KGF-2 targets alveolar epithelia and capillary endothelia to reduce high altitude pulmonary oedema in rats

B2M is a Biomarker Associated With Immune Infiltration In High Altitude Pulmonary Edema

BACKGROUND

High altitude pulmonary edema (HAPE) is a serious mountain sickness with certain mortality. Its early diagnosis is very important. However, the mechanism of its onset and progression is still controversial.

AIM

This study aimed to analyze the HAPE occurrence and development mechanism and search for prospective biomarkers in peripheral blood.

METHODS

The difference genes (DEGs) of the Control group and the HAPE group were enriched by gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and then GSEA analysis was performed. After identifying the immune-related hub genes, QPCR was used to verify and analyze the hub gene function and diagnostic value with single-gene GSEA and ROC curves, and the drugs that acted on the hub gene was found in the CTD database. Immune infiltration and its association with the hub genes were analyzed using CIBERSORT. Finally, WGCNA was employed to investigate immune invasion cells' significantly related gene modules, following enrichment analysis of their GO and KEGG.

RESULTS

The dataset enrichment analysis, immune invasion analysis and WGCNA analysis showed that the occurrence and early progression of HAPE were unrelated to inflammation. The hub genes associated with immunity obtained with MCODE algorithm of Cytoscape were JAK2 and B2M.. RT-qPCR and ROC curves confirmed that the hub gene B2M was a specific biomarker of HAPE and had diagnostic value, and single-gene GSEA analysis confirmed that it participated in MHC I molecule-mediated antigen presentation ability decreased, resulting in reduced immunity.

CONCLUSION

Occurrence and early progression of high altitude pulmonary edema may not be related to inflammation. B2M may be a new clinical potential biomarker for HAPE for early diagnosis and therapeutic evaluation as well as therapeutic targets, and its decrease may be related to reduced immunity due to reduced ability of MCH I to participate in antigen submission.

Deficiency of endothelial FGFR1 signaling via upregulation of ROCK2 activity aggravated ALI/ARDS

Vascular leakage and inflammation are pathological hallmarks of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Endothelial cells (ECs) serve as a semipermeable barrier and play a key role in disease progression. It is well known that fibroblast growth factor receptor 1 (FGFR1) is required for maintaining vascular integrity. However, how endothelial FGFR1 functions in ALI/ARDS remains obscure. Here, we revealed that conditional deletion of endothelial FGFR1 aggravated LPS-induced lung injury, including inflammation and vascular leakage. Inhibition of its downstream Rho-associated coiled-coil–forming protein kinase 2 (ROCK2) by AAV Vec-tie-shROCK2 or its selective inhibitor TDI01 effectively attenuated inflammation and vascular leakage in a mouse model. In vitro, TNFα-stimulated human umbilical vein endothelial cells (HUVECs) showed decreased FGFR1 expression and increased ROCK2 activity. Furthermore, knockdown of FGFR1 activated ROCK2 and thus promoted higher adhesive properties to inflammatory cells and higher permeability in HUVECs. TDI01 effectively suppressed ROCK2 activity and rescued the endothelial dysfunction. These data demonstrated that the loss of endothelial FGFR1 signaling mediated an increase in ROCK2 activity, which led to an inflammatory response and vascular leakage in vivo and in vitro. Moreover, inhibition of ROCK2 activity by TDI01 provided great value and shed light on clinical translation.

Repairing Mechanisms for Distal Airway Injuries and Related Targeted Therapeutics for Chronic Lung Diseases

Chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF), involve progressive and irreversible destruction and pathogenic remodeling of airways and have become the leading health care burden worldwide. Pulmonary tissue has extensive capacities to launch injury-responsive repairing programs (IRRPs) to replace the damaged or dead cells upon acute lung injuries. However, the IRRPs are frequently compromised in chronic lung diseases. In this review, we aim to provide an overview of somatic stem cell subpopulations within distal airway epithelium and the underlying mechanisms mediating their self-renewal and trans-differentiation under both physiological and pathological circumstances. We also compared the differences between humans and mice on distal airway structure and stem cell composition. At last, we reviewed the current status and future directions for the development of targeted therapeutics on defective distal airway regeneration and repairment in chronic lung diseases.

Fibroblast growth factor 10 attenuates chronic obstructive pulmonary disease by protecting against glycocalyx impairment and endothelial apoptosis

Background

The defects and imbalance in lung repair and structural maintenance contribute to the pathogenesis of chronic obstructive pulmonary diseases (COPD), yet the molecular mechanisms that regulate lung repair process are so far incompletely understood. We hypothesized that cigarette smoking causes glycocalyx impairment and endothelial apoptosis in COPD, which could be repaired by the stimulation of fibroblast growth factor 10 (FGF10)/FGF receptor 1 (FGFR1) signaling.

