SAM and folic acid prevent arsenic-induced oxidative and nitrative DNA damage in human lymphoblast cells by modulating expression of inflammatory and DNA repair genes

Glucopeptide Superstructure Hydrogel Promotes Surgical Wound Healing Following Neoadjuvant Radiotherapy by Producing NO and Anticellular Senescence

Neoadjuvant radiotherapy, a preoperative intervention regimen for reducing the stage of primary tumors and surgical margins, has gained increasing attention in the past decade. However, radiation-induced skin damage during neoadjuvant radiotherapy exacerbates surgical injury, remarkably increasing the risk of refractory wounds and compromising the therapeutic effects. Radiation impedes wound healing by increasing the production of reactive oxygen species and inducing cell apoptosis and senescence. Here, a self-assembling peptide (R-peptide) and hyaluronic-acid (HA)-based and cordycepin-loaded superstructure hydrogel is prepared for surgical incision healing after neoadjuvant radiotherapy. Results show that i) R-peptide coassembles with HA to form biomimetic fiber bundle microstructure, in which R-peptide drives the assembly of single fiber through π-π stacking and other forces and HA, as a single fiber adhesive, facilitates bunching through electrostatic interactions. ii) The biomimetic superstructure contributes to the adhesion and proliferation of cells in the surgical wound. iii) Aldehyde-modified HA provides dynamic covalent binding sites for cordycepin to achieve responsive release, inhibiting radiation-induced cellular senescence. iv) Arginine in the peptides provides antioxidant capacity and a substrate for the endogenous production of nitric oxide to promote wound healing and angiogenesis of surgical wounds after neoadjuvant radiotherapy.

DNA Hypomethylation-Mediated Transcription Dysregulation Participates in Pathogenesis of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a highly heterogeneous and genetically complex endocrine disorder. Although the etiology remains mostly elusive, growing evidence suggested abnormal changes of DNA methylation correlate well with systemic and tissue-specific dysfunctions in PCOS. A dehydroepiandrosterone-induced PCOS-like mouse model was generated, which has a similar metabolic and reproductive phenotype as human patients with PCOS, and was used to experimentally validate the potential role of aberrant DNA methylation in PCOS in this study. Integrated DNA methylation and transcriptome analysis revealed the potential role of genomic DNA hypomethylation in transcription regulation of PCOS and identified several key candidate genes, including BMP4, Adcy7, Tnfaip3, and Fas, which were regulated by aberrant DNA hypomethylation. Moreover, i.p. injection of S-adenosylmethionine increased the overall DNA methylation level of PCOS-like mice and restored expression of the candidate genes to similar levels as the control, alleviating reproductive and metabolic abnormalities in PCOS-like mice. These findings provided direct evidence showing the importance of normal DNA methylation in epigenetic regulation of PCOS and potential targets for diagnosis and treatment of the disease.

Association of arsenic exposure with measles antibody titers in US children: Influence of sex and serum folate levels

Exposure to arsenic during childhood is associated with various adverse health conditions. However, little is known about the effect of arsenic exposure on vaccine-related humoral immunity in children. We analyzed data from the National Health and Nutrition Examination Survey (2003-2004 and 2009-2010) to study the relationship between urinary arsenic and measles antibody levels in 476 US children aged 6-11. Multivariable linear regression was used to evaluate the association, adjusting for cycle, age, race, body mass index (BMI), serum cotinine, poverty index ratio, and vitamin B12 and selenium intakes. Stratified analyses were conducted by sex and serum folate levels using the median as cutoff (18.7 ng/mL). The measles antibody concentrations in the 3rd and 4th quartiles were found to have significantly decreased by 28.5 % (95 % Confidence Interval (CI) -47.6, -2.28) and 36.8 % (95 % CI -50.2, -19.5), compared to the lowest quartile among boys with serum folate levels lower than 18.7 ng/ml. The serum measles antibody titers significantly decreased by 16.7 % (95 %CI -25.0, -7.61) for each doubling of creatinine-corrected urinary total inorganic arsenic concentrations in the same group. No associations were found in boys with high serum folate levels or in girls. Further prospective studies are needed to validate these findings and develop interventions to protect children from infectious diseases.

Depletion of S-adenosylmethionine induced by arsenic exposure is involved in liver injury of rat through perturbing histone H3K36 trimethylation dependent bile acid metabolism

Long-term exposure to arsenic, a common environmental pollutant, can induce various types of liver injury, but the mechanism and treatment measures remain unclear. This study constructed a rat model of arsenic-induced liver injury, with methyl group donor S-adenosylmethionine (SAM) supplementation and Rosa roxburghii Tratt juice intervention, to explore the epigenetic mechanism and intervention method of arsenic-induced liver injury from the perspective of hepatic bile acid metabolism. The results showed that arsenic exposure induced the accumulation of total bile acids (TBA) in the liver and serum of rats, and the abnormalities in liver function and liver histopathology. Arsenic reduced histone H3K36 trimethylation (H3K36me3) in the liver via consuming methyl group donor SAM. The reduction of H3K36me3 was involved in arsenic-induced bile acid accumulation by inhibiting the transcription of negative feedback regulators Fxr and Fgfr4 for hepatic bile acid synthesis. SAM supplementation reversed arsenic-induced bile acid accumulation and liver injury by reactivating H3k36me3-dependent transcription of Fxr and Fgfr4. Moreover, this study found that Rosa roxburghii Tratt juice could rescue arsenic-induced SAM consumption, recover H3K36me3-dependent negative feedback regulation of hepatic bile acid synthesis, and alleviate arsenic-induced bile acid accumulation and liver injury. In conclusion, arsenic exposure perturbed H3K36me3-dependent hepatic bile acid metabolism via depleting SAM, thereby inducing hepatic bile acid accumulation and liver injury, which was ameliorated by the supporting effect of Rosa roxburghii Tratt juice on SAM. This study contributes to understanding the mechanism of arsenic-induced liver injury from the perspective of SAM-dependent epigenetics, providing new insight into its prevention and treatment.