Gregory D Sempowski

Duke University Medical Center, Durham, North Carolina, United States

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Publications (99)580.82 Total impact

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    ABSTRACT: Haemophilus ducreyi is the causative agent of the sexually transmitted genital ulcer disease chancroid. Strains of H. ducreyi are grouped in two classes (I and II) based on genotypic and phenotypic differences, including those found in DsrA, an outer membrane protein belonging to the family of multifunctional trimeric autotransporter adhesins. DsrA is a key serum resistance factor of H. ducreyi that prevents binding of natural IgM at the bacterial surface and functions as an adhesin to fibronectin, fibrinogen, vitronectin, and human keratinocytes. Monoclonal antibodies (MAbs) were developed to recombinant DsrA (DsrAI) from prototypical class I strain 35000HP to define targets for vaccine and/or therapeutics. Two anti-DsrAI MAbs bound monomers and multimers of DsrA from genital and non-genital/cutaneous H. ducreyi strains in a Western blot and reacted to the surface of the genital strains; however, these MAbs did not recognize denatured or native DsrA from class II strains. In a modified extracellular matrix protein binding assay using viable H. ducreyi, one of the MAbs partially inhibited binding of fibronectin, fibrinogen, and vitronectin to class I H. ducreyi strain 35000HP, suggesting a role for anti-DsrA antibodies in preventing binding of H. ducreyi to extracellular matrix proteins. Standard ELISA and surface plasmon resonance using a peptide library representing full-length, mature DsrAI revealed the smallest nominal epitope bound by one of the MAbs to be MEQNTHNINKLS. Taken together, our findings suggest that this epitope is a potential target for an H. ducreyi vaccine.
    Monoclonal Antibodies in Immunodiagnosis and Immunotherapy 04/2015; 34(2):73-82. DOI:10.1089/mab.2014.0054
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    ABSTRACT: The threat of radiation exposure requires a mechanistic understanding of radiation-induced immune injury and recovery. The study objective was to explore responses to ionizing radiation in ovariectomized (surgically post-menopausal) female cynomolgus macaques. Animals received a single total-body irradiation (TBI) exposure at doses of 0, 2, or 5 Gy with scheduled necropsies at 5 days, 8 weeks, and 24 weeks post-exposure. Blood and lymphoid tissues were evaluated for tissue, cellular, and molecular responses. Irradiated animals developed symptoms of acute hematopoietic syndrome, and reductions in thymus weight, thymopoiesis, and bone marrow cellularity. Acute, transient increases in plasma monocyte chemoattractant protein 1 (MCP-1) were observed in 5 Gy animals along with dose dependent altered messenger ribonucleic acid (mRNA) signatures in thymus, spleen, and lymph node. Expression of T cell markers was lower in thymus and spleen, while expression of macrophage marker CD68 (cluster of differentiation 68) was relatively elevated in lymphoid tissues from irradiated animals. Ovariectomized female macaques exposed to moderate doses of radiation experienced increased morbidity, including acute, dose-dependent alterations in systemic and tissue-specific biomarkers, and increased macrophage/T cell ratios. The effects on mortality exceeded expectations based on previous studies in males, warranting further investigation.
    International Journal of Radiation Biology 03/2015; 91(6):1-33. DOI:10.3109/09553002.2015.1028597 · 1.84 Impact Factor
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    ABSTRACT: Alveolar macrophages play a critical role in initiating the immune response to inhaled pathogens and have been shown to be the first cell type infected following intranasal inoculation with several pathogens, including Francisella tularensis. In an attempt to further dissect the role of alveolar macrophages in the immune response to Francisella, we selectively depleted alveolar macrophages using CD11c.DOG mice. CD11c.DOG mice express the diphtheria toxin receptor (DTR) under control of the full CD11c promoter. Because mice do not express DTR, tissue restricted expression of the primate DTR followed by treatment with diphtheria toxin (DT) has been widely used as a tool in immunology to examine the effect of acute depletion of a specific immune subset following normal development. We successfully depleted alveolar macrophages via intranasal administration of DT. However, alveolar macrophage depletion was accompanied by many other changes to the cellular composition and cytokine/chemokine milieu in the lung that potentially impact innate and adaptive immune responses. Importantly, we observed a transient influx of neutrophils in the lung and spleen. Our experience serves as a cautionary note to other researchers using DTR mice given the complex changes that occur following DT treatment that must be taken into account when analyzing data.
