[Pulmonary Vascular Remodeling Characteristics of Pulmonary Arterial Hypertension Mouse Model Induced by Left Pneumonectomy and Jugular Vein Injection of Monocrotaline Pyrrole]

Objective

To compare and investigate the differences and characteristics of pulmonary vascular remodeling in three mouse models of pulmonary arterial hypertension (PAH) constructed by left pneumonectomy, jugular vein injection of monocrotaline pyrrole, and left pneumonectomy combined with jugular vein injection of monocrotaline pyrrole, to explore for a PAH animal model that approximates the clinical pathogenesis of PAH, and to create a model that will provide sound basis for thorough investigation into the pathogenesis of severe PAH.

Methods

59 male C57/BL mice (10-12 weeks, 24-30 g) were randomized into four groups, a control group ( n=9), a group that had left pneumonectomy (PE, n=15), a group that had jugular vein injection of monocrotaline pyrrole (MCTP, n=15), and the last group that had left pneumonectomy combined with jugular injection of monocrotaline pyrrole (P+M, n=20). To evaluate the effect of modeling and the characteristics of pulmonary vascular remodeling, hemodynamic and morphological parameters, including right ventricular systolic pressure (RVSP), right ventricle/(left ventricle plus septum) (RV/LV+S), percent of wall thickness in the pulmonary artery (WT%), muscularization of non-muscular arteries, neointima formation, and vascular obstruction score (VOS), were measured in each group.

Results

1) Compared with those of the control group, the RVSP, RV/LV+S, WT%, and the degree of small pulmonary arteries muscularization in the P+M group were significantly increased ( P<0.01). The MCTP group had just slightly higher findings for these indicators ( P<0.05), while no significant change in these indicators was observed in the PE group ( P>0.05). 2) Neointima formation in the acinus pulmonary arteries, which caused obvious stenosis of the lumen, was observed in the P+M group, the VOS being 1.25±0.80 points ( P<0.001). In contrast, neointima formation was not observed in the MCTP group or the PE groups, the VOS being 0 point ( P>0.05).

Conclusion

Left pneumonectomy combined with jugular intravenous injection of MCTP could induce severe PAH formation in mouse. The model provides a good simulation of neointima formation, the characteristic pathological change of clinical severe PAH.

[Preliminary Experimental Study of Establishing a Lung Development Model with Specific Pathogen Free Preterm Pigs]

OBJECTIVE

To determine the best time for conducting cesarean section for the establishment of an animal model of lung development with specific pathogen free (SPF) preterm Bama minipigs under the condition of not making medical interventions such as hyperoxia, mechanical ventilation, or medication.

METHODS

SPF Bama sows at gestational day (GD) 113, GD107, GD104, GD101, and GD98 were selected and cesarean sections were performed. Then, the viability of the preterm piglets were observed. Based on their general data, viability, and paraffin sections stained with hematoxylin and eosin, the best time for performing cesarean section in order to build a SPF preterm pig model of lung development was determined.

RESULTS

Cesarean sections were performed on a total of 7 sows and 55 piglets were delivered, among which 25 were still alive 3 hours after delivery. Seven piglets of GD104 and all piglets of GD107 and GD113 survived, while piglets of GD98 and GD101 all died. The survival rate of piglets of GD104 was 33.33% (7/21). Piglets of GD98 already possessed fully developed physical appearance and lung shape. Piglets from GD104 had better lung expansion and higher density of thin-walled alveoli. The lungs of GD107 piglets were basically fully expanded, and the density of thin-walled alveoli was almost the same as that of normal full-term piglets.

CONCLUSIONS

Findings of this study suggest that SPF preterm piglets of GD104 with no specific pathogen exposure and no medical intervention can be used to establish a SPF preterm pig model of lung development.

[Clinical Analysis of 86 Cases of Children with Plastic Bronchitis]

OBJECTIVE

To investigate the clinical features of pediatric patients who had plastic bronchitis (PB) and to explore the risk factors for respiratory support in the pediatric patients with PB in order to improve the ability to identify PB in children.

METHODS

The basic information and clinical manifestations of 86 children diagnosed with PB at West China Second University Hospital of Sichuan University from March 2014 to December 2019 were collected and analyzed retrospectively. The patients were divided into the respiratory support (RS) group and non-respiratory support (NRS) group as per their need for respiratory support. Logistic regression was conducted to analyze the risk factors for respiratory support in PB patients.

