Adaptive evolution of carbapenem-resistant hypervirulent Klebsiella pneumoniae in the urinary tract of a single patient.

The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) is a growing concern due to its high mortality and limited treatment options. Although hypermucoviscosity is crucial for CR-hvKp infection, the role of changes in bacterial mucoviscosity in the host colonization and persistence of CR-hvKp is not clearly defined. Herein, we observed a phenotypic switch of CR-hvKp from a hypermucoviscous to a hypomucoviscous state in a patient with scrotal abscess and urinary tract infection (UTI). This switch was attributed to decreased expression of rmpADC, the regulator of mucoid phenotype, caused by deletion of the upstream insertion sequence ISKpn26. Postswitching, the hypomucoid variant showed a 9.0-fold decrease in mice sepsis mortality, a >170.0-fold reduction in the ability to evade macrophage phagocytosis in vitro, and an 11.2- to 40.9-fold drop in growth rate in normal mouse serum. Conversely, it exhibited an increased residence time in the mouse urinary tract (21 vs. 6 d), as well as a 216.4-fold boost in adhesion to bladder epithelial cells and a 48.7% enhancement in biofilm production. Notably, the CR-hvKp mucoid switch was reproduced in an antibiotic-free mouse UTI model. The in vivo generation of hypomucoid variants was primarily associated with defective or low expression of rmpADC or capsule synthesis gene wcaJ, mediated by ISKpn26 insertion/deletion or base-pair insertion. The spontaneous hypomucoid variants also outcompeted hypermucoid bacteria in the mouse urinary tract. Collectively, the ISKpn26-associated mucoid switch in CR-hvKp signifies the antibiotic-independent host adaptive evolution, providing insights into the role of mucoid switch in the persistence of CR-hvKp.

A Universal Approach for Controllable Synthesis of Homogeneously Alloyed PtM Nanoflowers toward Enhanced Methanol Oxidation.

Platinum (Pt)-based alloys have received considerable attention due to their compositional variability and unique electrochemical properties. However, homogeneous element distribution at the nanoscale, which is beneficial to various electrocatalytic reactions, is still a great challenge. Herein, a universal approach is proposed to synthesize homogeneously alloyed and size-tunable Pt-based nanoflowers utilizing high gravity technology. Owing to the significant intensification of micro-mixing and mass transfer in unique high gravity shearing surroundings, five typical binary/ternary Pt-based nanoflowers are instantaneously achieved at room temperature. As a proof-of-concept, as-synthesized Platinum-Silver nanoflowers (PtAg NFs) demonstrate excellent catalytic performance and anti-CO poisoning ability for anodic methanol oxidation reaction with high mass activity of 1830 mA mgPt -1, 3.5 and 3.2 times higher than those of conventional beaker products and commercial Pt/C, respectively. The experiment in combination with theory calculations suggest that the enhanced performance is due to additional electronic transmission and optimized d-band center of Pt caused by high alloying degree.

The Influence of Seawater on Fe(II)-Catalyzed Ferrihydrite Transformation and Its Subsequent Consequences for C Dynamics.

Short-range-ordered minerals like ferrihydrite often bind substantial organic carbon (OC), which can be altered if the minerals transform. Such mineral transformations can be catalyzed by aqueous Fe(II) (Fe(II)aq) in redox-dynamic environments like coastal wetlands, which are inundated with seawater during storm surges or tidal events associated with sea-level rise. Yet, it is unknown how seawater salinity will impact Fe(II)-catalyzed ferrihydrite transformation or the fate of bound OC. We reacted ferrihydrite with Fe(II)aq under anoxic conditions in the absence and presence of dissolved organic matter (DOM). We compared treatments with no salts (DI water), NaCl-KCl salts, and artificial seawater mixes (containing Ca and Mg ions) with or without SO42-/HCO3-. Both XRD and Mössbauer showed that NaCl-KCl favored lepidocrocite formation, whereas Ca2+/Mg2+/SO42-/HCO3- ions in seawater overrode the effects of NaCl-KCl and facilitated goethite formation. We found that the highly unsaturated and phenolic compounds (HuPh) of DOM selectively bound to Fe minerals, promoting nanogoethite formation in seawater treatments. Regardless of salt presence, only 5-9% of Fe-bound OC was released during ferrihydrite transformation, enriching HuPh relative to aliphatics in solution. This study offers new insights into the occurrence of (nano)goethite and the role of Fe minerals in OC protection in coastal wetlands.

