Antibacterial peptide Reg4 ameliorates Pseudomonas aeruginosa-induced pulmonary inflammation and fibrosis.

Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative facultative anaerobe that has become an important cause of severe infections in humans, particularly in patients with cystic fibrosis. The development of efficacious methods or mendicants against P. aeruginosa is still needed. We previously reported that regenerating islet-derived family member 4 (Reg4) has bactericidal activity against Salmonella Typhimurium, a Gram-negative flagellated bacterium. We herein explore whether Reg4 has bactericidal activity against P. aeruginosa. In the P. aeruginosa PAO1-chronic infection model, Reg4 significantly inhibits the colonization of PAO1 in the lung and subsequently ameliorates pulmonary inflammation and fibrosis. Reg4 recombinant protein suppresses the growth motility and biofilm formation capability of PAO1 in vitro. Mechanistically, Reg4 not only exerts bactericidal action via direct binding to the P. aeruginosa cell wall but also enhances the phagocytosis of alveolar macrophages in the host. Taken together, our study demonstrates that Reg4 may provide protection against P. aeruginosa-induced pulmonary inflammation and fibrosis via its antibacterial activity.IMPORTANCEChronic lung infection with Pseudomonas aeruginosa is a leading cause of morbidity and mortality in patients with cystic fibrosis. Due to the antibiotic resistance of Pseudomonas aeruginosa, antimicrobial peptides appear to be a potential alternative to combat its infection. In this study, we report an antimicrobial peptide, regenerating islet-derived 4 (Reg4), that showed killing activity against clinical strains of Pseudomonas aeruginosa PAO1 and ameliorated PAO1-induced pulmonary inflammation and fibrosis. Experimental data also showed Reg4 directly bound to the bacterial cell membrane and enhanced the phagocytosis of host alveolar macrophages. Our presented study will be a helpful resource in searching for novel antimicrobial peptides that could have the potential to replace conventional antibiotics.

Neurotensin contributes to cholestatic liver disease potentially modulating matrix metalloprotease-7.

The diagnosis and treatment of biliary atresia pose challenges due to the absence of reliable biomarkers and limited understanding of its etiology. The plasma and liver of patients with biliary atresia exhibit elevated levels of neurotensin. To investigate the specific role of neurotensin in the progression of biliary atresia, the patient's liver pathological section was employed. Biliary organoids, cultured biliary cells, and a mouse model were employed to elucidate both the potential diagnostic significance of neurotensin and its underlying mechanistic pathway. In patients' blood, the levels of neurotensin were positively correlated with matrix metalloprotease-7, interleukin-8, and liver function enzymes. Neurotensin and neurotensin receptors were mainly expressed in the intrahepatic biliary cells and were stimulated by bile acids. Neurotensin suppressed the growth and increased expression of matrix metalloprotease-7 in biliary organoids. Neurotensin inhibited mitochondrial respiration, oxidative phosphorylation, and attenuated the activation of calmodulin-dependent kinase kinase 2-adenosine monophosphate-activated protein kinase (CaMKK2-AMPK) signaling in cultured biliary cells. The stimulation of neurotensin in mice and cultured cholangiocytes resulted in the upregulation of matrix metalloprotease-7 expression through binding to its receptors, namely neurotensin receptors 1/3, thereby attenuating the activation of the CaMKK2-AMPK pathway. In conclusion, these findings revealed the changes of neurotensin in patients with cholestatic liver disease and its mechanism in the progression of the disease, providing a new understanding of the complex mechanism of hepatobiliary injury in children with biliary atresia.

Farnesoid X receptor agonist tropifexor detoxifies ammonia by regulating the glutamine metabolism and urea cycles in cholestatic livers.

