IU Indianapolis ScholarWorks :: Browsing by Author "Gaddy, Jennifer A."

Browsing by Author "Gaddy, Jennifer A."

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Antibacterial and Anti-biofilm Activity of the Human Breast Milk Glycoprotein Lactoferrin against Group B Streptococcus
(Wiley, 2021) Lu, Jacky; Francis, Jamisha D.; Guevara, Miriam A.; Doster, Ryan S.; Eastman, Alison J.; Rogers, Lisa M.; Noble, Kristin N.; Manning, Shannon D.; Damo, Steven M.; Aronoff, David M.; Townsend, Steven D.; Gaddy, Jennifer A.; Medicine, School of Medicine
Group B Streptococcus (GBS) is an encapsulated Gram-positive human pathogen that causes invasive infections in pregnant hosts and neonates, as well as immunocompromised individuals. Colonization of the human host requires the ability to adhere to mucosal surfaces and circumnavigate the nutritional challenges and antimicrobial defenses associated with the innate immune response. Biofilm formation is a critical process to facilitate GBS survival and establishment of a replicative niche in the vertebrate host. Previous work has shown that the host responds to GBS infection by producing the innate antimicrobial glycoprotein lactoferrin, which has been implicated in repressing bacterial growth and biofilm formation. Additionally, lactoferrin is highly abundant in human breast milk and could serve a protective role against invasive microbial pathogens. This study demonstrates that human breast milk lactoferrin has antimicrobial and anti-biofilm activity against GBS and inhibits its adherence to human gestational membranes. Together, these results indicate that human milk lactoferrin could be used as a prebiotic chemotherapeutic strategy to limit the impact of bacterial adherence and biofilm formation on GBS-associated disease outcomes.
Distinct Group B Streptococcus Sequence and Capsule Types Differentially Impact Macrophage Stress and Inflammatory Signaling Responses
(American Society for Microbiology, 2021-04-16) Flaherty, Rebecca A.; Aronoff, David M.; Gaddy, Jennifer A.; Petroff, Margaret G.; Manning, Shannon D.; Medicine, School of Medicine
Group B Streptococcus (GBS) is an opportunistic bacterial pathogen that can contribute to the induction of preterm birth in colonized pregnant women and to severe neonatal disease. Many questions regarding the mechanisms that drive GBS-associated pathogenesis remain unanswered, and it is not yet clear why virulence has been observed to vary so extensively across GBS strains. Previously, we demonstrated that GBS strains of different sequence types (STs) and capsule (CPS) types induce different cytokine profiles in infected THP-1 macrophage-like cells. Here, we expanded on these studies by utilizing the same set of genetically diverse GBS isolates to assess ST and CPS-specific differences in upstream cell death and inflammatory signaling pathways. Our results demonstrate that particularly virulent STs and CPS types, such as the ST-17 and CPS III groups, induce enhanced Jun-N-terminal protein kinase (JNK) and NF-κB pathway activation following GBS infection of macrophages compared with other ST or CPS groups. Additionally, we found that ST-17, CPS III, and CPS V GBS strains induce the greatest levels of macrophage cell death during infection and exhibit a more pronounced ability to be internalized and to survive in macrophages following phagocytosis. These data provide further support for the hypothesis that variable host innate immune responses to GBS, which significantly impact pathogenesis, stem in part from genotypic and phenotypic differences among GBS isolates. These and similar studies may inform the development of improved diagnostic, preventive, or therapeutic strategies targeting invasive GBS infections.
Environmental Toxicant Exposure Paralyzes Human Placental Macrophage Responses to Microbial Threat
(American Chemical Society, 2023) Stephens, Victoria R.; Moore, Rebecca E.; Spicer, Sabrina K.; Talbert, Julie A.; Lu, Jacky; Chinni, Riya; Chambers, Schuyler A.; Townsend, Steven D.; Manning, Shannon D.; Rogers, Lisa M.; Aronoff, David M.; Vue, Zer; Neikirk, Kit; Hinton, Antentor O., Jr.; Damo, Steven M.; Noble, Kristen N.; Eastman, Alison J.; McCallister, Monique M.; Osteen, Kevin G.; Gaddy, Jennifer A.; Medicine, School of Medicine
Exposure to environmental toxicants (such as dioxins) has been epidemiologically linked to adverse reproductive health outcomes, including placental inflammation and preterm birth. However, the molecular underpinnings that govern these outcomes in gravid reproductive tissues remain largely unclear. Placental macrophages (also known as Hofbauer cells) are crucial innate immune cells that defend the gravid reproductive tract and help promote maternal-fetal tolerance. We hypothesized that exposure to environmental toxicants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) could alter placental macrophage responses to inflammatory insults such as infection. To test this, placental macrophages were cultured in the presence or absence of TCDD and then infected with the perinatal pathogen Group B Streptococcus (GBS). Our results indicate that TCDD is lethal to placental macrophages at and above a 5 nM concentration and that sublethal dioxin exposure inhibits phagocytosis and cytokine production. Taken together, these results indicate that TCDD paralyzes placental macrophage responses to bacterial infection.
