A Perspective on How Fibrinaloid Microclots and Platelet Pathology May be Applied in Clinical Investigations

Microscopy imaging has enabled us to establish the presence of fibrin(ogen) amyloid (fibrinaloid) microclots in a range of chronic, inflammatory diseases. Microclots may also be induced by a variety of purified substances, often at very low concentrations. These molecules include bacterial inflammagens, serum amyloid A, and the S1 spike protein of severe acute respiratory syndrome coronavirus 2. Here, we explore which of the properties of these microclots might be used to contribute to differential clinical diagnoses and prognoses of the various diseases with which they may be associated. Such properties include distributions in their size and number before and after the addition of exogenous thrombin, their spectral properties, the diameter of the fibers of which they are made, their resistance to proteolysis by various proteases, their cross-seeding ability, and the concentration dependence of their ability to bind small molecules including fluorogenic amyloid stains. Measuring these microclot parameters, together with microscopy imaging itself, along with methodologies like proteomics and imaging flow cytometry, as well as more conventional assays such as those for cytokines, might open up the possibility of a much finer use of these microclot properties in generative methods for a future where personalized medicine will be standard procedures in all clotting pathology disease diagnoses.

Elucidation of the Role of TRPV1, VEGF-A, TXA2, Redox Homeostasis, and Inflammatory Cascades in Protection against Cold Injuries by Herbosomal-Loaded PEG-Poloxamer Topical Formulation

High-altitude regions, cold deserts, permafrost regions, and the polar region have some of the severest cold conditions on earth and pose immense perils of cold injuries to exposed individuals. Accidental and unintended exposures to severe cold, either unintentionally or due to occupational risks, can greatly increase the risk of serious conditions including hypothermia, trench foot, and cold injuries like frostbite. Cold-induced vasoconstriction and intracellular/intravascular ice crystal formation lead to hypoxic conditions at the cellular level. The condition is exacerbated in individuals having inadequate and proper covering and layering, particularly when large area of the body are exposed to extremely cold environments. There is a paucity of preventive and therapeutic pharmacological modalities that have been explored for managing and treating cold injuries. Given this, an efficient modality that can potentiate the healing of frostbite was investigated by studying various complex pathophysiological changes that occur during severe cold injuries. In the current research, we report the effectiveness and healing properties of a standardized formulation, i.e., a herbosomal-loaded PEG-poloxamer topical formulation (n-HPTF), on frostbite. The intricate mechanistic pathways modulated by the novel formulation have been elucidated by studying the pathophysiological sequelae that occur following severe cold exposures leading to frostbite. The results indicate that n-HPTF ameliorates the outcome of frostbite, as it activates positive sensory nerves widely distributed in the epidermis transient receptor potential vanilloid 1 (TRPV1), significantly (p < 0.05) upregulates cytokeratin-14, promotes angiogenesis (VEGF-A), prominently represses the expression of thromboxane formation (TXA2), and significantly (p < 0.05) restores levels of enzymatic (glutathione reductase, superoxide dismutase, and catalase) and nonenzymatic antioxidants (glutathione). Additionally, n-HPTF attenuates oxidative stress and the expression of inflammatory proteins PGF-2α, NFκB-p65, TNF-α, IL-6, IL-1β, malondialdehyde (MDA), advanced oxidative protein products (AOPP), and protein carbonylation (PCO). Masson's Trichrome staining showed that n-HPTF stimulates cellular proliferation, and increases collagen fiber deposition, which significantly (p < 0.05) promotes the healing of frostbitten tissue, as compared to control. We conclude that protection against severe cold injuries by n-HPTF is mediated via modulation of pathways involving TRPV1, VEGF-A, TXA2, redox homeostasis, and inflammatory cascades. The study is likely to have widespread implications for the prophylaxis and management of moderate-to-severe frostbite conditions.

