| Weightlessness will affect all body systems of astronauts, including the urinary system and the immune system. Disorders of the immune system resulting in decreased resistance, coupled with changes in bacterial toxicity, adhesion and invasion in the condition of microgravity, which cause a variety of infections, such as respiratory infections, intestinal infections,etc. The urethra is the site of the pathogenic bacteria to colonize. Urine retention and renal tubular injury caused by weightlessness contributes more retrograde bacterial infection and adhesion. Toll-like receptor 4(TLR4) is one of tne Toll-like receptor family, which play an important role in innate immunity against infection. It mainly expresses in the kidney as well as bladder and recognizes lipopolysaccharide of Gram-negative bacteria. It has a defensive role to prevent urinary tract bacterial infections. The researchers found that when TLR4 gene-deficient rats infected with gram-negative bacteria, the ability of urothelial cells activating cytokine will decline. This will result in reduced capacity of neutrophil chemotaxis gathered urinary tract infection site and urinary tract mucosal resistance to infection. This phenomenon also can be found in patients who suffer in asymptomatic urinary tract infection(AUB).Thus TLR4 is of great significance in immune regulation of urinary tract infections. Research on the impact of weightlessness on a kidney infection is still rare, the expression of renal TLR4 also not been investigated under simply weightlessness and weight loss when infected. This study aimed to explore what changes in pyelonephritis in rats and TLR4 expression in simulated weightlessness. Objective To investigate the influence of simulated weightlessness on the degree of inflammation in rat pyelonephritis and changes in the expression of TLR4.To analysis the relationship between changes in the expression of TLR4 and pyelonephritis degree of inflammation. Method Establishment of weightlessness model uses tail suspended. Pyelonephritis model established by injection of E. coli in the bladder through the urethra.96 female 8-week SD rats were randomly divided into control group, infection group, weightlessness group and weightlessness+infection group. Each group were randomly divided into three days, five days, seven days and two weeks sub-groups of six.The control group without any treatment. After establishing infection models, weightlessness+infection group were tail-suspended immediately. End of the experiment body weight and both kidneys were weighed. Blood was drawn for the detection of routine blood.Half kidneys fixed in 10% formalin for HE staining and immunohistochemistry to observe changes in pathology and TLR4 expression respectively. Half kidneys stored at-80 ℃ refrigerator for western bolt detect TLR4 protein expression. Results 1.Compared with the control group, the kidney weight coefficient of both weightlessness group and weightlessness+infection group were increased. Give priority to with left kidney weight coefficient(P<0.05).The difference of kidney weight coefficient between the infection 3days group or 5days group with the control group was statistically significant(P<0.05).2.The WBC level of weightlessness group and the control group was basically similar. Weightlessness+infection group of white blood cells is higher than in weightlessness group. But there was no statistically significant difference. Infection group of white blood cells compared with weightlessness+infection group difference was statistically significant in 5 days(P<0.05).3. HE dyed prompt a large number of neutrophils, lymphocytes and mononuclear cells and other inflammatory cells are infused into renal pelvis and renal interstitial and part of the renal parenchyma in infection group and weightlessness+infection group. Weightlessness group is given priority to with renal tubule pathologic change. The degree of inflammation score were significantly increased compared with the control group in infection group and weightlessness+infection group. The difference was statistically significant(P<0.05). Infection group increased more obviously. The group of 5 days, 7 days and 2 weeks group statistically significant differences in comparison with the weightlessness+infection group(P<0.05).4. Immunohistochemistry showed that infection group, loss of restructuring and infection restructuring have obvious tan particles positive expression. TLR4 is mainly expressed in renal interstitial and renal vascular endothelial cells and part of renal tubular epithelial in infection group. Tan particles mainly expressed in the distal convoluted tubule and a small number of proximal convoluted tubule and collecting duct in the weightlessness+infection group. Rat renal tubules, renal interstitial and renal blood vessels were positive expression in. weightlessness group. While control group only very little positive expression.5. Western Blot shows TLR4 protein expression were significantly increased compared with the control group in the rat kidney in weightlessness group and infection group and weightlessness+ infection group. In infection group increased most significantly. Infection 5 days and 7 days group difference was statistically significant compared with the weightlessness+ infection(P<0.05). TLR4 protein content present a tendency of increasing with the extension of weightlessness time. TLR4 protein expressed most in infection 7days group and weightlessness+ infection 7days group.Conclusion 1. Simulated weightlessness may reduce the degree of inflammation rats pyelonephritis. 2. Both inflammation and simulated weightlessness may lead to elevated TLR4 expression in rats kidney. 3. TLR4 protein expression and kidney inflammation score is not positively correlation.. |
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