Chronic Intermittent Hypoxia Facilitates the Development of Angiotensin II-Induced Abdominal Aortic Aneurysm in Male Mice.

Obstructive sleep apnea (OSA), characterized by episodes of intermittent hypoxia (IH), is highly prevalent in patients with abdominal aortic aneurysm (AAA). However, whether IH serves as an independent risk factor for AAA development remains to be investigated. Here, we determined the effects of chronic (6 months) IH on angiotensin (Ang II)-induced AAA development in C57BL/6J male mice, and IH underlying mechanisms in cultured vascular smooth muscle cells (SMCs). IH increased abdominal aortic diameter and the incidence of AAA in mice infused with Ang II as assessed by transabdominal ultrasound imaging. Importantly, IH with Ang II augmented aortic elastin degradation and expression of matrix metalloproteinase (MMP)s, mainly MMP8, MMP12 and a disintegrin and metalloproteinase-17 (ADAM17) as measured by histology and immunohistochemistry. Mechanistically, IH increased the activities of MMP2, MMP8, MMP9, MMP12, and ADAM17, while reducing the expression of the MMP regulator, reversion inducing cysteine rich protein with kazal motifs (RECK) in cultured SMCs. Aortic samples from human AAA were associated with decreased RECK and increased expression of ADAM17 and MMPs. These data suggest that IH promotes the development of AAA in association with an increased expression of MMPs and ADAM17, while decreased expression of RECK may be responsible for the increased protease activity. These findings support a potential causal link between OSA and AAA and provide a better understanding of the molecular mechanisms underlying the pathogenesis of AAA.

Synthetic Utilization of 2H-Heptafluoropropane: Ionic 1,4-Addition to Electron-Deficient Carbon-Carbon Unsaturated Bonds.

We have found a novel method for introducing heptafluoro-2-propyl CF(CF3)2 groups into carbon-carbon unsaturated bonds via a nucleophilic reaction using 2H-heptafluoropropane as the source of CF(CF3)2 groups. The reaction involves the nucleophilic addition of a heptafluoro-2-propyl anion, generated by treating 2H-heptafluoropropane with a fluoride ion, to various electron-deficient unsaturated compounds. This allows the easy synthesis of various aliphatic compounds containing heptafluoro-2-propyl groups.

Empagliflozin Reverses Oxidized LDL-Induced RECK Suppression, Cardiotrophin-1 Expression, MMP Activation, and Human Aortic Smooth Muscle Cell Proliferation and Migration.

Persistent oxidative stress and inflammation contribute causally to smooth muscle cell (SMC) proliferation and migration, the characteristic features of vascular proliferative diseases. Oxidatively modified low-density lipoproteins (OxLDL) elevate oxidative stress levels, inflammatory responses, and matrix metallopeptidase (MMP) activation, resulting ultimately in SMC migration, proliferation, and phenotype change. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK) is a membrane-anchored MMP inhibitor. Empagliflozin is an SGLT2 inhibitor and exerts pleiotropic cardiovascular protective effects, including antioxidant and anti-inflammatory effects. Here, we investigated (i) whether OxLDL regulates RECK expression, (ii) whether ectopic expression of RECK reverses OxLDL-induced SMC migration and proliferation, and (iii) whether pretreatment with empagliflozin reverses OxLDL-induced RECK suppression, MMP activation, and SMC migration, proliferation, and differentiation. Indeed, results show that OxLDL at pathophysiological concentration promotes SMC migration and proliferation via NF-κB/miR-30b-dependent RECK suppression. Moreover, OxLDL changed the SMC phenotype to a more pro-inflammatory type, and this effect is blunted by RECK overexpression. Further, treatment with empagliflozin reversed OxLDL-induced miR-30b induction, RECK suppression, MMP activation, SMC migration, proliferation, and proinflammatory phenotype changes. OxLDL-induced cardiotrophin (CT)-1 expression and CT-1 stimulated SMC proliferation and migration in part via leukemia inhibitory factor receptor (LIFR) and glycoprotein 130 (gp130). Ectopic expression of RECK inhibited these effects by physically associating with LIFR and gp130, as evidenced by immunoprecipitation/immunoblotting and double immunofluorescence. Importantly, empagliflozin inhibited CT-1-induced mitogenic and migratory effects. Together, these results suggest the therapeutic potential of sustaining RECK expression or empagliflozin in vascular diseases characterized by SMC proliferation and migration.

