Protective Effects of Qingjie Fuzheng Granules on Intestinal Mucosal Injury Induced by Docetaxel/Cyclophosphamide Chemotherapy in Breast Cancer Through the TLR4/NF-κB Pathway

<bold>Objective</bold>To investigate the protective mechanisms of Qingjie Fuzheng Granules (QFG) against intestinal mucosal injury induced by docetaxel and cyclophosphamide combination chemotherapy in breast cancer.<bold>Methods</bold>A total of 32 female BALB/c mice were selected and inoculated with 4T1 breast cancer cells to establish subcutaneous tumor models, with tumor volumes ranging from 50 to 100 mm³. The mice were randomly divided into control group, Qingjie Fuzheng Granules group (QFG group), chemotherapy group (TC group), and chemotherapy+Qingjie Fuzheng granules group (TC+QFG group) by Excel software, with eight mice in each group. The control group received sterile normal saline gavage once daily and intraperitoneal injections of sterile saline once weekly. The QFG group was given Qingjie Fuzheng Granules at 1 g/kg by gavage once daily, along with weekly intraperitoneal injections of sterile normal saline. The TC group received weekly intraperitoneal injections of docetaxel (15 mg/kg) and cyclophosphamide (20 mg/kg), along with daily intragastric sterile normal saline. The TC+QFG group received intraperitoneal docetaxel and cyclophosphamide once weekly and 1 g/kg of Qingjie Fuzheng Granules by gavage once daily, with a 0.5-hour interval between gavage and injection. The intervention lasted for four weeks in all groups. After intervention, the mice were assessed for body weight, diarrhea, and tumor volume growth. Hematoxylin and eosin (HE) staining was used to evaluate morphological changes in the ileal mucosa. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum contents of diamine oxidase (DAO), D-lactic acid (D-LA), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, IL-2, IL-4, IL-10, gamma interferon (IFN-γ), and secretory immunoglobulin A (sIgA). The TUNEL staining method was used to detect apoptosis in ileal mucosal cells. Immunohistochemistry was used to assess the expression of IgA⁺ cells and tight junction proteins (ZO-1, Occludin) in the ileal mucosa. Western blot was used to determine the expression levels of TLR4, NF-κB, and p-NF-κB proteins in the ileal mucosa.<bold>Results</bold>(1) Body weight, diarrhea score, and tumor volume: compared with the TC group, body weight in the TC+QFG group increased significantly at day 27 of intervention (<italic>P</italic>&lt;0.05), along with significantly decreased diarrhea scores at 1st and 8th day of intervention (<italic>P</italic>&lt;0.05). No statistically significant differences in body weight and diarrhea scores were observed at other times (<italic>P</italic>&gt;0.05). Compared with the control group, the tumor volume in the TC+QFG group decreased significantly on day 13 of intervention and all subsequent time points (<italic>P</italic>&lt;0.05). (2) Histopathological changes in ileal tissue: compared with the TC group, the TC+QFG group showed significant improvements in intestinal mucosal structure, including reduced epithelial edema, increased villus height, better organized villi arrangement, shallower crypt depth, and decreased inflammatory cell infiltration. After intervention, the villus height and villus/crypt ratio increased significantly (<italic>P</italic>&lt;0.05), while crypt depth significantly decreased in the TC+QFG group (<italic>P</italic>&lt;0.05). (3) Expression levels of ZO-1 and Occludin proteins in ileal mucosal tissue: compared with the TC group, the expression levels of ZO-1 and Occludin proteins in the ileal mucosal tissue of the TC+QFG group increased significantly after intervention (<italic>P</italic>&lt;0.05). (4) Serum levels of DAO and D-LA: compared with the TC group, serum levels of DAO and D-LA in the TC+QFG group decreased significantly after intervention (<italic>P</italic>&lt;0.05). (5) Serum levels of TNF-α, IL-1β, IL-6, IL-2, IL-4, IL-10, and IFN-γ: compared with the TC group, serum levels of IL-1β, TNF-α, IL-6, and IFN-γ in the TC+QFG group decreased significantly after intervention (<italic>P</italic>&lt;0.05), while the levels of IL-2, IL-4, and IL-10 increased significantly (<italic>P</italic>&lt;0.05). (6) Apoptosis in ileal mucosal tissue: compared with the TC group, nuclear yellowing and positive staining rate in the TC+QFG group decreased significantly after intervention (<italic>P</italic>&lt;0.05). (7) Serum sIgA levels and the number of IgA⁺ cells in ileal mucosal tissue: compared with the TC group, the serum sIgA contents and number of IgA⁺ cells in ileal mucosal tissue in the TC+QFG group increased significantly after intervention (<italic>P</italic>&lt;0.05). (8) Expression levels of TLR4/NF-κB pathway-related proteins in the ileal mucosal tissue: compared with the TC group, the expression levels of TLR4 and p-NF-κB proteins in the ileal mucosal tissue of the TC+QFG group decreased significantly after intervention (<italic>P</italic>&lt;0.05).<bold>Conclusion</bold>QFG demonstrates a protective effect against intestinal mucosal damage induced by chemotherapy in breast cancer, potentially through modulation of the TLR4/NF-κB signaling pathway, which may inhibit inflammatory responses, reduce intestinal epithelial cell apoptosis, and enhance both epithelial and immune barrier functions of the intestinal mucosa.