Limits...
Down-regulation of Toll-like receptor 4 gene expression by short interfering RNA attenuates bone cancer pain in a rat model.

Lan LS, Ping YJ, Na WL, Miao J, Cheng QQ, Ni MZ, Lei L, Fang LC, Guang RC, Jin Z, Wei L - Mol Pain (2010)

Bottom Line: We hypothesized that after intramedullary injection of Walker 256 cells (a breast cancer cell line) into the tibia, CNS neuroimmune activation and subsequent cytokine expression are triggered by the stimulation of microglial membrane-bound TLR4.The bone cancer pain rats treated with TLR4 siRNA displayed significantly attenuated behavioral hypersensitivity and decreased expression of spinal microglial markers and proinflammatory cytokines compared with controls.Further study of this early, specific, and innate CNS/microglial response, and how it leads to sustained glial/neuronal hypersensitivity, might lead to new therapies for the prevention and treatment of bone cancer pain syndromes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, China.

ABSTRACT

Background: This study demonstrates a critical role in CNS innate immunity of the microglial Toll-like receptor 4 (TLR4) in the induction and maintenance of behavioral hypersensitivity in a rat model of bone cancer pain with the technique of RNA interference (RNAi). We hypothesized that after intramedullary injection of Walker 256 cells (a breast cancer cell line) into the tibia, CNS neuroimmune activation and subsequent cytokine expression are triggered by the stimulation of microglial membrane-bound TLR4.

Results: We assessed tactile allodynia and spontaneous pain in female Sprague-Dawley (SD) rats after intramedullary injection of Walker 256 cells into the tibia. In a complementary study, TLR4 small interfering RNA(siRNA) was administered intrathecally to bone cancer pain rats to reduce the expression of spinal TLR4. The bone cancer pain rats treated with TLR4 siRNA displayed significantly attenuated behavioral hypersensitivity and decreased expression of spinal microglial markers and proinflammatory cytokines compared with controls. Only intrathecal injection of TRL4 siRNA at post-inoculation day 4 could prevent initial development of bone cancer pain; intrathecal injection of TRL4 siRNA at post-inoculation day 9 could attenuate, but not completely block, well-established bone cancer pain.

Conclusions: TLR4 might be the main mediator in the induction of bone cancer pain. Further study of this early, specific, and innate CNS/microglial response, and how it leads to sustained glial/neuronal hypersensitivity, might lead to new therapies for the prevention and treatment of bone cancer pain syndromes.

Show MeSH

Related in: MedlinePlus

Decreased bone cancer pain-induced microglial activation and proinflammatory cytokine expression by Intrathecal TLR4 siRNA439. In both IBCP group and WBCP group, Real-time quantitative RT-PCR analyses revealed a significant down-regulation of two microglial activation markers, CD14 and CD11b compared with mismatch siRNA- and vehicle-treated rats(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing, df = 3, F = 1.08). Proinflammatory cytokines mRNA expression was also significantly down-regulated, i.e., IL-1β (P < 0.01), TNF-α (P < 0.05), IL-6 (P < 0.01), and INF-β (P < 0.01) in the WBCP group; IL-1β (P < 0.01), and TNF-α (P < 0.01) in the IBCP group compared with rats treated with vehicle or the mismatch siRNA. Values are presented as mean ± SEM. *P < 0.05, **P < 0.01 vs. normal group; ▲ P < 0.05, ▲▲ P < 0.01 vs. vehicle-treated group; ◆P < 0.05, ◆◆P < 0.01 vs. mismatch siRNA-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2819998&req=5

Figure 7: Decreased bone cancer pain-induced microglial activation and proinflammatory cytokine expression by Intrathecal TLR4 siRNA439. In both IBCP group and WBCP group, Real-time quantitative RT-PCR analyses revealed a significant down-regulation of two microglial activation markers, CD14 and CD11b compared with mismatch siRNA- and vehicle-treated rats(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing, df = 3, F = 1.08). Proinflammatory cytokines mRNA expression was also significantly down-regulated, i.e., IL-1β (P < 0.01), TNF-α (P < 0.05), IL-6 (P < 0.01), and INF-β (P < 0.01) in the WBCP group; IL-1β (P < 0.01), and TNF-α (P < 0.01) in the IBCP group compared with rats treated with vehicle or the mismatch siRNA. Values are presented as mean ± SEM. *P < 0.05, **P < 0.01 vs. normal group; ▲ P < 0.05, ▲▲ P < 0.01 vs. vehicle-treated group; ◆P < 0.05, ◆◆P < 0.01 vs. mismatch siRNA-treated group.

Mentions: Decreased expression of TLR4 was coincident with decreased expression of the microglial activation markers CD11b (48% in IBCP group; 39% in WBCP group) and CD14 (43%; 30%)(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing). The decrease in TLR4 also led to a significant decrease in proinflammatory cytokines, i.e., TNF-α (31%; 20%), IL-1β (35%; 33%), IL-6 (16%; 31%), and INF-β (16%; 58%) compared with rats treated with vehicle or the mismatch siRNA (Fig. 7).


