Simvastatin Decreases Lipopolysaccharide-induced Pulmonary Inflammation in Healthy Volunteers

RATIONALE:
Simvastatin inhibits inflammatory responses in vitro and in murine models of lung inflammation in vivo. As simvastatin modulates a number of the underlying processes described in acute lung injury (ALI), it may be a potential therapeutic option.
OBJECTIVES:
To investigate in vivo if simvastatin modulates mechanisms important in the development of ALI in a model of acute lung inflammation induced by inhalation of lipopolysaccharide (LPS) in healthy human volunteers.
METHODS:
Thirty healthy subjects were enrolled in a double-blind, placebo-controlled study. Subjects were randomized to receive 40 mg or 80 mg of simvastatin or placebo (n = 10/group) for 4 days before inhalation of 50 microg LPS. Measurements were performed in bronchoalveolar lavage fluid (BALF) obtained at 6 hours and plasma obtained at 24 hours after LPS challenge. Nuclear translocation of nuclear factor-kappaB (NF-kappaB) was measured in monocyte-derived macrophages.
MEASUREMENTS AND MAIN RESULTS:
Pretreatment with simvastatin reduced LPS-induced BALF neutrophilia, myeloperoxidase, tumor necrosis factor-alpha, matrix metalloproteinases 7, 8, and 9, and C-reactive protein (CRP) as well as plasma CRP (all P < 0.05 vs. placebo). There was no significant difference between simvastatin 40 mg and 80 mg. BALF from subjects post-LPS inhalation induced a threefold up-regulation in nuclear NF-kappaB in monocyte-derived macrophages (P < 0.001); pretreatment with simvastatin reduced this by 35% (P < 0.001).
CONCLUSIONS:
Simvastatin has antiinflammatory effects in the pulmonary and systemic compartment in humans exposed to inhaled LPS.

Subcutaneous inflammation mimicking metastatic malignancy induced by injection of mistletoe extract

We describe the histological features of subcutaneous inflammation induced by mistletoe, a popular Christmas decoration, when used as an anticancer complementary therapy. We also outline the use of extract of mistletoe in this context.

Persistent Inflammation Subverts Thrombospondin-1–Induced Regulation of Retinal Angiogenesis and Is Driven by CCR2 Ligation

Neovascular retinal disease is a leading cause of blindness orchestrated by inflammatory responses. Although noninfectious uveoretinitis is mediated by CD4(+) T cells, in the persistent phase of disease, angiogenic responses are observed, along with degeneration of the retina. Full clinical manifestation relies on myeloid-derived cells, which are phenotypically distinct from, but potentially sharing common effector responses to age-related macular degeneration. To interrogate inflammation-mediated angiogenesis, we investigated experimental autoimmune uveoretinitis, an animal model for human uveitis. After the initial acute phase of severe inflammation, the retina sustains a persistent low-grade inflammation with tissue-infiltrating leukocytes for over 4 months. During this persistent phase, angiogenesis is observed as retinal neovascular membranes that arise from inflamed venules and postcapillary venules, increase in size as the disease progresses, and are associated with infiltrating arginase-1(+) macrophages. In the absence of thrombospondin-1, retinal neovascular membranes are markedly increased and are associated with arginase-1(-) CD68(+) macrophages, whereas deletion of the chemokine receptor CCR2 resulted in reduced retinal neovascular membranes in association with a predominant neutrophil infiltrate. CCR2 is important for macrophage recruitment to the retina in experimental autoimmune uveoretinitis and promotes chronicity in the form of a persistent angiogenesis response, which in turn is regulated by constitutive expression of angiogenic inhibitors like thrombospondin-1. This model offers a new platform to dissect the molecular and cellular pathology of inflammation-induced ocular angiogenesis.

Dynamics and Function of Langerhans Cells In Vivo: Dermal Dendritic Cells Colonize Lymph Node Areas Distinct from Slower Migrating Langerhans Cells

Langerhans cells (LCs) are prominent dendritic cells (DCs) in epithelia, but their role in immunity is poorly defined. To track and discriminate LCs from dermal DCs in vivo, we developed knockin mice expressing enhanced green fluorescent protein (EGFP) under the control of the langerin (CD207) gene. By using vital imaging, we showed that most EGFP(+) LCs were sessile under steady-state conditions, whereas skin inflammation induced LC motility and emigration to lymph nodes (LNs). After skin immunization, dermal DCs arrived in LNs first and colonized areas distinct from slower migrating LCs. LCs reaching LNs under steady-state or inflammatory conditions expressed similar levels of costimulatory molecules. Langerin and EGFP were also expressed on thymic DCs and on blood-derived, CD8alpha(+) DCs from all secondary lymphoid organs. By using a similar knockin strategy involving a diphtheria toxin receptor (DTR) fused to EGFP, we demonstrated that LCs were dispensable for triggering hapten-specific T cell effectors through skin immunization.

