Thrombopoietin mimetic stimulates bone marrow vascular and stromal niches to mitigate acute radiation syndrome

BACKGROUND

Acute radiation syndrome (ARS) manifests after exposure to high doses of radiation in the instances of radiologic accidents or incidents. Facilitating regeneration of the bone marrow (BM), namely the hematopoietic stem and progenitor cells (HSPCs), is key in mitigating ARS and multi-organ failure. JNJ-26366821, a PEGylated thrombopoietin mimetic (TPOm) peptide, has been shown as an effective medical countermeasure (MCM) to treat hematopoietic-ARS (H-ARS) in mice. However, the activity of TPOm on regulating BM vascular and stromal niches to support HSPC regeneration has yet to be elucidated.

METHODS

C57BL/6J mice (9-14 weeks old) received sublethal or lethal total body irradiation (TBI), a model for H-ARS, by 137Cs or X-rays. At 24 h post-irradiation, mice were subcutaneously injected with a single dose of TPOm (0.3 mg/kg or 1.0 mg/kg) or PBS (vehicle). At homeostasis and on days 4, 7, 10, 14, 18, and 21 post-TBI with and without TPOm treatment, BM was harvested for histology, BM flow cytometry of HSPCs, endothelial (EC) and mesenchymal stromal cells (MSC), and whole-mount confocal microscopy. For survival, irradiated mice were monitored and weighed for 30 days. Lastly, BM triple negative cells (TNC; CD45-, TER-119-, CD31-) were sorted for single-cell RNA-sequencing to examine transcriptomics after TBI with or without TPOm treatment.

RESULTS

At homeostasis, TPOm expanded the number of circulating platelets and HSPCs, ECs, and MSCs in the BM. Following sublethal TBI, TPOm improved BM architecture and promoted recovery of HSPCs, ECs, and MSCs. Furthermore, TPOm elevated VEGF-C levels in normal and irradiated mice. Following lethal irradiation, mice improved body weight recovery and 30-day survival when treated with TPOm after 137Cs and X-ray exposure. Additionally, TPOm reduced vascular dilation and permeability. Finally, single-cell RNA-seq analysis indicated that TPOm increased the expression of collagens in MSCs to enhance their interaction with other progenitors in BM and upregulated the regeneration pathway in MSCs.

CONCLUSIONS

TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI. Therefore, this work warrants the development of TPOm as a potent radiation MCM for the treatment of ARS.

Thrombopoietin mimetic stimulates bone marrow vascular and stromal niches to mitigate acute radiation syndrome

Background

Acute radiation syndrome (ARS) manifests after exposure to high doses of radiation in the instances of radiologic accidents or incidents. Facilitating the regeneration of the bone marrow (BM), namely the hematopoietic stem and progenitor cells (HSPCs), is a key in mitigating ARS and multi-organ failure. JNJ-26366821, a PEGylated thrombopoietin mimetic (TPOm) peptide, has been shown as an effective medical countermeasure (MCM) to treat hematopoietic-ARS (H-ARS) in mice. However, the activity of TPOm on regulating BM vascular and stromal niches to support HSPC regeneration has not yet been elucidated.

Methods

C57BL/6J mice (9-14 weeks old) received sublethal or lethal total body irradiation (TBI), a model for H-ARS, by 137Cs or X-rays. At 24 hours post-irradiation, mice were subcutaneously injected with a single dose of TPOm (0.3 mg/kg or 1.0 mg/kg) or PBS (vehicle). At homeostasis and on days 4, 7, 10, 14, 18, and 21 post-TBI with and without TPOm treatment, BM was harvested for histology, BM flow cytometry of HSPCs, endothelial (EC) and mesenchymal stromal cells (MSC), and whole-mount confocal microscopy. For survival, irradiated mice were monitored and weighed for 30 days. Lastly, BM triple negative cells (TNC; CD45-, TER-119-, CD31-) were sorted for single-cell RNA-sequencing to examine transcriptomics after TBI with or without TPOm treatment.

Results

At homeostasis, TPOm expanded the number of circulating platelets and HSPCs, ECs, and MSCs in the BM. Following sublethal TBI, TPOm improved BM architecture and promoted recovery of HSPCs, ECs, and MSCs. Furthermore, TPOm elevated VEGF-C levels in normal and irradiated mice. Following lethal irradiation, mice improved body weight recovery and 30-day survival when treated with TPOm after 137Cs and X-ray exposure. Additionally, TPOm reduced vascular dilation and permeability. Finally, single-cell RNA-seq analysis indicated that TPOm increased the expression of collagens in MSCs to enhance their interaction with other progenitors in BM and upregulated the regeneration pathway in MSCs.

Conclusions

TPOm interacts with BM vascular and stromal niches to locally support hematopoietic reconstitution and systemically improve survival in mice after TBI. Therefore, this work warrants the development of TPOm as a potent radiation MCM for the treatment of ARS.

Haematopoietic stem cell numbers are not solely determined by niche availability

Haematopoietic stem cells (HSCs) reside in specialized microenvironments, also referred to as niches, and it has been widely believed that HSC numbers are determined by the niche size alone 1-5 . However, the vast excess of the number of niche cells over that of HSCs raises questions about this model. We initially established a mathematical model of niche availability and occupancy, which predicted that HSC numbers are restricted at both systemic and local levels. To address this question experimentally, we developed a femoral bone transplantation system, enabling us to increase the number of available HSC niches. We found that the addition of niches does not alter total HSC numbers in the body, regardless of whether the endogenous (host) niche is intact or defective, suggesting that HSC numbers are limited at the systemic level. Additionally, HSC numbers in transplanted wild-type femurs did not increase beyond physiological levels when HSCs were mobilized from defective endogenous niches to the periphery, indicating that HSC numbers are also constrained at the local level. Our study demonstrates that HSC numbers are not solely determined by niche availability, thereby rewriting the long-standing model for the regulation of HSC numbers.

Tissue-resident glial cells associate with tumoral vasculature and promote cancer progression

Cancer cells are embedded within the tissue and interact dynamically with its components during cancer progression. Understanding the contribution of cellular components within the tumor microenvironment is crucial for the success of therapeutic applications. Here, we reveal the presence of perivascular GFAP+/Plp1+ cells within the tumor microenvironment. Using in vivo inducible Cre/loxP mediated systems, we demonstrated that these cells derive from tissue-resident Schwann cells. Genetic ablation of endogenous Schwann cells slowed down tumor growth and angiogenesis. Schwann cell-specific depletion also induced a boost in the immune surveillance by increasing tumor-infiltrating anti-tumor lymphocytes, while reducing immune-suppressor cells. In humans, a retrospective in silico analysis of tumor biopsies revealed that increased expression of Schwann cell-related genes within melanoma was associated with improved survival. Collectively, our study suggests that Schwann cells regulate tumor progression, indicating that manipulation of Schwann cells may provide a valuable tool to improve cancer patients' outcomes.

