MMP2 and TLRs modulate immune responses in the tumor microenvironment
Luciana R. Muniz-Bongers, Christopher B. McClain, Mansi Saxena, Gerold Bongers, Miriam Merad, Nina Bhardwaj
Luciana R. Muniz-Bongers, Christopher B. McClain, Mansi Saxena, Gerold Bongers, Miriam Merad, Nina Bhardwaj
View: Text | PDF
Research Article Immunology Oncology

MMP2 and TLRs modulate immune responses in the tumor microenvironment

Abstract

The presence of an immunosuppressive tumor microenvironment is a major obstacle in the success of cancer immunotherapies. Because extracellular matrix components can shape the microenvironment, we investigated the role of matrix metalloproteinase 2 (MMP2) in melanoma tumorigenesis. We found that MMP2 signals proinflammatory pathways on antigen presenting cells, and this requires both TLR2 and TLR4. B16 melanoma cells that express MMP2 at baseline have slower kinetics in Tlr2–/– Tlr4–/– mice, implicating MMP2 in promoting tumor growth. Indeed, Mmp2 overexpression in B16 cells potentiated rapid tumor growth, which was accompanied by reduced intratumoral cytolytic cells and increased M2 macrophages. In contrast, knockdown of Mmp2 slowed tumor growth and enhanced T cell proliferation and NK cell recruitment. Finally, we found that these effects of MMP2 are mediated through dysfunctional DC–T cell cross-talk as they are lost in Batf3–/– and Rag2–/– mice. These findings provide insights into the detrimental role of endogenous alarmins like MMP2 in modulating immune responses in the tumor microenvironment.

Authors

Luciana R. Muniz-Bongers, Christopher B. McClain, Mansi Saxena, Gerold Bongers, Miriam Merad, Nina Bhardwaj

×

Figure 5

Mmp2 depletion in B16 cells impairs melanoma tumor growth.

Options: View larger image (or click on image) Download as PowerPoint
Mmp2 depletion in B16 cells impairs melanoma tumor growth. The levels o...
The levels of Mmp2 in the B16 was modulated by CRISPR KO systems. In total, 3 × 105 B16 F1 or F1 Mmp2-KO cells and tumors were measured up to 20 days. (A and B) Tumor volume (A) and weight (B) are displayed. Data are representative of 5 independent experiments with mean ± SEM. n = 8–10 mice per group. *P < 0.05, **P < 0.01, and ***P < 0.001. Multiple t tests with Holm-Sidak correction for multiple comparisons. (C) FACS analysis on day 19 shows changes in hematopoietic cell infiltration. Data are representative of 3 independent experiments with mean ± SEM. n = 4 mice per group. *P < 0.05 and **P < 0.01. Multiple t tests with Holm-Sidak correction for multiple comparisons. (D–I) Immunofluorescence (IF) stainings. (D) IF staining for MMP2 (green) and DAPI (blue). F1 control tumors on the top panel and F1 Mmp2-KO controls on the bottom panel. Scale bars: 200 μm on left panels and 100 μm on right panels. (E) IF colocalization (white) of CD3+ T cells (green) with Ki67 (red) in Mmp2-KO tumors. Colocalization is shown is white arrowheads. Scale bars: 100 μm. (F) IF staining of CD8 (red) and DAPI (blue). Scale bars: 100 μm. (G) Quantification of the CD8 staining. Data representative of 2 experiments. n = 6. mean ± SEM. ***P < 0.001. Student’s t test. (H) IF staining of NK1.1 (red), granzyme B (green), and DAPI (blue) infiltrates in the tumor bed. F1 tumors on top panels and F1 Mmp2-KO tumors on the bottom panels. Scale bars: 200 μm on left panels and 100 μm on right panels. Colocalization is shown in orange. (I) Quantification of NK1.1 and granzyme-B staining. Data are representative of 2 experiments. n = 6. mean± SEM. ***P < 0.001. Student’s t test.