Browsing by Author "Brutkiewicz, Randy"

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    Characterization of Allergen-Specific Immunoglubulin E Development in a Food Allergy Model and Its Regulation by T Follicular Helper and T Follicular Regulatory Cells
    (2023-05) Chen, Qiang; Dent, Alexander; Kaplan, Mark; Brutkiewicz, Randy; Zhou, Baohua
    Food allergy is a highly prevalent and serious disease regulated by immunoglobin E (IgE) antibodies specific for food allergens.The development of IgE is regulated by T follicular helper cells (TFH) and T follicular regulatorycells (TFR) in the germinal center (GC). We aimed to understandthe regulation of IgEin the GC by TFH and TFR cellsusinga mouse food allergy model. We found that the dosage and timingof allergen delivery into thegut is criticalfor allergen-specific IgE development, in part because the timing of allergen delivery affected the expression of regulatory factors by TFH and TFR cells. We studied FGL2, an inhibitory factor, and found that down-regulation of FGL2 in TFH cells was important for the allergic IgEresponse. Apart from inhibitory factors, TFH cell-derived IL-4 is required for IgE responses. We unexpectedlyfound that TFR cells in food allergy produce comparable amountsof IL-4 to TFH cellsand IL-4–expressing TFR cells promoteallergen-specific IgEin food allergy. The IgE response is highly sensitive to IL-4 levels, suggesting the need for extra IL-4 from TFR cells. However,TFR cells have distinct functionsdepending on the immune environment, since TFR cells repress IgEinanairway inflammation model. We found that TFR cells in airway inflammation have a different gene expression profile from TFR cells in food allergy, whichmay explain their distinct functions. Lastly, previous studies showed that high-affinity IgE driving anaphylactic reactions is produced via IgG1-switchedintermediate B cells. We challenged this paradigm by showing that high-affinity IgE develops in the absence ofIgG1-switchedB cellsin our food allergy model.Overall, our studies reveal that IgE is regulated by novel pathways in food allergy. We hope to exploit these new pathways to develop new specific therapies for food allergy.
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    Diversifying biomedical training: A synergistic intervention
    (2010) Gibau, Gina Sanchez; Foertsch, Julie; Blum, Janice; Brutkiewicz, Randy; Queener, Sherry; Roman, Ann; Rhodes, Simon; Sturek, Michael; Wilkes, David; Broxmeyer, Hal
    For over three decades, the scientific community has expressed concern over the paucity of African American, Latino and Native American researchers in the biomedical training pipeline. Concern has been expressed regarding what is forecasted as a shortage of these underrepresented minority (URM) scientists given the demographic shifts occurring worldwide and particularly in the United States. Increased access to graduate education has made a positive contribution in addressing this disparity. This article describes the multiple pathway approaches that have been employed by a school of medicine at an urban Midwest research institution to increase the number of URM students enrolled in, and graduating from, doctoral programs within basic science departments, through the combination of R25 grants and other grant programs funded by the National Institutes of Health (NIH). This article outlines the process of implementing a strong synergistic approach to the training of URM students through linkages between the NIH-funded "Bridges to the Doctorate (BRIDGES)" and "Initiative for Maximizing Graduate Student Diversity (IMGSD)" programs. The article documents the specific gains witnessed by this particular institution and identifies key components of the interventions that may prove useful for institutions seeking to increment the biomedical pipeline with scientists from diverse backgrounds.
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    IL-9 Intrinsically Alters Gene Expression and Chromatin Structure in Pulmonary Macrophages to Enhance Lung Tumor Growth
    (2025-04) Cannon, Anthony Michael; Kaplan, Mark H.; Jerde, Travis; Brutkiewicz, Randy; Snell, Laura
    Tumor-associated macrophages are an abundant, tumor-infiltrating cell population that support tumor progression through mechanisms such as extracellular matrix remodeling, immunosuppression, and metabolic reprogramming. The cytokine milieu is a factor that influences the functional phenotype of TAMs within the tumor microenvironment. Among these, interleukin-9 (IL-9) is a pleiotropic cytokine with both tumor-promoting and tumor-suppressing roles depending on the cancer type and responding cell. Importantly, mechanistic understanding of IL-9 in cancer is largely undefined. The work described in this thesis mechanistically defines the role of IL-9-responsive macrophages in the progression and metastasis of lung tumors. We demonstrate that IL-9 expands lung interstitial macrophage populations and induces the expression of Arginase 1 (ARG1), a critical enzyme in arginine to polyamine metabolism that is associated with poor survival in patients. Therapeutically, targeting ARG1-expressing macrophages using Arg1 siRNA-loaded nanoparticles significantly reduced polyamine levels and tumor burden. Additionally, bulk RNA sequencing and single-nuclei multi-modal ATAC and RNA sequencing in mixed-bone marrow chimeric mice revealed that IL-9 intrinsically reprograms the epigenetic and transcriptomic landscape of lung interstitial macrophages. Dysregulation of key genes, including Pdl1 and several cathepsins (Ctsd, Ctse, and Ctss), was identified and linked to increased tumor growth and an impaired anti-tumor immune response. In summary, this work identifies a critical vii pro-tumor mechanism of IL-9 in lung interstitial macrophages, characterized by dysregulated arginine metabolism, altered macrophage gene expression, and reduced anti-tumor immune responses. These findings underscore the potential of targeting IL-9-mediated pathways in macrophages as a potential therapeutic approach in lung cancer and metastasis.