Synthesis and preclinical evaluation of a novel fluorine-18 labeled small-molecule PET radiotracer for imaging of CXCR3 receptor in mouse models of atherosclerosis.

BACKGROUND: CXCR3 is a chemokine receptor and is expressed in innate and adaptive immune cells. It promotes the recruitment of T-lymphocytes and other immune cells to the inflammatory site in response to the binding of cognate chemokines. Upregulation of CXCR3 and its chemokines has been found during atherosclerotic lesion formation. Therefore, detection of CXCR3 by positron emission tomography (PET) radiotracer can be a useful tool for detecting the development of atherosclerosis in a noninvasive manner. Herein, we report the synthesis, radiosynthesis, and characterization of a novel fluorine-18 (F-18, 18F) labeled small-molecule radiotracer for the imaging of the CXCR3 receptor in mouse models of atherosclerosis. RESULTS: The reference standard 1 and its precursor 9 were synthesized over 5 steps from starting materials in good to moderate yields. The measured Ki values of CXCR3A and CXCR3B were 0.81 ± 0.02 nM and 0.31 ± 0.02 nM, respectively. [18F]1 was prepared by a two-step radiosynthesis with a decay-corrected radiochemical yield of 13 ± 2%, radiochemical purity > 99%, and specific activity of 44.4 ± 3.7 GBq/µmol at the end of synthesis (n = 6). The baseline studies showed that [18F]1 displayed high uptake in the atherosclerotic aorta and brown adipose tissue in Apolipoprotein E (ApoE) knockout (KO) mice fed with a high-fat diet over 12 weeks. The uptake of [18F]1 in these regions was reduced significantly in self-blocking studies, demonstrating CXCR3 binding specificity. Contrary to this, no significant differences in uptake of [18F]1 in the abdominal aorta of C57BL/6 control mice fed with a normal diet were observed in both baseline and blocking studies, indicating increased CXCR3 expression in atherosclerotic lesions. Immunohistochemistry studies demonstrated that [18F]1-positive regions were correlated with CXCR3 expression, but some atherosclerotic plaques with significant size were not detected by [18F]1, and their CXCR3 expressions were minimal. CONCLUSION: [18F]1 was synthesized with good radiochemical yield and high radiochemical purity. In PET imaging studies, [18F]1 displayed CXCR3-specific uptake in the atherosclerotic aorta in ApoE KO mice. [18F]1 visualized CXCR3 expression in different regions in mice aligned with the tissue histology studies. Taken together, [18F]1 is a potential PET radiotracer for imaging CXCR3 in atherosclerosis.

Synthesis and preclinical evaluation of a novel fluorine-18 labeled small-molecule PET radiotracer for imaging of CXCR3 receptor in mouse models of atherosclerosis.

