The Preventive Effect Of Active Immunization With Recombinant Human HMGB1 Protein On Arthritis In Rats

Background:Rheumatoid arthritis(RA)is an inflammatory autoimmune disease that is characterized by chronic synovitis,subsequently with progressive,erosive destruction of articular tissues.High mobility group box chromosomal protein 1(HMGB1)is a conserved and ubiquitous chromosome-binding protein that can be secreted actively or released passively into the extracellular environment.It is generally accepted that extracellular HMGB1 is a potent inducer of inflammation.HMGB1 neutralizing antibody renders overt protection against structural damage and suppresses inflammatory responses in many animal models of inflammatory diseases.The aim of this study was to evaluate the effects of vaccine targeting HMGB1 in the model of RA.Methods:Using molecular biological technique,recombinant human HMGB1(rHMGB1)was expressed in Escherichia coli Rosetta using lactose as an inducer.The purified rHMGB1 was then used for active immunization in rats.Serum samples were collected after the fourth rHMGB1 immunization and measured for antibodies titers using indirect ELISA immediately.Next,collagen-induced arthritis(CIA)model was induced in rats.Rats were monitored for development of peripheral arthritis every other day from day 7 after the primary injection of bovine type II collagen.Finally,the severity of arthritis was analyzed with radiological diagnosis.The histopathologic changes of ankle of arthritic rats were determined by hematoxylin-eosin staining and safranin O-fast green staining.The level of serum pro-inflammatory cytokines was measured with commercial ELISA kits.Results:Upon CIA challenge,rats immunized with rHMGB1 showed greatly improved outcomes,including decreased clinical scores,delayed time of onset,and reduced swollen paws.Radiological and histological examinations showed that active immunization with rHMGB1 effectively protected animals from joint destruction and inflammation.Cytokine quantification showed that the rHMGB1 immunization led to a significant decrease of pro-inflammatory cytokines in the serum.In addition,our results suggested that rHMGB1 immunization has a long lasting prophylactic effect in CIA model.Conclusions:We proposed a novel hypothesis of using HMGB1 as vaccine for the prevention of RA,and demonstrated the safety and efficacy of this approach in CIA animal model.Our findings may shed light on the comprehensive treatment of severe inflammatory diseases,especially for the population who are susceptible to RA.