| First Author | Nishimoto S | Year | 2018 |
| Journal | Front Cardiovasc Med | Volume | 5 |
| Pages | 144 | PubMed ID | 30460242 |
| Mgi Jnum | J:289665 | Mgi Id | MGI:6433178 |
| Doi | 10.3389/fcvm.2018.00144 | Citation | Nishimoto S, et al. (2018) Activation of Toll-Like Receptor 9 Impairs Blood Flow Recovery After Hind-Limb Ischemia. Front Cardiovasc Med 5:144 |
| abstractText | Background: Peripheral artery disease causes significant functional disability and results in impaired quality of life. Ischemic tissue injury releases various endogenous ligands for Toll-like receptors (TLRs), suggesting the involvement of TLRs in blood flow recovery. However, the role of TLR9, which was originally known as a sensor for bacterial DNA, remains unknown. This study investigated the role of TLR9 in blood flow recovery in the ischemic limb using a mouse hind-limb ischemia model. Methods and Results: Unilateral femoral artery ligation was performed in TLR9-deficient (Tlr9 (-/-)) mice and wild-type mice. In wild-type mice, femoral artery ligation significantly increased mRNA expression of TLR9 in the ischemic limb (P < 0.001) and plasma levels of cell-free DNA (cfDNA) as determined by single-stranded DNA (ssDNA) (P < 0.05) and double-stranded DNA (dsDNA) (P < 0.01), which are endogenous ligands for TLR9, compared with the sham-operated group. Laser Doppler perfusion imaging demonstrated significantly improved ratio of blood flow in the ischemic to non-ischemic limb in Tlr9 (-/-) mice compared with wild-type mice at 2 weeks after ligation (P < 0.05). Tlr9 (-/-) mice showed increased capillary density and reduced macrophage infiltration in ischemic limb. Genetic deletion of TLR9 reduced the expression of TNF-alpha, and attenuated NF-kappaB activation in ischemic muscle compared with wild-type mice (P < 0.05, respectively) at 3 days after the surgery. ODN1826, a synthetic agonistic oligonucleotide for TLR9, or plasma obtained from mice with ischemic muscle promoted the expression of TNF-alpha in wild-type macrophages (P < 0.05), but not in Tlr9 (-/-) macrophages. ODN1826 also activated NF-kappaB signaling as determined by the degradation of IkappaBalpha in wild-type macrophages (P < 0.05), but not in Tlr9 (-/-) macrophages. In vitro experiments using human umbilical vein endothelial cells demonstrated that TNF-alpha, or conditioned medium obtained from wild-type macrophages treated with ODN1826 accelerated cell death as determined by MTS assay (P < 0.05 and P < 0.01, respectively). Conclusion: Our results suggest that ischemic muscle releases cfDNA, which activates TLR9 and enhances inflammation, leading to impairment of blood flow recovery in the ischemic limb. cfDNA-TLR9 signaling may serve as a potential therapeutic target in ischemic limb disease. |
