Secreted Protein Acidic And Rich In Cysteine Levels Research Articles

Exploring the roles of SPARC as a proinflammatory factor and its potential as a novel therapeutic target against cardiovascular disease.

Cardiovascular disease (CVD) is a leading cause of death worldwide, and the number of CVD patients continues to increase despite extensive research and developments in this field. Chronic inflammation is a pivotal pathological component of CVD, and unveiling new proinflammatory factors will help devise novel preventive and therapeutic strategies. The extracellular matrix (ECM) not only provides structural support between cells, but also contributes to cellular functions. Secreted protein acidic and rich in cysteine (SPARC) is a collagen-binding matricellular protein that is particularly induced during development and tissue remodeling. A proinflammatory role for SPARC has been demonstrated in various animal models, such as in the lipopolysaccharide-induced footpad model and dextran sodium sulfate-induced colitis model. Recent clinical studies reported a positive correlation between elevated plasma SPARC levels and hypertension, obesity, and the inflammatory marker high-sensitive C-reactive protein. In addition, SPARC gene deletion attenuates the cardiac injury induced by aging, myocardial infarction, and pressure-load, suggesting that SPARC has deleterious effects on CVD. This review summarizes the regulatory and proinflammatory mechanisms of SPARC on CVD, chronic kidney disease (CKD) and cerebrovascular disease, and discusses the rationale behind measuring SPARC as a biomarker of CVD, and the effects of inhibition of SPARC in the prevention and treatment of CVD.

Alteration of BDNF, SPARC, FGF-21, and GDF-15 circulating levels after 1 year of anti-obesity treatments and their association with 1-year weight loss

PurposeEmerging evidence revealed that brain-derived neurotrophic factor (BDNF), secreted protein acidic and rich in cysteine (SPARC), fibroblast growth factor 21(FGF-21) and growth differentiation factor 15 (GDF-15) are involved in energy metabolism and body weight regulation. Our study aimed at examining their association with BMI, their alterations after anti-obesity treatments, and their association with 1-year weight loss.MethodsA prospective observational study of 171 participants with overweight and obesity and 46 lean controls was established. All participants received lifestyle educational intervention (LEI) with or without anti-obesity treatments (LEI + bariatric/metabolic surgery, n = 41; LEI + topiramate, n = 46; LEI + liraglutide, n = 31; LEI + orlistat, n = 12; and LEI alone, n = 41). Anthropometric and metabolic parameters, insulin sensitivity, C-reactive protein (CRP), fasting plasma levels of BDNF, SPARC, GDF-15, and FGF-21 were measured at baseline and 1 year.ResultsMultiple linear regression showed that fasting levels of SPARC, FGF-21, and GDF-15 were significantly associated with baseline BMI after adjustment for age and sex. At 1 year, the average weight loss was 4.8% in the entire cohort with a significant improvement in glycemia, insulin sensitivity, and CRP. Multiple linear regression adjusted for age, sex, baseline BMI, type of treatment, and presence of T2DM revealed that the decrease in log10FGF-21 and log10GDF-15 at 1 year from baseline was significantly associated with a greater percentage of weight loss at 1 year.ConclusionsThis study highlights the association of SPARC, FGF-21, and GDF-15 levels with BMI. Decreased circulating levels of GDF-15 and FGF-21 were associated with greater weight loss at 1 year, regardless of the types of anti-obesity modalities.

Plasma SPARC Elevation in Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage.

Matricellular proteins have been implicated in pathologies after subarachnoid hemorrhage (SAH). To find a new therapeutic molecular target, the present study aimed to clarify the relationships between serially measured plasma levels of a matricellular protein, secreted protein acidic and rich in cysteine (SPARC), and delayed cerebral ischemia (DCI) in 117 consecutive aneurysmal SAH patients with admission World Federation of Neurological Surgeons (WFNS) grades I-III. DCI developed in 25 patients with higher incidences of past history of hypertension and dyslipidemia, preoperative WFNS grade III, modified Fisher grade 4, spinal drainage, and angiographic vasospasm. Plasma SPARC levels were increased after SAH, and significantly higher in patients with than without DCI at days 7-9, and in patients with VASOGRADE-Yellow compared with VASOGRADE-Green at days 1-3 and 7-9. However, there were no relationships between plasma SPARC levels and angiographic vasospasm. Receiver-operating characteristic curves differentiating DCI from no DCI determined the cut-off value of plasma SPARC ≥ 82.1ng/ml at days 7 - 9 (sensitivity, 0.800; specificity, 0.533; and area under the curve, 0.708), which was found to be an independent determinant of DCI development in multivariate analyses. This is the first study to show that SPARC is upregulated in peripheral blood after SAH, and that SPARC may be involved in the development of DCI without angiographic vasospasm in a clinical setting.

