Faculty Bibliography

Vanishing white matter (VWM) disease is an autosomal genetic leukodystrophy caused by mutations in subunits of eukaryotic translation initiation factor 2B (eIF2B). The clinical symptoms exhibit progressive loss of white matter in both hemispheres of the brain, accompanied by motor functions deterioration, neurological deficits, and early death. To date there is no treatment for VWM disease. The aim of this work was to expedite rational development of a therapeutic opportunity. Our approach was to design a computer-aided strategy for an efficient and reliable screening of drug-like molecules; and to use primary cultures of fibroblasts isolated from the Eif2b5^R132H/R132H VWM mouse model for screening. The abnormal mitochondria content phenotype of the mutant cells was chosen as a read-out for a simple cell-based fluorescent assay to assess the effect of the tested compounds. We obtained a hit rate of 0.04% (20 hits out of 50,000 compounds from the selected library). All primary hits decreased mitochondria content and brought it closer to WT levels. Structural similarities between our primary hits and other compounds with known targets allowed the identification of three putative cellular pathways/targets: 11β-hydroxysteroid dehydrogenase type 1, Sonic hedgehog (Shh), and Sigma-1-Receptor (S1R). In addition to initial experimental indication of Shh pathway impairment in VWM mouse brains, the current study provides evidence that S1R is a relevant target for pharmaceutical intervention for potential treatment of the disease. Specifically, we found lower expression level of S1R protein in fibroblasts, astrocytes, and whole brains isolated from Eif2b5^R132H/R132H compared to WT mice, and confirmed that one of the hits is a direct binder of S1R, acting as agonist. Furthermore, we provide evidence that treatment of mutant mouse fibroblasts and astrocytes with various S1R agonists corrects the functional impairments of their mitochondria and prevents their need to increase their mitochondria content for compensation purposes. Moreover, S1R activation enhances the survival rate of mutant cells under ER stress conditions, bringing it to WT levels. This study marks S1R as a target for drug development toward treatment of VWM disease. Moreover, it further establishes the important connection between white matter well-being and S1R-mediated proper mitochondria/ER function.

Background: Behavioral methods enhance the effectiveness of lifestyle interventions, but are often resource intensive. Although mobile health (mHealth) technology can help create lower input interventions, their feasibility, acceptability and efficacy have not been adequately evaluated in hemodialysis (HD) patients.
Method(s): Maintenance HD patients with persistent hyperphosphatemia (n=40) were randomized to receive: (1) educational (Edu) videos (EDU), (2) Edu + mobile selfmonitoring (SM) with MyNetDiary (MON), or (3) Edu + SM + social cognitive theory (SCT)-based behavioral counseling videos (SCT) over a 12-week period with videos for each group delivered using iPads. Serum phosphorus concentrations (sPO4) were measured at baseline, 12 and 24 weeks, and a 5-point Likert scale survey on the mHealth technology was completed at 24-weeks. Two participants in the EDU group with no follow-up sPO4 measurements were excluded; missing sPO4 measurements at 12-and 24-weeks were imputed by carrying forward the most recent sPO4 values.
Result(s): At the end of the intervention phase (12-weeks), there was a non-significant trend towards greater decreases in sPO4 in the MON (-0.5+/-1.6 mg/dL, p=0.32) and SCT (-0.3+/-2.1 mg/dL, p=0.56) groups compared to the EDU group (+0.2+/-1.4 mg/dL), but these differences had mostly disappeared by the end of the monitoring phase (24-weeks) (EDU +0.1+/-1.2 mg/dL, MON -0.1+/-1.9 mg/dL, SCT -0.1+/-2.1 mg/dL). Most participants agreed or strongly agreed that the iPads were convenient (64%), and SM helped them stay motivated (68%), take binders (61%), and limit phosphorus intake (68%). Relatively few participants reported that they agreed or strongly agreed that they sometimes "got lost" maneuvering the iPad programs (24%), felt that SM wasn't worthwhile (16%), or would have preferred face-to-face meetings offsite (4%).
Conclusion(s): Many HD patients are willing, able and report benefits of engaging in technology-supported behavioral interventions involving SM and SCT. Although these programs are easy to disseminate with limited resources once developed, any benefits for phosphorus management in HD patients may last only as long as the intervention is active

