Hematopoietic cytokines

Osteogenic Commitment of MSC Is Enhanced after Interaction with Umbilical Cord Blood Mononuclear Cells In Vitro

The effectiveness of stroma-dependent expansion of hematopoietic cells ex vivo may depend on the level of commitment of multipotent mesenchymal stromal cells (MSC). Markers of MSC osteodifferentiation and the level of soluble hematopoiesis regulators were determined during their interaction with umbilical cord blood mononuclears. After 72-h co-culturing, an increase in the expression of ALPL and alkaline phosphatase activity was revealed. In conditioned medium of co-cultures, the levels of osteopontin and osteoprotegerin were elevated and the levels of osteocalcin and sclerostin were reduced. Co-culturing of umbilical cord blood mononuclears with osteocommitted MSC was accompanied by more pronounced increase in the concentration of both positive (GM-CSF and G-CSF) and negative (IP-10, MIP-1α, and MCP-3) regulators of hematopoiesis. Thus, umbilical cord blood mononuclears induced the formation of early osteogenic progenitor phenotype in MSC ex vivo, providing the microenvironmental conditions necessary to support hematopoiesis. Preliminary osteocommitted MSC were more sensitive to the effect of umbilical cord blood mononuclears.

FDA-Approved Drug Screening for Compounds That Facilitate Hematopoietic Stem and Progenitor Cells (HSPCs) Expansion in Zebrafish

Hematopoietic stem cells (HSCs) are a specialized subset of cells with self-renewal and multilineage differentiation potency, which are essential for their function in bone marrow or umbilical cord blood transplantation to treat blood disorders. Expanding the hematopoietic stem and progenitor cells (HSPCs) ex vivo is essential to understand the HSPCs-based therapies potency. Here, we established a screening system in zebrafish by adopting an FDA-approved drug library to identify candidates that could facilitate HSPC expansion. To date, we have screened 171 drugs of 7 categories, including antibacterial, antineoplastic, glucocorticoid, NSAIDS, vitamins, antidepressant, and antipsychotic drugs. We found 21 drugs that contributed to HSPCs expansion, 32 drugs’ administration caused HSPCs diminishment and 118 drugs’ treatment elicited no effect on HSPCs amplification. Among these drugs, we further investigated the vitamin drugs ergocalciferol and panthenol, taking advantage of their acceptability, limited side-effects, and easy delivery. These two drugs, in particular, efficiently expanded the HSPCs pool in a dose-dependent manner. Their application even mitigated the compromised hematopoiesis in an ikzf1^−/− mutant. Taken together, our study implied that the larval zebrafish is a suitable model for drug repurposing of effective molecules (especially those already approved for clinical use) that can facilitate HSPCs expansion.

Sargramostim (rhu GM-CSF) as Cancer Therapy (Systematic Review) and An Immunomodulator. A Drug Before Its Time?

BACKGROUND

Sargramostim [recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF)] was approved by US FDA in 1991 to accelerate bone marrow recovery in diverse settings of bone marrow failure and is designated on the list of FDA Essential Medicines, Medical Countermeasures, and Critical Inputs. Other important biological activities including accelerating tissue repair and modulating host immunity to infection and cancer via the innate and adaptive immune systems are reported in pre-clinical models but incompletely studied in humans.

OBJECTIVE

Assess safety and efficacy of sargramostim in cancer and other diverse experimental and clinical settings.

METHODS AND RESULTS

We systematically reviewed PubMed, Cochrane and TRIP databases for clinical data on sargramostim in cancer. In a variety of settings, sargramostim after exposure to bone marrow-suppressing agents accelerated hematologic recovery resulting in fewer infections, less therapy-related toxicity and sometimes improved survival. As an immune modulator, sargramostim also enhanced anti-cancer responses in solid cancers when combined with conventional therapies, for example with immune checkpoint inhibitors and monoclonal antibodies.

CONCLUSIONS

Sargramostim accelerates hematologic recovery in diverse clinical settings and enhances anti-cancer responses with a favorable safety profile. Uses other than in hematologic recovery are less-well studied; more data are needed on immune-enhancing benefits. We envision significantly expanded use of sargramostim in varied immune settings. Sargramostim has the potential to reverse the immune suppression associated with sepsis, trauma, acute respiratory distress syndrome (ARDS) and COVID-19. Further, sargramostim therapy has been promising in the adjuvant setting with vaccines and for anti-microbial-resistant infections and treating autoimmune pulmonary alveolar proteinosis and gastrointestinal, peripheral arterial and neuro-inflammatory diseases. It also may be useful as an adjuvant in anti-cancer immunotherapy.

The Effect of Oxygen and Micronutrient Composition of Cell Growth Media on Cancer Cell Bioenergetics and Mitochondrial Networks

Cancer cell culture is routinely performed under superphysiologic O₂ levels and in media such as Dulbecco's Modified Eagle Medium (DMEM) with nutrient composition dissimilar to mammalian extracellular fluid. Recently developed cell culture media (e.g., Plasmax, Human Plasma-Like Medium (HPLM)), which are modeled on the metabolite composition of human blood plasma, have been shown to shift key cellular activities in several cancer cell lines. Similar effects have been reported with respect to O₂ levels in cell culture. Given these observations, we investigated how media composition and O₂ levels affect cellular energy metabolism and mitochondria network structure in MCF7, SaOS2, LNCaP, and Huh7 cells. Cells were cultured in physiologic (5%) or standard (18%) O₂ levels, and in physiologic (Plasmax) or standard cell culture media (DMEM). We show that both O₂ levels and media composition significantly affect mitochondrial abundance and network structure, concomitantly with changes in cellular bioenergetics. Extracellular acidification rate (ECAR), a proxy for glycolytic activity, was generally higher in cells cultured in DMEM while oxygen consumption rates (OCR) were lower. This effect of media on energy metabolism is an important consideration for the study of cancer drugs that target aspects of energy metabolism, including lactate dehydrogenase activity.

Engineered Cytokines for Cancer and Autoimmune Disease Immunotherapy

Cytokine signaling is critical to a range of biological processes including cell development, tissue repair, aging, and immunity. In addition to acting as key signal mediators of the immune system, cytokines can also serve as potent immunotherapies with more than 20 recombinant products currently Food and Drug Administration (FDA)-approved to treat conditions including hepatitis, multiple sclerosis, arthritis, and various cancers. Yet despite their biological importance and clinical utility, cytokine immunotherapies suffer from intrinsic challenges that limit their therapeutic potential including poor circulation, systemic toxicity, and low tissue- or cell-specificity. In the past decade in particular, methods have been devised to engineer cytokines in order to overcome such challenges and here, the myriad strategies are reviewed that may be employed in order to improve the therapeutic potential of cytokine and chemokine immunotherapies with applications in cancer and autoimmune disease therapy, as well as tissue engineering and regenerative medicine. For clarity, these strategies are collected and presented as they vary across size scales, ranging from single amino acid substitutions, to larger protein-polymer conjugates, nano/micrometer-scale particles, and macroscale implants. Together, this work aims to provide readers with a timely view of the field of cytokine engineering with an emphasis on early-stage therapeutic approaches.

