Penehyclidine Hydrochloride Has the Function of Lung Protection for Acute Lung Injury in Rat Models:A Systemic Review and Meta-analysis

review the effects of hydrochloride on acute lung injury in animal models.


Introduction
Acute lung injury (ALI) is a continuum of lung changes caused by infection, collagen vascular diseases and shock. It is typically characterized by in ammatory changes, dyspnea, and refractory hypoxemia that typically presents nally as respiratory distress syndrome(ARDS), resulting in raised morbidity [1] .
Studies have found that the in ammatory mechanism is very important for ALI's occurrence and development [2][3][4] . Shock, oxidative stress and other factors can stimulate the production of upstream Tolllike receptor 4 (TLR4) factor, which can effectively start the in ammatory signal pathway [5] . After the activation of the NF-κB signal pathway, it can further induce the activation of downstream in ammatory cells, to produce the in ammatory cascade effect, so that the in ammatory process can be ampli ed and sustained. Finally, it acts on the lung tissue, leading to in ammatory injury [6,7] . Recent studies have found that the PHC has the function of lung protection and in ammation inhibitation [8,9] . Therefore, PHC is an alternative drug for the treatment of acute lung injury. However, its e cacy and mechanism have not been systematically evaluated and analyzed. Therefore, we evaluated the effect of PHC intervention through the Meta-analysis, in order to understand the therapeutic effect of PHC for acute lung injury in rat models.

Study inclusion and Exclusion criteria
inclusion criteria included1) Randomized Controlled Trial (RCT);2) animal studies; Languages: Chinese and English; 3) Languages: Chinese and English; 4) Intervention measures: The experimental group was penehyclidine hydrochloride treatment group, and the control group was the same amount of normal saline injection or other treatments alone.
Exclusion criteria included 1)incomplete experimental data and unclear experimental methods; studies published as review, case report or abstract; 2) Clinical trial research, reviews, case reports or retrospective analysis; 3) duplicate publications.

Study quality assessment
The Camaradesi list score was used independently by two authors(Shasha LUO and Dongwei Wang)to evaluate the methodological quality of trials. We discuss and resolve when there is a disagreement. The Camaradesi list scoring system(ranging from 1 to 10)includes; 1)Sample size calculation 2 Randomization process; 3 Blindedness model induction of acute lung injury; 4 Blindedness assessment; 5) Appropriate mouse model; 6)Application the anesthetics do not signi cantly improve the degree of lung injury; 7)Control the temperature; 8)Published after peer review; 9)Comply with the animal protection law; 10 Declarate potential con icts and interest.YES scores 1 point, NO does not score. Higher scores indicate exceptional methodologic qualities, and lower scores suggest poor qualities.

Data abstraction
Two authors extracted independently the included studies (research general information ,intervention and control measures, observation indicators and research results)and then checked them. The authors of the included studies were contacted if the information is not comprehensive .

Statistical analysis
All data were provided by utilizing RevMan (version 5.3, Cochrane, α=0.05.), and all including studies were tested for heterogeneity χ 2 test , the xed-effects model is used for Meta-analysis when the homogeneity is good (P>0.10, I 2 <50%); conversely,the random-effects model is used when the heterogeneity is statistically signi cant (P<0.10, I 2 ≥50%).

Results
Included studies search reading the abstract and the main text.Document retrieval processes were presented in Figure 1.
Characteristics of included studies

1.Acute lung injury model
Most of the models are induced by injecting LPS or blunt chest trauma. Among the anaesthesia they used Chloral Hydrate ip pentobarbital iv and ketamine/xylazine (iv).

2.PHC intervene
PHC dosages ranged from 0.3 mg/kg to 5 mg/kg. PHC was administered 30 -60 min before model establishment . As shown in Table 1) Table 1. data of the included studies (n = 11) PaO2/FiO2 SOD lung W/D ratio IL-6 TNF-α. Quality Evaluation 1)Sample size calculation 2 Randomization process; 3 Blindedness model induction of acute lung injury; 4 Blindedness assessment; 5) Appropriate mouse model; 6)Application the anesthetics do not signi cantly improve the degree of lung injury; 7)Control the temperature; 8)Published after peer review; 9)Comply with the animal protection law; 10 Declarate potential con icts and interest.YES scores 1 point, NO does not score. Higher scores indicate exceptional methodologic qualities, and lower scores suggest poor qualities. This included 3 articles [10][11][12] to evaluate lung function through applying Oxygenation Index. There was statistical heterogeneity between the results of each study (I 2 =93%, P<0.0001), so we used the randomeffects model. Compared with the control group, PHC affected on improving the oxygenation index of the lungs[RR=1.73, 95%CI (0.01, 3.45), P<0.01]. ( Figure A)
[MD=-1.29,95%CI(-1.94, -0.64), P<0.001]( Figure C) 4.IL-6 and TNF-α This included 6 articles [13-15, 17, 19, 20] .Due to the different measurement units among the studies, we used random effects model. The IL-6 and level of the PHC group is lower than the control group.  [21] . Therefore, it is very important for us to nd a suitable treatment for ALI. Studies have shown that ALI is closely related to in ammation [2][3][4] . That is the reason why PHC is a good choice for the treatment of ALI, which can reduce in ammation and protect the lung [8,9] . At present, the application of PHC in animal models of acute lung injury has become more popular. Our study aims to clarify the effect of PHC for acute lung injury in rat models and provides a new treatment.
This study reviews systematically the studies of acute lung injury in rat models treatment with PHC .Based on the current evidence, PHC treatment can signi cantly reduce the IL-6, TNF-α, and lung W/D ratio, it can also increase SOD and lung oxygenation index.So it has a good effect on the lungs. Although the results show that PHC is bene cial, the heterogeneity is not satisfactory. The analysis may have the following reasons: 1. the quality of the included studies are not high; 2. the dose and time of PHC are different; 3. the rat species establish are different.

Limitations of systematic reviews
Although meta-analysis shows that PHC has certain advantages in acute lung injury treatment, the metaanalysis cannot replace multi-center RTC. In addition, we found that there are large differences in the mouse model ling methods, PHC doses, and PHC inject time. That is why the heterogeneity is not satisfaction. Therefore, we need more evidence support of double-blind RCT, and then select uni ed experimental standards. Only in this way our research results can be more reliable.

Declarations
Authors' contributions Shasha Luo analyzed the data and wrote the paper. Hongbao Tan Li Chen Dongwei Wang and Rong Hua revised and edited the paper.
All authors read and approved the manuscript. The authors declare that all data were generated in-house and that no paper mill was used.

This research was supported by grant number 2020JJ8039 from
The Natural Science Foundation of Hunan Province .

Con ict of interest
The author declares that she has no con ict of interest.
Availability of data and materials Not available.
Ethics approval and consent to participate Not available. Flow chart of literature selection.