Methods

We used immunostaining (immunohistochemical [IHC] and immunofluorescence [IF]) and enzyme-linked immunosorbent assay (ELISA) to detect the levels of glycocalyx components and endothelial apoptosis in animal models and in patients with COPD. We used the murine emphysema model and in vitro studies to determine the protective and reparative role of FGF10/FGFR1.

Results

Exposure to cigarette smoke caused endothelial glycocalyx impairment and emphysematous changes in murine models and human specimens. Pretreatment of FGF10 attenuated the development of emphysema and the shedding of glycocalyx components induced by CSE in vivo. However, FGF10 did not attenuate the emphysema induced by endothelial-specific killing peptide CGSPGWVRC-GG-_D(KLAKLAK)₂. Mechanistically, FGF10 alleviated smoke-induced endothelial apoptosis and glycocalyx repair through FGFR1/ERK/SOX9/HS6ST1 signaling in vitro. FGF10 was shown to repair pulmonary glycocalyx injury and endothelial apoptosis, and attenuate smoke-induced COPD through FGFR1 signaling.

Conclusions

Our results suggest that FGF10 may serve as a potential therapeutic strategy against COPD via endothelial repair and glycocalyx reconstitution.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02193-5.

It is the first time to prove the confirm the endothelial glycocalyx impairment in COPD.

FGF10 attenuates the development of emphysema and the shedding of glycocalyx induced by CSE in vivo.

FGF10 alleviates smoke-induced endothelial apoptosis and glycocalyx repair through FGFR1/ERK/SOX9/HS6ST1 signaling.

Study of mesenchymal stem cells derived from lung-resident, bone marrow and chorion for treatment of LPS-induced acute lung injury

BACKGROUND

Mesenchymal stem cells (MSCs) have been shown to improve acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). However, the optimal source of MSCs for cell-based therapy remains unknown. To determine which kind of MSCs are more effective, we compared the effects of rat lung resident MSC (LRMSC), human chorion-derived MSC (HMSC-C) and human bone marrow derived MSC (HMSC-BM) in LPS-induced ALI in mice.

METHODS

LPS (Pseudomonas aeruginosa) was used to induce ALI model. All three kinds of MSCs were administered via tail vein 4 h after LPS instillation. The mice were sacrificed 48 h after LPS instillation. H&E staining of lung section, wet-to-dry weight ratio of lung tissue, ratio of regulatory T cells (Tregs) and Th17 cells, and total protein concentration, leukocytes counting and cytokines in bronchoalveolar lavage fluid (BALF) were evaluated.

RESULTS

The data showed that compared with LRMSC and HMSC-BM, HMSC-C more significantly attenuated lung injury, upregulated the Tregs/Th17 cells ratio, and inhibited release of inflammatory cytokines (IL-1β, IL-6 and TNF-α) and recruitment of neutrophils and macrophages into alveolus.

CONCLUSIONS

Although all three kinds of LRMSC, HMSC-C and HMSC-BM are protective against LPS-induced lung injury, HMSC-C was more effective than LRMSC and HMSC-BM to treat LPS-induced lung injury.

Dexmedetomidine preconditioning ameliorates lung injury induced by pulmonary ischemia/reperfusion by upregulating promoter histone H3K4me3 modification of KGF-2

Keratinocyte growth factor (KGF)-2 has been highlighted to play a significant role in maintaining the endothelial barrier integrity in lung injury induced by ischemia-reperfusion (I/R). However, the underlying mechanism remains largely unknown. The aims of this study were to determine whether dexmedetomidine preconditioning (DexP) modulates pulmonary I/R-induced lung injury through the alteration in KGF-2 expression. In our I/R-modeled mice, DexP significantly inhibited pathological injury, inflammatory response, and inflammatory cell infiltration, while promoted endothelial barrier integrity and KGF-2 promoter activity in lung tissues. Bioinformatics prediction and ChIP-seq revealed that I/R significantly diminished the level of H3K4me3 modification in the KGF-2 promoter, which was significantly reversed by DexP. Moreover, DexP inhibited the expression of histone demethylase JMJD3, which in turn promoted the expression of KGF-2. In addition, overexpression of JMJD3 weakened the protective effect of DexP on lung injury in mice with I/R. Collectively, the present results demonstrated that DexP ameliorates endothelial barrier dysfunction via the JMJD3/KGF-2 axis.

Regulation of alveolar type 2 stem/progenitor cells in lung injury and regeneration

The renewal of lung epithelial cells is normally slow unless the lung is injured. The resident epithelial stem cells rapidly proliferate and differentiate to maintain lung structure and function when the lung is damaged. The alveolar epithelium is characterized by alveolar type 1 (AT1) and alveolar type 2 (AT2) cells. AT2 cells are the stem cells for alveoli, as they can both self-renew and generate AT1 cells. Abnormal proliferation and regulation of AT2 cells will lead to serious lung diseases including cancers. In this review, we focused on the alveolar stem/progenitor cells, the key physiological function of AT2 cells in lung homeostasis and the complicated regulation of AT2 cells in the repairing processes after lung injury.

