Publication: Upregulation of TLR9 may contribute to activation of microglia and painful diabetic neuropathy via the p38 MAPK pathway in rats
Authors
Niu, Zhaoxia ; Bao, Lei ; Chen, Jing
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Publisher
Universidad de Murcia, Departamento de Biologia Celular e Histiologia
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DOI
https://doi.org/10.14670/HH-18-405
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info:eu-repo/semantics/article
Description
Abstract
Painful diabetic neuropathy is a common
chronic complication of diabetes, and the underlying
mechanism remains largely elusive. A rat model of
painful diabetic neuropathy was established via
streptozotocin (STZ) injection and assessed as increased
heat and mechanical hypersensitivity. An upregulation of
TLR9 was observed in the spinal cords of rats injected
with STZ and rat microglia (primary microglia and
immortalized microglia HAPI) treated with high
glucose. To investigate the role of TLR9 in high glucoseinduced microglia activation, short hairpin RNAs
targeting TLR9 were used in vitro to knock down TLR9
in HAPI cells. TLR9 interference suppressed the high
glucose-induced expression and secretion of
inflammatory cytokines (TNF-α, IL-1β, and IL-6), IBA1 expression and the chemotaxis of HAPI microglia.
Similar results were obtained when HAPI microglia
were incubated with a p38 inhibitor (SB203580). P38
and ERK were downstream of TLR9 because TLR9
ablation markedly inhibited the phosphorylation of p38
and ERK. TLR9 was also knocked down in vivo via the
injection of shTLR9 lentiviral vector into the rat spinal
cord. Relief of STZ-induced heat and mechanical
hypersensitivity was observed in rats with TLR9
interference, and TLR9 knockdown prevented STZinduced inflammatory cytokine secretion and microglial
and MAPK signaling activation. Our study revealed the
participation of TLR9 in microglial activation and
diabetes-induced hyperalgesia likely via the MAPK
pathway. The targeting of TLR9 may be an effective
strategy for the treatment of painful diabetic neuropathy.
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Citation
Histology and Histopathology Vol. 37, nº1 (2022)
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Este ítem está sujeto a una licencia Creative Commons. http://creativecommons.org/licenses/by-nc-nd/4.0/