Androgen exposure potentiates formation of intratubular communities and renal abscesses by Escherichia coli

Analysing the influence of dapagliflozin on urinary tract infection vulnerability and kidney injury in mice infected with uropathogenic Escherichia coli

AIM

Sodium-glucose co-transporter-2 (SGLT2) inhibitors have revolutionized clinical medicine, but their association with urinary tract infection (UTI) risk remains debated. This study investigates the influence of dapagliflozin on UTI outcomes, focusing on kidney injury.

MATERIALS AND METHODS

Female non-diabetic C57BL/6J and C3H/HeOuJ mice, along with diabetic db/db mice, were orally administered dapagliflozin (1 mg/kg or 10 mg/kg) for 7 days before transurethral uropathogenic Escherichia coli (UPEC) infection. Mice were killed either 24 h after UTI or after six additional days of dapagliflozin treatment. UPEC titers were enumerated, and kidney histopathology, injury, fibrosis and function were assessed.

RESULTS

Vehicle- and dapagliflozin-treated C57BL/6J mice exhibited similar urine and bladder UPEC titers, with minimal kidney burden 24 h after UTI. In C3H/HeOuJ mice, UPEC burden was comparable in vehicle- and 1 mg/kg dapagliflozin-treated groups both 24 h and 7 days after UTI. However, C3H/HeOuJ mice receiving 10 mg/kg dapagliflozin had increased UPEC titers in the urine, bladder and kidneys at both endpoints. Kidney injury and fibrosis markers, as well as kidney function, were similar in vehicle and dapagliflozin groups. In diabetic db/db mice receiving dapagliflozin, UPEC strain UTI89 titers were reduced 7 days after UTI compared to vehicle-treated mice, but no difference in UPEC titers was observed when mice were infected with UPEC strain CFT073. Kidney injury and fibrosis markers and kidney function remained similar across treatment groups.

CONCLUSIONS

Dapagliflozin does not consistently influence UTI susceptibility and shows limited impact on kidney injury or fibrosis, suggesting SGLT2 inhibitors have minimal effects on UTI-related kidney complications.

Insulin receptor orchestrates kidney antibacterial defenses

Urinary tract infection (UTI) commonly afflicts people with diabetes. This augmented infection risk is partly due to deregulated insulin receptor (IR) signaling in the kidney collecting duct. The collecting duct is composed of intercalated cells (ICs) and principal cells (PCs). Evidence suggests that ICs contribute to UTI defenses. Here, we interrogate how IR deletion in ICs impacts antibacterial defenses against uropathogenic Escherichia coli. We also explore how IR deletion affects immune responses in neighboring PCs with intact IR expression. To accomplish this objective, we profile the transcriptomes of IC and PC populations enriched from kidneys of wild-type and IC-specific IR knock-out mice that have increased UTI susceptibility. Transcriptomic analysis demonstrates that IR deletion suppresses IC-integrated stress responses and innate immune defenses. To define how IR shapes these immune defenses, we employ murine and human kidney cultures. When challenged with bacteria, murine ICs and human kidney cells with deregulated IR signaling cannot engage central components of the integrated stress response-including activating transcriptional factor 4 (ATF4). Silencing ATF4 impairs NFkB activation and promotes infection. In turn, NFkB silencing augments infection and suppresses antimicrobial peptide expression. In diabetic mice and people with diabetes, collecting duct cells show reduced IR expression, impaired integrated stress response engagement, and compromised immunity. Collectively, these translational data illustrate how IR orchestrates collecting duct antibacterial responses and the communication between ICs and PCs.

