Accumulation Of Foamy Macrophages Research Articles

Concept and Diagnostic Challenges of Renal-Limited Hemophagocytic Syndrome/Macrophage Activation Syndrome.

Hemophagocytic syndrome/macrophage activation syndrome (HPS/MAS) is a serious clinical condition that frequently leads to multiple organ failure, including acute kidney injury (AKI). Although the pathogenesis of AKI is not yet fully understood, it is believed to result from uncontrolled activation of the immune system involving macrophages and cytotoxic lymphocytes. Renal histology in HPS/MAS often presents with characteristic foamy glomerular lesions (glomerular lipidosis) with massive macrophage infiltration, known as histiocytic glomerulopathy. In this review, we introduce the recently proposed concept of renal-limited HPS/MAS as a novel etiology of histiocytic glomerular lipidosis. Patients with renal-limited HPS/MAS often develop AKI but do not fulfill the diagnostic criteria for HPS/MAS because their systemic manifestations are less severe. Therefore, the diagnosis largely depends on characteristic histological findings, that is, diffuse and global glomerular accumulation of foamy macrophages and cytotoxic lymphocytes accompanied by the interaction of these cells as well as the exclusion of various differential diseases. Although there are no established therapeutic regimens, these patients receive various types of therapies, including high-dose glucocorticoids, immunosuppressants, or anti-interleukin-1 drug, and generally achieve favorable outcomes. We summarized the concept, diagnostic challenges, and recent topics of this disease entity and discussed treatment options based on our own experiences.

Endogenous lipid pneumonia associated with atherosclerosis in a blue-fronted Amazon parrot (Amazona aestiva)

Endogenous lipid pneumonia is a rare inflammatory, non-infectious lung disease characterized by the accumulation of endogenous lipids in alveolar macrophages. It has been associated with bronchial obstruction, chronic lung inflammation, alveolar proteinosis and lipid storage disorders. A 14-year-old female blue-fronted Amazon parrot (Amazona aestiva) presented with intermittent dyspnoea, neurological signs and persistent lipaemia of unknown aetiology. At necropsy, the most relevant gross findings were increased rigidity of the great vessels, lungs with diffuse grey to whitish discolouration of the parenchyma and multifocal small yellowish nodules. Microscopic examination revealed typical lesions of atherosclerosis and severe multifocal accumulation of foamy macrophages filling the parabronchi, which led to a diagnosis of endogenous lipid pneumonia. Although the relationship between dyslipidaemia, atherosclerosis and endogenous lipid pneumonia in birds is not well established, the chronic dyslipidaemia of unknown origin could be involved in the pathogenesis of both the atherosclerosis and the endogenous lipid pneumonia. The present case highlights the need to better understand the relationships between various disorders of lipid metabolism in psittacine birds.

Cerium fluoride nanoparticles as a theranostic material for optical imaging of vulnerable atherosclerosis plaques

AbstractAtherosclerosis (AS) is a chronic progressive vascular disease, which can bring on a threat against the health. The eruption of unstable arteriosclerosis plaques has been linked to heart attacks and strokes. The accumulation of foamy macrophages initiates and evolves atherosclerotic plaques, which can be a good target for identifying vulnerable plaques. CD36 and OPN overexpress in foamy macrophages surface, which have a preferable relation with plaque disruption. Furthermore, we choose Yb ions and Tm ions as doping ions and Ce fluoride as matrix of luminescent materials and prepare upconversion luminescent nanoparticles. With the modification of CD36 antibody and OPN antibody, this material can target macrophages in arteriosclerosis plaques. As‐prepared nanoparticles (CeF3:Yb,Tm@SiO2–CD36/OPN) can be excited by near‐infrared light with deep tissue penetration, while emitting strong blue light to image arteriosclerosis plaques. In brief, this study provides a new upconversion luminescent material for the identification and detection of vulnerable atherosclerosis plaques.

Accumulation of foamy macrophages in the bone marrow following chronic intravenous drug use.

