Role for mammalian chitinase 3-like protein 1 in traumatic brain injury.

Traumatic brain injury (TBI) is accompanied by inflammatory infiltrates and CNS tissue response. The astrocytosis associated with TBI has been proposed to have both beneficial and detrimental effects on surviving neural tissue. We recently observed prominent astrocytic expression of YKL-40/chitinase 3-like protein 1 (CHI3L1) associated with severity of brain injury. The physiological role of CHI3L1 in the CNS is unknown; however, its distribution at the perimeter of contusions and temporal course of expression suggested that in TBI it might be an important component of the astrocytic response to modulate CNS inflammation. To address this hypothesis, we used serially sectioned brains to quantitatively compare the neuropathological outcomes of TBI produced by controlled cortical impact in wild type (WT) and chi3l1 knockout (KO) mice where the murine YKL-40 homologue, breast regression protein 39 (BRP-39/CHI3l1), had been homozygously disrupted. At 21 days post-injury, chi3l1 KO mice displayed greater astrocytosis (increased GFAP staining) in the hemispheres ipsilateral and contralateral to impact compared with WT mice. Similarly, Iba1 expression as a measure of microglial/macrophage response was significantly increased in chi3l1 KO compared with WT in the hemisphere contralateral to impact. We conclude that astrocytic expression of CHI3L1 limits the extent of both astrocytic and microglial/macrophage facets of neuroinflammation and suggests a novel potential therapeutic target for modulating neuroinflammation.

Transcranial magnetic stimulation (TMS) for major depression: a multisite, naturalistic, observational study of quality of life outcome measures in clinical practice.

BACKGROUND: Transcranial magnetic stimulation (TMS) is an effective and safe therapy for major depressive disorder (MDD). This study assessed quality of life (QOL) and functional status outcomes for depressed patients after an acute course of TMS. METHODS: Forty-two, U.S.-based, clinical TMS practice sites treated 307 outpatients with a primary diagnosis of MDD and persistent symptoms despite prior adequate antidepressant pharmacotherapy. Treatment parameters were based on individual clinical considerations and followed the labeled procedures for use of the approved TMS device. Patient self-reported QOL outcomes included change in the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) and the EuroQol 5-Dimensions (EQ-5D) ratings from baseline to end of the acute treatment phase. RESULTS: Statistically significant improvement in functional status on a broad range of mental health and physical health domains was observed on the SF-36 following acute TMS treatment. Similarly, statistically significant improvement in patient-reported QOL was observed on all domains of the EQ-5D and on the General Health Perception and Health Index scores. Improvement on these measures was observed across the entire range of baseline depression symptom severity. CONCLUSION: These data confirm that TMS is effective in the acute treatment of MDD in routine clinical practice settings. This symptom benefit is accompanied by statistically and clinically meaningful improvements in patient-reported QOL and functional status outcomes.

In vivo CHI3L1 (YKL-40) expression in astrocytes in acute and chronic neurological diseases.

BACKGROUND: CHI3L1 (YKL-40) is up-regulated in a variety of inflammatory conditions and cancers. We have previously reported elevated CHI3L1 concentration in the cerebrospinal fluid (CSF) of human and non-human primates with lentiviral encephalitis and using immunohistochemistry showed that CHI3L1 was associated with astrocytes. METHODS: In the current study CHI3L1 transcription and expression were evaluated in a variety of acute and chronic human neurological diseases. RESULTS: ELISA revealed significant elevation of CHI3L1 in the CSF of multiple sclerosis (MS) patients as well as mild elevation with aging. In situ hybridization (ISH) showed CHI3L1 transcription mostly associated with reactive astrocytes, that was more pronounced in inflammatory conditions like lentiviral encephalitis and MS. Comparison of CHI3L1 expression in different stages of brain infarction showed that YKL40 was abundantly expressed in astrocytes during acute phases and diminished to low levels in chronic infarcts. CONCLUSIONS: Taken together, these findings demonstrate that CHI3L1 is induced in astrocytes in a variety of neurological diseases but that it is most abundantly associated with astrocytes in regions of inflammatory cells.

Systemic and brain macrophage infections in relation to the development of simian immunodeficiency virus encephalitis.