Growth hormone/IGF-I-dependent signaling restores decreased expression of the myokine SPARC in aged skeletal muscle

Skeletal muscle exerts many beneficial effects on the human body including the contraction-dependent secretion of peptides termed myokines. We have recently connected the myokine secreted protein acidic and rich in cysteine (SPARC) to the formation of intramuscular adipose tissue (IMAT) in skeletal muscle from aged mice and humans. Here, we searched for inducers of SPARC in order to uncover novel treatment approaches for IMAT. Endurance exercise in mice as well as forskolin treatment in vitro only modestly activated SPARC levels. However, through pharmacological treatments in vitro, we identified IGF-I as a potent inducer of SPARC expression in muscle cells, likely through a direct activation of its promoter via phosphatidylinositol 4,5-bisphospate 3-kinase (PI3K)-dependent signaling. We employed two different mouse models of growth hormone (GH)/IGF-I deficiency to solidify our understanding of the relationship between IGF-I and SPARC in vivo. GH administration robustly increased intramuscular SPARC levels (3.5-fold) in GH releasing hormone receptor-deficient mice and restored low intramuscular SPARC expression in skeletal muscle from aged mice. Intramuscular glycerol injections induced higher levels of adipocyte markers (adiponectin, perilipin) in aged compared to young mice, which was not prevented by GH treatment. Our study provides a roadmap for the study of myokine regulation during aging and demonstrates that the GH/IGF-I axis is critical for SPARC expression in skeletal muscle. Although GH treatment did not prevent IMAT formation in the glycerol model, targeting SPARC by exercise or by activation of IGF-I signaling might offer a novel therapeutic strategy against IMAT formation during aging.Key messagesIGF-I regulates the myokine SPARC in muscle cells directly at the promoter level.GH/IGF-I is able to restore the decreased SPARC levels in aged skeletal muscle.The glycerol model induces higher adipocyte markers in aged compared to young muscle.GH treatment does not prevent IMAT formation in the glycerol model.

Secreted Protein Acidic and Rich in Cysteine Mediates the Development and Progression of Diabetic Retinopathy.

BackgroundsDiabetic retinopathy (DR) is one of the most severe microvascular complications of diabetes mellitus (DM). Secreted protein acidic and rich in cysteine (SPARC) has been found to play an important role in many diseases, but its role and mechanism in DR remain unknown.MethodsWe studied the role of SPARC and integrin β1 in vascular pathophysiology and identified potential therapeutic translation. The SPARC levels were tested in human serum and vitreous by ELISA assay, and then the Gene Expression Omnibus (GEO) dataset was used to understand the key role of the target gene in DR. In human retinal capillary endothelial cells (HRCECs), we analyzed the mRNA and protein level by RT-PCR, immunohistochemistry, and Western blotting. The cell apoptosis, cell viability, and angiogenesis were analyzed by flow cytometry, CCK-8, and tube formation.ResultsIn this study, we investigated the role of SPARC in the development and progression of human DR and high glucose-induced HRCEC cells and found that the SPARC-ITGB1 signaling pathway mimics early molecular and advanced neurovascular pathophysiology complications of DR. The result revealed that DR patients have a high-level SPARC expression in serum and vitreous. Knockdown of SPARC could decrease the expressions of inflammatory factors and VEGFR, inhibit cell apoptosis and angiogenesis, and increase cell viability by regulating integrin β1 in HRCECs.ConclusionSPARC promotes diabetic retinopathy via the regulation of integrin β1. The results of this study can provide a potential therapeutic application for the treatment of DR.

SPARC, a Novel Regulator of Vascular Cell Function in Pulmonary Hypertension.