Epidemiological Trends of Racial Differences in Early- and Late-onset Group B Streptococcus Disease in Tennessee
(Oxford University Press, 2021) Hamdan, Lubna; Vandekar, Simon; Spieker, Andrew J.; Rahman, Herdi; Ndi, Danielle; Shekarabi, Emily S.; Thota, Jyotsna; Rankin, Danielle A.; Haddadin, Zaid; Markus, Tiffanie; Aronoff, David M.; Schaffner, William; Gaddy, Jennifer A.; Halasa, Natasha B.; Medicine, School of Medicine
Background: The rates of early-onset group B Streptococcus (GBS) disease (EOGBS) have declined since the implementation of universal screening and intrapartum antibiotic prophylaxis guidelines but late-onset (LOGBS) rates remain unchanged. Racial differences in GBS disease rates have been previously documented, with Black infants having higher rates of EOGBS and LOGBS, but it is not known if these have persisted. Therefore, we sought to determine the differences in EOGBS and LOGBS disease by race over the past decade in Tennessee. Methods: This study used active population-based and laboratory-based surveillance data for invasive GBS disease conducted through Active Bacterial Core surveillance in selected counties across Tennessee. We included infants younger than 90 days and who had invasive GBS disease between 2009 and 2018. Results: A total of 356 GBS cases were included, with 60% having LOGBS. EOGBS and LOGBS had decreasing temporal trends over the study period. Overall, there were no changes in temporal trend noted in the rates of EOGBS and LOGBS among White infants. However, Black infants had significantly decreasing EOGBS and LOGBS temporal trends (relative risk [95% confidence interval], .87 [.79, .96] [P = .007] and .90 [.84-.97] [P = .003], respectively). Conclusions: Years after the successful implementation of the universal screening guidelines, our data revealed an overall decrease in LOGBS rates, primarily driven by changes among Black infants. More studies are needed to characterize the racial disparities in GBS rates, and factors driving them. Prevention measures such as vaccination are needed to have a further impact on disease rates.
Group B Streptococcal Membrane Vesicles Induce Proinflammatory Cytokine Production and Are Sensed in an NLRP3 Inflammasome-Dependent Mechanism in a Human Macrophage-like Cell Line
(American Chemical Society, 2025) McCutcheon, Cole R.; Gaddy, Jennifer A.; Aronoff, David M.; Manning, Shannon D.; Petroff, Margaret G.; Medicine, School of Medicine
Group B Streptococcus (GBS) is a major cause of fetal and neonatal mortality worldwide. Many of the adverse effects of invasive GBS are associated with inflammation; therefore, understanding bacterial factors that promote inflammation is of critical importance. Membrane vesicles (MVs), which are produced by many bacteria, may modulate host inflammatory responses. While it is known that mice injected intra-amniotically with GBS MVs exhibit large-scale leukocyte infiltration, preterm birth, and subsequent fetal death, the immune effectors driving this response remain unclear. Here, we hypothesized that THP-1 macrophage-like cells respond to GBS-derived MVs by producing proinflammatory cytokines and are recognized through one or more pattern recognition receptors. We show that THP-1s produce high levels of neutrophil- and monocyte-specific chemokines in response to MVs derived from different clinical isolates of GBS. Using antibody microarrays and multiplex Luminex assays, we found that GBS MVs elicit significantly (p < 0.05) higher levels of CCL1, CCL2, CCL20, CXCL1, CXCL10, and IL-1β relative to untreated THP-1s. Using chemical inhibitors in combination with caspase-1 activity assays and Luminex assays, we further demonstrate that GBS MVs upregulated IL-1β production in a caspase-1 and NLRP3-dependent manner, ultimately identifying NLRP3 as a sensor of GBS MVs. These data indicate that MVs contain one or more pathogen-associated molecular patterns that can be sensed by the immune system and show that the NLRP3 inflammasome is a novel sensor of GBS MVs. Our data additionally indicate that MVs may serve as immune effectors that can be targeted for immunotherapeutics.
