Single-cell map of dynamic cellular microenvironment of radiation-induced intestinal injury.

Intestine is a highly radiation-sensitive organ that could be injured during the radiotherapy for pelvic, abdominal, and retroperitoneal tumors. However, the dynamic change of the intestinal microenvironment related to radiation-induced intestine injury (RIII) is still unclear. Using single-cell RNA sequencing, we pictured a dynamic landscape of the intestinal microenvironment during RIII and regeneration. We showed that the various cell types of intestine exhibited heterogeneous radiosensitivities. We revealed the distinct dynamic patterns of three subtypes of intestinal stem cells (ISCs), and the cellular trajectory analysis suggested a complex interconversion pattern among them. For the immune cells, we found that Ly6c+ monocytes can give rise to both pro-inflammatory macrophages and resident macrophages after RIII. Through cellular communication analysis, we identified a positive feedback loop between the macrophages and endothelial cells, which could amplify the inflammatory response induced by radiation. Besides, we identified different T cell subtypes and revealed their role in immunomodulation during the early stage of RIII through inflammation and defense response relevant signaling pathways. Overall, our study provides a valuable single-cell map of the multicellular dynamics during RIII and regeneration, which may facilitate the understanding of the mechanism of RIII.

Genetic characterization of duck hepatitis B viruses from Anhui Province, China.

Duck hepatitis B virus (DHBV) infection model was frequently used as the experimental model for human hepatitis B virus (HBV) research. In order to decipher the genetic characteristics of DHBVs from Anhui province of China, 120 duck liver tissue samples were collected and subjected to PCR screening, and 28 samples were detected as DHBV positive. Subsequently, five DHBV-positive samples were selected for genome-wide amplification and a comprehensive analysis. Comparative analysis of complete genome sequences using the MegAlign program showed that five strains of DHBVs shared 94.5-96.3% with each other and 93.2-98.7% with other reference strains in GenBank. The phylogenetic analysis showed that all five DHBV strains belonged to the evolutionary branch of "Chinese DHBV" isolates or DHBV-2. Importantly, three potential intra-genotypic recombination events, between strains AAU-6 and Guilin, strains AAU-1 and GD3, and strains AAU-6 and AAU-1, were respectively found using the RDP and SimPlot softwares and considered the first report in avihepadnaviruses. These results not only improve our understanding for molecular prevalence status of DHBV among ducks, but also provide a reference for recombination mechanism of HBV.

PARP1 modulates METTL3 promoter chromatin accessibility and associated LPAR5 RNA m6A methylation to control cancer cell radiosensitivity.

Chromatin remodeling and N6-methyladenosine (m6A) modification are two critical layers in controlling gene expression and DNA damage signaling in most eukaryotic bioprocesses. Here, we report that poly(ADP-ribose) polymerase 1 (PARP1) controls the chromatin accessibility of METTL3 to regulate its transcription and subsequent m6A methylation of poly(A)+ RNA in response to DNA damage induced by radiation. The transcription factors nuclear factor I-C (NFIC) and TATA binding protein (TBP) are dependent on PARP1 to access the METTL3 promoter to activate METTL3 transcription. Upon irradiation or PARP1 inhibitor treatment, PARP1 disassociated from METTL3 promoter chromatin, which resulted in attenuated accessibility of NFIC and TBP and, consequently, suppressed METTL3 expression and RNA m6A methylation. Lysophosphatidic Acid Receptor 5 (LPAR5) mRNA was identified as a target of METTL3, and m6A methylation was located at A1881. The level of m6A methylation of LPAR5 significantly decreased, along with METTL3 depression, in cells after irradiation or PARP1 inhibition. Mutation of the LPAR5 A1881 locus in its 3' UTR results in loss of m6A methylation and, consequently, decreased stability of LPAR5 mRNA. METTL3-targeted small-molecule inhibitors depress murine xenograft tumor growth and exhibit a synergistic effect with radiotherapy in vivo. These findings advance our comprehensive understanding of PARP-related biological roles, which may have implications for developing valuable therapeutic strategies for PARP1 inhibitors in oncology.

