Genetic Variation in the Renin-Angiotensin System and Diabetic Nephropathy in the Tunisian Population.

BACKGROUND: The aim of this study was to evaluate the association of ACE, angiotensinogen (AGT) and angiotensin II receptor type I (AGTR1) polymorphisms with diabetic nephropathy (DN) in Tunisians. METHODS: The study population comprised 236 type 2 diabetic patients: with nephropathy (DN = 47) and without nephropathy (DM = 189). Genotyping of ACE-I/D-rs1799752, ACE-rs4343G>A, AGT-rs5050A>C, AGT-rs 4762C>T, AGT-rs699A>G, and AGTR1-rs5186A>C was performed by PCR-RFLP. Haplotype and statistical analysis were realized using SNP Analyzer2.0 and SPSS20, respectively. RESULTS: Genotype frequencies were in Hardy-Weinberg equilibrium. After adjustment for potential confounding factors (age, gender, diabetes duration, hypertension…), an increased risk for DN was associated with mutated alleles of rs4762 (OR = 10.25, p = 0.001), rs699 (OR = 22.21, p < 0.001), and rs5186 (OR = 11.25, p < 0.001). However, mutated alleles of rs1799752 seemed to be protector (OR = 0.41, p = 0.011). Adjusted ORs of DN associated with the ACE haplotype (DA) was (OR = 9.56, p = 0.047) and with the ACE-AGT haplotype (ATADAA) was (OR = 5.38, p = 0.032). CONCLUSIONS: This study indicates that common variants in ACE, AGT, and AGTR1 seem to play a role in genetic susceptibility to DN in Tunisian population and provides evidence for a disease haplotype: ATADAA.

Paraoxonase 1 polymorphisms (L55M and Q192R) as a genetic marker of diabetic nephropathy in youth with type 1 diabetes.

INTRODUCTION: Paraoxonase 1 (PON1) polymorphisms have been largely involved in diabetes complications. The aim of the study is to evaluate the effects of PON1 polymorphisms (L55M and Q192R) on diabetic nephropathy (DN). MATERIAL AND METHODS: The study involved 116 children and adolescents with type 1 diabetes (T1D) and 91 healthy subjects. Albumin excretion rate (AER) was determined by immunoturbidimetry. PON1 activity was measured by a spectrophotometric method, and genotyping of PON1 gene was assessed by multiplex PCR followed by RFLP. RESULTS: PON1 activity was inversely correlated to AER (r = -0.245, p = 0.008). A significant decrease (p = 0.037) in PON1 activity was shown between patients with nephropathy and those without (162 [57-618] vs. 316 [37-788] IU/L, respectively). The distribution of AER was, for L55M polymorphism MM > LM > LL (p = 0.002), and for Q192R polymorphism QQ > QR > RR (p < 0.001). The opposite distribution was noted for PON 1 activity (p < 0.001). LMQQ and MMQQ haplotypes seem to increase AER (p = 0.004, p = 0.003, respectively) and to reduce PON1 activity (p = 0.011, p = 0.052, respectively) in youths with T1D. However, LLRR haplotype seems to have the opposite effect. CONCLUSIONS: This study demonstrated that PON1 polymorphisms L55M and Q192R seem to be genetic markers involved in the development of DN in T1D. (Endokrynol Pol 2017; 68 (1): 35-41).

Osteoprotegerin as a marker of cardiovascular risk in children and adolescents with type 1 diabetes.

BACKGROUND: Elevated osteoprotegerin (OPG) levels have been reported in patients with diabetes complications. We investigated whether plasma OPG levels can be used as a marker of cardiovascular risk in children and adolescents with type 1 diabetes (T1D). METHODS: Plasma blood samples were obtained from 243 subjects (143 children and adolescents with T1D and 100 healthy controls). OPG concentrations were measured by enzyme-linked immunosorbent assay (ELISA) method. All data were analyzed by using PASW statistics 18. RESULTS: A significant higher plasma OPG level was found in children with T1D compared to controls (p < 0.001). A significant increase of OPG levels has been related to the glucose level ≥ 7 mmol/L (2.44 [0.01-6.22] vs. 2.16 [0.13-6.22] pmol/L, p = 0.019), microalbuminuria ≥ 30 mg/24 h (3.71 [0.160-6.03] vs. 2.26 [0.01-6.22] pmol/L, p < 0.001), and cystatin-C ≥ 0.789 mg/L (2.64 [0.37-6.22] vs. 2.11 [0.01-5.82] pmol/L, p < 0.001). We noted a significant higher frequency of children with increased cystatin-C levels in the group with elevated plasma level of OPG compared with those with normal levels (49 vs. 18%, respectively) with an odds ratio (OR) = 4.42 [1.41-13.84] (p = 0.006). We showed a significant increase of OPG levels when the number of cardiovascular risk factors exceeds 3 (p = 0.001). CONCLUSION: OPG may be a potential biomarker of cardiovascular risk in T1D. Implementation of OPG determination in the clinical laboratory setting would be useful in order to better stratify patients and to assess the most adequate treatment.

[Is paraoxonase 1 a marker of cardiovascular risk in youth with type 1 diabetes? (Study about 109 cases)]. / La paraoxonase 1: un marqueur de risque cardiovasculaire chez les jeunes diabétiques de type 1 ? (109 cas).

