Rational downstream development for adeno-associated virus full/empty capsid separation - A streamlined methodology based on high-throughput screening and mechanistic modeling.

Recombinant adeno-associated virus (AAV) has emerged as one of the most promising systems for therapeutic gene delivery and has demonstrated clinical success in a wide range of genetic disorders. However, manufacturing of high-quality AAV in large amounts still remains a challenge. A significant difficulty for downstream processing is the need to remove empty capsids that are generated in all currently utilized expression systems and that represent product-related impurities that adversely affect safety and efficacy of AAV vectors. Empty and full capsids exhibit only subtle differences in surface charge and size, making chromatography-based separations highly challenging. Here, we present a rapid methodology for the systematic process development of the crucial AAV full/empty capsid separation on ion-exchange media based on high-throughput screening and mechanistic modeling. Two of the most commonly employed serotypes, AAV8 and AAV9, are used as case studies. First, high-throughput studies in filter-plate format are performed that allow the rapid and comprehensive study of binding and elution behavior of AAV on different resins, using different buffer systems, pH, salt conditions, and solution additives. Small amounts of separated empty and full AAV capsids are generated by iodixanol gradient centrifugation that allow studying the binding and elution behavior of the two vector species separately in miniaturized format. Process conditions that result in maximum differences in elution behavior between empty and full capsids are then transferred to benchtop chromatography systems that are used to generate calibration data for the estimation of steric mass-action isotherm and mass transport parameters for process simulation. The resulting column models are employed for in-silico process development that serves to enhance understanding of separation constraints and to identify optimized conditions for the removal of empty particles. Finally, optimized separation conditions are verified experimentally. The methodology presented in this work provides a systematic framework that affords mechanistic understanding of the crucial empty/full capsid separation and accelerates the development of a scalable AAV downstream process.

Demonstration of continuous gradient elution functionality with automated liquid handling systems for high-throughput purification process development.

Various high-throughput systems and strategies are employed by the biopharmaceutical industry for early to late-stage process development for biologics manufacturing. The associated increases to experiment productivity and reduction in material consumption makes high throughput tools integral for bioprocess development. While these high-throughput systems have been successfully leveraged to generate high quality data representative of manufacturing scale processes, their data interpretation often requires complex data transformation and time-intensive system characterization. With respect to high throughput purification development, RoboColumns by Repligen operated on Tecan automated liquid handling systems offer superior performance scalability, but lack an optimized liquid delivery system that is representative of preparative chromatography. Particularly, stock Tecan liquid handling systems lack the capability to provide high-capacity continuous liquid flow and ideal linear gradient chromatography conditions. These limitations impact protein chromatography performance and hinder the application of high-throughput gradient elution experiments. In this work, we describe a Tecan Freedom EVO high-throughput purification tool that provides more continuous liquid delivery enabling continuous gradient elution capability for RoboColumn experiments as demonstrated by generation of highly linear conductivity gradients. Results demonstrate that the tool can provide RoboColumn performance and product quality data that is in agreement with larger, bench scale chromatography formats for two model purification methods. The described gradient purification method also provides more consistent performance between RoboColumns and larger column formats compared to step elution methods using the same optimized Tecan system. Lastly, new insights into the impact of discontinuous flow on RoboColumn elution performance are introduced, which may help further improve application of these data towards bioprocess development.

Endogenous oxytocin levels are associated with facial emotion recognition accuracy but not gaze behavior in individuals with schizophrenia.

OBJECTIVE: Difficulties in social cognition are common in individuals with schizophrenia (SZ) and are not ameliorated by antipsychotic treatment. Intranasal oxytocin (OT) administration has been explored as a potential intervention to improve social cognition; however, results are inconsistent, suggesting potential individual difference variables that may influence treatment response. Less is known about the relationship between endogenous OT and social cognition in SZ, knowledge of which may improve the development of OT-focused therapies. We examined plasma OT in relationship to facial emotion recognition and visual attention to salient facial features in SZ and controls. METHODS: Forty-two individuals with SZ and 23 healthy controls viewed photographs of facial expressions of varying emotional intensity and identified the emotional expression displayed. Participants' gaze behavior during the task was recorded via eye tracking. Plasma oxytocin concentrations were determined by radioimmunoassay. RESULTS: SZ were less accurate than controls at identifying high-intensity fearful facial expressions and low-intensity sad expressions. Lower overall and high-intensity facial emotion recognition accuracy was associated with lower plasma OT levels in SZ but not controls. OT was not associated with visual attention to salient facial features; however, SZ had reduced visual attention to the nose region compared to controls. CONCLUSION: Individual differences in endogenous OT predict facial emotion recognition ability in SZ but are not associated with visual attention to salient facial features. Increased understanding of the association between endogenous OT and social cognitive abilities in SZ may help improve the design and interpretation of OT-focused clinical trials in SZ.

