Recombinant CCN1 prevents hyperoxia-induced lung injury in neonatal rats

Astragaloside IV improves pulmonary arterial hypertension by increasing the expression of CCN1 and activating the ERK1/2 pathway

The aim of the present study was to investigate the underlying mechanism of AS-IV and CCN1 in PAH and to evaluate whether the protective effect of AS-IV against PAH is associated with CCN1 and its related signalling pathway. In vivo, male SD rats were intraperitoneally injected with monocrotaline (MCT, 60 mg/kg) or exposed to hypoxia (10% oxygen) and gavaged with AS-IV (20, 40 and 80 mg/kg/day) to create a PAH model. In vitro, human pulmonary artery endothelial cells (hPAECs) were exposed to hypoxia (3% oxygen) or monocrotaline pyrrole (MCTP, 60 μg/mL) and treated with AS-IV (10, 20 and 40 μM), EGF (10 nM, ERK agonist), small interfering CCN1 (CCN1 siRNA) and recombinant CCN1 protein (rCCN1, 100 ng/mL). We identified the differences in the expression of genes in the lung tissues of PAH rats by proteomics. At the same time, we dynamically detected the expression of CCN1 by Western blot both in vivo and in vitro. The Western blot experimental results showed that the expression of CCN1 increased in the early stage of PAH and decreased in the advanced stage of PAH. The results showed that compared with the control group, MCT- and hypoxia-induced increased the hemodynamic parameters and apoptosis. AS-IV can improve PAH, as characterized by decreased hemodynamic parameters, vascular wall area ratio (WA%), vascular wall thickness ratio (WT%) and α-SMA expression and inhibition of cell apoptosis. Moreover, the improvement of PAH by AS-IV was accompanied by increased CCN1 expression, which activated the ERK1/2 signalling pathway. Meanwhile, CCN1 and p-ERK1/2 were inhibited by siCCN1 and promoted by rCCN1. EGF not only activated the ERK1/2 signalling pathway but also induced the expression of CCN1. In conclusion, AS-IV improves PAH by increasing the expression of CCN1 and activating the ERK1/2 signalling pathway. The results of our study provide a theoretical basis for additional study on the protective effect of AS-IV against PAH.

NLRP1 Inflammasomes: A Potential Target for the Treatment of Several Types of Brain Injury

NOD-like receptor (NLR) family pyrin domain-containing 1 (NLRP1) is a member of the NLR family. The NLRP1 inflammasome consists of the NLRP1 protein, the adaptor protein apoptosis-associated speck-like protein containing a CARD domain, and the effector molecule pro-caspase-1. When stimulated, the inflammasome initiates the cleavage of pro-caspase-1 and converts it into its active form, caspase-1; then, caspase-1 facilitates the cleavage of the proinflammatory cytokines interleukin-1β and interleukin-18 into their active and secreted forms. In addition, caspase-1 also mediates the cleavage of gasdermin D, which leads to pyroptosis, an inflammatory form of cell death. Pathological events that damage the brain and result in neuropathological conditions can generally be described as brain injury. Neuroinflammation, especially that driven by NLRP1, plays a considerable role in the pathophysiology of brain injury, such as early brain injury (EBI) of subarachnoid hemorrhage, ischemic brain injury during stroke, and traumatic brain injury (TBI). In this article, a thorough overview of NLRP1 is presented, including its structure, mechanism of activation, and role in neuroinflammation. We also present recent studies on NLRP1 as a target for the treatment of EBI, ischemic brain injury, TBI, and other types of brain injury, thus highlighting the perspective of NLRP1 as an effective mediator of catastrophic brain injury.