Hyperammonemia refers to elevated levels of ammonia in the blood, which is an important pathological feature of liver cirrhosis and hepatic failure. Preclinical studies suggest tropifexor (TXR), a novel non-bile acid agonist of Farnesoid X Receptor (FXR), has shown promising effects on reducing hepatic steatosis, inflammation, and fibrosis. This study evaluates the impact of TXR on hyperammonemia in a piglet model of cholestasis. We here observed blood ammonia significantly elevated in patients with biliary atresia (BA) and was positively correlated with liver injury. Targeted metabolomics and immunblotting showed glutamine metabolism and urea cycles were impaired in BA patients. Next, we observed that TXR potently suppresses bile duct ligation (BDL)-induced injuries in liver and brain with improving the glutamine metabolism and urea cycles. Within the liver, TXR enhances glutamine metabolism and urea cycles by up-regulation of key regulatory enzymes, including glutamine synthetase (GS), carbamoyl-phosphate synthetase 1 (CPS1), argininosuccinate synthetase (ASS1), argininosuccinate lyase (ASL), and arginase 1 (ARG1). In primary mice hepatocytes, TXR detoxified ammonia via increasing ureagenesis. Mechanically, TXR activating FXR to increase express enzymes that regulating ureagenesis and glutamine synthesis through a transcriptional approach. Together, these results suggest that TXR may have therapeutic implications for hyperammonemic conditions in cholestatic livers.

Loss of Mptx2 alters bacteria composition and intestinal homeostasis potentially by impairing autophagy.

A recent single-cell survey of the small-intestinal epithelium suggests that mucosal pentraxin 2 (Mptx2) is a new Paneth cell marker, but its function and involved mechanism in the Paneth cell are still unknown. Therefore, we create Mptx2 knockout (Mptx2-/-) mice to investigate its precise effects on intestinal homeostasis using models of lipopolysaccharide (LPS), methicillin-resistant Staphylococcus aureus (MRSA) peritoneal infection, and dextran sulfate sodium (DSS)-induced intestinal injury and inflammation. We here find that Mptx2 is selectively expressed in Paneth cells in the small intestines of mice. Mptx2-/- mice have increased susceptibility to intestinal inflammation and injured. Mptx2 deficiency reduces Paneth cell count and expression of antimicrobial factors, leading to altered intestinal bacteria composition. Loss of Mptx2 aggravates MRSA infection-induced damage in the intestine while decreasing autophagy in Paneth cells. Mptx2-/- mice are more vulnerable to LPS-induced intestinal possibly due to inhibition of the autophagy/endoplasmic reticulum (ER) stress pathway. Mptx2-/- mice are susceptible to DSS-induced colitis that could be ameliorated by treatment with gentamicin or vancomycin antibiotics. In conclusion, Mptx2 is essential to maintain intestinal homeostasis potentially via regulation of autophagy in Paneth cells.

Targeted metabolomics unravels altered phenylalanine levels in piglets receiving total parenteral nutrition.

Parenteral nutrition, received by many patients with intestinal failure, can induce hepatobiliary complications, which is termed as parenteral nutrition-associated liver disease (PNALD). The spectrum of PNALD ranges from cholestasis and steatosis to fibrosis and cirrhosis. Although many factors contribute to the pathogenesis of PNALD, the underlying mechanisms remain unclear. In this study, we performed targeted metabolomics to characterize the metabolomic profile in neonatal piglets receiving total parenteral nutrition (TPN) or enteral nutrition (EN) for 1 or 2 weeks. Overall, the metabolomic signature of TPN groups differed from EN groups at both time points. Among the 20 acylcarnitines identified, a majority of them were significantly reduced in TPN groups. KEGG pathway analysis showed that phenylalanine metabolism-associated pathways were dysregulated accompanied by more progressive liver steatosis associated with TPN. Next, we evaluated phenylalanine catabolism and its association with fatty acid oxidation in piglets and rats with PNALD. We showed that the hepatic expression of phenylalanine-degrading enzyme phenylalanine hydroxylase (PAH) was reduced and systemic phenylalanine levels were increased in both animal models of PNALD. Moreover, carnitine palmitoyltransferase 1A, a central regulator of fatty acid oxidation, was downregulated and its expression was negatively correlated with phenylalanine levels in TPN-fed animals. To explore the effects of phenylalanine accumulation on lipid metabolism, we treated HepG2 cells with phenylalanine co-cultured with sodium palmitate or soybean oil emulsion to induce lipid accumulation. We found that phenylalanine treatment exacerbated lipid accumulation by inhibiting fatty acid oxidation without affecting fatty acid synthesis. In summary, our findings establish a pathogenic role of increased phenylalanine levels in driving liver steatosis, linking dysregulation of phenylalanine catabolism with lipid accumulation in the context of PNALD.