Understanding the effects of system differences for parameter estimation and scale-up of high throughput chromatographic data.

In this paper, we evaluate how employing fraction collection and multistep gradients with RoboColumns® (Repligen, formally Atoll) affects both comparison to benchtop experimental data and column simulation parameter estimation. These operational differences arise from the RoboColumn® system (operated on an automated liquid handling device) requiring offline analysis for determination of elution profiles rather than the continuous in-line UV curves obtained with larger scale systems. In addition, multistep gradients are used to model the smooth linear gradients of larger scale systems because sequential injections are used to provide liquid flow. Comparisons of two sets of column simulations was first carried out to demonstrate that fraction collection reduced the first moments of the elution peaks by 1/2 of the fraction volumes. Additional column simulations determined that the effect of a multistep gradient approximation on retention volume was dependent upon the gradient step length. An empirical transformation was then developed to correct the first moments obtained from gradient experimental data using the RoboColumn® system. These corrected values provided a more direct comparison of the experimental data at different scales and resulted in a significant improvement in agreement with results obtained using a 20 mL benchtop column. Linear steric mass-action (SMA) parameters were then estimated using the corrected values and employed to successfully predict the performance of the benchtop system data. Finally, these parameters were demonstrated to be well suited for modeling the RoboColumn® gradient data when properly accounting for multistep gradients and fraction collection. This work continues previous investigations into understanding system differences associated with robotic liquid handling devices and proposes a methodology for properly accounting for operational differences to predict operation at larger scales using conventional chromatography systems.

Using multimodal chromatography for post-conjugation antibody-drug conjugate purification: A methodology from high throughput screening to in-silico process development.

In this paper, a methodology for the development of a multimodal chromatography process is presented that is aimed at removal of under-conjugated antibody-drug conjugate (ADC) species. Two ADCs are used as case studies: One ADC results from site-directed conjugation to inserted cysteine residues and has a drug-to-antibody ratio (DAR) of two, the other is the product of conjugation to interchain disulfide bonds with a DAR of eight. First, filter plate screening studies are designed for the unconjugated antibody and the ADCs. Different metrics for the analysis of these data sets are presented and discussed. From this analysis, the selected process conditions are then carried out using a benchtop chromatography system to confirm the separations observed in the filter plate studies while simultaneously generating data to estimate steric mass-action isotherm and mass transport parameters for process simulation. This column model is then employed to develop separation processes in-silico for the removal of the unconjugated parent antibody and under-conjugated product variants. The optimized process conditions identified using the model are then verified experimentally. The methodology presented in this work utilizes multimodal chromatography for ADC purification and provides the framework for a streamlined systematic approach to process development.

Endogenous oxytocin levels are associated with impaired social cognition and neurocognition in schizophrenia.

Intranasal administration of the neuropeptide oxytocin (OT) has yielded inconsistent effects on social cognition and general cognition in individuals with schizophrenia (SZ). Few studies have examined whether endogenous peripheral OT levels are also associated with social and general cognition in SZ. The current study examined whether plasma OT levels are associated with performance on a higher-order social cognition measure (i.e., a task that requires inferential processes and knowledge not directly presented in social stimuli), as well as domains of general cognition. Participants included 30 individuals with SZ and 21 demographically matched healthy controls (CN). The MATRICS Consensus Cognitive Battery was administered to assess neuropsychological impairment in relation to 7 domains (processing speed, attention/vigilance, working memory, verbal learning, visual learning, reasoning/problem solving, and social cognition). Plasma OT levels were measured via radioimmunoassay. SZ had significantly lower endogenous OT levels and poorer MCCB performance on all 7 domains than CN. In CN and SZ, lower endogenous OT was associated with poorer social cognition. In SZ, lower endogenous OT was also associated with poorer processing speed and working memory. The significant association between OT and social cognition in both CN and SZ highlights the importance of endogenous OT levels as a biological predictor of social cognition, irrespective of clinical status. Significant associations between plasma OT and general neurocognition may reflect either an anxiolytic effect of plasma OT that results in better neurocognitive performance, or OT's action on dopamine and enhancement of dopamine tone that results in improved cognition.