Testosterone increases the virulence traits of uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infections (UTIs) in humans. Testosterone negatively impacts UTIs by affecting the immune response, leading to higher susceptibility of chronic cystitis in individuals with elevated testosterone levels, regardless of gender. Current research is mostly focused on how testosterone affects the host response to UPEC, but not so much is known about how testosterone directly affect UPEC virulence. The aim of the present study was to investigate the impact of testosterone exposure on the virulence of UPEC. We found that testosterone directly increases UPEC growth, endotoxin release and biofilm formation. We also found that testosterone-stimulated CFT073 increased colonization and invasion of bladder epithelial cells. Testosterone-stimulated CFT073 also increased the release of IL-1β and LDH from bladder epithelial cells. Additionally, by using a Caenorhabditis elegans survival assay we also showed that testosterone decreased the survival of CFT073 infected C. elegans worms. Taken together, our findings show that testosterone directly increases the virulence traits of UPEC.

Current and emerging strategies to curb antibiotic-resistant urinary tract infections

Rising rates of antibiotic resistance in uropathogenic bacteria compromise patient outcomes and prolong hospital stays. Consequently, new strategies are needed to prevent and control the spread of antibiotic resistance in uropathogenic bacteria. Over the past two decades, sizeable clinical efforts and research advances have changed urinary tract infection (UTI) treatment and prevention strategies to conserve antibiotic use. The emergence of antimicrobial stewardship, policies from national societies, and the development of new antimicrobials have shaped modern UTI practices. Future UTI management practices could be driven by the evolution of antimicrobial stewardship, improved and readily available diagnostics, and an improved understanding of how the microbiome affects UTI. Forthcoming UTI treatment and prevention strategies could employ novel bactericidal compounds, combinations of new and classic antimicrobials that enhance bacterial killing, medications that prevent bacterial attachment to uroepithelial cells, repurposing drugs, and vaccines to curtail the rising rates of antibiotic resistance in uropathogenic bacteria and improve outcomes in people with UTI.

Insulin receptor signaling engages bladder urothelial defenses that limit urinary tract infection

Urinary tract infections (UTIs) commonly afflict people with diabetes. To better understand the mechanisms that predispose diabetics to UTIs, we employ diabetic mouse models and altered insulin signaling to show that insulin receptor (IR) shapes UTI defenses. Our findings are validated in human biosamples. We report that diabetic mice have suppressed IR expression and are more susceptible to UTIs caused by uropathogenic Escherichia coli (UPEC). Systemic IR inhibition increases UPEC susceptibility, while IR activation reduces UTIs. Localized IR deletion in bladder urothelium promotes UTI by increasing barrier permeability and suppressing antimicrobial peptides. Mechanistically, IR deletion reduces nuclear factor κB (NF-κB)-dependent programming that co-regulates urothelial tight junction integrity and antimicrobial peptides. Exfoliated urothelial cells or urine samples from diabetic youths show suppressed expression of IR, barrier genes, and antimicrobial peptides. These observations demonstrate that urothelial insulin signaling has a role in UTI prevention and link IR to urothelial barrier maintenance and antimicrobial peptide expression.

Androgen exposure impairs neutrophil maturation and function within the infected kidney

Urinary tract infections (UTIs) in men are uncommon yet carry an increased risk for severe pyelonephritis and other complications. In models of Escherichia coli UTI, C3H/HeN mice develop high-titer pyelonephritis (most with renal abscesses) in a testosterone-dependent manner, but the mechanisms underlying this phenotype are unknown. Here, using female mouse models, we show that androgen exposure impairs neutrophil maturation in the upper and lower urinary tract, compounded by a reduction of neutrophil function within the infected kidney, enabling persistent high-titer infection and promoting abscess formation. Following intravesical inoculation with uropathogenic E. coli (UPEC), kidneys of androgen-exposed C3H mice showed delayed local pro-inflammatory cytokine responses while robustly recruiting neutrophils. These were enriched for an end-organ-specific population of aged but immature neutrophils (CD49d+, CD101-). Compared to their mature counterparts, these aged immature kidney neutrophils exhibited reduced function in vitro, including impaired degranulation and diminished phagocytic activity, while splenic, bone marrow, and bladder neutrophils did not display these alterations. Furthermore, aged immature neutrophils manifested little phagocytic activity within intratubular UPEC communities in vivo. Experiments with B6 conditional androgen receptor (AR)-deficient mice indicated rescue of the maturation defect when AR was deleted in myeloid cells. We conclude that the recognized enhancement of UTI severity by androgens is attributable, at least in part, to local impairment of neutrophil maturation in the urinary tract (largely via cell-intrinsic AR signaling) and a kidney-specific reduction in neutrophil antimicrobial capacity.IMPORTANCEAlthough urinary tract infections (UTIs) predominantly occur in women, male UTIs carry an increased risk of morbidity and mortality. Pyelonephritis in androgen-exposed mice features robust neutrophil recruitment and abscess formation, while bacterial load remains consistently high. Here, we demonstrate that during UTI, neutrophils infiltrating the urinary tract of androgen-exposed mice exhibit reduced maturation, and those that have infiltrated the kidney have reduced phagocytic and degranulation functions, limiting their ability to effectively control infection. This work helps to elucidate mechanisms by which androgens enhance UTI susceptibility and severity, illuminating why male patients may be predisposed to severe outcomes of pyelonephritis.

