scholarly journals Phosphoinositide 3-kinase γ deficiency attenuates kidney injury and fibrosis in angiotensin II–induced hypertension

2020 ◽  
Vol 35 (9) ◽  
pp. 1491-1500
Author(s):  
Changlong An ◽  
Jia Wen ◽  
Zhaoyong Hu ◽  
William E Mitch ◽  
Yanlin Wang
Keyword(s):  
Blood Pressure ◽  
Bone Marrow ◽  
T Cells ◽  
Angiotensin Ii ◽  
Renal Injury ◽  
Matrix Protein ◽  
Kidney Injury ◽  
Inflammatory Cells ◽  
Extracellular Matrix Protein ◽  
Phosphoinositide 3 Kinase

Abstract Background We have shown that the CXCL16/CXCR6 axis plays a critical role in recruiting inflammatory cells and bone marrow-derived fibroblasts into the kidney leading to renal injury and fibrosis. However, the underlying signaling mechanisms are not known. Methods In the present study, we examined the role of phosphoinositide-3 kinase γ (PI3Kγ) signaling in the recruitment of inflammatory cells and bone marrow-derived fibroblasts into the kidney and development of renal injury and fibrosis in an experimental model of hypertension induced by angiotensin II. Results Blood pressure was comparable between wild-type (WT) and PI3Kγ knockout (KO) mice at baseline. Angiotensin II treatment led to an increase in blood pressure that was similar between WT and PI3Kγ KO mice. Compared with WT mice, PI3Kγ KO mice were protected from angiotensin II-induced renal dysfunction and injury and developed less proteinuria. PI3Kγ deficiency suppressed bone marrow-derived fibroblast accumulation and myofibroblast formation in the kidney and inhibited total collagen deposition and extracellular matrix protein production in the kidney in response to angiotensin II. PI3Kγ deficiency inhibited the infiltration of F4/80+ macrophages and CD3+ T cells into the kidney and reduced gene expression levels of pro-inflammatory cytokines in the kidney following angiotensin II treatment. Finally, inhibition of PI3Kγ suppressed CXCL16-induced monocyte migration in vitro. Conclusion These results indicate that PI3Kγ mediates the influx of macrophages, T cells and bone marrow-derived fibroblasts into the kidney resulting in kidney injury and fibrosis.

scholarly journals Elevated bone marrow sympathetic drive precedes systemic inflammation in angiotensin II hypertension

2019 ◽  
Vol 317 (2) ◽  
pp. H279-H289 ◽  
Author(s):  
Niousha Ahmari ◽  
Monica M. Santisteban ◽  
Douglas R. Miller ◽  
Natalie M. Geis ◽  
Riley Larkin ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Bone Marrow ◽  
T Cells ◽  
Immune System ◽  
Angiotensin Ii ◽  
Paraventricular Nucleus ◽  
Immune Cells ◽  
Rodent Models ◽  
Ang Ii ◽  
Pressure Infiltration

Increased sympathetic nervous system activity is a hallmark of hypertension (HTN), and it is implicated in altered immune system responses in its pathophysiology. However, the precise mechanisms of neural-immune interaction in HTN remain elusive. We have previously shown an association between elevated sympathetic drive to the bone marrow (BM) and activated BM immune cells in rodent models of HTN. Moreover, microglial-dependent neuroinflammation is also seen in rodent models of HTN. However, the cause-effect relationship between central and systemic inflammatory responses and the sympathetic drive remains unknown. These observations led us to hypothesize that increase in the femoral BM sympathetic nerve activity (fSNA) initiates a cascade of events leading to increase in blood pressure (BP). Here, we investigated the temporal relationship between the BM sympathetic drive, activation of the central and peripheral immune system, and increase in BP in the events leading to established HTN. The present study demonstrates that central infusion of angiotensin II (ANG II) induces early microglial activation in the paraventricular nucleus of hypothalamus, which preceded increase in the fSNA. In turn, activation of fSNA correlated with the timing of increased production and release of CD4+.IL17+ T cells and other proinflammatory cells into circulation and elevation in BP, whereas infiltration of CD4+ cells to the paraventricular nucleus marked establishment of ANG II HTN. This study identifies cellular and molecular mechanisms involved in neural-immune interactions in early and established stages of rodent ANG II HTN. NEW & NOTEWORTHY Early microglia activation in paraventricular nucleus precedes sympathetic activation of the bone marrow. This leads to increased bone marrow immune cells and their release into circulation and an increase in blood pressure. Infiltration of CD4+ T cells into paraventricular nucleus paraventricular nucleus marks late hypertension.