Anhedonia reflects impairment in making relative value judgments between positive and neutral stimuli in schizophrenia.

Anhedonia (i.e., diminished capacity to experience pleasure) has traditionally been viewed as a core symptom of schizophrenia (SZ). However, modern laboratory-based studies suggest that this definition may be incorrect, as hedonic capacity may be intact. Alternative conceptualizations have proposed that anhedonia may reflect an impairment in generating mental representations of affective value that are needed to guide decision-making and initiate motivated behavior. The current study evaluated this hypothesis in 42 outpatients with SZ and 19 healthy controls (CN) who completed two tasks: (a) an emotional experience task that required them to indicate how positive, negative, and calm/excited they felt in response to a single emotional or neutral photograph; (b) a relative value judgment task where they selected which of 2 photographs they preferred. Results indicated that SZ and CN reported similar levels of positive emotion and arousal in response to emotional and neutral stimuli; however, SZ reported higher negative affect for neutral and pleasant stimuli than CN. In the relative value judgment task, CN displayed clear preference for stimuli differing in valence; however, SZ showed less distinct preferences for positive over neutral stimuli. Findings suggest that although in-the-moment experiences of positive emotion to singular stimuli may be intact in SZ, the ability to make relative value judgments that are needed to guide decision-making is impaired. Original conceptualizations of anhedonia as a diminished capacity for pleasure in SZ may be inaccurate; anhedonia may more accurately reflect a deficit in relative value judgment that results from impaired value representation.

Understanding operational system differences for transfer of miniaturized chromatography column data using simulations.

In this paper, a simulation tool was employed to identify and appropriately incorporate differences between MiniColumns and benchtop column systems. It was first demonstrated that including multi-step gradients and fraction collection into the simulations resulted in improved agreement between simulated and experimental linear gradient profiles as well as calculated first moments in the MiniColumn experiments. Step elution experiments of binary mixtures (a monoclonal antibody and one of three model proteins) were then carried out to examine comparability of the MiniColumns to the benchtop system. Although the peak shapes were qualitatively similar, peak elution began earlier in the MiniColumn system while improved separation was observed between overlapping peaks using the benchtop format. Simulations were then carried out to demonstrate that increased dispersion of the eluent breakthrough in the benchtop system could readily explain these observed differences. Importantly, by incorporating these system differences into the simulations, we were able to predict benchtop step elution performance using the parameters solely obtained from the MiniColumns. The findings presented in this paper illustrate that the appropriate consideration of system differences can facilitate the implementation of miniature chromatography columns as scale-down models for bioprocess development.

Hyperdeactivation of the Default Mode Network in People With Schizophrenia When Focusing Attention in Space.

When studying selective attention in people with schizophrenia (PSZ), a counterintuitive but replicated finding has been that PSZ display larger performance benefits than healthy control subjects (HCS) by cues that predicts the location of a target stimulus relative to non-predictive cues. Possible explanations are that PSZ hyperfocus attention in response to predictive cues, or that an inability to maintain a broad attentional window impairs performance when the cue is non-predictive. Over-recruitment of regions involved in top-down focusing of spatial attention in response to predictive cues would support the former possibility, and an inappropriate recruitment of these regions in response to non-predictive cues the latter. We probed regions of the dorsal attention network while PSZ (N = 20) and HCS (N = 20) performed a visuospatial attention task. A central cue either predicted at which of 4 peripheral locations a target signal would appear, or it gave no information about the target location. As observed previously, PSZ displayed a larger reaction time difference between predictive and non-predictive cue trials than HCS. Activity in frontoparietal and occipital regions was greater for predictive than non-predictive cues. This effect was almost identical between PSZ and HCS. There was no sign of over-recruitment when the cue was predictive, or of inappropriate recruitment when the cue was non-predictive. However, PSZ differed from HCS in their cue-dependent deactivation of the default mode network. Unexpectedly, PSZ displayed significantly greater deactivation than HCS in predictive cue trials, which may reflect a tendency to expend more processing resources when focusing attention in space.

