Secreted frizzled-related protein 5 protects against renal fibrosis by inhibiting Wnt/β-catenin pathway

Renal fibrosis (RF) is an important pathogenesis for renal function deterioration in chronic kidney disease. Secreted frizzled-related protein 5 (SFRP5) is an anti-fibrotic adipokine but its direct role on RF remains unknown. It was aimed to study the protective effect of SFRP5 against RF and interference with Wnt/β-catenin signaling pathway for the first time. First, the therapeutic efficacy of SFRP5 was evaluated by adenovirus overexpression in rats with unilateral ureteral obstruction (UUO) in vivo. Thirty-six rats were randomly divided into the sham, UUO, and SFRP5 (UUO + Ad-SFRP5) groups. Half rats in each group were selected at random for euthanasia at 7 days and the others until 14 days. Then, the transforming growth factor (TGF)-β1-induced epithelial-mesenchymal transition (EMT) was established in HK-2 cells in vitro. The cells were divided into four groups: the control group, the TGF-β1 group, the TGF-β1 + SFRP5 group, and the TGF-β1 + SFRP5 + anti-SFRP5 group. The makers of EMT and Wnt/β-catenin pathway proteins were investigated. In the UUO model, expression of SFRP5 showed compensatory upregulation, and adenoviral-mediated SFRP5 over-expression remarkably attenuated RF, as demonstrated by maintenance of E-cadherin and suppression of α-smooth muscle actin (SMA). In vitro, SFRP5 was shown to inhibit TGF-β1-mediated positive regulation of α-SMA, fibronectin, collagen I but negative regulation of E-cadherin. Furthermore, SFRP5 abrogated activation of Wnt/β-catenin, which was the essential pathway in EMT and RF pathogenesis. The changes after a neutralizing antibody to SFRP5 confirmed the specificity of SFRP5 for inhibition. These findings suggest that SFRP5 can directly ameliorate EMT and protect against RF by inhibiting Wnt/β-catenin pathway.

Leptin/SFRP5 ratio as a potential predictor of postpartum weight retention. A prospective pilot study

Excessive gestational weight gain (EGWG) and failure to lose weight within 6 months from delivery are important and identifiable predictors of the long-term obesity. The aim of the study was to verify clinical usefulness of several substances that had been proved to play a significant role in metabolism and body mass regulation, i.e., leptin, ghrelin, fatty acid binding protein 4 (FABP4), secreted frizzled-related protein 5 (SFRP5), and vaspin, in relation to certain laboratory results, body composition and hydration status of females in the early postpartum period. The main goal was to determine a potential marker, which assessed as early as 48 hours after delivery, could predict serious difficulties in achieving pre pregnancy body mass of women with EGWG six months afterwards. The same inclusion criteria applied to the study group (women with EGWG) as well as the control group (women with appropriate body mass gain in pregnancy). These included normal pre-pregnancy BMI, absence of any diseases prior, during pregnancy and after delivery, 6-month long breastfeeding. Postpartum weight retention (PPWR) depended positively on gestational weight gain as well as the leptin/SFRP5 ratio assessed 48 hours after delivery. Both obstetricians and midwives should pay special attention to proper nutrition of pregnant women. The assessment of biophysical and biochemical parameters in the early postpartum period, when the mothers are usually hospitalized, seems to allow to predict the risk of greater body weight retention. Future research will help to determine to what extent the circulating concentrations of leptin and SFRP5 in the early puerperium are important for prediction of maternal PPWR and obesity.

Increased Secreted Frizzled-Related Protein 5 mRNA Expression in the Adipose Tissue of Women with Nonalcoholic Fatty Liver Disease Associated with Obesity

