Long non-coding RNAs mediate the association between short-term PM2.5 exposure and circulating biomarkers of systemic inflammation

Although short-term fine particulate matter (PM2.5) exposure is associated with systemic inflammation, the effect of lncRNA on these association remains unknown. This study aims to investigate whether the plasma lncRNA mediate the effect of short-term PM2.5 exposure on systemic inflammation. In this cross-sectional study, plasma Clara cell protein 16 (CC16), interleukin 6 (IL-6), IL-8, tumor necrosis factor-α (TNF-α) and lncRNA expression levels were measured in 161 adults between March and April in 2018 in Shijiazhuang, China. PM2.5 concentrations were estimated 0-3 days prior to the examination date and the moving averages were calculated. Multiple linear regressions were used to evaluate the associations between PM2.5, the four biomarkers and lncRNA expression levels. Mediation analyses were performed to explore the potential roles of lncRNA expression in these associations. The median concentration of PM2.5 ranged from 39.65 to 60.91 mg/m3 across different lag days. The most significant effects on IL-6 and TNF-α per interquartile range increase in PM2.5 were observed at lag 0-3 days, with increases of 0.70 pg/mL (95% CI: 0.33, 1.07) and 0.21 pg/mL (95% CI: 0.06, 0.36), respectively. While the associations between PM2.5 and IL-8 (0.68 pg/mL, 95% CI: 0.34, 1.02) and CC16 (3.86 ng/mL, 95% CI: 1.60, 6.13) were stronger at lag 0 day. Interestingly, a negative association between PM2.5 and the expression of four novel lncRNAs (lnc-ACAD11-1:1, lnc-PRICKLE1-4:1, lnc-GPR39-7:2, and lnc-MTRNR2L12-3:6) were observed at each lag days. Furthermore, these lncRNAs mediated the effects of PM2.5 on the four biomarkers, with proportions of mediation ranged from 2.27% (95% CI: 1.19%, 9.82%) for CC16 to 35.60% (95% CI: 17.16%, 175.45%) for IL-6. Our findings suggested that plasma lncRNA expression mediat the acute effects of PM2.5 exposure on systematic inflammation. These highlight a need to consider circulating lncRNA expression as biomarkers to reduce health risks associated with PM2.5.

Assessment of microRNA profiles in small extracellular vesicles isolated from bovine colostrum with different immunoglobulin G concentrations

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The RNA concentration in sEV isolated from bovine colostrum was highest using the combination of the miRCURY Cell/Urine/CSF and miRNeasy Mini kits.

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The top 50 miRNA were the same using miRDeep2 and sRNAbench, predominated by let-7b, let-7a-5p, miR-30a-5p, and miR-148a.

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Predicted target genes of the top 50 miRNA regulate PI3K-Akt and MAPK signaling pathways, axon guidance, and focal adhesion.

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The abundance of miR-27a-3p was higher in colostrum with high IgG concentrations.

The consumption of bovine colostrum by newborn calves during the first days of life is essential to ensure the transfer of passive immunity. In addition to critical IgG, colostrum also contains non-IgG biomolecules, including microRNA (miRNA). The present study investigated the profiles of miRNA in small extracellular vesicles (sEV) isolated from bovine colostrum with high (256.5 ± 5.7 mg/mL, mean ± standard deviation, n = 4) and low (62.8 ± 3.6 mg/mL, n = 4) concentrations of IgG. Different combination of sEV extraction methods and bioinformatic pipelines (miRDeep2 and sRNAbench) for miRNA analysis were evaluated. Results showed that miRCURY exosome Cell/Urine/CSF and miRNeasy Mini kits yielded the highest RNA concentration. The miRNA-seq data analysis showed miRDeep2 yielded more comprehensive miRNAome compared with sRNAbench (527 versus 392 unique miRNA), whereas 389 shared miRNA were identified using both approaches. The profiles of top 50 miRNA were the same using both approaches, and their abundance contributed to 91.7% and 94.3% of total abundance of miRNA using miRDeep2 and sRNAbennch, respectively. These core miRNA were predicted to target 2,655 genes, which regulate 78 KEGG (Kyoto Encyclopedia of Genes and Genomes) level-3 pathways including PI3K-Akt and MAPK signaling pathway, axon guidance, and focal adhesion. The expression profiles of sEV-associated miRNA were similar between high- and low-IgG colostrum samples, despite the fact that the abundance of miR-27a-3p was higher in colostrum with high concentrations of IgG. In conclusion, a core miRNAome in bovine colostrum may play a role in regulating health and developmental stages in neonatal calves, independent of IgG concentration.