Use of MiniColumns for linear isotherm parameter estimation and prediction of benchtop column performance.

In this paper, a comparison between experimental chromatography data and column simulations is carried out to determine the efficacy of using miniaturized chromatography columns (MiniColumns) for both column modeling parameter estimation and process development. Normalization of the data with respect to column volumes along with appropriate translations to account for system differences is shown to result in comparability of the experimental data for the MiniColumn and benchtop systems. A parameter estimation protocol is then employed to determine the linear steric mass-action (SMA) isotherm and lumped mass transport parameters for two cation exchange resins. The models are then validated and simulations using different parameter sets from the MiniColumn and benchtop systems are shown to result in similar predicted chromatography profiles and calculated retention volumes. The parameters generated from the MiniColumn system are demonstrated to be well suited for predicting experimental data from the benchtop system. These simulation results, the ability to operate MiniColumns in parallel, and the significantly lower material requirements per experiment support an industry trend toward increased usage of miniaturized chromatography columns as a scale-down model for process development.

Adjunctive Minocycline in Clozapine-Treated Schizophrenia Patients With Persistent Symptoms.

OBJECTIVE: Clozapine is the most effective antipsychotic for treatment refractory people with schizophrenia, yet many patients only partially respond. Accumulating preclinical and clinical data suggest benefits with minocycline. We tested adjunct minocycline to clozapine in a 10-week, double-blind, placebo-controlled trial. Primary outcomes tested were positive, and cognitive symptoms, while avolition, anxiety/depression, and negative symptoms were secondary outcomes. METHODS: Schizophrenia and schizoaffective participants (n = 52) with persistent positive symptoms were randomized to receive adjunct minocycline (100 mg oral capsule twice daily; n = 29) or placebo (n = 23). RESULTS: Brief Psychiatric Rating Scale (BPRS) psychosis factor (P = 0.098; effect size [ES], 0.39) and BPRS total score (P = 0.075; ES, 0.55) were not significant. A change in total BPRS symptoms of more than or equal to 30% was observed in 7 (25%) of 28 among minocycline and 1 (4%) of 23 among placebo participants, respectively (P = 0.044). Global cognitive function (MATRICS Consensus Cognitive Battery) did not differ, although there was a significant variation in size of treatment effects among cognitive domains (P = 0.03), with significant improvement in working memory favoring minocycline (P = 0.023; ES, 0.41). The Scale for the Assessment of Negative Symptoms total score did not differ, but significant improvement in avolition with minocycline was noted (P = 0.012; ES, 0.34). Significant improvement in the BPRS anxiety/depression factor was observed with minocycline (P = 0.028; ES, 0.49). Minocycline was well tolerated with significantly fewer headaches and constipation compared with placebo. CONCLUSIONS: Minocycline's effect on the MATRICS Consensus Cognitive Battery composite score and positive symptoms were not statistically significant. Significant improvements with minocycline were seen in working memory, avolition, and anxiety/depressive symptoms in a chronic population with persistent symptoms. Larger studies are needed to validate these findings.

Plasma oxytocin levels predict social cue recognition in individuals with schizophrenia.

