Enrique Gallego-Colon

Monocyte/Macrophage-derived IGF-1 Orchestrates Murine Skeletal Muscle Regeneration and Modulates Autocrine Polarization.

Insulin-like growth factor 1 (IGF-1) is a potent enhancer of tissue regeneration, and its overexpression in muscle injury leads to hastened resolution of the inflammatory phase. Here, we show that monocytes/macrophages constitute an important initial source of IGF-1 in muscle injury, as conditional deletion of the IGF-1 gene specifically in mouse myeloid cells (ϕIGF-1 CKO) blocked the normal surge of local IGF-1 in damaged muscle and significantly compromised regeneration. In injured muscle, Ly6C+ monocytes/macrophages and CD206+ macrophages expressed equivalent IGF-1 levels, which were transiently upregulated during transition from the inflammation to repair. In injured ϕIGF-1 CKO mouse muscle, accumulation of CD206+ macrophages was impaired, while an increase in Ly6C+ monocytes/macrophages was favored. Transcriptional profiling uncovered inflammatory skewing in ϕIGF-1 CKO macrophages, which failed to fully induce a reparative gene program in vitro or in vivo, revealing a novel autocrine role for IGF-1 in modulating murine macrophage phenotypes. These data establish local macrophage-derived IGF-1 as a key factor in inflammation resolution and macrophage polarization during muscle regeneration.

TSPO mutations in rats and a human polymorphism impair the rate of steroid synthesis

The 18u2005kDa translocator protein (TSPO) is a ubiquitous conserved outer mitochondrial membrane protein implicated in numerous cell and tissue functions, including steroid hormone biosynthesis, respiration, cell proliferation, and apoptosis. TSPO binds with high affinity to cholesterol and numerous compounds, is expressed at high levels in steroid-synthesizing tissues, and mediates cholesterol import into mitochondria, which is the rate-limiting step in steroid formation. In humans, the rs6971 polymorphism on the TSPO gene leads to an amino acid substitution in the fifth transmembrane loop of the protein, which is where the cholesterol-binding domain of TSPO is located, and this polymorphism has been associated with anxiety-related disorders. However, recent knockout mouse models have provided inconsistent conclusions of whether TSPO is directly involved in steroid synthesis. In this report, we show that TSPO deletion mutations in rat and its corresponding rs6971 polymorphism in humans alter adrenocorticotropic hormone-induced plasma corticosteroid concentrations. Rat tissues examined show increased cholesteryl ester accumulation, and neurosteroid formation was undetectable in homozygous rats. These results also support a role for TSPO ligands in diseases with steroid-dependent stress and anxiety elements.

Cardiac-Restricted IGF-1Ea Overexpression Reduces the Early Accumulation of Inflammatory Myeloid Cells and Mediates Expression of Extracellular Matrix Remodelling Genes after Myocardial Infarction

Strategies to limit damage and improve repair after myocardial infarct remain a major therapeutic goal in cardiology. Our previous studies have shown that constitutive expression of a locally acting insulin-like growth factor-1 Ea (IGF-1Ea) propeptide promotes functional restoration after cardiac injury associated with decreased scar formation. In the current study, we investigated the underlying molecular and cellular mechanisms behind the enhanced functional recovery. We observed improved cardiac function in mice overexpressing cardiac-specific IGF-1Ea as early as day 7 after myocardial infarction. Analysis of gene transcription revealed that supplemental IGF-1Ea regulated expression of key metalloproteinases (MMP-2 and MMP-9), their inhibitors (TIMP-1 and TIMP-2), and collagen types (Col 1α1 and Col 1α3) in the first week after injury. Infiltration of inflammatory cells, which direct the remodelling process, was also altered; in particular there was a notable reduction in inflammatory Ly6C+ monocytes at day 3 and an increase in anti-inflammatory CD206+ macrophages at day 7. Taken together, these results indicate that the IGF-1Ea transgene shifts the balance of innate immune cell populations early after infarction, favouring a reduction in inflammatory myeloid cells. This correlates with reduced extracellular matrix remodelling and changes in collagen composition that may confer enhanced scar elasticity and improved cardiac function.