Periosteal skeletal stem cells can migrate into the bone marrow and support hematopoiesis after injury

Functional stromal cells are known to support bone marrow regeneration after chemotherapy or radiation-induced injury to prevent prolonged myelosuppression. However, it is not known how stromal cells within the bone marrow are regenerated after injury. We have utilized a whole bone transplantation model that mimics the initial bone marrow necrosis and fatty infiltration that is seen after bone marrow injury and subsequent recovery. We demonstrate that periosteal skeletal stem cells (P-SSCs) can migrate into the bone marrow and contribute to stromal regeneration and hematopoietic recovery. Once in the bone marrow, P-SSCs are phenotypically and functionally reprogrammed into bone marrow mesenchymal stem cells (BM-MSCs), expressing high levels of hematopoietic stem cell (HSC) niche factors, such as Cxcl12 and Kitl. Additionally, our results further indicate that P-SSCs are more resistant to acute stress than BM-MSCs. Here, we report a new function of P-SSCs, highlighting their major plasticity and the role of the periosteum as a potential source of BM-MSCs following acute bone marrow injury.

Dietary iron restriction protects against vaso-occlusion and organ damage in murine sickle cell disease

Sickle cell disease (SCD) is an inherited disorder resulting from a β-globin gene mutation, and SCD patients experience erythrocyte sickling, vaso-occlusive episodes (VOE), and progressive organ damage. Chronic hemolysis, inflammation, and repeated red blood cell transfusions in SCD can disrupt iron homeostasis. Patients who receive multiple blood transfusions develop iron overload, and another subpopulation of SCD patients manifest iron deficiency. To elucidate connections between dietary iron, the microbiome, and SCD pathogenesis, we treated SCD mice with an iron-restricted diet (IRD). IRD treatment reduced iron availability and hemolysis, decreased acute VOE, and ameliorated chronic organ damage in SCD mice. Our results extend previous studies indicating that the gut microbiota regulate disease in SCD mice. IRD alters microbiota load and improves gut integrity, together preventing crosstalk between the gut microbiome and inflammatory factors such as aged neutrophils, dampening VOE, and organ damage. These findings provide strong evidence for the therapeutic potential of manipulating iron homeostasis and the gut microbiome to ameliorate SCD pathophysiology. Many treatments, which are under development, focus on lowering the systemic iron concentration to relieve disease complications, and our data suggest that iron-induced changes in microbiota load and gut integrity are related- and novel-therapeutic targets.

Whole bone subcutaneous transplantation as a strategy to study precisely the bone marrow niche

Hematopoietic stem cells are maintained in a specialized microenvironment, known as the 'niche', within the bone marrow. Understanding the contribution of cellular and molecular components within the bone marrow niche for the maintenance of hematopoietic stem cells is crucial for the success of therapeutic applications. So far, the roles of crucial mechanisms within the bone marrow niche have been explored in transgenic animals in which genetic modifications are ubiquitously introduced in the whole body. The lack of precise tools to explore genetic alterations exclusively within the bone marrow prevents our determination of whether the observed outcomes result from confounding effects from other organs. Here, we developed a new method - 'whole bone subcutaneous transplantation'- to study the bone marrow niche in transgenic animals precisely. Using immunolabeling of CD45.1 (donor) vs. CD45.2 (recipient) hematopoeitic stem cells, we demonstrated that hematopoeitic stem cells from the host animals colonize the subcutaneously transplanted femurs after transplantation, while the hematopoietic stem cells from the donor disappear. Strikinlgy, the bone marrow niche of these subcutaneously transplanted femurs remain from the donor mice, enabling us to study specifically cells of the bone marrow niche using this model. We also showed that genetic ablation of peri-arteriolar cells specifically in donor femurs reduced the numbers of hematopoietic stem cells in these bones. This supports the use of this strategy as a model, in combination with genetic tools, to evaluate how bone marrow niche specific modifications may impact non-modified hematopoietic stem cells. Thus, this approach can be utilized for genetic manipulation in vivo of specific cell types only within the bone marrow. The combination of whole bone subcutaneous transplantation with rodent transgenic models will facilitate a more precise, complex and comprehensive understanding of existing problems in the study of the hematopoietic stem cell bone marrow niche.

Brain motor and fear circuits regulate leukocytes during acute stress

The nervous and immune systems are intricately linked¹. Although psychological stress is known to modulate immune function, mechanistic pathways linking stress networks in the brain to peripheral leukocytes remain poorly understood². Here we show that distinct brain regions shape leukocyte distribution and function throughout the body during acute stress in mice. Using optogenetics and chemogenetics, we demonstrate that motor circuits induce rapid neutrophil mobilization from the bone marrow to peripheral tissues through skeletal-muscle-derived neutrophil-attracting chemokines. Conversely, the paraventricular hypothalamus controls monocyte and lymphocyte egress from secondary lymphoid organs and blood to the bone marrow through direct, cell-intrinsic glucocorticoid signalling. These stress-induced, counter-directional, population-wide leukocyte shifts are associated with altered disease susceptibility. On the one hand, acute stress changes innate immunity by reprogramming neutrophils and directing their recruitment to sites of injury. On the other hand, corticotropin-releasing hormone neuron-mediated leukocyte shifts protect against the acquisition of autoimmunity, but impair immunity to SARS-CoV-2 and influenza infection. Collectively, these data show that distinct brain regions differentially and rapidly tailor the leukocyte landscape during psychological stress, therefore calibrating the ability of the immune system to respond to physical threats.

Tet-mediated DNA demethylation regulates specification of hematopoietic stem and progenitor cells during mammalian embryogenesis

Ten-eleven translocation (Tet) enzymes promote DNA demethylation by oxidizing 5-methylcytosine. They are expressed during development and are essential for mouse gastrulation. However, their postgastrulation functions are not well established. We find that global or endothelial-specific loss of all three Tet enzymes immediately after gastrulation leads to reduced number of hematopoietic stem and progenitor cells (HSPCs) and lethality in mid-gestation mouse embryos. This is due to defects in specification of HSPCs from endothelial cells (ECs) that compromise primitive and definitive hematopoiesis. Mechanistically, loss of Tet enzymes in ECs led to hypermethylation and down-regulation of NFκB1 and master hematopoietic transcription factors (Gata1/2, Runx1, and Gfi1b). Restoring Tet catalytic activity or overexpression of these factors in Tet-deficient ECs rescued hematopoiesis defects. This establishes Tet enzymes as activators of hematopoiesis programs in ECs for specification of HSPCs during embryogenesis, which is distinct from their roles in adult hematopoiesis, with implications in deriving HSPCs from pluripotent cells.

