Browsing by Subject "Macrophage"

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An apoptotic body-inspired nanoparticle to modulate inflammatory macrophages
(2021-03-15) Kraynak, Chelsea Amanda; Suggs, Laura J.; Baker, Aaron; Cui, Zhengrong; Farrar, Roger
Chronic inflammation is a significant pathological process found in a range of disease states. Treatments to reduce inflammation in this family of diseases may improve symptoms and disease progression, but are largely limited by variable response rates, cost, and off-target effects. Macrophages are implicated in many inflammatory diseases for their critical role in the maintenance and resolution of inflammation. Macrophages exhibit significant plasticity to direct the inflammatory response by taking on an array of pro- and anti-inflammatory phenotypes based on extracellular cues. One robust anti-inflammatory physiologic cue is the engulfment of apoptotic cells. In this work, we have developed a nanoparticle to target and reduce macrophage-mediated inflammation by mimicking the anti-inflammatory effect of apoptotic cell engulfment. The nanoparticle, comprised of a poly(lactide-co-glycolide) core, is coated in phosphatidylserine (PS)-supplemented cell plasma membrane to emulate key characteristics of the apoptotic cell surface. We demonstrate that this particle can reduce the production of pro-inflammatory cytokines and drive an anti-inflammatory phenotype shift without the use of small molecules or other drugs. We additionally functionalized the particle surface with an acid-sensitive polyethylene glycol (PEG) moiety to increase the delivery of our particles to sites of chronic inflammation in a mouse model. Particles are preferentially taken up by macrophages at the site of inflammation to promote an anti-inflammatory phenotype shift. The development of a nanoparticle to drive this pro-to-anti-inflammatory macrophage phenotype transition, through the use of a physiologic anti-inflammatory pathway, illustrates a new potential strategy in the design of therapeutics for chronic inflammation.
Development and application of optical imaging techniques in diagnosing cardiovascular disease
(2012-05) Wang, Tianyi, 1982-; Milner, Thomas E.; Feldman, Marc; Johnston, Keith; Dunn, Andrew; Tunnell, James
Atherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques. Tissue phantoms and macrophage cell cultures were used to investigate the capability of nanorose as an imaging contrast agent to target macrophages. Ex vivo aorta segments from a rabbit model of atherosclerosis after intravenous nanorose injection were imaged by optical coherence tomography (OCT), photothermal imaging (PTW) and two-photon luminescence microscopy (TPLM), respectively. OCT images depicted detailed surface structure of atherosclerotic plaques. PTW images identified nanorose-loaded macrophages (confirmed by co-registration of a TPLM image and corresponding RAM-11 stain on a histological section) associated with lipid deposits at multiple depths. TPLM images showed three-dimensional distribution of nanorose-loaded macrophages with a high spatial resolution. Imaging results suggest that superficial nanorose-loaded macrophages are distributed at shoulders on the upstream side of atherosclerotic plaques at the edges of lipid deposits. Combination of OCT with PTW or TPLM can simultaneously reveal plaque structure and composition, permitting assessment of plaque vulnerability during cardiovascular interventions.
Development of a three dimensional in vitro vascularized tumor platform for investigating the role of the tumor stroma on inflammatory breast cancer
(2019-05-15) Gadde, Manasa; Rylander, Marissa Nichole, 1978-; Brock, Amy; Woodward, Wendy; Yankeelov, Thomas
Inflammatory breast cancer (IBC) is an aggressive disease with poor prognosis, accounting for 10% of breast cancer mortality. A contributing factor to this is the lack of therapeutics targeting IBC. IBC exhibits clinical features that differentiate it from non inflammatory breast cancers (nIBC) including swollen and enlarged breasts, skin redness, and diffuse distribution of IBC cells through the breast tissue. Even with the mentioned distinguishing features, as of now there are no differentiating molecular or histological markers that separate IBC from nIBC. Recent research has shown tumor stromal interactions to be the driving force in IBC with roles in promoting tumor development and growth, angiogenesis, and metastasis to distant tissues. Better understanding of these interactions is necessary for discovery of IBC distinct targeting markers and development of IBC specific treatments. We developed an in vitro vascularized IBC platform that allows for investigation of tumor-stromal interactions in IBC, specifically, we focused on the interactions between IBC cells, tumor associated macrophages (TAMs), and blood and lymphatic vasculatures. The platform allowed for spatiotemporal tracking of cellular interactions and responses in a physiologically relevant setting. Using the in vitro vascularized IBC platform, we showed the presence of triple negative IBC cells SUM149 resulted in a permeable blood vessel vasculature and decreased endothelial coverage of the vessel lumen while HER2+ IBC cells MDA-IBC3 promoted and supported angiogenic sprouting of the blood vessel and increased expression of angiogenic cytokines. Lymphatic vessels showed an increased permeability compared to blood vessels both with and without IBC cells as well as a lack of angiogenic sprouting and decreased matrix remodeling. When TAMs were incorporated into the blood vessel platforms, we observed an increase in the number of new vessel sprouts, increased permeability of the vessel, increased matrix porosity, and intravasation of MDA-IBC3 cells. In the in vitro IBC platforms with lymph vessels, TAMs induced lymphangiogenesis, albeit at a slower rate compared to blood vessel platforms, and increased matrix porosity. In conclusion, the work presented here brings us closer to uncovering the mechanisms that drive IBC and discovery of IBC specific therapeutic targets.
