Function of the chemokine receptor CXCR4 in haematopoiesis and in cerebellar development

Low Expression Levels of CXCL12, CXCR4, and CXCR 7 in Peripheral Blood and Decidual Tissues are Associated with Miscarriage in Women

Miscarriage can cause significant physical and psychological harm to women. The stromal cell-derived factor 1 (SDF-1, also known as CXCL12)/C-X-C motif chemokine receptor 4 (CXCR4) and C-X-C motif chemokine receptor 7 (CXCR7) axis can promote the proliferation and invasion of trophoblast cells in early pregnancy, and maintain immune tolerance at the maternal-fetal interface to aid with pregnancy success. From our findings, the serum CXCL12 level of women who have miscarried (n = 25) was significantly lower than that of healthy early pregnancy women (n = 20) by ELISA (P < .001). Additionally, CXCL12 levels in normal non-pregnant women (n = 20) were significantly lower than those in early pregnancy women (P < .001) and women who have miscarried (P < .001). Quantitative real-time PCR detected no significant difference in the mRNA transcription levels of CXCR4 and CXCR7 in the decidua tissues of women with early pregnancy (n = 20) and miscarriage (n = 20) (P = .724, P = .281, respectively). However, Western blot and immunohistochemistry of CXCR4 and CXCR7 in decidual tissue of women who have miscarried (n = 20) were significantly lower than those in early pregnancy women (n = 20) (P < .05 for both). Therefore, we believe that the increased serum CXCL12 levels in pregnant offspring may benefit normal pregnancy maintenance. The low level of CXCL12 in peripheral blood and the low expression of CXCR4 and CXCR7 proteins in decidua may be associated with the occurrence of early spontaneous abortion, and the clinical application value of serum CXCL12 in predicting adverse pregnancy outcomes is worth further exploring.

CXCR4+ Treg cells control serum IgM levels and natural IgM autoantibody production by B-1 cells in the bone marrow

Regulatory T (Treg) cells represent a specialized lineage of suppressive CD4⁺ T cells whose functionality is critically dependent on their ability to migrate to and dwell in the proximity of cells they control. Here we show that continuous expression of the chemokine receptor CXCR4 in Treg cells is required for their ability to accumulate in the bone marrow (BM). Induced CXCR4 ablation in Treg cells led to their rapid depletion and consequent increase in mature B cells, foremost the B-1 subset, observed exclusively in the BM without detectable changes in plasma cells or hematopoietic stem cells or any signs of systemic or local immune activation elsewhere. Dysregulation of BM B-1 B cells was associated with a highly specific increase in IgM autoantibodies and total serum IgM levels. Thus, Treg cells control autoreactive B-1 B cells in a CXCR4-dependent manner. These findings have significant implications for understanding the regulation of B cell autoreactivity and malignancies.

Systemic Delivery of an Adjuvant CXCR4-CXCL12 Signaling Inhibitor Encapsulated in Synthetic Protein Nanoparticles for Glioma Immunotherapy

Glioblastoma (GBM) is an aggressive primary brain cancer, with a 5 year survival of ∼5%. Challenges that hamper GBM therapeutic efficacy include (i) tumor heterogeneity, (ii) treatment resistance, (iii) immunosuppressive tumor microenvironment (TME), and (iv) the blood-brain barrier (BBB). The C-X-C motif chemokine ligand-12/C-X-C motif chemokine receptor-4 (CXCL12/CXCR4) signaling pathway is activated in GBM and is associated with tumor progression. Although the CXCR4 antagonist (AMD3100) has been proposed as an attractive anti-GBM therapeutic target, it has poor pharmacokinetic properties, and unfavorable bioavailability has hampered its clinical implementation. Thus, we developed synthetic protein nanoparticles (SPNPs) coated with the transcytotic peptide iRGD (AMD3100-SPNPs) to target the CXCL2/CXCR4 pathway in GBM via systemic delivery. We showed that AMD3100-SPNPs block CXCL12/CXCR4 signaling in three mouse and human GBM cell cultures in vitro and in a GBM mouse model in vivo. This results in (i) inhibition of GBM proliferation, (ii) reduced infiltration of CXCR4⁺ monocytic myeloid-derived suppressor cells (M-MDSCs) into the TME, (iii) restoration of BBB integrity, and (iv) induction of immunogenic cell death (ICD), sensitizing the tumor to radiotherapy and leading to anti-GBM immunity. Additionally, we showed that combining AMD3100-SPNPs with radiation led to long-term survival, with ∼60% of GBM tumor-bearing mice remaining tumor free after rechallenging with a second GBM in the contralateral hemisphere. This was due to a sustained anti-GBM immunological memory response that prevented tumor recurrence without additional treatment. In view of the potent ICD induction and reprogrammed tumor microenvironment, this SPNP-mediated strategy has a significant clinical translation applicability.

Chemokine C-X-C receptor 4 mediates recruitment of bone marrow-derived nonhematopoietic and immune cells to the pregnant uterus†

Bone marrow-derived progenitor cells (BMDPCs) are mobilized to the circulation in pregnancy and get recruited to the pregnant decidua where they contribute functionally to decidualization and successful implantation. However, the molecular mechanisms underlying BMDPCs recruitment to the decidua are unknown. CXCL12 ligand and its CXCR4 receptor play crucial roles in the mobilization and homing of stem/progenitor cells to various tissues. To investigate the role of CXCL12-CXCR4 axis in BMDPCs recruitment to decidua, we created transgenic GFP mice harboring CXCR4 gene susceptible to tamoxifen-inducible Cre-mediated ablation. These mice served as BM donors into wild-type C57BL/6 J female recipients using a 5-fluorouracil-based nongonadotoxic submyeloablation to achieve BM-specific CXCR4 knockout (CXCR4KO). Successful CXCR4 ablation was confirmed by RT-PCR and in vitro cell migration assays. Flow cytometry and immunohistochemistry showed a significant increase in GFP+ BM-derived cells (BMDCs) in the implantation site as compared to the nonpregnant uterus of control (2.7-fold) and CXCR4KO (1.8-fold) mice. This increase was uterus-specific and was not observed in other organs. This pregnancy-induced increase occurred in both hematopoietic (CD45+) and nonhematopoietic (CD45-) uterine BMDCs in control mice. In contrast, in CXCR4KO mice there was no increase in nonhematopoietic BMDCs in the pregnant uterus. Moreover, decidual recruitment of myeloid cells but not NK cells was diminished by BM CXCR4 deletion. Immunofluorescence showed the presence of nonhematopoietic GFP+ cells that were negative for CD45 (panleukocyte) and DBA (NK) markers in control but not CXCR4KO decidua. In conclusion, we report that CXCR4 expression in nonhematopoietic BMDPCs is essential for their recruitment to the pregnant decidua.

Niche Regulation of Hematopoiesis: The Environment Is "Micro," but the Influence Is Large

Immune cell production is governed by a process known as hematopoiesis, where hematopoietic stem cells (HSCs) differentiate through progenitor cells and ultimately to the mature blood and immune cells found in circulation. While HSCs are capable of cell-autonomous regulation, they also rely on extrinsic factors to balance their state of quiescence and activation. These cues can, in part, be derived from the niche in which HSCs are found. Under steady-state conditions, HSCs are found in the bone marrow. This niche is designed to support HSCs but also to respond to external factors, which allows hematopoiesis to be a finely tuned and coordinated process. However, the niche, and its regulation, can become dysregulated to potentiate inflammation during disease. This review will highlight the architecture of the bone marrow and key regulators of hematopoiesis within this niche. Emphasis will be placed on how these mechanisms go awry to exacerbate hematopoietic contributions that drive cardiovascular disease.

Integrins, anchors and signal transducers of hematopoietic stem cells during development and in adulthood

Hematopoietic stem cells (HSCs), the apex of the hierarchically organized blood cell production system, are generated in the yolk sac, aorta-gonad-mesonephros region and placenta of the developing embryo. To maintain life-long hematopoiesis, HSCs emigrate from their site of origin and seed in distinct microenvironments, called niches, of fetal liver and bone marrow where they receive supportive signals for self-renewal, expansion and production of hematopoietic progenitor cells (HPCs), which in turn orchestrate the production of the hematopoietic effector cells. The interactions of hematopoietic stem and progenitor cells (HSPCs) with niche components are to a large part mediated by the integrin superfamily of adhesion molecules. Here, we summarize the current knowledge regarding the functional properties of integrins and their activators, Talin-1 and Kindlin-3, for HSPC generation, function and fate decisions during development and in adulthood. In addition, we discuss integrin-mediated mechanosensing for HSC-niche interactions, ex vivo protocols aimed at expanding HSCs for therapeutic use, and recent approaches targeting the integrin-mediated adhesion in leukemia-inducing HSCs in their protecting, malignant niches.