Secreted frizzled-related protein 5 (SFRP5) is an anti-inflammatory adipocytokine secreted by adipocytes that seems to be linked with nonalcoholic fatty liver disease (NAFLD). We aimed to evaluate the role of the SFRP5-wingless-MMTV integration site family member 5a (WNT5A) pathway, closely related to adipogenesis, in subcutaneous (SAT) and visceral adipose tissues (VAT) and its relationship with obesity-related NAFLD. Our cohort was composed of 60 women with morbid obesity (MO), who underwent hypocaloric diet, subclassified according to their hepatic histopathology and 15 women with normal weight. We observed increased SFRP5 mRNA expression in VAT and lower WNT5A expression in SAT in MO compared to normal weight. We found elevated SFRP5 expression in nonalcoholic steatohepatitis (NASH) in SAT and in mild simple steatosis (SS) and NASH in VAT. We observed higher WNT5A expression in SS compared to normal liver in SAT, and a peak of WNT5A expression in mild SS. To conclude, we reported increased SFRP5 mRNA expression in SAT and VAT of NAFLD-related to obesity subjects, suggesting an implication of the SFRP5-WNT5A pathway in NAFLD pathogenesis, probably due to the adipose tissue-liver axis. Since the mechanisms by which this potential interaction takes place remain elusive, more research in this field is needed.

Secreted Frizzled-Related Protein 5 Protects Against Cardiac Rupture and Improves Cardiac Function Through Inhibiting Mitochondrial Dysfunction

Background: Secreted frizzled-related protein 5 (Sfrp5) has been suggested to be a protective regulatory protein in coronary heart disease. However, the role of Sfrp5 in regulating ischemic injury and its consequences is not known. The aim of our study was to explore the effects of Sfrp5 on hearts after myocardial infarction (MI) and to investigate the underlying mechanisms.

Methods and Results: We found that Sfrp5 was downregulated over time in the heart tissue of MI mice. To further elucidate the role of Sfrp5 during MI, we established a cardiac overexpression of an Sfrp5 mouse model using the cardiotropic adeno-associated virus serotype 9 (AAV9). Overexpression of Sfrp5 significantly reduced infarct size as demonstrated by a decrease in mortality owing to cardiac rupture. Moreover, cardiac overexpression of Sfrp5 increased left ventricular function and mitochondrial biogenesis, decreased cardiomyocyte apoptosis, suppressed inflammation reaction, inhibited oxidative stress, and ameliorated cardiac remodeling as demonstrated by left ventricular ejection fraction, mitochondrial morphology, heart weight, NADH oxidase activity levels, and myocardial fibrosis at 2 weeks post-MI. At the molecular level, overexpression of Sfrp5 significantly increased the expression of p-AMPK^Thr172 protein with higher expression of mitochondrial fusion protein (MFN1 and MFN2) and lower expression of mitochondrial fission protein (p-Drp1^Ser616/Mid49/MFF/Fis-1). In isolated neonatal rat cardiac myocytes, Sfrp5 treatment attenuated hypoxia-induced mitochondrial dysfunction. Inhibition of AMPK activity with compound C abrogated this benefit.

Conclusions: Sfrp5 overexpression inhibits ischemic injury, reduces risk of cardiac rupture, ameliorates post-MI remodeling, and decreases the progression to heart failure via disrupting mitochondrial dysfunction and partly through normalizing the AMPK activity.

Secreted Frizzled-Related Protein 5 is Associated with Glucose and Lipid Metabolism Related Metabolic Syndrome Components Among Adolescents in Northeastern China

PURPOSE

Secreted frizzled-related protein 5 (SFRP5) is a novel anti-inflammatory adipokine that has been associated with various metabolic diseases. However, such relationship among adolescents remains unclear. The purpose of this study was to clarify the relationship between SFRP5 and the components of metabolic syndrome in Chinese adolescents.

PATIENTS AND METHODS

In this cross-sectional study, we included a total of 684 adolescents aged 11-16 years old from Liaoyang city, Liaoning province, China. The ELISA kits were implemented to measure the plasma SFRP5 and high-sensitivity C-reactive protein. Serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C), serum uric acid (UA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), fasting plasma glucose (FPG), and fasting serum insulin (FINS) were also measured.

RESULTS

The multivariate logistic regression analysis showed that low SFRP5 level were an independent risk factor of high FPG [odds ratio (OR)=5.31, 95% confidence interval (CI): 1.85-15.22, P<0.01] and high TC (OR=1.73, 95% CI: 1.01-2.96, P<0.05) when adjusting for age, sex, family history of diabetes, body mass index, and high-sensitivity C-reactive protein.

CONCLUSION

The lower level of SFRP5 is strongly related to lipid and glucose metabolism among adolescents in Northeast China. The risk of high fasting plasma glucose and high total cholesterol increases significantly as the plasma SFRP5 level decreases.

