A Study On The Process Mechanisms Of Rat's Lung Tissues Of Type 2 DM And On The Intervention Of Rosiglitazone

In the early 1970's, Schuyler and some others initially had put forward that the lung may be one of the target organs of diabetes mellitus (DM). With the further study of complication of DM, increasingly more attention has been paid to the damage of DM to the lung. The alteration of the lung in DM showed non-specificity metergasis, such as the decrease of the diffusion function of the lung and the appearance of more pulmonary fibrosis and concurrent infection etc. Both type 1 and 2 diabetics have restriction, obstruction or mixed ventilatory disorder and diffusion disorder, but the mechanism of generate is still dimness. The study in the past few years indicated that nuclear factor kappa B (NF-κB)and inhibitor-IκB signaling pathway played important role in the generation and development of DM and its complication.Objectives:To study the relationship between damage to lung in DM and NF-κB / inhibitor-IκB signaling pathway; therefore to prefer that the activation of NF-κB signaling pathway may be one pathogenesis of DM; and, simultaneously, provide experimental data for therapying damage to lung in DM through observing the intervention of thiazolidinediones-rosiglitazone which can decrease glucose and have anti-inflammatory effect.Methods:The experimental type 2 diabetic rats were yielded by injecting streptozotocin (STZ) and feeding with high fat and glucose food, then we observed the alteration of morphology in the lung of rats in the control group, the DM group and the rosiglitazone group during 12w and 24w respectively to ascertain the state of modeling, and observed the collagen accumulation of lung by masson trichrome staining and alteration of NF-κB P₆₅, IκBα, TGF-β₁ and PKC in lung by immunohistochemistry .Results:1. Symptoms and Signs: The diabetic rats occurred polyuria, polydipsia, polyphagia in a week after injecting STZ, especially in 12w. Along with the extension of disease, symptoms aboved worsened, together with trichoxerosis, faint politure, blunt response and decreased activity. Compaired with the control group, there was no statistical difference in the two groups although the body weight of diabetic rats decreased slightly. Also there was no obvious amendment of symptoms above-mentioned in the rosiglitazone group.2. The changes of biochemistry markers: The levels of plasma glucose, fast insulin and triglyceride in the DM group at 12th week were higher than those in control group(p<0.05). The levels of triglyceride and cholesterol were significantly increased in DM group at the end of 24th week, compared with control rats and diabetic rats at the end of 12th week(p<0.01). The fast plasma glucose, fast insulin were high in two groups of diabetic rats and the difference of two groups was not significant. Compaired with those in the DM group, fast insulin and cholesterol in the rosiglitazone group decreased significantly(p<0.05), but plasma glucose and triglyceride decreased slightly.3. Hematoxylin and eosin staining: Alveoli of lung composed with monolayer alveolar epithelium and basilemma and distributed uniformity, there were jot connective tissue between consecutive alveoli of lung of the control in the light microscop. The organism structure of lung in the DM rats distributed deranged, bronchus wall and alveolar wall were thicken, alveolar epithelial cells were indistinct, alveoli of lung were atrophied and collapsed. There were more interstitial substances, extracellular matrixes circum-vasa and desmocytes companied with inflammatory cell infiltration. Pathological alterations above-mentioned in the DM rats were more significant at 24w. The pathological changes of organism in lung lessened obviously than the DM group, but the organism structure of lung hasn't recovered to normal.4. Masson staining: There was jot fibroglia fibrilses between interstitial substances, extracellular matrixes circum-vasa in the control. At 12w, fibroglia fibrilses between interstitial substances, circum-vasa increased and distributed deranged, facio-density of collagen of lung in the DM was 0.08±0.02, was much higher than that of control in the corresponding time period (0.05±0.06,p<0.01). With the extension of course of DM, changes above-mentioned aggratated, the organism structure of lung distributed deranged, alveoli of lung were atrophied at 24w, even replaced by fibroglia fibrils. Facio- density of collagen of lung in the DM at 24w was 0.27±0.03,was higher obviously than that of the control(0.08±0.03,p<0.01); compared with that at 12w, facio-density of collagen of lung in the DM at 24w increased obviously as well(p<0.01). Facio-density of collagen of lung in the rosiglitazone was 0.16±0.01, accumulation of collagen of lung tissues abatemented significantly to normal. Results of comparation between the control group, DM group at 24w and rosiglitazone group showed that there was significant difference respectively(p<0.01).5. Immunohistochemistry5.1 The expression of NF-κB P₆₅ in tissue of lung: The positive expression of NF-κB P₆₅ in tissue of lung in the DM group increased slightly and was stained shallow at 12w, the staining optical density value was 0.20±0.01 which was larger than