The aim of this study is to examine the associations between inflammatory disease activity and endothelial function in rheumatoid arthritis (RA) and spondyloarthritis patients treated with methotrexate and Tumor Necrosis Factor alpha (TNFalpha)inhibitor in combination or methotrexate or TNFalpha-inhibitor alone. Further, to look for improvement in endothelial function, and decrease in bone and cartilage destruction during treatment with the combination therapy of TNFalpha-inhibitor and methotrexate in RA and Psoriatic Arthritis (PSA) patients. Last, examine the TNFalpha inhibitors influence on endothelial function and levels of bone and cartilage markers in patients with Ankylosing Spondylitis (AS).

Inclusion Criteria:

• Males and females 18-80 years
• Able and willing to give written informed consent, and to comply with the requirements of the study protocol.
• Fulfilling the ACR 1987 revised diagnostic criteria for the diagnosis rheumatoid arthritis, or the diagnostic criteria by Moll and Wright for the diagnosis psoriatic arthritis, or the modified New York diagnostic criteria for ankylosing spondylitis.
• Clinical indication for starting treatment with methotrexate, TNFalpha- inhibitor or combination therapy.
• Use of reliable method of contraception for women with childbearing potential.

Exclusion Criteria:

• Lack of cooperativity
• Positive serology for hepatitis B or C
• History of positive HIV status.
• History of tuberculosis or untreated tuberculosis.
• PPD more than 15 mm in previously BCG immunized subjects. PPD 6 mm or more if not previously BCG immunized.
• Histoplasmosis or Listeriosis
• Persistent or recurrent infections
• Any inflammatory disease of permanence not related to RA, PSA or AS.
• Pregnancy or breast-feeding.
• Use of prednisolone more than 10 mg daily for 2 weeks at inclusion.
• Use of TNFalpha-inhibitor the last 4 weeks.
• History of cancer.
• Uncontrolled diabetes.
• Congestive heart failure (Nyha 3-4)
• Recent stroke (within 3 months)
• Previous diagnosis or signs of central nervous system demyelinating disease.
• Previously diagnosed immunodeficiency.

Patients with RA and spondyloarthritis starting with either combination therapy of TNFalpha-inhibitor and methotrexate or methotrexate or TNFalpha-inhibitor alone, at Lillehammer Hospital for Rheumatic diseases.Decision about treatment modality will be based on conventional clinial judgement.