Bile acid profiling as an effective biomarker for staging in pediatric inflammatory bowel disease.

Rapid and accurate clinical staging of pediatric patients with inflammatory bowel disease (IBD) is crucial to determine the appropriate therapeutic approach. This study aimed to identify effective, convenient biomarkers for staging IBD in pediatric patients. We recruited cohorts of pediatric patients with varying severities of IBD to compare the features of the intestinal microbiota and metabolites between the active and remitting disease stages. Metabolites with potential for staging were targeted for further assessment in both patients and colitis model mice. The performance of these markers was determined using machine learning and was validated in a separate patient cohort. Pediatric patients with IBD exhibited distinct gut microbiota structures at different stages of disease activity. The enterotypes of patients with remitting and active disease were Bacteroides-dominant and Escherichia-Shigella-dominant, respectively. The bile secretion pathway showed the most significant differences between the two stages. Fecal and serum bile acid (BA) levels were strongly related to disease activity in both children and mice. The ratio of primary BAs to secondary BAs in serum was developed as a novel comprehensive index, showing excellent diagnostic performance in stratifying IBD activity (0.84 area under the receiver operating characteristic curve in the primary cohort; 77% accuracy in the validation cohort). In conclusion, we report profound insights into the interactions between the gut microbiota and metabolites in pediatric IBD. Serum BAs have potential as biomarkers for classifying disease activity, and may facilitate the personalization of treatment for IBD.

Clostridioides difficile aggravates dextran sulfate solution (DSS)-induced colitis by shaping the gut microbiota and promoting neutrophil recruitment.

Clostridioides difficile is a pathogen contributing to increased morbidity and mortality of patients with inflammatory bowel disease (IBD). To determine how C. difficile affects the severity of colitis, we constructed a dextran sulfate solution-induced colitis model challenged with C. difficile. Without antibiotic administration, C. difficile led to transient colonization in mice with colitis, but still significantly enhanced disease severity as assessed by weight loss, histopathological damages, and inflammatory cytokine concentrations. Because this effect is independent of toxin production as shown by infection with a non-toxigenic strain, we focused on changes in the gut microbiota. The microbiota altered by C.difficile, featured with reduced proportions of g_Prevotellaceae_UCG-001 and g_Muribaculaceae, were confirmed to contribute to disease severity in colitis mice via fecal microbiota transplantations. The inflamed colon showed neutrophil accumulation by flow cytometric analysis and myeloperoxidase immunochemical staining. There was enrichment of upregulated genes in leukocyte chemotaxis or migration as shown by RNA sequencing analysis. The isolated neutrophils from C. difficile-infected mice with colitis showed a robust migratory ability and had enhanced expression of cytokines and chemokines. We observed a detrimental role of neutrophils in the progress of disease by hindering neutrophil recruitment with the CXCR2 inhibitor SB225002. Furthermore, neutrophil recruitment appeared to be regulated by interleukin (IL)-1ß, as inhibition of IL-1ß production by MCC950 markedly ameliorated inflammation with decreased neutrophil accumulation and neutrophil-derived chemokine expression. In conclusion, our study provides information on the complicated interaction between microbiota and immune responses in C. difficile-induced inflammation in mice with colitis. Our findings could help determine potential therapeutic targets for patients with IBD concurrent with C. difficile infection.

Assessment of patient based real-time quality control on comparative assays for common clinical analytes.

BACKGROUND: It is critical for laboratories to conduct multianalyzer comparisons as a part of daily routine work to strengthen the quality management of test systems. Here, we explored the application of patient-based real-time quality controls (PBRTQCs) on comparative assays to monitor the consistency among clinical laboratories. METHODS: The present study included 11 commonly tested analytes that were detected using three analyzers. PBRTQC procedures were set up with exponentially weighted moving average (EWMA) algorithms and evaluated using the AI-MA artificial intelligence platform. Comparative assays were carried out on serum samples, and patient data were collected. Patients were divided into total patient (TP), inpatient (IP), and outpatient (OP) groups. RESULTS: Optimal PBRTQC protocols were evaluated and selected with appropriate truncation limits and smoothing factors. Generally, similar comparative assay performance was achieved using both the EWMA and median methods. Good consistency between the results from patients' data and serum samples was obtained, and unacceptable bias was detected for alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) when using analyzer C. Categorizing patients' data and applying specific groups for comparative assays could significantly improve the performance of PBRTQCs. When monitoring the inter- and intraanalyzer stability on a daily basis, EWMA was superior in detecting very small quality-related changes with lower false-positive alarms. CONCLUSIONS: We found that PBRTQCs have the potential to efficiently assess multianalyzer comparability. Laboratories should be aware of population variations concerning both analytes and analyzers to build more suitable PBRTQC protocols.