Group B Streptococcus cpsE is required for serotype V capsule production and aids in biofilm formation and ascending infection of the reproductive tract during pregnancy
(American Chemical Society, 2021) Noble, Kristen; Lu, Jacky; Guevara, Miriam A.; Doster, Ryan S.; Chambers, Schuyler A.; Rogers, Lisa M.; Moore, Rebecca E.; Spicer, Sabrina K.; Eastman, Alison J.; Francis, Jamisha D.; Manning, Shannon D.; Rajagopal, Lakshmi; Aronoff, David M.; Townsend, Steven D.; Gaddy, Jennifer A.; Pediatrics, School of Medicine
Group B Streptococcus (GBS) is an encapsulated Gram-positive pathogen that causes ascending infections of the reproductive tract during pregnancy. The capsule of this organism is a critical virulence factor that has been implicated in a variety of cellular processes to promote pathogenesis. Primarily comprised of carbohydrates, the GBS capsule and its synthesis is driven by the capsule polysaccharide synthesis (cps) operon. The cpsE gene within this operon encodes a putative glycosyltransferase that is responsible for the transfer of a Glc-1-P from UDP-Glc to an undecaprenyl lipid molecule. We hypothesized that the cpsE gene product is important for GBS virulence and ascending infection during pregnancy. Our work demonstrates that a GBS cpsE mutant secretes fewer carbohydrates, has a reduced capsule, and forms less biofilm than the wild-type parental strain. We show that, compared to the parental strain, the ΔcpsE deletion mutant is more readily taken up by human placental macrophages and has a significantly attenuated ability to invade and proliferate in the mouse reproductive tract. Taken together, these results demonstrate that the cpsE gene product is an important virulence factor that aids in GBS colonization and invasion of the gravid reproductive tract.
Palmitate and group B Streptococcus synergistically and differentially induce IL-1β from human gestational membranes
(Frontiers Media, 2024-05-23) Gaddy, Jennifer A.; Moore, Rebecca E.; Lochner, Jonathan S.; Rogers, Lisa M.; Noble, Kristen N.; Giri, Ayush; Aronoff, David M.; Cliffel, David; Eastman, Alison J.; Medicine, School of Medicine
Introduction: Rupture of the gestational membranes often precedes major pregnancy complications, including preterm labor and preterm birth. One major cause of inflammation in the gestational membranes, chorioamnionitis (CAM) is often a result of bacterial infection. The commensal bacterium Streptococcus agalactiae, or Group B Streptococcus (GBS) is a leading infectious cause of CAM. Obesity is on the rise worldwide and roughly 1 in 4 pregnancy complications is related to obesity, and individuals with obesity are also more likely to be colonized by GBS. The gestational membranes are comprised of several distinct cell layers which are, from outermost to innermost: maternally-derived decidual stromal cells (DSCs), fetal cytotrophoblasts (CTBs), fetal mesenchymal cells, and fetal amnion epithelial cells (AECs). In addition, the gestational membranes have several immune cell populations; macrophages are the most common phagocyte. Here we characterize the effects of palmitate, the most common long-chain saturated fatty acid, on the inflammatory response of each layer of the gestational membranes when infected with GBS, using human cell lines and primary human tissue. Results: Palmitate itself slightly but significantly augments GBS proliferation. Palmitate and GBS co-stimulation synergized to induce many inflammatory proteins and cytokines, particularly IL-1β and matrix metalloproteinase 9 from DSCs, CTBs, and macrophages, but not from AECs. Many of these findings are recapitulated when treating cells with palmitate and a TLR2 or TLR4 agonist, suggesting broad applicability of palmitate-pathogen synergy. Co-culture of macrophages with DSCs or CTBs, upon co-stimulation with GBS and palmitate, resulted in increased inflammatory responses, contrary to previous work in the absence of palmitate. In whole gestational membrane biopsies, the amnion layer appeared to dampen immune responses from the DSC and CTB layers (the choriodecidua) to GBS and palmitate co-stimulation. Addition of the monounsaturated fatty acid oleate, the most abundant monounsaturated fatty acid in circulation, dampened the proinflammatory effect of palmitate. Discussion: These studies reveal a complex interplay between the immunological response of the distinct layers of the gestational membrane to GBS infection and that such responses can be altered by exposure to long-chain saturated fatty acids. These data provide insight into how metabolic syndromes such as obesity might contribute to an increased risk for GBS disease during pregnancy.
