Local Inflammatory Cell Infiltration Research Articles

Evidence for major basic protein immunoreactivity and interleukin 5 gene activation during the late phase response in explanted airways.

Current evidence suggests that the events subsequent to antigen challenge in allergic asthmatics involve eosinophil activation and the synthesis of proinflammatory cytokines, in particular interleukin 5 (IL-5). However, little is known about how local inflammatory cell infiltration and activation are related to the changes in lung function following allergen exposure. We have developed a novel technique to investigate the local inflammatory events during late-onset allergic bronchoconstriction in lung explants from sensitized Brown-Norway (BN) rats. In this study we tested the hypothesis that the in vitro late airway response involves IL-5 gene activation and recruitment and activation of eosinophils. Explants were prepared from excised lungs of BN rats (n = 9) sensitized 2 wk previously to ovalbumin (OVA). Lungs were inflated with liquid agarose solution (2% wt/vol, 48 ml/kg) following perfusion with cold Ca2+/Mg(2+)-free Hanks' solution, and refrigerated briefly to gel the agarose, and 0.5- to 1.0-mm slices were prepared and cultured overnight at 37 degrees C. Airways were identified and challenged by direct application of OVA (20 micrograms). Cryostat sections of explants were immunostained for major basic protein (MBP) and IL-5 mRNA was detected by a 35S-uridine triphosphate-labeled probe and in situ hybridization. Explants harvested immediately prior to challenge showed little evidence of MBP and IL-5 mRNA expression. Explants harvested at 6 h which exhibited evidence of bronchoconstriction showed strong cell-associated immunostaining for MBP and high expression of IL-5 mRNA in the bronchial mucosa. colocalization studies performed in lung explants demonstrating late-onset airway responses suggested that the majority of IL-5 mRNA expression was not found in MBP-positive cells. When compared with explants from sham-sensitized rats (n = 4), there was a significant increase in MBP-positive and IL-5 mRNA-positive cells per millimeter of basement membrane of the airway. The presence of MBP immunoreactivity and IL-5 gene expression was not observed in explants taken from sensitized BN rats which did not undergo late-onset airway responses, indicating an association between inflammatory cell activation and airway constriction. The increase in MBP-positive cells several hours after OVA suggests activation, local recruitment, and/or differentiation of eosinophils. This study provides direct evidence for a temporal association between IL-5 expression, eosinophil infiltration, and the late response in individual cultured airways.

Role of connective tissue autoimmunity in Graves' ophthalmopathy.

Histologic similarities exist between the tissues involved in the extrathyroidal manifestations of Graves' disease, namely ophthalmopathy and pretibial dermopathy. Both conditions are characterized by an accumulation of glycosaminoglycans (GAGs) and an infiltration of lymphocytes. We have shown that interleukin-1 and transforming growth factor-beta, cytokines released by the local inflammatory cell infiltrate, are capable of stimulating GAG synthesis by retroocular and pretibial fibroblasts. Additionally, affected retroocular and pretibial fibroblasts demonstrate an enhanced induction of HLA-DR in response to interferon-gamma treatment and both cell types express the 72 kDa heat shock protein in vivo and in vitro. Retroocular and pretibial fibroblasts from patients with Graves' ophthalmopathy and pretibial dermopathy thus seem to possess unique immunological features that may render them more susceptible to the autoimmune process in Graves' disease. Chronic stimulation of fibroblasts by cytokines released in the local inflammatory milieu may result in excessive GAG production. The accumulation of these hydrophilic mucopolysaccharides, with its associated edema, leads to the clinical manifestations of Graves' ophthalmopathy and pretibial dermopathy.

Retroocular fibroblasts: important effector cells in Graves' ophthalmopathy.

Retroocular and pretibial fibroblasts are likely important effector cells in Graves' ophthalmopathy and pretibial dermopathy. Histologic similarities exist between the tissues involved in these clinically diverse extrathyroidal manifestations of Graves' disease. Both conditions are characterized by an accumulation of glycosaminoglycans (GAGs) and an infiltration of lymphocytes. We have shown that particular cytokines, probably released by the local inflammatory cell infiltrate, are capable of stimulating GAG synthesis by retroocular and pretibial fibroblasts. In order to explain the site-selective involvement of these anatomically distinct areas in Graves' disease, we sought to identify unique characteristics shared by retroocular and pretibial fibroblasts. We have shown that affected retroocular and pretibial fibroblasts demonstrate an enhanced HLA-DR response to interferon-gamma treatment and that retroocular fibroblasts are especially sensitive to the GAG-stimulating effect of this cytokine. In addition, we have shown that only affected retroocular and pretibial fibroblasts express the 72 kDa heat shock protein. Therefore, affected retroocular and pretibial fibroblasts possess unique immunologic features that may render them more susceptible to the autoimmune process in Graves' disease. Chronic stimulation of fibroblasts by cytokines released in the local inflammatory milieu may result in excessive GAG production by these cells. The accumulation of these hydrophilic mucopolysaccharides, with attendant edema, leads to the clinical manifestations of Graves' ophthalmopathy and pretibial dermopathy.