[Mechanism of total glucosides of White Paeony Capsules in ameliorating acute lung injury based on NLRP3 inflammasome].

This study deciphered the ameliorating effect and molecular mechanism of the total glucosides of White Paeony Capsules(TGP) in the treatment of mice model with acute lung injury(ALI) via NOD-like receptor thermal protein domain associated protein 3(NLRP3) signaling pathway of the inflammasome. The study established an inflammasome activation model of primed bone marrow-derived macrophages(BMDMs), and its molecular mechanism was investigated by Western blot(WB), immunofluorescence staining, enzyme-linked immunosorbent assay(ELISA), and flow cytometry. C57BL/6J mice were randomly divided into a blank control group, a TGP group, a model group(LPS group), LPS+low-and high-dose TGP groups, LPS+MCC950 group, and LPS+MCC950+TGP group, with eight mice per group. The ALI model was induced in mice. Finally, bronchoalveolar lavage fluid(BALF) and lung tissue were collected. Lung index and lung weight wet-to-dry ratio were determined for each group of mice. The pathological changes in lung tissue were observed through hematoxylin-eosin(HE) staining. The number of neutrophils in the BALF of each group was detected using flow cytometry. The levels of interleukin(IL)-1ß, IL-6, and tumor necrosis factor(TNF)-α in the BALF were determined by ELISA. The expressions of IL-1ß, IL-18, IL-6, and TNF-α in the lung tissue were determined by real-time quantitative PCR(RT-qPCR). This study demonstrated that TGP dramatically blocked the activation of the NLRP3 inflammasome by inhibiting the production of upstream mitochondrial reactive oxygen species(mtROS) and the subsequent oligomerization of apoptosis-associated specks(ASC). Additionally, in the ALI mice model, compared with the blank control group, the model group showed alveolar structure rupture, thic-kening of alveolar septa, and dramatically increased lung index, lung weight wet-to-dry ratio in lung tissue, neutrophil count, and inflammatory factor levels. Compared with the model group, the pathological morphology of lung tissue was significantly ameliorated in the TGP and MCC950 groups, and the lung index and lung weight wet-to-dry ratio were significantly reduced. Neutrophil counts were reduced, and levels of inflammatory factors were significantly downregulated. Notably, compared with the MCC950 group, there was no significant difference in effect in the MCC950+TGP group. Collectively, the study reveals that TGP may ameliorate ALI in mice by inhibiting the activation of NLRP3 inflammasome, providing a safe and effective drug candidate for the prevention or treatment of ALI/ARDS.

Glabridin improves autoimmune disease in Trex1-deficient mice by reducing type I interferon production.

BACKGROUND: The cGAS-STING signaling pathway is an essential section of the natural immune system. In recent years, an increasing number of studies have shown a strong link between abnormal activation of the cGAS-STING signaling pathway, a natural immune pathway mediated by the nucleic acid receptor cGAS, and the development and progression of autoimmune diseases. Therefore, it is important to identify an effective compound to specifically downregulate this pathway for disease. METHODS: The effect of Glabridin (Glab) was investigated in BMDMs and Peripheral blood mononuclear cell (PBMC) by establishing an in vitro model of cGAS-STING signaling pathway activation. An activation model stimulated by DMXAA was also established in mice to study the effect of Glab. On the other hand, we investigated the possible mechanism of action of Glab and the effect of Glab on Trex1-deficient mice. RESULTS: In this research, we report that Glab, a major component of licorice, specifically inhibits the cGAS-STING signaling pathway by inhibiting the level of type I interferon and inflammatory cytokines (IL-6 and TNF-α). In addition, Glab has a therapeutic effect on innate immune diseases caused by abnormal cytoplasmic DNA in Trex1-deficient mice. Mechanistically, Glab can specifically inhibit the interaction of STING with IRF3. CONCLUSION: Glab is a specific inhibitor of the cGAS-STING signaling pathway and may be used in the clinical therapy of cGAS-STING pathway-mediated autoimmune diseases.