Burden of Child Anemia Attributable to Fine Particulate Matters Brought by Sand Dusts in Low- and Middle-Income Countries.

Addressing environmental factors has recently been recommended to curb the growing trend of anemia in low- and middle-income countries (LMICs). Fine particulate matter (PM2.5) generated by dust storms were concentrated in place with a high prevalence of anemia. In a multicounty, multicenter study, we analyzed the association between anemia and life-course averaged exposure to dust PM2.5 among children aged <5 years based on 0.65 million records from 47 LMICs. In the fully adjusted mixed effects model, each 10 µg/m3 increase in life-course averaged exposure to dust PM2.5 was associated with a 9.3% increase in the odds of anemia. The estimated exposure-response association was nonlinear, with a greater effect of dust PM2.5 exposure seen at low concentrations. Applying this association, we found that, in 2017, among all children aged <5 years in the 125 LMICs, dust PM2.5 contributed to 37.98 million cases of anemia. Results indicated that dust PM2.5 contributed a heavier burden than all of the well-identified risk factors did, except for iron deficiency. Our study revealed that long-term exposure to dust PM2.5 can be a novel risk factor, pronouncedly contributed to the burden of child anemia in LMICs, affected by land degradations or arid climate.

Responsive mechanism of Hemerocallis citrina Baroni to complex saline-alkali stress revealed by photosynthetic characteristics and antioxidant regulation.

KEY MESSAGE: Saline-alkali stress induces oxidative damage and photosynthesis inhibition in H. citrina, with a significant downregulation of the expression of photosynthesis- and antioxidant-related genes at high concentration. Soil salinization is a severe abiotic stress that impacts the growth and development of plants. In this study, Hemerocallis citrina Baroni was used to investigate its responsive mechanism to complex saline-alkali stress (NaCl:Na2SO4:NaHCO3:Na2CO3 = 1:9:9:1) for the first time. The growth phenotype, photoprotective mechanism, and antioxidant system of H. citrina were studied combining physiological and transcriptomic techniques. KEGG enrichment and GO analyses revealed significant enrichments of genes related to photosynthesis, chlorophyll degradation and antioxidant enzyme activities, respectively. Moreover, weighted gene co-expression network analysis (WGCNA) found that saline-alkali stress remarkably affected the photosynthetic characteristics and antioxidant system. A total of 29 key genes related to photosynthesis and 29 key genes related to antioxidant enzymes were discovered. High-concentration (250 mmol L-1) stress notably inhibited the expression levels of genes related to light-harvesting complex proteins, photosystem reaction center activity, electron transfer, chlorophyll synthesis, and Calvin cycle in H. citrina leaves. However, most of them were insignificantly changed under low-concentration (100 mmol L-1) stress. In addition, H. citrina leaves under saline-alkali stress exhibited yellow-brown necrotic spots, increased cell membrane permeability and accumulation of reactive oxygen species (ROS) as well as osmolytes. Under 100 mmol L-1 stress, ROS was eliminate by enhancing the activities of antioxidant enzymes. Nevertheless, 250 mmol L-1 stress down-regulated the expression levels of genes encoding antioxidant enzymes, and key enzymes in ascorbate-glutathione (AsA-GSH) cycle as well as thioredoxin-peroxiredoxin (Trx-Prx) pathway, thus inhibiting the activities of these enzymes. In conclusion, 250 mmol L-1 saline-alkali stress caused severe damage to H. citrina mainly by inhibiting photosynthesis and ROS scavenging capacity.

Melatonin Alleviates Lipopolysaccharide-Induced Abnormal Pregnancy through MTNR1B Regulation of m6A.