    03/2015; 3(2). DOI:10.1002/iid3.51
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    ABSTRACT: Ideal nanoparticle (NP)-based drug and vaccine delivery vectors should be free of inherent cytotoxic or immunostimulatory properties. Therefore, determining baseline immune responses to nanomaterials is of utmost importance when designing human therapeutics. We characterized the response of human immune cells to hydrogel NPs fabricated using Particle Replication in Non-wetting Templates (PRINT) technology. We found preferential NP uptake by primary CD14(+) monocytes, which was significantly reduced upon PEGylation of the NP surface. Multiplex cytokine analysis of NP treated primary human peripheral blood mononuclear cells (hu-PBMC) suggests that PRINT based hydrogel NPs do not evoke significant inflammatory responses nor do they induce cytotoxicity or complement activation. We furthered these studies using an in vivo humanized mouse model and similarly found preferential NP uptake by human CD14(+) monocytes without systemic inflammatory cytokine responses. These studies suggest that PRINT hydrogel particles form a desirable platform for vaccine and drug delivery as they neither induce inflammation nor toxicity. Copyright © 2015. Published by Elsevier Inc.
    Nanomedicine Nanotechnology Biology and Medicine 01/2015; 11(3). DOI:10.1016/j.nano.2014.11.010 · 5.98 Impact Factor
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    ABSTRACT: Aging of the world population and a concomitant increase in age-related diseases and disabilities mandates the search for strategies to increase healthspan, the length of time an individual lives healthy and productively. Due to the age-related decline of the immune system, infectious diseases remain among the top 5–10 causes of mortality and morbidity in the elderly, and improving immune function during aging remains an important aspect of healthspan extension. Calorie restriction (CR) and more recently rapamycin (rapa) feeding have both been used to extend lifespan in mice. Preciously few studies have actually investigated the impact of each of these interventions upon in vivo immune defense against relevant microbial challenge in old organisms. We tested how rapa and CR each impacted the immune system in adult and old mice. We report that each intervention differentially altered T-cell development in the thymus, peripheral T-cell maintenance, T-cell function and host survival after West Nile virus infection, inducing distinct but deleterious consequences to the aging immune system. We conclude that neither rapa feeding nor CR, in the current form/administration regimen, may be optimal strategies for extending healthy immune function and, with it, lifespan.
    Aging cell 11/2014; 14(1). DOI:10.1111/acel.12280 · 5.94 Impact Factor
  • Journal of Allergy and Clinical Immunology 09/2014; 135(2). DOI:10.1016/j.jaci.2014.07.058 · 11.25 Impact Factor
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    ABSTRACT: Toll-like receptor 2 (TLR2) is the best-characterized pattern-recognition receptor for the highly pathogenic intracellular bacterium, Francisella tularensis. We previously identified a mutant in the live vaccine strain (LVS) of Francisella, LVS clpB, which is attenuated, but induces a protective immune response. We sought to determine whether TLR2 signaling was required during the immune response to LVS clpB. TLR2 knock-out (TLR2 KO) mice previously infected with LVS clpB are completely protected during a lethal challenge with LVS. Furthermore, the kinetics and magnitude of the primary T-cell response in B6 and TLR2 KO mice are similar indicating that TLR2 signaling is dispensable for the adaptive immune response to LVS clpB. TLR2 signaling was important, however, for the innate immune response to LVS clpB. We identified three classes of cytokines/chemokines that differ in their dependence on TLR2 signaling for production on day 3 post-inoculation in the bronchoalveolar lavage fluid. IL-1α, IL-1β, IL-2, IL-17, MIP-1α, and TNF-α production depended on TLR2 signaling, while GM-CSF, IFN-γ, and VEGF production were completely independent of TLR2 signaling. IL-6, IL-12, IP-10, KC, and MIG production were partially dependent on TLR2 signaling. Together our data indicate that the innate immune response to LVS clpB requires TLR2 signaling for the maximal innate response, whereas TLR2 is not required for the adaptive immune response.
