Browsing by Author "Oestreich, Kenneth"
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- The Biological and Immunological Effects of Irreversible Electroporation and Combination Therapy Options for the Improving the Treatment of Pancreatic CancerBrock, Rebecca Michaela (Virginia Tech, 2020-06-05)While cancer treatments have advanced for multiple cancers, pancreatic cancer remains a lethal cancer with few therapy options available. This is due to the inaccessibility of the tumor by surgical and thermal ablative means, high potential for chemoresistance and metastasis, and strongly immunosuppressive tumor microenvironment that makes new treatment measures ineffective in clinic. Irreversible electroporation (IRE) utilizes short, high voltage electrical pulses to form microlesions in cell membranes and induce cell death. While IRE has had significant impact in pancreatic cancer treatment in clinical trials, little is known on the biological and immunological effects of IRE on pancreatic cancer. By studying the effects of IRE on pancreatic tumor biology and the host immune system, I hypothesize I can identify potential combination therapy targets for IRE. I utilized in vitro, ex vivo, and in vivo animal models of both human and murine cancer to study the effects of IRE on pancreatic cancer progression and its potential for immunomodulation. My findings have shown that IRE can significantly delay cancer progression by inducing necroptosis in the tumor and altering the tumor microenvironment by increasing inflammatory signaling. IRE can also produce viable antigens for presentation to induce local and systemic immunosurveillance. However, these effects are limited by countering expression of programmed-cell death ligand 1 (PD-L1), a checkpoint protein that inhibits cytotoxic lymphocyte activity and allows the tumors to recur. The effects of IRE can therefore be expanded by multiple combination therapy approaches, such as chemotherapeutic application (potentially with nanoparticle packaging), PD-1/PD-L1 antibody immunotherapies, and small molecule inhibitors directed at tumor growth signaling that previously showed limited efficacy in clinic.
- Dysregulation of Noncanonical NF-κB Signaling in Gastrointestinal DiseasesMorrison, Holly Ann (Virginia Tech, 2023-09-01)Regulation of host health is intricately coordinated by a diverse interplay of immune cells detecting assaults from pathogens via recognition of pathogen associated molecular patterns (PAMPs) to mount an immune response, as well as detecting damage associated molecular patterns (DAMP) to indicate an area of damage and signal tissue repair. The gastrointestinal tract is a major signaling hub for such immune responses, as intestinal epithelial cells (IECs) compose the epithelial barrier, immune cells surveillance breached barriers to regulate the gut microbiome, and intestinal stem cells (ISCs) proliferate to replenish the IEC pool. One such method for regulating these cellular functions downstream of PAMPs/DAMPs within the gastrointestinal tract is via NF-κB signaling. This cellular signaling pathway is activated by one of two pathways: the well- defined canonical NF-κB pathway and the understudied noncanonical NF-κB pathway. The noncanonical NF-κB pathway is unique as it requires NIK, the NF-κB-inducing Kinase, to further elicit signal transduction of this pathway. Noncanonical NF-κB activation is critical to maintaining gut health, as signaling is regulated at a precise level to ensure a balance of pro-/anti-inflammatory signals to elicit a proper damage response. Any perturbations to NIK-activated signaling significantly predisposes the gastrointestinal niche towards chronic inflammatory conditions of the gastrointestinal tract. In this work, we explore the potential involvement of dysregulated noncanonical NF-κB signaling in inducing chronic inflammatory diseases of the gut, including Eosinophilic Esophagitis (upper GI tract), Celiac Disease/Non-Celiac Gluten Sensitivities (small intestine), Inflammatory Bowel Disease (entire intestine/large intestine), and an inflammatory subtype of colorectal cancer being Colitis-Associated Colorectal Cancer (large intestine). We study this pathway via the use of murine models bearing genetic deletions, cellular models, and the generation of miniature organs (i.e. "organoids") in petri dishes. Further, we assess varying levels of NF-κB signaling through the genetic deletions of NIK and RelA to inhibit noncanonical and canonical NF-κB pathways, respectively. Reciprocally, we also examine overactivated signaling via loss of the negative regulatory NLRs, which are proteins that function to impede NF-κB signaling. Clinical relevancy of this work is evaluated using biopsy samples collected from human patients with active disease states. Culminating our work, we find that noncanonical NF-κB signaling levels is both tissue- and cell-type specific in driving disease formation. Finally, we conclude our findings by suggesting the promise of NIK as a potential candidate for disease biomarkers and a target for future drug development.
