The Ratio of Biological Health Score to Immune Cell Telomere Length: A Reliable Index Indicating the Association Between the Severity of Injury and Senescence in Mustard-chemical Veterans

Abstract

Background: Sulfur mustard (SM), a chemical weapon used in the Iraq-Iran war from 1983-1988, has multiple chronic complications. This study aimed to evaluate one of the long-act effects of SM, i.e. the senescence according to the severity of injury in veterans via the estimation of biological health score (BHS) and relative telomere length (TL) of immune cells. Materials and Methods: SM-chemical veterans were categorized into three groups according to the percentage of chemical injury (5-20%, 25-45%, and 50-70%). Healthy volunteers also participated as a control group. Eighteen biomarkers from different physiological systems (inflammatory/immune, endocrine, cardiovascular, and metabolic), and organs (liver and kidney) were used to estimate BHS. The TL of immune cells was also measured for each participant by monochrome multiplex real-time PCR. Results: There were significant correlations between age-adjusted TL (negative), BHS, and BHS/TL ratio (positive) and the percentage of injury. The TL was significantly decreased in all veterans with different injuries compared to healthy participants while it did not change in veterans with the injury percentages of 25-45% and 50-70%. The BHS in three groups of veterans was significantly higher than in healthy individuals. The BHS/TL ratio was significantly changed between all groups and increased with the progress of injury. Conclusion: The BHS and TL may not individually be accurate indices for the determination of senescence and biological aging while the ratio of these two parameters improves this defect and could be a more reliable index indicating biological aging in chemical veterans with different percentages of injury.