Increasing Planting Density and Reducing N Application Improves Yield and Grain Filling at Two Sowing Dates in Double-Cropping Rice Systems.

Grain filling plays an important role in achieving high grain yield. Manipulating planting densities is recognized as a viable approach to compensate for the reduced yield caused by nitrogen reduction. Understanding the effects of nitrogen fertilization and planting density on superior and inferior grain filling is crucial to ensure grain security. Hence, double-cropping paddy field trials were conducted to investigate the effect of three nitrogen levels (N1, conventional nitrogen application; N2, 10% nitrogen reduction; N3, 20% nitrogen reduction) and three planting densities (D1, conventional planting density; D2, 20% density increase; D3, 40% density increase) on grain yield, yield formation, and grain-filling characteristics at two sowing dates (S1, a conventional sowing date, and S2, a date postponed by ten days) in 2019-2020. The results revealed that the annual yield of S1 was 8.5-14% higher than that of S2. Reducing nitrogen from N2 to N3 decreased the annual yield by 2.8-7.6%, but increasing planting densities from D1 to D3 significantly improved yield, by 6.2-19.4%. Furthermore, N2D3 had the highest yield, which was 8.7-23.8% higher than the plants that had received the other treatments. The rice yield increase was attributed to higher numbers of panicles per m2 and spikelets per panicle on the primary branches, influenced by superior grain filling. Increasing planting density and reducing nitrogen application significantly affected grain-filling weight, with the 40% density increase significantly facilitating superior and inferior grain filling with the same nitrogen level. Increasing density can improve superior grains while reducing nitrogen will decrease superior grains. These results suggest that N2D3 is an optimal strategy to increase yield and grain filling for double-cropping rice grown under two sowing-date conditions.

Effects of Nonthermal Radiofrequency Stimulation on Neuronal Activity and Neural Circuit in Mice.

Whether the nonthermal effects of radiofrequency radiation (RFR) exist and how nonthermal RFR acts on the nervous system are unknown. An animal model of spatial memory impairment is established by exposing mice to 2856-MHz RFR in the range of thermal noise (≤1 °C). Glutamate release in the dorsal hippocampus (dHPC) CA1 region is not significantly changed after radiofrequency exposure, whereas dopamine release is reduced. Importantly, RFR enhances glutamatergic CA1 pyramidal neuron calcium activity by nonthermal mechanisms, which recover to the basal level with RFR termination. Furthermore, suppressed dHPC dopamine release induced by radiofrequency exposure is due to decreased density of dopaminergic projections from the locus coeruleus to dHPC, and artificial activation of dopamine axon terminals or D1 receptors in dHPC CA1 improve memory damage in mice exposed to RFR. These findings indicate that nonthermal radiofrequency stimulation modulates ongoing neuronal activity and affects nervous system function at the neural circuit level.

High-Power Electromagnetic Pulse Exposure of Healthy Mice: Assessment of Effects on Mice Cognitions, Neuronal Activities, and Hippocampal Structures.

Electromagnetic pulse (EMP) is a high-energy pulse with an extremely rapid rise time and a broad bandwidth. The brain is a target organ sensitive to electromagnetic radiation (EMR), the biological effects and related mechanisms of EMPs on the brain remain unclear. The objectives of the study were to assess the effects of EMP exposure on mouse cognitions, and the neuronal calcium activities in vivo under different cases of real-time exposure and post exposure. EMP-treated animal model was established by exposing male adult C57BL/6N mice to 300 kV/m EMPs. First, the effects of EMPs on the cognitions, including the spatial learning and memory, avoidance learning and memory, novelty-seeking behavior, and anxiety, were assessed by multiple behavioral experiments. Then, the changes in the neuronal activities of the hippocampal CA1 area in vivo were detected by fiber photometry in both cases of during real-time EMP radiation and post-exposure. Finally, the structures of neurons in hippocampi were observed by optical microscope and transmission electron microscope. We found that EMPs under this condition caused a decline in the spatial learning and memory ability in mice, but no effects on the avoidance learning and memory, novelty-seeking behavior, and anxiety. The neuron activities of hippocampal CA1 were disturbed by EMP exposure, which were inhibited during EMP exposure, but activated immediately after exposure end. Additionally, the CA1 neuron activities, when mice entered the central area in an Open field (OF) test or explored the novelty in a Novel object exploration (NOE) test, were inhibited on day 1 and day 7 after radiation. Besides, damaged structures in hippocampal neurons were observed after EMP radiation. In conclusion, EMP radiation impaired the spatial learning and memory ability and disturbed the neuronal activities in hippocampal CA1 in mice.