Humoral Effect of a B-Cell Tumor on the Bone Marrow Multipotent Mesenchymal Stromal Cells

The properties of bone marrow (BM)-derived multipotent mesenchymal stromal cells (MSCs) are altered in the patients with the diffuse large B cell lymphoma (DLBCL) without BM involvement. It was suggested that plasma from the patients contains soluble factors that affect MSCs. Plasma and BM-derived MSCs from the DLBCL patients at the onset of the disease and one month after the end of treatment were studied. Concentration of the plasma cytokines and gene expression in the MSCs were evaluated by the Bio-Plex Pro Human Cytokine Panel kit to measure 27 analytes and real-time PCR. Plasma and MSCs from the healthy donors were used as controls. Analysis of cytokines in the plasma from healthy donors and patients before and one month after the end of treatment revealed significant differences in the concentration of 14 out of 27 cytokines. Correlations between the levels of secreted cytokines were altered in the plasma from patients indicating that the immune response regulation was disturbed. Cultivation of the MSCs from the healthy donors in the medium supplemented with the plasma from patients led to the changes in the MSC properties, similar to those observed in the MSCs from patients. The BM-derived MSCs were shown to participate in the humoral changes occurring in the DLBCL patients. For the first time, it was shown that the precursors of the stromal microenvironment - multipotent mesenchymal stromal cells - are altered in the patients with DLBCL without bone marrow involvement due to the humoral effect of the tumor and the response of organism to it. Comprehensive analysis of the results shows that, when remission is achieved in the patients with DLBCL, composition of the plasma cytokines normalizes, but does not reach the level observed in the healthy donors. The discovery of a new aspect of the effect of the tumor B-cells on the organism could help to reveal general regularities of the humoral effect of various tumors on the bone marrow stromal cells.

Investigation of patient factors associated with the number of transfusions required during chemotherapy for high-risk neuroblastoma

BACKGROUND

Blood transfusion is an important supportive care for high-risk neuroblastoma. When the number of transfusions increases, transfusion-associated adverse reactions may be more problematic. However, the factors determining the degree of myelosuppression and the number of transfusions during chemotherapy for high-risk neuroblastoma remain unclear.

MATERIALS AND METHODS

We investigated patient factors determining the number of required transfusions in 15 high-risk neuroblastoma patients who received five courses of chemotherapy. Clinical data, cytokine profile and colony-forming assay with bone marrow samples at diagnosis were analysed.

RESULTS

The required number of transfusions of both platelets and erythrocytes decreased once in the second course and then increased as the course progressed. The variability among cases increased as the chemotherapy course progressed. In cases of low peripheral blood platelet count and lower fibrinogen level at diagnosis, the number of platelet transfusions was higher during chemotherapy. In contrast, there was a negative correlation between the forming ability of granulocyte-macrophage or erythroid colonies and the number of erythrocyte transfusions in the latter period.

CONCLUSION

In the early stages of chemotherapy, bone marrow infiltration in neuroblastoma and/or coagulopathy complication may cause thrombocytopenia and requirement of platelet transfusion; conversely, in the later stages, the number of erythrocyte transfusions may be defined by the patient's inherent hematopoietic ability. These factors may be useful in predicting the required number of transfusions.

Evolution of cancer stem cell lineage involving feedback regulation

Tumor emergence and progression is a complex phenomenon that assumes special molecular and cellular interactions. The hierarchical structuring and communication via feedback signaling of different cell types, which are categorized as the stem, progenitor, and differentiated cells in dependence of their maturity level, plays an important role. Under healthy conditions, these cells build a dynamical system that is responsible for facilitating the homeostatic regulation of the tissue. Generally, in this hierarchical setting, stem and progenitor cells are yet likely to undergo a mutation, when a cell divides into two daughter cells. This may lead to the development of abnormal characteristics, i.e. mutation in the cell, yielding an unrestrained number of cells. Therefore, the regulation of a stem cell’s proliferation and differentiation rate is crucial for maintaining the balance in the overall cell population. In this paper, a maturity based mathematical model with feedback regulation is formulated for healthy and mutated cell lineages. It is given in the form of coupled ordinary and partial differential equations. The focus is laid on the dynamical effects resulting from acquiring a mutation in the hierarchical structure of stem, progenitor and fully differentiated cells. Additionally, the effects of nonlinear feedback regulation from mature cells into both stem and progenitor cell populations have been inspected. The steady-state solutions of the model are derived analytically. Numerical simulations and results based on a finite volume scheme underpin various expected behavioral patterns of the homeostatic regulation and cancer evolution. For instance, it has been found that the mutated cells can experience significant growth even with a single somatic mutation, but under homeostatic regulation acquire a steady-state and thus, ensuing healthy cell population to either a steady-state or a lower cell concentration. Furthermore, the model behavior has been validated with different experimentally measured tumor values from the literature.

Soluble Prokaryotic Overexpression and Purification of Human GM-CSF Using the Protein Disulfide Isomerase b'a' Domain

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a member of the colony-stimulating factor (CSF) family, which functions to enhance the proliferation and differentiation of hematopoietic stem cells and other hematopoietic lineages such as neutrophils, dendritic cells, or macrophages. These proteins have thus generated considerable interest in clinical therapy research. A current obstacle to the prokaryotic production of human GM-CSF (hGM-CSF) is its low solubility when overexpressed and subsequent complex refolding processes. In our present study, the solubility of hGM-CSF was examined when combined with three N-terminal fusion tags in five E. coli strains at three different expression temperatures. In the five E. coli strains BL21 (DE3), ClearColi BL21 (DE3), LOBSTR, SHuffle T7 and Origami2 (DE3), the hexahistidine-tagged hGM-CSF showed the best expression but was insoluble in all cases at each examined temperature. Tagging with the maltose-binding protein (MBP) and the b'a' domain of protein disulfide isomerase (PDIb'a') greatly improved the soluble overexpression of hGM-CSF at 30 °C and 18 °C. The solubility was not improved using the Origami2 (DE3) and SHuffle T7 strains that have been engineered for disulfide bond formation. Two conventional chromatographic steps were used to purify hGM-CSF from the overexpressed PDIb'a'-hGM-CSF produced in ClearColi BL21 (DE3). In the experiment, 0.65 mg of hGM-CSF was isolated from a 0.5 L flask culture of these E. coli and showed a 98% purity by SDS-PAGE analysis and silver staining. The bioactivity of this purified hGM-CSF was measured at an EC₅₀ of 16.4 ± 2 pM by a CCK8 assay in TF-1 human erythroleukemia cells.

Invasive fungal disease and the immunocompromised host including allogeneic hematopoietic cell transplant recipients: Improved understanding and new strategic approach with sargramostim

In hosts with damaged or impaired immune systems such as those undergoing hematopoietic cell transplant (HCT) or intensive chemotherapy, breakthrough fungal infections can be fatal. Risk factors for breakthrough infections include severe neutropenia, use of corticosteroids, extended use of broad-spectrum antibiotics, and intensive care unit admission. An individual's cumulative state of immunosuppression directly contributes to the likelihood of experiencing increased infection risk. Incidence of invasive fungal infection (IFI) after HCT may be up to 5-8%. Early intervention may improve IFI outcomes, although many infections are resistant to standard therapies (voriconazole, caspofungin, micafungin, amphotericin B, posaconazole or itraconazole, as single agents or in combination). We review herein several contributing factors that may contribute to the net state of immunosuppression in recipients of HCT. We also review a new approach for IFI utilizing adjunctive therapy with sargramostim, a yeast-derived recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF).

Generation and utilization of a HEK-293T murine GM-CSF expressing cell line

Macrophages and dendritic cells (DCs) are innate immune cells that play a key role in defense against pathogens. In vitro cultures of bone marrow-derived macrophages (BMDMs) and dendritic cells (BMDCs) are well-established and valuable methods for immunological studies. Typically, commercially available recombinant GM-CSF is utilized to generate BMDCs and is also used to culture alveolar macrophages. We have generated a new HEK-293T cell line expressing murine GM-CSF that secretes high levels of GM-CSF (~180 ng/ml) into complete media as an alternative to commercial GM-CSF. Differentiation of dendritic cells and expression of various markers were kinetically assessed using the GM-CSF HEK293T cell line, termed supGM-CSF and compared directly to purified commercial GMCSF. After 7–9 days of cell culture the supGM-CSF yielded twice as many viable cells compared to the commercial purified GM-CSF. In addition to differentiating BMDCs, the supGM-CSF can be utilized to culture functionally active alveolar macrophages. Collectively, our results show that supernatant from our GM-CSF HEK293T cell line supports the differentiation of mouse BMDCs or alveolar macrophage culturing, providing an economical alternative to purified GM-CSF.