Simvastatin Inhibits NLRP3 Inflammasome Activation and Ameliorates Lung Injury in Hyperoxia-Induced Bronchopulmonary Dysplasia via the KLF2-Mediated Mechanism

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly found in premature infants. Excessive inflammation and oxidative stress contribute to BPD occurrence and development. Simvastatin, as an inhibitor of HMG-CoA reductase, has been reported to have antioxidative and anti-inflammatory effects. However, its effect and possible mechanisms in hyperoxia-induced lung injury are rarely reported. In this study, in vivo and in vitro experiments were conducted to investigate whether simvastatin could ameliorate hyperoxia-induced lung injury and explore its potential mechanism. For the in vivo study, simvastatin could improve alveolar development after hyperoxic lung injury and reduce hyperoxic stress and inflammation. The in vitro study revealed that simvastatin can reduce inflammation in A549 cells after high-oxygen exposure. Simvastatin suppressed NLRP3 inflammasome activation and played anti-inflammatory and antioxidant roles by increasing KLF2 (Krüppel-like factor 2) expression. In vitro experiments also revealed that these effects of simvastatin were partially reversed by KLF2 shRNA, indicating that KLF2 was involved in simvastatin effects. In summary, our findings indicate that simvastatin could downregulate NLRP3 inflammasome activation and attenuate lung injury in hyperoxia-induced bronchopulmonary dysplasia via KLF2-mediated mechanism.

The effect of miR-21-5p on the MAP2K3 expressions and cellular apoptosis in the lung tissues of neonatal rats with hyperoxia-induced lung injuries

OBJECTIVE

To explore the effect of miR-21-5p on the MAP2K3 expressions and cellular apoptosis in the lung tissues of neonatal rats with hyperoxia-induced lung injuries (HILI).

METHODS

Twenty Sprague-Dawley neonatal rats were assigned to the normal group, and 120 rats were used to create a HILI model and were divided into the following six groups of 20 rats each: the model group, the miR-21-5p NC group, the miR-21-5p agomir group, the oe-NC group (MAP2K3 overexpression NC), the oe-MAP2K3 group, and the miR-21-5p agomir+oe-MAP2K3 group.

RESULTS

miR-21-5p can target MAP2K3. Compared with the normal rats, the rats with HILI had lower miR-21-5p expression levels and higher MAP2K3 expression levels in the lung tissues (both P<0.05). Unlike the normal group, the other groups all presented different degrees of lung injuries, lower Bcl-2 expression levels, higher cellular apoptosis rates, and higher expression levels of cleaved caspase-3, Bax, IL-6, and TNF-α (all P<0.05). Compared with the model and the miR-21-5p NC groups, the miR-21-5p agomir group had better results in terms of the aforementioned markers; compared with the oe-NC group, the oe-MAP2K3 group had worse results in terms of these markers (all P<0.05). Moreover, we found that the protective effects of miR-21-5p overexpression on the lung tissues of HILI rats can be partially blocked by MAP2K3 overexpression.

CONCLUSION

miR-21-5p can inhibit MAP2K3 expression and reduce cellular apoptosis in HILI, thereby exerting protective effects on neonatal rats with HILI.

Tracing the genetic footprints of vertebrate landing in non-teleost ray-finned fishes

Rich fossil evidence suggests that many traits and functions related to terrestrial evolution were present long before the ancestor of lobe- and ray-finned fishes. Here, we present genome sequences of the bichir, paddlefish, bowfin, and alligator gar, covering all major early divergent lineages of ray-finned fishes. Our analyses show that these species exhibit many mosaic genomic features of lobe- and ray-finned fishes. In particular, many regulatory elements for limb development are present in these fishes, supporting the hypothesis that the relevant ancestral regulation networks emerged before the origin of tetrapods. Transcriptome analyses confirm the homology between the lung and swim bladder and reveal the presence of functional lung-related genes in early ray-finned fishes. Furthermore, we functionally validate the essential role of a jawed vertebrate highly conserved element for cardiovascular development. Our results imply the ancestors of jawed vertebrates already had the potential gene networks for cardio-respiratory systems supporting air breathing.

