Gaetano Arcuri

Propionyl-l-Carnitine Improves Postischemic Blood Flow Recovery and Arteriogenetic Revascularization and Reduces Endothelial NADPH-Oxidase 4–Mediated Superoxide Production

Objective—The beneficial effect of the natural compound propionyl-l-carnitine (PLC) on intermittent claudication in patients with peripheral arterial disease is attributed to its anaplerotic function in ischemic tissues, but inadequate information is available concerning action on the vasculature. Methods and Results—We investigated the effects of PLC in rabbit hind limb collateral vessels after femoral artery excision, mouse dorsal air pouch, chicken chorioallantoic membrane, and vascular cells by angiographic, Doppler flow, and histomorphometrical and biomolecular analyses. PLC injection accelerated hind limb blood flow recovery after 4 days (P<0.05) and increased angiographic quadriceps collateral vascularization after 7 days (P<0.001) Histomorphometry confirmed the increased vascular area (P<0.05), with unchanged intramuscular capillary density. PLC-induced dilatative adaptation, and growth was found associated with increased inducible nitric oxide synthase and reduced arterial vascular endothelial growth factor and intracellular adhesion molecule-1 expression. PLC also increased vascularization in air pouch and chorioallantoic membrane (P<0.05), particularly in large vessels. PLC increased endothelial and human umbilical vascular endothelial cell proliferation and rapidly reduced inducible nitric oxide synthase and NADPH-oxidase 4–mediated reactive oxygen species production in human umbilical vascular endothelial cells; NADPH-oxidase 4 also regulated NF-&kgr;B–independent intracellular adhesion molecule-1 expression. Conclusion—Our results provided strong evidence that PLC improves postischemic flow recovery and revascularization and reduces endothelial NADPH-oxidase–related superoxide production. We recommend that PLC should be included among therapeutic interventions that target endothelial function.

Age-related increase of stem marker expression influences vascular smooth muscle cell properties

OBJECTIVE Aging represents a major risk factor for vascular disease development. With aging, changes of the biological properties of vascular smooth muscle cells (SMCs) are observed. Stem marker expression characterizes SMCs during developmental growth and atherosclerosis, but the contribution of SMCs with stem features to the age-related arterial remodeling remains largely unknown. METHODS AND RESULTS Immunostaining revealed rare vascular growth factor receptor-1(+) (flt-1(+)) and c-kit(+) cells in tunica media of grossly normal human young (17-30 years old) large arteries and 2-month old rat aorta, whereas CD133(+) cells were absent. In large arteries of human aged donors (64-77 years), flt-1(+) and c-kit(+) cell number increased in the intimal thickening and tunica media. Double immunofluorescence revealed that 30.6 ± 3% of flt-1(+) intimal cells co-expressed α-smooth muscle actin. Immunostaining, blots and RT-PCR documented the increased expression of flt-1 and c-kit in 20-24-month old rat aortic media. In vitro, old rat aortic SMCs proliferated and migrated more with greater flt-1, c-kit, NF-κB, VCAM-1, IAP-1 and MCP-1 levels and less α-smooth muscle actin and myosin compared to young SMCs. Old SMCs were also more susceptible to all-trans retinoic and NF-κB inhibition-induced apoptosis compared to young SMCs. Anti-flt-1 blocking antibody reduced migration and placental growth factor-induced but not serum and PDGF-BB-stimulated proliferation of old SMCs. CONCLUSIONS The increase of flt-1(+) and c-kit(+) SMCs characterizes large arteries of aged donors; the blocking of flt-1 signaling influences the behavior of old SMCs, suggesting that the accumulation of SMCs with a stem phenotype contributes to the age-dependent adverse arterial remodeling.

Interferon gamma upregulates frataxin and corrects the functional deficits in a Friedreich ataxia model

Friedreichs ataxia (FRDA) is the most common hereditary ataxia, affecting ∼3 in 100 000 individuals in Caucasian populations. It is caused by intronic GAA repeat expansions that hinder the expression of the FXN gene, resulting in defective levels of the mitochondrial protein frataxin. Sensory neurons in dorsal root ganglia (DRG) are particularly damaged by frataxin deficiency. There is no specific therapy for FRDA. Here, we show that frataxin levels can be upregulated by interferon gamma (IFNγ) in a variety of cell types, including primary cells derived from FRDA patients. IFNγ appears to act largely through a transcriptional mechanism on the FXN gene. Importantly, in vivo treatment with IFNγ increases frataxin expression in DRG neurons, prevents their pathological changes and ameliorates the sensorimotor performance in FRDA mice. These results disclose new roles for IFNγ in cellular metabolism and have direct implications for the treatment of FRDA.

