Increased endothelial inflammation, sTie-2 and arginase activity in umbilical cords obtained from gestational diabetic mothers

Isolation and Culture of Human Umbilical Vein Endothelial Cells (HUVECs)

This protocol describes a simple and an economical method for isolation of endothelial cells from human umbilical vein. Umbilical cord is easily available postpartum following informed consent, and the method for its collection is noninvasive with few ethical concerns. Thus, umbilical vein is an ideal source for isolation of endothelial cells of human origin. Endothelial cells are isolated from umbilical vein by collagenase digestion. This is followed by their culture on extracellular matrix (ECM) protein coated tissue culture flasks in presence of endothelial cell growth medium. In the last few decades, human umbilical vein endothelial cells (HUVECs) have come to be regarded as a standard model system by vascular biologists to understand general principles of endothelial cell biology and dysfunction. Here, we describe isolation, culture, as well as validation of HUVECs.

Fetoplacental endothelial dysfunction in gestational diabetes mellitus and maternal obesity: A potential threat for programming cardiovascular disease

Gestational diabetes mellitus (GDM) and maternal obesity (MO) increase the risk of adverse fetal outcomes, and the incidence of cardiovascular disease later in life. Extensive research has been conducted to elucidate the underlying mechanisms by which GDM and MO program the offspring to disease. This review focuses on the role of fetoplacental endothelial dysfunction in programming the offspring for cardiovascular disease in GDM and MO pregnancies. We discuss how pre-existing maternal health conditions can lead to vascular dysfunction in the fetoplacental unit and the fetus. We also examine the role of fetoplacental endothelial dysfunction in impairing fetal cardiovascular system development and the involvement of nitric oxide and hydrogen sulfide in mediating fetoplacental vascular dysfunction. Furthermore, we suggest that the L-Arginine-Nitric Oxide and the Adenosine-L-Arginine-Nitric Oxide (ALANO) signaling pathways are pertinent targets for research. Despite significant progress in this area, there are still knowledge gaps that need to be addressed in future research.

High total cholesterol and triglycerides levels increase arginases metabolism, impairing nitric oxide signaling and worsening fetoplacental endothelial dysfunction in gestational diabetes mellitus pregnancies

During human pregnancy, maternal physiological dyslipidemia (MPD) supports fetal development. However, some women develop maternal supraphysiological dyslipidemia (MSPD: increased total cholesterol (TC) and triglycerides (TG) levels). MSPD is present in normal and pregnancies with gestational diabetes mellitus (GDM). Both pathologies associate with fetoplacental endothelial dysfunction, producing alterations in nitric oxide (NO)-L-arginine/arginase metabolism. Nevertheless, the effect of MSPD on GDM, and how this synergy alters fetoplacental endothelial function is unknown, which is the aim of this study. 123 women at term of pregnancy were classified as MPD (n=40), MSPD (n=35), GDM with normal lipids (GDM- MPD, n=23) and with increased lipids (GDM-MSPD, n=25). TC ≥291 mg/dL and TG ≥275 mg/dL were considered as MSPD. Endothelial NO synthase (eNOS), human cationic amino acid transporter 1 (hCat1), and arginase II protein abundance and activity, were assayed in umbilical vein endothelial cells. In MSPD and MSPD-GDM, TC and TG increased respect to MPD and MPD-GDM. eNOS activity was reduced in MSPD and MSPD-GDM, but increased in MPD-GDM compared with MPD. No changes were observed in eNOS protein. However, decreased tetrahydrobiopterin levels were observed in all groups compared with MPD. Increased hCat1 protein and L-arginine transport were observed in both GDM groups compared with MPD. However, the transport was higher in GDM-MSPD compared to GDM-MPD. Higher Arginase II protein and activity were observed in MSPD-GDM compared with MPD. Thus, MSPD in GDM pregnancies alters fetal endothelial function associated with NO metabolism.

