Bone Marrow-derived Immune Cells Research Articles

The importance of bone marrow and the immune system in driving increases in blood pressure and sympathetic nerve activity in hypertension.

What is the topic of this review? This manuscript provides a review of the current understanding of the role of the sympathetic nervous system in regulation of bone marrow-derived immune cells and the effect that the infiltrating bone marrow cells may have on perpetuation of the sympathetic over-activation in hypertension. What advances does it highlight? We highlight the recent advances in understanding of the neuroimmune interactions both peripherally and centrally as they relate to blood pressure control. The sympathetic nervous system (SNS) plays a crucial role in maintaining physiological homeostasis, in part by regulating, integrating and orchestrating processes between many physiological systems, including the immune system. Sympathetic nerves innervate all primary and secondary immune organs, and all cells of the immune system express β-adrenoreceptors. In turn, immune cells can produce cytokines, chemokines and neurotransmitters capable of modulating neuronal activity and, ultimately, SNS activity. Thus, the essential role of the SNS in the regulation of innate and adaptive immune functions is mediated, in part, via β-adrenoreceptor-induced activation of bone marrow cells by noradrenaline. Interestingly, both central and systemic inflammation are well-established hallmarks of hypertension and its co-morbidities, including an inflammatory process involving the transmigration and infiltration of immune cells into tissues. We propose that physiological states that prolong β-adrenoreceptor activation in bone marrow can disrupt neuroimmune homeostasis and impair communication between the immune system and SNS, leading to immune dysregulation, which, in turn, is sustained via a central mechanism involving neuroinflammation.

Lactate Exposure Promotes Immunosuppressive Phenotypes in Innate Immune Cells.

Lactate secreted by tumors is not just a byproduct, but rather an active modulator of immune cells. There are few studies aimed at investigating the true effect of lactate, which is normally confounded by pH. Such a knowledge gap needs to be addressed. Herein, we studied the immunomodulatory effects of lactate on dendritic cells (DCs) and macrophages (MΦs). Bone marrow-derived innate immune cells were treated with 50mM sodium lactate (sLA) and incubated for 2days or 5days at 37°C. Controls included media, lipopolysaccharide (LPS), MCT inhibitors (α-cyano-4-hydroxycinnamic acid and AR-C15585). Flow cytometric analysis of immune phenotypes were performed by incubating cells with specific marker antibodies and viability dye. Differential expression analyses were conducted on R using limma-voom and adjusted p-values were generated using the Bejamini-Hochberg Procedure. Lactate exposure attenuated DC maturation through the downregulation of CD80 and MHCII expression under LPS stimulation. For MΦs, lactate exposure resulted in M2 polarization as evidenced by the reduction of M1 markers (CD38 and iNOS), and the increase in expression of CD163 and Arg1. We also revealed the role of monocarboxylate transporters (MCTs) in mediating lactate effect in MΦs. MCT4 inhibition significantly boosted lactate M2 polarization, while blocking of MCT1/2 failed to reverse the immunosuppressive effect of lactate, correlating with the result of gene expression that lactate increased MCT4 expression, but downregulated the expression of MCT1/2. This research provides valuable insight on the influence of metabolic products on tumor immunity and will help to identify novel metabolic targets for augmenting cancer immunotherapies.

Esophageal Microenvironment: From Precursor Microenvironment to Premetastatic Niche.

Esophageal cancer (EC) is the sixth most deadly cancer, and its incidence is still increasing year by year. Although the researches on the molecular mechanisms of EC have been widely carried out and incremental progress has been made, its overall survival rate is still low. There is cumulative evidence showing that the esophageal microenvironment plays a vital role in the development of EC. In precancerous lesions of the esophagus, high-risk environmental factors can promote the development of precancerous lesions by inducing the production of inflammatory factors and the recruitment of immune cells. In the tumor microenvironment, tumor-promoting cells can inhibit anti-tumor immunity and promote tumor progression through a variety of pathways, such as bone marrow-derived suppressor cells (MDSCs), tumor-associated fibroblasts (CAFs), and regulatory T cells (Tregs). The formation of extracellular hypoxia and acidic microenvironment and the change of extracellular matrix stiffness are also important factors affecting tumor progression and metastasis. Simultaneously, primary tumor-derived cytokines and bone marrow-derived immune cells can also promote the formation of pre-metastasis niche of EC lymph nodes, which are beneficial to EC lymph node metastasis. Further research on the specific mechanism of these processes in the occurrence, development, and metastasis of each EC subtype will support us to grasp the overall pre-cancerous prevention, targeted treatment, and metastatic assessment of EC.