    Frontiers in Immunology 09/2014; 5:426. DOI:10.3389/fimmu.2014.00426
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    ABSTRACT: Lymphocytes are sensitive to ionizing radiation and naive lymphocytes are more radiosensitive than their memory counterparts. Less is known about radiosensitivity of memory cell subsets. We examined the radiosensitivity of naive (TN), effector memory (TEM), and central memory (TCM) T cell subsets in C57BL/6 mice and found TEM to be more resistant to radiation-induced apoptosis than either TN or TCM. Surprisingly, we found no correlation between the extent of radiation-induced apoptosis in T cell subsets and 1) levels of pro- and antiapoptotic Bcl-2 family members or 2) the H2AX content and maximal γH2AX fold change. Rather, TEM cell survival correlated with higher levels of immediate γH2AX marking, immediate break binding and genome-wide open chromatin structure. T cells were able to mark DNA damage seemingly instantly (30 s), even if kept on ice. Relaxing chromatin with the histone deacetylase inhibitor valproic acid following radiation or etoposide treatment improved the survival of TCM and TN cells up to levels seen in the resistant TEM cells but did not improve survival from caspase-mediated apoptosis. We conclude that an open genome-wide chromatin state is the key determinant of efficient immediate repair of DNA damage in T cells, explaining the observed T cell subset radiosensitivity differences.
    The Journal of Immunology 07/2014; 193(4). DOI:10.4049/jimmunol.1400434 · 5.36 Impact Factor
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    ABSTRACT: Using A/J mice, which are susceptible to Staphylococcus aureus, we sought to identify genetic determinants of susceptibility to S. aureus, and evaluate their function with regard to S. aureus infection. One QTL region on chromosome 11 containing 422 genes was found to be significantly associated with susceptibility to S. aureus infection. Of these 422 genes, whole genome transcription profiling identified five genes (Dcaf7, Dusp3, Fam134c, Psme3, and Slc4a1) that were significantly differentially expressed in a) S. aureus -infected susceptible (A/J) vs. resistant (C57BL/6J) mice and b) humans with S. aureus blood stream infection vs. healthy subjects. Three of these genes (Dcaf7, Dusp3, and Psme3) were down-regulated in susceptible vs. resistant mice at both pre- and post-infection time points by qPCR. siRNA-mediated knockdown of Dusp3 and Psme3 induced significant increases of cytokine production in S. aureus-challenged RAW264.7 macrophages and bone marrow derived macrophages (BMDMs) through enhancing NF-κB signaling activity. Similar increases in cytokine production and NF-κB activity were also seen in BMDMs from CSS11 (C57BL/6J background with chromosome 11 from A/J), but not C57BL/6J. These findings suggest that Dusp3 and Psme3 contribute to S. aureus infection susceptibility in A/J mice and play a role in human S. aureus infection.
    PLoS Pathogens 06/2014; 10(6):e1004149. DOI:10.1371/journal.ppat.1004149 · 8.14 Impact Factor
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    ABSTRACT: Adherence of pathogens to cellular targets is required to initiate most infections. Defining strategies that interfere with adhesion is important for the development of preventative measures against infectious diseases. As an adhesin to host extracellular matrix proteins and human keratinocytes, the trimeric autotransporter adhesin DsrA, a proven virulence factor of the Gram-negative bacterium Haemophilus ducreyi, is a potential target for vaccine development. A recombinant form of the N-terminal passenger domain of DsrA from H. ducreyi class I strain 35000HP, termed rNT-DsrAI, was tested as a vaccine immunogen in the experimental swine model of H. ducreyi infection. Viable homologous H. ducreyi was not recovered from any animal receiving four doses of rNT-DsrAI administered with Freund's adjuvant at two-week intervals. Control pigs receiving adjuvant only were all infected. All animals receiving the rNT-DsrAI vaccine developed antibody endpoint titers between 3.5 and 5 logs. All rNT-DsrAI antisera bound the surface of the two H. ducreyi strains used to challenge immunized pigs. Purified anti-rNT-DsrAI IgG partially blocked binding of fibrinogen at the surface of intact H. ducreyi. Overall, immunization with the passenger domain of the trimeric autotransporter adhesin DsrA therefore accelerated clearance of H. ducreyi in experimental lesions, possibly by interfering with fibrinogen binding.