Myoinositol Reduces Inflammation and Oxidative Stress in Human Endothelial Cells Exposed In Vivo to Chronic Hyperglycemia

Myo-inositol (Myo) improves insulin resistance, glucose metabolism, and helps gestational diabetes (GDM) management. GDM is associated with a pro-inflammatory state and increased oxidative stress, which are both involved in vascular damage in diabetes. Our aim was to study Myo anti-inflammatory/antioxidant potential effects on an in vitro model of human umbilical vein endothelial cells (HUVECs). To this end, monocyte cell adhesion to HUVECs, adhesion molecule membrane exposure, and oxidative stress levels were determined in cells from control (C-) and GDM women treated during pregnancy either with diet only (GD-) or with diet plus Myo (GD+Myo). To deeply study the vascular effects of Myo, the same evaluations were performed in C- and GD-HUVECs following 48 h in vitro stimulation with Myo. Notably, we first observed that GD-HUVECs obtained from women assuming Myo supplementation exhibited a significantly decreased number of monocytes that adhered to endothelial cells, less adhesion molecule exposure, and lower intracellular reactive oxygen species (ROS) levels in the basal state as compared to GD-HUVECs obtained from women treated by diet only. This Myo anti-inflammatory/antioxidant effect was confirmed by 48 h in vitro stimulation of GD-HUVECs as compared to controls. Altogether, these results strongly suggest that Myo may exert protective actions against chronic inflammation induced by endothelial dysfunction in diabetes.

Inositol and antioxidant supplementation: Safety and efficacy in pregnancy

Pregnancies complicated by diabetes have largely increased in number over the last 50 years. Pregnancy is characterized by a physiologic increase in insulin resistance, which, associated with increased oxidative stress and inflammations, could induce alterations of glucose metabolism and diabetes. If not optimally controlled, these conditions have a negative impact on maternal and foetal outcomes. To date, one can resort only to diet and lifestyle to treat obesity and insulin resistance during pregnancy, and insulin remains the only therapeutic option to manage diabetes during pregnancy. However, in the last years, in a variety of experimental models, inositol and antioxidants supplementation have shown insulin-sensitizing, anti-inflammatory, and antioxidant properties, which could be mediated by some possible complementary mechanism of action. Different isomers and multiple combinations of these compounds are presently available: Aim of the present review article is to examine the existing evidence in order to clarify and/or define the effects of different inositol- and antioxidant-based supplements during pregnancy complicated by insulin resistance and/or by diabetes. This could help the clinician's evaluation and choice of the appropriate supplementation regimen.

Impact of Arginine Nutrition and Metabolism during Pregnancy on Offspring Outcomes

By serving as a precursor for the synthesis of nitric oxide, polyamines, and other molecules with biological importance, arginine plays a key role in pregnancy and fetal development. Arginine supplementation is a potential therapy for treating many human diseases. An impaired arginine metabolic pathway during gestation might produce long-term morphological or functional changes in the offspring, namely, developmental programming to increase vulnerability to developing a variety of non-communicable diseases (NCDs) in later life. In contrast, reprogramming is a strategy that shifts therapeutic interventions from adulthood to early-life, in order to reverse the programming processes, which might counterbalance the rising epidemic of NCDs. This review presented the role of arginine synthesis and metabolism in pregnancy. We also provided evidence for the links between an impaired arginine metabolic pathway and the pathogenesis of compromised pregnancy and fetal programming. This was followed by reprogramming strategies targeting the arginine metabolic pathway, to prevent the developmental programming of NCDs. Despite emerging evidence from experimental studies showing that targeting the arginine metabolic pathway has promise as a reprogramming strategy in pregnancy to prevent NCDs in the offspring, these results need further clinical application.

Knockout of p16INK4a promotes aggregative growth of dermal papilla cells

OBJECTIVE

Dermal papilla cells (DPCs) are located in the hair follicles and play an important role in hair growth. These cells have the ability to induce hair follicle formation when they display aggregative behavior. DPCs derived from the androgenetic alopecia (AGA) area undergo premature senescence in vitro, associated with p16INK4a expression. The aim of the current study was to investigate the expression of p16INK4a in aggregative and non-aggregative DPCs and the effect of p16INK4a down-regulation in these cells by adenovirus-mediated RNA interference (RNAi).

METHOD

DPCs were isolated and cultured from healthy human scalp. p16INK4a gene and protein were detected in aggregative and non-aggregative cells. Expression of p16INK4a in DPCs was silenced by infection with rAd5-CDKN1A-1p2shRNA. Cell fate was monitored after infection. The growth of cells was measured by MTT assay. Cell cycle was evaluated by flow cytometry (FCM).

RESULTS

DPCs were isolated by digestion and showed aggregative behavior for six passages. The expression of p16INK4a showed a clear upward trend in non-aggregative cells when compared with aggregative group. p16INK4a expression was silenced by rAd5-CDKN1A-1p2shRNA (p<0.05). The p16INK4a-silenced cells grew more rapidly and exhibited a trend towards aggregative growth. There was an increase in the proportion of cells in G1 phase, while those in S phase were reduced after p16INK4a gene silencing (p<0.05).

