AICAR transformylase/IMP cyclohydrolase (ATIC) is essential for de novo purine biosynthesis and infection by Cryptococcus neoformans.

The fungal pathogen Cryptococcus neoformans is a leading cause of meningoencephalitis in the immunocompromised. As current antifungal treatments are toxic to the host, costly, limited in their efficacy, and associated with drug resistance, there is an urgent need to identify vulnerabilities in fungal physiology to accelerate antifungal discovery efforts. Rational drug design was pioneered in de novo purine biosynthesis as the end products of the pathway, ATP and GTP, are essential for replication, transcription, and energy metabolism, and the same rationale applies when considering the pathway as an antifungal target. Here, we describe the identification and characterization of C. neoformans 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase/5'-inosine monophosphate cyclohydrolase (ATIC), a bifunctional enzyme that catalyzes the final two enzymatic steps in the formation of the first purine base inosine monophosphate. We demonstrate that mutants lacking the ATIC-encoding ADE16 gene are adenine and histidine auxotrophs that are unable to establish an infection in a murine model of virulence. In addition, our assays employing recombinantly expressed and purified C. neoformans ATIC enzyme revealed Km values for its substrates AICAR and 5-formyl-AICAR are 8-fold and 20-fold higher, respectively, than in the human ortholog. Subsequently, we performed crystallographic studies that enabled the determination of the first fungal ATIC protein structure, revealing a key serine-to-tyrosine substitution in the active site, which has the potential to assist the design of fungus-specific inhibitors. Overall, our results validate ATIC as a promising antifungal drug target.

Prostaglandin E2/EP4 axis is upregulated in Spondyloarthritis and contributes to radiographic progression.

Ankylosing spondylitis (AS) is an inflammatory disease leading to spine ankylosis; however, the mechanisms behind new bone formation are still not fully understood. Single Nucleotide Polymorphisms (SNPs) in PTGER4, encoding for the receptor EP4 of prostaglandin E2 (PGE2), are associated with AS. Since the PGE2-EP4 axis participates in inflammation and bone metabolism, this work aims at investigating the influence of the prostaglandin-E2 axis on radiographic progression in AS. In 185 AS (97 progressors), baseline serum PGE2 predicted progression, and PTGER4 SNP rs6896969 was more frequent in progressors. Increased EP4/PTGER4 expression was observed in AS circulating immune cells, synovial tissue, and bone marrow. CD14highEP4 + cells frequency correlated with disease activity, and when monocytes were cocultured with mesenchymal stem cells, the PGE2/EP4 axis induced bone formation. In conclusion, the Prostaglandin E2 axis is involved in bone remodelling and may contribute to the radiographic progression in AS due to genetic and environmental upregulation.

Splenic Dendritic Cells and Macrophages Drive B Cells to Adopt a Plasmablast Cell Fate.

Upon encountering cognate antigen, B cells can differentiate into short-lived plasmablasts, early memory B cells or germinal center B cells. The factors that determine this fate decision are unclear. Past studies have addressed the role of B cell receptor affinity in this process, but the interplay with other cellular compartments for fate determination is less well understood. Moreover, B cell fate decisions have primarily been studied using model antigens rather than complex pathogen systems, which potentially ignore multifaceted interactions from other cells subsets during infection. Here we address this question using a Plasmodium infection model, examining the response of B cells specific for the immunodominant circumsporozoite protein (CSP). We show that B cell fate is determined in part by the organ environment in which priming occurs, with the majority of the CSP-specific B cell response being derived from splenic plasmablasts. This plasmablast response could occur independent of T cell help, though gamma-delta T cells were required to help with the early isotype switching from IgM to IgG. Interestingly, selective ablation of CD11c+ dendritic cells and macrophages significantly reduced the splenic plasmablast response in a manner independent of the presence of CD4 T cell help. Conversely, immunization approaches that targeted CSP-antigen to dendritic cells enhanced the magnitude of the plasmablast response. Altogether, these data indicate that the early CSP-specific response is predominately primed within the spleen and the plasmablast fate of CSP-specific B cells is driven by macrophages and CD11c+ dendritic cells.

Internet-delivered interpretation training reduces worry and anxiety in individuals with generalized anxiety disorder: A randomized controlled experiment.

