Functional role for interleukin-1 in the injured peripheral taste system.
The peripheral taste system presents an excellent model for studying the consequences of neural injury, for the damaged nerve and sensory cells and the neighboring, intact neural cells. Sectioning a primary afferent nerve, the chorda tympani (CT), rapidly recruits neutrophils to both sides of the tongue. The bilateral neutrophil response induces transient functional deficits in the intact CT. Normal function is subsequently restored as macrophages respond to injury. We hypothesized that macrophages produce the proinflammatory cytokine interleukin (IL)-1, which contributes to the maintenance of normal taste function after nearby injury. We demonstrate that IL-1β protein levels are significantly increased on the injured side of the tongue at day 2 after injury. Dietary sodium deficiency, a manipulation that prevents macrophage recruitment, inhibits the elevation in IL-1β. IL-1β was expressed in several cell populations, including taste receptor cells and infiltrating neutrophils and macrophages. To test whether IL-1 modulates taste function after injury, we blocked signaling with an IL-1 receptor antagonist (IL-1 RA) and recorded taste responses from the intact CT. This treatment inhibited the bilateral macrophage response to injury and impaired taste responses in the intact CT. Cytokine actions in the taste system are largely unstudied. These results demonstrate that IL-1 has a beneficial effect on taste function after nearby injury, in contrast to its detrimental role in the injured central nervous system.
Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, GA 30912-3000, USA.
Liqiao
L
Shi
Lianying
L
He
Padma
P
Sarvepalli
Lynnette Phillips
LP
McCluskey
D000704:Analysis of Variance; D000818:Animals; D002814:Chorda Tympani Nerve / Q000473:pathology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D053331:Ectodysplasins / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005155:Facial Nerve Diseases / Q000276:immunology / Q000473:pathology* / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality; D005786:Gene Expression Regulation / Q000502:physiology*; D053590:Interleukin 1 Receptor Antagonist Protein / Q000494:pharmacology; D053583:Interleukin-1beta / Q000378:metabolism*; D007962:Leukocytes / Q000187:drug effects; D008264:Macrophages / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000494:pharmacology; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000378:metabolism
D053331:Ectodysplasins; D053590:Interleukin 1 Receptor Antagonist Protein; D053583:Interleukin-1beta; D017472:Receptors, Interleukin-1; D012982:Sodium, Dietary