the association between circulating klotho and dipeptidyl peptidase-4 activity and inflammatory cytokines in elderly patients with alzheimer disease

Introduction: klotho and dipeptidyl peptidase-4 (dpp4) are two proteins that modulate inflammatory pathways. we investigated the association between circulating klotho and dpp4 activity and their relationship with inflammatory cytokines, mir-29a, and mir-195 in alzheimer disease (ad). methods: this study was conducted on 16 ad patients and 16 healthy age-matched controls. plasma levels of tumor necrosis factor-alpha (tnf-α), interleukin-1 beta (il-1β, interleukin-6 (il-6), klotho, and dpp4 were measured by enzyme-linked immunosorbent assay. plasma expression of mir-29a and mir-195 were also measured and compared by a real-time polymerase chain reaction. results: there was a significant increase in tnf-α (p=0.006), il-1β (p=0.012), and il-6 (p=0.012) levels in the ad subjects compared with controls. also, we found a decrease in plasma levels of klotho and an increase in plasma levels of dpp4 in the ad group that was not significant compared with the controls. lower expression of mir-29a (p=0.009) and higher expression of mir-195 (p=0.003) were observed in the ad group that was significant than controls. further analysis showed a negative correlation between klotho and plasma levels of il-6 (r=-0.58, p=0.01). also, there was a positive correlation between plasma dpp4 activity and tnf-α levels (r=0.50, p=0.04) and il-1β (r=0.62, p=0.01). likewise, plasma klotho concentration showed a negative correlation with the age of ad subjects (r=-0.56, p=0.02). conclusion: tnf-α, il-1β, and il-6 are involved in ad pathophysiology, and dysregulation of dpp4 and klotho may be associated with the inflammatory response of ad. down-regulation of mir-29a and up-regulation of mir‑195 indicated the role of mirnas in the ad process.