VCAM1 confers innate immune tolerance on haematopoietic and leukaemic stem cells

Haematopoietic stem cells (HSCs) home to the bone marrow via, in part, interactions with vascular cell adhesion molecule-1 (VCAM1)^1-3. Once in the bone marrow, HSCs are vetted by perivascular phagocytes to ensure their self-integrity. Here we show that VCAM1 is also expressed on healthy HSCs and upregulated on leukaemic stem cells (LSCs), where it serves as a quality-control checkpoint for entry into bone marrow by providing 'don't-eat-me' stamping in the context of major histocompatibility complex class-I (MHC-I) presentation. Although haplotype-mismatched HSCs can engraft, Vcam1 deletion, in the setting of haplotype mismatch, leads to impaired haematopoietic recovery due to HSC clearance by mononuclear phagocytes. Mechanistically, VCAM1 'don't-eat-me' activity is regulated by β2-microglobulin MHC presentation on HSCs and paired Ig-like receptor-B (PIR-B) on phagocytes. VCAM1 is also used by cancer cells to escape immune detection as its expression is upregulated in multiple cancers, including acute myeloid leukaemia (AML), where high expression associates with poor prognosis. In AML, VCAM1 promotes disease progression, whereas VCAM1 inhibition or deletion reduces leukaemia burden and extends survival. These results suggest that VCAM1 engagement regulates a critical immune-checkpoint gate in the bone marrow, and offers an alternative strategy to eliminate cancer cells via modulation of the innate immune tolerance.

The microbiota regulates hematopoietic stem cell fate decisions by controlling iron availability in bone marrow

Host microbiota crosstalk is essential for the production and functional modulation of blood-cell lineages. Whether, and if so how, the microbiota influences hematopoietic stem cells (HSCs) is unclear. Here, we show that the microbiota regulates HSC self-renewal and differentiation under stress conditions by modulating local iron availability in the bone marrow (BM). In microbiota-depleted mice, HSC self-renewal was enhanced during regeneration, while the commitment toward differentiation was dramatically compromised. Mechanistically, microbiota depletion selectively impaired the recycling of red blood cells (RBCs) by BM macrophages, resulting in reduced local iron levels without affecting systemic iron homeostasis. Limiting iron availability in food (in vivo) or in culture (ex vivo), or by CD169⁺ macrophage depletion, enhanced HSC self-renewal and expansion. These results reveal an intricate interplay between the microbiota, macrophages, and iron, and their essential roles in regulating critical HSC fate decisions under stress.

Olinciguat, a stimulator of soluble guanylyl cyclase, attenuates inflammation, vaso-occlusion and nephropathy in mouse models of sickle cell disease

BACKGROUND AND PURPOSE

Reduced bioavailability of NO, a hallmark of sickle cell disease (SCD), contributes to intravascular inflammation, vasoconstriction, vaso-occlusion and organ damage observed in SCD patients. Soluble guanylyl cyclase (sGC) catalyses synthesis of cGMP in response to NO. cGMP-amplifying agents, including NO donors and phosphodiesterase 9 inhibitors, alleviate TNFα-induced inflammation in wild-type C57BL/6 mice and in 'humanised' mouse models of SCD.

EXPERIMENTAL APPROACH

Effects of the sGC stimulator olinciguat on intravascular inflammation and renal injury were studied in acute (C57BL6 and Berkeley mice) and chronic (Townes mice) mouse models of TNFα-induced and systemic inflammation associated with SCD.

KEY RESULTS

Acute treatment with olinciguat attenuated increases in plasma biomarkers of endothelial cell activation and leukocyte-endothelial cell interactions in TNFα-challenged mice. Co-treatment with hydroxyurea, an FDA-approved SCD therapeutic agent, further augmented the anti-inflammatory effect of olinciguat. In the Berkeley mouse model of TNFα-induced vaso-occlusive crisis, a single dose of olinciguat attenuated leukocyte-endothelial cell interactions, improved blood flow and prolonged survival time compared to vehicle-treated mice. In Townes SCD mice, plasma biomarkers of inflammation and endothelial cell activation were lower in olinciguat- than in vehicle-treated mice. In addition, kidney mass, water consumption, 24-h urine excretion, plasma levels of cystatin C and urinary excretion of N-acetyl-β-d-glucosaminidase and neutrophil gelatinase-associated lipocalin were lower in Townes mice treated with olinciguat than in vehicle-treated mice.

CONCLUSION AND IMPLICATIONS

Our results suggest that the sGC stimulator olinciguat attenuates inflammation, vaso-occlusion and kidney injury in mouse models of SCD and systemic inflammation.

Nociceptors protect sickle cell disease mice from vaso-occlusive episodes and chronic organ damage

Sickle cell disease (SCD) is a common hereditary hematologic disorder. SCD patients suffer from acute vaso-occlusive episodes (VOEs), chronic organ damage, and premature death, with few therapeutic options. Although severe pain is a major clinical manifestation of SCD, it remains unknown whether nociception plays a role in SCD pathogenesis. To address this question, we generated nociceptor-deficient SCD mice and found, unexpectedly, that the absence of nociception led to more severe and more lethal VOE, indicating that somatosensory nerves protect SCD mice from VOE. Mechanistically, the beneficial effects of sensory nerves were induced by the neuropeptide calcitonin gene–related peptide (CGRP), which acted on hematopoietic cells. Additionally, oral capsaicin consumption, which can activate somatosensory nerves by binding to TRPV1, dramatically alleviated acute VOE and significantly prevented chronic liver and kidney damage in SCD mice. Thus, the manipulation of nociception may provide a promising approach to treat SCD.

MAEA is an E3 ubiquitin ligase promoting autophagy and maintenance of haematopoietic stem cells

Haematopoietic stem cells (HSCs) tightly regulate their quiescence, proliferation, and differentiation to generate blood cells during the entire lifetime. The mechanisms by which these critical activities are balanced are still unclear. Here, we report that Macrophage-Erythroblast Attacher (MAEA, also known as EMP), a receptor thus far only identified in erythroblastic island, is a membrane-associated E3 ubiquitin ligase subunit essential for HSC maintenance and lymphoid potential. Maea is highly expressed in HSCs and its deletion in mice severely impairs HSC quiescence and leads to a lethal myeloproliferative syndrome. Mechanistically, we have found that the surface expression of several haematopoietic cytokine receptors (e.g. MPL, FLT3) is stabilised in the absence of Maea, thereby prolonging their intracellular signalling. This is associated with impaired autophagy flux in HSCs but not in mature haematopoietic cells. Administration of receptor kinase inhibitor or autophagy-inducing compounds rescues the functional defects of Maea-deficient HSCs. Our results suggest that MAEA provides E3 ubiquitin ligase activity, guarding HSC function by restricting cytokine receptor signalling via autophagy.

