High expression of CXCR4 and stem cell markers in a monocrotaline and chronic hypoxia-induced rat model of pulmonary arterial hypertension

Stem Cell Studies in Cardiovascular Biology and Medicine: A Possible Key Role of Macrophages

Simple Summary

Stem cells are used in cardiovascular biology and biomedicine and this field of research is expanding. Two types of stem cells have been used in research: induced pluripotent and somatic stem cells. Induced pluripotent stem cells (iPSCs) are similar to embryonic stem cells (ESCs) in that they can differentiate into somatic cells. Bone marrow stem/stromal cells (BMSCs), adipose-derived stem cells (ASCs), and cardiac stem cells (CSCs) are somatic stem cells that have been used for cardiac regeneration. Recent studies have indicated that exosomes and vesicles from BMSCs and ASCs can be used in regenerative medicine and diagnostics. Chemokines and exosomes can contribute to the communication between inflammatory cells and stem cells to differentiate stem cells into the cell types required for tissue regeneration or repair. In this review, we address these issues based on our research and previous publications.

Abstract

Stem cells are used in cardiovascular biology and biomedicine, and research in this field is expanding. Two types of stem cells have been used in research: induced pluripotent and somatic stem cells. Stem cell research in cardiovascular medicine has developed rapidly following the discovery of different types of stem cells. Induced pluripotent stem cells (iPSCs) possess potent differentiation ability, unlike somatic stem cells, and have been postulated for a long time. However, differentiating into adult-type mature and functional cardiac myocytes (CMs) remains difficult. Bone marrow stem/stromal cells (BMSCs), adipose-derived stem cells (ASCs), and cardiac stem cells (CSCs) are somatic stem cells used for cardiac regeneration. Among somatic stem cells, bone marrow stem/stromal cells (BMSCs) were the first to be discovered and are relatively well-characterized. BMSCs were once thought to have differentiation ability in infarcted areas of the heart, but it has been identified that paracrine cytokines and micro-RNAs derived from BMSCs contributed to that effect. Moreover, vesicles and exosomes from these cells have similar effects and are effective in cardiac repair. The molecular signature of exosomes can also be used for diagnostics because exosomes have the characteristics of their origin cells. Cardiac stem cells (CSCs) differentiate into cardiomyocytes, smooth muscle cells, and endothelial cells, and supply cardiomyocytes during myocardial infarction by differentiating into newly formed cardiomyocytes. Stem cell niches and inflammatory cells play important roles in stem cell regulation and the recovery of damaged tissues. In particular, chemokines can contribute to the communication between inflammatory cells and stem cells. In this review, we present the current status of this exciting and promising research field.

CTRP9 Mitigates the Progression of Arteriovenous Shunt-Induced Pulmonary Artery Hypertension in Rats

The present study is aimed at investigating the molecular mechanism of C1q/TNF-related protein 9 (CTRP9) and providing a new perspective in arteriovenous shunt-induced pulmonary arterial hypertension (PAH). PAH was established by an arteriovenous shunt placement performed in rats. Adenovirus(Ad)-CTRP9 and Ad-green fluorescent protein viral particles were injected into the rats through the tail vein. Following 12 weeks, the mean pulmonary arterial pressure (mPAP) and right ventricular systolic pressure (RVSP) were measured and morphological analysis was conducted to confirm the establishment of the PAH model. The systemic elevation of CTRP9 maintained pulmonary vascular homeostasis and protected the rats from dysfunctional and abnormal remodeling. CTRP9 attenuated the pulmonary vascular remodeling in the shunt group by decreasing the mPAP and RVSP, which was associated with suppressed inflammation, apoptosis, and extracellular matrix injury. In addition, CTRP9 dramatically increased the phosphorylation of AKT and p38-MAPK in the lung tissues of shunt-operated animals. These findings suggest a previously unrecognized effect of CTRP9 in pulmonary vascular homeostasis during PAH pathogenesis.

Implication of proliferation gene biomarkers in pulmonary hypertension

Objective/Background

Proliferation is a widely recognized trigger for pulmonary hypertension (PH), a life-threatening, progressive disorder of pulmonary blood vessels. This study was aimed to identify some proliferation associated genes/targets for better comprehension of PH pathogenesis.

Methods

Human pulmonary arterial smooth muscle cells (hPASMCs) were cultured in the presence or absence of human recombinant platelet derived growth factor (rhPDGF)-BB. Cells were collected for metabolomics or transcriptomics study. Gene profiling of lungs of PH rats after hypoxia exposure or of PH patients were retrieved from GEO database.