Uropathogen and host responses in pyelonephritis

Urinary tract infections (UTIs) are among the most common bacterial infections seen in clinical practice. The ascent of UTI-causing pathogens to the kidneys results in pyelonephritis, which can trigger kidney injury, scarring and ultimately impair kidney function. Despite sizable efforts to understand how infections develop or are cleared in the bladder, our appreciation of the mechanisms by which infections develop, progress or are eradicated in the kidney is limited. The identification of virulence factors that are produced by uropathogenic Escherichia coli to promote pyelonephritis have begun to fill this knowledge gap, as have insights into the mechanisms by which kidney tubular epithelial cells oppose uropathogenic E. coli infection to prevent or eradicate UTIs. Emerging data also illustrate how specific cellular immune responses eradicate infection whereas other immune cell populations promote kidney injury. Insights into the mechanisms by which uropathogenic E. coli circumvent host immune defences or antibiotic therapy to cause pyelonephritis is paramount to the development of new prevention and treatment strategies to mitigate pyelonephritis and its associated complications.

Immune defenses in the urinary tract

Recent advances in preclinical modeling of urinary tract infections (UTIs) have enabled the identification of key facets of the host response that influence pathogen clearance and tissue damage. Here, we review new insights into the functions of neutrophils, macrophages, and antimicrobial peptides in innate control of uropathogens and in mammalian infection-related tissue injury and repair. We also discuss novel functions for renal epithelial cells in innate antimicrobial defense. In addition, epigenetic modifications during bacterial cystitis have been implicated in bladder remodeling, conveying susceptibility to recurrent UTI. In total, contemporary work in this arena has better defined host processes that shape UTI susceptibility and severity and might inform the development of novel preventive and therapeutic approaches for acute and recurrent UTI.

Effects of aging on urinary tract epithelial homeostasis and immunity

A global increase in older individuals creates an increasing demand to understand numerous healthcare challenges related to aging. This population is subject to changes in tissue physiology and the immune response network. Older individuals are particularly susceptible to infectious diseases, with one of the most common being urinary tract infections (UTIs). Postmenopausal and older women have the highest risk of recurrent UTIs (rUTIs); however, why rUTIs become more frequent after menopause and during old age is incompletely understood. This increased susceptibility and severity among older individuals may involve functional changes to the immune system with age. Aging also has substantial effects on the epithelium and the immune system that led to impaired protection against pathogens, yet heightened and prolonged inflammation. How the immune system and its responses to infection changes within the bladder mucosa during aging has largely remained poorly understood. In this review, we highlight our understanding of bladder innate and adaptive immunity and the impact of aging and hormones and hormone therapy on bladder epithelial homeostasis and immunity. In particular, we elaborate on how the cellular and molecular immune landscape within the bladder can be altered during aging as aged mice develop bladder tertiary lymphoid tissues (bTLT), which are absent in young mice leading to profound age-associated change to the immune landscape in bladders that might drive the significant increase in UTI susceptibility. Knowledge of host factors that prevent or promote infection can lead to targeted treatment and prevention regimens. This review also identifies unique host factors to consider in the older, female host for improving rUTI treatment and prevention by dissecting the age-associated alteration of the bladder mucosal immune system.