Single-cell transcriptomics identifies premature aging features of TERC-deficient mouse brain and bone marrow

Aging is a progressive loss of physiological function and increased susceptibility to major pathologies. Degenerative diseases in both brain and bone including Alzheimer disease (AD) and osteoporosis are common in aging groups. TERC is RNA component of telomerase, and its deficiency accelerates aging-related phenotypes including impaired life span, organ failure, bone loss, and brain dysfunction. In this study, we investigated the traits of bone marrow-brain cross-tissue communications in young mice, natural aging mice, and premature aging (TERC deficient, TERC-KO) mice by single-cell transcriptome sequencing. Differentially expressed gene analysis of brain as well as bone marrow between premature aging mouse and young mouse demonstrated aging-related inflammatory response and suppression of neuron development. Further analysis of senescence-associated secretory phenotype (SASP) landscape indicated that TERC-KO perturbation was enriched in oligodendrocyte progenitor cells (OPCs) and hematopoietic stem and progenitor cells (HSPC). Series of inflammatory associated myeloid cells was activated in premature aging mice brain and bone marrow. Cross-tissue comparison of TERC-KO mice brain and bone marrow illustrated obvious ligand-receptor communications between brain glia cells, macrophages, and bone marrow myeloid cells in premature aging-induced inflammation. Enrichment of co-regulation modules between brain and bone marrow identified premature aging response genes such as Dusp1 and Ifitm3. Our study provides a rich resource for understanding premature aging-associated perturbation in brain and bone marrow and supporting myeloid cells and endothelial cells as promising therapy targeting for age-related brain-bone diseases.

Neuronal Polarity Pathways as Central Integrators of Cell-Extrinsic Information During Interactions of Neural Progenitors With Germinal Niches

Germinal niche interactions and their effect on developing neurons have become the subject of intense investigation. Dissecting the complex interplay of cell-extrinsic and cell-intrinsic factors at the heart of these interactions reveals the critical basic mechanisms of neural development and how it goes awry in pediatric neurologic disorders. A full accounting of how developing neurons navigate their niches to mature and integrate into a developing neural circuit requires a combination of genetic characterization of and physical access to neurons and their supporting cell types plus transformative imaging to determine the cell biological and gene-regulatory responses to niche cues. The mouse cerebellar cortex is a prototypical experimental system meeting all of these criteria. The lessons learned therein have been scaled to other model systems and brain regions to stimulate discoveries of how developing neurons make many developmental decisions. This review focuses on how mouse cerebellar granule neuron progenitors interact with signals in their germinal niche and how that affects the neuronal differentiation and cell polarization programs that underpin lamination of the developing cerebellum. We show how modeling of these mechanisms in other systems has added to the growing evidence of how defective neuronal polarity contributes to developmental disease.

High-Throughput Sequencing Reveals CXCR4 and IGF1 Behave Different Roles in Weightlessness Osteoporosis

Objective

This study is aimed at screening the differential expression profiles of mRNA under weightlessness osteoporosis through high-throughput sequencing technology, as well as investigating the pathogenesis of weightlessness osteoporosis at the molecular level especially in bone marrow mesenchymal stem cells (BMSCs).

Methods

The mouse bone marrow mesenchymal stem cell line was divided into ground group and simulated microgravity (SMG) group. BMP-2 was used to induce osteogenic differentiation, and SMG group was placed into 2D-gyroscope to simulate weightless condition. Transcriptome sequencing was performed by Illumina technology, DEGs between ground and SMG group was conducted using the DEseq2 algorithm. Molecular functions and signaling pathways enriched by DEGs were then comprehensively analyzed via multiple bioinformatic approaches including but not limited to GO, KEGG, GSEA, and PPI analysis.

Results

A total of 263 DEGs were identified by comparing these 2 groups, including 186 upregulated genes and 77 downregulated genes. GO analysis showed that DEGs were enriched in osteoblasts, osteoclasts cell proliferation, differentiation, and apoptosis; KEGG analysis revealed that DEGs were significantly enriched in the TNF signaling pathway and FoxO signaling pathway; the enrichment results from Reactome database displayed that DEGs were mainly involved in the transcription of Hoxb3 gene, RUNX1 recruitment KMT2A gene, and activation of Hoxa2 chromatin signaling pathway. The four genes, IL6, CXCR4, IGF1, and PLOD2, were identified as hub genes for subsequent analysis.

Conclusions

This study elucidated the significance of 10 hub genes in the development of weightlessness osteoporosis. In addition, the results of this study provide a theoretical basis and novel ideas for the subsequent research of the pathogenesis and clinical treatment of weightlessness osteoporosis.

Colorectal Cancer: The Contribution of CXCL12 and Its Receptors CXCR4 and CXCR7

Simple Summary

Many signaling pathways are involved in cancer progression, and among these pathways, the CXCL12 axis and its two receptors CXCR4 and CXCR7 are well described for many cancers. This review presents the current knowledge on the role played by each of the actors of this axis in colorectal cancer and on its consideration in the development of new therapeutic strategies.

Abstract

Colorectal cancer is one of the most common cancers, and diagnosis at late metastatic stages is the main cause of death related to this cancer. This progression to metastasis is complex and involves different molecules such as the chemokine CXCL12 and its two receptors CXCR4 and CXCR7. The high expression of receptors in CRC is often associated with a poor prognosis and aggressiveness of the tumor. The interaction of CXCL12 and its receptors activates signaling pathways that induce chemotaxis, proliferation, migration, and cell invasion. To this end, receptor inhibitors were developed, and their use in preclinical and clinical studies is ongoing. This review provides an overview of studies involving CXCR4 and CXCR7 in CRC with an update on their targeting in anti-cancer therapies.

SIRT1 regulates cardiomyocyte alignment during maturation

Cardiomyocyte elongation and alignment, a critical step in cardiomyocyte maturation starting from the perinatal stage, is crucial for formation of the highly organized intra- and inter-cellular structures for spatially and temporally ordered contraction in adult cardiomyocytes. However, the mechanism(s) underlying the control of cardiomyocyte alignment remains elusive. Here, we report that SIRT1, the most conserved NAD+-dependent protein deacetylase highly expressed in perinatal heart, plays an important role in regulating cardiomyocyte remodeling during development. We observed that SIRT1 deficiency impairs the alignment of cardiomyocytes/myofibrils and disrupts normal beating patterns at late developmental stages in an in vitro differentiation system from human embryonic stem cells. Consistently, deletion of SIRT1 at a late developmental stage in mouse embryos induced the irregular distribution of cardiomyocytes and misalignment of myofibrils, and reduced the heart size. Mechanistically, the expression of several genes involved in chemotaxis, including those in the CXCL12/CXCR4 and CCL2/CCR2/CCR4 pathways, was dramatically blunted during maturation of SIRT1-deficient cardiomyocytes. Pharmacological inhibition of CCL2 signaling suppressed cardiomyocyte alignment. Our study identifies a regulatory factor that modulates cardiomyocyte alignment at the inter-cellular level during maturation.

Intravenous injection of SDF-1α-overexpressing bone marrow mesenchymal stem cells has a potential protective effect on myocardial ischemia in mice

Background Neutrophils are involved in the injury of myocytes during myocardial ischemia (MI). Stem cells migrate to the site of myocardial injury under homing signals and play a protective role, such as inhibiting inflammation. Chemokine SDF-1α and its related receptor CXCR4 are upregulated after myocardial infarction, which may play an important role in stem cell homing. Objectives This study aimed to explore the potential therapeutic effect of SDF-1α-modified bone marrow mesenchymal stem cells on myocardial ischemia/reperfusion (I/R) injury. Methods We explored the role of SDF-1α modified bone marrow mesenchymal stem cells in vivo and in vitro. SDF-1α and CXCR4 expression was detected under hypoxia/reoxygenation (H/R) condition. Cell migration was detected by the transwell method. The levels of SDF-1α and IL-1β, IL-6, IL-10, and TNF-α were detected in different groups. Results In vivo, SDF-1α was mainly upregulated and secreted by cardiomyocytes, and cardiomyocytes recruited stem cells through the SDF-1/CXCR4 pathway to reduce the damage of polymorphic mononuclear neutrophils to cardiomyocytes under H/R. Upregulation of SDF-1α increased the migration ability of BMSC Stem Cells to H/R-induced cardiomyocytes. In vitro, intravenous injection of SDF-1α gene-modified BMSC Stem Cells reduced inflammatory infiltration in the injured area as well as the level of systemic inflammatory factors. Conclusions SDF-1α-overexpressing BMSC Stem Cells protected the heart function of mice and significantly reduced I/R-induced myocardial injury, which has a potential protective effect on MI.

