New mouse model of pulmonary hypertension induced by respiratory syncytial virus bronchiolitis

Micro-CT Features of Lung Consolidation, Collagen Deposition and Inflammation in Experimental RSV Infection Are Aggravated in the Absence of Nrf2

Severe respiratory syncytial virus (RSV) infections in early life have been linked to the development of chronic airway disease. RSV triggers the production of reactive oxygen species (ROS), which contributes to inflammation and enhanced clinical disease. NF-E2-related factor 2 (Nrf2) is an important redox-responsive protein that helps to protect cells and whole organisms from oxidative stress and injury. The role of Nrf2 in the context of viral-mediated chronic lung injury is not known. Herein, we show that RSV experimental infection of adult Nrf2-deficient BALB/c mice (Nrf2-/-; Nrf2 KO) is characterized by enhanced disease, increased inflammatory cell recruitment to the bronchoalveolar compartment and a more robust upregulation of innate and inflammatory genes and proteins, compared to wild-type Nrf2+/+ competent mice (WT). These events that occur at very early time points lead to increased peak RSV replication in Nrf2 KO compared to WT mice (day 5). To evaluate longitudinal changes in the lung architecture, mice were scanned weekly via high-resolution micro-computed tomography (micro-CT) imaging up to 28 days after initial viral inoculation. Based on micro-CT qualitative 2D imaging and quantitative reconstructed histogram-based analysis of lung volume and density, we found that RSV-infected Nrf2 KO mice developed significantly greater and prolonged fibrosis compared to WT mice. The results of this study underscore the critical role of Nrf2-mediated protection from oxidative injury, not only in the acute pathogenesis of RSV infection but also in the long-term consequences of chronic airway injury.

Echocardiographic Markers of Mild Pulmonary Hypertension are not Correlated with Worse Respiratory Outcomes in Infants with Bronchiolitis

Pulmonary hypertension has been reported as a crucial factor in the pathophysiology of severe bronchiolitis. The aim of this study was to evaluate pulmonary artery pressure (PAP) in patients with bronchiolitis and to analyze their correlation with clinical outcomes. This prospective cohort study examined children admitted for bronchiolitis. PAP was assessed by right ventricle (RV) acceleration/ejection time ratio (AT/ET), isovolumic relaxation time, eccentricity index, and the presence of a pulmonary systolic notch. Pulmonary hypertension (PH) was considered if at least two altered parameters were present. Severity of clinical course was established by higher N-terminal (NT)-prohormone BNP (NT-proBNP) values, the need for positive pressure respiratory support (PPRS), and the duration of hospital admission. One hundred sixty-nine children were included in analysis. Sixty-eight patients (40%) required PPRS, and those patients had increased NT-proBNP values and worse tricuspid annular systolic excursion (TAPSE) compared to mild cases (p < 0.001and p < 0.001, respectively). Twenty-two (13%) cases had at least two altered parameters of PAP and met criteria for presumed PH, with no differences in NT-proBNP values, TAPSE, need for PPRS or hospital length of stay compared to normal PAP group (p = 0.98, p = 0.07, p = 0.94 and p = 0.64, respectively). We found no correlation between altered RV AT/ET and worse cardiac function, NT-proBNP values or hospital length of stay. In our cohort, the presence of echocardiographic findings of PH were not associated with worse clinical outcomes. Patients with severe bronchiolitis had higher values ​​of NT-proBNP but, interestingly, no clear association with PH.

Biomedical Imaging in Experimental Models of Cardiovascular Disease

Major advances in biomedical imaging have occurred over the last 2 decades and now allow many physiological, cellular, and molecular processes to be imaged noninvasively in small animal models of cardiovascular disease. Many of these techniques can be also used in humans, providing pathophysiological context and helping to define the clinical relevance of the model. Ultrasound remains the most widely used approach, and dedicated high-frequency systems can obtain extremely detailed images in mice. Likewise, dedicated small animal tomographic systems have been developed for magnetic resonance, positron emission tomography, fluorescence imaging, and computed tomography in mice. In this article, we review the use of ultrasound and positron emission tomography in small animal models, as well as emerging contrast mechanisms in magnetic resonance such as diffusion tensor imaging, hyperpolarized magnetic resonance, chemical exchange saturation transfer imaging, magnetic resonance elastography and strain, arterial spin labeling, and molecular imaging.