- Elucidating the Role of Pattern Recognition Receptors in Understanding, Treating, and Targeting CancerScaia, Veronica Marie (Virginia Tech, 2019-04-23)Pattern Recognition Receptors (PRRs) are a group of evolutionarily conserved and germline-encoded cellular receptors of the innate immune system that are responsible for recognizing and responding to the entirety of the pathogens a host encounters. The ingenuity of the innate immune system is that with a comparatively miniscule pool of receptors, these receptors are capable of responding to a diverse and large array of pathogens and damage signals. Two highly relevant subsets of PRRs include nucleotide binding domain leucine rich repeat containing (NOD-like) receptors (NLRs) and Toll-like receptors (TLRs). Both NLRs and TLRs have been implicated in several diseases, including autoimmune disorders, inflammatory conditions, and cancer. Mice lacking a specific NLR, NLRP1, are more susceptible to chemically induced colitis and colitis-associated tumorigenesis. We investigated whether the absence of NLRP1 in the gastrointestinal tract influenced the composition of the microbiome, and whether it was responsible for the predisposition of these animals to colitis-associated cancer. By carefully controlling for non-genotype influences, we found that in fact maternal and housing factors were greater predictors over genotype of gut flora composition. This study concluded with a clearer understanding of NLRP1. We next investigated the effectiveness of a novel tumor ablation therapy, termed High-Frequency Irreversible Electroporation (H-FIRE) in a murine model of triple negative breast cancer. The chosen 4T1 model closely mimics aggressive human metastatic triple negative breast cancer, and metastasizes to the same organs. After ablation of the primary mammary tumor, we saw significant improvements in disease burden and metastases, both of which were accompanied by PRR activation within the tumor microenvironment, implicating PRRs in the successful treatment outcome following H-FIRE ablation. Lastly, we generated novel CRISPR-Cas9 plasmids to genetically manipulate the Tlr4 gene of wild type C57Bl/6 mice in order to recapitulate the LPS-hyporesponsive TLR4 protein of C3H/HeJ mice. This proof-of-concept study successfully demonstrated that PRRs can be targets for gene editing purposes, and that nanoparticle delivery leads to enhanced and improved delivery. Collectively, this work attempts to better appreciate the role of PRRs in understanding, treating, and targeting cancer.
- Evaluation of the potential functions of Avian paramyxovirus Accessory proteinsAmmayappan Venkatachalam, Backiyalakshmi (Virginia Tech, 2016-06-06)Avian paramyxoviruses (APMVs) consist of twelve distinct serotypes (APMV-1 to -12) isolated from a wide variety of domestic and wild birds. APMV-1/Newcastle disease virus (NDV) is the most characterized and globally important avian pathogen, because of the huge economic loss associated with the disease. However, very little information is known about the pathogenicity of APMV 2-12. APMV expresses six structural and two accessory proteins. The functions of APMV accessory proteins (V and W) are not fully established. Only the function of V protein in NDV is studied so far. V protein was found to be an IFN antgonist and a major virulent determinant of NDV. In this study, we tested for the potential functions of W protein in NDV and fuctions of V protein in other APMV serotypes. Vaccination failure is a major cause for NDV outbreak in developing and tropical countries, because of thermolabile nature of vaccine strains. Thermostable and thermolabile NDV strains exhibit difference in W protein length. In the first part of our study, we mutated the genome of a thermolabile NDV strain to express W protein of different lengths, rescued recombinant viruses by reverse genetics system and tested for thermostability. Our results showed that W protein does not confer thermostability to NDV. In the second part of study, we constructed plasmids expressing APMV -2, -3 and -6V proteins and tested for IFN antagonism by a dual luciferase reporter assay. Our results showed that APMV-3V acts as IFN antagonist by blocking IFN induction and thereby may play an important role in the evasion of innate immunity.
