Showing papers by "B. Brett Finlay published in 2023"
2 citations
TL;DR: In this article , the role of GrlR and GrlA in the regulation of the locus of enterocyte effacement (LEE) was investigated in E. coli and Citrobacter rodentium.
Abstract: Introduction Enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium (CR) belong to a group of pathogens that share the ability to form “attaching and effacing” (A/E) lesions on the intestinal epithelia. A pathogenicity island known as the locus of enterocyte effacement (LEE) contains the genes required for A/E lesion formation. The specific regulation of LEE genes relies on three LEE-encoded regulators: Ler activates the expression of the LEE operons by antagonizing the silencing effect mediated by the global regulator H-NS, GrlA activates ler expression and GrlR represses the expression of the LEE by interacting with GrlA. However, despite the existing knowledge of LEE regulation, the interplay between GrlR and GrlA and their independent roles in gene regulation in A/E pathogens are still not fully understood. Methods To further explore the role that GrlR and GrlA in the regulation of the LEE, we used different EPEC regulatory mutants and cat transcriptional fusions, and performed protein secretion and expression assays, western blotting and native polyacrylamide gel electrophoresis. Results and discussion We showed that the transcriptional activity of LEE operons increased under LEE-repressing growth conditions in the absence of GrlR. Interestingly, GrlR overexpression exerted a strong repression effect over LEE genes in wild-type EPEC and, unexpectedly, even in the absence of H-NS, suggesting that GrlR plays an alternative repressor role. Moreover, GrlR repressed the expression of LEE promoters in a non-EPEC background. Experiments with single and double mutants showed that GrlR and H-NS negatively regulate the expression of LEE operons at two cooperative yet independent levels. In addition to the notion that GrlR acts as a repressor by inactivating GrlA through protein-protein interactions, here we showed that a DNA-binding defective GrlA mutant that still interacts with GrlR prevented GrlR-mediated repression, suggesting that GrlA has a dual role as a positive regulator by antagonizing GrlR’s alternative repressor role. In line with the importance of the GrlR-GrlA complex in modulating LEE gene expression, we showed that GrlR and GrlA are expressed and interact under both inducing and repressing conditions. Further studies will be required to determine whether the GrlR alternative repressor function depends on its interaction with DNA, RNA, or another protein. These findings provide insight into an alternative regulatory pathway that GrlR employs to function as a negative regulator of LEE genes.
TL;DR: In this paper , the authors used a combined RNA-Seq and TnSeq approach to characterize EHEC response to metabolites from an in vitro culture of 33 human gut microbiota isolates (MET-1), previously demonstrated to effectively resolve recurrent Clostridioides difficile infection in human patients.
Abstract: ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) is a major cause of severe bloody diarrhea, with potentially lethal complications, such as hemolytic uremic syndrome. In humans, EHEC colonizes the colon, which is also home to a diverse community of trillions of microbes known as the gut microbiota. Although these microbes and the metabolites that they produce represent an important component of EHEC’s ecological niche, little is known about how EHEC senses and responds to the presence of gut microbiota metabolites. In this study, we used a combined RNA-Seq and Tn-Seq approach to characterize EHEC’s response to metabolites from an in vitro culture of 33 human gut microbiota isolates (MET-1), previously demonstrated to effectively resolve recurrent Clostridioides difficile infection in human patients. Collectively, the results revealed that EHEC adjusts to growth in the presence of microbiota metabolites in two major ways: by altering its metabolism and by activating stress responses. Metabolic adaptations to the presence of microbiota metabolites included increased expression of systems for maintaining redox balance and decreased expression of biotin biosynthesis genes, reflecting the high levels of biotin released by the microbiota into the culture medium. In addition, numerous genes related to envelope and oxidative stress responses (including cpxP, spy, soxS, yhcN, and bhsA) were upregulated during EHEC growth in a medium containing microbiota metabolites. Together, these results provide insight into the molecular mechanisms by which pathogens adapt to the presence of competing microbes in the host environment, which ultimately may enable the development of therapies to enhance colonization resistance and prevent infection.
TL;DR: Zhang et al. as discussed by the authors discussed the role of malnutrition, malnutrition, and immunity on severity of COVID-19 and the importance of studying them from a gut-systemic perspective using multi-omics approaches.
TL;DR: In this paper , the authors used an LC-MS/MS approach to investigate the role of QS as an effective mechanism to regulate virulence according to the pathogen's spatio-temporal context to optimize colonization and transmission success.