Background: CXCR3 is a chemokine receptor and is expressed on innate and adaptive immune cells. It promotes the recruitment of T-lymphocytes and other immune cells to the inflammatory site in response to the binding of cognate chemokines. Upregulation of CXCR3 and its chemokines has been found during atherosclerotic lesion formation. Therefore, the detection of CXCR3 by positron emission tomography (PET) radiotracer may be a useful tool to detect atherosclerosis development noninvasively. Herein, we report the synthesis, radiosynthesis, and characterization of a novel fluorine-18 (F-18, 18 F) labeled small-molecule radiotracer for the imaging of the CXCR3 receptor in mouse models of atherosclerosis. Methods: The reference standard ( S )-2-(5-chloro-6-(4-(1-(4-chloro-2-fluorobenzyl)piperidin-4-yl)-3-ethylpiperazin-1-yl)pyridin-3-yl)-1,3,4-oxadiazole ( 1 ) and its corresponding precursor 9 were synthesized using organic syntheses. The radiotracer [ 18 F] 1 was prepared in one-pot, two-step synthesis via aromatic 18 F-substitution followed by reductive amination. Cell binding assays were conducted using 1 , [ 125 I]CXCL10, and CXCR3A- and CXCR3B-transfected human embryonic kidney (HEK) 293 cells. Dynamic PET imaging studies over 90 min were performed on C57BL/6 and apolipoprotein E (ApoE) knockout (KO) mice that were subjected to a normal and high-fat diet for 12 weeks, respectively. Blocking studies were conducted with preadministration of the hydrochloride salt of 1 (5 mg/kg) to assess the binding specificity. Time-activity curves (TACs) for [ 18 F] 1 in both mice were used to extract standard uptake values (SUVs). Biodistribution studies were performed on C57BL/6 mice, and the distribution of CXCR3 in the abdominal aorta of ApoE KO mice was assessed by immunohistochemistry (IHC). Results: The reference standard 1 and its precursor 9 were synthesized over 5 steps from starting materials in good to moderate yields. The measured K i values of CXCR3A and CXCR3B were 0.81 ± 0.02 nM and 0.31 ± 0.02 nM, respectively. [ 18 F] 1 was prepared with decay-corrected radiochemical yield (RCY) of 13 ± 2%, radiochemical purity (RCP) >99%, and specific activity of 44.4 ± 3.7 GBq/µmol at the end of synthesis (EOS) ( n =6). The baseline studies showed that [ 18 F] 1 displayed high uptake in the atherosclerotic aorta and brown adipose tissue (BAT) in ApoE KO mice. The uptake of [ 18 F] 1 in these regions was reduced significantly in self-blocking studies, demonstrating CXCR3 binding specificity. Contrary to this, no significant differences in uptake of [ 18 F] 1 in the abdominal aorta of C57BL/6 mice were observed in both baseline and blocking studies, indicating increased CXCR3 expression in atherosclerotic lesions. IHC studies demonstrated that [ 18 F] 1 -positive regions were correlated with CXCR3 expression, but some atherosclerotic plaques with significant size were not detected by [ 18 F] 1 , and their CXCR3 expressions were minimal. Conclusion: The novel radiotracer, [ 18 F] 1 was synthesized with good RCY and high RCP. In PET imaging studies, [ 18 F] 1 displayed CXCR3-specific uptake in the atherosclerotic aorta in ApoE KO mice. [ 18 F] 1 visualized CXCR3 expression in different regions in mice is in line with the tissue histology studies. Taken together, [ 18 F] 1 is a potential PET radiotracer for the imaging of CXCR3 in atherosclerosis.

Insulin-like growth factor 1 reduces coronary atherosclerosis in pigs with familial hypercholesterolemia.

Although murine models of coronary atherosclerotic disease have been used extensively to determine mechanisms, limited new therapeutic options have emerged. Pigs with familial hypercholesterolemia (FH pigs) develop complex coronary atheromas that are almost identical to human lesions. We reported previously that insulin-like growth factor 1 (IGF-1) reduced aortic atherosclerosis and promoted features of stable plaque in a murine model. We administered human recombinant IGF-1 or saline (control) in atherosclerotic FH pigs for 6 months. IGF-1 decreased relative coronary atheroma in vivo (intravascular ultrasound) and reduced lesion cross-sectional area (postmortem histology). IGF-1 increased plaque's fibrous cap thickness, and reduced necrotic core, macrophage content, and cell apoptosis, consistent with promotion of a stable plaque phenotype. IGF-1 reduced circulating triglycerides, markers of systemic oxidative stress, and CXCL12 chemokine levels. We used spatial transcriptomics (ST) to identify global transcriptome changes in advanced plaque compartments and to obtain mechanistic insights into IGF-1 effects. ST analysis showed that IGF-1 suppressed FOS/FOSB factors and gene expression of MMP9 and CXCL14 in plaque macrophages, suggesting possible involvement of these molecules in IGF-1's effect on atherosclerosis. Thus, IGF-1 reduced coronary plaque burden and promoted features of stable plaque in a pig model, providing support for consideration of clinical trials.

