Functional and Promiscuity Studies of Three-Residue Cyclophane Forming Enzymes Show Nonnative C-C Cross-Linked Products and Leader-Dependent Cyclization.

Enzymes catalyzing peptide macrocyclization are important biochemical tools in drug discovery. The three-residue cyclophane-forming enzymes (3-CyFEs) are an emerging family of post-translational modifying enzymes that catalyze the formation of three-residue peptide cyclophanes. In this report, we introduce three additional 3-CyFEs, including ChlB, WnsB, and FnnB, that catalyze cyclophane formation on Tyr, Trp, and Phe, respectively. To understand the promiscuity of these enzymes and those previously reported (MscB, HaaB, and YxdB), we tested single amino acid substitutions at the three-residue motif of modification (Ω1X2X3, Ω1 = aromatic). Collectively, we observe that substrate promiscuity is observed at the Ω1 and X2 positions, but a greater specificity is observed for the X3 residue. Two nonnative cyclophane products were characterized showing a Phe-C3 to Arg-Cß and His-C2 to Pro-Cß cross-links, respectively. We also tested the leader dependence of selected 3-CyFEs and show that a predicted helix region is important for cyclophane formation. These results demonstrate the biocatalytic potential of these maturases and allow rational design of substrates to obtain a diverse array of genetically encoded 3-residue cyclophanes.

Meta-analysis: analysis of mechanistic pathways in the treatment of non-alcoholic steatohepatitis. Evidence from a Bayesian network meta-analysis.

BACKGROUND AND AIMS: Non-alcoholic steatohepatitis (NASH) is the most common cause of liver disease. However, there is lack of comparison of efficacy between different NASH drug classes. We conducted a network meta-analysis evaluating drug classes through comparing histological outcomes and targets of drugs. APPROACH AND RESULTS: Medline, EMBASE and CENTRAL were searched for randomised controlled trials evaluating NASH drugs in biopsy-proven NASH patients. Primary outcomes included NASH resolution without worsening of fibrosis, at least 2-point reduction in Non-alcoholic fatty liver disease Activity Score (NAS) without worsening of fibrosis and at least 1-point reduction in fibrosis. Treatments were classified into inflammation, energy, bile acid and fibrosis modulators. The analysis was conducted with Bayesian network model and surface under the cumulative ranking curve (SUCRA) analysis. Among 49 included trials, treatments modulating energy (Risk ratio (RR): 1.92, Credible intervals (Crl): 1.59-2.34) were most likely to achieve NASH resolution followed by treatments modulating fibrosis (RR 1.66, Crl: 0.65-4.50), bile acids (RR: 1.37, Crl: 0.99-1.92) and inflammation (RR: 1.00, Crl: 0.75-1.33). Energy and bile acids modulation were effective in at least 2-point NAS reduction without worsening of fibrosis (RR: 1.52, Crl 1.30-1.77; RR: 1.69, Crl 1.41-2.03) and at least 1-point reduction in fibrosis (RR: 1.26, Crl:1.05-1.49; RR: 1.54, Crl: 1.20-1.97). CONCLUSIONS: This network analysis demonstrates the relative superiority of drugs modulating energy pathways and bile acids in NASH treatment. This guides the development and selection of drugs for combination therapies.

Systematic review with meta-analysis: The prevalence, risk factors and outcomes of upper gastrointestinal tract Crohn's disease.

AIMS: Upper gastrointestinal Crohn's disease (UGI-CD) is an important subclassification of Crohn's Disease (CD). We performed a systematic review and meta-analysis to evaluate the prevalence, risk factors, and clinical outcomes associated with UGI-CD. METHODS: We searched Embase and Medline for articles reporting the clinical information of UGI-CD in CD patients, through 27 October 2020. Disease location and phenotype were coded according to the Montreal classification, and results were pooled with random effects by DerSimonian and Laird model. RESULTS: 26 articles were included. The prevalence of UGI-CD was 13%. UGI-CD was most commonly found in the stomach (56%) and was associated with concurrent ileocolonic involvement (54%). Non-stricturing, non-penetrating UGI-CD was the most common behavioral phenotype (61%). L4-jejunal disease was associated with the highest rates of surgery. Region of origin did not significantly influence the location and phenotype of UGI-CD. Young, male patients presenting with erythema nodosum, aphthous ulcers and stricturing-phenotype are more likely to have UGI-CD, which in turn is linked to increased risk of hospitalization and surgery. CONCLUSION: UGI-CD is present in 13% of patients with CD, and patients with L4-jejunal disease are more likely to require surgery. Further studies examining the effect of ethnicity and region on UGI-CD are needed.

Kono-S anastomosis for Crohn's disease: a systemic review, meta-analysis, and meta-regression.

The Kono-S anastomosis was introduced in 2011 as an alternative anastomosis in Crohn's disease (CD) surgery. Since then, prevailing evidence of the favorable results of the Kono-S anastomosis has been published from around the world. We conducted this study to analyze the effectiveness of the Kono-S anastomosis, by searching Medline, Embase, CNKI, and google scholar. Binominal data were analyzed after Freeman-Tukey double-arcsine transformation. Comparative data were analyzed using the Mantel-Haenszel model for dichotomous outcomes and the mean difference for continuous outcomes. We identified 676 patients who underwent surgery with a Kono-S anastomosis. Surgical recurrence was pooled at an average of 0% (CI: 0.00-0.01) and a reduced mean Rutgeerts score of 1.375 (CI: 0.727-2.023) after Kono-S anastomosis. Endoscopic recurrence after sensitivity analysis was 5% (CI: 0.00-0.15). Complications were rare, with a 3% incidence of ileus (CI: 0.01-0.05), a 4% incidence of small bowel obstruction (CI: 0.01-0.10), a 1% incidence of an anastomotic leak incidence (CI: 0.00-0.03), and a 10% incidence of postoperative infection (CI: 0.03-0.20). Evidence from this meta-analysis favors the Kono-S anastomosis for CD patients, especially for ileocolic anastomosis. Thus, clinicians should consider the applicability of Kono-S anastomosis in respective institutions.