Therapeutic Targeting of the Tumor Microenvironment

Strategies to therapeutically target the tumor microenvironment (TME) have emerged as a promising approach for cancer treatment in recent years due to the critical roles of the TME in regulating tumor progression and modulating response to standard-of-care therapies. Here, we summarize the current knowledge regarding the most advanced TME-directed therapies, which have either been clinically approved or are currently being evaluated in trials, including immunotherapies, antiangiogenic drugs, and treatments directed against cancer-associated fibroblasts and the extracellular matrix. We also discuss some of the challenges associated with TME therapies, and future perspectives in this evolving field. SIGNIFICANCE: This review provides a comprehensive analysis of the current therapies targeting the TME, combining a discussion of the underlying basic biology with clinical evaluation of different therapeutic approaches, and highlighting the challenges and future perspectives.

Taro Lectin Can Act as a Cytokine-Mimetic Compound, Stimulating Myeloid and T Lymphocyte Lineages and Protecting Progenitors in Murine Bone Marrow

Taro (Colocasia esculenta) corm is traditionally consumed as a medicinal plant to stimulate immune responses and restore a health status. Tarin, a taro lectin, is considered responsible for the immunomodulatory effects of taro. In the present study, in order to investigate the effects of tarin on bone marrow hematopoietic population, murine cells were stimulated with tarin combined with a highly enriched conditioned medium containing either IL-3 or GM-CSF. Cells challenged with tarin proliferated in a dose-dependent manner, evidenced by the increase in cell density and number of clusters and colonies. Tarin exhibited a cytokine-mimetic effect similar to IL-3 and GM-CSF, increasing granulocytic cell lineage percentages, demonstrated by an increase in the relative percentage of Gr-1+ cells. Tarin does not increase lymphocytic lineages, but phenotyping revealed that the relative percentage of CD3+ cells was increased with a concomitant decrease in CD19+ and IL-7Rα+ cells. Most bone marrow cells were stained with tarin-FITC, indicating non-selective tarin binding, a phenomenon that must still be elucidated. In conclusion, taro corms contain an immunomodulatory lectin able to boost the immune system by promoting myeloid and lymphoid hematopoietic progenitor cell proliferation and differentiation.

Single-cell analyses reveal the clonal and molecular aetiology of Flt3L-induced emergency dendritic cell development

Regulation of haematopoietic stem and progenitor cell (HSPC) fate is crucial during homeostasis and under stress conditions. Here we examine the aetiology of the Flt3 ligand (Flt3L)-mediated increase of type 1 conventional dendritic cells (cDC1s). Using cellular barcoding we demonstrate this occurs through selective clonal expansion of HSPCs that are primed to produce cDC1s and not through activation of cDC1 fate by other HSPCs. In particular, multi/oligo-potent clones selectively amplify their cDC1 output, without compromising the production of other lineages, via a process we term tuning. We then develop Divi-Seq to simultaneously profile the division history, surface phenotype and transcriptome of individual HSPCs. We discover that Flt3L-responsive HSPCs maintain a proliferative 'early progenitor'-like state, leading to the selective expansion of multiple transitional cDC1-primed progenitor stages that are marked by Irf8 expression. These findings define the mechanistic action of Flt3L through clonal tuning, which has important implications for other models of 'emergency' haematopoiesis.

Toxicity of poly-dispersed single-walled carbon nanotubes on bone marrow derived Hematopoietic Stem and Progenitor Cells

This study has explored the effect of acid-functionalized single-walled carbon nanotubes (AF-SWCNTs) on Hematopoietic Stem and Progenitor Cell (HSPCs) in mouse bone marrow. Administration of AF-SWCNTs induced a significant decline in the live-cell recovery from bone marrow. Lin-negative Stem cell enriched HSPCs internalized AF-SWCNTs that remained localized in cytoplasmic areas. Incubation of HSPCs with AF-SWCNTs resulted in induction of cell death, inhibition of cell cycle, and induction of reactive oxygen species (ROS) as well as the expression of Caspase 3, 7 and 9 enzymes. In vitro culture with a cytokine cocktail (SCF, GM-CSF, IL3, IL6, IL7) induced differentiation of HSPCs into lymphocytes and myeloid cells, that was inhibited in presence of AF-SWCNTs. Relative recoveries of lymphocytes specifically B lymphocytes, was significantly reduced by AF-SWCNT-treatment, whereas the relative recovery of myeloid cells remained unaltered. These results suggest that AF-SWCNTs have significant toxic effects on HSPCs and differentially suppress the ontogeny of lymphoid and myeloid cells.

Somatic Mutations and the Risk of Undifferentiated Autoinflammatory Disease in MDS: An Under-Recognized but Prognostically Important Complication

Objectives: We theorized that myelodysplastic syndrome (MDS) with somatic mutations and karyotype abnormalities are associated with autoinflammation, and that the presence of autoinflammatory disease affected prognosis in MDS. Methods: One hundred thirty-four MDS patients were assessed for the prevalence of autoinflammatory complications and its link with karyotypes and somatic mutation status. Autoinflammatory complications were described either as well-defined autoinflammatory diseases (AD) or undifferentiated "autoinflammatory disease" (UAD) (defined as CRP over 10.0 mg/L on five consecutive occasions, taken at separate times and not explained by infection). Several patient characteristics including demographic, clinical, laboratory, cytogenetics charts, and outcomes, were compared between different groups. Results: Sixty-two (46.3%) patients had an autoinflammatory complication manifesting as arthralgia (43.5% vs. 23.6%, p = 0.0146), arthritis (30.6% vs. 15.3%, p = 0.0340), skin rash (27.4% vs. 12.5%, p = 0.0301), pleuritis (14.5% vs. 4.2%, p = 0.0371) and unexplained fever (27.4% vs. 0%, p < 0.0001). AD were found in 7.4% of MDS patients (with polymyalgia rheumatic being the most frequently one). Classical autoimmune diseases were found only in 4 MDS patients (3.0%). Transcription factor pathway mutations (RUNX1, BCOR, WTI, TP53) (OR 2.20 [95%CI 1.02-4.75], p = 0.0451) and abnormal karyotypes (OR 2.76 [95%CI 1.22-6.26], p = 0.0153) were associated with autoinflammatory complications. Acute leukaemic transformation was more frequent in MDS patients with autoinflammatory features than those without (27.4% vs. 9.7%, p = 0.0080). Conclusions: Autoinflammatory complications are common in MDS. Somatic mutations of transcription factor pathways and abnormal karyotypes are associated with greater risk of autoinflammatory complications, which are themselves linked to malignant transformation and a worse prognosis.

CSF1R defines the mononuclear phagocyte system lineage in human blood in health and COVID-19

Mononuclear phagocytes defend tissues, present antigens, and mediate recovery and healing. To date, we lack a marker to unify mononuclear phagocytes in humans or that informs us about their origin. Here, we reassess mononuclear phagocyte ontogeny in human blood through the lineage receptor CSF1R, in the steady state and in COVID-19. We define CSF1R as the first sensitive and reproducible pan-phagocyte lineage marker, to identify and enumerate all conventional monocytes, and the myeloid dendritic cells. In the steady state, CSF1R is sufficient for sorting and immuno-magnetic isolation. In pathology, changes in CSF1R are more sensitive than CD14 and CD16. In COVID-19, a significant drop in membrane CSF1R is useful for stratifying patients, beyond the power of cell categories published thus far, which fail to capture COVID-19 specific events. Importantly, CSF1R defines cells which are neither conventional monocytes nor DCs, which are missed in published analysis. CSF1R decrease can be linked ex vivo to high CSF1 levels. Blood assessment of CSF1R+ cells opens a developmental window to the Mononuclear Phagocyte System in transit from bone marrow to tissues, supports isolation and phenotypic characterisation, identifies novel cell types, and singles out CSF1R inhibition as therapeutic target in COVID-19 and other diseases.