CONCLUSION

Our results suggest that p16INK4a plays an important role in the premature senescence and aggregative behavior of DPCs. These observations can lead to novel therapeutic strategies for treatment of AGA.

Angiopoietin-2 and soluble Tie-2 receptor plasma levels in children with obstructive sleep apnea and obesity

OBJECTIVE

Obstructive sleep apnea (OSA) is a prevalent condition, especially in children with obesity, and is associated with increased risk for metabolic syndrome (MetS). Angiopoietins have been identified as potential biomarkers of endothelial dysfunction and MetS. In adults, angiopoietin-2 (Ang-2) and its soluble receptor (sTie-2) are associated with diabetes, hypertension, and obesity and could be increased in children with OSA and obesity, particularly those with evidence of cardiometabolic alterations.

METHODS

One hundred twenty-six children (7.4 ± 2.0 years) were consecutively recruited and underwent overnight polysomnography, as well as endothelial function and BMI z score assessments and a fasting blood draw the morning after the sleep study. In addition to lipid profile, glucose and insulin levels, and homeostatic model assessment of insulin resistance (HOMA-IR), Ang-2 and sTie-2 concentrations were determined.

RESULTS

Children with obesity and OSA had significantly elevated plasma Ang-2 and sTie-2 levels compared to corresponding controls with and without obesity. Furthermore, endothelial function (Tmax) and HOMA-IR were linearly and independently associated with Ang-2 and sTie-2 levels. In a small subset of children (n = 14), treatment of OSA by adenotonsillectomy resulted in reductions of Ang-2 and sTie-2 (P < 0.01).

CONCLUSIONS

Ang-2 and sTie-2 plasma levels are increased in pediatric OSA and obesity, particularly when endothelial dysfunction or insulin resistance is detectable, and appear to decrease upon OSA treatment.

The influence of occupational chronic lead exposure on the levels of selected pro-inflammatory cytokines and angiogenic factors

The aim of the study was to determine the effect of occupational exposure to lead on the blood levels of pro-inflammatory cytokines and selected factors that influence angiogenesis. The study population was divided into two groups. The first group consisted of 56 male workers chronically exposed to lead. The second group (control) was comprised of 24 male administrative workers. The serum levels of interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α) were significantly higher in the group of workers chronically exposed to lead compared to control values by 38%, 68%, and 57%, respectively. Similarly, the values of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and fibroblast growth factor-basic (FGF-basic) were higher by 19% and 63%, respectively. In the group of workers chronically exposed to lead, there were positive correlations between the levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and angiogenic factors (VEGF, FGF-basic, sVEGFR-1, and soluble angiopoietin receptor). In the control group, there were no correlations between the levels of the abovementioned parameters. Results of the present study indicate that chronic occupational lead exposure promotes inflammatory processes via induction of pro-inflammatory cytokines, modulates angiogenesis, and elicits interdependencies between the immune response and angiogenic factors.

Oxidative stress biomarkers and their relationship with cytokine concentrations in overweight/obese pregnant women and their neonates

Background

Oxidative damage present in obese/overweight mothers may lead to further oxidative stress conditions or inflammation in maternal and cord blood samples. Thirty-four pregnant women/newborn pairs were included in this study to assess the presence of oxidative stress biomarkers and their relationship with serum cytokine concentrations. Oxidative stress biomarkers and antioxidant enzymes were compared between the mother/offspring pairs. The presence of 27 cytokines was measured in maternal and cord blood samples. Analyses were initially performed between all mothers and newborns and later between normal weight and mothers with overweight and obesity, and diabetic/non-diabetic women.

Results

Significant differences were found in biomarker concentrations between mothers and newborns. Additionally, superoxide-dismutase activity was higher in pre-pregnancy overweight mothers compared to those with normal weight. Activity for this enzyme was higher in neonates born from mothers with normal pregestational weight compared with their mothers. Nitrites in overweight/obese mothers were statistically lower than in their offspring. Maternal free fatty acids, nitrites, carbonylated proteins, malondialdehyde and superoxide dismutase predicted maternal serum concentrations of IL-4, IL-13, IP-10 and MIP-1β. Arginase activity in maternal plasma was related to decreased concentrations of IL-4 and IL-1β in cord arterial blood. Increased maternal malondialdehyde plasma was associated with higher levels of IL-6 and IL-7 in the offspring.

