Study On The Changes Of Matrix Metalloproteinases In The Blood Of Acute Equine Laminitis

This experimental study the concentration tendency of metalloproteinase-1(MMP-1), matrix metalloproteinase-2(MMP-2), matrix metalloproteinase-9(MMP-9), aggrecanase-1, P38 mitogen activated protein kinase(P38 MAPK) and tumor necrosis factor-α(TNF-α) and the matrix metalloproteinase inhibitor-2(TIMP-2) of circulatory system in the model of acute laminitis induced by oligofructose, attempts to explore its role in the development of laminitis, provide technical standard and theoretical basis for early rapid diagnosis and forecasting.The 21 horses were randomly divided into experimental group(n = 12) and control group(n = 9), fed the horses in experimental group with nasogastric tube, meanwhile, fed 6L water to the horses in control group. Jugular venous blood samples were collected every 4 hs into heparinized tubes from 0 h to 72 h, and following each collection, immediately centrifuged at 300 × g for 10 mins at 4°C, and the plasma was stored at-80°C until assayed. Various biological indicators measured by Enzyme linked immunosorbent assay(Elisa). Body condition and degree of lameness were examined every time after blood collection. Sacrificed the horses when the degree reach three levels,take its hoof, and cut from the longitudinal axis of the hoof, remove its third phalanx carefully, exposed the laminitis layer, peel off the hoof laminitis layer shell. Horseshoe leaf layer itself is about 0.2 cm thick, simply cut into 2.0 cm × 2.0 cm pieces, stored in formalin solution.None of the control horses showed any clinical signs of laminitis throughout the observation period. Alternatively, out of 12 horses administered with oligofructose, clinical signs of laminitis were detected in 11 animals. Onset of Obel grade 1 lameness occurred between 8 h and 20 h post-induction and Obel grade 2 lameness was observed between 20 and 56 h. Individual horse appears the symptom of lameness. In addition, rectal temperature increased from 37.6 ± 0.2°C at 0 h to a maximum of 39.3 ± 0.8°C at 40 h, mean respiratory rate increased from 17.4 ± 1.8 to 25 ± 2.8 breaths/min, and heart rate increased from 49 ± 2.1 to 64 ± 4.2 bpm at the onset of O bel grade 2 lameness. All 12 horses in the experimental group developed profuse watery diarrhoea between 12 h and 24 h. Horse with a serious of clinical symptoms even showed significant tearing and photophobia acidosis symptoms. All the clinical symptoms improved after 60 h.The concentration of MMP-1, MMP-2, MMP-9, aggrecanase-1, P38 MAPK and TNF-α were increased, however, the concentration of TIMP-2 showed a decreased tendency. All the index number recovered to a normal level after 68 h. The concentration of MMP-1 significantly incrased at 12 h until 28 h, it peaked at 24 h, and the peak value was 37.96 ± 4.91 ng/ml, there is a significant difference(P <0.05) compared with the control group, declined at 32 h. The concentration of MMP-2 presented a wave tendency, peaked at 8 h, and the peak level was 21.44 ± 3.06 ng / ml, the difference was significant(P <0.05) compared with the control group, however, there is no significant difference compared with the control group at 12 h、28 h、32 h and 52 h. Concentration of TIMP-2 showed a downward trend from the first 8 h until 64 h, and reached the lowest value at 16 h, 36.40 ± 4.53 ng/ml,appears a significantly different(P <0.05) compared with the control group. However, there is no difference compared with the control group at 20 h、32 h、36 h、44 h、48 h and 52 h. The concentration of aggrecanase-1 was significantly increased from16 h to 56 h, the peak was appeared at 48 h, the peak level was 15.11 ± 1.50 ng/ml, the difference was significantly compared with the control group(P <0.05). The concentration of P38 MAPK increased at first and decreased later. It increased from 8h to 68 h, reached a peak at 16 h, the peak level was 46.44 ± 10.36 ng/ml, there is a significantly difference compared with the control group(P <0.05). However, there is no difference compared with the control group at 24 h, 28 h and 52 h. The concentration of TNF-α increased from 16 h to 28 h, reached a peak at 24 h, the peak level was 150.15 ± 13.19 ng/ml, there is a significantly difference compared with the control group(P <0.05).The results showed that, change trend of MMP-1, MMP-2, MMP-9, aggrecanase-1, TNF-α, and TIMP-2 concentration were consistent with the trend of the pathogenesis of acute laminitis; MMP-2 is the key indicators, plays an important role in oligofructose-induced acute laminitis model, be potential diagnostic value; and the P38 MAPK also play an important part.