OBJECTIVES: We purpose to verify if paraoxonase 1 (PON1) activity may be a marker of cardiovascular risk in a young Tunisian population with type 1 diabetes (T1D). METHODS: PON1 activity was measured by a kinetic method using paraoxon as substrate. The other parameters were determined by automated methods. RESULTS: One hundred and nine children and adolescents with T1D and 97 healthy subjects were involved in this study. PON1 activity and PON1/HDL-cholesterol ratio were significantly decreased in diabetics (303 ± 174 vs. 372 ± 180 U/L and 221 ± 139 vs. 298 ± 20 1U/mmol, P=0.006, P=0.002, respectively) compared to controls. A significant increase in total cholesterol, LDL-c and microalbuminuria was observed in diabetics compared to controls. PON1 activity was decreased by 9.5% in patients with diabetes duration ≥ 6 years, by 28.4% for those with fasting glycemia ≥ 7 mmol/L (P<0.001), by 14% in those with HbA1c ≥ 8% and by 12.3% for diabetics with dyslipidemia. PON1 activity is reduced when the number of cardiovascular risk factors increases (P<0.001). CONCLUSION: PON1 seems to be associated to cardiovascular risk markers in T1D. This result remains to be seen. Nevertheless, improving PON1 activity could be a significant target for reducing cardiovascular risk.

Can paraoxonase 1 polymorphisms (L55 M and Q192 R) protect children with type 1 diabetes against lipid abnormalities?

BACKGROUND: Only a few studies have focused on the possible modulatory role of paraoxonase 1 (PON1) polymorphisms in lipid profiles, especially in children and in adolescents with type 1 diabetes (T1D). OBJECTIVE: We propose to study the association between PON1 polymorphisms (PON1-55 and PON1-192) and a lipid profile in a young Tunisian population with T1D. METHODS: The study compared 122 children and adolescents with T1D with 97 controls. Genomic DNA was collected from 116 patients and 91 controls. Lipid parameters were determined by automated methods. PON1 activity was measured by a spectrophotometric method and genotyping of the PON1 gene was assessed by multiplex polymerase chain reaction followed by restriction fragment-length polymorphism. RESULTS: A significant increase in total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol (LDL-C), apolipoprotein B (ApoB), and lipoprotein (a) (Lp(a)) and a significant decrease in apolipoprotein A1 (ApoA1), ApoA1/ApoB ratio, and PON1 activity/HDL-C ratio were observed in children with T1D compared with controls. In the LLQR haplotype, the group with diabetes showed significantly higher values of total cholesterol, LDL-C, apoB, Lp(a), and apoA1/apoB ratio compared with the control group. Those with diabetes with the LLQQ haplotype showed a significant decrease in LDL-C and Lp(a) compared with controls (P < .0001). CONCLUSION: PON1 polymorphisms (PON1-55 and PON1-192) seem to be involved in the altering the lipid profile in T1D. The LLQR haplotype provided an atherogenic lipid profile in children with T1D compared with controls. LLQQ haplotype seemed to have a protective effect against the increase in LDL-C and Lp(a) that are heavily involved in the development of cardiovascular diseases.

[Does bilirubin interfere with capillary electrophoresis of serum proteins?]. / La bilirubine interfère-t-elle sur l'électrophorèse capillaire des protéines sériques ?

Capillary electrophoresis of serum proteins is a fast, reliable and simple technique, but many interference exist. The objective of our work is to study the interference of bilirubin on this technique; 70 icteric sera were analysed on Capillarys ™ (Sebia). A second electrophoresis was performed on 40 samples after bilirubin photodegradation. The bilirubin and serum proteins were determinated respectively by Jendrassik and Grof and biuret methods on Konélab 20i ™ (Thermo Electron Corporation). We found abnormal spreading of the albumin fraction of the anode side wich constitute sometimes an isolated fraction in the traditional area of pre-albumin migration. This fraction varies from 2.0 ± 2.0% (0.0 to 7.3%) or 0.98 ± 1.53 g/L (0 to 5.3 g/L) and it seems to be related to the direct bilirubin since, following overloading sera with a solution of bilirubin, no further fraction was recovered. An average decrease of bilirubin after photodegradation of 58 ± 17% (26-89%) is followed by a decrease in the same order 64 ± 38% (10-100%) of the additional fraction. Acetate cellulose electrophoresis of the same samples showed no variation. The high bilirubin levels seem modify slightly the electrophoretic profile. However the impact of the interference on the interpretation of electrophoretic trace is negligible.

Association between serum cystatin C levels and cardiovascular disease in type 2 diabetic patients.

Serum cystatin C concentration was recently reported as a marker of cardiovascular disease (CVD). In the present study, we evaluated the association between the increase of serum cystatin C levels and the risk of CVD in type 2 diabetes. 42 patients with type 2 diabetes were included in the present study; 27 of them have CVD. The control group consisted of 30 healthy adults. Cystatin C, creatinine, microalbuminuria and CRP were measured on Cobas 6000(TM). Cystatine C level was significantly higher in patients with CVD. A significant difference in serum cystatin C was found in patients with and without CVD among albuminuria. No difference in serum cystatin C levels was found according to number of affected vessels. A cystatin C level above 1.10 mg/L was associated with increase of risk of CVD with significant difference (OR = 42.52; IC 95% 1.455 to 1242.827 and p = 0.029). Our results suggested that the increase of serum cystatin C concentrations is a potential marker for CVD in diabetes.