Conclusions

Oxidative stress biomarkers differ between mothers and offspring and can predict maternal and newborn cytokine concentrations, indicating a potential role for oxidative stress in foetal metabolic and immunologic programming. Moreover, maternal obesity and diabetes may affect maternal microenvironments, and oxidative stress related to these can have an impact on the placenta and foetal growth.

Maternal obesity programs mitochondrial and lipid metabolism gene expression in infant umbilical vein endothelial cells

BACKGROUND/OBJECTIVES

Maternal obesity increases risk for childhood obesity, but molecular mechanisms are not well understood. We hypothesized that primary umbilical vein endothelial cells (HUVEC) from infants of overweight and obese mothers would harbor transcriptional patterns reflecting offspring obesity risk.

SUBJECTS/METHODS

In this observational cohort study, we recruited 13 lean (pre-pregnancy body mass index (BMI) <25.0 kg m^-2) and 24 overweight-obese ('ov-ob', BMI⩾25.0 kg m^-2) women. We isolated primary HUVEC, and analyzed both gene expression (Primeview, Affymetrix) and cord blood levels of hormones and adipokines.

RESULTS

A total of 142 transcripts were differentially expressed in HUVEC from infants of overweight-obese mothers (false discovery rate, FDR<0.05). Pathway analysis revealed that genes involved in mitochondrial and lipid metabolism were negatively correlated with maternal BMI (FDR<0.05). To test whether these transcriptomic patterns were associated with distinct nutrient exposures in the setting of maternal obesity, we analyzed the cord blood lipidome and noted significant increases in the levels of total free fatty acids (lean: 95.5±37.1 μg ml^-1, ov-ob: 124.1±46.0 μg ml^-1, P=0.049), palmitate (lean: 34.5±12.7 μg ml^-1, ov-ob: 46.3±18.4 μg ml^-1, P=0.03) and stearate (lean: 20.8±8.2 μg ml^-1, ov-ob: 29.7±17.2 μg ml^-1, P=0.04), in infants of overweight-obese mothers.

CONCLUSIONS

Prenatal exposure to maternal obesity alters HUVEC expression of genes involved in mitochondrial and lipid metabolism, potentially reflecting developmentally programmed differences in oxidative and lipid metabolism.

Post-transcriptional down regulation of ICAM-1 in feto-placental endothelium in GDM

Maternal gestational diabetes (GDM) is associated with hyperglycaemia and hyperinsulinemia in the fetal circulation which consequently may induce endothelial dysfunction in the feto-placental vasculature. In fact, feto-placental vasculature reveals various morphological changes in response to GDM. The cell adhesion molecules (CAMs) ICAM-1, VCAM-1 and E-selectin promote attachment and trans-endothelial migration of leukocytes, and are up regulated in inflammation and endothelial dysfunction. Thus, we hypothesized that the GDM environment upregulates ICAM-1, VCAM-1 and E-selectin in the feto-placental endothelium. We isolated primary feto-placental endothelial cells (fpEC) after normal (n=18) and GDM pregnancy (n=11) and analyzed mRNA (RT-qPCR) and protein expression (Immunoblot) of ICAM-1, VCAM-1 and E-selectin. While other CAMs were unchanged on mRNA and protein levels, ICAM-1 protein was decreased by GDM. Further analysis revealed also a decrease in the release of soluble ICAM-1 (sICAM-1), whose levels correlated negatively with maternal BMI. We conclude that this reduction of ICAM-1 protein species is the result of post-translational regulation, since ICAM-1 mRNA expression was unchanged. In fact, miRNAs targeting ICAM-1 were upregulated in GDM fpEC. Immunohistochemistry showed weaker ICAM-1 staining in the placental endothelium after GDM pregnancies, and demonstrated ICAM-1 binding partners CD11a and CD18 expressed on leukocytes in fetal circulation and on placental tissue macrophages. This study identified reduction of ICAM-1 protein in fpEC in GDM pregnancy, which was regulated post-transcriptionally. Low ICAM-1 protein production may represent a protective, placenta-specific mechanism to avoid leukocyte transmigration into the placenta in response to GDM.