The immune responses to different Uropathogens call individual interventions for bladder infection

Urinary tract infection (UTI) caused by uropathogens is the most common infectious disease and significantly affects all aspects of the quality of life of the patients. However, uropathogens are increasingly becoming antibiotic-resistant, which threatens the only effective treatment option available-antibiotic, resulting in higher medical costs, prolonged hospital stays, and increased mortality. Currently, people are turning their attention to the immune responses, hoping to find effective immunotherapeutic interventions which can be alternatives to the overuse of antibiotic drugs. Bladder infections are caused by the main nine uropathogens and the bladder executes different immune responses depending on the type of uropathogens. It is essential to understand the immune responses to diverse uropathogens in bladder infection for guiding the design and development of immunotherapeutic interventions. This review firstly sorts out and comparatively analyzes the immune responses to the main nine uropathogens in bladder infection, and summarizes their similarities and differences. Based on these immune responses, we innovatively propose that different microbial bladder infections should adopt corresponding immunomodulatory interventions, and the same immunomodulatory intervention can also be applied to diverse microbial infections if they share the same effective therapeutic targets.

Machine perfusion combined with antibiotics prevents donor-derived infections caused by multidrug-resistant bacteria

Donor infection affects organ utilization, especially the infections by multidrug-resistant bacteria, which may have disastrous outcomes. We established a rat model, inoculated with Escherichia coli or carbapenem-resistant Klebsiella pneumoniae (CRKP), to investigate whether hypothermic machine perfusion (HMP), normothermic machine perfusion (NMP), or static cold storage (SCS) combined with antibiotic (AB) could eliminate the bacteria. E. coli or CRKP-infected kidneys were treated with cefoperazone-sulbactam and tigecycline, respectively. The HMP+AB and NMP+AB treatments had significant therapeutic effects on E. coli or CRKP infection compared with the SCS+AB treatment. The bacterial load of CRKP-infected kidneys in the HMP+AB (22 050 ± 2884 CFU/g vs. 1900 ± 400 CFU/g, p = .007) and NMP+AB groups (25 433 ± 2059 CFU/g vs. 500 ± 458 CFU/g, p = .002) were significantly reduced, with no statistically significant difference between both groups. Subsequently, the CRKP-infected kidneys of the HMP+AB and SCS+AB groups were transplanted. The rats in the SCS+AB group were severe infected and euthanized on day 4 post-transplant. By contrast, the rats in the HMP+AB group were in good condition. In conclusion, HMP and NMP combined with AB seems to be efficient approaches to decrease bacterial load of infected kidneys. This might lead to higher utilization rates of donors with active infection.

The impact of biological sex on diseases of the urinary tract

Biological sex, being female or male, broadly influences diverse immune phenotypes, including immune responses to diseases at mucosal surfaces. Sex hormones, sex chromosomes, sexual dimorphism, and gender differences all contribute to how an organism will respond to diseases of the urinary tract, such as bladder infection or cancer. Although the incidence of urinary tract infection is strongly sex biased, rates of infection change over a lifetime in women and men, suggesting that accompanying changes in the levels of sex hormones may play a role in the response to infection. Bladder cancer is also sex biased in that 75% of newly diagnosed patients are men. Bladder cancer development is shaped by contributions from both sex hormones and sex chromosomes, demonstrating that the influence of sex on disease can be complex. With a better understanding of how sex influences disease and immunity, we can envision sex-specific therapies to better treat diseases of the urinary tract and potentially diseases of other mucosal tissues.