Synthesis and Evaluation of Novel Tetrahydronaphthyridine CXCR4 Antagonists with Improved Drug-like Profiles

Our first-generation CXCR4 antagonist TIQ15 was rationally modified to improve drug-like properties. Introducing a nitrogen atom into the aromatic portion of the tetrahydroisoquinoline ring led to several heterocyclic variants including the 5,6,7,8-tetrahydro-1,6-naphthyridine series, greatly reducing the inhibition of the CYP 2D6 enzyme. Compound 12a demonstrated the best overall properties after profiling a series of isomeric tetrahydronaphthyridine analogues in a battery of biochemical assays including CXCR4 antagonism, CYP 2D6 inhibition, metabolic stability, and permeability. The butyl amine side chain of 12a was substituted with various lipophilic groups to improve the permeability. These efforts culminated in the discovery of compound 30 as a potent CXCR4 antagonist (IC50 = 24 nM) with diminished CYP 2D6 activity, improved PAMPA permeability (309 nm/s), potent inhibition of human immunodeficiency virus entry (IC50 = 7 nM), a cleaner off-target in vitro safety profile, lower human ether a-go-go-related gene channel activity, and higher oral bioavailability in mice (% FPO = 27) compared to AMD11070 and TIQ15.

CRISPR-Cas9-mediated gene disruption of HIV-1 co-receptors confers broad resistance to infection in human T cells and humanized mice

In this preclinical study, we evaluated the efficacy and feasibility of creating broad human immunodeficiency virus (HIV) resistance by simultaneously disrupting the human CCR5 and CXCR4 genes, which encode cellular co-receptors required for HIV-1 infection. Using a clinically scalable system for transient ex vivo delivery of Cas9/guide RNA (gRNA) ribonucleoprotein (RNP) complexes, we demonstrated that CRISPR-mediated disruption of CCR5 and CXCR4 in T lymphocyte cells significantly reduced surface expression of the co-receptors, thereby establishing resistance to HIV-1 infection by CCR5 (R5)-tropic, CXCR4 (X4)-tropic, and dual (R5/X4)-tropic strains. Similarly, disruption of CCR5 alleles in human CD34⁺ hematopoietic stem and progenitor cells (HSPCs) successfully led to the differentiation of HIV-resistant macrophages. In a humanized mouse model under HIV-1 challenge, CXCR4-disrupted CD4⁺ T cells were enriched in the peripheral blood and spleen, indicating survival advantage because of resistance to viral infection. However, in human CD4⁺ T cells with both CCR5 and CXCR4 disruption, we observed poor engraftment in bone marrow, although significant changes were not observed in the lung, spleen, or peripheral blood. This study establishes a clinically scalable strategy for the dual knockout of HIV-1 co-receptors as a therapeutic strategy, while also raising caution of disrupting CXCR4, which may abate engraftment of CD4⁺ T cells in bone marrow.

Plasma proteome changes linked to late phase response after inhaled allergen challenge in asthmatics

Background

A subset of individuals with allergic asthma develops a late phase response (LPR) to inhaled allergens, which is characterized by a prolonged airway obstruction, airway inflammation and airway hyperresponsiveness. The aim of this study was to identify changes in the plasma proteome and circulating hematopoietic progenitor cells associated with the LPR following inhaled allergen challenge.

Methods

Serial plasma samples from asthmatics undergoing inhaled allergen challenge were analyzed by mass spectrometry and immunosorbent assays. Peripheral blood mononuclear cells were analyzed by flow cytometry. Mass spectrometry data were analyzed using a linear regression to model the relationship between airway obstruction during the LPR and plasma proteome changes. Data from immunosorbent assays were analyzed using linear mixed models.

Results

Out of 396 proteins quantified in plasma, 150 showed a statistically significant change 23 h post allergen challenge. Among the most upregulated proteins were three protease inhibitors: alpha-1-antitrypsin, alpha-1-antichymotrypsin and plasma serine protease inhibitor. Altered levels of 13 proteins were associated with the LPR, including increased factor XIII A and decreased von Willebrand factor. No relationship was found between the LPR and changes in the proportions of classical, intermediate, and non-classical monocytes.

Conclusions

Allergic reactions to inhaled allergens in asthmatic subjects were associated with changes in a large proportion of the measured plasma proteome, whereof protease inhibitors showed the largest changes, likely to influence the inflammatory response. Many of the proteins altered in relation to the LPR are associated with coagulation, highlighting potential mechanistic targets for future treatments of type-2 asthma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-01968-0.

Emerging Roles of the Atypical Chemokine Receptor 3 (ACKR3) in Cardiovascular Diseases

Chemokines, and their receptors play a crucial role in the pathophysiology of cardiovascular diseases (CVD). Chemokines classically mediate their effects by binding to G-protein-coupled receptors. The discovery that chemokines can also bind to atypical chemokine receptors (ACKRs) and initiate alternative signaling pathways has changed the paradigm regarding chemokine-related functions. Among these ACKRs, several studies have highlighted the exclusive role of ACKR3, previously known as C-X-C chemokine receptor type 7 (CXCR7), in CVD. Indeed, ACKR3 exert atheroprotective, cardioprotective and anti-thrombotic effects through a wide range of cells including endothelial cells, platelets, inflammatory cells, fibroblasts, vascular smooth muscle cells and cardiomyocytes. ACKR3 functions as a scavenger receptor notably for the pleiotropic chemokine CXCL12, but also as a activator of different pathways such as β-arrestin-mediated signaling or modulator of CXCR4 signaling through the formation of ACKR3-CXCR4 heterodimers. Hence, a better understanding of the precise roles of ACKR3 may pave the way towards the development of novel and improved therapeutic strategies for CVD. Here, we summarize the structural determinant characteristic of ACKR3, the molecules targeting this receptor and signaling pathways modulated by ACKR3. Finally, we present and discuss recent findings regarding the role of ACKR3 in CVD.

Hyaluronic acid-based hydrogels loaded with chemoattractant and anticancer drug - new formulation for attracting and tackling glioma cells

Over the last few years, significant interest has emerged in the development of localised therapeutic strategies for the treatment of glioblastoma (GBM). The concept of attracting and trapping residual tumour cells within a confined area to facilitate their eradication has developed progressively. Herein, we propose a new design of hyaluronic acid-based hydrogel which can be utilized as a matrix containing a soluble chemoattractant to attract residual glioma cells and chemotherapeutic agents to eradicate them in a less invasive and more efficient way compared to the currently available methods. Hydrogels were prepared at different crosslinking densities, e.g. low and high density, by crosslinking hyaluronic acid with various concentrations of adipic acid dihydrazide and U87MG GBM cell morphology, survival and CD44 expression were evaluated. As a proof-of-concept, hydrogels were loaded with a small peptide chemokine, human urotensin II (hUII), and the migration and survival of U87MG GBM cells were studied. Chemoattractant-containing hydrogels were also loaded with chemotherapeutic drugs to promote cell death in culture. The results showed that U87MG cells were able to invade the hydrogel network and to migrate in response to the chemoattractant hUII. In addition, in static condition, hydrogels loaded with doxorubicin demonstrated significant cytotoxicity leading to less than 80% U87MG cell viability after 48 hours when compared to the control sample. In addition, in in vitro invasive assays, it was originally shown that the chemoattractant effect of hUII can be effective before the cytotoxic action of doxorubicin on the U87MG cells trapped in the hydrogel. Our results provide new insights into a promising approach which can be readily translated in vivo for the treatment of one of the most devastating brain tumours.

ZnO-based micromotors fueled by CO2: the first example of self-reorientation-induced biomimetic chemotaxis

Synthetic chemotactic micro/nanomotors are envisioned to actively ‘seek out’ targets by following specific chemicals, but they are mainly powered by bioincompatible fuels and only show pseudochemotaxis (or advanced chemokinesis) due to their weak self-reorientation capabilities. Here we demonstrate that synthetic ZnO-based Janus micromotors can be powered by the alternative biocompatible fuel of CO₂, and further provide the first example of self-reorientation-induced biomimetic chemotaxis using them. The ZnO-based micromotors are highly sensitive to dissolved CO₂ in water, which enables the corrosion of ZnO to continuously occur by providing H⁺ through hydration. Thus, they can autonomously move even in water exposed to air based on self-diffusiophoresis. Furthermore, they can sense the local CO₂ gradient and perform positive chemotaxis by self-reorientations under the phoretic torque. Our discovery opens a gate to developing intelligent micro/nanomotors powered by, and sensitive to, biocompatible atmospheric or endogenous gaseous chemicals for biomedical and environmental applications.

Cellular Niches for Hematopoietic Stem Cells and Lympho-Hematopoiesis in Bone Marrow During Homeostasis and Blood Cancers

Most types of blood cells, including immune cells are generated from hematopoietic stem cells (HSCs) within bone marrow in the adult. Most HSCs are in contact with and require the special microenvironment known as a niche for their maintenance. It has been thought that HSC niches comprise various types of support cells that provide critical signals, including cytokines and extracellular matrix for HSC regulation. However, among these cells, several lines of evidence have demonstrated that the population of bone marrow-specific mesenchymal stem cells, termed CXC chemokine ligand 12 (CXCL12)-abundant reticular (CAR) cells, which overlap strongly with leptin receptor-expressing (LepR⁺) cells, is the major cellular component of HSC niches. CAR/LepR⁺ cells give rise to most adipocytes and osteoblasts in adult bone marrow and express much higher levels of HSC niche factors, including cytokines CXCL12 and stem cell factor (SCF), which are essential for HSC maintenance, and transcription factors Foxc1 and Ebf3, which are essential for the formation and maintenance of HSC niches than other types of cells. CAR/LepR⁺ cells are present in human bone marrow, undergo fibrotic expansion, and have reduced expression of HSC niche factors in hematopoietic malignancies.