Reduction of Secreted Frizzled-Related Protein 5 Drives Vascular Calcification through Wnt3a-Mediated Rho/ROCK/JNK Signaling in Chronic Kidney Disease

Vascular calcification (VC) is commonly associated with bone loss in patients with chronic kidney disease (CKD). The Wingless-related integration site (Wnt) regulates osteoblast activation through canonical signaling pathways, but the common pathophysiology of these pathways during VC and bone loss has not been identified. A rat model of adenine-induced CKD with VC was used in this study. The rats were fed 0.75% adenine (2.5% protein, 0.92% phosphate) with or without intraperitoneal injection of calcitriol (0.08 µg/kg/day) for 4 weeks. Angiotensin II (3 µM)-induced VC was achieved in high phosphate medium (3 mM) through its effect on vascular smooth muscle cells (VSMCs). In an mRNA profiler polymerase chain reaction assay of the Wnt signaling pathway, secreted frizzled-related protein 5 (sFRP5) levels were significantly decreased in the CKD rat model compared with the control group. The repression of sFRP5 on VSMC trans-differentiation was mediated through Rho/Rho-associated coiled coil containing protein kinase (ROCK) and c-Jun N-terminal kinase (JNK) pathways activated by Wnt3a. In a proof of concept study conducted with patients with CKD, serum sFRP5 concentrations were significantly lower in subjects with VC than in those without VC. Our findings suggest that repression of sFRP5 is associated with VC in the CKD environment via activation of the noncanonical Wnt pathway, and thus that sFRP5 might be a novel therapeutic target for VC in CKD.

Correlation Between Circulating Levels of Secreted Frizzled-Related Protein 5 and Type 2 Diabetic Patients and Subjects with Impaired-Glucose Regulation

BACKGROUND

Secreted frizzled-related protein 5 (SFRP5) is a recently identified adipokine; however, its functions during pathogenesis of T2DM and obesity remain unclear. This research attempted to investigate associations between circulating SFRP5 and obesity/T2DM.

MATERIALS AND METHODS

According to diagnosis, 107 patients were assigned as impaired-glucose regulation (IGR) and 111 patients newly-diagnosed as T2DM were assigned as the T2DM group. Meanwhile, 132 subjects with normal-glucose tolerance (NGT) were assigned as the NGT group. Differences in plasma SFRP5 levels among three groups were compared. Correlation between SFRP5 levels and different metabolic markers was analyzed. Multiple-linear stepwise regression analyses were performed to determine independent factors for SFRP5. Patients in the T2DM group were administrated with metformin for 12 weeks. Meanwhile, changes in plasma SFRP5 levels were also analyzed.

RESULTS

Plasma SFRP5 level of the IGR group was significantly lower compared to the NGT group (219.1±39.7 pg/mL vs 236.7±72.6 pg/mL, P<0.05), however, that of the T2DM group was significantly lower compared to the IGR group (203.5±42.1 pg/mL vs 219.1±39.7 pg/mL, P<0.01). Level of plasma SFRP5 was negatively correlated with fasting plasma glucose, BMI, waist circumference (WC), normalized WC (waist-to-height ratio) (WHtR), 2h plasma glucose, fasting insulin, glycosylated hemoglobin (HbA1c), fasting C-peptide, HOMA-IR, and hs-CRP (P<0.01). Among the above factors, HbA1c and fasting insulin levels (FIns) were two independent factors. Plasma SFRP5 levels were increased after 12-week metformin treatment (201.0±34.8 pg/mL vs 213.1±34.4 pg/mL, P<0.05), while insulin resistance was alleviated (ln(HOMA-IR): 1.35±0.55 vs 1.07±0.49, P<0.01).

CONCLUSION

Metformin reduced circulating levels of secreted frizzled-related protein 5 and improved pathophysiological parameters of T2DM.

