Pulmonary edema fluid from patients with early lung injury stimulates fibroblast proliferation through IL-1 beta-induced IL-6 expression

Targeted liposomes for macrophages-mediated pulmonary fibrosis therapy

Pulmonary fibrosis (PF) is a horrible lung disease that causes pulmonary ventilation dysfunction and respiratory failure, severely impacting sufferers' physical and mental health. Existing drugs can only partially control the condition and are prone to toxic side effects. Anti-inflammatory treatment is the committed step to alleviate PF. Celastrol (CLT) has significant anti-inflammatory effects and can reverse M1-type transformation of macrophages. In this study, we have developed liposomes loaded with CLT, modified with folate (FA), designated FA-CLT-Lips, which facilitate drug delivery by targeting macrophages. FA-CLT-Lips were shown to be more readily absorbed by macrophages in vitro and to encourage the transition of M1 macrophages into M2 macrophages. In addition, FA-CLT-Lips can inhibit the phosphorylation of Smad2/3, effectively reducing the deposition of extracellular matrix (ECM) and the production of inflammatory factors. This showed that FA-CLT-Lips can ameliorate early lung fibrosis by lowering inflammation. In vivo studies have shown that FA-CLT-Lips accumulate in lung tissue to better attenuate lung injury and collagen deposition, with less toxicity compared to free CLT. In summary, FA receptor-targeting liposomes loaded with CLT provide a secure and reliable PF therapy.

IL-1β stimulated human umbilical cord mesenchymal stem cells ameliorate rheumatoid arthritis via inducing apoptosis of fibroblast-like synoviocytes

Rheumatoid arthritis (RA) is characterized by synovial proliferation and lymphocyte accumulation leading to progressive damage of the periarticular bone and the articular cartilage. The hyperplasia of the synovial intima lining mainly consists of fibroblast-like synoviocytes-rheumatoid arthritis (HFLS-RA) which exhibit apoptosis-resistance, hyper-proliferation, and high invasiveness. The therapeutic efficacy of mesenchymal stem cells (MSCs) treatment in RA has been shown to be due to its immuno-regulatory ability. However, the exact factors and mechanisms involved in MSCs treatment in RA remain unclear. In this study, TRAIL receptor-Death receptor 4 (DR4), DR5, and LFA-1 ligand-intercellular adhesion molecule-1 (ICAM-1) were upregulated in IL-1β-stimulated HFLS-RA. We demonstrated that the total cell number of IL-1β-stimulated hUCMSCs adhering to IL-1β-stimulated HFLA-RA increased via LFA-1/ICAM-1 interaction. Direct co-culture of IL-1β-stimulated hUCMSCs with IL-1β-stimulated HFLS-RA increased the apoptosis of HFLS-RA. RA symptoms in the CIA mouse model improved after administration of IL-1β-stimulated hUCMSCs. In conclusion, IL-1β-stimulated hUCMSCs adhering to HFLS-RA occurred via LFA-1/ICAM-1 interaction, apoptosis of HFLS-RA was induced via TRAIL/DR4, DR5 contact, and RA symptoms and inflammation were significantly improved in a CIA mouse model. The results of this study suggest that IL-1β-stimulated hUCMSCs have therapeutic potential in RA treatment.

Targeting caveolae to pump bispecific antibody to TGF-β into diseased lungs enables ultra-low dose therapeutic efficacy

The long-sought-after "magic bullet" in systemic therapy remains unrealized for disease targets existing inside most tissues, theoretically because vascular endothelium impedes passive tissue entry and full target engagement. We engineered the first "dual precision" bispecific antibody with one arm pair to precisely bind to lung endothelium and drive active delivery and the other to precisely block TGF-β effector function inside lung tissue. Targeting caveolae for transendothelial pumping proved essential for delivering most of the injected intravenous dose precisely into lungs within one hour and for enhancing therapeutic potency by >1000-fold in a rat pneumonitis model. Ultra-low doses (μg/kg) inhibited inflammatory cell infiltration, edema, lung tissue damage, disease biomarker expression and TGF-β signaling. The prodigious benefit of active vs passive transvascular delivery of a precision therapeutic unveils a new promising drug design, delivery and therapy paradigm ripe for expansion and clinical testing.

DFV890: a new oral NLRP3 inhibitor—tested in an early phase 2a randomised clinical trial in patients with COVID-19 pneumonia and impaired respiratory function

Background

Coronavirus-associated acute respiratory distress syndrome (CARDS) has limited effective therapy to date. NLRP3 inflammasome activation induced by SARS-CoV-2 in COVID-19 contributes to cytokine storm.

Methods

This randomised, multinational study enrolled hospitalised patients (18–80 years) with COVID-19-associated pneumonia and impaired respiratory function. Eligible patients were randomised (1:1) via Interactive Response Technology to DFV890 + standard-of-care (SoC) or SoC alone for 14 days. Primary endpoint was APACHE II score at Day 14 or on day-of-discharge (whichever-came-first) with worst-case imputation for death. Other key assessments included clinical status, CRP levels, SARS-CoV-2 detection, other inflammatory markers, in-hospital outcomes, and safety.