The brains of individuals with lentiviral-associated encephalitis contain an abundance of infected and activated macrophages. It has been hypothesized that encephalitis develops when increased numbers of infected monocytes traffic into the central nervous system (CNS) during the end stages of immunosuppression. The relationships between the infection of brain and systemic macrophages and circulating monocytes and the development of lentiviral encephalitis are unknown. We longitudinally examined the extent of monocyte/macrophage infection in blood and lymph nodes of pigtailed macaques that did or did not develop simian immunodeficiency virus encephalitis (SIVE). Compared to levels in macaques that did not develop SIVE, more ex vivo virus production was detected from monocyte-derived macrophages and nonadherent peripheral blood mononuclear cells (PBMCs) from macaques that did develop SIVE. Prior to death, there was an increase in the number of circulating PBMCs following a rise in cerebrospinal fluid viral load in macaques that did develop SIVE but not in nonencephalitic macaques. At necropsy, macaques with SIVE had more infected macrophages in peripheral organs, with the exception of lymph nodes. T cells and NK cells with cytotoxic potential were more abundant in brains with encephalitis; however, T-cell and NK-cell infiltration in SIVE and human immunodeficiency virus encephalitis was more modest than that observed in classical acute herpes simplex virus encephalitis. These findings support the hypothesis that inherent differences in host systemic and CNS monocyte/macrophage viral production are associated with the development of encephalitis.

Longitudinal in vivo positron emission tomography imaging of infected and activated brain macrophages in a macaque model of human immunodeficiency virus encephalitis correlates with central and peripheral markers of encephalitis and areas of synaptic degeneration.

Human immunodeficiency virus encephalitis is characterized by infiltration of the brain with infected and activated macrophages; however, it is not known why disease occurs after variable lengths of infection in 25% of immunosuppressed acquired immune deficiency syndrome patients. We determined in vivo correlates (in peripheral blood and the central nervous system) for the development and progression of lentiviral encephalitis by longitudinally following infected and activated macrophages in the brain using positron emission tomography (PET). Using human postmortem brain tissues from both lentivirus-infected encephalitic patients and cell culture systems, we showed that the PET ligand [(3)H](R)-PK11195 bound specifically to virus-infected and activated macrophages. We longitudinally imaged infected and activated brain macrophages in a cohort of macaques infected with simian immunodeficiency virus using [(11)C](R)-PK11195. [(11)C](R)-PK11195 retention in vivo in the brain correlated with viral burden in the brain and cerebrospinal fluid, and with regions of both presynaptic and postsynaptic damage. Finally, longitudinal changes in [(11)C](R)-PK11195 retention in the brain in vivo correlated with changes in circulating monocytes as well as in both natural killer and memory CD4(+) T cells in the periphery. Our results suggest that development and progression of simian immunodeficiency virus encephalitis in vivo correlates with changes in specific cell subtypes in the periphery. A combination of PET imaging and the assessment of these peripheral immune parameters may facilitate longitudinal assessment of lentiviral encephalitis in living patients as well as evaluation of therapeutic efficacies.

YKL-40, a marker of simian immunodeficiency virus encephalitis, modulates the biological activity of basic fibroblast growth factor.

Human immunodeficiency virus encephalitis causes dementia in acquired immune deficiency syndrome patients. Using proteomic analysis of postmortem cerebrospinal fluid (CSF) and brain tissue from the simian immunodeficiency virus primate model, we demonstrate here a specific increase in YKL-40 that was tightly associated with lentiviral encephalitis. Longitudinal analysis of CSF from simian immunodeficiency virus-infected pigtailed macaques showed an increase in YKL-40 concentration 2 to 8 weeks before death from encephalitis. This increase in YKL-40 correlated with an increase in CSF viral load; it may therefore represent a biomarker for the development of encephalitis. Analysis of banked human CSF from human immunodeficiency virus-infected patients also demonstrated a correlation between YKL-40 concentration and CSF viral load. In vitro studies demonstrated increased YKL-40 expression and secretion by macrophages and microglia but not by neurons or astrocytes. We found that YKL40 displaced extracellular matrix-bound basic fibroblast growth factor (bFGF) as well as inhibited the mitogenic activity of both fibroblast growth factor receptor 1-expressing BaF3 cells and bFGF-induced axonal branching in hippocampal cultures. Taken together, these findings demonstrate that during lentiviral encephalitis, YKL-40 may interfere with the biological activity of bFGF and potentially of other heparin-binding growth factors and chemokines that can affect neuronal function or survival.

Toxicity of redox cycling pesticides in primary mesencephalic cultures.