Insulin-degrading enzyme (IDE): a novel heat shock-like protein.

Background: Insulin-degrading enzyme (IDE) is a highly conserved metallopeptidase initially described because of its ability to degrade insulin. Results: (i) IDE expression is stress-inducible; (ii) IDE concentration is up-regulated in some CNS tumors; (iii) IDE down-regulation impairs SHSY5Y cell proliferation/viability. Conclusion: IDE is a multifunctional protein. Significance: IDE is a novel HSP with important implications in cell growth regulation. Insulin-degrading enzyme (IDE) is a highly conserved zinc metallopeptidase that is ubiquitously distributed in human tissues, and particularly abundant in the brain, liver, and muscles. IDE activity has been historically associated with insulin and β-amyloid catabolism. However, over the last decade, several experimental findings have established that IDE is also involved in a wide variety of physiopathological processes, including ubiquitin clearance and Varicella Zoster Virus infection. In this study, we demonstrate that normal and malignant cells exposed to different stresses markedly up-regulate IDE in a heat shock protein (HSP)-like fashion. Additionally, we focused our attention on tumor cells and report that (i) IDE is overexpressed in vivo in tumors of the central nervous system (CNS); (ii) IDE-silencing inhibits neuroblastoma (SHSY5Y) cell proliferation and triggers cell death; (iii) IDE inhibition is accompanied by a decrease of the poly-ubiquitinated protein content and co-immunoprecipitates with proteasome and ubiquitin in SHSY5Y cells. In this work, we propose a novel role for IDE as a heat shock protein with implications in cell growth regulation and cancer progression, thus opening up an intriguing hypothesis of IDE as an anticancer target.

Sortilin expression is essential for pro-nerve growth factor-induced apoptosis of rat vascular smooth muscle cells.

Background Sortilin, a member of the Vps10p-domain receptor family, has been demonstrated a key regulator in mediating cellular response to pro-neurotrophins. In the present study, we investigated the role of sortilin in the apoptotic pathway of vascular smooth muscle cells. Methods and Principal Findings Immunohistochemistry revealed that sortilin was barely detectable in human and rat normal young vessels, while its expression was increased in human fibroatheromatous plaques. Sortilin immunodetection was also marked in the neointima of the rat aorta fifteen days after ballooning. In vitro, rat aortic intimal cells expressed higher sortilin levels than normal media SMCs; sortilin was distributed in the cytoplasm and in correspondence of the cell membrane. After 48 h, pro-nerve growth factor (proNGF) induced the strong dose-dependent increase of intimal cell apoptosis and the accumulation of sortilin protein. ProNGF was a more potent apoptotic inducer than equimolar or even higher concentration of NGF, whereas brain derived neutrotrophic factor was ineffective. Targeted interfering RNA-mediated sortilin reduction counteracted proNGF-induced apoptosis without affecting p75NTR expression. ProNGF-induced apoptosis was associated to NF-κB down-regulation and bax increase. Inhibition of NF-κB activity increased intimal cell apoptosis that did not further increase with the addition of proNGF. Conclusions Our results indicate that sortilin expression characterizes human atheromatous lesions and rat aortic post-injury neointima, and suggest that sortilin represents an important regulator of proNGF-induced SMC apoptosis and arterial remodeling.