Accumulation of foamy macrophages in the bone marrow following chronic intravenous drug use.

E-Cigarette or Vaping Product Use-Associated Lung Injury: A Review for Pathologists.

Vaping is the inhalation of heated aerosol from a small battery-powered device as a method to deliver nicotine or other substances. A recent outbreak of severe respiratory illness primarily in the United States has put a spotlight on vaping and its potential risks. To familiarize pathologists with vaping, the cytologic and histopathologic features of vaping-associated acute lung injury, and the role of pathology in this diagnosis. A targeted literature review was performed. Most cases of vaping-associated lung injury have been linked to vaping products containing tetrahydrocannabinol or other cannabinoids. Lung biopsies show a spectrum of nonspecific acute lung injury patterns (organizing pneumonia, diffuse alveolar damage, acute fibrinous, and organizing pneumonia, or combinations of the above), accompanied by prominent, foamy macrophage accumulation. Injury is usually accentuated around small airways. Lipid-laden macrophages can be identified in bronchioloalveolar lavage fluid in most patients and these can be highlighted using lipid stains, such as oil red O, but the clinical utility of this finding remains unclear, as lipid-laden macrophages can be seen in a wide variety of processes and should not be relied upon to make the diagnosis. Classic histologic features of exogenous lipoid pneumonia have not been identified in tissue samples. Lightly pigmented macrophages, similar to those seen with traditional cigarette smoking, are present in some cases but are usually a minor feature. To date, no specific pathologic features for vaping-related injury have been identified, and it remains a diagnosis of exclusion that requires clinicopathologic correlation.

Novel Anti-bacterial and Anti-inflammatory Roles for the Macrophage Galactose-type Lectin in Pulmonary Immunity to Mycobacterium tuberculosis

Abstract Pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) is characterized by inflammatory pathology that is regulated by poorly understood mechanisms of innate immunity. Pattern recognition receptors (PRR) expressed on the surface of macrophages regulate the balance of inflammatory and antimicrobial functions that determine disease outcome. Our work identifies a novel role for the C-type lectin receptor Macrophage Galactose-type Lectin (MGL) PRR in a murine model of experimental tuberculosis. Bone marrow derived macrophages (BMDM) upregulate MGL-1, but not MGL-2, following in vitro exposure to both heat killed and live Mtb. Macrophages from MGL-1-deficient mice display greater lipid accumulation, and increased production of pro-inflammatory cytokines (IL-1b, IL-6 and IFN-g). Mtb growth is also increased in MGL−/− BMDM, independent of the inflammatory outcomes and production of reactive nitrogen species. TB in mice lacking MGL-1 results in increased pro-inflammatory cytokines, more diffuse granulomatous inflammation, and increased accumulation of foamy macrophages. Assessment of disease kinetics suggests that MGL has an important role for controlling mycobacterial burden during the establishment stages of TB disease, and has less influence once the chronic disease stage is established. Macrophages in murine and human TB granulomas contain abundant MGL associated with inflammatory foci. These results suggest that MGL is a potential new therapeutic target against TB.

Innate immune role for the Macrophage Galactose Lectin (MGL) pathway in pulmonary tuberculosis

Abstract Pulmonary tuberculosis (TB), caused by the pathogen Mycobacterium tuberculosis (Mtb), remains a significant public health threat and accounts for 1.3 million deaths each year. Innate immune responses to Mtb through pathogen recognition receptor signaling are capable of producing protective immune responses and controlling infection. To date, however, an anti-mycobacterial role for the C-type lectin receptor Macrophage Galactose Lectin (MGL), present on the surface of alternatively activated macrophages and dendritic cells, has not been described. MGL has been shown to be an important anti-inflammatory immune receptor during Klebsiella pneumoniae pneumonic sepsis, suggesting its involvement during lung infections; although the role of MGL during TB has not been studied. In preliminary studies, we identified HIV-mediated disruption of MGL gene expression in the lungs of humanized mice co-infected with HIV and Mtb by using a custom macrophage transcriptome array. To further investigate a role for how loss of MGL activation would affect innate immunity to Mtb, we compared disease following pulmonary challenge of MGL−\− and WT mice with Mtb H37Rv. Compared to WT mice, we observed greater mycobacterial burden in the lungs of MGL−\− mice. We additionally observed differences in pulmonary pathology including the accumulation of foamy macrophages and altered patterns of leukocyte organization in granulomas. These data suggest that MGL signaling may regulate myeloid cell antimicrobial activity and inflammatory outcomes at sites of Mtb infection in the lung.

