gi-diseases-2018-scientifictracks-abstracts

4 / 8

Page 19
Notes:
conferenceseries.com
Volume 8 Journal of Gastrointestinal & Digestive System GI Diseases 2018
July 11-12, 2018
July 11-12, 2018 Sydney, Australia
15th International Conference on
Digestive Disorders and Gastroenterology
Cysteinylation of albumin leads to reduced antioxidant activity in non-alcoholic fatty liver disease
patients
Abhishak C Gupta
Indian Institute of Technology Delhi, India
Backgrounds &Aim:Oxidative stress is postulated to play an important role in liver disease progression.The degree of oxidized
cysteine (Cys) 34 in Human Serum Albumin (HSA) is correlated with oxidative stress related to pathological conditions and
modulates its physiological function. Present study aim is to develop a noninvasive diagnostic marker for Non-Alcoholic
Fatty Liver Disease (NAFLD) by studying the differential modification pattern of albumin and antioxidant activity in NAFLD
patients.
Patients & Methods: We analyzed purified plasma albumin from 46 biopsy-proven NAFLD patients and 21 matched healthy
blood donors. The albumin modifications were analyzed by liquid chromatography coupled with electrospray ionization time-
of-flight mass spectrometer (ESI-TOF/MS). Relative % abundance of unmodified (intact) and modified isoforms of albumin
was compared between NAFLD and controls. In vitro ROS generation and antioxidant activity was measured by Mean
Fluorescence Intensity (MFI) of Dihydrorhodamine (DHR) by flow cytometry in presence of purified albumin of controls and
NALFD patients.
Results: Three most prominent isoforms of albumin were observed in the de-convoluted ESI spectrum with molecular masses
of 66,438±2.8, 66,559±4.8 and 66,603±6 Da in controls and NAFLD patients represents intact, cysteinylated and glycated
isoforms of albumin respectively. Unmodified albumin was the predominant peak with 100% relative abundance in healthy
subjects in perfect agreement with calculated theoretical mass (66,438 Da, 542 aa). In contrast, the relative abundance of
modified formwith addition of +119Da (cysteinylation) of albuminwas predominant (100%) inNAFLDpatients. Cysteinylated
isoform of albumin (cys-Alb) was significantly higher in NAFLD patients than controls [100% v/s 52% (p<0.01)]. Although
NAFLD showed 100% relative abundance of cys-Alb isoform further fatty liver and NASH patients differ on the basis of
unmodified albumin isoforms [82% vs. 60% (p<0.05)] suggesting varied oxidative stress. Circular dichroism (CD) spectrum
showed clear structural alterations in purified albumin from NAFLD patients as compared to purified albumin from controls.
Further, purified albumin antioxidant activity was measured by removal of ROS productions in vitro. Significant differences
were observed in mean fluorescence intensity of DHR in presence of purified albumin from controls and patients (51.5±5.8%
vs. 60.3±13.8%, p<0.001) suggest reduced antioxidant activity of albumin in NAFLD patients. Three most prominent isoforms
of albumin were observed in de-convoluted ESI spectrum with molecular masses of 66,438±2.8, 66,559±4.8 and 66,603±6 Da
in controls and NAFLD patients represents intact, cysteinylated and glycated isoforms of albumin, respectively. Intact peak
with 100% relative abundance in healthy subjects in perfect agreement with calculated theoretical mass (66,438 Da, 542 aa).
In contrast, the relative abundance of modified form with addition of +119Da (cysteinylation) of albumin was predominant
(100%) in NAFLD patients. Cysteinylated isoform of albumin (cys-Alb) was significantly higher in NAFLD patients than
controls [100% v/s 52%, p<0.01].
Conclusion: Our results clearly showed that sustained oxidative stress and reduced antioxidant activity is reflected by high
levels of cysteinylated albumin in NAFLD patients and might be useful plasma marker for oxidative damage in NAFLD/NASH.
Abhishak C Gupta, J Gastrointest Dig Syst 2018, Volume 8
DOI: 10.4172/2161-069X-C2-067