- Insights Into the Regulatory Requirements for T Follicular Helper Cell DevelopmentPowell, Michael D. (Virginia Tech, 2019-04-22)During the course of an immune response, CD4+ T helper cells differentiate into a number of subsets including: T helper 1 (TH1), TH2, TH17, and T follicular helper (TFH) populations. The functional diversity of CD4+ T effector cells results in a coordinated, pathogen-specific immune response. For example, the production of IFNγ by TH1 cells is vital for the clearance of intracellular pathogens, while TFH cell engagement with cognate B cells is required for germinal center (GC) formation and the generation of pathogen- and vaccine- induced antibody production. The development of CD4+ subsets is contingent on extracellular signals, in the form of cytokines, and downstream transcriptional networks responsible for promoting the unique gene expression profile for each subset while simultaneously suppressing alternative cell fates. However, the exact composition of, and stage-specific requirements for, these environmental cytokines and transcription factor networks in the governance of TFH cell differentiation remain incompletely understood. The work in this dissertation seeks to understand how cell-extrinsic cytokine signals and cell-intrinsic transcription factor activities are integrated to properly regulate TFH cell development. Here, we demonstrate that in response to decreased IL-2 and constant IL-12 signaling, T helper 1 (TH1) cells upregulate a TFH-like phenotype, including expression of the TFH lineage defining transcription factor Bcl-6. Intriguingly, our work established that signals from IL-12 were required for both the differentiation and function of this TFH-like population. Mechanistically, IL-12 signals are propagated through both STAT3 and STAT4, leading to the upregulation of the TFH associated genes Bcl6, Il21, and Icos, correlating with increased B cell helper activity. Conversely, exposure of these TFH-like cells to IL-7 results in the STAT5-dependent repression of Bcl-6 and subsequent inhibition of the TFH phenotype. Finally, we describe a novel regulatory mechanism wherein STAT3 and the Ikaros zinc finger transcription factors Ikaros and Aiolos cooperate to regulate Bcl-6 expression in these TFH-like cells. Collectively, the work in this dissertation significantly advances our understanding of the regulatory mechanisms that govern TFH cell differentiation, setting the basis for the rational design of novel immunotherapeutic strategies and increasingly effective vaccines.
- Mechanisms underlying neural circuit remodeling in Toxoplasma gondii infectionCarrillo, Gabriela Lizana (Virginia Tech, 2022-09-20)The central nervous system (CNS) is protected by a vascular blood-brain barrier that prevents many types of pathogens from entering the brain. Still, some pathogens have evolved mechanisms to traverse this barrier and establish a long-term infection. The apicomplexan parasite, Toxoplasma gondii, is one such pathogen with the ability to infect the CNS in virtually all warm-blooded animals, including humans. Across the globe, an estimated 30% of the human population is infected with Toxoplasma, an infection for which mounting evidence suggests increases the risk for developing neurological and neuropsychiatric disorders, like seizures and schizophrenia. In my dissertation, I investigate the telencephalic neural circuit changes induced by long-term Toxoplasma infection in the mouse brain and the neuroimmune signaling role of the complement system in mediating microglial remodeling of neural circuits following parasitic infection. While there has been keen interest in investigating neural circuit changes in the amygdala – a region of the brain involved in fear response and which Toxoplasma infection alters in many species of infected hosts – the hippocampus and cortex have been less explored. These are brain regions for which Toxoplasma also has tropism, and moreover, are rich with fast-spiking parvalbumin perisomatic synapses, a type of GABAergic synapse whose dysfunction has been implicated in epilepsy and schizophrenia. By employing a range of visualization techniques to assess cell-to-cell connectivity and neuron-glia interactions (including immunohistochemistry, ultrastructural microscopy, and microglia-specific reporter mouse lines), I discovered that longterm Toxoplasma infection causes microglia to target and ensheath neuronal somata in these regions and subsequently phagocytose their perisomatic inhibitory synapses. These findings provide a novel model by which Toxoplasma infection within the brain can lead to seizure susceptibility and a wider range of behavioral and cognitive changes unrelated to fear response. In the Toxoplasma infected brain, microglia, along with monocytes recruited to the brain from the periphery, coordinate a neuroinflammatory response against pathogenic invasion. This is characterized by a widespread activation of these cells and their increased interaction with neurons and their synaptic inputs. Yet, whether T. gondii infection triggers microglia and monocytes (i.e. phagocytes) to target, ensheath, and remove perisomatic inhibitory synapses on neuronal somata indiscriminately, or whether specificity exists in this type of circuit remodeling, remained unclear. Through a comprehensive assessment of phagocyte interactions with cortical neuron subtypes, I demonstrate that phagocytes selectively target and ensheath excitatory pyramidal cells in long-term infection. Moreover, coupling of in situ hybridization with transgenic reporter lines and immunolabeling revealed that in addition to phagocytes, excitatory neurons also express complement component C3 following infection (while inhibitory interneurons do not). Lastly, by employing targeted deletion of complement components, C1q and C3, I show that complement is required for phagocyte ensheathment of excitatory cells and the subsequent removal of perisomatic inhibitory synapses on these cells (albeit not through the classical pathway). Together, these studies highlight a novel role for complement in mediating synapse-type and cell-type specific circuit remodeling in the Toxoplasma infected brain.
