Acute neuroinflammation, sickness behavior and working memory responses to acute systemic LPS challenge following noradrenergic lesion in mice.

Locus coeruleus (LC)-derived noradrenaline is important in cognition and decreases with age, but the impact of prior noradrenaline deficiency on vulnerability to inflammation-induced acute cognitive dysfunction is unclear. Here we assessed whether noradrenergic depletion, in female mice, impacted upon inflammation, locomotor activity and working memory directly after acute systemic immune challenge with bacterial lipopolysaccharide (LPS), a paradigm we have previously used to capture delirium-like acute cognitive deficits. Mice received 2 doses of the LC-selective noradrenergic toxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4; 50 mg/kg i.p.) and were challenged, 2 weeks later, with LPS (100 µg/kg i.p.). DSP-4 dramatically reduced noradrenaline concentrations and tyrosine hydroxylase-positive afferents in the frontal cortex and hippocampus. This did not significantly alter numbers of Pu.1-positive microglia, Iba1-positive microglial morphology or mRNA expression of microglia-associated gene transcripts (Tyrobp, Sall1, Cd68, Sra2, Clec7a) in the hippocampus or frontal cortex and produced modest reductions in Cx3cr1 and P2ry12. LPS induced blood and brain cytokine levels, cFOS activation and locomotor responses that were highly similar in DSP-4- and vehicle-treated mice, although LPS-induced plasma TNF-α was significantly reduced in those treated with DSP-4. Importantly, prior noradrenergic depletion did not predispose to LPS-induced T-maze working memory deficits. The data demonstrate that significant depletion of noradrenaline in the hippocampus and frontal cortex does not prompt acutely exaggerated neuroinflammation or leave the brain vulnerable to acute, transient working memory deficits upon low dose LPS challenge. These findings have implications for our understanding of the impact of systemic inflammation on the aging and vulnerable brain during septic encephalopathy and delirium.

Fingolimod Rescues Demyelination in a Mouse Model of Krabbe's Disease.

Krabbe's disease is an infantile neurodegenerative disease, which is affected by mutations in the lysosomal enzyme galactocerebrosidase, leading to the accumulation of its metabolite psychosine. We have shown previously that the S1P receptor agonist fingolimod (FTY720) attenuates psychosine-induced glial cell death and demyelination both in vitro and ex vivo models. These data, together with a lack of therapies for Krabbe's disease, prompted the current preclinical study examining the effects of fingolimod in twitcher mice, a murine model of Krabbe's disease. Twitcher mice, both male and female, carrying a natural mutation in the galc gene were given fingolimod via drinking water (1 mg/kg/d). The direct impact of fingolimod administration was assessed via histochemical and biochemical analysis using markers of myelin, astrocytes, microglia, neurons, globoid cells, and immune cells. The effects of fingolimod on twitching behavior and life span were also demonstrated. Our results show that treatment of twitcher mice with fingolimod significantly rescued myelin levels compared with vehicle-treated animals and also regulated astrocyte and microglial reactivity. Furthermore, nonphosphorylated neurofilament levels were decreased, indicating neuroprotective and neurorestorative processes. These protective effects of fingolimod on twitcher mice brain pathology was reflected by an increased life span of fingolimod-treated twitcher mice. These in vivo findings corroborate initial in vitro studies and highlight the potential use of S1P receptors as drug targets for treatment of Krabbe's disease.SIGNIFICANCE STATEMENT This study demonstrates that the administration of the therapy known as fingolimod in a mouse model of Krabbe's disease (namely, the twitcher mouse model) significantly rescues myelin levels. Further, the drug fingolimod also regulates the reactivity of glial cells, astrocytes and microglia, in this mouse model. These protective effects of fingolimod result in an increased life span of twitcher mice.

Pharmacological targeting of ß2 -adrenoceptors is neuroprotective in the LPS inflammatory rat model of Parkinson's disease.

BACKGROUND AND PURPOSE: Chronic inflammation may play a role in the pathogenesis of Parkinson's disease (PD). Noradrenaline is an endogenous neurotransmitter with anti-inflammatory properties. In the present investigation, we assessed the immunomodulatory and neuroprotective efficacy of pharmacologically targeting the CNS noradrenergic system in a rat model of PD. EXPERIMENTAL APPROACH: The impact of treatment with the ß2 -adrenoceptor agonists clenbuterol and formoterol was assessed in the intranigral LPS rat model of PD. The immunomodulatory potential of formoterol to influence the CNS response to systemic inflammation was also assessed. KEY RESULTS: LPS-induced deficits in motor function (akinesia and forelimb-use asymmetry) and nigrostriatal dopamine loss were rescued by both agents. Treatment with the noradrenaline reuptake inhibitor atomoxetine reduced striatal dopamine loss and motor deficits following intranigral LPS injection. Co-treatment with the ß2 -adrenoceptor antagonist ICI 118,551 attenuated the protective effects of atomoxetine. Systemic LPS challenge exacerbated reactive microgliosis, IL-1ß production, dopamine cell loss in the substantia nigra, nerve terminal degeneration in the striatum, and associated motor impairments in animals that previously received intranigral LPS. This exacerbation was attenuated by formoterol treatment. CONCLUSION AND IMPLICATIONS: The results indicate that pharmacologically targeting ß2 -adrenoceptors has the propensity to regulate the neuroinflammatory phenotype in vivo and may be a potential neuroprotective strategy where inflammation contributes to the progression of dopaminergic neurodegeneration. In accordance with this, clinical agents such as ß2 -adrenoceptor agonists may prove useful as immunomodulatory agents in the treatment of neurodegenerative conditions associated with brain inflammation.