Using CT-guided stereotactic prostate radiation therapy (CT-SPRT) to assess sustained murine prostate ablation

The prostate is a hormone-responsive organ where testicular androgens drive the proliferation and survival of prostatic cells, ensuring the development and functioning of this gland throughout life. Androgen deprivation therapy leads to apoptosis of prostatic cells and organ regression, and is a cornerstone of prostate cancer and benign prostatic hypertrophy treatment. For several decades, androgen deprivation has been used as an adjuvant to external beam radiotherapy, however, emerging data suggests that the low rates of epithelial proliferation in the castrated prostate imparts radio-resistance. As proliferating cells exhibit increased sensitivity to radiation, we hypothesized that short bursts of synchronized epithelial proliferation, which can be achieved by exogeneous testosterone supplementation prior to targeted high-dose radiation, would maximize sustained prostate ablation, while minimizing damage to surrounding tissues. To test this hypothesis, we designed a novel computed-tomography (CT)-guided stereotactic prostate radiation therapy (CT-SPRT) technique to deliver a single high-dose 25 Gy fraction of X-ray radiation. Sustained prostatic cell ablation was assessed post CT-SPRT by measuring prostate weight, epithelial cell number, and relative contributions of luminal and basal epithelial populations in control and testosterone-pretreated glands. CT-SPRT was safely delivered with no observed damage to surrounding rectal and bladder tissues. Importantly, castrated mice that received a pulse of testosterone to induce synchronous cell proliferation prior to CT-SPRT exhibited significant sustained gland ablation compared to control mice. These results provide new insights in stereotactic radiotherapy sensitivity to maximize prostatic cell ablation and improve our understanding of prostate gland regeneration that can potentially lead to improved non-invasive therapies for benign prostatic hypertrophy and prostate cancer.

Niche derived netrin-1 regulates hematopoietic stem cell dormancy via its receptor neogenin-1

Haematopoietic stem cells (HSCs) are characterized by their self-renewal potential associated to dormancy. Here we identify the cell surface receptor neogenin-1 as specifically expressed in dormant HSCs. Loss of neogenin-1 initially leads to increased HSC expansion but subsequently to loss of self-renewal and premature exhaustion in vivo. Its ligand netrin-1 induces Egr1 expression and maintains quiescence and function of cultured HSCs in a Neo1 dependent manner. Produced by arteriolar endothelial and periarteriolar stromal cells, conditional netrin-1 deletion in the bone marrow niche reduces HSC numbers, quiescence and self-renewal, while overexpression increases quiescence in vivo. Ageing associated bone marrow remodelling leads to the decline of netrin-1 expression in niches and a compensatory but reversible upregulation of neogenin-1 on HSCs. Our study suggests that niche produced netrin-1 preserves HSC quiescence and self-renewal via neogenin-1 function. Decline of netrin-1 production during ageing leads to the gradual decrease of Neo1 mediated HSC self-renewal.

Nociceptive nerves regulate haematopoietic stem cell mobilization

Haematopoietic stem cells (HSCs) reside in specialized microenvironments in the bone marrow-often referred to as 'niches'-that represent complex regulatory milieux influenced by multiple cellular constituents, including nerves^1,2. Although sympathetic nerves are known to regulate the HSC niche^3-6, the contribution of nociceptive neurons in the bone marrow remains unclear. Here we show that nociceptive nerves are required for enforced HSC mobilization and that they collaborate with sympathetic nerves to maintain HSCs in the bone marrow. Nociceptor neurons drive granulocyte colony-stimulating factor (G-CSF)-induced HSC mobilization via the secretion of calcitonin gene-related peptide (CGRP). Unlike sympathetic nerves, which regulate HSCs indirectly via the niche^3,4,6, CGRP acts directly on HSCs via receptor activity modifying protein 1 (RAMP1) and the calcitonin receptor-like receptor (CALCRL) to promote egress by activating the Gα_s/adenylyl cyclase/cAMP pathway. The ingestion of food containing capsaicin-a natural component of chili peppers that can trigger the activation of nociceptive neurons-significantly enhanced HSC mobilization in mice. Targeting the nociceptive nervous system could therefore represent a strategy to improve the yield of HSCs for stem cell-based therapeutic agents.

Future directions in preclinical and translational cancer neuroscience research

Recent advances in cancer neuroscience necessitate the systematic analysis of neural influences in cancer as potential therapeutic targets in oncology. Here, we outline recommendations for future preclinical and translational research in this field.

Use of beta-blocker types and risk of incident prostate cancer in a multiethnic population

PURPOSE

Increased adrenergic innervation is observed in prostate cancer (CaP) and is associated with aggressive disease. Emerging evidence suggests that beta-adrenergic blockade inhibits CaP progression. However, the association between type of beta-blocker use and risk of incident CaP on initial prostate biopsy has not been investigated in multiethnic populations.

MATERIALS AND METHODS

A retrospective study of racially/ethnically diverse men (64% African-American and Hispanic), who underwent initial prostate biopsy between 2006 and 2016 in a large healthcare system was performed. Oral use of beta-blocker type was assessed by reviewing active prescriptions within the 5-year period preceding initial biopsy. Patient demographics and clinical factors were collected.

RESULTS

Of 4,607 men who underwent initial prostate biopsy, 4,516 met criteria and 2,128 had a biopsy positive for CaP; 20% high-risk, 41% intermediate-risk, and 39% low or very-low risk (National Comprehensive Cancer Network classification). Overall, 15% of patients were taking a beta-blocker prior to initial biopsy, with Metoprolol, Atenolol, and Carvedilol accounting for the majority. Of beta-blocker types, Atenolol alone was associated with a 38% reduction in odds of incident CaP (P= 0.01), with a 40% and 54% reduction in risks of National Comprehensive Cancer Network intermediate and high-risk CaP (P = 0.03 and P = 0.03, respectively) compared to men not taking a beta-blocker. Furthermore, longer duration of Atenolol use (3-5 years) was associated with a 54% and 72% reduction in intermediate and high-risk disease, (P = 0.03 and P = 0.03, respectively).

CONCLUSIONS

Among beta blocker types, long-term Atenolol use is associated with a significant reduction in incident CaP risk on initial prostate biopsy for clinically-significant intermediate and high-risk disease compared to men not taking a beta-blocker.

