Solid-Phase-Supported Chemoenzymatic Synthesis and Analysis of Chondroitin Sulfate Proteoglycan Glycopeptides.

Proteoglycans (PGs), consisting of glycosaminoglycans (GAGs) linked with the core protein through a tetrasaccharide linkage region, play roles in many important biological events. The chemical synthesis of PG glycopeptides is extremely challenging. In this work, the enzymes required for synthesis of chondroitin sulfate (CS) PG (CSPG) have been expressed and the suitable sequence of enzymatic reactions has been established. To expedite CSPG synthesis, the peptide acceptor was immobilized on solid phase and the glycan units were directly installed enzymatically onto the peptide. Subsequent enzymatic chain elongation and sulfation led to the successful synthesis of CSPG glycopeptides. The CS dodecasaccharide glycopeptide was the longest homogeneous CS glycopeptide synthesized to date. The enzymatic synthesis was much more efficient than the chemical synthesis of the corresponding CS glycopeptides, which could reduce the total number of synthetic steps by 80%. The structures of the CS glycopeptides were confirmed by mass spectrometry analysis and NMR studies. In addition, the interactions between the CS glycopeptides and cathepsin G were studied. The sulfation of glycan chain was found to be important for binding with cathepsin G. This efficient chemoenzymatic strategy opens new avenues to investigate the structures and functions of PGs.

Binding of Per- and Polyfluoroalkyl Substances (PFAS) to the PPARγ/RXRα-DNA Complex.

Nuclear receptors are the fundamental building blocks of gene expression regulation and the focus of many drug targets. While binding to DNA, nuclear receptors act as transcription factors, governing a multitude of functions in the human body. Peroxisome proliferator-activator receptor γ (PPARγ) and the retinoid X receptor α (RXRα) form heterodimers with unique properties and have a primordial role in insulin sensitization. This PPARγ/RXRα heterodimer has been shown to be impacted by per- and polyfluoroalkyl substances (PFAS) and linked to a variety of significant health conditions in humans. Herein, a selection of the most common PFAS (legacy and emerging) was studied utilizing molecular dynamics simulations for PPARγ/RXRα. The local and global structural effects of PFAS binding on the known ligand binding pockets of PPARγ and RXRα as well as the DNA binding domain (DBD) of RXRα were inspected. The binding free energies were predicted computationally and were compared between the different binding pockets. In addition, two electronic structure approaches were utilized to model the interaction of PFAS within the DNA binding domain, density functional theory (DFT) and domain-based pair natural orbital coupled cluster with perturbative triples (DLPNO-CCSD(T)) approaches, with implicit solvation. Residue decomposition and hydrogen-bonding analysis were also performed, detailing the role of prominent residues in molecular recognition. The role of l-carnitine is explored as a potential in vivo remediation strategy for PFAS interaction with the PPARγ/RXRα heterodimer. In this work, it was found that PFAS can bind and act as agonists for all of the investigated pockets. For the first time in the literature, PFAS are postulated to bind to the DNA binding domain in a nonspecific manner. In addition, for the PPARγ ligand binding domain, l-carnitine shows promise in replacing smaller PFAS from the pocket.

Isolation and functional characterization of novel isoprene synthase from Artocarpus heterophyllus (jackfruit).

Isoprene, a Natural Volatile Organic Compound (NVOC) is one of the chief by-products of plant metabolism with important applications in the synthesis of rubber and pharmaceuticals as a platform molecule. Isoprene was obtained earlier from petroleum sources; however, to synthesise it new fermentation-based strategies are being adopted. Bioinformatics tools were utilised to isolate the Isoprene Synthase (IspS) gene which converts the precursors Isopentenyl Diphosphate (IPP) and Dimethylallyl Diphosphate (DMAPP) into isoprene. Metabolic engineering strategies were to synthesise an isoprene-producing recombinant clone derived from Artocarpus heterophyllus (jackfruit). The functional characterization was done using the overexpression of the isoprene synthase gene in an Escherichia coli BL21 host. The recombinant clone, ISPS_GBL_001 (submitted to GenBank, National Centre for Biotechnology Information or NCBI) was used for fermentation in the batch and fed-batch mode to produce isoprene. Isoprene productivity of 0.08 g/g dextrose was obtained via the fed-batch mode maintaining the process parameters at optimum. The quantification and confirmation of isoprene was done using gas chromatography (GC) and GC-mass spectrometry (GC-MS) of the extracted sample, respectively. This study makes significant contribution to the ongoing research on bio-isoprene synthesis by highlighting a novel plant source of the IspS gene followed by, its successful expression in a recombinant host, validated by fermentation. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03441-7.

Safety of SARS-CoV-2 vaccination in patients with inflammatory bowel disease: A systematic review and meta-analysis.