Pregnancy is a highly intricate and delicate process, where inflammation during early stages may lead to pregnancy loss or defective implantation. Melatonin, primarily produced by the pineal gland, exerts several pharmacological effects. N6-methyladenosine (m6A) is the most prevalent mRNA modification in eukaryotes. This study aimed to investigate the association between melatonin and m6A during pregnancy and elucidate the underlying protective mechanism of melatonin. Melatonin was found to alleviate lipopolysaccharide (LPS)-induced reductions in the number of implantation sites. Additionally, it mitigated the activation of inflammation, autophagy, and apoptosis pathways, thereby protecting the pregnancy process in mice. The study also revealed that melatonin regulates uterine m6A methylation levels and counteracts abnormal changes in m6A modification of various genes following LPS stimulation. Furthermore, melatonin was shown to regulate m6A methylation through melatonin receptor 1B (MTNR1B) and subsequently modulate inflammation, autophagy, and apoptosis through m6A. In conclusion, our study demonstrates that melatonin protects pregnancy by influencing inflammation, autophagy, and apoptosis pathways in an m6A-dependent manner via MTNR1B. These findings provide valuable insights into the mechanisms underlying melatonin's protective effects during pregnancy and may have implications for potential therapeutic strategies in managing pregnancy-related complications.

Mst1/2 Is Necessary for Satellite Cell Differentiation to Promote Muscle Regeneration.

The diminished ability for muscle to regenerate is associated with aging, diabetes, and cancers. Muscle regeneration depends on the activation and differentiation of satellite cells (SCs). Inactivation of Mst1/2 promotes cell proliferation by activating Yap, and that has been reported as a potential therapeutic target for improving many organ regeneration. However, the function of Mst1/2 in SCs fate decision and that effect on muscle regeneration remain unknown. By using inducible conditional knockout Mst1/2 in the SCs of mice and an inhibitor of Mst1/2, we found that inhibition of Mst1/2 in SCs significantly decrease Yap phosphorylation, thus causing Yap to accumulate in the nucleus and impairing SC differentiation; Mst1/2 were slightly elevated by irisin stimulation during SC differentiation; but inhibiting Mst1/2 in SCs significantly impaired irisin-induced muscle regeneration. These results indicate that Mst1/2 is necessary for SC differentiation and inhibiting Mst1/2 as a therapeutic target has potential risks for muscle regeneration.

Electron Transfer, Atom Exchange, and Transformation of Iron Minerals in Soils: The Influence of Soil Organic Matter.

Despite substantial experimental evidence of electron transfer, atom exchange, and mineralogical transformation during the reaction of Fe(II)aq with synthetic Fe(III) minerals, these processes are rarely investigated in natural soils. Here, we used an enriched Fe isotope approach and Mössbauer spectroscopy to evaluate how soil organic matter (OM) influences Fe(II)/Fe(III) electron transfer and atom exchange in surface soils collected from Luquillo and Calhoun Experimental Forests and how this reaction might affect Fe mineral composition. Following the reaction of 57Fe-enriched Fe(II)aq with soils for 33 days, Mössbauer spectra demonstrated marked electron transfer between sorbed Fe(II) and the underlying Fe(III) oxides in soils. Comparing the untreated and OM-removed soils indicates that soil OM largely attenuated Fe(II)/Fe(III) electron transfer in goethite, whereas electron transfer to ferrihydrite was unaffected. Soil OM also reduced the extent of Fe atom exchange. Following reaction with Fe(II)aq for 33 days, no measurable mineralogical changes were found for the Calhoun soils enriched with high-crystallinity goethite, while Fe(II) did drive an increase in Fe oxide crystallinity in OM-removed LCZO soils having low-crystallinity ferrihydrite and goethite. However, the presence of soil OM largely inhibited Fe(II)-catalyzed increases in Fe mineral crystallinity in the LCZO soil. Fe atom exchange appears to be commonplace in soils exposed to anoxic conditions, but its resulting Fe(II)-induced recrystallization and mineral transformation depend strongly on soil OM content and the existing soil Fe phases.

Mammalian sterile 20-like kinase 1 acts as a candidate biomarker of mortality of emergency surgical repair for acute type a aortic dissection.

