Hyperhomocysteinemia suppresses bone marrow CD34+/VEGF receptor 2+ cells and inhibits progenitor cell mobilization and homing to injured vasculature-a role of β1-integrin in progenitor cell migration and adhesion

C1q/Tumor Necrosis Factor-Related Protein-9 Is a Novel Vasculoprotective Cytokine That Restores High Glucose-Suppressed Endothelial Progenitor Cell Functions by Activating the Endothelial Nitric Oxide Synthase

BACKGROUND

This study investigated whether gCTRP9 (globular C1q/tumor necrosis factor-related protein-9) could restore high-glucose (HG)-suppressed endothelial progenitor cell (EPC) functions by activating the endothelial nitric oxide synthase (eNOS).

METHODS AND RESULTS

EPCs were treated with HG (25 mmol/L) and gCTRP9. Migration, adhesion, and tube formation assays were performed. Adiponectin receptor 1, adiponectin receptor 2, and N-cadherin expression and AMP-activated protein kinase, protein kinase B, and eNOS phosphorylation were measured by Western blotting. eNOS activity was determined using nitrite production measurement. In vivo reendothelialization and EPC homing assays were performed using Evans blue and immunofluorescence in mice. Treatment with gCTRP9 at physiological levels enhanced migration, adhesion, and tube formation of EPCs. gCTRP9 upregulated the phosphorylation of AMP-activated protein kinase, protein kinase B, and eNOS and increased nitrite production in a concentration-dependent manner. Exposure of EPCs to HG-attenuated EPC functions induced cellular senescence and decreased eNOS activity and nitric oxide synthesis; the effects of HG were reversed by gCTRP9. Protein kinase B knockdown inhibited eNOS phosphorylation but did not affect gCTRP9-induced AMP-activated protein kinase phosphorylation. HG impaired N-cadherin expression, but treatment with gCTRP9 restored N-cadherin expression after HG stimulation. gCTRP9 restored HG-impaired EPC functions through both adiponectin receptor 1 and N-cadherin-mediated AMP-activated protein kinase /protein kinase B/eNOS signaling. Nude mice that received EPCs treated with gCTRP9 under HG medium showed a significant enhancement of the reendothelialization capacity compared with those with EPCs incubated under HG conditions.

CONCLUSIONS

CTRP9 promotes EPC migration, adhesion, and tube formation and restores these functions under HG conditions through eNOS-mediated signaling mechanisms. Therefore, CTRP9 modulation could eventually be used for vascular healing after injury.

29 m6A-RNA Methylation (Epitranscriptomic) Regulators Are Regulated in 41 Diseases including Atherosclerosis and Tumors Potentially via ROS Regulation - 102 Transcriptomic Dataset Analyses

We performed a database mining on 102 transcriptomic datasets for the expressions of 29 m⁶A-RNA methylation (epitranscriptomic) regulators (m⁶A-RMRs) in 41 diseases and cancers and made significant findings: (1) a few m⁶A-RMRs were upregulated; and most m⁶A-RMRs were downregulated in sepsis, acute respiratory distress syndrome, shock, and trauma; (2) half of 29 m⁶A-RMRs were downregulated in atherosclerosis; (3) inflammatory bowel disease and rheumatoid arthritis modulated m⁶A-RMRs more than lupus and psoriasis; (4) some organ failures shared eight upregulated m⁶A-RMRs; end-stage renal failure (ESRF) downregulated 85% of m⁶A-RMRs; (5) Middle-East respiratory syndrome coronavirus infections modulated m⁶A-RMRs the most among viral infections; (6) proinflammatory oxPAPC modulated m⁶A-RMRs more than DAMP stimulation including LPS and oxLDL; (7) upregulated m⁶A-RMRs were more than downregulated m⁶A-RMRs in cancer types; five types of cancers upregulated ≥10 m⁶A-RMRs; (8) proinflammatory M1 macrophages upregulated seven m⁶A-RMRs; (9) 86% of m⁶A-RMRs were differentially expressed in the six clusters of CD4⁺Foxp3⁺ immunosuppressive Treg, and 8 out of 12 Treg signatures regulated m⁶A-RMRs; (10) immune checkpoint receptors TIM3, TIGIT, PD-L2, and CTLA4 modulated m⁶A-RMRs, and inhibition of CD40 upregulated m⁶A-RMRs; (11) cytokines and interferons modulated m⁶A-RMRs; (12) NF-κB and JAK/STAT pathways upregulated more than downregulated m⁶A-RMRs whereas TP53, PTEN, and APC did the opposite; (13) methionine-homocysteine-methyl cycle enzyme Mthfd1 downregulated more than upregulated m⁶A-RMRs; (14) m⁶A writer RBM15 and one m⁶A eraser FTO, H3K4 methyltransferase MLL1, and DNA methyltransferase, DNMT1, regulated m⁶A-RMRs; and (15) 40 out of 165 ROS regulators were modulated by m⁶A eraser FTO and two m⁶A writers METTL3 and WTAP. Our findings shed new light on the functions of upregulated m⁶A-RMRs in 41 diseases and cancers, nine cellular and molecular mechanisms, novel therapeutic targets for inflammatory disorders, metabolic cardiovascular diseases, autoimmune diseases, organ failures, and cancers.

Novel Knowledge-Based Transcriptomic Profiling of Lipid Lysophosphatidylinositol-Induced Endothelial Cell Activation