Pulmonary hypertension (PH) is a life-threatening disease, characterized by excessive pulmonary vascular remodeling, leading to elevated pulmonary arterial pressure and right heart hypertrophy. PH can be caused by chronic hypoxia, leading to hyper-proliferation of pulmonary arterial smooth muscle cells (PASMCs) and apoptosis-resistant pulmonary microvascular endothelial cells (PMVECs). On reexposure to normoxia, chronic hypoxia-induced PH in mice is reversible. In this study, the authors aim to identify novel candidate genes involved in pulmonary vascular remodeling specifically in the pulmonary vasculature. After microarray analysis, the authors assessed the role of SPARC (secreted protein acidic and rich in cysteine) in PH using lung tissue from idiopathic pulmonary arterial hypertension (IPAH) patients, as well as from chronically hypoxic mice. In vitro studies were conducted in primary human PASMCs and PMVECs. In vivo function of SPARC was proven in chronic hypoxia-induced PH in mice by using an adeno-associated virus-mediated Sparc knockdown approach. C57BL/6J mice were exposed to normoxia, chronic hypoxia, or chronic hypoxia with subsequent reexposure to normoxia for different time points. Microarray analysis of the pulmonary vascular compartment after laser microdissection identified Sparc as one of the genes downregulated at all reoxygenation time points investigated. Intriguingly, SPARC was vice versa upregulated in lungs during development of hypoxia-induced PH in mice as well as in IPAH, although SPARC plasma levels were not elevated in PH. TGF-β1 (transforming growth factor β1) or HIF2A (hypoxia-inducible factor 2A) signaling pathways induced SPARC expression in human PASMCs. In loss of function studies, SPARC silencing enhanced apoptosis and reduced proliferation. In gain of function studies, elevated SPARC levels induced PASMCs, but not PMVECs, proliferation. Coculture and conditioned medium experiments revealed that PMVECs-secreted SPARC acts as a paracrine factor triggering PASMCs proliferation. Contrary to the authors' expectations, in vivo congenital Sparc knockout mice were not protected from hypoxia-induced PH, most probably because of counter-regulatory proproliferative signaling. However, adeno-associated virus-mediated Sparc knockdown in adult mice significantly improved hemodynamic and cardiac function in PH mice. This study provides evidence for the involvement of SPARC in the pathogenesis of human PH and chronic hypoxia-induced PH in mice, most likely by affecting vascular cell function.

SPARC Overexpression Promotes Liver Cancer Cell Proliferation and Tumor Growth.

Background: Secreted protein acidic and rich in cysteine (SPARC) plays an important role in cancer development. The roles of SPARC in the liver hepatocellular carcinoma (LIHC) are unclear. Methods: GEPIA2 and UALCAN were used to analyze the SPARC mRNA expression levels in LIHC based on the TCGA database. The GEO database was used to verify the analysis results. Immunohistochemical (IHC) analysis was used to investigate the SPARC protein levels in LIHC tissues. The Kaplan–Meier (KM) plotter was used to analyze the correlation between SPARC and prognosis. The serum SPARC levels were measured by ELISA. CCK8 and murine xenograft models were used to investigate the effect of SPARC on the liver cancer growth in vitro and in vivo. SPARC-correlated genes were screened by LinkedOmics. Results: Based on the TCGA and GEO databases, the analysis showed that the SPARC mRNA expression levels were increased in tumor tissues and peripheral blood mononuclear cell (PBMC) from LIHC compared to normal controls. The IHC analysis showed an increased level of SPARC in LIHC tissues compared to adjacent non-tumor tissues. However, we found that the serum SPARC levels were lower in LIHC than those in healthy controls. The KM plotter showed that there was no significant correlation between the SPARC mRNA levels and overall survival. However, in sorafenib-treated LIHC patients, the high SPARC expression predicts favorable prognosis. Furthermore, the endogenous SPARC overexpression promotes liver cancer cell proliferation in vitro and tumor growth in vivo, while there was no significant effect of exogenous SPARC treatment on liver cancer cell proliferation. Function enrichment analysis of SPARC-correlated genes indicated a critical role of interaction with an extracellular matrix in SPARC-promoting cancer cell proliferation. Conclusion: SPARC mRNAs were increased in LIHC tumor tissues, and SPARC overexpression may promote the liver cancer growth. Further studies are needed to clarify the potential prognostic value of SPARC, both in tissues and in circulation.