BACKGROUND: Acute type A aortic dissection (ATAAD) is a life-threatening pathological change of the aorta. Patients who have undergone aortic surgery are usually at high risk of mortality. AIM: We investigated the predictive value of serum Mammalian sterile 20-like kinase 1 (MST1) as a biomarker for the risk of mortality of ATAAD patients. METHODS: In this retrospective cohort study, we analyzed 160 consecutive ATAAD patients who had undergone emergency surgery from July 2016 to April 2017. Medical records and blood samples were collected and analyzed. ELISA assays were performed to detect the concentrations of several proteins including MST1. The relationship between these potential biomarkers and the primary endpoint of death was evaluated using Cox proportional hazard regression analysis. RESULTS: Compared with a low level (< 1330.8 ng/L), high serum MST1 level (≥ 1330.8 ng/L) was positively associated with the 30-day mortality (OR = 5.233, 95%CI, 1.843-14.862, P < 0.01) and retained predictive after adjustment for sex, age, BMI, nasopharyngeal temperature and deep hypothermia circulatory arrest time (OR = 4.628 95% CI, 1.572-13.625, P < 0.01). A pre-existing basic clinical prediction model was improved with the inclusion of preoperative serum MST1. Specifically, the area under the ROC curve for base model (history of cerebrovascular disease, creatinine, time of operation) was 0.708 (95%CI, 0.546-0.836) and markedly increased to 0.823 when taking MST1 into consideration (95%CI, 0.700-0.912, P = 0.02). CONCLUSION: Our study suggests that high preoperative circulating MST1, with a concentration greater than 1330.8 ng/L, was correlated with the 30-day mortality of ATAAD patients who underwent emergency surgery.

Spontaneous drainage of a pancreatic pseudocyst into the stomach.

A 45-year-old woman presented with a ten-day history of abdominal pain. Laboratory examination upon admission indicated increased serum amylase level of 213 U/L (35-135 U/L). Tumor markers were within the normal range. Computed tomography (CT) of the abdomen showed a cystic mass in the greater curvature with homogeneous water like density. Similar round-like cystic masses with homogeneous water like density were also revealed in pancreas and spleen. Esophagogastroduodenoscopy revealed a eminence lesion in the fundus and corpus of the stomach. Endoscopic ultrasonography revealed a homogeneous hypoechoic mass in the fundus and corpus junction, measuring 4.6 cm × 2.7 cm. Magnetic resonance (MR) images showed multiple cystic masses with ring-like enhancement in the greater curvature, spleen and pancreatic tail. The patient was diagnosed as multiple pseudocysts due to pancreatitis and treated conservatively with anti-infection, acid suppression and inhibition of pancreatic secretion. He recovered with resolution of abdominal pain. The patient was feeling well at 8 months of follow-up.

MST1/2 in PDGFRα+ cells negatively regulates TGF-ß-induced myofibroblast accumulation in renal fibrosis.

Injury-induced fibroblast-to-myofibroblast differentiation is a key event of renal fibrosis. Yes-associated protein (YAP), a transcriptional coactivator, plays an important role in fibroblast activation and Smad transcriptional activity to promote transforming growth factor-ß (TGF-ß)-induced differentiation from fibroblasts to myofibrolasts. Macrophage stimulating 1/2 (MST1/2), a negative regulator of YAP, also increases in fibroblasts by TGF-ß stimulation. Here, we examined whether MST1/2, as a negative regulator, attenuated YAP and TGF-ß/Smad signaling in fibroblasts to reduce fibrosis. MST1/2 and YAP expression levels increased in platelet-derived growth factor receptor-α (PDGFRα)+ cells of obstructed kidneys following the increase of TGF-ß and renal fibrosis after unilateral ureteral obstruction. PDGFRα+ cell-specific knockout of Mst1/2 in mice increased unilateral ureteral obstruction-induced myofibroblast accumulation and fibrosis. In cultured fibroblasts, TGF-ß increased YAP and promoted its nucleus entry, but a high dose and prolonged treatment of TGF-ß increased the MST1/2 activation to prevent YAP from entering the nucleus. Our results indicate that MST1/2 is a negative feedback signal of TGF-ß-induced fibroblast differentiation.NEW & NOTEWORTHY Using a mouse model with macrophage stimulating 1/2 (Mst1/2) double knockout in PDGFRα+ cells and an MST1/2 inhibitor, we demonstrated that MST1/2 acted as a negative feedback signal of transforming growth factor-ß-induced fibroblast differentiation. Furthermore, we demonstrated that Hippo-MST as a negative feedback signal can decrease the renal fibrosis process. This finding contributes to our understanding of the mechanism of coregulated renal remodeling after injury.