KGF-2 and FGF-21 poloxamer 407 hydrogel coordinates inflammation and proliferation homeostasis to enhance wound repair of scalded skin in diabetic rats

OBJECTIVE

The present study focused on the development of a poloxamer 407 thermosensitive hydrogel loaded with keratinocyte growth factor-2 (KGF-2) and fibroblast growth factor-21 (FGF-21) as a therapeutic biomaterial in a scald-wound model of type-2 diabetes in Goto-Kakizaki (GK) rats.

RESEARCH DESIGN AND METHODS

In this study, a poloxamer 407 thermosensitive hydrogel loaded with KGF-2 and/or FGF-21 was prepared and its physical and biological properties were characterized. The repairing effects of this hydrogel were investigated in a scald-wound model of type-2 diabetes in GK rats. The wound healing rate, epithelialization, and formation of granulation tissue were examined, and biomarkers reflecting regulation of proliferation and inflammation were quantified by immunostaining and Western blotting. T tests and analyses of variance were used for statistical analysis via Graphpad Prism V.6.0.

RESULTS

A 17.0% (w/w) poloxamer 407 combined with 1.0% (w/w) glycerol exhibited controlled release characteristics and a three-dimensional structure. A KGF-2/FGF-21 poloxamer hydrogel promoted cellular migration without apoptosis. This KGF-2/FGF-21 poloxamer hydrogel also accelerated wound healing of scalded skin in GK rats better than that of a KGF-2 or FGF-21 hydrogel alone due to accelerated epithelialization, formation of granulation tissue, collagen synthesis, and angiogenesis via inhibition of inflammatory responses and increased expression of alpha-smooth muscle actin (α-SMA), collagen III, pan-keratin, transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and CD31.

CONCLUSIONS

A KGF-2/FGF-21 poloxamer hydrogel accelerated wound healing of scalded skin in GK rats, which was attributed to a synergistic effect of KGF-2-mediated cellular proliferation and FGF-21-mediated inhibition of inflammatory responses. Taken together, our findings provide a novel and potentially important insight into improving wound healing in patients with diabetic ulcers.

Fibroblast growth factor 10 alleviates particulate matter-induced lung injury by inhibiting the HMGB1-TLR4 pathway

Exposure to particulate matter (PM) is associated with increased incidence of respiratory diseases. The present study aimed to investigate the roles of fibroblast growth factor 10 (FGF10) in PM-induced lung injury. Mice were intratracheally instilled with FGF10 or phosphate-buffered saline at one hour before instillation of PM for two consecutive days. In addition, the anti-inflammatory impact of FGF10 in vitro and its effect on the high-mobility group box 1 (HMGB1)-toll-like receptor 4 (TLR4) pathway was investigated. It was found that PM exposure is associated with increased inflammatory cell infiltration into the lung and increased vascular protein leakage, while FGF10 pretreatment attenuated both of these effects. FGF10 also decreased the PM-induced expression of interleukin (IL)-6, IL-8, tumor necrosis factor-α and HMGB1 in murine bronchoalveolar lavage fluid and in the supernatants of human bronchial epithelial cells exposed to PM. FGF10 exerted anti-inflammatory and cytoprotective effects by inhibiting the HMGB1-TLR4 pathway. These results indicate that FGF10 may have therapeutic values for PM-induced lung injury.

Fibroblast growth factor 10 protects against particulate matter-induced airway inflammatory response through regulating inflammatory signaling and apoptosis

Chronic respiratory disorders are some of the most frequent and severe chronic diseases in China. Epidemiological research has shown that particulate matter (PM) is a risk factor and is closely correlated to the progression of numerous respiratory diseases. Fibroblast growth factor 10 (FGF10) is a mesenchymal-epithelial signaling messenger essential for the development and environmental stability of several tissues. Nevertheless, its role in PM-induced airway inflammation remains unclear. The present study aimed to explore the mechanisms underlying the FGF10-related slowing of lung injury and inflammation in vivo and in vitro, as well as the therapeutic potential of these phenomena. Mice were intraperitoneally injected with a vehicle (PBS) or FGF10 (0.5 mg/kg) at one hour before intratracheal treatment with vehicle (PBS) or PM (4 mg/kg) for two consecutive days. Human airway epithelial BEAS-2B cells were exposed to a vehicle (PBS) or FGF10 (10 ng/ml) in vitro at one hour prior to incubation with a vehicle or PM (200 ug/ml) for 24 hours. Then, the impact on inflammatory molecules was investigated. In vivo, it was found that FGF10 diminished the inflammatory cell aggregation and reduced the apoptosis. Interestingly, in the PM group, the level of FGF10 increased in the bronchoalveolar lavage fluid (BALF). However, the pre-treatment with FGF10 markedly impaired the PM-induced increase in IL-6, IL-8, TNF-α and PGE2 levels in BALF and the cell supernatant. In conclusion, the present findings indicate that FGF10 attenuates PM-induced airway inflammation by inhibiting apoptosis and inflammation. This may be exploited for the prevention and management of PM-induced airway inflammation.

