Structure-guided discovery of novel AflG inhibitors for aflatoxin contamination control in aspergillus flavus.

Aflatoxins (AFs) are highly carcinogenic metabolites produced by Aspergillus species that can contaminate critical food staples, leading to significant health and economic risks. The cytochrome P450 monooxygenase AflG catalyzes an early step in AF biosynthesis, resulting in the conversion of averantin (AVN) to 5'-hydroxy-averantin. However, the molecular mechanism underlying the AflG-AVN interaction remains unclear. Here, we sought to understand the structural features of AflG in complex with AVN to enable the identification of inhibitors targeting the AflG binding pocket. To achieve this goal, we employed a comprehensive approach combining computational and experimental methods. Structural modeling and microsecond-scale molecular dynamics (MD) simulations yielded new insights into AflG architecture and unveiled unique ligand binding conformations of the AflG-AVN complex. High-throughput virtual screening of more than 1.3 million compounds pinpointed specific subsets with favorable predicted docking scores. The resulting compounds were ranked based on binding free energy calculations and evaluated with MD simulations and in vitro experiments with Aspergillus flavus. Our results revealed two compounds significantly inhibited AF biosynthesis. Comprehensive structural analysis elucidated the binding sites of competitive inhibitors and demonstrated their regulation of AflG dynamics. This structure-guided pipeline successfully enabled the identification of novel AflG inhibitors and provided novel molecular insights that will guide future efforts to develop effective therapeutics that prevent AF contamination.

Sleep Quality in Patients With Ocular Graft-Versus-Host Disease After Allogeneic Hematopoietic Stem Cell Transplantation.

OBJECTIVES: To investigate the sleep quality in patients with ocular graft-versus-host disease (oGVHD) compared with patients without oGVHD after allogeneic hematopoietic stem cell transplantation (alloHCT) and healthy controls. METHODS: This cross-sectional study analyzed 142 patients after alloHCT including 94 patients with oGVHD and 48 without. Fifty healthy controls were also enrolled. oGVHD was diagnosed according to International Chronic Ocular GVHD Consensus Group (ICOGCG) criteria. Sleep quality was assessed by the Chinese version of the Pittsburgh Sleep Quality Index (CPSQI). Poor sleep quality was defined as CPQSI score greater than 6. RESULTS: Patients after alloHCT demonstrated a significantly higher CPQSI score than those of controls {7.0 [interquartile range (IQR) 5.0-10.0] vs. 5.5 [IQR 4.8-7.0], P =0.002}, especially in the oGVHD subgroup (7.5 [IQR 5.0-11.0] vs. 6.0 [IQR 5.0-8.0], P =0.04) with nearly double prevalence of poor sleep quality (58 [62%] vs. 18 [37%], P =0.006). Poor sleep quality was strikingly correlated with oGVHD diagnosis (adjusted odds ratio [OR]=2.55, 95% confidence interval [CI]: 1.02-6.34, P =0.04) and systemic immunosuppressants (adjusted OR=2.61, 95% CI: 1.32-5.71, P =0.02). Among the ocular parameters, poor sleep quality was significantly associated with higher ICOGCG score (adjusted OR=1.20, 95% CI: 1.03-1.39, P =0.02) and lower tear film break-up time (adjusted OR=0.85, 95% CI: 0.74-0.99, P =0.05). CONCLUSIONS: Poor sleep quality was associated with an increased severity of oGVHD and tear film instability in the long-term alloHCT survivorship.

Vision-specific and cancer-specific quality of life in ocular graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

