ABSTRACT
Objective:To study the role of neutrophil density and molecular mechanism in neutrophils-mediated inflammatory response induced by monosodium urate (MSU) crystals.Methods:Polymorphonuclear neutrophils (PMNs) isolated from healthy human peripheral blood were treated with MSU crystals at different density (5×10 6/ml, 20×10 6/ml, 100×10 6/ml) in vitro. The mean fluorescence intensity (MFI) of PMNs and production of reactive oxygen species (ROS) were detected by flow cytometry. The distribution of MSU crystals was observed by polarized light microscopy. The neutrophil extracellular traps (NETs) formation was detected by immune fluorescence. The cytokines in cell supernatant were measured by beads assay including interleukin 1β (IL-1β) , tumor necrosis factor α (TNFα) , interleukin 8 (IL-8) , interferon inducible protein 10 (IP-10) , macrophage inflammatory protein 1 (MIP-1) , monokine induced by interferon-γ (MIG) , macrophage inflammatory protein 1α (MIP-1α) , macrophage inflammatory protein 1β (MIP-1β) . Results:(1) After MSU crystal intervention, the side scatters (SSC) of neutrophils with medium-cell density (20×10 6/ml) and high-cell density (100×10 6/ml) were 128±13 and 93±9 respectively, both significantly lower than 170±19 in low-cell density (5×10 6/ml) group.(2) Similarly, compared with low-cell density group, the MFI (lucifer yellow) of PMNs with high-cell density was 1.8±0.2, also significantly decreased ( P<0.05). When co-treated with oxygenated adenosine triphosphate (oxATP), MFI of PMNs were all enhanced consistently. (3) In MSU crystals stimulated PMNs, after adding 2′,7′-dichlorodihydrofluorescein diacetate, the MFI values were 0.85±0.32, 2.49±0.78, 4.54±1.02 in low cell density groups, medium cell density groups, and high cell density groups respectively, indicating that the generation of ROS was positively correlated with the increase of PMN density ( P<0.05). After the intervention of oxATP, the ROS production was significantly reduced. (4) MSU crystal induced NETs formation, especially at high cell density. NETs formation promotes MSU crystal aggregation, which could be partially overcome by oxATP pretreatment. (5) The expression of cytokines were all significantly decreased in the supernatant of PMNs at high cell density exposed to MSU crystals compared with PMNs at medium cell density ( P<0.05) . Conclusion:The PMN-mediated inflammation induced by MSU crystals is cell density dependent, and ATP may play a role in partially overcoming the process.
ABSTRACT
Objective To clarify whether the Cosmc gene down-regnhtion in lgA nephropathy (IgAN) patients is resulted from genetic disorders or external suppressions. Methods Forty IgAN patients, 16 non-IgAN glomerulonephritis patients and 21 healthy controls were enrolled in the study. Genomie DNA was extracted and then Cosmc gene was amplified and sequenced. Peripheral B lymphoeytes were isolated and cultured with RPMI-1640 alone or plus lipopolysaecharide (LPS). The Cosmc mRNA expression levels at baseline, after RPMI-1640 culture or RPMI-1640+LPS treatment were measured respectively by real-time RT-PCR. Results (1) Only 2 missense mutations and 2 silent mutations were detected in coding frame region of Cosine gene in 2 IgAN patients. (2) The baseline Cosmc gene expression level was significantly lower in IgAN patients (31% of that in healthy controls) than that in healthy controls. (3) Relative quantification PCR indicated that Cosmc mRNA expression level was significantly increased (219% of baseline) after RPMI-1640 culture, and treatment of LPS could strongly inhibit this effect. (4) The Cosmc gene expression of healthy control was not affected by RPMI-1640 or LPS. Conclusion It is not genetic disorders but external suppression to cause the down-regulation of Cosmc gene mRNA expression in IgAN.