Keratinocyte Growth Factor-2 Is Protective in Oleic Acid-Induced Acute Lung Injury in Rats

Objective

The aim of this study was to examine the role of keratinocyte growth factor-2 (KGF-2) in oleic acid-induced acute lung injury (ALI) in rats.

Methods

 Forty-five healthy adult male Sprague Dawley rats were divided into 3 groups. Rat ALI model was established by injection of 0.01 mL/kg oleic acid into the tail vein. Rats in the control group were injected with the same amount of normal saline (NS). In the ALI + KGF-2 group, 5 mg/kg of KGF-2 was instilled into the airway of rats 72 hours before the model preparation, and the control group and the ALI model group were instilled with the same amount of NS. The lung permeability index (LPI) and lung wet/dry weight (W / D) ratios were measured 8 hours after the model preparation. The permeability of pulmonary microvascular endothelium was evaluated by Evans blue leakage test. Histopathological changes were observed under light microscope and the ALI pathology score (LIS) was calculated. Ultrastructural changes of lung tissue were observed under electron microscope. The apoptosis was detected by TUNEL assay. The expression of Claudin-5, ZO-1, and VE Cadherin in lung tissue was qualitatively and quantitatively analyzed by immunohistochemistry, Western Blot, and qRT-PCR, respectively.

Results

The ALI model group had severe lung injury and obvious pathological changes, including alveolar septal thickening and inflammatory cell infiltration. TUNEL assay showed that the apoptosis of ALI group was significantly increased. The LIS score, lung W/D ratio, LPI, and Evans blue leakage were significantly higher than those in the control group; electron microscopy showed that the alveolar-capillary barrier was severely damaged in the ALI group. Compared with the control group, the expression of Claudin-5, ZO-1, and VE cadherin in the lung tissue of the ALI model group was significantly attenuated. After pretreatment with KGF-2, the degree of lung tissue damage was significantly reduced and the pathological changes were significantly improved. TUNEL assay showed that the apoptosis of ALI group was decreased. Lung W/D ratio, LPI, and Evans blue leakage decreased; electron microscopy showed that the alveolar-capillary barrier of ALI group recovered significantly. Compared with the ALI model group, the expression of Claudin-5, ZO-1, and VE cadherin in the lung tissue of the KGF-2 pretreatment group increased.

Conclusion

The results indicate that KGF-2 may attenuate oleic acid-induced ALI in rats by maintaining the pulmonary microvascular endothelial barrier, which is an effective ALI preventive measure.

FGF10 and Human Lung Disease Across the Life Spectrum

Lung diseases impact patients across the lifespan, from infants in the first minutes of life through the aged population. Congenital abnormalities of lung structure can cause lung disease at birth or make adults more susceptible to chronic disease. Continuous inhalation of atmospheric components also requires the lung to be resilient to cellular injury. Fibroblast growth factor 10 (FGF10) regulates multiple stages of structural lung morphogenesis, cellular differentiation, and the response to injury. As a driver of lung airway branching morphogenesis, FGF10 signaling defects during development lead to neonatal lung disease. Alternatively, congenital airway abnormalities attributed to FGF10 mutations increase the risk of chronic airway disease in adulthood. FGF10 also maintains progenitor cell populations in the airway and promotes alveolar type 2 cell expansion and differentiation following injury. Here we review the cellular and molecular mechanisms linking FGF10 to multiple lung diseases, from bronchopulmonary dysplasia in extremely preterm neonates, cystic fibrosis in children, and chronic adult lung disorders. Understanding the connections between FGF10 and lung diseases may lead to exciting new therapeutic strategies.