Results

90 metabolites (VIP score >1, fold change >2 or <0.5 and p < .05) and 2701 unique metabolism associated genes (MAGs) were identified in rhPDGF-BB treated hPASMCs compared to control cells. In addition, 1151 differentially expressed genes (313 upregulated and 838 downregulated) were identified in rhPDGF-BB treated hPASMCs compared to control cells (fold change >2 or <0.5 and p < .05). 152 differentially expressed MAGs were then determined, out of which 9 hub genes (IL6, CXCL8, CCL2, CXCR4, CCND1, PLAUR, PLAU, HBEGF and F3) were defined as core proliferation associated hub genes in protein proten interaction analysis. In addition, the hub gene-based LASSO model can predict the occurrence of PH (AUC = 0.88). The expression of CXCR4, as one of the hub genes, was positively correlated to immune cell infiltrates.

Conclusion

Our findings revealed some key proliferation associated genes in PH, which provide the crucial information concerning complex metabolic reprogramming and inflammatory modulation in response to proliferation signals and might offer therapeutic gains for PH.

Circulating Nestin-GFP+ Cells Participate in the Pathogenesis of Paracoccidioides brasiliensis in the Lungs

Multiple infectious diseases lead to impaired lung function. Revealing the cellular mechanisms involved in this impairment is crucial for the understanding of how the lungs shift from a physiologic to a pathologic state in each specific condition. In this context, we explored the pathogenesis of Paracoccidioidomycosis, which affects pulmonary functioning. The presence of cells expressing Nestin-GFP has been reported in different tissues, and their roles as tissue-specific progenitors have been stablished in particular organs. Here, we explored how Nestin-GFP⁺ cells are affected after lung infection by Paracoccidioides brasiliensis, a model of lung granulomatous inflammation with fibrotic outcome. We used Nestin-GFP transgenic mice, parabiosis surgery, confocal microscopy and flow cytometry to investigate the participation of Nestin-GFP⁺ cells in Paracoccidioides brasiliensis pathogenesis. We revealed that these cells increase in the lungs post-Paracoccidioides brasiliensis infection, accumulating around granulomas. This increase was due mainly to Nestin-GPF⁺ cells derived from the blood circulation, not associated to blood vessels, that co-express markers suggestive of hematopoietic cells (Sca-1, CD45 and CXCR4). Therefore, our findings suggest that circulating Nestin-GFP⁺ cells participate in the Paracoccidioides brasiliensis pathogenesis in the lungs.

Anti-Breast Cancer Activities of Ketoprofen-RGD Conjugate by Targeting Breast Cancer Stem-Like Cells and Parental Cells

BACKGROUND

Cancer Stem Cells (CSCs) play an important role in various stages of cancer development, advancement, and therapy resistance. Ketoprofen-RGD has been revealed to act as an anti-cancer agent against some tumors.

OBJECTIVE

We aimed to explore the effects of a novel Ketoprofen-RGD compound on the suppression of Breast Cancer Stem-like Cells (BCSCs) and their parental cells.

METHODS

Mammospheres were developed from MCF-7 cells and assessed by CSC surface markers through flowcytometry. The anti-proliferative and pro-apoptotic activities of Ketoprofen-RGD were measured by MTS assay and flowcytometry. The expression levels of stemness markers and JAK2/STAT proteins were measured by quantitative Real Time-PCR (qRT-PCR) and western blotting, respectively. Intracellular Reactive Oxygen Species (ROS) was measured using a cell permeable, oxidant-sensitive fluorescence probe (carboxy-H2DCFDA).

RESULTS

Ketoprofen-RGD significantly reduced the mammosphere formation rate and the expression of three out of six stemness markers and remarkably decreased viability and induced apoptosis of spheroidal and parental cells compared to controls. Further experiments using CD95L, as a death ligand, and ZB4 antibody, as an extrinsic apoptotic pathway blocker, showed that Ketoprofen-RGD induced intrinsic pathway, suggesting a mechanism by which Ketoprofen-RGD triggers apoptosis. ROS production was also another way to induce apoptosis. Results of western blot analysis also revealed a marked diminish in the phosphorylation of JAK2 and STAT proteins.

CONCLUSION

Our study, for the first time, elucidated an anti-BCSC activity for Ketoprofen-RGD via declining stemness markers, inducing toxicity, and apoptosis in these cells and parental cells. These findings may suggest this compound as a promising anti-breast cancer.

