Interleukin-17A derived from mast cells contributes to fibrosis in gastric cancer with peritoneal dissemination.

OBJECTIVES: Interleukin-17A (IL-17A) is pro-inflammatory cytokine and acts as profibrotic factor in the fibrosis of various organs. Fibrosis tumor-like peritoneal dissemination of gastric cancer interferes with drug delivery and immune cell infiltration because of its high internal pressure. In this study, we examined the relationship between IL-17A and tissue fibrosis in peritoneal dissemination and elucidated the mechanism of fibrosis induced by IL-17A using human peritoneal mesothelial cells (HPMCs) and a mouse xenograft model. METHODS: Seventy gastric cancer patients with peritoneal dissemination were evaluated. The correlation between IL-17A and fibrosis was examined by immunofluorescence and immunohistochemistry. A fibrosis tumor model was developed based on subcutaneous transplantation of co-cultured cells (HPMCs and human gastric cancer cell line MKN-45) into the dorsal side of nude mice. Mice were subsequently treated with or without IL-17A. We also examined the effect of IL-17A on HPMCs in vitro. RESULTS: There was a significant correlation between IL-17A expression, the number of mast cell tryptase (MCT)-positive cells, and the degree of fibrosis (r = 0.417, P < 0.01). In the mouse model, IL-17A enhanced tumor progression and fibrosis. HPMCs treated with IL-17A revealed changes to a spindle-like morphology, decreased E-cadherin expression, and increased α-SMA expression through STAT3 phosphorylation. Moreover, HPMCs treated with IL-17A showed increased migration. CONCLUSIONS: IL-17A derived from mast cells contributes to tumor fibrosis in peritoneal dissemination of gastric cancer. Inhibiting degranulation of mast cells might be a promising treatment strategy to control organ fibrosis.

Established fibrous peritoneal metastasis in an immunocompetent mouse model similar to clinical immune microenvironment of gastric cancer.

BACKGROUND: Peritoneal metastasis (PM) in gastric cancer (GC) is characterized by diffusely infiltrating and proliferating cancer cells accompanied by extensive stromal fibrosis in the peritoneal space. The prognosis of GC with PM is still poor regardless of the various current treatments. In order to elucidate the cause of difficulties in PM treatment, we compared the tumor immune microenvironment (TME) in primary and PM lesions in GC. In addition, a PM model with fibrous stroma was constructed using immunocompetent mice to determine whether its TME was similar to that in patients. METHODS: Immuno-histochemical analyses of infiltrating immune cells were performed in paired primary and PM lesions from 28 patients with GC. A C57BL/6 J mouse model with PM was established using the mouse GC cell line YTN16 either with or without co-inoculation of mouse myofibroblast cell line LmcMF with α-SMA expression. The resected PM from each mouse model was analyzed the immunocompetent cells using immunohistochemistry. RESULTS: The number of CD8+ cells was significantly lower in PM lesions than in primary lesions (P < 0.01). Conversely, the number of CD163+ cells (M2 macrophages) was significantly higher in PM lesions than in primary lesions (P = 0.016). Azan staining revealed that YTN16 and LmcMF co-inoculated tumors were more fibrous than tumor with YTN16 alone (P < 0.05). Co-inoculated fibrous tumor also showed an invasive growth pattern and higher progression than tumor with YTN16 alone (P = 0.045). Additionally, YTN16 and LmcMF co-inoculated tumors showed lower infiltration of CD8+ cells and higher infiltration of M2 macrophages than tumors with YTN16 alone (P < 0.05, P < 0.05). These results indicate that LmcMF plays as cancer-associated fibroblasts (CAFs) by crosstalk with YTN16 and CAFs contribute tumor progression, invasion, fibrosis, and immune suppression. CONCLUSIONS: This model is the first immunocompetent mouse model similar to TME of human clinical PM with fibrosis. By using this model, new treatment strategies for PM, such as anti-CAFs therapies, may be developed.

[Successful Treatment of Advanced Esophageal Cancer with DCF Chemotherapy and Pegfilgrastim].

Docetaxel, cisplatin, and 5-FU(DCF)chemotherapy for esophageal cancer has been reported to be highly effective, but often causes serious adverse events, including severe bone marrow suppression. We report the successful treatment of a 67- year-old man with highly advanced esophageal cancer with invasion of the left bronchus and broad lymph node metastases. He received induction chemotherapy with DCF therapy, and prophylactic administration of pegfilgrastim. He safely completed 5 courses of DCF therapy without serious adverse events, such as neutropenia and febrile neutropenia. The size of the primary tumor and lymph node metastases remarkably reduced after the third course of DCF. He underwent thoracoscopic esophagectomy with three-field lymph node dissection and reconstruction with a gastric tube. The pathological findings of the resected specimen showed no viable malignant cells in the primary lesion and the pathological effect after chemotherapy was judged as Grade 3. Viable cancer cells still remained in 10 lymph nodes in the dissected field. DCF therapy with prophylactic administration of pegfilgrastim may be an effective and safe treatment for advanced esophageal cancer.

Surgical Approach to the Upper Side of the Gastrosplenic Ligament During Laparoscopic Total Gastrectomy for Proximal Gastric Cancer: Operative Techniques and Initial Results.

Background: Laparoscopic gastrectomy for gastric cancer has become widespread as minimally invasive surgical treatment, but use of laparoscopic total gastrectomy (LTG) remains limited because of the technical difficulty and complexity of lymphadenectomy at the splenic hilum. Surgical techniques and initial experiences with the surgical approach to the upper side of the gastrosplenic ligament during LTG are introduced. Materials and Methods: Between January 2019 and December 2022, 57 patients with proximal gastric cancer underwent LTG using this approach. Results: Regarding the extent of lymphadenectomy, D1+, D2, spleen-preserving D2 + 10, and D2 + 10 with splenectomy were performed in 31, 18, 4, and 4 patients, respectively. Operative time was 341 (192-724) minutes, and estimated blood loss was 30 (0-515) g. There were no conversions to laparotomy and no postoperative complications of Clavien-Dindo grade ≥III. Conclusions: The present procedure is safe and feasible and provides an excellent operative view at the splenic hilum, making it easier to determine exactly the extent of lymphadenectomy in accordance with cancer progression.