A mouse model displays host and bacterial strain differences in Aerococcus urinae urinary tract infection

In recent years, the clinical significance of Aerococcus urinae has been increasingly recognized. A. urinae has been implicated in cases of urinary tract infection (UTI; acute cystitis and pyelonephritis) in both male and female patients, ranging from children to older adults. Aerococcus urinae can also be invasive, causing urosepsis, endocarditis, and musculoskeletal infections. Mechanisms of pathogenesis in A. urinae infections are poorly understood, largely due to the lack of an animal model system. In response to this gap, we developed a model of A. urinae urinary tract infection in mice. We compared A. urinae UTI in female C3H/HeN and C57BL/6 mice and compared four clinical isolates of A. urinae isolated from patients with UTI, urgency urinary incontinence, and overactive bladder. Our data demonstrate that host genetic background modulates A. urinae UTI. Female C57BL/6 female mice rapidly cleared the infection. Female C3H/HeN mice, which have inherent vesicoureteral reflux that flushes urine from the bladder up into the kidneys, were susceptible to prolonged bacteriuria. This result is consistent with the fact that A. urinae infections most frequently occur in patients with underlying urinary tract abnormalities or disorders that make them susceptible to bacterial infection. Unlike uropathogens such as E. coli, which cause infection and inflammation both of the bladder and kidneys in C3H/HeN mice, A. urinae displayed tropism for the kidney, persisting in kidney tissue even after clearance of bacteria from the bladder. Aerococcus urinae strains from different genetic clades displayed varying propensities to cause persistent kidney infection. Aerococcus urinae infected kidneys displayed histological inflammation, neutrophil recruitment and increased pro-inflammatory cytokines. These results set the stage for future research that interrogates host-pathogen interactions between A. urinae and the urinary tract.

Summary:Aerococcus urinae clinical isolates are genetically diverse and display differential capacity to cause UTI in a mouse model. Infection was rapidly cleared from the bladder, but persisted and caused inflammation in the kidney.

Sex Differences in Population Dynamics during Formation of Kidney Bacterial Communities by Uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC), the primary etiologic agent of urinary tract infections (UTIs), encounters a restrictive population bottleneck within the female mammalian bladder. Its genetic diversity is restricted during establishment of cystitis because successful UPEC must invade superficial bladder epithelial cells prior to forming clonal intracellular bacterial communities (IBCs). In this study, we aimed to understand UPEC population dynamics during ascending pyelonephritis, namely, formation of kidney bacterial communities (KBCs) in the renal tubular lumen and nucleation of renal abscesses. We inoculated the bladders of both male and female C3H/HeN mice, a background which features vesicoureteral reflux; we have previously shown that in this model, males develop severe, high-titer pyelonephritis and renal abscesses much more frequently than females. Mice were infected with 40 isogenic, PCR-tagged ("barcoded") UPEC strains, and tags remaining in bladder and kidneys were ascertained at intervals following infection. In contrast to females, males maintained a majority of strains within both the bladder and kidneys throughout the course of infection, indicating only a modest host-imposed bottleneck on overall population diversity during successful renal infection. Moreover, the diverse population in the infected male kidneys obscured any restrictive bottleneck in the male bladder. Finally, using RNA in situ hybridization following mixed infections with isogenic UPEC bearing distinct markers, we found that despite their extracellular location (in the urinary space), KBCs are clonal in origin. This finding indicates that even with bulk reflux of infected bladder urine into the renal pelvis, successful ascension of UPEC to establish the tubular niche is an uncommon event.

Sex effects in pyelonephritis

Urinary tract infections (UTIs) are generally considered a disease of women. However, UTIs affect females throughout the lifespan, and certain male populations (including infants and elderly men) are also susceptible. Epidemiologically, pyelonephritis is more common in women but carries increased morbidity when it does occur in men. Among children, high-grade vesicoureteral reflux is a primary risk factor for upper-tract UTI in both sexes. However, among young infants with UTI, girls are outnumbered by boys; risk factors include posterior urethral valves and lack of circumcision. Recent advances in mouse models of UTI reveal sex differences in innate responses to UTI, which vary somewhat depending on the system used. Moreover, male mice and androgenized female mice suffer worse outcomes in experimental pyelonephritis; evidence suggests that androgen exposure may suppress innate control of infection in the urinary tract, but additional androgen effects, as well as non-hormonal sex effects, may yet be specified. Among other intriguing directions, recent experiments raise the hypothesis that the postnatal testosterone surge that occurs in male infants may represent an additional factor driving the higher incidence of UTI in males under 6 months of age. Ongoing work in contemporary models will further illuminate sex- and sex-hormone-specific effects on UTI pathogenesis and immune responses.

