[A survey on the implementation of cardiovascular surgery for congenital heart disease in China between 2017 and 2021]

Objective: To investigate the inplementation of cardiovascular surgery for congenital heart disease (CHD) in China. Methods: A cross-sectional study was carried out. The CHD cardiovascular surgery data collected by the Chinese Society of Extracorporeal Circulation from 2017 to 2021 in 31 provinces (autonomous regions/municipalities) of China were retrospectively reviewed, the implementation of CHD cardiovascular surgery in different provinces, regions, general/specialized hospitals, and different age groups (whether≤18 years old) were summarized, and the correlation analysis between the number of surgeries carried out in each province/region and the gross regional product and the number of the regional population was performed. Results: Between 2017 and 2021, the annual volume of CHD cardiovascular surgery was 77 120, 77 634, 81 161, 62 663 and 71 492, respectively, showing a decreasing trend. Meanwhile, the proportion of CHD patients aged≤18 years who underwent cardiovascular surgery also showed a downward trend, from 79.8% (61 557/77 120) in 2017 to 58.6% (41 871/71 492) in 2021 (P=0.027). The number of surgical cases varied greatly among different provinces, including 4 provinces with≥5 000 cases and 9 provinces with 2 000-5 000 cases. In the five years, the number of CHD cardiovascular surgeries in Central and East China was the largest, accounting for 41.1%-45.5% of the total surgical cases. The proportion of CHD surgery cases≤18 years old was the highest in Southwest China (69.7%-87.4%) and the lowest in Northeast China (28.2%-68.9%). Except for 2021, the number of cases carried out by each region between 2017 and 2020 was correlated with the gross regional product (r=0.929, 0.929, 0.893 and 0.964, respectively, all P<0.05) and the population (r=0.821, 0.893, 0.821 and 0.857, respectively, all P<0.05). Hospitals that performed more than 100 operations (20.5%±1.2% of the total number of hospitals) completed 86.2%±1.2% of the total number of operations in China during the 5-year period. In 2017 and 2021, the number of CHD cardiovascular surgeries preformed in children's/women's and children's specialized hospitals accounted for 24.3% (18 772/77 120) and 23.8% (17 012/71 492) of the total number of cases in China, respectively. Conclusions: From 2017 to 2021, the number of cardiovascular surgery for CHD decreases slightly, but the proportion of surgery for adult CHD patients increases significantly.There is a strong correlation between the number of CHD operations in each region and their economic development status. The scale of CHD cardiovascular surgery performed in children's hospitals/women's and children's hospitals accounts for about a quarter of the total volume in China.

A brief history of metal recruitment in protozoan predation

Metals and metalloids are used as weapons for predatory feeding by unicellular eukaryotes on prokaryotes. This review emphasizes the role of metal(loid) bioavailability over the course of Earth's history, coupled with eukaryogenesis and the evolution of the mitochondrion to trace the emergence and use of the metal(loid) prey-killing phagosome as a feeding strategy. Members of the genera Acanthamoeba and Dictyostelium use metals such as zinc (Zn) and copper (Cu), and possibly metalloids, to kill their bacterial prey after phagocytosis. We provide a potential timeline on when these capacities first evolved and how they correlate with perceived changes in metal(loid) bioavailability through Earth's history. The origin of phagotrophic eukaryotes must have postdated the Great Oxidation Event (GOE) in agreement with redox-dependent modification of metal(loid) bioavailability for phagotrophic poisoning. However, this predatory mechanism is predicted to have evolved much later - closer to the origin of the multicellular metazoans and the evolutionary development of the immune systems.

Elimination of virus-like particles reduces protein aggregation and extends replicative lifespan in Saccharomyces cerevisiae

A major consequence of aging and stress, in yeast to humans, is an increased accumulation of protein aggregates at distinct sites within the cells. Using genetic screens, immunoelectron microscopy, and three-dimensional modeling in our efforts to elucidate the importance of aggregate annexation, we found that most aggregates in yeast accumulate near the surface of mitochondria. Further, we show that virus-like particles (VLPs), which are part of the retrotransposition cycle of Ty elements, are markedly enriched in these sites of protein aggregation. RNA interference-mediated silencing of Ty expression perturbed aggregate sequestration to mitochondria, reduced overall protein aggregation, mitigated toxicity of a Huntington's disease model, and expanded the replicative lifespan of yeast in a partially Hsp104-dependent manner. The results are in line with recent data demonstrating that VLPs might act as aging factors in mammals, including humans, and extend these findings by linking VLPs to a toxic accumulation of protein aggregates and raising the possibility that they might negatively influence neurological disease progression.

Labile carbon inputs boost microbial contribution to legacy mercury reduction and emissions from industry-polluted soils

Soils is a crucial reservoir influencing mercury (Hg) emissions and soil-air exchange dynamics, partially modulated by microbial reducers aiding Hg reduction. Yet, the extent to which microbial engagements contribute to soil Hg volatilization remains largely unknown. Here, we characterized Hg-reducing bacterial communities in natural and anthropogenically perturbed soil environments and quantified their contribution to soil Hg(0) volatilization. Our results revealed distinct Hg-reducing bacterial compositions alongside elevated mercuric reductase (merA) gene abundance and diversity in soils adjacent to chemical factories compared to less-impacted ecosystems. Notably, solely industry-impacted soils exhibited increased merA gene abundance along Hg gradients, indicating microbial adaption to Hg selective pressure through quantitative changes in Hg reductase and genetic diversity. Microcosm studies demonstrated that glucose inputs boosted microbial involvement and induced 2-8 fold increments in cumulative Hg(0) volatilization in industry-impacted soils. Microbially-mediated Hg reduction contributed to 41.6% of soil Hg(0) volatilization in industry-impacted soils under 25% water-holding capacity and glucose input conditions over a 21-day incubation period. Alcaligenaceae, Moraxellaceae, Nitrosomonadaceae and Shewanellaceae were identified as potential contributors to Hg(0) volatilization in the soil. Collectively, our study provides novel insights into microbially-mediated Hg reduction and soil-air exchange processes, with important implications for risk assessment and management of industrial Hg-contaminated soils.

