The therapeutic mechanism of dexamethasone in lung injury induced by hydrogen sulfide

The lung is one of the primary target organs of hydrogen sulfide(H2S),as exposure to H2S can cause acute lung injury(ALI)and pulmonary edema.Dexamethasone(Dex)exerts a protective effect on ALI caused by exposure to toxic gases and is commonly used in the clinic;however,the underlying mechanisms remain elusive,and the dose is unclear.Methods:In vivo experiments:divided C57BL6 mice into 6 groups at random,12 in each group.The mice were exposed to H2S for 3 h and 5 or 50 mg/kg Dex pretreated before exposure,sacrificed 12 h later.The morphological changes of HE staining and the ultrastructural changes of lungs under transmission electron microscopy were evaluated.The wet/dry ratio of lung tissue was measured.Bronchial alveolar lavage fluid(BALF)protein content and lung permeability index were detected.The expression of AQP5 protein was measured by immunohistochemistry and Western Blot(WB).In vitro experiments:divided human lung adenocarcinoma cell line A549 into 4 groups.1μmol/L dexamethasone was added to pre-incubation.The WB analyzed the protein of p-ERK1/2,p-JNK,and p-p38 in MAPK pathway after 1 h of NaHS exposure;six hours after NaHS exposure,the AQP5 protein was measured by WB.Results:Dex treatment could significantly attenuate the H2S-induced destruction to the alveolar wall,increase the wet-to-dry weight ratio and decrease pulmonary permeability index,with high-dose dexamethasone seemingly functioning better.Additionally,our previous studies showed that aquaporin 5(AQP 5),a critical protein that regulates water flux,decreased both in a mouse and cell model following the exposure to H2S.This study indicates that tThe decrease in AQP 5 can be alleviated by Dex treatment.Additionally,the mitogen activated protein kinase(MAPK)pathway may be involved in the protective effects of Dex in ALI caused by exposure to H2S since H2Sinduced MAPK activation could be inhibited by Dex.Conclusion:The present results indicate that AQP 5 may be considered a therapeutic target for Dex in H2S or other hazardous gases-induced ALI.

Individualized prediction of perineural invasion in colorectal cancer: development and validation of a radiomics prediction model

Objective： To develop and validate a radiomics prediction model for individualized prediction of perineural invasion（PNI） in colorectal cancer（CRC）.Methods： After computed tomography（CT） radiomics features extraction, a radiomics signature was constructed in derivation cohort（346 CRC patients）. A prediction model was developed to integrate the radiomics signature and clinical candidate predictors [age, sex, tumor location, and carcinoembryonic antigen（CEA） level]. Apparent prediction performance was assessed. After internal validation, independent temporal validation（separate from the cohort used to build the model） was then conducted in 217 CRC patients. The final model was converted to an easy-to-use nomogram.Results： The developed radiomics nomogram that integrated the radiomics signature and CEA level showed good calibration and discrimination performance [Harrell＇s concordance index（c-index）： 0.817; 95% confidence interval（95% CI）： 0.811–0.823]. Application of the nomogram in validation cohort gave a comparable calibration and discrimination（c-index： 0.803; 95% CI： 0.794–0.812）.Conclusions： Integrating the radiomics signature and CEA level into a radiomics prediction model enables easy and effective risk assessment of PNI in CRC. This stratification of patients according to their PNI status may provide a basis for individualized auxiliary treatment.