Differentially expressed EREG and SPP1 are independent prognostic markers in cervical squamous cell carcinoma.

AIMS: Cervical squamous cell carcinoma (SCC) is one of the most frequent malignancies of the female reproductive system. The malignant mechanism of SCC has not been totally clarified. We aimed to discover a list of differentially expressed genes (DEGs) to identify the malignant mechanism of cervical SCC. METHOD: Three expression chips (GSE7803, GSE9750, and GSE64217) were downloaded from gene expression omnibus (GEO) datasets. After standardization, 50 cervical SCC tumor tissues and 33 normal cervical tissues (NCTs) were included for DEGs and clustering analysis. RobustRankAggreg (RRA) algorithm was used to extract the overlapping DEGs. Gene function and signaling pathway analysis was implemented based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway databases. Protein-protein interaction (PPI) analysis and prognostic analysis were also carried out to identify the DEGs as prognostic markers for cervical SCC. RESULTS: Totally 100 DEGs were obtained from GSE7803, 319 DEGs from GSE9750, and 1639 DEGs from GSE64217. RRA analysis uncovered 17 upregulated DEGs and 25 downregulated DEGs. GO and KEGG analysis showed DEGs were involved in the mediation of extracellular functions, cell-cell interactions, and cell metabolism. PPI network showed a close interaction among the integrated DEGs. Prognostic analysis showed gene secreted phosphoprotein 1 (SPP1) and epiregulin (EREG) genes were independent prognostic predictors of cervical SCC. CONCLUSION: The gene expression profile was changed in cervical SCC tumor tissues compared to NCTs. SPP1 and EREG were postulated as prognostic markers for cervical SCC, which might be potential targets for clinical therapy of cervical SCC.

Bacillus velezensis LG37: transcriptome profiling and functional verification of GlnK and MnrA in ammonia assimilation.

BACKGROUND: In recent years, interest in Bacillus velezensis has increased significantly due to its role in many industrial water bioremediation processes. In this study, we isolated and assessed the transcriptome of Bacillus velezensis LG37 (from an aquaculture pond) under different nitrogen sources. Since Bacillus species exhibit heterogeneity, it is worth investigating the molecular mechanism of LG37 through ammonia nitrogen assimilation, where nitrogen in the form of molecular ammonia is considered toxic to aquatic organisms. RESULTS: Here, a total of 812 differentially expressed genes (DEGs) from the transcriptomic sequencing of LG37 grown in minimal medium supplemented with ammonia (treatment) or glutamine (control) were obtained, from which 56 had Fold Change ≥2. BLAST-NCBI and UniProt databases revealed 27 out of the 56 DEGs were potentially involved in NH4+ assimilation. Among them, 8 DEGs together with the two-component regulatory system GlnK/GlnL were randomly selected for validation by quantitative real-time RT-PCR, and the results showed that expression of all the 8 DEGs are consistent with the RNA-seq data. Moreover, the transcriptome and relative expression analysis were consistent with the transporter gene amtB and it is not involved in ammonia transport, even in the highest ammonia concentrations. Besides, CRISPR-Cas9 knockout and overexpression glnK mutants further evidenced the exclusion of amtB regulation, suggesting the involvement of alternative transporter. Additionally, in the transcriptomic data, a novel ammonium transporter mnrA was expressed significantly in increased ammonia concentrations. Subsequently, OEmnrA and ΔmnrA LG37 strains showed unique expression pattern of specific genes compared to that of wild-LG37 strain. CONCLUSION: Based on the transcriptome data, regulation of nitrogen related genes was determined in the newly isolated LG37 strain to analyse the key regulating factors during ammonia assimilation. Using genomics tools, the novel MnrA transporter of LG37 became apparent in ammonia transport instead of AmtB, which transports ammonium nitrogen in other Bacillus strains. Collectively, this study defines heterogeneity of B. velezensis LG37 through comprehensive transcriptome analysis and subsequently, by genome editing techniques, sheds light on the enigmatic mechanisms controlling the functional genes under different nitrogen sources also reveals the need for further research.

