Expression and regulation of the CC-chemokine ligand 20 during human tuberculosis

CC-chemokine ligand 20 (CCL20), a unique chemokine ligand of CC-chemokine receptor 6 (CCR6), play roles in various pathologic conditions. However, the characteristic expression profiles of CCL20 during human tuberculosis (TB) have been largely unknown. The present study analyzed the production and regulatory mechanisms of CCL20 in peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages (MDM) from active pulmonary TB patients and healthy controls (HC). The 30-kDa antigen (Ag) of Mycobacterium tuberculosis actively induced the production of CCL20 by human PBMC and MDM. A comparative analysis revealed that the expression of CCL20 protein was prominently up-regulated in PBMC, MDM, bronchoalveolar lavage fluids (not in sera) from TB patients compared with the corresponding cells or body fluids from HC. Blockade of either tumour necrosis factor-alpha or interferon-gamma, but not interleukin-10, significantly attenuated the CCL20 production. In addition, recombinant CCL20 induced CCR6 expression by CD45RO+ T lymphocytes in a dose-dependent manner. Furthermore, the expression of CCR6 was significantly increased in CD45RO+ T lymphocytes from TB patients, as compared with those from HC. Pharmacological inhibition studies showed that the 30-kDa Ag-induced CCL20 mRNA expression involves mitogen-activated protein kinases (MAPK; extracellular signal-regulated kinase 1/2 and p38)- and NF-kappaB-dependent signalling. Collectively, the present study demonstrated that TB patients show the up-regulated expression of CCL20, which is modulated by proinflammatory cytokines, and through MAPK/NF-kappaB-mediated transcriptional mechanisms. The findings suggest important implications of potential roles of CCL20-CCR6 in immunopathogenesis of TB.