Comparative engraftment and clonality of macaque HSPCs expanded on human umbilical vein endothelial cells versus non-expanded cells

Ex vivo hematopoietic stem and progenitor cell (HSPC) expansion platforms are under active development, designed to increase HSPC numbers and thus engraftment ability of allogeneic cord blood grafts or autologous HSPCs for gene therapies. Murine and in vitro models have not correlated well with clinical outcomes of HSPC expansion, emphasizing the need for relevant pre-clinical models. Our rhesus macaque HSPC competitive autologous transplantation model utilizing genetically barcoded HSPC allows direct analysis of the relative short and long-term engraftment ability of lentivirally transduced HSPCs, along with additional critical characteristics such as HSPC clonal diversity and lineage bias. We investigated the impact of ex vivo expansion of macaque HSPCs on the engineered endothelial cell line (E-HUVECs) platform regarding safety, engraftment of transduced and E-HUVEC-expanded HSPC over time compared to non-expanded HSPC for up to 51 months post-transplantation, and both clonal diversity and lineage distribution of output from each engrafted cell source. Short and long-term engraftment were comparable for E-HUVEC expanded and the non-expanded HSPCs in both animals, despite extensive proliferation of CD34⁺ cells during 8 days of ex vivo culture for the E-HUVEC HSPCs, and optimization of harvesting and infusion of HSPCs co-cultured on E-HUVEC in the second animal. Long-term hematopoietic output from both E-HUVEC expanded and unexpanded HSPCs was highly polyclonal and multilineage. Overall, the comparable HSPC kinetics of macaques to humans, the ability to study post-transplant clonal patterns, and simultaneous multi-arm comparisons of grafts without the complication of interpreting allogeneic effects makes our model ideal to test ex vivo HSPC expansion platforms, particularly for gene therapy applications.

Trial Watch: Immunostimulatory cytokines

During the last two decades, a number of approaches for the activation of the immune system against cancer has been developed. These include highly specific interventions, such as monoclonal antibodies, vaccines and cell-based therapies, as well as relatively unselective strategies, such as the systemic administration of adjuvants and immunomodulatory cytokines. Cytokines constitute a huge group of proteins that, taken together, regulate not only virtually all the aspects of innate and cognate immunity, but also several other cellular and organismal functions. Cytokines operate via specific transmembrane receptors that are expressed on the plasma membrane of target cells and, depending on multiple variables, can engage autocrine, paracrine or endocrine signaling pathways. The most appropriate term for defining the cytokine network is “pleiotropic”: cytokines are produced by - and operate on - multiple, often overlapping, cell types, triggering context-depend biological outcomes as diverse as cell proliferation, chemotaxis, differentiation, inflammation, elimination of pathogens and cell death. Moreover, cytokines often induce the release of additional cytokines, thereby engaging self-amplificatory or self-inhibitory signaling cascades. In this Trial Watch, we will summarize the biological properties of cytokines and discuss the progress of ongoing clinical studies evaluating their safety and efficacy as immunomodulatory agents against cancer.

Immunosuppressive Myeloid Cells Induce Nitric Oxide-Dependent DNA Damage and p53 Pathway Activation in CD8+ T Cells

Tumor-infiltrating myeloid-derived suppressor cells (MDSC) are associated with poor survival outcomes in many human cancers. MDSCs inhibit T cell-mediated tumor immunity in part because they strongly inhibit T-cell function. However, whether MDSCs inhibit early or later steps of T-cell activation is not well established. Here we show that MDSCs inhibited proliferation and induced apoptosis of CD8⁺ T cells even in the presence of dendritic cells (DC) presenting a high-affinity cognate peptide. This inhibitory effect was also observed with delayed addition of MDSCs to cocultures, consistent with functional data showing that T cells expressed multiple early activation markers even in the presence of MDSCs. Single-cell RNA-sequencing analysis of CD8⁺ T cells demonstrated a p53 transcriptional signature in CD8⁺ T cells cocultured with MDSCs and DCs. Confocal microscopy showed induction of DNA damage and nuclear accumulation of activated p53 protein in a substantial fraction of these T cells. DNA damage in T cells was dependent on the iNOS enzyme and subsequent nitric oxide release by MDSCs. Small molecule-mediated inhibition of iNOS or inactivation of the Nos2 gene in MDSCs markedly diminished DNA damage in CD8⁺ T cells. DNA damage in CD8⁺ T cells was also observed in KPC pancreatic tumors but was reduced in tumors implanted into Nos2-deficient mice compared with wild-type mice. These data demonstrate that MDSCs do not block early steps of T-cell activation but rather induce DNA damage and p53 pathway activation in CD8⁺ T cells through an iNOS-dependent pathway.

The protective effects of granulocyte-macrophage colony-stimulating factor against radiation-induced lung injury

Background

Radiation-induced lung injury (RILI) is a common complication of thoracic cancer radiation therapy. Currently, there is no effective treatment for RILI. RILI is associated with chronic inflammation, this injury is perpetuated by the stimulation of chemokines and proinflammatory cytokines. Recent studies have demonstrated that granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a pivotal role in inflammation and fibrosis. This study aimed to investigate the protective effect of GM-CSF against the development of RILI in lung tissue.

Method

First, a single fraction of radiation at a dose of 16 Gy was targeted at the entire thorax of wild-type (WT) C57BL/6 mice and GM-CSF^–/– mice to induce RILI. Second, we detected the radioprotective effects of GM-CSF by measuring the inflammatory biomarkers and fibrosis alteration on radiated lung tissues. Furthermore, we investigated the potential mechanism of GM-CSF protective effects in RILI.

Results

The GM-CSF^–/– mice sustained more severe RILI than the WT mice. RILI was significantly alleviated by GM-CSF treatment. Intraperitoneally administered GM-CSF significantly inhibited inflammatory cytokine production and decreased epithelial-mesenchymal transition (EMT) in the RILI mouse model.

Conclusions

GM-CSF was shown to be an important modulator of RILI through regulating inflammatory cytokines, which provides a new strategy for the prevention and treatment of RILI.

Genomic Engineering in Human Hematopoietic Stem Cells: Hype or Hope?

Many gene editing techniques are developed and tested, yet, most of these are optimized for transformed cell lines, which differ from their primary cell counterparts in terms of transfectability, cell death propensity, differentiation capability, and chromatin accessibility to gene editing tools. Researchers are working to overcome the challenges associated with gene editing of primary cells, namely, at the level of improving the gene editing tool components, e.g., the use of modified single guide RNAs, more efficient delivery of Cas9 and RNA in the ribonucleoprotein of these cells. Despite these efforts, the low efficiency of proper gene editing in true primary cells is an obstacle that needs to be overcome in order to generate sufficiently high numbers of corrected cells for therapeutic use. In addition, many of the therapeutic candidate genes for gene editing are expressed in more mature blood cell lineages but not in the hematopoietic stem cells (HSCs), where they are tightly packed in heterochromatin, making them less accessible to gene editing enzymes. Bringing HSCs in proliferation is sometimes seen as a solution to overcome lack of chromatin access, but the induction of proliferation in HSCs often is associated with loss of stemness. The documented occurrences of off-target effects and, importantly, on-target side effects also raise important safety issues. In conclusion, many obstacles still remain to be overcome before gene editing in HSCs for gene correction purposes can be applied clinically. In this review, in a perspective way, we will discuss the challenges of researching and developing a novel genetic engineering therapy for monogenic blood and immune system disorders.