Transcriptome Analysis Reveals Nonfoamy Rather Than Foamy Plaque Macrophages Are Proinflammatory in Atherosclerotic Murine Models.

Monocyte infiltration into the subintimal space and its intracellular lipid accumulation are the most prominent features of atherosclerosis. To understand the pathophysiology of atherosclerotic disease, we need to understand the characteristics of lipid-laden foamy macrophages in the subintimal space during atherosclerosis. We sought to examine the transcriptomic profiles of foamy and nonfoamy macrophages isolated from atherosclerotic intima. Single-cell RNA sequencing analysis of CD45+ leukocytes from murine atherosclerotic aorta revealed that there are macrophage subpopulations with distinct differentially expressed genes involved in various functional pathways. To specifically characterize the intimal foamy macrophages of plaque, we developed a lipid staining-based flow cytometric method for analyzing the lipid-laden foam cells of atherosclerotic aortas. We used the fluorescent lipid probe BODIPY493/503 and assessed side-scattered light as an indication of cellular granularity. BODIPYhiSSChi foamy macrophages were found residing in intima and expressing CD11c. Foamy macrophage accumulation determined by flow cytometry was positively correlated with the severity of atherosclerosis. Bulk RNA sequencing analysis showed that compared with nonfoamy macrophages, foamy macrophages expressed few inflammatory genes but many lipid-processing genes. Intimal nonfoamy macrophages formed the major population expressing IL (interleukin)-1β and many other inflammatory transcripts in atherosclerotic aorta. RNA sequencing analysis of intimal macrophages from atherosclerotic aorta revealed that lipid-loaded plaque macrophages are not likely the plaque macrophages that drive lesional inflammation.

All-trans retinoic acid effectively reduces atheroma plaque size in a rabbit model of high-fat-induced atherosclerosis.

Atherosclerosis (AS) is one of the most prevalent causes of death around the world. Since there are different types of risk factors, different types of medications focus on preventing atheromas and plaques from establishing or on preventing established plaques from growing. The aim of this study was to evaluate the effect of all-trans retinoic acid (atRA) on AS in a rabbit model of fat-induced AS. Atherosclerosis was induced by a high-fat diet (HFD) for 75 days. Thirty rabbits were randomly divided into 5 groups. Group 1 was the negative control group and received a normal diet. The animals in the other groups were fed a HFD. Group 2 (the AS positive control group) received no drugs, Group 3 received atorvastatin orally (20 mg/kg/day), Group 4 received atRA (5 mg/kg/day, orally), and Group 5 received both drugs. All medications were started on day 45 and continued until the end of the study. Fasting blood samples were obtained for lipid profile evaluation. The aorta sections were evaluated for maximum wall and intima thickness. Oral administration of atRA, atorvastatin or their combination significantly improved serum lipid profile (p < 0.001). Atorvastatin and atRA significantly decreased serum total cholesterol and LDL-cholesterol levels in HFD (p < 0.001). No difference was found in serum HDL-cholesterol levels among the studied groups. The HFD group (Group 2 - positive control) showed significant intima irregularities with fat deposition and foamy macrophage accumulation (atheroma). Administration of atRA and atorvastatin significantly decreased the size of atherosclerotic plaques (intima thickness). The maximum vessel wall and intima thickness were significantly decreased after atRA and atorvastatin administration (p < 0.001). No difference was found between atRA and atorvastatin effectiveness, but combination therapy significantly decreased AS size in comparison to using either of the drugs alone (p < 0.001). In reducing AS plaque size, atRA is as effective as atorvastatin. Additionally, the combination therapy of atRA and atorvastatin decreased AS size much more effectively, showing their synergistic effect. atRA can also improve the serum lipid profile.

