Expression Of IL-8and Eotaxin In Rat Asthma Model And Dexmethasone Intervention Study

Objective：To investigate the expression of IL-8and Eotaxin in blood, Bronchoalveolar lavagefluid (BALF) and the mRNA and protein expressions of IL-8and eotaxin in lung tissueof asthma rat, and observe the effection of IL-8and Eotaxin interfered bydexamethasone.Methods：Thirty Sprague-Dawley(SD)male rats were randomly divided into three groups(10ineach), control group, asthma model group and dexamethasone treated group:(1)Asthmagroup:Rats were immunized on day1and day8by intraperitoneal injection of1mgovalbumin(OVA)in1ml of saline with100mg of aluminum hydroxide. From day15the animals were challenged with aerosolized1%OVA (in saline) for30minutes per dayfor7consecutive days.(2)DXM Group: OVA sensitized rats were injected1mg/kgDXM every day.(3)Control group: OVA and DXM was replaced with normal saline(NS). In the24hours after the last challenge, rats were killed to collect serum,bronchoalveolar lavage fluid (BALF) and lung tissue. Lung tissue is made into lungbiopsy specimens through dehydration, paraffin embedding. IL-8and Eotaxin levels inserum and BALF were detected by enzyme linked immunosorbent assay (ELISA)method. BALF cells and supernatant is separated by centrifugal separation. Total anddifferentiated leukocytes counts in bronchoalveolar lavage fluid (BALF). The lungtissue slices were stained with HE. The mRNA expressions of IL-8and Eotaxin in lungtissue were measured with RT-PCR. The protein expressions of IL-8and Eotaxin in lung tissue were measured by immunohistochemical techniques. Data for each groupwere statistically analyzed and compared.Results：1.Total white blood cell number, the percentage of eosinophils, neutrophils andlymphocytes in BALF of asthma group were increased than control group (P<0.01), thedexamethasone treated group Total white blood cell number of BALF and the cellcomposition percentage were lower to asthma group (P<0.05). The DXM treated grouptotal white blood cell number of BALF and the eosinophils percentage were higher thancontrol group (P<0.01), but the neutrophils and lymphocytes percentage no markeddifference(P>0.05).2. The IL-8and Eotaxin level of serum and BLAF in asthma group were increasedcompared with control group (P<0.05), and the DXM group were decreased comparedwith asthma group (P<0.05). The IL-8level of serum and BLAF in DXM group wereincreased compared with control group (P<0.05), but Eotaxin level no markeddifference (P>0.05).3. The mRNA and protein expressions of IL-8, Eotaxin in lung tissue of asthma groupwas higher than that of control group (P<0.01). The expressions of IL-8, Eotaxin mRNAand protein in lung tissue of DXM group was lower to asthma group (P<0.01).The expressions of IL-8, Eotaxin mRNA and protein in lung tissue of DXM group washigher to control group (P<0.05).Conclusions：IL-8and Eotaxin are involved in inflammation of asthma, and DXM may inhibit theexpression of IL-8and Eotaxin through relieve aggregation and activation of eosinophiland neutrophil to reduce inflammation.This is one mechanism of DXM to attenuateinflammation of asthma.