Scholarly article on topic 'Protective effects of pretreatment with Radix Paeoniae Rubra on acute lung injury induced by intestinal ischemia/reperfusion in rats'

Protective effects of pretreatment with Radix Paeoniae Rubra on acute lung injury induced by intestinal ischemia/reperfusion in rats Academic research paper on "Veterinary science"

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{"Reperfusion injury" / Intestines / "Respiratory distress syndrome / adult" / "Radix Paeoniae Rubra"}

Abstract of research paper on Veterinary science, author of scientific article — Chang Chen, Fan Zhang, Zhong-yuan XIA, Hui LIN, An-sheng MO

Abstract Objective To investigate the effect of pretreatment with Radix Paeoniae Rubra (RPR) on acute lung injury induced by intestinal ischemia/reperfusion in rats and its protective mechanism. Methods Thirty-two Wistar rats were randomly divided into four groups: Sham-operation group, ischemia/reperfusion group (I/R group), RPR-pretreatment group and hemin group. The model of intestinal ischemia/reperfusion was established by clamping the superior mesenteric artery for 1 hour followed by 2-hour reperfusion. The effect of RPR on the expression of heme oxygenase-1 (HO-1) in lung tissues was detected by immunohistochemistry and morphometry computer image analysis. Arterial blood gas analysis, lung permeability index, malondialdehyde (MDA) and superoxide dismutase (SOD) contents in lungs were measured. The histological changes of lung tissue were observed under light microscope. Results The expression of HO-1 in RPR-pretreatment group and hemin group was obviously higher than that in sham-operation group and I/R group (P < 0.01). The level of MDA and lung permeability index in RPR-pretreatment and hemin group were significantly lower than those in I/R group (P < 0.01 or P < 0.05), while the activity of SOD in RPR-pretreatment and hemin group was obviously higher than that in I/R group (P < 0.01). Under light microscope, the pathologic changes induced by I/R were significantly attenuated by RPR. Conclusion Intestinal ischemia/reperfusion may result in acute lung injury and pretreatment with RPR injection can attenuate the injury. The protective effect of RPR on the acute lung injury is related to its property of inducing HO-1 expression and inhibiting lipid peroxidation.

Academic research paper on topic "Protective effects of pretreatment with Radix Paeoniae Rubra on acute lung injury induced by intestinal ischemia/reperfusion in rats"

Protective effects of pretreatment with Radix Paeoniae Rubra on acute lung injury induced by intestinal ischemia/ reperfusion in rats

CHEN Chang ZHANG Fan ' , XIA Zhong-yuan M^'TV, UN Hui ##and MO An-sheng

Objective: To investigate the effect of pretreatment with Radix Paeoniae Rubra (RPR) on acute lung injury induced by intestinal ischemia/ reperfusion in rats and its protective mechanism.

Methods; Thirty-two Wistar rats were randomly divided into four groups; Sham-operation group, ischemia/ reperfusion group (I/R group), RPR-pretreatment group and hemin group. The model of intestinal ischemia/ reperfusion was established by clamping the superior mesenteric artery for 1 hour followed by 2-hour reperfusion. The effect of RPR on the expression of heme oxygenase-1 ( HO-1 ) in lung tissues was detected by immunohistochemistry and morphometry computer image analysis. Arterial blood gas analysis, lung permeability index, malondialdehyde (MDA) and superoxide dismutase (SOD) contents in lungs were measured. The histological changes of lung tissue were observed under light microscope.

Results: The expression of HO-1 in RPR-

Intestinal ischemia/reperfusion injury is commonly seen clinically. It can be elicited by many factors such as shock, intestinal obstruction, multiple injuries, and may result in remote vital organ damage even multiple organ failure. Among these complications, acute lung injury-induced acute respiratory distress syndrome ( ARDS) is liable to happen and the fatality is quite high. ' Heme oxygenase-1 ( HO-1 ) is a rate-limiting enzyme that catalyzes hemoglobin to produce carbon monoxide, bilirubin, and ferric ion. HO-1 is also called heat shock protein 32, and can be largely expressed when

Department of Anesthesiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China (Chen C)

Department of Anesthesiology, Renmin Hospital of Wuhan University, Wuhan 430060, China (Zhang F and Xia ZY)

Department of Cardiothoracic Surgery, People' s Hospital of Guangxi Zhuang Autonomus Region, Nanning 530021, China (Lin H and Mo AS)

* Corresponding author; Tel; 15994366417, E-mail; zfluck2002@ 163. com

pretreatment group and hemin group was obviously higher than that in sham-operation group and I/R group (P <0.01). The level of MDA and lung permeability index in RPR-pretreatment and hemin group were significantly lower than those in I/R group (P <0.01 or P<0.05), while the activity of SOD in RPR-pretreatment and hemin group was obviously higher than that in I/R group (P <0.01 ). Under light microscope, the pathologic changes induced by I/R were significantly attenuated by RPR.