Macrophage-Specific IGF-1 Overexpression Reduces CXCL12 Chemokine Levels and Suppresses Atherosclerotic Burden in Apoe-Deficient Mice.

OBJECTIVE: IGF-1 (insulin-like growth factor 1) exerts pleiotropic effects including promotion of cellular growth, differentiation, survival, and anabolism. We have shown that systemic IGF-1 administration reduced atherosclerosis in Apoe-/- (apolipoprotein E deficient) mice, and this effect was associated with a reduction in lesional macrophages and a decreased number of foam cells in the plaque. Almost all cell types secrete IGF-1, but the effect of macrophage-derived IGF-1 on the pathogenesis of atherosclerosis is poorly understood. We hypothesized that macrophage-derived IGF-1 will reduce atherosclerosis. Approach and Results: We created macrophage-specific IGF-1 overexpressing mice on an Apoe-/- background. Macrophage-specific IGF-1 overexpression reduced plaque macrophages, foam cells, and atherosclerotic burden and promoted features of stable atherosclerotic plaque. Macrophage-specific IGF1 mice had a reduction in monocyte infiltration into plaque, decreased expression of CXCL12 (CXC chemokine ligand 12), and upregulation of ABCA1 (ATP-binding cassette transporter 1), a cholesterol efflux regulator, in atherosclerotic plaque and in peritoneal macrophages. IGF-1 prevented oxidized lipid-induced CXCL12 upregulation and foam cell formation in cultured THP-1 macrophages and increased lipid efflux. We also found an increase in cholesterol efflux in macrophage-specific IGF1-derived peritoneal macrophages. CONCLUSIONS: Macrophage IGF-1 overexpression reduced atherosclerotic burden and increased features of plaque stability, likely via a reduction in CXCL12-mediated monocyte recruitment and an increase in ABCA1-dependent macrophage lipid efflux.

PET Imaging Radiotracers of Chemokine Receptors.

Chemokines and chemokine receptors have been recognized as critical signal components that maintain the physiological functions of various cells, particularly the immune cells. The signals of chemokines/chemokine receptors guide various leukocytes to respond to inflammatory reactions and infectious agents. Many chemokine receptors play supportive roles in the differentiation, proliferation, angiogenesis, and metastasis of diverse tumor cells. In addition, the signaling functions of a few chemokine receptors are associated with cardiac, pulmonary, and brain disorders. Over the years, numerous promising molecules ranging from small molecules to short peptides and antibodies have been developed to study the role of chemokine receptors in healthy states and diseased states. These drug-like candidates are in turn exploited as radiolabeled probes for the imaging of chemokine receptors using noninvasive in vivo imaging, such as positron emission tomography (PET). Recent advances in the development of radiotracers for various chemokine receptors, particularly of CXCR4, CCR2, and CCR5, shed new light on chemokine-related cancer and cardiovascular research and the subsequent drug development. Here, we present the recent progress in PET radiotracer development for imaging of various chemokine receptors.

Unusual cause of acute upper airway obstruction: spontaneous pharyngeal haematoma.

Spontaneous pharyngeal haematoma is a rare but life-threatening cause of acute upper airway obstruction, and the clinical manifestation may mimic haemoptysis. A 65-year-old man presented to our emergency department with symptoms of sore throat and haemoptysis. He had no medical history. At arrival, O2 saturation was 95% on 5 L/min of oxygen with a mask. Results of a blood examination including a coagulation test were normal. Laryngoscopy showed enlargement of the left pharynx and a narrowed airway. Contrast-enhanced CT showed extravascular leakage of contrast medium inside the left pharyngeal haematoma. Fortunately, the haematoma did not lead to airway obstruction, and it decreased spontaneously. We finally diagnosed this case as spontaneous pharyngeal haematoma. When we examine a patient with a symptom of haemoptysis accompanied by sore throat, it is necessary to consider pharyngeal haematoma and to prepare emergency airway protection for acute upper airway obstruction.