Transglutaminase 2 as a biomarker of osteoarthritis: an update

Osteoarthritis is a progressive joint disease characterized by cartilage degradation and bone remodelling. Under physiologic conditions, articular cartilage displays a stable chondrocyte phenotype, whereas in osteoarthritis a chondrocyte hypertrophy develops near the sites of cartilage surface damage and associates to the pathologic expression of type X collagen. Transglutaminases (TGs) include a family of Ca2+-dependent enzymes that catalyze the formation of γ-glutamyl cross-links. Their substrates include a variety of intracellular and extracellular macromolecular components. TGs are ubiquitously and abundantly expressed and implicated in a variety of physiopathological processes. TGs activity is modulated by inflammatory cytokines. TG2 (also known as tissue transglutaminase) mediates the hypertrophic differentiation of joint chondrocytes and interleukin-1-induced calcification. Histomorphometrical and biomolecular investigations document increased TG2 expression in human and experimental osteoarthritis. Consequently, the level of TG2 expression may represent an adjuvant additional marker to monitor tissue remodelling occurring in osteoarthritic joint tissue. Experimental induction of osteoarthritis in TG2 knockout mice is followed from reduced cartilage destruction and increased osteophyte formation compared to wild-type mice, suggesting a different influence on joint bone and cartilage remodelling. The capacity of transamidation by TG2 to regulate activation of latent TGF-β seems to have a potential impact on the regulation of inflammatory response in osteoarthritic tissues. Additional studies are needed to define TG2-regulated pathways that are differently modulated in osteoblasts and chondrocytes during osteoarthritis.

Propionyl-L-Carnitine is Efficacious in Ulcerative Colitis Through its Action on the Immune Function and Microvasculature.

Objectives:Microvascular endothelial dysfunction characterizes ulcerative colitis (UC), the most widespread form of inflammatory bowel disease. Intestinal mucosal microvessels in UC display aberrant expression of cell adhesion molecules (CAMs) and increased inflammatory cell recruitment. Propionyl-L-carnitine (PLC), an ester of L-carnitine required for the mitochondrial transport of fatty acids, ameliorates propionyl-CoA bioavailability and reduces oxidative stress in ischemic tissues. The present study aimed to document the efficacy of anti-oxidative stress properties of PLC in counteracting intestinal microvascular endothelial dysfunction and inflammation.Methods:To evaluate the efficacy in vivo, we analyzed the effects in intestinal biopsies of patients with mild-to-moderate UC receiving oral PLC co-treatment and in rat TNBS-induced colitis; in addition, we investigated antioxidant PLC action in TNF-α-stimulated human intestinal microvascular endothelial cells (HIMECs) in vitro.Results:Four-week PLC co-treatment reduced intestinal mucosal polymorph infiltration and CD4+ lymphocytes, ICAM-1+ and iNOS+ microvessels compared with placebo-treated patients with UC. Oral and intrarectal administration of PLC but not L-carnitine or propionate reduced intestinal damage and microvascular dysfunction in rat TNBS-induced acute and reactivated colitis. In cultured TNF-α-stimulated HIMECs, PLC restored β-oxidation and counteracted NADPH oxidase 4-generated oxidative stress-induced CAM expression and leukocyte adhesion. Inhibition of β-oxidation by L-aminocarnitine increased reactive oxygen species production and PLC beneficial effects on endothelial dysfunction and leukocyte adhesion. Finally, PLC reduced iNOS activity and nitric oxide accumulation in rat TNBS-induced colitis and in HIMEC cultures.Conclusions:Our results show that the beneficial antioxidant effect of PLC targeting intestinal microvasculature restores endothelial β-oxidation and function, and reduces mucosal inflammation in UC patients.

Antioxidant Treatment Prevents Serum Deprivation- and TNF-α-Induced Endothelial Dysfunction through the Inhibition of NADPH Oxidase 4 and the Restoration of β-Oxidation

Aims: Oxidative stress plays a pivotal role in the impaired endothelial function occurring in vascular diseases. Antioxidant strategies induce a clinical advantage in patients with endothelial dysfunction and atherosclerosis and protect from oxidative damage, but the underlying molecular mechanisms have been poorly evaluated. The aim of this study was to analyze the effects and mechanisms of action of antioxidant regimens on endothelial function. Methods and Results: Antioxidant efficacy of N-acetylcysteine, ascorbic acid and propionyl-L-carnitine was evaluated in serum-deprived and TNF-α-stimulated human umbilical vein endothelial cells in vitro. Cell adhesion molecule (CAM) expression was evaluated by blot and real-time PCR, and inflammatory cytokine secretion was evaluated by ELISA; leukocyte adhesion and reactive oxygen species assays and NADPH oxidase 4 isoform (Nox4) expression analyses by blots were also performed. Antioxidant pretreatment restored serum-deprived and TNF-α-induced impaired mitochondrial β-oxidation by reducing flavin adenine dinucleotide level and counteracting increased CAM and Nox4 expression, leukocyte adhesion and inflammatory cytokine secretion. Specific inhibition by plumbagin and siNox4 prevented TNF-α- and serum deprivation-induced detrimental effects, confirming that endothelial oxidative stress and inflammation were Nox4 dependent. Conclusions: Our findings documented Nox4 as a main actor in oxidative stress-induced endothelial dysfunction and further clarify the molecular basis of antioxidant treatment efficacy.