Fgf10 Signaling in Lung Development, Homeostasis, Disease, and Repair After Injury

The lung is morphologically structured into a complex tree-like network with branched airways ending distally in a large number of alveoli for efficient oxygen exchange. At the cellular level, the adult lung consists of at least 40–60 different cell types which can be broadly classified into epithelial, endothelial, mesenchymal, and immune cells. Fibroblast growth factor 10 (Fgf10) located in the lung mesenchyme is essential to regulate epithelial proliferation and lineage commitment during embryonic development and post-natal life, and to drive epithelial regeneration after injury. The cells that express Fgf10 in the mesenchyme are progenitors for mesenchymal cell lineages during embryonic development. During adult lung homeostasis, Fgf10 is expressed in mesenchymal stromal niches, between cartilage rings in the upper conducting airways where basal cells normally reside, and in the lipofibroblasts adjacent to alveolar type 2 cells. Fgf10 protects and promotes lung epithelial regeneration after different types of lung injuries. An Fgf10-Hippo epithelial-mesenchymal crosstalk ensures maintenance of stemness and quiescence during homeostasis and basal stem cell (BSC) recruitment to further promote regeneration in response to injury. Fgf10 signaling is dysregulated in different human lung diseases including bronchopulmonary dysplasia (BPD), idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD), suggesting that dysregulation of the FGF10 pathway is critical to the pathogenesis of several human lung diseases.

Mesenchymal stem cells reduce hypoxia-induced apoptosis in alveolar epithelial cells by modulating HIF and ROS hypoxic signaling

Distal lung diseases, such as pulmonary fibrosis or acute lung injury, are commonly associated with local alveolar hypoxia that may be deleterious through the stimulation of alveolar epithelial cell (AEC) apoptosis. In various murine models of alveolar injury, administration of allogenic human mesenchymal stem cells (hMSCs) exerts an overall protective paracrine effect, limiting lung inflammation and fibrosis. However, the precise mechanisms on lung cells themselves remain poorly understood. Here, we investigated whether hMSC-conditioned medium (hMSC-CM) would protect AECs from hypoxia-induced apoptosis and explored the mechanisms involved in this cytoprotective effect. Exposure of rat primary AECs to hypoxia (1.5% O₂ for 24 h) resulted in hypoxia-inducible factor (HIF)-1α protein stabilization, partly dependent on reactive oxygen species (ROS) accumulation, and in a twofold increase in AEC apoptosis that was prevented by the HIF inhibitor 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl-indazole and the antioxidant drug N-acetyl cysteine. Incubation of AECs with hMSC-CM significantly reduced hypoxia-induced apoptosis. hMSC-CM decreased HIF-1α protein expression, as well as ROS accumulation through an increase in antioxidant enzyme activities. Expression of Bnip3 and CHOP, two proapoptotic targets of HIF-1α and ROS pathways, respectively, was suppressed by hMSC-CM, while Bcl-2 expression was restored. The paracrine protective effect of hMSC was partly dependent on keratinocyte growth factor and hepatocyte growth factor secretion, preventing ROS and HIF-1α accumulation.

Therapeutic effects of fibroblast growth factor-10 on hyperoxia-induced bronchopulmonary dysplasia in neonatal mice

The survival rate of preterm neonates increases significantly with the development of neonatal care and comprehensive treatment, but more and more high-risk preterm neonates suffer from bronchopulmonary dysplasia (BPD). Currently, there is no effective treatment for BPD, thus it is still a major cause of disability and mortality in neonates. Thus, it is imperative to investigate the pathogenesis and treatment of BPD in depth. Fibroblast growth factor-10 (FGF-10) is a paracrine growth factor binding its receptors (FGFR1 and FGFR2) to regulate a lot of biological processes. FGF-10, with mitotic and chemotactic activities, plays an important role in histogenesis during embryonic stage. It can prevent and attenuate mechanical or infection induced inflammation in lung. Results showed lung FGF-10 expression reduced significantly in neonatal mice with BPD, and exogenous FGF-10 was able to promote the growth of pulmonary mesenchymal stem cells and alveolar epithelial cells type II and reduce the expression of pro-inflammatory cytokines. We preliminarily explored the relationship between FGF-10 and NF-κB in this animal model and found FGF-10 could inhibit NF-κB p65 expression as a feedback. Thus, to investigate the protective effects of FGF-10 on hyperoxia induced BPD in neonatal mice will provide a new strategy for the treatment of BPD.

Resolvin D1 Improves the Resolution of Inflammation via Activating NF-κB p50/p50-Mediated Cyclooxygenase-2 Expression in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a severe illness characterized by uncontrolled inflammation. The resolution of inflammation is a tightly regulated event controlled by endogenous mediators, such as resolvin D1 (RvD1). Cyclooxygenase-2 (COX-2) has been reported to promote inflammation, along with PGE2, in the initiation of inflammation, as well as in prompting resolution, with PGD2 acting in the later phase of inflammation. Our previous work demonstrated that RvD1 enhanced COX-2 and PGD2 expression to resolve inflammation. In this study, we investigated mechanisms underlying the effect of RvD1 in modulating proresolving COX-2 expression. In a self-limited ARDS model, an LPS challenge induced the biphasic activation of COX-2, and RvD1 promoted COX-2 expression during the resolution phase. However, it was significantly blocked by treatment of a NF-κB inhibitor. In pulmonary fibroblasts, NF-κB p50/p50 was shown to be responsible for the proresolving activity of COX-2. Additionally, RvD1 potently promoted p50 homodimer nuclear translocation and robustly triggered DNA-binding activity, upregulating COX-2 expression via lipoxin A4 receptor/formyl peptide receptor 2. Finally, the absence of p50 in knockout mice prevented RvD1 from promoting COX-2 and PGD2 expression and resulted in excessive pulmonary inflammation. In conclusion, RvD1 expedites the resolution of inflammation through activation of lipoxin A4 receptor/formyl peptide receptor 2 receptor and NF-κB p50/p50-COX-2 signaling pathways, indicating that RvD1 might have therapeutic potential in the management of ARDS.