The SGLT2 inhibitor Empagliflozin attenuates interleukin-17A-induced human aortic smooth muscle cell proliferation and migration by targeting TRAF3IP2/ROS/NLRP3/Caspase-1-dependent IL-1ß and IL-18 secretion.

Chronic inflammation and persistent oxidative stress contribute to the development and progression of vascular proliferative diseases. We hypothesized that the proinflammatory cytokine interleukin (IL)-17A induces oxidative stress and amplifies inflammatory signaling in human aortic smooth muscle cells (SMC) via TRAF3IP2-mediated NLRP3/caspase-1-dependent mitogenic and migratory proinflammatory cytokines IL-1ß and IL-18. Further, we hypothesized that these maladaptive changes are prevented by empagliflozin (EMPA), an SGLT2 (Sodium/Glucose Cotransporter 2) inhibitor. Supporting our hypotheses, exposure of cultured SMC to IL-17A promoted proliferation and migration via TRAF3IP2, TRAF3IP2-dependent superoxide and hydrogen peroxide production, NLRP3 expression, caspase-1 activation, and IL-1ß and IL-18 secretion. Furthermore, NLRP3 knockdown, caspase-1 inhibition, and pretreatment with IL-1ß and IL-18 neutralizing antibodies and IL-18BP, each attenuated IL-17A-induced SMC migration and proliferation. Importantly, SMC express SGLT2, and pre-treatment with EMPA attenuated IL-17A/TRAF3IP2-dependent oxidative stress, NLRP3 expression, caspase-1 activation, IL-1ß and IL-18 secretion, and SMC proliferation and migration. Importantly, silencing SGLT2 attenuated EMPA-mediated inhibition of IL-17A-induced cytokine secretion and SMC proliferation and migration. EMPA exerted these beneficial antioxidant, anti-inflammatory, anti-mitogenic and anti-migratory effects under normal glucose conditions and without inducing cell death. These results suggest the therapeutic potential of EMPA in vascular proliferative diseases.

Insulin-Like Growth Factor I Prevents Cellular Aging via Activation of Mitophagy.

Mitochondrial dysfunction is a hallmark of cellular aging. Mitophagy is a critical mitochondrial quality control mechanism that removes dysfunctional mitochondria and contributes to cell survival. Insulin-like growth factor 1 (IGF-1) promotes survival of smooth muscle cells (SMCs), but its potential effect on cellular aging is unknown yet. We found that IGF-1 decreased cell senescence, prevented DNA telomere shortening, increased mitochondrial membrane potential, activated cytochrome C oxidase, and reduced mitochondrial DNA damage in long-term cultured (aged) aortic SMC, suggesting an antiaging effect. IGF-1 increased mitophagy in aged cells, and this was associated with decreased expression of cyclin-dependent kinase inhibitors p16 and p21 and elevated levels of Nrf2 and Sirt3, regulators of mitophagy and mitochondrial biogenesis. SiRNA-induced inhibition of either Nrf2 or Sirt3 blocked IGF-1-induced upregulation of mitophagy, suggesting that the Nrf2/Sirt3 pathway was required for IGF-1's effect on mitophagy. PINK1 is a master regulator of mitophagy. PINK1 silencing suppressed mitophagy and inhibited IGF-1-induced antiaging effects in aged SMC, consistent with an essential role of mitophagy in IGF-1's effect on cellular aging. Thus, IGF-1 inhibited cellular aging via Nrf2/Sirt3-dependent activation of mitophagy. Our data suggest that activation of IGF-1 signaling is a novel potential strategy to activate mitophagy and slow cellular aging.

Endothelial deficiency of insulin-like growth factor-1 receptor reduces endothelial barrier function and promotes atherosclerosis in Apoe-deficient mice.