诱导性多能干细胞的低基因组稳定性使非同源末端连接增加

背景与目的诱导性多能干细胞(induced pluripotent stem cells,iPSCs)和胚胎干细胞(embryonic stem cells,ESCs)具有许多共同特征,包括相似的形态、基因表达和体外分化谱。然而,iPSCs的基因组稳定性远低于ESCs。在本研究中,我们研究了iPSCs中DNA损伤修复的改变是否为其具有更大诱变倾向的原因。方法将小鼠iPSCs、ESCs和胚胎成纤维细胞暴露于电离辐射(4 Gy),导致双链DNA断裂。照射4 h后使用全基因组重测序评估DNA损伤修复的保真度。我们还分析了分别源自iPSCs或ESCs的小鼠的基因组稳定性。结果照射后,与胚胎干细胞和胚胎成纤维细胞相比,iPSCs具有较低的DNA损伤修复能力,有更多的体细胞突变和短片段插入缺失。iPSCs有更多的非同源末端连接DNA修复和更少的同源重组DNA修复。源自iPSCs的小鼠比ESCs小鼠以及C57对照小鼠的DNA损伤修复能力更低。结论本研究结果部分表明,iPSCs的低基因组稳定性及其在体内的高致瘤性是由DNA损伤修复的低保真度所致。

Induced Pluripotent Stem Cells Are Sensitive to DNA Damage

Induced pluripotent stem cells （iPSCs） resemble embryonic stem cells （ESCs） in morphol- ogy, gene expression and in vitro differentiation, raising new hope for personalized clinical therapy. While many efforts have been made to improve reprogramming efficiency, significant problems such as genomic instability of iPSCs need to be addressed before clinical therapy. In this study, we try to figure out the real genomic state of iPSCs and their DNA damage response to ionizing radiation （IR）. We found that iPSC line 3FB4-1 had lower DNA damage repair ability than mouse embryonic fibroblast （MEF） cells, from which 3FB4-11ine was derived. After the introduction of DNA damage by IR, the number of 7-H2AX loci in 3FB4-1 increased modestly compared to a large increase seen in MEF, albeit both significantly （P 〈 0.01）. In addition, whole-genome sequencing analysis showed that after IR, 3FB4-1 possessed more point mutations than MEF and the point mutations spread all over chromosomes. These observations provide evidence that iPSCs are more sensitive to ionizing radiation and their relatively low DNA damage repair capacity may account for their high radiosensitivity. The compromised DNA damage repair capacity of iPSCs should be considered when used in clinical therapy.

Deep pedigree analysis reveals family specific ‘‘fingerprint” pattern of DNA methylation for men

DNA methylation plays an essential role in mammalian development[1].However,how DNA methylation is inherited between generations and if there is family-specific DNA methylation pattern remains to be elucidated[2].In this study,we collect male blood samples including a big pedigree of the descendants of an ancient Chinese empire and samples from different haplogroups to study their whole genome DNA methylation pattern.We find 115 male family-specific methylation sites from three families.The difference of whole genome DNA methylation pattern correlates

Lower genomic stability of induced pluripotent stem cells reflects increased non-homologous end joining

Background:Induced pluripotent stem cells(iPSCs)and embryonic stem cells(ESCs)share many common features,including similar morphology,gene expression and in vitro differentiation profiles.However,genomic stability is much lower in iPSCs than in ESCs.In the current study,we examined whether changes in DNA damage repair in iPSCs are responsible for their greater tendency towards mutagenesis.Methods:Mouse iPSCs,ESCs and embryonic fibroblasts were exposed to ionizing radiation(4 Gy)to introduce dou-ble-strand DNA breaks.At 4 h later,fidelity of DNA damage repair was assessed using whole-genome re-sequencing.We also analyzed genomic stability in mice derived from iPSCs versus ESCs.Results:In comparison to ESCs and embryonic fibroblasts,iPSCs had lower DNA damage repair capacity,more somatic mutations and short indels after irradiation.iPSCs showed greater non-homologous end joining DNA repair and less homologous recombination DNA repair.Mice derived from iPSCs had lower DNA damage repair capacity than ESC-derived mice as well as C57 control mice.Conclusions:The relatively low genomic stability of iPSCs and their high rate of tumorigenesis in vivo appear to be due,at least in part,to low fidelity of DNA damage repair.

Transgenerational analysis of H3K4me3 and H3K27me3 by ChIP-Seq links epigenetic inheritance to metabolism

Histone methylation is a kind of important epigenetic modification which occurs on the lysine residue or arginine residue of histone tails（Zhang and Reinberg,2001）.It takes part in multiple biological processes,including gene expression,genomic stability,stem cell maturity,genetic imprinting,mitosis and development（Fischle et al.,2005）.