Akkermansia muciniphila exoglycosidases target extended blood group antigens to generate ABO-universal blood.

Matching donor and recipient blood groups based on red blood cell (RBC) surface ABO glycans and antibodies in plasma is crucial to avoid potentially fatal reactions during transfusions. Enzymatic conversion of RBC glycans to the universal group O is an attractive solution to simplify blood logistics and prevent ABO-mismatched transfusions. The gut symbiont Akkermansia muciniphila can degrade mucin O-glycans including ABO epitopes. Here we biochemically evaluated 23 Akkermansia glycosyl hydrolases and identified exoglycosidase combinations which efficiently transformed both A and B antigens and four of their carbohydrate extensions. Enzymatic removal of canonical and extended ABO antigens on RBCs significantly improved compatibility with group O plasmas, compared to conversion of A or B antigens alone. Finally, structural analyses of two B-converting enzymes identified a previously unknown putative carbohydrate-binding module. This study demonstrates the potential utility of mucin-degrading gut bacteria as valuable sources of enzymes for production of universal blood for transfusions.

Truncated glycosyltransferase coding regions in novel ABO alleles give rise to weak A or B blood group expression and discrepant typing results.

BACKGROUND: Correct ABO blood-group matching between donor and patient is crucial for safe transfusions. We investigated the underlying reason causing inconclusive ABO serology in samples referred to our laboratory. STUDY DESIGN AND METHODS: Flow cytometric analysis, ABO genotyping, and sequencing were used to characterize ABO-discrepant blood samples (n = 13). ABO gene variants were inserted in a GFP-containing bicistronic vector to assess A/B expression following overexpression in HeLa cells. RESULTS: Seven novel alleles with nonsense mutations predicted to truncate the encoded ABO glycosyltransferases were identified. While these variants could represent O alleles, serology showed signs of ABO glycosyltransferase activity. ABO*A1.01-related alleles displayed remarkably characteristic percentages of A-positive cells for samples with the same variant: c.42C>A (p.Cys14*; 10%), c.102C>A (p.Tyr34*; 31%-32%, n = 2), c.106dup (p.Val36Glyfs*21; 16%-17%, n = 3) or c.181_182ins (p.Leu61Argfs*21; 12%-13%, n = 2). Transfection studies confirmed significantly decreased A expression compared to wild type. The remaining variants were found on ABO*B.01 background: c.1_5dup (pGly3Trpfs*20), c.15dup (p.Arg6Alafs*51) or c.496del (p.Thr166Profs*26). Although the absence of plasma anti-B was noted overall, B antigen expression was barely detected on erythrocytes. Overexpression confirmed decreased B in two variants compared to wildtype while c.1_5dup only showed a non-significant downward trend. CONCLUSION: Samples displaying aberrant ABO serology revealed seven principally interesting alleles. Despite the presence of truncating mutations, normally resulting in null alleles, low levels of ABO antigens were detectable where alterations affected ABO exons 1-4 but not exon 7. This is compatible with the previously proposed concept that alternative start codons in early exons can be used to initiate the translation of functional ABO glycosyltransferase.

An update on the GLOB blood group system (and former GLOB collection).

CONCLUSIONS: The main change that has occurred in the GLOB blood group system since the GLOB review published in this journal in 2013 is the addition of an antigen. The high-prevalence PX2 antigen, originally recognized as the x2 glycosphingolipid, is expressed on red blood cells of most individuals and is elevated in the rare PP1Pk-negative p blood group phenotype. P synthase, encoded by B3GALNT1, was found to elongate paragloboside to PX2 by adding the terminal ß3GalNAc moiety. Hence, PX2 was moved from the GLOB collection to the GLOB system. The presence of naturally-occurring anti-PX2 was noted in P1k and P2k individuals exhibiting nonfunctional P synthase. Although the clinical significance of this specificity remains unclear, a recommendation to avoid transfusing Pk patients with p phenotype blood has been made. Currently, 13 mutations at the highly conserved B3GALNT1 locus have been found to abolish P synthase function and are recognized as null alleles by the International Society of Blood Transfusion. A new allele with a missense mutation but resulting in normal expression of P has been assigned GLOB*02. Finally, the GLOB collection was made obsolete after the move of LKE antigen to the 901 series.

