Search

The purpose of this study was to follow the long-term progression of diabetic cardiomyopathy by combining cardiac magnetic resonance (CMR) and molecular analysis. The evolution of diabetic cardiomyopathy to heart failure affects patients'morbidity and mortality. CMR is the gold standard to assess cardiac remodeling, but there is a lack of markers linked to the mechanism of diabetic cardiomyopathy progression. Five-year longitudinal study on patients with type 2 diabetes mellitus (T2DM) enrolled in the CECSID (Cardiovascular Effects of Chronic Sildenafil in Men With Type 2 Diabetes) trial compared with nondiabetic age-matched controls. CMR with tagging together with metabolic and molecular assessments were performed at baseline and 5-year follow-up. A total of 79 men (age 64 ± 8 years) enrolled, comprising 59 men with T2DM compared with 20 nondiabetic age-matched controls. Longitudinal CMR with tagging showed an increase in ventricular mass (ΔLVMi = 13.47 ± 29.66 g/m2; p = 0.014) and a borderline increase in end-diastolic volume (ΔEDVi = 5.16 ± 14.71 ml/m2; p = 0.056) in men with T2DM. Cardiac strain worsened (Δσ = 1.52 ± 3.85%; p = 0.033) whereas torsion was unchanged (Δθ = 0.24 ± 4.04°; p = 0.737), revealing a loss of the adaptive equilibrium between strain and torsion. Contraction dynamics showed a decrease in the systolic time-to-peak (ΔTtP = −35.18 ± 28.81 ms; p < 0.001) and diastolic early recoil-rate (ΔRR = −20.01 ± 19.07 s-1; p < 0.001). The ejection fraction and metabolic parameters were unchanged. Circulating miR microarray revealed an up-regulation of miR122-5p. Network analysis predicted the matrix metalloproteinases (MMPs) MMP-16 and MMP-2 and their regulator (tissue inhibitors of metalloproteinases) as targets. In db/db mice we demonstrated that miR122-5p expression is associated with diabetic cardiomyopathy, that in the diabetic heart is overexpressed, and that, in vitro, it regulates MMP-2. Finally, we demonstrated that miR122-5p overexpression affects the extracellular matrix through MMP-2 modulation. Within 5 years of diabetic cardiomyopathy onset, increasing cardiac hypertrophy is associated with progressive impairment in strain, depletion of the compensatory role of torsion, and changes in viscoelastic contraction dynamics. These changes are independent of glycemic control and paralleled by the up-regulation of specific microRNAs targeting the extracellular matrix. (Cardiovascular Effects of Chronic Sildenafil in Men With Type 2 Diabetes [CECSID]; NCT00692237) [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: Bone marrow-derived cells contribute to tumor angiogenesis. Here, we demonstrate that monocytes expressing the Tie2 receptor (Tie2-expressing monocytes [TEMs]) (1) are a distinct hematopoietic lineage of proangiogenic cells, (2) are selectively recruited to spontaneous and orthotopic tumors, (3) promote angiogenesis in a paracrine manner, and (4) account for most of the proangiogenic activity of myeloid cells in tumors. Remarkably, TEM knockout completely prevented human glioma neovascularization in the mouse brain and induced substantial tumor regression. Besides TEMs and endothelial cells (ECs), Tie2 expression distinguished a rare population of tumor stroma-derived mesenchymal progenitors representing a primary source of tumor pericytes. Therefore, Tie2 expression characterizes three distinct cell types required for tumor neovascularization: ECs, proangiogenic cells of hematopoietic origin, and pericyte precursors of mesenchymal origin. [Copyright &y& Elsevier]

The cyclic guanosine monophosphate (cGMP) signaling system is one of the most prominent regulators of many physiopathological processes in humans and rodents. It has been strongly established as an accomplished cellular signal involved in the regulation of energy homeostasis and cell metabolism, and pharmacological enhancement of cGMP has shown beneficial effects in metabolic disorders models. cGMP intracellular levels are finely regulated by phosphodiesterases (PDEs). The main enzyme responsible for the degradation of cGMP is PDE5. Preclinical and clinical studies have shown that PDE5 inhibitors (PDE5i) have beneficial effects on improving insulin resistance and glucose metabolism representing a promising therapeutic strategy for the treatment of metabolic disorders. This review aims to describe the molecular basis underlying the use of PDE5i to prompt cell metabolism and summarize current clinical trials assessing the effects of PDE5i on glucose metabolism. [ABSTRACT FROM AUTHOR]