Emerging Viral Infections and the Potential Impact on Hypertension, Cardiovascular Disease, and Kidney Disease

Viruses are ubiquitous in the environment and continue to have a profound impact on human health and disease. The COVID-19 pandemic has highlighted this with impressive morbidity and mortality affecting the world's population. Importantly, the link between viruses and hypertension, cardiovascular disease, and kidney disease has resulted in a renewed focus and attention on this potential relationship. The virus responsible for COVID-19, SARS-CoV-2, has a direct link to one of the major enzymatic regulatory systems connected to blood pressure control and hypertension pathogenesis, the renin-angiotensin system. This is because the entry point for SARS-CoV-2 is the ACE2 (angiotensin-converting enzyme 2) protein. ACE2 is one of the main enzymes responsible for dampening the primary effector peptide Ang II (angiotensin II), metabolizing it to Ang-(1-7). A myriad of clinical questions has since emerged and are covered in this review. Several other viruses have been linked to hypertension, cardiovascular disease, and kidney health. Importantly, patients with high-risk apolipoprotein L1 (APOL1) alleles are at risk for developing the kidney lesion of collapsing glomerulopathy after viral infection. This review will highlight several emerging viruses and their potential unique tropisms for the kidney and cardiovascular system. We focus on SARS-CoV-2 as this body of literature in regards to cardiovascular disease has advanced significantly since the COVID-19 pandemic.

Characterization of Cardiopulmonary Interactions and Exploring Their Prognostic Value in Acute Bronchiolitis: A Prospective Cardiopulmonary Ultrasound Study

We aimed to delineate cardiopulmonary interactions in acute bronchiolitis and to evaluate the capacity of a combined cardiopulmonary ultrasonography to predict the need for respiratory support. This was a prospective observational single-center study that includes infants <12 month of age admitted to a hospital due to acute bronchiolitis. All the included patients underwent clinical, laboratory and cardiopulmonary ultrasonographic evaluation at the same time point within 24 h of hospital admission. The existence of significant correlation between cardiac and respiratory parameters was the primary outcome. The association of different cardiopulmonary variables with the need of respiratory support higher than O₂, the length of stay hospitalization, the PICU stay and the duration of respiratory support were a secondary outcome. We enrolled 112 infants (median age 1 (0.5–3) months; 62% males) hospitalized with acute bronchiolitis. Increased values of the pulmonary variables (BROSJOD score, pCO₂ and LUS) showed moderate correlations with NT-proBNP and all echocardiographic parameters indicative of pulmonary hypertension and myocardial dysfunction (Tei index). Up to 36 (32%) infants required respiratory support during the hospitalization. This group presented with higher lung ultrasound score (p < 0.001) and increased values of NT-proBNP (p < 0.001), the Tei index (p < 0.001) and pulmonary artery pressures (p < 0.001). All the analyzed respiratory and cardiac variables showed moderate-to-strong correlations with the LOS of hospitalization and the time of respiratory support. Lung ultrasound and echocardiography showed a moderate-to-strong predictive accuracy for the need of respiratory support in the ROC analysis, with the AUC varying from 0.74 to 0.87. Those cases of bronchiolitis with a worse pulmonary status presented with a more impaired cardiac status. Cardiopulmonary ultrasonography could be a useful tool to easily identify high-risk populations for complicated acute bronchiolitis hospitalization.

Pertussis Toxin Promotes Pulmonary Hypertension in an Infant Mouse Model of Bordetella pertussis Infection

Pertussis, caused by Bordetella pertussis, is a reemerging disease that can produce severe disease manifestations in infants, including pulmonary hypertension (PH). B. pertussis-induced PH is a major risk factor for infection-induced death, but the molecular mechanisms promoting PH are unknown and there is no effective treatment. We examined B. pertussis-induced PH in infant and adult mouse models of pertussis by Fulton index, right heart catheterization, or Doppler echocardiogram. Our results demonstrate that B. pertussis-induced PH is age related and dependent on the expression of pertussis toxin by the bacterium. Hence, pertussis toxin-targeting treatments may ameliorate PH and fatal infant infection.