The partial dopamine D2 receptor agonist aripiprazole is associated with weight gain in adolescent anorexia nervosa.

OBJECTIVE: Finding medication to support treatment of anorexia nervosa has been difficult. Neuroscience-based approaches may help in this effort. Recent brain imaging studies in adults and adolescents with anorexia nervosa suggest that dopamine-related reward circuits are hypersensitive and could provide a treatment target. METHODS: Here, we present a retrospective chart review of 106 adolescents with anorexia nervosa some of whom were treated with the dopamine D2 receptor partial agonist aripiprazole during treatment in a specialized eating disorder program. RESULTS: The results show that aripiprazole treatment was associated with greater increase in body mass index (BMI) during treatment. DISCUSSION: The use of dopamine receptor agonists may support treatment success in anorexia nervosa and should be further investigated.

Weight restoration on a high carbohydrate refeeding diet promotes rapid weight regain and hepatic lipid accumulation in female anorexic rats.

BACKGROUND: There is currently no standard clinical refeeding diet for the treatment of anorexia nervosa (AN). To provide the most efficacious AN clinical care, it is necessary to define the metabolic effects of current refeeding diets. METHODS: An activity-based model of anorexia nervosa (AN) was used in female rats. AN was induced over 7d by timed access to low fat (LF) diet with free access to a running wheel. Plasma hormones/metabolites and body composition were assessed at baseline, AN diagnosis (day 0), and following 28d of refeeding on LF diet. Energy balance and expenditure were measured via continuous indirect calorimetry on days -3 to +3. RESULTS: AN induction caused stress as indicated by higher levels of corticosterone versus controls (p < 0.0001). The rate of weight gain during refeeding was higher in AN rats than controls (p = 0.0188), despite lower overall energy intake (p < 0.0001). This was possible due to lower total energy expenditure (TEE) at the time of AN diagnosis which remained significantly lower during the entire refeeding period, driven by markedly lower resting energy expenditure (REE). AN rats exhibited lower lipid accumulation in visceral adipose tissues (VAT) but much higher liver accumulation (62 % higher in AN than control; p < 0.05) while maintaining the same total body weight as controls. It is possible that liver lipid accumulation was caused by overfeeding of carbohydrate suggesting that a lower carbohydrate, higher fat diet may be beneficial during AN treatment. To test whether such a diet would be accepted clinically, we conducted a study in adolescent female AN patients which showed equivalent palatability and acceptability for LF and moderate fat diets. In addition, this diet was feasible to provide clinically during inpatient treatment in this population. CONCLUSION: Refeeding a LF diet to restore body weight in female AN rats caused depressed TEE and REE which facilitated rapid regain. However, this weight gain was metabolically unhealthy as it resulted in elevated lipid accumulation in the liver. It is necessary to investigate the use of other diets, such as lower carbohydrate, moderate fat diets, in pre-clinical models to develop the optimal clinical refeeding diets for AN.

Body size overestimation and its association with body mass index, body dissatisfaction, and drive for thinness in anorexia nervosa.

BACKGROUND: Body size overestimation is a fundamental feature in anorexia nervosa (AN). There have been inconclusive findings about the extent to which this feature distinguishes psychopathology and some authors have argued that overestimation may be a function of lower body mass index (BMI). METHODS: We examine body size estimation accuracy and body dissatisfaction in 74 females with AN and 11 age-matched female controls using two well-established psychophysical procedures. RESULTS: Participants with AN overestimated their body size more and had greater body dissatisfaction than controls. Size accuracy was found to be independent of BMI and correlated with body dissatisfaction and drive for thinness in participants with AN. CONCLUSIONS: We conclude that overestimation of body size in AN is related to the psychopathology associated with the disorder and is not due to any perceptual tendency for people with lower BMI to overestimate their body size. We discuss the implications of these findings for treatment of AN.

