Quantitative brain MRI morphology in severe and attenuated forms of mucopolysaccharidosis type I.

OBJECTIVE: To assess our hypothesis that brain macrostructure is different in individuals with mucopolysaccharidosis type I (MPS I) and healthy controls (HC), we conducted a comprehensive multicenter study using a uniform quantitative magnetic resonance imaging (qMRI) protocol, with analyses that account for the effects of disease phenotype, age, and cognition. METHODS: Brain MRIs in 23 individuals with attenuated (MPS IA) and 38 with severe MPS I (MPS IH), aged 4-25 years, enrolled under the study protocol NCT01870375, were compared to 98 healthy controls. RESULTS: Cortical and subcortical gray matter, white matter, corpus callosum, ventricular and choroid plexus volumes in MPS I significantly differed from HC. Thicker cortex, lower white matter and corpus callosum volumes were already present at the youngest MPS I participants aged 4-5 years. Age-related differences were observed in both MPS I groups, but most markedly in MPS IH, particularly in cortical gray matter metrics. IQ scores were inversely associated with ventricular volume in both MPS I groups and were positively associated with cortical thickness only in MPS IA. CONCLUSIONS: Quantitatively-derived MRI measures distinguished MPS I participants from HC as well as severe from attenuated forms. Age-related neurodevelopmental trajectories in both MPS I forms differed from HC. The extent to which brain structure is altered by disease, potentially spared by treatment, and how it relates to neurocognitive dysfunction needs further exploration.

Attention and corpus callosum volumes in individuals with mucopolysaccharidosis type I.

OBJECTIVE: Previous research suggests attention and white matter (WM) abnormalities in individuals with mucopolysaccharidosis type I (MPS I); this cross-sectional comparison is one of the first to examine the relationship of WM structural abnormalities as measured by corpus callosum (CC) volumes with attention scores to evaluate this relationship in a larger sample of patients with MPS I. METHODS: Volumetric MRI data and performance on a computerized measure of sustained attention were compared for 18 participants with the severe form of MPS I (MPS IH), 18 participants with the attenuated form of MPS I (MPS IATT), and 60 typically developing age-matched controls. RESULTS: The MPS I groups showed below-average mean attention scores (p < 0.001) and smaller CC volumes (p < 0.001) than controls. No significant associations were found between attention performance and CC volume for controls. Attention was associated with posterior CC volumes in the participants with MPS IH (p = 0.053) and total (p = 0.007) and anterior (p < 0.001) CC volumes in participants with MPS IATT. CONCLUSIONS: We found that attention and CC volumes were reduced in participants with MPS I compared to typically developing controls. Smaller CC volumes in participants with MPS I were associated with decreased attention; such an association was not seen in controls. While hematopoietic cell transplantation used to treat MPS IH may compound these effects, attention difficulties were also seen in the MPS IATT group, suggesting that disease effects contribute substantially to the clinical attentional difficulties seen in this population.

High Frequencies of Caspase-3 Expressing Mycobacterium tuberculosis-Specific CD4+ T Cells Are Associated With Active Tuberculosis.

Antigen-specific CD4+ T cell responses to Mycobacterium tuberculosis (Mtb) infection are important for host defense against tuberculosis (TB). However, Mtb-specific IFN-γ-producing T cells do not distinguish active tuberculosis (ATB) patients from individuals with asymptomatic latent Mtb infection (LTBI). We reasoned that the immune phenotype of Mtb-specific IFN-γ+CD4+ T cells could provide an indirect gauge of Mtb antigen load within individuals. We sought to identify immune markers in Mtb-specific IFN-γ+CD4+ T cells and hypothesized that expression of caspase-3 Mtb-specific CD4+ T cells would be associated with ATB. Using polychromatic flow cytometry, we evaluated the expression of caspase-3 in Mtb-specific CD4+ T cells from LTBI and ATB as well as from ATB patients undergoing anti-TB treatment. We found significantly higher frequencies of Mtb-specific caspase-3+IFN-γ+CD4+ T cells in ATB compared to LTBI. Caspase-3+IFN-γ+CD4+ T cells were also more activated compared to their caspase-3-negative counterparts. Furthermore, the frequencies of caspase-3+IFN-γ+CD4+ T cells decreased in response to anti-TB treatment. Our studies suggest that the frequencies of caspase-3-expressing antigen-specific CD4+ T cells may reflect mycobacterial burden in vivo and may be useful for distinguishing Mtb infection status along with other host biomarkers.