PURPOSE: To compare the vision-specific and cancer-specific quality of life (QOL) between patients with and without ocular graft-versus-host disease (oGVHD) after allogeneic hematopoietic stem cell transplantation (alloHCT). METHODS: This cross-sectional observational study analyzed 142 patients after alloHCT including 94 patients with oGVHD and 48 without. oGVHD was diagnosed according to International Chronic Ocular GVHD Consensus Group (ICOGCG) criteria. QOL was assessed by using the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25) and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30). RESULTS: Compared with non-oGVHD patients, patients with oGVHD had worse vision-specific (NEI VFQ-25: 64.3 ± 20.3 vs. 77.6 ± 19.3, P < 0.001) and cancer-specific (EORTC QLQ-C30: 59.9 ± 20.3 vs. 67.4 ± 17.5, P = 0.03) QOL, as well as impaired cognitive function (72.7 ± 22.1 vs. 82.3 ± 19.0, P = 0.01). The vision-specific QOL was significantly correlated with ICOGCG score (ß = - 1.88, 95%CI: - 3.35 to - 0.41, P = 0.01) and post-alloHCT medical expense (ß = - 5.70, 95%CI: - 10.35 to - 1.05, P = 0.02), while cancer-specific QOL was strikingly correlated with post-alloHCT medical expense (ß = - 9.91, 95%CI: - 14.43 to - 5.39, P < 0.001), frequency of ophthalmic medication (ß = - 0.93, 95%CI: - 1.64 to - 0.21, P = 0.01), education (ß = - 6.97, 95%CI: - 13.31 to - 0.62, P = 0.03), and peripheral blood stem cell use (ß = - 6.42, 95%CI: - 12.59 to - 0.25, P = 0.04). CONCLUSIONS: Patients with oGVHD experienced significant impairment in both vision-specific and cancer-specific QOL including cognitive function when compared with those without after alloHCT. Multidimensional QOL assessment should be included in the long-term alloHCT survivorship care.

Posterior segment complications and the risk factors after allogeneic hematopoietic stem cell transplantation.

PURPOSE: To study the posterior segment complications (PSC) and the risk factors in patients after allogeneic hematopoietic stem cell transplantation (HSCT). METHODS: This cross-sectional, case-control study enroled 143 patients who received allogeneic HSCT. Comprehensive ocular examinations were performed to evaluate PSC and ocular Graft-versus-Host Disease (oGVHD). PSC was diagnosed based on the characteristic fundus findings and auxiliary examinations. Visual-evoked potential was examined in patients with unexplained visual loss and suspected visual pathway pathology (VPP). Ocular surface disease index, corneal fluorescein staining, conjunctival injection and Schirmer's test were scored to diagnose oGVHD. RESULTS: PSC was detected in 36 (25.2%) patients, while 107 (74.8%) patients were not. Among them, 102 (71.3%) patients were diagnosed with oGVHD. The most common PSC included cytomegalovirus retinitis (13/143, 9.1%) and VPP (7/143, 4.9%). Central nervous system relapse of leukaemia was detected in four out of seven cases of VPP. Patients with PSC had worse visual acuity, lower prevalence and milder severity of oGVHD, and more donors from unrelated and human leucocyte antigen (HLA)-mismatch (all P < 0.05). PSC was associated with transplant from unrelated (OR = 6.494, 95% CI: 1.635-25.794, P = 0.008) and HLA-mismatched (OR = 7.193, 95% CI: 2.829-18.291, P < 0.001) donor but not with the occurrence of systemic GVHD or oGVHD. CONCLUSIONS: PSC in post-HSCT patients was more common than previously noted, deserving the concern of ophthalmologists, especially in patients with unrelated or HLA-mismatched donors.

Curcumin alleviates LPS-induced intestinal homeostatic imbalance through reshaping gut microbiota structure and regulating group 3 innate lymphoid cells in chickens.

Gastrointestinal dysfunction is associated with a disturbance of immune homeostasis, changes in the intestinal microbiome, alteration of the composition of the bile acid pool, and dynamic imbalance of group 3 innate lymphoid cells (ILC3s). Curcumin (CUR), a polyphenolic compound isolated from turmeric, has been known to attenuate intestinal inflammation in potential therapies for gastrointestinal diseases. It was hypothesized that CUR could target the gut microbiome to modulate bile acid (BA) metabolism and the function of ILC3s in ameliorating lipopolysaccharide (LPS)-induced imbalance of intestinal homeostasis in chickens. Seven hundred and twenty 1-day-old crossbred chickens were randomly divided into four treatments, namely CON_saline (basal diet + saline control), CUR_saline (basal diet + 300 mg kg-1 curcumin + saline), CON_LPS (basal diet + LPS), and CUR_LPS (basal diet + 300 mg kg-1 curcumin + LPS), each consisting of 6 replicates of 30 birds. On days 14, 17, and 21, the chickens in the CON_LPS and CUR_LPS treatments were intraperitoneally injected with LPS at 0.5 mg per kg BW. Dietary CUR supplementation significantly decreased LPS-induced suppression of growth performance and injury to the intestinal tight junctions and decreased the vulnerability to LPS-induced acute inflammatory response by inhibiting pro-inflammatory (interleukin-1ß and tumor necrosis factor-α) cytokines. CUR reshaped the cecal microbial community and BA metabolism, contributing to regulation of the intestinal mucosal immunity by promoting the anti-inflammatory (interleukin 10, IL-10) cytokines and enhancing the concentrations of primary and secondary BA metabolites (chenodexycholic acid, lithocholic acid). LPS decreased farnesoid X receptor (FXR) and G protein-coupled receptor class C group 5 member A synthesis, which was reversed by CUR administration, along with an increase in interleukin 22 (IL-22) production from ILC3s. Dietary supplementation of CUR increased the prevalence of Butyricicoccus and Enterococcus and enhanced the tricarboxylic acid cycle of intestinal epithelial cells. In addition, curcumin supplementation significantly increased sirtuin 1 and sirtuin 5 transcription and protein expression, which contributes to regulating mitochondrial metabolic and oxidative stress responses to alleviate LPS-induced enteritis. Our findings demonstrated that curcumin played a pivotal role in regulating the structure of the intestinal microbiome for health promotion and the treatment of intestinal dysbiosis. The beneficial effects of CUR may be attributed to the modulation of the BA-FXR pathway and inhibition of inflammation that induces IL-22 secretion by ILC3s in the intestinal lamina propria.