Localized brain volume and white matter integrity alterations in adolescent anorexia nervosa.

OBJECTIVE: The neurobiological underpinnings of anorexia nervosa (AN) are poorly understood. In this study, we tested whether brain gray matter (GM) and white matter (WM) in adolescents with AN would show alterations comparable to those in adults. METHOD: We used magnetic resonance imaging to study GM and WM volume, and diffusion tensor imaging to assess fractional anisotropy for WM integrity in 19 adolescents with AN and 22 controls. RESULTS: Individuals with AN showed greater left orbitofrontal, right insular, and bilateral temporal cortex GM, as well as temporal lobe WM volumes compared to controls. WM integrity in adolescents with AN was lower (lower fractional anisotropy) in fornix, posterior frontal, and parietal areas, but higher in anterior frontal, orbitofrontal, and temporal lobes. In individuals with AN, orbitofrontal GM volume correlated negatively with sweet taste pleasantness. An additional comparison of this study cohort with adult individuals with AN and healthy controls supported greater orbitofrontal cortex and insula volumes in AN across age groups. CONCLUSIONS: This study indicates larger orbitofrontal and insular GM volumes, as well as lower fornix WM integrity in adolescents with AN, similar to adults. The pattern of larger anteroventral GM and WM volume as well as WM integrity, but lower WM integrity in posterior frontal and parietal regions may indicate that developmental factors such as GM pruning and WM growth could contribute to brain alterations in AN. The negative correlation between taste pleasantness and orbitofrontal cortex volume in individuals with AN could contribute to food avoidance in this disorder.

Increased physical activity not decreased energy intake is associated with inpatient medical treatment for anorexia nervosa in adolescent females.

There is a dearth of data regarding changes in dietary intake and physical activity over time that lead to inpatient medical treatment for anorexia nervosa (AN). Without such data, more effective nutritional therapies for patients cannot be devised. This study was undertaken to describe changes in diet and physical activity that precede inpatient medical hospitalization for AN in female adolescents. This data can be used to understand factors contributing to medical instability in AN, and may advance rodent models of AN to investigate novel weight restoration strategies. It was hypothesized that hospitalization for AN would be associated with progressive energy restriction and increased physical activity over time. 20 females, 11-19 years (14.3±1.8 years), with restricting type AN, completed retrospective, self-report questionnaires to assess dietary intake and physical activity over the 6 month period prior to inpatient admission (food frequency questionnaire, Pediatric physical activity recall) and 1 week prior (24 hour food recall, modifiable activity questionnaire). Physical activity increased acutely prior to inpatient admission without any change in energy or macronutrient intake. However, there were significant changes in reported micronutrient intake causing inadequate intake of Vitamin A, Vitamin D, and pantothenic acid at 1 week versus high, potentially harmful, intake of Vitamin A over 6 months prior to admission. Subject report of significantly increased physical activity, not decreased energy intake, were associated with medical hospitalization for AN. Physical activity and Vitamin A and D intake should be carefully monitored following initial AN diagnosis, as markers of disease progression as to potentially minimize the risk of medical instability.

Alterations in brain structures related to taste reward circuitry in ill and recovered anorexia nervosa and in bulimia nervosa.