Tolerance of chronic HDACi treatment for neurological, visceral and lung Niemann-Pick Type C disease in mice

Histone deacetylase (HDAC) inhibitors are of significant interest as drugs. However, their use to treat neurological disorders has raised concern because HDACs are required for brain function. We have previously shown that a triple combination formulation (TCF) of the pan HDACi vorinostat (Vo), 2-hydroxypropyl-beta-cyclodextrin (HPBCD) and polyethylene glycol (PEG) 400 improves pharmacokinetic exposure and entry of Vo into the brain. TCF treatment significantly delayed both neurodegeneration and death in the Npc1nmf164 murine model of Niemann-Pick Type C (NPC) disease. The TCF induces no metabolic toxicity, but its risk to normal brain functions and potential utility in treating lung disease, a major NPC clinical complication, remain unknown. Here we report that TCF administered in healthy mice for 8–10 months was not detrimental to the brain or neuromuscular functions based on quantitative analyses of Purkinje neurons, neuroinflammation, neurocognitive/muscular disease symptom progression, cerebellar/hippocampal nerve fiber-staining, and Hdac gene-expression. The TCF also improved delivery of Vo to lungs and reduced accumulation of foamy macrophages in Npc1nmf164 mice, with no injury. Together, these data support feasibility of tolerable, chronic administration of an HDACi formulation that treats murine NPC neurological disease and lung pathology, a frequent cause of death in this and possibly additional disorders.

Abstract 73: Triggering Receptor Expressed on Myeloid Cells-2 Expression derived From Microglia Contributes to Neurological Recovery in Experimental Ischemic Stroke

Background and Purpose: We previously reported that triggering receptor expressed on myeloid cells-2 (TREM2) expression promotes post-ischemic phagocytosis and leads to neurological recovery. However, the precise underlying mechanism is not fully understood yet. In present study, we aimed to clarify which pool of myeloid cells (brain resident microglia versus macrophage derived from circulation) are contributing to its beneficial role in post-ischemic recovery, with the usage of bone marrow (BM) chimeric mice. Methods: BM chimeric mice were created by BM transplanting BM from TREM2 knockout (KO) and wild type (Wt) mice into KO and Wt recipient mice. Thus, 4 groups (Wt (donor) to Wt (recipient), KO to Wt, Wt to KO, KO to KO; n=6/each) of BM chimeric mice were produced, then were subjected to dMCAO surgery. Neurological function was observed until 14 days after surgery. Infarct volume and immunohistological analysis (myeloid cell activation and infiltration: isolectin B4 (IB4) and CD11b; phagocytosis: oil red o and CD68; TREM2 expression) was also undergone. Results: Compared to mice lacking brain TREM2 (WT to KO and KO to KO), mice with intact TREM2 in brain microglia (KO to WT and WT to WT) showed better neurological recovery (p&lt;0.05), and smaller infarct volume (p&lt;0.01). Myeloid cell activation and infiltration (IB4) was significantly decreased in order of WT to WT, KO to Wt, Wt to KO, KO to KO (p&lt;0.05). Likewise, number of TREM2 positive myeloid cells (CD11b) showed similar decreases. Oil red o staining demonstrated that mice with intact TREM2 in microglia (KO to WT and WT to WT) showed more accumulation of foamy macrophages, compared to mice lacking TREM2 in brain (Wt to KO and KO to KO). Furthermore, both the number and proportion of TREM2 positive phagocytes (CD68) was significantly higher in mice with intact TREM2 in the brain, compared to mice lacking brain TREM2. Conclusions: Although our results suggest TREM2 expression in both microglia and circulating macrophage were crucial for post-ischemic recovery, its beneficial effect was greater when TREM2 was present in brain resident microglia.