Objective: Generalized anxiety disorder (GAD) is a debilitating condition, characterized by negative interpretations about ambiguous situations. This study tested whether entirely internet-delivered interpretation training [cognitive bias modification (CBM)] versus control promotes positive interpretations and reduces worry and anxiety in individuals with GAD, with or without depression. Method: A two-arm (CBM; control) parallel-group randomized controlled experiment. Assessments were preintervention (T0), postintervention (T1), 1-month (T2) postintervention, and 3-month (T3) postintervention. Participants with GAD (with or without comorbid depression) were randomly allocated to either CBM (n = 115) or control (n = 115). Participants, but not researchers, were blind to allocated condition. Participants completed up to 10 online CBM or control sessions across 1 month. Interpretation bias [coprimary outcomes: scrambled sentence test (SST), recognition test (RT)], and number of negative thought intrusions during a breathing focus task were measured at T0 and T1. Self-reported levels of worry [Penn State Worry Questionnaire-trait (PSWQ trait); Penn State Worry Questionnaire-past week (PSWQ weekly)], anxiety [Generalized Anxiety Disorder scale (GAD-7)], depression [Patient Health Questionnaire (PHQ-9)], rumination [Ruminative Response Scale (RRS)], and repetitive negative thinking [RNT; Repetitive Thinking Questionnaire-trait (RTQ-trait)] were assessed at T0-T3. Results: The per-protocol analyses included N = 186 participants (CBM n = 94; control n = 92). As predicted, we found moderate-to-large training effects on the primary outcome of interpretation bias at T1. Secondary outcomes of negative thought intrusions at T1 and self-reported symptoms at T2 were all significantly lower in the CBM versus control condition. All but one effect (trait RNT) were sustained at T3. Conclusions: In this randomized controlled study, we found that fully online interpretation training ameliorated core features of GAD in individuals with or without comorbid depression up to 3 months posttraining. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Effects of modifying interpretation bias on transdiagnostic repetitive negative thinking.

OBJECTIVE: Repetitive negative thinking (RNT; e.g., worry and rumination) is common across emotional disorders, as is the tendency to generate negative interpretations (interpretation bias). Ameliorating negative interpretations via cognitive bias modification of interpretations (CBM-I) reduces worry/rumination, and improves mood in people diagnosed with generalized anxiety disorder (GAD) or depression. We investigated whether these findings generalize to high worry or rumination populations, irrespective of diagnosis, and whether effects are increased by enhancing emotional engagement with training with active generation of positive resolutions of ambiguity and imagery. METHOD: Community volunteers with excessive worry and/or rumination, who were above clinical cut-off on anxiety and/or depression measures, were allocated to an active control condition (n = 54), interpretation training condition with prior activation of RNT (CBM_RNT; n = 54), or training condition augmented with positive outcome generation and imagery (CBM_ENH; n = 53). Interpretation bias, RNT, and mood were assessed before and following 10 Internet-based sessions completed within a 1-month period. RNT and mood questionnaires were also completed at 1-month follow-up. RESULTS: After training, both forms of CBM-I (vs. control) facilitated more positive interpretations and reduced negative intrusions during a worry task. At 1-month follow-up, anxiety, depression, RNT, and worry in the past week were lower in the CBM-I than control conditions, but not rumination or trait worry. Compared with standard CBM-I, the augmented form facilitated more positive interpretations, reduced negative intrusions after training, and reduced trait rumination at 1-month follow-up, but it did not augment effects on trait worry, anxiety or depression. CONCLUSIONS: Interpretation bias maintains transdiagnostic RNT and Internet-based CBM-I can reduce longer-term RNT. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Best practices in DNA methylation: lessons from inflammatory bowel disease, psoriasis and ankylosing spondylitis.

Advances in genomic technology have enabled a greater understanding of the genetics of common immune-mediated diseases such as ankylosing spondylitis (AS), inflammatory bowel disease (IBD) and psoriasis. The substantial overlap in genetically identified pathogenic pathways has been demonstrated between these diseases. However, to date, gene discovery approaches have only mapped a minority of the heritability of these common diseases, and most disease-associated variants have been found to be non-coding, suggesting mechanisms of disease-association through transcriptional regulatory effects.Epigenetics is a major interface between genetic and environmental modifiers of disease and strongly influence transcription. DNA methylation is a well-characterised epigenetic mechanism, and a highly stable epigenetic marker, that is implicated in disease pathogenesis. DNA methylation is an under-investigated area in immune-mediated diseases, and many studies in the field are affected by experimental design limitations, related to study design, technical limitations of the methylation typing methods employed, and statistical issues. This has resulted in both sparsity of investigations into disease-related changes in DNA methylation, a paucity of robust findings, and difficulties comparing studies in the same disease.In this review, we cover the basics of DNA methylation establishment and control, and the methods used to examine it. We examine the current state of DNA methylation studies in AS, IBD and psoriasis; the limitations of previous studies; and the best practices for DNA methylation studies. The purpose of this review is to assist with proper experimental design and consistency of approach in future studies to enable a better understanding of the functional role of DNA methylation in immune-mediated disease.