Simultaneous determination of linezolid and voriconazole serum concentrations using liquid chromatography-tandem mass spectrometry.

Linezolid and voriconazole are two antimicrobials used for severe infections in critically ill patients. Pharmacokinetics and pharmacodynamics are altered in critically ill patients. Therefore, standard dosing of anti-infective agents may not reach the optimal therapeutic targets. A rapid and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of linezolid and voriconazole in human serum only 3 min after one-step protein precipitation pretreatment to monitor their concentrations. Multiple-reaction monitoring (MRM) mode was used for detection. The calibration curves were linear over the range of 0.5-100 µg/mL for both linezolid and voriconazole, with regression coefficients above 0.9900 for all analytes. The intra- and interday coefficients of variation were below 15% at all concentration levels (LLOQ/LQC/MQC/HQC). This method was successfully applied to routine therapeutic drug monitoring (TDM) for critically ill patients and other patients in need.

The thromboelastography G parameter as a potential biomarker of acute coronary syndrome.

The most prominent event that defines acute coronary syndrome (ACS) is the formation of an intra-arterial thrombus, usually resulting from activation of platelet and fibrinogen at the ruptured plaque. Usually, conventional coagulation tests (CCTs) are used to estimate the hemostatic properties of patients. However, CCTs have significant limitations because they each assess individual aspects of the coagulation cascade, which is a complex multifaceted process. And CCTs are performed with platelet-poor plasma, while the contribution of platelets to clot formation is not measured. In contrast, thromboelastography (TEG) is a test for global hemostasis with whole blood, from the beginning of coagulation through clot formation to the ending with fibrinolysis. The aim of this study was to investigate whether TEG parameters could be surrogate biomarkers of thrombus formation process and diagnosis of ACS. Receiver operating characteristic（ROC）curve was used to evaluate the diagnosis performance of each index. Logistic regression analysis was utilized to define the independent risk factors of ACS. The results showed that the shear elastic modulus parameter (G) was an independent diagnostic indicator for ACS (odds ratio [OR], 2.600; 95% confidence interval [CI], 2.035-3.322). The area under ROC curve of G was 0.866. The optimal cut-off value for the diagnosis of ACS was 10.55 dyne/cm2, while the sensitivity was 66.2% and the specificity was 92.4%. In conclusion, G could be used as an optimal indicator of activation of platelet and fibrinogen, which is eligible to be a useful biomarker for early diagnosis of ACS.

Expression and Characterization of Gly-317 Variants of Factor IX Causing Variable Bleeding in Hemophilia B Patients.

We recently identified two hemophilia B patients who carried Gly-317 to Arg (FIX-G317R) or Gly-317 to Glu (FIX-G317E) substitutions in their FIX gene. The former mutation caused severe and the latter moderate bleeding in afflicted patients. To understand the molecular basis for the variable clinical manifestation of Gly-317 mutations, we prepared recombinant G317R and G317E derivatives of FIX and compared their kinetic properties to those of recombinant wild-type FIX in appropriate assay systems. Both physiological activators, factor XIa and extrinsic Tenase (factor VIIa-tissue factor), activated both zymogen variants with an ∼1.5-fold elevated K(m); however, extrinsic Tenase activated FIX-G317E with an ∼2-fold improved k(cat). By contrast to zymogen activation, the catalytic activities of both FIXa-G317R and FIXa-G317E enzymes toward the natural substrate, factor X, were dramatically (>4 orders of magnitude) impaired, but their apparent affinity for interaction with factor VIIIa was only slightly (<2-fold) decreased. Further studies revealed that the reactivity of FIXa-G317R and FIXa-G317E with antithrombin has been impaired 10- and 13-fold, respectively, in the absence and 166- and 500-fold, respectively, in the presence of pentasaccharide. As expected, the clotting activities of FIX variants could not be measured by the aPTT assay. These results implicate a critical role for Gly-317 in maintaining normal catalytic function for FIX/FIXa in the clotting cascade. The results further suggest that improved k(cat) of FIX-G317E activation in the extrinsic pathway together with dramatically impaired reactivity of FIXa-G317E with antithrombin may account for the less severe bleeding phenotype of a hemophilia B patient carrying the FIX-G317E mutation.

Molecular basis of the clotting defect in a bleeding patient missing the Asp-185 codon in the factor X gene.