Sedentary time, physical activity, and serum SPARC in a middle-aged population

ABSTRACT The influence of habitual physical activity (PA) on the circulating levels of secreted protein acidic and rich in cysteine (SPARC) remains unclear. The purpose of the current study was to clarify the effects of sedentary time, light-intensity PA (LPA), and moderate- to vigorous-intensity PA (MVPA) on the serum SPARC in a general middle-aged population. The current study is a cross-sectional study of 4,000 men and 6,040 women (40–69 years). Sedentary time, LPA, and MVPA were objectively measured by an accelerometer. The serum SPARC concentration was measured by enzyme-linked immunosorbent assay. Using an isotemporal substitution model, cross-sectional associations of replacing sedentary time with either LPA or MVPA on serum SPARC levels were analysed according to sex. Interactions with subject characteristics, such as the body mass index (BMI), smoking, and alcohol consumption, were also examined. In men, replacing 60 min of sedentary time with 60 min of MVPA was significantly associated with 23 ng/mL lower serum SPARC levels (confidence interval: −43, −2) after adjusting for confounders, including the BMI (P = 0.028). A significant interaction between replacing sedentary behaviour with LPA and the BMI on SPARC was detected in women (P = 0.029), although the stratified associations for each BMI level (<25 or ≥25 kg/m2) did not reach significance. The current study suggests that replacing sedentary time with MVPA is associated with reduced serum SPARC levels in middle-aged men, but not in women. In addition, a potential interaction between LPA and the BMI on SPARC was also found in women. Highlights An isotemporal substitution analysis showed that replacing sedentary behaviour with moderate- to vigorous-intensity physical activity (MVPA) is associated with decreased serum SPARC levels in men. Such an inverse association between replacing sedentary behaviour with MVPA and the SPARC levels was not observed in women. A potential interaction between replacing sedentary behaviour with light-intensity PA and the body mass index on the serum SPARC levels was also found in women.

Effects of exercise intensity and duration on a myokine, secreted protein acidic and rich in cysteine

ABSTRACT Secreted protein acidic and rich in cysteine (SPARC), an exercise-induced myokine, has been suggested as a potential endogenous factor that suppresses colon tumorigenesis. However, the effects of different exercise protocols on circulating SPARC levels are unclear. The main purpose of this study was to examine the effects of both exercise intensity and duration on circulating SPARC levels. This study also examined the relationship between responsiveness of SPARC levels and physical characteristics, including body composition and skeletal muscle function. Nineteen healthy adult men participated in four experimental interventions: two 30-min exercises at workloads corresponding to 60% (W60) and 40% (W40) peak oxygen uptake (VO2peak), a 45-min session of W40, and a 30-min session of complete rest. Blood SPARC and lactate concentrations were measured before and after each session. Only W60 significantly increased serum SPARC levels (p < 0.05), and a significant correlation was found between changes in SPARC levels and lactate concentrations (r = 0.411, p < 0.05). The relative changes in SPARC levels during W60 demonstrated significant positive correlations with skeletal muscle mass and knee extensor muscle strength (both p < 0.05). The increase in serum SPARC levels might be mediated by lactate accumulation and might not, hence, be induced during exercise at the intensity of the first ventilatory threshold levels even though the duration is prolonged. Our results provide fundamental insight into exercise prescription of both exercise intensity and duration for SPARC response, leading to a better understanding of the preventive effects of exercise on colon cancer. Highlight This study found that the increase in serum secreted protein acidic and rich in cysteine (SPARC) levels might be mediated by lactate accumulation and might, hence, be influenced by exercise intensity rather than exercise duration. An association was found between SPARC response to exercise and skeletal muscle mass. Our results provide a better understanding of the preventive effects of exercise on colon cancer.

Effect of Serum SPARC Levels on Survival in Patients with Digestive Tract Cancer: A Post Hoc Analysis of the AMATERASU Randomized Clinical Trial.