Protists regulate microbially mediated organic carbon turnover in soil aggregates

Soil protists, the major predator of bacteria and fungi, shape the taxonomic and functional structure of soil microbiome via trophic regulation. However, how trophic interactions between protists and their prey influence microbially mediated soil organic carbon turnover remains largely unknown. Here, we investigated the protistan communities and microbial trophic interactions across different aggregates-size fractions in agricultural soil with long-term fertilization regimes. Our results showed that aggregate sizes significantly influenced the protistan community and microbial hierarchical interactions. Bacterivores were the predominant protistan functional group and were more abundant in macroaggregates and silt + clay than in microaggregates, while omnivores showed an opposite distribution pattern. Furthermore, partial least square path modeling revealed positive impacts of omnivores on the C-decomposition genes and soil organic matter (SOM) contents, while bacterivores displayed negative impacts. Microbial trophic interactions were intensive in macroaggregates and silt + clay but were restricted in microaggregates, as indicated by the intensity of protistan-bacterial associations and network complexity and connectivity. Cercozoan taxa were consistently identified as the keystone species in SOM degradation-related ecological clusters in macroaggregates and silt + clay, indicating the critical roles of protists in SOM degradation by regulating bacterial and fungal taxa. Chemical fertilization had a positive effect on soil C sequestration through suppressing SOM degradation-related ecological clusters in macroaggregate and silt + clay. Conversely, the associations between the trophic interactions and SOM contents were decoupled in microaggregates, suggesting limited microbial contributions to SOM turnovers. Our study demonstrates the importance of protists-driven trophic interactions on soil C cycling in agricultural ecosystems.

[Predictive value of aMAP risk score for early recurrence of small hepatocellular carcinoma after microwave ablation]

Objective: To explore the value of the aMAP risk score (age, male, albumin-bilirubin, and platelets) to predict early recurrence within one year after microwave ablation in patients with small hepatocellular carcinoma. Methods: This was a retrospective study that enrolled 142 patients diagnosed with hepatocellular carcinoma who were treated with microwave ablation in the Department of Hepatology Unit of Nanfang Hospital, Southern Medical University from July 2016 to July 2021. The cohort enrolled 121 male and 21 female patients, including 110 patients that were <60 years old. All the patients were followed-up after microwave ablation to evaluate residual tumor and recurrence of tumor by computed tomography or magnetic resonance imaging. The observation indices mainly included general data and imaging data of patients. Using the X-tile tools, patients were divided into two groups: a high aMAP score group and a low aMAP score group. Multivariate Cox regression analysis was conducted for comparison of independent risk factors. Results: Multivariate Cox regression showed that high aMAP score, maximum tumor diameter >20 mm, and high AFP were the independent risk factors of early recurrence (all P<0.05). Kaplan-Meier survival curves showed that the median recurrence-free survival was 25.5 months in the low aMAP score group and 6.1 months in the high aMAP score group (P=0.001). Conclusions: The aMAP score could predict the early recurrence within 1 year of small hepatocellular carcinoma after microwave ablation. Patients with high aMAP score should undergo rigorous postoperative follow-up evaluations..

Neuroprotective Effect of Hydrogen Sulfide Subchronic Treatment Against TBI-Induced Ferroptosis and Cognitive Deficits Mediated Through Wnt Signaling Pathway

Emerging evidence shows that targeting ferroptosis may be a potential therapeutic strategy for treating traumatic brain injury (TBI). Hydrogen sulfide (H2S) has been proven to play a neuroprotective role in TBI, but little is known about the effects of H2S on TBI-induced ferroptosis. In addition, it is reported that the Wnt signaling pathway can also actively regulate ferroptosis. However, whether H2S inhibits ferroptosis via the Wnt signaling pathway after TBI remains unclear. In this study, we first found that in addition to alleviating neuronal damage and cognitive impairments, H2S remarkably attenuated abnormal iron accumulation, decreased lipid peroxidation, and improved the expression of glutathione peroxidase 4, demonstrating the potent anti-ferroptosis action of H2S after TBI. Moreover, Wnt3a or liproxstatin-1 treatment obtained similar results, suggesting that activation of the Wnt signaling pathway can render the cells less susceptible to ferroptosis post-TBI. More importantly, XAV939, an inhibitor of the Wnt signaling pathway, almost inversed ferroptosis inactivation and reduction of neuronal loss caused by H2S treatment, substantiating the involvement of the Wnt signaling pathway in anti-ferroptosis effects of H2S. In conclusion, the Wnt signaling pathway might be the critical mechanism in realizing the anti-ferroptosis effects of H2S against TBI. TBI induces ferroptosis-related changes characterized by iron overload, impaired antioxidant system, and lipid peroxidation at the chronic phase after TBI. However, NaHS subchronic treatment reduces the susceptibility to TBI-induced ferroptosis, at least partly by activating the Wnt signaling pathway.

Moderate Intensity of Treadmill Exercise Rescues TBI-Induced Ferroptosis, Neurodegeneration, and Cognitive Impairments via Suppressing STING Pathway

Traumatic brain injury (TBI) is a universal leading cause of long-term neurological disability and causes a huge burden to an ever-growing population. Moderate intensity of treadmill exercise has been recognized as an efficient intervention to combat TBI-induced motor and cognitive disorders, yet the underlying mechanism is still unclear. Ferroptosis is known to be highly implicated in TBI pathophysiology, and the anti-ferroptosis effects of treadmill exercise have been reported in other neurological diseases except for TBI. In addition to cytokine induction, recent evidence has demonstrated the involvement of the stimulator of interferon genes (STING) pathway in ferroptosis. Therefore, we examined the possibility that treadmill exercise might inhibit TBI-induced ferroptosis via STING pathway. In this study, we first found that a series of ferroptosis-related characteristics, including abnormal iron homeostasis, decreased glutathione peroxidase 4 (Gpx4), and increased lipid peroxidation, were detected at 44 days post TBI, substantiating the involvement of ferroptosis at the chronic stage following TBI. Furthermore, treadmill exercise potently decreased the aforementioned ferroptosis-related changes, suggesting the anti-ferroptosis role of treadmill exercise following TBI. In addition to alleviating neurodegeneration, treadmill exercise effectively reduced anxiety, enhanced spatial memory recovery, and improved social novelty post TBI. Interestingly, STING knockdown also obtained the similar anti-ferroptosis effects after TBI. More importantly, overexpression of STING largely reversed the ferroptosis inactivation caused by treadmill exercise following TBI. To conclude, moderate-intensity treadmill exercise rescues TBI-induced ferroptosis and cognitive deficits at least in part via STING pathway, broadening our understanding of neuroprotective effects induced by treadmill exercise against TBI.

[Risk factors associated with in-hospital mortality in patients requiring extracorporeal membrane oxygenation in the perioperative period of heart transplantation]

Objective: To explore risk factors associated with in-hospital mortality in patients requiring extracorporeal membrane oxygenation (ECMO) in the perioperative period of heart transplantation. Methods: The data of ECMO cases in the perioperative period of heart transplantation from the Chinese Society of Extracorporeal Life Support (CSECLS) between January 2017 and December 2021 were retrospectively analyzed. These patients were divided into the survival group and non-survival group according to their outcomes at discharge. The demographics, indications and complications of ECMO between the two groups were compared, and the related risk factors of poor prognosis were analyzed. Results: A total of 77 patients were included in the study, including 67 males and 10 females, with a median age [M(Q₁, Q₃)] of 48 (36, 59) years. Sixty-three patients (81.8%) were successfully withdrawn from the ECMO and 46 patients (59.7%) survived to discharge. The median ECMO time was 139 (92, 253) hours. Compared with the survival group, the non-survival group (n=31) had more patients with chronic kidney disease before surgery [22.6% (7/31) vs 4.3% (2/46), P=0.034], and a higher proportion of continuous renal replacement therapy (CRRT) during ECMO [74.2% (23/31) vs 50.0% (23/46), P=0.034]. Moreover, the non-survival group had longer duration of extracorporeal circulation [262 (195, 312) vs 201 (155, 261) min, P=0.056] and higher lactate value in the first 24 hours of ECMO support [2.7 (2.1, 4.7) vs 2.3 (1.4, 3.8) mmol/L, P=0.060], but the differences were not statistically significant. Multivariate logistic regression analysis showed that perioperative application of CRRT was an independent risk factor for poor prognosis in ECMO patients during heart transplantation (OR=19.345, 95%CI: 1.209-309.440, P=0.036). Conclusion: CRRT treatment during ECMO is a risk factor for in-hospital mortality in patients undergoing heart transplantation.