Stem Cell Markers CXCR-4 and CD133 Predict Aggressive Phenotype and Their Double Positivity Indicates Poor Prognosis of Oral Squamous Cell Carcinoma

Simple Summary

Oral cancer is one of the most frequent malignancies in the world, with a poor prognosis. The absence of accurate biomarkers for predicting oral cancer progression is the primary cause of treatment failures. Multiple studies have shown that cancer stem cells play a critical role in tumor growth and chemo resistance. We uncovered, for the first time, the importance of combinatorial expression of stem cell related molecules CXCR-4 and CD-133 as possible biomarkers to predict poor prognosis of oral squamous cell carcinoma. The findings will aid in the identification of high-risk cases in order to provide appropriate therapy.

Abstract

The activation of the SDF-1/CXCR-4 pathway is crucial for the invasion and metastasis of oral cancer cells. The CXCR-4 positive cells possess stem cell characteristics and express the cancer stem cell marker, CD133, in tumors of colon and pancreas. Despite several studies, the co-expression of CXCR-4 and CD133 and its significance is still largely unknown in oral cancer. Therefore, we aimed to investigate the impact of CXCR-4 and CD133 double positivity in the prognosis of oral cancer. The significance of PKC-δ, one of the key signaling molecules that regulates CXCR-4, was also analyzed. Immunohistochemistry and double immunofluorescence was used to investigate the co-localization of CXCR-4, PKC-δ and CD133 in the human tissues and cell lines of oral squamous cell carcinoma. The expression of CXCR-4, PKC-δ and CD133 were found to be higher in poorly differentiated and lymph node metastasis-positive cases. Interestingly, CXCR-4 positive cells showed positive staining for PKC-δ and CD133 in oral cancer tissue and cell lines. Moreover, CXCR-4+/CD133+ and CXCR-4+/PKC-δ+ double positive cases have the worst survival. We discovered, for the first time, that patients with expression of both CXCR-4 and CD133 have a lower survival rate, and CXCR-4+/CD133+, as well as CXCR-4+/PKC-δ+ double positivity, can be utilized to predict poor prognosis. CXCR-4, PKC-δ and CD133 might regulate aggressiveness and invasion of oral cancer cells.

SDF-1 expression after preoperative chemoradiotherapy is associated with prognosis in patients with advanced lower rectal cancer

Stromal cell-derived factor-1 (SDF-1) expression is associated with cancer progression, as a biomarker of prognosis. We clarified the significance of SDF-1 expression on chemoradiotherapy (CRT) resistance and prognosis in advanced lower rectal cancer patients. We evaluated 98 patients with advanced lower rectal cancer who underwent preoperative CRT. All patients received 40 Gy of radiation therapy, with concurrent chemotherapy containing fluorinated pyrimidines, followed by surgical resection. SDF-1 expression in surgical specimens was examined by immunohistochemistry. We divided the patients into SDF-1-positive- (n = 52) and SDF-1-negative groups (n = 46) and compared the clinicopathological factors and survival rates. The SDF-1-positive group was more resistant to CRT than the SDF-1-negative group (non-responder rate, 63.5% vs. 47.8%, respectively ; p = 0.12). Overall survival (OS) in the SDF-1 positive group was significantly poorer vs. the SDF-1-negative group (5-year OS, 73.4% vs. 88.0%, respectively ; p = 0.02), and disease-free survival (DFS) was worse (5-year DFS, 61.0% vs. 74.1%, respectively ; p = 0.07). Multivariate analysis confirmed that SDF-1 expression was a significant independent prognostic predictor of OS (p = 0.04). SDF-1 expression after preoperative CRT is significantly associated with a poor prognosis in advanced lower rectal cancer patients and is a promising biomarker. J. Med. Invest. 68 : 309-314, August, 2021.

Identification of microenvironmental niches for hematopoietic stem cells and lymphoid progenitors-bone marrow fibroblastic reticular cells with salient features

Most lineages of blood cells, including immune cells are generated from hematopoietic stem cells (HSCs) in bone marrow throughout adult life. Since HSCs cannot expand on their own, they require and contact the special microenvironments, termed niches for their maintenance. HSC niches comprise supportive cells that provide adjacent HSCs with critical signals, including cytokines. Although bone marrow microenvironments have been thought to be complex, recent studies have demonstrated that the bone marrow-specific population of fibroblastic reticular cells with long processes, termed CXC chemokine ligand 12 (CXCL12)-abundant reticular (CAR) cells, which overlap strongly with leptin receptor (LepR)-expressing (LepR +) cells, is the major cellular component of niches for HSCs and lymphoid progenitors. CAR cells have salient features, expressing much higher levels of critical HSC niche factors than any other cell populations and function as self-renewing mesenchymal stem cells. Human counterpart of CAR cells is present and affected in diseases, including leukemia. Foxl1 + telocytes recently identified as the niche for intestinal stem cells share some features with CAR cells, suggesting that CAR cells are prototypical fibroblastic reticular cells creating niche for long-lived cells, including tissue stem cells and memory lymphocytes. These findings provided the basis for future mechanistic studies on the crosstalk between hematopoietic cells and microenvironments in both health and disease.

Amino-Heterocycle Tetrahydroisoquinoline CXCR4 Antagonists with Improved ADME Profiles via Late-Stage Buchwald Couplings

This work surveys a variety of diamino-heterocycles as an isosteric replacement for the piperazine substructure of our previously disclosed piperarinyl-tetrahydroisoquinoline containing CXCR4 antagonists. A late-stage Buchwald coupling route was developed for rapid access to final compounds from commercial building blocks. Among 13 analogs in this study, compound 31 embodying an aza-piperazine linkage was found to have the best overall profile with potent CXCR4 inhibitory activity and favorable in vitro absorption, distribution, metabolism, and excretion (ADME) properties. An analysis of the calculated physiochemical parameters (ROF, cLogD) and the experimental ADME attributes of the analogs lead to the selection of 31 for pharmacokinetic studies in mice. Compared with the clinical compound AMD11070, compound 31 has no CYP450 3A4 or 2D6 inhibition, higher metabolic stability and PAMPA permeability, greatly improved physiochemical parameters, and superior oral bioavailability (%F = 24). A binding rationale for 31 within CXCR4 was elucidated from docking and molecular simulation studies.

Atypical opioid receptors: unconventional biology and therapeutic opportunities

Endogenous opioid peptides and prescription opioid drugs modulate pain, anxiety and stress by activating four opioid receptors, namely μ (mu, MOP), δ (delta, DOP), κ (kappa, KOP) and the nociceptin/orphanin FQ receptor (NOP). Interestingly, several other receptors are also activated by endogenous opioid peptides and influence opioid-driven signaling and biology. However, they do not meet the criteria to be recognized as classical opioid receptors, as they are phylogenetically distant from them and are insensitive to classical non-selective opioid receptor antagonists (e.g. naloxone). Nevertheless, accumulating reports suggest that these receptors may be interesting alternative targets, especially for the development of safer analgesics. Five of these opioid peptide-binding receptors belong to the family of G protein-coupled receptors (GPCRs)-two are members of the Mas-related G protein-coupled receptor X family (MrgX1, MrgX2), two of the bradykinin receptor family (B_1, B₂), and one is an atypical chemokine receptor (ACKR3). Additionally, the ion channel N-methyl-d-aspartate receptors (NMDARs) are also activated by opioid peptides. In this review, we recapitulate the implication of these alternative receptors in opioid-related disorders and discuss their unconventional biology, with members displaying signaling to scavenging properties. We provide an overview of their established and emerging roles and pharmacology in the context of pain management, as well as their clinical relevance as alternative targets to overcome the hurdles of chronic opioid use. Given the involvement of these receptors in a wide variety of functions, including inflammation, chemotaxis, anaphylaxis or synaptic transmission and plasticity, we also discuss the challenges associated with the modulation of both their canonical and opioid-driven signaling.

Expansion of cord blood stem cells in fibronectin-coated microfluidic bioreactor

Background

Hematopoietic stem/progenitor cell transplantation is the main treatment option for hematological malignancies and disorders. One strategy to solve the problem of low stem cell doses used in transplantation is pre-transplant expansion. We hypothesized that using fibronectin-coated microfluidic channels would expand HSPCs and keep self-renewal potential in a three-dimensional environment, compared to the conventional method. We also compared stem cell homing factors expression in microfluidic to conventional cultures.