Observational studies suggest that physical activity may improve, whereas sarcopenia may worsen the survival of cancer patients. It has been suggested that secreted protein acidic and rich in cysteine (SPARC), one of the myokines that is secreted into the bloodstream by muscle contraction, has tumor-suppressive effects. Based on the hypothesis that serum SPARC level may be a potential prognostic biomarker, a post hoc analysis of the AMATERASU randomized, double-blind, placebo-controlled trial of postoperative oral vitamin D supplementation (2000 IU/day) in patients with stage I–III digestive tract cancer from the esophagus to the rectum (UMIN000001977) was conducted with the aim of exploring the association between serum SPARC levels after operation and survival. On multivariate analyses adjusting serum 25-hydroxyvitamin D, vitamin D supplementation, sarcopenia, body mass index, age, sex, cancer loci, stage, and adjuvant chemotherapy, patients with SPARC levels lower than the median level had a significantly higher risk for death than those with higher levels (hazard ratio, 2.25; 95% confidence interval, 1.25–4.05; p = 0.007), whereas there were no significant associations with other outcomes including recurrence. However, on the same multivariate analyses, sarcopenia was not a risk factor for death and/or relapse. These results suggest that serum SPARC levels may be a potential biomarker for death but not cancer relapse.

SPARC is required for the maintenance of glucose homeostasis and insulin secretion in mice.

Obesity, metabolic syndrome, and type 2 diabetes, three strongly interrelated diseases, are associated to increased morbidity and mortality worldwide. The pathogenesis of obesity-associated disorders is still under study. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein expressed in many cell types including adipocytes, parenchymal, and non-parenchymal hepatic cells and pancreatic cells. Studies have demonstrated that SPARC inhibits adipogenesis and promotes insulin resistance; in addition, circulating SPARC levels were positively correlated with body mass index in obese individuals. Therefore, SPARC is being proposed as a key factor in the pathogenesis of obesity-associated disorders. The aim of this study is to elucidate the role of SPARC in glucose homeostasis. We show here that SPARC null (SPARC-/-) mice displayed an abnormal insulin-regulated glucose metabolism. SPARC-/- mice presented an increased adipose tissue deposition and an impaired glucose homeostasis as animals aged. In addition, the absence of SPARC worsens high-fat diet-induced diabetes in mice. Interestingly, although SPARC-/- mice on high-fat diet were sensitive to insulin they showed an impaired insulin secretion capacity. Of note, the expression of glucose transporter 2 in islets of SPARC-/- mice was dramatically reduced. The present study provides the first evidence that deleted SPARC expression causes diabetes in mice. Thus, SPARC deficient mice constitute a valuable model for studies concerning obesity and its related metabolic complications, including diabetes.

Diagnostic and Prognostic Performance of Secreted Protein Acidic and Rich in Cysteine (SPARC) Assay for Detecting Primary and Recurrent Urinary Bladder Cancer.

To evaluate the diagnostic and prognostic performance of Secreted Protein Acidic and Rich in Cysteine (SPARC) in detecting urinary bladder cancer (UBC). The Integrated Study on Bladder Cancer (n = 571; mean age:69.4±12.2 years) evaluates cross-sectionally SPARC diagnostic performance in primary (n = 264) and recurrent (n = 307) UBC. SPARC prognostic performance is evaluated in a nested cohort (n = 250) prospectively followed for 80 months to detect tumor relapse, recurrence and/or progression. Baseline urine samples are analyzed blindly using a commercially available SPARC ELISA assay, characterized for its analytical performance according to clinical test regulatory requirements (R&D Manufactures Inc.). While higher mean SPARC levels are detected in primary (p = 0.008) and recurrent (p < 0.0001) UBC, the assay has limited diagnostic performance (AUC:0.593; 95% CI:0.524-0.663). SPARC positive patients undergoing disease monitoring are more likely to develop tumor relapse (age and gender Adj. HR:1.52; 95% CI:1.04-2.22) and progression (Adj. HR:1.83; 95% CI:1.02-3.27). However, prognostic performance is affected by hematuria. SPARC diagnostic performance for detecting UBC appears insufficient for clinical implementation. In patients undergoing disease monitoring, SPARC is a promising prognostic marker for tumor relapse and/or progression, but is affected by hematuria.