Interleukin-35 Expression in Non-Small Cell Lung Cancer is Associated with Tumor Progression.

BACKGROUND/AIMS: Lung cancer continues to be the leading cause of cancer related deaths worldwide due to its high incidence, malignant behavior and lack of major advancements in treatment strategy. The occurrence and development of lung cancer is closely related to inflammation. Thus, we conducted the present study to investigate the effects of IL-35 (Interleukin 35), a newly identified anti-inflammatory factor, on non-small cell lung cancer (NSCLC), which accounts for about 85% of all lung cancers. METHODS: We first evaluated the IL-35 expression in 384 pairs of NSCLC samples and their adjacent normal mucosa by realtime PCR, ELISA (Enzyme-linked immunoassay) and tissue microarrays. Then the role of IL-35 on patient survival rates, cancer progression and their sensitivity to chemotherapy drugs were assessed. RESULTS: IL-35 was barely expressed in the NSCLC tissues but highly expressed in the adjacent normal tissues. The down-regulation of IL-35 was significantly correlated with the results of American Joint Committee on Cancer stage, differentiation and it was also shown to be an independent prognostic indicator of disease-free survival and overall survival for patients with NSCLC. Overexpression of IL-35 in NSCLC cells suppressed cell migration, invasion, proliferation, colony formation through suppressing ß-catenin. IL-35 inhibited NSCLC formation in the mice model and sensitize the cancer cells to chemotherapy drugs. CONCLUSION: Our results showed that IL-35 plays an inhibitory role in NSCLC development and function as a novel prognostic indicator and a potential therapeutic target.

Depletion of CD8+ T Cells Exacerbates CD4+ T Cell-Induced Monocyte-to-Fibroblast Transition in Renal Fibrosis.

Bone marrow-derived monocyte-to-fibroblast transition is a key step in renal fibrosis pathogenesis, which is regulated by the inflammatory microenvironment. However, the mechanism by which the inflammatory microenvironment regulates this transition is not fully understood. In this study, we examined how the CD8(+) T cell/IFN-γ microenvironment regulates the monocyte-to-fibroblast transition in renal fibrosis. Genetic ablation of CD8 promoted a monocyte-to-fibroblast transition and increased renal interstitial fibrosis, whereas reconstitution of CD8 knockout (KO) mice with CD8(+) T cells decreased fibrosis. However, depletion of CD4(+) T cells in CD8 KO mice also reduced fibrosis. To elucidate the role of CD4(+) T cells in mediating CD8-regulated monocyte-to-fibroblast transition, CD4(+) T cells were isolated from obstructed kidneys of CD8 KO or wild-type mice. CD4(+) T cells isolated from CD8 KO obstructed kidney expressed more IL-4 and GATA3 and less IFN-γ and T-bet and showed increased monocyte-to-fibroblast transition in vitro compared with those isolated from wild-type obstructed kidney. To examine the role of IFN-γ-expressing CD8(+) T cells, we reconstituted CD8 KO mice with CD8(+) T cells isolated from IFN-γ KO mice. The IFN-γ KO CD8(+) cells had no effect on IL-4, GATA3, IFN-γ, and T-bet mRNA expression in obstructed kidneys or renal fibrosis. Taken together, our findings identify the axis of CD8(+) T cells and IFN-γ-CD4(+) T cells as an important microenvironment for the monocyte-to-fibroblast transition, which negatively regulates renal fibrosis.

The pathway to muscle fibrosis depends on myostatin stimulating the differentiation of fibro/adipogenic progenitor cells in chronic kidney disease.