A host receptor enables type 1 pilus-mediated pathogenesis of Escherichia coli pyelonephritis

Type 1 pili have long been considered the major virulence factor enabling colonization of the urinary bladder by uropathogenic Escherichia coli (UPEC). The molecular pathogenesis of pyelonephritis is less well characterized, due to previous limitations in preclinical modeling of kidney infection. Here, we demonstrate in a recently developed mouse model that beyond bladder infection, type 1 pili also are critical for establishment of ascending pyelonephritis. Bacterial mutants lacking the type 1 pilus adhesin (FimH) were unable to establish kidney infection in male C3H/HeN mice. We developed an in vitro model of FimH-dependent UPEC binding to renal collecting duct cells, and performed a CRISPR screen in these cells, identifying desmoglein-2 as a primary renal epithelial receptor for FimH. The mannosylated extracellular domain of human DSG2 bound directly to the lectin domain of FimH in vitro, and introduction of a mutation in the FimH mannose-binding pocket abolished binding to DSG2. In infected C3H/HeN mice, type 1-piliated UPEC and Dsg2 were co-localized within collecting ducts, and administration of mannoside FIM1033, a potent small-molecule inhibitor of FimH, significantly attenuated bacterial loads in pyelonephritis. Our results broaden the biological importance of FimH, specify the first renal FimH receptor, and indicate that FimH-targeted therapeutics will also have application in pyelonephritis.

Urinary tract infections (UTIs) are among the most common bacterial infections in humans. While much has been discovered about how E. coli cause bladder infections, less is known about the host-pathogen interactions that underlie kidney infection (pyelonephritis). We employed recently developed mouse models to show that bacterial surface fibers called type 1 pili, which bear the adhesive protein FimH and are known to mediate E. coli binding to bladder epithelium, are also required for ascending kidney infection. We developed a cell-culture model of bacterial binding to renal collecting duct, then performed a screen using the gene-editing tool CRISPR to identify the first known FimH receptor in the kidney. This epithelial cell-surface protein, desmoglein-2, was shown to directly bind FimH, and we localized this binding to specific extracellular domains of DSG2. Further, we showed that mannosides, small-molecule FimH inhibitors currently in development to treat bladder infection, are also effective in experimental kidney infection. Our study reveals a novel host-pathogen interaction during pyelonephritis and demonstrates how this interaction may be therapeutically targeted.

The role of androgen and its related signals in PCOS

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women at reproductive age. However, the underlying pathogenic mechanisms have not been completely understood. Hyperandrogenism is an important clinic feature in patients with PCOS, suggesting its pathologic role in the development and progression of PCOS. However, the actual role of androgen and the related signals in PCOS and PCOS-related complications have not yet been clarified. In this review, we surveyed the origin and effects of androgen on PCOS and the related complications, highlighted the cellular signals affecting androgen synthesis and summarized the pathological processes caused by hyperandrogenism. Our review well reveals the important mechanisms referring the pathogenesis of PCOS and provides important clues to the clinic strategies in patients with PCOS.

Testosterone regulates the intracellular bacterial community formation of uropathogenic Escherichia coli in prostate cells via STAT3

BACKGROUND

UPEC can internalize clonally in prostate to form biofilm-like intracellular bacterial communities (IBCs) for recurrent or chronic infection. We previously indicated that the exposure of prostate cells to testosterone could suppress UPEC invasion and their persistent survival within cells by effectively inhibiting the JAK/STAT1 signaling pathway. However, the regulatory mechanism by which testosterone affects UPEC-induced prostatitis via STAT3, another latent transcription factor signaling pathway is still unclear. The present study aimed to clarify the role of STAT3 in the process of UPEC-induced inflammation and colonization in prostate epithelial cells.