The involvement of copper, circular RNAs, and inflammatory cytokines in chronic respiratory disease

Exposure to high concentrations of copper is associated with pulmonary inflammation and chronic respiratory disease (CRD). Epigenetic modulation of noncoding RNAs contributes to the development of several CRDs. It is unknown whether epigenetic modulation is involved in copper mediated pulmonary inflammation and CRD. We conducted a case-control study of 101 CRD cases and 161 control subjects in Shijiazhuang, China, and evaluated circRNAs and cytokine levels (IL-6 and IL-8) by qPCR and ELISA. Urinary copper concentration was determined by inductively coupled plasma mass spectrometry. Linear mixed models and generalized linear mixed models were used to assess the associations of circRNAs with CRD, urinary copper, and cytokines. We exposed the human bronchial epithelial cell line, 16HBE, to copper and assessed the functional role of a circRNA, circ_0008882, by RNA overexpression. Cellular location of circ_0008882 was assessed by separation of nuclear and cytoplasmic RNAs. Nine circRNAs were associated with an increased risk for CRDs, while the relative expression of circ_0008882 was decreased after copper exposure in vitro and in vivo. Copper exposure stimulated 16HBE cells to release proinflammatory IL-6 and IL-8. The release of the cytokines was inhibited by overexpression of circ_0008882. These results suggest a role for circ_0008882 in the regulation of CRD associated inflammation following copper exposure.

Upregulation of circ_0035266 contributes to the malignant progression of inflammation-associated malignant transformed cells induced by tobacco-specific carcinogen NNK

Cigarette smoking-induced chronic inflammation has been considered a vital driver of lung tumorigenesis. The compounds 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific carcinogen, and lipopolysaccharide (LPS), an inflammatory inducer, are important components of tobacco smoke which have been implicated in inflammation-driven carcinogenesis. However, the biological effects and underlying mechanisms of LPS-mediated inflammation on NNK-induced tumorigenesis are still unclear. In this study, BEAS-2B human bronchial epithelial cells were exposed to NNK, LPS or both, for short- or long-term periods. We found that acute LPS exposure promoted the secretion of granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin (IL)-6 in NNK-treated BEAS-2B cells. In addition, chronic LPS exposure facilitated the NNK-induced malignant transformation process by promoting cell proliferation, cell cycle alteration, migration and clonal formation. Previously, we determined that circular RNA circ_0035266 enhanced cellular inflammation in response to NNK+LPS by sponging miR-181d-5p and regulating expression of its downstream target DEAD-Box Helicase 3 X-Linked (DDX3X). Here, we found that knockdown of circ_0035266 or DDX3X led to a remarkable inhibition of the proliferation, cell cycle progression and migration of NNK+LPS-transformed BEAS-2B cells, while overexpression of these genes produced the opposite effects, indicating the oncogenic roles of circ_0035266 and DDX3X in the malignant progression of chronic inflammation-driven malignant transformed cells. Moreover, the regulatory relationships among circ_0035266, miR-181d-5p and DDX3X were further confirmed using a group of lung cancer tissues. Conclusively, our findings provide novel insights into our understanding of inflammation-driven tumorigenesis using a cellular malignant transformation model, and indicate a novel tumor-promoting role for circ_0035266 in chemical carcinogenesis.

Circular RNA circNIPBL promotes NNK-induced DNA damage in bronchial epithelial cells via the base excision repair pathway

Environmental chemical exposure often causes DNA damage, which leads to cellular dysfunction and the development of diseases. 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific carcinogen that is known to cause DNA damage, while remains unknown about the underlying mechanism. In this study, simulated doses of NNK exposure in smokers, ranging from 50 to 300 μM, were used to detect the DNA damage effects of NNK in two human bronchial epithelial cells, 16HBE and BEAS-2B. The comet assay revealed increased DNA damage in response to NNK treatment, as measured by increased Olive tail moment (OTM). NNK treatment also led to elevated foci formation and protein expression of γ-H2AX, a DNA damage sensor. Dysregulation of proliferation, cell cycle arrest and apoptosis, was also observed in NNK-treated cells. Furthermore, the most effective dose of NNK (300 μM) was used in subsequent mechanistic studies. A circular RNA circNIPBL was identified to be significantly up-regulated in NNK-treated cells, circNIPBL knockdown successfully alleviated NNK-induced DNA damage and reversed the cellular dysregulation, while circNIPBL overexpression had the opposite effect. Mechanistically, we identified an interaction between circNIPBL and PARP1, a critical enzyme of the base excision repair (BER) pathway. CircNIPBL silencing successfully alleviated the NNK-induced inhibition of BER pathway proteins, including PARP1, XRCC1, PCNA and FEN1, while overexpression of circNIPBL had the opposite effect. In summary, our study shows for the first time that circNIPBL promotes NNK-induced DNA damage and cellular dysfunction through the BER pathway. In addition, our findings reveal the crucial role of epigenetic regulation in carcinogen-induced genetic lesions and further our understanding of environmental carcinogenesis.

