Expression And Clinical Significance Of Soluble Tim-3 In Different Diseases

Background:Appropriate immune and inflammatory responses are protective defense against damage and stimuli, and are beneficial to maintaining the homeostasis of our body.However, excessive responses lead to tissue damage or dysfunction, even tumor and autoimmunity diseases. It is important for us to timely check immune response to keep the body healthy.In our bodies, there are some biological “makers” which are used to check or follow elevate immune and inflammatory responses and metabolic status and provide ways for diseases diagnosis and treatment. For example, the concentrations of C-reactive Protein(CRP),Anti-nuclear Antibody(ANA),urea、creatinine and glucose in the serum are high in patients with acute inflammation, autoimmunity diseases, renal insufficiency and diabetes, respectively. These biological makers,which can assess the severity and prognosis of the diseases, are key auxiliary means to the clinical diagnosis and treatment. With the development of scientific research, especially basic medical science, some new biological makers are being investigated and used.Tim-3 is a novel checkpoint molecular initially expressed on the activated Th1 cells. By binding to its ligand, Galectin-9, Tim-3 leads to the apoptosis of T cells and results in immune tolerance. Recent data demonstrated that the high expression of Tim-3 on the T cells and innate immune cells are intimately correlated with many immunity-related diseases. In addition, more investigations are focusing on the mechanisms of Tim-3 mediated immune tolerance and on the applications of Tim-3against inflammation and tumors. In vivo, there are membrane binding Tim-3 and soluble form of Tim-3, and the possible sources of soluble Tim-3 are selective gene splicing of Tim-3 or the shedding of membrane Tim-3. Up to now, people have had a good knowledge of membrane Tim-3, but little is known about soluble Tim-3.We have focused on the regulating mechanisms of Tim-3 for several years and developed a series of fused protein and antibodies on Tim-3.Based on the findings that Tim-3 plays key roles in promoting the polarization of macrophage and enhancing immune and inflammatory responses, we particulate that soluble Tim-3 in serum may be involved in regulating the immune and inflammatory reactions.In some serum samples of patients, we observed there may be a correlation between the concentration of soluble Tim-3 and the severity of diseases. While there are some reports about the soluble Tim-3 has potential roles in monitoring the process of diseases, but they are still some questions in research field concerning the application values of soluble Tim-3.So we will further explore the expression and clinical significance of soluble Tim-3 in different diseases to see whether it can be used as another biological markers in monitoring the development of diseases.Objective:1. Explore the expression of soluble Tim-3 in the serum of patients with acute injury systemic lupus erythematosus( SLE), Chronic Kidney Diseases(CKD),Rheumatoid arthritis(RA)and tumor, and then analyze the relations between the concentration of soluble Tim-3 and C reactive protein(CRP).2. Verify the correlation between the concentration of soluble Tim-3 and disease progression in patients with CKD and SLE through correlation analysis, and then confirm the possibility of using soluble Tim-3 as a clinical biological marker in monitoring progression.3. Preliminarily investigate the source of soluble Tim-3 and the mechanisms by which soluble Tim-3 regulates inflammation responses..Methods and Results:1. The expression of soluble Tim-3 in serum of different kinds of diseases and it’s relations with inflammatory responses1.1To observe the expression of soluble Tim-3 in different kinds of patients we collect 188 patients with chronic or acute inflammation from March 2014 to January 2016 in 304 hospital and then classify them into different groups including RA(41 patients),SLE(23 patients),CKD(66 patients),trauma(17patients),diabetes(10 patients),gastric carcinoma(15 patients),infection(16 patients)and healthy subject(20).Collect the serum and peripheral blood cells from above-mentioned patients on an empty stomach, and then determine the serum concentration of soluble Tim-3 by ELISA and the expression of Tim-3m RNA in peripheral blood cells by RT-PCR, respectively. The results demonstrated that,compared to the healthy subjects, the expression of soluble Tim-3 is significantly decreased in patients with acute injury, significantly increased in patients with chronic inflammation and tumor. Moreover, the change of Tim-3 is consistent at the level of m RNA and protein. These results show that the soluble Tim-3 can be a biological marker indicating the process of inflammatory responses.1.2 Comparative analysis between soluble Tim-3 and inflammation marker CRPThe degree of CRP is an important biological marker reflecting the severity of inflammation, and we found that the increase of CRP has no significant correlation with the decrease of soluble Tim-3 in acute inflammation. We also observed the slight but not significant increase of CRP and obvious increase of soluble Tim-3 in chronic inflammatory diseases SLE and RA, which indicates that the soluble Tim-3has more potential than CRP to be a biological marker reflecting the progression of chronic inflammation.2. Analysis of the roles of soluble Tim-3 in following the progression of patients with CKD and SLE.Previous study shows the obvious increase of soluble Tim-3 in some chronic inflammation. To further explore the clinic significance of soluble Tim-3,we observed the correlation between soluble Tim-3 and progression of diseases in immunity-related diseases, CKD and SLE. The results shows that the degree of soluble Tim-3 in serum is much higher than healthy subjects, positive correlation with renal injury and negative correlation with e GFR,which demonstrates that the degree of soluble Tim-3 is related to the progression of CKD. Besides, there is a correlation between the degree of soluble Tim-3 and biological markers concerning the severity of SLE. So these results demonstrated that the Tim-3 can be a new biological indicator monitoring the progression of CKD and SLE.3. The source and effect of soluble Tim-3As previously mentioned, the source of soluble Tim-3 may come from the upregulation of gene expression or the enhancement of shedding from membrane Tim-3.The previous study found the upregulation of Tim-3 at the level of protein and mRNA is synchronous in patients with SLE, which indicates that the soluble Tim-3 may come from the elevating expression of m RNA. In addition, recent study shows the sheddase of ADAM10 and ADAM17 may be involved in the shedding of soluble Tim-3 from membrane. So we detected the expression of ADAM10 and ADAM17 and found these two sheddases are positively correlated with the degree of soluble Tim-3,which shows that ADAM10 and ADAM17 may also be involved in the upregulation of soluble Tim-3 in patients. Furthermore, we also observed the up-regulation of inflammatory mediators such as IL-18 and IL-1β along with the increase of soluble Tim-3,which indicates soluble Tim-3 may lead to inflammatory responses.Conclusions:1. The degree of soluble Tim-3 is decreased in acute injury while increased in chronic inflammation.The soluble Tim-3 showed potential value better than CRP to be an indicator reflecting the progression of chronic inflammation2. The soluble Tim-3 shows potential value as a biomarker to monitor the progression of CKD and SLE3. The soluble Tim-3 may come from both the upregulated expression of mRNA and the enhancement of shedding of membrane Tim-3 and may promote inflammation by increasing the expression of inflammasome related cytokines.