One of the major barriers to stable gene transfer is the development of anti-transgene immunity. In studies of gene therapy for inherited diseases, such as the hemophilias, successful outcome has been precluded by the development of immune responses against the vector and transgene product. Several factors contribute to the induction of an immune response following gene transfer. Chief amongst these factors is the expression of the transgene product within antigen presenting cells (APCs). Tissue-specific promoters (TSPs) can be used to prevent expression within APCs. Unfortunately, even using TSPs, neutralizing antibodies against the transgene product and immune-mediated vector clearance can often be observed. This may be due to off-target transcriptional activity of the promoter within APCs. Restricting transgene expression to a particular cell type may also decrease the potential efficacy of gene transfer by limiting the pool of cell types expressing the transgene.Recently, a complex network of gene regulation was uncovered, which is mediated by small non-coding RNAs known as microRNAs (miRNA). In an effort to develop an improved system for systemic gene transfer, we sought to exploit the endogenous miRNA machinery, which de-targets rather than targets gene expression and functions at the post-transcriptional level, for regulating transgene expression. A lentiviral vector (LV) encoding GFP was modified to contain a sequence with perfect complementarity to mir-142-3p, a hematopoietic-specific miRNA. Using this design, we reasoned that transgene expression would be prevented in hematopoietic lineages, while high levels of expression would be permitted in non- hematopoietic cells.Indeed, we demonstrated that by adding the mir-142-3p target sequence, GFP expression could be completely prevented in both intra- and extra-vascular hematopoietic lineages, while expression was maintained in non-hematopoietic cells (Brown et al. Nature Medicine in press). This expression profile, which could not be attained until now, enabled stable gene transfer (> 120 days) and prevented immune-mediate vector clearance in immunocompetent mice, thus overcoming a major hurdle to successful gene therapy. In sharp contrast, there was rejection of transgene positive cells when mice were treated with an LV encoding antigen under control of the hepatocyte-specific albumin promoter.The improved restriction of transgene expression from the miRNA- regulated LV compared to the albumin promoter likely occurred because post-transcriptional regulation can overcome off-target expression due to positional effects of insertion and/or imperfect reconstitution of the TSP. In addition to preventing an immune response, miRNA de-targeting, unlike TSPs, enabled transgene expression in a larger population of cells, including fibroblasts and endothelium.We are now expanding the use of this system for the treatment of hemophilia B. miRNA-regulated LVs encoding human Factor IX have been developed, and studies are now underway to evaluate the effectiveness of this strategy for long-term correction of hemophilia B mice.Molecular Therapy (2006) 13, S311–S311; doi: 10.1016/j.ymthe.2006.08.1224 [ABSTRACT FROM AUTHOR]

An abstract of the article "Tie2 Expression Defines an Integrated System of Cell Types Specifically Involved in Angiogenesis, and Provides a Platform for Targeted Gene Delivery to Tumors," by Michele De Palma and colleagues is presented.

Tumor-infiltrating myeloid cells are involved in crucial processes during tumor development. A subset of monocytes that express the angiopoietin receptor Tie2 play an important role in tumor angiogenesis. Selective depletion of these Tie2-expressing monocytes (TEMs) in tumor-bearing mice inhibits tumor angiogenesis and growth, suggesting that they might regulate angiogenic processes in tumors by providing paracrine support to nascent blood vessels. TEMs have also been identified in human blood and tumors. We discuss here the therapeutic opportunities emanating from the discovery of TEMs, which include the identification of new antitumor targets, monitoring TEMs as surrogate markers for clinical responses in cancer patients, and the possible use of TEMs as cellular vehicles for gene delivery to tumors. [Copyright &y& Elsevier]