Production and Composition of Group B Streptococcal Membrane Vesicles Vary Across Diverse Lineages
(Frontiers Media, 2021-11-22) McCutcheon, Cole R.; Pell, Macy E.; Gaddy, Jennifer A.; Aronoff, David M.; Petroff, Margaret G.; Manning, Shannon D.; Medicine, School of Medicine
Although the neonatal and fetal pathogen Group B Streptococcus (GBS) asymptomatically colonizes the vaginal tract of ∼30% of pregnant women, only a fraction of their offspring develops invasive disease. We and others have postulated that these dimorphic clinical phenotypes are driven by strain variability; however, the bacterial factors that promote these divergent clinical phenotypes remain unclear. It was previously shown that GBS produces membrane vesicles (MVs) that contain active virulence factors capable of inducing adverse pregnancy outcomes. Because the relationship between strain variation and vesicle composition or production is unknown, we sought to quantify MV production and examine the protein composition, using label-free proteomics on MVs produced by diverse clinical GBS strains representing three phylogenetically distinct lineages. We found that MV production varied across strains, with certain strains displaying nearly twofold increases in production relative to others. Hierarchical clustering and principal component analysis of the proteomes revealed that MV composition is lineage-dependent but independent of clinical phenotype. Multiple proteins that contribute to virulence or immunomodulation, including hyaluronidase, C5a peptidase, and sialidases, were differentially abundant in MVs, and were partially responsible for this divergence. Together, these data indicate that production and composition of GBS MVs vary in a strain-dependent manner, suggesting that MVs have lineage-specific functions relating to virulence. Such differences may contribute to variation in clinical phenotypes observed among individuals infected with GBS strains representing distinct lineages.
Streptococcus agalactiae cadD alleviates metal stress and promotes intracellular survival in macrophages and ascending infection during pregnancy
(Springer Nature, 2022-09-14) Korir, Michelle L.; Doster, Ryan S.; Lu, Jacky; Guevara, Miriam A.; Spicer, Sabrina K.; Moore, Rebecca E.; Francis, Jamisha D.; Rogers, Lisa M.; Haley, Kathryn P.; Blackman, Amondrea; Noble, Kristen N.; Eastman, Alison J.; Williams, Janice A.; Damo, Steven M.; Boyd, Kelli L.; Townsend, Steven D.; Serezani, C. Henrique; Aronoff, David M.; Manning, Shannon D.; Gaddy, Jennifer A.; Medicine, School of Medicine
Perinatal infection with Streptococcus agalactiae, or Group B Streptococcus (GBS), is associated with preterm birth, neonatal sepsis, and stillbirth. Here, we study the interactions of GBS with macrophages, essential sentinel immune cells that defend the gravid reproductive tract. Transcriptional analyses of GBS-macrophage co-cultures reveal enhanced expression of a gene encoding a putative metal resistance determinant, cadD. Deletion of cadD reduces GBS survival in macrophages, metal efflux, and resistance to metal toxicity. In a mouse model of ascending infection during pregnancy, the ΔcadD strain displays attenuated bacterial burden, inflammation, and cytokine production in gestational tissues. Furthermore, depletion of host macrophages alters cytokine expression and decreases GBS invasion in a cadD-dependent fashion. Our results indicate that GBS cadD plays an important role in metal detoxification, which promotes immune evasion and bacterial proliferation in the pregnant host.
Streptococcus agalactiae npx Is Required for Survival in Human Placental Macrophages and Full Virulence in a Model of Ascending Vaginal Infection during Pregnancy
(American Society for Microbiology, 2022-11-21) Lu, Jacky; Moore, Rebecca E.; Spice, Sabrina K.; Doster, Ryan S.; Guevara, Miriam A.; Francis, Jamisha D.; Noble, Kristen N.; Rogers, Lisa M.; Talbert, Julie A.; Korir, Michelle L.; Townsend, Steven D.; Aronoff, David M.; Manning, Shannon D.; Gaddy, Jennifer A.; Medicine, School of Medicine
Streptococcus agalactiae, also known as group B Streptococcus (GBS), is a Gram-positive encapsulated bacterium that colonizes the gastrointestinal tract of 30 to 50% of humans. GBS causes invasive infection during pregnancy that can lead to chorioamnionitis, funisitis, preterm prelabor rupture of membranes (PPROM), preterm birth, neonatal sepsis, and maternal and fetal demise. Upon infecting the host, GBS encounters sentinel innate immune cells, such as macrophages, within reproductive tissues. Once phagocytosed by macrophages, GBS upregulates the expression of the gene npx, which encodes an NADH peroxidase. GBS mutants with an npx deletion (Δnpx) are exquisitely sensitive to reactive oxygen stress. Furthermore, we have shown that npx is required for GBS survival in both THP-1 and placental macrophages. In an in vivo murine model of ascending GBS vaginal infection during pregnancy, npx is required for invading reproductive tissues and is critical for inducing disease progression, including PPROM and preterm birth. Reproductive tissue cytokine production was also significantly diminished in Δnpx mutant-infected animals compared to that in animals infected with wild-type (WT) GBS. Complementation in trans reversed this phenotype, indicating that npx is critical for GBS survival and the initiation of proinflammatory signaling in the gravid host.

Browsing by Author "Gaddy, Jennifer A."

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