A loss of nigrostriatal dopaminergic neurons is the primary neurodegenerative feature of Parkinson's disease. Paraquat, a known redox cycling herbicide, has recently been shown to kill selectively nigrostriatal dopaminergic cells in the mouse model. The purpose of this study was to test the ability of paraquat and other redox cycling pesticides to damage dopaminergic neurons in primary mesencephalic cultures. Addition of paraquat, diquat, or benzyl viologen to mesencephalic cultures induced morphological changes (e.g., dystrophic neuronal processes) consistent with dopaminergic cell injury. The three pesticides also caused cell death as assessed by a reduction of the number of tyrosine hydroxylase-immunoreactive neurons and a dose-dependent decrease in [(3)H]dopamine uptake. Quite interestingly, diquat and benzyl viologen were significantly more toxic than paraquat, probably reflecting their more pronounced ability to trigger redox cycling reactions. The data support a role of redox cycling as a mechanism of dopaminergic cell degeneration and suggest that the property of redox cycling should be taken into consideration when evaluating putative environmental risk factors for Parkinson's disease.

Characterization of the neuroprotective activity of rasagiline in cerebellar granule cells.

Rasagiline (N-propargyl-1-R-aminoindan) is a new selective inhibitor of MAO-B which is in development for the treatment of Parkinson's disease. The aim of the present study was to evaluate the neuroprotective properties of rasagiline and characterize the mechanism by which it exerts its neuroprotective effect in cerebellar granule cells. Cerebellar granule cells were prepared from 7 to 8 days postnatal Sprague-Dawley rats and maintained in high K(+) (25 mM) medium. Rasagiline increased the survival of cerebellar granule cells treated with cytosine beta-D-arabinofuranoside (Ara-C), L-buthionine-(S,R)-sulfoximine (BSO) or glutamate (100 microM) but did not reduce cell death induced by transferring the cells to physiological K(+) concentration (5 mM) or by serum deprivation. Examination of different derivatives of rasagiline showed that the propargyl moiety is essential to the neuroprotective effect of these molecules, as the compound 1-R-aminoindan (a major metabolite of rasagiline) was devoid of neuroprotective effect in this model system and a rasagiline derivative with a double bond in place of the acetylenic propargyl triple bond was much less effective. The S(-)-enantiomer of rasagiline was also significantly less active than R(+)-rasagiline, as was 6-fluoro rasagiline. Addition of rasagiline (0.1-10 microM) to cerebellar granule cells grown in medium containing a physiological concentration of K(+) did not have an effect on neurite outgrowth as measured by synapsin expression level but increased the density of glial cell processes. The neuroprotective effects of rasagiline may include a direct action on the neurons through inhibition of neuronal death as well as an indirect effect mediated by the astrocytes.

Redox cycling of the herbicide paraquat in microglial cultures.

Mechanisms involved in paraquat neurotoxicity that selectively target nigrostriatal dopaminergic neurons remain relatively unknown. In this study, we tested the hypotheses that paraquat exposure leads to the production of reactive oxygen species (ROS) through a process of redox cycling and that microglia represent an important site for the initiation of redox cycling reactions. Addition of paraquat to N9 microglial cultures resulted in a dose- and time-dependent release of superoxide radicals. Other agents that share with paraquat the property of redox cycling, i.e., benzyl viologen and diquat, also induced a marked production of superoxide radicals by microglia. The ability of paraquat, benzyl viologen, and diquat to induce superoxide release was correlated to their one-electron reduction potentials and thus their tendency to redox cycle. Nitric oxide synthase and NADPH oxidase were identified as enzymatic sources of electrons that triggered paraquat redox cycling by microglia. Taken together, these data provide evidence in favor of a new mechanism by which microglia could play a role in oxidative injury during neurodegenerative processes. Microglial NOS and NADPH oxidase could promote the generation of ROS via the redox cycling of paraquat-like toxicants.

A multisite, naturalistic, observational study of transcranial magnetic stimulation for patients with pharmacoresistant major depressive disorder: durability of benefit over a 1-year follow-up period.

