Topical treatment targeting sphingosine-1-phosphate and sphingosine lyase abrogates experimental allergic rhinitis in a murine model.

BACKGROUND: Sphingosine-1-phosphate (S1P) plays a crucial role in homeostasis of the immune system by regulating lymphocyte recirculation and inflammatory cell recruitment. The levels of S1P are tightly controlled through regulated production and controlled breakdown by sphingosine-lyase (SL). The S1P analogue FTY720 has been developed as an immunosuppressant in transplantation and tested as a treatment for various inflammatory diseases. FTY720 exploits S1P biology by acting as a S1P1 and S1P 3 agonist and by inhibiting S1P breakdown by SL. OBJECTIVE: Here, we investigate interfering S1P in allergic rhinitis (AR) and its way of action. METHODS: Allergic rhinitis was induced by sensitizing mice to ovalbumin (OVA) and challenging the nose with OVA allergen. At the time of allergen challenge, mice received topical intranasal treatment with FTY720. To address the relative contribution of SL inhibition in mediating its effects, some mice were treated with the SL inhibitor 2-acetyl-4-tetrahydroxybutyl (THI). RESULTS: FTY720 treatment resulted in significantly fewer eosinophils, mast cells and dendritic cells in the nasal mucosa of AR animals, compared with diluent treatment. Levels of IL-4, IL-5, IL-10 and IL-13 produced by lymph node cells fell significantly in FTY720-treated animals. Moreover, FTY720 proved potent enough to suppress inflammation in a model of persistent AR. In vitro and in vivo experiments indicate that FTY720 impaired Th2 differentiation and proliferation important in driving eosinophilia and induced apoptosis in mast cells. CONCLUSION: Our results indicate that interfering with S1P metabolism is a powerful and feasible strategy to develop new topical agents that suppress AR.

United airways: circulating Th2 effector cells in an allergic rhinitis model are responsible for promoting lower airways inflammation.

BACKGROUND: Allergic rhinitis (AR) and asthma often coexist and are referred to as 'united airways' disease. However, the molecular and cellular pathways that are crucially involved in the interaction between upper and lower airways remain to be identified. OBJECTIVE: We sought to assess whether and how AR exacerbates lower airway inflammation upon allergen challenge in mice. METHODS: We previously developed an intranasal ovalbumin (OVA)-driven AR model, characterized by nasal eosinophilic inflammation, enhanced serum levels of OVA-specific IgE and Th2 cytokine production in cervical lymph nodes. In OVA-sensitized mice with or without AR, a lower airway challenge was given, and after 24 h, lower airway inflammation was analysed. RESULTS: We found that AR mice were more susceptible to eosinophilic inflammation following a lower airway OVA challenge than OVA-sensitized controls. AR mice manifested increased numbers of eosinophils in bronchoalveolar lavage fluid and increased inter-cellular adhesion molecule-1 (ICAM-1) expression on lung endothelium, when compared with OVA-sensitized controls. Depletion of T cells in OVA-challenged AR mice completely abrogated all hallmarks of lower airway inflammation, including enhanced IL-5 and tissue eosinophilia. Conversely, adoptive transfer of Th2 effector cells in naïve animals induced lower airway eosinophilic inflammation after challenge with OVA. Blocking T cell recirculation during AR development by the spingosine-1 analogue FTY720 also prevented lower airway inflammation including ICAM-1 expression in AR mice upon a single lower airway challenge. CONCLUSION: Our mouse model of 'united airways' disease supports epidemiological and clinical data that AR has a significant impact on lower airway inflammation. Circulating Th2 effector cells are responsible for lung priming in AR mice, most likely through up-regulation of ICAM-1.

Caspase-3-mediated cleavage of amyloid precursor protein and formation of amyloid Beta peptide in traumatic axonal injury.

