Purpose: Weight loss from bariatric surgery can lead to the reversal of several obesity related disorders, such as diabetes. Obestatin is a peptide produced by gastric tissue which is cleaved and processed from pre-proghrelin and may have a role in appetite satiation. In humans, an inverse relationship between obestatin and body mass index has been established. The aim of the study was to assess the relationship between weight loss after bariatric surgery and circulating hormones and cytokines.
Methods: After informed consent, serum samples were collected from patients undergoing bariatric surgery (collected immediately prior to surgery). Baseline and follow up (f/u) clinical and laboratory data were collected. Fasting serum was assayed for obestatin, acylated and desacylated ghrelin concentrations using sandwich ELISA. Additionally, for all patients, IL6, IL7, IL8, G-CSF, CCL2 and MIP-1b were also assayed. Pearson correlations were calculated.
Results: A total of 35 patients were included (age 45.9 years, gender 25.7% male, median length of f/u after surgery: 53 weeks, baseline BMI: 47.5, f/u BMI: 33.4, baseline DM (25.7%), f/u DM (2.9%), baseline hyperlipidemia (42.9%), f/u hyperlipidemia (8.6%). For the entire length of f/u, the average weight loss per day for the cohort was 0.22 Kg/day. However, this weight loss was faster during the first three months (0.49 Kg/day) and even for the first 24 months (0.29 Kg/day). The only circulating hormone that correlated with rate of weight loss was baseline level of serum obestatin. Although baseline obestatin concentration correlated with the rate of weight loss for the entire cohort and for entire duration of f/u (r=0.515, P=0.002), the strongest correlation between baseline circulating obestatin and rate of weight loss was seen within the first three months (r=0.699, P=0.024). Additionally, the correlation between baseline obestatin and rate of weight loss remained surprisingly strong for up to 24 months after surgery (r=0.664, P=0.002).
Conclusion: Rate of post bariatric surgery weight loss may be associated with baseline circulating obestatin levels. A high baseline obestatin level can be strongly associated with the rate of weight loss after bariatric surgery.