Neutrophil extracellular trap (NET) levels in human plasma are associated with active TB.

Neutrophils are increasingly associated with tuberculosis (TB) disease. Neutrophil extracellular traps (NETs), which are released by neutrophils as a host antimicrobial defense mechanism, are also associated with tissue damage. However, a link between NET levels and TB disease has not been studied. Here we investigate plasma NETs levels in patients with active pulmonary tuberculosis using an ELISA assay that is suitable for high-throughput processing. We show that plasma NETs levels at baseline correlated with disease severity and decreased with antibiotic therapy. Our study demonstrates the biologic plausibility of measuring NETs in plasma samples from patients with TB.

Neurocognition across the spectrum of mucopolysaccharidosis type I: Age, severity, and treatment.

OBJECTIVES: Precise characterization of cognitive outcomes and factors that contribute to cognitive variability will enable better understanding of disease progression and treatment effects in mucopolysaccharidosis type I (MPS I). We examined the effects on cognition of phenotype, genotype, age at evaluation and first treatment, and somatic disease burden. METHODS: Sixty patients with severe MPS IH (Hurler syndrome treated with hematopoietic cell transplant and 29 with attenuated MPS I treated with enzyme replacement therapy), were studied with IQ measures, medical history, genotypes. Sixty-seven patients had volumetric MRI. Subjects were grouped by age and phenotype and MRI and compared to 96 normal controls. RESULTS: Prior to hematopoietic cell transplant, MPS IH patients were all cognitively average, but post-transplant, 59% were below average, but stable. Genotype and age at HCT were associated with cognitive ability. In attenuated MPS I, 40% were below average with genotype and somatic disease burden predicting their cognitive ability. White matter volumes were associated with IQ for controls, but not for MPS I. Gray matter volumes were positively associated with IQ in controls and attenuated MPS I patients, but negatively associated in MPS IH. CONCLUSIONS: Cognitive impairment, a major difficulty for many MPS I patients, is associated with genotype, age at treatment and somatic disease burden. IQ association with white matter differed from controls. Many attenuated MPS patients have significant physical and/or cognitive problems and receive insufficient support services. Results provide direction for future clinical trials and better disease management.

Biomarkers on patient T cells diagnose active tuberculosis and monitor treatment response.

BACKGROUND: The identification and treatment of individuals with tuberculosis (TB) is a global public health priority. Accurate diagnosis of pulmonary active TB (ATB) disease remains challenging and relies on extensive medical evaluation and detection of Mycobacterium tuberculosis (Mtb) in the patient's sputum. Further, the response to treatment is monitored by sputum culture conversion, which takes several weeks for results. Here, we sought to identify blood-based host biomarkers associated with ATB and hypothesized that immune activation markers on Mtb-specific CD4+ T cells would be associated with Mtb load in vivo and could thus provide a gauge of Mtb infection. METHODS: Using polychromatic flow cytometry, we evaluated the expression of immune activation markers on Mtb-specific CD4+ T cells from individuals with asymptomatic latent Mtb infection (LTBI) and ATB as well as from ATB patients undergoing anti-TB treatment. RESULTS: Frequencies of Mtb-specific IFN-γ+CD4+ T cells that expressed immune activation markers CD38 and HLA-DR as well as intracellular proliferation marker Ki-67 were substantially higher in subjects with ATB compared with those with LTBI. These markers accurately classified ATB and LTBI status, with cutoff values of 18%, 60%, and 5% for CD38+IFN-γ+, HLA-DR+IFN-γ+, and Ki-67+IFN-γ+, respectively, with 100% specificity and greater than 96% sensitivity. These markers also distinguished individuals with untreated ATB from those who had successfully completed anti-TB treatment and correlated with decreasing mycobacterial loads during treatment. CONCLUSION: We have identified host blood-based biomarkers on Mtb-specific CD4+ T cells that discriminate between ATB and LTBI and provide a set of tools for monitoring treatment response and cure. TRIAL REGISTRATION: Registration is not required for observational studies. FUNDING: This study was funded by Emory University, the NIH, and the Yerkes National Primate Center.