Tanshinone I specifically suppresses NLRP3 inflammasome activation by disrupting the association of NLRP3 and ASC.

BACKGROUND: Abnormal activation of NLRP3 inflammasome is related to a series of inflammatory diseases, including type 2 diabetes, gouty arthritis, non-alcoholic steatohepatitis (NASH), and neurodegenerative disorders. Therefore, targeting NLRP3 inflammasome is regarded as a potential therapeutic strategy for many inflammatory diseases. A growing number of studies have identified tanshinone I (Tan I) as a potential anti-inflammatory agent because of its good anti-inflammatory activity. However, its specific anti-inflammatory mechanism and direct target are unclear and need further study. METHODS: IL-1ß and caspase-1 were detected by immunoblotting and ELISA, and mtROS levels were measured by flow cytometry. Immunoprecipitation was used to explore the interaction between NLRP3, NEK7 and ASC. In a mouse model of LPS-induced septic shock, IL-1ß levels in peritoneal lavage fluid and serum were measured by ELISA. Liver inflammation and fibrosis in the NASH model were analyzed by HE staining and immunohistochemistry. RESULTS: Tan I inhibited the activation of NLRP3 inflammasome in macrophages, but had no effect on the activation of AIM2 or NLRC4 inflammasome. Mechanistically, Tan I inhibited NLRP3 inflammasome assembly and activation by targeting NLRP3-ASC interaction. Furthermore, Tan I exhibited protective effects in mouse models of NLRP3 inflammasome-mediated diseases, including septic shock and NASH. CONCLUSIONS: Tan I specifically suppresses NLRP3 inflammasome activation by disrupting the association of NLRP3 and ASC, and exhibits protective effects in mouse models of LPS-induced septic shock and NASH. These findings suggest that Tan I is a specific NLRP3 inhibitor and may be a promising candidate for treating NLRP3 inflammasome-related diseases.

Tricyclic antidepressants induce liver inflammation by targeting NLRP3 inflammasome activation.

BACKGROUND: Idiosyncratic drug-induced liver injury (IDILI) is common in hepatology practices and, in some cases, lethal. Increasing evidence show that tricyclic antidepressants (TCAs) can induce IDILI in clinical applications but the underlying mechanisms are still poorly understood. METHODS: We assessed the specificity of several TCAs for NLRP3 inflammasome via MCC950 (a selective NLRP3 inhibitor) pretreatment and Nlrp3 knockout (Nlrp3-/-) BMDMs. Meanwhile, the role of NLRP3 inflammasome in the TCA nortriptyline-induced hepatotoxicity was demonstrated in Nlrp3-/- mice. RESULTS: We reported here that nortriptyline, a common TCA, induced idiosyncratic hepatotoxicity in a NLRP3 inflammasome-dependent manner in mildly inflammatory states. In parallel in vitro studies, nortriptyline triggered the inflammasome activation, which was completely blocked by Nlrp3 deficiency or MCC950 pretreatment. Furthermore, nortriptyline treatment led to mitochondrial damage and subsequent mitochondrial reactive oxygen species (mtROS) production resulting in aberrant activation of the NLRP3 inflammasome; a selective mitochondrial ROS inhibitor pretreatment dramatically abrogated nortriptyline-triggered the NLRP3 inflammasome activation. Notably, exposure to other TCAs also induced aberrant activation of the NLRP3 inflammasome by triggering upstream signaling events. CONCLUSION: Collectively, our findings revealed that the NLRP3 inflammasome may act as a crucial target for TCA agents and suggested that the core structures of TCAs may contribute to the aberrant activation of NLRP3 inflammasome induced by them, an important factor involved in the pathogenesis of TCA-induced liver injury. Video Abstract.

[Preventive and therapeutic effect of bioactive component of licorice on antidepressant-induced liver injury].