ConclusionIntestinal ischemia/reperfusion may result in acute lung injury and pretreatment with RPR injection can attenuate the injury. The protective effect of RPR on the acute lung injury is related to its property of inducing HO-1 expression and inhibiting lipid peroxidation.

Key words; Reperfusion injury; Intestines; Respiratory distress syndrome, adult; Radix Paeoniae Rubra

Chin J Traumatol 2008; //(/ ): 37-41

induced by oxidative stress or other pathologic factors.24 As a result, it accelerates hemoglobin catabolism and the production of endogenous carbon monoxide and bilirubin. It has been found in recent years that HO-1 expression is involved in a series of pathophysiologic reactions of many organs and may have substantial protective effect on cells. Radix Paeoniae Rubra ( RPR) has conspicuous effects of promoting blood circulation to remove blood stasis, and can ameliorate oxygenation of the lungs and blood in ARDS.5 However the protective effect of RPR on acute lung injury induced by intestinal ischemia/reperfusion has not seen in the literature to our knowledge so far. This study aims to elucidate the effect of RPR on HO-1 expression, lung permeability, malonaldehyde ( MDA ) and peroxide dismutase ( SOD) contents, as well as lung histomorphology, on which to offer references for its clinical use.

METHODS

Materials

Thirty-two healthy male Wistar rats weighing 200250 g were provided by the Experimental Animal Centre of Medical College of Wuhan University. RPR injection was made by Zhuoyi Kangna Pharmaceutical Co. Ltd, batch number 060301, Jilin, China. Hemin was made by Sigma, USA. HO-1 polyclonal antibody was from StressGen Biotechnologies Co. USA. MDA and SOD kits were from Jiancheng Bioengineering Institute, Nanjing, China. High resolution pathologic image analysis system was made by Tongji Technology Co. Wuhan, China.

Preparation of animal model and grouping

Rats were anesthetized by peritoneal injection of 7% chlordhydrate (5 ml • kg"1 ). The model of intestinal ischemia/reperfusion was made according to the literature. 1 All animals were killed by carotid exsanguination after 2 hours of reperfusion. The animals were randomally divided into 4 groups with 8 animals in each group. ( 1) Sham-operation group, in which the superior mesenteric artery was only separated but not clamped, and the other procedures were the same as ischemia/reperfusion group. (2) Ischemia/ reperfusion ( I/R) group, in which the superior mesenteric artery was clamped for 1 hour and then reperfused for 2 hours. Saline was infused via the femoral vein. (3) RPR pretreatment group, in which at 4 hours before the superior mesenteric artery was clamped, RPR injection was pumped (30 mg • kg 1) continuously into the femoral vein for 2 hours. (4) Hemin group, in which at 18 hours before the superior mesenteric artery was clamped, hemin (75 (xmol • kg4 ) was injected intraperitoneally.

Detection of lung HO-1 content

The inferior lobe of the right lung was harvested, fixed by 4% paraform, conventionally dehydrated and imbedded with paraffin, and sliced, stained by SP immunohistochemical method, from which some slices were taken randomly and phosphate buffer saline (PBS) was used instead of HO-1 polyclonal antibody (StressGen Biotechnologies Co. USA) as negative control. Total automatic image analysis system (Tongji Technology Co. Wuhan, China) was used to analyse the samples. The average optical density ( OD) of positive expression of HO-1 was assayed, and the mean

value of 5 high power fields was defined as the representative value of the slice.

Lung permeability index assay

Blood sample of 1 ml was withdrawn from the right carotid, anticoagulated and centrifuged hypothermically to separate serum. After thoracotomy and ligation of right hilus of the lungs, we repeatedly lavaged the left lung for three times with 2 ml of saline each time and get bronchoalveolar lavage fluid. The ratio of bronchoalveolar lavage fluid to serum protein concentration was determined by Coomassie brilliant blue method. It was the lung permeability index.

Measurement of MDA and SOD in lung tissues

The middle lobe of right lung (100 mg) was homogenated and centrifuged to get supernatant. The content of MDA and SOD was measured according to the instruction of the kit.

Blood gas analysis

Blood gas analysis was done in the 1 ml of anticoagulated blood sample taken from rats ' right carotid before they were sacrificed.