To determine whether pro-inflammatory lipid lysophosphatidylinositols (LPIs) upregulate the expressions of membrane proteins for adhesion/signaling and secretory proteins in human aortic endothelial cell (HAEC) activation, we developed an EC biology knowledge-based transcriptomic formula to profile RNA-Seq data panoramically. We made the following primary findings: first, G protein-coupled receptor 55 (GPR55), the LPI receptor, is expressed in the endothelium of both human and mouse aortas, and is significantly upregulated in hyperlipidemia; second, LPIs upregulate 43 clusters of differentiation (CD) in HAECs, promoting EC activation, innate immune trans-differentiation, and immune/inflammatory responses; 72.1% of LPI-upregulated CDs are not induced in influenza virus-, MERS-CoV virus- and herpes virus-infected human endothelial cells, which hinted the specificity of LPIs in HAEC activation; third, LPIs upregulate six types of 640 secretomic genes (SGs), namely, 216 canonical SGs, 60 caspase-1-gasdermin D (GSDMD) SGs, 117 caspase-4/11-GSDMD SGs, 40 exosome SGs, 179 Human Protein Atlas (HPA)-cytokines, and 28 HPA-chemokines, which make HAECs a large secretory organ for inflammation/immune responses and other functions; fourth, LPIs activate transcriptomic remodeling by upregulating 172 transcription factors (TFs), namely, pro-inflammatory factors NR4A3, FOS, KLF3, and HIF1A; fifth, LPIs upregulate 152 nuclear DNA-encoded mitochondrial (mitoCarta) genes, which alter mitochondrial mechanisms and functions, such as mitochondrial organization, respiration, translation, and transport; sixth, LPIs activate reactive oxygen species (ROS) mechanism by upregulating 18 ROS regulators; finally, utilizing the Cytoscape software, we found that three mechanisms, namely, LPI-upregulated TFs, mitoCarta genes, and ROS regulators, are integrated to promote HAEC activation. Our results provide novel insights into aortic EC activation, formulate an EC biology knowledge-based transcriptomic profile strategy, and identify new targets for the development of therapeutics for cardiovascular diseases, inflammatory conditions, immune diseases, organ transplantation, aging, and cancers.

Organelle Crosstalk Regulators Are Regulated in Diseases, Tumors, and Regulatory T Cells: Novel Classification of Organelle Crosstalk Regulators

To examine whether the expressions of 260 organelle crosstalk regulators (OCRGs) in 16 functional groups are modulated in 23 diseases and 28 tumors, we performed extensive -omics data mining analyses and made a set of significant findings: (1) the ratios of upregulated vs. downregulated OCRGs are 1:2.8 in acute inflammations, 1:1 in metabolic diseases, 1:1.2 in autoimmune diseases, and 1:3.8 in organ failures; (2) sepsis and trauma-upregulated OCRG groups such as vesicle, mitochondrial (MT) fission, and mitophagy but not others, are termed as the cell crisis-handling OCRGs. Similarly, sepsis and trauma plus organ failures upregulated seven OCRG groups including vesicle, MT fission, mitophagy, sarcoplasmic reticulum–MT, MT fusion, autophagosome–lysosome fusion, and autophagosome/endosome–lysosome fusion, classified as the cell failure-handling OCRGs; (3) suppression of autophagosome–lysosome fusion in endothelial and epithelial cells is required for viral replications, which classify this decreased group as the viral replication-suppressed OCRGs; (4) pro-atherogenic damage-associated molecular patterns (DAMPs) such as oxidized low-density lipoprotein (oxLDL), lipopolysaccharide (LPS), oxidized-1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (oxPAPC), and interferons (IFNs) totally upregulated 33 OCRGs in endothelial cells (ECs) including vesicle, MT fission, mitophagy, MT fusion, endoplasmic reticulum (ER)–MT contact, ER– plasma membrane (PM) junction, autophagosome/endosome–lysosome fusion, sarcoplasmic reticulum–MT, autophagosome–endosome/lysosome fusion, and ER–Golgi complex (GC) interaction as the 10 EC-activation/inflammation-promoting OCRG groups; (5) the expression of OCRGs is upregulated more than downregulated in regulatory T cells (Tregs) from the lymph nodes, spleen, peripheral blood, intestine, and brown adipose tissue in comparison with that of CD4⁺CD25⁻ T effector controls; (6) toll-like receptors (TLRs), reactive oxygen species (ROS) regulator nuclear factor erythroid 2-related factor 2 (Nrf2), and inflammasome-activated regulator caspase-1 regulated the expressions of OCRGs in diseases, virus-infected cells, and pro-atherogenic DAMP-treated ECs; (7) OCRG expressions are significantly modulated in all the 28 cancer datasets, and the upregulated OCRGs are correlated with tumor immune infiltrates in some tumors; (8) tumor promoter factor IKK2 and tumor suppressor Tp53 significantly modulate the expressions of OCRGs. Our findings provide novel insights on the roles of upregulated OCRGs in the pathogenesis of inflammatory diseases and cancers, and novel pathways for the future therapeutic interventions for inflammations, sepsis, trauma, organ failures, autoimmune diseases, metabolic cardiovascular diseases (CVDs), and cancers.

Low-Energy Shockwave Treatment Promotes Endothelial Progenitor Cell Homing to the Stenotic Pig Kidney

Endothelial progenitor cells (EPCs) patrols the circulation and contributes to endothelial cell regeneration. Atherosclerotic renal artery stenosis (ARAS) induces microvascular loss in the stenotic kidney (STK). Low-energy shockwave therapy (SW) can induce angiogenesis and restore the STK microcirculation, but the underlying mechanism remains unclear. We tested the hypothesis that SW increases EPC homing to the swine STK, associated with capillary regeneration. Normal pigs and pigs after 3 wk of renal artery stenosis were treated with six sessions of low-energy SW (biweekly for three consecutive weeks) or left untreated. Four weeks after completion of treatment, we assessed EPC (CD34+/KDR+) numbers and levels of the homing-factor stromal cell-derived factor (SDF)-1 in the inferior vena cava and the STK vein and artery, as well as urinary levels of vascular endothelial growth factor (VEGF) and integrin-1β. Subsequently, we assessed STK morphology, capillary count, and expression of the proangiogenic growth factors angiopoietin-1, VEGF, and endothelial nitric oxide synthase ex vivo. A 3-wk low-energy SW regimen improved STK structure, capillary count, and function in ARAS+SW, and EPC numbers and gradients across the STK decreased. Plasma SDF-1 and renal expression of angiogenic factors were increased in ARAS+SW, and urinary levels of VEGF and integrin-1β tended to rise during the SW regimen. In conclusion, SW improves ischemic kidney capillary density, which is associated with, and may be at least in part mediated by, promoting EPCs mobilization and homing to the stenotic kidney.

Factors Affecting the Re-Endothelialization of Endothelial Progenitor Cell

The vascular endothelium, which plays an essential role in maintaining the normal shape and function of blood vessels, is a natural barrier between the circulating blood and the vascular wall tissue. The endothelial damage can cause vascular lesions, such as atherosclerosis and restenosis. After the vascular intima injury, the body starts the endothelial repair (re-endothelialization) to inhibit the neointimal hyperplasia. Endothelial progenitor cell is the precursor of endothelial cells and plays an important role in the vascular re-endothelialization. However, re-endothelialization is inevitably affected in vivo and in vitro by factors, which can be divided into two types, namely, promotion and inhibition, and act on different links of the vascular re-endothelialization. This article reviews these factors and related mechanisms.

