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Rationale: TCR-T cell therapy plays a critical role in the treatment of malignant cancers. However, it is unclear how TCR-T cells are affected by PD-L1 molecule in the tumor environment. We performed an in-depth evaluation on how differential expressions of tumor PD-L1 can affect the functionality of T cells. Methods: We used MART-1-specific TCR-T cells (TCR-TMART-1), stimulated with MART-127-35 peptide-loaded MEL-526 tumor cells, expressing different proportions of PD-L1, to perform cellular assays and high-throughput single-cell RNA sequencing. Results: Different clusters of activated or cytotoxic TCR-TMART-1 responded divergently when stimulated with tumor cells expressing different percentages of PD-L1 expression. Compared to control T cells, TCR-TMART-1 were more sensitive to exhaustion, and secreted not only pro-inflammatory cytokines but also anti-inflammatory cytokines with increasing proportions of PD-L1+ tumor cells. The gene profiles of chemokines were modified by increased expression of tumor PD-L1, which concurrently downregulated pro-inflammatory and anti-inflammatory transcription factors. Furthermore, increased expression of tumor PD-L1 showed distinct effects on different inhibitory checkpoint molecules (ICMs). In addition, there was a limited correlation between the enrichment of cell death signaling in tumor cells and T cells and increased tumor PD-L1 expression. Conclusion: Overall, though the effector functionality of TCR-T cells was suppressed by increased expression percentages of tumor PD-L1 in vitro, scRNA-seq profiles revealed that both the anti-inflammatory and pro-inflammatory responses were triggered by a higher expression of tumor PD-L1. This suggests that the sole blockade of tumor PD-L1 might inhibit not only the anti-inflammatory response but also the pro-inflammatory response in the complicated tumor microenvironment. Thus, the outcome of PD-L1 intervention may depend on the final balance among the highly dynamic and heterogeneous immune regulatory circuits.

The switchable chimeric antigen receptors (CARs) have shown many advantages in CAR T-cell therapy. However, human primary T-cells are required to evaluate antigen-specific adaptors by IFN-γ assay or FACS analysis, which limits the throughput of adaptor screening. A sensitive and robust CD16-CAR Jurkat NFAT-eGFP reporter system has been developed to assess the therapeutic efficacy of antibody-targeted CAR-T-cell by effectively evaluating the T-cell activation by various tumor cells and the impact of immune checkpoint inhibitor antibodies. This reporter system facilitates the screening of targeted antibodies in a high throughput manner for the development of improved T-cell immunotherapy.

PD-L1 expression levels in tumors do not consistently predict cancer patients’ response to PD-(L)1 inhibitors. We therefore evaluated how tumor PD-L1 levels affect the anti-PD-(L)1 efficacy and T cell function. We used MART-1-specific TCR-T cells (TCR-TMART-1) stimulated with MART-127-35peptide-loaded MEL-526 tumor cells with different proportions of them expressing PD-L1 to perform cellular assays and high-throughput single-cell RNA sequencing. Compared to control T cells, TCR-TMART-1were more sensitive to exhaustion and secreted lower pro-inflammatory but higher anti-inflammatory cytokines with increasing proportions of PD-L1+tumor cells. The colocalization of T cells and tumor cells in gene clusters correlated negatively with the proportion of PD-L1+tumor cells and positively with immune cell cytotoxicity. Moreover, elevated proportion of PD-L1+tumor cells increased PD-L1 expression and decreased PD-1 expression on T cells and enhanced T cell death. The expression of PD-1 and PD-L1 in T cells and macrophages also correlated positively with COVID-19 severity.

Improper storage of wolfberry fruit is liable to soften, discoloration and adhesion, we call it “oil-spilling”. The purpose of the study is to explore the mechanism of “oil-spilling” of wolfberry fruits during storage. In our study, the relationship between water content, superoxide dismutase (SOD), peroxidase (POD) activity, malondialdehyde (MDA) content and the cross section, epidermal cells of wolfberry fruit were studied during storage. Results showed that wolfberry fruits began to “oil-spilling” on the 20th day, and with the extension of storage time, the degree of “oil-spilling” gradually deepened, the content of water increased and the activity of POD decreased, and the content of MDA increased. It suggested that “oil-spilling” was the result of improper external storage conditions, which it could promote the increase of water content and reactive oxygen free radical of wolfberry fruit, and lead to damage of cell structure and function and lipid peroxidation of cell membrane. The results explain the mechanism of “oil-spilling” and provide a strong basis for the establishment of scientific storage methods of wolfberry fruit.