Abstract: Quorum Sensing (QS) is a form of cell-to-cell communication that enables bacteria to modify behaviour according to their population density. While QS has been proposed as a potential intervention against pathogen infection, QS-mediated communication within the mammalian digestive tract remains understudied. Using an LC-MS/MS approach, we discovered that Citrobacter rodentium, a natural murine pathogen used to model human infection by pathogenic Escherichia coli, utilizes the CroIR system to produce three QS-molecules. We then profiled their accumulation both in vitro and across different gastrointestinal sites over the course of infection. Importantly, we found that in the absence of QS capabilities the virulence of C. rodentium is enhanced. This highlights the role of QS as an effective mechanism to regulate virulence according to the pathogen’s spatio-temporal context to optimize colonization and transmission success. These results also demonstrate that inhibiting QS may not always be an effective strategy for the control of virulence.
TL;DR: In this article , the authors developed a preclinical model to examine undernutrition's metabolic and functional impact on the host and gut microbiome early in life, and they found that early-life multiple micronutrient deficiencies induced stunting, altered body composition, impaired glucose and insulin tolerance, and altered the levels of other micRONutrients not depleted in the diet within the host.
Abstract: Micronutrients perform a wide range of physiological functions essential for growth and development. However, most people still need to meet the estimated average requirement worldwide. Globally, 2 billion people suffer from micronutrient deficiency, most of which are co-occurring deficiencies in children under age five. Despite decades of research, animal models studying multiple micronutrient deficiencies within the early-life period are lacking, which hinders our complete understanding of the long-term health implications and may contribute to the inefficacy of some nutritional interventions. Evidence supporting the Developmental Origins of Health and Disease (DOHaD) theory demonstrates that early-life nutritional deficiencies carry life-long consequences mediated through various mechanisms such as abnormal metabolic programming, stunting, altered body composition, and the gut microbiome. However, this is largely unexplored in the multiple micronutrient deficient host.we developed a preclinical model to examine undernutrition’s metabolic and functional impact on the host and gut microbiome early in life. Three-week-old weanling C57BL/6N male mice were fed a low-micronutrient diet deficient in zinc, folate, iron, vitamin A, and vitamin B12 or a control diet for 4-weeks.Our results showed that early-life multiple micronutrient deficiencies induced stunting, altered body composition, impaired glucose and insulin tolerance, and altered the levels of other micronutrients not depleted in the diet within the host. In addition, functional metagenomics profiling and a carbohydrate fermentation assay showed an increased microbial preference for simple sugars rather than complex ones, suggestive of a less developed microbiome in the low-micronutrient-fed mice. Moreover, we found that a zinc-only deficient diet was not sufficient to induce these phenotypes, further supporting the importance of studying co-occurring deficiencies.Together, these findings highlight a previously unappreciated role of early-life multiple micronutrient deficiencies in shaping the metabolic phenome of the host and gut microbiome through altered glucose energy metabolism, which may have implications for metabolic disease later in life in micronutrient-deficient survivors.
TL;DR: In this paper , the authors reported that aberrant activity of host FASN enzyme may cause mitochondrial dysfunction and thus, facilitate intestinal colonization by Enterobacteriaceae in colitis patients.
TL;DR: Gerbec et al. as mentioned in this paper found that microbiome depletion significantly reduces primary tumor growth highly metastatic 4T1 tumors specifically, and they also found bacterial depletion reduces metastatic burden and extends survival time compared to microbiome-replete controls.