Intestinal Reg4 deficiency confers susceptibility to high-fat diet-induced liver steatosis by increasing intestinal fat absorption in mice.

Background & Aims: Regenerating gene family member 4 (REG4) is a novel marker for enteroendocrine cells and is selectively expressed in specialised enteroendocrine cells of the small intestine. However, the exact roles of REG4 are largely unknown. In this study we investigate the effects of REG4 on the development of dietary fat-dependent liver steatosis and the mechanisms involved. Methods: Mice with intestinal-specific Reg4 deficiency (Reg4 ΔIEC ) and Reg4-floxed alleles (Reg4 fl/fl ) were generated to investigate the effects of Reg4 on diet-induced obesity and liver steatosis. Serum levels of REG4 were also measured in children with obesity using ELISA. Results: Reg4 ΔIEC mice fed a high-fat diet demonstrated significantly increased intestinal fat absorption and were prone to obesity and hepatic steatosis. Importantly, Reg4 ΔIEC mice exhibit enhanced activation of adenosine monophosphate-activated protein kinase (AMPK) signalling and increased protein abundance of the intestinal fat transporters, as well as enzymes involved in triglyceride synthesis and packaging at the proximal small intestine. Moreover, REG4 administration reduced fat absorption, and decreased the expression of intestinal fat absorption-related proteins in cultured intestinal cells possibly via the CaMKK2-AMPK pathway. Serum REG4 levels were markedly lower in children with obesity with advanced liver steatosis (p <0.05). Serum REG4 levels were inversely correlated with levels of liver enzymes, homeostasis model assessment of insulin resistance, low-density lipoprotein cholesterol, and triglycerides. Conclusions: Our findings directly link Reg4 deficiency with increased fat absorption and obesity-related liver steatosis, and suggest that REG4 may provide a potential target for prevention and treatment of liver steatosis in children. Impact and Implications: Hepatic steatosis is a key histological feature of non-alcoholic fatty liver disease, which is the leading chronic liver disease in children leading to the development of metabolic diseases; however, little is known about mechanisms induced by dietary fat. Intestinal REG4 acts as a novel enteroendocrine hormone reducing high-fat-diet-induced liver steatosis with decreasing intestinal fat absorption. REG4 may be a novel target for treatment of paediatric liver steatosis from the perspective of crosstalk between intestine and liver.

Inositol hexaphosphate promotes intestinal adaptation in short bowel syndrome via an HDAC3-mediated epigenetic pathway.

