Successful cancer immunotherapy hinges on a complex web of cellular interactions within the immune system. It’s particularly exciting to see how vaccinations with small numbers of human plasmacytoid dendritic cells (pDCs) can trigger anti-tumor immunity in patients with metastatic cancer. Despite being a rare subset, pDCs function like the Swiss army knives of the immune system, balancing tolerance and immunity by secreting large amounts of type I interferons, priming T cells, and exerting cytotoxic functions. However, it remains unclear whether all pDCs possess these functions or if the population consists of distinct subsets with specialized roles. This project aimed to identify which pDCs are most effective at inducing cytotoxic T cells to enhance cancer immunity.
Despite advancements in single-cell technologies, the heterogeneity within immune cell populations is still not fully understood. The ImmunoCode project seeked to bridge this gap by developing an innovative single-cell technology platform. This platform would leverage cutting-edge microfluidic approaches and single-cell transcriptomics to enable functional analysis of individual immune cells and the creation of minimal environments free from external influences.
The main objectives of this project were:
1. Understanding the heterogeneity of plasmacytoid dendritic cells.
2. Developing a microfluidic toolbox for high-throughput studies of bi-directional crosstalk between pairs of single cells.
3. Creating complex artificial microenvironments to study the behavior of single pDCs in response to soluble messengers.
This approach would offer a unique opportunity to unravel the functions and plasticity of pDCs. Ultimately, the findings from this project could significantly impact the design of vaccine strategies and the development of diverse cellular vaccines to combat cancer, infectious diseases, and autoimmune disorders.
Final outcomes and impact
For a long-time, cellular communication was attributed to auto-, para-, endo-, or juxtacrine interactions. Only recently have a few studies proposed immune quorum sensing as a new mode of communication. Our platform revealed the presence and regulation of immune quorum sensing of IFN-I dynamics. The scientific impact here is significant, as our approach, technology, and methodologies are not restricted to specific proteins or cells but can be applied to virtually any cell type with expected heterogeneity or cytokine communication systems. This will provide a more comprehensive picture of how cytokine communication and cellular heterogeneity are intertwined, likely extending beyond current dogmas in understanding immune regulation.
Our approach is unique, as no other currently available technology, such as single cell RNA-seq, can study this exciting behavior of single cells. Understanding the molecular basis underlying the heterogeneity within IFN-I secreting cell systems will lead to new and better therapeutic strategies aimed at controlling type I IFN production.
The microfluidic technologies and analysis techniques developed and introduced in this project are certainly beyond the current state-of-the-art. The droplet-based microfluidic system that enables automated, high-throughput, real-time analysis of cytotoxic events is highly novel, as is the combined in-droplet cytokine detection assay. This innovative platform is a breakthrough technology with many possibilities for improving our understanding of cellular functional heterogeneity across a wide variety of immune cells. Consequently, the group of the Principal Investigator (PI) was regularly approached by both academic and industrial stakeholders to explore potential collaborative endeavors. The high level of interest from different stakeholders was unexpected but clearly indicates the potential high impact this technology could have across various fields.
All the objectives were met, leading to several new innovations published in high-impact journals.