Circular RNA circ_Cabin1 promotes DNA damage in multiple mouse organs via inhibition of non-homologous end-joining repair upon PM2.5 exposure

Fine particulate matter (PM_2.5) has been shown to induce DNA damage. Circular RNAs (circRNAs) have been implicated in various disease processes related to environmental chemical exposure. However, the role of circRNAs in the regulation of DNA damage response (DDR) after PM_2.5 exposure remains unclear. In this study, male ICR mice were exposed to PM_2.5 at a daily mean concentration of 382.18 μg/m³ for 3 months in an enriched-ambient PM_2.5 exposure system in Shijiazhuang, China, and PM_2.5 collected form Shijiazhuang was applied to RAW264.7 cells at 100 µg/mL for 48 h. The results indicated that exposure to PM_2.5 induced histopathological changes and DNA damage in the lung, kidney and spleen of male ICR mice, and led to decreased cell viability, increased LDH activity and DNA damage in RAW264.7 cells. Furthermore, circ_Cabin1 expression was significantly upregulated in multiple mouse organs as well as in RAW264.7 cells upon exposure to PM_2.5. PM_2.5 exposure also resulted in impairment of non-homologous end joining (NHEJ) repair via the downregulation of Lig4 or Dclre1c expression in vivo and in vitro. Importantly, circ_Cabin1 promoted PM_2.5-induced DNA damage via inhibiting of NHEJ repair. Moreover, the expression of circ_Cabin1 and Lig4 or Dclre1c was strongly correlated in multiple mouse organs, as well as in the blood. In summary, our study provides a new perspective on circRNAs in the regulation of DDR after environmental chemical exposure.

Tobacco-Related Exposure Upregulates Circ_0035266 to Exacerbate Inflammatory Responses in Human Bronchial Epithelial Cells

One of the most carcinogenic chemicals found in cigarette tobacco smoke is 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which has been confirmed to be associated with the etiology of diverse cancers. Lipopolysaccharide (LPS), another biologically active component of cigarette smoke, is a risk factor which enhances NNK-induced lung tumorigenesis due to chronic lung inflammation. Although inflammatory responses play critical roles in the initiation of many tumors, our knowledge about the mechanisms of NNK+LPS on inflammation is currently limited. Here, we investigated the inflammatory effects of NNK+LPS in human bronchial epithelial cells (BEAS-2B) and explored the underlying mechanisms mediated by circular RNAs (circRNAs). We identified a novel circRNA, circ_0035266, which was strongly upregulated in NNK+LPS-induced BEAS-2B cells and enhanced the inflammatory responses to NNK+LPS by regulating the secretion of pro-inflammatory cytokines interleukin (IL)-6 and IL-8. Specifically, circ_0035266 knockdown alleviated NNK+LPS-induced inflammatory responses, whereas overexpression of circ_0035266 had the opposite effect. Moreover, dual-luciferase reporter and fluorescence in situ hybridization (FISH) assays verified that circ_0035266 bound to miR-181d-5p directly in the cytoplasm. qRT-PCR, dual-luciferase reporter assays, and Western blot analyses showed that DDX3X (DDX3) was the downstream target of miR-181d-5p and that DDX3X expression levels were modulated by circ_0035266. These results suggested that circ_0035266 served as a competitive endogenous RNA for miR-181d-5p to regulate DDX3X expression, which is involved in the modulation of NNK+LPS-induced inflammatory responses in BEAS-2B cells.

Circular RNA circBbs9 promotes PM2.5-induced lung inflammation in mice via NLRP3 inflammasome activation

Fine particulate matter (PM_2.5) is one of the most important components of environmental pollutants, and is associated with pulmonary injury. However, the biological mechanisms of pulmonary damage caused by PM_2.5 are poorly defined, especially the molecular pathways related to inflammation. Following system exposure to PM_2.5 for 3 months in normal mice and in chronic obstructive pulmonary disease (COPD) model mice, it was found that PM_2.5 exposure increased the expression of IL-1β and IL-18 in lung tissues via NLRP3 activation, and these effects were more intense in COPD model mice. Circular RNA (circRNA) sequencing showed that the expression profiles of circRNAs were changed after PM_2.5 exposure, and the positive roles of circBbs9 in inflammation induced by PM_2.5 were verified. The circBbs9 knockdown alleviated PM_2.5-induced inflammation via NLRP3 inflammasome inactivation, as well as IL-1β and IL-18 inhibition in RAW264.7 cells, while overexpression of circBbs9 had the opposite effect. Bioinformatics and luciferase reporter assays showed that circBbs9 bound to microRNA-30e-5p (miR-30e-5p) and co-regulated the expression of Adar, a downstream target gene of miR-30e-5p. Taken together, these results revealed that PM_2.5 induced pulmonary inflammation through NLRP3 inflammasome activation regulated by the circBbs9-miR-30e-5p-Adar pathway. Our findings provide a new target, circBbs9, for the assessment of lung inflammation and COPD exacerbation induced by PM_2.5 exposure.