The Role of Innate Immunity in Pulmonary Infections

Innate immunity forms a protective line of defense in the early stages of pulmonary infection. The primary cellular players of the innate immunity against respiratory infections are alveolar macrophages (AMs), dendritic cells (DCs), neutrophils, natural killer (NK) cells, and innate lymphoid cells (ILCs). They recognize conserved structures of microorganisms through membrane-bound and intracellular receptors to initiate appropriate responses. In this review, we focus on the prominent roles of innate immune cells and summarize transmembrane and cytosolic pattern recognition receptor (PRR) signaling recognition mechanisms during pulmonary microbial infections. Understanding the mechanisms of PRR signal recognition during pulmonary pathogen infections will help us to understand pulmonary immunopathology and lay a foundation for the development of effective therapies to treat and/or prevent pulmonary infections.

Somanath P, Zhang D. The Roles of CCN1/CYR61 in Pulmonary Diseases

CCN1 (cysteine-rich 61, connective tissue growth factor, and nephroblastoma-1), previously named CYR61 (cysteine-rich angiogenic inducer 61) belongs to the CCN family of matricellular proteins. CCN1 plays critical roles in the regulation of proliferation, differentiation, apoptosis, angiogenesis, and fibrosis. Recent studies have extensively characterized the important physiological and pathological roles of CCN1 in various tissues and organs. In this review, we summarize both basic and clinical aspects of CCN1 in pulmonary diseases, including acute lung injury (ALI), chronic obstructive pulmonary disease (COPD), lung fibrosis, pulmonary arterial hypertension (PAH), lung infection, and lung cancer. We also emphasize the important challenges for future investigations to better understand the CCN1 and its role in physiology and pathology, as well as the questions that need to be addressed for the therapeutic development of CCN1 antagonists in various lung diseases.

Effects of Klotho supplementation on hyperoxia-induced renal injury in a rodent model of postnatal nephrogenesis

BACKGROUND

Hyperoxia (HO) causes kidney injury in preterm infants; however, whether these effects are modifiable is unknown. We hypothesized that administration of exogenous soluble Klotho, a kidney-derived antioxidant, would attenuate HO-induced kidney injury during postnatal nephrogenesis in rats.

METHODS

Sprague Dawley neonatal rats assigned to normoxia (21% O₂) or HO (85% O₂) groups from postnatal day (P) 1 to 21 were randomly assigned to receive alternate day intraperitoneal injections of recombinant Klotho or placebo for 3 weeks. They were recovered in normoxia for an additional 3 weeks and sacrificed at 6 weeks. Renal artery resistance and pulsatility indices, tubular injury scores, glomerular area, and renal antioxidant capacity were assessed.

RESULTS

Rodents exposed to HO during postnatal nephrogenesis had reduced kidney Klotho expression, glomerulomegaly, and higher tubular injury scores. Exogenous Klotho administration improved renal perfusion as indicated by decreases in both resistance and pulsatility indices and increased antioxidant enzyme expression.

CONCLUSIONS

HO exposure during postnatal nephrogenesis in rodents results in a decline in kidney Klotho expression, decreased renal perfusion, enlarged glomerular size, and tubular injury. The exogenous administration of Klotho attenuated HO-induced kidney injury and augmented antioxidant capacity.

Caffeine prevents hyperoxia-induced lung injury in neonatal mice through NLRP3 inflammasome and NF-κB pathway

Background

Bronchopulmonary dysplasia (BPD) is a common chronic lung disease in premature infants and hyperoxia exposure is a major cause. In hyperoxic lung injury animal model, alveolar simplification and pro-inflammatory cells infiltration are the main pathophysiologic changes. Caffeine is a drug used to treat apnea in premature infants. Early use of caffeine can decrease the rate and the severity of BPD while the mechanisms are still unclear. The purpose of this study was to evaluate the effects of caffeine on inflammation and lung development in neonatal mice with hyperoxic lung injury and to explore the possible mechanism.

Methods

Following 14 d of 75% oxygen exposure in newborn mouse, the BPD model was established. Caffeine at a dose of 1 g/L was added in drinking water to nursing mouse. We measured the concentration of caffeine in serum and oxidative stress in lung by commercially available kits. Adenosine 2A receptor (A_2AR) expression and lung inflammation were measured by Immunohistochemistry and western blotting. Apoptosis and surfactant protein-C (SFTPC) levels were measured by immunofluorescence. The inflammasome and NF-κB pathway proteins were assessed by western blotting.