Plastispheres as hotspots of microbially-driven methylmercury production in paddy soils

Microplastics (MPs) as emerging contaminants have accumulated extensively in agricultural ecosystems and are known to exert important effects on biogeochemical processes. However, how MPs in paddy soils influence the conversion of mercury (Hg) to neurotoxic methylmercury (MeHg) remains poorly understood. Here, we evaluated the effects of MPs on Hg methylation and associated microbial communities in microcosms using two typical paddy soils in China (i.e., yellow and red soils). Results showed that the addition of MPs significantly increased MeHg production in both soils, which could be related to higher Hg methylation potential in the plastisphere than in the bulk soil. We found significant divergences in the community composition of Hg methylators between the plastisphere and the bulk soil. In addition, the plastisphere had higher proportions of Geobacterales in the yellow soil and Methanomicrobia in the red soil compared with the bulk soil, respectively; and plastisphere also had more densely connected microbial groups between non-Hg methylators and Hg methylators. These microbiota in the plastisphere are different from those in the bulk soil, which could partially account for their distinct MeHg production ability. Our findings suggest plastisphere as a unique biotope for MeHg production and provide new insights into the environment risks of MP accumulation in agricultural soils.

Limited impacts of high doses of dietary copper on the gut bacterial metal resistome explain negligible co-selection of antibiotic resistance

High dietary intake of Cu has previously been linked to the selection of Cu resistance and co-selection of antibiotic resistance in specific gut bacteria. Based on a novel HT-qPCR metal resistance gene chip as combined with 16S rRNA gene amplicon sequencing and phenotypic resistance typing of Escherichia coli isolates, we here report the impacts of two contrasting Cu-based feed additives on the swine gut bacterial metal resistome and community assembly. DNA was extracted from fecal samples (n = 80) collected at day 26 and 116 of the experiment from 200 pigs allotted to five dietary treatments: negative control (NC) diet with 20 μg CuSO₄ g^-1 and four diets added 125 or 250 μg CuSO₄ g^-1 feed or 125 or 250 μg Cu₂O g^-1 feed to the NC diet. Dietary Cu supplementation reduced the relative abundance of Lactobacillus, but it had negligible impacts on bacterial community composition relative to the gut microbiome maturation effect (time). The relative importance of different bacterial community assembly processes was not markedly affected by the dietary Cu treatments, and differences in swine gut metal resistome composition could be explained primarily by differences in bacterial community composition rather than by dietary Cu treatments. High dietary Cu intake (250 μg Cu g^-1) selected for phenotypic Cu resistance in E. coli isolates, but surprisingly it did not result in increased prevalence of the Cu resistance genes targeted by the HT-qPCR chip. In conclusion, the lacking impacts of dietary Cu on the gut bacterial metal resistome explain results from a previous study showing that even high therapeutic doses of dietary Cu did not cause co-selection of antibiotic resistance genes and mobile genetic elements known to harbor these genes.

Core Species Derived from Multispecies Interactions Facilitate the Immobilization of Cadmium

Microbial consortia have opened new avenues for heavy-metal remediation. However, the limited understanding of the overall effect of interspecific interactions on remediation efficacy hinders its application. Here, the effects of multispecies growth and biofilm formation on Cd immobilization were explored from direct and multiple interactions through random combinations of two or three rhizosphere bacteria. In monocultures, Cd stress resulted in an average decrease in planktonic biomass of 26%, but through cooperation, the decrease was attenuated in dual (21%) and triple cultures (13%), possibly involving an increase in surface polysaccharides. More than 65% of the co-cultures exhibited induction of biofilm formation under Cd stress, which further enhanced the role of biofilms in Cd immobilization. Notably, excellent biofilm-forming ability or extensive social induction makes Pseudomonas putida and Brevundimonas diminuta stand out in multispecies biofilm formation and Cd immobilization. These two core species significantly increase the colonization of soil microorganisms on rice roots compared to the control, resulting in a 40% decrease in Cd uptake by rice. Our study enhances the understanding of bacterial interactions under Cd stress and provides a novel strategy for adjusting beneficial soil consortia for heavy-metal remediation.

[Treat-all: challenges of partial response and low-level viremia]

The recently updated "Guidelines for the Prevention and Treatment of Chronic Hepatitis B" in China have brought about significant changes. The new treatment indications almost mandate the implementation of a Treat-all strategy for the chronically HBV-infected population in China. While simultaneous negativity for hepatitis B surface antigen (HBsAg) and hepatitis B virus (HBV) DNA has long been an accepted criterion for treatment discontinuation, there has been controversies over the initiation of treatment criteria starting with HBsAg and HBV DNA positivity. Despite the inconsistent treatment criteria, the academic community has started supporting treat-all strategies in recent years due to the decreasing cost of treatment, prolonged management duration, and growing evidence of poor outcomes in untreated populations. Therefore, this update to the Chinese HBV guidelines represents a new direction that suggests "The greatest truths are the simplest." However, in the process of rolling out the Treat-all strategy, we must remain cautious of possible issues arising from the new strategy. Among them, the problem of partial response or low-level viremia following treatment may become more prominent due to the inclusion of a significant number of patients with normal or low levels of alanine transaminase. As existing evidence suggests that low-level viremia increases the risk of HCC in patients, it is essential to monitor and explore optimal therapeutic options for these patients.

