Expression of Serum GRP78 and CHOP in Endoplasmic Reticulum Stress Pathways of Chinese Type 2 Diabetic Kidney Disease Patients
Background: The kidney has a rich endoplasmic reticulum system. A close relationship exists between endoplasmic reticulum stress (ERS) and diabetic kidney disease (DKD). The current study aimed to investigate serum glucose-regulated protein 78 (GRP78) as well as CCAAT/enhancer binding protein homologous protein (CHOP) concentrations in type 2 diabetes mellitus (T2DM) Chinese patients, especially those with microalbuminuria. Methods: We evaluated the relationships between serum GRP78 or CHOP
... m GRP78 or CHOP levels and DKD. We recruited 67 patients with T2DM and 63 control subjects. We determined serum GRP78 and CHOP concentrations by ELISA, collected anthropometric data, and measured biochemical parameters in a clinical laboratory. Results: Compared with control groups, Chinese T2DM patients showed decreased serum levels of GRP78 [0.21 (0.16–0.24) vs. 0.16 (0.16–0.19) ng/mL, p < 0.01] and CHOP [3.8 (3.0–5.5) vs. 5.5 (3.7–7.9) ng/mL, p < 0.01]. Reduction in GRP78 and CHOP serum levels was more pronounced in patients with more severe categories of microalbuminuria. Amounts of serum GRP78 correlated directly with serum fasting c-peptide, cystatin-c (cys-c), creatinine (Cr), blood urea nitrogen (BUN), and uric acid, and inversely with glomerular filtration rates. Serum CHOP level was positively correlated with age, Cr, BUN, cys-c, urinary microalbumin/creatinine (UmALB/Cr), and eGFR. Serum GRP78 was predicted independently by Cr, BUN, serum uric acid, eGFR, and cys-c, while CHOP depended on age, Cr, BUN, serum uric acid, eGFR, UmALB/Cr, and cys-c. After controlling for confounding factors, GRP78 and CHOP expression was significantly associated with DKD (binary logistic regression, p < 0.01). Conclusions: T2DM patients showed increased serum GRP78 and CHOP concentrations. Receiver operating characteristic (ROC) areas under the curve for predicting DKD based on GRP78 and CHOP were 0.686 [95% CI: 0.558–0.813] and 0.670[0.524–0.816], respectively.