An Efficient and High Yield Method for Isolation of Mouse Dendritic Cell Subsets

HyPR-seq: Single-cell quantification of chosen RNAs via hybridization and sequencing of DNA probes

Single-cell quantification of RNAs is important for understanding cellular heterogeneity and gene regulation, yet current approaches suffer from low sensitivity for individual transcripts, limiting their utility for many applications. Here we present Hybridization of Probes to RNA for sequencing (HyPR-seq), a method to sensitively quantify the expression of hundreds of chosen genes in single cells. HyPR-seq involves hybridizing DNA probes to RNA, distributing cells into nanoliter droplets, amplifying the probes with PCR, and sequencing the amplicons to quantify the expression of chosen genes. HyPR-seq achieves high sensitivity for individual transcripts, detects nonpolyadenylated and low-abundance transcripts, and can profile more than 100,000 single cells. We demonstrate how HyPR-seq can profile the effects of CRISPR perturbations in pooled screens, detect time-resolved changes in gene expression via measurements of gene introns, and detect rare transcripts and quantify cell-type frequencies in tissue using low-abundance marker genes. By directing sequencing power to genes of interest and sensitively quantifying individual transcripts, HyPR-seq reduces costs by up to 100-fold compared to whole-transcriptome single-cell RNA-sequencing, making HyPR-seq a powerful method for targeted RNA profiling in single cells.

Efficacy of co-immunization with the DNA and peptide vaccines containing SYCP1 and ACRBP epitopes in a murine triple-negative breast cancer model

Multiepitope cancer vaccines have gained lots of attention for prophylactic and therapeutic purposes in cancer patients. In our previous study, multiepitope DNA and peptide cancer vaccines consisted of the most immunodominant epitopes of ACRBP and SYCP1 antigens were designed by bioinformatic tools. In this study, the effect of prophylactic co-immunization with these DNA and peptide cancer vaccines in the 4T1 breast cancer animal model was assessed. Serum levels of the peptide-specific IgG total, IgG2a and IgG1 were measured by enzyme-linked immunosorbent assay (ELISA). Also, the efficacy of the immunized mice splenocytes' for producing interleukin-4 (IL-4) and interferon-γ (IFN-γ) was evaluated. The co-immunization caused a significant (P < .05) increase in the serum levels of IgG1 and IgG2a. The co-immunized mice splenocytes exhibited significantly enhanced IL-4 (6.6-fold) and IFN-γ (19-fold) production. Also, their lymphocytes exhibited higher proliferation rate (3-fold) and granzyme B production (6.5-fold) in comparison with the control. The prophylactic co-immunization significantly decreased the breast tumors' volume (78%) and increased the tumor-bearing mice survival time (37.5%) in comparison with the control. Taking together, prophylactic co-immunization with these multiepitope DNA and peptide cancer vaccines can activate the immune system against breast cancer. However, further experiments are needed to evaluate their efficacy from different angles.

Exosomes Shuttle TREX1-Sensitive IFN-Stimulatory dsDNA from Irradiated Cancer Cells to DCs

Radiotherapy (RT) used at immunogenic doses leads to accumulation of cytosolic double-stranded DNA (dsDNA) in cancer cells, which activates type I IFN (IFN-I) via the cGAS/STING pathway. Cancer cell-derived IFN-I is required to recruit BATF3-dependent dendritic cells (DC) to poorly immunogenic tumors and trigger antitumor T-cell responses in combination with immune checkpoint blockade. We have previously demonstrated that the exonuclease TREX1 regulates radiation immunogenicity by degrading cytosolic dsDNA. Tumor-derived DNA can also activate cGAS/STING-mediated production of IFN-I by DCs infiltrating immunogenic tumors. However, how DNA from cancer cells is transferred to the cytoplasm of DCs remains unclear. Here, we showed that tumor-derived exosomes (TEX) produced by irradiated mouse breast cancer cells (RT-TEX) transfer dsDNA to DCs and stimulate DC upregulation of costimulatory molecules and STING-dependent activation of IFN-I. In vivo, RT-TEX elicited tumor-specific CD8⁺ T-cell responses and protected mice from tumor development significantly better than TEX from untreated cancer cells in a prophylactic vaccination experiment. We demonstrated that the IFN-stimulatory dsDNA cargo of RT-TEX is regulated by TREX1 expression in the parent cells. Overall, these results identify RT-TEX as a mechanism whereby IFN-stimulatory dsDNA is transferred from irradiated cancer cells to DCs. We have previously shown that the expression of TREX1 is dependent on the RT dose size. Thus, these data have important implications for the use of RT with immunotherapy. Cancer Immunol Res; 6(8); 910-20. ©2018 AACR.

Live Attenuated Leishmania donovani Centrin Gene-Deleted Parasites Induce IL-23-Dependent IL-17-Protective Immune Response against Visceral Leishmaniasis in a Murine Model

No vaccine exists against visceral leishmaniasis. To develop effective vaccines, we have previously reported protective role of live attenuated centrin gene-deleted Leishmania donovani (LdCen^-/- ) parasites through induction of Th1 type immune response in mice, hamsters, and dogs. In this study, we specifically explored the role of Th17 cells in LdCen^-/- -induced host protection in mice. Our results showed that compared with wild-type L. donovani infection, LdCen^-/- parasites induce significantly higher expression of Th17 differentiation cytokines in splenic dendritic cells. There was also induction of IL-17 and its promoting cytokines in total splenocytes and in both CD4 and CD8 T cells following immunization with LdCen^-/- Upon challenge with wild-type parasites, IL-17 and its differentiating cytokines were significantly higher in LdCen^-/- -immunized mice compared with nonimmunized mice that resulted in parasite control. Alongside IL-17 induction, we observed induction of IFN-γ-producing Th1 cells as reported earlier. However, Th17 cells are generated before Th1 cells. Neutralization of either IL-17 or IFN-γ abrogated LdCen^-/- -induced host protection further confirming the essential role of Th17 along with Th1 cytokines in host protection. Treatment with recombinant IL-23, which is required for stabilization and maintenance of IL-17, heightened Th17, and Tc17 responses in immunized mice splenocytes. In contrast, Th17 response was absent in immunized IL-23R^-/- mice that failed to induce protection upon virulent Leishmania challenge suggesting that IL-23 plays an essential role in IL-17-mediated protection by LdCen^-/- parasites. This study unveiled the role of IL-23-dependent IL-17 induction in LdCen^-/- parasite-induced immunity and subsequent protection against visceral leishmaniasis.