Molecular processes mediating hyperhomocysteinemia-induced metabolic reprogramming, redox regulation and growth inhibition in endothelial cells

Hyperhomocysteinemia (HHcy) is an established and potent independent risk factor for degenerative diseases, including cardiovascular disease (CVD), Alzheimer disease, type II diabetes mellitus, and chronic kidney disease. HHcy has been shown to inhibit proliferation and promote inflammatory responses in endothelial cells (EC), and impair endothelial function, a hallmark for vascular injury. However, metabolic processes and molecular mechanisms mediating HHcy-induced endothelial injury remains to be elucidated. This study examined the effects of HHcy on the expression of microRNA (miRNA) and mRNA in human aortic EC treated with a pathophysiologically relevant concentration of homocysteine (Hcy 500 μM). We performed a set of extensive bioinformatics analyses to identify HHcy-altered metabolic and molecular processes. The global functional implications and molecular network were determined by Gene Set Enrichment Analysis (GSEA) followed by Cytoscape analysis. We identified 244 significantly differentially expressed (SDE) mRNA, their relevant functional pathways, and 45 SDE miRNA. HHcy-altered SDE inversely correlated miRNA-mRNA pairs (45 induced/14 reduced mRNA) were discovered and applied to network construction using an experimentally verified database. We established a hypothetical model to describe the biochemical and molecular network with these specified miRNA/mRNA axes, finding: 1) HHcy causes metabolic reprogramming by increasing glucose uptake and oxidation, by glycogen debranching and NAD⁺/CoA synthesis, and by stimulating mitochondrial reactive oxygen species production via NNT/IDH2 suppression-induced NAD⁺/NADP-NADPH/NADP⁺ metabolism disruption; 2) HHcy activates inflammatory responses by activating inflammasome-pyroptosis mainly through ↓miR193b→↑CASP-9 signaling and by inducing IL-1β and adhesion molecules through the ↓miR29c→↑NEDD9 and the ↓miR1256→↑ICAM-1 axes, as well as GPCR and interferon α/β signaling; 3) HHcy promotes cell degradation by the activation of lysosome autophagy and ubiquitin proteasome systems; 4) HHcy causes cell cycle arrest at G1/S and S/G2 transitions, suppresses spindle checkpoint complex and cytokinetic abscission, and suppresses proliferation through ↓miRNA335/↑VASH1 and other axes. These findings are in accordance with our previous studies and add a wealth of heretofore-unexplored molecular and metabolic mechanisms underlying HHcy-induced endothelial injury. This is the first study to consider the effects of HHcy on both global mRNA and miRNA expression changes for mechanism identification. Molecular axes and biochemical processes identified in this study are useful not only for the understanding of mechanisms underlying HHcy-induced endothelial injury, but also for discovering therapeutic targets for CVD in general.

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Identified multiple HHcy-altered metabolic and molecular processes potentially responsible for HHcy-induced endothelial injury via examining global mRNA/miRNA expression changes in Hcy-treated EC and performing comprehensive bioinformatic studies.

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HHcy may activate glucose uptake signaling via the ↓miR148b→↑SLC2A axis.

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HHcy may induce glucose oxidation signaling by switching pyruvate metabolism from lactate synthesis to mitochondrial oxidation via expression changes of ↑MPC1 & ↓LDHB.

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HHcy may disrupt redox homeostasis mostly by suppressing NNT/IDH2-related mt-NADPH/mt-NAD⁺ signaling.

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HHcy may increase FA β-oxidation, glutamine, TCA cycle and OXPHOS signaling.

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HHcy may activate inflammatory signaling via the ↓miR29c→↑NEDD9 and the ↓miR1256→↑ICAM-1 axes.

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HHcy may activate inflammasome/pyroptosis-related signaling by the ↓miR137→↑TLR3, the ↓miR574→↑TRAF5, and the ↓miR193b→↑CASP-9 axes, and induce IL1α/β and CASP-10/7.

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HHcy may induce inflammation signaling via GPCR activation through the ↓miRNA335→↑CXCR4/↑GNA14 axes.

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HHcy may activate molecular degradation process signaling through the ↓miRNA335→↑ASAH1/↑ABCB9 axes.

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HHcy may suppress cell cycle and proliferation through the miR491→↓HMGA2→↓CCNA2/CCNB2, the ↓miR335→↑VASH1, the ↓miR181a→↑PHLDA1, the miR6045→↓CENPH, the miR22→↓PRR11/↓BRCA2, and the miR605/miR497/miR514a→CEP55 axes

Canonical Secretomes, Innate Immune Caspase-1-, 4/11-Gasdermin D Non-Canonical Secretomes and Exosomes May Contribute to Maintain Treg-Ness for Treg Immunosuppression, Tissue Repair and Modulate Anti-Tumor Immunity via ROS Pathways

We performed a transcriptomic analyses using the strategies we pioneered and made the following findings: 1) Normal lymphoid Tregs, diseased kidney Tregs, splenic Tregs from mice with injured muscle have 3, 17 and 3 specific (S-) pathways, respectively; 2) Tumor splenic Tregs share 12 pathways with tumor Tregs; tumor splenic Tregs and tumor Tregs have 11 and 8 S-pathways, respectively; 3) Normal and non-tumor disease Tregs upregulate some of novel 2641 canonical secretomic genes (SGs) with 24 pathways, and tumor Tregs upregulate canonical secretomes with 17 pathways; 4) Normal and non-tumor disease tissue Tregs upregulate some of novel 6560 exosome SGs with 56 exosome SG pathways (ESP), tumor Treg ESP are more focused than other Tregs; 5) Normal, non-tumor diseased Treg and tumor Tregs upregulate some of novel 961 innate immune caspase-1 SGs and 1223 innate immune caspase-4 SGs to fulfill their tissue/SG-specific and shared functions; 6) Most tissue Treg transcriptomes are controlled by Foxp3; and Tumor Tregs had increased Foxp3 non-collaboration genes with ROS and 17 other pathways; 7) Immune checkpoint receptor PD-1 does, but CTLA-4 does not, play significant roles in promoting Treg upregulated genes in normal and non-tumor disease tissue Tregs; and tumor splenic and tumor Tregs have certain CTLA-4-, and PD-1-, non-collaboration transcriptomic changes with innate immune dominant pathways; 8) Tumor Tregs downregulate more immunometabolic and innate immune memory (trained immunity) genes than Tregs from other groups; and 11) ROS significantly regulate Treg transcriptomes; and ROS-suppressed genes are downregulated more in tumor Tregs than Tregs from other groups. Our results have provided novel insights on the roles of Tregs in normal, injuries, regeneration, tumor conditions and some of canonical and innate immune non-canonical secretomes via ROS-regulatory mechanisms and new therapeutic targets for immunosuppression, tissue repair, cardiovascular diseases, chronic kidney disease, autoimmune diseases, transplantation, and cancers.