Ocular surface disease index questionnaire as a sensitive test for primary screening of chronic ocular graft-versus-host disease.

Background: After allogeneic hematopoietic stem cell transplantation (allo-HSCT), patients are followed up by transplant clinicians. Finding an effective primary screening method that transplant clinicians or patients can master is essential in the early referral of suspected chronic ocular graft-versus-host disease (coGVHD) to an ophthalmologist. This study investigated if the ocular surface disease index (OSDI) questionnaire could be used for coGVHD primary screening. Methods: This case-controlled, cross-sectional study enrolled 161 allo-HSCT patients. All participants completed an OSDI questionnaire and underwent a silt-lamp examination. Bulbar conjunctival injection (BCI) was assessed using torchlight, while tear volume was measured via the Schirmer test (ST). The receiver operating characteristic curve was used to evaluate the sensitivity, specificity, and cutoff values of OSDI, ST, and BCI grading. Performance comparisons of the 3 tests applied in isolation, parallel, and series were made. Results: There were 84 patients with and 77 patients without coGVHD. Compared to those without coGVHD, patients with coGVHD had significantly higher median values of OSDI, corneal fluorescein staining, conjunctival injection, conjunctival fibrosis, and meibum quality, but lower ST scores (All P values <0.001). The cutoff values for OSDI, ST, and BCI grade in the diagnosis of coGVHD were 19.4 points, 7 mm, and grade 0, respectively. The sensitivity and specificity of the tests based on the cutoff values were, respectively, 89.3% and 89.6% for OSDI, 91.7% and 59.7% for ST, and 78.6% and 70.1% for BCI. The area under the curve (AUC) value of OSDI was significantly higher than that of ST (0.931 vs. 0.826; P=0.010) and BCI grade (0.931 vs. 0.781; P<0.001). The AUC values of the combinations were lower than that of OSDI alone. Conclusions: The OSDI questionnaire can be used as a simple screening test for coGVHD as demonstrated by its high sensitivity and specificity in the transplant clinic and patients' self-monitoring. An OSDI greater than 19.4 could be considered an ophthalmology referral criterion.

Whole-exome sequencing reveals POLR3B variants associated with progeria-related Wiedemann-Rautenstrauch syndrome.

BACKGROUND: Wiedemann-Rautenstrauch syndrome (WRS) is a rare autosomal recessive neonatal progeroid disorder characterized by prenatal and postnatal growth retardation, short stature, a progeroid appearance, hypotonia, and mental impairment. CASE PRESENTATION: A 6-year-old patient, who initially presented with multiple postnatal abnormalities, facial dysplasia, micrognathia, skull appearance, hallux valgus, and congenital dislocation of the hip, was recruited in this study. The patient was initially diagnosed with progeria. The mother of the patient had abnormal fetal development during her second pregnancy check-up, and the clinical phenotype of the fetus was similar to that of the patient. Whole-exome sequencing (WES) of the patient was performed, and POLR3B compound heterozygous variants-c.2191G > C:p.E731Q and c.3046G > A:p.V1016M-were identified in the patient. Using Sanger sequencing, we found that the phenotypes and genotypes were segregated within the pedigree. These two variants are novel and not found in the gnomAD and 1000 Genomes databases. The two mutation sites are highly conserved between humans and zebrafish. CONCLUSIONS: Our study not only identified a novel WRS-associated gene, POLR3B, but also broadened the mutational and phenotypic spectra of POLR3B. Furthermore, WES may be useful for identifying rare disease-related genetic variants.

