Effect Of Metalloproteinase Inhibitor On Acute Graft-Vursus-Host Disease In Mice After Bone Marrow Transplantation

Objectives: Allogeneic bone marrow transplantation (Allo-HSCT) has been a clinical treatment modality for hematopoietic disorder and hematologic malignancies. The success rate of HSCT has been steadily increased in recent years, but graft-vursus-host disease(GVHD) is still a major cause of post-transplant mortality. Matrix metalloproteinase (MMPs) are zinc proteinase that degrade compounds of the extracellular matrix (ECM) . These enzymes play a pivotal role in turnover and remodeling of the ECM during organism growth and development and the pathological destruction of tissues in disease .The aim of this study is to examine the therapeutic effect of MMPI in a murine acute GVHD model.Methods: 15 healthy C57BL/6mice were used as donors and 45 healthy BALB/C mice as recipients in this study. After being irradiated with ⁶⁰Co γ 10. 0Gy at dose rate of 10¹2cGy/min, recipients received 1×10⁷ BM cells and 5×10⁶ spleen cells from C57BL/6 donors through the tail veins. After transplantation, recipients were randomly divided into 3 group: 15 recipient mice in group A were injected intraperitoneally with MMPI 2mg/ per day during the first 14 days; 15 recipient mice in group B were injected intraperitoneally with cyclosporine A 5mg/kg per day during the first 14 days; 15 recipients mice in group C were injected with NS 0. 2ml/injectionper day during the first 14 days. In all the three groups, the fur, posture as well as survival time, etc. were observed. Pathological abnormalities of the liver, spleen, and intestine were examined to evaluate the severity of aGVHD. Complete blood cells were counted as usual. The concentration of TNF-a was measured with ELISA method.Results: 1. White blood cells (WBC) in peripheral blood of all three groups decreased to the lowest point on the day 12 after transplantation. WBC began to rise on the day 14 in groups A and B, and WBC in group C was lower than those in groups A and B on the day 14 (P<0. 05). The number of WBC in group A was also lower than that in group B on the day 14, but there was no significant difference (P>0. 05).2. platelets(PLT) in peripheral blood of all 3 groups decreased to the lowest point on the 12th day after transplantation. PLT began to rise on the 14th day in group A and B, and on the day 14, PLT in group C was lower than in group A and B (P<0. 05). There were no significant difference in group A and B(P>0. 05).3. The concentrations of TNF-a in serum of recipient mice in groups B and C increased as aGVHD became serious on day 7. In contrast, serum TNF-a was not detectable in group A.4. GVHD response appeared on the seventh day after transplantation, the deaths of mice reached its peak on the twelfth—fourteenth day in groupA, GVHD reaction appeared on the ninth day after transplantation , the deaths of mice reached its peak on the thirteenth—sixteenth day in groupB, while GVHD reaction appeared on the fifth day, the deaths of mice reached its peak on the ninth^tenth day in group C. GVHD reaction of mice in group A and B were less severe than that of mice in group C. Pathological abnormalities of the liver, spleen, and intestine were less severe in groups A and B than those in group C. In the liver from the mice in groupC, a massive infiltration of mononuclear cells and fibrosis was generallyobserved in the parenchyma.In contrast , such inflammatory changes were limited to foci at the peritortal areas in the liver from the mice in group A and B. The gut from the mice in group C exhibited dilatation, flattening of the villi.and elevation of the crypts, which are characteristics of intestinal GVHD .All these lesions were virtually absent in the mice of group A and B. The spleen of the mice in group C showed a marked lymphoid atrophy and structural disorganization. In contrast, such changes were mild in the mice of group A and B.5. The colony-forming unit- spleen (CFU-s) of group A and B were higher than that in group C and there was a significant difference. There was no significant difference between group A and group B.6. Compared with group C, the survival time of group A and B was significantly longer (P<0. 05).Conclusion: l.MMPI can relieve aGVHD response and It's the same effective as CsA in the prevention and treatment of GVHD.2. We may conclude that the blockage of the release of TNF- a contributes to the effect of MMPI on aGVHD.3. MMPI does nor have an adverse effect on hematopoitic reconstituition.