Brain derived neurotrophic factor (BDNF) is a neurotrophin, expressed in the central nervous system and in peripheral tissues, that is regulated by the Gsα/cAMP pathway. In bone, it regulates osteogenesis and stimulates RANKL secretion and osteoclast formation in osteolytic tumors such as Multiple Myeloma. Fibrous dysplasia (FD) of bone is a rare genetic disease of the skeleton caused by gain-of-function mutations of the Gsα gene in which RANKL-dependent enhanced bone resorption is a major cause of bone fragility and clinical morbidity. We observed that BDNF transcripts are expressed in human FD lesions. Specifically, immunolocalization studies performed on biopsies obtained from FD patients revealed the expression of BDNF in osteoblasts and, to a lower extent, in the spindle-shaped cells within the fibrous tissue. Therefore, we hypothesized that BDNF can play a role in the pathogenesis of FD by stimulating RANKL secretion and bone resorption. To test this hypothesis, we used the EF1α-GsαR201C mouse model of the human disease (FD mice). Western blot analysis revealed a higher expression of BDNF in bone segments of FD mice compared to WT mice and the immunolabeling pattern within mouse FD lesions was similar to that observed in human FD. Treatment of FD mice with a monoclonal antibody against BDNF reduced the fibrous tissue along with the number of osteoclasts and osteoblasts within femoral lesions. These results reveal BDNF as a new player in the pathogenesis of FD and a potential molecular mechanism by which osteoclastogenesis may be nourished within FD bone lesions. They also suggest that BDNF inhibition may be a new approach to reduce abnormal bone remodeling in FD. [Display omitted] • BDNF is expressed in human Fibrous Dysplasia (FD) bone lesions • BDNF is preferentially expressed in osteoclast-rich human FD lesions • BDNF is expressed in FD bone lesions of EF1α-GsαR201C mice • Inhibition of BDNF reduces fibrous tissue, osteoclasts and osteoblasts in femoral FD lesions of EF1α-GsαR201C mice • Inhibition of BDNF reduces osteogenic differentiation of BMSCs isolated from EF1α-GsαR201C mice [ABSTRACT FROM AUTHOR]

Cushing's syndrome (CS), or chronic hypercortisolism, induces a variety of alterations in the immune system, often leading to severe clinical complications such as sepsis and opportunistic infections. Prolonged exposure to high levels of glucocorticoids (GC), changes in the circadian rhythm, and the comorbidities associated therewith all combine to cause profound changes in the immune profile of affected patients. While traditionally associated with generalized immune suppression, such changes actually comprise a much more complex scenario, sharing traits with chronic inflammatory disorders. Persistently increased levels of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNFα) and adipose tissue infiltration by immune cells lead to a chronic, nonresolving, inflammatory state. The combination of low-grade inflammation and selectively impaired immune response is thought to play a major role in the pathogenesis of clinical complications of CS, including diabetes, lipodystrophy, visceral adiposity, atherosclerosis, osteoporosis, and cognitive impairment. This dysregulation also explains rebound phenomena when CS is treated, involving new clinical complications sustained by an excessive immune response and autoimmunity. The aim of this review is to summarize the available evidence on the immune system in chronic hypercortisolism, while describing the main mechanisms of immune derangement and their role in the increased mortality and morbidity seen in this complex disease. A better understanding of immune system alterations in CS could help improve risk stratification, offer novel biomarkers, and provide the basis for more tailored therapies and post-remission follow-up. Increased GC exposure during the active phase of CS affects all immune cells, leading to overall immune suppression characterized by cell death, impaired immune regulation, and defective immune response. CS-induced lymphopenia (mainly of the CD4+ subset) with an altered CD4/CD8 ratio increases patients' susceptibility to viral infections. GCs alter the ratio of Th1/Th2 subpopulations, leading to apoptosis of mature T lymphocytes. The increased neutrophil count contributes to the establishment of a hypercoagulative state and the development of sepsis, both requiring active monitoring. The remission phase of CS can be associated with the unmasking of autoimmune diseases elicited by reactivation of the previously suppressed immune system, occasionally leading to an excessive response. [ABSTRACT FROM AUTHOR]

Genetic and molecular disparities between men and women have a role in the differing incidence, pathophysiology, clinical signs, and treatment outcome of several cancers. Sex differences in cancer incidence are attributed to regulation at the genetic/molecular level and to sex hormones that in turn modulate gene expression in various cancers. Sex differences in the incidence of cancer, its aggressiveness, and the disease prognosis have been reported for several types of cancer but little is known for pancreatic neuroendocrine neoplasms (PNENs). The aim of this Opinion article is to provide an overview of sex differences in PNENs in terms of epidemiology, pathophysiology, treatment responses, prognosis, and survival. This overview might allow better tailoring of the management of PNENs. Pancreatic neuroendocrine neoplasms (PNENs) are rare neoplasms with malignant potential whose incidence is on the rise; their clinical behavior mostly depends on the grade and the stage of the tumor. In addition, recent studies have emphasized a sex difference in PNENs in terms of clinical behavior. Male patients with PNENs have a worse prognosis, a greater risk of disease recurrence after curative surgery, and a higher incidence of complications than females. Conversely, female patients with PNENs have a longer survival and a better response to locoregional treatment of liver metastases than males. No significant sex differences have yet been demonstrated with regard to the response to treatment with somatostatin analogs, chemotherapy, peptide receptor radionuclide therapy, or molecularly targeted therapies. Considering the close relationship between sex and clinical behavior in PNENs, sex-driven management of PNENs appears to be needed. [ABSTRACT FROM AUTHOR]

