Macrophages of distinct origins contribute to tumor development in the lung

Area of Science:

• Immunology
• Oncology
• Macrophage Biology

Background:

• Tissue-resident macrophages possess self-maintenance capabilities independent of adult hematopoiesis.
• Tumor-associated macrophages (TAMs) play critical roles in tumor progression and response to therapy.
• Understanding TAM origins is crucial for developing effective cancer treatments.

Purpose of the Study:

• To investigate the contribution of tissue-resident interstitial macrophages (Res-TAMs) to the TAM pool in lung tumors.
• To differentiate the roles of Res-TAMs and CCR2-dependent recruited macrophages (MoD-TAMs) in tumor growth, spreading, and response to therapy.
• To evaluate the impact of combined anti-VEGF and chemotherapy on TAM subsets and therapeutic efficacy.

Main Methods:

• Analysis of macrophage populations in mouse lung tumor models.
• Characterization of tissue-resident interstitial macrophages (Res-TAMs) and CCR2-dependent recruited macrophages (MoD-TAMs).
• Assessment of TAM response to chemotherapy and anti-VEGF treatment, alone and in combination.

Main Results:

• Res-TAMs correlated with tumor growth, while MoD-TAMs were associated with enhanced tumor spreading.
• Both TAM subsets were depleted by chemotherapy, but MoD-TAMs rapidly recovered and mediated tumor clearance.
• Combined anti-VEGF and chemotherapy inhibited TAM reconstitution without affecting monocyte infiltration, improving treatment efficacy.

Conclusions:

• The developmental origin of TAMs dictates their distribution, function, and therapeutic response in lung tumors.
• Targeting TAM reconstitution may represent a viable strategy to enhance cancer therapy efficacy.
• Distinct TAM subsets exhibit differential roles and responses, highlighting the complexity of the tumor microenvironment.