Silibinin Upregulates CXCR4 Expression in Cultured Bone Marrow Cells (BMCs) Especially in Pulmonary Arterial Hypertension Rat Model

Previously we reported that silibinin ameliorated pulmonary arterial hypertension (PAH) in rat PAH models, possibly through the suppression of the CXCR4/SDF-1, until the point where PAH became a severe and irreversible condition. To further investigate how silibinin ameliorates PAH, we first attempted to clarify its effect on bone marrow cells (BMCs), since the CXCR4/SDF-1 axis is known to regulate stem cell migration and attachment in BM niches. Rat PAH models were established through a combination of a single subcutaneous injection of monocrotaline (MCT) and chronic hypoxic conditions (10% O₂). BMCs were harvested and cultured, and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and flow cytometry (FCM) were performed to investigate whether silibinin affected CXCR4 expression. Silibinin upregulated the gene expression of stem cell related markers CXCR4, SDF-1, SCF, and c-Kit, inflammatory markers IL-6 and TNFα, mesenchymal stem cell (MSC)-related markers CD44 and CD29, and the granulocyte/monocyte-macrophage marker CD14 in cultured BM in PAH rats, but not in normal rats, except CXCR4. FCM showed that silibinin increased the CXCR4-positive cell population in a granulocyte fraction of cultured BMCs. However, immunohistochemical (IHC) staining showed no significant change in CXCR4 expression in the BM of the tibias. These results suggest that silibinin increases the expression of CXCR4 in BM, and the increased CXCR4-positive cells could be granulocytes/monocyte-macrophages.

Pulmonary Hypertension Remodels the Genomic Fabrics of Major Functional Pathways

Pulmonary hypertension (PH) is a serious disorder with high morbidity and mortality rate. We analyzed the right-ventricular systolic pressure (RVSP), right-ventricular hypertrophy (RVH), lung histology, and transcriptomes of six-week-old male rats with PH induced by (1) hypoxia (HO), (2) administration of monocrotaline (CM), or (3) administration of monocrotaline and exposure to hypoxia (HM). The results in PH rats were compared to those in control rats (CO). After four weeks exposure, increased RVSP and RVH, pulmonary arterial wall thickening, and alteration of the lung transcriptome were observed in all PH groups. The HM group exhibited the largest alterations, as well as neointimal lesions and obliteration of the lumen in small arteries. We found that PH increased the expression of caveolin1, matrix metallopeptidase 2, and numerous inflammatory and cell proliferation genes. The cell cycle, vascular smooth muscle contraction, and oxidative phosphorylation pathways, as well as their interplay, were largely perturbed. Our results also suggest that the upregulated Rhoa (Ras homolog family member A) mediates its action through expression coordination with several ATPases. The upregulation of antioxidant genes and the extensive mitochondrial damage observed, especially in the HM group, indicate metabolic shift toward aerobic glycolysis.

Multiple roles of macrophage migration inhibitory factor in pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening condition arising from the loss and obstructive remodeling of the pulmonary arteries, leading to the sustained elevation of pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR) and subsequently right ventricular (RV) failure and death. PH encompasses a group of multifactorial diseases, such as pulmonary arterial hypertension (PAH) and chronic thromboembolic PH, for which there is no treatment that can stop or reverse the progression of remodeling of the pulmonary vasculature. The identification of new molecular targets for the development of more effective drugs is thus urgently needed. In this context, macrophage migration inhibitory factor (MIF), a pleiotropic upstream proinflammatory mediator, is emerging as a promising molecular target, as it contributes to perivascular inflammation and pulmonary arterial remodeling, two key hallmarks of PAH that are not specifically targeted by currently approved therapies. The objective of this review is to summarize the scientific evidence on the pathogenic roles of MIF and its potential as a biomarker and therapeutic target in PH/PAH.

Silibinin efficacy in a rat model of pulmonary arterial hypertension using monocrotaline and chronic hypoxia

Background

C-X-C chemokine receptor type 4 (CXCR4) may be involved in the development of pulmonary arterial hypertension (PAH). CXCR4 inhibitor AMD3100 was described to have a positive effect on the prevention of pulmonary arterial muscularization in PAH models. Silibinin is a traditional medicine that has an antagonistic effect on CXCR4. We investigated the effect of silibinin using rat models of PAH.

Methods

PAH was induced by a single subcutaneous injection of monocrotaline. The rats were maintained in a chronic hypoxic condition (10% O₂) with or without silibinin. To evaluate the efficacy of silibinin on PAH, right ventricular systolic pressure (RVSP), Fulton index (weight ratio of right ventricle to the left ventricle and septum), percent medial wall thickness (% MT), and vascular occlusion score (VOS) were measured and calculated. Immunohistochemical analysis was performed targeting CXCR4 and c-Kit. Reverse transcription-quantitative polymerase chain reaction was performed for the stem cell markers CXCR4, stromal cell derived factor-1 (SDF-1), c-Kit, and stem cell factor (SCF), and the inflammatory markers monocyte chemoattractant protein 1 (MCP1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα). Statistical analyses were performed using t-test and one-way analysis of variance with Bonferroni’s post hoc test.

