[Hyaluronan-mediated regulation of inflammation].

Hyaluronan is high-molecular-weight biopolymer. Its linear structure is created by repeating disaccharide units. A single unit is composed of N-acetyl-D-glucosamine and D-glucuronic acid. Hyaluronan is the main component of the extracellular matrix. Apart from its structural role, hyaluronan can influence cell proliferation, differentiation, and migration, angiogenesis, as well as inflammation and immune cell function. During inflammation, high-molecular-weight hyaluronan is broken down under the influence of free radicals and enzymes to smaller fragments. Numerous literature data show that the effect of haluronan on immune cells is closely dependent on its molecular mass. High-molecular-weight hyaluronan can participate in restraining inflammation, while the low-molecular-weight form possesses a proinflammatory effect and activates immune cells. Through interaction with surface receptors (CD44, RHAMM, TLR4), hyaluronan fragments stimulate immune cells and enhance cytokine and reactive oxygen species production as well as other factors participating in inflammation. Hyaluronate can thus be an important regulator of the inflammatory process. Low-molecular-weight fragments deliver signal about tissue damage and mobilize immune cells, while the high-molecular-form suppresses immune cell function and prevents excessive exacerbation of inflammation.