Mechanism of action of Taohong Siwu decoction in the alleviation of primary dysmenorrhea

Background

As one of the most common gynecological disorders, PD significantly impacts the quality of life for women. TSD, a well-known traditional Chinese medical prescription, has gained popularity for its use in treating gynecological cold coagulation and blood stasis syndromes such as PD. However, the lack of comprehensive data hinders our understanding of its molecular mechanism.

Purpose

The objective of the present study is to investigate the therapeutic effects of TSD on PD and elucidate its plausible mechanism.

Methods

HPLC was employed to confirm the presence of the principal metabolites of TSD. The rat model of PD was induced by OT exposure following IWM and EB pretreatment, and subsequently treated with TSD via gastric gavage. The effects and potential mechanisms of TSD on PD rats were explored, encompassing general behavior, morphological alterations in the uterus and ovaries, biochemical indicators in the uterus and serum, and levels of proteins related to the PI3K/AKT signaling pathway.

Results

Gallic acid, hydroxysafflower yellow A, albiflorin, paeoniflorin, and ferulic acid were determined to be the primary active metabolites of TSD. The pharmacological studies yielded results indicating the successful establishment of the PD model in rats. Additionally, TSD demonstrated its ability to protect PD rats by ameliorating general behavior, mitigating pathological damage to uterine and ovarian tissues, and modulating the expression levels of correlated factors (PGE2, PGF2α, Ca2+, TXB2, IL-6, TNF-α, NO, and COX-2) as well as p-PI3K/PI3K and p-AKT/AKT proteins.

Conclusion

TSD exhibited protective effects against PD in rats through its interaction with multiple targets including P13K/AKT signaling pathway, indicating that TSD holds therapeutic potential for PD treatment and providing evidence supporting the rational utilization of TSD.

Thromboxane prostanoid signaling in macrophages attenuates lymphedema and facilitates lymphangiogenesis in mice : TP signaling and lymphangiogenesis

BACKGROUND

Accumulating evidence suggests that prostaglandin E2, an arachidonic acid (AA) metabolite, enhances lymphangiogenesis in response to inflammation. However, thromboxane A2 (TXA2), another AA metabolite, is not well known. Thus, this study aimed to determine the role of thromboxane prostanoid (TP) signaling in lymphangiogenesis in secondary lymphedema.

METHODS AND RESULTS

Lymphedema was induced by the ablation of lymphatic vessels in mouse tails. Compared with wild-type mice, tail lymphedema in Tp-deficient mice was enhanced, which was associated with suppressed lymphangiogenesis as indicated by decreased lymphatic vessel area and pro-lymphangiogenesis-stimulating factors. Numerous macrophages were found in the tail tissues of Tp-deficient mice. Furthermore, the deletion of TP in macrophages increased tail edema and decreased lymphangiogenesis and pro-lymphangiogenic cytokines, which was accompanied by increased numbers of macrophages and gene expression related to a pro-inflammatory macrophage phenotype in tail tissues. In vivo microscopic studies revealed fluorescent dye leakage in the lymphatic vessels in the wounded tissues.

CONCLUSIONS

The results suggest that TP signaling in macrophages promotes lymphangiogenesis and prevents tail lymphedema. TP signaling may be a therapeutic target for improving lymphedema-related symptoms by enhancing lymphangiogenesis.

The microsomal prostaglandin E synthase-1/prostaglandin E2 axis induces recovery from ischaemia via recruitment of regulatory T cells

AIMS

Microsomal prostaglandin E synthase-1 (mPGES-1)/prostaglandin E2 (PGE2) induces angiogenesis through the prostaglandin E2 receptor (EP1-4). Among immune cells, regulatory T cells (Tregs), which inhibit immune responses, have been implicated in angiogenesis, and PGE2 is known to modulate the function and differentiation of Tregs. We hypothesized that mPGES-1/PGE2-EP signalling could contribute to recovery from ischaemic conditions by promoting the accumulation of Tregs.

