[PATHOGENESIS OF UNDIFFERENTIATED SPONDYLOARTHRITIS].

Spondyloarthritis or spondyloarthropathy (SpA) is a multifactorial disease in which a disturbed interplay occurs between the immune system and environmental factors on a predisposing genetic background, which leads to inflammation and structural damage of target tissue. Many recent researches on development of SpA showed important role of innate and adaptive immunity as well as of prominent bone tissue remodeling which leads to osteoproliferation and ankylosis. It is believed that possible sites of inflammation in SpA are entheses, sinovium and gut. Current knowledge on inflammation and tissue destruction leads to conclusion that SpA is disease characterized by disorders on different levels. Disorder on the first level is disturbed pathogen recognition and immune response activation, on second level disturbed inflammatory cells migration and on third level disturbed immune response regulation. As follows, disease progress depends on range of disturbances: disease course can be short, as in reactive arthritis, or long-lasting with substantial structural damage, as in ankylosing spondylitis. Unfortunately, there are still no confident markers of disease progression, so at the mere beginning disease is often described as undifferentiated.