scholarly journals AT1 and AT2 receptors modulate renal tubular cell necroptosis in angiotensin II-infused renal injury mice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yongjun Zhu ◽  
Hongwang Cui ◽  
Jie Lv ◽  
Haiqin Liang ◽  
Yanping Zheng ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Renal Injury ◽  
Critical Role ◽  
Kidney Injury ◽  
Renin Angiotensin System ◽  
Tubular Cell ◽  
Tubular Damage ◽  
Renal Tubular Cell ◽  
Ang Ii ◽  
Renal Tubular

AbstractAbnormal renin-angiotensin system (RAS) activation plays a critical role in the initiation and progression of chronic kidney disease (CKD) by directly mediating renal tubular cell apoptosis. Our previous study showed that necroptosis may play a more important role than apoptosis in mediating renal tubular cell loss in chronic renal injury rats, but the mechanism involved remains unknown. Here, we investigate whether blocking the angiotensin II type 1 receptor (AT1R) and/or angiotensin II type 2 receptor (AT2R) beneficially alleviates renal tubular cell necroptosis and chronic kidney injury. In an angiotensin II (Ang II)-induced renal injury mouse model, we found that blocking AT1R and AT2R effectively mitigates Ang II-induced increases in necroptotic tubular epithelial cell percentages, necroptosis-related RIP3 and MLKL protein expression, serum creatinine and blood urea nitrogen levels, and tubular damage scores. Furthermore, inhibition of AT1R and AT2R diminishes Ang II-induced necroptosis in HK-2 cells and the AT2 agonist CGP42112A increases the percentage of necroptotic HK-2 cells. In addition, the current study also demonstrates that Losartan and PD123319 effectively mitigated the Ang II-induced increases in Fas and FasL signaling molecule expression. Importantly, disruption of FasL significantly suppressed Ang II-induced increases in necroptotic HK-2 cell percentages, and necroptosis-related proteins. These results suggest that Fas and FasL, as subsequent signaling molecules of AT1R and AT2R, might involve in Ang II-induced necroptosis. Taken together, our results suggest that Ang II-induced necroptosis of renal tubular cell might be involved both AT1R and AT2R and the subsequent expression of Fas, FasL signaling. Thus, AT1R and AT2R might function as critical mediators.

Abstract 161: Identification of Genetic Variants Associated with Kidney Injury That Leads to Increased Blood Pressure

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Ashlyn C Harmon ◽  
Ashley C Johnson ◽  
Santosh Atanur ◽  
Klio Maratou ◽  
Tim Aitman ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Bone Marrow ◽  
Immune Response ◽  
Renal Function ◽  
Kidney Disease ◽  
Kidney Function ◽  
Genetic Variants ◽  
Kidney Injury ◽  
Chromosome 11 ◽  
Genomic Locus

