| Background:Chronic periodontitis is a chronic inflammatory disease caused by bacteria,which can bring about damage to soft tissue and bone tissue of periodontal.It is one of the main reasons of tooth loss in adults.The treatment of periodontitis aims to prevent the further development of the disease,reduce symptoms such as gum inflammation,tooth looseness,weak occlusion,and restore the lost periodontal tissue as much as possible to reduce the risk of tooth loss.In addition to the methods of mechanically removing plaque bacteria,such as upper gingival cleansing,subgingival curettage,root planing,and various periodontal surgery,the medication is also an adjuvant therapy for periodontitis which is widely used in clinic,in order to sterilize and reduce inflammation as soon as possible and alleviate the symptoms of periodontitis,because it can reach the range that the equipment cannot reach.The clinical medicine for periodontitis can be systemic or local,but at the present both stages have side effects to varying degrees: when systemic antibacterials are used,the drug concentration in the periodontal pocket is relatively low,while it is easy to induce resistance drug strain and gastrointestinal reactions and etc.The drug that systematically regulates host defense response cannot effectively respond to the diversity etiology of periodontitis,so the effectis poor.Gargle drugs,which residence time is short and the drug cannot enter periodontal pocket,cannot have very satisfactory effect.The application of slow-release and controlled-release antibacterial drugs may induce the generation of drug-resistant strains in periodontal pockets.Therefore,searching for a new drug with good effect,low irritation,and avoidance of resistant strains has always been the goal of industry exploration.RNA targeted therapy is a new type of drug treatment.The mechanism of RNA therapy is to use oligonucleotides that can bind to messenger RNA through base pairing to affect the metabolic process of m RNA and the expression of related proteins.Among them,Mongersen(formerly known as GED0301)is a 21-base single-stranded phosphorothioate oligonucleotide preparation that hybridizes with Smad7 m RNA to promote its RNA degradation,so as to its protein.Smad7 is a downstream signaling molecule of TGF-?1,which can greatly promote the inflammatory response in many disease,such as colitis and periodontitis and etc.Mongersen has previously been shown to down-regulate the protein expression of Smad7 in order to alleviate Crohn's disease-like colitis in mice,which has successfully completed clinical phase II experiments.Studies have shown that periodontitis is closely related to the pathogenesis of enteritis.In previous,it was found that in the periodontitis microenvironment,Mongersen can inhibit the related downstream signaling pathways by inhibiting the expression of Smad7,and the expression of disruptive factors IL-6,TNF-?,IL-1?and INOS are decreased in vitro.Therefore,I speculate that topical application of Mongersen in periodontitis rats can also play an anti-inflammatory effect,in order to looking forward to providing new ideas for the treatment of periodontitis.Method:1.Establishment of rat periodontitis model(1)Twenty-two healthy 8-week-old male Wistar rats were selected,and 16 of them were randomly chose to construct periodontitis models using ligation in the first molar on both sides of the maxilla,and the rest of rats were controls.(2)After 6 weeks of ligation,one rat was taken from the periodontitis group and the control group,the periodontal tissue inflammation status,bleeding index,periodontal pocket depth were checked,and the degree of alveolar bone resorption was measured by Micro-CT to determine whether the periodontitis model was built successfully.2.Group and intervention(1)Fifteen periodontitis rats were randomly divided into three groups: Group C,Group N and Group M,of which Group C was periodontitis control group;group N was saline group,which were injected with 20 ?l of physiological saline by mini syringe for 2 weeks(3 times/week);group M was Mongersen group,which were injected with 20 ?l of physiological saline solution of Mongersen(25 mg / L)by mini syringe for 2 weeks(3 times/ week).(2)The inflammation and clinical indicators of periodontitis in each group were observed.Then sacrificed them all,separated the maxillary bone,and put some of them into neutral formalin fixative solution,the others freezed at-80 ?.3.Effect of Mongersen on periodontal rats(1)First,detected the alveolar bone resorption level of each group of rats by Micro-CT,and then decalcified them in neutral EDTA for 3months,and then used hematoxylin-eosin staining to detect periodontal pockets and destruction of related periodontal tissues.(2)Isolated the periodontal soft tissue around the maxillary first molar of each group,q RT-PCR was used to detect the gene expression of pro-inflammatory factors TNF-?,IL-1?,IL-6 and INOS in each group;Western-blot was used to detect the protein expression of P65,I?B-?,P-I?B-?and Smad7 in each group,in order to clarify the possibility of Mongersen can inhibit Smad7 to suppress its downstream signal pathway and then relieves inflammatory conditions.Result:1.After ligated for 6 weeks,we examined the situation in wistar rats,found that the gum tissue around the first molars on both sides of the upper jaw was redness,swelling,softness,bleedingn on probing,and the formation of deep periodontal pockets was obvious;After one rat of each group was sacrificed,Micro-CT results also showed that the alveolar bone resorption of wistar rats in the periodontitis group was obviouscompared with the control group,indicating that the periodontitis model had been successfully established.2.Two weeks after dosing,visual observation found that in group C0 which was normal control group periodontal tissues color were normal,tough texture;group N and group C had red and swollen gums and soft texture;compared with the N and C groups,M group showed lighter gum tissue,tougher texture,and less swelling.Then periodontitis-related clinical indicators of each group were detected,we found that there was no periodontal pocket formation and probing on bleeding in group C0;in group C and group N,periodontal pockets were significantly deepened and probing on bleeding was existed;compared with C and group N,in group M the periodontal exploration depth was shallow and there was no obvious probing on bleeding.3.Histological examination revealed that the gingival sulcus bottom of group C0 was near the dentino-cemental junction,no periodontal pockets were formed,and the collagen fibers in the periodontal tissues were regularly arranged;group C and N showed deep periodontal pockets and the height of alveolar bone was significantly reduced,meanwhile a wide range of irregularly arranged collagen fibers appeared;compared with group C and N,group M had shallower periodontal pockets,more regularly arranged collagen fibers,at the same time,more alveolar bone tissue is preserved.Micro-CT found that compared with group N and group C,the distance from alveolar bone crest to the dentino-cementaljunction was smaller in group M,and the difference was statistically significant.4.The results of q RT-PCR showed that the gene expressions of the pro-inflammatory factors TNF-?,IL-6,IL-1? and INOS were significantly reduced in the group M compared to group N and group C.Western-blot results showed that the protein expressions of Smad7,P-I?B-?/I?B-?,and P65 were reduced in M group compared to the N and C groups,and the results were statistically significant.Conclusion:1.Studies have found that Mongersen can effectively relieve periodontal tissue inflammation in vivo.2.Mongersen can inhibit the proinflammatory cytokines gene expression of IL-1?,IL-6,TNF-?,and INOS.3.Mongersen can inhibit the protein expression of Smad7 and related protein of P65 signaling pathway. |
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