Umbilical Cord SFRP5 Levels of Term Newborns in Relation to Normal and Excessive Gestational Weight Gain

Among the new adipokines, secreted frizzled-related protein 5 (SFRP5) is considered to prevent obesity and insulin resistance. The umbilical cord SFRP5 levels have not yet been investigated. The main aim of the study was to investigate whether the umbilical cord SFRP5 concentrations are altered in term neonates born to mothers with excessive gestational weight gain (EGWG). Two groups of subjects were selected depending on their gestational weight gain, i.e. 28 controls and 38 patients with EGWG. Umbilical cord and maternal serum SFRP5 levels were lower in the EGWG group. Umbilical cord SFRP5 concentrations were directly associated with the maternal serum SFRP5, hemoglobin A1c and lean tissue index, umbilical cord leptin levels, as well as newborns’ anthropometric measurements in the EGWG subjects. In multiple linear regression models performed in all the study participants, umbilical cord SFRP5 concentrations depended positively on the maternal serum SFRP5, ghrelin, and leptin levels and negatively on the umbilical cord ghrelin levels, low-density lipoprotein cholesterol, pre-pregnancy body mass index, and gestational weight gain. EGWG is associated with disturbances in SFRP5 concentrations. Obstetricians and midwives should pay attention to nutrition and weight management during pregnancy.

Inhibition of secreted frizzled-related protein 5 improves glucose metabolism

Elucidating the role of secreted frizzled-related protein 5 (SFRP5) in metabolism and obesity has been complicated by contradictory findings when knockout mice were used to determine metabolic phenotypes. By overexpressing SFRP5 in obese, prediabetic mice we consistently observed elevated hyperglycemia and glucose intolerance, supporting SFRP5 as a negative regulator of glucose metabolism. Accordingly, Sfrp5 mRNA expression analysis of both epididymal and subcutaneous adipose depots of mice indicated a correlation with obesity. Thus, we generated a monoclonal antibody (mAb) against SFRP5 to ascertain the effect of SFRP5 inhibition in vivo. Congruent with SFRP5 overexpression worsening blood glucose levels and glucose intolerance, anti-SFRP5 mAb therapy improved these phenotypes in vivo. The results from both the overexpression and mAb inhibition studies suggest a role for SFRP5 in glucose metabolism and pancreatic β-cell function and thus establish the use of an anti-SFRP5 mAb as a potential approach to treat type 2 diabetes.

Serum secreted frizzled-related protein 5 levels differentially decrease in patients with hepatitis B virus-associated chronic infection and hepatocellular carcinoma

The aim of this study was to investigate the characteristics of serum secreted frizzled-related protein 5 (SFRP5), an inhibitor of Wnt signaling, in hepatitis B virus (HBV)-associated infections and hepatocellular carcinoma (HCC) patients. Serum SFRP5 levels were detected in 147 patients with HBV-associated chronic infection or HCC. Compared with the non-HBV-infected and non-HCC group, the HBV-associated chronic infection and HCC groups exhibited decreased serum SFRP5 levels. A significant inverse correlation between serum SFRP5 levels and HBV DNA levels was identified in the HBV-associated chronic infection and HCC groups. Furthermore, SFRP5 levels differentially decreased in patients with HBV-associated diseases, in a manner which was dependent on liver disease status. Compared with patients exhibiting HBV-associated chronic infection, patients with HCC were found to exhibit lower serum SFRP5 levels. The results of the present study indicated that patients with HBV-associated liver infection and HCC exhibited significantly deceased serum SFRP5 levels, which were found to negatively correlate with HBV DNA levels. Serum SFRP5 levels may present a biomarker for the severity of HBV-associated liver infection, and the risk of HCC initiation and progression.

Serum secreted frizzled-related protein 5 levels differentially decrease in patients with hepatitis B virus-associated chronic infection and hepatocellular carcinoma

The aim of this study was to investigate the characteristics of serum secreted frizzled-related protein 5 (SFRP5), an inhibitor of Wnt signaling, in hepatitis B virus (HBV)-associated infections and hepatocellular carcinoma (HCC) patients. Serum SFRP5 levels were detected in 147 patients with HBV-associated chronic infection or HCC. Compared with the non-HBV-infected and non-HCC group, the HBV-associated chronic infection and HCC groups exhibited decreased serum SFRP5 levels. A significant inverse correlation between serum SFRP5 levels and HBV DNA levels was identified in the HBV-associated chronic infection and HCC groups. Furthermore, SFRP5 levels differentially decreased in patients with HBV-associated diseases, in a manner which was dependent on liver disease status. Compared with patients exhibiting HBV-associated chronic infection, patients with HCC were found to exhibit lower serum SFRP5 levels. The results of the present study indicated that patients with HBV-associated liver infection and HCC exhibited significantly deceased serum SFRP5 levels, which were found to negatively correlate with HBV DNA levels. Serum SFRP5 levels may present a biomarker for the severity of HBV-associated liver infection, and the risk of HCC initiation and progression.