Influence of insulin-like growth factor-I on skeletal muscle regeneration
(2012-12) Hammers, David Wayne; Farrar, Roger P; Suggs, Laura J; Adamo, Martin L; Sweeney, H. Lee; Thompson, Wesley J; Ivy, John L
Skeletal muscle regeneration involves a tightly regulated coordination of cellular and signaling events to remodel and repair the site of injury. When this coordination is perturbed, the regenerative process is impaired. The expression of insulin-like growth factor-I (IGF-I) is robust in the typical muscle regenerative program, promoting cell survival and increasing myoblast activity. In this project, we found that severely depressed IGF-I expression and intracellular signaling in aged skeletal muscle coincided with impaired regeneration from ischemia/reperfusion (I/R). To hasten muscle regeneration, we developed the PEGylated fibrin gel (PEG-Fib) system as a means to intramuscularly deliver IGF-I in a controlled manner to injured muscle. This strategy resulted in greatly improved muscle function and histological assessment following 14 days of reperfusion, which are likely mediated by improved myofiber survival. Recent evidence suggests macrophages (MPs) are responsible for the upregulation of IGF-I following injury, therefore we developed a rapid, reproducible, and cost-effective model of investigating MP profiles in injured muscle via flow cytometry. Using information gathered from this model, we found that increasing the number of a non-inflammatory MP population improves the recovery of muscle from I/R. These data demonstrate that immunomodulatory therapies have the potential to greatly improve the recovery of skeletal muscle from injury.
The immunoregulation of dying cell components on macrophages and their therapeutic potential in ischemic muscle regeneration
(2021-11-29) Huang, Wenbai; Suggs, Laura J.; Farrar, Roger P.; Stone, Audrey; Zoldan, Janet; Ehrlich, Lauren
Skeletal muscle regeneration after serious injury highly relies on local stem cell proliferation and differentiation which are processes that are tightly regulated by macrophages. Utilization of tissue-derived and ex-vivo expanded mesenchymal stromal cells (MSCs) in skeletal muscle regeneration has been heavily researched for the past decades but the results have not been consistent and the potential therapeutic mechanism or mechanisms remains unclear. In this project, we characterized the cell components of MSCs after inducing cell death under different conditions and confirmed their anti-inflammatory and pro-regenerative effects on macrophage polarization in vitro. We further investigated the underlying mechanisms of macrophage polarization by different components resulting from cell death. We found potent therapeutic effects from freeze and thaw (F&T) induced cell debris, and these effects are dependent on the externalization of phosphatidylserine (PtS) on the plasma membrane. In contrast, effects from the supernatant of F&T induced cell death primarily depends on the released protein content. Based on the findings from our in vitro studies, we applied the F&T induced cell supernatant to an animal model of peripheral artery disease (PAD) to treat muscle injury caused by a severe ischemia. This treatment resulted in significantly improved muscle functional and histological recovery as well as increased blood flow to the affected muscles 2 weeks after the injury procedure, validating the therapeutic potential of cell components of MSCs induced by F&T process, obviating the need for a viable cell population to treat injury. This result has implications for cell-free therapeutic approaches for ischemic injury to muscle.
Treating Macrophages with Anti-inflammatory Nanoparticles as a Strategy to Improve Muscle Repair
(2019-05) Yan, Derek; Suggs, Laura
The macrophage is an immune cell that is involved in host defense. More recent research, however, has revealed that they also play a central role in mediating the skeletal muscle regenerative process. Upon muscle injury, macrophages are recruited to the damaged site and begin differentiating into a pro-inflammatory phenotype, known as the M1 phenotype. M1 macrophages secrete inflammatory cytokines to facilitate the acute response to muscle injury, and are characterized by phagocytosis of cellular debris and exhibiting strong microbicidal activity. However, another hallmark of inflammatory macrophages is the metabolism of arginine into nitric oxide (NO), which is further metabolized into other reactive oxygen species such as superoxide and peroxynitrite. If left unchecked, prolonged macrophage inflammation leads to muscle cell lysis due to the persistence of reactive oxygen radicals. The capacity of macrophages to stimulate myogenic cells to proliferate is also reduced if inflammation persists. To improve muscle regeneration, we have developed and synthesized a nanoparticle formulation that allows controlled reduction of macrophage inflammatory phenotype. Previous published studies have shown lactic acid and magnesium as chemical agents that attenuate M1 phenotype in macrophages. We developed a poly-lactic-co-glycolic acid (PLGA) nanoparticle emulsified with magnesium sulfate to attenuate the inflammatory phenotype in a murine macrophage cell line. This Magnesium-PLGA nanoparticle has been optimized to be uptaken by macrophages without affecting cell viability. We hope that these contributions make the first steps towards developing an injectable therapy to modulate macrophage phenotype, and can be used in conjunction with existing treatments to improve skeletal muscle repair following injury.