Downregulation of SPARC Is Associated with Epithelial-Mesenchymal Transition and Low Differentiation State of Biliary Tract Cancer Cells

Background: Biliary tract cancers (BTCs) have a poor prognosis. BTCs are characterized by a prominent desmoplastic reaction which possibly contributes to the aggressive phenotype of this tumor. The desmoplastic reaction includes excessive production and deposition of extracellular matrix proteins such as periostin, secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1, as well as accumulation of α-smooth muscle actin-positive cancer-associated fibroblasts and immune cells, secreting growth factors and cytokines including transforming growth factor (TGF)-β. In the present study, we investigated the expression of SPARC in BTC as well as its possible regulation by TGF-β. Methods: Expression levels of Sparc, TGF-β1 and its receptor ALK5 were evaluated by quantitative real-time PCR in 6 biliary tract cell lines as well as 1 immortalized cholangiocyte cell line (MMNK-1). RNAs from tumor samples of 7 biliary tract cancer patients were analyzed for expression of Sparc, TGF-β type II receptor (TbRII) as well as Twist and ZO-1. MMNK-1 cells were stimulated with TGF-β for 24 h, and Sparc, ZO-1 and E-Cadherin expressions were determined. The presence of SPARC protein was analyzed by immunohistochemistry in tumor specimens from 10 patients. Results: When comparing basal Sparc transcript levels in diverse BTC cell lines to MMNK-1 cells, we found that it was strongly downregulated in all cancer cell lines. The remaining expression levels were higher in highly differentiated cell lines (CCSW1, MZChA1, MZChA2 and TFK-1) than in less differentiated and undifferentiated ones (BDC, SKChA1). Expression of Sparc in BTC patient samples showed a significant positive correlation with expression of the epithelial marker ZO-1. In contrast, the mesenchymal marker Twist and the TbRII showed a trend of negative correlation with expression of Sparc in these samples. TGF-β exposure significantly downregulated Sparc expression in MMNK-1 cholangiocytes in vitro in parallel to downregulation of epithelial markers (E-Cadherin and ZO-1). Finally, SPARC immunostaining was performed in 10 patient samples, and the correlation between absence of SPARC and survival times was analyzed. Conclusions: These data imply that a decrease in SPARC expression is correlated with dedifferentiation of BTC cells resulting in enhanced EMT being possibly mediated by TGF-β. Thereby SPARC levels might be a marker for individual prognosis of a patient, and strategies aiming at inhibition of SPARC downregulation might have potential for new future therapies.

SPARC and GluA1-Containing AMPA Receptors Promote Neuronal Health Following CNS Injury.

The proper formation and maintenance of functional synapses in the central nervous system (CNS) requires communication between neurons and astrocytes and the ability of astrocytes to release neuromodulatory molecules. Previously, we described a novel role for the astrocyte-secreted matricellular protein SPARC (Secreted Protein, Acidic and Rich in Cysteine) in regulating α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) and plasticity at developing synapses. SPARC is highly expressed by astrocytes and microglia during CNS development but its level is reduced in adulthood. Interestingly, SPARC has been shown to be upregulated in CNS injury and disease. However, the role of SPARC upregulation in these contexts is not fully understood. In this study, we investigated the effect of chronic SPARC administration on glutamate receptors on mature hippocampal neuron cultures and following CNS injury. We found that SPARC treatment increased the number of GluA1-containing AMPARs at synapses and enhanced synaptic function. Furthermore, we determined that the increase in synaptic strength induced by SPARC could be inhibited by Philanthotoxin-433, a blocker of homomeric GluA1-containing AMPARs. We then investigated the effect of SPARC treatment on neuronal health in an injury context where SPARC expression is upregulated. We found that SPARC levels are increased in astrocytes and microglia following middle cerebral artery occlusion (MCAO) in vivo and oxygen-glucose deprivation (OGD) in vitro. Remarkably, chronic pre-treatment with SPARC prevented OGD-induced loss of synaptic GluA1. Furthermore, SPARC treatment reduced neuronal death through Philanthotoxin-433 sensitive GluA1 receptors. Taken together, this study suggests a novel role for SPARC and GluA1 in promoting neuronal health and recovery following CNS damage.