Insulin-like growth factor-1 (IGF-1) decreases atherosclerosis in apolipoprotein E (Apoe)-deficient mice when administered systemically. However, mechanisms for its atheroprotective effect are not fully understood. We generated endothelium-specific IGF-1 receptor (IGF1R)-deficient mice on an Apoe-deficient background to assess effects of IGF-1 on the endothelium in the context of hyperlipidemia-induced atherosclerosis. Endothelial deficiency of IGF1R promoted atherosclerotic burden, when animals were fed on a high-fat diet for 12 wk or normal chow for 12 mo. Under the normal chow feeding condition, the vascular relaxation response to acetylcholine was increased in the endothelial IGF1R-deficient aorta; however, feeding of a high-fat diet substantially attenuated the relaxation response, and there was no difference between endothelial IGF1R-deficient and control mice. The endothelium and its intercellular junctions provide a barrier function to the vasculature. In human aortic endothelial cells, IGF-1 upregulated occludin, claudin 5, VE-cadherin, JAM-A, and CD31 expression levels, and vice versa, specific IGF1R inhibitor, picropodophyllin, an IGF1R-neutralizing antibody (αIR3), or siRNA to IGF1R abolished the IGF-1 effects on junction and adherens proteins, suggesting that IGF-1 promoted endothelial barrier function. Moreover, endothelial transwell permeability assays indicated that inhibition of IGF-1 signaling elevated solute permeability through the monolayer of human aortic endothelial cells. In summary, endothelial IGF1R deficiency increases atherosclerosis, and IGF-1 positively regulates tight junction protein and adherens junction protein levels and endothelial barrier function. Our findings suggest that the elevation of the endothelial junction protein level is, at least in part, the mechanism for antiatherogenic effects of IGF-1.NEW & NOTEWORTHY Endothelial insulin-like growth factor-1 (IGF-1) receptor deficiency significantly elevated atherosclerotic burden in apolipoprotein E-deficient mice, mediated at least in part by downregulation of intercellular junction proteins and, thus, elevated endothelial permeability. This study revealed a novel role for IGF-1 in supporting endothelial barrier function. These findings suggest that IGF-1's ability to promote endothelial barrier function may offer a novel therapeutic strategy for vascular diseases such as atherosclerosis.

Malignant Peritoneal Mesothelioma Presenting with Polymyalgia Rheumatica-like Syndrome.

A 30-year-old man was admitted to our hospital because of pain in his proximal extremities. The pain mimicked polymyalgia rheumatica (PMR) and it temporarily improved by a low dose of glucocorticoids, but his symptoms relapsed many times. After six years of glucocorticoid treatment, he developed abdominal pain and ascites, for which he was diagnosed with malignant peritoneal mesothelioma (MPM). His PMR-like symptoms improved with cytoreductive surgery and chemotherapy for MPM. Finally, we diagnosed this PMR-like syndrome to be paraneoplastic syndrome with MPM. Although cases of MPM complicated by PMR-like syndrome are rare, MPM should be taken into account in the differential diagnosis.

RECK suppresses interleukin-17/TRAF3IP2-mediated MMP-13 activation and human aortic smooth muscle cell migration and proliferation.

Sustained inflammation and matrix metalloproteinase (MMP) activation contribute to vascular occlusive/proliferative disorders. Interleukin-17 (IL-17) is a proinflammatory cytokine that signals mainly via TRAF3 Interacting Protein 2 (TRAF3IP2), an upstream regulator of various critical transcription factors, including AP-1 and NF-κB. Reversion inducing cysteine rich protein with kazal motifs (RECK) is a membrane-anchored MMP inhibitor. Here we investigated whether IL-17A/TRAF3IP2 signaling promotes MMP-13-dependent human aortic smooth muscle cell (SMC) proliferation and migration, and determined whether RECK overexpression blunts these responses. Indeed, IL-17A treatment induced (a) JNK, p38 MAPK, AP-1, NF-κB, and CREB activation, (b) miR-21 induction, (c) miR-27b and miR-320 inhibition, (d) MMP-13 expression and activation, (e) RECK suppression, and (f) SMC migration and proliferation, all in a TRAF3IP2-dependent manner. In fact, gain of TRAG3IP2 function, by itself, induced MMP-13 expression and activation, and RECK suppression. Furthermore, treatment with recombinant MMP-13 stimulated SMC migration in part via ERK activation. Importantly, RECK gain-of-function attenuated MMP-13 activity without affecting its mRNA or protein levels, and inhibited IL-17A- and MMP-13-induced SMC migration. These results indicate that increased MMP-13 and decreased RECK contribute to IL-17A-induced TRAF3IP2-dependent SMC migration and proliferation, and suggest that TRAF3IP2 inhibitors or RECK inducers have the potential to block the progression of neointimal thickening in hyperplastic vascular diseases.

