Expression and significance of NLRP3 inflammasome and its downstream factors IL-1β/IL-18 in rat model of allergic rhinitis
Objective: To detect the expression and explore the role of the innate immune NLRP3 inflammasome and its downstream factors interleukin-1β (IL-1β)/ interleukin-18 (IL-18) in rat model of allergic rhinitis (AR).
Methods: Forty Sprague Dawley (SD) rats were randomly divided into control group (A group), AR model group 1 (B group), AR model group 2(C group), AR model group 3 (D group). Every group contained 10 rats. After the rats in the model group were sensitized by ovalbumin (OVA) and alum, B, C and D groups were separately stimulated with 5% OVA for 10 days, 20 days and 30 days (once a day). The control group did not add OVA in the process of sensitization and excitation. All rats were executed after excitation.Eosinophil granulocyte (EOS) infiltration were observed in nasal mucosa by hematoxylin-eosin (HE) staining, the expression of NLRP3 and cysteinyl aspartate-specific protease-1 (Caspase-1) were observed in nasal mucosa by immunohistochemical staining. The concentrations of ovalbumin specific IgE (OVA-sIgE), IL-18 and IL-1β in peripheral blood and the concentrations of IL-18 and IL-1β in nasal fluid were tested by enzyme-linked immunosorbent assay (ELISA). The data were processed by SPSS 17.0 software.
Results: EOS cell counted, the behavioral score and the concentrations of OVA-sIgE in AR model group were obviously higher than those in control group (P < 0.05), and the difference of which had statistical significance between the AR model groups (P < 0.05). The expression of NLRP3 in AR model group (The expression of NLRP3 in group of B, C and D were 48.80 ± 10.75, 71.80 ± 16.98 and 100.32 ± 13.91, respectively) were obviously higher than those in control group (17.47 ± 5.59), the difference of which had statistical significance (F = 78.399, P < 0.05). The expression of Caspase-1 in AR model group (The expression of Caspase-1 in group of B, C and D were 36.33 ± 4.71, 50.87 ± 11.18 and 73.10 ± 14.77, respectively) were obviously higher than those in control group (11.48 ± 2.70), the difference of which had statistical significance (F = 71.727, P < 0.05). The concentrations of IL-1β in AR model group [The concentrations of IL-1β in group of B, C and D were (56.46 ± 10.13), (82.37 ± 11.93), (112.01 ± 22.91) pg/ml, respectively] were obviously higher than those in control group [(38.26 ± 4.66) pg/ml], the difference of which had statistical significance (F = 51.981, P < 0.05). The concentrations of IL-18 in AR model group [The concentrations of IL-18 in group of B, C and D were (177.92 ± 23.63), (194.33 ± 20.78), (234.06 ± 31.70) pg/ml, respectively] were obviously higher than those in control group [(89.71 ± 5.56) pg/ml], the difference of which had statistical significance (F = 73.295, P < 0.05). And the difference of which had statistical significance between the AR model groups (P < 0.05). The expression of NLRP3 was significantly positively correlated with the behavioral score, the concentrations of OVA-sIgE and EOS cell counted in rat model of allergic rhinitis (r value were 0.833,0.873 and 0.868, respectively, all P < 0.01).
Conclusions: NLRP3 inflammasome and its downstream factors IL-1β/IL-18 play a role in the pathogenesis of allergic rhinitis, which may be correlated with the degree of inflammation.