Hypertension, diabetes and obesity, along with genetic predisposition, contribute to the growing number of chronic kidney disease patients. Our novel congenic model [S.SHR(11)] was developed through genetic modification of the Dahl salt-sensitive (S) rat, a model of hypertension related renal disease. The S.SHR(11) strain exhibits accelerated kidney injury compared to the already highly susceptible S rat. On either a low or high-salt diet, the S.SHR(11) model predominately exhibited more tubulointerstitial fibrosis compared to the S rat (17.1±1.29% vs. 12.9±1.22%). Increased α-SMA and macrophage infiltration was also observed. The S and S.SHR(11) had similar blood pressure (week 12), despite an early reduction in renal function in the S.SHR(11); however at an advanced age the S.SHR(11) demonstrated significantly higher blood pressure than the S (215±6.6 mm Hg vs. 183±5.9, respectively). This suggests that increased kidney injury is driving the development of hypertension later in life. Since these two animal models are identical with exception of chromosome 11, the causative genetic variants contributing to decreased renal function must reside within this region. The Dahl S and SHR genomes have been sequenced; this data provides a catalog of all the genetic variants between the two models. The 95% confidence interval of the genomic locus contains 28 non-synonymous SNP, with 15 of these SNP occurring within only three genes: Retnlg , Trat1 and Myh15. Two of these genes, Retnlg and Trat1, are known to play a role in immune response leading to our hypothesis that genetic variants in these genes alter protein function and lead to an increased immune response. Bone marrow transplant studies have been initiated to test our hypothesis and preliminary data shows that S rats who receive S.SHR(11) bone marrow have kidney function measurements similar to the S.SHR(11). The sequencing information has also lead to the development of nine new, more refined congenic strains. Through functional analysis of these new congenic animals, identification of the causative genetic variations will be expedited. In summary, we are employing a model of accelerated kidney disease to identify genes or genetic variants responsible for reduced kidney function and hypertension.

Upregulation of α8β1-integrin in cardiac fibroblast by angiotensin II and transforming growth factor-β1

2001 ◽  
Vol 281 (5) ◽  
pp. C1457-C1467 ◽  
Author(s):  
Gaétan Thibault ◽  
Marie-Josée Lacombe ◽  
Lynn M. Schnapp ◽  
Alexandre Lacasse ◽  
Fatiha Bouzeghrane ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Growth Factor ◽  
Matrix Protein ◽  
Transforming Growth Factor ◽  
Cardiac Fibroblasts ◽  
Transforming Growth Factor Β1 ◽  
Cardiac Fibroblast ◽  
Extracellular Matrix Protein ◽  
Ang Ii ◽  
Tgf Β1

Using a novel pharmacological tool with125I-echistatin to detect integrins on the cell, we have observed that cardiac fibroblasts harbor five different RGD-binding integrins: α8β1, α3β1, α5β1, αvβ1, and αvβ3. Stimulation of cardiac fibroblasts by angiotensin II (ANG II) or transforming growth factor-β1 (TGF-β1) resulted in an increase of protein and heightening by 50% of the receptor density of α8β1-integrin. The effect of ANG II was blocked by an AT1, but not an AT2, receptor antagonist, or by an anti-TGF-β1 antibody. ANG II and TGF-β1 increased fibronectin secretion, smooth muscle α-actin synthesis, and formation of actin stress fibers and enhanced attachment of fibroblasts to a fibronectin matrix. The α8- and β1-subunits were colocalized by immunocytochemistry with vinculin or β3-integrin at focal adhesion sites. These results indicate that α8β1-integrin is an abundant integrin on rat cardiac fibroblasts. Its positive modulation by ANG II and TGF-β1 in a myofibroblast-like phenotype suggests the involvement of α8β1-integrin in extracellular matrix protein deposition and cardiac fibroblast adhesion.

Extracellular Matrix Protein Matrilin-4 Regulates HSC Stress Response

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 601-601
Author(s):  
Hannah Uckelmann ◽  
Sandra Blaszkiewicz ◽  
Marieke Essers
Keyword(s):  
Cell Cycle ◽  
Bone Marrow ◽  
Extracellular Matrix ◽  
Matrix Protein ◽  
Bone Marrow Cells ◽  
Blood System ◽  
Extracellular Matrix Protein

