IU Indianapolis ScholarWorks :: Browsing by Author "Pelus, Louis M."

Browsing by Author "Pelus, Louis M."

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Aging negatively impacts the ability of megakaryocytes to stimulate osteoblast proliferation and bone mass
(Elsevier, 2019) Maupin, Kevin A.; Himes, Evan R.; Plett, Artur P.; Chua, Hui Lin; Singh, Pratibha; Ghosh, Joydeep; Mohamad, Safa F.; Abeysekera, Irushi; Fisher, Alexa; Sampson, Carol; Hong, Jung-Min; Childress, Paul; Alvarez, Marta; Srour, Edward F.; Bruzzaniti, Angela; Pelus, Louis M.; Orschell, Christie M.; Kacena, Melissa A.; Orthopaedic Surgery, School of Medicine
Osteoblast number and activity decreases with aging, contributing to the age-associated decline of bone mass, but the mechanisms underlying changes in osteoblast activity are not well understood. Here, we show that the age-associated bone loss critically depends on impairment of the ability of megakaryocytes (MKs) to support osteoblast proliferation. Co-culture of osteoblast precursors with young MKs is known to increase osteoblast proliferation and bone formation. However, co-culture of osteoblast precursors with aged MKs resulted in significantly fewer osteoblasts compared to co-culture with young MKs, and this was associated with the downregulation of transforming growth factor beta. In addition, the ability of MKs to increase bone mass was attenuated during aging as transplantation of GATA1low/low hematopoietic donor cells (which have elevated MKs/MK precursors) from young mice resulted in an increase in bone mass of recipient mice compared to transplantation of young wild-type donor cells, whereas transplantation of GATA1low/low donor cells from old mice failed to enhance bone mass in recipient mice compared to transplantation of old wild-type donor cells. These findings suggest that the preservation or restoration of the MK-mediated induction of osteoblast proliferation during aging may hold the potential to prevent age-associated bone loss and resulting fractures.
Alterations to maternal cortical and trabecular bone in multiparous middle-aged mice
(Hylonome, 2017-11) Gu, Alex; Sellamuthu, Rajendran; Himes, Evan; Childress, Paul J.; Pelus, Louis M.; Orschell, Christie M.; Kacena, Melissa A.; Orthopaedic Surgery, School of Medicine
Objectives: During the reproductive cycle, altered calcium homeostasis is observed due to variable demand for mineral requirements. This results in increased bone resorption during the time period leading up to parturition and subsequent lactation. During lactation, women will lose 1-3% of bone mineral density per month, which is comparable to the loss experienced on an annual basis post-menopausal. The purpose of this study was to determine the effect of parity on bone formation in middle-aged mice. Methods: Mice were mated and grouped by number of parity and compared with age matched nulliparous controls. Measurements were taken of femoral trabecular and cortical bone. Calcium, protein and alkaline phosphatase levels were also measured. Results: An increase in trabecular bone mineral density was observed when comparing mice that had undergone parity once to the nulliparous control. An overall decrease in trabecular bone mineral density was observed as parity increased from 1 to 5 pregnancies. No alteration was seen in cortical bone formation. No difference was observed when calcium, protein and alkaline phosphatase levels were assessed. Conclusions: This study demonstrates that number of parity has an impact on trabecular bone formation in middle-aged mice, with substantial changes in bone density seen among the parous groups.
Bleeding the laboratory mouse: Not all methods are equal
(Elsevier, 2016-02) Hoggatt, Jonathan; Hoggatt, Amber F.; Tate, Tiffany A.; Fortman, Jeffrey; Pelus, Louis M.; Microbiology and Immunology, School of Medicine
The laboratory mouse is the model most frequently used in hematologic studies and assessment of blood parameters across a broad range of disciplines. Often, analysis of blood occurs in a nonterminal manner. However, the small body size of the mouse limits collection based on volume, frequency, and accessible sites. Commonly used sites in the mouse include the retro-orbital sinus, facial vein, tail vein, saphenous vein, and heart. The method of blood acquisition varies considerably across laboratories and is often not reported in detail. In this study, we report significant alterations in blood parameters, particularly of total white blood cells, specific populations of dendritic cells and myeloid-derived suppressor cells, and hematopoietic progenitor cells, as a result of site and manner of sampling. Intriguingly, warming of mice prior to tail bleeding was found to significantly alter blood values. Our findings suggest that the same method should be used across an entire study, that mice should be warmed prior to tail bleeds to make levels uniform, and that accurate description of bleeding methods in publications should be provided to allow for interpretation of comparative reports and inter- and intralaboratory experimental variability.