A Study on the Radiosensitivity of Radiation-Induced Lung Injury at the Acute Phase Based on Single-Cell Transcriptomics.

Background and Aims: Radiation-induced lung injury (RILI) is the most common complication associated with chest tumors, such as lung and breast cancers, after radiotherapy; however, the pathogenic mechanisms are unclear. Single-cell RNA sequencing has laid the foundation for studying RILI at the cellular microenvironmental level. This study focused on changes during the acute pneumonitis stage of RILI at the cellular microenvironmental level and investigated the interactions between different cell types. Methods: An acute RILI model in mice and a single-cell transcriptional library were established. Intercellular communication networks were constructed to study the heterogeneity and intercellular interactions among different cell types. Results: A single-cell transcriptome map was established in a mouse model of acute lung injury. In total, 18,500 single-cell transcripts were generated, and 10 major cell types were identified. The heterogeneity and radiosensitivity of each cell type or subtype in the lung tissues during the acute stage were revealed. It was found that immune cells had higher radiosensitivity than stromal cells. Immune cells were highly heterogeneous in terms of radiosensitivity, while some immune cells had the characteristics of radiation resistance. Two groups of radiation-induced Cd8+Mki67+ T cells and Cd4+Cxcr6+ helper T cells were identified. The presence of these cells was verified using immunofluorescence. The ligand-receptor interactions were analyzed by constructing intercellular communication networks. These explained the origins of the cells and revealed that they had been recruited from endothelial cells to the inflammatory site. Conclusions: This study revealed the heterogeneity of in vivo radiosensitivity of different cell types in the lung at the initial stage post irradiation.

Single-Cell RNA Sequencing for Analyzing the Intestinal Tract in Healthy and Diseased Individuals.

The intestinal tract is composed of different cell lineages with distinct functions and gene expression profiles, providing uptake of nutrients and protection against insults to the gut lumen. Changes in or damage to the cellulosity or local environment of the intestinal tract can cause various diseases. Single-cell RNA sequencing (scRNA-seq) is a powerful tool for profiling and analyzing individual cell data, making it possible to resolve rare and intermediate cell states that are hardly observed at the bulk level. In this review, we discuss the application of intestinal tract scRNA-seq in identifying novel cell subtypes and states, targets, and explaining the molecular mechanisms involved in intestinal diseases. Finally, we provide future perspectives on using single-cell techniques to discover molecular and cellular targets and biomarkers as a new approach for developing novel therapeutics for intestinal diseases.

Comprehensive characterization of CRC with germline mutations reveals a distinct somatic mutational landscape and elevated cancer risk in the Chinese population.

OBJECTIVE: Hereditary colorectal cancer (CRC) accounts for approximately 5%-10% of all CRC cases. The full profile of CRC-related germline mutations and the corresponding somatic mutational profile have not been fully determined in the Chinese population. METHODS: We performed the first population study investigating the germline mutation status in more than 1,000 (n = 1,923) Chinese patients with CRC and examined their relationship with the somatic mutational landscape. Germline alterations were examined with a 58-gene next-generation sequencing panel, and somatic alterations were examined with a 605-gene panel. RESULTS: A total of 92 pathogenic (P) mutations were identified in 85 patients, and 81 likely pathogenic (LP) germline mutations were identified in 62 patients, accounting for 7.6% (147/1,923) of all patients. MSH2 and APC was the most mutated gene in the Lynch syndrome and non-Lynch syndrome groups, respectively. Patients with P/LP mutations had a significantly higher ratio of microsatellite instability, highly deficient mismatch repair, family history of CRC, and lower age. The somatic mutational landscape revealed a significantly higher mutational frequency in the P group and a trend toward higher copy number variations in the non-P group. The Lynch syndrome group had a significantly higher mutational frequency and tumor mutational burden than the non-Lynch syndrome group. Clustering analysis revealed that the Notch signaling pathway was uniquely clustered in the Lynch syndrome group, and the MAPK and cAMP signaling pathways were uniquely clustered in the non-Lynch syndrome group. Population risk analysis indicated that the overall odds ratio was 11.13 (95% CI: 8.289-15.44) for the P group and 20.68 (95% CI: 12.89-33.18) for the LP group. CONCLUSIONS: Distinct features were revealed in Chinese patients with CRC with germline mutations. The Notch signaling pathway was uniquely clustered in the Lynch syndrome group, and the MAPK and cAMP signaling pathways were uniquely clustered in the non-Lynch syndrome group. Patients with P/LP germline mutations exhibited higher CRC risk.