Phagotrophic Protists Modulate Copper Resistance of the Bacterial Community in Soil

Protist predation is a crucial biotic driver modulating bacterial populations and functional traits. Previous studies using pure cultures have demonstrated that bacteria with copper (Cu) resistance exhibited fitness advantages over Cu-sensitive bacteria under the pressure of protist predation. However, the impact of diverse natural communities of protist grazers on bacterial Cu resistance in natural environments remains unknown. Here, we characterized the communities of phagotrophic protists in long-term Cu-contaminated soils and deciphered their potential ecological impacts on bacterial Cu resistance. Long-term field Cu pollution increased the relative abundances of most of the phagotrophic lineages in Cercozoa and Amoebozoa but reduced the relative abundance of Ciliophora. After accounting for soil properties and Cu pollution, phagotrophs were consistently identified as the most important predictor of the Cu-resistant (Cu^R) bacterial community. Phagotrophs positively contributed to the abundance of a Cu resistance gene (copA) through influencing the cumulative relative abundance of Cu-resistant and -sensitive ecological clusters. Microcosm experiments further confirmed the promotion effect of protist predation on bacterial Cu resistance. Our results indicate that the selection by protist predation can have a strong impact on the Cu^R bacterial community, which broadens our understanding of the ecological function of soil phagotrophic protists.

Tracking soil resistance and virulence genes in rice-crayfish co-culture systems across China

Rice-crayfish co-culture (RC) has been widely and rapidly promoted as a sustainable agricultural system in many countries. The accumulation of crayfish residues could enhance soil organic matters; however, impacts of this integrated farming model on the dissemination and pathogenicity of resistance and virulence genes remain poorly understood. Here, we characterized antibiotic resistance genes (ARGs), biocide resistance genes (BRGs), metal resistance genes (MRGs) and virulence factor genes (VFGs) using metagenomic methods in paired RC and rice monoculture (RM) systems across China. The RC model did not increase the abundance of soil ARGs, BRGs, MRGs, or VFGs in comparison to the RM model, but selectively enriched 35 subtypes of these potential resistance and virulence genes. Network analysis revealed that resistance and virulence genes had a higher number of connections with mobile genetic elements (MGEs) in the RC system than that in the RM system, suggesting a higher horizontal transfer potential of these genes. Moreover, the RC model had a higher abundance of human opportunistic pathogens such as Salmonella enterica, Vibrio cholerae, and Shigella dysenteriae which were potential hosts of VFGs such as phoP, fleS, and gspE, suggesting a potential threat to human health. We further unraveled that stochastic process was the main driver of the assembly of resistance and virulence genes in the RC system. The abundance of ARGs and VFGs were primarily associated with microbial community compositions, while the abundance of BRGs and MRGs were mainly associated with that of MGEs. Taken together, our results suggest that the RC model has potential to cause the dissemination and pathogenicity of resistance and virulence genes, which has important implications for the control of soil-borne biological risks and the strategic management of sustainable agriculture.

Dichotomous Role of Humic Substances in Modulating Transformation of Antibiotic Resistance Genes in Mineral Systems

Widespread antibiotic resistance genes (ARGs) have emerged as a focus of attention for public health. Transformation is essential for ARGs dissemination in soils and associated environments; however, the mechanisms of how soil components contribute to the transformation of ARGs remain elusive. Here we demonstrate that three representative mineral-humic acid (HA) composites exert contrasting influence on the transformation of plasmid-borne ARGs in Bacillus subtilis. Mineral surface-bound HA facilitated transformation in kaolinite and montmorillonite systems, while an inhibitory effect of HA was observed for goethite. The elevated transformation by HA-coated kaolinite was mainly attributed to the enhanced activity of competence-stimulating factor (CSF), while increased transformation by montmorillonite-HA composites was assigned to the weakened adsorption affinity of DNA and enhanced gene expression induced by flagella-driven cell motility. In goethite system, HA played an overriding role in suppressing transformation via alleviation of cell membrane damage. The results obtained offer insights into the divergent mechanisms of humic substances in modulating bacterial transformation by soil minerals. Our findings would help for a better understanding on the fate of ARGs in soil systems and provide potentials for the utilization of soil components, particularly organic matter, to mitigate the spread of ARGs in a range of settings.

Rice-crayfish co-culture increases microbial necromass' contribution to the soil nitrogen pool

The rice-crayfish co-culture (RC) is a putative sustainable agricultural system. However, studies on the ecological effects of long-term RC systems were still lacking. Here, we compare enzymatic stoichiometry, microbial necromass, and microbial community between the RC and rice monoculture systems (RM). Soil enzymatic stoichiometry analysis showed that after transformation from RM to RC for about three years, ammonium nitrogen (NH₄⁺-N) availability increased to depress relative N-acquiring enzyme production, especially for leucine aminopeptidase. The contents of microbial necromass increased approximately onefold in the RC system, making microbial necromass' contribution to the soil nitrogen (N) reach up to 46.72%. Elevation in NH₄⁺ decreased N-acquiring enzyme, and a relatively more effective C acquisition likely benefited microbial necromass retention and production in the RC system. This study highlights that the rice-crayfish co-culture could modify the N pool of the surface paddy soil.

Microbial autotrophy explains large-scale soil CO2 fixation

Microbial communities play critical roles in fixing carbon from the atmosphere and fixing it in the soils. However, the large-scale variations and drivers of these microbial communities remain poorly understood. Here, we conducted a large-scale survey across China and found that soil autotrophic organisms are critical for explaining CO₂ fluxes from the atmosphere to soils. In particular, we showed that large-scale variations in CO₂ fixation rates are highly correlated to those in autotrophic bacteria and phototrophic protists. Paddy soils, supporting a larger proportion of obligate bacterial and protist autotrophs, display four-fold of CO₂ fixation rates over upland and forest soils. Precipitation and pH, together with key ecological clusters of autotrophic microbes, also played important roles in controlling CO₂ fixation. Our work provides a novel quantification on the contribution of terrestrial autotrophic microbes to soil CO₂ fixation processes at a large scale, with implications for global carbon regulation under climate change.

Ammonia level influences the assembly of dissimilatory nitrate reduction to ammonia bacterial community in soils under different heavy metal remediation treatments

Heavy metal remediation treatments might influence functional microbial community assembly. Dissimilatory nitrate reduction to ammonia (DNRA) contributes to the nitrogen retention processes in soil ecosystems. We assumed that remediation might reduce heavy metal toxicity and increase some available nutrients for the DNRA microbes, thus balancing the deterministic and stochastic process for DNRA community assembly. Here, we investigated the process of DNRA bacterial community assembly under different heavy metal remediation treatments (including control, biochar, limestone, rice straw, rice straw + limestone, and biochar + limestone) in an Alfisol soil. The abundance of DNRA bacteria diverged across treatments. The α-diversity of the DNRA bacterial community was correlated with pH, available phosphorus (AP), ammonium (NH₄⁺), and extractable Fe (EFe). Metal Cd and Fe significantly affected the abundance of the nrfA gene. The β-diversity was associated with pH, NH₄⁺, and EFe. Deterministic processes dominantly drove the assembly processes of the DNRA bacterial community. NH₄⁺ level played an essential role in the assembly processes than the other soil physicochemical properties and metal availability. High, moderate, and low levels of NH₄⁺ could advocate stochastic process plus selection, heterogeneous selection to stochastic process, and heterogeneous selection, respectively. Network analysis highlighted a predominant role of NH₄⁺ in regulating DNRA bacterial community assembly. However, the relative abundance of modules and some keystone species also were influenced by pH and EFe, respectively. Therefore, the DNRA bacterial community assembly under different heavy metal remediation treatments in this study was dominantly driven by nitrogen availability. pH, phosphorus, and metal availability were auxiliary regulators on DNRA bacterial community.