METHODS

The effects of testosterone-mediated inhibition were compared between the prostatitis by different UPEC strains (CFT073 and J96) through the specific GFP-UPEC-infected prostate cell model. Fluorescence microscopy was used for UPEC IBCs detection and quantifying, and Flow cytometry, RT-PCR and western blotting were used for analyzing related gene and protein expressions. Pretreatment of JAK and STAT3 inhibitors were also applied to verify the regulation of transduction pathway in testosterone-mediated anti-UPEC infection.

RESULTS

This study revealed that testosterone effectively suppresses UPEC infection and IBC formation in prostate cells through the JAK/STAT3 pathway. The results show that CFT073 and J96 UPEC infection rates and colony numbers were dose-dependently reduced in RWPE-1 cells pretreated with 5 and 20 μg/mL testosterone at 0 and 24 h post-infection. Further, testosterone reduced the amounts of UPEC infecting and surviving within the prostate cells, as well as suppressed the size of IBCs formed. We demonstrated that pretreating testosterone effectively inhibited UPEC infection along with dose-dependent suppression of STAT3 and the phosphorylated-STAT3 expression in prostate cells, especially in 24 h J96 UPEC infected groups. The STAT inhibitor, SOCS3 also up-regulated at the same time. In addition, we pretreated the JAK1 or STAT3 inhibitor with testosterone to block the signaling transduction before CFT073 and J96 UPEC infection, and found the significant restoring in both the sizes of IBCs and bacterial numbers in RWPE-1 cells. Therefore, our results suggest that the suppression of STAT3 by testosterone treatment attenuate UPEC growing within IBCs and interfere with their infection to prostate cells.

CONCLUSIONS

Overall, our study demonstrates that testosterone suppresses the initial infection of prostate epithelial cells by UPEC and reduces the survival of UPEC within IBCs after infection. These results indicate a critical role for STAT3 in facilitating UPEC infection and persistence, and its participation in driving testosterone-suppressive responses in prostate epithelial cells. In conclusion, this study suggests that testosterone may be beneficial in treating clinically recurrent UPEC infections and, thus, the persistent recurrence of prostatic inflammation.

Androgen-Influenced Polarization of Activin A-Producing Macrophages Accompanies Post-pyelonephritic Renal Scarring

Ascending bacterial pyelonephritis, a form of urinary tract infection (UTI) that can result in hospitalization, sepsis, and other complications, occurs in ~250,000 US patients annually; uropathogenic Escherichia coli (UPEC) cause a large majority of these infections. Although UTIs are primarily a disease of women, acute pyelonephritis in males is associated with increased mortality and morbidity, including renal scarring, and end-stage renal disease. Preclinical models of UTI have only recently allowed investigation of sex and sex-hormone effects on pathogenesis. We previously demonstrated that renal scarring after experimental UPEC pyelonephritis is augmented by androgen exposure; testosterone exposure increases both the severity of pyelonephritis and the degree of renal scarring in both male and female mice. Activin A is an important driver of scarring in non-infectious renal injury, as well as a mediator of macrophage polarization. In this work, we investigated how androgen exposure influences immune cell recruitment to the UPEC-infected kidney and how cell-specific activin A production affects post-pyelonephritic scar formation. Compared with vehicle-treated females, androgenized mice exhibited reduced bacterial clearance from the kidney, despite robust myeloid cell recruitment that continued to increase as infection progressed. Infected kidneys from androgenized mice harbored more alternatively activated (M2) macrophages than vehicle-treated mice, reflecting an earlier shift from a pro-inflammatory (M1) phenotype. Androgen exposure also led to a sharp increase in activin A-producing myeloid cells in the infected kidney, as well as decreased levels of follistatin (which normally antagonizes activin action). As a result, infection in androgenized mice featured prolonged polarization of macrophages toward a pro-fibrotic M2a phenotype, accompanied by an increase in M2a-associated cytokines. These data indicate that androgen enhancement of UTI severity and resulting scar formation is related to augmented local activin A production and corresponding promotion of M2a macrophage polarization.