Since exploding rates of modern mental diseases, application of antidepressants has increased. Worryingly, the antidepressant-induced liver injury has gradually become a serious health burden. Furthermore, since most of the knowledge about antidepressant hepatotoxicity are from pharmacovigilance and clinical case reports and lack of observational studies, the underlying mechanisms are poorly understood and there is a lack of efficient treatment strategies. In this study, antidepressant paroxetine directly triggered inflammasome activation evidenced by caspase-1 activation and downstream effector cytokines interleukin(IL)-1ß secretion. The pretreatment of echinatin, a bioactive component of licorice, completely blocked the activation. This study also found that echinatin effectively inhibited the production of inflammasome-independent tumor necrosis factor α(TNF)-α induced by paroxetine. Mechanistically, the accumulation of mitochondrial reactive oxygen species(mtROS) was a key upstream event of paroxetine-induced inflammasome activation, which was dramatically inhibited by echinatin. In the lipopolysaccharide(LPS)-mediated idiosyncratic drug-induced liver injury(IDILI) model, the combination of LPS and paroxetine triggered aberrant activation of the inflammasome to induce idiosyncratic hepatotoxicity, which was reversed by echinatin pretreatment. Notably, this study also found that various bioactive components of licorice had an inhibitory effect on paroxetine-triggered inflammasome activation. Meanwhile, multiple antidepressant-induced aberrant activation of the inflammasome could be completely blocked by echinatin pretreatment. In conclusion, this study provides a novel insight for mechanism of antidepressant-induced liver injury and a new strategy for the treatment of antidepressant-induced hepatotoxicity.

LicochalconeB inhibits cGAS-STING signaling pathway and prevents autoimmunity diseases.

Cytosolic DNA activates the STING (stimulator of interferon genes) signaling pathway to trigger interferon and inflammatory responses that protect against microbial infections and cancer. However, Aicardi-Goutières syndrome (AGS) persistently activates the STING signaling pathway, which can lead to severe autoimmune diseases. We demonstrate herein that Licochalcone B (LicoB), the main component of traditional licorice, is an inhibitor of the STING signaling pathway. We observed that LicoB inhibited the activation of the STING signaling pathway in macrophages. Mechanically, LicoB affected the STING-TBK1-IRF3 signal axis and inhibited the activation of the STING downstream signaling pathway. Furthermore, LicoB inhibited the increase in type I interferon levels in mice induced by the STING agonist CMA. LicoB significantly reduced systemic inflammation in Trex1-/- mice. Our results show that LicoB, a STING signaling pathway inhibitor, is a promising candidate for the treatment of diseases related to STING signaling pathway activation.

Licorice extract inhibits the cGAS-STING pathway and protects against non-alcoholic steatohepatitis.

Background: Inflammation and fibrosis are typical symptoms of non-alcoholic steatohepatitis (NASH), which is one of the most common chronic liver diseases. The cGAS-STING signaling pathway has been implicated in the progression of NASH, and targeting this pathway may represent a new therapeutic strategy. Licorice is a widely used herb with anti-inflammatory and liver-protective properties. In this study, we assessed the effect of licorice extract on the cGAS-STING pathway. Methods: Bone marrow-derived macrophages (BMDMs) were treated with licorice extract and then stimulated with HT-DNA, 2'3'-cGAMP, or other agonists to activate the cGAS-STING pathway. Quantitative real-time PCR and western blot were conducted to analyze whether licorice extract could affect the cGAS-STING pathway. Methionine and choline-deficient diet (MCD) was used to induce NASH in mice, which were treated with licorice extract (500 mg/kg) by gavage and/or c-176 (15 mg/kg) by intraperitoneal injection every 2 days. After 6 weeks of treatment, histological analysis of liver tissue was performed, along with measurements of plasma biochemical parameters. Results: Licorice extract inhibits cGAS-STING pathway activation. Mechanistically, it might function by inhibiting the oligomerization of STING. Treatment with licorice extract reduced inflammation and fibrosis in MCD diet-induced NASH mice models. Furthermore, we found that the therapeutic effect of combination treatment with licorice extract and C-176 (STING inhibitor) on the pathology and fibrosis of MCD diet-induced NASH models was similar to that of licorice extract or C-176 administered alone. Conclusion: Licorice extract can inhibit the cGAS-STING pathway and improve hepatic inflammation and fibrosis in NASH mice models. It strongly suggests that licorice extract may be a candidate therapeutic for NASH.

