Scientific corner

Down-modulation of toll-like receptor 2 expression on granulocytes and suppression of interleukin-8 production due to in vitro treatment with cellulose acetate beads

Mayumi Hidaka 1Kenji Fukuzawa, Ther Apher Dial. 2011 Dec;15(6):572-8.

The Adacolumn, which is filled with cellulose acetate beads (CA beads), has been used as a medical device for inflammatory diseases. The CA beads selectively adsorb granulocytes and monocytes and remove them from the peripheral blood. The anti-inflammatory effects of the Adacolumn are possibly caused by removal of these cells but also due to the functional changes in the processed cells. In this study, we investigated the effects of CA beads treatment on modulation of the expression of innate immunity receptors such as the Toll-like receptor (TLR) family and production of an inflammatory cytokine, interleukin-8 (IL-8). Changes in the expressions of TLR1, 2, 4 and 6 in peripheral leukocytes exposed to CA beads were examined by flow cytometry. TLR2 expression on the surface of granulocytes exposed to CA beads was decreased, but the amount of intracellular TLR2 was increased, possibly by internalization. These changes were not observed in monocytes or lymphocytes. Peptidoglycan (PGN) treatment produced similar changes in TLR2 on granulocytes. We also measured the amounts of IL-8 in cultured blood treated with lipopolysaccharide (LPS) and PGN, which are known TLR agonists. PGN-induced IL-8 production was lower in CA beads-treated leukocytes than that in non-treated leukocytes, but LPS did not induce these changes. Based on these findings, we conclude that the down-modulation of TLR2 and suppression of IL-8 production on granulocytes by CA beads, may play an important role in the anti-inflammatory effects of the Adacolumn.

Scientific corner

W1254 The Decreased TLR2 Expression and Elevated IL-8 Production On Peripheral Leukocytes in Patients with Active Ulcerative Colitis: the Modulation of the Leukocyte Sensitivity to Pgn By Granulocyte and Monocyte Apheresis

Suzuki, Yasuo; Yamada, Akihiro; Aoki, Hiroshi; Osamura, Aisaku; Nakamura, Kentaro; Yoshimatsu, Yasushi; Hosoe, Nobuo; Takada, Nobuo; Tsuda, Yukio; Shirai, Koji (2008). W1254 The Decreased TLR2 Expression and Elevated IL-8 Production On Peripheral Leukocytes in Patients with Active Ulcerative Colitis: the Modulation of the Leukocyte Sensitivity to Pgn By Granulocyte and Monocyte Apheresis. Gastroenterology, 134(4), A-665–. doi:10.1016/S0016-5085(08)63105-4 

BACKGROUND & AIM: Mucosal lesions of active ulcerative colitis (UC) are characterized by acute inflammatory cell (polymorphonuclear granulocyte, PMN) infiltrate and ulceration. Granulocyte and monocyte apheresis (GMA) using a column device, Adacolumn, selectively adsorbs and removes leukocytes from the peripheral blood, and has been reported to be effective in patients with active UC. The aim of this study was to investigate the expression of toll like receptor 2 (TLR2) on PMNs and monocytes in patients with active UC as compared to the level in healthy subjects and see the impact of GMA on TLR2. METHODS: Fortyeight patients with active UC, Clinical Activity Index (CAI, Lichtiger index) ≥5, were included in this study. Patients received several GMA sessions (maximum 10 sessions), and CAI ≤ 3 was considered remission. Blood samples were obtained from patients at each GMA session and also from healthy subjects (n=14), after obtaining informed consent. The expression of TLR2 was investigated by flowcytometry. In several samples, IL-8 production by cultured blood upon stimulation with peptidoglycan (PGN, a ligand for TLR2) was measured (n=21). RESULTS: An average of CAI at the entry was 11.0 (n=48), and remission rate by GMA was 56.3%(27/48). At the baseline, the expression of TLR2 on PMN of patients with active UC was significantly less than the level in healthy subjects (p<0.001). Further, the improvement in CAI was accompanied by a trend towards normalization of TLR2 on PMN (up-regulation, p<0.05) together with a significant fall (P<0.01) of plasma IL-8 level. However, as for the patients with still active symptoms (CAI>5) in course of GMA therapy, the decreased TLR2 on PMN and the elevated release of IL-8 from PGN-stimulated leukocytes were kept on. By exposing blood to the column carriers In Vitro, TLR2 expression on the cell surface of PMN was decreased, but increased within the cellular of PMN. Similarly, in the blood on column outflow of GMA, the TLR2 expression on PMN and IL-8 production by PGN-stimulation were significantly decreased (TLR2:P<0.001, IL-8:P<0.001), indicating that leukocyte sensitivity to PGN is weakened by GMA column. CONCLUSION: The expression of TLR2 on PMN in patients with active UC is significantly decreased compared with remission status or healthy subjects. In connection with the decreased TLR2 expression, the IL-8 production by PGN-stimulated leukocytes is elevated in patients with active UC. These changes seem to reflect PMN activation based on UC disease activity. GMA or exposure of blood to GMA carriers is associated with down-modulation of the TLR2 expression on PMN and also leukocyte sensitivity to PGN

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