Global research trends on the links between gut microbiota and cancer immunotherapy: A bibliometric analysis (2012-2021).

Background: There is a crosstalk between gut microbiota (GM) and cancer immunotherapy (CI). The purpose of this study is to use bibliometric analysis to identify the highly cited papers relating to GM/CI and explore the research status and development trends of the GM/CI research. Methods: A literature search regarding GM/CI publications from 2012 to 2021 was undertaken on July 4, 2022. The article titles, journals, authors, institutions, countries, total citations, keywords, and other information were extracted from the Science Citation Index Expanded (SCIE) of Web of Science Core Collection (WoSCC). The Bibliometrix of R package and VOSviewer were used for bibliometric analysis. Results: A total of 665 papers were extracted. The number of papers has increased rapidly over the past decade, especially after 2018. The United States and China had the most publications and made great contributions to this field. Th5e Univ Texas MD Anderson Canc Ctr and Univ Paris Saclay were absolutely in the leading position in GM/CI. The most influential authors were Zitvogel L and Routy B. Frontiers in Immunology had the most publications and Science had the most total citations. Historical direct citation analysis explained the historical evolution in GM/CI. Highly cited papers and high-frequency keywords illustrated the current status and trends of GM/CI. Four clusters were identified and the important topics included the role of GM and antibiotics in CI, the methods of targeting GM to improve CI outcomes, the mechanism by which GM affects CI and the application of ICIs in melanoma. "Tumor microbiome", "proton pump inhibitors" and "prognosis" may be the new focus of attention in the next few years. Conclusion: This study filtered global publications on GM/CI correlation and analyzed their bibliometric characteristics, identified the most cited papers in GM/CI, and gained insight into the status, hotspots and trends of global GM/CI research, which may inform researchers and practitioners of future directions.

Response of soil microbial community to plant composition changes in broad-leaved forests of the karst area in Mid-Subtropical China.

The rapid growth and expansion ofCryptomeria japonica (Thunb. ex L. f.) D. Don in karst area strongly affects plant composition of native deciduous broad-leaved forest, which seriously threat ecosystem function and service. Given the importance of soil microorganisms in regulating nutrients cycling and plant species coexistence, understanding soil microbial attributes and their relationships with soil and vegetation features in forests harboring different C. japonica abundance will help understanding the drivers of ecosystem function changes. Here we examined the diversity and composition of soil bacterial and fungal communities and their correlations with plant diversity as well as soil physicochemical properties in karst broad-leaved forests with different relative abundances of C. japonica (i.e., a high, moderate, low and no proportion level with a stem density of 1,487, 538, 156 and 0 plant/hm2, respectively) in Mid-Subtropical China. We found that soil pH decreased while soil water content (SWC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) tended to increase with the increase in C. japonica abundance. In contrast, soil available nitrogen (AN), available phosphorus (AP) and available potassium (AK) content declined by 26.1%∼49.3% under the high level of C. japonica abundance. A gradual decrease in relative abundance of Acidobacteria and Chloroflexi while a pronounced increase in relative abundance of Ascomycota and Basidiomycota were observed with increase of C. japonica abundance. Alternations in bacterial composition were closely related to changes in AP and AK, while the change of fungal structure was mainly related to SWC, soil organic carbon (SOC) and pH, indicating that bacterial community was sensitive to declines in soil available nutrients and fungal structure was sensitive to changes in soil physicochemical properties (i.e., pH and SWC) and organic carbon resource. Understory plants had the highest α-diversity in forest containing moderate abundance of C. japonica, which might be related to the high bacterial diversity. Our findings suggest conservation of soil bacterial and fungal taxa that are responsible for nutrients availability and carbon sequestration is of great significance for improving the resistance of natural deciduous broad-leaved forests to the rapid spread of C. japonica in karst areas. Moreover, Acidobacteria, Chloroflexi, Ascomycota and Basidiomycota are potential indicators for soil properties changes, which should be taken into consideration in karst forest managements.

Risk Factors and a New Prediction Model for Pancreatic Fistula After Pancreaticoduodenectomy.

AIM: In order to find the risk factors of postoperative pancreatic fistula (POPF) after pancreaticoduodenectomy (PD) according to the latest definition and grading system of International Study Group of Pancreatic Surgery (ISGPS) (version 2016) and propose a nomogram for predicting POPF. METHODS: We conducted a retrospective analysis of 232 successive cases of PD performed at our hospital by the same operator from August 2012 to June 2020. POPF was diagnosed in accordance with the latest definition of pancreatic fistula from the ISGPS. The risk factors of POPF were analyzed by univariate and multivariate logistic regression analysis. A nomogram model to predict the risk of POPF was constructed based on significant factors. RESULTS: There were 18 cases of POPF, accounting for 7.8% of the total. Among them, 17 cases were classified into ISGPF grade B and 1 case was classified into ISGPF grade C. In addition, 35 cases were classified into biochemical leak. Univariate and multivariate analysis showed that hypertension, non-diabetes, no history of abdominal surgery, antecolic gastrojejunostomy and soft pancreas were independent risk factors of POPF. Based on significant factors, a nomogram is plotted to predict the risk of POPF. The C-index of this nomogram to assess prediction accuracy was 0.916 (P < 0.001) indicating good prediction performance. CONCLUSION: Hypertension, non-diabetes, no history of abdominal surgery, antecolic gastrojejunostomy and soft pancreas were independent risk factors of POPF. Meanwhile, a nomogram for predicting POPF with good test performance and discriminatory capacity was constituted.