Secreted frizzled-related protein 5 suppresses inflammatory response in rheumatoid arthritis fibroblast-like synoviocytes through down-regulation of c-Jun N-terminal kinase

OBJECTIVE

This study was performed to investigate the effect of secreted frizzled-related protein 5 (Sfrp5), a novel anti-inflammatory adipokine that competes with the frizzled proteins for Wnt binding, on inflammatory response and the c-Jun N-terminal kinase (JNK) signalling pathway in RA.

METHODS

Expression of Sfrp5 mRNA in peripheral blood mononuclear cells (PBMCs) and fibroblast-like synoviocytes (FLSs) from patients with RA and OA was determined using real-time quantitative PCR (qPCR). Sfrp5 RNA interference (RNAi) plasmids were transfected to abrogate Sfrp5 expression in RA FLSs, and adenovirus containing the Sfrp5 transcript was delivered into RA FLSs to strengthen Sfrp5 expression. Levels of pro-inflammatory genes and their protein products were determined using real-time qPCR and ELISA in RA FLSs. Production of mitogen-activated protein kinase kinase 7 (MKK-7), JNK and c-Jun were assessed by Western blot analysis.

RESULTS

Expression of Sfrp5 mRNA was decreased in PMBCs and FLSs from patients with RA compared with patients with OA. Gene expression and production of IL-1β, IL-6, chemokine ligand 2 (CCL-2), CCL-7, cyclooxygenase 2 and MMP-9 were markedly increased in Sfrp5 RNAi plasmid-transfected RA FLSs, while transfection with adenoviral vectors encoding Sfrp5 induced reductions in those levels. Phosphorylated forms of MKK-7, JNK and c-Jun were increased by Sfrp5 RNAi plasmids and were decreased by adenoviral vectors encoding Sfrp5.

CONCLUSION

Sfrp5 suppressed the inflammatory response and down-regulated JNK signalling in RA FLSs. These findings provide evidence for the anti-inflammatory effect of Sfrp5 in RA.

Circulating secreted frizzled-related protein 5 (Sfrp5) and wingless-type MMTV integration site family member 5a (Wnt5a) levels in patients with type 2 diabetes mellitus

BACKGROUND

Secreted frizzled-related protein 5 (Sfrp5), an endogenous inhibitor of wingless-type MMTV integration site family (Wnt) signalling, is an anti-inflammatory adipokine whose expression is perturbed in models of obesity and type 2 diabetes mellitus (T2DM). Wnt member 5a (Wnt5a) is a representative ligand, and recent reports suggest that Wnt5a is involved in inflammatory diseases and metabolic disorders. The aim of this study was to investigate whether plasma Wnt5a and Sfrp5 levels are altered in patients with T2DM.

METHODS

Plasma Sfrp5 and Wnt5a concentrations were measured through enzyme-linked immunosorbent assay in type 2 diabetic and nondiabetic subjects.

RESULTS

A total of 82 patients with T2DM and 42 nondiabetic subjects were studied. Plasma Sfrp5 levels were found to be elevated in patients with T2DM (9.4 ± 9.0 vs 7.4 ± 10.9 ng/mL, p = 0.006). In contrast, Wnt5a levels were decreased (6.8 ± 12.6 vs 9.1 ± 4.0 ng/dL, p < 0.001). Increasing concentrations of Sfrp5 were independently and significantly associated with T2DM. Multiple logistic regression analysis revealed Sfrp5 as an independent association factor for T2DM, even after full adjustment of known biomarkers. In a multiple linear regression analysis, only the fasting glucose level was positively associated with the plasma Sfrp5 level.

CONCLUSIONS

Our results indicate that Sfrp5 may play a role in the pathogenesis of T2DM.