    Vaccine 05/2014; 32(30). DOI:10.1016/j.vaccine.2014.05.031 · 3.49 Impact Factor
  • Lydia M Roberts · John S Davies · Gregory D Sempowski · Jeffrey A Frelinger
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    ABSTRACT: IL-17 and IFN-γ production by Th17 and Th1 cells, respectively, is critical for survival during primary respiratory infection with the pathogenic bacterium, Francisella tularensis Live Vaccine Strain (LVS). The importance, however, of these T cell subsets and their soluble mediators is not well understood during a secondary or memory response. We measured the number of CD4(+) T cells producing IFN-γ or IL-17 in the spleen and lungs of vaccinated mice on day four of the secondary response using intracellular cytokine staining in order to identify protective T cell subsets participating in the memory response. Few bacteria were present in spleens of vaccinated mice on day four and a T cell response was not observed. In the lung, where more bacteria were present, there was a robust Th1 response in vaccinated mice but Th17 cells were not present at higher numbers in vaccinated mice compared to unvaccinated mice. These data show that the lung is the dominant site of the secondary immune response and suggest that Th17 cells are not required for survival during secondary challenge. To further investigate the importance of IFN-γ and IL-17 during the secondary response to F. tularensis, we neutralized either IFN-γ or IL-17 in vivo using monoclonal antibody treatment. Vaccinated mice treated with anti-IFN-γ lost more weight and had higher bacterial burdens compared to vaccinated mice treated with isotype control antibody. In contrast, treatment with anti-IL-17A antibody did not alter weight loss profiles or bacterial burdens compared to mice treated with isotype control antibody. Together, these results suggested that IFN-γ is required during both primary and secondary respiratory F. tularensis infection. IL-17, on the other hand, is only critical during the primary response to respiratory F. tularensis but dispensable during the secondary response.
    Vaccine 05/2014; 32(29). DOI:10.1016/j.vaccine.2014.05.013 · 3.49 Impact Factor
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    ABSTRACT: Luminex bead array assays are widely used for rapid biomarker quantification due to the ability to measure up to 100 unique analytes in a single well of a 96-well plate. There has been, however, no comprehensive analysis of variables impacting assay performance, nor development of a standardized proficiency testing program for laboratories performing these assays. To meet this need, the NIH/NIAID and the Cancer Immunotherapy Consortium of the Cancer Research Institute collaborated to develop and implement a Luminex assay proficiency testing program as part of the NIH/NIAID-sponsored External Quality Assurance Program Oversight Laboratory (EQAPOL) at Duke University. The program currently monitors 25 domestic and international sites with two external proficiency panels per year. Each panel includes a de-identified commercial Luminex assay kit with standards to quantify human IFNγ, TNFα, IL-6, IL-10 and IL-2, and a series of recombinant cytokine-spiked human serum samples. All aspects of panel development, testing and shipping are performed under GCLP by EQAPOL support teams. Following development testing, a comprehensive site proficiency scoring system comprised of timeliness, protocol adherence, accuracy and precision was implemented. The overall mean proficiency score across three rounds of testing has remained stable (EP3:76%, EP4:75%, EP5:77%); however, a more detailed analysis of site reported results indicates a significant improvement of intra- (within) and inter- (between) site variation, suggesting that training and remediation for poor performing sites may be having a positive impact on proficiency. Through continued proficiency testing, identification of variables affecting Luminex assay outcomes will strengthen efforts to bring standardization to the field.