- Modulation of RNA Cytosine-5 Methylation by Neuronal Activity and Methyl-donor FolateXu, Xiguang (Virginia Tech, 2020-06-09)RNA epigenetics or Epitranscriptomics has emerged as a new field for understanding the post-transcriptional regulation of gene expression by RNA modifications. Among numerous types of RNA modifications, RNA cytosine-5 methylation (5-mrC) is recognized as an important epitranscriptomic mark that modulates mRNA transportation, stability and translation. In chapter 1, we summarize the currently available approaches to detect 5-mrC modification at global, transcriptome-wide and locus-specific levels, and compare the corresponding advantages and disadvantages of the techniques. We further focus on the bioinformatics data analysis of RNA bisulfite sequencing datasets by comparing existing packages with respect to key parameters for alignment and methylation calling and filtering of potentially false positive 5-mrC sites. To investigate the dynamic regulation of 5-mrC modification, as described in chapter 2, we adopt a widely used neuronal activity model, and perform RNA sequencing (RNA-seq) and RNA bisulfite sequencing (RNA BS-seq) to profile gene expression as well as transcriptome-wide 5-mrC modification. We have identified distinct gene expression profiles and differentially methylated 5-mrC sites (DMS) in neurons upon activation, and the genes with DMS sites are enriched with mitochondrial and synaptic functions. Moreover, it reveals a negative correlation between RNA methylation and mRNA expression in mouse cortical neurons during neuronal activity. Thus, these findings identify the dynamic regulation of 5-mrC modification during neuronal activity and reveal a potential link between RNA methylation and mRNA expression. In chapter 3, we investigate the effect of folate, a methyl-donor, on RNA cytosine-5 methylation (5-mrC) modification in adult mouse neural stem cells (NSCs). Compared to the control, NSCs cultured in folate deficiency or supplementation condition have shown no changes in mRNA expression, but significant changes in mRNA translation efficiency. RNA bisulfite sequencing of both total and polysome poly(A) RNA samples shows distinct 5-mrC profiles in NSCs treated with different concentrations of folic acid. It also shows consistent hypermethylation in polysome mRNAs than that in total mRNAs. This study presents the comprehensive influence of folate deficiency and supplementation on RNA cytosine-5 methylation and mRNA translation.