Ozone-Induced Vascular Contractility and Pulmonary Injury Are Differentially Impacted by Diets Enriched With Coconut Oil, Fish Oil, and Olive Oil.

Fish, olive, and coconut oil dietary supplementation have several cardioprotective benefits, but it is not established if they protect against air pollution-induced adverse effects. We hypothesized that these dietary supplements would attenuate ozone-induced systemic and pulmonary effects. Male Wistar Kyoto rats were fed either a normal diet, or a diet supplemented with fish, olive, or coconut oil for 8 weeks. Animals were then exposed to air or ozone (0.8 ppm), 4 h/day for 2 days. Ozone exposure increased phenylephrine-induced aortic vasocontraction, which was completely abolished in rats fed the fish oil diet. Despite this cardioprotective effect, the fish oil diet increased baseline levels of bronchoalveolar lavage fluid (BALF) markers of lung injury and inflammation. Ozone-induced pulmonary injury/inflammation were comparable in rats on normal, coconut oil, and olive oil diets with altered expression of markers in animals fed the fish oil diet. Fish oil, regardless of exposure, led to enlarged, foamy macrophages in the BALF that coincided with decreased pulmonary mRNA expression of cholesterol transporters, cholesterol receptors, and nuclear receptors. Serum microRNA profile was assessed and demonstrated marked depletion of a variety of microRNAs in animals fed the fish oil diet, several of which were of splenic origin. No ozone-specific changes were noted. Collectively, these data indicate that although fish oil offered vascular protection from ozone exposure, it increased pulmonary injury/inflammation and impaired lipid transport mechanisms resulting in foamy macrophage accumulation, demonstrating the need to be cognizant of potential off-target pulmonary effects that might offset the overall benefit of this vasoprotective supplement.

Histologic and biochemical alterations predict pulmonary mechanical dysfunction in aging mice with chronic lung inflammation.

Both aging and chronic inflammation produce complex structural and biochemical alterations to the lung known to impact work of breathing. Mice deficient in surfactant protein D (Sftpd) develop progressive age-related lung pathology characterized by tissue destruction/remodeling, accumulation of foamy macrophages and alteration in surfactant composition. This study proposes to relate changes in tissue structure seen in normal aging and in chronic inflammation to altered lung mechanics using a computational model. Alterations in lung function in aging and Sftpd -/- mice have been inferred from fitting simple mechanical models to respiratory impedance data (Zrs), however interpretation has been confounded by the simultaneous presence of multiple coexisting pathophysiologic processes. In contrast to the inverse modeling approach, this study uses simulation from experimental measurements to recapitulate how aging and inflammation alter Zrs. Histologic and mechanical measurements were made in C57BL6/J mice and congenic Sftpd-/- mice at 8, 27 and 80 weeks of age (n = 8/group). An anatomic computational model based on published airway morphometry was developed and Zrs was simulated between 0.5 and 20 Hz. End expiratory pressure dependent changes in airway caliber and recruitment were estimated from mechanical measurements. Tissue elements were simulated using the constant phase model of viscoelasticity. Baseline elastance distribution was estimated in 8-week-old wild type mice, and stochastically varied for each condition based on experimentally measured alteration in elastic fiber composition, alveolar geometry and surfactant composition. Weighing reduction in model error against increasing model complexity allowed for identification of essential features underlying mechanical pathology and their contribution to Zrs. Using a maximum likelihood approach, alteration in lung recruitment and diminished elastic fiber density were shown predictive of mechanical alteration at airway opening, to a greater extent than overt acinar wall destruction. Model-predicted deficits in PEEP-dependent lung recruitment correlate with altered lung lining fluid composition independent of age or genotype.

