Fluctuation of annexin-A1 positive mast cells in chronic granulomatous inflammation

OBJECTIVE: We have applied here a model of chronic granulomatous inflammation to study the profile of mast cell activation and their expression of annexin-A1 in the nodular lesion.MATERIALS: Granulomatous inflammation was induced by injection of croton oil and Freund's complete adjuvant (CO/FCA) into the dorsal air-pouches of mice. Skin tissue samples were collected from control group (24 h time-point; i. e. before disease development) and 7, 14, 21, 28 and 42 days post-CO/FCA treatment.RESULTS: Histopathological analyses revealed an on-going inflammation characterized by an increased number of activated mast cells at sites of the chronic inflammatory reaction in all experimental groups. Immunohistochemical analysis showed skin mast cells highly immunoreactive for annexin-A1, both at an initial (day 7) and a delayed (day 28) phase of the inflammatory reaction.CONCLUSIONS: The observed time-dependent modulation of mast cell activation, during the granulomatous injury, indicates that multiple pathways centred on annexin-A1 might become activated at different stages of this chronic inflammatory response, including the delayed and pro-resolving phase.     

Novel murine model of chronic granulomatous lung inflammation elicited by carbon nanotubes

Lung granulomas are associated with numerous conditions, including inflammatory disorders, exposure to environmental pollutants, and infection. Osteopontin is a chemotactic cytokine produced by macrophages, and is implicated in extracellular matrix remodeling. Furthermore, osteopontin is up-regulated in granulomatous disease, and osteopontin null mice exhibit reduced granuloma formation. Animal models currently used to investigate chronic lung granulomatous inflammation bear a pathological resemblance, but lack the chronic nature of human granulomatous disease. Carbon nanoparticles are generated as byproducts of combustion. Interestingly, experimental exposures to carbon nanoparticles induce pulmonary granuloma-like lesions. However, the recruited cellular populations and extracellular matrix gene expression profiles within these lesions have not been explored. Because of the rapid resolution of granulomas in current animal models, the mechanisms responsible for persistence have been elusive. To overcome the limitations of previous models, we investigated whether a model using multiwall carbon nanoparticles would resemble chronic human lung granulomatous inflammation. We hypothesized that pulmonary exposure to multiwall carbon nanoparticles would induce granulomas, elicit a macrophage and T-cell response, and mimic other granulomatous disorders with an up-regulation of osteopontin. This model demonstrates: (1) granulomatous inflammation, with macrophage and T-cell infiltration; (2) resemblance to the chronicity of human granulomas, with persistence up to 90 days; and (3) a marked elevation of osteopontin, metalloproteinases, and cell adhesion molecules in granulomatous foci isolated by laser-capture microdissection and in alveolar macrophages from bronchoalveolar lavage. The establishment of such a model provides an important platform for mechanistic studies on the persistence of granuloma.     

Modulation of angiogenesis in a model of chronic inflammation

Inflammation Research -     

Lymphocyte kinetics in a murine model of chronic inflammation

A modification of the air pouch system [1], has been developed to investigate the role of lymphocytes in an inmmunologically driven model of chronic inflammation. Radiolabelled spleen and lymph node mononuclear cells from mice presensitised withBordatella pertussis vaccine (BPV) were infused intravenously into mice also presensitised with BPV and challenged with BPV into 6 day old air pouches. Cell migration was monitored by gamma counting of tissues sampled 4 hours after infusion. The percentage increase in counts obtained in air pouch tissue compared to control skin, over a time course of 30 days, reached a peak at 10 days after BPV challenge. Vessels with features of high endothelial venules, and clusters of lymphocytes have been demonstrated histologically and immunohistochemically in air pouch tissue at this time.     

The anti-inflammatory activity of intal and beta-carotene in a model of experimental granulomatous lung inflammation

A-25 sephadex-induced granulomatous inflammation of the lungs in rats was treated with beta-carotene and intal in inhalations. Both drugs showed antiinflammatory activity reducing the area of alveolitis and emphysema in the lungs, number of neutrophils and lymphocytes in the bronchoalveolar fluid. The experimental data allow to recommend further trial of intal and beta-carotene in granulomatous pulmonary diseases.     

