The relationship between salivary C-reactive protein and cognitive function in children aged 11-14years: Does psychopathology have a moderating effect?

Elevated C-reactive protein (CRP), a non-specific biomarker of systemic bodily inflammation, has been associated with more pronounced cognitive impairments in adults with psychiatric disorders, particularly in the domains of memory and executive function. Whether this association is present in early life (i.e., the time at which the cognitive impairments that characterise these disorders become evident), and is specific to those with emerging psychiatric disorders, has yet to be investigated. To this end, we examined the association between salivary CRP and cognitive function in children aged 11-14years and explored the moderating effect of psychopathology. The study utilised data from an established longitudinal investigation of children recruited from the community (N=107) that had purposively over-sampled individuals experiencing psychopathology (determined using questionnaires). CRP was measured in saliva samples and participants completed assessments of cognition (memory and executive function) and psychopathology (internalising and externalising symptoms and psychotic-like experiences). Linear regression models indicated that higher salivary CRP was associated with poorer letter fluency (ß=-0.24, p=0.006) and scores on the inhibition (ß=-0.28, p=0.004) and inhibition/switching (ß=-0.36, p<0.001) subtests of the colour-word interference test, but not with performance on any of the memory tasks (working, visual, and verbal memory tasks). Results were largely unchanged after adjustment for psychopathology and no significant interactions between CRP and psychopathology were observed on any cognitive measure. Our findings provide preliminary evidence that elevated salivary CRP is associated with poorer cognitive function in early life, but that this association is not moderated by concurrent psychopathology. These findings have implications for early intervention strategies that attempt to ameliorate cognitive deficits associated with emerging psychiatric disorders. Further research is needed to determine whether salivary CRP levels can be used as a valid marker of peripheral inflammation among healthy adolescents.

Design and synthesis of irreversible inhibitors of foot-and-mouth disease virus 3C protease.

Foot-and-mouth disease virus (FMDV) causes a highly infectious and economically devastating disease of livestock. The FMDV genome is translated as a single polypeptide precursor that is cleaved into functional proteins predominantly by the highly conserved viral 3C protease, making this enzyme an attractive target for antiviral drugs. A peptide corresponding to an optimal substrate has been modified at the C-terminus, by the addition of a warhead, to produce irreversible inhibitors that react as Michael acceptors with the enzyme active site. Further investigation highlighted key structural determinants for inhibition, with a positively charged P2 being particularly important for potency.

Cortisol Levels in Childhood Associated With Emergence of Attenuated Psychotic Symptoms in Early Adulthood.

BACKGROUND: In individuals at clinical high-risk for psychosis, elevated cortisol levels predict subsequent onset of psychotic disorder. However, it is unclear whether cortisol alterations are evident at an earlier clinical stage and promote progression of psychosis expression. This study aimed to address this issue by investigating whether cortisol levels in childhood were associated with the emergence of attenuated psychotic symptoms in early adulthood. In exploratory analyses, we examined whether cortisol and psychosocial stress measures interacted in predicting attenuated psychotic symptoms. METHODS: A sample of children (N = 109) enriched for psychosis risk factors were recruited at age 9-12 years and assessed at age 11-14 years (T1) and 17-21 years (T2). Measures of psychopathology, psychosocial stressors, and salivary cortisol were obtained at T1. Attenuated psychotic symptoms were assessed at T2 using the Prodromal Questionnaire. RESULTS: Diurnal cortisol (ß = 0.915, 95% CI: 0.062-1.769) and daily stressors (ß = 0.379, 95% CI: 0.034-0.723) at T1 were independently associated with total Prodromal Questionnaire scores at T2 after accounting for demographic factors and T1 psychopathology. Exploratory analyses indicated a significant interaction between T1 diurnal cortisol and daily stressors (ß = 0.743, 95% CI: 0.081-1.405), with the highest predicted T2 total Prodromal Questionnaire scores occurring when both diurnal cortisol and daily stressors were increased. CONCLUSIONS: Our findings suggest that daily stressors and elevations in diurnal cortisol in late childhood/early adolescence increases risk for developing attenuated psychotic symptoms. These findings emphasize the importance of assessing environmental and biological risk factors for psychosis during neurodevelopmentally vulnerable time periods.

Cortisol awakening response is decreased in patients with first-episode psychosis and increased in healthy controls with a history of severe childhood abuse.

