Scientists from UCLA’s Center for Regenerative Medicine at Regenerative and Stem Cell Research at UCLA have developed a device that allows researchers to detect rare T cells capable of infecting viruses, cancers and other diseases marking.
The approach could increase scientists’ understanding of how these critical immune cells react to a wide range of diseases and advance the development of T cell therapies. This includes immunotherapies that is aimed at stimulating the activity and size of cancers or viruses that aim to regulate the activity of T cells that are proactive in autoimmune diseases such as diabetes and multiple sclerosis.
The study, published today in Proceedings of the National Academy of Sciences, describes how the new method, called CLInt-Seq, combining and developing existing methods to collect and genetically order rare T cells.
“T cells are essential for protecting the body against both diseases and cancers,” said Pavlo Nesterenko, first author of the new paper and a graduate student in Dr. Owen Witte’s lab. “They are both the influencers and organizers of the body’s immune response, which means they can be used as a therapeutic and can study the dynamics to shed light on overall immune activity.”
T cells stand out from other immune cells because they are equipped with molecules on their surface called T-cell receptors that recognize fragments of foreign proteins called antigens.
Our bodies make millions and millions of T cells every day and each of these cells has its own set of receptors. Each T-cell receptor is capable of recognizing one specific antigen. One T-cell receptor may recognize an antigen from the virus that causes the common cold while another recognize an antigen from breast cancer, for example.
When a T cell encounters an antigen recognized by its receptor, it activates, secrete large numbers of copies of itself and commands other parts of the immune system to attack cells with that antigen.
Researchers around the world are exploring ways to collect T cells with receptors that target cancer or other diseases such as the SARS-CoV-2 virus from patients, expanding these cells in the process surgery and then return this larger population of targeted T cells to patients to increase their immune response.
The problem is, in most of the cells we have access to, whether from peripheral blood or samples taken from other parts of the human body, T cells are found with interesting receptors in very low numbers. Procedures for capturing and recognizing these T cells are labor intensive and need to develop. “
Dr. Owen Witte, Principal Research Author and Founding Director, Broad Stem Cell Research Center, University of California, Los Angeles
Part of the reason this process is ineffective is that when T cells identify the antigen for which they have the corresponding receptor, they send out signals that stimulate other nearby cells to part implemented.
“The so-called bystander cells are excited by the activity around them, but they are not really able to react with the antigen that triggers the immune response,” said Witte, who holds the headrest. President of developmental immunology in the department of microbiology, immunology and molecular genetics and is a member of the UCLA Jonsson Comprehensive Cancer Center.
When researchers try to separate T cells from specific receptors using traditional methods, they end up capturing many of those bystander cells. CLInt-Seq alleviates this problem by introducing a mechanism that allows researchers to differentiate T cells with interesting receptors from most bystander cells.
T cells with specific receptors are just the first step. For these isolated cells to be useful, they need to be analyzed using droplet-based mRNA sequences, also called Drop-seq, which can measure messenger RNA expression in thousands of individual cells at the same time. time.
“Once you know the range of interesting T-cell receptors, you can use that information to develop cures that do either of those cells in the fight against cancer and viruses or introducing regulatory T cells with this receptor sequence to inhibit an inactive immune response in a specific region, ”Nesterenko said.
The process of separating T cells from specific receptors requires that the contents of the cells be fixed in place by using chemicals that make connections between the proteins within each cell and their surroundings – this method is called cross-linking. Unfortunately, cross-linking reduces the RNA of T cells, which makes Drop-seq analysis very challenging. CLInt-Seq overcomes this barrier by using a method for modulating cross-linking and thus preserving the RNA of T cells.
“The innovation of this system is that it combines an improved method that identifies T-cell receptors with greater specificity by chemical modification that makes this process consistent with a mRNA-based series. droplet, “Witte said. “This addresses challenges that are at the heart of finding T-cell receptors for the treatment of cancer and other diseases as well as viral infections – from viruses such as the virus that causes COVID- 19 to harmful viruses such as Epstein Barr or herpes. “
Source:
University of California, Los Angeles
Magazine Reference:
Nesterenko, PA, et al. (2021) A droplet-based mRNA sequence of cells located and permeabilized by CLInt-seq allows antigen-specific TCR cloning. Proceedings of the National Academy of Sciences. doi.org/10.1073/pnas.2021190118.