摘要
Background： The previous study showed that mycophenolic acid （MPA） synergizing with lipopolysaccharide （LPS） promotcd interleukin （IL）-1β release, but the mechanism is unclear. This study aimed to investigate the nlechanism ofMPA synergizing with LPS to induce IL-1β release. Methods： Undiluted human blood cells, THP- I human rnyeloid leukemia mononuclear cells （THP- 1 ） cells, or monocytes were stimulated with L PS and treated with or without M PA, and the supernatant IL-1β was detected by enzyme-linked immunosorbent assay. The m RN A levels of IL- 1β were detected by real-time quantitative polymerase chain reaction. The intracellular protein levels of nuclear factor kappa B （NF-κ） phospho-p65 （p-p65）, precursor interleukin-1β （pro-IL-1β）, NOD-like receptor pyrin domain containing-3 （NLRP3）, and cysteine aspartic acid-specific protease-1 （caspase-1 ） p20 in THP-1 cell were measured by Western blot. Results： The MPA alone failed to induce IL-1β, whereas MPA synergized with LPS to increase IL-1β in a dose-dependent manner （685.00 ± 20.00 pg/ml in LPS ＋ 5 μmol/L MPA group, P =0.035; 742.00 ± 31.58 pg/ml in LPS ＋ 25 μmol/L MPA group, P = 0.017：1000.00 ± 65.59 pg/ml in LPS ＋ 75 μmol/L MPA group, P = 0.024： versus 408.00 ± 35.50 pg/ml in LPS group）. MPA alone has no effect on the IL-1β mRNA expression, LPS induced the expression of IL-1β mRNA 2761 fold, and LPS ＋ MPA increased the IL-1β expression 3018 fold, which had the same effect with LPS group （P = 0.834）. MPA did not affect the intracellular NF-κB p-p65 and pro-IL-1β protein levels but activated N LRP3 inflammasonae. Ac-YVAD-cmk blocked the activation ofcaspase-1 and subsequently attenuated IL- 1β secretion （ 181.00 ± 45.24 pg/ml in LPS ＋ M PA ＋ YVAD group vs. 588.00 ± 41.99 pg/ml in LPS ＋ M PA group, P= 0.014）. Conclusions： Taken together, MPA synergized with LPS to induce IL- 1β release via the activation of caspase- 1, rather than the enhanced production ofpro-IL-1β. These findings suggested that patients immunosuppressed with mycophenolate mofetil may have overly activated caspase- 1 during infection, which might contribute to a more sensitive host defense response to invading germs.
Background： The previous study showed that mycophenolic acid （MPA） synergizing with lipopolysaccharide （LPS） promotcd interleukin （IL）-1β release, but the mechanism is unclear. This study aimed to investigate the nlechanism ofMPA synergizing with LPS to induce IL-1β release. Methods： Undiluted human blood cells, THP- I human rnyeloid leukemia mononuclear cells （THP- 1 ） cells, or monocytes were stimulated with L PS and treated with or without M PA, and the supernatant IL-1β was detected by enzyme-linked immunosorbent assay. The m RN A levels of IL- 1β were detected by real-time quantitative polymerase chain reaction. The intracellular protein levels of nuclear factor kappa B （NF-κ） phospho-p65 （p-p65）, precursor interleukin-1β （pro-IL-1β）, NOD-like receptor pyrin domain containing-3 （NLRP3）, and cysteine aspartic acid-specific protease-1 （caspase-1 ） p20 in THP-1 cell were measured by Western blot. Results： The MPA alone failed to induce IL-1β, whereas MPA synergized with LPS to increase IL-1β in a dose-dependent manner （685.00 ± 20.00 pg/ml in LPS ＋ 5 μmol/L MPA group, P =0.035; 742.00 ± 31.58 pg/ml in LPS ＋ 25 μmol/L MPA group, P = 0.017：1000.00 ± 65.59 pg/ml in LPS ＋ 75 μmol/L MPA group, P = 0.024： versus 408.00 ± 35.50 pg/ml in LPS group）. MPA alone has no effect on the IL-1β mRNA expression, LPS induced the expression of IL-1β mRNA 2761 fold, and LPS ＋ MPA increased the IL-1β expression 3018 fold, which had the same effect with LPS group （P = 0.834）. MPA did not affect the intracellular NF-κB p-p65 and pro-IL-1β protein levels but activated N LRP3 inflammasonae. Ac-YVAD-cmk blocked the activation ofcaspase-1 and subsequently attenuated IL- 1β secretion （ 181.00 ± 45.24 pg/ml in LPS ＋ M PA ＋ YVAD group vs. 588.00 ± 41.99 pg/ml in LPS ＋ M PA group, P= 0.014）. Conclusions： Taken together, MPA synergized with LPS to induce IL- 1β release via the activation of caspase- 1, rather than the enhanced production ofpro-IL-1β. These findings suggested that patients immunosuppressed with mycophenolate mofetil may have overly activated caspase- 1 during infection, which might contribute to a more sensitive host defense response to invading germs.
基金
This study was supported by grants from National Natural Science Foundation of China （No. 81501417 and No. 81671623）.