Results

We found that the caffeine concentration in plasma at present dose significantly decreased the expression of A_2AR protein in mice lung. Caffeine treatment significantly reduced oxidative stress, improved weight gain, promoted alveolar development, attenuated inflammatory infiltration and lung injury in hyperoxia-induced lung injury mice. Moreover, caffeine decreased the cell apoptosis in lung tissues, especially the Type II alveolar epithelial cell. The expression of NLRP3 inflammasome protein and NF-κB pathway were significantly inhibited by caffeine treatment.

Conclusion

Caffeine treatment can protect hyperoxia-induced mice lung from oxidative injury by inhibiting NLRP3 inflammasome and NF-κB pathway.

Recent advances in our understanding of the mechanisms of lung alveolarization and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the most common cause of morbidity and mortality in preterm infants. A key histopathological feature of BPD is stunted late lung development, where the process of alveolarization-the generation of alveolar gas exchange units-is impeded, through mechanisms that remain largely unclear. As such, there is interest in the clarification both of the pathomechanisms at play in affected lungs, and the mechanisms of de novo alveoli generation in healthy, developing lungs. A better understanding of normal and pathological alveolarization might reveal opportunities for improved medical management of affected infants. Furthermore, disturbances to the alveolar architecture are a key histopathological feature of several adult chronic lung diseases, including emphysema and fibrosis, and it is envisaged that knowledge about the mechanisms of alveologenesis might facilitate regeneration of healthy lung parenchyma in affected patients. To this end, recent efforts have interrogated clinical data, developed new-and refined existing-in vivo and in vitro models of BPD, have applied new microscopic and radiographic approaches, and have developed advanced cell-culture approaches, including organoid generation. Advances have also been made in the development of other methodologies, including single-cell analysis, metabolomics, lipidomics, and proteomics, as well as the generation and use of complex mouse genetics tools. The objective of this review is to present advances made in our understanding of the mechanisms of lung alveolarization and BPD over the period 1 January 2017-30 June 2019, a period that spans the 50th anniversary of the original clinical description of BPD in preterm infants.

Time Dependent Pathway Activation of Signalling Cascades in Rat Organs after Short-Term Hyperoxia

Administration of oxygen is one of the most common interventions in medicine. Previous research showed that differential regulated proteins could be linked to hyperoxia-associated signaling cascades in different tissues. However, it still remains unclear which signaling pathways are activated by hyperoxia. The present study analyses hyperoxia-induced protein alterations in lung, brain, and kidney tissue using a proteomic and bioinformatic approach. Pooled data of 36 Wistar rats exposed to hyperoxia were used. To identify possible hyperoxia biomarkers, and to evaluate the relationship between protein alterations in hyperoxia affected organs and blood, proteomics data from brain, lung, and kidney were analyzed. Functional network analyses (IPA^®, PathwaysStudio^®, and GENEmania^®) in combination with hierarchical cluster analysis (Perseus^®) was used to identify relevant pathways and key proteins. Data of 54 2D-gels with more than 2500 significantly regulated spots per gel were collected. Thirty-eight differentially expressed proteins were identified and consecutively analyzed by bioinformatic methods. Most differences between hyperoxia and normoxia (21 proteins up-regulated, 17 proteins down-regulated) were found immediately after hyperoxia (15 protein spots), followed by day 3 (13 spots), and day 7 (10 spots). A highly significant association with inflammation and the inflammatory response was found. Cell proliferation, oxidative stress, apoptosis and cell death as well as cellular functions were revealed to be affected. Three hours of hyperoxia resulted in significant alterations of protein expression in different organs (brain, lung, kidney) up to seven days after exposure. Further studies are required to interpret the relevance of protein alterations in signaling cascades during/after hyperoxia.

