Figure 5. XBP1 Promotes DC Malfunction in the OvCa Microenvironment.

(A) WT BMDCs were left untreated or treated with tunicamycin (Tm), oleate, or TCM for 8 hr and then pulsed overnight with 100-μg/ml full-length OVA protein. CFSE-labeled OT-1 T cells were co-cultured with treated BMDCs, and proliferation was assessed by FACS 3 days later. (B) WT or XBP1-deficient (KO) BMDCs were incubated in 25% TCM for 8 hr, and the proliferation assay was repeated as described in (A). (C) CFSE-dilution analysis of OT-1 T cells co-cultured with OVA protein-pulsed tDCs isolated from the peritoneal cavity of XBP1^f/f or XBP1^f/f CD11c-Cre mice bearing ID8-Defb29-VegfA ovarian tumors for 4 weeks. tDCs were treated or untreated with vitamin E (VitE) during the OVA pulse. (D and E) Enhanced endogenous T cell activation at tumor sites in mice devoid of XBP1 in tDCs. Peritoneal wash samples from WT (XBP1^f/f, black bars) or XBP1-deficient (XBP1^f/f CD11c-Cre, gray bars) mice were collected 2–3 weeks after peritoneal implantation of ID8-Defb29-VegfA OvCa cells. Surface expression of CD44 and intracellular levels of tumoricidal IFN-γ were analyzed on CD3⁺CD4⁺ (D) or CD3⁺CD8⁺ (E) tumor-infiltrating T cells (TILs). (F) Proportion of T regulatory cells at tumor locations in mice of the indicated genotypes bearing metastatic ID8-Defb29-VegfA ovarian tumors for 3 weeks. In all cases, data are representative of two independent experiments using three to four mice per group. (G and H) Growth of solid ID8-Defb29-VegfA ovarian tumors in hosts adoptively transferred with splenic and draining lymph node T cells isolated from XBP1 ^f/f or XBP1^f/f CD11c-Cre mice bearing metastatic tumors for 30 days. Error bars represent SEM.