A developing brain shows intense reorganization and heightened neuronal plasticity allowing for environmental modulation of its development. During early life, maternal care is a key factor of this environment and defects in this care can derail adaptive brain development and may result in susceptibility to neuropsychiatric disorders. Nevertheless, the mechanisms by which those maternal interactions immediately impact the offspring's brain activity to initiate the pathway to pathology are not well understood. We do know that multiple neurotransmitter systems are involved, including the serotonergic system, a key neuromodulator involved in brain development and emotional regulation. We tested the importance of the serotonergic system and pups' immediate neural response to maternal presence using wireless electrophysiological recordings, a novel approach allowing us to record neural activity during pups' interactions with their mother. We found that maternal contact modulates the P10-P12 rat pups' anterior cingulate cortex (ACC) activity by notably increasing local-field potential (LFP) power in low-frequency bands. We demonstrated, by blocking serotonergic receptors, that this increase is mediated through 5-HT2 receptors (5-HT2Rs). Finally, we showed in isolated pups that enhancing serotonergic transmission, using a selective-serotonin-reuptake-inhibitor, is sufficient to enhance LFP power in low-frequency bands in a pattern similar to that observed when the mother is in the nest. Our results highlight a significant contribution of the serotonergic system in mediating changes of cortical activity in pups related to maternal presence.

Serotonin (5-HT) is one of the best-studied modulatory neurotransmitters with ubiquitous presynaptic release and postsynaptic reception. 5-HT has been implicated in a wide variety of brain functions, ranging from autonomic regulation, sensory perception, feeding and motor function to emotional regulation and cognition. The role of this neuromodulator in neuropsychiatric diseases is unquestionable with important neuropsychiatric medications, e.g., most antidepressants, targeting this system. Importantly, 5-HT modulates neurodevelopment and changes in its levels during development can have life-long consequences. In this mini-review, we highlight that exposure to both low and high serotonin levels during the perinatal period can lead to behavioral deficits in adulthood. We focus on three exogenous factors that can change 5-HT levels during the critical perinatal period: dietary tryptophan depletion, exposure to serotonin-selective-reuptake-inhibitors (SSRIs) and poor early life care. We discuss the effects of each of these on behavioral deficits in adulthood.

Background: Cystinuria is an inherited kidney stone disorder caused by mutations to the SLC3A1 and SLC7A9 genes. While most cases are due to biallelic mutations to either gene, monoallelic and digenic families have been described, with overall considerable disease variability. Nevertheless, clear genotype/phenotype correlations have not been described to date.
Method(s): A next generation sequencing (NGS) panel consisting of 90 known and candidate kidney stone genes was developed and validated. A total of 49 unrelated, genetically unscreened individuals with a clinical diagnosis of cystinuria were analyzed using this panel. Preliminary correlations with phenotype were made with the genic groups.
Result(s): The baseline mean (SD) characteristics of the cohort were: age at diagnosis = 19.6y (12.5), number of stones = 5.8 (6.6), cystine excretion = 939.9mg (323.6), eGFR = 82.1ml/min/1.73m² (24.5), with age at last follow up = 43.8y (14). A total of 34 patients (69.4%) had biallelic SLC3A1 and 11 (22.4%) biallelic SLC7A9 mutations. One SLC3A1 and two SLC7A9 cases had a single detected mutation, and one case had no mutations detected. Large rearrangements, detected by LOG2 ratio analysis of the sequence data and confirmed by Multiplex Ligation-dependent Probe Amplification (MLPA), accounted for 31.9% of all SLC3A1 mutations, mainly the common ex5-9 duplication. Other common mutations were the SLC3A1 missense change p.Met467Thr (21.7% alleles) and the nonsense mutation p.Arg270* (18.8%), while for SLC7A9 the missense mutation p.Gly105Arg accounted for 29.2% of pathogenic alleles. Ten novel mutations were identified for each gene. The only detected correlation with genotype was with baseline mean stone number, SLC3A1 = 7.1 (7.1), SLC7A9 = 2.0 (2.1; p=0.05) in this cohort.
Conclusion(s): This analysis shows the utility of a panel-based NGS approach in cystinuria populations and more broadly in patients with suspected monogenic stone disease. Other genetic and/or environmental factors likely also contribute to the observed phenotypic variability

Manganese-enhanced MRI (MRI) is a technique that allows for a noninvasive in vivo estimation of neuronal transport. It relies on the physicochemical properties of manganese, which is both a calcium analogue being transported along neurons by active transport, and a paramagnetic compound that can be detected on conventional T1-weighted images. Here, we report a multi-session MEMRI protocol that helps establish time-dependent curves relating to neuronal transport along the olfactory tract over several days. The characterization of these curves via unbiased fitting enables us to infer objectively a set of three parameters (the rate of manganese transport from the maximum slope, the peak intensity, and the time to peak intensity). These parameters, measured previously in wild type mice during normal aging, have served as a baseline to demonstrate their significant sensitivity to pathogenic processes associated with Tau pathology. Importantly, the evaluation of these three parameters and their use as indicators can be extended to monitor any normal and pathogenic processes where neuronal transport is altered. This approach can be applied to characterize and quantify the effect of any neurological disease conditions on neuronal transport in animal models, together with the efficacy of potential therapies.