Hypervirulent Mycobacterium tuberculosis strain triggers necrotic lung pathology associated with enhanced recruitment of neutrophils in resistant C57BL/6 mice.

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (Mtb) that in most cases induces irreversible necrosis of lung tissue as a result of excessive inflammatory reactions. The murine model of TB in resistant C57BL/6 mice infected with reference Mtb strains is widely used in TB studies; however, these mice do not show a necrotic pathology, which restricts their use in studies of irreversible tissue damage. Recently, we demonstrated that necrotic lung lesions could be induced in the C57BL/6 mice by highly virulent Mtb strains belonging to the modern Beijing sublineage. However, the pathogenic mechanisms leading to necrosis in this model were not elucidated. In this study, we investigated the dynamics of lung lesions in mice infected with highly virulent Beijing Mtb strain M299, compared with those infected with laboratory Mtb strain H37Rv. The data demonstrate that necrotic lung lesions in mice infected by the strain M299 were associated with enhanced recruitment of myeloid cells, especially neutrophils, and increased levels of proinflammatory cytokines, consistent with exacerbated inflammation. High levels of IFN-γ production contributed to the control of bacterial growth. Further progression to chronic disease was associated with a reduction in the levels of inflammatory mediators in the lungs, the accumulation of foamy macrophages and partial healing of the necrotic tissue by fibrosis. At a late stage of disease, degradation of foamy cells resulted in the liberation of accumulated lipids and persisting bacilli and further activation of inflammation, which promoted lung consolidation. Overall, our studies show that C57BL/6 mice infected with highly virulent Mtb strain may serve as a TB model reproducing an exacerbated inflammatory response in a resistant host to hypervirulent mycobacteria, leading to irreversible necrotic lung lesions.

Nonclinical safety of mavrilimumab, an anti-GMCSF receptor alpha monoclonal antibody, in cynomolgus monkeys: Relevance for human safety

Mavrilimumab (CAM-3001) is an investigational human IgG4 monoclonal antibody (MAb) targeting GM-CSF receptor alpha which is currently being developed for the treatment of RA. GM-CSF plays a central role in the pathogenesis of rheumatoid arthritis (RA) through the activation, differentiation, and survival of macrophages and neutrophils. To support clinical development, the nonclinical safety of mavrilimumab was evaluated in several studies with cynomolgus monkeys as the pharmacologically relevant species. Comprehensive toxicity parameters were assessed in each study, and treatment duration ranged from 4 to 26weeks. Mavrilimumab has an acceptable safety profile in monkeys with no changes in any parameters other than microscopic findings in lung. In several studies, minimal accumulation of foamy alveolar macrophages was observed. This finding was only seen in studies of at least 11weeks duration, was reversible following a dose-free recovery period and was considered non-adverse. At higher dose levels (≥30mg/kg/week), in a 26-week repeat-IV dose study, the presence of lung foreign material, cholesterol clefts, and granulomatous inflammation was also observed in a few animals and was considered adverse. The dose- and time-related accumulation of foamy macrophages in lung following exposure to mavrilimumab observed in several NHP studies was expected based upon the known role of GM-CSFRα signaling in the function of alveolar macrophages. Overall, a clean no-observed-adverse-effect-level (NOAEL) without any effects in lung was established and provided adequate clinical safety margins. In clinical studies in RA patients, mavrilimumab has demonstrated good clinical activity with adequate safety to support further clinical development. A Phase 2b study of mavrilimumab in subjects with RA is in progress.

