Lipoxin A4 attenuates hyperoxia‑induced lung epithelial cell injury via the upregulation of heme oxygenase‑1 and inhibition of proinflammatory cytokines

A signaling network map of Lipoxin (LXA4): an anti-inflammatory molecule

Lipoxins (LXs) are a class of endogenous bioactive lipid mediators that are involved in the regulation of inflammation. They exert immunomodulatory effects by regulating the behaviour of various immune cells, including neutrophils, macrophages, and T and B cells, by promoting the clearance of apoptotic neutrophils. This helps to dampen inflammation and promote tissue repair. LXs regulate the expression of many inflammatory genes by modulating the levels of transcription factors, such as nuclear factor κB (NF-κB), activator protein-1 (AP-1), nerve growth factor-regulated factor 1A binding protein 1 (NGF), and peroxisome proliferator activated receptor γ (PPAR-γ), which are elevated in various diseases, such as respiratory tract diseases, renal diseases, cancer, neurodegenerative diseases, and viral infections. Lipoxin-mediated signaling is involved in chronic inflammation, cancer, diabetes-associated kidney disease, lung injury, liver injury, endometriosis, respiratory tract diseases, neurodegenerative diseases, chronic cerebral hypoperfusion, and retinal degeneration. In this study, we systematically investigated the intricate network of lipoxin signaling by analyzing the relevant literature. The resulting map comprised 467 molecules categorized as activation/inhibition, enzyme catalysis, gene and protein expression, molecular associations, and translocation events. This map serves as a valuable resource for understanding the complexity of lipoxin signaling and its impact on various cellular functions.

Dose-dependent effects of human umbilical cord-derived mesenchymal stem cell treatment in hyperoxia-induced lung injury of neonatal rats

Background

Mesenchymal stem cells (MSCs) are multipotent stromal cells that have been reported to possess great potential for the treatment of bronchopulmonary dysplasia (BPD).

Objective

Our study aims to assess the effects of three different doses of intraperitoneal administration of human umbilical cord-derived MSCs (hUC-MSCs) on a hyperoxia-induced BPD model of newborn rat.

Methods

Neonatal Sprague Dawley (SD) rats were reared in either hyperoxia (75% O2) or room air (RA) from postnatal days (PN) 1-14. At PN5, hUC-MSCs (1 × 106, 5× 106,or 1× 107 cells per pup) were given intraperitoneally to newborn rats exposed to 75% O2 from birth; the controls received an equal volume of normal saline (NS). At PN14, the lung tissues, serum, and bronchoalveolar fluid (BALF) were collected for histologic examination, wet/dry (W/D) weight ratio analysis, engraftment, myeoloperoxidase (MPO) activity analysis, cytokine analysis, and western blot analysis of protein expression.

Results

Compared to rat pups reared in RA, rat pups reared in hyperoxia had a significant lower survival rate (53.3%) (P < 0.01). Hyperoxia-exposed rats exhibited pulmonary inflammation accompanied by alveolar-capillary leakage, neutrophile infiltration, augmented myeloperoxidase (MPO) activity, prominent alveolar simplification, and increased mean linear intercept (MLI), which was ameliorated by hUC-MSCs treatment. Increased oxidative stress and inflammatory cytokine production were also reduced. Importantly, the expression of Fas, an apoptosis-associated protein that was increasingly expressed in hyperoxia-exposed rats (P < 0.05), was downregulated after administration of hUC-MSCs (P < 0.05).

Conclusions

Our results suggest that intraperitoneal administration of high number hUC-MSCs (1 × 107 cells) may represent an effective modality for the treatment of hyperoxia-induced BPD in neonatal rats.

Intratracheal administration of umbilical cord-derived mesenchymal stem cells attenuates hyperoxia-induced multi-organ injury via heme oxygenase-1 and JAK/STAT pathways

BACKGROUND

Bronchopulmonary dysplasia (BPD) is not merely a chronic lung disease, but a systemic condition with multiple organs implications predominantly associated with hyperoxia exposure. Despite advances in current management strategies, limited progress has been made in reducing the BPD-related systemic damage. Meanwhile, although the protective effects of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) or their exosomes on hyperoxia-induced lung injury have been explored by many researchers, the underlying mechanism has not been addressed in detail, and few studies have focused on the therapeutic effect on systemic multiple organ injury.

AIM

To investigate whether hUC-MSC intratracheal administration could attenuate hyperoxia-induced lung, heart, and kidney injuries and the underlying regulatory mechanisms.