OBJECTIVE: The pathophysiology of anorexia nervosa remains obscure, but structural brain alterations could be functionally important biomarkers. The authors assessed taste pleasantness and reward sensitivity in relation to brain structure, which may be related to food avoidance commonly seen in eating disorders. METHOD: The authors used structural MR imaging to study gray and white matter volumes in women with current restricting-type anorexia nervosa (N=19), women recovered from restricting-type anorexia nervosa (N=24), women with bulimia nervosa (N=19), and healthy comparison women (N=24). RESULTS: All eating disorder groups exhibited increased gray matter volume of the medial orbitofrontal cortex (gyrus rectus). Manual tracing confirmed larger gyrus rectus volume, and volume predicted taste pleasantness ratings across all groups. Analyses also indicated other morphological differences between diagnostic categories. Antero-ventral insula gray matter volumes were increased on the right side in the anorexia nervosa and recovered anorexia nervosa groups and on the left side in the bulimia nervosa group relative to the healthy comparison group. Dorsal striatum volumes were reduced in the recovered anorexia nervosa and bulimia nervosa groups and predicted sensitivity to reward in all three eating disorder groups. The eating disorder groups also showed reduced white matter in right temporal and parietal areas relative to the healthy comparison group. The results held when a range of covariates, such as age, depression, anxiety, and medications, were controlled for. CONCLUSION: Brain structure in the medial orbitofrontal cortex, insula, and striatum is altered in eating disorders and suggests altered brain circuitry that has been associated with taste pleasantness and reward value.

Cognitive set-shifting in anorexia nervosa.

OBJECTIVE: Adult anorexia nervosa (AN) is associated with inefficient cognitive flexibility and set-shifting. Whether such inefficiencies also characterize adolescent AN is an important area of research. METHOD: Adolescents with AN and matched controls were administered a computerized task that required initial learning of an explicit rule using corrective feedback and learning of a new rule after a set number of trials. Adult patients with AN and controls were also examined. RESULTS: Adolescents with AN did not differ from matched controls with respect to set-shifting cost (decrease in performance after rule change), whereas adults with AN had significantly greater set-shifting cost compared with controls. DISCUSSION: This study suggests that set-shifting inefficiencies may not be a vulnerability factor for AN development in adolescents with AN, but might become an important aspect of the disorder at later age, and could point towards developmental neurobiologic brain changes that could affect AN at different ages.

Heightened fear of uncertainty in anorexia and bulimia nervosa.

OBJECTIVE: To test whether intolerance of uncertainty (IU) is related to eating disorder (ED) pathology. METHOD: Thirty individuals with anorexia nervosa (AN), 19 with bulimia nervosa (BN), and 28 healthy control women (CW) completed the Intolerance of Uncertainty Scale (IUS). RESULTS: AN and BN groups showed higher IU compared with CW. In AN and BN, Harm Avoidance and Depression scores were positively correlated with IU. In AN but not BN, IU was related positively to Drive for Thinness and Body Dissatisfaction. DISCUSSION: Elevated IU is associated with AN and BN. Anxious traits may be inherent in EDs and IU could be a developmental factor contributing to anxiety, mood, and ED behavior in AN and BN.

Altered implicit category learning in anorexia nervosa.

OBJECTIVE: Recent research has identified specific cognitive deficits in patients with anorexia nervosa (AN), including impairment in executive functioning and attention. Another such cognitive process, implicit category learning has been less studied in AN. This study examined whether implicit category learning is impaired in AN. METHOD: Twenty-one women diagnosed with AN and 19 control women (CW) were administered an implicit category learning task in which they were asked to categorize simple perceptual stimuli (Gabor patches) into one of two categories. Category membership was based on a linear integration (i.e., an implicit task) of two stimulus dimensions (orientation and spatial frequency of the stimulus). RESULTS: AN individuals were less accurate on implicit category learning relative to age-matched CW. Model-based analyses indicated that, even when AN individuals used the appropriate (i.e., implicit) strategy they were still impaired relative to CW who also used the same strategy. In addition, task performance in AN patients was worse the higher they were in self-reported novelty seeking and the lower they were in sensitivity to punishment. CONCLUSIONS: These results indicate that AN patients have implicit category learning deficits, and given this type of learning is thought to be mediated by striatal dopamine pathways, AN patients may have deficits in these neural systems. The finding of significant correlations with novelty seeking and sensitivity to punishment suggests that feedback sensitivity is related to implicit learning in AN.

A double-blind, placebo-controlled study of risperidone for the treatment of adolescents and young adults with anorexia nervosa: a pilot study.

