Impaired Glucocorticoid Receptor Dimerization Aggravates LPS-Induced Circulatory and Pulmonary Dysfunction

Area of Science:

• Immunology
• Critical Care Medicine
• Molecular Biology

Background:

• Sepsis, a common cause of acute lung injury (ALI), involves systemic inflammation and activation of the hypothalamus-pituitary-adrenal (HPA) axis.
• Glucocorticoids (GCs), released during inflammation, mediate effects via the GC receptor (GR) monomer or dimer.
• Impaired GR dimerization (GRdim/dim) was previously linked to higher mortality and GC resistance in inflammatory models.

Purpose of the Study:

• To investigate the role of impaired GR dimerization in organ function during lipopolysaccharide (LPS)-induced systemic inflammation under intensive care management.
• To identify genes crucial for lung function in this context.

Main Methods:

• GRdim/dim and wildtype mice were challenged with LPS and received intensive care (mechanical ventilation, fluids, norepinephrine).
• Lung mechanics, gas exchange, hemodynamics, and mitochondrial oxygen consumption were assessed.
• Western blots, immunohistochemistry, and qPCR analyzed lung tissue and inflammatory mediators.

Main Results:

• GRdim/dim mice exhibited higher mortality and increased norepinephrine requirements under intensive care after LPS challenge.
• These mice showed aggravated ALI, with impaired gas exchange, lung mechanics, and elevated osteopontin (Opn) expression.
• Systemic hypotension and impaired lung function were more pronounced in GRdim/dim mice.

Conclusions:

• Impaired GR dimerization exacerbates systemic hypotension and lung dysfunction in LPS-induced endotoxic shock.
• The GR dimer plays a critical role in mediating hemodynamic stability and lung function, potentially via Opn regulation.