The Role of Maternal Gestational Diabetes in Inducing Fetal Endothelial Dysfunction

Gestational diabetes mellitus (GDM) is known to be associated with fetal endothelial dysfunction, however, the mechanisms are not fully understood. This study examines the effect of maternal diabetes on fetal endothelial function and gene expression under physiological glucose conditions (5 mM). Human umbilical vein endothelial cell (HUVEC) isolated from diabetic mothers (d.HUVEC) grew more slowly than HUVEC isolated from healthy mothers (c.HUVEC) and had delayed doubling time despite increased levels of total vascular endothelial growth factor (VEGF) expression and protein production as determined by real-time PCR and ELISA respectively. Using western blot, the levels of antiproliferative VEGF165b isoform were increased in d.HUVEC relative to c.HUVEC. Successful VEGF165b knockdown by small interfering RNA (siRNA) resulted in increased proliferation of d.HUVEC measured by MTT, compared with negative siRNA control, to similar levels measured in c.HUVEC. In addition, d.HUVEC generated excess levels of ROS as revealed by 2',7' Dichlorodihydrofluorescein Diacetate (DCFH-DA) and Nitrotetrazolium blue (NBT). Using microarray, 102 genes were differentially overexpressed between d.HUVEC versus c.HUVEC (>1.5-fold change; P < 0.05). Functional clustering analysis of these differentially expressed genes revealed participation in inflammatory responses (including adhesion) which may be related to pathological outcomes. Of these genes, ICAM-1 was validated as upregulated, confirming microarray results. Additional confirmatory immunofluorescence staining revealed increased protein expression of ICAM-1 compared with c.HUVEC which was reduced by vitamin C treatment (100 μM). Thus, maternal diabetes induces persistent alterations in fetal endothelial function and gene expression following glucose normalization and antioxidant treatment could help reverse endothelium dysfunction.

Centella asiatica and lipoic acid, or a combination thereof, inhibit monocyte adhesion to endothelial cells from umbilical cords of gestational diabetic women

BACKGROUND AND AIMS

Diabetes mellitus is associated with inflammatory endothelial activation and increased vascular leukocyte adhesion molecule expression, both playing a prominent role in the development of vascular complications. Centella asiatica (CA) and Lipoic Acid (LA) have shown anti-inflammatory and anti-oxidant properties in a variety of experimental models; however, their action on human umbilical vein endothelial cells (HUVECs), chronically exposed to hyperglycemia and pro-inflammatory environment during pregnancy, is still unknown.

METHODS AND RESULTS

In HUVECs from umbilical cords of gestational diabetic (GD) or healthy (C) women, both CA and LA affected tumor necrosis factor-α (TNF-α)-induced inflammation, being associated with a significant decrease in vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) expression (western blot) and exposure (flow cytometry), as well as monocyte-HUVECs interaction (adhesion assay). Notably, this was associated with a significant reduction of an index of nitro-oxidative stress, such as the intracellular peroxynitrite levels (fluorescence detection by cytometric analysis), Mitogen-Activated Protein kinase (p44/42 MAPK) expression/phosphorylation levels and Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB p65) cytoplasm-nucleus translocation (flow cytometry). Overall our results indicate that both CA and LA used separately, and even better when combined, are effective to reduce the inflammatory response in TNF-α-treated HUVECs. Notably, this was more significant in GD than in C-HUVECs and also evident at baseline.

CONCLUSION

In conclusion, our in vitro study demonstrates that both CA and LA, or a combination thereof, are able to mitigate the potentially dangerous effects on the endothelium of chronic exposure to hyperglycemia in vivo.

Mouse hepatocytes and LSEC proteome reveal novel mechanisms of ischemia/reperfusion damage and protection by A2aR stimulation

BACKGROUND & AIMS

Ischemia-reperfusion (IR) of liver results in hepatocytes (HP) and sinusoidal endothelial cells (LSEC) irreversible damage. Ischemic preconditioning protects IR damage upon adenosine A2a receptor (A2aR) stimulation. Understanding the phenotypic changes that underlie hepatocellular damage and protection is critical to optimize strategies against IR.

METHODS

The proteome of HP and LSEC, isolated from sham or IR exposed mice, receiving or not the A2aR agonist CGS21680 (0.5mg/kg b.w.), was analyzed by 2-D DIGE/MALDI-TOF.