Schisandrin C enhances cGAS-STING pathway activation and inhibits HBV replication.

ETHNOPHARMACOLOGICAL RELEVANCE: Schisandra Chinensis (Turcz.) Baill. is a long-term used traditional Chinese medicine with the functions of tonifying the kidney and calming the heart, tonifying qi and engendering fluid. It can be used to treat insomnia and dreaminess, spermatorrhea, coughs, as well as liver and kidney deficiency of Yin or Yang Syndrome. Modern pharmacological studies have shown that Schisandra Chinensis regulates host immunity and exhibits anti-cancer, antiviral and liver-protecting effects. However, the specific mechanism by which Schisandra Chinensis modulates antiviral immunity is unknown. AIM OF THE STUDY: We sought to explore the therapeutic effect of the active components of Schisandra Chinensis on anti-viral immunity and further investigate the underlying mechanism. MATERIALS AND METHODS: Immunoblotting, quantitative real-time PCR, enzyme-linked immunosorbent assay, immunofluorescence, and immunoprecipitation were used to investigate the effect of schisandrin C (SC), one of the most abundant and biologically active components of Schisandra Chinensis, on the activation of cGAS-STING signaling pathway and the underlying mechanism. In addition, CMA-mediated STING activation and hydrodynamic injection-mediated HBV-replicating mouse model were used to investigate the effect of SC on the activation of STING signaling pathway and its antiviral effect in vivo. RESULTS: SC promoted cGAS-STING pathway activation, accompanied by increased production of interferon ß (IFN ß) and downstream gene expression. Moreover, SC also exerted anti-HBV effects, reducing HBeAg, HBcAg, HBsAg, and HBV DNA levels in hydrodynamic injection-mediated HBV-replicating mouse model and elevating the production of IFN ß and expression of interferon-stimulated genes (IFIT1, ISG15, and CXCL10). Mechanistically, SC could facilitate the interaction between TANK-binding kinase 1 (TBK1) and STING, which is important for IRF3 phosphorylation and production of IFN ß. CONCLUSIONS: Our study confirmed that SC enhances cGAS-STING pathway activation and inhibits HBV replication, as well as provides clues for chronic hepatitis B and other infectious diseases treated by SC.

Flavonoids derived from licorice suppress LPS-induced acute lung injury in mice by inhibiting the cGAS-STING signaling pathway.

In recent years, we have found that the dysregulation of the cyclic-GMP-AMP synthase (cGAS)‒stimulator of interferon genes (STING) pathway leads to the development of immune and inflammatory diseases, therefore, finding compounds that can specifically regulate this pathway is essential for effective regulation of the immune pathway for addressing inflammatory diseases. Licorice flavonoids (LFs), are active ingredients extracted from the Chinese herb licorice, which has been reported to have strong anti-inflammatory activity in previous studies. Here, we report that LFs inhibit the activation of the cGAS-STING pathway evidenced by the inhibition of the expression of type I interferons and related downstream genes such as interferon-stimulated gene 15 (ISG15) and C-X-C motif chemokine ligand 10 (CXCL10), as well as inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Notably, LFs markedly improve the LPS-induced acute lung injury by inhibiting the excessive activation of cGAS-STING signaling pathway. Mechanistically, LFs treatment leads to the blocking of 2'3'-cyclic GMP-AMP (cGAMP) synthesis resulting in an inhibition of the activation of the cGAS-STING pathway. Our results indicate that LFs is a specific inhibitor of the cGAS-STING pathway, which is suggested to be a potential candidate for the treatment of cGAS-STING pathway-mediated inflammatory diseases.