METHODS AND RESULTS

Wild-type (WT), mPGES-1-deficient (mPges-1-/-), and EP4 receptor-deficient (Ep4-/-) male mice, 6-8 weeks old, were used. Hindlimb ischaemia was induced by femoral artery ligation. Recovery from ischaemia was suppressed in mPges-1-/- mice and compared with WT mice. The number of accumulated forkhead box protein P3 (FoxP3)+ cells in ischaemic muscle tissue was decreased in mPges-1-/- mice compared with that in WT mice. Expression levels of transforming growth factor-β (TGF-β) and stromal cell derived factor-1 (SDF-1) in ischaemic tissue were also suppressed in mPges-1-/- mice. The number of accumulated FoxP3+ cells and blood flow recovery were suppressed when Tregs were depleted by injecting antibody against folate receptor 4 in WT mice but not in mPges-1-/- mice. Recovery from ischaemia was significantly suppressed in Ep4-/- mice compared with that in WT mice. Furthermore, mRNA levels of Foxp3 and Tgf-β were suppressed in Ep4-/- mice. Moreover, the number of accumulated FoxP3+ cells in ischaemic tissue was diminished in Ep4-/- mice compared with that in Ep4+/+ mice.

CONCLUSION

These findings suggested that mPGES-1/PGE2 induced neovascularization from ischaemia via EP4 by promoting the accumulation of Tregs. Highly selective EP4 agonists could be useful for the treatment of peripheral artery disease.

A biologically active lipid, thromboxane, as a regulator of angiogenesis and lymphangiogenesis

Thromboxane (TX) and prostaglandins are metabolites of arachidonic acid, a twenty-carbon unsaturated fatty acid, and have a variety of actions that are exerted via specific receptors. Angiogenesis is defined as the formation of new blood vessels from pre-existing vascular beds and is a critical component of pathological conditions, including inflammation and cancer. Lymphatic vessels play crucial roles in the regulation of interstitial fluid, immune surveillance, and the absorption of dietary fat from the intestine; and they are also involved in the pathogenesis of various diseases. Similar to angiogenesis, lymphangiogenesis, the formation of new lymphatic vessels, is a critical component of pathological conditions. The TP-dependent accumulation of platelets in microvessels has been reported to enhance angiogenesis under pathological conditions. Although the roles of some growth factors and cytokines in angiogenesis and lymphangiogenesis have been well characterized, accumulating evidence suggests that TX induces the production of proangiogenic and prolymphangiogenic factors through the activation of adenylate cyclase, and upregulates angiogenesis and lymphangiogenesis under disease conditions. In this review, we discuss the role of TX as a regulator of angiogenesis and lymphangiogenesis, and its emerging importance as a therapeutic target.

Thromboxane A2 receptor activation via Gα13-RhoA/C-ROCK-LIMK2-dependent signal transduction inhibits angiogenic sprouting of human endothelial cells

We could previously show that thromboxane A₂ receptor (TP) activation inhibits the angiogenic capacity of human endothelial cells, but the underlying mechanisms remained unclear. Therefore, the aim of this study was to elucidate TP signal transduction pathways relevant to angiogenic sprouting of human endothelial cells. To clarify this matter, we used RNAi-mediated gene silencing as well as pharmacological inhibition of potential TP downstream targets in human umbilical vein endothelial cells (HUVEC) and VEGF-induced angiogenic sprouting of HUVEC spheroids in vitro as a functional read-out. In this experimental set-up, the TP agonist U-46619 completely blocked VEGF-induced angiogenic sprouting of HUVEC spheroids. Moreover, in live-cell analyses TP activation induced endothelial cell contraction, sprout retraction as well as endothelial cell tension and focal adhesion dysregulation of HUVEC. These effects were reversed by pharmacological TP inhibition or TP knockdown. Moreover, we identified a TP-G_α13-RhoA/C-ROCK-LIMK2-dependent signal transduction pathway to be relevant for U-46619-induced inhibition of VEGF-mediated HUVEC sprouting. In line with these results, U-46619-mediated TP activation potently induced RhoA and RhoC activity in live HUVEC as measured by FRET biosensors. Interestingly, pharmacological inhibition of ROCK and LIMK2 also normalized U-46619-induced endothelial cell tension and focal adhesion dysregulation of HUVEC. In summary, our work reveals mechanisms by which the TP may disturb angiogenic endothelial function in disease states associated with sustained endothelial TP activation.

