Biology subjects

Zulk, J. J.

Publications and source records attributed to Zulk, J. J..

8 recordsLinked to original sources

bioRxiv2026

Type 2 diabetes mellitus exacerbates vaginal group B Streptococcus colonization via impaired mucosal cytokine response

Type 2 diabetes mellitus (T2D) is a metabolic disorder that confers increased risk of microbial infections, including those caused by the opportunistic pathogen group B Streptococcus (GBS). Asymptomatic GBS carriage in the vaginal tract is a notable reservoir for infection, but the impact of T2D on the vaginal mucosa and GBS colonization is not fully understood. We employed a diet-induced mouse model of T2D paired with vaginal GBS colonization to investigate the impact of diabetes on glucose availability, vaginal microbiome composition, and vaginal cytokine profiles at baseline and in response to GBS. We observed enhanced susceptibility of diabetic mice to GBS vaginal colonization and reproductive tract dissemination. Despite experiencing hyperglycemia, diabetic mice did not exhibit elevated glucose in the reproductive tract. Regarding the vaginal microbiota, diabetic mice had minimal compositional differences with decreased Mammaliicoccus being the only significant taxonomic variance. Vaginal cytokine profiling revealed consistently depressed cytokines in diabetic mice, beginning with KC at baseline and expanding to an array of eight pro-inflammatory cytokines post-GBS infection. Pairing cytokine observations with GBS colonization outcomes revealed a correlation between delayed vaginal IL-1 induction and persistent vaginal GBS, suggesting that vaginal cytokine deficiency may contribute to diabetic GBS vaginal colonization. Supplementation with intravaginal rIL-1 was sufficient to resolve GBS burden differences between diabetic mice and non-diabetic controls, confirming that deficient vaginal cytokine responses contribute to diabetic GBS vaginal persistence. These findings advance our understanding of diabetic vaginal mucosal susceptibility to pathogens and support the potential for immunological intervention in the susceptible diabetic population. IMPORTANCEPeople with T2D are more susceptible to microbial infections, but there is limited understanding of the mechanisms that drive this vulnerability. One possibility is that T2D enhances colonization of opportunistic pathogens, like GBS, in mucosal reservoirs as a precursor to infection. In this study, we used a diabetic mouse model to test whether diabetes alters the vaginal mucosa to promote GBS colonization. We found that increased vaginal GBS colonization in diabetic mice was not linked to tissue glucose availability or changes to the vaginal microbiome, but instead was associated with impaired vaginal immune responses. These findings provide a foundation for translational approaches to reduce GBS persistence and dissemination in at-risk individuals.

microbiology↗

bioRxiv2025

Bacteriophage-mediated reduction of uropathogenic E. coli from the urogenital epithelium

Urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), affect millions annually. UPEC gains access to the urinary tract through mucosal reservoirs including the vaginal tract. With rising antibiotic resistance and frequent recurrence, alternative non-antibiotic strategies like bacteriophage (phage) therapy are gaining attention. We explored the potential of a lytic phage, {Phi}HP3, as well as a phage cocktail to decolonize UPEC from the urogenital tract using in vitro and in vivo models. Phage significantly inhibited UPEC growth in both bacteriologic medium and simulated vaginal fluid. Pretreatment of human vaginal epithelial cells (VK2/E6E7) and bladder carcinoma cells (HTB-9) with phage reduced adhesion and invasion of UPEC compared with controls. Phage treatment was further able to reduce intracellular UPEC in VK2 cells. Notably, phage pretreatment did not impact phage resistant UPEC strains, indicating that phage lysis was the primary driver of phenotypes. Live confocal microscopy confirmed interaction of phage particles with UPEC and with both epithelial cell lines. In vivo, daily intravaginal {Phi}HP3 administration in humanized microbiota mice significantly reduced vaginal UPEC burden after 4 days. Treatment with a phage cocktail also reduced vaginal and cervical tissue burdens by day 7 post-treatment. UPEC dissemination was observed to uterine and kidney tissues, but burdens were not different between phage and mock-treated groups. In conclusion, we demonstrate that phage and phage cocktails can modestly reduce UPEC urogenital colonization, highlighting the potential of phage therapy as a viable treatment option for UTI prevention. IMPORTANCEUrinary tract infections (UTIs) are among the most common infections worldwide, with millions of cases each year. Due to frequent recurrence and increasing antibiotic resistance, UTIs are becoming more difficult to treat, and non-antibiotic prevention options remain limited. The bacteria responsible for UTIs, such as uropathogenic E. coli (UPEC), often colonize other body sites, such as the intestines or vagina, before causing infection. In this study, we investigated whether bacteriophage (phage), viruses that infect bacteria, could reduce UPEC colonization. We found that phage treatment decreased UPEC adherence to vaginal and bladder cell lines, but only modestly reduced UPEC vaginal colonization in a mouse model. These findings suggest that phages may offer a potential strategy for UTI prevention, though further research is needed to optimize their therapeutic use.