The Gut Microbiome Regulates Psychological-Stress-Induced Inflammation

Psychological stress has adverse effects on various human diseases, including those of the cardiovascular system. However, the mechanisms by which stress influences disease activity remain unclear. Here, using vaso-occlusive episodes (VOEs) of sickle cell disease as a vascular disease model, we show that stress promotes VOEs by eliciting a glucocorticoid hormonal response that augments gut permeability, leading to microbiota-dependent interleukin-17A (IL-17A) secretion from T helper 17 (Th17) cells of the lamina propria, followed by the expansion of the circulating pool of aged neutrophils that trigger VOEs. We identify segmented filamentous bacteria as the commensal essential for the stress-induced expansion of aged neutrophils that enhance VOEs in mice. Importantly, the inhibition of glucocorticoids synthesis, blockade of IL-17A, or depletion of the Th17 cell-inducing gut microbiota markedly reduces stress-induced VOEs. These results offer potential therapeutic targets to limit the impact of psychological stress on acute vascular occlusion.

Clinically Actionable Strategies for Studying Neural Influences in Cancer

Neuro-glial activation is a recently identified hallmark of growing cancers. Targeting tumor hyperinnervation in preclinical and small clinical trials has yielded promising antitumor effects, highlighting the need of systematic analysis of neural influences in cancer (NIC). Here, we outline the strategies translating these findings from bench to the clinic.

Beneficial Effects of Soluble Guanylyl Cyclase Stimulation and Activation in Sickle Cell Disease Are Amplified by Hydroxyurea: In Vitro and In Vivo Studies

The complex pathophysiology of sickle cell anemia (SCA) involves intravascular hemolytic processes and recurrent vaso-occlusion, driven by chronic vascular inflammation, which result in the disease’s severe clinical complications, including recurrent painful vaso-occlusive episodes. Hydroxyurea, the only drug frequently used for SCA therapy, is a cytostatic agent, although it appears to exert nitric oxide/soluble guanylyl cyclase (sGC) modulating activity. As new drugs that can complement or replace the use of hydroxyurea are sought to further reduce vaso-occlusive episode frequency in SCA, we investigated the effects of the sGC agonists BAY 60-2770 (sGC activator) and BAY 41-2272 (sGC stimulator) in the presence or absence of hydroxyurea on SCA vaso-occlusive mechanisms and cell recruitment both ex vivo and in vivo. These agents significantly reduced stimulated human SCA neutrophil adhesive properties ex vivo in association with the inhibition of surface β2-integrin activation. A single administration of BAY 60-2770 or BAY 41-2272 decreased tumor necrosis factor cytokine–induced leukocyte recruitment in a mouse model of SCA vaso-occlusion. Importantly, the in vivo actions of both agonists were significantly potentiated by the coadministration of hydroxyurea. Erythroid cell fetal hemoglobin (HbF) elevation is also a major goal for SCA therapy. BAY 41-2272 but not BAY 60-2770 at the concentrations employed significantly induced γ-globin gene transcription in association with HbF production in cultured erythroleukemic cells. In conclusion, sGC agonist drugs could represent a promising approach as therapy for SCA, for use either as stand-alone treatments or in combination with hydroxyurea.

Snai2 Maintains Bone Marrow Niche Cells by Repressing Osteopontin Expression

Bone marrow (BM) mesenchymal stem and progenitor cells (MSPCs) are a critical constituent of the hematopoietic stem cell (HSC) niche. Previous studies have suggested that the zinc-finger epithelial-mesenchymal transition transcription factor Snai2 (also known as Slug) regulated HSCs autonomously. Here, we show that Snai2 expression in the BM is restricted to the BM stromal compartment where it regulates the HSC niche. Germline or MSPC-selective Snai2 deletion reduces the functional MSPC pool and their mesenchymal lineage output and impairs HSC niche function during homeostasis and after stress. RNA sequencing analysis revealed that Spp1 (osteopontin) expression is markedly upregulated in Snai2-deficient MSPCs. Genetic deletion of Spp1 in Snai2-deficient mice rescues MSPCs' functions. Thus, SNAI2 is a critical regulator of the transcriptional network maintaining MSPCs by the suppression of osteopontin expression.

Dietary Intake Regulates the Circulating Inflammatory Monocyte Pool

Caloric restriction is known to improve inflammatory and autoimmune diseases. However, the mechanisms by which reduced caloric intake modulates inflammation are poorly understood. Here we show that short-term fasting reduced monocyte metabolic and inflammatory activity and drastically reduced the number of circulating monocytes. Regulation of peripheral monocyte numbers was dependent on dietary glucose and protein levels. Specifically, we found that activation of the low-energy sensor 5'-AMP-activated protein kinase (AMPK) in hepatocytes and suppression of systemic CCL2 production by peroxisome proliferator-activator receptor alpha (PPARα) reduced monocyte mobilization from the bone marrow. Importantly, we show that fasting improves chronic inflammatory diseases without compromising monocyte emergency mobilization during acute infectious inflammation and tissue repair. These results reveal that caloric intake and liver energy sensors dictate the blood and tissue immune tone and link dietary habits to inflammatory disease outcome.

Roadmap for the Emerging Field of Cancer Neuroscience

Mounting evidence indicates that the nervous system plays a central role in cancer pathogenesis. In turn, cancers and cancer therapies can alter nervous system form and function. This Commentary seeks to describe the burgeoning field of "cancer neuroscience" and encourage multidisciplinary collaboration for the study of cancer-nervous system interactions.

Haematopoietic stem cell activity and interactions with the niche

The haematopoietic stem cell (HSC) microenvironment in the bone marrow, termed the niche, ensures haematopoietic homeostasis by controlling the proliferation, self-renewal, differentiation and migration of HSCs and progenitor cells at steady state and in response to emergencies and injury. Improved methods for HSC isolation, driven by advances in single-cell and molecular technologies, have led to a better understanding of their behaviour, heterogeneity and lineage fate and of the niche cells and signals that regulate their function. Niche regulatory signals can be in the form of cell-bound or secreted factors and other local physical cues. A combination of technological advances in bone marrow imaging and genetic manipulation of crucial regulatory factors has enabled the identification of several candidate cell types regulating the niche, including both non-haematopoietic (for example, perivascular mesenchymal stem and endothelial cells) and HSC-derived (for example, megakaryocytes, macrophages and regulatory T cells), with better topographical understanding of HSC localization in the bone marrow. Here, we review advances in our understanding of HSC regulation by niches during homeostasis, ageing and cancer, and we discuss their implications for the development of therapies to rejuvenate aged HSCs or niches or to disrupt self-reinforcing malignant niches.