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    Novel Strategies for the Prevention of Post-Stroke Epilepsy and Sudden Unexpected Death in Epilepsy Patients
    (2022-10) Adhikari, Yadav Prasad; Truitt, William; Witkin, Jeffrey M.; Gupta, Kunal; Brutkiewicz, Randy; Jin, Xiaoming
    Stroke is the second leading cause of mortality worldwide, accounting for 5.5 million deaths annually. In addition to its high mortality rate, stroke is the most common cause of acquired epilepsy. Three to thirty percent of stroke survivors develop post-stroke epilepsy. Although currently available therapies such as thrombolytics and mechanical thrombectomy prevent immediate mortality by restoring blood flow after stroke, these treatments do not target the cellular and molecular mechanisms that lead to post-stroke epileptogenesis. With the increasing number of stroke survivors, there is an urgent need for therapies that prevent epilepsy development in this population. Here, we showed that homeostatic plasticity is involved in the development of hyperexcitability after stroke and can be targeted to prevent the development of post-stroke epilepsy. Using two-photon calcium imaging, we found that homeostatic regulation leads to cortical hyperexcitability after stroke. We also found that activity enhancement by optogenetic and pharmacological approaches can target homeostatic plasticity to prevent post-stroke epilepsy. This study demonstrates the high translational potential of activity enhancement as a novel strategy to prevent post-stroke epilepsy through regulating cortical homeostatic plasticity. Sudden premature death is a leading cause of death in patients with medically refractory epilepsy. This unanticipated death of a relatively healthy person with epilepsy in which no structural or toxicological cause of death can be identified after postmortem analysis is referred to as sudden unexpected death in epilepsy patients (SUDEP). Respiratory failure during seizures is an important underlying mechanism of SUDEP. Here, we showed that LPS-induced peripheral inflammation is protective against SUDEP. This protection is mediated at least in part via enhancing serotonergic function in the brain stem. To the best of our knowledge, this is the first study demonstrating the relationship between peripheral inflammation and SUDEP prevention.
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    A Synthetic Lethal shRNA Screen and Genetic Proof of Concept Identifies RAC1 as a Novel Target to Disrupt Plexiform Neurofibroma Formation
    (2019-12) Mund, Julie Ann; Clapp, D. Wade; Goebl, Mark; Harrington, Maureen; Brutkiewicz, Randy
    Neurofibromatosis Type 1 (NF1) is a highly penetrant autosomal dominant genetic disorder where mutations in the tumor suppressor gene NF1 leads to decreased neurofibromin. The most debilitating manifestation is the presence of complex multilineage Schwann cell-derived plexiform neurofibromas (PN). Historically, little clinical success has been achieved targeting PN through surgery or chemotherapies. I performed an shRNA library screen of patient-derived Schwann cell lines to identify novel therapeutic targets to disrupt PN formation and progression. An shRNA library screen of human kinases and Rho-GTPases was performed in NF1-/- and paired NF1 competent immortalized Schwann cell lines. Following sequencing, candidates were identified. We previously developed a novel mouse model of NF1 wherein a neural crest specific Postncre targeted loxp-flanked Nf1 that replicated the PN found in patients. Additional cohorts of mice were generated with biallelic deletion of Rac1 (Nf1f/fRac1f/f Postn-Cre+; DKO ). Mice were aged for 9 months and peripheral nerves were harvested and fixed in formalin. Peripheral nerve size was measured and tumors were identified through blinded analysis of hematoxylin and eosin and Masson’s Trichrome (collagen) stained slides. Rho family members, including RAC1, were identified as candidates through an shRNA library screen. Genetic disruption of Rac1 in the Schwann cell lineage resulted in the prevention of tumor formation in DKO mice, as observed by peripheral nerve size and histological analysis. I observed an average of 14.8 +/- 2.65 tumors per mouse in the Nf1f/f Postnviii Cre+ cohort compared to 0 tumors in the DKO (p<0.0001). Following an shRNA library screen, RAC1 was identified as a candidate to modulate PN formation. Biallelic deletion of Rac1 in vivo prevented PN formation. I demonstrate that a candidate identified in an shRNA library screen can translate to an biological effect in a mouse model of PN.