Factor X (FX) is a vitamin K-dependent plasma zymogen, which following activation to factor Xa (FXa), converts prothrombin to thrombin in the blood clotting cascade. It was recently demonstrated that a natural variant of FX carrying the Asp-185 deletion (FX-D185del, chymotrypsinogen numbering) was associated with mild bleeding in a patient with severe FX deficiency. In this study, we expressed FX-D185del in mammalian cells and characterized its properties in appropriate kinetic assays in purified systems. We discovered that while the FX variant can be normally activated by physiological activators; both amidolytic and proteolytic activities of the mutant are dramatically impaired. Interestingly, factor Va (FVa) significantly improved the proteolytic defect when the mutant protease was assembled into the prothrombinase complex. Thus, in contrast to >50-fold catalytic defect in the absence of FVa, the variant activated prothrombin with only ~2.5-fold decreased catalytic efficiency in the presence of the cofactor. The FXa variant dramatically lost its susceptibility to inhibition by antithrombin and tissue factor pathway inhibitor, thus exhibiting ~2-3 orders of magnitude lower reactivity with the plasma inhibitors. Further studies revealed that Na(+) no longer activates the variant protease, suggesting that the functionally important allosteric linkage between the Na(+)-binding and the P1-binding sites of the protease has been eliminated. These results suggest that the lower catalytic efficiency of FXa-D185del in the bleeding patient may be partially compensated by the loss of its reactivity with plasma inhibitors, possibly explaining the basis for the paradoxical severe FX deficiency with only mild bleeding tendency for this mutation.

Characterization of the protein Z-dependent protease inhibitor interactive-sites of protein Z.

BACKGROUND: Protein Z (PZ) has been reported to promote the inactivation of factor Xa (FXa) by PZ-dependent protease inhibitor (ZPI) by about three orders of magnitude. Previously, we prepared a chimeric PZ in which its C-terminal pseudo-catalytic domain was grafted on FX light-chain (Gla and EGF-like domains) (PZ/FX-LC). Characterization of PZ/FX-LC revealed that the ZPI interactive-site is primarily located within PZ pseudo-catalytic domain. Nevertheless, the cofactor function and apparent Kd of PZ/FX-LC for interaction with ZPI remained impaired ~6-7-fold, suggesting that PZ contains a ZPI interactive-site outside pseudo-catalytic domain. X-ray structural data indicates that Tyr-240 of ZPI interacts with EGF2-domain of PZ. Structural data further suggests that 3 other ZPI surface loops make salt-bridge interactions with PZ pseudo-catalytic domain. To identify ZPI interactive-sites on PZ, we grafted the N-terminal EGF2 subdomain of PZ onto PZ/FX-LC chimera (PZ-EGF2/FX-LC) and also generated two compensatory charge reversal mutants of PZ pseudo-catalytic domain (Glu-244 and Arg-212) and ZPI surface loops (Lys-239 and Asp-293). METHODS: PZ chimeras were expressed in mammalian cells and ZPI derivatives were expressed in Escherichia coli. RESULTS: The PZ EGF2 subdomain fusion restored the defective cofactor function of PZ/FX-LC. The activities of PZ and ZPI mutants were all impaired if assayed individually, but partially restored if the compensatory charge reversal mutants were used in the assay. CONCLUSIONS: PZ EGF2 subdomain constitutes an interactive-site for ZPI. Data with compensatory charge reversal mutants validates structural data that the identified residues are part of interactive-sites. GENERAL SIGNIFICANCE: Insight is provided into mechanisms through which specificity of ZPI-PZ-FXa complex formation is determined.

Molecular basis of type I antithrombin deficiency in two women with recurrent venous thromboembolism in the first trimester of pregnancy.

Inherited antithrombin (AT) deficiency carries a 50% risk of venous thromboembolism (VTE) during pregnancy. Here, we investigated the molecular basis of type I AT deficiency in two women with recurrent VTE in the first trimester of pregnancy. Phenotype analysis showed both probands had almost 50% of normal AT levels. Two novel heterozygous AT mutations were identified: g.7920C>T resulting in a Trp225Cys mutation in case 1 and g.13863C>A causing an Ala404Asp mutation in case 2. Transient expression of either wild-type (WT) or mutant AT expression vectors in HEK293T and CHO cells showed impaired secretion of both AT mutant proteins. Immunofluorescence analysis revealed that the staining of AT-Trp225Cys in both endoplasmic reticulum (ER) and Golgi apparatus was similar to that of AT-WT, and the staining of AT-Ala404Asp was mainly present in ER but was weaker than that of AT-WT. These results revealed that the type I AT deficiency in two patients was caused by impaired secretion of the AT-Trp225Cys and AT-Ala404Asp mutant proteins, respectively. The two mutations are associated with a high risk of thrombotic onset and women with these AT mutations are prone to VTE in early pregnancy.