MAC mediates mammary duct epithelial cell injury in plasma cell mastitis and granulomatous mastitis.

Plasma cell mastitis (PCM) and granulomatous mastitis (GM) are common inflammatory nonbacterial mastitis (NBM). However, the pathogenesis of NBM is still unclear. METHODS: In this study, we statistically analyzed the pathological features of PCM and GM using pathological HE staining and tissue transmission electron microscopy. The levels of MAC (C5b-9n), P-selectin, E-selectin, and ICAM-1 were detected through IHC, WB, ELISA, and qPCR. The expression level and location of MAC were observed by tissue immunological electron microscopy. In addition, exosomes were isolated from tissues, identified using transmission electron microscopy, and the densities were detected by Nano-FCM. Finally, the expression intensity of MAC in exosomes was detected by flow cytometry and immunoelectron microscopy. RESULTS: The damage and apoptosis of mammary duct epithelial cells are the common pathological features of PCM and GM. MAC is primarily located in the cell membrane of mammary ductal epithelial cells and is significantly expressed in PCM and GM. The density of exosomes in PCM and GM tissues was elevated, and MAC was highly expressed in exosomes. In addition, the expression of P-selectin, E-selectin, and ICAM-1 in PCM and GM was significantly higher than in the normal group. CONCLUSION: We found severe damage of the mammary duct epithelial cells in PCM and GM tissues, which was verified by relevant pathological methods. Earlier studies demonstrated that MAC is highly expressed in PCM and GM tissues and exosomes seem to play a very important role in the understanding of MAC. Furthermore, MAC is involved in inflammatory infiltration and lesion of mammary duct epithelial cells upregulated by P-selectin, E-selectin, and ICAM-1. These findings provide new insights into PCM and GM molecular mechanisms.

Composition and plasticity of triple-negative breast carcinoma-infiltrating regulatory T cells.

Low Foxp3+ regulatory T-cell (Treg) presence in the tumor-infiltrating lymphocytes (TILs) is considered favorable in breast cancer, and numerous CD25-targeting agents have been applied in the attempt to remove Foxp3+ Treg cells, which typically present CD4+ CD25+/hi surface phenotype. However, CD25 is not Treg-exclusive and can be upregulated by effector T cells. Hence, CD25 depletion may cause the elimination of activated T cells that are responding to tumor-specific antigens. In this study, the composition and function of CD4+ CD25+ cells inside the microenvironment of triple-negative breast carcinoma (TNBC) were investigated. Directly ex vivo, the Foxp3+ Treg cells represented a minor subset in total CD4+ CD25+ TILs. Significant differences were observed in the expression of Treg-associated molecules between CD4+ CD25+ Foxp3+ TILs and CD4+ CD25+ Foxp3- TILs. While both the CD4+ CD25+ Foxp3+ and the CD4+ CD25+ Foxp3- TILs could express CTLA-4 and LAG-3, the expression levels were significantly higher in CD4+ CD25+ Foxp3+ TILs than in CD4+ CD25+ Foxp3- TILs. Upon TCR stimulation, the expression of TGF-beta was significantly higher in CD4+ CD25+ Foxp3+ TILs, while the expression of IL-10 was significantly higher in CD4+ CD25+ Foxp3- TILs. These differences were conserved in the blood counterparts of these cells. Interestingly, the level of CD25+ Foxp3+ cells in circulating CD4+ T cells was positively correlated with the level of CD25+ Foxp3+ cells in CD4+ TILs, but the level of CD25+ Foxp3- cells in circulating CD4+ T cells was not associated with the level of CD25+ Foxp3- cells in CD4+ TILs. Th17-polarizing medium could readily remodel CD4+ CD25+ Foxp3- , but not CD4+ CD25+ Foxp3+ , T cells into RORgammat and IL-17-expressing T cells, demonstrating stronger plasticity of the former subset. Together, these data demonstrated that the CD4+ CD25+ TILs were composed of distinctive Foxp3- and Foxp3+ cells, with the former representing the major subset. The antigen specificity and effector molecule expression of the CD4+ CD25+ Foxp3- thus require further analyses.

IL-9-producing CD8+ T cells represent a distinctive subset with different transcriptional characteristics from conventional CD8+ T cells, and partially infiltrate breast tumors.