Nerves in cancer

The contribution of nerves to the pathogenesis of malignancies has emerged as an important component of the tumour microenvironment. Recent studies have shown that peripheral nerves (sympathetic, parasympathetic and sensory) interact with tumour and stromal cells to promote the initiation and progression of a variety of solid and haematological malignancies. Furthermore, new evidence suggests that cancers may reactivate nerve-dependent developmental and regenerative processes to promote their growth and survival. Here we review emerging concepts and discuss the therapeutic implications of manipulating nerves and neural signalling for the prevention and treatment of cancer.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Artery-Associated Sympathetic Innervation Drives Rhythmic Vascular Inflammation of Arteries and Veins

BACKGROUND

The incidence of acute cardiovascular complications is highly time-of-day dependent. However, the mechanisms driving rhythmicity of ischemic vascular events are unknown. Although enhanced numbers of leukocytes have been linked to an increased risk of cardiovascular complications, the role that rhythmic leukocyte adhesion plays in different vascular beds has not been studied.

METHODS

We evaluated leukocyte recruitment in vivo by using real-time multichannel fluorescence intravital microscopy of a tumor necrosis factor-α-induced acute inflammation model in both murine arterial and venous macrovasculature and microvasculature. These approaches were complemented with genetic, surgical, and pharmacological ablation of sympathetic nerves or adrenergic receptors to assess their relevance for rhythmic leukocyte adhesion. In addition, we genetically targeted the key circadian clock gene Bmal1 (also known as Arntl) in a lineage-specific manner to dissect the importance of oscillations in leukocytes and components of the vessel wall in this process.

RESULTS

In vivo quantitative imaging analyses of acute inflammation revealed a 24-hour rhythm in leukocyte recruitment to arteries and veins of the mouse macrovasculature and microvasculature. Unexpectedly, although in arteries leukocyte adhesion was highest in the morning, it peaked at night in veins. This phase shift was governed by a rhythmic microenvironment and a vessel type-specific oscillatory pattern in the expression of promigratory molecules. Differences in cell adhesion molecules and leukocyte adhesion were ablated when disrupting sympathetic nerves, demonstrating their critical role in this process and the importance of β₂-adrenergic receptor signaling. Loss of the core clock gene Bmal1 in leukocytes, endothelial cells, or arterial mural cells affected the oscillations in a vessel type-specific manner. Rhythmicity in the intravascular reactivity of adherent leukocytes resulted in increased interactions with platelets in the morning in arteries and in veins at night with a higher predisposition to acute thrombosis at different times as a consequence.

CONCLUSIONS

Together, our findings point to an important and previously unrecognized role of artery-associated sympathetic innervation in governing rhythmicity in vascular inflammation in both arteries and veins and its potential implications in the occurrence of time-of-day-dependent vessel type-specific thrombotic events.

Nestin+NG2+ Cells Form a Reserve Stem Cell Population in the Mouse Prostate

In the prostate, stem and progenitor cell regenerative capacities have been ascribed to both basal and luminal epithelial cells. Here, we show that a rare subset of mesenchymal cells in the prostate are epithelial-primed Nestin-expressing cells (EPNECs) that can generate self-renewing prostate organoids with bipotential capacity. Upon transplantation, these EPNECs can form prostate gland tissue grafts at the clonal level. Lineage-tracing analyses show that cells marked by Nestin or NG2 transgenic mice contribute to prostate epithelium during organogenesis. In the adult, modest contributions in repeated rounds of regression and regeneration are observed, whereas prostate epithelial cells derived from Nestin/NG2-marked cells are dramatically increased after severe irradiation-induced organ damage. These results indicate that Nestin/NG2 expression marks a novel radioresistant prostate stem cell that is active during development and displays reserve stem cell activity for tissue maintenance.

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The murine prostate mesenchyme contains epithelial-primed Nestin⁺ cells

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Nestin⁺ cells generate self-renewing prostate organoids and glands at clonal level

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NG2/Nestin⁺ cells contribute to prostate epithelium during organogenesis

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NG2/Nestin⁺ cells retain reserve stem cell activity for tissue regeneration in the adult

Engineering a haematopoietic stem cell niche by revitalizing mesenchymal stromal cells

Haematopoietic stem cells (HSCs) are maintained by bone marrow (BM) niches in vivo^1,2, but the ability of niche cells to maintain HSCs ex vivo is markedly diminished. Expression of niche factors by Nestin-GFP⁺ mesenchymal-derived stromal cells (MSCs) is downregulated upon culture, suggesting that transcriptional rewiring may contribute to this reduced HSC maintenance potential. Using an RNA sequencing screen, we identified 5 transcription factors (Klf7, Ostf1, Xbp1, Irf3, Irf7) that restored HSC niche function in cultured BM-derived MSCs. These revitalized MSCs (rMSCs) exhibited enhanced synthesis of HSC niche factors while retaining their mesenchymal differentiation capacity. In contrast to HSCs co-cultured with control MSCs, HSCs expanded with rMSCs showed higher repopulation capacity and protected lethally irradiated recipient mice. Competitive reconstitution assays revealed ~7-fold expansion of functional HSCs by rMSCs. rMSCs prevented the accumulation of DNA damage in cultured HSCs, a hallmark of ageing and replication stress. Analysis of the reprogramming mechanisms uncovered a role for myocyte enhancer factor 2c (Mef2c) in the revitalization of MSCs. These results provide insight in the transcriptional regulation of the niche with implications for stem cell-based therapies.

The bone marrow microenvironment at single-cell resolution

The bone marrow microenvironment has a key role in regulating haematopoiesis, but its molecular complexity and response to stress are incompletely understood. Here we map the transcriptional landscape of mouse bone marrow vascular, perivascular and osteoblast cell populations at single-cell resolution, both at homeostasis and under conditions of stress-induced haematopoiesis. This analysis revealed previously unappreciated levels of cellular heterogeneity within the bone marrow niche and resolved cellular sources of pro-haematopoietic growth factors, chemokines and membrane-bound ligands. Our studies demonstrate a considerable transcriptional remodelling of niche elements under stress conditions, including an adipocytic skewing of perivascular cells. Among the stress-induced changes, we observed that vascular Notch delta-like ligands (encoded by Dll1 and Dll4) were downregulated. In the absence of vascular Dll4, haematopoietic stem cells prematurely induced a myeloid transcriptional program. These findings refine our understanding of the cellular architecture of the bone marrow niche, reveal a dynamic and heterogeneous molecular landscape that is highly sensitive to stress and illustrate the utility of single-cell transcriptomic data in evaluating the regulation of haematopoiesis by discrete niche populations.