Hydrogen sulfide is a novel mediator of lipopolysaccharide-induced inflammation in the mouse

Hydrogen sulfide (H2S) is synthesized in the body from L-Cysteine by several enzymes including cystathionine-gamma-lyase (CSE). To date, there is little information about the potential role of H2S in inflammation. We have now investigated the part played by H2S in endotoxin-induced inflammation in the mouse. E. coli lipopolysaccharide (LPS) administration produced a dose (10 and 20 mg/kg ip)- and time (6 and 24 h)-dependent increase in plasma H2S concentration. LPS (10 mg/kg ip, 6 h) increased plasma H2S concentration from 34.1 +/- 0.7 mu M to 40.9 +/- 0.6 mu M (n=6, P

Paraquat-Induced Retinal Degeneration Is Exaggerated in CX3CR1-Deficient Mice and Is Associated with Increased Retinal Inflammation

PURPOSE:
To investigate the role of the Fractalkine receptor CX3CR1 pathway in oxidative insults-mediated retinal degeneration and immune activation.
METHODS:
A prooxidant, paraquat (0.75 µM) was injected into the vitreous of C57BL/6J, CX3CR1(gpf/+), and CX3CR1(gfp/gfp) mice. Retinal lesions were investigated clinically by topic endoscopic fundus imaging and fluorescence angiography, and pathologically by light- and electron microscopy. Retinal immune gene expression was determined by real-time RT-PCR. Microglial activation and immune cell infiltration were examined by confocal microscopy of retinal flatmounts.
RESULTS:
Intravitreal injection of paraquat (0.75 µM) resulted in acute retinal capillary nonperfusion within 2 days, which improved from 4 days to 4 weeks postinjection (p.i.). Panretinal degeneration was observed at 4 days p.i. and progressed further at 4 weeks p.i. In the absence of CX3CR1, retinal degeneration was exaggerated and was accompanied by increased TNF-a, iNOS, IL-1ß, Ccl2, and Casp-1 gene expression. Confocal microscopy of retinal flatmounts revealed microglial activation and CD44(+)MHC-II(+) monocyte and GR1(+) neutrophil infiltration in paraquat-injected eyes. The number of activated microglia and infiltrating leukocytes was significantly higher in CX3CR1(gfp/gfp) mice than in CX3CR1(gfp/+) mice.
CONCLUSIONS:
Our results suggest that the CX3CR1 signaling pathway may play an important role in controlling retinal inflammation under oxidative and ischemia/reperfusion conditions. In the absence of CX3CR1, uncontrolled retinal inflammation results in exaggerated retinal degeneration.

A selective antagonist of histamine H₄ receptors prevents antigen-induced airway inflammation and bronchoconstriction in guinea pigs:involvement of lipocortin-1

BACKGROUND AND PURPOSE: Among the pathogenic mechanisms of asthma, a role for oxidative/nitrosative stress has been well documented. Recent evidence suggests that histamine H₄ receptors play a modulatory role in allergic inflammation. Here we report the effects of compound JNJ 7777120 (JNJ), a selective H4 receptor antagonist, on antigen-induced airway inflammation, paying special attention to its effects on lipocortin-1 (LC-1/annexin-A1), a 37 kDA anti-inflammatory protein that plays a key role in the production of inflammatory mediators.

EXPERIMENTAL APPROACH: Ovalbumin (OA)-sensitized guinea pigs placed in a respiratory chamber were challenged with antigen. JNJ (5, 7.5 and 10 mg.kg⁻¹) was given i.p. for 4 days before antigen challenge. Respiratory parameters were recorded. Bronchoalveolar lavage (BAL) fluid was collected and lung specimens taken for further analyses 1 h after antigen challenge. In BAL fluid, levels of LC-1, PGD2 , LTB4 and TNF-α were measured. In lung tissue samples, myeloperoxidase, caspase-3 and Mn-superoxide dismutase activities and 8-hydroxy-2-deoxyguanosine levels were measured.

KEY RESULTS: OA challenge decreased LC-1 levels in BAL fluid, induced cough, dyspnoea and bronchoconstriction and increased PGD2 , LTB4 and TNF-α levels in lung tissue. Treatment with JNJ dose-dependently increased levels of LC-1, reduced respiratory abnormalities and lowered levels of PGD2 , LTB4 and TNF-α in BAL fluid.

CONCLUSIONS AND IMPLICATIONS: Antigen-induced asthma-like reactions in guinea pigs decreased levels of LC-1 and increased TNF-α and eicosanoid production. JNJ pretreatment reduced allergic asthmatic responses and airway inflammation, an effect associated with LC-1 up-regulation.

