Immune Cell Infiltration and Broncovascular Remodeling After Nitric Acid Nasal Instillation in a Mouse Bronchiolitis Obliterans Model

Abstract

Immune cell airway infiltration and the bronchovascular remodeling process have shown to be promising in the understanding of bronchiolitis obliterans (BO) pathogenesis. In this study we sought to validate the importance of immune cells, whether diffusely distributed or forming lymphoid follicles, collagen density, and vascular factors. Eight weeks after a single nitric acid (NA) nasal instillation, lung changes were characterized by lumen distortion, epithelial layer folding, reduction or total obliteration of terminal bronchiole (TB) lumen, and wall thickness increase. The morphologic changes in the TB and TA (terminal artery) lumen coincide with the measurement difference in the three groups. The TB diameter and lumen were significantly decreased in BO when compared with non-BO lungs (0.76 +/- 0.05 microm vs. 0.81 +/- 0.05 microm and 12,286.13 +/- 378.83 microm vs. 18,182.27 +/- 5,593.98 microm, p = 0.05 and p = 0.01, respectively). Equally significant was the increase in TB thickness in BO when compared with the non-BO group (201.72 +/- 35.75 microm vs. 149.75 +/- 40.61 microm, p = 0.007). The morphologic changes in immune cells seen in TB, TA, and bronchus-associated lymphoid tissue (BALT) also coincide with the quantification differences observed in the three groups. We concluded that immune cell infiltration and collagen/vascular remodeling are related to the spectrum of histologic changes in a BO nasal-induced model in mice and may be an appropriate target for prospective studies of human bronchiolitis.

Spatial and Phenotypic Characterization of Vascular Remodeling in a Mouse Model of Asthma

“…Previous studies have shown changes associated with the bronchovascular remodeling process in non-allergic inflammation. In a study by Ga rippo et al [32] , nasal instillation of nitric acid in a mouse model of bronchiolitis showed distortion and reduction in the terminal bronchiolar lumen, increase in bronchiolar and arteriolar wall thicknesses, deposition of collagen fibers, and diffuse immune cell infiltration. It was concluded that immune cell infiltration and collagen/vascular remodeling are related to the spectrum of histological changes in this mouse model.…”

Nasal Tolerance With Collagen v Protein Reverts Bronchovascular Axis Remodeling in Experimental Bronchiolitis Obliterans

“…13 For the immune cell infiltration markers, we used the following antibodies: CD20, B-Cell (Clone L26, Dako Corporation Carpinteria, USA, 1:600); CD3 (Leu-4, T 3 , 1:600), T-Cell CD4 (CD45RO, clone OPD4, 1:400); CD8 T-Cell (Clone C8/144B, 1:100); Macrophage, CD68 (Clone KP1, 1:3200), Neutrophil Elastase (Clone NP57, 1:800) from Dako A/S Denmark. A secondary procedure using the VECTASTAIN ® ABC kit (Vector Technologies, Burlingame, CA), which produces a streptavidin-biotin complex, was then performed.…”

“…Forty normal female BALB/c mice (4-6 weeks old and 17-26 g) were randomly divided into 4 groups: (i) in the control group, animals did not undergo any procedures (CTRL, n = 10); (ii) in the bronchiolitis obliterans group (BO, n = 10), mice received a single nasal instillation of a solution of 4.8 mmol/mL of HNO 3 2%, pH 0.1, as previously described; 13 (iii) nasal tolerance was induced in the animals with 8 weeks of bronchiolitis obliterans by daily nasal administrations of 20 ml (0.5 mg/mL/animal/day) collagen V for 7 days and, subsequently, after 30 days on alternate days 7 (BO + COLV-TOL group; n = 10); (iv) animals with 8 weeks of bronchiolitis obliterans were treated with 0.002 mg/animal/day of prednisone for 7 days (BO+PR group; n = 10). Figure 1 shows the experimental design.…”

“…We have recently reported immune cell infiltration and broncovascular axis remodeling after nasal instillation of nitric acid in a mouse model of bronchiolitis obliterans. 13 In the present study, we proposed to establish nasal tolerance with collagen V protein in an attempt to ascertain whether the main aspects of bronchiolitis obliterans, including bronchovascular axis remodeling, could be reverted by this therapeutic approach. To evaluate the significance of the effect of nasal tolerance with collagen V protein in bronchiolitis obliterans, we also assessed the effect of steroid treatment on bronchovascular axis remodeling.…”

“…12 Recently, we have shown an important inflammatory response in bronchiolitis obliterans produced by chemical injury, followed by remodeling of the bronchovascular axis. 13 The aim of promoting mucosal tolerance is to suppress specific immune reactivity without affecting the entire immunological system by deleting or inactivating specific antigen-driven T-cell clones. We have recently reported immune cell infiltration and broncovascular axis remodeling after nasal instillation of nitric acid in a mouse model of bronchiolitis obliterans.…”