microbiology↗

bioRxiv2025

Human bladder organoids model urinary tract infection and bacteriophage therapy

Urinary tract infections (UTIs), primarily caused by uropathogenic Escherichia coli (UPEC), are among the most common antibiotic-resistant infections. Despite this, currently available preclinical UTI models lack the breadth of morphotypic and heterogenous cell populations of the human bladder, impairing the development of novel therapies. To address these limitations, we developed human bladder organoids derived from the bladder stem cells of multiple healthy donors which recapitulate cellular diversity of the urothelium. Using bulk and single cell RNA-sequencing, we characterized organoid responses to UPEC and phage exposure individually and in combination to model phage therapy. Although phage minimally affected the uroepithelium in the absence of infection, during UTI, phage treatment reduced bacterial burdens and dampened inflammatory responses and barrier disruption. Collectively, our findings highlight human bladder organoids as a tool for capturing conserved and individual-specific uroepithelial responses to infection while also providing preclinical efficacy and safety testing for therapeutic development.

microbiology↗

bioRxiv2024

Distinct maternofetal immune signatures delineate preterm birth onset following urinary tract infection

Preterm birth is the leading cause of infant mortality resulting in over one million neonatal deaths annually. Maternal urinary tract infection (UTI) during pregnancy increases risk for preterm birth; however, biological processes mediating UTI-associated preterm birth are not well-described. We established a murine maternal UTI model in which challenge with uropathogenic E. coli resulted in preterm birth in about half of dams. Dams experiencing preterm birth displayed excessive bladder inflammation and altered uteroplacental T cell polarization compared to non-laboring infected dams, with no differences in bacterial burdens. Additional factors associated with preterm birth included higher proportions of male fetuses and lower maternal serum IL-10. Furthermore, exogenous maternal IL-10 treatment absolved UTI-associated preterm birth but contributed to fetal growth restriction in this model. Using urine samples from a cohort of human pregnancies with or without UTI, we correlated urinary cytokines with birth outcomes and urine culture status. These analyses yielded a non-invasive, highly predictive three-model system for evaluating preterm birth risk implicating cytokines IL-10, IL-15, IL-1{beta}, and IL-1RA. Our unique bimodal murine model coupled with patient samples provides a platform to investigate immunological and microbial factors governing UTI-associated preterm birth, revealing novel therapeutic opportunities to predict or prevent preterm birth.

immunology↗

bioRxiv2023

Gestational diabetes augments group B Streptococcus perinatal infection through disruptions in maternal immunity and the vaginal microbiota

Group B Streptococcus (GBS) is a pervasive perinatal pathogen, yet factors driving GBS dissemination in utero are poorly defined. Gestational diabetes mellitus (GDM), a complication marked by dysregulated immunity and maternal microbial dysbiosis, increases risk for GBS perinatal disease. We interrogated host-pathogen dynamics in a novel murine GDM model of GBS colonization and perinatal transmission. GDM mice had greater GBS in utero dissemination and subsequently worse neonatal outcomes. Dual-RNA sequencing revealed differential GBS adaptation to the GDM reproductive tract, including a putative glycosyltransferase (yfhO), and altered host responses. GDM disruption of immunity included reduced uterine natural killer cell activation, impaired recruitment to placentae, and altered vaginal cytokines. Lastly, we observed distinct vaginal microbial taxa associated with GDM status and GBS invasive disease status. Our translational model of GBS perinatal transmission in GDM hosts recapitulates several clinical aspects and enables discovery of host and bacterial drivers of GBS perinatal disease.

microbiology↗

bioRxiv2023

Progress toward the development of an effective vaccine for Extraintestinal pathogenic E. coli (ExPEC): The application of the multiple-protein subunits vaccine in different murine models

Extraintestinal pathogenic E. coli (ExPEC) is the primary Gram-negative bacterial pathogen, and the leading cause of life-threatening sepsis and urinary tract infections (UTI) in adults. The emergence and increasing prevalence of multidrug-resistance (MDR) ExPEC strains have led to considerable treatment failures, increased hospitalization rates, morbidity, and mortality. A prophylactic vaccine against ExPEC has the potential to reduce severe infection-related morbidity and mortality, helping to address the escalating antimicrobial resistance (AMR) crisis worldwide. The -hemolysin (HlyA) is a critical, frequently detected secreted cytotoxic virulence factor in ExPEC, with HlyA-expressing ExPEC strains correlating with increased severity and infection dissemination in clinical levels. In this study, we assessed the protective efficacy of pro-HlyA (the inactive and immature precursor of HlyA) and Dual-Hit (a combination of pro-HlyA and SinH-3, the previously reported immunoglobulin-like domain-3 of the invasin-like autotransporter protein SinH), as ExPEC vaccine candidates. We demonstrated that immunizing mice with pro-HlyA or Dual-Hit significantly reduced bacterial burden and increased survival rates against pandemic ExPEC sequence type strains, ST73 (CFT073) and ST95 (UTI89), in the model of bacteremia and mortality. Both pro-HlyA or Dual-Hit immunizations also provided significant protection against UTI89 colonization in the bladder in the murine UTI model. Furthermore, vaccination with Dual-Hit provided enduring and robust protection against a mixture of ten typical high-virulent sequence types of ExPEC strains, resulting in a promising broad-spectrum vaccine candidate. These findings suggest that pro-HlyA and Dual-Hit might serve as highly effective vaccine targets and highlight the potential of these vaccine candidates for further development and evaluation.