The Majority of CD45- Ter119- CD31- Bone Marrow Cell Fraction Is of Hematopoietic Origin and Contains Erythroid and Lymphoid Progenitors

The non-hematopoietic cell fraction of the bone marrow (BM) is classically identified as CD45^- Ter119^- CD31^- (herein referred to as triple-negative cells or TNCs). Although TNCs are believed to contain heterogeneous stromal cell populations, they remain poorly defined. Here we showed that the vast majority of TNCs (∼85%) have a hematopoietic rather than mesenchymal origin. Single cell RNA-sequencing revealed erythroid and lymphoid progenitor signatures among CD51^- TNCs. Ly6D⁺ CD44⁺ CD51^- TNCs phenotypically and functionally resembled CD45⁺ pro-B lymphoid cells, whereas Ly6D^- CD44⁺ CD51^- TNCs were enriched in previously unappreciated stromal-dependent erythroid progenitors hierarchically situated between preCFU-E and proerythroblasts. Upon adoptive transfer, CD44⁺ CD51^- TNCs contributed to repopulate the B-lymphoid and erythroid compartments. CD44⁺ CD51^- TNCs also expanded during phenylhydrazine-induced acute hemolysis or in a model of sickle cell anemia. These findings thus uncover physiologically relevant new classes of stromal-associated functional CD45^- hematopoietic progenitors.

Neural Regulation of Bone and Bone Marrow

Bones provide both skeletal scaffolding and space for hematopoiesis in its marrow. Previous work has shown that these functions were tightly regulated by the nervous system. The central and peripheral nervous systems tightly regulate compact bone remodeling, its metabolism, and hematopoietic homeostasis in the bone marrow (BM). Accumulating evidence indicates that the nervous system, which fine-tunes inflammatory responses and alterations in neural functions, may regulate autoimmune diseases. Neural signals also influence the progression of hematological malignancies such as acute and chronic myeloid leukemias. Here, we review the interplay of the nervous system with bone, BM, and immunity, and discuss future challenges to target hematological diseases through modulation of activity of the nervous system.

Niches for Hematopoietic Stem Cells and Their Progeny

Steady-state hematopoietic stem cells' (HSCs) self-renewal and differentiation toward their mature progeny in the adult bone marrow is tightly regulated by cues from the microenvironment. Recent insights into the cellular and molecular constituents have uncovered a high level of complexity. Here, we review emerging evidence showing how HSCs and their progeny are regulated by an interdependent network of mesenchymal stromal cells, nerve fibers, the vasculature, and also other hematopoietic cells. Understanding the interaction mechanisms in these intricate niches will provide great opportunities for HSC-related therapies and immune modulation.

CD150high Bone Marrow Tregs Maintain Hematopoietic Stem Cell Quiescence and Immune Privilege via Adenosine

A crucial player in immune regulation, FoxP3+ regulatory T cells (Tregs) are drawing attention for their heterogeneity and noncanonical functions. Here, we describe a Treg subpopulation that controls hematopoietic stem cell (HSC) quiescence and engraftment. These Tregs highly expressed an HSC marker, CD150, and localized within the HSC niche in the bone marrow (BM). Specific reduction of BM Tregs achieved by conditional deletion of CXCR4 in Tregs increased HSC numbers in the BM. Adenosine generated via the CD39 cell surface ectoenzyme on niche Tregs protected HSCs from oxidative stress and maintained HSC quiescence. In transplantation settings, niche Tregs prevented allogeneic (allo-) HSC rejection through adenosine and facilitated allo-HSC engraftment. Furthermore, transfer of niche Tregs promoted allo-HSC engraftment to a much greater extent than transfer of other Tregs. These results identify a unique niche-associated Treg subset and adenosine as regulators of HSC quiescence, abundance, and engraftment, further highlighting their therapeutic utility.

Lineage-Biased Hematopoietic Stem Cells Are Regulated by Distinct Niches

The spatial localization of hematopoietic stem cells (HSCs) in the bone marrow (BM) remains controversial, with some studies suggesting that they are maintained in homogeneously distributed niches while others have suggested the contributions of distinct niche structures. Subsets of quiescent HSCs have been reported to associate with megakaryocytes (MK) or arterioles in the BM. However, these HSC subsets have not been prospectively defined. Here, we show that platelet and myeloid-biased HSCs, marked by von Willebrand factor (vWF) expression, are highly enriched in MK niches. Depletion of MK selectively expands vWF⁺ HSCs, whereas the depletion of NG2⁺ arteriolar niche cells selectively depletes vWF^- lymphoid-biased HSCs. In addition, MK depletion compromises vWF⁺ HSC function by reducing their long-term self-renewal capacity and eliminating their lineage bias after transplantation. These studies demonstrate the existence of two spatially and functionally separate BM niches for HSC subsets with distinct developmental potential.

The hematopoietic stem cell niche: from embryo to adult

Hematopoietic stem cells (HSCs) develop in discrete anatomical niches, migrating during embryogenesis from the aorta-gonad-mesonephros (AGM) region to the fetal liver, and finally to the bone marrow, where most HSCs reside throughout adult life. These niches provide supportive microenvironments that specify, expand and maintain HSCs. Understanding the constituents and molecular regulation of HSC niches is of considerable importance as it could shed new light on the mechanistic principles of HSC emergence and maintenance, and provide novel strategies for regenerative medicine. However, controversy exists concerning the cellular complexity of the bone marrow niche, and our understanding of the different HSC niches during development remains limited. In this Review, we summarize and discuss what is known about the heterogeneity of the HSC niches at distinct stages of their ontogeny, from the embryo to the adult bone marrow, drawing predominantly on data from mouse studies.

Adrenergic nerves activate an angio-metabolic switch in prostate cancer

Nerves closely associate with blood vessels and help to pattern the vasculature during development. Recent work suggests that newly formed nerve fibers may regulate the tumor microenvironment, but their exact functions are unclear. Studying mouse models of prostate cancer, we show that endothelial β-adrenergic receptor signaling via adrenergic nerve-derived noradrenaline in the prostate stroma is critical for activation of an angiogenic switch that fuels exponential tumor growth. Mechanistically, this occurs through alteration of endothelial cell metabolism. Endothelial cells typically rely on aerobic glycolysis for angiogenesis. We found that the loss of endothelial Adrb2, the gene encoding the β₂-adrenergic receptor, leads to inhibition of angiogenesis through enhancement of endothelial oxidative phosphorylation. Codeletion of Adrb2 and Cox10, a gene encoding a cytochrome IV oxidase assembly factor, prevented the metabolic shift induced by Adrb2 deletion and rescued prostate cancer progression. This cross-talk between nerves and endothelial metabolism could potentially be targeted as an anticancer therapy.

