Recruitment of beneficial M2 macrophages to injured spinal cord is orchestrated by remote brain choroid plexus

Monocyte-derived macrophages are essential for recovery after spinal cord injury, but their homing mechanism is poorly understood. Here, we show that although of common origin, the homing of proinflammatory (M1) and the "alternatively activated" anti-inflammatory (M2) macrophages to traumatized spinal cord (SC) was distinctly regulated, neither being through breached blood-brain barrier. The M1 macrophages (Ly6c(hi)CX3CR1(lo)) derived from monocytes homed in a CCL2 chemokine-dependent manner through the adjacent SC leptomeninges. The resolving M2 macrophages (Ly6c(lo)CX3CR1(hi)) derived from monocytes trafficked through a remote blood-cerebrospinal-fluid (CSF) barrier, the brain-ventricular choroid plexus (CP), via VCAM-1-VLA-4 adhesion molecules and epithelial CD73 enzyme for extravasation and epithelial transmigration. Blockage of these determinants, or mechanical CSF flow obstruction, inhibited M2 macrophage recruitment and impaired motor-function recovery. The CP, along with the CSF and the central canal, provided an anti-inflammatory supporting milieu, potentially priming the trafficking monocytes. Overall, our finding demonstrates that the route of monocyte entry to central nervous system provides an instructional environment to shape their function.

p53 coordinates cranial neural crest cell growth and epithelial-mesenchymal transition/delamination processes

Neural crest development involves epithelial-mesenchymal transition (EMT), during which epithelial cells are converted into individual migratory cells. Notably, the same signaling pathways regulate EMT function during both development and tumor metastasis. p53 plays multiple roles in the prevention of tumor development; however, its precise roles during embryogenesis are less clear. We have investigated the role of p53 in early cranial neural crest (CNC) development in chick and mouse embryos. In the mouse, p53 knockout embryos displayed broad craniofacial defects in skeletal, neuronal and muscle tissues. In the chick, p53 is expressed in CNC progenitors and its expression decreases with their delamination from the neural tube. Stabilization of p53 protein using a pharmacological inhibitor of its negative regulator, MDM2, resulted in reduced SNAIL2 (SLUG) and ETS1 expression, fewer migrating CNC cells and in craniofacial defects. By contrast, electroporation of a dominant-negative p53 construct increased PAX7(+) SOX9(+) CNC progenitors and EMT/delamination of CNC from the neural tube, although the migration of these cells to the periphery was impaired. Investigating the underlying molecular mechanisms revealed that p53 coordinates CNC cell growth and EMT/delamination processes by affecting cell cycle gene expression and proliferation at discrete developmental stages; disruption of these processes can lead to craniofacial defects.

Hemispheric asymmetries for global and local visual perception: effects of stimulus and task factors

Although neurotogical and physiological studies indicate a right hemisphere superiority in global processing and a left hemisphere superiority in local processing of Navon-type hierarchical letters (D. Navon, 1977), most investigations of lateralized perception in healthy participants report neither asymmetry. In 6 experiments the authors examined the influence of attentional demands, stimulus properties, and mode of response on perceptual asymmetries for global and local perception. Consistent with their theoretical predictions, asymmetries were more robust on divided- than focused-attention tasks and in response to stimuli in which local and global levels were equally salient compared with those with greater global than local saliency. Contrary to their prediction, perceptual asymmetries were not influenced by the complexity of the motor response.

The effects of sex, menstrual cycle, and oral contraceptives on the number and activity of natural killer cells

OBJECTIVES

The aim of this study was to study the impact of sex, the menstrual cycle, and the use of oral contraceptives (OC) on the number and activity of natural killer (NK) cells.

METHODS

Both the number and the activity of NK cells were assessed per milliliter of blood, and NK activity (NKA) per NK cell and per lymphocyte was calculated. NKA was measured in each subject using a whole blood assay, which preserves the plasma and all blood cells, and using a washed blood assay, in which plasma is replaced with an artificial medium. The subjects were young (20-29 years old) women with a regular menstrual cycle (n = 39; 26 tested on both the follicular and the luteal phases), age-matched women who use OC (n = 26), and age-matched men (n = 20).

RESULTS

Men showed markedly and significantly higher NKA than women with regular menstrual cycles or women using OC, who had the lowest levels of NKA. No significant differences in blood concentration of NK cell were found. Differences in NKA were of similar magnitude in the whole and washed blood assays per milliliter of blood, per NK cell, or per lymphocyte. The menstrual cycle had no significant effect on activity levels of NK cells, but during the periovulatory phase, the number of NK cells per milliliter of blood increased significantly.

CONCLUSIONS

The observed differences are independent of the presence of serum factors during the in vitro assessment of NKA, but may be related to chronic exposure to sex steroids and to fluctuation in the NK cell expression of beta-adrenoceptors.

Higher natural killer cell activity in schizophrenic patients: the impact of serum factors, medication, and smoking

Schizophrenia has been associated with altered immunity and reduced occurrence of autoimmune diseases and malignancies. A few studies in schizophrenic patients have assessed natural killer cell activity (NKA), but no consistent findings have emerged. However, NKA was assessed using standard procedures and in the absence of autologous serum and the various cytokines that modulate NKA and appear to be abnormal in schizophrenic patients. In the current study, therefore, the number of NK cells and the activity of the individual NK cell were assessed in whole blood shortly after blood withdrawal, in both the presence and the absence of autologous serum. Twenty-nine schizophrenic patients (11 nonmedicated), 8 nonschizophrenic control patients (bipolar and personality disorders), and 31 age-matched healthy controls were studied. Schizophrenic patients showed higher NKA per NK cell than controls and nonschizophrenic patients. This difference remained significant even when the nonmedicated schizophrenics, who showed the highest levels of NKA, were excluded. However, the increase in NKA was more pronounced in the presence of serum and was reduced to an insignificant level when serum was removed from the same samples. In both schizophrenic patients and controls, smokers and women showed lower NKA. Numbers of NK cells did not differ among groups, although medication affected blood concentration of other leukocytes. These findings indicate that the effects of serum factors, psychiatric medication, gender, and smoking should be considered when assessing NKA in schizophrenic patients. The observed higher NKA may help explain the surprising reports of low incidence of lung cancer and other malignancies in schizophrenic patients, despite their higher rate of smoking.

Dissociation between startle and prepulse inhibition in rats exposed to gamma radiation at day 15 of embryogeny

The role of prenatal trauma in disordered sensory gating was explored in albino rats of the Sprague-Dawley strain. Pregnant rats were exposed to 1.5 Gy (0.15 Gy/min) of the whole-body gamma radiation on days 15, 17, or 19 of gestation. Controls were sham-exposed during 10 min in the same conditions. Exposed and control offsprings were evaluated for the auditory startle response (ASR) and its gating by either the habituation process or by the preceding weak sensory stimulus in the prepulse inhibition of startle (PPI) procedure. The tests were conducted when the animals reached 27 and 57 days of age. A noticeable hyperresponding and delayed habituation of startle were found in rats exposed at E15, with meager effects in rats exposed at E17 and E19. Maximal deficit was obtained on tests conducted on P57 but not on P27. However, in rats pretreated with amphetamine, dysfunctional startle was unmasked already on the P27 test. By contrast, PPI was insensitive to the damaging effect of prenatal irradiation at either period. This dissociation is reminiscent of one observed in patients with posttraumatic stress disorder (PTSD).