[Application of liquid biopsy in early screening and recurrence prediction of hepatocellular carcinoma]

The incidence and mortality of HCC in China account for approximately 50% of all cases worldwide. Low early diagnosis rate and high postoperative recurrence rate are two major causes for poor 5-year survival rate of HCC patients in China. At present, multiple problems such as low performance and compliance of screening technology and lack of effective markers for predicting postoperative recurrence, remain to be resolved. Due to the simplicity and accuracy, new molecular markers, such as liquid biopsy, are expected to serve as supplementary tools to traditional screening and early warning approaches, thereby realizing early detection and accurate treatment of HCC. In this article, research progress upon the clinical application of liquid biopsy in early screening and prediction of postoperative recurrence of HCC was reviewed, and prospects the future research.

Stronger responses of soil protistan communities to legacy mercury pollution than bacterial and fungal communities in agricultural systems

Soil pollution is an important stressor affecting biodiversity and ecosystem functioning. However, we lack a holistic understanding of how soil microbial communities respond to heavy metal pollution in agricultural ecosystems. Here, we explored the distribution patterns and inter-kingdom interactions of entire soil microbiome (including bacteria, fungi, and protists) in 47 paired paddy and upland fields along a gradient of legacy mercury (Hg) pollution. We found that the richness and composition of protistan community had stronger responses to Hg pollution than those of bacterial and fungal communities in both paddy and upland soils. Mercury polluted soils harbored less protistan phototrophs but more protistan consumers. We further revealed that long-term Hg pollution greatly increased network complexity of protistan community than that of bacterial and fungal communities, as well as intensified the interactions between protists and the other microorganisms. Moreover, our results consistently indicated that protistan communities had stronger responses to long-term Hg pollution than bacterial and fungal communities in agricultural soils based on structural equation models and random forest analyses. Our study highlights that soil protists can be used as bioindicators of Hg pollution, with important implications for the assessment of contaminated farmlands and the sustainable management of agricultural ecosystems.

MRG Chip: A High-Throughput qPCR-Based Tool for Assessment of the Heavy Metal(loid) Resistome

Bacterial metal detoxification mechanisms have been well studied for centuries in pure culture systems. However, profiling metal resistance determinants at the community level is still a challenge due to the lack of comprehensive and reliable quantification tools. Here, a novel high-throughput quantitative polymerase chain reaction (HT-qPCR) chip, termed the metal resistance gene (MRG) chip, has been developed for the quantification of genes involved in the homeostasis of 9 metals. The MRG chip contains 77 newly designed degenerate primer sets and 9 published primer sets covering 56 metal resistance genes. Computational evaluation of the taxonomic coverage indicated that the MRG chip had a broad coverage matching 2 kingdoms, 29 phyla, 64 classes, 130 orders, 226 families, and 382 genera. Temperature gradient PCR and HT-qPCR verified that 57 °C was the optimal annealing temperature, with amplification efficiencies of over 94% primer sets achieving 80-110%, with R² > 0.993. Both computational evaluation and the melting curve analysis of HT-qPCR validated a high specificity. The MRG chip has been successfully applied to characterize the distribution of diverse metal resistance determinants in natural and human-related environments, confirming its wide scope of application. Collectively, the MRG chip is a powerful and efficient high-throughput quantification tool for exploring the microbial metal resistome.

P-448 Changes in gene transcription induced by cyclophosphamide treatment in an experimental ovarian culture model

Study question

How does cyclophosphamide (CPA) treatment impact at transcriptional level on mouse ovarian tissue?

Summary answer

Cultured murine ovarian tissue with CPA versus control showed up-regulated intrinsic and extrinsic apoptotic signaling pathways, associated with DNA damage, DNA repair and oxidative response.

What is known already

Alkylating chemotherapeutic treatment depletes the ovarian pool and induces infertility in women. The suggested mechanisms behind these adverse effects include apoptosis and/or over-activation of the dormant primordial follicle pool. However, there is a lack of knowledge about the pathways that lead to these outcomes and previous researches have been inconclusive. The investigation of changes in the ovarian transcriptomic profiling following the alkylating drug CPA treatment can be useful to identify new potential targets for fertility preservation in women treated for cancer.

Study design, size, duration

Controlled experimental study using 20 female B6CBA/F1 4-day-old mice. Ovaries were collected and randomly assigned to CPA (4-hydroperoxycyclophosphamide) treated group (n = 20) or control group (n = 20). Five ovaries/group were collected at 8, 12, 24 and 36 h to investigate the dynamic of the changes. RNA extraction and RNA sequencing analysis were carried out.

Participants/materials, setting, methods

Ovaries were cultured on Millicell cell culture inserts floating on 0.25 mL culture medium in a 24-well plate. Freshly prepared 4-hydroperoxycyclophosphamide solution was added to the wells of CPA group (final concentration = 5 µM). Equal amount of solvent was added to the wells of control group. Culture medium was refreshed at 48 h with culture medium only. RNA sequencing data were processed for subsequent differentially expressed genes (DEGs) and gene set enrichment analysis (GSEA).

Main results and the role of chance

At 8 h, CPA treatment induced the up-regulation of biological processes related to hypoxia, cell growth and embryonic organ development. At 12 h, DNA damage and the ovarian cell responses were evidenced by an increased activity of DNA damage response, DNA damage checkpoint, DNA repair (double-strand break, mismatch, single strand binding), stress-activated MAPK cascade, antioxidant activity and intrinsic apoptotic signaling pathway. The representative genes of these processes there were Bbc3, Bax, Trp73, Cdkn1a, Trp53inp1 and Mdm2. A dramatic increase in the number of DEGs was found at 24 h (8 h, n = 209; 12 h, n = 239; 24 h, n = 2013). Also at 24 h DNA repair, intrinsic and extrinsic apoptotic signaling pathways were the most representative processes evidenced by the addition of Rad9a, H2afx, Casp3, Bak1 and Casp8 genes to the above mentioned. Whereas, germ cell related genes Ybx2, Nobox and Ddx4 were all down-regulated. At 36 h, the number of DEGs (n = 3804) still increased, the up-regulated pathways were similar to 24 h, while meiosis and microtubule-based movements pathways were observed in the down-regulated set too.

Limitations, reasons for caution

Although the age of the mice chosen for the experiment ensured a high and representative content of primordial follicles in the ovary, whole ovaries were used for RNA sequencing analysis containing a heterogeneous composition of cells other than follicles.