Tissue Treg Secretomes and Transcription Factors Shared With Stem Cells Contribute to a Treg Niche to Maintain Treg-Ness With 80% Innate Immune Pathways, and Functions of Immunosuppression and Tissue Repair

We used functional -omics angles and examined transcriptomic heterogeneity in CD4⁺Foxp3⁺ regulatory T cells (Treg) from spleen (s-Treg), lymph nodes (LN-Treg), intestine (int-Treg), and visceral adipose tissue (VAT-Treg), and made significant findings: 1) Five new shared Treg genes including NIBAN, TNFRSF1b, DUSP4,VAV2, and KLRG1, and 68 new signatures are identified. Among 27 signaling pathways shared in four tissue Treg, 22 pathways are innate immune pathways (81.5%); 2) s-Treg, LN-Treg, int-Treg, and VAT-Treg have zero, 49, 45, and 116 upregulated pathways, respectively; 3) 12, 7, and 15 out of 373 CD markers are identified as specific for LN-Treg, int-Treg, and VAT-Treg, respectively, which may initiate innate immune signaling; 4) 7, 49, 44, and 79 increased cytokines out of 1176 cytokines are identified for four Treg, respectively, suggesting that Treg have much more secretory proteins/cytokines than IL-10, TGF-β, and IL-35; 5) LN-Treg, int-Treg, and VAT-Treg have 13 additional secretory functions more than s-Treg, found by analyzing 1,706 secretomic genes; 6) 2, 20, 25, and 43 increased transcription factors (TFs) out of 1,496 TFs are identified four Treg, respectively; 7) LN-Treg and int-Treg have increased pyroptosis regulators but VAT-Treg have increased apoptosis regulators; 8) 1, 15, 19, and 31 increased kinases out of 661 kinome are identified for s-Treg, LN-Treg, int-Treg, and VAT-Treg, respectively; 9) comparing with that of s-Treg, LN-Treg, int-Treg, and VAT-Treg increase activated cluster (clusters 1–3) markers; and decrease resting cluster (clusters 4–6) markers; and 10) Treg promote tissue repair by sharing secretomes and TFs AHR, ETV5, EGR1, and KLF4 with stem cells, which partially promote upregulation of all the groups of Treg genes. These results suggest that stem cell-shared master genes make tissue Treg as the first T cell type using a Treg niche to maintain their Treg-ness with 80% innate immune pathways, and triple functions of immunosuppression, tissue repair, and homeostasis maintenance. Our results have provided novel insights on the roles of innate immune pathways on Treg heterogeneity and new therapeutic targets for immunosuppression, tissue repair, cardiovascular diseases, chronic kidney disease, autoimmune diseases, transplantation, and cancers.

Importance of β2AR elevation for re-endothelialization capacity mediated by late endothelial progenitor cells in hypertensive patients

Dysfunction of late endothelial progenitor cells (EPCs) has been suggested to be associated with hypertension. β2-Adrenergic receptor (β2AR) is a novel and key target for EPC homing. Here, we proposed that attenuated β2AR signaling contributes to EPCs dysfunction, whereas enhanced β2AR signaling restores EPCs' functions in hypertension. EPCs derived from hypertensive patients exhibited reduced cell number, impaired in vitro migratory and adhesion abilities, and impaired re-endothelialization after transplantation in nude mice with carotid artery injury. β2AR expression of EPCs from hypertensive patients was markedly downregulated, whereas the phosphorylation of the p38 mitogen-activated protein kinase (p38-MAPK) was elevated. The cleaved caspase-3 levels were elevated in EPCs. The overexpression of β2AR in EPCs from hypertensive patients inhibited p38-MAPK signaling, whereas it enhanced in vitro EPC proliferation, migration, and adhesion and in vivo re-endothelialization. The β2AR-mediated effects were attenuated by treating the EPCs with a neutralizing monoclonal antibody against β2AR, which could be partially antagonized by the p38-MAPK inhibitor SB203580. Moreover, shear stress stimulation, a classic nonpharmacological intervention, increased the phosphorylation levels of β2AR and enhanced the in vitro and in vivo functions of EPCs from hypertensive patients. Collectively, the current investigation demonstrated that impaired β2AR/p38-MAPK/caspase-3 signaling at least partially reduced the re-endothelialization capacity of EPCs from hypertensive patients. Restoration of β2AR expression and shear stress treatment could improve their endothelial repair capacity by regulating the p38-MAPK/caspase-3 signaling pathway. The clinical significance of β2AR in endothelium repair still requires further investigation.NEW & NOTEWORTHY Impaired β2-adrenergic receptor (β2AR) expression with an elevation of p38-MAPK/caspase-3 signaling at least partially contributes to the decline of re-endothelialization capacity of late endothelial progenitor cells (EPCs) from hypertensive patients. β2AR gene transfer and shear stress treatment improve the late EPC-mediated enhancement of the re-endothelialization capacity in hypertensive patients through activating β2AR/p38-MAPK/caspase-3 signaling. The present study is the first to reveal the potential molecular mechanism of the impaired endothelium-reparative capacity of late EPCs in hypertension after vascular injury and strongly suggests that β2AR is a novel and crucial therapeutic target for increasing EPC-mediated re-endothelialization capacity in hypertension.

