4-OI ameliorates bleomycin-induced pulmonary fibrosis by activating Nrf2 and suppressing macrophage-mediated epithelial-mesenchymal transition

OBJECTIVES

Pulmonary fibrosis (PF) is a chronic and refractory interstitial lung disease with limited therapeutic options. 4-octyl itaconate (4-OI), a cell-permeable derivative of itaconate, has been shown to have anti-oxidative and anti-inflammatory properties. However, the effect and the underlying mechanism of 4-OI on PF are still unknown.

METHODS

WT or Nrf2 knockout (Nrf2^-/-) mice were intratracheally injected with bleomycin (BLM) to establish PF model and then treated with 4-OI. The mechanism study was performed by using RAW264.7 cells, primary macrophages, and conditional medium-cultured MLE-12 cells.

RESULTS

4-OI significantly alleviated BLM-induced PF and EMT process. Mechanism studies have found that 4-OI can not only directly inhibit EMT process, but also can reduce the production of TGF-β1 by restraining macrophage M2 polarization, which in turn inhibits EMT process. Moreover, the effect of 4-OI on PF and EMT depends on Nrf2.

CONCLUSION

4-OI ameliorates BLM-induced PF in an Nrf2-dependent manner, and its role in alleviating PF is partly due to the direct inhibition on EMT, and partly through indirect inhibition of M2-mediated EMT. These findings suggested that 4-OI has great clinical potential to develop as a new anti-fibrotic agent for PF therapy.

Detection of myeloma cell-derived microvesicles: a tool to monitor multiple myeloma load

The persistence of tumor load in multiple myeloma (MM) lead to relapse in patients achieving complete remission (CR). Appropriate and effective methods of myeloma tumor load monitoring are important for guiding clinical management. This study aimed to clarify the value of microvesicles in monitoring MM tumor load. Microvesicles in bone marrow and peripheral blood were isolated by differential ultracentrifugation and detected by flow cytometry. Western blotting was applied to assess myosin light chain phosphorylation levels. Flow cytometry to detect Ps⁺CD41a^-, Ps⁺CD41a^-CD138⁺, Ps⁺CD41a^-BCMA⁺ microvesicles from bone marrow can be used to predict myeloma burden, furthermore, Ps⁺CD41a^- microvesicles may as a potential index to MRD test. Mechanistically, the releasing of microvesicles from MM cell was regulated by Pim-2 Kinase via Phosphorylation of MLC-2 protein.

Maternal propionate supplementation ameliorates glucose and lipid metabolic disturbance in hypoxia-induced fetal growth restriction

Intrauterine growth restriction (IUGR), one of the major complications of pregnancy, is characterized by low birth weight and results in higher risks for long-term problems including developing metabolic and cardiovascular diseases. Short-chain fatty acids (SCFAs), especially propionate, have been reported to correct glucose and lipid disorders in metabolic diseases. We hypothesized that maternal propionate supplementation could prevent glucose and lipid metabolic disturbance in hypoxia-induced IUGR. Here, in our study, maternal hypoxia was induced from gestational day (GD) 11 to GD 17.5 to establish an IUGR mouse model. Maternal propionate treatment reversed reduced birth weight in male IUGR offspring. Hepatic transcriptomics demonstrated that SP treatment significantly lowered glucose and lipid metabolism-related genes (Scd1, G6pc, Pck1 and Fasl) in IUGR offspring. KOG enrichment analysis showed that propionate-induced down-regulated differential expressed genes (DEGs) mainly belonged to lipid transport and metabolism. KEGG enrichment results showed that the down-regulated DEGs were mostly enriched in PPAR and FoxO signaling pathways. We also found that maternal oral administration of SP decreased serum lipid content, attenuated hepatic insulin resistance and liver lipid accumulation, reduced hepatic key gene expressions of gluconeogenesis and lipogenesis, increased energy expenditure and improved liver function in 11-week-old male IUGR offspring. These results indicate that maternal propionate supplementation increases birth weight and corrects hepatic glucose and lipid metabolic disturbance and energy expenditure in male mice born with IUGR, which may provide a basis for using propionate to treat IUGR disease.