Wider implications of the findings

Our results provide evidence of dynamic sequential changes in transcriptional level where apoptosis was involved in CPA-induced ovarian follicle depletion. Our research indicates a time frame before the occurrence of DNA definitive damage following CPA-treatment, where application of possible treatments in order to prevent the following apoptosis would be possible.

Trial registration number

Not Applicable

POS0102 GLOBAL CHARACTERIZATION OF SALIVARY GLANDS IMMUNE MICROENVIRONMENT IN PRIMARY SJÖGREN’S SYNDROME BY SINGLE-CELL SEQUENCING

Background

Primary Sjögren’s syndrome (pSS) is a heterogeneous, chronic, complex systemic autoimmune disease. The hallmark symptom of the disease is exocrinopathy, chiefly salivary and lachrymal glands, which often results in dryness of the mouth and eyes. As of today, although a lot of genetic and epigenetic studies have reveal the complexity of pSS to a certain extent, but the knowledge of existing pSS disease heterogeneity is still limited and the immune mechanisms of salivary glands (SG) injury have been challenging to clarify.

Objectives

Single-cell RNA sequencing (scRNA-seq) is a powerful tool capable of defining cell types and states on the basis of their individual transcriptome in a given sample from health and disease. To characterize the salivary glands immune microenvironment of patients with pSS, we performed droplet-based single cell mRNA sequencing (scRNA-seq) (10X Genomics) to provide a deeper insight into the cellular and molecular characteristics of salivary glands from pSS patients.

Methods

11 patients and 5 non-pSS controls were recruited from the The First Affiliated Hospital of USTC. The non-pSS were subjects who had experienced subjective symptoms of dryness, but no not meet any of the classification criteria of pSS. The clinical characteristics and laboratory findings of enrolled patients were also collected. After resection, salivary glands tissue samples were obtained after labial gland biopsy, rapidly digested to a single-cell suspension and subjected to scRNA-seq using the 10X platform. After rigorous quality control (QC) definition, low-quality cells were filtered. Following gene expression normalization for read depth and mitochondrial read count, we applied principle component analysis on genes variably expressed across all 72,853 cell.

Results

A total of 72,853 cells were obtained from all salivary glands samples. Our results revealed 12 major unique cell populations of salivary glands cell, including T cells, B cells, plasma cells, epithelial cells, myoepithelial cells, endothelial cells, myofibroblast, pericytes, melanocytes, fibroblast, myeloid cells and a cluster of unknown cells. As expected, lymphocytes (T and B cell populations) were significant increase in the salivary glands of patients with pSS. For further subsets analysis, we identify 41 subsets, including novel subpopulations in cell types hitherto considered to be homogeneous, as well as transcription factors underlying their heterogeneity. Strikingly, we found that differentially expressed genes (DEGs) that myoepithelial cells uniquely downregulated in pSS patients were involved in regeneration, stem cell population maintenance, cell division, and epithelial cell proliferation. This indicated an impaired stem cell property and regeneration capacity of myoepithelial cells in the SG of pSS patients which may result in the reduction of normal epithelial cells differentiation and proliferation. Our results identified three distinct endothelial subtypes according to the differentially expressed cell markers. ACKR1+ endothelial cells were expanded in the SG of pSS patients which may enhance Leukocyte transendothelial migration. A clear interferon response was observed in most celltypes. We also found a significantly expand PD-1hiCXCR5–CD4+T peripheral helper (Tph), GZMK+CD8+ T cells and a patient-specific fibroblasts in pSS patients. Cellular interaction analysis of SG revealed a strong interaction between epithelial cells and immune cells from pSS patients through CD74-MIF, MIF-TNFRSF14 and HLA-C-FAM3C receptor/ ligand pairs. Chemokine receptors CXCR4 were broadly expressed in SG immune cells implying a potentially central role in cell trafficking.

Conclusion

This resource provides deeper insights into pSS salivary glands immune microenvironment that will be helpful in understanding of the disease heterogeneity and advancing pSS therapy.

Disclosure of Interests

None declared

MiR-590 suppresses the progression of non-small cell lung cancer by regulating YAP1 and Wnt/β-catenin signaling

OBJECTIVE

Accumulating evidence has been revealed that miR-590 is involved in the progression and carcinogenesis of various cancers. However, the molecular mechanism of miR-590 in non-small-cell lung cancer (NSCLC) remains unclear.

METHODS

Quantitative reverse transcription-PCR (qRT-PCR), western blot, MTT, and transwell assay were applied to investigate the functional role of miR-590 in this study. Dual luciferase reporter assay was utilized to investigate the interaction between YAP1 and miR-590 expression. Cells transfected with miR-590 mimic or inhibitor were subjected to western blot to investigate the role of Wnt/β-catenin signaling in NSCLC modulated by miR-590.

RESULTS

MiR-590 was down-regulated in NSCLC tissues and cells. Kaplan-Meier analysis found that the higher expression of miR-590 in NSCLC patients, the more improved survival rate of NSCLC patients. Over-expression of miR-590 inhibited NSCLC cell proliferation, migration, and invasion. Moreover, increasing miR-590 suppressed Yes-associated protein 1 (YAP1) expression and inhibited the Wnt/β-catenin pathway in NSCLC cells. Furthermore, miR-590 was negatively correlated with YAP1 expression.

CONCLUSION

These findings demonstrated that the miR-590/YAP1 axis exerted an important role in the progression of NSCLC, suggesting that miR-590 might be the appealing prognostic marker for NSCLC treatment.

OUP accepted manuscript

During germination, the seed releases nutrient-rich exudates into the spermosphere, thereby fostering competition between resident microorganisms. However, insight into the composition and temporal dynamics of seed-associated bacterial communities under field conditions is currently lacking. This field study determined the temporal changes from 11 to 31 days after sowing in the composition of seed-associated bacterial communities of winter wheat as affected by long-term soil fertilization history, and by introduction of the plant growth-promoting microbial inoculants Penicillium bilaiae and Bacillus simplex. The temporal dynamics were the most important factor affecting the composition of the seed-associated communities. An increase in the relative abundance of genes involved in organic nitrogen metabolism (ureC and gdhA), and in ammonium oxidation (amoA), suggested increased mineralization of plant-derived nitrogen compounds over time. Dynamics of the phosphorus cycling genes ppt, ppx and cphy indicated inorganic phosphorus and polyphosphate cycling, as well as phytate hydrolysis by the seed-associated bacteria early after germination. Later, an increase in genes for utilization of organic phosphorus sources (phoD, phoX and phnK) indicated phosphorus limitation. The results indicate that community temporal dynamics are partly driven by changed availability of major nutrients, and reveal no functional consequences of the added inoculants during seed germination.