The E3 ubiquitin ligase Pellino3 protects against obesity-induced inflammation and insulin resistance

Diet-induced obesity can induce low-level inflammation and insulin resistance. Interleukin-1β (IL-1β) is one of the key proinflammatory cytokines that contributes to the generation of insulin resistance and diabetes, but the mechanisms that regulate obesity-driven inflammation are ill defined. Here we found reduced expression of the E3 ubiquitin ligase Pellino3 in human abdominal adipose tissue from obese subjects and in adipose tissue of mice fed a high-fat diet and showing signs of insulin resistance. Pellino3-deficient mice demonstrated exacerbated high-fat-diet-induced inflammation, IL-1β expression, and insulin resistance. Mechanistically, Pellino3 negatively regulated TNF receptor associated 6 (TRAF6)-mediated ubiquitination and stabilization of hypoxia-inducible factor 1α (HIF1α), resulting in reduced HIF1α-induced expression of IL-1β. Our studies identify a regulatory mechanism controlling diet-induced insulin resistance by highlighting a critical role for Pellino3 in regulating IL-1β expression with implications for diseases like type 2 diabetes.

TNF alpha-Induced p38MAPK Activation Regulates TRPA1 and TRPV4 Activity in Odontoblast-Like Cells

The transient receptor potential (TRP) channels are unique cellular sensors that are widely expressed in many neuronal and nonneuronal cells. Among the TRP family members, TRPA1 and TRPV4 are emerging as candidate mechanosensitive channels that play a pivotal role in inflammatory pain and mechanical hyperalgesia. Odontoblasts are nonneuronal cells that possess many of the features of mechanosensitive cells and mediate important defense and sensory functions. However, the effect of inflammation on the activity of the odontoblast's mechanosensitive channels remains unknown. By using immunohistochemistry and calcium microfluorimetry, we showed that odontoblast-like cells express TRPA1 and TRPV4 and that these channels were activated by hypotonicity-induced membrane stretch. Short treatment of odontoblast-like cells with tumor necrosis factor (TNF)-α enhanced TRPA1 and TRPV4 responses to their chemical agonists and membrane stretch. This enhanced channel activity was accompanied by phospho-p38 mitogen-activated protein kinase (MAPK) expression. Treatment of cells with the p38 inhibitor SB202190 reduced TNF-α effects, suggesting modulation of channel activity via p38 MAPK. In addition, TNF-α treatment also resulted in an up-regulation of TRPA1 expression but down-regulation of TRPV4. Unlike TRPV4, enhanced TRPA1 expression was also evident in dental pulp of carious compared with noncarious teeth. SB202190 treatment significantly reduced TNF-α-induced TRPA1 expression, suggesting a role for p38 MAPK signaling in modulating both the transcriptional and non-transcriptional regulation of TRP channels in odontoblasts.

Caries-induced changes in the expression of pulpal neuropeptide Y

Recent evidence suggests that the sympathetic nervous system may have a role in modulating neurogenic inflammation and bone remodelling. Neuropeptide Y (NPY) is a well-characterized neuropeptide transmitter in the peripheral sympathetic nervous system. NPY is known to be present in human dental pulp; however, quantitative data on NPY levels in pulpal health and disease in an adult population remain to be determined. The aims of the current study were to assess, quantitatively, NPY levels by radioimmunoassay and confirm the distribution of NPY fibres by immunocytochemistry in carious and non-carious adult human pulp tissue. Our results suggest changes in the levels and distribution of NPY in human dental pulp during the caries process, with significantly higher levels of NPY in carious compared with non-carious adult human teeth. Within the carious samples studied, our finding, that NPY levels were significantly elevated in mild/moderate caries, concurs with the hypothesis that NPY could have a modulatory role in pulpal inflammation and in reparative dentine formation. © 2006 Eur J Oral Sci.

Langerhans cells are critical in the development of atopic dermatitis-like inflammation and symptoms in mice

Genetic or vitamin D3-induced overexpression of thymic stromal lymphopoietin (TSLP) by keratinocytes results in an atopic dermatitis (AD)-like inflammatory phenotype in mice echoing the discovery of high TSLP expression in epidermis from AD patients. Although skin dendritic cells (DC) are suspected to be involved in AD, direct evidence of a pathogenetic role for skin DC in TSLP-induced skin inflammation has not yet been demonstrated. In a mouse model of AD, i.e. mice treated with the low-calcemic vitamin D3 analogue, MC903, we show that epidermal Langerhans cells (LC)-depleted mice treated with MC903 do neither develop AD-like inflammation nor increased serum IgE as compared to vitamin D3 analogue-treated control mice. Accordingly, we show that, in mice treated with MC903 or in K14-TSLP transgenic mice, expression of maturation markers by LC is increased whereas maturation of dermal DC is not altered. Moreover, only LC are responsible for the polarization of naive CD4+ T cells to a Th2 phenotype, i.e. decrease in interferon-gamma and increase in interleukin (IL)-13 production by CD4+ T cells. This effect of LC on T-lymphocytes does not require OX40-L/CD134 and is mediated by a concomitant down-regulation of IL-12 and CD70. Although it was previously stated that TSLP up-regulates the production of thymus and activation-regulated chemokine (TARC)/chemokine (C-C motif) ligand 17 (CCL17) and macrophage-derived chemokine (MDC)/CCL22 by human LC in vitro, our work shows that production of these Th2- cell attracting chemokines is increased only in keratinocytes in response to TSLP overexpression. These results demonstrate that LC are required for the development of AD in mouse models of AD involving epidermal TSLP overexpression.