Fibroblast Growth Factor-10 (FGF-10) Mobilizes Lung-resident Mesenchymal Stem Cells and Protects Against Acute Lung Injury

FGF-10 can prevent or reduce lung specific inflammation due to traumatic or infectious lung injury. However, the exact mechanisms are poorly characterized. Additionally, the effect of FGF-10 on lung-resident mesenchymal stem cells (LR-MSCs) has not been studied. To better characterize the effect of FGF-10 on LR-MSCs, FGF-10 was intratracheally delivered into the lungs of rats. Three days after instillation, bronchoalveolar lavage was performed and plastic-adherent cells were cultured, characterized and then delivered therapeutically to rats after LPS intratracheal instillation. Immunophenotyping analysis of FGF-10 mobilized and cultured cells revealed expression of the MSC markers CD29, CD73, CD90, and CD105, and the absence of the hematopoietic lineage markers CD34 and CD45. Multipotency of these cells was demonstrated by their capacity to differentiate into osteocytes, adipocytes, and chondrocytes. Delivery of LR-MSCs into the lungs after LPS injury reduced the inflammatory response as evidenced by decreased wet-to-dry ratio, reduced neutrophil and leukocyte recruitment and decreased inflammatory cytokines compared to control rats. Lastly, direct delivery of FGF-10 in the lungs of rats led to an increase of LR-MSCs in the treated lungs, suggesting that the protective effect of FGF-10 might be mediated, in part, by the mobilization of LR-MSCs in lungs.

Neuron-derived FGF10 ameliorates cerebral ischemia injury via inhibiting NF-κB-dependent neuroinflammation and activating PI3K/Akt survival signaling pathway in mice

FGF10 is a member of fibroblast growth factors (FGFs). We previously showed that FGF10 protects neuron against oxygen-glucose deprivation injury in vitro; however, the effect of FGF10 in ischemic stroke in vivo is unknown. In the present study, we showed that FGF10 was mainly expressed in neurons but not astrocytes, and detected FGF10 in mouse cerebrospinal fluid. The FGF10 levels in neurons culture medium and cell lysate were much higher than those in astrocytes. FGF10 expression in brain tissue and FGF10 level in CSF were increased in mouse middle cerebral artery occlusion (MCAO) model. Administration of FGF10 into lateral cerebroventricle not only decreased MCAO-induced brain infarct volume and neurological deficit, but also reduced the number of TUNEL-positive cells and activities of Caspases. Moreover, FGF10 treatment depressed the triggered inflammatory factors (TNF-α and IL-6) and NF-κB signaling pathway, and increased phosphorylation of PI3K/Akt signaling pathway. Blockade of PI3K/Akt signaling pathway by wortmannin and Akt1/2-kinase inhibitor, partly compromised the neuroprotection of FGF10. However, blockade of PI3K/Akt signaling pathway did not impair the anti-inflammation action of FGF10. Collectively, our results demonstrate that neuron-derived FGF10 ameliorates cerebral ischemia injury via inhibiting NF-κB-dependent neuroinflammation and activating PI3K/Akt survival signaling pathway in mice.

Keratinocyte growth factor-2 inhibits bacterial infection with Pseudomonas aeruginosa pneumonia in a mouse model

