FTIR study of Achilles tendinopathy: protein secondary structure changes in tendon post injury

Abstract Introduction Tendinopathy, a disease involving tendon inflammation and damage, results in considerable productivity and economic losses for the patient and the society. Currently available diagnosis/ treatment monitoring modalities are less efficacious and highly subjective, underlying the need for better tools. Previously, we have shown that Fourier Transform Infrared (FTIR) spectroscopy has potential in tendinopathy diagnosis/ monitoring, when combined with multivariate statistical analysis. The current study explores the spectral range that gave the best results in statistical analysis, to discover protein secondary structures associated with tendon injury and recovery that can act as markers of disease. Methods Animals (n=60) underwent a surgery in which Achilles tendon were injured by dropping a 20g weight. Rats were divided into three groups (n=20) – control (C), Achilles tendon injury (I) and Achilles tendon injury treated with amniotic membrane fragment treated (T). FTIR spectra were obtained from each group 3, 7, 14, and 28 days post injury/ treatment. Results Triple helix, β-turn, and disordered structure levels differ between control, injured and treated tendons over the time period studied. Parallel β-sheets increase steadily over time in treated tendons compared to control and injured. Conclusion Combined analysis of Triple helix, β- sheets, β-turn, and disordered structure levels may be useful for tendinopathy diagnosis and treatment monitoring. However, further studies in this area are required to confirm the findings.