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Sjögren's syndrome is a rare disease (affecting just under one in 10,000 adults) with an onset that most commonly occurs after the age of 50. It is linked to an inflammation of the endocrine glands, including the lacrimal and salivary glands, which are infiltrated by B and T lymphocytes (white blood cells); as a consequence, the glands can no longer secrete sufficient fluids in the skin and mucous membranes.
MicroRNAs are small regulatory RNAs that can bind to messenger RNAs when genes are expressed and thus inhibit their translation into proteins. Since they intervene in the functioning of genes without modifying their sequence, these microRNAs are considered epigenetic agents. A team from the CEA's Institut François-Jacob has conducted a quantitative study of the microRNAs expressed in B and T lymphocytes. These cells, which are directly involved in Sjögren's syndrome, were sortable from the blood of patients and controls. For the first time, the researchers were able to identify different amounts of microRNAs in the blood cells of patients specific to each cell type.
The team then focused on the effect of microRNA under-expression by studying one of them: miR-30b-5p. This microRNA targets the messenger RNA of B-cell activating factor, which has a key role in the disease. When miR-30b-5p is blocked in cells by synthesis inhibitors (antagomirs), this activation factor increases. This is the idea of a treatment for Sjögren's syndrome, based on the administration of microRNA in glands where they are under-expressed. These microRNAs would thus make it possible to control the activation of the lymphocytes responsible for this disease.
Deregulation of microRNA expression in purified T and B lymphocytes from patients with primary Sjögren's syndrome | Annals of the rheumatic diseases
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