Ligand-bound glutamine binding protein assumes multiple metastable binding sites with different binding affinities.

Protein dynamics plays key roles in ligand binding. However, the microscopic description of conformational dynamics-coupled ligand binding remains a challenge. In this study, we integrate molecular dynamics simulations, Markov state model (MSM) analysis and experimental methods to characterize the conformational dynamics of ligand-bound glutamine binding protein (GlnBP). We show that ligand-bound GlnBP has high conformational flexibility and additional metastable binding sites, presenting a more complex energy landscape than the scenario in the absence of ligand. The diverse conformations of GlnBP demonstrate different binding affinities and entail complex transition kinetics, implicating a concerted ligand binding mechanism. Single molecule fluorescence resonance energy transfer measurements and mutagenesis experiments are performed to validate our MSM-derived structure ensemble as well as the binding mechanism. Collectively, our study provides deeper insights into the protein dynamics-coupled ligand binding, revealing an intricate regulatory network underlying the apparent binding affinity.

Dissecting the Conformational Dynamics-Modulated Enzyme Catalysis with Single-Molecule FRET.

Conformational changes of enzyme proteins are often coupled with a catalytic reaction and modulate the enzyme activity. Single-molecule technology is a powerful tool to study the mechanism of enzyme catalysis in these complicated cases. However, the chemical reaction cycles and conformational changes could not be monitored simultaneously in a single-molecule detection experiment, resulting in some unresolved key kinetic parameters. Here, we describe a method to extract all of the kinetic parameters from comprehensive single-molecule FRET (smFRET) measurements and model analysis. On the basis of the smFRET, we calculated the undetectable parameters by solving the rate equations of the kinetic model with the input of the smFRET-measured conformational state populations and state-transition rate constants. A case study of MalK2 ATPase demonstrates that this method could reveal the quantitative mechanism of the catalytic reaction of the enzyme as well as its coupled conformational dynamics. The strategy employed in this study could be widely applied to investigate the conformational fluctuation-coupled catalysis of other enzymes.

Novel expression and regulation of TIMP-1 in Epstein Barr virus-infected cells and its impact on cell survival.

Epstein Barr virus (EBV) uses various strategies to manipulate host cytokine production in favor of the survival of infected B-cells. Microarray and cytokine protein array assays revealed that tissue inhibitor of metalloproteinase-1 (TIMP-1) was significantly up-regulated in EBV-infected primary B cells and maintained in abundance in EBV-immortalized lymphoblastoid cell lines (LCLs). TIMP-1 plays critical roles in extracellular matrix homeostasis and regulates signaling pathways. In this study, we demonstrated that the EBV-encoded immediate early lytic protein, Zta, upregulates mainly TIMP-1 expression by binding to the AP-1 site within the TIMP-1 promoter. Moreover, knockdown of TIMP-1 expression promoted cisplastin and cold shock-induced death of LCLs. This study provides a mechanistic link between EBV-induced TIMP-1 expression and its impact on LCL survival.

p53 and Sp1 cooperate to regulate the expression of Epstein-Barr viral Zta protein.

Epstein-Barr virus (EBV) belongs to the gammaherpesvirus family. To produce infectious progeny, EBV reactivates from latency into the lytic cycle by expressing the determinative lytic transactivator, Zta. In the presence of histone deacetylase inhibitor (HDACi), p53 is a prerequisite for the initiation of the EBV lytic cycle by facilitating the expression of Zta. In this study, a serial mutational analysis of Zta promoter (Zp) indicated an important role for the ZID element in responding to HDACi induction and p53 binds to this ZID element together with Sp1, a universal transcription factor. Abolition of the DNA-binding ability of Sp1 reduces the inducibility of ZID by HDACi and also reduces the amount of p53 binding to ZID. Finally, it was shown that EBV in p53-positive-lymphoblastoid cell lines (LCLs) can enter into the lytic cycle spontaneously; however, knockdown of p53 in LCLs leads to retardation of EBV reactivation.