Materials and methods

A microfluidic device was created and characterized by scanning electron microscopy. The CD133+ cells were collected from cord blood and purified. They were subsequently cultured in 24-well plates and microfluidic bioreactor systems using the StemSpan serum-free medium. Eventually, we analyzed cell surface expression levels of the CXCR4 molecule and CXCR4 mRNA expression in CD133+ cells cultured in different systems.

Results

The expansion results showed significant improvement in CD133+ cell expansion in the microfluidic system than the conventional method. The median expression of the CXCR4 in the expanded cell was lower in the conventional system than in the microfluidic system. The CXCR4 gene expression up-regulated in the microfluidic system.

Conclusion

Utilizing microfluidic systems to expand desired cells effectively is the next step in cell culture. Comparative gene expression profiling provides a glimpse of the effects of culture microenvironments on the genetic program of HSCs grown in different systems.

Mitigating oxygen stress enhances aged mouse hematopoietic stem cell numbers and function

Bone marrow (BM) hematopoietic stem cells (HSCs) become dysfunctional during aging (i.e., they are increased in number but have an overall reduction in long-term repopulation potential and increased myeloid differentiation) compared with young HSCs, suggesting limited use of old donor BM cells for hematopoietic cell transplantation (HCT). BM cells reside in an in vivo hypoxic environment yet are evaluated after collection and processing in ambient air. We detected an increase in the number of both young and aged mouse BM HSCs collected and processed in 3% O2 compared with the number of young BM HSCs collected and processed in ambient air (~21% O2). Aged BM collected and processed under hypoxic conditions demonstrated enhanced engraftment capability during competitive transplantation analysis and contained more functional HSCs as determined by limiting dilution analysis. Importantly, the myeloid-to-lymphoid differentiation ratio of aged BM collected in 3% O2 was similar to that detected in young BM collected in ambient air or hypoxic conditions, consistent with the increased number of common lymphoid progenitors following collection under hypoxia. Enhanced functional activity and differentiation of old BM collected and processed in hypoxia correlated with reduced "stress" associated with ambient air BM collection and suggests that aged BM may be better and more efficiently used for HCT if collected and processed under hypoxia so that it is never exposed to ambient air O2.

A fish with no sex: gonadal and adrenal functions partition between zebrafish NR5A1 co-orthologs

People with NR5A1 mutations experience testicular dysgenesis, ovotestes, or adrenal insufficiency, but we do not completely understand the origin of this phenotypic diversity. NR5A1 is expressed in gonadal soma precursor cells before expression of the sex-determining gene SRY. Many fish have two co-orthologs of NR5A1 that likely partitioned ancestral gene subfunctions between them. To explore ancestral roles of NR5A1, we knocked out nr5a1a and nr5a1b in zebrafish. Single-cell RNA-seq identified nr5a1a-expressing cells that co-expressed genes for steroid biosynthesis and the chemokine receptor Cxcl12a in 1-day postfertilization (dpf) embryos, as does the mammalian adrenal-gonadal (interrenal-gonadal) primordium. In 2dpf embryos, nr5a1a was expressed stronger in the interrenal-gonadal primordium than in the early hypothalamus but nr5a1b showed the reverse. Adult Leydig cells expressed both ohnologs and granulosa cells expressed nr5a1a stronger than nr5a1b. Mutants for nr5a1a lacked the interrenal, formed incompletely differentiated testes, had no Leydig cells, and grew far larger than normal fish. Mutants for nr5a1b formed a disorganized interrenal and their gonads completely disappeared. All homozygous mutant genotypes lacked secondary sex characteristics, including male breeding tubercles and female sex papillae, and had exceedingly low levels of estradiol, 11-ketotestosterone, and cortisol. RNA-seq showed that at 21dpf, some animals were developing as females and others were not, independent of nr5a1 genotype. By 35dpf, all mutant genotypes greatly under-expressed ovary-biased genes. Because adult nr5a1a mutants form gonads but lack an interrenal and conversely, adult nr5a1b mutants lack a gonad but have an interrenal, the adrenal, and gonadal functions of the ancestral nr5a1 gene partitioned between ohnologs after the teleost genome duplication, likely owing to reciprocal loss of ancestral tissue-specific regulatory elements. Identifying such elements could provide hints to otherwise unexplained cases of Differences in Sex Development.

Fetal hematopoietic stem cell homing is controlled by VEGF regulating the integrity and oxidative status of the stromal-vascular bone marrow niches

Hematopoietic stem and progenitor cell (HSPC) engraftment after transplantation during anticancer treatment depends on support from the recipient bone marrow (BM) microenvironment. Here, by studying physiological homing of fetal HSPCs, we show the critical requirement of balanced local crosstalk within the skeletal niche for successful HSPC settlement in BM. Transgene-induced overproduction of vascular endothelial growth factor (VEGF) by osteoprogenitor cells elicits stromal and endothelial hyperactivation, profoundly impacting the stromal-vessel interface and vascular architecture. Concomitantly, HSPC homing and survival are drastically impaired. Transcriptome profiling, flow cytometry, and high-resolution imaging indicate alterations in perivascular and endothelial cell characteristics, vascular function and cellular metabolism, associated with increased oxidative stress within the VEGF-enriched BM environment. Thus, developmental HSPC homing to bone is controlled by local stromal-vascular integrity and the oxidative-metabolic status of the recipient milieu. Interestingly, irradiation of adult mice also induces stromal VEGF expression and similar osteo-angiogenic niche changes, underscoring that our findings may contribute targets for improving stem cell therapies.

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Establishment of BM hematopoiesis is coupled to development of the skeletal niches

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Primary HSPC seeding of bone depends on balanced molecular crosstalk in the niche

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Stromal VEGF triggers EC activation and controls stromal-vascular niche integrity

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Excessive skeletal VEGF deranges cell metabolism and induces oxidative stress in BM

Sclerostin Depletion Induces Inflammation in the Bone Marrow of Mice

Romosozumab, a humanized monoclonal antibody specific for sclerostin (SOST), has been approved for treatment of postmenopausal women with osteoporosis at a high risk for fracture. Previous work in sclerostin global knockout (Sost^-/-) mice indicated alterations in immune cell development in the bone marrow (BM), which could be a possible side effect in romosozumab-treated patients. Here, we examined the effects of short-term sclerostin depletion in the BM on hematopoiesis in young mice receiving sclerostin antibody (Scl-Ab) treatment for 6 weeks, and the effects of long-term Sost deficiency on wild-type (WT) long-term hematopoietic stem cells transplanted into older cohorts of Sost^-/- mice. Our analyses revealed an increased frequency of granulocytes in the BM of Scl-Ab-treated mice and WT→Sost^-/- chimeras, indicating myeloid-biased differentiation in Sost-deficient BM microenvironments. This myeloid bias extended to extramedullary hematopoiesis in the spleen and was correlated with an increase in inflammatory cytokines TNFα, IL-1α, and MCP-1 in Sost^-/- BM serum. Additionally, we observed alterations in erythrocyte differentiation in the BM and spleen of Sost^-/- mice. Taken together, our current study indicates novel roles for Sost in the regulation of myelopoiesis and control of inflammation in the BM.

Cell-Based Therapies for Trabecular Meshwork Regeneration to Treat Glaucoma

Glaucoma is clinically characterized by elevated intraocular pressure (IOP) that leads to retinal ganglion cell (RGC) and optic nerve damage, and eventually blindness if left untreated. Even in normal pressure glaucoma patients, a reduction of IOP is currently the only effective way to prevent blindness, by either increasing aqueous humor outflow or decreasing aqueous humor production. The trabecular meshwork (TM) and the adjacent Schlemm’s canal inner wall play a key role in regulating IOP by providing resistance when aqueous humor drains through the tissue. TM dysfunction seen in glaucoma, through reduced cellularity, abnormal extracellular matrix accumulation, and increased stiffness, contributes to elevated IOP, but current therapies do not target the TM tissue. Stem cell transplantation for regeneration and re-functionalization of damaged TM has shown promise in providing a more direct and effective therapy for glaucoma. In this review, we describe the use of different types of stem cells for TM regeneration in glaucoma models, the mechanisms of regeneration, and the potential for glaucoma treatment using autologous stem cell transplantation.

