The study will reveal the transcriptomic signature linked to the aberrant activation of B lymphocytes in RA identifying novel molecular potential targets for inflammation resolution and immune tolerance promotion. The combination with B lymphocytes phenotyping will dissect the impact of the identified genes on B lymphocyte maturation and activation in RA. Moreover, in vitro study on B lymphocyte cultures using selective JAK1 inhibition will reveal, at deeper level, its transcriptomic effect on RA B lymphocytes activation profile and phenotype, providing the discovery of new biomarkers of the loss of immunological tolerance, active disease and long lasting disease remission.

Inclusion Criteria:

1. Signed Written Informed Consent. Before any study procedures are performed,subjects will have the details of the study described to them, and they will be given a written informed consent document to read. Then, if subjects consent to participate in the study, they will indicate that consent by signing and dating the informed consent document in the presence of trained study personnel.
2. Patients fulfilling classification criteria for Rheumatoid Arthritis (2010 ACR/EULARclassification criteria)
3. Age: 18-70 years
4. For preclinical cohort: Individuals with positivity for ACPA or IgM/IgA RF without clinical signs of arthritis, whose positivity is not related to other concomitant pathologic conditions.
5. For naive to treatment cohort: RA patients without previous exposure to conventional DMARDs or biologic/targeted synthetic-DMARDs.
6. For resistant to treatment cohort: RA patients with failure to previous conventionalDMARDs for inadequate response or side effects.
7. For remission RA cohort: RA patients in sustained clinical and ultrasound remission as stated in section 3.3.1.
8. For healthy control cohort: Healthy donors will be aged from 18 to 70 years.

Exclusion Criteria:

1. Severe and uncontrolled infections such as sepsis and opportunistic infections.
2. Patients who are currently included in any interventional clinical trial in RA.
3. RA patients in therapy with other biologics.
4. Healthy donors receiving anti-inflammatory drugs

This is an interventional research without experimental drug which will be performed at the Division of Clinical Immunology of the Fondazione Policlinico Universitario A. Gemelli IRCCS in Rome, Italy, where patients with Rheumatoid Arthritis will undergo to synovial tissue inflammation assessment through minimally invasive US-guided synovial tissue biopsy.