RESULTS

A total of 86 children with PB were included in the study, including 62 (72.1%) who were over 3 years old. 57 patients (66.3%) had complications. 56 patients were given respiratory support after admission. All the 86 children had a history of fever and cough, and 76 (88.4%) experienced fever peaks≥39.5°C. Chest imaging showed large lung consolidation or atelectasis in 82 cases (95.3%) and pleural effusion in 63 cases (73.3%). 70 cases (81.4%) were tested positive for pathogens, with the highest infection rate of 68.6% for mycoplasma pneumoniae. There were 30 patients (34.9%) in the NRS group and 56 patients (65.1%) in the RS group. Logistic regression analysis showed that patient being younger than 3 years old ( OR=4.99) and having complications ( OR=7.22) were independent risk factors for respiratory support in children with PB (all P<0.05).

CONCLUSIONS

Clinically, severe clinical symptoms combined with other systemic complications, large lung consolidation or atelectasis, pleural effusion, and positive lab results for mycoplasma pneumoniae should be an alert indicating the possibility of having PB. Young age and complications were independent risk factors for respiratory support in PB patients.

[The Effects of Ginsenoside Compound K on PDGF-BB-Induced PASMCs Proliferation and Phenotypic Conversion of Pulmonary Arterial Smooth Muscle Cells]

OBJECTIVE

To explore the inhibitory effects of ginsenoside compound K (CK) on pulmonary arterial smooth muscle cells (PASMCs) proliferation and phenotypic conversion in vitro and investigate its related mechanisms.

METHODS

PASMCs cultured in vitro were examined in the study. They were induced with platelet-derived growth factor-BB (PDGF-BB) and then treated with CK. The cells were randomly assigned to the control group (receiving no treatment), the model group (PDGF-BB, 20 ng/mL), and the intervention group (20 ng/mL PDGF-BB+5 μmol/L CK). The cell proliferation was measured by CCK-8 assay (on the basis of the above group assignment, concentrations of CK was set at 1, 3, and 5 μmol/L in the intervention group, and the drug group was added, receiving 1, 3, and 5 μmol/L CK, respectively). Cell cycle and apoptosis were examined by flow cytometry. The levels of mRNA and proteins of α-smooth muscle actin ( α-SMA) and smooth muscle 22α ( SM22 α), markers of phenotypic conversion, were detected by quantitative real-time PCR and Western blot. The levels of protein expression related to Wnt/β-catenin signaling pathway were examined by Western blot.

RESULTS

Compared with the model group, CK significantly inhibited PDGF-BB-induced proliferation of PASMCs in a dose-dependent way. The results of 5 μmol/L CK intervention were not significantly different from that of the control group ( P>0.05). Hence, 5 μmol/L CK was chosen for subsequent experiments. Separate treatment of PASMCs with CK at doses of 1, 3, and 5 μmol/L did not reveal any cytotoxicity to PASMCs ( P>0.05). CK also arrested the cell cycle of PASMCs at the G 0/G 1 phase, promoted the apoptosis of PASMCs, and reversed the mRNA and protein expression of α-SMA and SM22 α ( P<0.01). In addition, CK down-regulated the expressions of cyclin D1 and β-catenin, while it up-regulated the protein expressions of phosphorylated glycogen synthase kinase-3β (pGSK-3β)/glycogen synthase kinase-3β (GSK-3β) ( P<0.01).

CONCLUSION

CK was capable of inhibiting the abnormal proliferation of PASMCs and reversing the phenotypic conversion, and its acting mechanism may be related to the Wnt/β-catenin signaling pathway, suggesting the therapeutic potential of CK in controlling pulmonary arterial hypertension.

[Epidemiological features and mechanism of coronavirus disease 2019 in children]

Compared with adults, children tend to have lower incidence rate, hospitalization rate, and mortality rate of coronavirus disease 2019 (COVID-19), while the cause of such age-based differences in disease severity remains unclear. An investigation of pathogenesis in children may help to analyze the therapies for the high-risk population. Human angiotensin-converting enzyme Ⅱ is the main receptor of severe acute respiratory syndrome coronavirus 2 and can limit pulmonary capillary leakage and inflammation mediated by angiotensin 2 and exert a protective effect against acute lung injury. Its expression decreases with age. Regular vaccination and frequent upper respiratory virus infection in children can lead to regular immune activation, and its combination with strong innate immunity can help to achieve virus clearance in the early stage of infection in children with COVID-19. Meanwhile, there are strong regeneration and repair abilities of alveolar epithelial cells in children, which may help with the early recovery of infection. In addition, risk factors, such as underlying cardiopulmonary diseases, obesity, and smoking, are relatively uncommon in children. Social factors, including home quarantine and timely closure of schools, may help to reduce the infection rate in children. However, children with immunodeficiency are a high-risk population and should be closely monitored. Further studies are needed to investigate the immune and protection mechanisms against COVID-19 in children.