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.

Morphologic Design of Silver-Bearing Sugar-Based Polymer Nanoparticles for Uroepithelial Cell Binding and Antimicrobial Delivery.

Platelet-like and cylindrical nanostructures from sugar-based polymers are designed to mimic the aspect ratio of bacteria and achieve uroepithelial cell binding and internalization, thereby improving their potential for local treatment of recurrent urinary tract infections. Polymer nanostructures, derived from amphiphilic block polymers composed of zwitterionic poly(d-glucose carbonate) and semicrystalline poly(l-lactide) segments, were constructed with morphologies that could be tuned to enhance uroepithelial cell binding. These nanoparticles exhibited negligible cytotoxicity, immunotoxicity, and cytokine adsorption, while also offering substantial silver cation loading capacity, extended release, and in vitro antimicrobial activity (as effective as free silver cations) against uropathogenic Escherichia coli. In comparison to spherical analogues, cylindrical and platelet-like nanostructures engaged in significantly higher association with uroepithelial cells, as measured by flow cytometry; despite their larger size, platelet-like nanostructures maintained the capacity for cell internalization. This work establishes initial evidence of degradable platelet-shaped nanostructures as versatile therapeutic carriers for treatment of epithelial infections.

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.

TGFß1 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 TGFß1 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 TGFß1 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 TGFß1 signaling blunted myofibroblast activation. We conclude that renal fibrosis after pyelonephritis is exacerbated by the presence of androgens and involves activation of the TGFß1 signaling cascade, leading to increases in cortical populations of MSC-like cells and the Gli1 + activated myofibroblasts that are responsible for scarring.

Mitochondrial inefficiency in infants born to overweight African-American mothers.

BACKGROUND: Currently 20-35% of pregnant women are obese, posing a major health risk for mother and fetus. It is postulated that an abnormal maternal-fetal nutritional environment leads to adverse metabolic programming, resulting in altered substrate metabolism in the offspring and predisposing to risks of obesity and diabetes later in life. Data indicate that oocytes from overweight animals have abnormal mitochondria. We hypothesized that maternal obesity is associated with altered mitochondrial function in healthy neonatal offspring. METHODS: Overweight and obese (body mass index, (BMI) ≥ 25 kg/m2, n = 14) and lean (BMI < 25 kg/m2, n = 8), African-American pregnant women carrying male fetuses were recruited from the Barnes Jewish Hospital obstetric clinic. Maternal and infant data were extracted from medical records. Infants underwent body composition testing in the first days of life. Circumcision skin was collected for isolation of fibroblasts. Fibroblast cells were evaluated for mitochondrial function, metabolic gene expression, nutrient uptake, and oxidative stress. RESULTS: Skin fibroblasts of infants born to overweight mothers had significantly higher mitochondrial respiration without a concurrent increase in ATP production, indicating mitochondrial inefficiency. These fibroblasts had higher levels of reactive oxygen species and evidence of oxidative stress. Evaluation of gene expression in offspring fibroblasts revealed altered expression of multiple genes involved in fatty acid and glucose metabolism and mitochondrial respiration in infants of overweight mothers. CONCLUSIONS: This study demonstrates altered mitochondrial function and oxidative stress in skin fibroblasts of infants born to overweight mothers. Future studies are needed to determine the long-term impact of this finding on the metabolic health of these children.

High-sucrose-induced maternal obesity disrupts ovarian function and decreases fertility in Drosophila melanogaster.

As the obesity epidemic worsens, the prevalence of maternal obesity is expected to rise. Both high-fat and high-sucrose diets are known to promote maternal obesity and several studies have elucidated the molecular influence of high-fat feeding on female reproduction. However, to date, the molecular impact of a high-sucrose diet on maternal obesity remains to be investigated. Using our previously reported Drosophila high-sucrose maternal obesity model, we sought to determine how excess dietary sucrose impacted the ovary. High-sucrose diet (HSD) fed adult females developed systemic insulin resistance and exhibited an ovarian phenotype characterized by excess accumulation of lipids and cholesterol in the ovary, decreased ovary size, and impaired egg maturation. We also observed decreased expression of antioxidant genes and increased protein carbonylation in the ovaries of HSD females. HSD females laid fewer eggs; however, the overall survival of offspring was unchanged relative to lean control females. Ovaries of HSD females had increased mitochondrial DNA copy number and decreased expression of key mitochondrial regulators, suggestive of an ineffective compensatory response to mitochondrial dysfunction. Mitochondrial alterations were also observed in male offspring of obese females. This study demonstrates that high-sucrose-induced maternal obesity promotes insulin resistance, while disrupting ovarian metabolism and function.