Proinflammatory cytokines expression in noise-induced damaged cochlea

Masato Fujioka, Sho Kanzaki, Hirotaka James Okano, Masatsugu Masuda, Kaoru Ogawa, Hideyuki Okano

Research output: Contribution to journalArticle

160 Citations (Scopus)

Abstract

Recent studies have showed that inflammatory responses occur in inner ear under various damaging conditions including noise-overstimulation. We evaluated the time-dependent expression of proinflammatory cytokines in noise-exposed rat cochlea. Among several detected cytokines, real-time RT-PCR showed that interleukin-1beta (IL-1β) and interleukin-6 (IL-6) were significantly induced 3 hr after noise exposure, and quickly downregulated to the basal level. Tumor necrosis factor-alpha (TNF-α) was also slightly upregulated immediately after noise exposure, Immunohistochemical analysis showed that IL-6 expression was distinctively induced within the lateral side of the spiral ligament. Sequential expression analysis showed that IL-6 immunoreactivity was initially found in the cytoplasm of lateral wall cells, including Type IV and III fibrocytes, and expanded broader throughout the lateral wall, finally to the stria vascularis. Because of the negative Iba-1 staining, IL-6 expression in the early-phase was not due to macrophage or microglia activation. IL-6 was also detected in spiral ganglion neurons at 12 and 24 hr after noise exposure. Our data demonstrates the production of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6, in early phase of noise overstimulated cochlea. IL-6 expression was observed in the spiral ligament, stria vascularis, and spiral ganglion neurons. These cytokines, produced by the cochlear structure itself in response to noise exposure, may initiate an inflammatory response and have some role in the mechanism of noise-induced cochlear damage.

Original languageEnglish
Pages (from-to)575-583
Number of pages9
JournalJournal of Neuroscience Research
Volume83
Issue number4
DOIs
Publication statusPublished - 2006 Mar

Fingerprint

Cochlea
Noise
Interleukin-6
Cytokines
Spiral Ligament of Cochlea
Stria Vascularis
Spiral Ganglion
Interleukin-1beta
Tumor Necrosis Factor-alpha
Neurons
Microglia
Inner Ear
Cell Wall
Real-Time Polymerase Chain Reaction
Cytoplasm
Down-Regulation
Macrophages
Staining and Labeling

Keywords

  • Cochlea damage
  • Cytokines
  • Gene expression
  • Hearing
  • Inflammation

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Proinflammatory cytokines expression in noise-induced damaged cochlea. / Fujioka, Masato; Kanzaki, Sho; Okano, Hirotaka James; Masuda, Masatsugu; Ogawa, Kaoru; Okano, Hideyuki.

In: Journal of Neuroscience Research, Vol. 83, No. 4, 03.2006, p. 575-583.

Research output: Contribution to journalArticle

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