Background: Short bowel syndrome (SBS) has high morbidity and mortality rates, and promoting intestinal adaptation of the residual intestine is a critical treatment. Dietary inositol hexaphosphate (IP6) plays an important role in maintaining intestinal homeostasis, but its effect on SBS remains unclear. This study aimed at investigating the effect of IP6 on SBS and clarified its underlying mechanism. Methods: Forty male Sprague-Dawley rats (3-week-old) were randomly assigned into four groups (Sham, Sham + IP6, SBS, and SBS + IP6 groups). Rats were fed standard pelleted rat chow and underwent resection of 75% of the small intestine after 1 week of acclimation. They received 1 mL IP6 treatment (2 mg/g) or sterile water daily for 13 days by gavage. Intestinal length, levels of inositol 1,4,5-trisphosphate (IP3), histone deacetylase 3 (HDAC3) activity, and proliferation of intestinal epithelial cell-6 (IEC-6) were detected. Results: IP6 treatment increased the length of the residual intestine in rats with SBS. Furthermore, IP6 treatment caused an increase in body weight, intestinal mucosal weight, and IEC proliferation, and a decrease in intestinal permeability. IP6 treatment led to higher levels of IP3 in feces and serum, and higher HDAC3 activity of the intestine. Interestingly, HDAC3 activity was positively correlated with the levels of IP3 in feces (r = 0.49, P = 0.01) and serum (r = 0.44, P = 0.03). Consistently, IP3 treatment promoted the proliferation of IEC-6 cells by increasing HDAC3 activity in vitro. IP3 regulated the Forkhead box O3 (FOXO3)/Cyclin D1 (CCND1) signaling pathway. Conclusion: IP6 treatment promotes intestinal adaptation in rats with SBS. IP6 is metabolized to IP3 to increase HDAC3 activity to regulate the FOXO3/CCND1 signaling pathway and may represent a potential therapeutic approach for patients with SBS.

Selective depletion of CD11b-positive monocytes/macrophages potently suppresses bleomycin-induced pulmonary fibrosis.

The understanding of pathogenesis underlying idiopathic pulmonary fibrosis (IPF) is still limited presently. Monocytes or macrophages are involved in progression of the pulmonary injury and repair. The aim of this study is to investigate the roles of CD11b+ monocytes/macrophages in the progression of pulmonary fibrosis. In this study, the expression levels of CD11B gene and inflammatory genes in the IPF patients are evaluated using the available datasets. CD11b cells are conditionally depleted in a CD11b-diptheria toxin receptor (CD11b-DTR) mouse by administration of diptheria toxin (DT). Pulmonary fibrosis in mice is induced using intranasalbleomycin. The mRNAs and proteins expression in lung tissues are determined by quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF) staining and Western-blot assays. It shows that the expression of CD11B mRNA is up-regulated in fibrotic lungs and alveolar macrophages of IPF patients and bleomycin-treated rodents. Selective depletion of CD11b+ monocytes/macrophages in CD11b-DTR mice potently halts bleomycin-induced pulmonary fibrosis progression. CD11b depletion inhibits the polarization of macrophages in the fibrotic lungs. Mechanically, CD11b deficiency represses the activation of sphingosine 1-phosphate receptor 2 (S1PR2)/sphingosine kinase 2 (SphK2) signaling during pulmonary fibrosis. In conclusion, our data suggest that CD11b+ monocytes/macrophages contribute to pulmonary fibrosis and represent a potential therapeutic target for IPF.

Heterozygous Actg2R257C mice mimic the phenotype of megacystis microcolon intestinal hypoperistalsis syndrome.

BACKGROUND: Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare and serious congenital disorder with poor outcomes, where a heterozygous missense mutation is present in the ACTG2 gene. Here, we aimed to investigate the pathogenesis of ACTG2 in MMIHS. METHODS: A cohort with 20 patients with MMIHS was screened. Actg2R257C heterozygous mutant mice were generated using the CRISPR/Cas9 system. Gastrointestinal (GI) motility, voluntary urination, collagen gel contraction, and G-actin/F-actin analysis were performed. KEY RESULTS: The R257C variant of ACTG2 most frequently occurred in patients with MMIHS and demonstrated the typical symptoms of MMIHS. Actg2R257C heterozygous mutant mice had dilated intestines and bladders. The functional assay showed a prolonged total time of GI transit and decreased urine spot area. Collagen gel contraction assay and G-actin/F-actin analysis indicated that mutant mice showed reduced area of contraction of smooth muscle cells (SMCs) and impaired actin polymerization. CONCLUSIONS & INFERENCES: A mouse model demonstrating MMIHS-like symptoms was generated. The Actg2R257C heterozygous variant impairs SMCs contraction by interfering with actin polymerization, leading to GI motility disorders.