Analysis of healthcare-associated infection in patients with pulmonary arterial hypertension associated with congenital heart disease in PICU: Evidence from a tertiary hospital in western China

OBJECTIVE

The present study intends to analyze the targeted surveillance and risk factors for healthcare-associated infection (HAI) in patients with pulmonary arterial hypertension associated with congenital heart disease (CHD-PAH) in a Pediatric intensive care unit (PICU), and provide basis for formulating relevant prevention and control measures of HAI.

METHODS

Children (≤14 years old) who were admitted to the PICU for ≥2 calendar days from January 2018 to December 2021 were included. Targeted surveillance of HAI was described.

RESULTS

A total of 7,828 patients in PICU were monitored, and the total hospitalization days of the patients were 36,174. 108 cases of HAI occurred, with a per-case infection rate of 1.38% and a per-thousand day infection rate of 2.99. 1,129 patients with CHD-PAH were included, among which the total hospitalization days were 1,483. In this subpopulation, 38 cases of HAI were diagnosed, with a per-case infection rate of 3.37% and a per-thousand day infection rate of 25.62. The main site of HAI was lower respiratory tract (43.51%), followed by blood infection (34.26%) and surgical site infection (9.26%). 36 strains of pathogenic bacteria were detected from patients with HAI. The top three pathogens with the highest detection rate were Klebsiella pneumoniae (6 episodes, 16.67%), Enterococcus faecium (6 episodes, 16.67%) and Acinetobacter baumannii (4 episodes, 11.11%). The incidence of VAP, CAUTI and CLABSI was 2.78, 0.08 and 1.66 per 1,000 catheter days respectively. Analysis revealed that patients with CHD-PAH were younger and prone to receive surgical corrections. CHD-PAH could significantly increase the length of ICU stay, ventilator days, times of central venous catheterization and central venous catheterization days. The choice of different central venous catheter types differed significantly between the two groups.

CONCLUSION

Patients with CHD-PAH are characterized with excessive central venous catheterization operations, prolonged indwelling time, and more types of catheterization, which are considered to be risk factors for HAI, thus increasing the length of hospital stay. The clinical etiology is mainly G-bacteria, which requires reasonable selection of antibiotics and strict aseptic operation. Limiting unnecessary invasive procedures is helpful for reducing the incidence of postoperative HAI in PICU.

Deficiency in ST2 signaling ameliorates RSV-associated pulmonary hypertension

Pulmonary hypertension (PH) observed during respiratory syncytial virus (RSV) bronchiolitis is associated with morbidity and mortality, especially in children with congenital heart disease. Yet, the pathophysiological mechanisms of RSV-associated PH remain unclear. Therefore, this study aimed to investigate the pathophysiological mechanism of RSV-associated PH. We used a translational mouse model of RSV-associated PH, in which wild-type (WT) and suppression of tumorigenicity 2 (ST2) knockout neonatal mice were infected with RSV at 5 days old and reinfected 4 wk later. The development of PH in WT mice following RSV reinfection was evidenced by elevated right ventricle systolic pressure, shortened pulmonary artery acceleration time (PAT), and decreased PAT/ejection time (ET) ratio. It coincided with the augmentation of periostin and IL-13 expression and increased arginase bioactivity by both arginase 1 and 2 as well as induction of nitric oxide synthase (NOS) uncoupling. Absence of ST2 signaling prevented RSV-reinfected mice from developing PH by suppressing NOS uncoupling. In summary, ST2 signaling was involved in the development of RSV-associated PH. ST2 signaling inhibition may be a novel therapeutic target for RSV-associated PH.NEW & NOTEWORTHY We report that the pathogenic role of ST2-mediated type 2 immunity and mechanisms contribute to RSV-associated pulmonary hypertension. Inhibiting ST2 signaling may be a novel therapeutic target for this condition.