METHODS

Neonatal rats were exposed to hyperoxia (80% O₂), treated with hUC-MSCs intratracheal (iT) or intraperitoneal (iP) on postnatal day 7, and harvested on postnatal day 21. The tissue sections of the lung, heart, and kidney were analyzed morphometrically. Protein contents of the bronchoalveolar lavage fluid (BALF), myeloperoxidase (MPO) expression, and malondialdehyde (MDA) levels were examined. Pulmonary inflammatory cytokines were measured via enzyme-linked immunosorbent assay. A comparative transcriptomic analysis of differentially expressed genes (DEGs) in lung tissue was conducted via RNA-sequencing. Subsequently, we performed reverse transcription-quantitative polymerase chain reaction and western blot analysis to explore the expression of target mRNA and proteins related to inflammatory and oxidative responses.

RESULTS

iT hUC-MSCs administration improved pulmonary alveolarization and angiogenesis (P < 0.01, P < 0.01, P < 0.001, and P < 0.05 for mean linear intercept, septal counts, vascular medial thickness index, and microvessel density respectively). Meanwhile, treatment with hUC-MSCs iT ameliorated right ventricular hypertrophy (for Fulton’s index, P < 0.01), and relieved reduced nephrogenic zone width (P < 0.01) and glomerular diameter (P < 0.001) in kidneys. Among the beneficial effects, a reduction of BALF protein, MPO, and MDA was observed in hUC-MSCs groups (P < 0.01, P < 0.001, and P < 0.05 respectively). Increased pro-inflammatory cytokines tumor necrosis factor-alpha, interleukin (IL)-1β, and IL-6 expression observed in the hyperoxia group were significantly attenuated by hUC-MSCs administration (P < 0.01, P < 0.001, and P < 0.05 respectively). In addition, we observed an increase in anti-inflammatory cytokine IL-10 expression in rats that received hUC-MSCs iT compared with rats reared in hyperoxia (P < 0.05). Transcriptomic analysis showed that the DEGs in lung tissues induced by hyperoxia were enriched in pathways related to inflammatory responses, epithelial cell proliferation, and vasculature development. hUC-MSCs administration blunted these hyperoxia-induced dysregulated genes and resulted in a shift in the gene expression pattern toward the normoxia group. hUC-MSCs increased heme oxygenase-1 (HO-1), JAK2, and STAT3 expression, and their phosphorylation in the lung, heart, and kidney (P < 0.05). Remarkably, no significant difference was observed between the iT and iP administration.

CONCLUSION

iT hUC-MSCs administration ameliorates hyperoxia-induced lung, heart, and kidney injuries by activating HO-1 expression and JAK/STAT signaling. The therapeutic benefits of local iT and iP administration are equivalent.

Obesity Attenuates Ventilator-Induced Lung Injury by Modulating the STAT3-SOCS3 Pathway

Background

Ventilator-induced lung injury (VILI) is characterized by vascular barrier dysfunction and suppression of alveolar fluid clearance (AFC). Obesity itself leads to chronic inflammation, which may initiate an injurious cascade to the lungs and simultaneously induce a protective feedback. In this study, we investigated the protective mechanism of obesity on VILI in a mouse model.

Methods

The VILI model was set up via 6-h mechanical ventilation with a high tidal volume. Parameters including lung injury score, STAT3/NFκB pathway, and AFC were assessed. Mice with diet-induced obesity were obtained by allowing free access to a high-fat diet since the age of 3 weeks. After a 9-week diet intervention, these mice were sacrificed at the age of 12 weeks. The manipulation of SOCS3 protein was achieved by siRNA knockdown and pharmaceutical stimulation using hesperetin. WNK4 knockin and knockout obese mice were used to clarify the pathway of AFC modulation.

Results

Obesity itself attenuated VILI. Knockdown of SOCS3 in obese mice offset the protection against VILI afforded by obesity. Hesperetin stimulated SOCS3 upregulation in nonobese mice and provided protection against VILI. In obese mice, the WNK4 axis was upregulated at the baseline, but was significantly attenuated after VILI compared with nonobese mice. At the baseline, the manipulation of SOCS3 by siRNA and hesperetin also led to the corresponding alteration of WNK4, albeit to a lesser extent. After VILI, WNK4 expression correlated with STAT3/NFκB activation, regardless of SOCS3 status. Obese mice carrying WNK4 knockout had VILI with a severity similar to that of wild-type obese mice. The severity of VILI in WNK4-knockin obese mice was counteracted by obesity, similar to that of wild-type nonobese mice only.

Conclusions

Obesity protects lungs from VILI by upregulating SOCS3, thus suppressing the STAT3/NFκB inflammatory pathway and enhancing WNK4-related AFC. However, WNK4 activation is mainly from direct NFκB downstreaming, and less from SOCS3 upregulation. Moreover, JAK2-STAT3/NFκB signaling predominates the pathogenesis of VILI. Nevertheless, the interaction between SOCS3 and WNK4 in modulating VILI in obesity warrants further investigation.