Taurine chloramine selectively regulates neutrophil degranulation through the inhibition of myeloperoxidase and upregulation of lactoferrin
Authors: Kim, Dong Gye; Kwon, Young Min; Kang, In Soon; Kim, Chaekyun
Taurine is a free amino acid rich in neutrophils, and neutrophils play an important role in the forefront defense against infection. Upon neutrophil activation, taurine reacts with hypochlorous acid (HOCl/OCl-) produced by the myeloperoxidase (MPO) system and gets converted to taurine chloramine (Tau-Cl). Neutrophils have three types of granules, of which the primary granule MPO, secondary granule lactoferrin, and tertiary granule matrix metalloproteinase (MMP)-9 are released into the extracellular space by a process called degranulation. MPO produces hypochlorous acid to kill microorganisms, and the released MPO forms neutrophil extracellular traps (NETs) with released chromatin. Excessive secretion of MPO causes oxidative damage to the surrounding tissues. Lactoferrin exerts antioxidant activity, prevents pro-inflammatory pathway activation, sepsis, and tissue damages, and delays neutrophil apoptosis. Our experimental results show that neutrophils released small amount of granules in an inactive state, and phorbol 12-myristate 13-acetate (PMA) andN-formyl-methionine-leucyl-phenylalanine induced neutrophil degranulation. Tau-Cl inhibited the PMA-induced degranulation of MPO and formation of NETs. While Tau-Cl increased the degranulation of lactoferrin, it had no effect on MMP-9 degranulation. MPO negatively regulated the production of macrophage inflammatory protein (MIP)-2, which stimulates the degranulation and migration of neutrophils. Tau-Cl abrogated MIP-2 expression, suggestive of its inhibitory effect on MPO release. The increase in the intracellular level of MPO may negatively regulates MIP-2 expression, thereby contributing to the further regulation of neutrophil degranulation and migration. Here, we suggest that Tau-Cl selectively inhibits MPO degranulation and stimulates lactoferrin degranulation from neutrophils, thereby protecting inflamed tissues from oxidative damage induced by excessively released MPO.
Maytenus robusta Reissek, a medicinal plant popularly used to treat digestive diseases, promotes ameliorative effects in colon and liver of mice exposed to dextran sulfate sodium
JOURNAL OF ETHNOPHARMACOLOGY
Authors: Mees, Marieli; Meurer, Marianne Caroline; Bolda Mariano, Luisa Nathalia; Boeing, Thaise; Somensi, Lincon Bordignon; Mariott, Mariha; Niero, Rivaldo; Cechinel-Filho, Valdir; de Andrade, Sergio Faloni; Duarte, Lucienir Pains; de Sousa, Grasiely Faria; de Souza, Priscila; Da Silva, Luisa Mota
Ethnopharmacological relevance: Maytenus robusta Reissek (Celesteraceae), popularly named as cafezinho do mato or coracao de bugre, is employed to treat inflammatory digestive diseases in the south of Brazil. However, despite popular usage, the effects of this species on an experimental model of ulcerative colitis are unknown. Aim of the study: To evaluate the effects of M. robusta extract (HEMR) on colon and liver from mice with colitis induced by dextran sulfate sodium (DSS). Materials and methods: Firstly, the cytotoxicity of HEMR and its effects on ROS and nitrite production in IEC-6 cells were evaluated. The experimental colitis was established by adding 3% DSS on drinking water of mice and the effects of HEMR (1-100 mg/kg, p.o, once a day by 7 days) in colonic and hepatic tissues were analyzed. Results: The HEMR (1-100 mu g/mL) did not alter the cell viability but reduced nitrite production of IEC-6 stimulated by LPS. Moreover, HEMR (100 mg/Kg) attenuates macro and microscopic alterations in the colon from mice exposed to DSS, as evidenced by a reduction of the colon shortening, attenuation of the epithelial erosion, submucosal edema and preservation of the Goblet cells integrity, as well as the restoration of mucin depletion. The treatment with HEMR increased GSH amount, reduced LOOH levels and normalizes CAT activity in the colon. The group treated with HEMR showed increased GST activity, reduced MPO activity and decreased inflammatory cytokines secretion (TNF and IL-6) in the colonic tissue. In the liver, HEMR increased GST activity, decreased the GPx activity and reduced IL-6 levels. Furthermore, the HEMR treatment reduced AST and ALT serum levels in mice exposed to DSS. Finally, the HEMR was able to reduce intestinal transit. Conclusions: HEMR treatment minimizes inflammation of the colon and maintaining the antioxidant homeostasis. In addition, HEMR may be a potential tool to prevent hepatic injury secondary to ulcerative colitis.