A Thromboxane A2 Receptor-Driven COX-2-Dependent Feedback Loop That Affects Endothelial Homeostasis and Angiogenesis

BACKGROUND

TP (thromboxane A₂ receptor) plays an eminent role in the pathophysiology of endothelial dysfunction and cardiovascular disease. Moreover, its expression is reported to increase in the intimal layer of blood vessels of cardiovascular high-risk individuals. Yet it is unknown, whether TP upregulation per se has the potential to affect the homeostasis of the vascular endothelium.

METHODS

We combined global transcriptome analysis, lipid mediator profiling, functional cell analyses, and in vivo angiogenesis assays to study the effects of endothelial TP overexpression or knockdown/knockout on the angiogenic capacity of endothelial cells in vitro and in vivo.

RESULTS

Here we report that endothelial TP expression induces COX-2 (cyclooxygenase-2) in a G_i/o- and G_q/11-dependent manner, thereby promoting its own activation via the auto/paracrine release of TP agonists, such as PGH₂ (prostaglandin H₂) or prostaglandin F₂ but not TxA₂ (thromboxane A₂). TP overexpression induces endothelial cell tension and aberrant cell morphology, affects focal adhesion dynamics, and inhibits the angiogenic capacity of human endothelial cells in vitro and in vivo, whereas TP knockdown or endothelial-specific TP knockout exerts opposing effects. Consequently, this TP-dependent feedback loop is disrupted by pharmacological TP or COX-2 inhibition and by genetic reconstitution of PGH₂-metabolizing prostacyclin synthase even in the absence of functional prostacyclin receptor expression.

CONCLUSIONS

Our work uncovers a TP-driven COX-2-dependent feedback loop and important effector mechanisms that directly link TP upregulation to angiostatic TP signaling in endothelial cells. By these previously unrecognized mechanisms, pathological endothelial upregulation of the TP could directly foster endothelial dysfunction, microvascular rarefaction, and systemic hypertension even in the absence of exogenous sources of TP agonists.

The role of thromboxane prostanoid receptor signaling in gastric ulcer healing

The process of gastric ulcer healing includes cell migration, proliferation, angiogenesis and re-epithelialization. Platelets contain angiogenesis stimulating factors that induce angiogenesis. Thromboxane A2 (TXA2 ) not only induces platelet activity but also angiogenesis. This study investigated the role of TXA2 in gastric ulcer healing using TXA2 receptor knockout (TPKO) mice. Gastric ulcer healing was suppressed by treatment with the TXA2 synthase inhibitor OKY-046 and the TXA2 receptor antagonist S-1452 compared with vehicle-treated mice. TPKO showed delayed gastric ulcer healing compared with wild-type mice (WT). The number of microvessels and CD31 expression were lower in TPKO than in WT mice, and TPKO suppressed the expression of transforming growth factor beta (TGF-β) and vascular endothelial growth factor A (VEGF-A) in areas around gastric ulcers. Immunofluorescence assays showed that TGF-β and VEGF-A co-localized with platelets. Gastric ulcer healing was significantly reduced in WT mice transplanted with TPKO compared with WT bone marrow. These results suggested that TP signalling on platelets facilitates gastric ulcer healing through TGF-β and VEGF-A.