O11.2. ELEVATION OF MACROPHAGE-RELATED TRANSCRIPTS IN THE MIDBRAIN IN SCHIZOPHRENIA

BackgroundNeuroinflammation and dopamine dysregulation contribute to psychosis and cognitive deficits in schizophrenia. Approximately 50% of people with schizophrenia have elevated gene expression of proinflammatory cytokines in the postmortem midbrain, the location of the dopamine neurons. Infiltration of macrophages into the cortex was identified in a subset of high inflammatory schizophrenia cases. It is not known whether molecular measures of macrophages and cell adhesion molecules are increased in the midbrain in schizophrenia. We hypothesised that gene expression of macrophage markers CD163 (cluster of differentiation 163; perivascular macrophages), Fn1 (fibronectin 1; expressed by peripheral macrophages, not brain microglia), CD64 (pro-inflammatory macrophage), MRC1 (anti-inflammatory macrophage) and intracellular cell adhesion molecule 1 (ICAM1; enabling recruitment of peripheral macrophages into the brain), will be elevated in the midbrain of schizophrenia cases compared to controls.MethodsGene expression was examined by qRT-PCR in the midbrain from 28 schizophrenia cases (13 high inflammation, 15 low inflammation) and 29 healthy controls (low inflammation). ANCOVA, with age, PMI and RIN as covariates when correlations detected, were used to detect differences between diagnostic or diagnostic/inflammatory groups. For schizophrenia cases, antipsychotic doses were converted to chlorpromazine (CPZ) equivalents. Correlations were used to determine relationships between illness duration, antipsychotics and gene expression. CD163+ cells were identified in fresh frozen midbrain (14µm) from schizophrenia and control cases by immunohistochemistry to qualitatively assess their location relative to dopamine neurons.ResultsWe found abundant macrophages (CD163+ cells) in and around blood vessels and in the schizophrenia midbrain parenchyma in close proximity to dopamine neurons. CD163, Fn1 and ICAM mRNAs were increased 237.6%, 39.67% and 137.7% respectively, in schizophrenia cases compared to control cases [all F(1,50 >5.045, p<0.05]. The pro-inflammatory macrophage marker (CD64 mRNA) was increased by 39% (F1,51=11.10, p=0.002), while the anti-inflammatory macrophage marker (MRC1 mRNA) was unchanged (F(1,52=2.97. p=0.09) in schizophrenia midbrain compared to control. CD163 and Fn1 mRNAs were not correlated in controls (R=0.319, p=0.112, n=24) but were correlated in schizophrenia cases (R=0.455, p=0.019, n=24). CD163 and ICAM mRNAs were positively correlated in controls (R=0.42, p=0.031, n=24) and schizophrenia cases (R=0.84, p<0.0001, n=24), and the correlation was stronger in schizophrenia cases (p=0.014). CD163 and ICAM mRNAs were positively correlated with CPZ (Rho>0.5, p<0.02, n=21) but not illness duration (Rho=0.024, p>0.05, n=28). Fn1 mRNA did not correlate with illness duration or antipsychotics.DiscussionIncreased ICAM1 may lead to increased transmigration of monocytes into the midbrain parenchyma. The increase in CD64 and the positive relationship between Fn1, expressed by peripheral monocytes/macrophages but not brain microglia, and CD163 expression in schizophrenia cases provides support that there is an increase in pro-inflammatory bone marrow-derived immune cells in the psychotic midbrain. These peripheral immune cells may be a source of increased cytokines identified in the midbrain schizophrenia cases and thus may contribute to dopamine neuron pathophysiology. Although the role of antipsychotics in increased macrophage marker expression in the midbrain is suggested, increased antipsychotics in patients displaying higher expression of inflammatory transcripts may indicate a more symptomatic patient requiring higher treatment doses.

The 2019 FASEB Science Research Conference on Matricellular Proteins in Inflammation and Tissue Remodeling, July 14-19, 2019, Lisbon, Portugal.

The 2019 FASEB Science Research Conference on Matricellular Proteins in Inflammation and Tissue Remodeling, July 14-19, 2019, Lisbon, Portugal.

Isolation and Preparation of Bone Marrow-Derived Immune Cells for Metabolic Analysis.