BACKGROUND: Childhood abuse is highly prevalent in psychosis patients, but whether/how it affects hypothalamic-pituitary-adrenal (HPA) axis at the onset of psychosis remains unclear. We aimed to investigate the effects of severity of childhood abuse on HPA axis activity, in first-episode psychosis (FEP) and healthy controls. METHODS: We recruited 169 FEP patients and 133 controls with different degrees of childhood physical and sexual abuse (i.e. no abuse exposure, non-severe abuse exposure, and severe abuse exposure). Saliva samples were collected to measure cortisol awakening response with respect to ground (CARg), increase (CARi) and diurnal (CDD) cortisol levels. Two-way ANOVA analyses were conducted to test the relationships between severity of childhood abuse and psychosis on cortisol levels in individuals with psychosis and healthy controls with and without childhood abuse history. RESULTS: A statistically significant interaction between childhood abuse and psychosis on CARg was found (F(2,262) = 4.60, p = 0.011, ω2 = 0.42). Overall, controls showed a U-shaped relationship between abuse exposure and CARg, while patients showed an inverted U-shaped relationship. CARg values were markedly different between patients and controls with either no abuse history or exposure to severe childhood abuse. No significant differences were found when looking at CARi and CDD. CONCLUSIONS: Our results show a divergent effect of severe childhood abuse on HPA axis activity in patients with first-episode psychosis and in controls. In the presence of exposure to severe childhood abuse, a blunted CARg and a less reactive HPA axis may represent one of the biological mechanisms involved in the development of psychosis.

Multiple measures of HPA axis function in ultra high risk and first-episode schizophrenia patients.

INTRODUCTION: Abnormalities within hypothalamus-pituitary-adrenal (HPA) axis might interact with other neurobiological systems to enhance the risk of psychosis. Most of the neurodevelopmental and HPA axis changes occur in adolescence; this is also the period when prodromal and psychotic symptoms occur for the first time. More knowledge about how various stress components interact can advance understanding of the link between psychosis and the HPA axis. METHOD: We examined 41 ultra high-risk (UHR) patients and 40 antipsychotic-naïve first-episode schizophrenia (FES) patients and compared them with 47 matched controls. The Perceived Stress Scale and the Recent Life Events Questionnaire were used to assess the stress levels. Day-time saliva samples were taken to measure cortisol. The pituitary gland volume was measured manually on the structural MRI using stereology. RESULTS: Only the UHR patients, had a higher cortisol increase just after awakening (p = 0.009) compared to healthy controls. In UHR patients, we found a negative correlation between cortisol increase after awakening and symptom severity (p = 0.008). Pituitary gland volume and diurnal cortisol were not significantly different among the three groups. There was no correlation between pituitary gland volume, perceived stress/recent life events and any of the cortisol measures or symptoms. CONCLUSION: Symptom severity during the very early phase of illness (UHR) seems to be associated with altered cortisol increase. Longitudinal studies in UHR patients would be useful to examine how stress levels affect the course of the illness.

Foot-and-mouth disease virus 3C protease: recent structural and functional insights into an antiviral target.

The 3C protease from foot-and-mouth disease virus (FMDV 3C(pro)) is critical for viral pathogenesis, having vital roles in both the processing of the polyprotein precursor and RNA replication. Although recent structural and functional studies have revealed new insights into the mechanism and function of the enzyme, key questions remain that must be addressed before the potential of FMDV 3C(pro) as an antiviral drug target can be realised.

Circadian and homeostatic modulation of functional connectivity and regional cerebral blood flow in humans under normal entrained conditions.

Diurnal rhythms have been observed in human behaviors as diverse as sleep, olfaction, and learning. Despite its potential impact, time of day is rarely considered when brain responses are studied by neuroimaging techniques. To address this issue, we explicitly examined the effects of circadian and homeostatic regulation on functional connectivity (FC) and regional cerebral blood flow (rCBF) in healthy human volunteers, using whole-brain resting-state functional magnetic resonance imaging (rs-fMRI) and arterial spin labeling (ASL). In common with many circadian studies, we collected salivary cortisol to represent the normal circadian activity and functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Intriguingly, the changes in FC and rCBF we observed indicated fundamental decreases in the functional integration of the default mode network (DMN) moving from morning to afternoon. Within the anterior cingulate cortex (ACC), our results indicate that morning cortisol levels are negatively correlated with rCBF. We hypothesize that the homeostatic mechanisms of the HPA axis has a role in modulating the functional integrity of the DMN (specifically, the ACC), and for the purposes of using fMRI as a tool to measure changes in disease processes or in response to treatment, we demonstrate that time of the day is important when interpreting resting-state data.

Cortisol awakening response and diurnal cortisol among children at elevated risk for schizophrenia: relationship to psychosocial stress and cognition.

