URSA: University Research, Scholarship, and Archives

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  • Effect of Calcitriol on the Immunomodulatory Properties and Hyaluronic Acid Metabolic Pathways of Human Mesenchymal Stem Cells

    Braley, Katherine; School of Medicine
    Mesenchymal stem cells (MSCs) are non-hematopoietic stem cells which have remarkable immunomodulatory and tissue reparative properties, sparking clinical interest in their use in regenerative medicine. MSC-mediated immunomodulation occurs primarily via production of soluble factors like indolamine-2,3-dioxygenase (IDO), programmed death ligand-1 (PDL-1), prostaglandin E2 (PGE2), among others which function to inhibit effector immune cell function while promoting regulatory subtypes. Our lab focuses on the role of hyaluronic acid (HA) metabolism and signaling through HA receptor, CD44, in MSC’s ability to modulate the immune system and promote tissue repair. Data from our lab has demonstrated alterations in HA metabolism, production, and signaling in MSCs that have been primed with an inflammatory signal. Emerging research has suggested that calcitriol, the biologically active form of Vitamin D, may modulate soluble factor production by MSCs in response to inflammation. Taken together, we then hypothesized that calcitriol may also augment HA metabolic pathways. We utilized secretomes from Staphylococcal enterotoxin B (SEB)-activated peripheral blood mononuclear cells (PBMCs) to simulate the inflammatory microenvironment. In PBMC supernatant-activated MSCs we saw a consistent upregulation in gene expression of CD44, HA synthase isoform HAS-3, IDO-1, and PDL-1. Preliminary data suggests possible alterations in the molecular weight of hyaluronic acid secreted by activated MSCs when treated with calcitriol and PBMC supernatant when visualized by gel electrophoresis, though further replicates are needed. xi On its own, calcitriol was not able to modulate the alterations seen in HA metabolism in activated MSCs, as there was no statistically significant change in HAS3 gene expression between calcitriol and vehicle at 24-hour time-points. Though, calcitriol was shown to decrease total HA production in activated MSCs, as well as partially restore high molecular weight HA in PBMC supernatant- activated MSCs. Calcitriol was not demonstrated to meaningfully alter gene expression of IDO-1 or PDL-1 compared to PBMC supernatant-treated cells, suggesting that calcitriol does not affect MSC activation by inflammatory stimuli. However, optimization of the calcitriol delivery process and exposure time is necessary. Preliminary results following optimization of calcitriol dose and timing demonstrate a significant alteration in expression of HAS3, though further replicates are needed to confirm this effect. Additional studies investigating the effects of secretomes from MSCs treated with calcitriol on immune cell activity, and co-culturing experiments between MSCs and immune cells in the presence of calcitriol may provide more insight into the role of calcitriol and its effect on the immunomodulatory properties of MSCs.
  • Nursing Student Perceptions of Presence in a Virtual Learning Environment: A Qualitative Description Study

    Thrift, Jason R; Georgia Baptist College of Nursing
    Multifaceted approaches to learning are used for educating student nurses. One common teaching modality in nursing education, simulation, provides hands-on experiences in a safe environment to prepare student nurses for professional roles. High quality simulation standards recommend an engaging immersive experience, with physical, emotional, and conceptual fidelity to clinical practice. Presence is the perception of being there in a simulation as if it were real. Studies have reported improved learning outcomes with increased sense of presence. A simulation modality seldom used in nursing education is virtual reality simulation (VR-Sim) a three dimensional, immersive experience. VR-Sim with head mounted visual and haptic enhancements has the potential to increase presence and improve learning. Student perceptions of presence in VR-Sim is unknown. The purpose of this study was to explore student nurses’ perceptions of presence during simulation. A qualitative description design included a VR-Sim of a patient needing cardiopulmonary resuscitation (CPR). Each participant (N=11) performed two repetitions in the VR-Sim followed by debriefing and a guided interview. The conceptual framework for the study was informed by extant literature including theoretical frameworks. Two research questions guided the study to 1) explore student perceptions of presence in VR-Sim and 2) align findings with current theories of simulation and presence. Braun and Clarke’s (2006) steps for theme development and Saldaña’s (2016) coding informed the data analysis. For Research Question 1, three themes and eight subthemes described participants perceptions of being there in the VR-Sim environment. Findings showed all participants reported experiencing presence during the simulation (Theme: What Brought Me In, What Brought Me Out), but glitches, feel of compressions, and sensing the real physical environment outside the simulation interrupted the experience of presence (Theme: Issues in VR-Sim). Additionally, participants described the experience of learning CPR with the VR-Sim (Theme: Higher Level of Learning). For Research Question 2, the main constructs from the extant theories aligned with the perceptions of participants including ideas about presence, fidelity, individual factors, learning outcomes, and collaboration. The study conceptual model provided a sound framework for continued research of the efficacy of VR-Sim in nursing education.
  • Predictive Analysis of the Immunosuppressive Functionality of Human Bone Marrow Derived Mesenchymal Stem Cells as Cellular Therapeutics