The isolation of immune cells from the bone marrow is important for obtaining sufficient numbers for downstream analysis. Immune cells derived from the bone marrow may be subjected to metabolic assays for analysis or used to test the effect of infectious agents on immune cells. Here, we describe a process for the isolation of macrophages, dendritic cells, and neutrophils from mice. Using the methods described herein, specific immune cells with purity above 85-90% can be obtained from the bone marrow of mice.

Analysis of Secreted MIF from Cultured Murine Bone Marrow-Derived Immune Cells.

Macrophage migration inhibitory factor (MIF) is expressed and released ubiquitously by numerous cell types and tissues. MIF is detected and constitutively expressed at the protein level both intra- and extracellularly. This chapter outlines methods for cultivating, purifying, detecting, and quantifying concentrations of MIF from murine primary derived macrophages and dendritic cell culture supernatants.

Acute Kidney Injury Induces Remote Cardiac Damage and Dysfunction Through the Galectin-3 Pathway

Acute kidney injury is associated with increased risk of heart failure and mortality. This study demonstrates that acute kidney injury induces remote cardiac dysfunction, damage, injury, and fibrosis via a galectin-3 (Gal-3) dependent pathway. Gal-3 originates from bone marrow-derived immune cells. Cardiac damage could beprevented by blocking this pathway.

Human cord blood (hCB)-CD34+ humanized mice fail to reject human acute myeloid leukemia cells.

Since their appearance, humanized mice carrying human immune system seemed promising tools to study the crosstalk between cancer and immunity. The NOD-scidIL2Rgammanull (NSG) mice engrafted with human cord blood (hCB)-CD34+ cells have been proposed to be a valuable tool to reproduce human immune system in mouse. However, the lack of solid evidences on the functionality of their human immune components limits their usage in immune-oncology. We report that (hCB)-CD34+ cells lose their ability to propagate and originate bone marrow-derived human immune cells after two serial transplantations in NSG mice. We demonstrate that transplants of bone marrow patient-derived acute myeloid leukemias (hAMLs) grow very similarly in the humanized (hCB)-CD34+ NSG and parental NSG mice. The similar extent of engraftment and development of leukemias in (hCB)-CD34+ NSG and controls suggests a poor human immune response against not compatible hAMLs. Our findings suggest that (hCB)-CD34+ NSG mice are transient and/or incomplete carriers of the human immune system and, therefore, represent a suboptimal tool to study the interaction between tumor and immune cells.

ADAM17 selectively activates the IL-6 trans-signaling/ERK MAPK axis in KRAS-addicted lung cancer.

Oncogenic KRAS mutations are major drivers of lung adenocarcinoma (LAC), yet the direct therapeutic targeting of KRAS has been problematic. Here, we reveal an obligate requirement by oncogenic KRAS for the ADAM17 protease in LAC. In genetically engineered and xenograft (human cell line and patient‐derived) Kras G12D‐driven LAC models, the specific blockade of ADAM17, including with a non‐toxic prodomain inhibitor, suppressed tumor burden by reducing cellular proliferation. The pro‐tumorigenic activity of ADAM17 was dependent upon its threonine phosphorylation by p38 MAPK, along with the preferential shedding of the ADAM17 substrate, IL‐6R, to release soluble IL‐6R that drives IL‐6 trans‐signaling via the ERK1/2 MAPK pathway. The requirement for ADAM17 in Kras G12D‐driven LAC was independent of bone marrow‐derived immune cells. Furthermore, in KRAS mutant human LAC, there was a significant positive correlation between augmented phospho‐ADAM17 levels, observed primarily in epithelial rather than immune cells, and activation of ERK and p38 MAPK pathways. Collectively, these findings identify ADAM17 as a druggable target for oncogenic KRAS‐driven LAC and provide the rationale to employ ADAM17‐based therapeutic strategies for targeting KRAS mutant cancers.