Schisandra chinensis Oil Attenuates Aristolochic Acid I-Induced Nephrotoxicity in vivo and in vitro.

OBJECTIVE: To investigate the protective effects of Schisandra chinensis oil (SCEO) against aristolochic acid I (AA I)-induced nephrotoxicity in vivo and in vitro and elucidate the underlying mechanism. METHODS: C57BL/6 mice were randomly divided into 5 groups according to a random number table, including control group, AA I group, and AA I +SCEO (0.25, 0.5 and 1 g/kg) groups (n=5 per group). Pretreatment with SCEO was done for 2 days by oral administration, while the control and AA I groups were treated with sodium carboxymethyl cellulose. Mice of all groups except for the control group were injected intraperitoneally with AA I (5 mg/kg) from day 3 until day 7. Histopathological examination and apoptosis of kidney tissue were observed by hematoxylin and eosin and TdT-mediated dUTP nick-end labeling (TUNEL) staining, respectively. The levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and serum creatinine (SCr), as well as renal malondialdehyde (MDA), glutathione, r-glutamyl cysteingl+glycine (GSH), and superoxide dismutase (SOD) were analyzed using enzyme-linked immunosorbent assay (ELISA). Expressions of hepatic cytochrome P450 1A1 (CYP1A1), CYP1A2, and nad(p)hquinonedehydrogenase1 (NQO1) were analyzed using ELISA, quantitative real-time polymerase chain reaction (qPCR) and Western blot, respectively. In vitro, SCEO (40 µ g/mL) was added 12 h before treatment with AA I (40 µ mol/mL for 48 h) in human renal proximal tubule cell line (HK-2), then apoptosis and reactive oxygen species (ROS) were analyzed by flow cytometry. RESULTS: SCEO 0.5 and 1 g/kg ameliorated histopathological changes and TUNEL+ staining in the kidney tissues of mice with AA I-induced nephrotoxicity, and reduced serum levels of ALT, AST, BUN and SCr (P<0.01 or P<0.05). SCEO 0.5 and 1 g/kg alleviated the ROS generation in kidney, containing MDA, GSH and SOD (P<0.01 or P<0.05). SCEO 1 g/kg increased the expressions of CYP1A1 and CYP1A2 and decreased NQO1 level in the liver tissues (P<0.01 or P<0.05). Besides, in vitro studies also demonstrated that SCEO 40 µ g/mL inhibited apoptosis and ROS generation (P<0.05 or P<0.01). CONCLUSIONS: SCEO can alleviate AA I-induced kidney damage both in vivo and in vitro. The protective mechanism may be closely related to the regulation of metabolic enzymes, thereby inhibiting apoptosis and ROS production.

Integration of Transcriptomic and Metabolomic Data to Compare the Hepatotoxicity of Neonatal and Adult Mice Exposed to Aristolochic Acid I.

Aristolochic acid (AA) is a group of structurally related compounds what have been used to treat various diseases in recent decades. Aristolochic acid I (AAI), an important ingredient, has been associated with tumorigenesis. Recently, some studies indicated that AAI could induce liver injury in mice of different age, but comprehensive mechanisms of AAI-induced differences in liver injury in various age groups have not yet been elucidated. This study aims to evaluate the causal relationship between AAI-induced liver injury and age based on neonatal mice and adult mice. A survival experiment indicated that all neonatal mice survived. Moreover, the adult mice in the high-dose AAI group all died, whereas half of the adult mice in the low-dose AAI group died. In observation experiments, AAI induced more severe liver injury in neonatal mice than adult mice under long-term than short-term exposure. Furthermore, integrated metabolomics and transcriptomics indicated that AAI disturbing steroid hormone biosynthesis, arachidonic acid metabolism, the drug metabolism-cytochrome P450 pathway and glycerophospholipid metabolism induced neonatal mice liver injury. The important role of age in AAI-induced liver injury was illustrated in our study. This study also lays a solid foundation for scientific supervision of AA safety.