Unusual cause of progressively impaired cognitive function: Mycobacterium avium complex meningoencephalitis.

Mycobacterium avium complex (MAC) is a rare cause of meningoencephalitis. Non-tuberculous mycobacterium meningoencephalitis including MAC meningoencephalitis is an important cause of rapidly progressive dementia. We present a case of MAC meningoencephalitis in an immunosuppressed woman who had progressively impaired cognitive function. An 83-year-old woman who had been taking glucocorticoid for myasthenia gravis developed cognitive dysfunction and visual hallucinations over a period of 2 weeks. Cerebrospinal fluid (CSF) findings were normal, but MAC was positive in CSF culture and M. avium and M. intracellulare were identified by PCR. She was treated with multiple antimycobacterial agents and her symptoms fully recovered. MAC meningoencephalitis is an unusual cause of progressively impaired cognitive function. The possibility of mycobacterial central nervous system infection cannot be excluded by normal CSF findings.

Minocycline inhibits PDGF-BB-induced human aortic smooth muscle cell proliferation and migration by reversing miR-221- and -222-mediated RECK suppression.

Minocycline, a tetracycline antibiotic, is known to exert vasculoprotective effects independent of its anti-bacterial properties; however the underlying molecular mechanisms are not completely understood. Reversion Inducing Cysteine Rich Protein with Kazal Motifs (RECK) is a cell surface expressed, membrane anchored protein, and its overexpression inhibits cancer cell migration. We hypothesized that minocycline inhibits platelet-derived growth factor (PDGF)-induced human aortic smooth muscle cell (SMC) proliferation and migration via RECK upregulation. Our data show that the BB homodimer of recombinant PDGF (PDGF-BB) induced SMC migration and proliferation, effects significantly blunted by pre-treatment with minocycline. Further investigations revealed that PDGF-BB induced PI3K-dependent AKT activation, ERK activation, reactive oxygen species generation, Nuclear Factor-κB and Activator Protein-1 activation, microRNA (miR)-221 and miR-222 induction, RECK suppression, and matrix metalloproteinase (MMP2 and 9) activation, effects that were reversed by minocycline. Notably, minocycline induced RECK expression dose-dependently within the therapeutic dose of 1-100 µM, and silencing RECK partially reversed the inhibitory effects of minocycline on PDGF-BB-induced MMP activation, and SMC proliferation and migration. Further, targeting MMP2 and MMP9 blunted PDGF-BB-induced SMC migration. Together, these results demonstrate that minocycline inhibits PDGF-BB-induced SMC proliferation and migration by restoring RECK, an MMP inhibitor. These results indicate that the induction of RECK is one of the mechanisms by which minocycline exerts vasculoprotective effects.

IGF-1 and cardiovascular disease.

Atherosclerosis is an inflammatory arterial pathogenic condition, which leads to ischemic cardiovascular diseases, such as coronary artery disease and myocardial infarction, stroke, and peripheral arterial disease. Atherosclerosis is a multifactorial disorder and its pathophysiology is highly complex. Changes in expression of multiple genes coupled with environmental and lifestyle factors initiate cascades of adverse events involving multiple types of cells (e.g. vascular endothelial cells, smooth muscle cells, and macrophages). IGF-1 is a pleiotropic factor, which is found in the circulation (endocrine IGF-1) and is also produced locally in arteries (endothelial cells and smooth muscle cells). IGF-1 exerts a variety of effects on these cell types in the context of the pathogenesis of atherosclerosis. In fact, there is an increasing body of evidence suggesting that IGF-1 has beneficial effects on the biology of atherosclerosis. This review will discuss recent findings relating to clinical investigations on the relation between IGF-1 and cardiovascular disease and basic research using animal models of atherosclerosis that have elucidated some of the mechanisms underlying atheroprotective effects of IGF-1.