Cardiac and Renal Delayed Effects of Acute Radiation Exposure: Organ Differences in Vasculopathy, Inflammation, Senescence and Oxidative Balance
(Radiation Research Society, 2019-05) Unthank, Joseph L.; Ortiz, Miguel; Trivedi, Hina; Pelus, Louis M.; Sampson, Carol H.; Sellamuthu, Rajendran; Fisher, Alexa; Chua, Hui Lin; Plett, Artur; Orschel, Christie M.; Cohen, Eric P.; Miller, Steven J.; Surgery, School of Medicine
We have previously shown significant pathology in the heart and kidney of murine hematopoietic-acute radiation syndrome (H-ARS) survivors of 8.7-9.0 Gy total-body irradiation (TBI). The goal of this study was to determine temporal relationships in the development of vasculopathy and the progression of renal and cardiovascular delayed effects of acute radiation exposure (DEARE) at TBI doses less than 9 Gy and to elucidate the potential roles of senescence, inflammation and oxidative stress. Our results show significant loss of endothelial cells in coronary arteries by 4 months post-TBI (8.53 or 8.72 Gy of gamma radiation). This loss precedes renal dysfunction and interstitial fibrosis and progresses to abnormalities in the arterial media and adventitia and loss of coronary arterioles. Major differences in radiation-induced pathobiology exist between the heart and kidney in terms of vasculopathy progression and also in indices of inflammation, senescence and oxidative imbalance. The results of this work suggest a need for different medical countermeasures for multiple targets in different organs and at various times after acute radiation injury to prevent the progression of DEARE.
CD166 regulates human and murine hematopoietic stem cells and the hematopoietic niche
(American Society of Hematology, 2014-07-24) Chitteti, Brahmananda Reddy; Kobayashi, Michihiro; Cheng, Yinghua; Zhang, Huajia; Poteat, Bradley A.; Broxmeyer, Hal E.; Pelus, Louis M.; Hanenberg, Helmut; Zollman, Amy; Kamocka, Malgorzata M.; Carlesso, Nadia; Cardoso, Angelo A.; Kacena, Melissa A.; Srour, Edward F.; Department of Medicine, IU School of Medicine
We previously showed that immature CD166(+) osteoblasts (OB) promote hematopoietic stem cell (HSC) function. Here, we demonstrate that CD166 is a functional HSC marker that identifies both murine and human long-term repopulating cells. Both murine LSKCD48(-)CD166(+)CD150(+) and LSKCD48(-)CD166(+)CD150(+)CD9(+) cells, as well as human Lin(-)CD34(+)CD38(-)CD49f(+)CD166(+) cells sustained significantly higher levels of chimerism in primary and secondary recipients than CD166(-) cells. CD166(-/-) knockout (KO) LSK cells engrafted poorly in wild-type (WT) recipients and KO bone marrow cells failed to radioprotect lethally irradiated WT recipients. CD166(-/-) hosts supported short-term, but not long-term WT HSC engraftment, confirming that loss of CD166 is detrimental to the competence of the hematopoietic niche. CD166(-/-) mice were significantly more sensitive to hematopoietic stress. Marrow-homed transplanted WT hematopoietic cells lodged closer to the recipient endosteum than CD166(-/-) cells, suggesting that HSC-OB homophilic CD166 interactions are critical for HSC engraftment. STAT3 has 3 binding sites on the CD166 promoter and STAT3 inhibition reduced CD166 expression, suggesting that both CD166 and STAT3 may be functionally coupled and involved in HSC competence. These studies illustrate the significance of CD166 in the identification and engraftment of HSC and in HSC-niche interactions, and suggest that CD166 expression can be modulated to enhance HSC function.
Defining the mechanism of prostaglandin E₂-enhanced hematopoietic stem and progenitor cell homing
(2014-04-02) Speth, Jennifer M.; Pelus, Louis M.; Broxmeyer, Hal E.; Harrington, Maureen A.; Ivan, Mircea; Srour, Edward F.