Accumulating evidence suggests that IL-9 and IL-9-producing cells exert various roles in antitumor immunity. Our study examined the IL-9 production in CD8+ T cells from breast cancer patients as compared to healthy controls. IL-9 secretion was undetectable in CD8+ T cells ex vivo, but could be readily detected following anti-TCR or PMA + ionomycin stimulation, and was higher in breast cancer patients than in healthy controls. The capacity to express IL-9 was not universal to all CD8+ T cells, but was favored in IL-9Rhigh CD8+ T cells, which were also present in breast cancer patients at significantly higher frequency than in healthy controls. Interestingly, exogenous IL-9 could significantly increase the expression of both IL-9 and IL-9R in IL-9Rhigh, but not IL-9Rlow, CD8+ T cells. IL-9Rhigh CD8+ T cells ex vivo presented lower expression of KLRG-1, PD-1, and Tim-3 than IL-9Rlow CD8+ T cells. Additionally, IL-9Rhigh CD8+ T cells following anti-TCR and PMA + ionomycin stimulation presented higher IL-2 and IL-17 expression, and lower IFN-γ expression, than IL-9Rlow CD8+ T cells. IL-9-expressing CD8+ T cells could be found in some, but not all, resected breast tumors. IL-9R expression, on the other hand, was readily present in CD8+ T cells, but with high variability from patient to patient. Patients with high intratumoral IL-9 expression also tended to present high IL-9R expression. Together, these data demonstrate that a transcriptionally distinctive IL-9-producing CD8+ T cell subset was elevated in breast cancer patients and could be found inside the tumor, with higher capacity to produce IL-2 and IL-17 and lower expression of inhibitory receptors.

Th9 cells promote antitumor immunity via IL-9 and IL-21 and demonstrate atypical cytokine expression in breast cancer.

Breast cancer is a major cause of cancer-related death in women. Antitumor T cell responses play critical therapeutic roles, including direct cytotoxicity mediated by CD8+ T cells and immunomodulatory roles mediated by CD4+ T cells. The IL-9-expressing Th9 cells are recently found to present antitumor immunity in melanoma and lung adenocarcinoma. In this study, we found that IL-9 expression in the serum and in circulating CD4+ T cells were significantly upregulated in breast cancer patients compared to healthy controls. The IL-9-expressing Th9 cells were enriched in the CCR4-CCR6-CXCR3- subset. Upon TCR stimulation, this subset also presented potent IL-10 and IL-21 expression in addition to IL-9 expression. CCR4-CCR6-CXCR3- CD4+ T cells also assisted in the killing of autologous tumor cells by CD8+ T cells, but did not initiate cytotoxicity by themselves. This enhancement in CD8+ T cell-mediated cytotoxicity was dependent on IL-9 as well as on IL-21. Interestingly, the tumor-infiltrating Th9 cells presented comparable IL-9, reduced IL-10, and elevated IL-21 expression compared with their counterparts in the peripheral blood. Together, these results demonstrated that IL-9-expressing Th9 cells were upregulated in breast cancer patients and potentially possessed antitumor roles by enhancing CD8+ T cell-mediated cytotoxicity.

MicroRNA-26a inhibits proliferation by targeting high mobility group AT-hook 1 in breast cancer.

OBJECTIVES: To investigate the crucial role of miR-26a in breast cancer and to validate whether miR-26a could regulate proliferation of breast cancer cells by targeting high mobility group AT-hook 1 (HMGA1). METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to quantify the expression levels of miR-26a in breast cancer and adjacent non-cancerous breast tissues. MTT, cell migration and invasion assay were carried out to characterize the miR-26a function. Finally, to validate the target gene of miR-26a, luciferase reporter assay was employed, followed by RT-PCR and Western blot confirmation. RESULTS: Compared with normal tissues, a significant down-regulation of miR-26a expression was observed in breast cancer tissues (P=0.002). miR-26a suppresses MDA-MB-231 and Mcf-7 breast cancer cell lines proliferation and motility. The luciferase activity was significantly decreased after co-transfection with psiCHECK-2/HMGA1 3'-UTR and miR-26a mimics in comparison with control cells, and qRT-PCR and Western blotting analysis found that HMGA1 expression at the mRNA and protein levels decreased in the miR-26a mimic-treatment group relative to NC. MTT assay showed that down regulation of HMGA1 by siRNA could significantly enhance the tumor-suppressive effect of miR-26a (P < 0.05). CONCLUSIONS: The results of the present study indicate that miR-26a may be associated with human breast carcinogenesis, which inhibits tumor cell proliferation by targeting HMGA1.