Production of Tone 2 in disyllabic words in Mandarin Chinese speaking children aged 3-5 with a cochlear implant and a contralateral hearing aid.

To investigate Mandarin Tone 2 production of disyllabic words of prelingually deafened children with a cochlear implant (CI) and a contralateral hearing aid (HA) and to evaluate the relationship between their demographic variables and tone-production ability. Thirty prelingually Mandarin-speaking preschoolers with CI+HA and 30 age-matched normal-hearing (NH) children participated in the study. Fourteen disyllabic words were recorded from each child. A total of 840 tokens (14 × 60) were then used in tone-perception tests in which four speech therapists participated. The production of T2-related disyllabic words of the bimodal group was significantly worse than that of the NH group, as reflected in the overall accuracy (88.57% ± 16.31% vs 99.29% ± 21.79%, p < 0.05), the accuracy of T1+T2 (93.33% vs 100%), the accuracy of T2+T1 (66.67 ± 37.91% vs 98.33 ± 9.13%), and the accuracy of T2+T4 (78.33 ± 33.95% vs 100%). In addition, the bimodal group showed significantly inferior production accuracy of T2+T1 than T2+T2 and T3+T2, p < 0.05. Both bimodal age and implantation age were significantly negatively correlated with the overall production accuracy, p < 0.05. For the error patterns, bimodal participants experienced more errors when T2 was in the first position of the tone combination, and T2 was most likely to be mispronounced as T1 and T3. Bimodal patients aged 3-5 have T2-related disyllabic lexical tone production defects, and their performances are related to tone combination, implantation age, and bimodal age.

Postbiotic muramyl dipeptide alleviates colitis via activating autophagy in intestinal epithelial cells.

The pathogenesis of IBD is complicated and still unclear. Nucleotide-binding oligomerization domain 2 (NOD2) plays a significant role in regulating gut inflammation under the activation of muramyl dipeptide (MDP), which is used as a postbiotic. The study aimed to investigate the effect of MDP on the intestinal barrier in colitis and the mechanism involved. In this study, C57BL/6 mice were challenged with dextran sodium sulfate (DSS) for establishing a colitis model with the pre-treatment of MDP in vivo. Intestinal permeability was reflected by detecting the serum concentration of 4 kDa Fluorescein Isothiocyanate-Dextran. The expression of inflammation, barrier-related proteins, and autophagy was tested by Western Blotting. Proliferation and apoptosis in intestinal epithelial cells were detected by immunohistochemistry. Caco-2 cells were exposed to lipopolysaccharide for imitating inflammation in vitro. The findings showed that administration of MDP ameliorated losses of body weight loss, gross injury, and histology score of the colon in the DSS-induced colitis mice. MDP significantly ameliorated the condition of gut permeability, and promoted intestinal barrier repair by increasing the expression of Zonula occludens-1 and E-cadherin. Meanwhile, MDP promoted proliferation and reduced apoptosis of intestinal epithelial cells. In the experiment group treated with MDP, LC3 was upregulated, and p62 was downregulated, respectively. These results suggested that MDP stimulation attenuates intestinal inflammation both in vivo and in vitro. Potentially, MDP reduced the intestinal barrier damage by regulating autophagy in intestinal epithelial cells. Future trials investigating the effects of MDP-based postbiotics on IBD may be promising.

Metabolic regulation of cholestatic liver injury by D-2-hydroxyglutarate with the modulation of hepatic microenvironment and the mammalian target of rapamycin signaling.

