A UNIQUE type of T cell has been discovered in patients with rheumatoid arthritis (RA). Research conducted at the Brigham and Women’s Hospital (BWH), Boston, Massachusetts, USA, has recognised the pivotal role these cells play in mediating the damaging immune response accountable for the joint inflammation associated with RA. Existing treatments rely on non-specific mechanisms that inhibit parts of the immune system and are increasing in effectiveness, although a cure is yet to be discovered.
The pain associated with this autoimmune condition is caused by inflammation of the synovium, a soft tissue lining that surrounds the synovial joints. An abnormal immune response causes the body to mistakenly recognise host cells as foreign, although the precise cause is not known. Evidence gathered from previous research indicates the involvement of T cells in the development of RA, primarily through their ability to stimulate antibody-producing B cells.
Tissue samples obtained from RA patients were analysed using ‘disease deconstruction’ methods, permitting a level of detail not previously possible. Mass cytometry and RNA sequencing techniques were used to isolate and differentiate between different cell populations by distinguishing between cell surface markers and their gene expression.
Researchers discovered a marked increase in the number of T cells, specifically, CD4+ helper T cells, accounting for almost one-quarter of all T cells within the sample. The study showed that this population are programmed to migrate to inflamed tissue, promote B cell responses, and encourage auto-antibody production. “Our results help illuminate a path toward treatments that are much more precise and focussed only on the most relevant immune cells.” explained Dr Deepak Rao, Human Immunology Centre, BMH.
Future activity will be directed at determining the signalling pathways responsible for the development of these particular CD4+ T cells. Additional focus will be concentrated on whether these cells play a role in any additional autoimmune diseases, including lupus, multiple sclerosis, and Type 1 diabetes mellitus. This cell type may present as an effective target for the development of RA treatments in the future. Dr Rao concluded: “These cells do not adhere to the conventional view of helper T cells, and that is really interesting.”