Induction of human plasmablasts during infection with antibiotic-resistant nosocomial bacteria.

OBJECTIVES: Nosocomial pathogens such as Acinetobacter baumannii are a growing public health threat, due in part to their increasing resistance to antibiotics. Since some strains are resistant to all available antibiotics, novel therapies are urgently needed. Plasmablasts are short-lived B cells found in the blood that can be collected and harnessed to produce therapeutic antibodies. We set out to determine whether plasmablasts are induced during infection with A. baumannii and other nosocomial pathogens. METHODS: We obtained blood samples from patients infected with antibiotic-resistant nosocomial pathogens, and analysed their plasmablast response by flow cytometry. RESULTS: We observed a strong induction of plasmablasts in patients with antibiotic-resistant A. baumannii infection. Furthermore, plasmablasts were also induced in response to other drug-resistant nosocomial pathogens. CONCLUSIONS: These data suggest that plasmablasts may be broadly harnessed to develop therapeutic antibodies to combat otherwise untreatable antibiotic-resistant infections.

Neurocognitive and neuropsychiatric phenotypes associated with the mutation L238Q of the α-L-iduronidase gene in Hurler-Scheie syndrome.

UNLABELLED: The lysosomal enzyme α-L-iduronidase hydrolyzes terminal iduronic acid from heparan sulfate and dermatan sulfate, and is an essential step in GAG degradation. Mutations of its gene, IDUA, yield a spectrum of mucopolysaccharidosis (MPS) type I clinical disorders. The IDUA mutation, c.712T>A (p.L238Q) was previously noted as a mild mutation. In a longitudinal study of MPS brain structure and function (Lysosomal Disease Network), we found this mutation in 6 of 14 Hurler-Scheie syndrome patients in the age range of 15 to 25 years. We hypothesized that L238Q, when paired with a nonsense mutation, is significantly more severe than other missense-nonsense combinations. METHODS: Of 6 patients with a L238Q mutation, the L238Q allele was paired with a nonsense mutation in 4 patients, paired with a deletion in 1, and with a splice site mutation in another. This group was compared to 6 Hurler-Scheie patients closely matched in age and mutation type. IQ and other neuropsychological tests were administered as part of the protocol. Medical history was compiled into a Physical Symptom Score (PSS). Assessment of IQ, attention, memory, spatial ability, adaptive function and psychological status were measured. RESULTS: No group differences were found in mean age at evaluation (17.8 and 19.0 years), duration of ERT, or PSS. By history, all were reported to be average in IQ (4/6 with documentation) in early childhood. All (100%) of the L238Q group had a psychiatric history and sleep problems compared to none (0%) of the comparison group. Significant differences were found in depression and withdrawal on parent report measures. IQ was lower in the L238Q group (mean IQ 74) than the comparison group (mean IQ 95; p<0.016). Attention, memory, and visual-spatial ability scores were also significantly lower. Three occurrences of shunted hydrocephalus, and 4 of cervical cord compression were found in the L238Q group; the comparison group had one occurrence of unshunted hydrocephalus and two of cord compression. DISCUSSION: The missense mutation L238Q, when paired with a nonsense mutation, is associated with significant, late-onset brain disease: psychiatric disorder, cognitive deficit, and general decline starting at a later age than in Hurler syndrome with a mutation-related rate of GAG accumulation and its pathologic sequelae. This particular genotype-phenotype may provide insight into the genesis of psychiatric illnesses more broadly. Consideration of methods for early, brain-targeted treatment in these patients might be considered.