Histopathological, Immunohistochemical and Exfoliative Cytological Studies of Oral Verruciform Xanthoma

Verruciform xanthoma is a rare tumor-like lesion, predominantly affecting the oral mucosa. Although several studies of verruciform xanthoma have been reported, the characteristic features and pathogenesis have not been fully clarified. The purpose of the present study is to perform immunohistochemical analysis using markers of proliferative cell activity and cytokeratins, and to perform comparative analysis between cytological and histological features in order to clarify the characteristic features of verruciform xanthomas. Histological findings showed exophitic proliferation of stratified squamous epithelium and accumulation of foamy macrophages between epithelial processes. Immunohistochemically, accumulated foamy cells showed positive immuno-reactivity for CD68, and positive cells were also present in the epithelium. Expression of pancy-tokeratin was observed in most layers of the epithelium, whereas cytokeratin 13 was also detected in prickle cell layers. Positive reactivity for Ki-67 was observed in epithelial cell nuclei. Positive reactivity was largely distributed in basal and/or parabasal cell layers, and the positive cell rate was 20%. In addition, exfoliative cytological findings showed hyperkeratotic epithelial cells with picnosis, thus suggesting the characteristics of hyperplastic epithelium in verruciforma, although foamy cells were not observed in the cytological specimens. These results suggest that benign morphological characteristics with local cellular immune response of verruciform xanthoma may be evaluated based on immunohistochemical expression of cytokeratin and Ki-67, as well as exfoliative cytological findings.

Evaluation of a compression resistant matrix for recombinant human bone morphogenetic protein‐2

Previous studies document the therapeutic potential of recombinant human bone morphogenetic protein-2 (rhBMP-2) in an absorbable collagen sponge (ACS) carrier for indications in the axial and appendicular skeleton. Nevertheless, the ACS does not comprise structural integrity to adequately support bone formation for onlay indications. The objective of this study was to evaluate local bone formation and osseointegration following surgical implantation of rhBMP-2 soak-loaded onto a compression resistant matrix (CRM). Routine, contralateral, critical-size, supraalveolar, peri-implant defects in five adult male Hound Labrador mongrel dogs received 0.8mg rhBMP-2 soak-loaded onto either the ACS (benchmark control) or a CRM (collagen/β-TCP/hydroxyapatite) followed by submerged wound closure for primary intention healing. The animals were euthanized at 8weeks for histologic/histometric evaluation. Healing was uneventful albeit considerable initial swelling was observed for either treatment. Sites receiving rhBMP-2/CRM showed significantly increased bone area (20.0±0.9 versus 12.3±2.6mm(2) , p=0.03) and bone density (24.1±1.4% versus 14.6±2.0%, p=0.04) compared with those receiving rhBMP-2/ACS. There were no significant differences between treatments for new bone height and osseointegration. Woven and lamellar trabecular bone lined with abundant osteoid was observed for all sites. Inconsistent cortex formation confirmed the immature nature of the newly formed bone. Seroma formation was observed for both treatments (80-100% of the animals/implants). Sites receiving rhBMP-2/CRM showed residual ceramic granules undergoing biodegradation, including accumulation of foamy macrophages. rhBMP-2/CRM supports bone formation of clinically relevant geometry. Longer observation intervals as well as dose variations appear necessary to capture maturation of the newly formed bone, elimination of residual ceramic granules and resolution of seroma formation(s).

Abstract 313: The Nuclear Liver X Receptor as a Potential Regulator of Interleukin 18 Binding Protein in the Lung