Interpretation training to target repetitive negative thinking in generalized anxiety disorder and depression.

OBJECTIVE: Repetitive negative thinking (RNT) for example, worry in generalized anxiety disorder (GAD) and rumination in depression, is often targeted during psychological treatments. To test the hypothesis that negative interpretation bias contributes to worry and rumination, we assessed the effects of inducing more positive interpretations in reducing RNT. METHOD: Volunteers diagnosed with GAD (66) or depression (65) were randomly allocated to one of two versions of cognitive bias modification for interpretation (CBM-I), either with or without RNT priming prior to training, or a control condition, each involving 10 Internet-delivered sessions. Outcome measures of interpretation bias, a behavioral RNT task and self-reported worry, rumination, anxiety and depression were obtained at baseline, after home-based training and at 1-month follow-up (self-report questionnaires only). RESULTS: CBM-I training, across diagnostic groups, promoted a more positive interpretation bias and led to reductions in worry, rumination, and depressive symptoms, which were maintained at follow-up. Anxiety symptoms were reduced only in the GAD group at follow-up. There were no differences between CBM-I versions; brief priming of RNT did not influence CBM-I effectiveness. Level of interpretation bias post training partially mediated the effects of CBM-I on follow-up questionnaire scores. CONCLUSIONS: In contrast to some recent failures to demonstrate improvements following Internet-delivered CBM, we found that self-reported RNT and negative mood were reduced by CBM-I. This is consistent with a causal role for negative interpretation bias in both worry and rumination, suggesting a useful role for CBM-I within treatments for anxiety and depression. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Cognitive bias modification for interpretation with and without prior repetitive negative thinking to reduce worry and rumination in generalised anxiety disorder and depression: protocol for a multisession experimental study with an active control condition.

INTRODUCTION: Worry and rumination are two forms of repetitive thinking characterised by their negative content and apparently uncontrollable nature. Although worry and rumination share common features and have been conceptualised as part of a transdiagnostic repetitive negative thinking (RNT) process, it remains unclear whether they share the same underlying cognitive mechanisms. This multisession experimental study investigates the tendency to make negative interpretations regarding ambiguous information as a cognitive mechanism underlying RNT. We compare multisession cognitive bias modification for interpretations (CBM-I) with an active control condition to examine whether repeatedly training positive interpretations reduces worry and rumination in individuals with generalised anxiety disorder or depression, respectively. Further, we examine the potential modulatory effects of engaging in RNT immediately prior to CBM-I. DESIGN, METHODS AND ANALYSIS: A community sample of individuals meeting diagnostic criteria for either generalised anxiety disorder (n=60) or current major depressive episode (n=60) will be randomly allocated to CBM-I with prior RNT, CBM-I without prior RNT (ie, standard CBM-I), or an active control (no resolution of ambiguity) condition. All conditions receive a 3-week internet-based intervention consisting of one initial session at the first study visit and nine home-based sessions of CBM-I training (or active control). We will assess and compare the effects of CBM-I with and without prior RNT on 'near-transfer' measures of interpretation bias closely related to the training as well as 'far-transfer' outcomes related to RNT and emotional distress. Impact on questionnaire measures will additionally be assessed at 1-month follow-up. Multigroup analyses will be conducted to assess the impact of CBM-I on near-transfer and far-transfer outcome measures.

Defining the Nutritional and Metabolic Context of FGF21 Using the Geometric Framework.

Fibroblast growth factor 21 (FGF21) is the first known endocrine signal activated by protein restriction. Although FGF21 is robustly elevated in low-protein environments, increased FGF21 is also seen in various other contexts such as fasting, overfeeding, ketogenic diets, and high-carbohydrate diets, leaving its nutritional context and physiological role unresolved and controversial. Here, we use the Geometric Framework, a nutritional modeling platform, to help reconcile these apparently conflicting findings in mice confined to one of 25 diets that varied in protein, carbohydrate, and fat content. We show that FGF21 was elevated under low protein intakes and maximally when low protein was coupled with high carbohydrate intakes. Our results explain how elevation of FGF21 occurs both under starvation and hyperphagia, and show that the metabolic outcomes associated with elevated FGF21 depend on the nutritional context, differing according to whether the animal is in a state of under- or overfeeding.