Background: Human pancreatic ductal adenocarcinoma (PDAC) responds poorly to immune checkpoint inhibitor (ICPi). While the mechanism is not completely clear, it has been recognized that tumor microenvironment (TME) plays key roles. We investigated if targeting CD47 with a monoclonal antibody could enhance the response of PDAC to ICPi by altering the TME. Methods: Using immunohistochemistry, we examined tumor-infiltrating CD68 + pan-macrophages (CD68 + M) and CD163 + M2 macrophages (CD163 + M2) and tumor expression of CD47 and PD-L1 proteins in 106 cases of PDAC. The efficacy of CD47 blockade was examined in xenograft models. CD45 + immune cells from syngeneic tumor models were subjected to single-cell RNA-sequencing (scRNA-seq) by using the 10x Genomics pipeline. Results: We found that CD47 expression correlated with the level of CD68 + M but not CD163 + M2. High levels of tumor-infiltrating CD68 + M, CD163 + M2, and CD47 expression were significantly associated with worse survival. CD47 high /CD68 + M high and CD47 high /CD163 + M2 high correlated significantly with shorter survival, whereas CD47 low / CD68 + M low and CD47 low /CD163 + M2 low correlated with longer survival. Intriguingly, CD47 blockade decreased the tumor burden in the Panc02 but not in the MPC-83 syngeneic mouse model. Using scRNA-seq, we showed that anti-CD47 treatment significantly remodeled the intratumoral lymphocyte and macrophage compartments in Panc02 tumor-bearing mice by increasing the pro-inflammatory macrophages that exhibit anti-tumor function, while reducing the anti-inflammatory macrophages. Moreover, CD47 blockade not only increased the number of intratumoral CD8 + T cells, but also remodeled the T cell cluster toward a more activated one. Further, combination therapy targeting both CD47 and PD-L1 resulted in synergistic inhibition of PDAC growth in the MPC-83 but not in Panc02 model. MPC-83 but not Panc02 mice treated with both anti-CD47 and anti-PD-L1 showed increased number of PD-1 + CD8 + T cells and enhanced expression of key immune activating genes. Conclusion: Our data indicate that CD47 targeting induces compartmental remodeling of tumor-infiltrating immune cells of the TME in PDAC. Different PDAC mouse models exhibited differential response to the anti-CD47 and anti-PD-L1 blockade due to the differential effect of this combination treatment on the infiltrating immune cells and key immune activating genes in the TME established by the different PDAC cell lines.

Human pancreatic ductal adenocarcinoma (PDAC) exhibits marginal responses to anti-PD-1/PD-L1 immunotherapy and its mechanism remains poorly understood. We have investigated the effect of anti-PD-L1 and c-Myc inhibition in PDAC. Using 87 patients with PDAC from our hospital database we found a significant correlation between the expression of PD-L1 and c-Myc. Moreover, the expression of both PD-L1 and c-Myc was associated with poor overall survival. In addition, we confirmed this finding with the PDAC patients in the TCGA database. Using several PDAC cell lines we demonstrated a significant correlation between the expression of PD-L1 and c-Myc. We also found that expression of PD-L1 correlated with high-grade histology. JQ1, an inhibitor of c-Myc inhibited PD-L1 expression and tumor growth. Using xenograft models, we demonstrated that the combination of JQ1 and anti-PD-L1 antibody exerted synergistic inhibition of PDAC growth. Our data demonstrated that the expression of PD-L1 and c-Myc may be helpful prognostic biomarkers, and their inhibition may potentially serve as an effective treatment for PDAC.

Objective. It is known that noxious stimuli from inflamed tissue may increase the excitability of spinal dorsal horn neurons (a process known as central sensitization), which can signal back and contribute to peripheral inflammation. However, the underlying mechanisms have yet to be fully defined. A number of recent studies have indicated that spinal NF-B/p65 is involved in central sensitization, as well as pain-related behavior. Thus, the aim of this study was to determine whether NF-B/p65 can facilitate a peripheral inflammatory response in rat adjuvant-induced arthritis (AIA).Methods. Lentiviral vectors encoding short hairpin RNAs that target NF-B/p65 (LV-shNF-B/p65) were constructed for gene silencing. The spines of rats with AIA were injected with LV-shNF-B/p65 on day 3 or day 10 after treatment with Freund's complete adjuvant (CFA). During an observation period of 20 days, pain-related behavior, paw swelling, and joint histopathologic changes were evaluated. Moreover, the expression levels of spinal tumor necrosis factor ␣ (TNF␣), interleukin-1␤ (IL-1␤), and cyclooxygenase 2 (COX-2) were assessed on day 14 after CFA treatment. Conclusion. These findings indicate that spinal NF-B/p65 plays an important role in the initiation and development of both peripheral inflammation and hyperalgesia. Thus, inhibition of spinal NF-B/p65 expression may provide a potential treatment to manage painful inflammatory disorders. Results

Objective V-domain Ig suppressor of T cell activation (VISTA) is a novel immune checkpoint protein that belongs to the B7 family. The aim of this study was to investigate the prognostic significance and therapeutic potential of VISTA in patients with pancreatic cancer. Methods Using immunohistochemistry (IHC), we examined the expression of VISTA and demonstrated the associations between the VISTA and overall survival in 223 PDAC patients from 2 different unrelated retrospective cohorts. The multiplex immunofluorescence was performed to illuminate the relationship between VISTA expression and tumor-infiltrating immune cell subclusters of PDAC. We also verified the findings in The Cancer Genome Atlas (TCGA) dataset. The anti-tumor effect of anti-VISTA therapy was studied by the mouse model with liver metastases of PDAC. Results The VISTA protein was highly expressed in 25.6% of tumor cells (TCs), 38.1% of immune cells, and 26.0% of endothelial cells in 223 PDAC tumor tissues. VISTA expression in TCs was significantly associated with prolonged overall survival. Multiplex immunofluorescence analysis revealed that VISTA level was positively correlated with CD68+ macrophages, CD3+ T cells, and CD19+ B cells in PDAC. However, a higher expression level of VISTA was detected in tumor-infiltrating CD68+ macrophages than in CD3+ T and CD19+ B cells. Furthermore, anti-VISTA antibody treatment significantly reduced the number of metastatic nodules in livers of mouse models of PDAC with liver metastases. Conclusion VISTA expressed in TCs is associated with a favorable prognosis in PDAC. Moreover, immunotherapy with anti-VISTA antibodies may potentially be an effective treatment strategy against PDAC.