Full text
| |
| Author(s): |
Raphael Sanches Peres
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2016-09-28 |
| Examining board members: |
Fernando de Queiroz Cunha;
Marcelo Torres Bozza;
Paulo Louzada Júnior
|
| Advisor: | Fernando de Queiroz Cunha |
| Abstract | |
Rheumatoid arthritis (RA) is an autoimmune multifactorial arthropathy with unknown etiology that affects approximately 1% of the adult population. The standard strategy for RA treatment comprises the administration of low doses of methotrexate (MTX), whose antiinflammatory effects are associated with maintenance of high levels of extracellular adenosine (ADO). However, a considerable proportion of RA patients is resistant to MTX treatment and the mechanisms underlying this phenomenon occurs is poorly understood. Within this context, the present study showed that therapeutic efficacy of MTX is associated with expression on Treg cells of the ectoenzyme CD39, whose function is related to the generation of extracellular ADO by ATP metabolism. Specifically, we conducted a longitudinal study and observed that responsive patients to MTX (R-MTX) exhibit an increase in the frequency of circulating Treg cells expressing CD39 after MTX treatment. On the other hand, we found that non-responsive patients to MTX (UR-MTX) have a reduction of CD39 expression on Treg cells, which culminates in an impairment of Treg function. Furthermore, these findings indicate that CD39 expression on Treg cells is a biomarker for therapeutic response to MTX, since UR-MTX patients had a depressed CD39 expression on Treg cells even before MTX treatment. Subsequently, the present study investigated the molecular mechanisms that would cause the reduction of CD39 expression on Treg cells from UR-MTX patients. For this, we demonstrated that TGF-? stimulation increases CD39 expression in isolated and in vitro differentiated Treg cells through participation/activation of the following molecules: receptors of TGF-?, TGFBRII and TGFBRI, signal transducer SMAD2 and transcription factor CREB, through p38 activity dependent-manner. Once identified these molecules involved with CD39 induction, we demonstrated that differentiated Treg cells from healthy individuals with an intrinsic reduction of CD39 expression on circulating Treg cells are unable to increase CD39 expression by TGF-? stimulation. Transposing our findings to RA patients, we found that UR-MTX patients exhibit a reduction of mRNA for TGFBRII and CREB as well as reduction on levels of phospho-SMAD2 and phospho-CREB in CD4+ and Treg cells, suggesting that an impairment in TGF-? signaling pathway, related to induction of CD39 expression on Treg cells, is associated with MTX resistance. (AU) | |
| FAPESP's process: | 12/10438-0 - Association of CD39 expression on Treg cells with the therapeutic efficacy of methotrexate in treatment of rheumatoid arthritis |
| Grantee: | Raphael Sanches Peres |
| Support Opportunities: | Scholarships in Brazil - Doctorate |