Nanogold-Carried Graphene Oxide: Anti-Inflammation and Increased Differentiation Capacity of Mesenchymal Stem Cells

Graphene-based nanocomposites such as graphene oxide (GO) and nanoparticle-decorated graphene with demonstrated excellent physicochemical properties have worthwhile applications in biomedicine and bioengineering such as tissue engineering. In this study, we fabricated gold nanoparticle-decorated GO (GO-Au) nanocomposites and characterized their physicochemical properties using UV-Vis absorption spectra, FTIR spectra, contact angle analyses, and free radical scavenging potential. Moreover, we investigated the potent applications of GO-Au nanocomposites on directing mesenchymal stem cells (MSCs) for tissue regeneration. We compared the efficacy of as-prepared GO-derived nanocomposites including GO, GO-Au, and GO-Au (×2) on the biocompatibility of MSCs, immune cell identification, anti-inflammatory effects, differentiation capacity, as well as animal immune compatibility. Our results showed that Au-deposited GO nanocomposites, especially GO-Au (×2), significantly exhibited increased cell viability of MSCs, had good anti-oxidative ability, sponged the immune response toward monocyte-macrophage transition, as well as inhibited the activity of platelets. Moreover, we also validated the superior efficacy of Au-deposited GO nanocomposites on the enhancement of cell motility and various MSCs-derived cell types of differentiation including neuron cells, adipocytes, osteocytes, and endothelial cells. Additionally, the lower induction of fibrotic formation, reduced M1 macrophage polarization, and higher induction of M2 macrophage, as well as promotion of the endothelialization, were also found in the Au-deposited GO nanocomposites implanted animal model. These results suggest that the Au-deposited GO nanocomposites have excellent immune compatibility and anti-inflammatory effects in vivo and in vitro. Altogether, our findings indicate that Au-decorated GO nanocomposites, especially GO-Au (×2), can be a potent nanocarrier for tissue engineering and an effective clinical strategy for anti-inflammation.

Polyfunctionality of the CXCR4/CXCL12 axis in health and disease: Implications for therapeutic interventions in cancer and immune-mediated diseases

Historically the chemokine receptor CXCR4 and its canonical ligand CXCL12 are associated with the bone marrow niche and hematopoiesis. However, CXCL12 exhibits broad tissue expression including brain, thymus, heart, lung, liver, kidney, spleen, and bone marrow. CXCR4 can be considered as a node which is integrating and transducing inputs from a range of ligand-receptor interactions into a responsive and divergent network of intracellular signaling pathways that impact multiple cellular processes such as proliferation, migration, and stress resistance. Dysregulation of the CXCR4/CXCL12 axis and consequent fundamental cellular processes, are associated with a panoply of disease. This review frames the polyfunctionality of the receptor at a molecular, physiological, and pathophysiological levels. Transitioning our perspective of this axis from a single gene/protein:single function model to a polyfunctional signaling cascade highlights the potential for finer therapeutic intervention and cautions against a reductionist approach.

Smooth Muscle Specific Ablation of CXCL12 in Mice Downregulates CXCR7 Associated with Defective Coronary Arteries and Cardiac Hypertrophy

The chemokine CXCL12 plays a fundamental role in cardiovascular development, cell trafficking, and myocardial repair. Human genome-wide association studies even have identified novel loci downstream of the CXCL12 gene locus associated with coronary artery disease and myocardial infarction. Nevertheless, cell and tissue specific effects of CXCL12 are barely understood. Since we detected high expression of CXCL12 in smooth muscle (SM) cells, we generated a SM22-alpha-Cre driven mouse model to ablate CXCL12 (SM-CXCL12^−/−). SM-CXCL12^−/− mice revealed high embryonic lethality (50%) with developmental defects, including aberrant topology of coronary arteries. Postnatally, SM-CXCL12^−/− mice developed severe cardiac hypertrophy associated with fibrosis, apoptotic cell death, impaired heart function, and severe coronary vascular defects characterized by thinned and dilated arteries. Transcriptome analyses showed specific upregulation of pathways associated with hypertrophic cardiomyopathy, collagen protein network, heart-related proteoglycans, and downregulation of the M2 macrophage modulators. CXCL12 mutants showed endothelial downregulation of the CXCL12 co-receptor CXCR7. Treatment of SM-CXCL12^−/− mice with the CXCR7 agonist TC14012 attenuated cardiac hypertrophy associated with increased pERK signaling. Our data suggest a critical role of smooth muscle-specific CXCL12 in arterial development, vessel maturation, and cardiac hypertrophy. Pharmacological stimulation of CXCR7 might be a promising target to attenuate adverse hypertrophic remodeling.

Role of CXCR4 in the progression and therapy of acute leukaemia

CXCR4 is expressed on leukaemia cells and haematopoietic stem cells (HSCs), and its ligand stromal-derived factor 1 (SDF-1) is produced abundantly by stromal cells in the bone marrow (BM). The SDF-1/CXCR4 axis plays important roles in homing to and retention in the protective BM microenvironment of malignant leukaemia cells and normal HSCs. CXCR4 expression is regulated by multiple mechanisms and the level of CXCR4 expression on leukaemia cells has prognostic indications in patients with acute leukaemia. CXCR4 antagonists can mobilize leukaemia cells from BM to circulation, which render them effectively eradicated by chemotherapeutic agents, small molecular inhibitors or hypomethylating agents. Therefore, such combinational therapies have been tested in clinical trials. However, new evidence emerged that drug-resistant leukaemia cells were not affected by CXCR4 antagonists, and the migration of certain leukaemia cells to the leukaemia niche was independent of SDF-1/CXCR4 axis. In this review, we summarize the role of CXCR4 in progression and treatment of acute leukaemia, with a focus on the potential of CXCR4 as a therapeutic target for acute leukaemia. We also discuss the potential value of using CXCR4 antagonists as chemosensitizer for conditioning regimens and immunosensitizer for graft-vs-leukaemia effects of allogeneic haematopoietic stem cell transplantation.

Marginal Zone Formation Requires ACKR3 Expression on B Cells

The marginal zone (MZ) contributes to the highly organized spleen microarchitecture. We show that expression of atypical chemokine receptor 3 (ACKR3) defines two equal-sized populations of mouse MZ B cells (MZBs). ACKR3 is required for development of a functional MZ and for positioning of MZBs. Deletion of ACKR3 on B cells distorts the MZ, and MZBs fail to deliver antigens to follicles, reducing humoral responses. Reconstitution of MZ-deficient CD19^ko mice shows that ACKR3^- MZBs can differentiate into ACKR3⁺ MZBs, but not vice versa. The lack of a MZ is rescued by adoptive transfer of ACKR3-sufficient, and less by ACKR3-deficient, follicular B cells (FoBs); hence, ACKR3 expression is crucial for establishment of the MZ. The inability of CD19^ko mice to respond to T-independent antigen is rescued when ACKR3-proficient, but not ACKR3-deficient, FoBs are transferred. Accordingly, ACKR3-deficient FoBs are able to reconstitute the MZ if the niche is pre-established by ACKR3-proficient MZBs.

Tumor microenvironment immune-related lncRNA signature for patients with melanoma

Background

The incidence of malignant melanoma accounts for only approximately 5% of skin malignant tumors, however, it accounts for 75% of its mortality. Long-chain non-coding RNA (lncRNA) has a wide range of functional activities. Disorders of lncRNAs may lead to the occurrence and development of melanoma, and may also be related to immunotherapy.

Methods

The transcriptomic data of primary and metastatic melanoma patients and 331 immune-related genes were downloaded from skin cutaneous melanoma (SKCM) in the The Cancer Genome Atlas (TCGA) database. On this basis, 460 immunologically relevant lncRNAs were identified by constructing a co-expression network of immunogenic genes and lncRNAs in primary and metastatic melanoma patients. Prognostic genes were screened using univariate Cox regression analysis. ROC analysis was performed to evaluate the robustness of the prognostic signature.

Results

Univariate correlation analysis showed that only 3 of the 23 immune-related lncRNAs were at high risk and the rest were at low risk. Signatures of 7 immune-related lncRNAs were identified by multivariate correlation analysis. The clinical correlation analysis showed that the 7 immune-related lncRNAs were associated with the clinical stage of primary and metastatic melanoma. Principal component analysis (PCA) showed that only 7 immune-related lncRNA signals divided tumor patients into high-risk and low-risk groups, while the low-risk group was enriched in the immune system process M13664 and immune response M19817 sets. PPI interaction network analysis showed that 11 G protein-coupled receptors and 6 corresponding ligands in the 2 gene sets affected the tumor microenvironment and were negatively related to the risk of the 7 immune-related lncRNAs. The tumor microenvironment immune cell infiltration analysis also supported the finding that anti-tumor immunity in the low-risk group was stronger than in the high-risk group.

Conclusions

These results indicate that characteristics of the 7 immune-related lncRNAs have prognostic value for melanoma patients and can be used as potential immunotherapy targets.

