Mitochondrial Common Deletion Level in Adipose Tissue is Not Associated with Obesity but is Associated with a Structural Change in Triglycerides as Revealed by FTIR Spectroscopy

Abstract

Objective: Several studies have shown that the mitochondrial metabolism may be disrupted if the rate of the specific 4977 bp deletion of mitochondrial DNA (mtDNA) reaches a threshold. This study aims to investigate the possible associations between the mtDNA4977 deletion load and obesity-related metabolic abnormalities in the adipose tissue.Methods: The study included thirty obese individuals, who underwent bariatric surgery, and twelve control subjects. mtDNA4977 deletion, adenine nucleotides and lactate levels, which show the bioenergetic status were evaluated in visceral adipose tissues. Fourier transform infrared (FTIR) spectroscopy was used to investigate the structural variations and composition of adipose tissue in the context of deletion load.Results: There were no differences between the two groups in terms of mtDNA4977 deletion, adenine nucleotides, and lactate levels. The FTIR spectra indicated a few obesity-related alterations in adipose tissue that were not related to the mtDNA deletion load. Also, statistical analysis showed a correlation between deletion load and a band shift of 1744 cm(-1), which assigns C = O stretching of the carbonyl group of the ester group in triglycerides and other esterified fatty acids, although it is not associated with obesity.Conclusions: Our data suggest that the mtDNA4977 deletion in visceral adipose tissue of obese individuals do not have a significant impact on bioenergetic status. However, the increased accumulation of deletion may be associated with a specific change in the ester bond, indicating structural differences in the lipids. These findings shed light on our understanding of the tissue-specific distribution of mtDNA deletions and obesity-related adipose tissue pathogenesis.