The Role And Mechanism Of Local Immune Microenvironment Regulation In Refractory Wound Healing Of Type Ⅰ Diabetes

Background:Type 1 diabetes(T1D)is an autoimmune disease.Its main characteristics are the inflammatory infiltration of pancreatic islets and the destruction of pancreaticβ-cell structure by autoreactive cells.The incidence of type 1 diabetes in the world is high,and it is no exception in China.The incidence of type 1 diabetes is estimated that 1.01 get sick in per100,000 people.The new type 1 diabetes is mainly in adults,but in the past 20 years,the incidence of type 1 diabetes in people under 15 has also increased rapidly.Although various treatments to improve the effect of the patients,with the lengthened patients survival time lead to the duration of diabetes,the effects of diabetes patients with refractory wounds on patients quality of life are more and more obvious.the effective treatment of refractory wounds in diabetic patients has become a focus of basic and clinical research.T cell-mediated immunity is the main cause of inflammation-relatedβ-cell death.The reason for the prolonged and difficult healing of refractory wounds caused by T1D is related to the continuous infiltration of immune cells such as macrophages and T cells in the wound.It is also closely related to abnormal innate immunity and acquired immune response.Curcumin is a phenolic substance extracted from plant rhizomes.It has a variety of biological activities including anti-inflammatory and has a good prospect for clinical medicinal development.In more than ten years of application of curcumin in the treatment of chronic diseases,especially in the research of improving diabetes,related experiments have received good results,and curcumin has the characteristics of minor adverse reactions to make its anti-inflammatory related research a hot spot.Researches have shown that curcumin can inhibit the metastasis of macrophages,reduce the secretion of pro-inflammatory factors such as tumor necrosis factor alpha(TNF-α),increase tissue insulin sensitivity and prevent the destruction of islet cells.Curcumin can also effectively reduce the infiltration of macrophages in adipose tissue and improve the condition of innate immune cells in chronic disease tissues.CD26 molecule is the surface antigen of T cells,also known as DPP-4.It participates in the maturation and activation and immune effect process of T cell.It plays a very important role in many immune diseases(autoimmune diseases and inflammatory infectious diseases such as rheumatoid arthritis and bronchial asthma).It can mediate humans CD8~+T cell activation through granzyme B,TNF-αand interferonγ.It can also mediate NF-κB to trigger the proliferation,activation and differentiation of CD4~+T cells.However,in Treg cells,the expression of CD26 is low.CD26-related inhibitors such as linagliptin are first-line hypoglycemic agent in clinical applications,it inhibits CD26 to effectively reduce the inactivation of glucagon-like peptide-1,thereby improving blood sugar control in humans.However,in recent studies,it has been found that CD26 inhibitors have the effect of reducing acquired immune cells such as CD8~+T cells in adipose tissue in addition to their hypoglycemic mechanism.In the local immune microenvironment of refractory wounds,the high inflammatory response produced by the continuous infiltration of macrophages and other innate immune cells is the main reason for the prolonged unhealing of refractory wounds.However,the reduction in the accumulation and activation of acquired immune cells such as Treg cells in the wound can also lead to delayed wound healing.Therefore,when considering the regulation of the immune microenvironment of refractory wounds for treatment,a two-pronged approach should be taken,and the adjustment of innate immunity and adaptive immunity should be considered to achieve better therapeutic effects.Objective:Aiming at the unique local microenvironment of autoimmune disease T1D wounds,this research constructed a diabetic wound model based on type 1 diabetic mice,and encapsulated curcumin and CD26 inhibitors with a degradable amino acid hydrogel.By separately regulating innate immunity and acquired immunity,it can play the role of synergistically regulating the local immune microenvironment of diabetic wounds and achieve the ultimate goal of promoting the healing of diabetic wounds.Methods:(1)Prepare a hydrogel suitable for diabetic wounds,and mix linagliptin and curcumin in the hydrogel to construct a hydrogel system with controlled release of linagliptin and curcumin.(2)Based on BALB/c mice,intraperitoneal injection of streptozotocin(STZ)was used to construct a type 1 diabetic mouse model,and on this basis,chronic wounds on the back of the mice were made to simulate the refractory treatment of diabetic patients Wounds of sexual ulcers.(3)A hydrogel system with controlled release of two drugs is used for the treatment of type1 diabetes wounds,and the wound healing is clarified by general appearance,scanning electron microscopy,HE staining,histology and other methods.(4)Compared with the control group,in the mouse serum on day 14,the content of the anti-inflammatory factor IL-4 in the experimental group loaded with the two drugs was significantly increased,while the content of the pro-inflammatory factors IL-6,TNF and IFN-γhave different degrees of decline.(5)Use flow cytometry and CBA kit to detect the immune microenvironment at different time points in the wound area to clarify the mechanism.Result:(1)On the 14th day after treatment,the unclosed area of the wound in the hydrogel group containing both CD26 inhibitors and curcumin was smaller,and the collagen deposition at the wound was significantly increased.The healing is good.(2)Changes in innate immunity:The number of M1 macrophages in the hydrogel group containing both CD26 inhibitors and curcumin was significantly reduced on the 7th day after treatment,and the number of M2 macrophages increased.(3)Changes in acquired immunity:In the hydrogel group containing both CD26 inhibitors and curcumin,CD8~+T cells decreased and Treg cells increased on the seventh day.(4)Compared with the single application,the two drugs have a synergistic effect.Conclusion:Drugs such as curcumin and linagliptin can change the distribution of immune cells such as macrophages and T cells,and regulate the local immune microenvironment of diabetic wounds.It can also promote collagen deposition on the wound surface and accelerate wound closure,but its specific mechanism needs to be further explored and optimized.