RESULTS

We identified 64 proteins involved in cytoprotection, regeneration, energy metabolism and response to oxidative stress; among them, 34 were associated with IR injury and A2aR protection. The main pathways, downregulated by IR and upregulated by CGS21680 in HP and LSEC, were related to carbohydrate, protein and lipid supply and metabolism. In LSEC, IR reduced stress response enzymes that were instead upregulated by CGS21680 treatment. Functional validation experiments confirmed the metabolic involvement and showed that inhibition of pyruvate kinase, 3-chetoacylCoA thiolase, and arginase reduced the protection by CGS21680 of in vitro hypoxia-reoxygenation injury, whereas their metabolic products induced liver cell protection. Moreover, LSEC, but not HP, were sensitive to H2O2-induced oxidative damage and CGS21680 protected against this effect.

CONCLUSIONS

IR and A2aR stimulation produces pathological and protected liver cell phenotypes, respectively characterized by down- and upregulation of proteins involved in the response to O2 and nutrients deprivation during ischemia, oxidative stress, and reactivation of aerobic energy synthesis at reperfusion. This provides novel insights into IR hepatocellular damage and protection, and suggests additional therapeutic options.

Features of endothelial dysfunction in umbilical cord vessels of women with gestational diabetes

BACKGROUND AND AIMS

Gestational diabetes (GDM) is associated with increased oxidative stress and overexpression of inflammatory cytokines, both of which might lead to endothelial dysfunction and vascular disease. As such, GDM could be viewed as a sort of ‘short lived’ metabolic syndrome. As umbilical cord vessels represent a suitable model for the study of vascular alterations brought about by GDM, the aim of the present work was to characterize the phenotype of human umbilical vein endothelial cells (HUVECs) chronically exposed to hyperglycaemia and to a pro-inflammatory environment during pregnancy so as to identify molecular modifications of cellular homoeostasis eventually impacting on endothelial dysfunction.

METHODS AND RESULT

Tissue specimens and HUVECs were obtained from umbilical cords of GDMand control women. As compared to controls, GD-HUVEC exhibited enhanced monocyte adhesion and vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1(ICAM-1) expression and exposure on plasma membrane after tumour necrosis factor-alpha(TNF-α) stimulation (Western blot, flow cytometer). As compared to control cells, GD-HUVEC in basal conditions exhibited enhanced monocyte adhesion, nitric oxide synthase (NOS) expression and activity (eNOS Real-Time polymerase chain reaction, Western Blot for eNOS total protein and monomers/dimers ratio, conversion of [3H]-L-arginine in [3H]-L-citrulline), increased O(-)(2)egeneration together with increased NT levels (immunofluorescence) and reduced NO bioavailability(guanosine 3',5'-monophosphate (cGMP) production, EIA). Furthermore, immunohistochemistry revealed increased eNOS and NT immunoreactivity in GD umbilical cords.

CONCLUSION

Endothelial cells exposed in vivo even transiently to hyperglycaemia, oxidative stress and inflammation exhibit durable pro-atherogenic modifications.

Assessment of serum arginase I as a type 2 diabetes mellitus diagnosis biomarker in patients

Previous studies have reported that levels of serum arginase I are increased in certain diseases. However, the exact association between arginase I and diabetes mellitus (DM) has yet to be determined. The aim of the present study was to investigate the correlation between arginase I activity and DM to determine whether arginase I activity may be used as a diagnostic biomarker for DM. DM was induced by a streptozotocin injection, while the arginase inhibitor, citrulline, was administered daily. Serum levels of glucose, reactive oxygen species (ROS) and arginase I activity were analyzed, and quantitative polymerase chain reaction and western blot analysis were performed to detect the mRNA and protein expression levels of arginase I, respectively. In addition, western blot analysis was used to determine the protein expression of the Tie 2 receptor. Pearson’s analysis was used to determine the correlation between arginase I activity and Tie 2 expression, while concordance analysis was performed using the Cohen’s test to obtain the Kappa statistic. The results demonstrated that serum arginase I activity levels in the rats with DM were significantly elevated compared with the control group, and positively correlated with the blood glucose levels. In addition, the blood glucose and ROS levels were increased significantly in the rats with DM. Arginase I mRNA and protein expression levels were significantly elevated in the diabetic rats when compared with the control group, and Tie 2 expression levels increased and were shown to correlate with arginase I activity in the diabetic rats. In addition, arginase I activity was shown to correlate with glucose intolerance and post-load glucose values. Good concordance was observed between arginase I activity and the clinical diagnosis for DM (κ=0.876; P<0.001). Therefore, the results indicated that arginase I may function as a diagnostic biomarker for DM rats model.