# Single-nucleus transcriptomics illuminates sex differences during murine Escherichia coli pyelonephritis

## TL;DR

This study uses single-nucleus RNA sequencing to reveal how male and female mice respond differently at the cellular level during kidney infections.

## Contribution

The paper presents the first whole-kidney single-nucleus transcriptomic dataset from infected mice, revealing sex-specific responses.

## Key findings

- Female mice showed limited cell-type responses with strong upregulation of pro-inflammatory genes.
- Male mice exhibited injury-related pathways even without infection and responded to infection across more cell types.
- Sex differences in transcriptional responses extend beyond cells directly interacting with bacteria.

## Abstract

There are profound sex differences in the prevalence and outcomes of urinary tract infections (UTI). While females comprise the majority of infections, males exhibit higher morbidity and mortality with upper-tract UTI. Correspondingly, preclinical modeling has demonstrated that male and androgen-exposed female mice are highly susceptible to severe high-titer pyelonephritis, a phenotype observed in < 20% of females. We subjected kidneys from female, male, and androgen-exposed female C3H/HeN mice exhibiting high-titer pyelonephritis and PBS-exposed control mice to single-nucleus RNA sequencing, creating, to our knowledge, the first whole-kidney single-nucleus transcriptomic dataset reflecting an infected state. We differentiated healthy cell populations from those affected during UTI and showed sex-discrepant responses that extended to kidney cell types beyond those directly interacting with bacteria. The female response to UTI comprised a more limited range of cell types exhibiting significant upregulation of genes within KEGG pathways and transcription factor regulons related to pro-inflammatory processes. Meanwhile, males evidenced predisposition to injury pathways even with control (saline) inoculation and responded to UTI with less intensity but across more cell types than females. In total, these data illuminate sex-discrepant transcriptional responses and outcomes in renal infection and enable extended dissection of these responses at the cellular and molecular level.