456 Secreted Protein Acidic and Rich in Cysteine, a new biomarker of localized scleroderma

Secreted Protein Acidic and Rich in Cysteine (SPARC) is a multifunctional secreted glycoprotein found in the extracellular matrix. SPARC is expressed only at sites of tissue remodeling and wound repair. SPARC gene overexpression by cultured dermal fibroblasts from patients with systemic sclerosis has been shown in a cDNA micro-array study. Serum levels of SPARC of 20 patients with limited cutaneous systemic sclerosis, 13 patients with diffuse cutaneous systemic sclerosis, 33 patients with systemic sclerosis, 15 patients with localized scleroderma, 12 patients with dermatomyositis and 15 healthy volunteers were measured with specific enzyme linked immunosorbent assay. The mRNA and protein levels of SPARC were also investigated by real time PCR and immunohistochemistry. The relationships between the clinical manifestations of patients and the expressions of SPARC were analyzed. Serum levels of SPARC were significantly higher in patients with localized scleroderma than those in other groups or healthy individuals. The mRNA levels of SPARC were up regulated in all groups of scleroderma. The SPARC protein were highly expressed in the skin tissue of localized scleroderma. And the patients with elevated serum SPARC levels had significantly larger number of sclerotic lesions and significantly higher serum levels of anti-single strand DNA antibodies than those without. These results suggested that the serum levels of SPARC might be a serological marker for the disease activity and the extent of skin involvement in localized scleroderma.

Variations of SPARC levels in serum and foot muscle tissue of patients with type 2 diabetic foot

Objective To observe secreted protein acidic and rich in cysteine(SPARC)levels in serum and foot muscle tissue of patients with type 2 diabetic foot(DF). Methods All participants were divided into four groups with 40 cases in each group, including type 2 diabetic patients without(DMA)and with(DMB)lower limb arterial sclerosis and peripheral neuropathy, DF group, and normal control(NC)group. The muscle tissues of foot from DF group(n=6)and NC group(n=6)were taken. Serum SPARC level was measured with ELISA. RT-PCR, Western blot, immunofluorescence, and immunohistochemistry were used to examine SPARC mRNA and protein expressions in the foot muscle. Results Serum SPARC levels were higher in DMA and DMB groupscompared with NC and DF groups[(1 040.48±212.12 and 1 068.36±165.45 vs 841.93±144.57 and 835.43±188.37)ng/L, P 0.05). The expression levels of SPARC mRNA and protein in the foot muscle were higher in DF compared with NC group(P<0.05). Conclusion SPARC mRNA and protein expressions in foot muscle tissue are higher in DF group compared with control group, indicating that SPARC may participate in the repair and healing of damaged muscle tissue of diabetic foot. (Chin J Endocrinol Metab, 2015, 31: 961-966) Key words: Secreted protein acidic and rich in cysteine; Diabetes mellitus, type 2; Diabetic foot

SPARC Facilitates Inflammation in the Aging Heart and Suppresses Macrophage M2 Polarization

Cardiac aging is characterized by inflammation and fibrosis. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular protein known to play a role in extracellular matrix assembly and inflammation. SPARC levels increase with age in the left ventricle. We hypothesized that SPARC might facilitate age‐related cardiac inflammation. We studied 6 groups of mice (n=7‐10/group): young (3‐5 month old), middle‐aged (10‐12 m.o.) and old (18‐29 m.o.) C57BL/6J wild type (WT) and SPARC‐null (Null). Left ventricular wall thickness and myocyte size increased in an age‐related manner in WT but not Null (both p&lt;0.05). Expression of pro‐inflammatory markers (Ccl5, Cx3cl1, Ccr2, Cxcr3) and Adamts1were increased in middle‐aged and old WT and old Null compared to respective young (all p&lt;0.05). Versican is a substrate of Adamts1 that when cleaved promotes cell infiltration, and it decreased with age only in WT (p&lt;0.05). Expression of α2 integrin and macrophage infiltration were increased with age in WT, but not Null. Isolated peritoneal macrophages from young and old WT showed similar levels of pro‐inflammatory M1 markers (Ccl5, Ccl3, Tnfα); however, peritoneal macrophages from old WT mice displayed reduced anti‐inflammatory M2 markers (Arg1, Mrc1). SPARC treatment of young macrophages decreased M2 markers to levels observed in old mice. In summary, SPARC mediates age‐related cardiac inflammation by suppressing M2 macrophage polarization.

