Canonical NF-κB p65, but Not p105, Contributes to IL-1β-Induced IL-8 Expression in Cardiac Fibroblasts

Area of Science:

• Cardiovascular Biology
• Immunology
• Cellular Signaling

Background:

• Cardiac fibroblasts act as sentinel cells in cardiac inflammation.
• Interleukin-8 (IL-8) is vital for innate immunity, recruiting immune cells like neutrophils to inflammatory sites.

Purpose of the Study:

• To investigate the effect of the proinflammatory cytokine, interleukin-1β (IL-1β), on interleukin-8 (IL-8) expression in canine cardiac fibroblasts.
• To elucidate the signaling pathway involved in IL-1β-induced IL-8 expression.

Main Methods:

• Dose- and time-dependent analysis of IL-1β's effect on IL-8 mRNA and protein.
• Inhibition studies using a nuclear factor-kappa B (NF-κB) inhibitor.
• Western blotting to assess NF-κB p65 and p105 phosphorylation.
• Small interfering RNA (siRNA) transfections targeting NF-κB p65 and p105.

Main Results:

• IL-1β significantly increased IL-8 mRNA expression and protein release in a dose- and time-dependent manner.
• An NF-κB inhibitor suppressed IL-1β-induced IL-8 release and mRNA expression.
• IL-1β treatment led to transient phosphorylation of NF-κB p65 and p105.
• Silencing of NF-κB p65, but not p105, abrogated IL-1β-induced IL-8 mRNA expression.

Conclusions:

• IL-1β induces IL-8 expression in canine cardiac fibroblasts.
• The mechanism involves the activation of the NF-κB p65 pathway.
• This finding highlights a key inflammatory pathway in canine cardiac fibroblasts relevant to heart disease.