Histomorphologic observation

The middle lobe of right lung was harvested and fixed in 4% paraform aldehyde solution. After gradient alcoholic dehydration, paraffin imbedding, sectioning and staining, the specimen was observed under light microscope.

Statistical analysis

The experimental data were expressed as x ± s and analysed by the variance analysis or q test with the statistical software of SPSS 10.0.

RESULTS

Effect of RPR on the expression of HO-1 in lung tissues

After immunohistochemical staining, the cytoplasm of cell that was positive for HO-1 expression exhibited dark yellow color. The expression of HO-1 in different groups is shown in Figure 1. The major HO-1-expressed sites were alveolar epithelial cells, bronchi, macrophages, and neutrophils. In comparison with sham-operation group, the highly positive expression of HO-1 in lung tissues was seen in I/R, RPR, and

hemin groups (t = 29.937, P = 0.000; i=36.637, P = 0.000; t =27.764, P= 0.000). HO-1 expression level in sham-operation group was 0. 033 ± 0. 010, 0.163 ± 0. 007 in I/R group, 0. 203 ± 0. 009 in RPR group, and 0. 208 + 0. 015 in hemin group. It was increased by 24% and 27% respectively in RPR and hemin groups from the level of I/R group(t = 9. 940, P =0.000; t= 7.613, P = 0.000).

Effect of RPR on lung permeability index, MDA and SOD contents

The lung permeability index and MDA content were significantly higher but SOD was significantly lower in I/R group than sham-operation group ( t =

12.939, P = 0.000; t = 6. 557, P=0.000; t = 6.678, P =0.000). The lung permeability index and MDA content were significantly lower but SOD was significantly higher in RPR and hemin groups than I/R group (i =5.225, P = 0.000; «=5.661, P=0.000; Table 1).

Effects of RPR on arterial blood gas

Arterial pH values were similar among groups. Pa02 and PaC02 were significantly reduced after ischemia/reperfusion as compared with sham-operation group (t = 12. 848, P = 0. 000; t = 4. 615, P = 0.000), but in hemin and RPR groups, they were significantly higher than I/R group ( Table 2 ) .

Fig. 1. Immunohistochemical assay of HO-1. A: There was nearly no positive expression in lung tissues of sham-operation group( x 400). B: Positive expression (dark yellow staining) for HO-1 was seen in alveolar macrophages and intracytoplasm of inflammatory cells ( x200). C: High positive expression (dark yellow staining) for HO-1 was seen in RPR group ( x400).

Fig.2. Lung histomorphological changes (HE). A; There was no evident pathological changes in sham-operation group ( x400). B: In I/R group, lung tissue edema, angiotelectasis and inflammatory cell infiltration; bleeding and protein exudant in the alveolar space, accompanied by local atelectasis and emphysema ( x 200 ). C ; A small number of lymphocytes infiltration was seen in some alveoli and around vascular wall in RPR group, but the impaired extent was milder than that of I/R group ( x 200 ).

Table 1. Influence of RPR on lung permeability index, MDA and SOD contents (x±s, n= 8)

Table 2. Comparison of arterial blood gas analysis among groups(x ±s, n= 8)

Groups Lung permeability index ( x 10 ) MDA( p,moI/g) SOD( U/mg) Groups pHU Pa02(mm Hg) PaC02 ( mm Hg)

Sham- 1.01 ±0.29 operation 18.62 ±3.27 112.81 ±20.25 Sham-operation 7.41 ±0.05 100.0 ±0.9 37.5 ±3.5

I/R 3.96 ±0.58* * 46.43 ±11.54** 50.78 ±16.74** I/R 7.47 ±0.06 80.2 ±4. 1 * 30.6 ±2.3*

RPR 2. 20 ±0. 31 *A 22.11 ±5.61 *AA 85.47 ±8.51 **AA RPR 7.44 ±0.04 94.8 ±3.4A 33.3 ±4.6A

Hemin 2.48 ±0. 37 *A 18.01 ±3.40*AA 94.09 ± 13.71 *AA Hemin 7.45 ±0.05 93.5 ±3.9A 35.7 ±5. 3 A

* P <0.05, * * P <0.01, compared with sham-operation group. AP <0.05 , AAP<0.01, compared with I/R group.

*P<0.01, compared with sham-operation group. AP<0.05, compared with I/R group.