Quercetin attenuates the hyperoxic lung injury in neonatal mice: Implications for Bronchopulmonary dysplasia (BPD)

Quercetin (QU) is one of the most common flavonoids that are present in a wide variety of fruits, vegetables, and beverages. This compound possesses potent anti-inflammatory and anti-oxidant properties. Supplemental oxygen is routinely administered to premature infants with pulmonary insufficiency. However, hyperoxia is one of the major risk factors for the development of bronchopulmonary dysplasia (BPD), which is also termed chronic lung disease in premature infants. Currently, no preventive approaches have been reported against BPD. The treatment of BPD is notably limited to oxygen administration, ventilatory support, and steroids. Since QU has been shown to be effective in reducing inflammation and oxidative stress in various disease models, we hypothesized that the postnatal QU treatment of newborn mice will protect against hyperoxic lung injury by the upregulation of the phase I (CYP1A/B) and/or phase II, NADPH quinone reductase enzymes. Newborn C57BL/6J mice within 24 h of birth with the nursing dams were exposed to either 21% O₂ (air) and/or 85% O₂ (hyperoxia) for 7 days. The mice were treated, intraperitoneally (i.p.) once every other day with quercetin, at a concentration of 20 mg/kg, or saline alone from postnatal day (PND) 2-6. The mice were sacrificed on day 7, and lung and liver tissues were collected. The expression levels of CYP1A1, CYP1B1, NQO1 proteins and mRNA as well as the levels of MDA-protein adducts were analyzed in lung and liver tissues. The findings indicated that QU attenuated hyperoxia-mediated lung injury by reducing inflammation and improving alveolarization with decreased number of neutrophil and macrophage infiltration. The attenuation of this lung injury correlated with the upregulation of CYP1A1/CYP1B1/NQO1 mRNA, proteins and the down regulation of NF-kB levels and MDA-protein adducts in lung and liver tissues. The present study demonstrated the potential therapeutic value of quercetin in the prevention and/or treatment of BPD.

The matricellular protein CCN1 in tissue injury repair

The expression of Ccn1 (Cyr61) is essential for cardiovascular development during embryogenesis, whereas in adulthood it is associated with inflammation, wound healing, injury repair, and related pathologies including fibrosis and cancer. Recent studies have found that CCN1 plays a critical role in promoting wound healing and tissue repair. Mechanistically, CCN1 functions through direct interaction with specific integrin receptors expressed in various cell types in the wound tissue microenvironment to coordinate diverse cellular functions for repair. Here we briefly summarize the current knowledge on the functions of CCN1 in tissue injury repair and discuss pertinent unanswered questions.

CCN5 in alveolar epithelial proliferation and differentiation during neonatal lung oxygen injury

Lung immaturity is the major cause of morbidity and mortality in premature infants, especially those born <28 weeks of gestation. These infants are at high risk of developing respiratory distress syndrome (RDS), a lung disease caused by insufficient surfactant production and immaturity of saccular/alveolar type II epithelial cells in the lung. RDS treatment includes oxygen and respiratory support that improve survival but also increase the risk for bronchopulmonary dysplasia (BPD), a chronic lung disease characterized by arrested alveolarization, airway hyperreactivity, and pulmonary hypertension. The mechanisms regulating normal alveolar development and how injury disrupts normal development to cause BPD are not well understood. We examined the role of the matricellular protein CCN5 (Cysteine-rich protein 61/Connective tissue growth factor/Nephroblastoma-overexpressed protein) in the development of BPD. Cultured non-proliferating alveolar type II cells expressed low levels of CCN5 protein, and displayed higher levels during proliferation. siRNA targeting of CCN5 reduced alveolar type II cell proliferation and migration in cell culture. In a mouse model of hyperoxia-induced BPD, CCN5 protein was increased only in proliferating alveolar type I cells. Alveolar epithelial cells co-expressing markers of type II cells and type I cells also appeared. The results suggest that hyperoxic injury in immature lungs induces proliferation of type I cells and trans-differentiation of type II cells into type I cells. We propose that the mechanism of the injury response in BPD includes CCN5 expression. Study of CCN5 in neonatal alveolar injury will further our understanding of BPD pathophysiology while providing a mechanistic foundation for therapeutic approaches.