ABSTRACT
Radiation-induced pulmonary fibrosis (RTPF) is a progressive, serious condition in many subjects treated for thoracic malignancies or after accidental nuclear exposure. No biomarker exists for identifying the irradiated subjects most susceptible to pulmonary fibrosis (PF). Previously, we determined that gastrin-releasing peptide (GRP) was elevated within days after birth in newborns exposed to hyperoxia who later developed chronic lung disease. The goal of the current study was to test whether radiation (RT) exposure triggers GRP release in mice and whether this contributes to RTPF in vivo. We determined urine GRP levels and lung GRP immunostaining in mice 0 to 24 after post-thoracic RT (15 Gy). Urine GRP levels were significantly elevated between 24 hours post-RT; GRP-blocking monoclonal antibody 2A11, given minutes post-RT, abrogated urine GRP levels by 6 to 12 hours and also altered phosphoprotein signaling pathways at 24 hours post-RT. Strong extracellular GRP immunostaining was observed in lung at 6 hours post-RT. Mice given one dose of GRP monoclonal antibody 2A11 24 hours post-RT had significantly reduced myofibroblast accumulation and collagen deposition 15 weeks later, indicating protection against lung fibrosis. Therefore, elevation of urine GRP could be predictive of RTPF development. In addition, transient GRP blockade could mitigate PF in normal lung after therapeutic or accidental RT exposure.
Subject(s)
Gamma Rays/adverse effects , Gastrin-Releasing Peptide/metabolism , Phosphoproteins/metabolism , Pulmonary Fibrosis/etiology , Radiation Injuries/etiology , Animals , Female , Mice , Pulmonary Fibrosis/metabolism , Pulmonary Fibrosis/pathology , Radiation Injuries/metabolism , Radiation Injuries/pathologyABSTRACT
Elastin synthesis and degradation in the airway and lung parenchyma contribute to airway mechanics, including airway patency and elastic recoil. IL-13 mediates many features of asthma pathobiology, including airway remodeling, but the effects of IL-13 on elastin architecture in the airway wall are not known. We hypothesized that IL-13 modulates elastin expression in airway fibroblasts from subjects with allergic asthma. Twenty-five subjects with mild asthma (FEV1, 89 ± 3% predicted) and 30 normal control subjects (FEV1, 102 ± 2% predicted) underwent bronchoscopy with endobronchial biopsy. Elastic fibers were visualized in airway biopsy specimens using Weigert's resorcin-fuchsin elastic stain. Airway fibroblasts were exposed to IL-13; a pan-matrix metalloproteinase (MMP) inhibitor (GM6001); specific inhibitors to MMP-1, -2, -3, and -8; and combinations of IL-13 with MMP inhibitors in separate conditions in serum-free media for 48 hours. Elastin (ELN) expression as well as MMP secretion and activity were quantified. Results of this study show that elastic fiber staining of airway biopsy tissue was significantly associated with methacholine PC20 (i.e., the provocative concentration of methacholine resulting in a 20% fall in FEV1 levels) in patients with asthma. IL-13 significantly suppressed ELN expression in asthmatic airway fibroblasts as compared with normal control fibroblasts. The effect of IL-13 on ELN expression was significantly correlated with postbronchodilator FEV1/FVC in patients with asthma. MMP inhibition significantly stimulated ELN expression in patients with asthma as compared with normal control subjects. Specific inhibition of MMP-1 and MMP-2, but not MMP-3 or MMP-8, reversed the IL-13-induced suppression of ELN expression. In asthma, MMP-1 and MMP-2 mediate IL-13-induced suppression of ELN expression in airway fibroblasts.
Subject(s)
Airway Remodeling/drug effects , Asthma/enzymology , Elastin/metabolism , Fibroblasts/metabolism , Interleukin-13/pharmacology , Lung/drug effects , Matrix Metalloproteinase 1/metabolism , Matrix Metalloproteinase 2/metabolism , Adult , Asthma/genetics , Asthma/pathology , Asthma/physiopathology , Bronchial Provocation Tests , Case-Control Studies , Colorado , Down-Regulation , Elastic Tissue/enzymology , Elastic Tissue/pathology , Elastin/genetics , Female , Fibroblasts/enzymology , Fibroblasts/pathology , Forced Expiratory Volume , Humans , Lung/enzymology , Lung/pathology , Lung/physiopathology , Male , Matrix Metalloproteinase Inhibitors/pharmacology , North Carolina , Severity of Illness Index , Signal Transduction/drug effects , Vital CapacityABSTRACT
BACKGROUND: Despite universal adoption of sentinel lymph node biopsy (SLNB) for breast cancer, there remains no standardized protocol for preoperative lymphoscintographic assessment of sentinel nodes. Both immediate and delayed lymphoscintigraphy are currently utilized, although it is unclear how delayed imaging impacts SLN identification. METHODS: Among patients diagnosed with breast cancer who underwent SLNB at Duke from 2011 to 2012, two protocols for preoperative lymphoscintigraphy were used: protocol A included both immediate and delayed lymphoscintigraphy (n = 152), while protocol B involved immediate lymphoscintigraphy only (n = 103). RESULTS: The overall intraoperative SLN identification rate was 98.4% and did not differ between groups. A lower number of SLN were visualized on the immediate scan using protocol A compared to protocol B (P < 0.001). Although a greater total number of nodes was excised using protocol A, this result was not statistically significant (P = 0.08). Moreover, there was no significant difference in the number of negative SLN between groups (P = 0.51). CONCLUSIONS: We found no significant impact on identification rate or number of SLN excised with the use of delayed versus immediate imaging. These findings support abandoning delayed lymphoscintographic imaging, except in those cases where aberrant drainage is suspected.
