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ORAL 23 - Prevention and Cancer Risk (ID 121)
- Event: WCLC 2015
- Type: Oral Session
- Track: Prevention and Tobacco Control
- Presentations: 1
ORAL23.03 - Role of Inflammatory Infiltrates in Promoting Persistence or Regression of Bronchial Dysplasia (ID 3026)
10:45 - 12:15 | Author(s): M.G. Edwards
Inflammatory infiltrates show differing capacities to eliminate malignant cells. This capacity is related to the polarization of key inflammatory cells in tumor infiltrates. A pathway analysis of genes that are differentially expressed between persistent and regressive bronchial dysplasia (BD) identified 13 pathways associated with persistence of which 8 were related to inflammation. We have hypothesized that differences in inflammatory infiltrate polarization may contribute to lung carcinogenesis and have employed gene expression and in situ analyses to characterize differences in inflammatory infiltrates related to persistence and regression of pre-malignant BD.
Normalized gene expression levels (Affymetrix Hu 1.0) of selected genes related to inflammatory cell polarization features were analyzed to find differences associated with follow-up histology for BD. Validational analyses of these relationships were undertaken in studies of baseline biopsies selected to represent persistent (n=43) and regressive BD (n=39). These biopsies were analyzed by quantitative immunohistochemistry and dual immunofluorescence studies to characterize the overall proportion of subsets of T-lymphocytes and macrophages in each of the groups. Image analysis tools (Aperio) were used to characterize the density of inflammatory cell subsets in the stromal and epithelial compartments of biopsy tissue within defined areas.
Analysis of expression levels for a subset of inflammatory cell related genes assessed in a global gene expression analysis indicated significantly higher levels of expression of macrophage M1 markers HLA-DRA (p=0.01) and inducible nitric oxide synthetase (iNOS; p=0.02) and T-helper lymphocyte marker CD4 (p=0.04) in regressive BD compared to persistent BD. There was also a trend toward higher expression of cytotoxic T-lymphocyte marker CD8 in regressive BD (p=0.25). Expression of B-lymphocyte and neutrophil markers were not different between regressive and persistent BD. CD68 immunohistochemical stains (IHC) demonstrated a trend toward an increase in macrophages per area of combined dysplastic epithelium and underlying stroma with a mean increase in IHC positivity of 1.75-fold in regressive versus persistent BD (p=0.08). CD4 and CD8 IHC showed 1.36- and 1.19-fold increases, respectively, in regressive BD but these changes were not statistically significant (p=0.36 and p=0.43 respectively). Dual immunofluorescence was undertaken to determine if polarization specific subsets of macrophages correlated with regression or persistence of BD. Analysis of a preliminary subset of regressive (n=3) and persistent (n=3) BD demonstrates a wide range of M1 to M2 ratios (range = 0.84 – 4.82 for ratio of HLA-DRA-CD68 dual positive M1 to CD206-CD68 dual positive M2 macrophages per high power field, 400X). Additional analyses of macrophages are ongoing to determine if the polarization status is related to regression or persistence of BD, and analysis of markers of T-helper lymphocyte subsets are planned.
Gene expression analyses indicate that increased expression of markers of M1 macrophages and T-helper lymphocytes are associated with regression, and in situ analyses suggest that differences in the amount of inflammatory cell subsets may be related to outcome in BD. These studies could have implications for predicting the behavior of premalignant disease and manipulating inflammatory activity in preventing progression of BD to invasive lung cancer.
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