MIF-CD74 Signaling Defines a Brain-Specific Immune Vulnerability in Metastasis and Neurologic Disease

Area of Science:

• Immunology
• Neuroscience
• Oncology

Background:

• Brain metastases pose significant challenges in cancer treatment, with poor patient outcomes.
• The brain's unique microenvironment often hinders the efficacy of systemic cancer therapies.
• Brain-specific programs are implicated in the progression of metastatic disease within the central nervous system.

Purpose of the Study:

• To investigate the role of the immune molecule CD74 in brain metastasis.
• To identify novel therapeutic targets for intracranial tumors.
• To explore shared microenvironmental mechanisms in diverse brain disorders.

Main Methods:

• Characterization of CD74 expression in macrophages during metastatic colonization.
• Analysis of the interaction between macrophage migration inhibitory factor (MIF) and CD74.
• Assessment of downstream signaling pathways, including NF-κB and mitochondrial plasticity.
• Evaluation of the therapeutic efficacy of a MIF-CD74 inhibitor (ibudilast) in preclinical models and patient-derived cultures.

Main Results:

• A specific CD74-positive macrophage population emerges during brain metastatic colonization.
• MIF-CD74 signaling activates NF-κB and promotes a prometastatic state via oxidative phosphorylation and mitochondrial changes.
• Ibudilast effectively suppresses brain metastatic tumor growth in mouse models.
• The therapeutic strategy demonstrated efficacy in patient-derived organotypic cultures from various cancer origins.

Conclusions:

• CD74 is a critical component of a brain-induced myeloid program that promotes cancer metastasis.
• The MIF-CD74 signaling pathway is a viable therapeutic target for brain metastases.
• CD74+ macrophages mediate shared programs in both cancer and other neurologic pathologies, suggesting broader therapeutic potential.