CD163 Dominance Within Macrophages/Microglia Reflects a Favorable Prognosis in Patients With Glioblastoma

Glioblastoma is the most common primary malignant central nervous system (CNS) tumor; however, its microenvironment, including tumor-associated microglia/macrophages (TAMs), is not fully understood. Although ionized calcium-binding adaptor molecule 1 (IBA-1) is expressed in various microglial phenotypes in the healthy human brain, CD163 is a marker of activated/phagocytic microglia. Tissues from 34 patients with glioblastoma were analyzed, and 17.6% of cases were CD163-dominant. CD163-dominant patients showed better overall survival than IBA-1-dominant patients (p = 0.019). CD163 dominance was identified as an independent prognostic factor for overall survival (hazard ratio [HR], 0.17; p = 0.011). Compared with the IBA-1-dominant group, CD163-dominant tumors showed more CD4-positive cell infiltration (p = 0.005), fewer ameboid TAMs (p = 0.021), and fewer non-microvascular proliferation (non-MVP) vessels (p = 0.012). No significant differences were found in patient characteristics, such as age, sex, tumor location, or extent of resection. The CD163-to-IBA-1 ratio of TAMs is a significant independent prognostic factor in glioblastoma, suggesting that the activation status of these cells and their interactions with the vascular endothelium and T cells influence tumor progression. These findings highlight TAMs as potential therapeutic targets for glioblastoma.