Lower endogenous levels of the neuropeptide oxytocin may be an important biological predictor of social cognition impairments in schizophrenia (SZ). Prior studies have demonstrated that lower-level social cognitive processes (e.g., facial affect perception) are significantly associated with reduced plasma oxytocin levels in SZ; however, it is unclear whether higher-level social cognition, which requires inferential processes and knowledge not directly presented in the stimulus, is associated with endogenous oxytocin. The current study explored the association between endogenous oxytocin levels and lower- and higher-level social cognition in 40 individuals diagnosed with SZ and 22 demographically matched healthy controls (CN). All participants received the Social Cue Recognition Test (SCRT), which presents participants with videotaped interpersonal vignettes and subsequent true/false questions related to concrete or abstract aspects of social interactions in the vignettes. Results indicated that SZ had significantly higher plasma oxytocin concentrations than CN. SZ and CN did not differ on SCRT hits, but SZ had more false positives and lower sensitivity scores than CN. Higher plasma oxytocin levels were associated with better sensitivity scores for abstract items in CN and fewer false positives for concrete items in individuals with SZ. Findings indicate that endogenous oxytocin levels predict accurate encoding of lower-level socially relevant information in SZ.

Plasma oxytocin levels predict olfactory identification and negative symptoms in individuals with schizophrenia.

Basic neuroscience research provides strong evidence for the role of oxytocin in olfactory processes and social affiliation in rodents. Given prior indication of olfactory impairments that are linked to greater severity of asociality in schizophrenia, we examined the association between plasma oxytocin levels and measures of olfaction and social outcome in a sample of outpatients with schizophrenia (n=39) and demographically matched healthy controls (n=21). Participants completed the 40-item University of Pennsylvania Smell Identification Test (UPSIT), and rated each odor for how positive and how negative it made them feel. Results indicated that individuals with schizophrenia had higher plasma oxytocin levels and lower overall accuracy for UPSIT items than controls. Individuals with schizophrenia also reported experiencing more negative emotionality than controls in response to the olfactory stimuli. Lower plasma oxytocin levels were associated with poorer accuracy for pleasant and unpleasant odors and greater severity of asociality in individuals with schizophrenia. These findings suggest that endogenous oxytocin levels may be an important predictor of olfactory identification deficits and negative symptoms in schizophrenia.

Endogenous oxytocin levels are associated with the perception of emotion in dynamic body expressions in schizophrenia.

Lower endogenous oxytocin levels have been associated with impaired social cognition in schizophrenia, particularly facial affect identification. Little is known about the relationship between oxytocin and other forms of emotion perception. In the current study, 41 individuals with schizophrenia (SZ) and 22 demographically matched healthy controls (CN) completed a forced-choice affective body expression classification task. Stimuli included dynamic videos of male and female actors portraying 4 discrete emotions: happiness, sadness, anger, and neutral. Plasma oxytocin levels were determined via radioimmunoassay. Results indicated that SZ had significantly higher plasma oxytocin concentrations than CN. SZ were also less accurate at identifying expressions of happiness and sadness; however, there were no group differences for anger or neutral stimuli. A group×sex interaction was also present, such that female CN were more accurate than male CN, whereas male SZ were more accurate than female SZ. Higher endogenous oxytocin levels were associated with better total recognition in both SZ and CN; this association was specific to females in SZ. Findings indicate that sex plays an important role in identifying emotional expressions in body gestures in SZ, and that individual differences in endogenous oxytocin predict emotion perception accuracy.

Rasagiline in the Treatment of the Persistent Negative Symptoms of Schizophrenia.

OBJECTIVE: The current study examined the efficacy and safety of rasagiline, a selective MAO-B inhibitor, for the treatment of persistent negative symptoms. METHODS: Sixty people with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, schizophrenia or schizoaffective disorder, who met a priori criteria for persistent negative symptoms, were randomized to receive rasagiline, 1mg/d (n = 31) or placebo (n = 29) in a 12-week, double-blind, placebo-controlled clinical trial. The Scale for the Assessment of Negative Symptoms (SANS) total score was used to assess change in negative symptoms. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), N-Back test, a probabilistic learning task, and a delayed discounting task were used to assess cognition. RESULTS: In a mixed model analysis of covariance (MM-ANCOVA), with time as a continuous variable, there was a significant treatment × time effect for SANS total score (F = 5.61(df = 1,40.3), P = .023). The treatment × time interaction effect was also significant for the SANS avolition subscale score (F(1,40.2) = 10.41, P = .002). In a post hoc MM-ANCOVA analyses, with time as a categorical variable, group differences were significant at week 12 for SANS total score (t(37.3) = 2.15; P = .04; d = -0.41) and SANS avolition subscale score (t(49.0) = 3.06; P = .004; d = -0.46). There was a significant difference in number of participants with a ≥20% reduction in SANS avolition score (χ(2)(1) = 10.94; P = .0009), but not in SANS total score (χ(2)(1) = 1.11; P = .29). There were no significant group differences on the RBANS, N-Back, probabilistic learning, or delayed discounting tasks. CONCLUSIONS: Study results support future studies of the utility of rasagiline for the treatment of negative symptoms, including avolition (clinicaltrials.gov trial number: NCT00492336).