The immune response to infection in the bladder

The bladder is continuously protected by passive defences such as a mucus layer, antimicrobial peptides and secretory immunoglobulins; however, these defences are occasionally overcome by invading bacteria that can induce a strong host inflammatory response in the bladder. The urothelium and resident immune cells produce additional defence molecules, cytokines and chemokines, which recruit inflammatory cells to the infected tissue. Resident and recruited immune cells act together to eradicate bacteria from the bladder and to develop lasting immune memory against infection. However, urinary tract infection (UTI) is commonly recurrent, suggesting that the induction of a memory response in the bladder is inadequate to prevent reinfection. Additionally, infection seems to induce long-lasting changes in the urothelium, which can render the tissue more susceptible to future infection. The innate immune response is well-studied in the field of UTI, but considerably less is known about how adaptive immunity develops and how repair mechanisms restore bladder homeostasis following infection. Furthermore, data demonstrate that sex-based differences in immunity affect resolution and infection can lead to tissue remodelling in the bladder following resolution of UTI. To combat the rise in antimicrobial resistance, innovative therapeutic approaches to bladder infection are currently in development. Improving our understanding of how the bladder responds to infection will support the development of improved treatments for UTI, particularly for those at risk of recurrent infection.

TGFβ1 orchestrates renal fibrosis following Escherichia coli pyelonephritis

Renal scarring after pyelonephritis is linked to long-term health risks for hypertension and chronic kidney disease. Androgen exposure increases susceptibility to, and severity of, uropathogenic Escherichia coli (UPEC) pyelonephritis and resultant scarring in both male and female mice, while anti-androgen therapy is protective against severe urinary tract infection (UTI) in these models. This work employed androgenized female C57BL/6 mice to elucidate the molecular mechanisms of post-infectious renal fibrosis and to determine how these pathways are altered by the presence of androgens. We found that elevated circulating testosterone levels primed the kidney for fibrosis by increasing local production of TGFβ1 before the initiation of UTI, altering the ratio of transcription factors Smad2 and Smad3 and increasing the presence of mesenchymal stem cell (MSC)-like cells and Gli1 + activated myofibroblasts, the cells primarily responsible for deposition of scar components. Increased production of TGFβ1 and aberrations in Smad2:Smad3 were maintained throughout the course of infection in the presence of androgen, correlating with renal scarring that was not observed in non-androgenized female mice. Pharmacologic inhibition of TGFβ1 signaling blunted myofibroblast activation. We conclude that renal fibrosis after pyelonephritis is exacerbated by the presence of androgens and involves activation of the TGFβ1 signaling cascade, leading to increases in cortical populations of MSC-like cells and the Gli1 + activated myofibroblasts that are responsible for scarring.

Pathophysiology, Treatment, and Prevention of Catheter-Associated Urinary Tract Infection

Urinary tract infections (UTIs) are among the most common microbial infections in humans and represent a substantial burden on the health care system. UTIs can be uncomplicated, as when affecting healthy individuals, or complicated, when affecting individuals with compromised urodynamics and/or host defenses, such as those with a urinary catheter. There are clear differences between uncomplicated UTI and catheter-associated UTI (CAUTI) in clinical manifestations, causative organisms, and pathophysiology. Therefore, uncomplicated UTI and CAUTI cannot be approached similarly, or the risk of complications and treatment failure may increase. It is imperative to understand the key aspects of each condition to develop successful treatment options and improve patient outcomes. Here, we will review the epidemiology, pathogen prevalence, differential mechanisms used by uropathogens, and treatment and prevention of uncomplicated UTI and CAUTI.