Spatial organization of neutrophil and macrophage populations in surgically treated hepatocellular carcinoma: a practical tissue-based immunophenotyping study.

BACKGROUND AND AIMS: Hepatocellular carcinoma (HCC) has a spatially heterogeneous immune microenvironment, but the compartment-specific distribution of tumor-associated neutrophils (TANs) and its relationship with systemic inflammation remain incompletely defined. This study characterized CD177-defined neutrophil populations and other immune components across HCC tissue compartments and examined their associations with peripheral neutrophil-to-lymphocyte ratio (NLR).

METHODS

Paired tumor center (TC), tumor margin/interface (IM), and adjacent non-neoplastic liver (NNL) specimens from 28 patients with HCC were analyzed using immunofluorescence microscopy and quantitative immunohistochemistry. Total neutrophil elastase-positive (NE+) and CD177+NE+ neutrophils, CD8+ lymphocytes, CD68+ and CD163+ macrophages, and CD34+ microvascular density were quantified.

RESULTS

Total NE+ neutrophil density differed across compartments and was higher in both tumor-associated compartments than in NNL (median: TC, 46.40 cells/mm²; IM, 39.65 cells/mm²; NNL, 8.80 cells/mm²; P < 0.001). CD177+NE+ density showed a modest compartmental effect and was higher in the TC than at the IM (RR 2.68, 95% CI 1.20-6.02; Holm-adjusted P = 0.050). In contrast, the CD177+ fraction among total NE+ neutrophils was markedly lower in both tumor-associated compartments than in NNL (median: TC, 17.63%; IM, 10.90%; NNL, 88.08%; P < 0.001)among, accompanied by substantial enrichment of estimated NE+CD177- neutrophils. CD8+ lymphocytes preferentially accumulated at the IM, whereas CD34+ microvascular density followed a TC>IM>NNL gradient. CD68+ macrophages were more abundant in NNL, while CD163+ macrophage density showed a modest overall compartment effect (mixed-effects P = 0.037), and the CD163/CD68 macrophage-polarization index was higher in the TC than at the IM (P = 0.009). In exploratory analyses, higher preoperative NLR was associated with the CD163/CD68 macrophage-polarization index specifically in the TC (ρ = 0.451, P = 0.016; q = 0.048), but not with neutrophil abundance, CD177-defined distribution, or patient-level neutrophil spatial-distribution indices.

CONCLUSIONS

HCC exhibits marked spatial myeloid heterogeneity, characterized by neutrophil enrichment in tumor-associated compartments, compartmental differences in CD177-defined populations, and compartment-specific macrophage polarization. These findings, generated using a practical tissue-based immunophenotyping approach applicable to routinely processed specimens, warrant validation in larger mechanistic studies.