In a recent study entitled “B regulatory cells are decreased and functionally impaired in patients with systemic sclerosis”, researchers report that a specific population of B cells – regulatory B cells – with established functions in immune suppression, have their numbers markedly reduced and functions impaired in systemic sclerosis patients. These findings suggest a potential new therapeutics for systemic sclerosis patients by rescuing regulatory B cells function. The study was published in the Arthritis & Rheumatology journal.
Systemic sclerosis, also known as scleroderma (meaning hard skin), is characterized by excessive deposition of collagen in the skin, although the disease frequently progresses into a systemic disease therefore affecting internal organs, such as kidneys, heart, lungs and intestine. The disease induces vascular damage, fibrosis and autoantibodies production. Scleroderma remains a disease with high mortality and no effective treatment.
Immune cells, such as T cells, have been implicated in systemic sclerosis disease pathogenesis, but the role of B cells (immune cells responsible for antibody production) remains largely unknown, despite the fact that B cell infiltrates can be observed in systemic sclerosis lesions. Recently, a small population of B cells named regulatory B cells (Bregs) was reported to modulate and suppress immune responses, thereby preventing autoimmunity. This was achieved by secreting interleukin 10 (IL-10).
The authors determined the number and function of Bregs in systemic sclerosis, particularly the Bregs-producing IL-10. To this end, the team measured Bregs in 45 patients with systemic sclerosis (from which 12 patients had early disease and 33 had systemic sclerosis-associated pulmonary fibrosis), 10 healthy controls and 10 patients with rheumatoid arthritis-associated pulmonary fibrosis. They found that not only Bregs numbers were decreased in systemic sclerosis patients, but were also functionally impaired as their expression of IL-10 was significantly reduced upon Bregs stimulation.
B10 cells (IL-10 producing) negatively regulate inflammation and autoimmunity, with studies in mice showing B10 cells ameliorate collagen-induced arthritis. These findings suggest that the decreased number of Bregs and inability to produce IL-10 after stimuli have implications in systemic sclerosis pathogenesis. Hence, ex vivo expansion of B10 cells and their administration back into systemic sclerosis patients may constitute a potential new treatment strategy for systemic sclerosis.