Aptamer-based fluorescent sensors for the detection of cancer biomarkers.

Aptamers are short single-stranded RNA or DNA molecules that can recognize a series of targets with high affinity and specificity. Known as "chemical antibodies", aptamers have many unique merits, including ease of chemical synthesis, high chemical stability, low molecular weight, lack of immunogenicity, and ease of modification and manipulation compared to their protein counterparts. Using aptamers as the recognition groups, fluorescent aptasensors provide exciting opportunities for sensitive detection and quantification of analytes. Herein, we give an overview on the recent development of aptamer-based fluorescent sensors for the detection of cancer biomarkers. Based on various nanostructured sensor designs, we extended our discussions on sensitivity, specificity and the potential applications of aptamer-based fluorescent sensors in early diagnosis, treatment and prognosis of cancers.

Molecular mechanism of the smart attack of pathogenic bacteria on nematodes.

Nematode-bacterial associations are far-reaching subjects in view of their impact on ecosystems, economies, agriculture and human health. There is still no conclusion regarding which pathogenic bacteria sense nematodes. Here, we found that the pathogenic bacterium Bacillus nematocida B16 was sensitive to C. elegans and could launch smart attacks to kill the nematodes. Further analysis revealed that the spores of B. nematocida B16 are essential virulence factors. Once gaseous molecules (morpholine) produced from C. elegans were sensed, the sporulation of B16 was greatly accelerated. Then, B16 showed maximum attraction to C. elegans during the spore-forming process but had no attraction until all the spores were formed. The disruption of either the spore formation gene spo0A or the germination gene gerD impaired colonization and attenuated infection in B16. In contrast, complementation with the intact genes restored most of the above-mentioned deficient phenotypes, which indicated that the spo0A gene was a key factor in the smart attack of B16 on C. elegans. Further, transcriptome, molecular simulations and quantitative PCR analysis showed that morpholine from C. elegans could promote sporulation and initiate infection by increasing the transcription of the spo0A gene by decreasing the transcription of the rapA and spo0E genes. The overexpression of rapA or spo0E decreased the induced sporulation effect, and morpholine directly reduced the level of phosphorylation of purified recombinant RapA and Spo0E compared to that of Spo0A. Collectively, these findings further support a 'Trojan horse-like' infection model. The significance of our paper is that we showed that the soil-dwelling bacterium B. nematocida B16 has the ability to actively detect, attract and attack their host C. elegans. These studies are the first report on the behaviours, signalling molecules and mechanism of the smart attack of B16 on nematodes and also reveal new insights into microbe-host interactions.

Formaldehyde removal in the air by six plant systems with or without rhizosphere microorganisms.

Uptake and in-plant transport of formaldehyde by six plants with or without soil microorganisms were investigated. The capabilities of fresh and boiled leaf extracts to dissipate added formaldehyde were also measured to evaluate formaldehyde metabolism in plant tissues. Results show that when the initial formaldehyde level in air was 0.56 ± 0.04 mg·m-3, the removal rate in the plant-only systems varied from 1.91 to 31.8 µg·h-1·g-1 FW (fresh weight). The removal rate of plants in the plant-only systems were ordered as Helianthus annuus Linn > Lycopersicon esculentum Miller > Oryza sativa > Sansevieria trifasciata Prain > Bryophyllum pinnatum > Mesembryanthemum cordifolium L. f. Most reduction of formaldehyde in the air was due to degradation by active components in the plant tissues, of which 4-64% of these were through to be enzymatic reactions. In the microbe-plant systems, formaldehyde removal rates increased by 0.24-9.53 fold compared to the plant-only systems, with approximately 19.6-90.5% of the formaldehyde reduction resulting from microbial degradation. Microorganisms added to the rhizosphere solution enhanced phytoremediation by increasing the downward transport of formaldehyde and its release by roots. Results suggest a new means to screen for efficient plant species that can be used for phytoremediation of indoor air.

Efficiency and mechanism of formaldehyde removal from air by two wild plants; Plantago asiatica L. and Taraxacum mongolicum Hand.-Mazz.