P142 CONSTITUTIVELY ACTIVE MAC-1 (CD11B) AMELIORATES INFLAMMATION IN MOUSE DSS COLITIS MODEL

Mac-1 (CD11b/CD18)-is an integrin expressed on bone marrow-derived immune cells that binds ICAM-1 to regulate leukocyte adhesion and migration across the endothelium or epithelium. The role of CD11b in tumorigenesis and colitis is controversial. It has been reported that deficiency of CD11b exacerbates dextran sodium sulfate (DSS)-induced colitis. The opposite scenario, in which CD11b deficiency suppresses intestinal tumor growth in CD11b -/- APC min/+ animals by reducing myeloid cell recruitment has also been reported. Additional studies have concluded that an active CD11b signal can exert an inhibitory effect on TLR triggered inflammatory response in macrophages and even inhibit full T cells activation by myeloid dendritic cells. Clinical trials using agents designed to inhibit the binding of this integrin to its ligands have had limited success in humans. In this initial exploratory study, we compared the absence and the permanent activation of CD11b to further clarify the role of Mac-1 in the DSS colitis model. CD11bKO, CD11bKI-expressing constitutively active CD11b, and their corresponding littermates were treated with 4% DSS to induce colitis. Disease activity index and percentage weight loss were recorded. Distal colons were collected for the DSS as well as the water treated controls. Pathology scores were assigned following scoring criteria described in Erben et al., 2014 Flow cytometry immunophenotyping of lamina propria leukocytes was used to determine infiltrate composition and quantify myeloid-derived suppressor cells (MDSCs) defined by CD11b+/Gr-1+ expression. CD4 immunofluorescence was used for inter-strain comparison of effector T cell abundance. We also performed experiments to ascertain the effects of a CD11b agonist: Leukadherin-1 (LA1). Animals lacking CD11b expression were the least inflamed, while the constitutive activation of CD11b resulted in a decrease in the level of inflammation in relation to the C57 wild type group as per disease activity index and percentage weight loss. Ratios of neutrophil counts in DSS and untreated animals showed a higher neutrophilic infiltration in C57 animals while the CD11bKO displayed the lowest number.The number of CD4+ T cells and MDSCs present correlated with the levels of inflammation in these three strains. Use of LA1 resulted in intermediate levels of inflammation comparable to that observed in CD11bKI. Although more work needs to be done to elucidate the role of CD11b in colitis, our initial findings suggest that whether by dampening leukocyte migration and/or inhibiting full T cells activation during antigen presentation, constitutive activation of CD11b ameliorates inflammation in DSS treated animals. Therefore making CD11b is a worthy pharmacological target in the treatment of inflammatory diseases.

C-Met Signaling Protects from Nonalcoholic Steatohepatitis- (NASH-) Induced Fibrosis in Different Liver Cell Types.

Nonalcoholic steatohepatitis (NASH) is the most common chronic, progressive liver disease in Western countries. The significance of cellular interactions of the HGF/c-Met axis in different liver cell subtypes and its relation to the oxidative stress response remains unclear so far. Hence, the present study is aimed at investigating the role of c-Met and the interaction with the oxidative stress response during NASH development in mice and humans. Conditional c-Met knockout (KO) lines (LysCre for Kupffer cells/macrophages, GFAPCre for α-SMA+ and CK19+ cells and MxCre for bone marrow-derived immune cells) were fed chow and either methionine-choline-deficient diet (MCD) for 4 weeks or high-fat diet (HFD) for 24 weeks. Mice lacking c-Met either in Kupffer cells, α-SMA+ and CK19+ cells, or bone marrow-derived immune cells displayed earlier and faster progressing steatohepatitis during dietary treatments. Severe fatty liver degeneration and histomorphological changes were accompanied by an increased infiltration of immune cells and a significant upregulation of inflammatory cytokine expression reflecting an earlier initiation of steatohepatitis development. In addition, animals with a cell-type-specific deletion of c-Met exhibited a strong generation of reactive oxygen species (ROS) by dihydroethidium (hydroethidine) (DHE) staining showing a significant increase in the oxidative stress response especially in LysCre/c-Metmut and MxCre/c-Metmut animals. All these changes finally lead to earlier and stronger fibrosis progression with strong accumulation of collagen within liver tissue of mice deficient for c-Met in different liver cell types. The HGF/c-Met signaling pathway prevents from steatosis development and has a protective function in the progression to steatohepatitis and fibrosis. It conveys an antifibrotic role independent on which cell type c-Met is missing (Kupffer cells/macrophages, α-SMA+ and CK19+ cells, or bone marrow-derived immune cells). These results highlight a global protective capacity of c-Met in NASH development and progression.

Metabolic Symbiosis and Immunomodulation: How Tumor Cell-Derived Lactate May Disturb Innate and Adaptive Immune Responses.