Granulocyte macrophage colony-stimulating factor has come of age: From a vaccine adjuvant to antiviral immunotherapy

GM-CSF acts as a pro-inflammatory cytokine and a key growth factor produced by several immune cells such as macrophages and activated T cells. In this review, we discuss recent studies that point to the crucial role of GM-CSF in the immune response against infections. Upon induction, GM-CSF activates four main signalling networks including the JAK/STAT, PI3K, MAPK, and NFκB pathways. Many of these transduction pathways such as JAK/STAT signal via proteins commonly activated with other antiviral signalling cascades, such as those induced by IFNs. GM-CSF also helps defend against respiratory infections by regulating alveolar macrophage differentiation and enhancing innate immunity in the lungs. Here, we also summarize the numerous clinical trials that have taken advantage of GM-CSF's mechanistic attributes in immunotherapy. Moreover, we discuss how GM-CSF is used as an adjuvant in vaccines and how its activity is interfered with to reduce inflammation such as in the case of COVID-19. This review brings forth the current knowledge on the antiviral actions of GM-CSF, the associated signalling cascades, and its application in immunotherapy.

An expanded role for dipeptidyl peptidase 4 in cell regulation

PURPOSE OF REVIEW

Dipeptidyl peptidase 4 (DPP4) is a serine protease with diverse regulatory functions in healthy and diseased cells. Much remains unknown about the mechanisms and targets of DPP4. Here we discuss new studies exploring DPP4-mediated cellular regulation, provide an updated list of potential targets of DPP4, and discuss clinical implications of each.

RECENT FINDINGS

Recent studies have sought enhanced efficacy of targeting DPP4's role in regulating hematopoietic stem and progenitor cells for improved clinical application. Further studies have identified DPP4 functions in different cellular compartments and have proposed ways to target this protein in malignancy. These findings, together with an expanded list of putative extracellular, cell surface, and intracellular DPP4 targets, provide insight into new DPP4-mediated cell regulation.

SUMMARY

DPP4 posttranslationally modifies proteins and peptides with essential roles in hematopoietic cell regulation, stem cell transplantation, and malignancy. Targets include secreted signaling factors and may include membrane proteins and transcription factors critical for different hematopoietic functions. Knowing these targets and functions can provide insight into new regulatory roles for DPP4 that may be targeted to enhance transplantation, treat disease, and better understand different regulatory pathways of hematopoiesis.

L-carnitine in a certain concentration increases expression of cell surface marker CD34 and apoptosis in the rat bone marrow CD34+ hematopoietic stem cells

BACKGROUND

Stem cell based therapy has been encouraged as an attractive method in regenerative medicine. Poor survival and maintenance of the cells transferred into the damaged tissue are broadly accepted as serious barriers to enhancing the efficacy of regenerative medicine. For this reason, some antioxidants such as L-carnitine (LC) are used as a favorite strategy to improve cell survival and retention properties.

AIMS

This study aims to evaluate the effect of LC on the expression of CD34 marker and its effect on apoptosis and SUZ12 gene expression.

METHODS

Rat bone marrow mono-nuclear cells (rBMNCs) were isolated. Then, CD34+ hematopoietic stem cells (HSCs) were enriched using the magnetic activated cell sorting (MACS) method. The cells were treated with 0.2 and 0.4 mM LC. Gene and protein expression levels of the CD34 were then measured by real-time PCR and flow cytometry, respectively. The percentage of apoptosis and SUZ12 gene expression were measured using the Annexin V/PI method and real-time PCR, respectively.

RESULTS

The results showed that in the experimental group, of the CD34+ HSCs treated with 0.2 mM LC, gene and protein expressions of CD34 increased by 1.7 fold and 0.49%, respectively. At the concentration of 0.4 mM, the early cell apoptosis increased by 25.9% (P<0.05). Also, in the concentration of 0.2 and 0.4 mM LC, the SUZ12 gene expression increased by 1.10 and 1.75 folds compared to the control group (P<0.05 and P<0.01), respectively.

CONCLUSION

The results of this study could be used to improve chronic myeloid leukemia (CML) as a multidirectional therapeutic strategy.

A Review of Evaluating Hematopoietic Stem Cells Derived from Umbilical Cord Blood's Expansion and Homing

Transplantation of hematopoietic stem cells (HSCs) derived from umbilical cord blood (UCB) has been taken into account as a therapeutic approach in patients with hematologic malignancies. Unfortunately, there are limitations concerning HSC transplantation (HSCT), including (a) low contents of UCB-HSCs in a single unit of UCB and (b) defects in UCB-HSC homing to their niche. Therefore, delays are observed in hematopoietic and immunologic recovery and homing. Among numerous strategies proposed, ex vivo expansion of UCB-HSCs to enhance UCB-HSC dose without any differentiation into mature cells is known as an efficient procedure that is able to alter clinical treatments through adjusting transplantation-related results and making them available. Accordingly, culture type, cytokine combinations, O2 level, co-culture with mesenchymal stromal cells (MSCs), as well as gene manipulation of UCB-HSCs can have effects on their expansion and growth. Besides, defects in homing can be resolved by exposing UCB-HSCs to compounds aimed at improving homing. Fucosylation of HSCs before expansion, CXCR4-SDF-1 axis partnership and homing gene involvement are among strategies that all depend on efficiency, reasonable costs, and confirmation of clinical trials. In general, the present study reviewed factors improving the expansion and homing of UCB-HSCs aimed at advancing hematopoietic recovery and expansion in clinical applications and future directions.

Using mathematical models to improve risk-scoring in acute myeloid leukemia

Acute myeloid leukemia (AML) is an aggressive cancer of the blood forming (hematopoietic) system. Due to the high patient variability of disease dynamics, risk-scoring is an important part of its clinical management. AML is characterized by impaired blood cell formation and the accumulation of so-called leukemic blasts in the bone marrow of patients. Recently, it has been proposed to use counts of blood-producing (hematopoietic) stem cells (HSCs) as a biomarker for patient prognosis. In this work, we use a non-linear mathematical model to provide mechanistic evidence for the suitability of HSC counts as a prognostic marker. Using model analysis and computer simulations, we compare different risk-scores involving HSC quantification. We propose and validate a simple approach to improve risk prediction based on HSC and blast counts measured at the time of diagnosis.

Comprehensive Evaluation of Immune-Checkpoint DNA Cancer Vaccines in a Rat Cholangiocarcinoma Model

Cholangiocarcinoma (CCA) is a malignant tumor with aggressive biological behavior. Immune checkpoints such as cytotoxic T-lymphocyte antigen 4 (CTLA4) and antiprogrammed death 1 (PD-1) are critical immune-checkpoint molecules that repress T-cell activation. The DNA vaccine potential against CTLA4 and PD-1 in CCA is unknown. We used a thioacetamide (TAA)-induced intrahepatic cholangiocarcinoma (iCCA) rat model to investigate the DNA vaccine potential against CTLA4, PD-1, and PD-L1. We detected PD-L1 expression in CCA and CD8⁺ T-cell infiltration during CCA progression in rats. We validated antibody production, carcinogenesis, and CD8⁺ T-cell infiltration in rats receiving DNA vaccination against PD-1, PD-L1, or CTLA4. In our TAA-induced iCCA rat model, the expression of PD-L1 and the infiltration of CD8⁺ T cells increased as in rat CCA tumorigenesis. PD-1 antibodies in rats were not increased after receiving PD-1 DNA vaccination, and CCA tumor growth was not suppressed. However, in rats receiving PD-L1–CTLA4 DNA vaccination, CCA tumor growth was inhibited, and the antibodies of PD-L1 and CTLA4 were produced. Furthermore, the number of CD8⁺ T cells was enhanced after PD-L1–CTLA4 DNA vaccination. DNA vaccination targeting CTLA4–PD-L1 triggered the production of specific antibodies and suppressed tumor growth in TAA-induced iCCA rats.