that of the control in the corresponding time period 0.12±0.02(p<0.01);the positive staining optical density value at 24w was 0.35±0.06 which was larger than that of 12w DM and that of the control in the corresponding time period(0.17±0.03,p<0.05); The positive expression of NF-κB P₆₅ in tissue of lung in the rosiglitazone group was 0.25±0.05, stained shallow, which was more than that of the control but not so many as 24w DM. Results of comparison between the control group, DM group at 24w and rosiglitazone group showed that there was significant difference respectively(p<0.01).5.2 The expression of IκBαin tissue of lung: The positive expression of IκBαin tissue of lung in the DM group increased slightly and was stained shallow at 12w, the staining optical density value was 0.29±0.002 which was larger than that of the control in the corresponding time period 0.08±0.02 (p<0.01);the positive staining optical density value at 24w was 0.36±0.03 which was larger than that of 12w DM and that of the control in the corresponding time period(0.22±0.01,p<0.05), the positive expression increased obviously, buffy particles was fairly deep and distributed gobbetly in nuclear, in endochylema buffy particles was fairly deep too; The positive expression of IκBαin tissue of lung in the rosiglitazone group was 0.26±0.02, which was more than that of the control but not so many as 24w DM. Results of comparation between the control group, DM group at 24w and rosiglitazone group showed that there was significant difference respectively(p<0.05).5.3 The expression of TGF-β₁ in tissue of lung: The positive expression of TGF-β₁ in tissue of lung in the DM group increased slightly and was stained shallow at 12w, the staining optical density value was 0.22±0.02 which was larger than that of the control in the corresponding time period 0.14±0.01(p<0.01);the positive staining optical density value at 24w was 0.33±0.02 which was larger than that of 12w DM and that of the control in the corresponding time period(0.16±0.02, p<0.01), the positive expression increased obviously, buffy particles was fairly deep and distributed gobbetly in nuclear; The positive expression of TGF-β1 in tissue of lung in the rosiglitazone group was 0.23±0.02, which was more than that of the control but not so many as 24w DM. Results of comparation between the control group, DM group at 24w and the rosiglitazone group showed that there was significant difference respectively(p<0.01).5.4 The expression of PKC in tissue of lung: There were faint positive expression of PKC in alveolar epithelium, bronchus epithelium cytolemma and cytoplasm in the control. The expression of PKC in tissue of lung in the DM group increased obviously and was stained to deepen, that expression in alveolar epithelium increased, furthermore, there was more positive expression in cytolemma. The positive staining area increased, the optical density value was 0.25±0.05 which was larger than that of the control in the corresponding time period 0.15±0.03(p<0.05) at 12w;the positive staining optical density value at 24w was 0.32±0.03 which was larger than that of the control in the corresponding time period(0.18±0.01, p<0.05). The number of positive cells of PKC in the rosiglitazone group decreased(0.21±0.03). Results of comparison between the control group, DM group at 24w and rosiglitazone group showed that there was significant difference respectively(p< 0.01).6. The associativity analysis between NF-κB P₆₅ and IκBαThe expression of NF-κB P₆₅ has positive correlation with that of IκBαrate significantly(r=0.8401, p<0.01).7. The associativity analysis between NF-κB P₆₅ and TGF-β₁ The expression of NF-κB P₆₅ has positive correlation with that of TGF-β₁ rate significantly(r=0.8795, p<0.01).8. The associativity analysis between NF-κB P₆₅ and PKC The expression of NF-κB P₆₅ has positive correlation with that of PKC rate significantly(r=0.7939, p<0.01).Conclusions:1 The model of type 2 diabetes could be made by injecting streptozotocin(STZ, 30mg\kg) and fed with high and glucose food. The morphologic changes and collagen accumulation were observed in diabetic lung, which indicated the lung could be injured in type 2 DM rats.2 The expression of NF-κB P₆₅, IκBαand TGF-β₁ increased and the activity of PKC enhanced in tissue of lung in type 2 DM rats. With the development of pathogen tic condition, those expression increased increasingly obviously, which indicated that in the state of high glucose with DM, the activity of PKC enhanced to irritate NF-κB and generate transcription in nuclear, then the expression increased, meanwhile, the degradation of inhibitor- IκBαincreased, and the expression of TGF-β₁ increased; furthermore, there were positive correlation between NF-κB P₆₅ and IκBα,TGF-β₁ and PKC, which hints that the signaling pathway of NF-κB/IκB participate in the occurrence and development in process of lung in DM, and may be one of the mechanisms of injury of lungs.3 The pathological alteration of tissue in lung in rosiglitazone group rats mitigated obviously, accumulation of collagen abatemented, the expression of NF-κB P₆₅, IκBα, TGF-β₁ and PKC of lung tissues were inhibited, which indicated the intervention of rosiglitazone could mitigate the degree of process of lung tissues in DM.