The tumor microenvironment (TME) is composed by cellular and non-cellular components. Examples include the following: (i) bone marrow-derived inflammatory cells, (ii) fibroblasts, (iii) blood vessels, (iv) immune cells, and (v) extracellular matrix components. In most cases, this combination of components may result in an inhospitable environment, in which a significant retrenchment in nutrients and oxygen considerably disturbs cell metabolism. Cancer cells are characterized by an enhanced uptake and utilization of glucose, a phenomenon described by Otto Warburg over 90 years ago. One of the main products of this reprogrammed cell metabolism is lactate. “Lactagenic” or lactate-producing cancer cells are characterized by their immunomodulatory properties, since lactate, the end product of the aerobic glycolysis, besides acting as an inducer of cellular signaling phenomena to influence cellular fate, might also play a role as an immunosuppressive metabolite. Over the last 10 years, it has been well accepted that in the TME, the lactate secreted by transformed cells is able to compromise the function and/or assembly of an effective immune response against tumors. Herein, we will discuss recent advances regarding the deleterious effect of high concentrations of lactate on the tumor-infiltrating immune cells, which might characterize an innovative way of understanding the tumor-immune privilege.

Sphingomyelin synthase 2 deficiency inhibits the induction of murine colitis-associated colon cancer.

Sphingomyelin synthase 2 (SMS2) is the synthetic enzyme of sphingomyelin (SM), which regulates membrane fluidity and microdomain structure. SMS2 plays a role in LPS-induced lung injury and inflammation; however, its role in inflammation-mediated tumorigenesis is unclear. We investigated the effect of SMS2 deficiency on dextran sodium sulfate (DSS)-induced murine colitis and found inhibition of DSS-induced inflammation in SMS2-deficient (SMS2-/-) mice. DSS treatment induced a significant increase in ceramide levels, with a decrease of SM levels in SMS2-/- colon tissue, and demonstrated attenuation of the elevation of both inflammation-related gene expression and proinflammatory cytokines and chemokines, leukocyte infiltration, and MAPK and signal transducer and activator of transcription 3 activation. After undergoing transplantation of wild-type bone marrow, SMS2-/- mice also exhibited inhibition of DSS-induced inflammation in the colon, which suggested that SMS2 deficiency in bone marrow-derived immune cells was not involved in the inhibition of colitis. Finally, in an azoxymethane/DSS-induced cancer model, SMS2 deficiency significantly decreased tumor incidence in the colon. Our results demonstrate that SMS2 deficiency inhibits DSS-induced colitis and subsequent colitis-associated colon cancer via inhibition of colon epithelial cell-mediated inflammation; therefore, inhibition of SMS2 may be a potential therapeutic target for human colitis and colorectal cancer.-Ohnishi, T., Hashizume, C., Taniguchi, M., Furumoto, H., Han, J., Gao, R., Kinami, S., Kosaka, T., Okazaki, T. Sphingomyelin synthase 2 deficiency inhibits the induction of murine colitis-associated colon cancer.

Unlocking bat immunology: establishment of Pteropus alecto bone marrow-derived dendritic cells and macrophages.

Bats carry and shed many emerging infectious disease agents including Ebola virus and SARS-like Coronaviruses, yet they rarely display clinical symptoms of infection. Bat epithelial or fibroblast cell lines were previously established to study the bat immune response against viral infection. However, the lack of professional immune cells such as dendritic cells (DC) and macrophages has greatly limited the significance of current investigations. Using Pteropus alecto (P. alecto) GM-CSF plus IL4, FLT3L and CSF-1, we successfully generated bat bone marrow-derived DC and macrophages. Cells with the phenotype, morphology and functional features of monocyte-derived DC, bona fide DC or macrophages were obtained in GM-CSF/IL4, FLT3L or CSF-1 cultures, respectively. The successful generation of the first bat bone marrow-derived immune cells paves the way to unlocking the immune mechanisms that confer host resilience to pathogens in bats.