Assessment of hepatic functions, hematopoietic cytokines and haematological parameters in people occupationally exposed to volatile petroleum hydrocarbons

Humans are occupationally exposed to volatile petroleum hydrocarbons through inhalation and ingestion. To access the effect of exposure to volatile hydrocarbons, hematopoietic cytokines, haematological parameters and hepatic functions were assayed for in 100 subjects. Male participants showed significant increase (p < 0.05) in erythropoietin, interleukin-3, alanine transaminase (ALT), alkaline phosphatase (ALP), mean cell hemoglobin concentration (MCHC), mean cell volume (MCV) and significant decrease (p < 0.05) in mean cell hemoglobin (MCH). Female participants showed significant increase (p < 0.05) in interleukin-3, ALT, AST, ALP, MCHC, MCV and significant decrease (p < 0.05) in MCH, platelets, hemoglobin and hematocrit compared to their controls. Exposure to volatile petroleum hydrocarbons raised the absolute red blood cell indices and liver enzymes and could stimulate combined increase in the release of erythropoietin and interleukin-3 leading to ineffective hematopoiesis.

A Review of the Action of Magnesium on Several Processes Involved in the Modulation of Hematopoiesis

Magnesium (Mg²⁺) is an essential mineral for the functioning and maintenance of the body. Disturbances in Mg²⁺ intracellular homeostasis result in cell-membrane modification, an increase in oxidative stress, alteration in the proliferation mechanism, differentiation, and apoptosis. Mg²⁺ deficiency often results in inflammation, with activation of inflammatory pathways and increased production of proinflammatory cytokines by immune cells. Immune cells and others that make up the blood system are from hematopoietic tissue in the bone marrow. The hematopoietic tissue is a tissue with high indices of renovation, and Mg²⁺ has a pivotal role in the cell replication process, as well as DNA and RNA synthesis. However, the impact of the intra- and extracellular disturbance of Mg²⁺ homeostasis on the hematopoietic tissue is little explored. This review deals specifically with the physiological requirements of Mg²⁺ on hematopoiesis, showing various studies related to the physiological requirements and the effects of deficiency or excess of this mineral on the hematopoiesis regulation, as well as on the specific process of erythropoiesis, granulopoiesis, lymphopoiesis, and thrombopoiesis. The literature selected includes studies in vitro, in animal models, and in humans, giving details about the impact that alterations of Mg²⁺ homeostasis can have on hematopoietic cells and hematopoietic tissue.

Human cord blood hematopoietic cells acquire neural features when cultured in the presence of neurogenic cytokines

In vitro growth of hematopoietic cells depends on the presence of hematopoietic cytokines. To date, it is unclear if these cells would be able to respond to non-hematopoietic cytokines. In the present study, we have explored this by culturing human hematopoietic cells in presence of neurogenic cytokines. Lineage-negative (Lin^-) umbilical cord blood (UCB)-derived cells -enriched for hematopoietic stem and progenitor cells- were cultured in presence of different combinations of hematopoietic cytokines, neurotrophins, epidermal growth factor, fibroblast growth factor, and neurogenic culture media, in a 3-phase culture system. A proportion (1-22%) of Lin^- UCB hematopoietic cells normally express neural markers and are capable of responding to neural cytokines. Neural cytokines did not have effects on hematopoietic cell proliferation; however, we observed generation of neural-like cells, assessed by morphology, and a significant increase in the proportion of cells expressing neural markers. Such neural-like cells, however, retained expression of hematopoietic markers. It seems that under our culture conditions, no actual transdifferentiation of hematopoietic cells into neural cells occurred; instead, the cells generated in culture seem to be hematopoietic cells that acquired neural features upon contact with neurogenic factors. The identity of UCB cells that acquired a neural phenotype is still unclear.

In The Blood: Connecting Variant to Function In Human Hematopoiesis

Genome-wide association studies (GWAS) have identified thousands of genetic variants associated with a range of human diseases and traits. However, understanding the mechanisms by which these genetic variants have an impact on associated diseases and traits, often referred to as the variant-to-function (V2F) problem, remains a significant hurdle. Solving the V2F challenge requires us to identify causative genetic variants, relevant cell types/states, target genes, and mechanisms by which variants can cause diseases or alter phenotypic traits. We discuss emerging functional approaches that are being applied to tackle the V2F problem for blood cell traits, illuminating how human genetic variation can impact on key mechanisms in hematopoiesis, as well as highlighting future prospects for this nascent field.

Autocrine Regulation of Interleukin-3 in the Activity of Regulatory T Cells and its Effectiveness in the Pathophysiology of Sepsis

Regulatory T cells (Tregs) play a crucial role in modulating the inflammatory response and participated in sepsis-related immune dysfunctions. However, little is known about the regulatory mechanisms by which Tregs are kept in check during immune responses. Here, we verified the simultaneous expression of interleukin-3 (IL-3) and its receptor (IL-3R) in Tregs. Then, by modulation of IL-3 expression via lentiviral transduction-mediated small interfering RNA, we demonstrated that IL-3 negatively regulated Tregs activity via an autocrine mechanism. Furthermore, we found that anti-IL-3 antibody treatment significantly diminished inflammatory cytokines and organ injury, and improved survival in septic mice, which was associated with enhanced Treg percentage and function. Collectively, these results suggest that IL-3 negatively regulates the activity of Tregs in a previously unrecognized autocrine manner, and plays an important role in the excessive inflammatory response in sepsis, which might be utilized as a therapeutic strategy for the treatment of complications in sepsis.

Regulation of the germinal center and humoral immunity by interleukin-21

Here we review the critical and non-redundant functions of IL-21 in regulating humoral immune responses. We particularly focus on studies in natura—from individuals from inborn errors of immunity that impact on IL-21 production and/or function.

Cytokines play critical roles in regulating the development, survival, differentiation, and function of immune cells. Cytokines exert their function by binding specific receptor complexes on the surface of immune cells and activating intracellular signaling pathways, thereby resulting in induction of specific transcription factors and regulated expression of target genes. While the function of cytokines is often fundamental for the generation of robust and effective immunity following infection or vaccination, aberrant production or function of cytokines can underpin immunopathology. IL-21 is a pleiotropic cytokine produced predominantly by CD4⁺ T cells. Gene-targeting studies in mice, in vitro analyses of human and murine lymphocytes, and the recent discoveries and analyses of humans with germline loss-of-function mutations in IL21 or IL21R have revealed diverse roles of IL-21 in immune regulation and effector function. This review will focus on recent advances in IL-21 biology that have highlighted its critical role in T cell–dependent B cell activation, germinal center reactions, and humoral immunity and how impaired responses to, or production of, IL-21 can lead to immune dysregulation.

Granulopoiesis and Neutrophil Homeostasis: A Metabolic, Daily Balancing Act

Granulopoiesis is part of the hematopoietic hierarchic architecture, where hematopoietic stem cells give rise to highly proliferative multipotent and lineage-committed granulocytic progenitor cells that differentiate into unipotent neutrophil progenitors. Given their short lifespan, neutrophils are rapidly cleared from circulation through specialized efferocytic macrophages. Together with an intrinsic clock, these processes contribute to circadian fluctuations, preserving self-tolerance and protection against invading pathogens. However, metabolic perturbation of granulopoiesis and neutrophil homeostasis can result in low-grade chronic inflammation, as observed with aging. During acute pathogenic infections, hematopoiesis can also be switched into emergency mode, which has been recently associated with significant neutrophil functional heterogeneity. This review focuses on a new reassessment of regulatory mechanisms governing neutrophil production, life-cycle, and diversity in health and disease.

