Interleukine-6 (IL-6) synthesis and gp130 expression by human pericardium.

Area of Science:

• Cardiovascular Biology
• Immunology
• Molecular Biology

Background:

• Cytokines of the Interleukin-6 (IL-6) family are implicated in cardiac physiology, including cardiomyocyte hypertrophy.
• The presence and origin of IL-6 and its soluble receptors in the pericardial space are not well understood.

Purpose of the Study:

• To detect Interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), and soluble gp130 (sgp130) in human pericardial fluids.
• To investigate whether the pericardium produces these cytokines and their receptors.
• To explore the regulation of IL-6 production by pericardial tissue.

Main Methods:

• Detection of IL-6, sIL-6R, and sgp130 in pericardial fluid and serum using biochemical assays.
• In vitro culture of human pericardial samples to assess cytokine production.
• Methylprednisolone treatment to evaluate its effect on cytokine synthesis.
• Reverse transcription-polymerase chain reaction (RT-PCR) for IL-6 gene expression.
• In situ hybridization and immunohistochemistry to localize IL-6 and gp130 in pericardial tissue.

Main Results:

• IL-6, sIL-6R, and sgp130 were detected in pericardial fluid of patients with coronary pathologies.
• Pericardial fluid levels did not correlate with serum levels, suggesting local production.
• Cultured pericardial samples produced significant amounts of IL-6, which was inhibited by methylprednisolone.
• IL-6 expression was low in fresh tissue but strongly induced after culture.
• IL-6 and gp130 were localized to mesothelial cells.
• Pericardium also produced sIL-6R and sgp130 in vitro, with upregulated synthesis by methylprednisolone.

Conclusions:

• The pericardium synthesizes IL-6, sIL-6R, and sgp130, contributing to their presence in pericardial fluid.
• IL-6 production by pericardial tissue is inducible and can be regulated, notably by methylprednisolone.
• These findings suggest a potential paracrine role for IL-6 family cytokines in regulating cardiomyocyte function in cardiac health and disease.