Biliary atresia (BA) is a cholestatic liver disease in neonates with devastating obstructive intrahepatic and extrahepatic biliary ducts. Owing to the lack of an early diagnostic marker and limited understanding of its pathogenesis, BA often leads to death within 2 years. Therefore, this study aimed to develop early diagnostic methods and investigate the underlying pathogenesis of liver injury in BA using metabolomics. Metabolomics and organoid combined energy metabolism analysis was used to obtain new insights into BA diagnosis and pathobiology using patient samples, mice liver organoids, and a zebrafish model. Metabolomics revealed that D-2-hydroxyglutarate (D-2-HG) levels were significantly elevated in the plasma and liver of patients with BA and closely correlated with liver injuries and impaired liver regeneration. D-2-HG suppressed the growth and expansion of liver organoids derived from the intrahepatic biliary ducts. The energy metabolism analysis demonstrated that D-2-HG inhibited mitochondrial respiration and ATP synthase; however, it increased aerobic glycolysis in organoids. In addition, D-2-HG exposure caused liver degeneration in zebrafish larvae. Mechanistically, D-2-HG inhibited the activation of protein kinase B and the mammalian target of rapamycin signaling. These findings reveal that D-2-HG may represent a novel noninvasive diagnostic biomarker and a potential therapeutic target for infants with BA.

Reg4 protects against Salmonella infection-associated intestinal inflammation via adopting a calcium-dependent lectin-like domain.

Salmonella Typhimurium (S. Tm) is Gram-negative flagellated bacteria that can cause food-borne gastroenteritis and diarrhea in human. Developing efficacious methods against Salmonella infection is still challenged. Herein, we report that regenerating islet-derived family member 4 (Reg4) has potent bactericidal activity against S. Tm. For the S. Tm-infected mice, Reg4 significantly inhibits colonization of S. Tm in the intestine and subsequently ameliorates intestinal inflammation. In vitro experiments, the addition of Reg4 significantly suppresses the growth and proliferation of Salmonella. Moreover, both human and mice Reg4 proteins restrain the Salmonella to invade the intestinal epithelia. Mechanistically, Reg4 performs bactericidal action against Salmonella via a motif (HDPQK) homologous to a calcium-dependent (C-type) lectin-like domain. Reg4 can specifically bind to the flagella of Salmonella to restrain bacterial motility and suppress the host inflammatory response. In conclusion, our findings identify that Reg4 acts as a new antimicrobial protein against Salmonella, which suggests Reg4 may have a great significance for developing novel agents against Salmonella infection-associated intestinal inflammation.

Beta-amyloid Deposition in Biliary Atresia Reduces Liver Regeneration by Inhibiting Energy Metabolism and Mammalian Target of Rapamycin Signaling.

INTRODUCTION: Biliary atresia (BA) is a devastating obstructive bile duct disease found in newborns. This study aims to investigate the roles and involved mechanisms of beta-amyloid (Aß) in the pathogenesis of BA. METHODS: We examined the distribution of Aß protein and its precursor in the livers of patients with BA. A murine liver organoid and a zebrafish model were established to investigate the exact roles of Aß in liver regeneration for BA. RESULTS: Both Aß mRNA and protein significantly increased in livers of infants with BA and deposited around the central vein. In the plasma, Aß elevated significantly in patients with BA and positively correlated with liver injury progression. In vitro , Aß treatment induced abnormal morphology and caused impaired growth in liver organoids. Energy metabolism analysis demonstrated Aß increased aerobic glycolysis and reduced ATP synthase in organoids, in which the mammalian target of rapamycin signaling was suppressed. In vivo , Aß42 exposure caused liver degeneration in zebrafish larvae. DISCUSSION: Aß depositing in livers of infants with BA reduced the liver regeneration through attenuating mitochondrial respiration and mammalian target of rapamycin signaling.

Diagnostic values of plasma matrix metalloproteinase-7, interleukin-8, and gamma-glutamyl transferase in biliary atresia.