Down-regulation of Toll-like receptor 4 gene expression by short interfering RNA attenuates bone cancer pain in a rat model.

Lan LS, Ping YJ, Na WL, Miao J, Cheng QQ, Ni MZ, Lei L, Fang LC, Guang RC, Jin Z, Wei L - Mol Pain (2010)

Decreased bone cancer pain-induced microglial activation and proinflammatory cytokine expression by Intrathecal TLR4 siRNA439. In both IBCP group and WBCP group, Real-time quantitative RT-PCR analyses revealed a significant down-regulation of two microglial activation markers, CD14 and CD11b compared with mismatch siRNA- and vehicle-treated rats(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing, df = 3, F = 1.08). Proinflammatory cytokines mRNA expression was also significantly down-regulated, i.e., IL-1β (P < 0.01), TNF-α (P < 0.05), IL-6 (P < 0.01), and INF-β (P < 0.01) in the WBCP group; IL-1β (P < 0.01), and TNF-α (P < 0.01) in the IBCP group compared with rats treated with vehicle or the mismatch siRNA. Values are presented as mean ± SEM. *P < 0.05, **P < 0.01 vs. normal group; ▲ P < 0.05, ▲▲ P < 0.01 vs. vehicle-treated group; ◆P < 0.05, ◆◆P < 0.01 vs. mismatch siRNA-treated group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2819998&req=5

Figure 7: Decreased bone cancer pain-induced microglial activation and proinflammatory cytokine expression by Intrathecal TLR4 siRNA439. In both IBCP group and WBCP group, Real-time quantitative RT-PCR analyses revealed a significant down-regulation of two microglial activation markers, CD14 and CD11b compared with mismatch siRNA- and vehicle-treated rats(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing, df = 3, F = 1.08). Proinflammatory cytokines mRNA expression was also significantly down-regulated, i.e., IL-1β (P < 0.01), TNF-α (P < 0.05), IL-6 (P < 0.01), and INF-β (P < 0.01) in the WBCP group; IL-1β (P < 0.01), and TNF-α (P < 0.01) in the IBCP group compared with rats treated with vehicle or the mismatch siRNA. Values are presented as mean ± SEM. *P < 0.05, **P < 0.01 vs. normal group; ▲ P < 0.05, ▲▲ P < 0.01 vs. vehicle-treated group; ◆P < 0.05, ◆◆P < 0.01 vs. mismatch siRNA-treated group.
Mentions: Decreased expression of TLR4 was coincident with decreased expression of the microglial activation markers CD11b (48% in IBCP group; 39% in WBCP group) and CD14 (43%; 30%)(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing). The decrease in TLR4 also led to a significant decrease in proinflammatory cytokines, i.e., TNF-α (31%; 20%), IL-1β (35%; 33%), IL-6 (16%; 31%), and INF-β (16%; 58%) compared with rats treated with vehicle or the mismatch siRNA (Fig. 7).

Bottom Line: We hypothesized that after intramedullary injection of Walker 256 cells (a breast cancer cell line) into the tibia, CNS neuroimmune activation and subsequent cytokine expression are triggered by the stimulation of microglial membrane-bound TLR4.The bone cancer pain rats treated with TLR4 siRNA displayed significantly attenuated behavioral hypersensitivity and decreased expression of spinal microglial markers and proinflammatory cytokines compared with controls.Further study of this early, specific, and innate CNS/microglial response, and how it leads to sustained glial/neuronal hypersensitivity, might lead to new therapies for the prevention and treatment of bone cancer pain syndromes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anesthesiology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu 215006, China.

ABSTRACT

Background: This study demonstrates a critical role in CNS innate immunity of the microglial Toll-like receptor 4 (TLR4) in the induction and maintenance of behavioral hypersensitivity in a rat model of bone cancer pain with the technique of RNA interference (RNAi). We hypothesized that after intramedullary injection of Walker 256 cells (a breast cancer cell line) into the tibia, CNS neuroimmune activation and subsequent cytokine expression are triggered by the stimulation of microglial membrane-bound TLR4.

Results: We assessed tactile allodynia and spontaneous pain in female Sprague-Dawley (SD) rats after intramedullary injection of Walker 256 cells into the tibia. In a complementary study, TLR4 small interfering RNA(siRNA) was administered intrathecally to bone cancer pain rats to reduce the expression of spinal TLR4. The bone cancer pain rats treated with TLR4 siRNA displayed significantly attenuated behavioral hypersensitivity and decreased expression of spinal microglial markers and proinflammatory cytokines compared with controls. Only intrathecal injection of TRL4 siRNA at post-inoculation day 4 could prevent initial development of bone cancer pain; intrathecal injection of TRL4 siRNA at post-inoculation day 9 could attenuate, but not completely block, well-established bone cancer pain.

Conclusions: TLR4 might be the main mediator in the induction of bone cancer pain. Further study of this early, specific, and innate CNS/microglial response, and how it leads to sustained glial/neuronal hypersensitivity, might lead to new therapies for the prevention and treatment of bone cancer pain syndromes.

Show MeSH
Related in: MedlinePlus