Approaching Inflammation Paradoxes-Proinflammatory Cytokine Blockages Induce Inflammatory Regulators

The mechanisms that underlie various inflammation paradoxes, metabolically healthy obesity, and increased inflammations after inflammatory cytokine blockades and deficiencies remain poorly determined. We performed an extensive -omics database mining, determined the expressions of 1367 innate immune regulators in 18 microarrays after deficiencies of 15 proinflammatory cytokines/regulators and eight microarray datasets of patients receiving Mab therapies, and made a set of significant findings: 1) proinflammatory cytokines/regulators suppress the expressions of innate immune regulators; 2) upregulations of innate immune regulators in the deficiencies of IFNγ/IFNγR1, IL-17A, STAT3 and miR155 are more than that after deficiencies of TNFα, IL-1β, IL-6, IL-18, STAT1, NF-kB, and miR221; 3) IFNγ, IFNγR and IL-17RA inhibit 10, 59 and 39 proinflammatory cytokine/regulator pathways, respectively; in contrast, TNFα, IL-6 and IL-18 each inhibits only four to five pathways; 4) The IFNγ-promoted and -suppressed innate immune regulators have four shared pathways; the IFNγR1-promoted and -suppressed innate immune regulators have 11 shared pathways; and the miR155-promoted and -suppressed innate immune regulators have 13 shared pathways, suggesting negative-feedback mechanisms in their conserved regulatory pathways for innate immune regulators; 5) Deficiencies of proinflammatory cytokine/regulator-suppressed, promoted programs share signaling pathways and increase the likelihood of developing 11 diseases including cardiovascular disease; 6) There are the shared innate immune regulators and pathways between deficiency of TNFα in mice and anti-TNF therapy in clinical patients; 7) Mechanistically, up-regulated reactive oxygen species regulators such as myeloperoxidase caused by suppression of proinflammatory cytokines/regulators can drive the upregulation of suppressed innate immune regulators. Our findings have provided novel insights on various inflammation paradoxes and proinflammatory cytokines regulation of innate immune regulators; and may re-shape new therapeutic strategies for cardiovascular disease and other inflammatory diseases.

End-stage renal disease is different from chronic kidney disease in upregulating ROS-modulated proinflammatory secretome in PBMCs - A novel multiple-hit model for disease progression

Background

The molecular mechanisms underlying chronic kidney disease (CKD) transition to end-stage renal disease (ESRD) and CKD acceleration of cardiovascular and other tissue inflammations remain poorly determined.

Methods

We conducted a comprehensive data analyses on 7 microarray datasets in peripheral blood mononuclear cells (PBMCs) from patients with CKD and ESRD from NCBI-GEO databases, where we examined the expressions of 2641 secretome genes (SG).

Results

1) 86.7% middle class (molecular weight >500 Daltons) uremic toxins (UTs) were encoded by SGs; 2) Upregulation of SGs in PBMCs in patients with ESRD (121 SGs) were significantly higher than that of CKD (44 SGs); 3) Transcriptomic analyses of PBMC secretome had advantages to identify more comprehensive secretome than conventional secretomic analyses; 4) ESRD-induced SGs had strong proinflammatory pathways; 5) Proinflammatory cytokines-based UTs such as IL-1β and IL-18 promoted ESRD modulation of SGs; 6) ESRD-upregulated co-stimulation receptors CD48 and CD58 increased secretomic upregulation in the PBMCs, which were magnified enormously in tissues; 7) M1-, and M2-macrophage polarization signals contributed to ESRD- and CKD-upregulated SGs; 8) ESRD- and CKD-upregulated SGs contained senescence-promoting regulators by upregulating proinflammatory IGFBP7 and downregulating anti-inflammatory TGF-β1 and telomere stabilizer SERPINE1/PAI-1; 9) ROS pathways played bigger roles in mediating ESRD-upregulated SGs (11.6%) than that in CKD-upregulated SGs (6.8%), and half of ESRD-upregulated SGs were ROS-independent.

Conclusions

Our analysis suggests novel secretomic upregulation in PBMCs of patients with CKD and ESRD, act synergistically with uremic toxins, to promote inflammation and potential disease progression. Our findings have provided novel insights on PBMC secretome upregulation to promote disease progression and may lead to the identification of new therapeutic targets for novel regimens for CKD, ESRD and their accelerated cardiovascular disease, other inflammations and cancers. (Total words: 279).

Common Injuries and Repair Mechanisms in the Endothelial Lining

Objective:

Endothelial cells (ECs) are important metabolic and endocrinal organs which play a significant role in regulating vascular function. Vascular ECs, located between the blood and vascular tissues, can not only complete the metabolism of blood and interstitial fluid but also synthesize and secrete a variety of biologically active substances to maintain vascular tension and keep a normal flow of blood and long-term patency. Therefore, this article presents a systematic review of common injuries and healing mechanisms for the vascular endothelium.

Data Sources:

An extensive search in the PubMed database was undertaken, focusing on research published after 2003 with keywords including endothelium, vascular, wounds and injuries, and wound healing.

Study Selection:

Several types of articles, including original studies and literature reviews, were identified and reviewed to summarize common injury and repair processes of the endothelial lining.

Results:

Endothelial injury is closely related to the development of multiple cardiovascular and cerebrovascular diseases. However, the mechanism of vascular endothelial injury is not fully understood. Numerous studies have shown that the mechanisms of EC injury mainly involve inflammatory reactions, physical stimulation, chemical poisons, concurrency of related diseases, and molecular changes. Endothelial progenitor cells play an important role during the process of endothelial repair after such injuries. What's more, a variety of restorative cells, changes in cytokines and molecules, chemical drugs, certain RNAs, regulation of blood pressure, and physical fitness training protect the endothelial lining by reducing the inducing factors, inhibiting inflammation and oxidative stress reactions, and delaying endothelial caducity.

Conclusions:

ECs are always in the process of being damaged. Several therapeutic targets and drugs were seeked to protect the endothelium and promote repair.

Induced pluripotent stem cell-derived endothelial progenitor cells attenuate ischemic acute kidney injury and cardiac dysfunction

Background

Renal ischemia–reperfusion (I/R) injury is a major cause of acute kidney injury (AKI), which is associated with high morbidity and mortality. AKI is a serious and costly medical condition. Effective therapy for AKI is an unmet clinical need, and molecular mechanisms underlying the interactions between an injured kidney and distant organs remain unclear. Therefore, novel therapeutic strategies should be developed.