The role of NLRP3 inflammasome in psychotropic drug-induced hepatotoxicity.

Increased medical application of psychotropic drugs raised attention concerning their toxicological effects. In fact, more than 160 psychotropic drugs including antidepressants and antipsychotics, have been shown to cause liver side effects, but the underlying mechanisms are still poorly understood. Here, we discovered that fluoxetine, a common antidepressant, was specifically sensed by NLRP3 inflammasome, whose subsequent activation resulted in the maturation of caspase-1 and IL-1ß, as well as gasdermin D (GSDMD) cleavage, which could be completely abrogated by a selective NLRP3 inhibitor MCC950 or Nlrp3 knockout (Nlrp3-/-). Mechanistically, mitochondrial damage and the subsequent mitochondrial reactive oxygen species (mtROS) accumulation were crucial upstream signaling events in fluoxetine-triggered NLRP3 inflammasome activation. In fluoxetine hepatotoxicity models, mice showed the alterations of aminotransferase levels, hepatic inflammation and hepatocyte death in an NLRP3-dependent manner, and MCC950 pretreatment could reverse these side effects of fluoxetine. Notably, we also found that multiple antidepressants, such as amitriptyline, paroxetine, and imipramine, and antipsychotics, such as asenapine, could specifically trigger the NLRP3 inflammasome activation. Collectively, our findings implicate multiple psychotropic drugs may act as danger signals sensed by the NLRP3 inflammasome and result in hepatic injury.

The Combination of Schisandrol B and Wedelolactone Synergistically Reverses Hepatic Fibrosis Via Modulating Multiple Signaling Pathways in Mice.

Hepatic fibrosis represents an important event in the progression of chronic liver injury to cirrhosis, and is characterized by excessive extracellular matrix proteins aggregation. Early fibrosis can be reversed by inhibiting hepatocyte injury, inflammation, or hepatic stellate cells activation, so the development of antifibrotic drugs is important to reduce the incidence of hepatic cirrhosis or even hepatic carcinoma. Here we demonstrate that Schisandrol B (SolB), one of the major active constituents of traditional hepato-protective Chinese medicine, Schisandra sphenanthera, significantly protects against hepatocyte injury, while Wedelolactone (WeD) suppresses the TGF-ß1/Smads signaling pathway in hepatic stellate cells (HSCs) and inflammation, the combination of the two reverses hepatic fibrosis in mice and the inhibitory effect of the combination on hepatic fibrosis is superior to that of SolB or WeD treatment alone. Combined pharmacotherapy represents a promising strategy for the prevention and treatment of liver fibrosis.

Corrigendum: The Combination of Schisandrol B and Wedelolactone Synergistically Reverses Hepatic Fibrosis via Modulating Multiple Signaling Pathways in Mice.

[This corrects the article DOI: 10.3389/fphar.2021.655531.].

Curdione and Schisandrin C Synergistically Reverse Hepatic Fibrosis via Modulating the TGF-ß Pathway and Inhibiting Oxidative Stress.