Influence of Legacy Mercury on Antibiotic Resistomes: Evidence from Agricultural Soils with Different Cropping Systems

Agricultural soils are important reservoirs for antibiotic resistance genes (ARGs), which have close linkage to human health via crop production. Metal stress in environments may function as a selection pressure for antibiotic resistomes. However, there is still a lack of field studies focusing on the effect of historical mercury (Hg) contamination on antibiotic resistomes in agricultural soils. Here, we explored the ARG profile in soils with different cropping systems (paddy and upland) and linked them to legacy Hg exposure. We found that ARG profiles were significantly different between paddy and upland soils. However, both paddy and upland soils with long-term field Hg contamination harbored higher diversity and abundance of ARGs than non-polluted soils. The co-occurrence network reveals significant associations among Hg, Hg resistance genes, mobile genetic elements (MGEs), and ARGs. Together with path analysis showing legacy Hg possibly affecting soil resistomes through the shifts of soil microbiota, Hg resistance genes, and MGEs, we suggest that legacy Hg-induced potential co-selection might elevate the ARG level. Redundancy analysis further supports that legacy Hg pollution had a significant association with ARG variations in the paddy and upland soils (P < 0.01). Collectively, our results highlight the underappreciated role of legacy Hg as a potential persistent selecting agent in contributing to soil ARGs in agroecosystems.

Identification of RNA silencing suppressor encoded by wheat blue dwarf (WBD) phytoplasma

Plants possess an innate immune system for defence against pathogens. In turn, pathogens have various strategies to overcome complex plant defences. Among diverse pathogens, phytoplasmas are associated with serious diseases in a range of species. RNA silencing serves as an efficient defence system against pathogens in eukaryotes but can be interrupted by RNA silencing suppressors (RSSs) encoded by pathogens. Currently, many RSSs have been identified in viruses, bacteria, oomycetes and fungi. Phytoplasmas are pathogens in several hundred plant species. In this research, 37 candidate effectors of wheat blue dwarf (WBD) phytoplasma were screened for presence of RSS. Agro-infiltration assay, yeast expression system, floral-dip method for constructing transgenic A. thaliana, Western blotting and RT-qPCR were used for identification of RNA silencing suppressors. SWP16 encoded by WBD phytoplasma was found to be a secretory protein that inhibited accumulation of GFP siRNA and led to the accumulation of GPF mRNA in systemic N. benthamiana 16c. Furthermore, in A. thaliana SWP16 inhibited production of miRNAs, which are components of RNA silencing. SWP16 also promoted infection of potato virus X. We conclude that SWP16 encoded by WBD phytoplasma was an RSS, suppressing systemic RNA silencing. This is the first evidence that a phytoplasma encodes an RSS and provides a theoretical basis for research on the interaction mechanisms between pathogens and plants.

Divergent bacterial transformation exerted by soil minerals

As one of the horizontal gene transfer processes, transformation provides bacteria flexible adaptation to changing environmental conditions. Soil minerals have been shown to inhibit bacterial transformation efficiency due to their high adsorption affinity for DNA molecules. However, the intrinsic mechanisms in regulating genetic transformation by soil components remain elusive. Little is known whether bacterial exposure to minerals may influence competence development which is regarded as a prerequisite of bacterial transformation. In this study, we examined the effects of kaolinite, montmorillonite, and goethite on the transformation of B. subtilis via chemical adsorption, Live-Dead staining, β-galactosidase assay, and qPCR. Results showed that kaolinite and montmorillonite reduced the transformability of B. subtilis by strong adsorption of CSF (competence-stimulating factor), a signaling molecule of cell competence, and the down-regulated transcriptional genes resulting from suppressed competence development. Conversely, goethite depressed bacterial transformation only at low mineral content by DNA adsorption. The striking membrane damage on B. subtilis in presence of high content of goethite yielded a marked increase of bacterial transformation. This finding subverted our previous view regarding the impact of soil minerals on bacterial transformation. Three mechanisms were thus proposed governing bacterial transformation in mineral systems: adsorption of CSF, gene expression and membrane damage. This work has advanced our understanding on the genetic transformation of bacteria as influenced by minerals in a wide range of soils and associated environments.

Retrospective analysis of molecular biology mechanism of ABO blood group typing discrepancy among blood donors in Jinan blood station

BACKGROUND

To accurately identify ABO blood typing in pre-transfusion testing is very important to ensure blood transfusion safely, which is a major responsibility of blood station.

METHODS

Eighty-one blood donors samples with ABO blood group typing discrepancy was collected among 61952 donor samples in our blood station from January 2019 to July 2020. Blood group serological method was used to detect ABO blood group. DNA Sequencing was used to determine the genotype. The antibody screening test detects antibodies other than ABO.

RESULTS

In total, 61,952 donor samples were analysed for ABO typing discrepancies. The incidence among blood donors was 0.13% (81/61952). The most common reason of ABO typing discrepancies was due to specific antibody or non-specific agglutination (54.32%, 44/81), mainly anti-M antibody, cold autoantibody, anti-D antibody, anti-N antibody and anti-Lea antibody. The major cause of forward typing discrepancies among blood donors was ABO subgroups (25.93%, 21/81), including 10 cases of A subtype (1 case of A2, 2 cases of A3, 2 cases of Ax, 3 cases of AxB, 1 case of Ael, 1 case of Ahm), 6 cases of B subtype (2 cases of B3, 1 case of Bel, 3 cases of AB3), 2 cases of B subtype (A), 1 case of cisAB, and 2 cases of acquired B. The serum antibody was weakened in 16 cases (19.75%).

CONCLUSIONS

The blood types should be correctly identified by combining serology with gene sequencing to ensure the safety of clinical blood transfusion, when the forward and reverse typing discrepancies among the blood donors.

[Application of aMAP score to assess the risk of hepatocarciongenesis in population of chronic liver disease in primary hospitals]

Objective: The aMAP score is a hepatocellular carcinoma (HCC) risk prediction model based on an international cooperative cohort, which can be applied to various liver diseases. The aim of this study is to use the aMAP score to stratify the risk of HCC in patients with chronic liver disease (combined or non-combined metabolic diseases) admitted to People's Hospital of Yudu County, Ganzhou City, Jiangxi Province, in order to guide personalized HCC screening. Methods: The demographic information, laboratory test results (platelets, albumin, and total bilirubin) and combined disease information of patients with chronic liver disease who were admitted to People's Hospital of Yudu from January 2016 to December 2020 were collected, and the aMAP score was calculated to stratify HCC risk in this population. Results: A total of 3629 cases with chronic liver disease were included in the analysis, including 3 452 (95.1%) cases with hepatitis B virus (HBV) infection, 177 (4.9%) cases with fatty liver, and 22 (0.6%) cases with HBV infection and fatty liver. There were 2 679 (73.8%) male and the median age was 44 (35, 54). In the overall population, low, medium and high risk of HCC accounted for 52.6%, 29.0%, and 18.4% respectively. In the HBV-infected population, the proportion of high risk of HCC was significantly higher than that of fatty liver (18.9% vs. 9.6%, P = 0.001). The proportion of chronic liver disease patients with combined hypertension or diabetes was significantly higher than that of those with non-combined metabolic diseases (combined hypertension: 32.3% vs. 17.9%, P < 0.001; combined diabetes: 36.5% vs. 18.1%, P < 0.001). Moreover, the proportion of high-risk population with two metabolic diseases was significantly higher than that with one and no metabolic diseases (40.9% vs. 31.8% vs. 17.7%, P < 0.001). Conclusion: The aMAP score can be used as a simple tool for HCC screening and management of chronic liver disease in primary hospitals, and it is helpful to improve the personalized follow-up management system of chronic liver disease population. Chronic liver disease patients with metabolic diseases have a higher risk of HCC, and people with high risk of HCC should be given special priority in follow-up visits, so as to improve the rate of HCC early diagnosis and reduce the mortality rate.