Biliary atresia (BA) is a severe cholestatic liver disease in children featuring cholestasis and liver fibrosis. The early diagnosis of BA is still challenging. This study aimed to evaluate the diagnostic values of matrix metalloprotease-7 (MMP-7), interleukin-8 (IL-8), and gamma-glutamyl transferase (GGT) in BA. Infants diagnosed with BA and non-BA between 2013 and 2018 were retrospectively analyzed. Plasma levels of MMP-7, IL-8, and GGT were measured in these infants. The receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) were used to assess the diagnostic values of MMP-7, IL-8, and GGT. The expression of MMP-7 and IL-8 in the livers was detected by immunofluorescence staining. A total of 229 infants were enrolled in this study: 156 BA infants and 73 non-BA infants including 16 ones with infantile hepatitis syndrome. The plasma levels of MMP-7, IL-8, and GGT in BA infants had a median of 11.8 ng/mL (interquartile range, IQR: 5.3-57.5), 1.5 ng/mL (IQR: 1.0-2.8), and 381.0 U/L (IQR: 197.0-749.0), respectively, which were higher than non-BA subjects [MMP-7, 4.4 ng/mL (IQR: 3.3-6.1); IL-8, 0.7 ng/mL (IQR: 0.5-1.0); GGT, 59.0 U/L (IQR: 26.0-124.0)]. The AUC values of MMP-7, IL-8, and GGT for the diagnosis of BA were 0.8035, 0.8083, and 0.9126, respectively. The AUC values of MMP-7 + IL-8, MMP-7 + GGT, IL-8 + GGT, and MMP-7 + IL-8 + GGT for the diagnosis of BA were 0.8248, 0.9382, 0.9168, and 0.9392, respectively. The AUC values of MMP-7, IL-8, and GGT for differentiating BA infants with cholic stool from non-BA infants with cholic stool were 0.8006, 0.8258, and 0.9141, respectively. The expression of MMP-7 and IL-8 was increased in the cholangiocytes in BA livers.   Conclusion: Plasma MMP-7, IL-8, and GGT alone or a combination of them has good accuracy to differentiate BA from non-BA and may be reliable biomarkers for BA. What is Known: • Biliary atresia (BA) is a severe cholestatic liver disease in children featuring cholestasis and progressive liver fibrosis. • Although early diagnosis of BA is crucial for good outcomes, it remains a clinical challenge. What is New: • Plasma MMP-7, IL-8, and GGT alone or a combination of them has good accuracy to differentiate BA from non-BA. • Plasma MMP-7, IL-8, and GGT have good accuracy for differentiating BA infants with cholic stool from non-BA infants with cholic stool.

Upregulation of cadherin-11 contributes to cholestatic liver fibrosis.

Importance: Cadherin-11 (CDH11), a cell-to-cell adhesion molecule, is implicated in the fibrotic process of several organs. Biliary atresia (BA) is a common cholestatic liver disease featuring cholestasis and progressive liver fibrosis in children. Cholestatic liver fibrosis may progress to liver cirrhosis and lacks effective therapeutic strategies. Currently, the role of CDH11 in cholestatic liver fibrosis remains unclear. Objective: This study aimed to explore the functions of CDH11 in cholestatic liver fibrosis. Methods: The expression of CDH11 in BA livers was evaluated by database analysis and immunostaining. Seven BA liver samples were used for immunostaining. The wild type (Wt) and CDH11 knockout (CDH11-/- ) mice were subjected to bile duct ligation (BDL) to induce cholestatic liver fibrosis. The serum biochemical analysis, liver histology, and western blotting were used to assess the extent of liver injury and fibrosis as well as activation of transforming growth factor-ß (TGF-ß)/Smad pathway. The effect of CDH11 on the activation of hepatic stellate cell line LX-2 cells was investigated. Results: Analysis of public RNA-seq datasets showed that CDH11 expression levels were significantly increased in livers of BA, and CDH11 was correlated with liver fibrosis in BA. BDL-induced liver injury and liver fibrosis were attenuated in CDH11-/- mice compared to Wt mice. The protein expression levels of phosphorylated Smad2/3 were decreased in livers of CDH11-/- BDL mice compared to Wt BDL mice. CDH11 knockdown inhibited the activation of LX-2 cells. Interpretation: CDH11 plays an important role in cholestatic liver fibrosis and may represent a potential therapeutic target for cholestatic liver disease, such as BA.