Abstract The life-long maintenance of the blood system is accomplished by a pool of self-renewing multipotent hematopoietic stem cells (HSCs). Adult HSCs are found in a dormant state for most of their lifetime, entering cell cycle only to maintain homeostatic blood supply. Under stress conditions such as infection or chemotherapy, the loss of mature blood cells leads to an activation of dormant HSCs to replenish the blood system. Gene expression analysis performed by our group now revealed that Matrilin-4 is highly expressed in long-term HSCs (LT-HSCs) compared to short-term HSCs or committed progenitors, suggesting a potential role of Matrilin-4 in HSC function. Matrilin-4 is a member of the von Willebrand factor A-containing family of extracellular adapter proteins, which form filamentous structures outside of cells. Using mice lacking the entire family of Matrilins (1-4) we have investigated the role of Matrilins in HSC function. Constitutive Matrilin 1-4 KO mice exhibit normal hematopoiesis with a mild reduction in bone marrow cellularity and LSK numbers. However, when Matrilin KO bone marrow cells are pushed to proliferate in competitive transplantation assays with wildtype (WT) cells, they show a striking growth advantage. In a competitive transplant setting, where bone marrow cells of Matrilin KO versus WT mice are transplanted in a 1:1 ratio, the KO cells outcompete WT cells within four weeks, reaching a 90% chimerism at 16 weeks. This competitive advantage of Matrilin KO cells is evident in the long-term stem cell level as well as progenitors and is consistent in secondary transplants. To explore this remarkable phenotype, we performed single cell transplantation experiments of LT-HSCs and observed a more rapid reconstitution of peripheral blood cell levels of KO HSCs compared to WT controls. Confirming this growth advantage, Matrilin KO LSK cells show higher colony forming and serial replating potential in vitro, which can be rescued by the addition of recombinant or overexpressed Matrilin-4. While Matrilin-4 is highly expressed in homeostatic HSCs, in vivo treatment with IFNα or other inflammatory agents, such as LPS or G-CSF result in a dramatic downregulation (25-fold) of Matrilin-4 on the transcript as well as the protein level. Moreover, Matrilin KO HSCs are more sensitive to inflammatory stress, as they show a 2-fold stronger cell cycle activation in response to IFNα in vivo. Critically, Matrilin-4 KO HSCs return to the G0 state of the cell cycle normally after stress-induced activation and transplantation, thereby preventing their exhaustion. In summary, we show that the extracellular matrix protein Matrilin-4 is a novel component of the HSC niche, regulating HSC stress response. Surprisingly, HSCs lacking this extracellular matrix protein show a higher HSC potential due to an accelerated response to stress. Our data suggest that high expression of Matrilin-4 in LT-HSCs confers a resistance to stress stimuli. In situations of acute stress such as infection or transplantation however, this protection is rapidly lost to allow HSCs to efficiently replenish the blood system. Disclosures No relevant conflicts of interest to declare.

scholarly journals Sustained Growth of Primary Myeloma Cells in Coculture with Whole Donor Bone Marrow Is Associated with Induced Secretion of the Microenvironmental Mediator of Cytokinesis, Hemicentin-1

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3403-3403
Author(s):  
Rakesh Bam ◽  
Ricky D Edmondson ◽  
Caleb K Stein ◽  
Xin Li ◽  
Wen Ling ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Extracellular Matrix ◽  
Matrix Protein ◽  
Plasma Cells ◽  
Conflicts Of Interest ◽  
Extracellular Matrix Protein ◽  
Focal Lesion ◽  
Adherent Cells ◽  
Bone Biopsies