Indoor potted plants played an important role in the removal of air-borne VOCs. According to the difference between plant fresh extracts and boiled extracts on breakdown ability to the added formaldehyde, a simple quantitative evaluation method was used to identify the mechanisms of formaldehyde removal from the air by wild Taraxacum mongolicum Hand.-Mazz. and Plantago asiatica L.. After shoots exposure to formaldehyde (1.28 mg/m3 in the air) for 24 h, the formaldehyde removal rates of P. asiatica and T. mongolicum were 73.18 and 121.20 mg/h/kg FW (fresh weight), respectively. Formaldehyde can be transported from the air to the rhizosphere solution by plants, and the maximum rates of transmission by T. mongolicum and P. asiatica were 23.73 and 83.08 mg/h/kg FW, respectively. Although plant metabolism was responsible for formaldehyde loss in the air-plant-solution system, and the metabolic activity depended on the enzymatic and redox reactions in the plants, P. asiatica and T. mongolicum are still good candidate species for developing phyto-microbial technologies. The redox reaction was the main mechanism used by P. asiatica shoots to dissipate formaldehyde, while the enzymatic reaction was the main mechanism used by T. mongolicum. The higher oxidative potential and lower defensive enzyme activity in P. asiatica shoots led to its higher formaldehyde removal rate compared to T. mongolicum. Meanwhile, the stronger redox reaction ability in the T. mongolicum roots was partly responsible for its lower formaldehyde transmission rate. The results show two plants have strong tolerance to formaldehyde in the air and good formaldehyde removal ability.

Overexpression of the Key Virulence Factor 1,3-1,4-ß-d-Glucanase in the Endophytic Bacterium Bacillus halotolerans Y6 To Improve Verticillium Resistance in Cotton.

Verticillium wilt, caused by Verticillium dahliae, results in a dramatic loss of cotton yields in China. There is great potential for biocontrol to manage this destructive crop disease. In this study, we obtained the endophytic bacterium Bacillus halotolerans Y6 from Verticillium wilt-resistant cotton Gossypium barbadense Xinhai15; this bacterium possesses strong antagonistic abilities that inhibit V. dahliae spore germination and mycelial growth. The results of the enzyme activity assay, heterologous expression, and gene knockdown showed that the key virulence factor of Y6 for antagonizing V. dahliae was ß -glucanase Bgy6. To facilitate field tests of biological control, we constructed the homologous Bgy6-overexpression strain OY6. Compared with the wild-type Y6 strain, the ß-glucanase activity of OY6 was increased by 91.79%, and the inhibition rate of OY6 against V. dahliae V991 exceeded 96.7%. Moreover, the spores of V. dahliae V991 treated with OY6 showed more mucus and larger holes on the surface, as observed by scanning electron microscopy. Potting test results illustrated that both OY6 and Y6 could improve the resistance of upland cotton to Verticillium wilt. With the inoculation of V. dahliae V991 for 45 days, the disease index of G. hirsutum TM-1 treated with OY6 was only 8.33, which was significantly lower than that in plants treated with the wild-type strain Y6 (17.86) or the controls without bacteria (35.94). Our research provides a new idea for the control of Verticillium wilt in upland cotton via transforming endophytic bacteria of Verticillium wilt-resistant cotton and proposes a new solution to prevent and control Verticillium wilt.

Silver-ion-mediated Mg2+-dependent DNAzyme activity for amplified fluorescence detection of cysteine.

In this paper, by taking advantage of the fact that silver ions could mediate the Mg2+-dependent DNAzyme (Mgzyme) activity, we for the first time developed a turn-on fluorescent biosensor for amplified cysteine (Cys) detection. Because Mgzyme can interact with the silver ion and form cytosine-Ag+-cytosine (C-Ag+-C) base pairs, the conformation of its catalytic core was changed. As a result, the catalytic activity of Mgzyme was suppressed and the Mgzyme-Ag+ complex could not initiate the cleavage reaction. Therefore, the background fluorescence of the biosensor was very low. In the presence of Cys, Cys can bind tightly to the silver ion and disrupt the C-Ag+-C base pairs in the Mgzyme-Ag+ complex, leading to the restoration of Mgzyme activity. The activated Mgzyme could hybridize with the MB substrate and undergo many cleavage cycles, resulting in a significant increase of fluorescence intensity. This designed strategy provided amplified fluorescence detection of cysteine, with a detection limit of 2 nM. Moreover, the strong binding between Cys and Ag+ ensured that the biosensor had a desirable selectivity for Cys. This sensing system was also used to detect Cys in human urine samples and displayed satisfying results.

Roles of reactive oxygen species and antioxidant enzymes on formaldehyde removal from air by plants.

The roles of enzymatic reactions and redox reactions caused by reactive oxygen species (ROS) in formaldehyde metabolism in tomatoes and wheat seedlings and the changes in peroxidase (POD) and catalase (CAT) activities in plants were investigated. Differences in the breakdown of added formaldehyde between fresh and boiled plant extracts were determined to calculate the contributions of different removal mechanisms. Two plant seedlings efficiently removed formaldehyde from air when its level varied from 0.65 to 1.91 mg m-3; meanwhile, the maximum rate at which tomato seedlings transported formaldehyde from air to the rhizosphere solution reached 182.26 µg h-1 kg-1 FW (fresh weight). Metabolism in plants was mainly responsible for the formaldehyde dissipation. The enzymatic contribution to formaldehyde dissipation decreased with increasing shoot exposure time or air formaldehyde level, while the redox contribution increased in importance because of an increasing level of ROS. The different enzymatic antioxidant activities of plants resulted in different levels of ROS and hence different tolerance and removal efficiencies toward formaldehyde. The self-enhancing ability of plants to remove formaldehyde via redox reactions suggested that the formaldehyde removal efficiency could be enhanced by plant adaptation to environmental stress.