Related Experiment Video
Updated: Feb 8, 2026
Evaluation of Caspase Activation to Assess Innate Immune Cell Death
Published on: January 20, 2023
Mycophenolic Acid Synergizing with Lipopolysaccharide to Induce Interleukin-1β Release via Activation of Caspase-1
Xue-Chan Huang1, Yi He2, Jian Zhuang1
1Southern Medical University, Guangzhou, Guangdong 510515, China.
Background:
The previous study showed that mycophenolic acid (MPA) synergizing with lipopolysaccharide (LPS) promoted interleukin (IL)-1β release, but the mechanism is unclear. This study aimed to investigate the mechanism of MPA synergizing with LPS to induce IL-1β release.
Methods:
Undiluted human blood cells, THP-1 human myeloid leukemia mononuclear cells (THP-1) cells, or monocytes were stimulated with LPS and treated with or without MPA, and the supernatant IL-1β was detected by enzyme-linked immunosorbent assay. The mRNA levels of IL-1β were detected by real-time quantitative polymerase chain reaction. The intracellular protein levels of nuclear factor kappa B (NF-κB) 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 NLRP3 inflammasome. Ac-YVAD-cmk blocked the activation of caspase-1 and subsequently attenuated IL-1β secretion (181.00 ± 45.24 pg/ml in LPS + MPA + YVAD group vs. 588.00 ± 41.99 pg/ml in LPS + MPA 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 of pro-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.
Insights
Mycophenolic acid (MPA) combined with lipopolysaccharide (LPS) increases interleukin-1β (IL-1β) release by activating caspase-1, not by boosting pro-IL-1β. This suggests potential overactivation of caspase-1 in immunosuppressed patients during infection.
Area of Science:
- Immunology
- Molecular Biology
Background:
- Previous studies indicated mycophenolic acid (MPA) synergizes with lipopolysaccharide (LPS) to promote interleukin-1β (IL-1β) release, but the underlying mechanism remained unclear.
- This study investigated the synergistic mechanism of MPA and LPS in inducing IL-1β release.
Purpose of the Study:
- To elucidate the molecular mechanism by which MPA and LPS synergistically induce IL-1β release.
- To determine whether the synergy involves enhanced pro-IL-1β production or caspase-1 activation.
Main Methods:
- Human blood cells, THP-1 cells, and monocytes were stimulated with LPS and treated with MPA.
- IL-1β levels in supernatants were measured by ELISA.
- mRNA expression of IL-1β was quantified using real-time PCR.
- Intracellular protein levels of NF-κB, pro-IL-1β, NLRP3, and caspase-1 were analyzed by Western blot.
Main Results:
- MPA alone did not induce IL-1β, but synergized with LPS in a dose-dependent manner to increase IL-1β secretion.
- MPA and LPS co-treatment increased IL-1β mRNA expression similarly to LPS alone.
- MPA did not affect NF-κB p-p65 or pro-IL-1β levels but activated the NLRP3 inflammasome.
- Inhibition of caspase-1 with Ac-YVAD-cmk significantly attenuated IL-1β secretion.
Conclusions:
- MPA synergizes with LPS to induce IL-1β release primarily through the activation of caspase-1, independent of increased pro-IL-1β production.
- These findings suggest that patients on mycophenolate mofetil may experience heightened caspase-1 activity during infections, potentially enhancing host defense.
- The study highlights a specific molecular pathway for MPA-LPS-induced IL-1β release, relevant to immunosuppressed individuals.
Related Concept Videos
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.
01:24Caspases
01:27Combined Effects of Drugs: Synergism
Such synergistic combinations...
01:19Formation of Lipopolysaccharides
01:10Acid–Base Equilibria: Activity-Based Definition of pH
In solutions of very low ionic strength—for example, pure water—the...
01:28Chemotherapy-Induced Nausea and Vomiting: Neurokinin-1 Receptor Antagonists