Background: Cystic fibrosis (CF) may predispose patients to urinary stone disease (USD) via several proposed mechanisms including antibiotic exposure and intestinal malabsorption. Prevalence of USD in patients with CF was estimated at 2-6% in studies with mean age 16-27 years. These data are limited by small sample sizes and single-center settings. The CF Foundation Patient Registry (CFFPR) began collecting prevalence data on USD in 2006.
Method(s): We studied 29,396 patients in the CFFPR living in 2016 to calculate age-stratified prevalence of USD.USD was assessed by trained CF clinic staff at each encounter. For 15,531 patients age 18 or older we examined associations between age, BMI, demographics, CFTR mutation class, other clinical parameters, and prevalent USD using multivariate logistic regression.
Result(s): Overall prevalence of USD was 3.1% (95% CI 2.9-3.3%). Prevalence under age 18 years was 0.4% (0.3-0.5%), 18 to 24 years, 3.1% (2.7-3.6%), 25 to 34 years, 6.4% (5.8-7.1%), 35 to 44 years, 7.5% (6.5-8.5%), and 45 years and older, 6.7% (5.8-7.8%). Mean age of all patients was 21.3 years. We also calculated prevalence for age ranges 20-29, and 30-39 years to compare with published NHANES data for the general population. Stone prevalence was 4.8% and 7.1% in in CF patients within these two age cohorts, respectively, compared to 3.4 and 6.4% in NHANES. Multivariate adjusted odds ratios for stone prevalence were significant for female sex, OR 1.4 (95% CI 1.2-1.7), severe CFTR mutations, OR 1.8 (1.2-2.5), diabetes, OR 1.2 (1.0-1.5), hypertension, OR 1.4 (1.0-1.9), and chronic macrolide therapy, OR 1.3 (1.1-1.6). BMI was not associated with USD.
Conclusion(s): USD prevalence in CFFPR may be higher than in the general population and increased with age. Some risk factors for stone disease in the general population appear significant for adult patients with CF, including hypertension and diabetes. However, BMI did not show the same relationship. Several novel associations with USD in CF patients also were identified, including a greater prevalence in women. This study is limited by the method of USD assessment; it is possible patients with more severe CF had higher rates of reported asymptomatic stones incidentally diagnosed due to more frequent imaging. As life expectancy of people with CF increases, the prevalence of USD may also increase

The anterior cingulate cortex (ACC) is thought to be important for acute pain perception as well as the development of chronic pain after peripheral nerve injury. Nevertheless, how ACC neurons respond to sensory stimulation under chronic pain states is not well understood. Here, we used an in vivo two-photon imaging technique to monitor the activity of individual neurons in the ACC of awake, head restrained mice. Calcium imaging in the dorsal ACC revealed robust somatic activity in layer 5 (L5) pyramidal neurons in response to peripheral noxious stimuli, and the degree of evoked activity was correlated with the intensity of noxious stimulation. Furthermore, the activation of ACC neurons occurred bilaterally upon noxious stimulation to either contralateral or ipsilateral hind paws. Notably, with nerve injury-induced neuropathic pain in one limb, L5 pyramidal neurons in both sides of the ACC showed enhanced activity in the absence or presence of pain stimuli. These results reveal hyperactivity of L5 pyramidal neurons in the bilateral ACC during the development of neuropathic pain.

Cortical mechanisms that regulate acute or chronic pain remain poorly understood. The prefrontal cortex (PFC) exerts crucial control of sensory and affective behaviors. Recent studies show that activation of the projections from the PFC to the nucleus accumbens (NAc), an important pathway in the brain's reward circuitry, can produce inhibition of both sensory and affective components of pain. However, it is unclear whether this circuit is endogenously engaged in pain regulation. To answer this question, we disrupted this circuit using an optogenetic strategy. We expressed halorhodopsin in pyramidal neurons from the PFC, and then selectively inhibited the axonal projection from these neurons to neurons in the NAc core. Our results reveal that inhibition of the PFC or its projection to the NAc, heightens both sensory and affective symptoms of acute pain in naïve rats. Inhibition of this corticostriatal pathway also increased nociceptive sensitivity and the aversive response in a chronic neuropathic pain model. Finally, corticostriatal inhibition resulted in a similar aversive phenotype as chronic pain. These results strongly suggest that the projection from the PFC to the NAc plays an important role in endogenous pain regulation, and its impairment contributes to the pathology of chronic pain.