Expression of Notch homologues in local tissue inflammation in rheumatoid arthritis (RA) and cultured synoviocytes has been reported, but the expression profile of Notch-related molecules in peripheral lymphocytes in RA remains unclear. In this study, we measured the expression of Notch receptors and downstream molecules in peripheral lymphocytes from RA patients.
Expression of Notch receptors in peripheral lymphocytes of RA patients was assessed by both flow cytometry and real-time polymerase chain reaction (PCR). Expression of the representative Notch target gene HES-1 and the regulatory gene NUMB in purified T helper cells from RA patients was determined by real-time PCR, and expression of Notch intracellular domain (ICD) was determined by immunoblot analysis.
There was an increased expression of Notch 2, Notch 3, and Notch 4 in T helper cells from active RA patients, among which increased expression of Notch 3 was mainly by activated T cells. Notably, expression of Notch 3 in T cells decreased in inactive RA patients and the level was similar to that of healthy controls (HC). Notch receptors were rarely observed on B cells and no difference in expression was found between RA patients and HC. T helper cells from RA patients exhibited increased expression of the target gene HES-1 but decreased expression of the negative modulation gene NUMB of Notch signalling. There was also an increased nuclear translocation of Notch-ICD in T helper cells from active RA disease.
The present study demonstrated that T helper cells from RA patients display a significantly altered expression profile of Notch receptors and enhanced activation of Notch signalling compared with HC.