Galectin Targeted Therapy in Oncology: Current Knowledge and Perspectives

The incidence and mortality of cancer have increased over the past decades. Significant progress has been made in understanding the underpinnings of this disease and developing therapies. Despite this, cancer still remains a major therapeutic challenge. Current therapeutic research has targeted several aspects of the disease such as cancer development, growth, angiogenesis and metastases. Many molecular and cellular mechanisms remain unknown and current therapies have so far failed to meet their intended potential. Recent studies show that glycans, especially oligosaccharide chains, may play a role in carcinogenesis as recognition patterns for galectins. Galectins are members of the lectin family, which show high affinity for β-galactosides. The galectin–glycan conjugate plays a fundamental role in metastasis, angiogenesis, tumor immunity, proliferation and apoptosis. Galectins’ action is mediated by a structure containing at least one carbohydrate recognition domain (CRD). The potential prognostic value of galectins has been described in several neoplasms and helps clinicians predict disease outcome and determine therapeutic interventions. Currently, new therapeutic strategies involve the use of inhibitors such as competitive carbohydrates, small non-carbohydrate binding molecules and antibodies. This review outlines our current knowledge regarding the mechanism of action and potential therapy implications of galectins in cancer.

Intravenous delivery of adeno-associated virus 9-encoded IGF-1Ea propeptide improves post-infarct cardiac remodelling

The insulin-like growth factor Ea propeptide (IGF-1Ea) is a powerful enhancer of cardiac muscle growth and regeneration, also blocking age-related atrophy and beneficial in multiple skeletal muscle diseases. The therapeutic potential of IGF-1Ea compared with mature IGF-1 derives from its local action in the area of synthesis. We have developed an adeno-associated virus (AAV) vector for IGF-1Ea delivery to the heart to treat mice after myocardial infarction and examine the reparative effects of local IGF-1Ea production on left ventricular remodelling. A cardiotropic AAV9 vector carrying a cardiomyocyte-specific IGF-1Ea-luciferase bi-cistronic gene expression cassette (AAV9.IGF-1Ea) was administered intravenously to infarcted mice, 5u2009h after ischemia followed by reperfusion (I/R), as a model of myocardial infarction. Virally encoded IGF-1Ea in the heart improved global left ventricular function and remodelling, as measured by wall motion and thickness, 28 days after delivery, with higher viral titers yielding better improvement. The present study demonstrates that single intravenous AAV9-mediated IGF-1Ea Gene Therapy represents a tissue-targeted therapeutic approach to prevent the adverse remodelling after myocardial infarct.

Exenatide modulates expression of metalloproteinases and their tissue inhibitors in TNF-α stimulated human retinal pigment epithelial cells

BACKGROUNDnDiabetic retinopathy (DR) is one of the most common complications of diabetes and the leading cause of acquired blindness in adults. In diabetic patients hyperglycemia induces complex metabolic abnormalities affecting retinal homeostasis, and promotes retinal inflammation and angiogenesis. Incretin mimetic drugs such exenatide, are a relatively new group of drugs used in the treatment of diabetes. We investigated the potential direct effects of exenatide on human retinal pigment epithelium (HRPE).nnnMETHODSncAMP production was measured after stimulation of HRPE cells with GLP-1 and exenatide. Intracellular signaling pathways were also examined. HRPE cells were stimulated with TNF-α and subsequently incubated with exenatide. The concentration of metalloproteinases, MMP-1, MMP-2 and MMP-9, and tissue inhibitors of metalloproteinases, TIMP-1, TIMP-2, and TIMP-3 were evaluated. Viability, cytotoxicity and caspase 3/7 activation were determined. Activity of dipeptidyl peptidase-4 (DPP-4), an enzyme involved in GLP-1 inactivation, was also determined.nnnRESULTSnBoth GLP-1 and exenatide stimulation in HRPE cells caused no effect in cAMP levels suggesting alternative signaling pathways. Signaling pathway analysis showed that exenatide reduced phosphorylation of Akt-Ser473, PRAS40, SAPK/JNK, Bad, and S6 proteins but not Akt-Thr308. Exenatide also decreased MMP-1, MMP-9, and TIMP-2 protein levels whereas MMP-2 level in HRPE cells was increased. Finally, we show that exenatide decreased the activity of DPP-4 in TNF-α stimulated HRPE cells.nnnCONCLUSIONSnThese findings indicate that exenatide modulates regulation of extracellular matrix components involved in retinal remodeling.