Oxidative damages in chronic inflammation of a mouse autoimmune disease model

Reactive oxygen species are generated in many types of inflammation; it is unclear, however, if inflammation leads to oxidative damage of DNA, proteins and lipids within the inflamed tissues. In this study, we used mice that are homozygous for the alymphoplasia (aly) mutation as a model to determine if inflammation induces oxidative damage in liver and pancreas. We found that 8-hydroxy-2'-deoxyguanosine (8OHdG), which is a product of oxidative DNA damage, increases with age in livers and pancreata of C57BL/6aly/aly (aly/aly) and C57BL/6 wild type (WT) mice. The 8OHdG levels in liver, but not in pancreas, of aged aly/aly mice were significantly higher than those in age-matched WT mice. We showed that aging enhances oxidative protein damage, as measured by carbonylated protein contents, in the pancreata of WT but not aly/aly mice. In contrast, neither aging nor inflammation was associated with lipid damage, as measured by thiobarbituric acid-reactive substances (TBARS), in aly/aly or WT mice. Our results indicate that chronic inflammation in liver but not pancreas leads to increased oxidative damage to DNA, but not to lipids and proteins in aly/aly mouse model.     

An immunocytochemical and in situ hybridization analysis of annexin 1 expression in rat mast cells: modulation by inflammation and dexamethasone

The presence and localization of the anti-inflammatory protein annexin 1 (also known as lipocortin 1) in perivenular rat mast cells was investigated here. Using the rat mesenteric microvascular bed and a combination of morphologic techniques ranging from immunofluorescence to electron microscopy analyses, we detected the presence of annexin 1 in discrete intracellular sites, both in the nucleus and in the cytoplasm. In resting mast cells, most of the protein pool (approximately 80% of the cytosolic portion) was localized to cytoplasmic granules. In agreement with other cell types, treatment of rats with dexamethasone (0.2 mg/kg, ip) increased annexin 1 expression in mast cells, inducing a remarkable appearance of clusters of protein immunoreactivity. This effect was most likely the result of de novo protein synthesis as determined by an increase in mRNA seen by in situ hybridization. Triggering an ongoing experimental inflammatory response (0.3 mg of carrageenin, ip) increased annexin 1 mRNA and protein levels. In conclusion, we report for the first time the localization of annexin 1 in connective tissue mast cells, and its susceptibility not only to glucocorticoid hormone treatment, but also to an experimental acute inflammatory response.     

Oral tolerance attenuates airway inflammation and remodeling in a model of chronic pulmonary allergic inflammation

We investigated the effects of oral tolerance (OT) in controlling inflammatory response, hyperresponsiveness and airway remodeling in guinea pigs (GP) with chronic allergic inflammation. Animals received seven inhalations of ovalbumin (1-5mg/mL-OVA group) or normal saline (NS group). OT was induced by offering ad libitum ovalbumin 2% in sterile drinking water starting with the 1st ovalbumin inhalation (OT1 group) or after the 4th (OT2 group). The induction of OT in sensitized animals decreased the elastance of respiratory system (Ers) response after both antigen and methacholine challenges, peribronchial edema formation, eosinophilic airway infiltration, eosinophilopoiesis, and airways collagen and elastic fiber content compared to OVA group (P<0.05). The number of mononuclear cells and resistance of respiratory system (Rrs) responses after antigen and methacholine challenges were decreased only in OT2 group compared to OVA group (P<0.05). Concluding, our results show that inducing OT attenuates airway remodeling as well as eosinophilic inflammation and respiratory system mechanics.     

The controversial aspects of granulomatous inflammation

The necessity of a new concept of nontumorous benign monocytosis is brought forward for discussion. It is suggested to include into the group of "granulomatous inflammation" chronic inflammation with epithelioid cell granulomas. Species peculiarities of rodents (mice and rats) are underlined, i.e. their capacity to form liver macrophagal proliferates as a response to various stimuli including antigenic and acute infectious ones.     

Distribution of cyclooxygenase isoforms in murine chronic granulomatous inflammation. Implications for future anti-inflammatory therapy

Inhibition of the enzyme cyclooxygenase (COX) is the basis for the mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs). COX exists as a constitutive (COX-1) and a mitogen-inducible (COX-2) isoform. The relative contribution of COX-1 and COX-2 to inflammation is unknown. This study investigated COX activity and the distribution of COX-1 and COX-2 during the development of a murine air pouch model of chronic granulomatous inflammation. COX activity progressively rose and was maximal at day 14. Of the COX metabolites measured, PGE₂ was the greatest >6-keto PGF_1α>TXB₂>PGF_2α. By day 7, COX-2-labelled fibroblast- and macrophage-like cells were observed and their number and distribution increased with time. At all time points, endothelial cells of venules in the loose connective tissue of the dermis showed immunoreactivity for COX-2. After day 14, labelling of capillaries in the granuloma was also observed. This study is the first to show that COX-2 is the predominant COX isoform in all stages of the inflammatory response. These results suggest that selective inhibition of COX-2 may prove more beneficial, with fewer gastric and renal side-effects, than existing NSAID therapy for the treatment of chronic inflammatory diseases.     

