Tyrophagus putrescentiae (Tp) as a storage mite inhabitats in stored grains, hay, and straw at agricultural areas. T. putrescentiae stimulates an immune response and triggers inflammatory cytokines release, and thus it is a source of allergen that sensitize and induce allergic reactions. Also, T. putrescentiae has been reported to cause asthma and atopic disease by cross-reactivity with Dermatophagoides pteronyssinus (Dp). The study on T. putrescentiae in human monocytic THP-1 cells is not enough to understand cytokine expression and pathological mechanisms. The aim of this study is to investigate the effect of T. putrescentiae extract (TpE) on production of inflammatory cytokines and expression of mRNA level in THP-1 cells. THP-1 cells are treated with TpE and supernatants were analyzed for the production of cytokines using enzyme-linked immunosorbent assay (ELISA). mRNA level in the culture cells was measured by a reverse transcriptase-polymerase chain reaction (RT-PCR). As a result of this study, TpE significantly induced secretion of interleukin-6, interleukin-8, and monocyte chemotactic protein-1 (MCP-1) in THP-1 cells in time- and dose-dependent manner. These results suggest that TpE may play a role in contributing to inflammatory disease through stimulation of immune cell. Further research of T. putrescentiae is needed to understand the elucidation of the pathogenic mechanism.

House dust mites (HDMs) play an important role in the occurrence of allergic diseases such as asthma and atopic dermatitis. Dermatophagoides pteronyssinus (Der p) is one of the most prevalent HDMs. It mediates the activation of T cells and monocytes, and induces the elevation of immunoglobulin E levels in allergic diseases. However, the effects of Der p on human monocytes have not been fully understood. In the present study, we investigated whether or not Der p has a great effect on the chemotactic activity of the human monocytic cell line, THP-1 cells, as induced by CC chemokines. We also show that the Der p extract (DpE) increased the chemotactic activity of THP-1 cells in response to MCP-1, RANTES, MIP-1α, and TARC, but has no effect on the expressions of CC chemokine receptors (CCRs) binding to CC chemokines in THP-1 cells. Protease inhibitors, such as aprotinin and E64, blocked the increased chemotaxis, while cytoplasmic Ca2+ influx mediated by these chemokines was inhibited by DpE. These results indicate that DpE increases the chemotactic activity of THP-1 cells in response to CC chemokines by regulating the cells’ protease-dependent mechanism. This finding may be useful in identifying the pathogenesis of allergic diseases induced by Der p.