microbiology↗

bioRxiv2023

Vaginal microbial dynamics and pathogen colonization in a humanized microbiota mouse model

Vaginal microbiota composition is associated with differential risk of urogenital infection. Although vaginal Lactobacillus spp. are thought to confer protection through acidification, bacteriocin production, and immunomodulation, lack of an in vivo model system that closely resembles the human vaginal microbiota remains a prominent barrier to mechanistic discovery. We performed 16S rRNA amplicon sequencing of wildtype C57BL/6J mice, commonly used to study pathogen colonization, and found that the vaginal microbiome composition varies highly both within and between colonies from three distinct vivaria. Because of the strong influence of environmental exposure on vaginal microbiome composition, we assessed whether a humanized microbiota mouse (HMbmice) would model a more human-like vaginal microbiota. Similar to humans and conventional mice, HMbmice vaginal microbiota clustered into five community state types (hmCST). Uniquely, HMbmice vaginal communities were frequently dominated by Lactobacilli or Enterobacteriaceae. Compared to genetically-matched conventional mice, HMbmice were less susceptible to uterine ascension by urogenital pathobionts group B Streptococcus (GBS) and Prevotella bivia, but no differences were observed with uropathogenic E. coli. Specifically, vaginal Enterobacteriaceae and Lactobacillus were associated with the absence of uterine GBS. Anti-GBS activity of HMbmice vaginal E. coli and L. murinus isolates, representing Enterobacteriaceae and Lactobacillus respectively, were characterized in vitro and in vivo. Although L. murinus reduced GBS growth in vitro, vaginal pre-inoculation with HMbmouse-derived E. coli, but not L. murinus, conferred protection against vaginal GBS burden. Overall, the HMbmice are an improved model to elucidate the role of endogenous microbes in conferring protection against urogenital pathogens. IMPORTANCEAn altered vaginal microbiota, typically with little to no levels of Lactobacillus, is associated with increased susceptibility to urogenital infections, although mechanisms driving this vulnerability are not fully understood. Despite known inhibitory properties of Lactobacillus against urogenital pathogens, clinical studies with Lactobacillus probiotics have shown mixed success. In this study, we characterize the impact of the vaginal microbiota on urogenital pathogen colonization using a humanized microbiota mouse model that more closely mimics the human vaginal microbiota. We found several vaginal bacterial taxa that correlated with reduced pathogen levels but showed discordant effects in pathogen inhibition between in vitro and in vivo assays. We propose that this humanized microbiota mouse platform is an improved model to describe the role of the vaginal microbiota in protection against urogenital pathogens. Furthermore, this model will be useful in testing efficacy of new probiotic strategies in the complex vaginal environment.

microbiology↗

bioRxiv2021

Phage resistance accompanies reduced fitness of uropathogenic E. coli in the urinary environment

Urinary tract infections (UTIs) are among the most common infections treated worldwide each year and are primarily caused by uropathogenic E. coli (UPEC). Rising rates of antibiotic resistance among uropathogens have spurred consideration of alternative strategies such as bacteriophage (phage) therapy; however, phage-bacterial interactions within the urinary environment are poorly defined. Here, we assess the activity of two phages, HP3 and ES17, against clinical UPEC isolates using in vitro and in vivo models of UTI. In both bacteriologic medium and pooled human urine, we identified phage resistance arising within the first 6-8 hours of coincubation. Whole genome sequencing revealed that UPEC resistant to HP3 and ES17 harbored mutations in genes involved in lipopolysaccharide (LPS) biosynthesis. These mutations coincided with several in vitro phenotypes, including alterations to adherence to and invasion of human bladder epithelial HTB-9 cells, and increased biofilm formation. Interestingly, these phage-resistant UPEC demonstrated reduced growth in pooled human urine, which could be partially rescued by nutrient supplementation, and were more sensitive to several outer membrane targeting antibiotics than parental strains. Additionally, these phage-resistant UPEC were attenuated in a murine UTI model. In total, our findings suggest that while resistance to phages, such as LPS-targeted HP3 and ES17, may readily arise in the urinary environment, phage resistance is accompanied by fitness costs rendering UPEC more susceptible to host immunity or antibiotics. IMPORTANCEUTIs are one of the most common causes of outpatient antibiotic use, and rising antibiotic resistance threatens the ability to control these infections unless alternative treatments are developed. Bacteriophage (phage) therapy is gaining renewed interest, however, much like antibiotics, bacteria can readily become resistant to phage. For successful UTI treatment, we must predict how bacteria will evade killing by phage and identify the downstream consequences of phage-resistant bacterial infections. In our current study, we found that while phage-resistant mutant bacteria quickly emerged, these mutations left bacteria less capable of growing in human urine and colonizing the murine bladder. These results suggest that phage therapy poses a viable UTI treatment if phage resistance confers fitness costs for the uropathogen. These results have implications for developing cocktails of phage with multiple different bacterial targets, each of which is only evaded at the cost of bacterial fitness.

microbiology↗