Browsing by Author "Ousman, Shalina S"

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    Deriving Conventional Dendritic Cells from ER-Hoxb8 Immortalized Hematopoietic Stem and Progenitor Cells & Evaluating CD36 Dependent Uptake of Oxidized Low-Density Lipoprotein in Type 1 Conventional Dendritic Cells
    (2024-04-19) Moore, Melanie R; Canton, Johnathan Anias; Yates, Robin M; Jirik, Frank Robert; Ousman, Shalina S; Devinney, Rebekah P
    Dendritic cells (DCs) play a crucial role in immunity, acting as professional antigen presenting cells (APCs) that bridge the innate and adaptive immune systems through antigen presentation. Among DC subtypes, type 1 conventional dendritic cells (cDC1s) excel in cross-presentation, which allows for the loading of processed antigen onto MHC I and is believed to be the primary means by which naïve CD8 T cells are converted into effector CD8 T cells. Despite comprising a small fraction of the total leukocyte population, cDC1s are disproportionately important in tumor environments, where their presence correlates with improved patient survival and treatment response across multiple cancers. However, studying cDCs poses challenges due to limited tools and inefficient methods for obtaining primary murine cDC1s. To address this, we developed a system that consistently provides high yields of cDCs, utilizing an easily accessible cell line of immortalized cDC progenitors. Using fluorescence activated cell sorting (FACS), we enriched an FLT3L-driven Hoxb8-immortalized hematopoietic stem and progenitor (HSPC) cell line to obtain a pre-cDC progenitor population. We then optimized existing methods of obtaining cDCs from bone marrow to consistently obtain cDC populations from our immortalized cDC progenitor cell line. Subsequently, we confirmed that this approach yields cDC subset compositions comparable to those obtained using established primary bone marrow protocols. Additionally, we investigated the role of CD36, a receptor for oxidized low-density lipoprotein (oxLDL), in cDC1s. We demonstrated a significant reduction in oxLDL uptake in cDCs lacking CD36, as well as in cDCs under the influence of macropinocytosis inhibiting drugs, suggesting that CD36-assisted macropinocytosis facilitates oxLDL uptake in cDC1s, ultimately leading to lipid body formation akin to macrophage foam cells. After replicating a commonly observed decrease in cross-presentation abilities in lipid-laden cDC1s, we provided a potential mechanism for this impairment, suggesting that a disruption in the recruitment of apolipoprotein 7c (APOL7C), which is vital to successful cross presentation, may be attributed to a significant oxLDL-dependent delay in phagosomal maturation. In summary, our research sheds light on the interplay between CD36, oxLDL, and cDC1s, offering valuable insights for future cDC studies and providing a promising tool for investigating their roles in immunity and disease.
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    Incidence, prevalence, and occurrence rate of infection among adults hospitalized after traumatic brain injury: study protocol for a systematic review and meta-analysis
    (BioMed Central, 2013-08-24) Scott, Brittney NV; Roberts, Derek J; Robertson, Helen Lee; Kramer, Andreas H; Laupland, Kevin B; Ousman, Shalina S; Kubes, Paul; Zygun, David A
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    Presence and activation of pro-inflammatory macrophages are associated with CRYAB expression in vitro and after peripheral nerve injury
    (2021-03-24) Lim, Erin-Mai F; Hoghooghi, Vahid; Hagen, Kathleen M; Kapoor, Kunal; Frederick, Ariana; Finlay, Trisha M; Ousman, Shalina S
    Abstract Background Inflammation constitutes both positive and negative aspects to recovery following peripheral nerve injury. Following damage to the peripheral nervous system (PNS), immune cells such as macrophages play a beneficial role in creating a supportive environment for regrowing axons by phagocytosing myelin and axonal debris. However, a prolonged inflammatory response after peripheral nerve injury has been implicated in the pathogenesis of negative symptoms like neuropathic pain. Therefore, the post-injury inflammation must be carefully controlled to prevent secondary damage while allowing for regeneration. CRYAB (also known as alphaB-crystallin/HSPB5) is a small heat shock protein that has many protective functions including an immunomodulatory role in mouse models of multiple sclerosis, spinal cord injury, and stroke. Because its expression wanes and rebounds in the early and late periods respectively after PNS damage, and CRYAB null mice with sciatic nerve crush injury display symptoms of pain, we investigated whether CRYAB is involved in the immune response following PNS injury. Methods Sciatic nerve crush injuries were performed in age-matched Cryab knockout (Cryab−/−) and wildtype (WT) female mice. Nerve segments distal to the injury site were processed by immunohistochemistry for macrophages and myelin while protein lysates of the nerves were analyzed for cytokines and chemokines using Luminex and enzyme-linked immunosorbent assay (ELISA). Peritoneal macrophages from the two genotypes were also cultured and polarized into pro-inflammatory or anti-inflammatory phenotypes where their supernatants were analyzed for cytokines and chemokines by ELISA and protein lysates for macrophage antigen presenting markers using western blotting. Results We report that (1) more pro-inflammatory CD16/32+ macrophages are present in the nerves of Cryab−/− mice at days 14 and 21 after sciatic nerve crush-injury compared to WT counterparts, and (2) CRYAB has an immunosuppressive effect on cytokine secretion [interleukin (IL)-β, IL-6, IL-12p40, tumor necrosis factor (TNF)-α] from pro-inflammatory macrophages in vitro. Conclusions CRYAB may play a role in curbing the potentially detrimental pro-inflammatory macrophage response during the late stages of peripheral nerve regeneration.