Abstract Primary human myeloma (MM) cells do not survive in culture while current systems for growing these cells are limited to coculture with specific bone marrow (BM) cell type or growth in immunodeficient animals. The aim of the study was to establish a coculture system for studying long-term growth of primary MM and their interaction with whole BM microenvironment, namely normal bone marrow (NBM) system . Whole BM cells from healthy donors (n=20) were cultured in medium supplemented with serum (10% v/v) pooled from MM patients for 7 days followed by coculture with CD138-selected primary MM cells (4:1 NBM:MM ratio) or MM cell lines (10:1 NBM:MM ratio) for ≥7 days. This NBM system is composed of adherent and non-adherent compartments. Adherent cells were mainly macrophages and mesenchymal stem cells (MSCs) whereas non-adherent cells contained typical hematopoietic cells including CD19+, CD3+, CD11b+ and CD33+ cells. Growth of MM cells was determined by CD45/CD38 flow cytometry and by bioluminescence of luciferase-expressing MM cells. MM cells or subset of MM cells from all patients (n=60) survived and grew in this system regardless of molecular risk or subtype, and MM growth was comparable to coculture with the supportive osteoclasts or MSCs. Adherent and non-adherent compartments supported MM cells which required patient’s serum for optimal growth. In 14 of 20 experiments, number of MM plasma cells, quantified by flow cytometry or bioluminescence analysis was increased by 58±12% (p<0.0005) in the NBM system and cell proliferation was evident by the loss of cell membrane PKH26 dye or by BudR uptake in dividing cocultured MM cells. Growth of OPM2, H929 and ARP1 lines was also stimulated in the NBM system which protected these cells from dexamethasone (1-2.5µM) but not bortezomib (0.01-5nM), while the effect of lenalidomide varied (0.1-5µM). For identifying secreted proteins that may mediate MM growth in the NBM system, supernatant were collected from serum-free culture of NBM, MM cells and NBM/MM coculture (18 hrs, n=3). Proteomics analysis performed on supernatant samples identified 1843 proteins. The clinical markers B2M and LDHA were present at high levels and were significantly higher by 2-2.4 folds in NBM/MM coculture compared to cultured NBM (p<0.04). Further filtration revealed 89 proteins that were significantly changed upon NBM/MM coculture but minimally detected in the MM cells culture: 14 were significantly lower and 75 were higher in NBM/MM cocultures compared to cultured NBM. These factors include mediators of extracellular matrix, immunity, and inflammation. A microenvironmental secreted factor that was not detected in the supernatant from MM cells or NBM but was secreted in cocultures was hemicentin-1 (HMCN1), a unique extracellular matrix protein directly involved in cytokinesis (Xu and Vogel, Curr Biol 2011) but has yet not been implicated in MM. Hemicentin-1 gene expression was detected in cultured NBM and MSCs but not in primary MM cells, MM lines or CD11b+ NBM cells. Induction of hemicentin-1 expression in MSCs after coculture with MM cells was validated by immunohistochemistry. Hemicentin-1 expression is higher in random bone biopsies from newly diagnosed MM patients (n=406) compared to donor biopsies (n=25, p<0.008) and highest in MM focal lesion biopsies (n=49, q<0.0005 vs. paired random bone biopsies). Higher baseline HMCN1 expression in biopsies was associated with inferior overall survival in TT3b clinical trial (p<0.027). The NBM system demonstrates the ability of primary MM plasma cells to interact with and to survive in coculture with healthy allogeneic adult BM through secretion of factors involved in immune evasion and extracellular matrix modification. Ongoing work is underway to unravel the role of hemicentin-1 in MM growth. Disclosures No relevant conflicts of interest to declare.

scholarly journals Effects of Angiotensin II Type 1A Receptor on ACE2, Neprilysin and KIM-1 in Two Kidney One Clip (2K1C) Model of Renovascular Hypertension

2021 ◽  
Vol 11 ◽  
Author(s):  
Laale F. Alawi ◽  
Sanjeev Dhakal ◽  
Sana E. Emberesh ◽  
Harshal Sawant ◽  
Anhar Hosawi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Mouse Model ◽  
Cell Injury ◽  
Kidney Injury ◽  
Ang Ii ◽  
Knock Out ◽  
Contralateral Kidney ◽  
Arterial Blood ◽  
Expression And Activity