- Negative Regulation of Inflammation: Implications for Inflammatory Bowel Disease and Colitis Associated CancerRothschild, Daniel E. (Virginia Tech, 2018)The ability to sense and respond to external environmental signals is closely regulated by a plurality of cell signaling pathways, thereby maintaining homeostasis. In particular, the inflammatory signaling cascade contributes to cellular homeostasis and regulates responses prompted by external stimuli. Such responses are diverse and range from a variety of processes, including tissue repair, cell fate decisions, and even immune-cell signaling. As with any signaling cascade, strict regulation is required for proper functioning, as abnormalities within the pathway are often associated with pathologic outcomes. A hyperactive inflammatory response within the gastrointestinal tract, for example, contributes to inflammatory bowel disease (IBD), presenting as Crohn’s disease or ulcerative colitis. Furthermore, as a chronic condition, IBD is associated with an increased risk for the development of colitis-associated cancer. In order to resolve inflammation and thus restore homeostasis, negative regulation may be utilized to mediate the activity of inflammatory molecules. The mechanistic action of a specific negative regulator of interest, interleukin receptor associated kinase M (IRAK- M), is explored in detail within the present dissertation. Investigation of IRAK-M in mouse models of colitis, which mimics human IBD, and in mouse models of inflammation-driven tumorigenesis, which models colitis associated cancer, demonstrated that loss of this molecule contributes to host protection. Therefore, IRAK- M may be a suitable target for inhibition in order to advance therapeutic options for human patients afflicted with a GI-related inflammatory disease, such as IBD and colitis associated cancer. Furthermore, an ex vivo method that models the interaction of intestinal epithelial cells with microbes present in the GI tract was optimized and is described in the present dissertation. This method takes advantage of primary intestinal derived organoids, also termed “mini-guts”, which display similar features corresponding to intestinal tissue in vivo. For this reason, the use of “mini-guts” has several advantages, particularly for the enhancement of personalized medicine. The method discussed herein aims to normalize experimental conditions in order to enhance reproducibility, which can further be used to uncover microbial-epithelial interactions that contribute to a pathological state, such as IBD. Finally, this method of intestinal epithelial cell culture was utilized to evaluate the role of a protein, termed NF-κB inducing kinase (NIK), in intestinal epithelial cell growth and proliferation. Ultimately, ex vivo organoid culture can serve as an important model system to study the contribution of NIK in intestinal stem cell renewal, cancer progression, as well as in maintenance of the integrity of the gastrointestinal barrier.
- Noncanonical NF-KB in Gastrointestinal DiseaseEden, Kristin (Virginia Tech, 2018-11-20)Noncanonical NF-KB is an alternative NF-KB pathway that is critically involved in the development and maturation of the adaptive immune system. As such, it has typically been studied in B and T cell biology without application to complex organ systems such as the gut. The following work explores the contribution of noncanonical NF-KB to inflammatory and neoplastic disease in the gastrointestinal (GI) system, as well as the effects of its loss on GI health. Chapter 1 opens with an overview of gastrointestinal homeostasis and inflammation, with emphasis on the particular diseases studied in this body of work. Chapter 2 focuses on a review of noncanonical NF-KB function and components, as well as its applications in inflammatory bowel disease (IBD), a quintessential example of disruption of intestinal homeostasis. In Chapter 3 we determine the role of noncanonical NF-KB in allergic disease of the upper gastrointestinal tract, namely a novel model of the disease eosinophilic esophagitis. Our studies revealed that loss of NF-KB-inducing kinase (NIK), the bottleneck molecule in noncanonical NF-KB signaling, results in targeted esophageal inflammation, remodeling, and gene expression changes that are comparable to the human disease. In Chapter 4, we examine the role of noncanonical NF-KB in inflammatory bowel disease using biopsy samples from human IBD patients, and compare the expression of various components of the pathway to inflammation status and treatment response. Noncanonical NF-KB is upregulated in IBD patients, and also appears to be specifically upregulated in patients that have lost response to anti-TNF inhibitors, which are potent drugs that are widely used to treat IBD. In Chapter 5 we focus on NIK and its effects on stem cell function, growth, and inflammation-induced cancer in the gut. Loss of NIK in mice results in alterations in colonic stem cell function and changes in colonic microbiome, which predisposes them to the development of inflammation-induced carcinogenesis. Indeed, in human patients with colorectal cancer, noncanonical NF-KB is also suppressed. Overall, we have discovered multiple novel roles of noncanonical NF-KB signaling at multiple levels in the gut and in the context of a variety of diseases, and have greatly expanded the current body of knowledge as to the functions and effects of this pathway.