We recently described a lineage of proangiogenic monocytes implicated in tumor angiogenesis. These cells, identified by expression of the angiopoietin receptor (Tie2-Expressing Monocytes, TEMs), are selectively recruited to tumors and promote angiogenesis in a paracrine manner by interacting with locally derived endothelial cells (De Palma et al., Cancer Cell, 2005).Because Tie2 is specifically expressed by TEMs among the progeny of hematopoietic stem cells (HSCs), transplanting HSCs transduced by lentiviral vectors (LVs) containing the Tie2 promoter provides for selective gene expression in TEMs. Here we explored the feasibility of targeted delivery of cancer gene therapy using TEMs as selective cellular vehicles.We transduced HSCs with LVs expressing the potent anti- angiogenic factor alpha-interferon (IFN) or GFP under the control of either the Tie2 or the ubiquitously active PGK promoter, and transplanted the transduced cells into nude mice. All PGK-IFN mice died of graft failure, indicating that ubiquitous expression of IFN in the HSC progeny was severely myelotoxic. In contrast, Tie2-GFP and Tie2-IFN mice were fully reconstituted by transduced HSCs. To compare TEM-mediated delivery with systemic expression of IFN, a group of Tie2-GFP mice received an intravascular injection of PGK-IFN LV, which led to sustained IFN expression in the plasma. Eight weeks post-transplant, we injected human glioma cells intracranially and monitored tumor growth by magnetic resonance imaging. Remarkably, while all other mice displayed large brain tumors, Tie2-IFN mice were tumor free 9 days after challenge. Ten days later, tumors became detectable also in Tie2-IFN mice, although they were markedly necrotic and smaller than in Tie2-GFP mice. Serial brain sections showed that tumors of Tie2-GFP mice were viable and highly vascularized, with GFP+ TEMs surrounding typical angiogenic vessels. By contrast, tumors grown in Tie2-IFN mice had reduced vascular area and exhibited normalized/regressing blood vessels. In these tumors, we observed overexpression of IFN in a subset of tumor-infiltrating myeloid cells, likely corresponding to TEMs, suggesting that targeted expression of IFN in close proximity to neoangiogenic vessels effectively inhibited endothelial cell proliferation. Surprisingly, systemic expression of IFN not only failed to inhibit tumor angiogenesis, but also induced body wasting and severe myelotoxicity.In conclusion, targeted delivery of IFN by TEMs achieved substantial anti-tumor activity in the absence of systemic toxicity, whereas ubiquitous expression in BM-derived cells or systemic delivery were not efficacious and were highly toxic. These results provide proof of principle of a new gene therapy paradigm in which ex vivo transduction of HSCs can be used to safely deliver potent anti-cancer molecules in a tumor-targeted fashion.Molecular Therapy (2006) 13, S24–S24; doi: 10.1016/j.ymthe.2006.08.072 [ABSTRACT FROM AUTHOR]

Summary: The use of type I interferons (IFNs) in cancer therapy has been limited by ineffective dosing and significant toxicity. Here, we exploited the tumor-homing ability of proangiogenic Tie2-expressing monocytes (TEMs) to deliver IFN-α to tumors. By transplanting hematopoietic progenitors transduced with a Tie2 promoter/enhancer-driven Ifna1 gene, we turned TEMs into IFN-α cell vehicles that efficiently targeted the IFN response to orthotopic human gliomas and spontaneous mouse mammary carcinomas and obtained significant antitumor responses and near complete abrogation of metastasis. TEM-mediated IFN-α delivery inhibited tumor angiogenesis and activated innate and adaptive immune cells but did not impair myelopoiesis and wound healing detectably. These results illustrate the therapeutic potential of gene- and cell-based IFN-α delivery and should allow the development of IFN treatments that more effectively treat cancer. [Copyright &y& Elsevier]