| Background and ObjectiveAllergic rhinitis is referred to as “AR”.The worldwide average incidence of AR is between 10% and25%.The prevalence rate of AR is doubling every 20 years now, which seriously influence People’s Daily work, life and study. In 2001, AR had been defined as a long-term control but hardly to cure disease by the "allergic rhinitis and its impact on asthma"(ARIA) working group.So it is necessary for this disease to elucidate the pathogenesis and explore a newly diagnostic and therapeutic methods.It was reported that the main allergen of domestic allergic rhinitis was House Dust mite(HDM). A recent study found that scaffolding proteins of HDM contained chitin, which can activate NLRP3 and can transmit signal through the antigenpresenting cell.In signal transduction of house dust mite, NLRP3 can play a key role, so the research about NLRP3 in allergic rhinitis is particular important.NLRP3 is one of the most important of innate immune intracellular Nod-samplemodel receptors, which can identify a variety of endogenous danger signals(such as reactive oxygen species, ATP, etc.) and exogenous danger signals(such as uric acid crystal, aluminum hydroxide, etc.). NLRP3 is inhibited by itself in general. When NLRP3 is activated by endogenous and exogenous danger signals, NLRP3 couples with ASC and activates Caspases-1 to form a complex-protein-enzyme compound, that is NLRP3 inflammasome.The activation of Caspase-1 can facilitate the processing and secretion of IL-1β/ IL-18.IL- 1β and IL- 18 are belong to IL-1 family. IL-1β(that is former inflammation cytokine) is secreted by mononuclear macrophages, which can promote differentiation of Th17 cell and maintain production of Th17 related cytokines, also can promote the eosinophil gathering.IL-18 can promote T cells, mast cells and basophils to secret IL-4, IL- 13, which can enhance the immune response of Th2 mediated at the same time enhance the immune response of Th1 mediated.so the role of IL-18 in AR is controversial.Recent studies suggested that single nucleotide polymorphisms of NLRP3 gene was associated with aspirin-induced asthma and food-induced anaphylactic shock. Some studies showed that NLRP3 and downstream factor IL-1β, IL-18 played an important role in the formation of airway inflammation in bronchial asthma. But studies had found that there were no significant differences in airway eosinophilia, histopathologic condition,mucus production,and airway hyperresponsiveness between wild-type and NLRP3 deficient mice in either acute(alum-dependent) or chronic(alum-independent) OVA models.In this report, they did not detect a role for NLRP3 in the development of allergic airway disease in the OVA model. In addition,IL-1βand IL-18 in the lung were below the level of detection in all of the allergic airway disease model.Thus, the role of NLRP3 inflammasome and downstream inflammatory factors in allergic diseases have not been determined and has less research on allergic rhinitis,so which need further study.In this study, by detecting the expression and doing correlated study of the innate immune factor NLRP3 inflammasome(NLRP3 receptor, Caspase-1) and its downstream factors IL-18/IL-1β in rat model of allergic rhinitis, the role of NLRP3 inflammsome in the pathogenesis of allergic rhinitis and its relationship with the degree of inflammation were explored. we try to further clarify the pathogenesis of allergic rhinitis and look for a new target therapy to open up new fields. Animals and Methods1. The establishment of the rat model with allergic rhinitis 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 30days(once/day). The control group didn’t add OVA in process of Sensitization and excitation. All rats were executed after excitation. Eosinophil granulocyte(EOS) infiltration and histological changes were observed in nasal mucosa by Hematoxylin-eosin( HE) Staining, The concentrations of Ovalbumin specific Ig E(OVA-s Ig E) in peripheral blood were tested by enzymelinked immunosorbent assay(ELISA).2. The expression of NLRP3 and Caspase-1 were observed in nasal mucosa by immunohistochemical staining. The concentrations of 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). Results1. EOS cell counted, the Behavioral score and the concentrations of OVA-s Ig E in AR model group were obviously higher than those in control group(P<0.05). More nasal challenges, the concentration of the EOS cell count, the behavioral score and OVA- s Ig E were more increased, the difference of which had statistical significance between AR model groups(P < 0.05).2. 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).3. In peripheral blood :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 and 112.01±22.91, respectively)were obviously higher than those in control group(38.26±4.66), 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 and 234.06±31.70, respectively)were obviously higher than those in control group(89.71±5.56),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).4. In nasal fluid: The concentrations of IL-1β in AR model group(The concentrations of IL-1β in group of B, C and D were 35.20±3.78,55.23±9.73 and 75.16±9.70, respectively) were obviously higher than those in control group(20.42±7.02), the difference of which had statistical significance(F=89.959,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 74.93±10.63,107.72±15.90 and 125.77±19.43, respectively)were obviously higher than those in control group(39.87±6.76),the difference of which had statistical significance(F=72.603,P<0.05). And the difference of which had statistical significance between the AR model groups(P<0.05).5. By correlation test of Pearson, the concentrations of IL-1βof peripheral blood was significantly positively correlated with EOS cell counted of nasal mucosa and the concentrations of OVA-s Ig E of peripheral blood in rat model of allergic rhinitis(r value were 0.871 and 0.794,all P<0.01). The concentrations of IL-18 of peripheral blood was significantly positively correlated with EOS cell counted of nasal mucosa and the concentrations of OVA-s Ig E of peripheral blood in rat model of allergic rhinitis(r value were 0.818 and 0.828,all P<0.01).6. By correlation test of Pearson,the expression of NLRP3 was significantly positively correlated with the behavioral score, the concentrations of OVA-s Ig E and EOS cell counted in rat model of allergic rhinitis(r value were 0.833,0.873 and0.868,respectively,all P<0.01). Conclusions1. The rat model of allergic rhinitis is established successfully. More nasal challenges, the inflammation degree of Allergic rhinitis is more increased.2. NLRP3 inflammasome and its downstream factors IL-1β/IL-18 play an important role in the pathogenesis of allergic rhinitis.3. NLRP3 inflammasome and its downstream factors IL-1β/IL-18 may be correlated with the degree of inflammation. Interference with the transmission of the signal pathway of NLRP3 inflammasome can be used as a new target for the treatment of allergic rhinitis. |
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