Intra-Tumor Heterogeneity of Colorectal Cancer Necessitates the Multi-Regional Sequencing for Comprehensive Mutational Profiling.

BACKGROUND: The panorama and details of quantitative intratumor heterogeneity have not been fully investigated in colorectal cancer (CRC) patients with solitary lesion without distal metastasis, and its influences on sequencing interpretation and therapeutic strategies have not been explored. METHODS: Cancer tissues and matched blood from 70 sporadic CRC patients were collected and were divided into two cohorts. Four individual tissue biopsies were obtained from each of the 47 patients (multi-sample cohort). One random cancer tissue biopsy was obtained from each of the rest 23 patients (single-sample cohort). A 10 mL of blood was collected from all patients and the circulating cell-free DNA (cfDNA) was extracted. A 605-gene panel was used for targeted sequencing with tissue and paired blood. RESULTS: Mutational landscape revealed significantly higher mutational frequency in APC, CARD11 and CSMD3 in multi-sample cohort than single-sample cohort (P<0.05). The number of mutations and the ratio of trunk, shared and branch mutations showed extensive heterogeneity in multi-sample cohort, and the percentage of trunk mutations in major driver genes, including APC, TP53 and KRAS, was higher than 70%. A total of 929 mutations were detected in tissue/blood in multi-sample group, with 921(99.1%) from tissue and 472(50.8%) from blood (464 common mutations,49.9%). In contrast, 394 mutations were detected in tissue/blood in single-sample group, with 231 (58.6%) from tissue and 219 (55.6%) from blood (56 common mutations, 11.9%). The number of mutations of major driver genes detected in tissue was higher than that in blood in the multi-sample cohort, while it was similar in the single-sample group. Quantification analysis revealed differential correlation between tissue and blood VAF in trunk, shared and branch mutations. Meanwhile, VAF of trunk mutations was significantly higher than shared mutations and branch mutations. VAF exhibited significant differences among distinct stages, locations, differentiation and sex status. CONCLUSION: Characteristic extensive heterogeneity was revealed for solitary CRC without distal metastasis. Multi-regional biopsy was necessary for comprehensive mutation detection in CRC.

Establishment of hydrolysis probe system real-time PCR assay for rapid detection of canine circovirus.

In the study, we established a hydrolysis probe-based real-time polymerase chain reaction (PCR) assay to rapidly detect Canine circovirus (CanineCV) DNA in faecal samples. We designed a pair of specific primers and one probe targeting Rep in CanineCV, and sensitivity, specificity, and repeatability tests were performed to evaluate the efficacy of the assay. The assay showed high sensitivity and a minimum detection limit of 8.42 × 101 copies/µL, which is 1000-fold more sensitive compared to traditional PCR. The method was also highly specific, without cross-reaction with other common canine viruses. Moreover, the assay showed high repeatability, and the mean intra-assay and inter-assay coefficients of variation were 0.26 and 0.36%, respectively. The results of the detection of clinical samples showed that the positive detection rate of CanineCV was 14.04% (8/57). Notably, 8% of clinical samples were co-infected with other canine pathogens. In conclusion, the establishment of a hydrolysis probe-based real-time PCR method provides a fast, sensitive, specific, reliable, and repeatable method for CanineCV detection. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-03031-z.

