Legionella lipoprotein activates toll-like receptor 2 and induces cytokine production and expression of costimulatory molecules in peritoneal macrophages

Legionella bacterium, an intracellular pathogen of mononuclear phagocytes, causes acute fatal pneumonia, especially in patients with impaired cellular immune responses. Until recently, however, the toll-like receptor (TLR) engagement of bacterial proteins derived from Legionella is uncertain. We previously showed that a 19-kDa highly conserved peptidoglycan-associated lipoprotein (PAL) of Legionella pneumophila induced the PAL-specific B cell and T cell responses in mice. In this study, we observed that the rPAL antigen of L. pneumophila, as an effector molecule, activated murine macrophages via TLR2 and produced proinflammatory cytokines such as IL-6 and TNF-alpha. In both BALB/c and TLR4-deficient C3H/HeJ mice, pretreatment of macrophages with anti-TLR2 mAb showed severely impaired cytokine production in response to the rPAL. In addition, in vitro the rPAL treatment increased the cell surface expression of CD40, CD80, CD86 and MHC I/II molecules. We further showed that the synthetic CpG-oligodeoxynucleotides (CpG ODN) coadministered with the rPAL enhanced IL-12 and IL-6 production and expression of CD40, CD80 and MHC II compared to the rPAL treatment alone. In conclusions, these results indicate that Legionella PAL might activate macrophages via a TLR2-dependent mechanism which thus induce cytokine production and expression of costimulatory and MHC molecules.

Effect of lipoxins on proliferation and secretion of peritoneal macrophages from patients with precclampsia in vitro / 中华妇产科杂志

Objegtlve To study the effect of lipexins on the proliferation and secretion of peritoneal macrophages from patients with preeclampsia in vitro.Methods Peritoneal macrophages were obtained from 24 patients with preeclampsia(preeclampsia group)and 24 normal pregnant women(normal pregnant group)who were treated in the First Affiliated Hospital of Wenzhou Medical Coilege from March to July 2007.Enzyme linked immunosorbent assay (ELISA) was used to detect the concentration of tumor necrosis factor-α(TNF-α)in the supernatant of macrophages which were pulsed with lipoxins at different concentrations(0,10,100 nmol/L)in both groups after 48 hours.Methyl thiazolyl tetrazolium (MTT)assay was used to detect the inhibition rate of cell proliferation of macrophages which were pulsed with lipoxins at different concentrations(0,10,100 nmol/L)in both groups after 24 hours.Results (1)The concentration of TNF-α:the levels of TNF-α were(1867.5±47.3),(1836.9±4.5) and (1800.5±2.7)ng/L after treatment with differed concentrations of lipoxins(0,10,100 nmol/L)in preeclampsia group vs normal pregnant group[(791.3±62.2),(789.4±2.3),(781.5±1.9)ng/L].The levels of TNF-α in preeclampsia group were significantly higher than that in normal pregnant group(P＜0.05).Lipoxins significantly inhibited the concentration of TNF-α in a dose-dependent manner in preeclampsia group (P＜0.05),while it had no significant effect in normal pregnant group(P＞0.05).(2)Cell proliferation inhibition:Incubation with lipoxins produced a dose-dependent(0,10,100 nmol/L)inhibitory effect on proliferation in preeclampsia group,[(14.8±6.3)%,(32.9±3.6)%,(36.7±3.8)%],vs normal pregnant group[(16.8±6.9)%,(16.7±5.4)%,(15.9±2.1)%].The rate of cell proliferation in preeclampsia group was significantly hisher than that in normal pregnant group.Lipoxins significandy inhibited this growth(P＜0.05),while it had no significant effect in normal pregnant group(P＞0.05).Conclusion Lipoxins can inhibit the proliferation of macrophage and secretion of TNF-α in preeclampsia in a dose-dependent manner.Lipoxins may be potentially useful in prevention and treatment of preeclampsia.

IGF-1R, p-ERK is involved in LDLs-induced mouse peritoneal macrophage survival* / 中国病理生理杂志

AIM: To study the effects of low density lipoproteins (LDLs) on insulin-like growth factor-1 receptor (IGF-1R), phosphorylated extracellular signal-regulated kinase (p-ERK), Bcl-2 and Bax protein expression in mouse peritoneal macrophages (MPMs). METHODS: Using the methods of immunocytochemistry and Western blotting, the expression of IGF-1R, p-ERK, Bcl-2 and Bax protein in MPMs treated with LDLs, anti-IGF-1R antibody (?-IR-3) or ERK inhibitor (PD98059) were detected. RESULTS: oxLDL significantly increased the IGF-1R protein expression in a dose and time-dependent manner. P-ERK protein expression induced by oxLDL peaked at 5 min. Moreover, oxLDL could induced ERK translocation from cytoplasm to nuclear. When given ?-IR-3, p-ERK protein expression was significantly inhibited, and ERK translocation disappeared. oxLDL increased Bcl-2 protein expression and reduced Bax expression in a dose and time-dependent manner. When given PD98059, Bcl-2 and Bax protein expression induced by oxLDL altered significantly. Native LDL had no significant effect on the expression of these four proteins. CONCLUSIONS: oxLDL may promote cultured MPMs survival at least by enhancing IGF-1R expression and ERK phosphorylation, and there may be many pathways involved in MPMs survival induced by oxLDL, Whereas native LDL had no effects on culture MPMs.

Effect of ?-MSH on the NO production and SOCS-3 mRNA expression in murine peritoneal macrophages induced by LPS / 中国病理生理杂志

AIM: To explore the anti-LPS mechanisms of ?-melanocyte-stimulating hormone (?-MSH), the effects of ?-MSH on the expression of SOCS-3 mRNA and the production of NO in murine peritoneal macrophages induced by LPS were investigated. METHODS: BALB/c mouse peritoneal macrophages were cultured in vitro and induced by LPS, ?-MSH and LPS with ?-MSH, respectively. The expression of SOCS-3 mRNA was detected using reverse transcription polymerase chain reaction (RT-PCR). NO produced in macrophages was tested with Griess reagent. RESULTS: The level of NO and the expression of SOCS-3 mRNA were significantly increased in macrophages stimulated with LPS.?-MSH markedly decreased the expression of SOCS-3 mRNA and almost completely inhibited the production of NO induced by LPS. CONCLUSION: These results suggest that the negative regulative circuits operated by SOCS are activated during the inflammation induced by LPS, but SOCS might not be involved in the anti-LPS mechanism of ?-MSH.