Induction of cardiovascular pathology in a novel model of low-grade chronic inflammation

ObjectiveEpidemiological and clinical evidence indicate that inflammatory processes play a pivotal role in a number of conditions associated with aging, including osteoporosis and cardiovascular diseases. The purpose of this study was to evaluate cardiovascular pathology and select inflammatory mediators of interest in a model of low-grade inflammation-induced osteopenia.MethodsSlow-release pellets were subcutaneously implanted in male rats to deliver 0, 3.3, or 33.3 μg of lipopolysaccharide (LPS)/day for 90 days. Tail blood was collected at 1, 2, and 3 months for differential white cell counts, and at the end of the study, hearts were harvested for histological and immunohistochemical evaluation.ResultsThe low-grade inflammatory response was characterized by elevated peripheral blood neutrophils and monocytes. Histological examination of heart cross sections revealed increased fibrous tissue, infiltration of lymphocytes, accumulation of mast cells, and roughened intimal borders within the arteries and arterioles, consistent with vascular disease. Inflammatory mediators (cyclooxygenase-2, tumor necrosis factor-α, and interleukin-1β) were up-regulated, and increased expression of platelet endothelial cell adhesion molecule-1 and receptor activator for NF-κB ligand was localized to the microvasculature endothelium.ConclusionsThese findings suggest that inflammation induced by chronic exposure to LPS produces cardiovascular pathology in the smaller intramural arteries and arterioles and support the utility of this model for further mechanistic and therapeutic studies focused on the role of chronic inflammation in cardiovascular disease.     

Fibronectin in chronic inflammation: studies using the rat air pouch model of chronic allergic inflammation

Fibronectin is a large glycoprotein of plasma, tissue fluids and tissues. The rat air pouch model of mesenchymal inflammation was used to examine changes in fibronectin levels during inflammation within a mesenchymal cavity. Rat plasma fibronectin levels showed a rapid and significant rise in relation to the induction of an air pouch. In contrast pouch fluid fibronectin levels were initially low and gradually increased with chronicity. They were unrelated to plasma levels. Pouch fluid fibronectin showed no relationship to cell content of the fluid, its volume, nor the weight of granulation tissue. Two-dimensional immuno-electrophoresis showed pouch fluid fibronectin was partially complexed but plasma fibronectin was not. These results show plasma and tissue fluid fibronectin have different patterns of response to inflammation. In rats plasma fibronectin is an acute-phase reactant, although this is not the case in humans.     

Biochemical characterization of arylsulfatases detected in granulomatous inflammation

Arylsulfatases A and B were measured in the liver of mice infected with Schistosoma mansoni. The increase of total arylsulfatases paralleled enlargement of the granulomas. It began at 7 weeks after infection and reached a maximum at 10 to 14 weeks when the enzyme activity became about 2.5 times that of normal liver. The elevated enzyme activity was due to granulomatous tissue, because when granulomas were separated from hepatic cells, the former contained the increased activity but the latter did not. Arylsulfatase A, arylsulfatase B, and arylsulfatase Bv, in both normal liver and granulomas, were separated by anion-exchange column chromatography and differences in net charges of these enzymes were demonstrated by polyacrylamide gel electrophoresis. Biochemical properties were indistinguishable between arylsulfatase B and arylsulfatase Bv while they differed from arylsulfatase A. Granulomas at 8 weeks after infection showed 3.0-, 3.5-, and 5.0-fold increases in activity for arylsulfatase A, B, and Bv, respectively. As the granulomas enlarged, by 12 weeks, arylsulfatases B and Bv activities further increased but the arylsulfatase A value remained the same as that of 8 weeks. The finding suggests that arylsulfatases are involved in granuloma development and arylsulfatases B and Bv activities may reflect functions of macrophages and other cells including fibroblasts.     

Macrophages and control of granulomatous inflammation in tuberculosis

The granuloma that forms in response to Mycobacterium tuberculosis must be carefully balanced in terms of immune responses to provide sufficient immune cell activation to inhibit the growth of the bacilli, yet modulate the inflammation to prevent pathology. There are likely many scenarios by which this balance can be reached, given the complexity of the immune responses induced by M. tuberculosis. In this review, we focus on the key role of the macrophage in balancing inflammation in the granuloma.