Activation of the renin angiotensin system plays a pivotal role in the regulation of blood pressure, which is mainly attributed to the formation of angiotensin-II (Ang II). The actions of Ang II are mediated through binding to the Ang-II type 1 receptor (AT1R) which leads to increased blood pressure, fluid retention, and aldosterone secretion. In addition, Ang II is also involved in cell injury, vascular remodeling, and inflammation. The actions of Ang II could be antagonized by its conversion to the vasodilator peptide Ang (1–7), partly generated by the action of angiotensin converting enzyme 2 (ACE2) and/or neprilysin (NEP). Previous studies demonstrated increased urinary ACE2 shedding in the db/db mouse model of diabetic kidney disease. The aim of the study was to investigate whether renal and urinary ACE2 and NEP are altered in the 2K1C Goldblatt hypertensive mice. Since AT1R is highly expressed in the kidney, we also researched the effect of global deletion of AT1R on renal and urinary ACE2, NEP, and kidney injury marker (KIM-1). Hypertension and albuminuria were induced in AT1R knock out (AT1RKO) and WT mice by unilateral constriction of the renal artery of one kidney. The 24 h mean arterial blood pressure (MAP) was measured using radio-telemetry. Two weeks after 2K1C surgery, MAP and albuminuria were significantly increased in WT mice compared to AT1RKO mice. Results demonstrated a correlation between MAP and albuminuria. Unlike db/db diabetic mice, ACE2 and NEP expression and activities were significantly decreased in the clipped kidney of WT and AT1RKO compared with the contralateral kidney and sham control (p &lt; 0.05). There was no detectable urinary ACE2 and NEP expression and activity in 2K1C mice. KIM-1 was significantly increased in the clipped kidney of WT and AT1KO (p &lt; 0.05). Deletion of AT1R has no effect on the increased urinary KIM-1 excretion detected in 2K1C mice. In conclusion, renal injury in 2K1C Goldblatt mouse model is associated with loss of renal ACE2 and NEP expression and activity. Urinary KIM-1 could serve as an early indicator of acute kidney injury. Deletion of AT1R attenuates albuminuria and hypertension without affecting renal ACE2, NEP, and KIM-1 expression.

scholarly journals Greater T Regulatory Cells in Females Attenuate DOCA-Salt–Induced Increases in Blood Pressure Versus Males

Hypertension ◽  
2020 ◽  
Vol 75 (6) ◽  
pp. 1615-1623 ◽  
Author(s):  
Kasey M. Belanger ◽  
G. Ryan Crislip ◽  
Ellen E. Gillis ◽  
Mahmoud Abdelbary ◽  
Jacqueline B. Musall ◽  
...  
Keyword(s):  
Blood Pressure ◽  
T Cells ◽  
T Regulatory Cells ◽  
Critical Role ◽  
Kidney Injury ◽  
Male Rats ◽  
Regulatory Cells ◽  
Salt Treatment ◽  
Males And Females ◽  
The Impact

Hypertension is the most common risk factor for cardiovascular disease, causing over 18 million deaths a year. Although the mechanisms controlling blood pressure (BP) in either sex remain largely unknown, T cells play a critical role in the development of hypertension. Further evidence supports a role for the immune system in contributing to sex differences in hypertension. The goal of the current study was to first, determine the impact of sex on the renal T-cell profiles in DOCA-salt hypertensive males and females and second, test the hypothesis that greater numbers of T regulatory cells (Tregs) in females protect against DOCA-salt–induced increases in BP and kidney injury. Male rats displayed greater increases in BP than females following 3 weeks of DOCA-salt treatment, although increases in renal injury were comparable between the sexes. DOCA-salt treatment resulted in an increase in proinflammatory T cells in both sexes; however, females had more anti-inflammatory Tregs than males. Additional male and female DOCA-salt rats were treated with anti-CD25 to decrease Tregs. Decreasing Tregs significantly increased BP only in females, thereby abolishing the sex difference in the BP response to DOCA-salt. This data supports the hypothesis that Tregs protect against the development of hypertension and are particularly important for the control of BP in females.