Biologically active lipids in the regulation of lymphangiogenesis in disease states

Lymphatic vessels have crucial roles in the regulation of interstitial fluids, immune surveillance, and the absorption of dietary fat in the intestine. Lymphatic function is also closely related to the pathogenesis of various disease states such as inflammation, lymphedema, endometriosis, liver dysfunction, and tumor metastasis. Lymphangiogenesis, the formation of new lymphatic vessels from pre-existing lymphatic vessels, is a critical determinant in the above conditions. Although the effect of growth factors on lymphangiogenesis is well-characterized, and biologically active lipids are known to affect smooth muscle contractility and vasoaction, there is accumulating evidence that biologically active lipids are also important inducers of growth factors and cytokines that regulate lymphangiogenesis. This review discusses recent advances in our understanding of biologically active lipids, including arachidonic acid metabolites, sphingosine 1-phosphate, and lysophosphatidic acid, as regulators of lymphangiogenesis, and the emerging importance of the lymphangiogenesis as a therapeutic target.

Bioactive constituents and the molecular mechanism of Curcumae Rhizoma in the treatment of primary dysmenorrhea based on network pharmacology and molecular docking

BACKGROUND

Curcumae Rhizoma (CR) has a clinical efficacy in activating blood circulation to dissipate blood stasis and has been used for the clinical treatment of qi stagnation and blood stasis (QSBS) primary dysmenorrhea for many years. However, its molecular mechanism is unknown.

OBJECTIVE

The present study aimed to demonstrate the multicomponent, multitarget and multipathway regulatory molecular mechanisms of CR in the treatment of QSBS primary dysmenorrhea.

METHODS

Observations of pathological changes in uterine tissues and biochemical assays were used to confirm that a rat model was successfully established and that CR was effective in the treatment of QSBS primary dysmenorrhea. The main active components of CR in rat plasma were identified and screened by ultra-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UPLC-Q/TOF-MS). The component-target-disease network and protein-protein interaction (PPI) network of CR were constructed by a network pharmacology approach. Then, we performed Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Molecular docking was adopted to verify the interactions between the core components and targets of CR to confirm the accuracy of the network pharmacology prediction results. Furthermore, we evaluated the bioactive constituents of CR and molecular mechanism of by which CR promote blood circulation and remove blood stasis via platelet tests in vivo and in vitro and Western blot analysis.

RESULTS

The results of HE staining and biochemical assays of PGF2α, TXB2 and Ca2+ showed that CR was effective in the treatment of QSBS primary dysmenorrhea. A total of 36 active components were identified in CR, and 329 common targets were obtained and used to construct the networks. Of these, 14 core components and 10 core targets of CR in the treatment of primary dysmenorrhea were identified. The GO and KEGG enrichment analyses revealed that the common targets were involved in multiple signaling pathways, including the calcium, cAMP, MAPK, and PI3K-Akt signaling pathways, as well as platelet activation, which is closely related to platelet aggregation. The molecular docking results showed that the 14 core components and 10 core targets could bind spontaneously. Two core targets (MAPK1 and CCR5) and 7 core components (Isoprocurcumenol, Curcumadione, Epiprocurcumenol, (+)-Curdione, Neocurdione, Procurcumenol, and 13-Hydroxygermacrone) were closely related to CR in the treatment of primary dysmenorrhea. Furthermore, the in vivo platelet test showed that CR clearly inhibited platelet aggregation. Five core components ((+)-Curdione, Neocurdione, Isoprocurcumenol, Curcumadione and Procurcumenol) obviously inhibited platelet aggregation in vitro. In addition, based on the relationships among the signaling pathways, we confirmed that CR can effectively inhibit the expression of MAPK and PI3K-Akt signaling pathway-related proteins and decrease the protein expression levels of ERK, JNK, MAPK, PI3K, AKT and CCR5, thereby inhibiting platelet aggregation.

CONCLUSION

This study demonstrated the bioactive constituents and mechanisms of CR in promoting blood circulation and removing blood stasis and its multicomponent, multitarget and multipathway treatment characteristics in primary dysmenorrhea. The results provide theoretical evidence for the development and utilization of CR.

Roles of Thromboxane Receptor Signaling in Enhancement of Lipopolysaccharide-Induced Lymphangiogenesis and Lymphatic Drainage Function in Diaphragm

[Figure: see text].