[Establishing an integrated hospital-community pyramid for screening and achieving hepatocellular carcinoma early diagnosis and treatment]

The comprehensive management of hepatocellular carcinoma (HCC) is a complete, dynamic and personalized process. Therefore, how to scientifically determine the HCC high-risk/extremely high-risk populations and develop a stratified monitoring plan is the key link to early detection, diagnosis and improvement of overall survival. In addition, accurately identifying high-risk/extremely high-risk groups based on the HCC risk prediction model, and applying it to establish an integrated hospital-community pyramid for HCC screening through the implementation of interdisciplinary scientific management and treatment may ultimately reduce HCC-related mortality rate.

Microscale heterogeneity of the soil nitrogen cycling microbial functional structure and potential metabolism

Soil aggregates, with complex spatial and nutritional heterogeneity, are clearly important for regulating microbial community ecology and biogeochemistry in soils. However, how the taxonomic composition and functional attributes of N-cycling-microbes within different soil particle-size fractions under a long-term fertilization treatment remains largely unknown. Here, we examined the composition and metabolic potential for urease activity, nitrification, N₂ O production and reduction of the microbial communities attached to different sized soil particles (2000-250, 250-53 and <53 μm) using a functional gene microarray (GeoChip) and functional assays. We found that urease activity and nitrification were higher in <53 μm fractions, whereas N₂ O production and reduction rates were greater in 2000-250 and 250-53 μm across different fertilizer regimes. The abundance of key N-cycling genes involved in anammox, ammonification, assimilatory and dissimilatory N reduction, denitrification, nitrification and N₂ -fixation detected by GeoChip increased as soil aggregate size decreased; and the particular key genes abundance (e.g., ureC, amoA, narG, nirS/K) and their corresponding activity were uncoupled. Aggregate fraction exerted significant impacts on N-cycling microbial taxonomic composition, which was significantly shaped by soil nutrition. Taken together, these findings indicate the important roles of soil aggregates in differentiating N-cycling metabolic potential and taxonomic composition, and provide empirical evidence that nitrogen metabolism potential and community are uncoupled due to aggregate heterogeneity.

[Role and related mechanism of Mst-1 on regulating hypoxic reoxygenation induced autophagy and apoptosis in cardiomyocytes of mouse]

Objective: To explore the role and related mechanism of mammalian sterile 20-like kinase 1(Mst-1)in regulating hypoxia reoxygenation (HR) induced myocardial cell autophagy and apoptosis. Methods: Enzyme digestion method combined with differential adherent method was used to culture neonatal mouse myocardial cells. HR model was established by hypoxia for 24 hours and reoxygenation for 6 hours. The experimental groups including control group (normal cultured cardiomyocytes), Mst-1 empty virus group (cardiomyocytes transfected with recombinant lentiviral empty vector for 48 hours), Mst-1 knockdown group (recombinant lentivirus carrying Mst-1small interfering RNA (siRNA) was transfected into cardiomyocytes for 48 hours), Mst-1 overexpression group (cardiomyocytes were transfected with recombinant lentivirus carrying Mst-1 gene for 48 hours), HR group (cardiomyocytes exposed to HR), Mst-1 knockdown+HR group (HR model of cardiomyocyte was established 48 hours after transfection with recombinant lentivirus carrying Mst-1siRNA) and Mst-1 overexpression+HR group (HR model of cardiomyocyte was established 48 hours after transfection with recombinant lentivirus carrying Mst-1 gene). Real-time fluorescence quantitative RCR (qPCR) and Western blot were used to detect the relative expression of Mst-1 mRNA and protein in the cells, immunofluorescence staining was used to detect cardiomyocyte troponin T (cTnT), and autophagosomes and autophagy enzyme changes. TUNEL method was used to detect myocardial cell apoptosis, Western blot was adopted to detect autophagy-related protein microtubule-related protein 1 light chain 3 (LC3) Ⅱ/LC3 Ⅰ, P62 and apoptosis-related protein cleaved-caspase 9, pro-caspase 9, cleaved-caspase-3, pro-caspase-3, and myeloid leukemia 1 (MCL-1) expression. MCL-1 inhibitor A1210477 was used to validate the signaling pathway of Mst-1 on regulating cardiomyocyte apoptosis and autophagy. Results: Immunofluorescence detection revealed that the cultured cells expressed cardiomyocyte-specific marker cTnT. The expression of Mst-1 in cardiomyocytes increased in HR model. Lentiviral transfection could effectively inhibit or overexpress Mst-1 in treated cells. The levels of autophagosomes and autophagolysosomes in cardiomyocytes undergoing HR and in Mst-1 overexpression+HR group were lower than those of control group, while autophagosomes and autophagolysosomes in cardiomyocytes of Mst-1 knockdown+HR group was significantly higher than in the HR group (all P<0.05). The TUNEL results showed that the proportion of TUNEL positive cells was significantly increased in the HR group and Mst-1 overexpression+HR group than in the control group, while the proportion of TUNEL positive cells was significantly decreased in the Mst-1 knockdown group+HR group as compared to the HR group (all P<0.05). Western blot results showed that the LC3 Ⅱ/LC3 Ⅰ levels were significantly lower, while the expression levels of P62, cleaved-caspase-9 and cleaved-caspase-3 were significantly higher in the HR group and Mst-1 overexpression+HR group than in control group (all P<0.05). The LC3 Ⅱ/LC3 Ⅰ value was significantly higher, and the expression levels of P62, cleaved-caspase-9 and cleaved-caspase-3 were significantly lower in the Mst-1 knockdown+HR group than in the HR group (P both<0.05). The expression level of P-MCL-1 protein was significantly lower in cardiomyocytes of HR and Mst-1 overexpression+HR group than in control group, and the expression level of P-MCL-1 protein was higher in Mst-1 knockdown+HR group than in HR group (P both<0.05). The recovery experiment showed that inhibiting MCL-1 in cells can block the regulatory effect of Mst-1 siRNA on cell autophagy and apoptosis. Conclusion: Inhibiting Mst-1 expression in cardiomyocytes can promote the autophagy of cardiomyocytes induced by hypoxic reoxygenation and reduce the apoptosis of cardiomyocytes via activating McL-1.