Measurements of Oxidative Stress in Plasma and Adipose Tissues in Obese Patients after Abdominal Weight Lose Surgery
¹Lindsey Holloman, Aimin Li, M.D., Jason M. Hanson, Ph.D., Nana Gletsu-Miller, Ph.D., Edward Lin, D.O.
¹Departments of Surgery and Pediatrics, Emory University School of Medicine Atlanta, GA

Abstract

Background: Excess adipose tissue, classified as obesity, secretes an excess amount of cytokines as a result of trauma. This could induce changes in oxidative stress, which may contribute to the onset of insulin resistance.

In this pilot study, we determined oxidative changes by analyzing the redox balance of GSH/GSSG in visceral and subcutaneous adipose tissues and the Cys/CySS balance in plasma from obese patients before and after weight loss surgery.

Oxidative stress increased in response to surgical trauma in adipose tissues, but not in plasma. Furthermore, there were differences in the change of oxidative stress in patients depending on which surgery they had undergone. These preliminary findings will form the basis of a larger study to investigate the relationships between obesity and oxidative stress.

Introduction

• Adipose tissue secretes a number of inflammatory cytokines locally and systemically, normally released as a result of trauma or sickness.
• Therefore, obesity is a state of chronic inflammation, inducing excess cytokines which may lead to oxidative stress and promote insulin resistance.
• Oxidative stress is an imbalance between oxidants, which damage lipids, proteins, and DNA in the body, and antioxidants, which protect against damage.
• Few studies have determined the relationship between excess adipose tissue and oxidative stress.
• Obese patients may undergo a variety of weight loss surgeries which include adjustable banding surgery, where a constrictive band is placed around the stomach, and Roux-en-Y gastric bypass surgery, where stomach size is decreased and most of the small intestine is bypassed.
• In patients undergoing surgical trauma, we determined changes in oxidative stress in plasma and in adipose tissue biopsies.

Methods and Materials

• Subcutaneous (SAT) and visceral adipose tissue (VAT) as well as plasma samples were obtained from six severely obese patients immediately before and after gastric bypass (n=2) and adjustable banding (n=4) surgery.
• Tissue and plasma samples were treated and prepared for redox analysis using High Performance Liquid Chromatography (HPLC).
• In adipose tissues, DNA was quantified using Quant-iT PicoGreen fluorescent assay [invitrogen, California U.S.A].
• The subcutaneous and visceral adipose tissues were assessed using an HPLC analysis to quantify the amounts of glutathione (GSH) and glutathione disulfide (GSSG) and redox status (GSH/GSSG).
• Plasma samples were also assessed by HPLC to quantify cysteine (Cys) and cystine (CySS) concentrations and Cys redox status (Eh Cys/CySS).

Objective
To determine the effects of obesity on oxidative stress in abdominal adipose tissue and plasma following surgical trauma.

Results

Figure 1. In plasma, Cys/CySS decreased in obese patients post surgery indicating a decrease in oxidative stress, p>0.05.


Figure 2. Oxidative stress increased in adipose tissue after surgery, indicated by a decrease in redox status, p>0.05.
Figure 3. Gastric bypass surgery patients showed an increase in oxidative stress in visceral adipose tissue, however adjustable banding surgery patients showed no change in oxidative stress, p>0.05.


Figure 4. Gastric bypass patients tended to show an increase in oxidative stress following surgery while adjustable banding surgery patients showed no change, p>0.05.

Conclusions and Future Studies

• Obese patients generally exhibit an increase in oxidative stress immediately following surgery in adipose tissues.
• Plasma showed a slight decrease in oxidative stress post surgery in obese patients.
• In gastric bypass patients, visceral and subcutaneous adipose tissues indicated an increase in oxidative stress while lab-band surgery patients did not.
• The differences in response to surgery may be due to the varying lengths of surgery time which may be determined in future studies.

Resources

This material is based upon work supported by the Howard Hughes Medical Institute under Grant No. 52005873 and by the National Science Foundation Award under Grant No. 0450303 (Subaward No. I-66-606-63 to Emory University).

References

1. Gletsu et.al. Surgery 140: 50-57, 2006
2. Jones. Antioxidants & Redox Signaling 8: 1865-1879, 2006
3. Van Gaal, et.al. Nature 444: 875-879, 2006