Microsomal prostaglandin E synthase-1 promotes lung metastasis via SDF-1/CXCR4-mediated recruitment of CD11b+Gr1+MDSCs from bone marrow

BACKGROUND

Accumulation of myeloid-derived suppressor cells (MDSCs) to tumors is related to cancer prognosis. We investigated the contribution of host stromal microsomal prostaglandin E synthase-1 (mPGES-1) to the accumulation of MDSCs in metastasized lungs of prostate cancer in mice.

MATERIAL AND METHODS

Eight-week-old male C57Bl/6 wild type (WT) mice and mPGES-1 knock out mice (mPGES-1KO) were injected with RM9 murine prostate cancer cell line (5 × 10⁶ cells/mL). Lung metastasis was evaluated by the number of colonies, the weight of the lung, and the number of MDSCs (CD11b⁺Gr1⁺ cells) in the lung.

RESULTS

Intravenous injections of RM9, a murine prostate cancer cell line to WT mice revealed that lung metastasis and accumulation of MDCSs were suppressed with treatments with a Gr1 antibody, a COX-2 inhibitor, and an mPGES-1 inhibitor. Lung metastasis and accumulation of CD11b⁺Gr1⁺MDSCs were suppressed in mPGES-1KO mice. The mRNA level of stromal cell-derived factor-1 (SDF-1) in the lung and the number of accumulated SDF-1-expressing CD11b⁺Gr1⁺ MDSCs were elevated at an early stage in lung metastasis of C-X-C chemokine receptor type 4 (CXCR4)-expressing RM9 in an mPGES-1-dependent manner. The number of CXCR4-expressing CD11b⁺Gr1⁺MDSCs in WT mice was higher than that in mPGES-1KO mice. RM9 lung metastasis and accumulation of CD11b⁺Gr1⁺MDSCs were suppressed by CXCR4 antibody in WT mice but not in mPGES-1KO. WT mice transplanted with mPGES-1 KO bone marrow (BM) showed a significant reduction in lung metastasis and accumulation of CD11b⁺Gr1⁺MDSCs.

CONCLUSION

These results suggest that mPGES-1 enhances tumor metastasis by inducing accumulation of BM-derived MDSCs. Selective mPGES-1 inhibitors might, therefore, represent valuable therapeutic tools for the suppression of tumor metastasis.

Platelets as Potent Signaling Entities in Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a multifactorial disease with a dysregulated circulating inflammatory molecule tendency. T2DM is closely associated with systemic inflammation, endothelial dysfunction, cardiovascular risk, and increased clotting susceptibility. Platelets have fundamental roles in the development and propagation of inflammation and cardiovascular risk. They signal through membrane receptors, resulting in (hyper)activation and release of inflammatory molecules from platelet compartments. This review highlights how circulating inflammatory molecules, acting as platelet receptor ligands, interact with platelets, causing platelets to be potent drivers of systemic inflammation. We conclude by suggesting that focused platelet research in T2DM is an important avenue to pursue to identify novel therapeutic targets, and that platelets could be used as cellular activity sensors themselves.

Resolution of sickle cell disease-associated inflammation and tissue damage with 17R-resolvin D1

Resolvins (Rvs), endogenous lipid mediators, play a key role in the resolution of inflammation. Sickle cell disease (SCD), a genetic disorder of hemoglobin, is characterized by inflammatory and vaso-occlusive pathologies. We document altered proresolving events following hypoxia/reperfusion in humanized SCD mice. We demonstrate novel protective actions of 17R-resolvin D1 (17R-RvD1; 7S, 8R, 17R-trihydroxy-4Z, 9E, 11E, 13Z, 15E, 19Z-docosahexaenoic acid) in reducing ex vivo human SCD blood leukocyte recruitment by microvascular endothelial cells and in vivo neutrophil adhesion and transmigration. In SCD mice exposed to hypoxia/reoxygenation, oral administration of 17R -RvD1 reduces systemic/local inflammation and vascular dysfunction in lung and kidney. The mechanism of action of 17R-RvD1 involves (1) enhancement of SCD erythrocytes and polymorphonuclear leukocyte efferocytosis, (2) blunting of NF-κB activation, and (3) a reduction in inflammatory cytokines, vascular activation markers, and E-selectin expression. Thus, 17R-RvD1 might represent a new therapeutic strategy for the inflammatory vasculopathy of SCD.