To determine protective effects of concurrent administration of Keratinocyte growth factor-2 (KGF-2) with Pseudomonas aeruginosa (P. aeruginosa) inoculation on the induced pneumonia. KGF-2 (5 mg/kg) was concurrently administered into the left lobe of 55 mice with P. aeruginosa PAO1 (5 × 10(6) CFU, half-lethal dose); 55 mice in the control group were concurrently administered PBS with the PAO1. We detected and analyzed: body temperature; amount of P. aeruginosa in homogenates; count of total number of nucleated cells and of mononuclear macrophages; protein concentration in bronchoalveolar lavage fluid (BALF); lung wet-to-dry weight ratio; cytokines in BALF and blood; and lung morphology. To study survival rate, concurrent administration of KGF-2 (experimental group) versus PBS (control) with a lethal dose of PAO1 (1 × 10(7) CFU was performed, and survivorship was documented for 7 days post-inoculation. The bacterial CFU in lung homogenates was significantly decreased in the KGF-2 group compared to the control group. There were significantly more mononuclear macrophages in the BALF from the KGF-2 group than from the control group (p < 0.05). KGF-2 increased the surfactant protein and GM-CSF mRNA in lung at 6 h and 72 h after inoculation. Significant reduction of lung injury scores, protein concentrations, lung wet-to-dry weight ratio, and IL-6 and TNF-α levels was noted in the KGF-2 treated rats at 72 h after inoculation (p < 0.05). The 7-day survival rate of the KGF-2 group was significantly higher than that of the control group (p < 0.05). Concurrent administration of KGF-2 facilitates the clearance of P. aeruginosa from the lungs, attenuates P. aeruginosa-induced lung injury, and extends the 7-day survival rate in mice model with P. aeruginosa pneumonia.

NSFC spurs significant basic research progress of respiratory medicine in China

Over the years, research in respiratory medicine has progressed rapidly in China. This commentary narrates the role of the National Natural Science Foundation of China (NSFC) in supporting the basic research of respiratory medicine, summarizes the major progress of respiratory medicine in China, and addresses the main future research directions sponsored by the NSFC.

Protective effects of keratinocyte growth factor-2 on ischemia-reperfusion-induced lung injury in rats

Ischemia-reperfusion (I/R) is a common cause to compromise tissue injury via endothelial and epithelial barrier dysfunction and damage. Keratinocyte growth factor (KGF)-2 could play an important role in the repair of alveolar epithelial damage and maintain the capillary barrier function. The present study aimed to investigate the potential effects of KGF-2 on I/R-induced lung injury in rats and the related mechanisms. KGF-2 (2.5-10 mg/kg) was administered intratracheally in rats 3 days before the left lobe with ischemia for 60 minutes followed by reperfusion for 180 minutes. Lung injury was evaluated by measuring lung morphology, blood gas analysis, total cell number, and protein concentration in the bronchoalveolar lavage fluid. The protective effects of KGF-2 on human pulmonary microvascular endothelial cells and related mechanisms were evaluated. Pretreatment with KGF-2 significantly prevented I/R-induced lung edema, inflammatory cell infiltration, protein exudation, and the release of inflammatory cytokines in rats, or I/R-induced endothelial cell apoptosis, migration, and barrier dysfunction. Phosphoinositide 3-kinase or epidermal growth factor receptor inhibitors attenuated the protective effect of KGF-2 in endothelial cells. Our results evidence that the local administration of KGF-2 may be an alternative to prophylactic or adjunct drug therapies for I/R-induced lung injury.

Keratinocyte growth factor-2 is protective in lipopolysaccharide-induced acute lung injury in rats

Keratinocyte growth factor-2 (KGF-2) plays a key role in lung development, but its role in acute lung injury has not been well characterized. Lipopolysaccharide instillation caused acute lung injury, which significantly elevated lung wet-to-dry weight ratio, protein and neutrophils in bronchoalveolar lavage fluid (BALF), inhibited surfactant protein A and C expression in lung tissue, and increased pathological injury. Pretreatment with KGF-2 improved the above lung injury parameters, partially restored surfactant protein A and C expression, and KGF-2 given 2-3 days before LPS challenge showed maximum lung injury improvement. Pretreatment with KGF-2 also markedly reduced the levels of TNF-α, MIP-2, IL-1β and IL-6 in BALF and the levels of IL-1β and IL-6 in lung tissue. Histological analysis showed there was increased proliferation of alveolar type II epithelial cells in lung parenchyma, which reached maximal 2 days after KGF-2 instillation. Intratracheal administration of KGF-2 attenuates lung injury induced by LPS, suggesting KGF-2 may be potent in the intervention of acute lung injury.

Keratinocyte growth factor-2 intratracheal instillation significantly attenuates ventilator-induced lung injury in rats

Preservation or restoration of normal alveolar epithelial barrier function is crucial for pulmonary oedema resolution. Keratinocyte growth factor-2 (KGF-2), a potent epithelial cell mitogen, may have a role in preventing ventilator-induced lung injury (VILI), which occurs frequently in mechanically ventilated patients. The aim of the study was to test the role of KGF-2 in VILI in rats. Forty healthy adult male Sprague-Dawley rats were randomly allocated into four groups, where rats in Groups HVZP (high-volume zero positive end-expiratory pressure) and HVZP+KGF-2 were given intratracheally equal PBS and 5 mg/kg KGF-2 72 hrs before 4 hrs HVZP ventilation (20 ml/kg), respectively, while PBS and KGF-2 were administered in the same manner in Groups Control and KGF-2, which underwent tracheotomy only with spontaneous breathing. Inflammatory cytokines (tumour necrosis factor-α, macrophage inflammatory protein 2), neutrophil and total protein levels in bronchoalveolar lavage fluid and surfactant protein mRNA expression in lung tissue were detected; the number of alveolar type II cells, lung water content and lung morphology were also evaluated. The results indicate that pre-treatment with KGF-2 showed dramatic improvement in lung oedema and inflammation compared with HVZP alone, together with increased surfactant protein mRNA and alveolar type II cells. Our results suggest that KGF-2 might be considered a promising prevention for human VILI or other acute lung injury diseases.

