The Role Of A-FABP In Asthmatic Mice

Background: Bronchial asthma referred to asthma is a type of chronic inflammatory disease of the airways involved by many cells and cellular components such as T lymphocytes, eosinophils, airway epithelial cells and so on. It's confirmed that some inflammatory mediators can regulate the disease such as leukotrienes, prostaglandin, thromboxane and so on. Studies have shown that free fatty acids (FFA) in many cells can be metabolized bioactive substances such as leukotriene, prostaglandin, thromboxane and so on, these substances can promote inflammatory cell accumulation in the airways, cause vascular permeability and airway smooth muscle contraction.The pathogenesis of asthma is extremely complex, a number of mechanisms are not entirely clear, but the theory of Th1/Th2 cytokine imbalance has been recognized by most scholars, believed that the Th2 cytokines are mainly dominated in asthma. Recent studies have found that human bronchial epithelial cells (HBEs) express adipocyte fatty acid binding protein (A-FABP), that is adjusted by the Th2 cytokines and Th1 cytokines, The Th2 cytokines such as IL-4 and IL-13 strongly increase HBEs A-FABP expression, but the Th1 cytokines such as IFN-γdecrease the expression of A-FABP.Objective: In order to explore the effects of FFA, A-FABP in the inflammatory pathogenesis of asthma. The asthma model group have been compared with the control group through mice serum immunoglobulin E (IgE), FFA, A-FABP levels, and A-FABP expression by the immunohistochemistry in the lung tissue.Method: A total of 35 female BALB/c mice were randomly divided into two groups:asthma model group (group A) (n=20) and normal control group (group B) (n=15), The mice in asthma group were intraperitoneally sensitized with ovalbumin (OVA) adsorbed on aluminum hydroxide [Al(OH)₃] and nasally challenged with OVA. The group A of sensitization: all of the mice were injected pulsed liquid 0.2 ml (0.08% of the OVA 0.1 ml with an equal volume of 10% Al(OH)₃ mixed). Challenge: All of the mice were covered (20cm×20cm×15cm) in the solution of 10ml of 1% OVA by aerosol inhalation in the 24,25,26,27,28 days for 40 minutes every time. In the group B, same volume of physiological saline solution were sensitized and challenged instead of OVA. The general condition of all of the mice were observed, including respiration, activity, hair and so on. 48h after the last antigen stimulated blood were decapitated, opening the mice, removing the right upper lobe tissue into 4% paraformaldehyde fixative fixed for 24 hours, in order to maintain the original structure. The lung tissue was sliceed through paraffin embedded. Lung biopsy was going staining by the methods of HE, the levels of serum IgE was assayed by ELISA, in order to checking whether the success of the asthma model or not. Serum FFA level was investigated using colorimetry, A-FABP was determined in the blood by enzyme-linked immunosorbent assay(ELISA), expression of A-FABP in lung tissue was detected with immunohistochemical.Results:1 The appearance of the two groups of miceAsthma model group:All of the mice after OVA inhalation appeared irritability, shortness of breath, nose incitement, abdominal spasm, incontinence and so on, more seriously, limbs limp, dull coat. Normal control group:All of the mice after OVA inhalation appeared normal activities,smooth breathing,no irritability and so on.2 HE staining of lung biopsyThe mice of asthma model group appeared shedding of airway epithelial cells. Lots of inflammatory cells infiltrating in airway and perivascular, mainly eosinophils, which can also be found in pulmonary interstitial and alveolar.The mice of normal control group appeared complete airway epithelium, a very small amount of inflammatory cells can be found in airway and perivascular. 3 Detection of the serum levels of FFA by colorimetryThe serum FFA levels of asthma model group (2116.06±1054.94)umol/L compared with normal control group (1061.14±676.58)umol/L was significantly higher (p<0.01).4 Detection of the serum about protein expression levels of IgE, A-FABPIn the asthma model group, the levels of serum IgE and A-FABP were (22.95±1.70)ng/mL and (2.12±0.13)ng/mL, in the normal control group, the levels of serum IgE and A-FABP were (21.77±1.50)ng/mL, and (2.01±0.10)ng/mL. Further more, the levels of serum IgE and A-FABP of asthma model group compared with normal control group were significantly higher (p<0.05).5 Observation of the A-FABP in lung tissue by the immunohistochemistryThe average optical density levels of lung tissue expression of A-FABP of asthma model group(109.73±4.64) compared with normal control group(100.94±4.79) were significantly higher (p<0.01), and A-FABP expressed mainly in cell cytoplasm such as murine macrophage, airway epithelial cells, endothelial cells and so on.Conclusion:1 The levels of serum FFA and A-FABP of asthma model group compared with normal control group were significantly higher. It is shown that FFA and A-FABP are involved in the process of the pathophysiology of asthma.2 The expression of A-FABP in mice lung tissue of asthma model group was significantly enhanced, mainly in macrophages, airway epithelial cells, endothelial cells of asthmatic mice lung tissue. Which may play an important role in asthma as main target cells.3 The levels of serum FFA and A-FABP of asthma model group compared with normal control group were significantly higher, asthma and the metabolic diseases involved in FFA, A-FABP may have some relationship with each other.