Comprehensive Metabolomics Analysis of Xueshuan Xinmaining Tablet in Blood Stasis Model Rats Using UPLC-Q/TOF-MS

Blood stasis syndrome (BSS) is one of the most common Chinese medicine patterns in coronary heart disease. Our previous work proved that Xueshuan Xinmaining Tablet (XXT) could treat blood stasis through regulating the expression of F13a1, Car1 and Tbxa2r. In the current study, the effect and mechanism of XXT on BSS was comprehensively and holistically investigated based on a metabolomics approach. Urine and plasma samples of 10 BBS rats treated with XXT (XT), 9 BSS model rats (BM) and 11 normal control (NC) rats were collected and then determined by UPLC-Q/TOP-MS. Multivariate analyses were applied to distinguish differentiate urinary and plasma metabolite patterns between three groups. Results showed that a clear separation of three groups was achieved. XT group was located between BM group and NC group, and showing a tendency of recovering to NC group, which was consistent with the results of hemorheological studies. Some significantly changed metabolites like cortexolone, 3α,21-dihydroxy-5β-pregnane-11,20-dione and 19S-hete and leukotriene A4, chiefly involved in steroid hormone biosynthesis, arachidonic acid metabolism and lipid metabolism, were found and identified to explain the mechanism. These potential markers and their corresponding pathways will help explain the mechanism of BSS and XXT treatment. This work also proves that metabolomics is effective in traditional Chinese medicinal research.

Vascular endothelial growth factor receptor 1 (VEGFR1) tyrosine kinase signaling facilitates granulation tissue formation with recruitment of VEGFR1+ cells from bone marrow

Vascular endothelial growth factor (VEGF)-A facilitates wound healing. VEGF-A binds to VEGF receptor 1 (VEGFR1) and VEGFR2 and induces wound healing through the receptor's tyrosine kinase (TK) domain. During blood flow recovery and lung regeneration, expression of VEGFR1 is elevated. However, the precise mechanism of wound healing, especially granulation formation on VEGFR1, is not well understood. We hypothesized that VEGFR1-TK signaling induces wound healing by promoting granulation tissue formation. A surgical sponge implantation model was made by implanting a sponge disk into dorsal subcutaneous tissue of mice. Granulation formation was estimated from the weight of the sponge and the granulation area from the immunohistochemical analysis of collagen I. The expression of fibroblast markers was estimated from the expression of transforming growth factor-beta (TGF-β) and cellular fibroblast growth factor-2 (FGF-2) using real-time PCR (polymerase chain reaction) and from the immunohistochemical analysis of S100A4. VEGFR1 TK knockout (TK^-/-) mice exhibited suppressed granulation tissue formation compared to that in wild-type (WT) mice. Expression of FGF-2, TGF-β, and VEGF-A was significantly suppressed in VEGFR1 TK^-/- mice, and the accumulation of VEGFR1⁺ cells in granulation tissue was reduced in VEGFR1 TK^-/- mice compared to that in WT mice. The numbers of VEGFR1⁺ cells and S100A4⁺ cells derived from bone marrow (BM) were higher in WT mice transplanted with green fluorescent protein (GFP) transgenic WT BM than in VEGFR1 TK^-/- mice transplanted with GFP transgenic VEGFR1 TK^-/- BM. These results indicated that VEGFR1-TK signaling induced the accumulation of BM-derived VEGFR1⁺ cells expressing F4/80 and S100A4 and contributed to granulation formation around the surgically implanted sponge area in a mouse model.