Histomorphologic changes of the lungs

There was no obvious pathological alteration in sham-operation group. In I/R group however, lung tissue edema, telangiectasis, inflammatory cell infiltration (most of them were neutrophils) were seen. There were bleeding and protein exudant in the alveolar space, accompanied by local atelectasis and emphysema. In RPR group, a small number of lymphocytes were infiltrated in some alveoli or around the vessel wall. The damaged extent was milder as compared with I/R group.

DISCUSSION

Intestinal ischemia/reperfusion injury can induce remote organ impairment. After intestinal ischemia/ reperfusion injury, the death of enterocytes, breakdown of intestinal mucous membrane barrier, and permeability increase may accelerate endotoxin absorbance and bacterial translocation, and these will contribute to the release of cytokines and inflammatory mediators and further induce systematic inflammatory reaction.6,7 In this situation, a large number of oxygen free radicals will emerge. They can not only aggravate gastrointestinal tract damage, but also result in remote organ insult, in which the liver is the most vulnerable organ to injury. In this experiment, we found lung edema, telangiectasis, and inflammatory cell infiltration after ischemia/reperfusion. There were bleeding and protein exudant in the alveolar space. Pa02 and PaC02 in the arterial blood dropped and lung permeability index rose. These findings that are identical to the results of previous studies8'10 demonstrate that intestinal ischemia for 1 hour and reperfusion for 2 hours will induce the pathological manifestations of typical acute lung injury in rats.

It is confirmed that HO-1 is an anti-injury heat-shock protein and takes part in the stress protection of ischemia/reperfusion. Adriacin-pretreated HO-1 has a protective effect on lung injury elicited by intestinal ischemia for 120 minutes and reperfusion for 120 minutes. This effect will be attenuated when HO-1 inhibitor, zinc protoporphyrin, is administrated, suggesting that the functional amelioration of lung injury may directly or indirectly be induced by HO-1. 1 Many studies have found that overexpression of HO-1 has a protective effect on ischemia/reperfusion injury in the animal models of heart, liver, intestine, or

muscular flap transplantations. 11-13 The protective properties need further study.

RPR is a traditional Chinese medicine, having the function of promoting blood circulation to remove blood stasis. Modern pharmacological study clarifies that its major component, propyl gallate, has a conspicuous biological effect. It possesses many kinds of pharmacological activities, such as powerful antioxidation, anti-free radical, anti-inflammatory functions, blocking lipoxidase activity, enhancing cAMP level, inhibiting thromboxan B2 synthesis and platelet aggregation. It can also ameliorate the microcirculation of ischemic tissues, raise the tolerance to ischemia and anoxemia, diminish pulmonary vascular resistance, ameliorate myocardial function by abating afterload and increasing cardiac output. Reddan et al14 consider PG is an analogue of SOD, and it can prevent lens epithelial cell from hydrogen peroxide insult. Shanker et al15 demonstrate that PG, as a free radical scavenger, can attenuate the production of reactive oxygen species of cerebral astrocytes elicited by dimethylmercury. Overseas studies exhibit that RPR contains an effective component, 1,2,3,4, 6-five-O-glucogallin ( PGG) , which has the function of antioxidant, anti-inducing mutation, and antiproliferation. When N2A cells are exposed to PGG, they can induce the stable expression of HO-1 mRNA and heme oxygenase activation in a time- and dose-dependent manner. 16

Our study found that as preventive administration of RPR injection and hemin, lung HO-1 expression would increase, lung MDA content decrease, SOD activity rise, lung oxygenation index was greatly improved and pathological changes were abated, suggesting that HO-1 can retard the pathological changes of the lung and is a substantial protective factor during ischemia/reperfusion. The mechanism that preventive use of RPR has a marked protection effect against acute lungs injury during ischemia/ reperfusion is considered as follows. ( 1 ) RPR can directly induce HO-1 mRNA expression, upregulate HO-1 expression and activity. (2) It can raise the activities of SOD, glutathione peroxidase, and hydrogen peroxidase, and reduce the production of oxygen free radicals, by which to abate the lipid peroxidation reaction of lung tissues. (3) It may relate to such properties of RPR as dilating coronary vessels,

increasing coronary flow, improving cardiac function, and increasing cardiac output. In addition, RPR can inhibit endogenous factor XH activation, retard the tendency to high coagulation and microthrombosis, and ameliorate lung microcirculation.

Therefore, we deem that preventive use of RPR can greatly mitigate acute lung injury elicited by ischemia/reperfusion, attenuate lung pathological changes. Accordingly it will ameliorate lung function, raise oxygen delivery ability and diminish hypoxic state of the body.

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(Received May 25, 2007) Edited by SONG Shuang-ming