A decade of sustained geographic spread of HIV infections among women in Durban, South Africa.

BACKGROUND: Fine scale geospatial analysis of HIV infection patterns can be used to facilitate geographically targeted interventions. Our objective was to use the geospatial technology to map age and time standardized HIV incidence rates over a period of 10 years to identify communities at high risk of HIV in the greater Durban area. METHODS: HIV incidence rates from 7557 South African women enrolled in five community-based HIV prevention trials (2002-2012) were mapped using participant household global positioning system (GPS) coordinates. Age and period standardized HIV incidence rates were calculated for 43 recruitment clusters across greater Durban. Bayesian conditional autoregressive areal spatial regression (CAR) was used to identify significant patterns and clustering of new HIV infections in recruitment communities. RESULTS: The total person-time in the cohort was 9093.93 years and 613 seroconversions were observed. The overall crude HIV incidence rate across all communities was 6·74 per 100PY (95% CI: 6·22-7·30). 95% of the clusters had HIV incidence rates greater than 3 per 100PY. The CAR analysis identified six communities with significantly high HIV incidence. Estimated relative risks for these clusters ranged from 1.34 to 1.70. Consistent with these results, age standardized HIV incidence rates were also highest in these clusters and estimated to be 10 or more per 100 PY. Compared to women 35+ years old younger women were more likely to reside in the highest incidence areas (aOR: 1·51, 95% CI: 1·06-2·15; aOR: 1.59, 95% CI: 1·19-2·14 and aOR: 1·62, 95% CI: 1·2-2·18 for < 20, 20-24, 25-29 years old respectively). Partnership factors (2+ sex partners and being unmarried/not cohabiting) were also more common in the highest incidence clusters (aOR 1.48, 95% CI: 1.25-1.75 and aOR 1.54, 95% CI: 1.28-1.84 respectively). CONCLUSION: Fine geospatial analysis showed a continuous, unrelenting, hyper HIV epidemic in most of the greater Durban region with six communities characterised by particularly high levels of HIV incidence. The results motivate for comprehensive community-based HIV prevention approaches including expanded access to PrEP. In addition, a higher concentration of HIV related services is required in the highest risk communities to effectively reach the most vulnerable populations.

Geographical-level contributions of risk factors for HIV infections using generalized additive models: results from a cohort of South African women.

South Africa has the highest burden of human immunodeficiency virus (HIV) infections in the world with significant geographical variations. We identified the predictors of HIV infections and their sub-geographical-level contributions to the epidemic using a decade long data (2002-2012) from 6484 South African women. Generalized additive models were used to uncover the most significant features of these estimates across the region. In the overall analysis, younger age, not married or cohabiting with a partner, partner has another partner(s) and null/prim parity, using injectable contraceptives and presence of other sexually transmitted infections (STIs) were identified as independent predictors of HIV seroconversions. Overall, the top three highest contributors to infections were women's marital status (PAR% = 73%, 95% CI: 68%, 77%), parity (PAR% = 47%, 95% CI: 42%, 53%) and partnership factors (PAR% = 37%, 95% CI: 30%, 44%). However, their contributions varied remarkably at sub-geographical level. This was mainly due to the substantial localized variations in their prevalence and hazard ratios across the region. Our results will guide policy makers to develop tailored prevention strategies in order to allocate scarce resources by targeting the most significant contributors of HIV infection at sub-geographical level.

Treatment with the noradrenaline re-uptake inhibitor atomoxetine alone and in combination with the α2-adrenoceptor antagonist idazoxan attenuates loss of dopamine and associated motor deficits in the LPS inflammatory rat model of Parkinson's disease.