Clinical use of colistin induces cross-resistance to host antimicrobials in Acinetobacter baumannii.

The alarming rise in antibiotic resistance has led to an increase in patient mortality and health care costs. This problem is compounded by the absence of new antibiotics close to regulatory approval. Acinetobacter baumannii is a human pathogen that causes infections primarily in patients in intensive care units (ICUs) and is highly antibiotic resistant. Colistin is one of the last-line antibiotics for treating A. baumannii infections; however, colistin-resistant strains are becoming increasingly common. This cationic antibiotic attacks negatively charged bacterial membranes in a manner similar to that seen with cationic antimicrobials of the innate immune system. We therefore set out to determine if the increasing use of colistin, and emergence of colistin-resistant strains, is concomitant with the generation of cross-resistance to host cationic antimicrobials. We found that there is indeed a positive correlation between resistance to colistin and resistance to the host antimicrobials LL-37 and lysozyme among clinical isolates. Importantly, isolates obtained before and after treatment of individual patients demonstrated that colistin use correlated with increased resistance to cationic host antimicrobials. These data reveal the overlooked risk of inducing cross-resistance to host antimicrobials when treating patients with colistin as a last-line antibiotic. IMPORTANCE Increased use of the cationic antibiotic colistin to treat multidrug-resistant Acinetobacter baumannii has led to the development of colistin-resistant strains. Here we report that treatment of patients with colistin can induce not only increased resistance to colistin but also resistance to host cationic antimicrobials. This worrisome finding likely represents an example of a broader trend observed in other bacteria against which colistin is used therapeutically such as Pseudomonas aeruginosa and Klebsiella pneumoniae. Furthermore, these data suggest that the possible future use of an array of cationic antimicrobial peptides in development as therapeutics may have unintended negative consequences, eventually leading to the generation of hypervirulent strains that are resistant to innate host defenses. The potential for the induction of cross-resistance to innate immune antimicrobials should be considered during the development of new therapeutics.

Cocaine increases actin cycling: effects in the reinstatement model of drug seeking.

Addiction to cocaine is associated with persistent changes in synaptic function. The cycling of actin between polymerized [F (for filamentous)] and depolymerized forms contributes to synaptic plasticity, and acute and withdrawal from repeated cocaine administration produced reversible and enduring elevations, respectively, in F-actin in the nucleus accumbens. Increased F-actin after 3 weeks withdrawal from repeated cocaine resulted from changes in the content or phosphorylation state of actin binding proteins (ABPs) that cosediment with F-actin. The profile of altered APBs was consistent with filopodia formation, including increased mammalian Enabled, phosphorylated (p)-cortactin, and p-vasodilator-stimulated phosphoprotein, and increased actin depolymerization [e.g., reduced LIM (Lin11/Isl-1/Mec3)-kinase and p-cofilin]. In contrast to repeated cocaine, the increase in F-actin after acute cocaine administration resulted from reduced depolymerization and actin cycling. The potential involvement of chronic cocaine-induced increases in actin cycling in cocaine addiction was examined using the reinstatement of cocaine seeking in rats previously trained to self-administer cocaine by inhibiting actin polymerization with intra-accumbens latrunculin A or by accelerating actin depolymerization with a LIM-kinase inhibitor. Disrupting actin cycling via either mechanism augmented cocaine-induced reinstatement of drug seeking but did not affect the locomotor response to acute cocaine administration. Thus, withdrawal from repeated cocaine induces a restructuring of actin-ABP complexes, which increases actin cycling and may modulate cocaine-induced reinstatement of drug seeking.

Homer2 is necessary for EtOH-induced neuroplasticity.