Prostaglandin E2 regulates renal function in C57/BL6 mouse with 5/6 nephrectomy

AIMS

To investigate the roles of cyclooxygenases (COX) and their metabolites in C57/BL6 mice with 5/6 nephrectomy, an animal model of chronic renal failure.

MAIN METHODS

C57/BL6 mice were grouped into sham-operated (2K), one kidney removal (1K) and 5/6 nephrectomy groups (5/6Nx). Renal resistive index was measured by ultrasonography. Blood, aortae, renal arteries and renal cortex were collected for measurement of kidney function, assessment of vascular responsiveness, Western blotting, immuohistochemistry and enzyme-linked immunosorbent assays.

KEY FINDINGS

After four weeks, acetylcholine-induced relaxations were blunted in renal arteries of 1K and 5/6Nx mice; indomethacin, a non-selective COX inhibitor, improved the response in 5/6Nx, but not in 1K renal arteries. In 5/6Nx renal arteries, but not in 1K preparations, the protein presence of endothelial nitric oxide synthase (eNOS) was decreased, while that of COX-2 and its products [prostacyclin and thromboxane A₂] were increased. The renal resistive index was lower in 5/6Nx mice, suggesting a lower resistance in the renal microvasculature. In the renal cortex of 5/6Nx mice, eNOS protein presence was increased; while the presence of COX-2 was not detectable. The prostaglandin E₂ level was lower in the 5/6Nx cortex than in the other two groups.

SIGNIFICANCE

The early stage of renal mass removal is associated with increased renal arterial constriction and reduced microvascular resistance. The former is due to downregulation of eNOS and upregulation of COX-2, leading to an increased production of prostacyclin and thromboxane A₂. A reduced production of PGE₂ in the renal cortex is important for maintaining normal renal function.

Vascular endothelial growth factor receptor-1 (VEGFR-1) signaling enhances angiogenesis in a surgical sponge model

BACKGROUND

Vascular endothelial growth factor (VEGF)-A binds to both VEGF receptor (VEGFR)-1 and VEGFR-2, thereby promoting angiogenesis. It is widely accepted that VEGF-A, especially VEGFR-2, is a central player in angiogenesis, however the role of VEGFR-1 in angiogenesis remains unclear. The present study was conducted to examine the role of VEGFR-1 signaling in angiogenesis, using a quantitative in vivo angiogenesis model.

METHODS

Polyurethane sponge disks were implanted into dorsal subcutaneous tissue of mice. Angiogenesis was estimated by determining the number of CD31(+) vessels by immunohistochemical analysis. The expression of pro-angiogenic factors was quantified by reverse transcription quantitative polymerase chain reaction.

RESULTS

Compared to control IgG-treated mice, the number of CD31(+) vessels in the sponge implant was significantly suppressed in anti-VEGF-A neutralizing antibody-treated mice. CD31(+) vessel counts were suppressed in VEGFR-1 tyrosine kinase knockout (TKKO) mice, at the same level as in VEGFR-2 tyrosine kinase inhibitor (ZD6474)-treated mice compared to wild-type (WT) mice. The accumulation of VEGFR-1(+) cells in granulation tissue was significantly suppressed in VEGFR-1 TKKO mice compared to WT mice. In addition, expression of the pro-angiogenic growth factors, VEGF-A, matrix metalloproteinase-2, interleukin-6, and basic fibroblast growth factor in granulation tissue was suppressed in VEGFR-1 TKKO mice. A bone marrow (BM) transplantation experiment showed that the number of VEGFR-1(+) BM-derived cells and angiogenesis were significantly suppressed in VEGFR-1 TKKO mice transplanted with green fluorescent protein (GFP)(+) VEGFR-1 TKKO BM compared to WT mice transplanted with GFP(+) WT BM.

CONCLUSIONS

These results suggest that the VEGFR-1 tyrosine kinase signaling has an effect on angiogenesis. A selective VEGFR-1 agonist/antagonist could be a candidate therapeutic agent to control angiogenesis with recruitment of BM cells.