P6296The role of extracellular matrix protein 1 (ECM1) - a novel link between inflammation and cardiac fibrosis

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
S Hardy ◽  
N S Mabotuwana ◽  
L A Murtha ◽  
B Coulter ◽  
S S Bezenilla ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Extracellular Matrix ◽  
Matrix Protein ◽  
Cardiac Fibrosis ◽  
In Situ Hybridisation ◽  
Extracellular Matrix Protein ◽  
Cardiac Diseases ◽  
Extracellular Matrix Protein 1 ◽  
Primary Mouse

Abstract Introduction Cardiac fibrosis is a severe consequence of cardiovascular disease and aging, in which we currently have no effective treatments. The mechanisms underpinning the development of cardiac fibrosis remains poorly understood. Our preliminary data suggested extracellular matrix protein 1 (ECM1) is involved in cardiac fibrosis. We therefore aimed to investigate the role of ECM1 in several fibrotic cardiac diseases. Methods Young and ageing (3m/18m) male C57BL/6 mice, and primary mouse cardiac fibroblast (cFB) cultures, commercial human cardiac fibroblasts (Hu-cFB), human coronary artery endothelial cell (HCAEC)/smooth muscle cell (HCASMC), and human cardiac myocyte (HCM) cell lines were used. Young mice were subject to myocardial infarction (MI, 3-day/28-day, n=6/6), or pressure overload (TAC, 3-day/13-week, n=4/4). Left ventricle (LV) was collected at all time-points, and at 18m (ageing; n=3). Spleen and bone marrow was extracted from young control mice. Hu-cFB cells were treated with recombinant ECM1 (20ng/ml) for either 10, 30 or 50 min, or 48h. Immunoblotting was conducted on all samples, qPCR on LV tissue only, density gradient centrifugation and multicolour flow cytometry coupled with fluorescent ECM1 mRNA in-situ hybridisation (FISH-Flow) on bone marrow cells. Results ECM1 expression was upregulated in ageing LV (mRNA 2.2±0.1-fold, p=0.0002; protein 2.0-fold, p=0.0006), day-3 post-MI (mRNA, 4.9±2.0-fold, p=0.004; protein, 3.0-fold, p=0.004), a trend of ECM1 upregulation was observed at day-28 post-MI (mRNA, 13.2±12.0-fold, p=0.003; protein, 1.8-fold, p=0.2), but no change post-TAC. Both ERK1/2 and AKT phosphorylation was upregulated 10 min post-ECM1 treatment of Hu-cFBs (ERK1/2, 2.0-fold, p<0.0001; AKT, 1.9-fold, p<0.0001), and Collagen-I protein expression was upregulated 48h post-ECM1 treatment (1.9-fold, p=0.004). ECM1 protein was not expressed in cFB, Hu-cFB, HCAEC, HCASMC or HCM, however ECM1 protein was highly expressed in spleen and bone marrow; to a greater extent in granulocytes compared to monocytes (p=0.004). tSNE analysis of ECM1 mRNA FISH-Flow revealed ECM1+ are highly granular, moderate to large in size, and express (to varying levels) CD45, CD11b, CD11c, F4/80, Ly6-C, Ly-6G, and FcεrI-α. However ECM1+ cells did not express markers indicative of smaller cells (CD3 or MHC II). Conclusions These data demonstrate that ECM1 plays a role in ageing and post-MI fibrosis. Although ECM1 was not produced by resident cardiac cells, it was highly expressed in spleen and bone marrow; specifically, large, granular bone marrow cell sub-types such as granulocytes and/or macrophages. Our data suggest ECM1 is expressed by cardiac infiltrating leukocytes to provoke fibroblast collagen expression in a disease specific manner; potentially via the ERK1/2 and/or AKT pathway activation. Therefore, ECM1 warrants further investigation, and may be a promising target for the treatment of fibrotic cardiac diseases. Acknowledgement/Funding John hunter hospital charitable trust, Hunter medical research institute (HMRI) grants

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