Increased glutathionylated hemoglobin (HbSSG) in type 2 diabetes subjects with microangiopathy.
OBJECTIVE
Protein glutathionylation is considered an important post-translational modification in the pathogenesis of complex diseases. The aim of this study was to examine whether hemoglobin (Hb) is modified by reduced glutathione (GSH) via oxidation of the thiol groups present in diabetes and its associated microangiopathy and to determine whether oxidative imbalance has any correlation with glutathionylated Hb (HbSSG) levels.


METHODS
The study group consisted of a total of 130 subjects which included non-diabetic healthy control subjects (n = 30) and type 2 diabetic patients with (n = 53) and without (n = 47) microangiopathy. All subjects were assessed for glycemic and lipidemic status, while diabetic subjects were also assessed for the diagnosis of retinopathy and nephropathy. RBC lysates from all the subjects were analyzed by liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) for HbSSG beta-globin chains. Levels of GSH and thiobarbituric acid substances (TBARS) levels were measured by spectrophotometric and fluorimetric methods, respectively.


RESULTS
The positivity for HbSSG in diabetic subjects with microangiopathy was significantly higher (69%) compared to diabetics without microangiopathy (22%) and control subjects (14%). In univariate regression analysis, HbSSG levels were significantly associated with the duration of diabetes, HbA1c, and TBARS levels. GSH levels were negatively correlated (r = -0.57, P < 0.001) with HbSSG in diabetic subjects. A significant inverse correlation (r = -0.42, P < 0.001) between the GSH levels and HbA1c levels was also seen in diabetic subjects.


CONCLUSIONS
This is perhaps the largest LC-MS-based study to demonstrate that HbSSG levels are markedly increased in diabetic subjects with microangiopathy. Since diabetic subjects also exhibited increased lipid peroxidation and decreased GSH levels, it appears that enhanced oxidative stress may account for the increased HbSSG concentrations and altered reduction-oxidation (redox) signaling.
Sampathkumar
Rangasamy
R
Department of Cell and Molecular Biology, Madras Diabetes Research Foundation, 6B, Conran Smith Road, Gopalapuram, Chennai-600 086, India.
Balasubramanyam
Muthuswamy
M
Sudarslal
Sadasivannair
S
Rema
Mohan
M
Mohan
Viswanthan
V
Balaram
Padmanabhan
P
D015415:Biomarkers / Q000097:blood; D048909:Diabetes Complications / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D003925:Diabetic Angiopathies / Q000097:blood*; D005978:Glutathione / Q000097:blood*; D006454:Hemoglobins; D006801:Humans; D015227:Lipid Peroxidation; D008875:Middle Aged; D018384:Oxidative Stress; D021241:Spectrometry, Mass, Electrospray Ionization
D015415:Biomarkers; D006454:Hemoglobins; C404464:glutathionyl hemoglobin; D005978:Glutathione