- Protective or Problematic? Investigating the role of the innate immune receptor NLRX1 as a tumor suppressor or promoter in breast and pancreatic cancerNagai-Singer, Margaret Ann (Virginia Tech, 2023-02-14)The innate immune system houses cellular signaling proteins called pattern recognition receptors (PRRs) that are responsible for recognizing highly-conserved molecular patterns associated with pathogens or damage to elicit an immune response. However, NLRX1 is a unique PRR in the NOD-like receptor (NLR) family that instead functions to attenuate pro-inflammatory pathways that are activated by other PRRs, such as NF-κB and type-1 interferon signaling which both have implications in cancer. NLRX1 can regulate additional cancer-associated pathways, such as MAPK and AKT, and cancer-associated functions like metabolism and reactive oxygen species (ROS) production. Interestingly, depending on the type and subtype of cancer, NLRX1 can either be tumor promoting or tumor suppressing. Here, we investigate the role of NLRX1 in two deadly cancers: triple-negative breast cancer (TNBC) and pancreatic cancer. In a murine mammary tumor model that highly mimics TNBC, we discovered that NLRX1 is protective against disease burden in vivo when NLRX1 is expressed in healthy host cells. NLRX1 exerts its protection through limiting the recruitment of eosinophils to the tumor, suppressing epithelial-mesenchymal transition (EMT), and attenuating the formation of the metastatic niche. Conversely, when NLRX1 is instead expressed by the mammary tumor cells, NLRX1 promotes cancer-associated characteristics in vitro and disease burden in vivo by promoting EMT. This indicates that the role of NLRX1 in TNBC is highly dependent on cellular context. Conversely, in murine pancreatic cancer cells, we found that NLRX1 expression by the tumor cells is protective against cancer-associated characteristics in vitro, and that this is likely driven by NF-κB, MAPK, AKT, and inflammasome signaling with a potential to also limit immune evasion. Together, this research indicates that the role of NLRX1 can be highly variable based on the cell and tumor type and identifies the underlying mechanisms through which NLRX1 functions in these two cancer models. This is critical information for drug development initiatives so therapies can be developed that target NLRX1 in the appropriate cell type and in the appropriate disease.
- The Role of Histone Deacetylase 6 Inhibition on Systemic Lupus ErythematosusRen, Jingjing (Virginia Tech, 2019-09-13)Systemic lupus erythematosus (SLE) is a chronic multifactorial inflammatory autoimmune disease with heterogeneous clinical manifestations. Among different manifestations, lupus nephritis (LN) remains a major cause of morbidity and mortality. There are few FDA approved treatments for LN. In general, they are non-selective and lead to global immunosuppression with significant side effects including an increased risk of infection. In the past 60 years, only one new drug, belimumab was approved for lupus disease with modest efficacy in clinic and not approved for patients suffering for nephritis. Therefore, it is urgent to develop new treatments to replace or reduce the use of current ones. Histone deacetylase 6 (HDAC6) plays a variety of biologic functions in a number of important molecular pathways in diverse immune cells. Both innate and adaptive immune cells contribute to pathogenesis of lupus. Among those cells, B cells play a central role in pathogenesis of lupus nephritis in an anti-body dependent manner through differentiation into plasma cells (PCs). As a result, HDAC6 inhibitors represent an entirely new class of agents that could have potent effects in SLE. Importantly, the available toxicity profile suggests that HDAC6 inhibitors could be advanced into SLE safely. We have demonstrated previously that histone deacetylase (HDAC6) expression is increased in animal models of systemic lupus erythematosus (SLE) and that inhibition of HDAC6 decreased disease. ACY-738 is a hydroxamic acid HDAC6 inhibitor that is highly selective for HDAC6. In our current studies, we tested if an orally selective HDAC6 inhibitor, ACY-738, would decrease disease pathogenesis in a lupus mouse model with established early disease. Moreover, we sought to delineate the cellular and molecular mechanism(s) of action of a selective HDAC6 inhibitor in SLE. In order to define the mechanism by which HDAC6 inhibition decreases disease pathogenesis in NZB/W mice by using RNAseq to evaluate the transcriptomic signatures of splenocytes from treated and untreated mice coupled with applied computational cellular and pathway analysis. In addition, we sought to bridge between the transcriptomic data obtained from the HDAC6 treated mice and human gene expression information to determine the relevance to this target in possibly controlling human lupus. We treated 20-week-old (early-disease) NZB/W