New insights of aquaporin 5 in the pathogenesis of high altitude pulmonary edema

Background

High altitude pulmonary edema (HAPE) affects individuals and is characterized by alveolar flooding with protein-rich edema as a consequence of blood-gas barrier disruption. In this study, we hypothesized that aquaporin 5 (AQP5) which is one kind of water channels may play a role in preservation of alveolar epithelial barrier integrity in high altitude pulmonary edema (HAPE).

Methods

Therefore, we established a model in Wildtype mice and AQP5 −/− mice were assingned to normoxic rest (NR), hypoxic rest (HR) and hypoxic exercise (HE) group. Mice were produced by training to walk at treadmill for exercising and chamber pressure was reduced to simulate climbing an altitude of 5000 m for 48 hours. Studies using BAL in HAPE mice to demonstrated that edema is caused leakage of albumin proteins and red cells across the alveolarcapillary barrier in the absence of any evidence of inflammation.

Results

In this study, the Lung wet/dry weight ratio and broncholalveolar lavage protein concentrations were slightly increased in HE AQP5 −/− mice compared to wildtype mice. And histologic evidence of hemorrhagic pulmonary edema was distinctly shown in HE group. The lung Evan’s blue permeability of HE group was showed slightly increased compare to the wildtype groups, and HR group was showed a medium situation from normal to HAPE development compared with NR and HE group.

Conclusions

Deletion of AQP5 slightly increased lung edema and lung injury compared to wildtype mice during HAPE development, which suggested that the AQP5 plays an important role in HAPE formation induced by high altitude simulation.

Barrier enhancing signals in pulmonary edema

Increased endothelial permeability and reduction of alveolar liquid clearance capacity are two leading pathogenic mechanisms of pulmonary edema, which is a major complication of acute lung injury, severe pneumonia, and acute respiratory distress syndrome, the pathologies characterized by unacceptably high rates of morbidity and mortality. Besides the success in protective ventilation strategies, no efficient pharmacological approaches exist to treat this devastating condition. Understanding of fundamental mechanisms involved in regulation of endothelial permeability is essential for development of barrier protective therapeutic strategies. Ongoing studies characterized specific barrier protective mechanisms and identified intracellular targets directly involved in regulation of endothelial permeability. Growing evidence suggests that, although each protective agonist triggers a unique pattern of signaling pathways, selected common mechanisms contributing to endothelial barrier protection may be shared by different barrier protective agents. Therefore, understanding of basic barrier protective mechanisms in pulmonary endothelium is essential for selection of optimal treatment of pulmonary edema of different etiology. This article focuses on mechanisms of lung vascular permeability, reviews major intracellular signaling cascades involved in endothelial monolayer barrier preservation and summarizes a current knowledge regarding recently identified compounds which either reduce pulmonary endothelial barrier disruption and hyperpermeability, or reverse preexisting lung vascular barrier compromise induced by pathologic insults.

Rhodiola crenulata Extract Alleviates Hypoxic Pulmonary Edema in Rats

Sudden exposure of nonacclimatized individuals to high altitude can easily lead to high altitude illnesses. High altitude pulmonary edema (HAPE) is the most lethal form of high altitude illness. The present study was designed to investigate the ability of Rhodiola crenulata extract (RCE), an herbal medicine traditionally used as an antiacute mountain sickness remedy, to attenuate hypoxia-induced pulmonary injury. Exposure of animals to hypobaric hypoxia led to a significant increase in pathological indicators for pulmonary edema, including the lung water content, disruption of the alveolar-capillary barrier, and protein-rich fluid in the lungs. In addition, hypobaric hypoxia also increased oxidative stress markers, including (ROS) production, (MDA) level, and (MPO) activity. Furthermore, overexpression of plasma (ET-1), (VEGF) in (BALF), and (HIF-1α) in lung tissue was also found. However, pretreatment with RCE relieved the HAPE findings by curtailing all of the hypoxia-induced lung injury parameters. These findings suggest that RCE confers effective protection for maintaining the integrity of the alveolar-capillary barrier by alleviating the elevated ET-1 and VEGF levels; it does so by reducing hypoxia-induced oxidative stress. Our results offer substantial evidence to support arguments in favor of traditional applications of Rhodiola crenulata for antihigh altitude illness.