    Journal of immunological methods 05/2014; 409. DOI:10.1016/j.jim.2014.04.011 · 2.01 Impact Factor
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    ABSTRACT: The induction of an intense inflammatory response by Neisseria gonorrhoeae and the persistence of this pathogen in the presence of innate effectors is a fascinating aspect of gonorrhea. Phosphoethanolamine (PEA) decoration of lipid A increases gonococcal resistance to complement-mediated bacteriolysis and cationic antimicrobial peptides (CAMPs), and recently we reported that wild-type N. gonorrhoeae strain FA1090 has a survival advantage relative to a PEA transferase A (lptA) mutant in the human urethral challenge and murine lower genital tract infection models. Here we tested the immunostimulatory role of this lipid A modification. Purified lipooligosaccharide (LOS) containing lipid A devoid of the PEA modification and an lptA mutant of strain FA19 induced significantly lower levels of NFκB in human embryonic kidney Toll-like receptor 4 (TLR4) cells and murine embryonic fibroblasts compared to the wild-type LOS or the parent strain. Moreover, in contrast to mice infected with the wild-type and complemented lptA mutant bacteria, vaginal proinflammatory cytokines and chemokines were not elevated in female mice infected with the isogenic lptA mutant compared to uninfected mice. We also demonstrated that lptA mutant bacteria were more susceptible to the human and murine cathelicidins due to increased binding by these peptides, and that the differential induction of NFκB by wild-type and unmodified lipid A was more pronounced in the presence of CAMPs. This work demonstrates that PEA-decoration of lipid A plays both protective and immunostimulatory roles and that host-derived CAMPs may further reduce the capacity of PEA-deficient lipid A to interact with TLR4 during infection.
    Infection and immunity 03/2014; 82(6). DOI:10.1128/IAI.01504-14 · 4.16 Impact Factor
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    ABSTRACT: The adaptive immune response to Francisella tularensis is dependent on the route of inoculation. Intradermal inoculation with F. tularensis live vaccine strain (LVS) results in a robust Th1 response in the lung whereas intranasal inoculation produces fewer Th1 cells and instead many Th17 cells. Interestingly, bacterial loads in the lung are similar early after inoculation regardless of the inoculation route. We hypothesize that the adaptive immune response is influenced by local events in the lung, such as the type of cells that are first infected with Francisella. Using fluorescent activated cell sorting, we identified alveolar macrophages as the first cell type infected in the lungs of mice intranasally inoculated with F. novicida U112, LVS, or F. tularensis Schu S4. Following bacterial dissemination from the skin to the lung, interstitial macrophages or neutrophils are infected. Overall, we identified the early interactions between Francisella and the host following two different routes of inoculation.
    Infection and immunity 03/2014; 82(6). DOI:10.1128/IAI.01654-13 · 4.16 Impact Factor
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    ABSTRACT: Establishment of humoral immunity against pathogens is dependent on events that occur in the germinal center and the subsequent induction of high-affinity neutralizing antibodies. Quantitative assays that allow monitoring of affinity maturation and duration of antibody responses can provide useful information regarding the efficacy of vaccines and adjuvants. Using an anthrax protective antigen (rPA) and alum model antigen/adjuvant system, we describe a methodology for monitoring antigen-specific serum antibody concentration and avidity by surface plasmon resonance during primary and secondary immune responses. Our analyses showed that following a priming dose in mice, rPA-specific antibody concentration and avidity increases over time and reaches a maximal response in about six weeks, but gradually declines in the absence of antigenic boost. Germinal center reactions were observed early with maximal development achieved during the primary response, which coincided with peak antibody avidity responses to primary immunization. Boosting with antigen resulted in a rapid increase in rPA-specific antibody concentration and five-fold increase in avidity, which was not dependent on sustained GC development. The described methodology couples surface plasmon resonance-based plasma avidity measurements with germinal center analysis and provides a novel way to monitor humoral responses that can play a role in facilitating vaccine and adjuvant development.