Hematopoietic stem cell (HSC) transplantation is a lifesaving therapy for a number of hematological disorders. However, to be effective, transplanted HSCs must efficiently “home” to supportive niches within the bone marrow. Limited HSC number and poor function are complications of transplant in some circumstances, and can lead to delayed engraftment and immune reconstitution, or in some cases, bone marrow failure. Enhancing HSC homing is a strategy to improve stem cell transplantation efficiency. We have previously shown that ex vivo treatment of mouse or human HSCs with 16-16 dimethyl PGE2 (dmPGE2) increases their bone marrow homing efficiency and engraftment, resulting in part from upregulation of surface CXCR4 expression. We now show that pulse-treatment of mouse or human HSPCs with dmPGE2 stabilizes HIF1α in HSPCs, and that similar treatment with the hypoxia mimetic DMOG produces analogous effects to dmPGE2 on HSPC CXCR4 expression and homing. This suggests that HIF1α is responsible for PGE2’s enhancing effects on HSPCs. Pharmacological inhibition of HIF1α stabilization in vitro with Sodium Nitroprusside (SNP), confirms the requirement of HIF1α for dmPGE2-enhanced migration and CXCR4 upregulation. Additionally, we confirm the requirement for HIF1α in dmPGE2-enhanced in vivo homing using a conditional knockout mouse model of HIF1α gene deletion. Finally, we validate that the hypoxia response element located 1.3kb from the transcriptional start site within the CXCR4 promoter is required for enhanced CXCR4 expression after PGE2 treatment. Interestingly, we also observe an increase in the small GTPase Rac1 after dmPGE2 treatment, as well as a defect in PGE2-enhanced migration and CXCR4 expression in Rac1 knockout HSPCs. Using state-of-the-art imaging technology we, confirm an increase in Rac1 and CXCR4 colocalization after dmPGE2 treatment that likely explains enhanced sensitivity of PGE2-treated HSPCs to SDF-1. Taken together, these results define a precise mechanism through which ex vivo pulse treatment of HSPC with dmPGE2 enhances HSPC function through alterations in cell motility and homing, and describe a role for hypoxia and HIF1α in enhancement of hematopoietic transplantation.
Eicosanoid Regulation of Hematopoietic Stem and Progenitor Cell Function
(2010-07-21T19:13:29Z) Hoggatt, Jonathan G.; Pelus, Louis M.; Broxmeyer, Hal E.; Clapp, D. Wade; Srour, Edward
Adult hematopoietic stem cells (HSC) are routinely used to reconstitute hematopoiesis after myeloablation; however, transplantation efficacy and multilineage reconstitution can be limited by inadequate HSC number, or poor homing, engraftment or self-renewal. We have demonstrated that mouse and human HSC express prostaglandin E2 (PGE2) receptors, and that short-term ex vivo exposure of HSC to PGE2 enhances their homing, survival and proliferation, resulting in increased long-term repopulating cell and competitive repopulating unit (CRU) frequency. HSC pulsed with PGE2 are more competitive, as determined by head-to-head comparison in a competitive transplantation model. Enhanced HSC frequency and competitive advantage is stable and maintained upon multiple serial transplantations, with full multi-lineage reconstitution. PGE2 increases HSC CXCR4 mRNA and surface expression and enhances their migration to SDF-1α in vitro and homing to bone marrow in vivo and stimulates HSC entry into and progression through cell cycle. In addition, PGE2 enhances HSC survival, associated with an increase in Survivin mRNA and protein expression and reduction in intracellular active caspase-3. While PGE2 pulse of HSC promotes HSC self-renewal, blockade of PGE2 biosynthesis with non-steroidal anti-inflammatory drugs (NSAIDs) results in expansion of bone marrow hematopoietic progenitor cells (HPC). We co-administered NSAIDs along with the mobilizing agent granulocyte-colony stimulating factor (G-CSF) and evaluations of limiting dilution transplants, assays monitoring neutrophil and platelet recoveries, and secondary transplantations, clearly indicate that NSAIDs facilitate mobilization of a hematopoietic graft with superior functional activity compared to the graft mobilized by G-CSF alone. Enhanced mobilization has also been confirmed in baboons mobilized with G-CSF and a NSAID. Increases in mobilization are the result of a reduction of signaling through the PGE2 receptor EP4, which results in marrow expansion and reduction in the osteoblastic HSC niche. We also identify a new role for cannabinoids, an eicosanoid with opposing functions to PGE2, in hematopoietic mobilization. Additionally, we demonstrate increased survival in lethally irradiated mice treated with PGE2, NSAIDs, or the hypoxia mimetic cobalt chloride. Our results define novel mechanisms of action whereby eicosanoids regulate HSC and HPC function, and characterize novel translational strategies for hematopoietic therapies.