Hydrogen regulates the M1/M2 polarization of alveolar macrophages in a rat model of chronic obstructive pulmonary disease.

OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a respiratory disease with high morbidity and mortality worldwide, so far there is no ideal treatment method. Previous studies have shown that hydrogen (H2) is involved in the treatment of COPD as an antioxidant. In this study, the effect of H2 on M1/M2 polarization of alveolar macrophages in COPD rats was observed, and its anti-inflammatory mechanism was further elucidated. Methods: Twenty-four Sprague-Dawley rats were randomly divided into three groups including the control, COPD and H2 group. A rat model of COPD was established by cigarette exposure combined with lipopolysaccharide (LPS) induction. H2 therapy was administered 2 hours per day for 14 days. Lung function and pathology were assessed. The levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-ß1 and IL-10 in bronchoalveolar lavage fluid (BALF) and lung tissue were measured by enzyme-linked immunosorbent assay. The mRNA, protein expression and immunoreactivity of inducible nitric oxide synthase (iNOS) and arginase (Arg)-1 in lung were observed by quantitative real-time PCR, western blot and immunohistochemistry. Results: Compared with the control rats, there were a significant decline in lung function, a marked inflammatory infiltration and pulmonary parenchymal remodeling and the increases of IL-6, TNF-α and TGF-ß1 levels in BALF and lung tissue, but a lower expression of IL-10 in COPD rats. The iNOS mRNA and protein expression, as well as its optical density (OD), were increased significantly in lung tissue, while those of Arg-1 decreased significantly. H2 treatment improved the lung function and the parenchymal inflammation, reversed the increased levels of IL-6, TNF-α and TGF-ß1, and the lower IL-10. Meanwhile, H2 also down-regulated the expression of iNOS, but up-regulated expression of Arg-1 in lung tissue. Conclusion: H2 reduces inflammation in the lung of COPD, which may be related to its inhibition of M1 type polarization and activation of M2 type polarization of alveolar macrophage.

Progress on the Function and Application of Thymosin ß4.

Thymosin ß4 (Tß4) is a multifunctional and widely distributed peptide that plays a pivotal role in several physiological and pathological processes in the body, namely, increasing angiogenesis and proliferation and inhibiting apoptosis and inflammation. Moreover, Tß4 is effectively utilized for several indications in animal experiments or clinical trials, such as myocardial infarction and myocardial ischemia-reperfusion injury, xerophthalmia, liver and renal fibrosis, ulcerative colitis and colon cancer, and skin trauma. Recent studies have reported the potential application of Tß4 and its underlying mechanisms. The present study reveals the progress regarding functions and applications of Tß4.

mmu-miR-145a-5p Accelerates Diabetic Wound Healing by Promoting Macrophage Polarization Toward the M2 Phenotype.

Diabetic wounds are recalcitrant to healing. One of the important characteristics of diabetic trauma is impaired macrophage polarization with an excessive inflammatory response. Many studies have described the important regulatory roles of microRNAs (miRNAs) in macrophage differentiation and polarization. However, the differentially expressed miRNAs involved in wound healing and their effects on diabetic wounds remain to be further explored. In this study, we first identified differentially expressed miRNAs in the inflammation, tissue formation and reconstruction phases in wound healing using Illumina sequencing and RT-qPCR techniques. Thereafter, the expression of musculus (mmu)-miR-145a-5p ("miR-145a-5p" for short) in excisional wounds of diabetic mice was identified. Finally, expression of miR-145a-5p was measured to determine its effects on macrophage polarization in murine RAW 264.7 macrophage cells and wound healing in diabetic mice. We identified differentially expressed miRNAs at different stages of wound healing, ten of which were further confirmed by RT-qPCR. Expression of miR-145a-5p in diabetic wounds was downregulated during the tissue formation stage. Furthermore, we observed that miR-145a-5p blocked M1 macrophage polarization while promoting M2 phenotype activation in vitro. Administration of miR-145a-5p mimics during initiation of the repair phase significantly accelerated wound healing in db/db diabetic mice. In conclusion, our findings suggest that rectifying macrophage function using miR-145a-5p overexpression accelerates diabetic chronic wound healing.