Methods

We directed the differentiation of human induced pluripotent stem (iPS) cells into endothelial progenitor cells (iEPCs), which were then applied for treating mouse AKI. The mouse model of AKI was induced by I/R injury.

Results

We discovered that intravenously infused iEPCs were recruited to the injured kidney, expressed the mature endothelial cell marker CD31, and replaced injured endothelial cells. Moreover, infused iEPCs produced abundant proangiogenic proteins, which entered into circulation. In AKI mice, blood urea nitrogen and plasma creatinine levels increased 2 days after I/R injury and reduced after the infusion of iEPCs. Tubular injury, cell apoptosis, and peritubular capillary rarefaction in injured kidneys were attenuated accordingly. In the AKI mice, iEPC therapy also ameliorated apoptosis of cardiomyocytes and cardiac dysfunction, as indicated by echocardiography. The therapy also ameliorated an increase in serum brain natriuretic peptide. Regarding the relevant mechanisms, indoxyl sulfate and interleukin-1β synergistically induced apoptosis of cardiomyocytes. Systemic iEPC therapy downregulated the proapoptotic protein caspase-3 and upregulated the anti-apoptotic protein Bcl-2 in the hearts of the AKI mice, possibly through the reduction of indoxyl sulfate and interleukin-1β.

Conclusions

Therapy using human iPS cell-derived iEPCs provided a protective effect against ischemic AKI and remote cardiac dysfunction through the repair of endothelial cells and the attenuation of cardiomyocyte apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1092-x) contains supplementary material, which is available to authorized users.

SCAP knockdown in vascular smooth muscle cells alleviates atherosclerosis plaque formation via up-regulating autophagy in ApoE-/- mice

Sterol regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) is a cholesterol sensor that plays a critical role in regulating intracellular cholesterol levels, but the association between SCAP and foam cell formation in vascular smooth muscle cells (VSMCs) is poorly understood. Using tissue-specific SCAP knockdown in apolipoprotein E (ApoE)^-/- mice, we sought to search the mechanism through which SCAP signaling affects VSMC foam cell development. VSMC-specific SCAP knockdown mice were generated by Cre/LoxP-mediated gene targeting in ApoE^-/- mice. Breeding SCAP^flox/flox mice with SM22α-Cre mice resulted in no viable offspring with the homozygote SM22-Cre: SCAP^flox/flox genotype due to embryonic lethality. We found that the heterozygote SM22α-Cre:SCAP^flox/+:ApoE^-/- mice fed a Western diet for 12 wk had significantly fewer atherosclerotic plaques in their aortas than the control mice due to reduced cholesterol uptake and synthesis. Furthermore, we found that autophagy in VSMCs was increased in SM22α-Cre:SCAP^flox/+:ApoE^-/- mice. Similarly, in vitro, SCAP knockdown in human coronary artery VSMCs by RNA interference reduced lipid accumulation and increased autophagy under LDL cholesterol loading. SCAP knockdown in VSMCs reduced oxidative stress and increased AMPK phosphorylation, which contributed to the up-regulation of autophagy in vivo and in vitro. VSMC-specific SCAP knockdown decreased the lipid accumulation and intracellular oxidative stress, increased excessive lipid clearance by enhancing lipid autophagy mediated by the reactive oxygen species/AMPK pathway in VSMCs, and consequently alleviated atherosclerosis plaque formation.-Li, D., Chen, A., Lan, T., Zou, Y., Zhao, L., Yang, P., Qu, H., Wei, L., Varghese, Z., Moorhead, J. F., Chen, Y., Ruan, X. Z. SCAP knockdown in vascular smooth muscle cells alleviates atherosclerosis plaque formation via up-regulating autophagy in ApoE^-/- mice.

Identification of homocysteine-suppressive mitochondrial ETC complex genes and tissue expression profile - Novel hypothesis establishment

Hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular disease (CVD) which has been implicated in matochondrial (Mt) function impairment. In this study, we characterized Hcy metabolism in mouse tissues by using LC-ESI-MS/MS analysis, established tissue expression profiles for 84 nuclear-encoded Mt electron transport chain complex (nMt-ETC-Com) genes in 20 human and 19 mouse tissues by database mining, and modeled the effect of HHcy on Mt-ETC function. Hcy levels were high in mouse kidney/lung/spleen/liver (24-14 nmol/g tissue) but low in brain/heart (~5 nmol/g). S-adenosylhomocysteine (SAH) levels were high in the liver/kidney (59-33 nmol/g), moderate in lung/heart/brain (7-4 nmol/g) and low in spleen (1 nmol/g). S-adenosylmethionine (SAM) was comparable in all tissues (42-18 nmol/g). SAM/SAH ratio was as high as 25.6 in the spleen but much lower in the heart/lung/brain/kidney/liver (7-0.6). The nMt-ETC-Com genes were highly expressed in muscle/pituitary gland/heart/BM in humans and in lymph node/heart/pancreas/brain in mice. We identified 15 Hcy-suppressive nMt-ETC-Com genes whose mRNA levels were negatively correlated with tissue Hcy levels, including 11 complex-I, one complex-IV and two complex-V genes. Among the 11 Hcy-suppressive complex-I genes, 4 are complex-I core subunits. Based on the pattern of tissue expression of these genes, we classified tissues into three tiers (high/mid/low-Hcy responsive), and defined heart/eye/pancreas/brain/kidney/liver/testis/embryonic tissues as tier 1 (high-Hcy responsive) tissues in both human and mice. Furthermore, through extensive literature mining, we found that most of the Hcy-suppressive nMt-ETC-Com genes were suppressed in HHcy conditions and related with Mt complex assembly/activity impairment in human disease and experimental models. We hypothesize that HHcy inhibits Mt complex I gene expression leading to Mt dysfunction.