    lipat, ariel joy mann; School of Medicine
    Human Mesenchymal Stem/Stromal Cells (MSCs) of bone marrow carry immunomodulatory and regenerative properties and are being tested as a cellular therapy for inflammatory and degenerative disorders. They are involved with the paracrine secretion of anti-inflammatory cytokines and chemokines and the promotion of anti-inflammation in tissue microenvironments by dampening inflammatory T-cells. However, the mechanism of action of MSCs on T-cells has yet to be understood. Here we aim to identify the pattern of chemokine secretion in human bone marrow MSCs and their regulation and functions on T-cell responses and immune suppression. MSCs were derived from healthy human bone marrow aspirates. MSC secretome was collected systematically under defined cell densities and subjected to multiplex secretome analysis with or without exogenous stimulation to identify inherently secreted MSC chemokines. MSC derived chemokines’ immunosuppressive role on T-cells was further determined with a PBMC and MSC coculture and siRNA chemokine transfection strategies. MSC secretome was further tested on human peripheral blood mononuclear cells (PBMCs) derived from blood and early phosphorylation of signaling molecules in T-cells were specifically analyzed utilizing PhosflowTM technology in flow cytometry. Of thirty tested chemokines nine (CXCL16, CCL2, CXCL6, CCL7, CXCL1, CCL13, CCL5 CXCL2 and CCL1) are secreted inherently by MSCs suggesting that MSC potency and immunosuppressive potential can be determined by the presence of these chemokines. In addition, MSC mediated blocking of T cell proliferation predominantly inversely correlates with chemokines. Knockdown of chemokines have demonstrated that MSC sourced inherent chemokines do not actively play a role in T cell suppression and thus are the bystander predictors of T cell suppression. The present analysis of MSC’s matrix chemokine responses can be deployed in the advanced potency determination of MSCs. As well, little difference was seen between chemokine levels from intestinal organoid secretome samples from IBD and non-IBD cultures. Seven signaling molecules [PLCγ1, PLCγ2, PKCα, JNK, P38 MAPK, Erk ½, pAkt (pS473)] were analyzed for phosphorylation events in T-cells when stimulated with MSC secretome. Our results provided evidence that MSC derived chemokines and secretome predicts T-cell suppression. These mechanistic understandings will help us to improve MSC based cellular therapy.
  • A Comparison of SUMOylation in HK1 and BL41 Cell Lines