Abstract:
Metastasis is a major barrier to long-term survival and therapeutic options for aggressive, metastatic forms of breast cancer remain limited. Studies using patient samples have identified tumor-resident bacteria that preferentially associate with specific breast cancer types including highly aggressive TNBC. However, it is not yet understood how intratumoral bacteria directly contributes to disease progression and metastatic propensity independent of other prognostic factors. It is therefore the goal of the Dedhar and Finlay labs to identify how specific bacteria within metastatic breast cancer control immune and tumor cell functions to regulate metastatic potential and determine the outcome of disease progression. Using the syngenic, immunocompetent 4T1 and 67NR breast cancer models of metastatic and non-metastatic disease, we found microbiome depletion significantly reduces primary tumor growth highly metastatic 4T1 tumors specifically. We also found bacterial depletion reduces metastatic burden and extends survival time compared to microbiome-replete controls. Along with alterations in disease progression, microbiome depletion induces changes in immune cell function that occur specifically in the metastatic 4T1 tumors, revealing differential microbial-based regulation of metastatic versus non-metastatic disease. To identify bacteria that control metastasis in microbiome-replete controls, we plated surgically resected tumor suspensions on bacterial growth media and compared bacteria from the 4T1 and 67NR primary tumors. We identified several species of the Bacillus genus that were unique to 4T1 tumors and were present both within the primary tumor as well as metastatic nodules. To determine how these bacteria effect disease progression, we designed several in vivo model systems to directly test the ability of the isolated bacteria to promote metastasis. Using an orthotopic inoculation model with 4T1 or EMT6 cells, we found that following intratumoral injection, the 4T1- derived Bacillus species was actually able to augment metastasis when introduced directly back into primary tumors. To determine the specificity of this phenomenon, we then compared the effects of the 4T1 and 67NR-isolated bacteria on metastasis by injecting 4T1 cells that had been co-cultured with either bacteria prior to injection. Interestingly, we found that while the 67NR-derived bacteria had little effect on metastasis, the 4T1-derived Bacillus species significantly enhanced metastatic tumor burden compared to all other groups including those cultured with the 67NR-derived bacteria. These data demonstrate the ability of certain bacteria to promote metastatic disease. Based on these findings, we hypothesize specific bacteria play a causative role in augmenting metastatic propensity, and seek to determine functional differences between intratumoral bacteria to identify mechanistic targets for prevention of metastasis. We also seek to expand this work into clinical models to identify potential prognostic factors as well as mechanistic targets for disease treatment.
Citation Format: Zachary J. Gerbec, Antonio Serapio-Palacios, Sarah E. Woodword, Jorge Pena Diaz, Brett Finlay, Shoukat Dedhar. Tumor-derived bacteria drive breast cancer metastasis [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr A047.
TL;DR: Gerbec et al. as discussed by the authors identified several species of the Bacillus genus that were unique to 4T1 tumors and were present both within the primary tumor as well as metastatic nodules.
Abstract:
Metastasis is a major barrier to long-term survival and therapeutic options for aggressive, metastatic forms of breast cancer remain limited. Studies using patient samples have identified tumor-resident bacteria that preferentially associate with specific breast cancer types, however, it is not yet understood how intratumoral bacteria directly contributes to disease progression and metastatic propensity independent of other prognostic factors. It is therefore the goal of the Dedhar and Finlay labs to identify how specific bacteria within metastatic breast cancer control immune and tumor cell functions to regulate metastatic potential and determine the outcome of disease progression. Using the syngenic, immunocompetent 4T1 and 67NR breast cancer models of metastatic and non-metastatic disease, we found microbiome depletion significantly reduces primary tumor growth of highly metastatic 4T1 tumors specifically. We also found bacterial depletion reduces metastatic burden and extends survival time compared to microbiome-replete controls. Microbiome depletion also induces changes in immune cell function that occur specifically in the metastatic 4T1 tumors, revealing differential microbial-based regulation of metastatic versus non-metastatic disease. To identify bacteria that control metastasis in microbiome-replete controls, we plated surgically resected tumor suspensions on bacterial growth media and compared bacteria from the 4T1 and 67NR primary tumors. We identified several species of the Bacillus genus that were unique to 4T1 tumors and were present both within the primary tumor as well as metastatic nodules. We then designed several in vivo model systems to directly test the ability of the isolated bacteria to promote metastasis. Using an orthotopic inoculation model with 4T1 or EMT6 cells, we found that following intratumoral injection, the 4T1-derived Bacillus species was actually able to augment metastasis when introduced directly back into primary tumors. To determine the specificity of this phenomenon, we then compared the effects of the 4T1 and 67NR-isolated bacteria on metastasis by injecting 4T1 cells that had been co-cultured with either bacteria prior to injection. Interestingly, we found that while the 67NR-derived bacteria had little effect on metastasis, the 4T1-derived Bacillus species significantly enhanced metastatic tumor burden compared to all other groups including those cultured with the 67NR-derived bacteria. These data demonstrate the ability of certain bacteria to promote metastatic disease. Based on these findings, we hypothesize specific bacteria play a causative role in augmenting metastatic propensity, and seek to determine functional differences between intratumoral bacteria to identify mechanistic targets for prevention of metastasis. We also seek to expand this work into clinical models to identify potential prognostic factors as well as mechanistic targets for disease treatment.
Citation Format: Zachary J. Gerbec, Antonio Serapio-Palacios, Sarah Woodward, Jorge Pena-Diaz, B Brett Finlay, Shoukat Dedhar. Tumor-derived bacteria drive breast cancer metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5897.