Glioma-Induced Alterations in Excitatory Neurons are Reversed by mTOR Inhibition

Gliomas are highly aggressive brain tumors characterized by poor prognosis and composed of diffusely infiltrating tumor cells that intermingle with non-neoplastic cells in the tumor microenvironment, including neurons. Neurons are increasingly appreciated as important reactive components of the glioma microenvironment, due to their role in causing hallmark glioma symptoms, such as cognitive deficits and seizures, as well as their potential ability to drive glioma progression. Separately, mTOR signaling has been shown to have pleiotropic effects in the brain tumor microenvironment, including regulation of neuronal hyperexcitability. However, the local cellular-level effects of mTOR inhibition on glioma-induced neuronal alterations are not well understood. Here we employed neuron-specific profiling of ribosome-bound mRNA via 'RiboTag,' morphometric analysis of dendritic spines, and in vivo calcium imaging, along with pharmacological mTOR inhibition to investigate the impact of glioma burden and mTOR inhibition on these neuronal alterations. The RiboTag analysis of tumor-associated excitatory neurons showed a downregulation of transcripts encoding excitatory and inhibitory postsynaptic proteins and dendritic spine development, and an upregulation of transcripts encoding cytoskeletal proteins involved in dendritic spine turnover. Light and electron microscopy of tumor-associated excitatory neurons demonstrated marked decreases in dendritic spine density. In vivo two-photon calcium imaging in tumor-associated excitatory neurons revealed progressive alterations in neuronal activity, both at the population and single-neuron level, throughout tumor growth. This in vivo calcium imaging also revealed altered stimulus-evoked somatic calcium events, with changes in event rate, size, and temporal alignment to stimulus, which was most pronounced in neurons with high-tumor burden. A single acute dose of AZD8055, a combined mTORC1/2 inhibitor, reversed the glioma-induced alterations on the excitatory neurons, including the alterations in ribosome-bound transcripts, dendritic spine density, and stimulus evoked responses seen by calcium imaging. These results point to mTOR-driven pathological plasticity in neurons at the infiltrative margin of glioma - manifested by alterations in ribosome-bound mRNA, dendritic spine density, and stimulus-evoked neuronal activity. Collectively, our work identifies the pathological changes that tumor-associated excitatory neurons experience as both hyperlocal and reversible under the influence of mTOR inhibition, providing a foundation for developing therapies targeting neuronal signaling in glioma.

Computer-aided learning for managing stress: A feasibility trial with clinical high risk adolescents and young adults

AIM

The peak onset of psychotic disorders occurs during adolescence and early adulthood, yet treatments for youth at clinical high risk (CHR) for psychosis are generally designed for adults. CHR youth, despite poor academic and social engagement, spend hours each day playing complicated videogames. The aim of this study was to test the feasibility of integrating biofeedback and cooperative videogame play within family therapy as a means of engaging and enhancing this population's resilience.

METHODS

We conducted a feasibility trial of an innovative 12-week family therapy for CHR ages 12-30 (clinicaltrials.gov NCT02531243). We report feasibility outcomes and preliminary effect sizes for pre-post changes and youth-parent differences.

RESULTS

Of 88 individuals referred to the centre who met age and CHR criteria, 11 (13%) youth-parent pairs met full criteria and engaged in treatment. Ten (91%) completed at least six sessions. Youth found CALMS initially credible, but parents tended to find it more credible and to be more satisfied over time. Surprisingly, parents reported a better game experience than youth. As a group, youth and parent participants reported experiencing reduced stress and perceiving each other as less critical by the end of treatment. Youth were rated as having significantly improved social, but not role or global functioning by the end of treatment.

CONCLUSIONS

Multiuser videogames may have a role to play in engaging youth at risk for psychosis in therapy and reducing stress and familial risk factors. A number of key developments are needed to enhance the appeal, effectiveness and practicality of this approach.

Psychosis screening practices in schools: A survey of school-based mental health providers

AIM

Many school districts in the United States employ mental health professionals to provide assessment, counselling and crisis interventions within the school setting; however, little is known about actual clinical practices of psychosis screening in schools. The aim of the present study is to examine attitudes and practices regarding psychosis screening among school mental health providers in metropolitan Boston, Massachusetts.

METHODS

School-based mental health clinicians (N = 100) completed an anonymous survey assessing familiarity, screening, and involvement with psychosis and psychosis risk prior to attending trainings on psychosis.

RESULTS

Providers reported screening for psychosis less often than other mental health problems and rated themselves as less confident treating psychosis relative to other mental health concerns. Frequency of screening for psychosis was significantly associated with familiarity with psychosis assessment and case management, confidence providing treatment for individuals experiencing psychosis, and the number of students with or at risk for psychosis with whom providers had been involved. Frequency of screening for psychosis was not associated with years of practice, suggesting that both novice and experienced school-based providers may benefit from training on this issue.

CONCLUSIONS

Community outreach via school-based provider training on assessment and management of psychosis may help to increase providers' understanding of psychosis and increase the practice of verbal or written screening for psychosis and psychosis risk within schools.