Fig 2: IL-20 activates the IL20RA-STAT3-OAS1/RNase L-NLR signaling to produce IL-18 to regulate the macrophages polarization.(A) qRT-PCR analysis of Oas1a and Il18 upon IL20RA reconstitution in ID8 cells. (B) The secreted IL-18 from IL20RA-reconstituted and control ID8 cells was measured by ELISA. (C) Western blot analysis of indicated proteins in IL20RA-reconstituted and control ID8 cells under the stimulation of IL-20. (D) Western blot analysis of indicated proteins in SK-OV-3 cells stimulated with IL-20 or phosphate-buffered saline (PBS) (Ctrl) for 24 hr. (E) ELISA measurement of IL-18 secreted from SK-OV-3 cells stimulated by IL-20 for 24 hr. (F) Schematic of the Oas1a promoter and Il18 promoter with predicted STAT3-binding sites and the primer sets. (G) IL20RA-reconstituted ID8 cells were stimulated with IL-20 or PBS (Ctrl) for 24 hr before the STAT3 binding on Oas1a promoter and Il18 promoter was analyzed by ChIP-qPCR. (H, I) Immunohistochemical analysis of IL20RA, p-STAT3, OAS1, and IL-18 in human primary ovarian cancer tissues (Pri) and paired peritoneal metastatic nodules (Met) (H) and quantification (I). **p<0.01; ***p<0.001, by paired two-sided Student’s t-test. Scale bar: 20 µm. (J) qRT-PCR analysis of macrophage marker genes in RAW 264.7 cells stimulated with IL-20 protein for 72 hr. (K) qRT-PCR analysis of macrophage marker genes in RAW 264.7 cells treated by CMIL20RA IL-20 (+) or CMVec IL-20 (+) together with IL-18 neutralizing antibody (nAb) or nonspecific lgG (IgG) for 72 hr. All the qRT-PCR and ELISA data are shown as means ± SEM from three independent experiments, *p<0.05, **p<0.01, ***p<0.001, by unpaired two-sided Student’s t-test. Figure 7—source data 1.An Excel sheet with numerical quantification data.

Fig 3: Roflumilast reduced IL-18 induced expression and secretion of pro-inflammatory chemokines CCL5, CXCL9, and CXCL10 in MH7A FLS. Cells were stimulated with IL-18 (10 ng/mL) in the presence or absence of 5 and 10 µM roflumilast. (A–C) mRNA of CCL5, CXCL9, and CXCL10; (D–F) secretions of CCL5, CXCL9, and CXCL10 (####P < 0.0001 vs vehicle group; **P < 0.01, ***P < 0.001 vs IL-18 group).

Fig 4: Roflumilast reduced IL-18-induced activation of AP-1 in MH7A FLS. Cells were stimulated with IL-18 (10 ng/mL) in the presence or absence of 5 and 10 μM roflumilast. (A) Protein expression of c-Jun and c-Fos and (B) luciferase activity of AP-1 (####P < 0.0001 vs vehicle group; **P < 0.01, ***P < 0.001 vs IL-18 group).

Fig 5: The therapeutic effect of recombinant IL-18 against the metastasis of ovarian cancer (OC).(A) Schematic of the experiments. ID8 cells were orthotopic injected into the ovaries of C57BL/6 mice. The phosphate-buffered saline or IL-18 protein were intraperitoneal (i.p.) injected every 2 days. (B–E) Representative images of the metastatic nodules in peritoneal cavity (B) and ascites formation (D) at day 60 post-inoculation. The quantification of metastatic nodules and ascites is shown in (C) and (E), respectively. Data are shown as means ± SEM (n = 7). ***p<0.001, by unpaired two-sided Student’s t-test. (F) Flow cytometry analysis of macrophages (CD45+ CD11b+ F4/80+) and M1-like (MHC II+ CD206-) and M2-like (MHC II- CD206+) subpopulations in ascites formed in C57BL/6 mice at 60 days after orthotopically inoculated with ID8 cells (means ± SEM, n = 5, *p<0.05, ***p<0.001, ns, not significant, by unpaired two-sided Student’s t-test). (G) Schematics summarizing the IL-20/IL20RA-OAS1/RNase L-NLR-IL-18 axis in preventing the transcoelomic metastasis of OC. Figure 9—source data 1.An Excel sheet with numerical quantification data.