In a previous paper, we reported that triptolide (TP), a commonly used immunomodulator, could attenuate cardiac hypertrophy. This present study aimed to further explore the inhibition of cardiac fibrosis by TP and the possible mechanism from the perspective of the NOD-like receptor protein 3 (NLRP3) inflammasome. Hematoxylin-eosin and Masson’s staining, immunohistochemistry, and immunofluorescence were performed to observe cardiac fibrotic changes in mice and mouse cardiac fibroblasts (CFs). The Western blot, colocalization, and immunoprecipitation were applied to detect protein expression and interactions. Results suggested that TP dose-dependently inhibited cardiac fibrosis induced by isoproterenol and collagen production of CFs induced by angiotensin II. TP exhibited an antifibrotic effect via inhibiting activation of the NLRP3 inflammasome, which sequentially decreased IL-1β maturation, myeloid differentiation factor 88 (MyD88)-related phosphorylation of c-Jun N-terminal kinase (JNK), extracellular regulated protein kinase 1/2 (ERK1/2), and TGF-β1/Smad signaling, and ultimately resulted in less collagen production. Moreover, TP showed no antifibrotic effect in Nlrp3-knockout CFs. Notably, TP inhibited the expression of NLRP3 and apoptosis-associated speck-like proteins containing a caspase recruitment domain (ASC) as well as inflammasome assembly, by interrupting the NLRP3-ASC interaction to inhibit inflammasome activation. Finally, TP indeed inhibited the NLRP3-TGFβ1-Smad pathway in vivo. Conclusively, TP was found to play a dual role in interrupting the activation of the NLRP3 inflammasome to attenuate cardiac fibrosis.

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) has been identified to have the potential to improve lung fibrosis and lung cancer. To avoid the liver and kidney toxicities and the fast metabolism of emodin, emodin-loaded polylactic acid microspheres (ED-PLA-MS) were prepared and their characteristics were studied. ED-PLA-MS were prepared by the organic phase dispersion-solvent diffusion method. By applying an orthogonal design, our results indicated that the optimal formulation was 12 mg/mL PLA, 0.5% gelatin, and an organic phase:glycerol ratio of 1:20. Using the optimal experimental conditions, the drug loading and encapsulation efficiencies were (19.0 ± 1.8)% and (62.2 ± 2.6)%, respectively. The average particle size was 9.7 ± 0.7 μm. In vitro studies indicated that the ED-PLA-MS demonstrated a well-sustained release efficacy. The microspheres delivered emodin, primarily to the lungs of mice, upon intravenous injection. It was also detected by microscopy that partial lung inflammation was observed in lung tissues and no pathological changes were found in other tissues of the ED-PLA-MS-treated animals. These results suggested that ED-PLA-MS are of potential value in treating lung diseases in animals.

Radiation-induced pulmonary fibrosis (RIPF) is a severe complication in patients treated with thoracic irradiation. Until now, there are no effective therapeutic drugs for RIPF. In the present study, we attempted to evaluate the effect of Magnesium isoglycyrrhizinate (MgIG) on RIPF, and to further explore the underlying mechanisms. We found that MgIG treatment markedly improved radiation-induced lung pathological changes, reduced collagen deposition, and decreased the transforming growth factor beta1 (TGF-β1) elevation induced by irradiation. In addition, MgIG treatment significantly relieved oxidative damage of pulmonary fibrosis in mice characterized by increased antioxidant factors expression and reduced oxidative factors expression. And, MgIG treatment also significantly reduced the production of intracellular reactive oxygen species (ROS) in vitro. Interestingly, administration of MgIG achieved lower expression levels of Nox4, and phosphorylation of p38MAPK and Akt in vivo and in vitro. Furthermore, treatment with MgIG notably reduced the expression levels of myofibroblast markers, Nox4, and phosphorylation of p38MAPK and Akt both in vivo and in vitro. More importantly, the inhibitory effects of MgIG on fibroblast differentiation were enhanced when the p38MAPK/Akt/Nox4 pathway was inhibited using their respective antagonists or Nox4 siRNA in vitro. Taken together, these findings suggested that MgIG could attenuate RIPF partly by inhibiting fibroblast differentiation, which was closely related to modulation of the p38MAPK/Akt/Nox4 pathway.