The effects of IL-1ß stimulated human umbilical cord mesenchymal stem cells on polarization and apoptosis of macrophages in rheumatoid arthritis.

Macrophages play an important role in the pathogenesis of rheumatoid arthritis (RA), in which the functions of pro-inflammatory macrophages (M1) and anti-inflammatory macrophages (M2) are different. Our previous studies have demonstrated that interleukin-1ß (IL-1ß) stimulated human umbilical cord mesenchymal stem cells (hUCMSCs) increase the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and initiate breast cancer cell apoptosis via ligand to death receptor 4 (DR4) and DR5. In this study, we examined the effect of IL-1ß stimulated hUCMSCs (IL-1ß-hUCMSCs) on immunoregulation of M1 and M2 macrophages in vitro and in the RA mouse model. The results showed that IL-1ß-hUCMSCs increased macrophage polarization into M2 macrophages and enhanced apoptosis of M1 macrophages in vitro. Moreover, the intravenous injected IL-1ß-hUCMSCs in RA mice rehabilitated the imbalance of M1/M2 ratio and thus demonstrated the potential to reduce inflammation in RA. This study advances our knowledge of the underlying immunoregulatory mechanisms involved in IL-1ß-hUCMSCs to induce M1 macrophage apoptosis and promote the anti-inflammatory polarization of M2 macrophages and demonstrates the potential of IL-1ß-hUCMSCs to reduce inflammation in RA.

[Determination of 39 fatty acids in liver of rats by gas chromatography-mass spectrometry].

Fatty acids not only form phospholipids that contribute to the formation of cell membranes but also participate in many metabolic activities, such as energy storage and cell signal transduction. The liver plays a key role in the synthesis and metabolism of fatty acids. The composition and contents of fatty acids in the liver are closely related to body health. Most fatty acid-detection methods require a large sample size and can detect only a small number of fatty acids. Therefore, a sensitive and efficient method to determine fatty acids in the liver is urgently required. Herein, a method based on gas chromatography-mass spectrometry (GC-MS) was established for the simultaneous determination of 39 fatty acids in 1.1 mg of liver tissue. Different extraction methods and derivatization conditions were compared to develop an optimal sample-treatment method. The performance of two different columns in separating the target fatty acids were also compared. A total of 10 mg of liver was added to 450 µL of normal saline and ground at -35 ℃ to obtain a homogenate. Next, 50 µL of the homogenate (equivalent to 1.1 mg of liver) was added with 750 µL of chloroform-methanol (1∶2, v/v) to extract total fatty acids. The fatty acid extracts were dried under nitrogen, and then derivatized at 100 ℃ for 90 min after being added with methanol containing 5% sulfuric acid. The fatty acid methyl esters were extracted with hexane and then separated on an SP-2560 capillary column (100 m×0.25 mm×0.2 µm; Supelco, USA) via GC-MS. The results revealed that all 39 fatty acid methyl esters detected had good linearities in the certain mass concentration ranges with correlation coefficients (R2) greater than 0.9940. The limits of detection (LOD) and quantification (LOQ) of these methyl esters in the liver were 2-272 ng/mg and 7-906 ng/mg, respectively. The accuracy and precision of the method were evaluated by spiking the liver homogenate with tridecylic acid and eicosanoic acid at low (0.09 µg/mg), moderate (0.90 µg/mg), and high (5.40 µg/mg) concentration levels. The recoveries ranged from 82.4% to 101.0% with an intraday relative standard deviations (RSDs) (n=5) of 3.2%-12.0% and interday RSDs (n=3) of 5.4%-13.4%. The method was successfully applied to detect fatty acids in the livers of four healthy male Sprague-Dawley (SD) rats and four male SD rats with abnormal liver function induced by perfluorooctane sulfonate (PFOS). PFOS is a persistent organic pollutant. Twenty-six fatty acids were detected in the livers of both groups. Among the fatty acids investigated, pentadecanoic acid (C15∶0), γ-linolenic acid (C18∶3n6), and elaidic acid (C18∶1n9t) cannot be detected by the methods reported in the literature. By contrast, the method developed in this study could separate the isomers of oleic acid (elaidic acid, C18∶1n9t; oleic acid, C18∶1n9c) and linolenic acid (linolelaidic acid, C18∶2n6t; linoleic acid, C18∶2n6c). In conclusion, the developed method is simple and can detect a large number of fatty acids using small sample amounts and few reagents. More importantly, it could successfully separate fatty acid isomers. These findings indicate that the developed method is suitable for the detection of fatty acid composition and contents in the liver in clinical and experimental research.