Fibrosis in skeletal muscle develops after injury or in response to chronic kidney disease (CKD), but the origin of cells becoming fibrous tissue and the initiating and sustaining mechanisms causing muscle fibrosis are unclear. We identified muscle fibro/adipogenic progenitor cells (FAPs) that potentially differentiate into adipose tissues or fibrosis. We also demonstrated that CKD stimulates myostatin production in muscle. Therefore, we tested whether CKD induces myostatin, which stimulates fibrotic differentiation of FAPs leading to fibrosis in skeletal muscles. We isolated FAPs from mouse muscles and found that myostatin stimulates their proliferation and conversion into fibrocytes. In vivo, FAPs isolated from EGFP-transgenic mice (FAPs-EGFP) were transplanted into muscles of mice with CKD or into mouse muscles that were treated with myostatin. CKD or myostatin stimulated FAPs-EGFP proliferation in muscle and increased α-smooth muscle actin expression in FAP-EGFP cells. When myostatin was inhibited with a neutralizing peptibody (a chimeric peptide-Fc fusion protein), the FAP proliferation and muscle fibrosis induced by CKD were both suppressed. Knocking down Smad3 in cultured FAPs interrupted their conversion into fibrocytes, indicating that myostatin directly converts FAPs into fibrocytes. Thus, counteracting myostatin may be a strategy for preventing the development of fibrosis in skeletal muscles of patients with CKD.

Evidence for the Importance of Atmospheric Nitrogen Deposition to Eutrophic Lake Dianchi, China.

Elevated atmospheric nitrogen (N) deposition has significantly influenced aquatic ecosystems, especially with regard to their N budgets and phytoplankton growth potentials. Compared to a considerable number of studies on oligotrophic lakes and oceanic waters, little evidence for the importance of N deposition has been generated for eutrophic lakes, even though emphasis has been placed on reducing external N inputs to control eutrophication in these lakes. Our high-resolution observations of atmospheric depositions and riverine inputs of biologically reactive N species into eutrophic Lake Dianchi (the sixth largest freshwater lake in China) shed new light onto the contribution of N deposition to total N loads. Annual N deposition accounted for 15.7% to 16.6% of total N loads under variable precipitation conditions, 2-fold higher than previous estimates (7.6%) for the Lake Dianchi. The proportion of N deposition to total N loads further increased to 27-48% in May and June when toxic blooms of the ubiquitous non-N2 fixing cyanobacteria Microcystis spp. are initiated and proliferate. Our observations reveal that reduced N (59%) contributes a greater amount than oxidized N to total N deposition, reaching 56-83% from late spring to summer. Progress toward mitigating eutrophication in Lake Dianchi and other bloom-impacted eutrophic lakes will be difficult without reductions in ammonia emissions and subsequent N deposition.

CX3CL1-CX3CR1 Interaction Increases the Population of Ly6C(-)CX3CR1(hi) Macrophages Contributing to Unilateral Ureteral Obstruction-Induced Fibrosis.

Chemokines modulate inflammatory responses that are prerequisites for kidney injury. The specific role of monocyte-associated CX3CR1 and its cognate ligand CX3CL1 in unilateral ureteral obstruction (UUO)-induced kidney injury remains unclear. In this study, we found that UUO caused a CCR2-dependent increase in numbers of Ly6C(hi) monocytes both in the blood and kidneys and of Ly6C(-)CX3CR1(+) macrophages in the obstructed kidneys of mice. Using CX3CR1(gfp/+) knockin mice, we observed a rapid conversion of infiltrating proinflammatory Ly6C(+)CX3CR1(1o) monocytes/macrophages to anti-inflammatory Ly6C(-)CX3CR1(hi) macrophages. CX3CR1 deficiency affected neither monocyte trafficking nor macrophage differentiation in vivo upon renal obstruction, but CX3CR1 expression in monocytes and macrophages was required for increases in fibrosis in the obstructed kidneys. Mechanistically, CX3CL1-CX3CR1 interaction increases Ly6C(-)CX3CR1(hi) macrophage survival within the obstructed kidneys. Therefore, CX3CL1 and CX3CR1 may represent attractive therapeutic targets in obstructive nephropathy.

