Functional role for interleukin‐1 in the injured peripheral taste system

Abstract

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 which 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 (CNS).

Targeting Imbalance between IL-1β and IL-1 Receptor Antagonist Ameliorates Delayed Epithelium Wound Healing in Diabetic Mouse Corneas

“…26 In the literature, IL-1Ra was shown to either play a protective role against transthyretin-mediated axonal loss in a mouse model of familial amyloidotic polyneuropathy 55 or impair taste responses in the intact chorda tympani after nearby injury. 56 Our results indicate a supportive role of IL-1Ra in the DM cornea and corroborate the potential use of IL-1Ra in promoting sensory nerve regeneration in DM peripheral tissues.…”

Differential Expression of Immune Related Genes in Taste Buds of Fed and Fasted Mice

“…Differential regulation of chemokine and immune related transcripts between hungry and satiated mice is particularly intriguing, as immune cytokine signaling seems to be involved in taste cell communication (Feng et al 2014b; Hevezi et al 2009). Specifically, subpopulations of TRCs express interferon-γ, tumor necrosis factor, interlukin-10, and their cognate receptors (Feng et al 2014a; Feng et al 2012; Shi et al 2012; Wang et al 2007). They also express multiple types of toll-like receptors (Wang et al 2009), which are responsible for detecting pathogenic microbial proteins.…”

Ingestion of bacterial lipopolysaccharide inhibits peripheral taste responses to sucrose in mice

“…At the same time, we recognize the complexity of potential hormonal and cytokine signaling upstream from Tas1r2/3 mRNA. For example, LPS acutely increases circulating leptin levels in mice and rats via IL-1β (Fantuzzi and Faggioni, 2000), which is constitutively expressed in fungiform taste buds along with the IL-1 receptor (Shi et al, 2012). …”