Community adherence to schizophrenia treatment and safety monitoring guidelines.

The 2003 Schizophrenia Patient Outcomes Research Team (PORT) treatment recommendations and the Mount Sinai Conference Safety Monitoring recommendations generated guidelines for pharmacological treatment of schizophrenia and monitoring of antipsychotic side effects. This study examined rate of recommendation adherence and impact of adherence on outcomes of outpatients with schizophrenia or schizoaffective disorder in community mental health centers. Clinical practice was assessed as conformant, nonconformant, or not applicable. Treatment practices were conformant for antipsychotic dose (83%); use of antiparkinsonian (97%), antidepressant (100%), and antianxiety agents (90%) but not clozapine for residual positive symptoms (31%); and monitoring weight gain (48%), glucose dysregulation (53%), hyperlipidemia (34%), or extrapyramidal symptoms (11%). Community mental health center treatment practices were largely conformant with the 2003 Schizophrenia PORT treatment recommendations. There is less evidence that patients who receive treatment in the community are adequately monitored for antipsychotic side effects per the Mount Sinai recommendations.

Treating symptomatic hyperprolactinemia in women with schizophrenia: presentation of the ongoing DAAMSEL clinical trial (Dopamine partial Agonist, Aripiprazole, for the Management of Symptomatic ELevated prolactin).

Prolactin elevations occur in people treated with antipsychotic medications and are often much higher in women than in men. Hyperprolactinemia is known to cause amenorrhea, oligomenorrhea, galactorrhea and gynecomastia in females and is also associated with sexual dysfunction and bone loss. These side effects increase risk of antipsychotic nonadherence and suicide and pose significant problems in the long term management of women with schizophrenia. In this manuscript, we review the literature on prolactin; its physiology, plasma levels, side effects and strategies for treatment. We also present the rationale and protocol for an ongoing clinical trial to treat symptomatic hyperprolactinemia in premenopausal women with schizophrenia. More attention and focus are needed to address these significant side effects and help the field better personalize the treatment of women with schizophrenia.

Deconstructing negative symptoms of schizophrenia: avolition-apathy and diminished expression clusters predict clinical presentation and functional outcome.

BACKGROUND: Previous studies indicate that negative symptoms reflect a separable domain of pathology from other symptoms of schizophrenia. However, it is currently unclear whether negative symptoms themselves are multi-faceted, and whether sub-groups of patients who display unique negative symptom profiles can be identified. METHODS: A data-driven approach was used to examine the heterogeneity of negative symptom presentations in two samples: Study 1 included 199 individuals with schizophrenia assessed with a standard measure of negative symptoms and Study 2 included 169 individuals meeting criteria for deficit schizophrenia (i.e., primary and enduring negative symptoms) assessed with a specialized measure of deficit symptoms. Cluster analysis was used to determine whether different groups of patients with distinct negative symptoms profiles could be identified. RESULTS: Across both studies, we found evidence for two distinctive negative symptom sub-groups: one group with predominantly Avolition-Apathy (AA) symptoms and another with a predominantly Diminished Expression (DE) profile. Follow-up discriminant function analyses confirmed the validity of these groups. AA and DE negative symptom sub-groups significantly differed on clinically relevant external validators, including measures of functional outcome, premorbid adjustment, clinical course, disorganized symptoms, social cognition, sex, and ethnicity. CONCLUSIONS: These results suggest that distinct subgroups of patients with elevated AA or DE can be identified within the broader diagnosis of schizophrenia and that these subgroups show clinically meaningful differences in presentation. Additionally, AA tends to be associated with poorer outcomes than DE, suggesting that it may be a more severe aspect of psychopathology.