OBJECTIVE: The purpose of this double-blind, placebo-controlled exploratory pilot study was to evaluate the safety and efficacy of risperidone for the treatment of anorexia nervosa. METHOD: Forty female subjects 12 to 21 years of age (mean, 16 years) with primary anorexia nervosa in an eating disorders program were randomized to receive risperidone (n = 18) or placebo (n = 22). Subjects completed the Eating Disorder Inventory 2, Color-A-Person Test, Body Image Software, and Multidimensional Anxiety Scale for Children at baseline and regular intervals. Weight, laboratory values, and electrocardiograms were monitored. Study medication was started at 0.5 mg daily and titrated upward weekly in 0.5-mg increments to a maximum dose of 4 mg until the subject reached a study endpoint. RESULTS: The mean dose for the risperidone group was 2.5 mg and for the placebo group was 3 mg for a mean duration of 9 weeks. Subjects taking risperidone had a significant decrease on the Eating Disorder Inventory 2 Drive for Thinness subscale over the first 7 weeks (effect size, 0.88; p = .002), but this difference was not sustained to the end of the study (p = .13). The Eating Disorder Inventory 2 Interpersonal Distrust subscale decreased significantly more in subjects taking risperidone (effect size, 0.60; p = .03). Subjects taking risperidone had increased prolactin levels (week 7; p = .001). There were no significant differences between groups at baseline or the end of the study for the other rating scales, change in weight, or laboratory measurements. CONCLUSIONS: This study does not demonstrate a benefit for the addition of risperidone in adolescents with anorexia nervosa during the weight-restoration phase of care. Clinical trial registration information-A Double-Blind, Placebo-Controlled Study of Risperidone for the Treatment of Anorexia Nervosa, http://www.clinicaltrials.gov, NCT00140426.

Altered fimbria-fornix white matter integrity in anorexia nervosa predicts harm avoidance.

The eating disorder anorexia nervosa (AN) is associated with high anxiety. The brain mechanisms that drive those behaviors are unknown. In this study we wanted to test whether brain white matter (WM) integrity is altered in AN, and related to heightened anxiety. Sixteen adult women with AN (mean age 24 ± 7 years) and 17 healthy control women (CW, mean age 25 ± 4 years) underwent diffusion tensor imaging (DTI) of the brain. The DTI brain images were used to calculate the fractional anisotropy (FA) of WM tracts, which is a measure for WM integrity. AN individuals compared to CW showed clusters of significantly reduced FA (p<0.05, corrected) in the bilateral fimbria-fornix and the fronto-occipital fasciculus, as well as the posterior cingulum WM. In the AN group, Harm Avoidance was predicted by FA in the left and right fimbria-fornix. Those findings were not due to WM volume deficits in AN. This study indicates that WM integrity is abnormal in AN in limbic and association pathways, which could contribute to disturbed feeding, emotion processing and body perception in AN. The prediction of Harm Avoidance in AN by fimbria-fornix WM integrity suggests that this pathway may be mechanistically involved in high anxiety in AN.

Heightened sensitivity to reward and punishment in anorexia nervosa.

OBJECTIVE: The objective of this study is to test whether females with anorexia nervosa (AN) have increased sensitivity to punishing or rewarding stimuli, behaviors that could drive high self-control and anxious, avoidant behaviors. METHOD: Sixty-four females completed the study: 33 control females (CFs, mean age 19.7 years) and 31 females with AN (mean age 19.6 years). Participants completed diagnostic exams, questionnaires for eating disorder severity and personality, and the Sensitivity to Punishment/Sensitivity to Reward Questionnaire (SPSRQ). RESULTS: Females with AN scored higher than CFs on SPSRQ sensitivity to punishment (p < 0.00001) and sensitivity to reward (p = 0.005). Females with AN without anxiety or depression continued to have increased SPSRQ scores compared to CFs. DISCUSSION: This is the first study comparing the SPSRQ in females with AN and CFs. Results suggest that reward and punishment sensitivity are increased in females with AN and could be potential trait markers. It is possible that harm-avoidant, anxious behaviors in females with AN are related to this heightened sensitivity.