Exogenous remodeling of lung resident macrophages protects against infectious consequences of bone marrow-suppressive chemotherapy

Infection is the single greatest threat to survival during cancer chemotherapy because of depletion of bone marrow-derived immune cells. Phagocytes, especially neutrophils, are key effectors in immunity to extracellular pathogens, which has limited the development of new approaches to protect patients with cancer and chemotherapy-induced neutropenia. Using a model of vaccine-induced protection against lethal Pseudomonas aeruginosa pneumonia in the setting of chemotherapy-induced neutropenia, we found a population of resident lung macrophages in the immunized lung that mediated protection in the absence of neutrophils, bone marrow-derived monocytes, or antibodies. These vaccine-induced macrophages (ViMs) expanded after immunization, locally proliferated, and were closely related to alveolar macrophages (AMs) by surface phenotype and gene expression profiles. By contrast to AMs, numbers of ViMs were stable through chemotherapy, showed enhanced phagocytic activity, and prolonged survival of neutropenic mice from lethal P. aeruginosa pneumonia upon intratracheal adoptive transfer. Thus, induction of ViMs by tissue macrophage remodeling may become a framework for new strategies to activate immune-mediated reserves against infection in immunocompromised hosts.

Abstract IA14: PDX models in head and neck cancers: Present status and future application for immune-oriented biology and therapy development

Abstract Targeted therapy development in head and neck squamous cell carcinoma (HNSCC) is challenging given the rarity of activating mutations. Additionally, HNSCC incidence is dramatically increasing related to human papillomavirus (HPV). We sought to develop an in vivo model derived from patients reflecting the evolving HNSCC epidemiologic landscape, and use it to identify new therapies. Primary and relapsed tumors from over 100 HNSCC patients, both HPV+ and HPV-, have been implanted on mice, giving rise to over 50 strains. Resulting xenografts were characterized by detecting key mutations, measuring protein expression by IHC and gene expression/pathway analysis by mRNA-sequencing. The genetic makeup of these tumors was consistent with the frequencies of TP53, PI3KCA, NOTCH1, and NOTCH2 mutations found in landmark genomic characterization of large HNSCC patient cohorts. Tumors maintained their original morphology, genetic profiles, and drug susceptibilities through serial passaging. Cancer cells deceive the host to create an advantageous microenvironment and evade immune surveillance. A limitation to studying human cancer is the limited availability of in vivo models with appropriate human stroma and immunity. To address this unmet need, we generated an allogeneic humanized mouse (aHM) model where HNSCC were implanted on NOD/SCID/IL2rg-/- (NSG) mice reconstituted with human hematopoietic stem cells (HSCs) and other precursors from an unrelated donor. In aHM, bone marrow-derived human immune and mesenchymal cells homed into the growing tumor and interacted with human cancer cells as they would in a patient, partially reversing the gene expression drift that occurs after tumor passage on immune compromised mice. Further work is aimed at improving upon this platform. In summary, we have developed a HNSCC model covering its clinical spectrum whose major genetic alterations and susceptibility to anticancer agents represent contemporary HNSCC. Then, we have generated an aHM model to enable immune biology and therapy exploration in HNSCC. These models will enable prospectively testing therapeutic-oriented hypotheses leading to enhanced precision medicine, especially in the field of immune therapy. Citation Format: Antonio Jimeno. PDX models in head and neck cancers: Present status and future application for immune-oriented biology and therapy development. [abstract]. In: Proceedings of the AACR Special Conference: Patient-Derived Cancer Models: Present and Future Applications from Basic Science to the Clinic; Feb 11-14, 2016; New Orleans, LA. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(16_Suppl):Abstract nr IA14.

Lumbar Myeloid Cell Trafficking into Locomotor Networks after Thoracic Spinal Cord Injury

Spinal cord injury (SCI) promotes inflammation along the neuroaxis that jeopardizes plasticity, intrinsic repair and recovery. While inflammation at the injury site is well-established, less is known within remote spinal networks. The presence of bone marrow-derived immune (myeloid) cells in these areas may further impede functional recovery. Previously, high levels of the gelatinase, matrix metalloproteinase-9 (MMP-9) occurred within the lumbar enlargement after thoracic SCI and impeded activity-dependent recovery. Since SCI-induced MMP-9 potentially increases vascular permeability, myeloid cell infiltration may drive inflammatory toxicity in locomotor networks. Therefore, we examined neurovascular reactivity and myeloid cell infiltration in the lumbar cord after thoracic SCI. We show evidence of region-specific recruitment of myeloid cells into the lumbar but not cervical region. Myeloid infiltration occurred with concomitant increases in chemoattractants (CCL2) and cell adhesion molecules (ICAM-1) around lumbar vasculature 24h and 7days post injury. Bone marrow GFP chimeric mice established robust infiltration of bone marrow-derived myeloid cells into the lumbar gray matter 24h after SCI. This cell infiltration occurred when the blood-spinal cord barrier was intact, suggesting active recruitment across the endothelium. Myeloid cells persisted as ramified macrophages at 7days post injury in parallel with increased inhibitory GAD67 labeling. Importantly, macrophage infiltration required MMP-9.