Classic and new mediators for in vitro modelling of human macrophages

Macrophages are key immune cells in the activation and regulation of immune responses. These cells are present in all tissues under homeostatic conditions and in many disease settings. Macrophages can exhibit a wide range of phenotypes depending on local and systemic cues that drive the differentiation and activation process. Macrophage heterogeneity is also defined by their ontogeny. Tissue macrophages can either derive from circulating blood monocytes or are seeded as tissue-resident macrophages during embryonic development. In humans, the study of in vivo-generated macrophages is often difficult with laborious and cell-changing isolation procedures. Therefore, translatable, reproducible, and robust in vitro models for human macrophages in health and disease are necessary. Most of the methods for studying monocyte-derived macrophages are based on the use of limited factors to differentiate the monocytes into macrophages. Current knowledge shows that the in vivo situation is more complex, and a wide range of molecules in the tissue microenvironment promote and impact on monocyte to macrophage differentiation as well as activation. In this review, macrophage heterogeneity is discussed and the human in vitro models that can be applied for research, especially for monocyte-derived macrophages. We also focus on new molecules (IL-34, platelet factor 4, etc.) used to generate macrophages expressing different phenotypes.

Hematopoiesis is regulated by cholesterol efflux pathways and lipid rafts: connections with cardiovascular diseases

Lipid rafts are highly ordered regions of the plasma membrane that are enriched in cholesterol and sphingolipids and play important roles in many cells. In hematopoietic stem and progenitor cells (HSPCs), lipid rafts house receptors critical for normal hematopoiesis. Lipid rafts also can bind and sequester kinases that induce negative feedback pathways to limit proliferative cytokine receptor cycling back to the cell membrane. Modulation of lipid rafts occurs through an array of mechanisms, with optimal cholesterol efflux one of the major regulators. As such, cholesterol homeostasis also regulates hematopoiesis. Increased lipid raft content, which occurs in response to changes in cholesterol efflux in the membrane, can result in prolonged receptor occupancy in the cell membrane and enhanced signaling. In addition, certain diseases, like diabetes, may contribute to lipid raft formation and affect cholesterol retention in rafts. In this review, we explore the role of lipid raft-related mechanisms in hematopoiesis and CVD (specifically, atherosclerosis) and discuss how defective cholesterol efflux pathways in HSPCs contribute to expansion of lipid rafts, thereby promoting myelopoiesis and thrombopoiesis. We also discuss the utility of cholesterol acceptors in contributing to lipid raft regulation and disruption, and highlight the potential to manipulate these pathways for therapeutic gain in CVD as well as other disorders with aberrant hematopoiesis.jlr;61/5/667/F1F1f1.

Calf thymus polypeptide improved hematopoiesis via regulating colony-stimulating factors in BALB/c mice with hematopoietic dysfunction

Calf thymus polypeptide (CTP) is prepared from calf thymus. It has a molecular mass of <10 kilodalton (kDa) and contains 17 types of amino acids. This study investigated the hematopoietic function-improvement effect of CTP in CHRF, K562, and bone marrow mononuclear cells; mice with immunosuppression; and with hematopoietic dysfunction. In mice with immunosuppression, CTP enhanced the cytotoxic activity of natural killer cells and the proliferation of lymphocytes and regulated the levels of immunoglobulins. It also enhanced the proliferation and differentiation of CHRF and K562 cells by upregulating the expression of proliferation- and differentiation-related proteins. In mice with hematopoietic dysfunction, CTP restored white blood cell, neutrophil, and hemoglobin proportions in the peripheral blood and enhanced the levels of B lymphocytes and hematopoietic stem cells and progenitor cells in the bone marrow. CTP effectively regulated the levels of hematopoiesis-related cytokines, such as granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), interleukin 2, and interferons-γ, and enhanced the expression of hematopoiesis-related proteins in both primary bone marrow cells and mice with hematopoietic dysfunction. These results indicate that CTP has hematopoietic function-improvement effect and this effect may be related to the modulation of colony-stimulating factors (CSFs) and related signaling pathways.

Granulocyte-Macrophage Colony Stimulating Factor As an Indirect Mediator of Nociceptor Activation and Pain

The interaction between the immune system and the nervous system has been at the center of multiple research studies in recent years. Whereas the role played by cytokines as neuronal mediators is no longer contested, the mechanisms by which cytokines modulate pain processing remain to be elucidated. In this study, we have analyzed the involvement of granulocyte-macrophage colony stimulating factor (GM-CSF) in nociceptor activation in male and female mice. Previous studies have suggested GM-CSF might directly activate neurons. However, here we established the absence of a functional GM-CSF receptor in murine nociceptors, and suggest an indirect mechanism of action, via immune cells. We report that GM-CSF applied directly to magnetically purified nociceptors does not induce any transcriptional changes in nociceptive genes. In contrast, conditioned medium from GM-CSF-treated murine macrophages was able to drive nociceptor transcription. We also found that conditioned medium from nociceptors treated with the well established pain mediator, nerve growth factor, could also modify macrophage gene transcription, providing further evidence for a bidirectional crosstalk.SIGNIFICANCE STATEMENT The interaction of the immune system and the nervous system is known to play an important role in the development and maintenance of chronic pain disorders. Elucidating the mechanisms of these interactions is an important step toward understanding, and therefore treating, chronic pain disorders. This study provides evidence for a two-way crosstalk between macrophages and nociceptors in the peripheral nervous system, which may contribute to the sensitization of nociceptors by cytokines in pain development.

Effects of cannabis oil extract on immune response gene expression in human small airway epithelial cells (HSAEpC): implications for chronic obstructive pulmonary disease (COPD)

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is commonly associated with both a pro-inflammatory and a T-helper 1 (Th1) immune response. It was hypothesized that cannabis oil extract can alleviate COPD symptoms by eliciting an anti-inflammatory Th2 immune response. Accordingly, the effects of cannabis oil extract on the expression of 84 Th2 and related immune response genes in human small airways epithelial cells (HSAEpC) were investigated.

METHODS

HSAEpC from a single donor were treated with three dilutions of a standardized cannabis oil extract (1:400, 1:800 and 1:1600) along with a solvent control (0.25% [2.5 ul/ml] ethanol) for 24 h. There were four replicates per treatment dilution, and six for the control. RNA isolated from cells were employed in pathway-focused quantitative polymerase chain reaction (qPCR) microarray assays.

RESULTS

The extract induced significant (P < 0.05) changes in expression of 37 tested genes. Six genes (CSF2, IL1RL1, IL4, IL13RA2, IL17A and PPARG) were up-regulated at all three dilutions. Another two (CCL22 and TSLP) were up-regulated while six (CLCA1, CMA1, EPX, LTB4R, MAF and PMCH) were down-regulated at the 1:400 and 1:800 dilutions. The relationship of differentially-expressed genes of interest to biologic pathways was explored using the Database for Annotation, Visualization and Integrated Discovery (DAVID).

CONCLUSIONS

This exploratory investigation indicates that cannabis oil extract may affect expression of specific airway epithelial cell genes that could modulate pro-inflammatory or Th1 processes in COPD. These results provide a basis for further investigations and have prompted in vivo studies of the effects of cannabis oil extract on pulmonary function.

TRIAL REGISTRATION

NONE (all in vitro experiments).