Results

Silibinin treatment for 1 week reduced RVSP and Fulton index. Treatment for 2 weeks reduced RVSP, Fulton index, % MT, and VOS, as well as downregulating the expression of CXCR4, SDF-1, and TNFα in pulmonary arteries. In contrast, treatment for 3 weeks failed to ameliorate PAH. The time-course study demonstrated that RVSP, Fulton index, % MT, and VOS gradually increased over time, with a decrease in the expression of CXCR4 and TNFα occurring after 2 weeks of PAH development. After 3 weeks, SDF-1, c-Kit, and SCF began to decrease and, after 5 weeks, MCP1 and IL-6 gradually accumulated.

Conclusions

The CXCR4 inhibitor silibinin can ameliorate PAH, possibly through the suppression of the CXCR4/SDF-1 axis, until the point where PAH becomes a severe and irreversible condition. Silibinin results in reduced pulmonary arterial pressure and delays pulmonary arteriolar occlusion and pulmonary vascular remodeling.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1041-y) contains supplementary material, which is available to authorized users.

Involvement of CXCR4 in Normal and Abnormal Development

CXC motif chemokine receptor type 4 (CXCR4) is associated with normal and abnormal development, including oncogenesis. The ligand of CXCR4 is stromal cell-derived factor (SDF), also known as CXC motif ligand (CXCL) 12. Through the SDF-1/CXCR4 axis, both homing and migration of hematopoietic (stem) cells are regulated through niches in the bone marrow. Outside of the bone marrow, however, SDF-1 can recruit CXCR4-positive cells from the bone marrow. SDF/CXCR4 has been implicated in the maintenance and/or differentiation of stemness, and tissue-derived stem cells can be associated with SDF-1 and CXCR4 activity. CXCR4 plays a role in multiple pathways involved in carcinogenesis and other pathologies. Here, we summarize reports detailing the functions of CXCR4. We address the molecular signature of CXCR4 and how this molecule and cells expressing it are involved in either normal (maintaining stemness or inducing differentiation) or abnormal (developing cancer and other pathologies) events. As a constituent of stem cells, the SDF-1/CXCR4 axis influences downstream signal transduction and the cell microenvironment.

HIF-1α-Deficiency in Myeloid Cells Leads to a Disturbed Accumulation of Myeloid Derived Suppressor Cells (MDSC) During Pregnancy and to an Increased Abortion Rate in Mice

Abortions are the most important reason for unintentional childlessness. During pregnancy, maternal immune cells are in close contact to cells of the semi-allogeneic fetus. Dysregulation of the maternal immune system leading to defective adaptation to pregnancy often plays a role in pathogenesis of abortions. Myeloid-derived suppressor cells (MDSC) are myeloid cells that suppress functions of other immune cells, especially T-cells, thereby negatively affecting diseases such as cancer, sepsis or trauma. They seem, however, also necessary for maintenance of maternal-fetal tolerance. Mechanisms regulating MDSC expansion and function during pregnancy are only incompletely understood. In tumor environment, hypoxia is crucial for MDSC accumulation and activation. Hypoxia is also important for early placenta and embryo development. Effects of hypoxia are mediated through hypoxia-inducible factor 1α (HIF-1α). In the present study we aimed to examine the role of HIF-1α in myeloid cells for MDSC accumulation and MDSC function during pregnancy and for pregnancy outcome. We therefore used a mouse model with targeted deletion of HIF-1α in myeloid cells (myeloid HIF-KO) and analyzed blood, spleens and uteri of pregnant mice at gestational day E 10.5 in comparison to non-pregnant animals and wildtype (WT) animals. Further we analyzed pregnancy success by determining rates of failed implantation and abortion in WT and myeloid HIF-KO animals. We found that myeloid HIF-KO in mice led to an abrogated MDSC accumulation in the pregnant uterus and to impaired suppressive activity of MDSC. While expression of chemokine receptors and integrins on MDSC was not affected by HIF-1α, myeloid HIF-KO led to increased apoptosis rates of MDSC in the uterus. Myeloid-HIF-KO resulted in increased proportions of non-pregnant animals after positive vaginal plug and increased abortion rates, suggesting that activation of HIF-1α dependent pathways in MDSC are important for maintenance of pregnancy.