Enhancing Hematopoietic Stem Cell Transplantation Efficacy by Mitigating Oxygen Shock
(Elsevier, 2015-06-18) Mantel, Charlie R.; O'Leary, Heather A.; Chitteti, Brahmananda R.; Huang, XinXin; Cooper, Scott; Hangoc, Giao; Brustovetsky, Nickolay; Srour, Edward F.; Lee, Man-Ryul; Messina-Graham, Steve; Haas, David M.; Falah, Nadia; Kapur, Reuben; Pelus, Louis M.; Bardeesy, Nabeel; Fitamant, Julien; Ivan, Mircea; Kim, Kye-Seong; Broxmeyer, Hal E.; Department of Microbiology & Immunology, IU School of Medicine
Hematopoietic stem cells (HSCs) reside in hypoxic niches within bone marrow and cord blood. Yet, essentially all HSC studies have been performed with cells isolated and processed in non-physiologic ambient air. By collecting and manipulating bone marrow and cord blood in native conditions of hypoxia, we demonstrate that brief exposure to ambient oxygen decreases recovery of long-term repopulating HSCs and increases progenitor cells, a phenomenon we term extraphysiologic oxygen shock/stress (EPHOSS). Thus, true numbers of HSCs in the bone marrow and cord blood are routinely underestimated. We linked ROS production and induction of the mitochondrial permeability transition pore (MPTP) via cyclophilin D and p53 as mechanisms of EPHOSS. The MPTP inhibitor cyclosporin A protects mouse bone marrow and human cord blood HSCs from EPHOSS during collection in air, resulting in increased recovery of transplantable HSCs. Mitigating EPHOSS during cell collection and processing by pharmacological means may be clinically advantageous for transplantation.
The Exploration of an Effective Medical Countermeasure Enhancing Survival and Hematopoietic Recovery and Preventing Immune Insufficiency in Lethally-Irradiated Mice
(2020-08) Wu, Tong; Orschell, Christie M.; Basile, David P.; Unthank, Joseph L.; Haneline, Laura S.; Pelus, Louis M.; MacVittie, Thomas J.
There is an urgent demand for effective medical countermeasures (MCM) in the event of high-dose radiation exposure ranging from nuclear plant disasters to potential nuclear warfare. Victims of lethal-dose radiation exposure face multi-organ injuries including the hematopoietic acute radiation syndrome (H-ARS) and the delayed effects of acute radiation exposure (DEARE) years after irradiation. Defective lymphocyte reconstitution and its subsequent immune insufficiency are some of the most serious consequences of H-ARS and DEARE. In order to investigate potential MCMs to protect or mitigate these radiation injuries, the prolonged tissue-specific immunosuppression at all levels of lymphocyte development in established murine H-ARS and DEARE models was defined, along with unique sex-related and age-related changes present in some tissues but not others. The “double hits” of irradiation and age-related stress on lymphopoiesis led to significant myeloid skew and long-term immune involution. Different kinds and different combinations of hematopoietic growth factors, some in combination with angiotensin converting enzyme inhibitor, were administered to lethally irradiated mice. These radiomitigators were found to significantly increase survival and enhance hematopoiesis in H-ARS, but they did little to alleviate the severity of DEARE including immune insufficiency. 16,16 dimethyl-prostaglandin E2 (dmPGE2), a long-acting formulation of PGE2 with similar biological effects as PGE2, was found to enhance survival and hematopoiesis in lethal-irradiated mice when used as radiomitigator or radioprotectant. The optimum time window for administration of radioprotectant and radiomitigator dmPGE2 was defined, which is -3hr to -15min prior to irradiation and +6hr to +30hr post irradiation. Significant survival efficacy of radioprotectant dmPGE2 was also demonstrated in pediatric and geriatric mice. Using specific PGE2 receptor (EP) agonists, the EP4 receptor was defined as the PGE2 receptor potentially responsible for dmPGE2 radioprotection. Radioprotectant dmPGE2 was also found to prevent radiation-induced thymic involution and to ameliorate the long-term immune suppression in radiation survivors in the DEARE phase via promoting hematopoietic stem cell differentiation towards to the lymphoid lineage. This is the first report of an effective MCM for H-ARS which also targets long-term thymic involution and lymphoid lineage reconstitution.
G-CSF in stem cell mobilization: new insights, new questions
(AME Publishing Company, 2017-07) Patterson, Andrea M.; Pelus, Louis M.; Microbiology and Immunology, School of Medicine

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