Lactobacillus plantarum supplementation alleviates liver and intestinal injury in parenteral nutrition-fed piglets.

OBJECTIVE: Long-term parenteral nutrition (PN) causes PN-associated liver disease, for which therapeutic approaches are limited. This study aimed to investigate the effects of Lactobacillus plantarum CGMCC 1258 (LP) on liver and intestinal injury in PN-fed neonatal piglets. METHODS: The piglets received PN with or without oral LP for 14 days. The levels of liver enzymes and inflammatory markers were measured using biochemical kits and quantitative real-time polymerase chain reaction. Serum fibroblast growth factor 19 (FGF19) was detected using an enzyme-linked immunosorbent assay. The bile acid (BA) profiles in the liver, serum, and intestinal contents were determined using ultraperformance liquid chromatography coupled with mass spectrometry. The composition of intestinal bacteria was analyzed with 16S rRNA gene amplicon sequencing. RESULTS: LP supplementation was associated with improved markers of liver disease, inflammation, and oxidative stress in PN-fed piglets. Moreover, markers of intestinal injury and inflammation were alleviated by LP in PN-fed piglets. Mechanistically, LP increased the abundance of Lactobacillus in ileal contents and stimulated FGF19 expression in ileal mucosa. Subsequently, it increased the expression of small heterodimer partner (SHP) and inhibited cholesterol 7α-hydroxylase (CYP7A1) expression in the liver. Additionally, LP altered the systemic composition and metabolism of BAs. CONCLUSIONS: LP alleviated liver and intestinal injury in PN-fed neonatal piglets by altering the composition of intestinal bacteria and BAs.

Mptx2 defends against peritoneal infection by methicillin-resistant staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) has an increasing prevalence of multi-drug resistance. There is an urgent need for developing novel approaches to combat MRSA infection. Mucosal pentraxin 2 (Mptx2) is predicted to be a member of the pentraxin family, but its biological function is still unknown. This study is aimed to explore the roles of Mptx2 in MRSA-associated peritoneal infection. The recombinant Mptx2 protein is used to evaluate its antibacterial activity. Biofilm formation assay and macrophage phagocytic experiment are performed to explore the involved mechanisms. The effects of Mptx2 on peritoneal infection are investigated in a MRSA-induced peritoneal infected model. We here show that addition of Mptx2 suppresses the growth and biofilm formation of MRSA in vitro. Enzyme-linked immunosorbent assay (ELISA) binding analysis shows that Mptx2 protein directly binds to the MRSA. Additionally, Mptx2 supplementation promotes macrophages to phagocytize and clear the MRSA. In the MRSA-infected peritonitis model, Mptx2 administration reduces MRSA loading in peritoneal organs and alleviates peritoneal damage. Mptx2 knockout aggravates MRSA infection-induced peritoneal injury. In conclusion, our findings reveal that Mptx2 has bactericidal activity against MRSA both in vitro and in vivo, which may shed light on the discovery and development of novel strategies for MRSA-infected peritonitis.

Role of the Gut Microbiota in Parenteral Nutrition-Associated Liver Disease: From Current Knowledge to Future Opportunities.

Parenteral nutrition-associated liver disease (PNALD) refers to a spectrum of conditions that can develop cholestasis, steatosis, fibrosis, and cirrhosis in the setting of parenteral nutrition (PN) use. Patient risk factors include short bowel syndrome, bacterial overgrowth and translocation, disturbance of hepatobiliary circulation, and lack of enteral feeding. A growing body of evidence suggests an intricate linkage between the gut microbiota and the pathogenesis of PNALD. In this review, we highlight current knowledge on the taxonomic and functional changes in the gut microbiota that might serve as noninvasive biomarkers. We also discuss the function of microbial metabolites and associated signaling pathways in the pathogenesis of PNALD. By providing the perspectives of microbiota-host interactions in PNALD for basic and translational research and summarizing current limitations of microbiota-based approaches, this review paves the path for developing novel and precise microbiota-based therapies in PNALD.