Resveratrol affects in vitro rumen fermentation, methane production and prokaryotic community composition in a time- and diet-specific manner

This study aimed to investigate the effect of resveratrol on methane production, rumen fermentation and microbial composition under high-concentrate (HC) and high-forage (HF) diets using the in vitro fermentation system. A total of 25 mg of resveratrol was supplemented into 300 mg of either HC or HF diet. Methane production, total volatile fatty acid (VFA) concentration, molar proportion of VFA, metabolites of resveratrol and prokaryotic community composition were measured after 12 and 24 h of in vitro fermentation. Resveratrol reduced methane production (ml per mg of dry matter degraded) by 41% and 60% under both HC and HF diets (P < 0.001), respectively, and this result could be associated with the lower abundance of Methanobrevibacter (P < 0.001) in response to resveratrol. The molar proportion of propionate was significantly higher in the resveratrol group only under the HC diet (P = 0.045). The relative abundance of 10 bacterial genera was affected by the three-way interaction of treatment, diet and time (P < 0.05). Resveratrol was partly converted to dihydroresveratrol after 24 h of fermentation, and its degradation could be associated with microbes belonging to the order Coriobacteriales. Our results suggest that multiple factors (e.g. diet and time) should be considered in animal experiments to test the effect of polyphenol or other plant extracts on rumen fermentation, methane emission and microbial composition.

Safety, feasibility, and effect of an enhanced nutritional support pathway including extended preoperative and home enteral nutrition in patients undergoing enhanced recovery after esophagectomy: a pilot randomized clinical trial

The aims of this pilot study are to evaluate the feasibility, safety, and effectiveness of conducting an enhanced nutritional support pathway including extended preoperative nutritional support and one month home enteral nutrition (HEN) for patients who underwent enhanced recovery after esophagectomy. We implemented extended preoperative nutritional support and one month HEN after discharge for patients randomized into an enhanced nutrition group and implemented standard nutritional support for patients randomized into a conventional nutrition group. Except the nutritional support program, both group patients underwent the same standardized enhanced recovery after surgery programs of esophagectomy based on published guidelines. Patients were assessed at preoperative day, postoperative day 7 (POD7), and POD30 for perioperative outcomes and nutritional status. To facilitate the determination of an effect size for subsequent appropriately powered randomized clinical trials and assess the effectiveness, the primary outcome we chose was the weight change before and after esophagectomy. Other outcomes including body mass index (BMI), lean body mass (LBM), appendicular skeletal muscle mass index (ASMI), nutrition-related complications, and quality of life (QoL) were also analyzed. The intention-to-treat analysis of the 50 randomized patients showed that there was no significant difference in baseline characteristics. The weight (-2.03 ± 2.28 kg vs. -4.05 ± 3.13 kg, P = 0.012), BMI (-0.73 ± 0.79 kg/m2 vs. -1.48 ± 1.11 kg/m2, P = 0.008), and ASMI (-1.10 ± 0.37 kg/m2 vs. -1.60 ± 0.66 kg/m2, P = 0.010) loss of patients in the enhanced nutrition group were obviously decreased compared to the conventional nutrition group at POD30. In particular, LBM (48.90 ± 9.69 kg vs. 41.96 ± 9.37 kg, p = 0.031) and ASMI (7.56 ± 1.07 kg/m2 vs. 6.50 ± 0.97 kg/m2, P = 0.003) in the enhanced nutrition group were significantly higher compared to the conventional nutrition group at POD30, despite no significant change between pre- and postoperation. In addition, European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 scores revealed that enhanced nutritional support improved the QoL of patients in physical function (75.13 ± 9.72 vs. 68.33 ± 7.68, P = 0.009) and fatigue symptom (42.27 ± 9.93 vs. 49.07 ± 11.33, P = 0.028) compared to conventional nutritional support. This pilot study demonstrated that an enhanced nutritional support pathway including extended preoperative nutritional support and HEN was feasible, safe, and might be beneficial to patients who underwent enhanced recovery after esophagectomy. An appropriately powered trial is warranted to confirm the efficacy of this approach.