    Suarez, Persia; School of Medicine
    Nearly 96% of the population is infected with Epstein Barr virus (EBV), a gammaherpesvirus that results in a life-long infection. EBV lytically infects B lymphocytes and epithelial cells, and it establishes latency in B lymphocytes. Latent EBV infection often evades the host’s immune system; however, the presence of the EBV genome in certain cancers suggests that the virus is associated with approximately 200,000 new cases of cancer, specifically Burkitt’s lymphoma, Hodgkin’s lymphoma (HL), and nasopharyngeal carcinoma (NPC), each year. One cellular process commonly dysregulated in cancers, including EBV-positive lymphomas, is the post-translational modification of lysine residues by the Small Ubiquitin-like Modifier (SUMO), and SUMOylation inhibitors have been proposed to have potential anti-cancer properties. Our recent work focused on the small molecule inhibitor ML-792, which decreases global levels of SUMOylated proteins in EBV-positive and EBV-negative B lymphocytes. Similar experiments repeated with paired EBV-negative and EBV-positive nasopharyngeal cell line HK1 revealed that ML-792 only inhibited SUMOylation processes in the EBV-positive epithelial cells and not in their EBV-negative counterparts. We hypothesized that EBV may differentially modulate SUMOylation processes in epithelial cells when compared with B lymphocytes. This study aims to elaborate on the role of EBV on SUMOylation in epithelial cells. Paired primary B lymphocytes and epithelial cells were examined to determine the expression of the SUMO machinery. Results showed that EBV infection coincided with increased levels of SUMO-modified proteins and the SUMO-activating enzyme (SAE1 and SAE2), but not the SUMO-conjugating enzyme (Ubc9). Global levels of SUMOylated proteins increased in EBV-positive HK1 cells when compared with their EBV-negative counterparts. However, RNA and protein levels of the SUMO machinery varied greatly, which led us to ask if the confluence of the epithelial cells affected EBV-mediated changes in cells. Results demonstrated that RNA levels of the SUMO machinery significantly increased in sub-confluent EBV-positive HK1 cells, but these changes were not as apparent at the protein level. EBV-medicated changes in the SUMO machinery were more apparent at the protein level in confluent cells. To mimic a more physiological environment, EBV-negative and EBV-positive HK1 cells were also grown using a modified air-liquid interface method to model the human airway. Results showed that the presence of EBV corresponded with increased levels of the SUMO-activating enzyme and the SUMO-conjugating enzyme. Furthermore, the pattern of SUMOylated proteins changed in EBV-positive cells when compared with their EBV-negative counterparts. Taken together, our findings demonstrate that EBV does manipulate the SUMO machinery in epithelial cells, but not to the same extent as it does in lymphocytes. Therefore, additional studies are needed to better understand the effect of EBV on global levels of SUMOylated proteins in epithelial cells, which could identify if SUMOylation inhibitors have a therapeutic potential in the treatment of EBV-positive epithelial cancers.
  • Persistence as Resistance: A Phenomenological Narrative Analysis of the Africultural Coping and Motivational Strategies of African American College Students

    Scott, Miraca Joann; Tift College of Education
    Despite decades of institutional efforts to mitigate African American college student first-year attrition, this population continues to have the lowest graduation rates compared to other races and ethnicities (National Center for Education Statistics, 2021). Historically, the collegiate first and fourth years have received more attention from student success researchers due to their direct connection to institutional enrollment and graduation rates (Gahagan & Hunter, 2006); however, more recent research has indicated that the collegiate sophomore year poses the most significant threat to student retention and graduation rates (Perez, 2020). This qualitative study explored how racial-cultural identity salience, culture-specific coping behaviors, and motivation influenced how Afrocentric African American college students avoided college departure to persist to junior year successfully. Framed within an Afrocentric theoretical framework, a phenomenological narrative methodology was employed to assess students’ perceptions of which coping behaviors and motivational factors helped them overcome challenges experienced during their sophomore year at a southern public, four-year predominantly white institution. Six participants were recruited using criterion and snowball sampling techniques. Data analysis revealed 22 subthemes which were consolidated into six emergent themes: 1) Achievement-oriented Motivation, 2) Soundproofing, 3) Centripetal Autonomy, 4) Centripetal Grouping, 5) Self-Care, and 6) Self-Monitoring. Findings suggest an inextricable link between Black sophomores’ need for intraracial connection, the salience of their racial and cultural identity as African American or Black, and their community-centered motivations for persevering during their sophomore year. Implications for practice include establishing wrap-around support for African American sophomore students, championing and amplifying Black sophomore voices, and integrating culturally-aligned theory into higher education policy. For a representative body of literature, researchers are encouraged to abandon using theoretical models that embody Euro-American values when studying Black students. Implications of this study suggest future studies should be positioned using an Afrocentric theoretical framework to illuminate the needs of African American students.

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