Spatial immune profiling of local tissues and its correlation with peripheral blood cytokines in lung squamous cell carcinoma patients with immune-related pneumonitis.

Background: Checkpoint inhibitor-induced pneumonitis (CIP) is a potentially fatal adverse event in lung squamous cell carcinoma (LUSC) patients, yet reliable early predictive biomarkers remain elusive. This study aimed to characterize the association between pre-treatment spatial immune landscapes and post-therapy peripheral cytokine fluctuations, in order to identify effective predictive biomarkers for CIP. Methods: This retrospective study enrolled 19 LUSC patients treated with immune checkpoint inhibitors (ICIs) between January 2022 and December 2024, of whom 4 developed CIP. Pre-treatment tumor tissues were obtained at baseline, while peripheral blood specimens were collected at the onset of CIP. Multiplex immunofluorescence (mIF) was employed to analyze the spatial distribution of immune cells and factors, including IL-8, CD66b Results: No statistically significant differences were observed in baseline clinical characteristics or routine hematological parameters between the two groups. Cytokine profiling revealed that post-onset peripheral IL-8 and TNF-α levels were significantly lower in the CIP group than in the non-CIP group (P<0.05). mIF analysis demonstrated significantly elevated pre-treatment IL-8 expression accompanied by marked enrichment of CD66b Conclusions: Increased stromal IL-8 expression and CD66b⁺ neutrophil enrichment before treatment may be associated with subsequent CIP development in patients with LUSC receiving ICIs. These findings support a potential role of localized immune microenvironment alterations in CIP and may provide clues for future risk assessment strategies.