Abstract 15308: SPARC Deletion Suppresses Age-related Cardiac Inflammation

Secreted protein acidic and rich in cysteine (SPARC) is a collagen-binding matricellular protein that facilitates the formation and assembly of mature cross-linked collagen fibrils. We previously reported that aged mice exhibit increased SPARC levels in the heart, and SPARC deletion inhibits age-related collagen deposition. The present study investigated whether SPARC deletion could suppress age-related cardiac inflammation. Six groups of mice were studied: young (3-5 month old), middle-aged (10-12 m.o.) and old (18-29 m.o.) C57BL/6J wild type (WT) and SPARC-null (Null) mice (n=5-10 per group). Echocardiography and histology revealed that LV wall thickness and myocyte size were 15% and 43% increased with age in WT, respectively (both p&lt;0.05 old versus young). These age-dependent structural changes were blunted in the Null. The pro-inflammatory chemokines Ccl5 and Ccr2 were increased in middle-aged and old WT, and Cxcl1 was increased in old WT, compared to young WT (all p&lt;0.05). Interestingly, the age-dependent increases in Ccl5, Ccr2, and Cxcl1 were delayed in Null. Migration inhibitory factor (Mif) and Cx3cl1 showed an age-dependent increase in both WT and Null. Cxcl5 expression levels increased age-dependently only in Null, suggesting a compensatory increase for the decline of other chemokines. In summary, these results suggest that SPARC deletion slowed age-related cardiac inflammation.

Correlation of secreted protein acidic and rich in cysteine with diabetic nephropathy

Objective To investigate the serum concentrations of secreted protein acidic and rich in cysteine (SPARC) in patients with diabetic nephropathy and SPARC mRNA and protein expressions in renal tissue of db/db mice.Methods Serum SPARC levels in normal subjects and patients with type 2 diabetes mellitus (without diabetic nephropathy),chronic renal failure (without diabetes mellitus),and diabetic nephropathy were determined with enzyme-linked immunosorbent assay.RT-PCR,Western blot,and immunofluorescence were used to detect the mRNA and protein expressions of SPARC in renal tissue of db/db mice.Results The serum level of SPARC in diabetic nephropathy group was significantly higher than those in normal group,type 2 diabetes mellitus,and chronic renal failure group [(5.78 ± 1.41 vs 3.58 ±0.41,4.51 ± 1.08,and 3.81 ± 1.16) μg/L,P＜0.05 or P＜0.01].The SPARC level in the type 2 diabetes mellitus group was higher than that in normal group (P＜0.05),but there was no difference between normal group and chronic renal failure.SPARC mRNA and protein levels in renal tissue of db/db mice were higher compared with the littermates (P ＜ 0.05).Conclusions The long term hyperglycemic state in patients with diabetic nephropathy causes pathological change of renal tissue.Simultaneously,increased secretion of SPARC from renal tissue results in elevation of serum SPARC level and may play a role in pathological change of diabetic nephropathy. Key words: Secreted protein acidic and rich in cysteine; Diabetic nephropathy; Insulin-like growth factor; Transforming growth factor β1

Re-sensitization of 5-FU resistance by SPARC through negative regulation of glucose metabolism in hepatocellular carcinoma

Secreted protein, acidic and rich in cysteine (SPARC), a calcium-binding matricellular glycoprotein, is implicated in the progression of many cancers. Currently, there is growing evidence for important functions of SPARC in a variety of cancers and its role in cancer depends on tumor types. In this study, we reported SPARC negatively regulated glucose metabolism in hepatocellular carcinoma (HCC). Overexpression of SPARC inhibited glucose uptake and lactate product through downregulation of key enzymes of glucose metabolism. On the other hand, knock down of SPARC reversed the phenotypes. Meanwhile, exogenous expression of SPARC in HepG2 cells resulted in tolerance to low glucose and was correlated with AMPK pathway. Interestingly, the 5-fluorouracil (5-FU)-resistant HepG2 cells showed increased glucose metabolism and downregulated SPARC levels. Finally, we reported the overexpression of SPARC re-sensitize 5-FU-resistant cells to 5-FU through inhibition of glycolysis both in vitro and in vivo. Our study proposed a novel function of SPARC in the regulation of glucose metabolism in hepatocellular carcinoma and will facilitate the development of therapeutic strategies for the treatments of liver tumor patients.