Transcriptomic and Epigenomic Profiling of Histone Deacetylase Inhibitor Treatment Reveals Distinct Gene Regulation Profiles Leading to Impaired Neutrophil Development

Supplemental Digital Content is available in the text

The clinical use of histone deacetylase inhibitors (HDACi) for the treatment of bone marrow failure and hematopoietic malignancies has increased dramatically over the last decades. Nonetheless, their effects on normal myelopoiesis remain poorly evaluated. Here, we treated cord blood derived CD34+ progenitor cells with two chemically distinct HDACi inhibitors MS-275 or SAHA and analyzed their effects on the transcriptome (RNA-seq), epigenome (H3K27ac ChIP-seq) and functional and morphological characteristics during neutrophil development. MS-275 (entinostat) selectively inhibits class I HDACs, with a preference for HDAC1, while SAHA (vorinostat) is a non-selective class I/II HDACi. Treatment with individual HDACi resulted in both overlapping and distinct effects on both transcriptome and epigenome, whereas functional effects were relatively similar. Both HDACi resulted in reduced expansion and increased apoptosis in neutrophil progenitor cells. Morphologically, HDACi disrupted normal neutrophil differentiation what was illustrated by decreased percentages of mature neutrophils. In addition, while SAHA treatment clearly showed a block at the promyelocytic stage, MS-275 treatment was characterized by dysplastic features and skewing towards the monocytic lineage. These effects could be mimicked using shRNA-mediated knockdown of HDAC1. Taken together, our data provide novel insights into the effects of HDAC inhibition on normal hematopoietic cells during neutrophil differentiation. These findings should be taken into account when considering the clinical use of MS-275 and SAHA, and can be potentially utilized to tailor more specific, hematopoietic-directed HDACi in the future.

Regulation of hematopoiesis by the chemokine system

Although chemokines are best known for their role in directing cell migration, accumulating evidence indicate their involvement in many other processes. This review focus on the role of chemokines in hematopoiesis with an emphasis on myelopoiesis. Indeed, many chemokine family members are an important component of the cytokine network present in the bone marrow that controls proliferation, retention, and mobilization of hematopoietic progenitors.

Biomaterial-based platforms for in situ dendritic cell programming and their use in antitumor immunotherapy

Dendritic cells (DCs) are central players in the immune system, with an exquisite capacity to initiate and modulate immune responses. These functional characteristics have led to intense research on the development of DC-based immunotherapies, particularly for oncologic diseases. During recent decades, DC-based vaccines have generated very promising results in animal studies, and more than 300 clinical assays have demonstrated the safety profile of this approach. However, clinical data are inconsistent, and clear evidence of meaningful efficacy is still lacking. One of the reasons for this lack of evidence is the limited functional abilities of the used ex vivo-differentiated DCs. Therefore, alternative approaches for targeting and modulating endogenous DC subpopulations have emerged as an attractive concept. Here, we sought to revise the evolution of several strategies for the in situ mobilization and modulation of DCs. The first approaches using chemokine-secreting irradiated tumor cells are addressed, and special attention is given to the cutting-edge injectable bioengineered platforms, programmed to release chemoattractants, tumor antigens and DC maturating agents. Finally, we discuss how our increasing knowledge of DC biology, the use of neoantigens and their combination with immune checkpoint inhibitors can leverage the refinement of these polymeric vaccines to boost their antitumor efficacy.

Microglia-neuron interactions in the models of neuropathic pain

Chronic pain is a debilitating condition that often emerges as a clinical symptom of inflammatory diseases. It has therefore been widely accepted that the immune system critically contributes to the pathology of chronic pain. Microglia, a type of immune cell in the central nervous system, has attracted researchers' attention because in rodent models of neuropathic pain that develop strong mechanical and thermal hypersensitivity, histologically activated microglia are seen in the dorsal horn of spinal cord. Several kinds of cytokines are generated by damaged peripheral neurons and contribute to microglial activation at the distal site of the injury where damaged neurons send their projections. Microglia are known as key players in the surveillance of the local environment in the central nervous system and have a significant role of circuit remodeling by physical contact to synapses. Key molecules for the pathology of neuropathic pain exist in the activated microglia, but the factors driving pain-inducible microglial activation remain unclear. Therefore, to find the key molecules inducing activation of spinal microglia and to figure out the precise mechanism of how microglia modulate neuronal circuits in the spinal cord to form chronic pain state is a critical step for developing effective treatment of neuropathic pain.

Studying tissue macrophages in vitro: are iPSC-derived cells the answer?

Macrophages are immune cells with important roles in tissue homeostasis, inflammation and pathologies. Hence, macrophage populations represent promising targets for modern medicine. Exploiting the potential of macrophage-targeted therapies will require a thorough understanding of the mechanisms controlling their development, specialization and maintenance throughout their lifespan. Macrophages have been studied in vitro for many years, but recent advances in the field of macrophage biology have called into question the validity of traditional approaches. New models, such as recent innovations in generating macrophages from induced pluripotent stem cells (iPSCs), must take into account the impact of heterogeneity in the origin and tissue-specific functions of macrophages. Here, we discuss these protocols and argue for a better understanding of the type of macrophages made in vitro; we also encourage recognition of the importance of tissue identity of macrophages, which cannot be recapitulated by cytokine-dependent protocols. We suggest that a two-step model - in which iPSC-derived macrophages are first generated based on their ontogeny and then conditioned by their tissue-specific environment - offers immense potential for generating biologically relevant macrophages for future studies.

Microbes, metabolites, and the gut-lung axis

The microbiota plays an essential role in the education, development, and function of the immune system, both locally and systemically. Emerging experimental and epidemiological evidence highlights a crucial cross-talk between the intestinal microbiota and the lungs, termed the 'gut-lung axis'. Changes in the constituents of the gut microbiome, through either diet, disease or medical interventions (such as antibiotics) is linked with altered immune responses and homeostasis in the airways. The importance of the gut-lung axis has become more evident following the identification of several gut microbe-derived components and metabolites, such as short-chain fatty acids (SCFAs), as key mediators for setting the tone of the immune system. Recent studies have supported a role for SCFAs in influencing hematopoietic precursors in the bone marrow-a major site of innate and adaptive immune cell development. Here, we review the current understanding of host-microbe cross-talk along the gut-lung axis. We highlight the importance of SCFAs in shaping and promoting bone marrow hematopoiesis to resolve airway inflammation and to support a healthy homeostasis.

New paradigms on hematopoietic stem cell differentiation

Ever since hematopoietic stem cells (HSCs) were first identified half a century ago, their differentiation roadmap has been extensively studied. The classical model of hematopoiesis has long held as a dogma that HSCs reside at the top of a hierarchy in which HSCs possess self-renewal capacity and can progressively give rise to all blood lineage cells. However, over the past several years, with advances in single cell technologies, this developmental scheme has been challenged. In this review, we discuss the evidence supporting heterogeneity within HSC and progenitor populations as well as the hierarchical models revised by novel approaches mainly in mouse system. These evolving views provide further understanding of hematopoiesis and highlight the complexity of hematopoietic differentiation.

Topological control of cytokine receptor signaling induces differential effects in hematopoiesis

Although tunable signaling by G protein-coupled receptors can be exploited through medicinal chemistry, a comparable pharmacological approach has been lacking for the modulation of signaling through dimeric receptors, such as those for cytokines. We present a strategy to modulate cytokine receptor signaling output by use of a series of designed C2-symmetric cytokine mimetics, based on the designed ankyrin repeat protein (DARPin) scaffold, that can systematically control erythropoietin receptor (EpoR) dimerization orientation and distance between monomers. We sampled a range of EpoR geometries by varying intermonomer angle and distance, corroborated by several ligand-EpoR complex crystal structures. Across the range, we observed full, partial, and biased agonism as well as stage-selective effects on hematopoiesis. This surrogate ligand strategy opens access to pharmacological modulation of therapeutically important cytokine and growth factor receptor systems.