OBJECTIVE: Transcranial magnetic stimulation (TMS) is an effective and safe acute treatment for patients not benefiting from antidepressant pharmacotherapy. Few studies have examined its longer term durability. This study assessed the long-term effectiveness of TMS in naturalistic clinical practice settings following acute treatment. METHOD: Adult patients with a primary diagnosis of unipolar, nonpsychotic major depressive disorder (DSM-IV clinical criteria), who did not benefit from antidepressant medication, received TMS treatment in 42 clinical practices. Two hundred fifty-seven patients completed a course of acute TMS treatment and consented to follow-up over 52 weeks. Assessments were obtained at 3, 6, 9, and 12 months. The study was conducted between March 2010 and August 2012. RESULTS: Compared with pre-TMS baseline, there was a statistically significant reduction in mean total scores on the Clinical Global Impressions-Severity of Illness scale (primary outcome), 9-Item Patient Health Questionnaire, and Inventory of Depressive Symptoms-Self Report (IDS-SR) at the end of acute treatment (all P < .0001), which was sustained throughout follow-up (all P < .0001). The proportion of patients who achieved remission at the conclusion of acute treatment remained similar at conclusion of the long-term follow-up. Among 120 patients who met IDS-SR response or remission criteria at the end of acute treatment, 75 (62.5%) continued to meet response criteria throughout long-term follow-up. After the first month, when the majority of acute TMS tapering was completed, 93 patients (36.2%) received reintroduction of TMS. In this group, the mean (SD) number of TMS treatment days was 16.2 (21.1). CONCLUSIONS: TMS demonstrates a statistically and clinically meaningful durability of acute benefit over 12 months of follow-up. This was observed under a pragmatic regimen of continuation antidepressant medication and access to TMS retreatment for symptom recurrence. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01114477.

Exacerbation of experimental autoimmune encephalomyelitis in the absence of breast regression protein 39/chitinase 3-like 1.

We previously reported that YKL-40, the human analog of mouse breast regression protein 39 ([BRP-39] chitinase 3like 1), is elevated in the cerebrospinal fluid of patients with a variety of neuroinflammatory conditions, such as multiple sclerosis and traumatic brain injury. Expression of YKL-40 in the CNS was predominantly associated with reactive astrocytes in the vicinity of inflammatory lesions. Because previous studies have shown that reactive astrocytes play a critical role in limiting immune infiltration in the mouse model of experimental autoimmune encephalomyelitis, we explored the role of BRP-39 in regulatingneuroinflammation in experimental autoimmune encephalomyelitis. Using BRP-39--deficient (BRP-39(-/-)) mice, we demonstrate the importance of BRP-39 in modulating the severity of clinical experimentalautoimmune encephalomyelitis and CNS neuroinflammation. At disease onset, absence of BRP-39 had little effect on clinical disease orlymphocytic infiltrate, but by 14 days after immunization, differences in clinical scores were evident. By 28 days after immunization, BRP-39(-/-) mice showed more severe and persistent clinical disease than BRP-39(+/+) controls. Histopathological evaluation showed that BRP-39(-/-) mice had more marked lymphocytic and macrophage infiltrates and gliosis versus BRP-39(+/+) mice. These findings support the role of BRP-39 expression in limiting immune cell infiltration into the CNS and offer a new target to modulate neuroinflammation.

Astrocyte and macrophage regulation of YKL-40 expression and cellular response in neuroinflammation.

Numerous inflammatory conditions are associated with elevated YKL-40 expression by infiltrating macrophages. Thus, we were surprised to observe minimal macrophage and abundant astrocyte expression of YKL-40 in neuroinflammatory conditions. The aims of the current study were to better delineate this discrepancy, characterize the factors that regulate YKL-40 expression in macrophages and astrocytes and study whether YKL-40 expression correlates with cell morphology and/or activation state. In vitro, macrophages expressed high levels of YKL-40 that was induced by classical activation and inhibited by alternative activation. Cytokines released from macrophages induced YKL-40 transcription in astrocytes that was accompanied by morphological changes and altered astrocytic motility. Because coculturing of astrocytes and macrophages did not reverse this in vitro expression pattern, additional components of the in vivo central nervous system (CNS) milieu must be required to suppress macrophage and induce astrocyte expression of YKL-40.

YKL-40 expression in traumatic brain injury: an initial analysis.

YKL-40 (chitinase 3-like protein 1) is expressed in a broad spectrum of inflammatory conditions and cancers. We have previously reported that YKL-40 levels are elevated in the cerebrospinal fluid (CSF) of macaques and humans with lentiviral encephalitis, as well as multiple sclerosis (MS). The current study assessed temporal CSF YKL-40 levels in subjects with severe traumatic brain injury (TBI; Glasgow Coma Scale [GCS] score

Brain extracellular matrix in neurodegeneration.

The role of extracellular matrix (ECM) in neurological development, function and degeneration has evolved from a simplistic physical adhesion to a system of intricate cellular signaling. While most cells require ECM adhesion to survive, it is now clear that differentiated function is intimately dependent upon cellular interaction with the ECM. Therefore, it is not surprising that the ECM is increasingly found to be involved in the enigmatic process of neurodegeneration. Descriptive studies of human neurodegenerative disorders and experimental studies of animal models of neurodegeneration have begun to define potential mechanisms of ECM disruption that can lead to synaptic and neuronal loss.