Thiazolidinediones are ligands that bind to and activate the nuclear peroxisome proliferator-activated receptor gamma. They are widely used as insulin sensitizers for the treatment of type 2 diabetes. Several studies have implicated the peroxisome proliferator-activated receptor gamma agonists rosiglitazone and pioglitazone in inflammatory events. To assess the anti-inflammatory properties of rosiglitazone, we investigated its effects on the molecular and cellular inflammatory response induced by a carotid injury in the rat. Male Wistar rats were randomized into a rosiglitazone-treated group (10 mg kg(-1) day(-1)) and a control group (0.9% w/v NaCl). The drug or vehicle was administered by gavage for 7 days before carotid injury and for up to 21 days after injury. The inflammatory markers p38 mitogen-activated protein kinase, cyclooxygenase 2, nuclear factor-kappaB, and heat shock protein 47 and the influx and activity of cells in response to injury were measured. Rosiglitazone treatment significantly reduced the expression of the inflammatory markers compared with control group. p38 mitogen-activated protein kinase and nuclear factor-kappaB started to decrease a few hours after injury, whereas cyclooxygenase 2 and heat shock protein 47 expression decreased 7 and 14 days, respectively, after injury. Rosiglitazone also reduced neointima formation and inflammatory cell infiltration. In conclusion, rosiglitazone negatively regulated the inflammatory events involved in tissue repair at molecular and cellular levels. These results suggest that rosiglitazone plays a protective role in inflammatory vascular diseases.

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SUMMARYPeriodate-lysine-paraformaldehyde (PLP) has been proposed as a fixative for glycoprotein antigens which should stabilize periodate oxidized polysaccharide chains through lysine mediated crosslinks, either directly or by the intermediation of formaldehyde. In spite of premises and attempts reported in the literature, this fixative has never become popular for the study of membrane antigens of immune system cells, which leads to doubts on its real efficacy. We have addressed this issue in biopsies of human skin and found that PLP followed by cryoprotection with 30% sucrose and cryosectioning, or PLP fixation of isolated epidermal sheets, consistently provided for good preservation of morphology and intense labeling of major histocompatibility complex class II molecules, CD1a, CD4, CD8, E-cadherin, cytokeratins in general, cytokeratin-18 in particular, and bromodeoxyuridine, incorporated by cycling cells in vitro, and for the demonstration of tyrosinase enzyme activity. PLP-fixed, osmicated and epon-embedded epidermal sheets proved as good as sheets fixed 365 with a mixture of formaldehyde and glutaraldehyde for electron microscopic morphological analysis. Also, these sheets were amenable to immunoperoxidase staining of Langerhans cell membrane antigen CD1a and keratinocyte membrane antigen E-cadherin before being osmicated and prepared for electron microscopy. In a parallel paper, we had also shown that oral mucosa biopsies fixed in PLP showed good morphology and immunolabeling of CD54, CD80, CD83 and CD86. Therefore, we conclude that PLP can be proposed as a multi-task fixative for light and electron microscopic analysis of membrane, cytoplasmic and nuclear antigens of immune system cells and keratinocytes.

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Objectives: Intratracheal endotoxin in rats causes acute lung injury. Here we have addressed the cellular physiopathology of lung recovery from that injury. Methods: The lungs of 5 untreated rats and rats treated with intratracheal endotoxin from 2, 3, 5, 8 (5 rats each) and 15 days (2 rats) were studied by light and electron microscopy and immunohistochemistry. Results: In the acute phase there was a reduction in the aerated spaces (p < 0.01); diffuse infiltration of granulocytes and macrophages; hyperplasia of type-II pneumocytes, and hypertrophy of interstitial cells. Aerated spaces improved during recovery. In the early recovery phase (3–8 days) the compartmentalization of infiltrating cells varied significantly (p < 0.01): macrophages remained widespread while neutrophils were inside blood vessels. Many pneumocytes were intermediate between type-I and type-II cells. In the late recovery phase (15 days) the infiltrate disappeared; myofibroblasts were significantly more than previously (p < 0.01) and extracellular matrix was abundant; type-II pneumocytes contained non-lamellated lipid inclusions. Conclusions: Macrophages play a pivotal role in the damage-repair processes of the lung following endotoxin injury, leading to an increase in extracellular matrix, differentiation of myofibroblasts and altered secretion of surfactant by newly differentiated type-II pneumocytes.