Immunohistochemical studies demonstrate accumulation of the beta-amyloid precursor protein (APP) within injured axons following traumatic brain injury (TBI). Despite such descriptions, little is known about the ultimate fate of accumulating APP at sites of traumatic axonal injury (TAI). Recently, caspase-3-mediated cleavage of APP and subsequent Abeta deposition was linked to apoptotic neuronal death pathways in hippocampal neurons following ischemic and excitotoxic brain injury. Given that (1) APP is known to accumulate within traumatically injured axons, (2) caspase-3 activation has been demonstrated in traumatic axonal injury (TAI), and (3) recent studies have identified a caspase-3 cleavage site within APP, we initiated the current investigation to determine whether caspase-3-mediated cleavage of APP occurs in TAI. We further assessed whether these events were found in relation to Abeta peptide formation. To this end, we employed antibodies targeting APP, the caspase-3-mediated breakdown product of APP proteolysis, and the Abeta peptide. Rats were subjected to impact acceleration TBI (6 h to 10 days survival), and their brains were processed for single-label bright field and multiple double-label immunofluorescent paradigms using the above antibodies. By 12 h postinjury, caspase-3-mediated APP proteolysis (CMAP) was demonstrated within the medial lemniscus (ML) and medial longitudinal fasciculus (MLF) in axons undergoing TAI, identified by their concomitant APP accumulation. Immunoreactivity for CMAP persisted up to 48 h postinjury in the ML and MLF, but was notably reduced by 10 days following injury. Further, CMAP was colocalized with Abeta formation in foci of TAI. The current study demonstrates that caspase-3 cleavage of APP occurs in TAI and is associated with formation of Abeta peptide. These findings are of interest given recent epidemiological studies supporting an association between TBI and later risk for AD development.

Dose-response of cyclosporin A in attenuating traumatic axonal injury in rat.

Cyclosporin A has emerged as a promising therapeutic agent in traumatic brain injury (TBI), although its precise neuroprotective mechanism is unclear. Cyclosporin A, given as a single-dose intrathecal bolus, has previously been shown to attenuate mitochondrial damage and reduce axonal injury in experimental TBI. We assessed the effect of a range of intravenous cyclosporin A doses upon axonal injury attenuation to determine the ideal dose. Rats were subjected to experimental TBI and given one of five intravenous doses of cyclosporin A. At 3 h post-injury, brains were processed for brain tissue cyclosporin A concentration. In a second set of animals, at 24 h postinjury, brains were processed for amyloid precursor protein immunoreactivity, a widely used marker of axonal injury. Intravenous administration produced therapeutic levels of cyclosporin A in brain parenchyma. Higher concentrations were achieved with equivalent doses given intrathecally; this is consistent with the reported poor blood-brain barrier permeability of cyclosporin A. Cyclosporin A 10 mg/kg i.v. produced the greatest degree of neuroprotection against diffuse axonal injury; cyclosporin A 50 mg/kg i.v. was toxic. Intravenous cyclosporin A administration achieves therapeutic levels in brain parenchyma and 10 mg/kg is the most effective dose in attenuating axonal damage after traumatic brain injury.

Inflammatory response after neurosurgery.

Investigation into the inflammatory response in the central nervous system (CNS) is a rapidly growing field, and a vast amount of information on this topic has accumulated over the past two decades. Inflammation is a particularly interesting issue in the (traditionally non-regenerating) CNS, owing to its dual role in worsening or improving regeneration and functional outcome in certain circumstances. This paper reviews the current literature on the interactions between the immune system and the CNS in physiological and pathological states. The first part will provide an overview of the cellular and molecular components of CNS inflammation, this being followed by a discussion of the concept of systemic immunodepression after neurotrauma and neurosurgery. Finally, the delicate balance of immune responses in the CNS, with an emphasis on the beneficial effects of inflammation and possible therapeutic options, will be discussed.

Effect of montelukast compared with inhaled fluticasone on airway inflammation.