Pioglitazone restores the homocysteine‑impaired function of endothelial progenitor cells via the inhibition of the protein kinase C/NADPH oxidase pathway

Homocysteine (Hcy) has been shown to impair the migratory and adhesive activity of endothelial progenitor cells (EPCs). As a peroxisome proliferator-activated receptor γ agonist, pioglitazone (PIO) has been predicted to regulate angiogenesis, and cell adhesion, migration and survival. The aim of the present study was to determine whether PIO could inhibit Hcy-induced EPC dysfunctions such as impairments of cell migration and adhesion. EPC migration and adhesion were assayed using 8.0-µm pore size Transwell membranes and fibronectin-coated culture dishes, respectively. Hcy at a concentration of 200 µM was observed to markedly impair cell migration and adhesiveness, and PIO at a concentration of 10 µM attenuated the Hcy-mediated inhibition of EPC migration and adhesion. The mechanism of these effects may be through the inhibition of protein kinase C (PKC) and reactive oxygen species production. The expression levels of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits, NADPH oxidase 2 (Nox2) and p67phox, were upregulated by Hcy, with a peak in levels following treatment with a concentration of 200 µM. PIO downregulated the expression levels of Nox2 and p67phox via the PKC signaling pathway. Furthermore, the mechanism of PIO associated with downregulating the p67phox and Nox2 subunits of NADPH oxidase was verified. Thus, PKC and NADPH oxidase may serve a major role in the protective effects of PIO in EPCs under conditions of high Hcy concentrations.

Circulating progenitor cells and their interaction with platelets in patients with an acute coronary syndrome

CD34⁺ cells expressing KDR (CD34⁺/KDR⁺) represent a small proportion of circulating progenitor cells that have the capacity to interact with platelets and to differentiate into mature endothelial cells, thus contributing to vascular homeostasis and regeneration as well as to re-endothelialization. We investigated the levels of CD34⁺ and CD34⁺/KDR⁺ progenitor cells as well as their interaction with platelets in acute coronary syndrome (ACS) patients before the initiation (baseline) of their treatment with a P2Y₁₂ receptor antagonist, and at 5-days post-treatment (follow-up). Sixty-seven consecutive ACS patients and thirty healthy subjects (controls) participated in the study. On admission, all patients received 325 mg aspirin, followed by 100 mg/day and then were loaded either with 600 mg clopidogrel or 180 mg ticagrelor, followed by 75 mg/day (n = 36) or 90 mg × 2/day (n = 31), respectively. The levels of circulating CD34⁺ and CD34⁺/KDR⁺ progenitor cells, as well as their interaction with platelets, were determined by flow cytometry, before and after activation with ADP, in vitro. The circulating levels of CD34⁺ and CD34⁺/KDR⁺ cells in both patient groups at baseline were lower compared with controls while they were significantly increased at 5-days of follow-up in both groups, this increase being more pronounced in the ticagrelor group. The platelet/CD34⁺ (CD61⁺/CD34⁺) conjugates were higher at baseline and reduced at follow-up while the platelet/KDR⁺ (CD61⁺/KDR⁺) conjugates were lower at baseline and increased at follow-up, both changes being more pronounced in the ticagrelor group. ADP activation of control samples significantly increased the KDR expression by CD34⁺ cells and the CD61⁺/KDR⁺ conjugates, these parameters being unaffected in patients at baseline but increased at follow-up. Short-term dual antiplatelet therapy in ACS patients restores the low platelet/KDR⁺ conjugates and CD34⁺ cell levels and improves the low membrane expression levels of KDR in these cells, an effect being more pronounced in ticagrelor-treated patients. This may represent a pleiotropic effect of antiplatelet therapy towards vascular endothelial regeneration.

Endothelial angiogenesis is directed by RUNX1T1-regulated VEGFA, BMP4 and TGF-β2 expression

Tissue angiogenesis is intimately regulated during embryogenesis and postnatal development. Defected angiogenesis contributes to aberrant development and is the main complication associated with ischemia-related diseases. We previously identified the increased expression of RUNX1T1 in umbilical cord blood-derived endothelial colony-forming cells (ECFCs) by gene expression microarray. However, the biological relevance of RUNX1T1 in endothelial lineage is not defined clearly. Here, we demonstrate RUNX1T1 regulates the survival, motility and tube forming capability of ECFCs and EA.hy926 endothelial cells by loss-and gain-of function assays, respectively. Second, embryonic vasculatures and quantity of bone marrow-derived angiogenic progenitors are found to be reduced in the established Runx1t1 heterozygous knockout mice. Finally, a central RUNX1T1-regulated signature is uncovered and VEGFA, BMP4 as well as TGF-β2 are demonstrated to mediate RUNX1T1-orchested angiogenic activities. Taken together, our results reveal that RUNX1T1 serves as a common angiogenic driver for vaculogenesis and functionality of endothelial lineage cells. Therefore, the discovery and application of pharmaceutical activators for RUNX1T1 will improve therapeutic efficacy toward ischemia by promoting neovascularization.

Toll-like receptor 4 mediates vascular remodeling in hyperhomocysteinemia

Although hyperhomocysteinemia (HHcy) is known to promote downstream pro-inflammatory cytokine elevation, the precise mechanism is still unknown. One of the possible receptors that could have significant attention in the field of hypertension is toll-like receptor 4 (TLR-4). TLR-4 is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. Its mutation can attenuate the effects of HHcy-mediated vascular inflammation and mitochondria- dependent cell death that suppresses hypertension. In this review, we observed that HHcy induces vascular remodeling through immunological adaptation, promoting inflammatory cytokine up-regulation (IL-1β, IL-6, TNF-α) and initiation of mitochondrial dysfunction leading to cell death and chronic vascular inflammation. The literature suggests that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death inducing peripheral vascular remodeling. In the previous studies, we have characterized the role of TLR-4 mutation in attenuating vascular remodeling in hyperhomocysteinemia. This review includes, but is not limited to, the physiological synergistic aspects of the downstream elevation of cytokines found within the vascular inflammatory cascade. These events subsequently induce mitochondrial dysfunction defined by excessive mitochondrial fission and mitochondrial apoptosis contributing to vascular remodeling followed by hypertension.