Cardiac Stem Cells: A Plethora of Potential Therapies for Myocardial Regeneration Within Reach

The limited regenerative capacity of the adult heart hinders cardiac regeneration and still remains an unsolved therapeutic target. In the last decade, the development of cell-based approaches for the treatment of myocardial infarction has made substantial progress. The use of cardiac stem cells (CSC) represents a promising therapeutic tool upon massive loss of cardiac tissue such as after myocardial infarction. Different putative CSC populations, with self-renewing capacity and potential to differentiate into cardiomyocytes, smooth muscle, or endothelial cells, are under evaluation. Preclinical studies have discovered various pools of putative CSC including c-kit cardiac progenitor cells (CPCs), epicardium-derived cells (EPDC), Sca-1, cardiac side population (cSP), islet-1 CPC, cardiosphere-derived cells (CDCs), cardiac colony-forming unit fibroblast (cCFU-F), cardiac atrial appendage stem cells (CASCs), bone marrow-derived CSC (BMdCSC), and modified embryonic or induced pluripotent stem cells. Preclinical studies provided encouraging results on the ability of CSC to restore cardiac contractility, regional and global function, myocyte survival, and the remodeling process. Although CSC therapy is safe and feasible in the clinics, heterogeneous outcomes have cast doubts on CSC efficacy to promote cardiac regeneration. Overall, the poor engraftment of transplanted CSC highlights the possibility that the observed beneficial effects may be attributed to the release of paracrine factors rather than CSC ability to reconstitute functional well-differentiated myocardium. Unfortunately, controversy remains around the benefit of CSC therapy, and big challenges such as ideal dose, identification and selection of the best CSC type, delivery system, and concomitant treatments must be addressed. The success of CSC regenerative therapies implies more basic research, and further clinical trials are needed before to reach the clinical practice and fulfill the long-lasting goal of cardiac regeneration.

Pacemaker lead endocarditis: A rare cause of relapsing brucellosis

Highlights • Brucellosis is a multystemic disease that presents with broad spectrum of clinical manifestations.• Endocarditis caused by infection of the pacemaker is a complication of brucelosis.• Managements options include device removal and extended combination therapy with antibiotics.

Exenatide exhibits anti-inflammatory properties and modulates endothelial response to tumor necrosis factor α-mediated activation

INTRODUCTIONnCardiovascular disease is the main cause of mortality and morbidity in the industrialized world. Incretin-mimetic compounds such as exenatide are currently used in the treatment of type 2 diabetes.nnnAIMSnWe investigated the effects of incretin drugs on apoptosis, adhesion molecule expression, and concentration of extracellular matrix (ECM) metalloproteinases under inflammatory conditions within the context of atherosclerotic plaque formation of both human coronary artery endothelial cells (hCAECs) and human aortic endothelial cells (hAoECs). TNF-α-stimulated hCAEC and hAoEC were treated with exenatide (1 and 10xa0nmol/L) and GLP-1 (10 and 100xa0nmol/L) then evaluated for caspase 3/7 activity and assayed for protein levels of adhesion molecules sICAM-1, sVCAM-1, and P-selectin. Concentrations of matrix metalloproteinases (MMPs) MMP-1, MMP-2, MMP-9, and their inhibitors-tissue inhibitor of metalloproteinases (TIMPs), TIMP-1, TIMP-2 were also measured to evaluate the effects on extracellular matrix turnover within an inflammatory environment. Intracellular signaling pathways were evaluated via transfection of endothelial cells with a GFP vector under the NF-κB promoter.nnnRESULTSnOur experimental data suggest that GLP-1 receptor (GLP-1R) agonists downregulate activation of NF-κB and adhesion molecules ICAM and VCAM, but not P-selectin, in both endothelial cell lines. Exendin-4 and GLP-1 modulate the expression of MMPs and TIMPs, with statistically significant effects observed at high concentrations of both incretins. Expressive modulation may be mediated by NF-κB as observed by activation of the vector when stimulated under inflammatory conditions.nnnCONCLUSIONnThese findings indicate that GLP-1 analogs have anti-inflammatory properties in endothelial cells that may play an important role in preventing atherosclerosis.

Incretin drugs as modulators of atherosclerosis

Atherosclerosis is a major underlying cause of ischemic heart diseases, ischemic stroke, and peripheral artery disease. Atherosclerotic plaque progression is characterized by chronic progressive inflammation of the arterial wall, endothelial cell dysfunction, and subendothelial lipoprotein retention. Incretin drugs, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dipeptidyl peptidase-IV (DPP-IV) inhibitors, are promising anti-hyperglycemic agents used for the treatment of type 2 diabetes mellitus (T2DM). In addition to glucose-lowering effects, emerging data suggest that incretin drugs have anti-atherogenic effects with the potential to stabilize atherosclerotic plaques and treat arterial inflammation. Clinical and preclinical studies have reported a plethora of therapeutic benefits of incretin drugs, including modulation of inflammatory response, reduction of intima-media thickening, improvement in lipid profiles, endothelial and smooth muscle cell modulation. Despite extensive research and widespread clinical use of incretin-based therapies, the research on the incretin hormones continues to expand. This review outlines clinical studies, molecular aspects, and potential therapeutic implications of incretin drugs in attenuation of atherosclerosis.