Stem cell marker expression and proliferation and apoptosis of vascular smooth muscle cells

Vascular endothelial Flt-1 and other stem cell markers are variably expressed in vascular smooth muscle cells (SMCs) during normal and pathological conditions, but their biological role remains uncertain. In normal rat aorta, rare flt-1+ and c-kit+ SMCs were detected. Fifteen days after injury, 61.8+3.8, 45.7+3% of the intimal cells resulted flt-1+ and c-kit+ and expressed low level of alpha-smooth muscle actin; CD133+ cells were 5.6+0.7%. BrDU+/flt-1+ largely predominated in the neointima, whereas BrDU+/CD133+ cells were rare. Forty-five and sixty days after injury, intimal proliferation such as BrDU+ cells was greatly reduced. After sixty days, intimal stem marker expression had almost disappeared whereas alpha-smooth muscle actin was restored. Flk-1 and Oct-4 SMC immunodection was consistently negative. In vitro, intimal cells obtained fifteen days after injury exhibited an epithelioid phenotype and increased flt-1 and c-kit protein and mRNA and low smooth muscle markers compared to spindle-shaped medial and intimal SMCs obtained after sixty days. Epithelioid clones, independently from layer of origin, were similar in stem cell marker expression. The anti-flt-1 blocking antibody added to epithelioid SMC cultures reduced serum-deprived apoptosis and migration but not PDGF-BB-induced proliferation, and increased cell-populated collagen lattice contraction. In conclusion, stem marker expression in vascular SMCs was variable, chronologically regulated and prevailed in epithelioid populations and clones; among stem markers, flt-1 expression critically regulates intimal SMC response to microenviromental changes.

High insulin-induced down-regulation of Erk-1/IGF-1R/FGFR-1 signaling is required for oxidative stress-mediated apoptosis of adipose-derived stem cells.

Homeostasis of adipose tissue requires highly coordinated response between circulating factors and cell population. Human adult adipose‐derived stem cells (ASCs) display multiple differentiation properties and are sensitive to insulin stimulation. Insulin resistance and high level of circulating insulin characterize patients with type 2 diabetes and obesity. At physiological concentration, insulin promoted proliferation and survival of ASCs in vitro, whereas high insulin level induced their dose‐dependent proliferative arrest and apoptosis. Insulin‐induced apoptotic commitment depended on the down‐regulation of Erk‐1, insulin growth factor‐1 receptor (IGF‐1R), and fibroblast growth factor receptor‐1 (FGFR‐1)‐mediated signaling. Specific inhibition of Erk‐1/2, IGF‐1R, and FGFR activity promoted ASC apoptosis but did not increase insulin effects, whereas EGFR and ErbB2 inhibition potentiated insulin‐induced apoptosis. FGFRs and EGFR inhibition reduced ASC adipogenic differentiation, whereas Erk‐1/2 and IGF‐1R inhibition was ineffective. Insulin‐induced apoptosis associated to reactive oxygen species (ROS) accumulation and inhibition of NADPH oxidase 4 (Nox4) activity prevented ASC apoptosis. Moreover, specific inhibition of Erk‐1/2, IGF‐1R, and FGFR‐1 activity promoted ROS generation and this effect was not cumulative with that of insulin alone. Our data indicate that insulin concentration is a critical regulatory switch between proliferation and survival of ASCs. High insulin level‐induced apoptotic machinery involves Nox4‐generated oxidative stress and the down‐regulation of a complex receptor signaling, partially distinct from that influencing adipogenic differentiation of ASCs. J. Cell. Physiol. 229: 2077–2087, 2014.