    Journal of immunological methods 12/2013; 404. DOI:10.1016/j.jim.2013.11.026 · 2.01 Impact Factor
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    ABSTRACT: Cryptococcus neoformans is an opportunistic fungal pathogen that initiates infection following inhalation. As a result, the pulmonary immune response provides a first line of defense against C. neoformans. Surfactant protein D (SP-D) is an important regulator of pulmonary immune responses and is typically host-protective against bacterial and viral respiratory infections. However, SP-D is not protective against C. neoformans. This is evidenced by previous work from our laboratory demonstrating that SP-D deficient mice infected with C. neoformans have a lower fungal burden and live longer, compared to wild-type (WT) control animals. We hypothesized that SP-D alters susceptibility to C. neoformans by dysregulating the innate pulmonary immune response following infection. Thus inflammatory cells and cytokines were compared in the bronchoalveolar lavage fluid from WT and SP-D(-/-) mice after C. neoformans infection. Post-infection, mice lacking SP-D have reduced eosinophil infiltration and IL-5 in lung lavage fluid. To further explore the interplay of SP-D, eosinophils, and IL-5, mice expressing altered levels of eosinophils and/or IL-5 were infected with C. neoformans to assess the role of these innate immune mediators. IL-5 overexpressing mice have increased pulmonary eosinophilia and are more susceptible to C. neoformans infection as compared to WT mice. Furthermore, susceptibility of SP-D(-/-) mice to C. neoformans infection could be restored to that of WT mice by increasing IL-5 and eosinophils, via crossing the IL-5 overexpressing mice with SP-D(-/-) mice. Together, these studies support the conclusion that SP-D increases susceptibility to C. neoformans infection by promoting C. neoformans-driven pulmonary IL-5 and eosinophil infiltration.
    Infection and immunity 11/2013; 82(2). DOI:10.1128/IAI.00855-13 · 4.16 Impact Factor
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    ABSTRACT: Neisseria gonorrhoeae causes gonorrhea, a sexually transmitted infection characterized by inflammation of the cervix or urethra. However, a significant subset of patients with N. gonorrhoeae remains asymptomatic without evidence of localized inflammation. Inflammatory responses to N. gonorrhoeae are generated by host innate immune recognition of N. gonorrhoeae by several innate immune signaling pathways including lipooligosaccharide and other pathogen-derived molecules through activation of innate immune signaling systems including toll-like receptor 4 (TLR4) and the IL-1β processing complex known as the inflammasome. The lipooligosaccharide of N. gonorrhoeae has a hexa-acylated lipid A. N. gonorrhoeae that carry an inactivated msbB (also known as lpxL1) gene produce a penta-acylated lipid A and exhibit reduced biofilm formation, survival in epithelial cells, and induction of epithelial cell inflammatory signaling. We now show that msbB-deficient N. gonorrhoeae induces less inflammatory signaling in human monocytic cell lines and murine macrophages than the parent organism. The penta-acylated LOS exhibits reduced toll-like receptor 4 signaling but does not effect N. gonorrhoeae-mediated activation of the inflammasome. We demonstrate that N. gonorrhoeae msbB is dispensible for initiating and maintaining infection in a murine model of gonorrhea. Interestingly, infection with msbB-deficient N. gonorrhoeae is associated with less localized inflammation. Combined, these data suggest that TLR4-mediated recognition of N. gonorrhoeae LOS plays an important role the pathogenesis of symptomatic gonorrhea infection and that alterations in lipid A biosynthesis may play a role in determining symptomatic and asymptomatic infections.
    Infection and immunity 10/2013; DOI:10.1128/IAI.00890-13 · 4.16 Impact Factor
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    ABSTRACT: Macrophages and dendritic cells (DC) are distributed throughout the body and play important roles in pathogen detection and tissue homeostasis. In tissues, resident macrophages exhibit distinct phenotypes and activities, yet the transcriptional pathways that specify tissue-specific macrophages are largely unknown. We investigated the functions and origins of two peritoneal macrophage populations in mice: small and large peritoneal macrophages (SPM and LPM, respectively). SPM and LPM differ in their ability to phagocytose apoptotic cells, as well as in the production of cytokines in response to LPS. In steady-state conditions, SPM are sustained by circulating precursors, whereas LPM are maintained independently of hematopoiesis; however, both populations are replenished by bone marrow precursors following radiation injury. Transcription factor analysis revealed that SPM and LPM express abundant CCAAT/enhancer binding protein (C/EBP)-β. Cebpb(-/-) mice exhibit elevated numbers of SPM-like cells but lack functional LPM. Alveolar macrophages are also missing in Cebpb(-/-) mice, although macrophage populations in the spleen, kidney, skin, mesenteric lymph nodes, and liver are normal. Adoptive transfer of SPM into Cebpb(-/-) mice results in SPM differentiation into LPM, yet donor SPM do not generate LPM after transfer into C/EBPβ-sufficient mice, suggesting that endogenous LPM inhibit differentiation by SPM. We conclude that C/EBPβ plays an intrinsic, tissue-restricted role in the generation of resident macrophages.
