Morphological transformation of calcium phenylphosphonate microspheres induced by micellization of γ-polyglutamic acid.

The γ-polyglutamic acid (γ-PGA), an anionic homo-polyamide similar to naturally occurring polyaspartic acid in mollusk shells, is selected for morphosynthesis of calcium phenylphosphonates. It has been found that they exhibit a series of interesting morphological transformation with changing γ-PGA amount and initial pH. A rare, reversible transformation between solid and hollow microspheres, in particular, is observed. Systematic investigation suggests, for the first time, that γ-PGA exhibits the "schizophrenic" micellization behavior in response to structural and morphological changes caused by spontaneous hydrophobic modification with phenylphosphonic acids and calcium ions. The present work introduces a new paradigm for biomimetic synthesis. The results not only bring insight into the template mechanism of biomacromolecules from spontaneous hydrophobic modification, but also provide a universally applicable strategy for morphosynthesis of metal phosphonates containing hydrophobic groups. In addition, solid and hollow calcium phenylphosphonate microspheres with hierarchical structures are excellent adsorbents in the removal of aqueous lead ions. They consistently exhibit 100% Pb2+ removal efficiency when Pb2+ concentration is not more than 600 mg L-1 and even after four recycles, making them promising candidates as efficient and reusable adsorbents.

Nrf2 regulates the inflammatory response, including heme oxygenase-1 induction, by mycoplasma pneumoniae lipid-associated membrane proteins in THP-1 cells.

A series of inflammatory responses caused by Mycoplasma pneumoniae largely depend on the lipid-associated membrane proteins (LAMPs). Nuclear factor E2-related factor 2 (Nrf2), a transcription factor, is considered to be a critical modulator of inflammatory responses and cellular redox homeostasis. Monocytes play an important role in the invasion and immunity to resist pathogens. Here, we investigated the role of Nrf2 in the anti-inflammatory response stimulated by LAMPs using the human monocyte cell line THP-1. LAMPs were shown to affect the localization of Nrf2, and the levels of reactive oxygen species and inflammatory reactants, including nitric oxide (NO), prostaglandin E2 (PGE2) and cytokines (IL-6, IL-8), were highly elevated in LAMP-stimulated Nrf2-silenced THP-1 cells. Moreover, LAMPs induced the levels of mRNA and the expression of heme oxygenase-1 (HO-1). In summary, our results demonstrated that LAMPs cause nuclear translocation of Nrf2, which further suppresses the expression of inflammatory reactants in THP-1 cells.

Macrophage-activating lipopeptide-2 requires Mal and PI3K for efficient induction of heme oxygenase-1.

AIMS: This study is to investigate the mechanisms by which macrophage-activating lipopeptide-2 (MALP-2) induces heme oxygenase (HO)-1, a cytoprotective enzyme that catalyzes the degradation of heme, in human monocytes. METHODS: Human monocytic THP-1 cells were cultured for transient transfection with plasmids and stimulation with MALP-2 for indicative time intervals. After incubation with MALP-2, cells were collected and disrupted, before being tested for promoter activity using luciferase assay. For analysis of proteins, immunoreactive bands were detected using an enhanced chemiluminescence Western blotting system, and the band intensity was measured by densitometryic analysis. For the detection of co-immunoprecipitation, SDS-PAGE was performed and the membranes were probed using respective antibodies. To investigate the cellular localization of NF-E2-related factor 2 (Nrf2), cells underwent immunofluorescence staining and confocal microscopy, and were analyzed using electrophoretic mobility shift assay. RESULTS: MALP-2-induced HO-1 expression and promoter activity were abrogated by transfection with dominant negative (DN) plasmids of TLR2 and TLR6, or their neutralizing antibodies. However, inhibition of MyD88 or transfection with the DN-MyD88 was insufficient to attenuate HO-1 expression. In contrast, mutation or silencing of MyD88 adapter-like (Mal) by DN-Mal or siRNA almost completely blocked HO-1 induction. Btk, c-Src and PI3K were also involved in MALP-2-induced HO-1 expression, as revealed by specific inhibitors LFM-A13, PP1 and LY294002, or by transfection with siRNA of c-Src. MALP-2-induced activation of PI3K was attenuated by transfection with DN mutant of Mal, and by pretreatment with LFM-A13 or PP1. Furthermore, MALP-2 stimulated the translocation of Nrf2 from the cytosol to the nucleus and Nrf2 binding to the ARE site in the HO-1 promoter, which could also be inhibited by pretreatment with a PI3K inhibitor, LY294002. CONCLUSIONS: These results indicated that MALP-2 required TLR2/6, Btk, Mal and c-Src to activate PI3K, which in turn initiated the activation of Nrf2 for efficient HO-1 induction.