INTRODUCTION: Risk of adverse effects and flare of inflammatory bowel disease (IBD) are frequently cited reasons for COVID-19 vaccine hesitancy. METHODS: Electronic databases were searched to identify studies reporting the use of COVID-19 vaccine in IBD. We selected studies reporting the incidence of various adverse effects (local or systemic) and flares of IBD after COVID-19 vaccination. The pooled incidence rates for various adverse effects, stratified for the dose and the type of vaccine (adenoviral or mRNA) were estimated. RESULTS: Nine studies (16 vaccination cohorts) were included. The pooled incidence rate of overall adverse events was 0.55 (95%CI, 0.45-0.64, I2= 95%). The pooled incidence rate of local adverse events was 0.64 (0.47-0.78, I2= 100%). The pooled incidence rates of fatigue, headache, myalgia, fever and chills were 0.30 (0.21-0.40, I2= 99%), 0.23 (0.17-0.30, I2= 99%), 0.18 (0.13-0.24, I2= 99%), 0.10 (0.06-0.17, I2= 98%) and 0.15 (0.06-0.3, I2= 86%), respectively. The pooled incidence rates of severe adverse events, adverse events requiring hospitalization and flares of IBD following COVID-19 vaccination were 0.02 (0.00-0.12, I2= 97%), 0.00 (0.00-0.01, I2= 27%) and 0.01 (0.01-0.03, I2= 45%), respectively. CONCLUSION: COVID-19 vaccination in patients with IBD appears to be safe with only mild adverse events. Flares of IBD and severe adverse events requiring hospitalization were infrequent.

Endoscopic Ultrasound-guided Drainage of Patients With Infected Walled-off Necrosis: Which Stent to Choose?

BACKGROUND: Endoscopic ultrasound (EUS)-guided drainage is the preferred treatment of pancreatic fluid collections (PFC). However, the choice of the stent for EUS-guided drainage in critically ill PFC cases with infected walled-off necrosis (WON) and/or organ failure (OF) remains unknown. MATERIALS AND METHODS: Between January 2018 and December 2019, consecutive patients with symptomatic PFC subjected to EUS-guided drainage using biflanged metal stents (BFMS) or double-pigtail plastic stents (DPPS) were compared for technical success, clinical success, duration of the procedure, need for intensive care unit stay, duration of intensive care unit stay, ventilator need, resolution of OF, the duration for resolution of OF, complications, need for salvage percutaneous drainage or surgery and mortality. A subgroup of patients having infected WON with/without OF were analyzed separately. RESULTS: Among 120 patients (84.6% males) with PFC (108 WON, 22 pseudocyst) who underwent EUS-guided drainage, there was no difference in outcome parameters in BFMS and DPPS groups. Among patients with WON, clinical success was significantly higher (96.2% vs. 81.8%, P=0.04), with significantly shorter hospital stay (6 vs. 10 d) and procedure duration (17.18±4.6 vs. 43.6±9.7 min, P<0.0001) in the BFMS group. Among patients with infected WON with/without OF, the clinical success was significantly higher (100% vs. 73.9%, P=0.02), and the duration of the procedure was significantly lower (16.28±4.4 vs. 44.39±10.7, P<0.0001) in BFMS compared with DPPS group. CONCLUSION: EUS-guided drainage of WON using BFMS scores over DPPS. In patients having infected WON with/without OF, BFMS may be preferred over DPPS.

Effectiveness and Durability of COVID-19 Vaccination in 9447 Patients With IBD: A Systematic Review and Meta-Analysis.

BACKGROUND AND AIMS: The serological responses after severe acute respiratory syndrome coronavirus 2 vaccination may be attenuated in immunocompromised individuals. The study aimed to systematically evaluate the seroconversion rates after complete vaccination for coronavirus disease 2019 (COVID-19) in patients with inflammatory bowel disease (IBD). METHODS: Electronic databases were searched to identify studies reporting response to COVID-19 vaccination in IBD. Pooled seroconversion rates after complete vaccination were calculated. Subgroup analysis for vaccine types was also performed. Pooled seroconversion rates for various drugs or classes were also estimated. The pooled rates of breakthrough infections in vaccinated IBD patients were estimated. The pooled neutralization rates after complete vaccination were also estimated. The studies reporting durability of titers were systematically assessed. RESULTS: A total of 46 studies were included. The pooled seroconversion rate for complete vaccination (31 studies, 9447 patients) was 0.96 (95% confidence interval [CI], 0.94-0.97; I2 = 90%). When compared with healthy control subjects, the pooled relative risk of seroconversion was lower (0.98; 95% CI, 0.98-0.99; I2 = 39%). The pooled seroconversion rates were statistically similar among various drug classes. The pooled positivity of neutralization assays (8 studies, 771 participants) was 0.80 (95% CI, 0.70-0.87; I2 = 82%). The pooled relative risk of breakthrough infections in vaccinated IBD patients was similar to vaccinated control subjects (0.60; 95% CI, 0.25-1.42; I2 = 79%). Most studies suggested that titers fall after 4 weeks of COVID-19 vaccination, and the decay was higher in patients on anti-tumor necrosis factor alone or combination with immunomodulators. An additional dose of COVID-19 vaccine elicited serological response in most nonresponders to complete vaccination. CONCLUSIONS: Complete COVID-19 vaccination is associated with seroconversion in most patients with IBD. The decay in titers over time necessitates consideration of additional doses in these patients.