Background and Objectives: Second hand smoke (SHS) is a major risk factor for development of chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis in non-smokers. The role of liver X receptor (LXR) in the pathogenesis of COPD/emphysema is not well understood. Both LXR and LXR were found in the lung. The alpha isoform is involved in the regulation of lipid metabolism whereas the beta isoform is involved in the regulation of inflammation. Here we investigate the effects of cigarette smoke (CS) on LXR activation as well as target gene and protein regulation in vivo and in vitro . Methods: Sprague Dawley rats were exposed to SHS for 2 months. Lung tissue and bronchoalveolar lavage fluid (BALf) cells were examined for LXR gene expression and emphysema development (measured by mean linear intercept). Rat alveolar macrophages (AM) and rat pulmonary microvascular endothelial cells (RPMVEC) were treated with cigarette smoke extract (CSE), LPS or DMHCA, a steroidal LXR agonist) in vitro and changes in LXR and its target gene and protein expression were examined. Results: LXR gene expression was impaired and the expression of the LXR target gene, ATP binding cassette transporter A1 (ABCA1), was significantly downregulated in BALf cells from SHS-exposed rat lungs and in rat AM treated with CSE. Real-time PCR revealed significant downregulation of LXR and upregulation of LXR in BALf cells after 1 month of SHS exposure. Similar changes were also observed in CSE-treated RPMVEC. There was a significant increase in the pro-inflammatory interleukin 18 (IL18) levels in BALf cells of SHS-exposed rats, whereas the levels of IL18 binding protein (IL18bp), an endogenous inhibitor of IL18, remained unchanged. Interestingly, activation of LXR led to upregulation of IL18bp in AM and peritoneal macrophages where potential LXR response element (LXRE) sites were indentified, in silico , in the promoter region of IL18bp. Additionally, emphysematous changes and foamy macrophage accumulation were observed in lungs of LXR-deficient mice. Conclusions: These findings implicate IL18bp as a new LXR target gene involved in the anti-inflammatory signaling pathway. Our data suggest that LXR agonist treatment may be beneficial in the prevention and treatment of CS-induced emphysema.

Salida celular y transporte reverso de colesterol

The ability of high-density lipoproteins (HDL) to transport cholesterol from peripheral tissues to the liver for excretion is considered crucial to prevent the accumulation of foamy macrophages in the arterial intima. The acquisition of cellular cholesterol is initiated by ABCA1-mediated cholesterol efflux to apolipoprotein (apo) A-I, thus generating pre-β-HDL. Cholesterol esterification by lecithin-cholesterol acyltransferase promotes the formation of mature HDL (α-HDL). In humans, practically all HDL cholesterol esters reach the liver after being transferred to very low (VLDL)- and low (LDL)-density lipoproteins by the cholesteryl ester transfer protein and subsequent uptake by the LDL receptor. However, HDL can deliver free cholesterol directly to the liver through the CLA- 1/SR-B1 receptor, a step that is aided by the prior action of hepatic lipase. These latter interactions lead to the release of small HDL particles and apo A-I, which then can newly acquire cholesterol in the peripheral tissues.

Evaluation of Lung Tolerance of Ethanol, Propylene Glycol, and Sorbitan Monooleate as Solvents in Medical Aerosols

Aerosol therapy is an expanding technique allowing administration of drugs acting locally in the bronchial tree and lungs or acting systemically after absorption through the respiratory tract. However, the choice of solvents and adjuvants is a critical step in the formulation process of new drugs. Pulmonary tolerance of ethanol, propylene glycol and sorbitan ester was evaluated in a rat model of intratracheal administration using a Microsprayer in a 4-day toxicity study. Four groups of Sprague-Dawley rats (11 rats per group, n = 44) have received, on 4 consecutive days 150 microL of solutions containing the solvents, by intratracheal route using a IA-1B-2 inches-Microsprayer (PennCentury, Philadelphia, PA). Once a day, the rats received deionized water (control) or ethanol 10% or propylene glycol 30% or sorbitan monooleate 10%. All rats were sacrificed 24 h after the fourth administration. Biochemical analysis on bronchoalveolar lavage (BAL) fluid was performed on seven rats per group. The respiratory tract of the remaining four rats/group was examined histologically. Biochemistry and histopathology findings demonstrated that under the conditions tested, deionized water, 10% ethanol, and 30% propylene glycol were tolerated in a qualitatively similar way presenting limited cellular reaction. In contrast, 10% sorbitan monooleate produced an accumulation of foamy macrophages in the lungs and a higher degree of inflammation. In addition, animals in this group showed higher polymorphonuclear neutrophil recruitment and total proteins levels in BAL fluid. The overall results recommended ranking the vehicles according to the degree of inflammation which was induced: deionized water <10% ethanol < or =30% propylene glycol <10% Tween 80.