Changes Of The Rat Anti-streptococcus Pneumoniae In Simulated Weightlessness

ObjectiveMicrogravity should have an impact on respiratory, and a certain degree damage topulmonary tissue comes out. The simulated weightlessness model was created bytail-suspension (TS). Observing the changes of rat anti-streptococcus pneumoniae insimulated weightlessness. And deeply to know lung,s pathological changes after infectionof streptococcus pneumoniaeto, study the variations of the inflammation index in blood,the cellular immune, for example: CD4+/CD8+changes, etc. To provide the basis for theaerospace medical insurance.Methods：1. The simulated microgravity and infected animal model:32health clean Wistar malerats, weight290±20g, According to the random number table divided into4groups asfollows: group A: the tail-suspension and streptococcus pneumoniae group (after tailsuspension three days, injected the streptococcus pneumoniae by trachea), group B: thetail-suspension without streptococcus pneumoniae group, group C: the unsuspended withstreptococcus pneumoniae group (injected the streptococcus pneumoniae at the sametime with tail suspension group) and group D: the unsuspended without streptococcuspneumoniae group, and each group of only8rats, We used the tail suspension,Specifically as follows: each animal cage was hanging one rat, making the rat on thebottom of the cage in front, the tail was suspended, to the horizon into about30°.Experimental environment for room temperature (22℃), night and day, cycle12h:12h, rats can free to eat and drink. After3days of tail suspension,the Streptococcuspneumoniae were injected by the tracheal intubation,0.4ml9×108CFU/ml ofAmerican Type Culture Collection (ATCC)6303, non-Streptococcus pneumoniae groupswere injected0.4ml sterile saline at the same time with the same method, and just forone time,7days for the experiment is ok.2. The bacteria’s recovery and preparation for the experiment American Type CultureCollection (ATCC)6303, bought from Shanghai Mibaolai technology Co.,LTD.According to the specification, firstly bacteria were recovery on the blood agar plate,then shifting to the blood culture bottle to increase. To get1ml in centrifugal tube, highspeed centrifugal12000r/min,5min later, abandon the liquid. To get the requiredconcentration by bacteria concentration locator.3. Blood tests, c-reactive protein (CRP) and the whole blood specimen processing: With2%sodium pentobarbital60mg/kg for anesthesia, got the sample by carotid artery or theabdominal aorta,within7hours got the results of routine blood test and CRP; to get theresults of CD4+/CD8+by flow cytometric. The method was as follows: To take50μlanticoagulant whole blood into five special test tubes: the blank tube, CD3antibodymarked tube, CD4antibody marked tube, CD8antibody marked tube, three kinds ofantibody mixed marked tube. Except the blank tube,1μl antibody added, and37℃water bathed,30minutes later, plus2ml hemolysin for10min, taken out andcentrifuged for1200r/min,5minutes later, abandoning the liquid, plus2ml PBS asbefore to wash it again, and for two times, then plus500μl PBS for flow cytometric test.4. Histopathological analysis: To take the superior lobe of right lung into4%ofpolyphophate formaldehyde, HE dyed, and study with the microscope. Results：1. The changes of rat lung The lung was obvious congestion, bleeding spots were inthe anterior lobe, and back was more than ventral side. Lung’s small veins andcapillaries expanded, the alveolars fusion increased, alveolar interstitials got sick andthe alveolar cavity deformation in group A. The surface of lung in the streptococcuspneumoniae group is uneven, in a granular pulmonary consolidation, and more obviousin the tail suspension and streptococcus pneumoniae group. Group B and C also had thechanges of alveolars fusion, alveolar interstitials sick and the cavity deformation, butless than group A;2. To get the streptococcus pneumoniae from lung tissue and BALF in the streptococcuspneumoniae group (group A and C), we can see the growth in blood agar plate as thefigures (11,12). The bacteria grew luxuriantly in group A. No bacteria in group B andD;3. Comparied with group D, neutrophils percentage rose in group A, B and C, the valueof c-reactive protein was significantly higher; amount of Lymphocytes reduce, andgroup A was the most obvious;4. Comparied with the control group, CD4+/CD8+ratio of the experiment group was low,but no statistical difference; After the experiment, weight loss for each group, and groupA was the most significant.Conclusions: Rat’s immune function is reduced in weightlessness, the ability toanti-streptococcus pneumoniae infection is decreasing, histopathological changes are more serious, reaction to inflammation is stronger, weight loss is more significant, weshould take measures for protection.