A non-cell-autonomous role for Pml in the maintenance of leukemia from the niche

Disease recurrence after therapy, due to the persistence of resistant leukemic cells, represents a fundamental problem in the treatment of leukemia. Elucidating the mechanisms responsible for the maintenance of leukemic cells, before and after treatment, is therefore critical to identify curative modalities. It has become increasingly clear that cell-autonomous mechanisms are not solely responsible for leukemia maintenance. Here, we report a role for Pml in mesenchymal stem cells (MSCs) in supporting leukemic cells of both CML and AML. Mechanistically, we show that Pml regulates pro-inflammatory cytokines within MSCs, and that this function is critical in sustaining CML-KLS and AML ckit+ leukemic cells non-cell autonomously.

Stimulation of adrenergic activity by desipramine enhances hematopoietic stem and progenitor cell mobilization along with G-CSF in multiple myeloma: A pilot study

Hematopoietic stem cell (HSC) release is positively regulated by the sympathetic nervous system through the β3 adrenergic receptor. Preclinical studies have demonstrated that the combination of desipramine and G-CSF resulted in improved HSC mobilization. Here, we present the results of an open-label single-arm pilot study in patients with multiple myeloma undergoing autologous stem cell transplantation (ASCT) to assess the safety and efficacy of desipramine combined with G-SCF to induce HSC mobilization. The primary endpoint was safety of the combination including engraftment kinetics. The secondary endpoint was the proportion of patients who collected ≥5 × 10⁶ CD34⁺ cells/kg. Outcomes were compared with historical matched controls during the same time period with multiple myeloma mobilized with G-CSF. All study patients received desipramine 100 mg daily for 7 days, starting 4 days prior to G-CSF administration (D-3) and continued taking it along with G-CSF for a total of 7 days. Six of ten patients enrolled completed the protocol with minimal side effects. All of them achieved the target collection of 5 × 10⁶ CD34 cells/kg in a median of 1.5 apheresis session with two patients needing additional plerixafor (16%), while 11 out of 13 patients (85%) achieved the target of 5 × 10⁶ CD34 cells/kg in the historical control group in a median of 2 apheresis procedures and seven patients needed plerixafor (54%). The combination of desipramine and G-CSF is safe and signals improved mobilization over G-CSF alone, providing a possible alternative means of mobilization that needs further investigation.

T-Regulating Hair Follicle Stem Cells

Regulatory T (Treg) cells are well known to modulate inflammatory responses. In a recent issue of Cell, Ali et al. (2017) reveal a function for Treg cells in stem cell maintenance by showing that skin-resident Foxp3⁺ Treg cells preferentially localize to the hair follicle stem cell (HFSC) niche to control HFSC-mediated hair regeneration.

HSC Contribution in Making Steady-State Blood

In homeostasis, whether blood cells are derived from committed progenitor or mutipotent stem cell activity remains controversial. In this issue of Immunity, Sawai et al. (2016) describe murine HSCs as the major contributor to the maintenance of multilineage hematopoiesis, both in the steady state and during cytokine response.

Abstract 1821: Sympathetic nerves regulate a metabolic switch promoting angiogenesis through adrenergic signaling in prostate cancer

Nerves pattern the vasculature during development and regeneration. Recent studies have shown that the sympathetic nervous system (SNS) is coopted to promote carcinogenesis, and that depletion of SNS β-adrenergic receptors (βARs) in the prostate stromal compartment inhibits tumor growth. As the vasculature is in direct contact with the SNS, and regulates tumor glucose and oxygen delivery, we aimed to identify the stromal populations that mediate SNS signaling and the mechanisms by which loss of βAR signaling inhibits prostate cancer progression. In vivo xenograft tumor growth was measured in Adrb2-/-; Adrb3-/- mice using an orthotopic PC3-luciferase model. Prostate cancer progression in the transgenic autochthonous HI-myc model was assessed after conditional Adrb2 deletion in stromal populations by intercrossing Adrb2fl/fl line to stromal Cre lines. Metabolism was measured ex vivo by flow quantification of the lipophilic cationic dye TMRE whose accumulation reflects mitochondrial membrane potential, and by NADH autofluorescence under UV excitation. In vitro oxidative phosphorylation and glycolytic flux were measured in primary prostate endothelial cells (VeraVec) using the Seahorse bioanalyzer and targeted gas chromatography-mass spectrometry (GC/MS). Deletion of the SNS βAR neural receptors in the microenvironment synergized to arrest exponential tumor growth. Imaging the tumor vasculature revealed a defect in vessel branching, a phenotype also observed after chemical sympathectomy, suggesting altered angiogenesis in the absence of βAR stimulation. Histology revealed an increase in vascular innervation and density during the transition from low to high grade pre-neoplastic PIN. Conditional Adrb2 deletion (Adrb2cKO) in endothelial cells (ECs), but not myeloid cells or pericytes, not only inhibited angiogenesis, but also reduced disease progression throughout all histopathological cancer stages. Transcriptome analysis of flow isolated Adrb2cKO ECs suggested an increase in oxidative metabolism and upregulation of mitochondrial Coa6. Ex vivo analysis of ECs revealed a metabolic switch during the low to high grade PIN transition, and this switch was inhibited by Adrb2cKO. Further in vitro characterization by Adrb2 knockdown revealed a metabolic shift in ECs to oxidative phosphorylation, which was mediated by Coa6 upregulation. As Coa6 cooperates with Cox10 in respiratory complex IV assembly, conditional co-deletion of Adrb2 and Cox10 in the HI-myc mouse rescued aerobic glycolysis, angiogenesis, and cancer progression. Our data thus demonstrates that the SNS mediates a pro-angiogenic switch during the early stages of prostate carcinogenesis. Moreover, we identified ECs as SNS stromal targets, and that abrogation of βAR signaling inhibits the angio-metabolic switch and delays prostate cancer progression, suggesting a novel therapeutic target for prostate cancer treatment.

Citation Format: Ali Zahalka, Anna Arnal-Estape, Maria Maryanovich, Fumio Nakahara, Cristian Cruz, Paul S. Frenette. Sympathetic nerves regulate a metabolic switch promoting angiogenesis through adrenergic signaling in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1821. doi:10.1158/1538-7445.AM2017-1821

Complexity of bone marrow hematopoietic stem cell niche

Hematopoietic stem cells (HSCs) that produce a variety of hematopoietic lineage cells throughout the life reside in specialized microenvironment called "niche" in the bone marrow (BM) where they are tightly regulated. With the recent advances in experimental technologies enabling the selective deletion of molecules, various types of cells in the BM have been proposed to contribute to HSC niche activity. Among these are stromal cells closely associated with the vasculature. In this review, we provide an overview of recent advances in HSC niche research, and focus on the studies describing the functional roles of perivascular cells for HSC maintenance and mobilization. Not only for physiologic state, we also discuss the recent evidences suggesting the importance of microenvironment for emergence of malignant hematopoietic diseases.