Angiogenic Properties of Concentrated Growth Factors (CGFs): The Role of Soluble Factors and Cellular Components

Blood-derived concentrated growth factors (CGFs) represent a novel autologous biomaterial with promising applications in regenerative medicine. Angiogenesis is a key factor in tissue regeneration, but the role played by CGFs in vessel formation is not clear. The purpose of this study was to characterize the angiogenic properties of CGFs by evaluating the effects of its soluble factors and cellular components on the neovascularization in an in vitro model of angiogenesis. CGF clots were cultured for 14 days in cell culture medium; after that, CGF-conditioned medium (CGF-CM) was collected, and soluble factors and cellular components were separated and characterized. CGF-soluble factors, such as growth factors (VEGF and TGF-β1) and matrix metalloproteinases (MMP-2 and -9), were assessed by ELISA. Angiogenic properties of CGF-soluble factors were analyzed by stimulating human cultured endothelial cells with increasing concentrations (1%, 5%, 10%, or 20%) of CGF-CM, and their effect on cell migration and tubule-like formation was assessed by wound healing and Matrigel assay, respectively. The expression of endothelial angiogenic mediators was determined using qRT-PCR and ELISA assays. CGF-derived cells were characterized by immunostaining, qRT-PCR and Matrigel assay. We found that CGF-CM, consisting of essential pro-angiogenic factors, such as VEGF, TGF-β1, MMP-9, and MMP-2, promoted endothelial cell migration; tubule structure formation; and endothelial expression of multiple angiogenic mediators, including growth factors, chemokines, and metalloproteinases. Moreover, we discovered that CGF-derived cells exhibited features such as endothelial progenitor cells, since they expressed the CD34 stem cell marker and endothelial markers and participated in the neo-angiogenic process. In conclusion, our results suggest that CGFs are able to promote endothelial angiogenesis through their soluble and cellular components and that CGFs can be used as a biomaterial for therapeutic vasculogenesis in the field of tissue regeneration.

Differential Expression of the Tetraspanin CD9 in Normal and Leukemic Stem Cells

Simple Summary

Before their use in regenerative medicine, stem cells need to be expanded to obtain sufficient cells for the efficient reparation of the injured tissues. This expansion must not affect their integrity. Regarding the role played by different receptors, we observed that, during their expansion, the number of promising pluripotent stem cells found in adult tissues, i.e., very small embryonic-like stem cells (VSELs), which express the CD9 receptor, decreased. This is due to their higher mortality rate compared to that of those not expressing CD9, which can lead to low regenerative efficiency for injured tissues. Interestingly, this could be overcome by the addition of a specific growth factor, allowing the re-establishment of their function. Finally, we found that the expression of this receptor is also deregulated in cells phenotypically identical to VSELs isolated from leukemic patients, which attests to the instability of its expression and may explain disease progression.

Abstract

CD9 plays a crucial role in cellular growth, mobility, and signal transduction, as well as in hematological malignancy. In myeloid neoplasms, CD9 is involved in the altered interactions between leukemic and stromal cells. However, apart from its role in CD34⁺ progenitors and myeloid and megakaryocytic differentiation, its function in normal and leukemic pluripotent cells has not yet been determined. Very small embryonic-like stem cells (VSELs) are promising pluripotent stem cells found in adult tissues that can be developed for safe and efficient regenerative medicine. VSELs express different surface receptors of the highest importance in cell functioning, including CD9, and can be effectively mobilized after organ injury or in leukemic patients. In the present study, we observed that CD9 is among the most expressed receptors in VSELs under steady-state conditions; however, once the VSELs are expanded, CD9⁺ VSELs decrease and are more apoptotic. CD9^– VSELs had no proliferative improvement in vitro compared to those that were CD9⁺. Interestingly, the addition of SDF-1 induced CD9 expression on the surface of VSELs, as observed by flow cytometry, and improved their migration. In addition, we observed, in the phenotypically identical VSELs present in the peripheral blood of patients with myeloproliferative neoplasms, compared to healthy subjects, a significantly higher number of CD9⁺ cells. However, in their hematopoietic stem cell (HSC) counterparts, the expression remained comparable. These results indicate that, likewise, in progenitors and mature cells, CD9 may play an important function in normal and malignant VSELs. This could explain the refractoriness observed by some groups of expanded stem cells to repairing efficiently damaged tissue when used as a source in cell therapies. Understanding the function of the CD9 receptor in normal and malignant CD34⁺ and VSELs, along with its relationship with the CXCR4/SDF-1 pathway, will enable advances in the field of adult pluripotent cell usage in regenerative medicine and in their role in leukemia.

Mycobacterial infection-induced miR-206 inhibits protective neutrophil recruitment via the CXCL12/CXCR4 signalling axis

Pathogenic mycobacteria actively dysregulate protective host immune signalling pathways during infection to drive the formation of permissive granuloma microenvironments. Dynamic regulation of host microRNA (miRNA) expression is a conserved feature of mycobacterial infections across host-pathogen pairings. Here we examine the role of miR-206 in the zebrafish model of Mycobacterium marinum infection, which allows investigation of the early stages of granuloma formation. We find miR-206 is upregulated following infection by pathogenic M. marinum and that antagomir-mediated knockdown of miR-206 is protective against infection. We observed striking upregulation of cxcl12a and cxcr4b in infected miR-206 knockdown zebrafish embryos and live imaging revealed enhanced recruitment of neutrophils to sites of infection. We used CRISPR/Cas9-mediated knockdown of cxcl12a and cxcr4b expression and AMD3100 inhibition of Cxcr4 to show that the enhanced neutrophil response and reduced bacterial burden caused by miR-206 knockdown was dependent on the Cxcl12/Cxcr4 signalling axis. Together, our data illustrate a pathway through which pathogenic mycobacteria induce host miR-206 expression to suppress Cxcl12/Cxcr4 signalling and prevent protective neutrophil recruitment to granulomas.

CXCR4 inhibition with AMD3100 attenuates amphetamine induced locomotor activity in adolescent Long Evans male rats

Adolescent psychostimulant abuse has been on the rise over the past decade. This trend has demonstrable ramifications on adolescent behavior and brain morphology, increasing risk for development of addiction during adolescence and in later adulthood. Neuroimmune substrates are implicated in the etiology of substance use disorders. To add to this body of work, the current study was developed to explore the role of a chemokine receptor, CXC Chemokine Receptor 4 (CXCR4), in the development of amphetamine (AMPH) sensitization. We targeted CXCR4 as it is implicated in developmental processes, dopaminergic transmission, neuroimmune responses, and the potentiation of psychostimulant abuse pathology. To evaluate the role of CXCR4 activity on the development of AMPH sensitization, a CXCR4 antagonist (Plerixafor; AMD3100) was administered to rats as a pretreatment variable. Specifically, adolescent Long Evans male rats (N = 37) were divided into four groups: (1) AMD3100 (IP, 4.0 mg/kg) + AMPH (IP, 4.0 mg/kg), (2) saline (SAL; 0.9% NaCl) + AMPH, (3) AMD3100 + SAL, and (4) SAL + SAL. Animals were first habituated to locomotor activity (LMA) chambers, then injected with a pretreatment drug (AMD3100 or SAL) followed by AMPH or SAL every other for four days. After a one-week withdrawal period, all animals were administered a low challenge dose of AMPH (IP, 1.0 mg/kg). AMPH-injected rats displayed significantly more locomotor activity compared to controls across all testing days. CXCR4 antagonism significantly attenuated AMPH-induced locomotor activity. On challenge day, AMD3100 pre-treated animals exhibited diminutive AMPH-induced locomotor activity compared to SAL pre-treated animals. Postmortem analyses of brain tissue revealed elevated CXCR4 protein levels in the striatum of all experimental groups. Our results implicate CXCR4 signaling in the development of AMPH sensitization and may represent an important therapeutic target for future research in psychostimulant abuse.

Strategies and progress in CXCR4-targeted anti-HIV therapeutic development

The acquired immunodeficiency syndrome (AIDS), caused by the human immunodeficiency virus (HIV), has been a global public health challenge for several decades. The majority of HIV infection is caused by the human immunodeficiency virus type 1 (HIV-1) which enters and infects a host cell via the cell surface proteins of CD4 as the primary receptor, and chemokine receptors CXCR4 or CCR5 as the co-receptor-then undergoing replication using the cell's intracellular machinery. Whereas many drugs targeting CCR5-mediated entry or HIV-1 replication via reverse transcriptase or proteases have long been used clinically, agents targeting CXCR4 are yet to be advanced to clinical application. Here in this review we highlight some of the strategies for and progress made in the discovery of novel small molecules, peptides, and larger molecules that target CXCR4, and their future prospects for translation into the clinic as a new class of anti-HIV therapeutics.

WT1-specific CD8 + cytotoxic T cells with the capacity for antigen-specific expansion accumulate in the bone marrow in MDS

Wilms' tumor 1 (WT1) is a tumor-associated antigen and immunotherapy target in myelodysplastic syndrome (MDS). Further information is needed on the characteristics of WT1-specific CD8 + T cells to develop immunotherapeutic strategies for MDS. To clarify the frequency, distribution, and phenotype of WT1-specific CD8 + T cells, which occur innately in MDS patients, we analyzed paired peripheral blood (PB) and bone marrow (BM) samples from 39 patients with MDS or acute myeloid leukemia with myelodysplasia-related changes. The median frequency of WT1 tetramer-binding CD8 + T cells in the CD8 + T cell population was 0.11% in PB and 0.18% in BM. A further tetramer assay combined with mixed lymphocyte peptide culture (MLPC assay) was used to detect functional WT1-specific CD8 + T cells that could respond to the WT1 peptide. Functional WT1-specific CD8 + T cells were detected in BM in 61% of patients, which was significantly higher than in PB (23%, p = 0.001). The frequency of these cells estimated by the MLPC assay was tenfold higher in BM than in PB. The majority of WT1 tetramer-binding CD8 + T cells in BM had a unique phenotype with co-expression of CD39 and CXCR4. These findings will facilitate the development of novel immunotherapeutic strategies for MDS.