Dehydrocostus Lactone Attenuates Methicillin-Resistant Staphylococcus aureus-Induced Inflammation and Acute Lung Injury via Modulating Macrophage Polarization

Dehydrocostus lactone (DHL), a natural sesquiterpene lactone isolated from the traditional Chinese herbs Saussurea lappa and Inula helenium L., has important anti-inflammatory properties used for treating colitis, fibrosis, and Gram-negative bacteria-induced acute lung injury (ALI). However, the effects of DHL on Gram-positive bacteria-induced macrophage activation and ALI remains unclear. In this study, we found that DHL inhibited the phosphorylation of p38 MAPK, the degradation of IκBα, and the activation and nuclear translocation of NF-κB p65, but enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and the expression of Nrf2 and HO-1 in lipoteichoic acid (LTA)-stimulated RAW264.7 cells and primary bone-marrow-derived macrophages (BMDMs). Given the critical role of the p38 MAPK/NF-κB and AMPK/Nrf2 signaling pathways in the balance of M1/M2 macrophage polarization and inflammation, we speculated that DHL would also have an effect on macrophage polarization. Further studies verified that DHL promoted M2 macrophage polarization and reduced M1 polarization, then resulted in a decreased inflammatory response. An in vivo study also revealed that DHL exhibited anti-inflammatory effects and ameliorated methicillin-resistant Staphylococcus aureus (MRSA)-induced ALI. In addition, DHL treatment significantly inhibited the p38 MAPK/NF-κB pathway and activated AMPK/Nrf2 signaling, leading to accelerated switching of macrophages from M1 to M2 in the MRSA-induced murine ALI model. Collectively, these data demonstrated that DHL can promote macrophage polarization to an anti-inflammatory M2 phenotype via interfering in p38 MAPK/NF-κB signaling, as well as activating the AMPK/Nrf2 pathway in vitro and in vivo. Our results suggested that DHL might be a novel candidate for treating inflammatory diseases caused by Gram-positive bacteria.

IL-6-type cytokines enhance epidermal growth factor-stimulated astrocyte proliferation

Proliferating astrocytes are frequently observed in diseased and injured brains. These newly generated astrocytes are necessary to reestablish the barriers that isolate the CNS from the rest of the body; however, they also create a matrix that inhibits regeneration and remyelination. Therefore, it is important to understand the mechanisms that enable a terminally differentiated astrocyte to reenter the cell cycle. Ciliary neurotrophic factor (CNTF), interleukin-6 (IL-6), transforming growth factor-alpha (TGF-alpha), and fibroblastic growth factor-2 (FGF-2) are four cytokines that are rapidly elevated in damaged neural tissue. These cytokines also have been implicated in glial scar formation. We sought to determine whether IL-6 and CNTF stimulate astroglial proliferation alone or in combination with other mitogens. Intraparenchymal CNTF modestly increased the number of proliferating cell nuclear antigen (PCNA) and glial fibrillary acidic protein (GFAP) double positive astrocytes when introduced by stereotactic injection into the adult rat brain. When applied directly to highly enriched rat forebrain astrocyte cultures, neither CNTF nor IL-6-stimulated DNA synthesis. Therefore, they are not astroglial mitogens. However, both cytokines synergized with epidermal growth factor (EGF), increasing its mitogenicity by approximately twofold. Astrocytes that had been "aged" for at least 3 weeks in vitro became refractory to EGF; however, when these "aged" astrocytes were pretreated with either IL-6 or CNTF for as little as 2 h, they became competent to reenter the cell cycle upon exposure to EGF. These data suggest that IL-6 type cytokines, likely by activating STAT family transcription factors, induce the expression of signaling molecules that endow resting astrocytes with the competence to respond to mitogens and to reenter the cell cycle.