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    Spinal Oxygen Sensors: location, function and mechanism
    (2021-04-05) Orsi Barioni, Nicole; Wilson, Richard JA.; Whelan, Patrick.; Zocal, Daniel B; Ousman, Shalina S; Thompson, Roger J; Gordon, Grant RJ.
    In hypoxic conditions, the mammalian body composes cardiorespiratory responses aimed to increase oxygen supply to vital organs. Although the carotid bodies are the primary oxygen chemoreceptors for breathing, data in the literature show that hypoxia-triggered cardiovascular responses remain in their absence, suggesting the existence of an additional hypoxia sensor responsible to elicit those responses. In the present work, my objectives were to determine 1) the origin of the cardiovascular responses to hypoxia in the absence of the carotid bodies; 2) the function of these oxygen sensors in rescuing cardiorespiratory control under hypoxia; and 3) the oxygen sensing mechanism through which these cells compose the hypoxic response. Using in vivo, in situ, en bloc and patch clamp preparations combined with pharmacological, immunological and genetic approaches, our data show that thoracic spinal preganglionic neurons (SPNs) are highly oxygen sensitive and this sensitivity is not mediated by surrounding glia (although spinal glia also seem to be oxygen sensitive). Additionally, these spinal oxygen sensors (SOS) are not only capable of increasing phrenic activity independent of the brainstem, but also modulating the brainstem’s process of gasp generation under asphyxia by increasing sympathetic output and promoting autoresuscitation – in some cases producing gasps on its own. Furthermore, our results suggest that the SOS are equipped with a novel oxygen sensing mechanism involving neuronal nitric oxide synthase (NOS1), expressed abundantly in SPNs. The high expression levels of NOS1 in SPNs causes high levels of NADPH consumption. However, as oxygenation decays in hypoxia, NOS1 becomes dormant due to its high KmO2, making NADPH available for NOX2 in the production of ROS. The increased ROS concentration inside the SPNs triggers TRP channels and IP3R, culminating in elevated intracellular calcium and, consequently, neuronal depolarization. In conclusion, the present thesis investigates a spinal oxygen sensor which potentially contributes to survival behaviours and appears to use a novel oxygen sensing mechanism.
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    The immune response and aging in chronic inflammatory demyelinating polyradiculoneuropathy
    (2021-03-22) Hagen, Kathleen M; Ousman, Shalina S
    Abstract Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) consists of various autoimmune subtypes in which the peripheral nervous system (PNS) is attacked. CIDP can follow a relapsing-remitting or progressive course where the resultant demyelination caused by immune cells (e.g., T cells, macrophages) and antibodies can lead to disability in patients. Importantly, the age of CIDP patients has a role in their symptomology and specific variants have been associated with differing ages of onset. Furthermore, older patients have a decreased frequency of functional recovery after CIDP insult. This may be related to perturbations in immune cell populations that could exacerbate the disease with increasing age. In the present review, the immune profile of typical CIDP will be discussed followed by inferences into the potential role of relevant aging immune cell populations. Atypical variants will also be briefly reviewed followed by an examination of the available studies on the immunology underlying them.