Hepatic fibrosis is the final pathway of several chronic liver diseases, which is characterized by the accumulation of extracellular matrix due to chronic hepatocyte damage. Activation of hepatic stellate cells and oxidative stress (OS) play an important role in mediating liver damage and initiating hepatic fibrosis. Hence, hepatic fibrosis can be reversed by inhibiting multiple channels such as oxidative stress, liver cell damage, or activation of hepatic stellate cells. Liuwei Wuling Tablets is a traditional Chinese medicine formula with the effect of anti- hepatic fibrosis, but the composition and mechanism of reversing hepatic fibrosis are still unclear. Our study demonstrated that one of the main active components of the Chinese medicine Schisandra chinensis, schisandrin C (Sin C), significantly inhibited oxidative stress and prevented hepatocyte injury. Meanwhile one of the main active components of the Chinese medicine Curdione inhibited hepatic stellate cell activation by targeting the TGF-ß1/Smads signaling pathway. The further in vivo experiments showed that Sin C, Curdione and the combination of both have the effect of reversing liver fibrosis in mice, and the combined effect of inhibiting hepatic fibrosis is superior to treatment with Sin C or Curdione alone. Our study provides a potential candidate for multi-molecular or multi-pathway combination therapies for the treatment of hepatic fibrosis and demonstrates that combined pharmacotherapy holds great promise in the prevention and treatment of hepatic fibrosis.

Temperature governs the distribution of hot spring microbial community in three hydrothermal fields, Eastern Tibetan Plateau Geothermal Belt, Western China.

The eastern Tibetan Plateau geothermal belt in the southwest of China hosts a number of hot springs with a wide range of temperature and hydrogeochemical conditions, which may harbor different niches for the distribution of microbial communities. In this study, we investigated hydrochemical characteristics and microbial community composition in 16 hot springs with a temperature range of 34.6 to 88.2 °C within and across three typical hydrothermal fields (Kangding, Litang, and Batang). According to aquifer lithologic and tectonic differences, the hydrochemical compositions of hot springs displayed an apparent regional-specific pattern with distinct distributions of major and trace elements (e.g., Ca2+, Mg2+, F-/B) and were primarily formed by water-rock interaction across the three hydrothermal fields. Nonetheless, microbial communities significantly assembled with the temperature rather than the geographic locations with distinct hydrogeological features. Low temperature (<45 °C), moderate temperature (55-70 °C) and high temperature (>70 °C) groups were identified based on their community compositions. Proteobacteria and Nitrospirae were the predominant phyla in low-temperature hot springs, while in moderate to high-temperature springs they were mainly composed of Aquificae, Deinococcus-Thermus, Thermodesulfobacteria, Thermotogae and Cyanobacteria. Variation partition analysis suggested a higher explanation of temperature (29.6%) than spatial variable (1.8%) and other geochemical variables (2.5%) on the microbial distribution. Microbial co-occurrence network showed >80% negative associations hinting a low co-existence pattern and highlighted the driving force of temperature as well as F- or total organic carbon (TOC) for microbial interactions. Microbial dissimilarity displayed significant linear correlations with environmental (temperature) and geographic distance in Batang but only with temperature in Kangding area, which might be attributed to the regional-specific hydrogeochemistry. This study may help us to better understand the distribution of the microbial community in hot spring across different hydrothermal fields.

Identifying locations and sources of groundwater discharge into Poyang Lake (eastern China) using radium and stable isotopes (deuterium and oxygen-18).

Knowledge of groundwater discharge (location and sources) into Poyang Lake is needed for water resources management and ecological security. In this study, hydrochemical and stable (δD and δ18O) and radium (223Ra, 224Ra, 226Ra, and 228Ra) isotopic approaches were employed to study the hydrochemical and isotopic characteristics of groundwater and surface water (river water and lake water) to identify the places where groundwater discharged into Poyang Lake and the groundwater discharge sources. The results showed that the groundwater discharge area was extensive during the dry season. The locations of predominant groundwater discharge were indicated by the evolution of radium and stable isotopes in lake water along two water flow profiles. At the confluence of Ganjiang and Xiushui rivers, groundwater with more negative δ18O value than that of the lake water discharged into this area, and the estimated groundwater discharge proportion in this area was close to that of the river water input. The main sources of groundwater input for Poyang Lake were inferred to originate from clastic rock pore-fissure aquifer and bedrock fissured aquifer around this lake. This study also found that groundwater affected by the anthropogenic activities may have discharged into Poyang Lake. Future studies are required to focus on groundwater discharge into Poyang Lake for its management and protection.