The Role of Hyaluronan and CD44 in the Pathogenesis of Lupus Nephritis

Table 1

Functions of native and depolymerized hyaluronan.

Native hyaluronan	Hyaluronan fragments
Contributes to tissue integrity and maintenance of epithelial cell phenotype	Induces chemokine and cytokine secretion in infiltrating, renal tubular epithelial and endothelial cells
Contributes to water balance and regulation of tissue hydration	Induces phosphorylation of signaling pathways, for example, MAPK
Contributes to transportation and distribution of plasma proteins	Induces cell proliferation and migration in chondrocytes, endothelial cells and fibroblasts
Protects against tissue damage by scavenging free radicals	Activates NFκB
Anti-inflammatory-can inhibit activation of inflammatory cells	Induces nitric oxide synthase
Protects against apoptosis	Suppresses cell death and apoptosis in cell culture
Anti-angiogenic	Promotes angiogenesis
Immunosuppressive-prevents ligand binding to surface receptors	Increases matrix protein synthesis, for example, collagen type I
Inhibits phagocytosis	Increases transcription of matrix metalloproteinases

Hyaluronan fragments: range from 4 to 40 saccharide units.