Toll-like receptor 4 mutation suppresses hyperhomocysteinemia-induced hypertension

Hyperhomocysteinemia (HHcy) has been observed to promote hypertension, but the mechanisms are unclear. Toll-like receptor 4 (TLR-4) is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. TLR-4 activation has been known to promote inflammation that has been associated with the pathogenesis of hypertension. In this study we hypothesize that HHcy induces hypertension by TLR-4 activation, which promotes inflammatory cytokine (IL-1β, IL-6, and TNF-α) upregulation and initiation of mitochondria-dependent apoptosis, leading to cell death and chronic vascular inflammation. To test this hypothesis, we used C57BL/6J (WT) mice, cystathionine β-synthase (CBS)-deficient (CBS^+/-) mice with genetic mild HHcy, C3H/HeJ (C3H) mice with TLR-4 mutation, and mice with combined genetic HHcy and TLR-4 mutation (CBS^+/-/C3H). Ultrasonography of the superior mesenteric artery (SMA) detected an increase in wall-to-lumen ratio, resistive index (RI), and pulsatility index (PI). Tail cuff blood pressure (BP) measurement revealed elevated BP in CBS^+/- mice. RI, PI, and wall-to-lumen ratio of the SMA in CBS^+/-/C3H mice were similar to the control group, and BP was significantly alleviated. TLR-4, IL-1β, IL-6, and TNF-α expression were upregulated in the SMA of CBS^+/- mice and reduced in the SMA of CBS^+/-/C3H mice. Molecules involved in the mitochondria-mediated cell death pathway (BAX, caspase-9, and caspase-3) were upregulated in CBS^+/- mice and attenuated in CBS^+/-/C3H mice. We conclude that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death, inducing hypertension. TLR-4 mutation attenuates vascular inflammation and cell death, which suppress hypertension.

Caspase-1 Inflammasome Activation Mediates Homocysteine-Induced Pyrop-Apoptosis in Endothelial Cells

RATIONALE

Endothelial injury is an initial mechanism mediating cardiovascular disease.

OBJECTIVE

Here, we investigated the effect of hyperhomocysteinemia on programed cell death in endothelial cells (EC).

METHODS AND RESULTS

We established a novel flow-cytometric gating method to define pyrotosis (Annexin V(-)/Propidium iodide(+)). In cultured human EC, we found that: (1) homocysteine and lipopolysaccharide individually and synergistically induced inflammatory pyroptotic and noninflammatory apoptotic cell death; (2) homocysteine/lipopolysaccharide induced caspase-1 activation before caspase-8, caspase-9, and caspase-3 activations; (3) caspase-1/caspase-3 inhibitors rescued homocysteine/lipopolysaccharide-induced pyroptosis/apoptosis, but caspase-8/caspase-9 inhibitors had differential rescue effect; (4) homocysteine/lipopolysaccharide-induced nucleotide-binding oligomerization domain, and leucine-rich repeat and pyrin domain containing protein 3 (NLRP3) protein caused NLRP3-containing inflammasome assembly, caspase-1 activation, and interleukin (IL)-1β cleavage/activation; (5) homocysteine/lipopolysaccharide elevated intracellular reactive oxygen species, (6) intracellular oxidative gradient determined cell death destiny as intermediate intracellular reactive oxygen species levels are associated with pyroptosis, whereas high reactive oxygen species corresponded to apoptosis; (7) homocysteine/lipopolysaccharide induced mitochondrial membrane potential collapse and cytochrome-c release, and increased B-cell lymphoma 2-associated X protein/B-cell lymphoma 2 ratio which were attenuated by antioxidants and caspase-1 inhibitor; and (8) antioxidants extracellular superoxide dismutase and catalase prevented homocysteine/lipopolysaccharide -induced caspase-1 activation, mitochondrial dysfunction, and pyroptosis/apoptosis. In cystathionine β-synthase-deficient (Cbs(-/-)) mice, severe hyperhomocysteinemia-induced caspase-1 activation in isolated lung EC and caspase-1 expression in aortic endothelium, and elevated aortic caspase-1, caspase-9 protein/activity and B-cell lymphoma 2-associated X protein/B-cell lymphoma 2 ratio in Cbs(-/-) aorta and human umbilical vein endothelial cells. Finally, homocysteine-induced DNA fragmentation was reversed in caspase-1(-/-) EC. Hyperhomocysteinemia-induced aortic endothelial dysfunction was rescued in caspase-1(-/-) and NLRP3(-/-) mice.

CONCLUSIONS

Hyperhomocysteinemia preferentially induces EC pyroptosis via caspase-1-dependent inflammasome activation leading to endothelial dysfunction. We termed caspase-1 responsive pyroptosis and apoptosis as pyrop-apoptosis.

Challenges and opportunities for stem cell therapy in patients with chronic kidney disease

Chronic kidney disease (CKD) is a global health care burden affecting billions of individuals worldwide. The kidney has limited regenerative capacity from chronic insults, and for the most common causes of CKD, no effective treatment exists to prevent progression to end-stage kidney failure. Therefore, novel interventions, such as regenerative cell-based therapies, need to be developed for CKD. Given the risk of allosensitization, autologous transplantation of cells to boost regenerative potential is preferred. Therefore, verification of cell function and vitality in CKD patients is imperative. Two cell types have been most commonly applied in regenerative medicine. Endothelial progenitor cells contribute to neovasculogenesis primarily through paracrine angiogenic activity and partly by differentiation into mature endothelial cells in situ. Mesenchymal stem cells also exert paracrine effects, including proangiogenic, anti-inflammatory, and antifibrotic activity. However, in CKD, multiple factors may contribute to reduced cell function, including older age, coexisting cardiovascular disease, diabetes, chronic inflammatory states, and uremia, which may limit the effectiveness of an autologous cell-based therapy approach. This Review highlights current knowledge on stem and progenitor cell function and vitality, aspects of the uremic milieu that may serve as a barrier to therapy, and novel methods to improve stem cell function for potential transplantation.

Metabolic Diseases Downregulate the Majority of Histone Modification Enzymes, Making a Few Upregulated Enzymes Novel Therapeutic Targets--"Sand Out and Gold Stays"

To determine whether the expression of histone modification enzymes is regulated in physiological and pathological conditions, we took an experimental database mining approach pioneered in our labs to determine a panoramic expression profile of 164 enzymes in 19 human and 17 murine tissues. We have made the following significant findings: (1) Histone enzymes are differentially expressed in cardiovascular, immune, and other tissues; (2) our new pyramid model showed that heart and T cells are among a few tissues in which histone acetylation/deacetylation, and histone methylation/demethylation are in the highest varieties; and (3) histone enzymes are more downregulated than upregulated in metabolic diseases and regulatory T cell (Treg) polarization/ differentiation, but not in tumors. These results have demonstrated a new working model of "Sand out and Gold stays," where more downregulation than upregulation of histone enzymes in metabolic diseases makes a few upregulated enzymes the potential novel therapeutic targets in metabolic diseases and Treg activity.