| Severe acute pancreatitis (SAP) is a common clinical acute abdomenwith an acute onset, rapid progression, complex complications and extremelyhigh mortality. Its pathogenesis is complex and not fully understood.The extent of pancreatic necrosis is not the only factor to determine theprognosis of acute pancreatitis, the secondary infection of the pancreas whichis usually caused by bacterial translocation through the damaged intestinalmucosa also plays an important role. One study found that bacteria andendotoxin which should be in the intestines pass into the circulation syetemthrough the damaged tight junctions between the epithelial cells of theintestinal mucosa during SAP and cause enterogenic endotoxemia. Theystimulate the activated monocyte-macrophages, and then accelerate theprocess of sepsis, prompte the occurrence of SIRS which will act as a hard"second-strike" to the pancreas and other organs, even may induce andaggravate MODS and even cause death at last. Therefore, improving theintestinal barrier function may be new strategies for preventing or improvingof the SAP-induced intestinal dysfunction. Occludin, as one of the majorproteins in the tight junctions, its functional status play an important role inregulating the epithelial/endothelial permeability and maintaining the basicstructure and function of tight junctions. Occludin has become a significanttarget for clinical treatment.With the developments in glycobiology and carbohydrate chemistry, theanti-inflammatory and immunomodulatory effect of many carbohydrates havebeen found. The current study found that mannose has a series ofphysiological effects on the human body, such as anti-inflammatory effect,regulating the immune system, accelerating wound healing, inhibiting thetumor growth and metastasis, increase cancer survival rate and so on. There is no report about whether mannose has protective effect for intestinal mucosalbarrier damage induced by severe acute pancreatitis.Objective: To evaluate the changes of intestinal barrier in the early stageof SAP and the expression as well as the changes of Occludin mRNA andprotein in SAP rats’ intestinal mucosa. To explore the preventive effects ofmannose on intestinal barrier damage induced by SAP in the rat model and tryto find the possible mechanism.Methods:60SD rats were randomly divided into sham operation (SO)group, SAP group and mannose treatment (MT) group,20rats in eachgroup,then rats in each group were subdivided into two subgroups accordingto time points,6h group and12h group. SAP model was establishedby retro injection of5%sodium taurocholate into the biliary pancreatic duct.Blood, pancreas and ileum tissues were taken6or12hours after establishingthe model. After that，Hematine-Eosin staining was used to evaluate thepathological changes in pancreas and intestinum. We tested the endotoxin andD-lactate in plasma to evaluate intestinal permeability. The expression ofoccludin protein in intestinal epithelial tight junction was analyzed by WesternBlotting. The mRNA level was measured by RT-PCR．Results:(1) Pancreatic histopathologic score: in SO group, the structureof pancreatic acinar and islet tissue was clear, necrotic and hemorrhagic focicells could be found occasionally, no inflammatory cell was seen; in SAPgroup, the structure was disorganized and the interstitial edema was obvious.Acinar cell necrosis, bleeding, infiltration of inflammatory cells could be seen,the situation got worse as time passes; in MT group,the disorder degree ofpancreatic structure was lighter with regional interlobular edema. It showedfew necrotic cells and hemorrhagic foci, a small amount of inflammatory cellsinfiltrated. The pathological score of pancreas in SAP group (6h8.33±1.53;12h10.67±1.53) and MT group (6h4.33±0.58;12h6.33±1.53) weresignificantly higher than that of the SO group(6h0.67±0.58;12h2.33±1.16)(P<0.05), the score of SAP group increased more significantly (P<0.01);compared with the SAP group at each time point, the score of MT group decreased (P<0.05), the score of12h group decreased moresignificantly (P<0.01);there was no significant difference between the twosubgroups of each group in the scores (P>0.05).(2) Intestinal histopathologicscore: HE staining of SO rats mucosa showed no damage, intestinal epithelialvillus morphological was complete (6h0.67±1.15;12h0.67±0.58); Differentdegrees of damage in the intestinal mucosa of SAP group and MT group couldbe seen,.In SAP group, necrotic epithelial cell layers shedding off the tissuewith some villus loss was seen, edema in the lamina propria, telangiectasia,and congestion (6h3.33±0.58;12h3.67±0.58)could be found. Comparedwith SO group, the score was significantly higher inMT group (P<0.01). Thepathological changes in MT group (6h1.33±0.58;12h1.33±0.58)significantly reduced compared with SAP group (P <0.05), the villus wasarranged neatly, mild edema in the lamina propria and no cell necrosis wasfound; No significant difference was found between the subgroups in eachgroup（P＞0.05）.(3) The level of plasma endotoxin (mmol/L,×10-2):compared with SO group at each time point (6h12.22±0.88;12h12.65±1.44), endotoxin in SAP group, MT group significantly increased (P<0.01); compared with SAP group (6h15.00±0.67;12h17.60±1.00) at eachtime point, endotoxin in MT group (6h13.93±0.64;12h16.56±0.75)decreased (P<0.05); in each group but SO group, endotoxin in12h group wassignificantly higher than that of the6h group (P <0.01).(4)The level ofplasma D-lactate: compared with each subgroup of SO group (6h0.81±0.11;12h0.91±0.09), plasma D-lactate in SAP group (6h1.20±0.12;12h1.33±0.15) significantly increased (P<0.01); plasma D-lactate in MT group(6h0.98±0.07;12h1.10±0.12) also increased (P <0.05).Compared with SAPgroup, plasma D-lactate in MT group significantly decreased (P <0.05).Between subgroups of each group, plasma D-lactate in12h group wassignificantly higher than6h group except SO group (P <0.01).(5) OccludinmRNA expression: compared with the SO group, the expression of occludinmRNA in SAP group and the MT group significantly decreased (P <0.01),6hand12h mRNA amount in SAP group were0.51±0.06,0.80±0.05times of the SO group.6h and12h mRNA amount in MT group were0.61±0.03,0.86±0.05times of SO group;6h and12h mRNA amount in MT group were1.20±0.21,1.09±0.13times of SAP group (P<0.05). Between the two subgroupsin each group, mRNA amount in12h group was significantly higher than thatof the6h group (P <0.01) except SO group.(6) Expression of occludin protein:there was a specific protein bands at65KD area in each group. With theprogression of SAP, the occludin protein expression in intestinal tissuedecreased. The expression of the occludin protein in SAP group (6h0.23±0.02;12h0.25±0.00) significantly decreased when compared with the twosubgroups of SO group (6h0.36±0.02;12h0.36±0.01)(P<0.01); theocclude protein level in MT group (6h0.30±0.01;12h0.33±0.01) wassignificantly lower than that of the SO group (P<0.01) while being higherthan that of the SAP group (P <0.05). Comparing the two subgroups in eachgroup, a significant difference in MT group could be seen(P<0.05), nosignificant difference was found in the subgroups of the other two groups (P>0.05).Conclusions:(1) mannose can improve the pathological changes of thepancreas and intestines;(2) mannose can improve severe acute pancreatitisintestinal barrier damage and reduce the permeability of the intestinalmucosa,It also increases the expression of occludin protein and decreasesplasma D-lactic acid and endotoxin level;(3) mannose have a protective effectfor intestinal mucosal barrier injury of acute pancreatitis. As a safe, non-toxicsimple monosaccharide, mannose has a further research value in theprevention and treatment of intestinal mucosal barrier injury. |
PDF Full Text Request