Inhibition of Stat3 activation suppresses caspase-3 and the ubiquitin-proteasome system, leading to preservation of muscle mass in cancer cachexia.

Cachexia occurs in patients with advanced cancers. Despite the adverse clinical impact of cancer-induced muscle wasting, pathways causing cachexia are controversial, and clinically reliable therapies are not available. A trigger of muscle protein loss is the Jak/Stat pathway, and indeed, we found that conditioned medium from C26 colon carcinoma (C26) or Lewis lung carcinoma cells activates Stat3 (p-Stat3) in C2C12 myotubes. We identified two proteolytic pathways that are activated in muscle by p-Stat3; one is activation of caspase-3, and the other is p-Stat3 to myostatin, MAFbx/Atrogin-1, and MuRF-1 via CAAT/enhancer-binding protein δ (C/EBPδ). Using sequential deletions of the caspase-3 promoter and CHIP assays, we determined that Stat3 activation increases caspase-3 expression in C2C12 cells. Caspase-3 expression and proteolytic activity were stimulated by p-Stat3 in muscles of tumor-bearing mice. In mice with cachexia caused by Lewis lung carcinoma or C26 tumors, knock-out of p-Stat3 in muscle or with a small chemical inhibitor of p-Stat3 suppressed muscle mass losses, improved protein synthesis and degradation in muscle, and increased body weight and grip strength. Activation of p-Stat3 stimulates a pathway from C/EBPδ to myostatin and expression of MAFbx/Atrogin-1 and increases the ubiquitin-proteasome system. Indeed, C/EBPδ KO decreases the expression of MAFbx/Atrogin-1 and myostatin, while increasing muscle mass and grip strength. In conclusion, cancer stimulates p-Stat3 in muscle, activating protein loss by stimulating caspase-3, myostatin, and the ubiquitin-proteasome system. These results could lead to novel strategies for preventing cancer-induced muscle wasting.

Inhibition of myostatin in mice improves insulin sensitivity via irisin-mediated cross talk between muscle and adipose tissues.

BACKGROUND/OBJECTIVE: In mice, a high-fat diet (HFD) induces obesity, insulin resistance and myostatin production. We tested whether inhibition of myostatin in mice can reverse these HFD-induced abnormalities. SUBJECTS/METHODS: C57BL/6 mice were fed a HFD for 16 weeks including the final 4 weeks some mice were treated with an anti-myostatin peptibody. Body composition, the respiratory exchange ratio plus glucose and insulin tolerance tests were examined. Myostatin knock down in C2C12 cells was performed using small hairpin RNA lentivirus. Adipose tissue-derived stem cells were cultured to measure their responses to conditioned media from C2C12 cells lacking myostatin, or to recombinant myostatin or irisin. Isolated peritoneal macrophages were treated with myostatin or irisin to determine whether myostatin or irisin induce inflammatory mechanisms. RESULTS: In HFD-fed mice, peptibody treatment stimulated muscle growth and improved insulin resistance. The improved glucose and insulin tolerances were confirmed when we found increased muscle expression of p-Akt and the glucose transporter, Glut4. In HFD-fed mice, the peptibody suppressed macrophage infiltration and the expression of proinflammatory cytokines in both the muscle and adipocytes. Inhibition of myostatin caused the conversion of white (WAT) to brown adipose tissue, whereas stimulating fatty acid oxidation and increasing energy expenditure. The related mechanism is a muscle-to-fat cross talk mediated by irisin. Myostatin inhibition increased peroxisome proliferator-activated receptor gamma, coactivator 1α expression and irisin production in the muscle. Irisin then stimulated WAT browning. Irisin also suppresses inflammation and stimulates macrophage polarization from M1 to M2 types. CONCLUSIONS: These results uncover a metabolic pathway from an increase in myostatin that suppresses irisin leading to the activation of inflammatory cytokines and insulin resistance. Thus, myostatin is a potential therapeutic target to treat insulin resistance of type II diabetes as well as the shortage of brown/beige fat in obesity.