Homer proteins are integral to the assembly of proteins regulating glutamate signaling and synaptic plasticity. Constitutive Homer2 gene deletion [knock-out (KO)] and rescue with adeno-associated viral (AAV) transfection of Homer2b was used to demonstrate the importance of Homer proteins in neuroplasticity produced by repeated ethanol (EtOH) administration. Homer2 KO mice avoided drinking high concentrations of EtOH and did not develop place preference or locomotor sensitization after repeated EtOH administration. The deficient behavioral plasticity to EtOH after Homer2 deletion was paralleled by a lack of augmentation in the rise in extracellular dopamine and glutamate elicited by repeated EtOH injections. The genotypic differences in EtOH-induced change in behavior and neurochemistry were essentially reversed by AAV-mediated transfection of Homer2b into accumbens cells including, differences in EtOH preference, locomotor sensitization, and EtOH-induced elevations in extracellular glutamate and dopamine. These data demonstrate a necessary and active role for accumbens Homer2 expression in regulating EtOH-induced behavioral and cellular neuroplasticity.

Cocaine-induced reinstatement requires endogenous stimulation of mu-opioid receptors in the ventral pallidum.

The projection from the nucleus accumbens to the ventral pallidum regulates the reinstatement of cocaine seeking in rats extinguished from cocaine self-administration. This projection coexpresses GABA and enkephalin, posing a role for mu-opioid receptors in the ventral pallidum in mediating the reinstatement of cocaine seeking. Rats were extinguished from cocaine self-administration, and the reinstatement of active lever pressing by cocaine was blocked by intra-ventral pallidum administration of the mu receptor antagonist Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP) (0.03-3.0 microg). Conversely, stimulating mu receptors with morphine (1-30 microg) in the ventral pallidum reinstated cocaine seeking. The ability of intra-ventral pallidum morphine to reinstate lever pressing was blocked by co-microinjection of the mu antagonist CTAP and was augmented by systemic cocaine administration. The reinstatement of cocaine seeking was associated with reduced extracellular GABA in the ventral pallidum, and the reduction in GABA was also prevented by blocking mu receptors with CTAP (10 microm). Although immunoblotting revealed that neither the total tissue concentration nor the membrane insertion of mu receptors in the ventral pallidum was altered by withdrawal from cocaine, the capacity of morphine (0.01-10 microm) to reduce ventral pallidum levels of extracellular GABA was augmented in rats extinguished from cocaine self-administration. These data are consistent with the reinstatement of cocaine seeking being modulated in part by coreleased enkephalin and GABA from the accumbens-ventral pallidal projection, a modulation that may involve the inhibition of GABA release by presynaptic mu receptors.

Ethanol exposure decreases glutamate uptake in the nucleus accumbens.

BACKGROUND: An increased level of extracellular glutamate is a key neurochemical feature associated with ethanol exposure and withdrawal. METHODS: In the current study, extracellular levels of glutamate and glutamate transport in the nucleus accumbens were assayed 24 hr after repeated ethanol exposure (1 g/kg ip daily for 7 days) with use of in vivo no-net-flux microdialysis and in vitro [(3)H]glutamate uptake, respectively. RESULTS: Microdialysis revealed higher extracellular glutamate concentrations in the nucleus accumbens of rats that were given ethanol. The increase in basal extracellular glutamate levels was accounted for in part by a decrease in the in vivo probe recovery of glutamate. Moreover, an in vitro accumbens slice preparation measuring [(3)H]glutamate uptake revealed that Na(+)-dependent [(3)H]glutamate uptake was significantly reduced 24 hr after 7 days of repeated ethanol exposure. The ethanol-induced deficit in glutamate uptake was not associated with decreased total tissue levels of the transporters GLAST or GLT1. The in vivo and in vitro ethanol-induced changes in glutamate levels and uptake returned to control levels 14 days after discontinuing 7 days of repeated ethanol exposure. CONCLUSIONS: These results suggest that the previously reported increases in extracellular glutamate induced by ethanol exposure may be due in part to deficits in glutamate transport.