis of
renal epithelial cells, and this effect is abolished in the presence of a non-selective P2X inhibitor. Leveraging
updated models of ascending UTI, small-molecule P2X inhibitors, and our in vitro model of renal collecting duct
infection, we will test the central hypothesis that UPEC alpha-hemolysin drives renal pathology during
pyelonephritis, and its activity is augmented by testosterone via enhancement of P2X channel function.
Completion of this work will delineate the contribution of HlyA to UPEC pathogenesis within the kidney, determine
the mechanism which facilitates the sex-biased pathogenic effect of HlyA, and define the contribution of
pharmacologically targetable host P2X4 channels to HlyA toxicity during pyelonephritis.

## Key facts

- **NIH application ID:** 10823500
- **Project number:** 1F31AI176711-01A1
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Hunter W Kuhn
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $35,482
- **Award type:** 1
- **Project period:** 2024-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10823500

## Citation

> US National Institutes of Health, RePORTER application 10823500, Androgen Enhancement of E. coli Hemolysin Toxicity during Pyelonephritis. (1F31AI176711-01A1). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/10823500. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*