Nucleic acid detection is a necessary part of medical treatment and fieldwork. However, the current detection technologies are far from ideal. A lack of timely and accessible testing for identifying cases and close contacts has allowed severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), the causative virus of the ongoing coronavirus disease‐2019 (COVID‐19) pandemic, to spread uncontrollably. The slow and expensive detection of mutations—predictors for chronic diseases such as cancer—form a barrier to personalized treatment. A recently developed diagnostic assay is ideal and field‐ready—it relies on CRISPR‐Cas13. CRISPR‐Cas13 works similarly to other CRISPR systems: Cas13 is guided by a crRNA to cleave next to a specific RNA target sequence. Additionally, Cas13 boasts a unique collateral cleavage activity; collateral cleavage of a fluorescent reporter detects the presence of the target sequence in sample RNA. This system forms the basis of CRISPR‐Cas13 diagnostic assays. CRISPR‐Cas13 assays have >95% sensitivity and >99% specificity. Detection is rapid (<2 h), inexpensive ($0.05 per test), and portable—a test using lateral flow strips is akin to a pregnancy test. The recent adaptation of micro‐well chips facilitates high‐level multiplexing and is high‐throughput. In this review, we cover the development of CRISPR‐Cas13 assays for medical diagnosis, discuss the advantages of CRISPR‐Cas13‐based diagnosis over the traditional reverse transcription polymerase chain reaction (RT‐PCR), and present examples of detection from real patient samples.
In the era of immune checkpoint blockade cancer therapy, cytokines have become an attractive immune therapeutics to increase response rates. Interleukin 21 (IL21) as a single agent has been evaluated for cancer treatment with good clinical efficacy. However, the clinical application of IL21 is limited by a short half-life and concern about potential immune suppressive effect on dendritic cells. Here, we examined the antitumor function of a half-life extended IL21 alone and in combination with PD-1 blockade using preclinical mouse tumor models. We also determined the immune mechanisms of combination therapy. We found that combination therapy additively inhibited the growth of mouse tumors by increasing the effector function of type 1 lymphocytes. Combination therapy also increased the fraction of type 1 dendritic cells (DC1s) and M1 macrophages in the tumor microenvironment (TME). However, combination therapy also induced immune regulatory mechanisms, including the checkpoint molecules Tim-3, Lag-3, and CD39, as well as myeloid derived suppressor cells (MDSC). This study reveals the mechanisms of IL21/PD-1 cooperation and shed light on rational design of novel combination cancer immunotherapy.
T cell-stimulating cytokines and immune checkpoint inhibitors (ICIs) are an ideal combination for increasing response rates of cancer immunotherapy. However, the results of clinical trials have not been satisfying. It is important to understand the mechanism of synergy between these two therapeutic modalities. Here, through integrated analysis of multiple single-cell RNA sequencing (scRNAseq) datasets of human tumor-infiltrating immune cells, we demonstrate that IL21 is produced by tumor-associated T follicular helper (Tfh) cells and hyperactivated/exhausted CXCL13+CD4+ T cells in the human tumor microenvironment (TME). In the mouse model, the hyperactivated/exhausted CD4+ T cell-derived IL21 enhances the helper function of CD4+ T cells that boost CD8+ T cell-mediated immune responses during PD-1 blockade immunotherapy. In addition, we demonstrated that IL21’s anti-tumor activity did not require T-cell trafficking. Using scRNAseq analysis of the whole tumor-infiltrating immune cells, we demonstrated that IL21 treatment in combination with anti-PD-1 blockade synergistically drives tumor antigen-specific CD8+ T cells to undergo clonal expansion and differentiate towards the hyperactive/exhausted functional state in the TME. In addition, IL21 treatment and anti-PD-1 blockade synergistically promote dendritic cell (DC) activation and maturation to mature DC (mDC) as well as monocyte to macrophage 1 (M1) differentiation in the TME. Furthermore, the combined treatment reprograms the immune cellular network by reshaping cell-cell communication in the TME. Our study establishes unique mechanisms of synergy between IL21 and PD-1-based ICI in the TME through the coordinated promotion of type 1 immune responses.
<p>Supplementary Figure 4. IL21-anti-HSA and PD-1 mAbs synergy at the proliferation is due to upregulation of IL21R by PD-1 mAbs treatment and IL21 directly promotes proliferation on IL21R+ CD8+ T cells.</p>
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