Brain radiation injury leads to a dose- and time-dependent recruitment of peripheral myeloid cells that depends on CCR2 signaling.

BackgroundCranial radiotherapy is used to treat tumors of the central nervous system (CNS), as well as non-neoplastic conditions such as arterio-venous malformations; however, its use is limited by the tolerance of adjacent normal CNS tissue, which can lead to devastating long-term sequelae for patients. Despite decades of research, the underlying mechanisms by which radiation induces CNS tissue injury remain unclear. Neuroinflammation and immune cell infiltration are a recognized component of the CNS radiation response; however, the extent and mechanisms by which bone marrow-derived (BMD) immune cells participate in late radiation injury is unknown. Thus, we set out to better characterize the response and tested the hypothesis that C-C chemokine receptor type 2 (CCR2) signaling was required for myeloid cell recruitment following brain irradiation.MethodsWe used young adult C57BL/6 male bone marrow chimeric mice created with donor mice that constitutively express enhanced green fluorescent protein (eGFP). The head was shielded to avoid brain radiation exposure during chimera construction. Radiation dose and time response studies were conducted in wild-type chimeras, and additional experiments were performed with chimeras created using donor marrow from CCR2 deficient, eGFP-expressing mice. Infiltrating eGFP+ cells were identified and quantified using immunofluorescent microscopy.ResultsBrain irradiation resulted in a dose- and time-dependent infiltration of BMD immune cells (predominately myeloid) that began at 1 month and persisted until 6 months following ≥15 Gy brain irradiation. Infiltration was limited to areas that were directly exposed to radiation. CCR2 signaling loss resulted in decreased numbers of infiltrating cells at 6 months that appeared to be restricted to cells also expressing major histocompatibility complex class II molecules.ConclusionsThe potential roles played by infiltrating immune cells are of current importance due to increasing interest in immunotherapeutic approaches for cancer treatment and a growing clinical interest in survivorship and quality of life issues. Our findings demonstrate that injury from brain radiation facilitates a dose- and time-dependent recruitment of BMD cells that persists for at least 6 months and, in the case of myeloid cells, is dependent on CCR2 signaling.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-016-0496-8) contains supplementary material, which is available to authorized users.

Anti-inflammatory and anti-diabetic effects of brown seaweeds in high-fat diet-induced obese mice.

BACKGROUND/OBJECTIVESSeaweeds have been reported to have various health beneficial effects. In this study, we investigated the potential anti-obesity and anti-inflammatory effects of four types of domestic brown seaweeds in a high-fat diet-induced obese mouse model and bone marrow-derived macrophages (BMDM).MATERIALS/METHODSMale C57BL/6N mice were fed low-fat diet (LFD), high-fat diet (HFD) or HFD containing Undaria Pinnatifida, HFD containing Laminaria Japonica (LJ), HFD containing Sargassum Fulvellum, or HFD containing Hizikia Fusiforme (HF) for 16 weeks.RESULTSBrown seaweed supplementation did not affect long-term HFD-associated changes in body weight or adiposity, although mice fed HFD + LJ or HFD + HF gained slightly less body weight compared with those fed HFD at the beginning of feeding. Despite being obese, mice fed HFD + LJ appeared to show improved insulin sensitivity compared to mice fed HFD. Consistently, we observed significantly reduced blood glucose concentrations in mice fed HFD + LJ compared with those of mice fed HFD. Although no significant differences in adipocyte size were detected among the HFD-fed groups, consumption of seaweeds decreased formation of HFD-induced crown-like structures in gonadal adipose tissue as well as plasma inflammatory cytokines. BMDM from mice fed HFDs with seaweeds showed differential regulation of pro-inflammatory cytokines such as IL-1β and IL-6 compared with BMDM from mice fed HFD by LPS stimulation.CONCLUSIONAlthough seaweed consumption did not prevent long-term HFD-induced obesity in C57BL/6N mice, it reduced insulin resistance (IR) and circulation of pro-inflammatory cytokines. Therefore, seaweeds may ameliorate systemic inflammation and IR in obesity partially due to inhibition of inflammatory signaling in adipose tissue cells as well as bone marrow-derived immune cells.