Researchers Uncover Previously Unknown Function Of Immune Dendritic Cells Which Can Pave Way For Newer Treatment Protocols
Source: Thailand Medical News Dec 16, 2019 5 years, 6 days, 6 hours, 10 minutes ago
Rheumatoid arthritis, psoriasis, and Crohn’s disease and other
autoimmune disorders plague tens of millions of individuals worldwide and are the result of the body’s
immune system, whose role is to fight against disease-causing pathogens, turning against itself.
Although several new drugs designed to fight these diseases are now available,the downside is that some of these drugs, a class of biologics called
TNF inhibitors, carry a risk of serious infections and even
cancer.
A medical research team led by Michigan Medicine may have discovered why. Their study, which appears in the journal
Science Advances, reveals a previously unknown function of a specific type of
immune cell called
dendritic cells.
Dr Michal Olszewski, DVM, Ph.D., a research biologist with the Ann Arbor VA Hospital, associate professor of internal medicine at U-M and senior author on the paper told
Thailand Medical News, “Dendritic cells are the master orchestrator of the
immune response, telling the other cells of the
immune system what to do.”
Typically,
dendritic cells are part of the innate
immune network, the body’s first line of defense against a threat. They help another type of
immune cell called T cells, which are part of the adaptive
immune system, learn how to respond appropriately to a given germ or disease-causing agent.
This new study reveals that the cells have their own form of program memory and hinges on a well-known
immune signaling molecule called
TNFalpha, which causes the inflammation so painfully familiar to those with arthritis and other
autoimmune diseases.
Dr Olszewski added, “Our studies have found that
TNFalpha is part of the system that programs
dendritic cells so that they know how to program T cells.
TNFalpha is especially important in helping
dendritic cells teach T cells to fight off infections like certain fungal infections and tuberculosis that can hide inside the body’s cells. This is why people taking these
autoimmune drugs are particularly at risk.”
Dr Jintao Xu, Ph.D. of the Ann Arbor VA Hospital and co-first author commented, “Some microbes are very clever and fool the
immune system so it doesn’t detect and kill them, causing disease. But in our study, we found in the presence of
TNFalpha, microbes can’t do those tricks. With its help,
dendritic cells don’t get fooled and therefore can activate the protective T cell response.”
In addition, the group found that the
dendritic cell programming relied on rapidly developing epigenetic changes affording
ng>dendritic cell program stability and conferred to the T cells. This finding has major implications for the development of therapies targeting the immune system.
Dr Olszewski added, “This will be important for vaccine development, for understanding how the immune system responds to chronic infections, and why people who take anti-TNF for treatment of autoimmune diseases are particularly vulnerable to these kinds of diseases.”
Besides proof-of-concept study, the team found that by removing dendritic cells from mice taking an anti-TNF drug, exposing the cells to TNFalpha and reinjecting them into the mice, they could induce a normal immune response against infection. This procedure hints at a complimentary therapy for people on anti-TNF drugs as well as a potential advanced immunotherapy for cancer.
Dr Olszewski concluded, “Cancer can produce a group of signals that dampen the immune response. We speculate that one could program the dendritic cells outside of the cancerous environment and make them remember that they are to remain activated and continue to fight the cancer instead of ignoring it.”
Reference: Eastman, et al. (2019) Epigenetic stabilization of DC and DC precursor classical activation by TNFα contributes to protective T cell polarization. Science Advances. DOI: 10.1126/sciadv.aaw9051 
