Brain, behavior, and immunity
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Brain Behav. Immun. · May 2010
Infiltration of Th1 and Th17 cells and activation of microglia in the CNS during the course of experimental autoimmune encephalomyelitis.
Experimental autoimmune encephalomyelitis (EAE) is a mouse model for multiple sclerosis, where disease is mediated by autoantigen-specific T cells. Although there is evidence linking CD4(+) T cells that secrete IL-17, termed Th17 cells, and IFN-gamma-secreting Th1 cells with the pathogenesis of EAE, the precise contribution of these T cell subtypes or their associated cytokines is still unclear. We have investigated the infiltration of CD4(+) T cells that secrete IFN-gamma, IL-17 or both cytokines into CNS during development of EAE and have examined the role of T cells in microglial activation. ⋯ Co-culture experiments, using mixed glia and MOG-specific T cells, revealed that T cells that secreted IFN-gamma and IL-17 were potent activators of pro-inflammatory cytokines but T cells that secrete IFN-gamma, but not IL-17, were less effective. In contrast both Th1 and Th1/Th17 cells enhanced MHC-class II and co-stimulatory molecule expression on microglia. Our findings suggest that T cells which secrete IL-17 or IL-17 and IFN-gamma infiltrate the CNS prior to the onset of clinical symptoms of EAE, where they may mediate CNS inflammation, in part, through microglial activation.
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Brain Behav. Immun. · Mar 2010
Self-reported experiences of everyday discrimination are associated with elevated C-reactive protein levels in older African-American adults.
Self-reported experiences of "everyday" discrimination have been linked to indices of cardiovascular disease and overall mortality and findings have been particularly pronounced for African-American populations. However, the biological mechanisms underlying these associations remain unclear. C-reactive protein (CRP), a marker of inflammation, is a known correlate of cardiovascular and other health outcomes and has also been linked to several psychosocial processes. ⋯ This association remained significant after additional adjustments for depressive symptoms (B=.10, p=.04), smoking, and chronic health conditions (heart disease, diabetes, hypertension) that might influence inflammation (B=.11, p=.02). However, results were attenuated when body mass index (BMI) was added to the model (B=.09, p=.07). In conclusion, self-reported experiences of everyday discrimination are associated with higher levels of CRP in older African-American adults, although this association is not completely independent of BMI.
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Brain Behav. Immun. · Mar 2010
Spinally applied ketamine or morphine attenuate peripheral inflammation and hyperalgesia in acute and chronic phases of experimental arthritis.
Inflammation causes sensitization of peripheral and central nociceptive neurons. Pharmacological modulation of the latter has successfully been used for clinical pain relief. In particular, inhibitors of the NMDA glutamate receptor such as ketamine and agonists at the mu-opioid receptor such as morphine are broadly used. ⋯ Morphine showed strong antinociceptive effects in the acute phase only, while the newly established effective dose for ketamine in a continuous application design reduced hyperalgesia in the acute and the chronic stage. In conclusion, both compounds exhibit anti-inflammatory effects during induction and maintenance of arthritis when applied intrathecally. These data thus propose a role of spinal NMDA- and opioid-receptors in the neuronal control of immune-mediated inflammation.
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Brain Behav. Immun. · Mar 2010
The effect of non-steroidal anti-inflammatory agents on behavioural changes and cytokine production following systemic inflammation: Implications for a role of COX-1.
Systemic inflammation gives rise to metabolic and behavioural changes, largely mediated by pro-inflammatory cytokines and prostaglandin production (PGE(2)) at the blood-brain barrier. Despite numerous studies, the exact biological pathways that give rise to these changes remains elusive. This study investigated the mechanisms underlying immune-to-brain communication following systemic inflammation using various anti-inflammatory agents. ⋯ Our results suggest that the acute LPS-induced changes in burrowing and open-field activity depend on COX-1. We further show that COX-1 is not responsible for the induction of brain IL-6, IL-1beta and TNF-alpha synthesis or LPS-induced hypothermia. Our results may have implications for novel therapeutic strategies to treat or prevent neurological diseases with an inflammatory component.
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Brain Behav. Immun. · Jan 2010
Glial cell line-derived neurotrophic factor acutely modulates the excitability of rat small-diameter trigeminal ganglion neurons innervating facial skin.
Glial cell line-derived neurotrophic factor (GDNF) plays an important role in adult sensory neuron function. However, the acute effects of GDNF on primary sensory neuron excitability remain to be elucidated. The aim of the present study was to investigate whether GDNF acutely modulates the excitability of adult rat trigeminal ganglion (TRG) neurons that innervate the facial skin by using perforated-patch clamping, retrograde-labeling and immunohistochemistry techniques. ⋯ GDNF application also increased the duration of the repolarization phase and decreased the duration of the depolarization phase of the action potential, and these characteristic effects were also abolished by co-application of K252b. These results suggest that acute application of GDNF enhances the neuronal excitability of adult rat small-diameter TRG neurons innervating the facial skin, via activation of GDNF-induced intracellular signaling pathway. We therefore conclude that a local release of GDNF from TRG neuronal soma and/or nerve terminals may regulate normal sensory function, including nociception.