BACKGROUND: Inhaled corticosteroids are currently regarded as the gold standard in anti-inflammatory therapy, however, leukotriene receptor antagonists have been ascribed anti-inflammatory properties. OBJECTIVE: We directly compared the anti-inflammatory effects of inhaled fluticasone propionate (FP, 100 microg Diskus, twice daily) and oral montelukast (MON 10 mg, nocte) in bronchial biopsies of patients with asthma in a double-blind, double-dummy, parallel-group design. METHODS: Bronchial biopsies, serum and urine samples were collected from 36 atopic asthmatics before and after 8 weeks of treatment. Activated T cells (CD25+), eosinophils (MBP+) and mast cells (tryptase+) were analysed by immunohistochemistry. Serum eosinophil cationic protein (ECP) and IL-5 were analysed by radio and enzyme immunoassay (EIA), respectively. Urinary 9alpha-11beta-PGF2 and leukotriene E4 (LTE4) were measured by EIA. RESULTS: A comparison of changes from baseline [FP/MON ratio (95% confidence interval)] of activated T cells was not different when subjects were treated with FP compared to treatment with MON [1.00 (0.18-4.86); P=0.924]. Following treatment, mast cells in the FP group were significantly lower than in the group treated with MON [0.39 (0.16-0.97); P=0.041]. There was no difference in the number of eosinophils in the lamina propria following either treatment [0.54 (0.05-2.57); P=0.263]. However, treatment with FP resulted in a significantly greater decrease in serum ECP, compared to treatment with MON [0.37 (0.25-0.71); P=0.002]. CONCLUSIONS: FP appears to be superior to MON as an anti-inflammatory therapy in mild asthmatics.

Airway inflammation is present during clinical remission of atopic asthma.

Symptoms of atopic asthma often disappear at puberty. However, asthmatic subjects in clinical remission will frequently have a relapse later in life. The aim of this study was to investigate whether subjects in clinical remission of atopic asthma have persistent airway inflammation and/or airway remodeling. Bronchial biopsies were obtained from subjects in clinical remission, asthmatic subjects, and healthy control subjects. The presence and/or activation state of eosinophils, mast cells, macrophages, T lymphocytes, interleukin (IL)-5, eotaxin, and inducible nitric oxide synthase (iNOS) were analyzed. Results were compared with less invasive indicators of airway inflammation. Also aspects of airway remodeling were determined. Eosinophils, T cells, mast cells, and IL-5 were significantly elevated in the airway mucosa of subjects in remission compared with control subjects. Also, blood eosinophil cell counts were significantly higher in subjects in clinical remission. Blood eosinophil cell counts, exhaled nitric oxide (eNO) levels, and bronchial response to adenosine-5'-monophosphate correlated significantly with the quantity of tissue eosinophils. Significant airway remodeling was found in subjects in clinical remission. Our study has shown ongoing airway inflammation and airway remodeling in adolescents in clinical remission of atopic asthma. Subclinical airway inflammation may well determine the risk of an asthma relapse later in life.

Impaired axonal transport and altered axolemmal permeability occur in distinct populations of damaged axons following traumatic brain injury.

Traumatic axonal injury (TAI) evolves within minutes to hours following traumatic brain injury (TBI). Previous studies have identified axolemmal disruption and impaired axonal transport (AxT) as key mechanisms in the evolution of TAI. While initially hypothesized that axolemmal disruption culminates in impaired AxT, previous studies employed single-label methodologies that did not allow for a full determination of the spatial-temporal relationships of these two events. To explore directly the relationship between impaired AxT and altered axolemmal permeability, the current investigation employed 40, 10, and 3 kDa fluorescently conjugated dextrans as markers of axolemmal integrity, with antibodies targeting the anterogradely transported amyloid precursor protein (APP) utilized as a marker of impaired AxT. Rats underwent impact acceleration TBI and were intrathecally administered 40 kDa, 40 + 10 kDa or 40 + 3 kDa fluorescently tagged dextrans, with brains subsequently prepared for APP immunofluorescence. Brainstem corticospinal tracts (CSpT), medial lemnisci (ML), and medial longitudinal fasciculi were examined for evidence of TAI. APP and all dextrans consistently localized to distinct classes of TAI. Dextrans were noted as early as 5 min following injury within axonal segments demonstrating an irregular/tortuous appearance, and were seen within thin and elongate/vacuolated axons by 30 min-6 h following injury. APP, first noted within swollen axons at 30 min following injury, was found within progressively swollen axons that showed no dextran colocalization within 3 h of injury. However, by 6 h, dextrans colocalized in disconnected axonal bulbs. At this time-point, dextrans also persisted within single-labeled, highly vacuolated/thin, and elongate axons. These studies confirm that axolemmal disruption and impaired AxT occur as distinct non-related events early in the pathogenesis of TAI. Further, these studies provide evidence that the process of impaired axonal transport and subsequent axonal disconnection leads to delayed axolemmal instability, rather than proceeding as a consequence of initial axolemmal failure. This finding underscores the need of multiple approaches to fully assess the axonal response to TBI.