IL-21 receptor expression in human tendinopathy.

Area of Science:

• Biomedical science
• Immunology
• Orthopedics

Background:

• Tendinopathy pathogenesis is debated, with evidence suggesting early inflammation.
• The Interleukin-21 (IL-21)/IL-21 receptor (IL-21R) axis is implicated in chronic inflammatory diseases.

Purpose of the Study:

• To investigate the role and expression of the IL-21/IL-21R axis in human tendinopathy.
• To determine if IL-21R is present and upregulated in early tendinopathy.

Main Methods:

• Analysis of human tendon samples for IL-21 and IL-21R expression at message and protein levels.
• In vitro studies using human tenocytes treated with proinflammatory cytokines (TNFα/IL-1β).

Main Results:

• Significantly elevated IL-21 receptor (IL-21R) message and protein expression were found in human tendinopathy samples.
• No convincing evidence of IL-21 presence was detected.
• Proinflammatory cytokines upregulated IL-21R expression in human tenocytes.
• IL-21R was primarily expressed by tenocytes and macrophages in early tendinopathy.

Conclusions:

• Early human tendinopathy exhibits an inflammatory/cytokine phenotype.
• IL-21R is present and upregulated in early tendinopathy, suggesting its potential role.
• These findings may offer novel therapeutic targets for tendinopathy treatment.