F1 female mice with two different doses of the selective HDAC6 inhibitor (ACY-738) for 4~5 weeks. As the mice aged, we determined autoantibody production and cytokine levels by ELISA, and renal function by measuring proteinuria. At the termination of the study, we performed a comprehensive analysis on B cells, T cells, and innate immune cells using flow cytometry and examined renal tissue for immune-mediated pathogenesis using immunohistochemistry and immunofluorescence. We then used RNAseq to determine the genomic signatures of splenocytes from treated and untreated mice and applied computational cellular and pathway analysis to reveal multiple signaling events associated with B cell activation and differentiation in SLE that were modulated by HDAC6 inhibition. Our results showed a reduced germinal center B cell response, decreased T follicular helper cells and diminished interferon (IFN)-γ production from T helper cells in splenic tissue. Additionally, we found the IFN-α-producing ability of plasmacytoid dendritic cells was decreased along with immunoglobulin isotype switching and the generation of pathogenic autoantibodies. Renal tissue showed decreased immunoglobulin deposition and reduced inflammation as judged by glomerular and interstitial inflammation. The molecular pathways by which B cells become pathogenic PC secreting autoantibodies in SLE are incompletely characterized. RNA sequence data showed that PC development was abrogated and germinal center (GC) formation was greatly reduced. When the HDAC6 inhibitor-treated lupus mouse gene signatures were compared to human lupus patient gene signatures, the results showed numerous immune and inflammatory pathways increased in active human lupus were significantly decreased in the HDAC6 inhibitor treated animals. Pathway analysis suggested alterations in cellular metabolism might contribute to the normalization of lupus mouse spleen genomic signatures, and this was confirmed by direct measurement of the impact of the HDAC6 inhibitor on metabolic activities of murine spleen cells. Taken together, these studies show selective HDAC6 inhibition decreased several parameters of disease pathogenesis in lupus-prone mice. The decrease was in part due to inhibition of B cell development and response. RNA sequence data analysis show HDAC6 inhibition decreases B cell activation signaling pathways and reduces PC differentiation in SLE and suggests that a critical event might be modulation of cellular metabolism.
- The Role of IkZF Factors in Mediating TH1/TFH Development and FlexibilityBharath Krishnan Nair, Sreekumar (Virginia Tech, 2020-01-24)The ability of cells within the adaptive immune system to develop into specialized subsets allow for a robust and tailored immune response in the advent of an infection or injury. Here, CD4+ T-cells are a crucial component within this system, with subsets such as TH1, TH2, TH17, TFH and TREG cells playing vital roles in propagating cell-mediated immunity. For example, TH1 cells are essential in combating intracellular pathogens such as viruses, while TFH cells communicate with B-cells to optimize antibody responses against an invading pathogen. The development (and functionality) of these subsets is ultimately dictated by the appropriate integration of extracellular cues such as cytokines with cell intrinsic transcription factors, thereby promoting the necessary gene profile. Moreover, the observation that T-helper cells could exhibit a flexible nature (i.e having shared gene profiles and effector functions) not only demonstrate the efficiency of our immune system but also how such flexibility could have unintended consequences during adverse events such as autoimmunity. An important mediator of such flexibility is cytokines. However, the complete network of factors that come together to co-ordinate cytokine mediated plasticity remain unknown. Thus, the work in this dissertation hope to delineate the factors that collaborate to regulate cytokine induced T-helper cell flexibility. As such, we see that in the presence of IL-2, the Ikaros Zinc Finger (IkZF) transcription factor Eos is upregulated in TH1 cells, with this factor playing a significant role in promoting regulatory and effector functions of TH1 cells. Moreover, we show that Eos forms a novel protein complex with STAT5 and promotes STAT5 activity in TH1 cells. However, depleting IL-2 from the micro-environment leads to the upregulation of two other members within the IkZF family, Ikaros and Aiolos. Aiolos in turn collaborate with STAT3, induces Bcl-6 expression within these cells, thus promoting these cells to exhibit characteristic features of TFH cells. The work in this dissertation hopes to advance our understanding of the regulatory mechanisms involved in cytokine mediated T-cell flexibility thereby hoping to open new avenues for the development of novel therapeutic strategies in the event of autoimmunity.