Abnormal hypothalamic-pituitary-adrenal (HPA) axis function, as indexed by elevated diurnal cortisol levels and/or a blunted cortisol awakening response (CAR), has been observed among patients with first episode psychosis and associated with neurocognitive deficits in this population. However, the extent to which these features precede illness onset is unclear. The current study aimed to determine whether children who are at putatively elevated risk for psychosis because they present multiple antecedents of schizophrenia (ASz), and high-risk children with a family history of illness (FHx), are characterized by abnormal cortisol levels when compared with their typically developing (TD) peers. A further aim was to investigate the extent to which cortisol levels are associated with psychosocial stress and neurocognitive function. Thirty-three ASz children, 22 FHx children, and 40 TD children were identified at age 9-12 years using a novel community-based screening procedure or as relatives of individuals with schizophrenia. All participants were antipsychotic-naive and not currently seeking treatment for their symptoms. At age 11-14 years, participants provided salivary cortisol samples and completed psychosocial stress measures and tests of memory and executive function. Results indicated that FHx children, but not ASz children, were characterized by a blunted CAR relative to their TD peers (effect size=-0.73, p=0.01) that was not explained by psychosocial stress exposure or by distress relating to these experiences. Neither FHx nor ASz children were characterized by elevated diurnal cortisol. Among both FHx and ASz children, more pronounced HPA axis function abnormalities (i.e., higher diurnal cortisol levels and greater blunting of the CAR) were associated with poorer performance on tests of verbal memory and executive function. These findings support the notion that at least some HPA axis abnormalities described in psychosis precede illness onset, rather than being a subsequent epiphenomenon. We speculate that the blunted CAR may constitute an early (potentially genetically mediated) marker of psychosis vulnerability, whilst elevated diurnal cortisol levels may emerge only proximally to disease onset.

Hypothalamic-pituitary-adrenal axis and clinical symptoms in first-episode psychosis.

BACKGROUND: Abnormalities in hypothalamic-pituitary-adrenal (HPA) axis activity have been reported in patients with psychosis, but it is still unclear how these are related to the clinical symptomatology. Inconsistent findings have emerged from previous studies on the association between cortisol levels and clinical symptoms. Methodological and/or clinical factors, such as patients' diagnosis or illness phase, might partially account for these inconsistencies. The aim of this study was to investigate the association between HPA axis activity and clinical symptoms in first-episode psychosis, taking into account diagnosis and illness phase. METHOD: Saliva samples were collected in 55 subjects with first-episode psychosis to assess the Cortisol Awakening Response (CAR) and diurnal cortisol levels (AUC-DAY). Severity of symptoms was assessed with the Positive and Negative Syndrome Scale (PANSS). Scores for subscales and symptom dimensions were used as predictors in multivariate analyses in different diagnostic subgroups and in clinically remitted patients. In addition, a systematic review of the literature on this topic was conducted. RESULTS: In subjects with schizophrenia (n=36), the CAR was predicted by the severity of positive symptoms (beta=0.47, p=0.04); in subjects with depressive psychoses (n=8) the CAR was predicted by excitement (beta=0.58, p=0.005), disorganization (beta=0.39, p=0.007) and depressive symptoms (beta=0.32, p=0.005). In patients with bipolar psychoses (n=11) AUC-DAY was predicted negatively by disorganization (beta=-2.82, p=0.009) and positively by excitement (beta=2.06, p=0.009) and positive symptoms (beta=1.28, p=0.02). In the sample in clinical remission (n=9), the CAR was associated with the severity of positive symptoms (beta=1.34, p=0.009) and, negatively, with excitement (beta=-1.05, p=0.04). The systematic review (on a total of 28 papers, including n=1022 patients), found that in patients with psychosis cortisol levels have been associated with the severity of multiple symptom dimensions. CONCLUSIONS: HPA axis activity is associated with the severity of multiple types of symptoms in first-episode psychosis. Patients' diagnosis and clinical phase partially influence these associations.

Insights into cleavage specificity from the crystal structure of foot-and-mouth disease virus 3C protease complexed with a peptide substrate.

Picornavirus replication is critically dependent on the correct processing of a polyprotein precursor by 3C protease(s) (3C(pro)) at multiple specific sites with related but non-identical sequences. To investigate the structural basis of its cleavage specificity, we performed the first crystallographic structural analysis of non-covalent complexes of a picornavirus 3C(pro) with peptide substrates. The X-ray crystal structure of the foot-and-mouth disease virus 3C(pro), mutated to replace the catalytic Cys by Ala and bound to a peptide (APAKQ|LLNFD) corresponding to the P5-P5' region of the VP1-2A cleavage junction in the viral polyprotein, was determined up to 2.5 A resolution. Comparison with free enzyme reveals significant conformational changes in 3C(pro) on substrate binding that lead to the formation of an extended interface of contact primarily involving the P4-P2' positions of the peptide. Strikingly, the deep S1' specificity pocket needed to accommodate P1'-Leu only forms when the peptide binds. Substrate specificity was investigated using peptide cleavage assays to show the impact of amino acid substitutions within the P5-P4' region of synthetic substrates. The structure of the enzyme-peptide complex explains the marked substrate preferences for particular P4, P2 and P1 residue types, as well as the relative promiscuity at P3 and on the P' side of the scissile bond. Furthermore, crystallographic analysis of the complex with a modified VP1-2A peptide (APAKE|LLNFD) containing a Gln-to-Glu substitution reveals an identical mode of peptide binding and explains the ability of foot-and-mouth disease virus 3C(pro) to cleave sequences containing either P1-Gln or P1-Glu. Structure-based mutagenesis was used to probe interactions within the S1' specificity pocket and to provide direct evidence of the important contribution made by Asp84 of the Cys-His-Asp catalytic triad to proteolytic activity. Our results provide a new level of detail in our understanding of the structural basis of polyprotein cleavage by 3C(pro).