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.

Chemokine signaling is required for homeostatic and injury-induced neurogenesis in the olfactory epithelium

The olfactory epithelium (OE) possesses unique lifelong neuroregenerative capacities and undergoes constitutive neurogenesis throughout mammalian lifespan. Two populations of stem cells, frequently dividing globose basal cells (GBCs) and quiescent horizontal basal cells (HBCs), readily replace olfactory neurons throughout lifetime. Although lineage commitment and neuronal differentiation of stem cells has already been described in terms of transcription factor expression, little is known about external factors balancing between differentiation and self-renewal. We show here that expression of the CXC-motif chemokine receptor 4 (CXCR4) distinguishes both types of stem cells. Extensive colocalization analysis revealed exclusive expression of CXCR4 in proliferating GBCs and their neuronal progenies. Moreover, only neuronal lineage cells were derived from CXCR4-CreER-tdTomato reporter mice in the OE. Furthermore, Cre-tdTomato mice specific for HBCs (Nestin+ and Cytokeratin14+) did not reduce CXCR4 expression when bred to mice bearing floxed CXCR4 alleles, and did not show labeling of the neuronal cells. CXCR4 and its ligand CXCL12 were markedly upregulated upon induction of GBC proliferation during injury-induced regeneration. in vivo overexpression of CXCL12 did downregulate CXCR4 levels, which results in reduced GBC maintenance and neuronal differentiation. We proved that these effects were caused by CXCR4 downregulation rather than over-activation by showing that the phenotypes of CXCL12-overexpressing mice were highly similar to the phenotypes of CXCR4 knockout mice. Our results demonstrate functional CXCR4 signaling in GBCs regulates cell cycle exit and neural differentiation. We propose that CXCR4/CXCL12 signaling is an essential regulator of olfactory neurogenesis and provide new insights into the dynamics of neurogenesis in the OE.

Identification of latent core genes and pathways associated with myelodysplastic syndromes based on integrated bioinformatics analysis

Background: Myelodysplastic syndromes (MDS) are relatively common hematological malignancies characterized by dysplastic hematopoiesis in one or more of the lineages of the bone marrow. This study aimed to identify critical pathogenic biomarkers associated with the carcinogenesis and progression of MDS. Methods: To explore the candidate genes, the expression profiles of GSE2779, GSE4619, and GSE19429 were downloaded from the Gene Expression Omnibus (GEO) database, which contained CD34+ cells isolated from MDS patients and normal controls. The three microarray datasets were integrated to obtain differentially expressed genes (DEGs) and were deeply analyzed by bioinformatics methods. The construction of protein-protein interaction (PPI) network together with module analysis was performed based on Cytoscape software and the Search Tool for the Retrieval of Interacting Genes (STRING) database. Results: Our study identified 114 DEGs, which were highly enriched in various key pathways, including forkhead box protein O (FoxO) signaling pathway, the primary immunodeficiency, and hematopoietic cell lineage. Twelve core genes, such as FOXO1, PAX5 and CXCR4 were identified with a high degree of connectivity. It is plausible that FoxO signaling pathway plays an important role in MDS, and the dysregulation of FOXO1 was significantly associated with TGFβ, IL2/STAT5, Notch signaling and apoptosis pathways. Conclusion: The current study for the first time identified twelve latent indicators and their downstream targets, which might become significant biomarkers for worse clinical characteristics in MDS.

Drebrin regulates cytoskeleton dynamics in migrating neurons through interaction with CXCR4

Stromal cell-derived factor-1 (SDF-1) and chemokine receptor type 4 (CXCR4) are regulators of neuronal migration (e.g., GnRH neurons, cortical neurons, and hippocampal granule cells). However, how SDF-1/CXCR4 alters cytoskeletal components remains unclear. Developmentally regulated brain protein (drebrin) stabilizes actin polymerization, interacts with microtubule plus ends, and has been proposed to directly interact with CXCR4 in T cells. The current study examined, in mice, whether CXCR4 under SDF-1 stimulation interacts with drebrin to facilitate neuronal migration. Bioinformatic prediction of protein-protein interaction highlighted binding sites between drebrin and crystallized CXCR4. In migrating GnRH neurons, drebrin, CXCR4, and the microtubule plus-end binding protein EB1 were localized close to the cell membrane. Coimmunoprecipitation (co-IP) confirmed a direct interaction between drebrin and CXCR4 using wild-type E14.5 whole head and a GnRH cell line. Analysis of drebrin knockout (DBN1 KO) mice showed delayed migration of GnRH cells into the brain. A decrease in hippocampal granule cells was also detected, and co-IP confirmed a direct interaction between drebrin and CXCR4 in PN4 hippocampi. Migration assays on primary neurons established that inhibiting drebrin (either pharmacologically or using cells from DBN1 KO mice) prevented the effects of SDF-1 on neuronal movement. Bioinformatic prediction then identified binding sites between drebrin and the microtubule plus end protein, EB1, and super-resolution microscopy revealed decreased EB1 and drebrin coexpression after drebrin inhibition. Together, these data show a mechanism by which a chemokine, via a membrane receptor, communicates with the intracellular cytoskeleton in migrating neurons during central nervous system development.

Origins, Development, and Compartmentation of the Granule Cells of the Cerebellum

Granule cells (GCs) are the most numerous cell type in the cerebellum and indeed, in the brain: at least 99% of all cerebellar neurons are granule cells. In this review article, we first consider the formation of the upper rhombic lip, from which all granule cell precursors arise, and the way by which the upper rhombic lip generates the external granular layer, a secondary germinal epithelium that serves to amplify the upper rhombic lip precursors. Next, we review the mechanisms by which postmitotic granule cells are generated in the external granular layer and migrate radially to settle in the granular layer. In addition, we review the evidence that far from being a homogeneous population, granule cells come in multiple phenotypes with distinct topographical distributions and consider ways in which the heterogeneity of granule cells might arise during development.

The CXCL12gamma chemokine immobilized by heparan sulfate on stromal niche cells controls adhesion and mediates drug resistance in multiple myeloma

Background

The survival and proliferation of multiple myeloma (MM) cells in the bone marrow (BM) critically depend on interaction with stromal cells expressing the chemokine CXCL12. CXCL12 regulates the homing to the BM niche by mediating the transendothelial migration and adhesion/retention of the MM cells. The gamma isoform of CXCL12 (CXCL12γ) has been reported to be highly expressed in mouse BM and to show enhanced biological activity compared to the ‘common’ CXCL12α isoform, mediated by its unique extended C-terminal domain, which binds heparan sulfate proteoglycans (HSPGs) with an extraordinary high affinity. Here, we investigated the expression of CXCL12γ in human BM and studied its functional role in the interaction of MM cells with BM stromal cells (BMSCs).

Methods

We assessed CXCL12γ mRNA and protein expression by human BMSCs using qPCR, flow cytometry, and immunohistochemistry. CRISPR-Cas9 was employed to delete CXCL12γ and the heparan sulfate (HS) co-polymerase EXT1 in BMSCs. To study the functional roles of BMSC-derived CXCL12γ and HSPGs in the interaction of MM cells with BMSCs cells, MM cell lines and primary MM cells were co-cultured with BMSCs.

Results

We observed that CXCL12γ is expressed in situ by reticular stromal cells in both normal and MM BM, as well as by primary BMSC isolates and BMSC lines. Importantly, upon secretion, CXCL12γ, unlike the CXCL12α isoform, was retained on the surface of BMSCs. This membrane retention of CXCL12γ is HSPG mediated, since it was completely annulated by CRISPR-Cas9-mediated deletion of the HS co-polymerase EXT1. CXCL12γ expressed by BMSCs and membrane-retained by HSPGs supported robust adhesion of MM cells to the BMSCs. Specific genetic deletion of either CXCL12γ or EXT1 significantly attenuated the ability of BMSCs to support MM cell adhesion and, in addition, impaired their capacity to protect MM cells from bortezomib-induced cell death.

Conclusions

We show that CXCL12γ is expressed by human BMSCs and upon secretion is retained on their cell surface by HSPGs. The membrane-bound CXCL12γ controls adhesion of MM cells to the stromal niche and mediates drug resistance. These findings designate CXCL12γ and associated HSPGs as partners in mediating MM–niche interaction and as potential therapeutic targets in MM.