The impact of treatment with the noradrenaline (NA) re-uptake inhibitor atomoxetine and the α2-adrenoceptor (AR) antagonist idazoxan in an animal model of Parkinson's disease (PD) was assessed. Concurrent systemic treatment with atomoxetine and idazoxan, a combination which serves to enhance the extra-synaptic availability of NA, exerts anti-inflammatory and neuroprotective effects following delivery of an inflammatory stimulus, the bacterial endotoxin, lipopolysaccharide (LPS) into the substantia nigra. Lesion-induced deficits in motor function (akinesia, forelimb-use asymmetry) and striatal dopamine (DA) loss were rescued to varying degrees depending on the treatment. Treatment with atomoxetine following LPS-induced lesion to the substantia nigra, yielded a robust anti-inflammatory effect, suppressing microglial activation and expression of the pro-inflammatory cytokine TNF-α whilst increasing the expression of neurotrophic factors. Furthermore atomoxetine treatment prevented loss of tyrosine hydroxylase (TH) positive nigral dopaminergic neurons and resulted in functional improvements in motor behaviours. Atomoxetine alone was sufficient to achieve most of the observed effects. In combination with idazoxan, an additional improvement in the impairment of contralateral limb use 7 days post lesion and a reduction in amphetamine-mediated rotational asymmetry 14 days post-lesion was observed, compared to atomoxetine or idazoxan treatments alone. The results indicate that increases in central NA tone has the propensity to regulate the neuroinflammatory phenotype in vivo and may act as an endogenous neuroprotective mechanism where inflammation contributes to the progression of DA loss. In accordance with this, the clinical use of agents such as NA re-uptake inhibitors and α2-AR antagonists may prove useful in enhancing the endogenous neuroimmunomodulatory potential of NA in conditions associated with brain inflammation.

The ß2-adrenoceptor agonist clenbuterol reduces the neuroinflammatory response, neutrophil infiltration and apoptosis following intra-striatal IL-1ß administration to rats.

OBJECTIVES: Clenbuterol is a brain penetrant ß2-adrenoceptor agonist with anti-inflammatory and putative neuroprotective properties. In the present investigation, the effect of clenbuterol was assessed in a rat model of acute brain injury induced by intra-striatal administration of the pro-inflammatory cytokine IL-1ß. METHODS: Clenbuterol (0.5 mg/kg; i.p.) was administered one hour prior to stereotactically delivered IL-1ß (100 ng) into the striatum. Four hours postinjection, rats were anesthetized, blood samples were collected for circulating cytokine and chemokine analysis, and the ipsilateral striatum and liver tissue were harvested for mRNA expression analysis of target genes. RESULTS: Intrastriatal IL-1ß provoked an inflammatory response with increased expression of IL-1ß and the pro-inflammatory cytokine TNF-α. TNF-α expression was also increased in the liver and circulating concentrations of the chemokine cytokine-induced neutrophil chemoattractant 1 (CINC-1) were raised in response to intrastriatal IL-1ß administration. The striatal response was accompanied by NFκB activation and 24 hours postinjection, increased immunoreactivity of the neutrophil marker MBS-2, indicative of cell infiltration and increased TUNEL staining, a cell marker of apoptosis. Treatment with clenbuterol attenuated all IL-1ß-induced changes in the striatum including MBS-2 immunoreactivity and TUNEL + staining. Clenbuterol also attenuated IL-1ß-induced expression of TNF-α in the liver and the increase in circulating CINC-1 concentrations. CONCLUSIONS: The results provide evidence that clenbuterol elicits anti-inflammatory effects, suppresses the peripheral acute phase response and reduces the infiltration of neutrophils and apoptotic response to acute IL-1ß-induced brain injury. Suppression of both the central and peripheral response following clenbuterol administration may contribute to its protective properties following brain injury.

Stimulation of central ß2-adrenoceptors suppresses NFκB activity in rat brain: a role for IκB.

In this study we examined the impact of systemic treatment with the long-acting brain penetrant ß2-adrenoceptor agonist clenbuterol on NFκB activity and IκB expression in rat brain. Clenbuterol decreased NFκB activity (p65 DNA binding) in nuclear extracts prepared from rat cortex and hippocampus for up to 8h following a single treatment. This was accompanied by increased expression of IκBα mRNA and protein. The temporal increase in IκB protein expression paralleled the suppression of NFκB activity, suggesting that IκBα mediates the suppression NFκB activity observed. These actions of clenbuterol were prevented by pre-treatment with the non-selective ß-adrenoceptor antagonist propranolol, the ß2-adrenoceptor antagonist ICI-118,551, but not the ß1-adrenoceptor antagonist metoprolol, suggesting that the effects of clenbuterol on IκBα expression and NFκB activity are mediated specifically by the ß2-adrenoceptor. In addition, the actions of clenbuterol were mimicked by systemic administration of another highly selective long-acting ß2-adrenoceptor agonist formoterol. As neurodegenerative diseases are associated with inflammation we determined if clenbuterol could suppress NFκB activation that occurs in response to an inflammatory stimulus. In this regard we demonstrate that clenbuterol inhibited IκB phosphorylation and IκB degradation and inhibited NFκB activity in hippocampus and cortex of rats following a central injection of the inflammagen bacterial lipopolysaccharide (LPS). In tandem, clenbuterol blocked expression of the NFκB-inducible genes TNF-α and ICAM-1 following LPS administration. Our finding that clenbuterol and formoterol inhibit NFκB activity in the CNS further supports the idea that ß2-adrenoceptors may be an attractive target for treating neuroinflammation and combating inflammation-related neurodegeneration.