Outcome and significance of pulmonary pathological changes induced by a single intramuscular injection of chemokine-like factor 1 in mice

Abstract

To investigate the significance of pathological changes in murine lung by a single intramuscular injection of chemokine-like factor 1 (CKLF1). A total of 120 gender-matched BALB/c mice were randomly and evenly divided into treatment group and control group (60 in each). One hundred nanomilligram of pcDNA3.1-CKLF1-Myc-His, CKLF1-expressing plasmid, in 100 microl of pyrogen-free saline was injected into the anterior tibial muscle of mice followed by the delivery of electric pulses. Mice in the control group received 100 microg of pcDNA3.1-Myc-His in 100 microl of pyrogen-free saline. At the end of week 1, 4 and 8 respectively after injection of CKLF1, 20 mice were sacrificed in every group and the cellular profiles in bronchoalveolar lavage fluid (BALF) and the pulmonary pathological changes were observed. At the end of week 1 and 4 respectively after CKLF1 injection, the neutrophils [(35.0 +/- 5.2)% and (22.9 +/- 2.2)% respectively] and lymphocytes [(34.5 +/- 2.8)% and (22.0 +/- 2.0)% respectively] in BALF of the treatment group were higher than those of the control group [neutrophils: (6.7 +/- 2.2)% and (7.0 +/- 2.4)% respectively, lymphocytes: (5.9 +/- 1.6)% and (6.1 +/- 2.7)% respectively, all P < 0.01]. Pathological studies demonstrated shedding of bronchiolar epithelium, congestion and edema in interstitial tissue and inflammatory cell infiltration in mice at 1 week after CKLF1 injection. Week 4 after CKLF1 administration, the alveolar wall was shown significantly thickened with proliferation of neutrophils, macrophages and fibroblasts as well as remarked collagen deposition in the interstitium. At the end of week 8 after CKLF1 administration, the remarkable morphological changes of the lung gradually subsided and the structure of the lung returned to normal. CKLF1 causes injury of inflammation and remodeling in airway in mice. The pulmonary pathological changes induced by a single intramuscular injection of CKLF are reversible.