Carbon black (CB) deposition, or anthracosis, is frequently observed in the regional lymph nodes (RLNs) of patients with thoracic malignancies, particularly those with a history of smoking; however, its clinical significance in immune checkpoint inhibitor (ICI)-based therapy remains unclear. This retrospective study aimed to investigate the association between CB deposition in RLNs and response to ICI-based therapy in recurrent esophageal squamous cell carcinoma (ESCC). The study included 47 patients with recurrent ESCC who underwent curative-intent esophagectomy and subsequently received ICI-based therapy. The proportion of CB-containing RLNs (%CB) was histologically evaluated, and patients were divided into high- and low-CB groups according to the median %CB value. CB was mainly detected in lymph node sinus macrophages. Patients in the high-CB group showed a significantly higher disease control rate than those in the low-CB group. Progression-free survival tended to be longer in the high-CB group, although the difference did not reach statistical significance. CB-containing sinus macrophages expressed CD68 and CD163, whereas CD169 expression was markedly reduced or absent. No significant association was observed between %CB and tumor-infiltrating immune cell densities or HLA class I/PD-L1 expression. By contrast, ectopic HLA-DR expression in cancer cells was more frequent in the high-CB group. These findings suggest that a higher proportion of CB-containing RLNs is associated with disease control following ICI-based therapy in recurrent ESCC. Histological assessment of CB deposition in RLNs may provide useful information regarding clinical benefit from ICI-based immunotherapy.

Tumor-associated macrophages (TAMs) play important roles in shaping the tumor microenvironment and regulating antitumor immune responses. Triggering receptor expressed on myeloid cells 2 (TREM2) and stabilin-1 (STAB1/CLEVER1) have recently attracted attention as molecules associated with immunosuppressive macrophage phenotypes; however, their expression patterns in clear-cell renal cell carcinoma (ccRCC) remain unclear. This study aimed to examine TREM2 and STAB1 expression in ccRCC using public transcriptomic datasets and public single-cell RNA sequencing data, as well as immunohistochemistry using ccRCC specimens. In the TCGA cohort, high TREM2 and STAB1 mRNA expression was associated with poor overall survival and advanced tumor stage. In an independent immunohistochemistry cohort, TREM2 was expressed mainly in TAMs, whereas STAB1 was expressed in both TAMs and endothelial cells. TREM2-positive TAM density was significantly associated with high nuclear grade, whereas STAB1-positive TAM density was not. Double immunohistochemistry and single-cell RNA sequencing analyses suggested different, but partially overlapping, expression patterns of TREM2 and STAB1 among TAMs. TREM2-high TAMs showed features of monocyte-derived macrophages, whereas STAB1-high TAMs showed features associated with tissue-resident macrophages. These findings suggest that TREM2-positive TAMs and STAB1-positive TAMs contribute differently to the immune microenvironment of ccRCC. Further studies are needed to clarify their functional significance and therapeutic potential.

Whole embryo culture is a unique system for developing rodent embryos outside the uterus. This system enables the observation and manipulation of mammalian embryos during specific periods of embryonic development. Established techniques utilize a rotating bottle system that continuously supplies oxygen. However, commercial devices are currently unavailable, making the new implementation of this system virtually impossible. Furthermore, the conventional device had limitations in temperature settings, making embryonic development studies impossible under conditions deviating from the optimal temperature for mammalian embryos. In this study, we developed a simple rotating culture system that can be installed in a commercially available incubator. Embryo growth and physiological status in this devise are equivalent to those in embryos cultured in the conventional system. Using this system, we clarified the harmful effects of hyperthermia during the early stages of mouse embryonic development. This device is fully suitable for whole embryo culture in mammals and provides a foundation for verifying embryonic development states in rodents under various temperature conditions.