    The Journal of Immunology 09/2013; 191(9). DOI:10.4049/jimmunol.1300581 · 5.36 Impact Factor
  • Melissa S Ventevogel · Gregory D Sempowski
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    ABSTRACT: The thymus is a vital organ for homeostatic maintenance of the peripheral immune system. It is within this mediastinal tissue that T cells develop and are extensively educated and exported to the periphery for establishment of a functional and effective immune system. A striking paradoxical feature of this critical lymphoid tissue is that it undergoes profound age-associated involution. Thymic decline is of minimal consequence to healthy individuals, but the reduced efficacy of the immune system with age has direct etiological linkages with an increase in diseases including opportunistic infections, autoimmunity, and incidence/burden of cancer. Furthermore the inability of adults to restore immune function following insult induced by chemotherapy, ionizing radiation exposure or therapy, and infections (e.g. HIV-1) leads to increased morbidity and often mortality in the elderly. For these reasons, it is important that investigators strive to translate their understanding of mechanisms that drive thymic involution, and develop safe and effective strategies to rejuvenate the thymus in settings of clinical need. In this review, we present a discussion of the current status of thymic rejuvenation efforts associated with: sex steroid ablation, cytokines, growth factors, and hormones.
    Current opinion in immunology 07/2013; 25(4). DOI:10.1016/j.coi.2013.06.002 · 7.87 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: The liver's response to injury is fibrosis, and when chronic, cirrhosis. Age is a critical factor impacting many immune-mediated processes, potentially including the liver's wounding response to injury. METHODS: The effects of age on acute and chronic liver injury were evaluated using a carbon tetrachloride model in mice. Lymphocyte and macrophage populations were assessed by flow cytometry and immunohistochemical analysis. RESULTS: Acute liver injury was greater in 18-month-old (old) mice than in 9-month-old (middle-aged) mice as judged by changes in aminotransferases. Similarly, livers of 18-month-old mice had a significantly greater fibrogenic response to injury than did livers of 9-month-old mice after chronic injury (assessed by col1α1 mRNA expression, morphometric analysis and hydroxyproline measurement). Interestingly, livers from young mice (6 weeks old) also exhibited an increase in fibrogenesis compared to 9-month-old mice, albeit not to the same degree as in old mice. Consistent with a role for macrophages in fibrogenesis, the number of liver macrophages in young and 9-month-old mice increased, while in chronically injured livers of 18-month-old mice, the number of macrophages was reduced, and was less than in the livers of young and 9-month-old injured livers. CONCLUSIONS: Our data indicate that the fibrogenic response to injury varies substantially with age, and moreover that macrophage recruitment and dynamics may be an important component in differential age-associated fibrotic disease.
    Liver international: official journal of the International Association for the Study of the Liver 04/2013; DOI:10.1111/liv.12202 · 4.41 Impact Factor

Publication Stats

4k Citations
580.82 Total Impact Points

Institutions

  • 1999–2015
    • Duke University Medical Center
      • • Duke Human Vaccine Institute
      • • Department of Pathology
      • • Department of Cell Biology
      • • Department of Medicine
      • • Department of Pediatrics
      Durham, North Carolina, United States
  • 2001–2014
    • Duke University
      • Department of Medicine
      Durham, North Carolina, United States
  • 2002
    • Max Planck Institute of Molecular Cell Biology and Genetics
      Dresden, Saxony, Germany