Findings

Between May 27, 2020 and December 24, 2020, 143 patients (31 clinical sites, 12 countries) were randomly assigned to DFV890 + SoC (n = 71) or SoC alone (n = 72). Primary endpoint to establish clinical efficacy of DFV890 vs. SoC, based on combined APACHE II score, was not met; LSM (SE), 8·7 (1.06) vs. 8·6 (1.05); p = 0.467. More patients treated with DFV890 vs. SoC showed ≥ 1-level improvement in clinical status (84.3% vs. 73.6% at Day 14), earlier clearance of SARS-CoV-2 (76.4% vs. 57.4% at Day 7), and mechanical ventilation-free survival (85.7% vs. 80.6% through Day 28), and there were fewer fatal events in DFV890 group (8.6% vs. 11.1% through Day 28). DFV890 was well tolerated with no unexpected safety signals.

Interpretation

DFV890 did not meet statistical significance for superiority vs. SoC in primary endpoint of combined APACHE II score at Day 14. However, early SARS-CoV-2 clearance, improved clinical status and in-hospital outcomes, and fewer fatal events occurred with DFV890 vs. SoC, and it may be considered as a protective therapy for CARDS.

Trial registration

ClinicalTrials.gov, NCT04382053.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-022-01904-w.

Glucocorticoid therapy in respiratory illness: bench to bedside

Each year, hundreds of millions of individuals are affected by respiratory disease leading to approximately 4 million deaths. Most respiratory pathologies involve substantially dysregulated immune processes that either fail to resolve the underlying process or actively exacerbate the disease. Therefore, clinicians have long considered immune-modulating corticosteroids (CSs), particularly glucocorticoids (GCs), as a critical tool for management of a wide spectrum of respiratory conditions. However, the complex interplay between effectiveness, risks and side effects can lead to different results, depending on the disease in consideration. In this comprehensive review, we present a summary of the bench and the bedside evidence regarding GC treatment in a spectrum of respiratory illnesses. We first describe here the experimental evidence of GC effects in the distal airways and/or parenchyma, both in vitro and in disease-specific animal studies, then we evaluate the recent clinical evidence regarding GC treatment in over 20 respiratory pathologies. Overall, CS remain a critical tool in the management of respiratory illness, but their benefits are dependent on the underlying pathology and should be weighed against patient-specific risks.

From ARDS to pulmonary fibrosis: the next phase of the COVID-19 pandemic?

While the coronavirus disease 19 (COVID-19) pandemic has transformed the medical and scientific communites since it was first reported in late 2019, we are only beginning to understand the chronic health burdens associated with this disease. Although COVID-19 is a multi-systemic disease, the lungs are the primary source of infection and injury, resulting in pneumonia and, in severe cases, acute respiratory distress syndrome (ARDS). Given that pulmonary fibrosis is a well-recognized sequela of ARDS, many have questioned whether COVID-19 survivors will face long-term pulmonary consequences. This review is aimed at integrating our understanding of the pathophysiologic mechanisms underlying fibroproliferative ARDS with our current knowledge of the pulmonary consequences of COVID-19 disease.

Potential therapeutic interventions of plant-derived isoflavones against acute lung injury

Acute lung injury (ALI) is a life-threatening syndrome that possibly leads to high morbidity and mortality as no therapy exists. Several natural ingredients with negligible adverse effects have recently been investigated to possibly inhibit the inflammatory pathways associated with ALI at the molecular level. Isoflavones, as phytoestrogenic compounds, are naturally occurring bioactive compounds that represent the most abundant category of plant polyphenols (Leguminosae family). A broad range of therapeutic activities of isoflavones, including antioxidants, chemopreventive, anti-inflammatory, antiallergic and antibacterial potentials, have been extensively documented in the literature. Our review exclusively focuses on the possible anti-inflammatory, antioxidant role of botanicals'-derived isoflavones against ALI and their immunomodulatory effect in experimentally induced ALI. Despite the limited scope covering their molecular mechanisms, isoflavones substantially contributed to protecting from ALI via inhibiting toll-like receptor 4 (TLR4)/Myd88/NF-κB pathway and subsequent cytokines, chemokines, and adherent proteins. Nonetheless, future research is suggested to fill the gap in elucidating the protective roles of isoflavones to alleviate ALI concerning antioxidant potentials, inhibition of the inflammatory pathways, and associated molecular mechanisms.

Critical Role of Mortalin/GRP75 in Endothelial Cell Dysfunction Associated with Acute Lung Injury

Mortalin/GRP75 (glucose regulated protein 75), a member of heat shock protein 70 family of chaperones, is involved in several cellular processes including proliferation and signaling, and plays a pivotal role in cancer and neurodegenerative disorders. In this study, we sought to determine the role of mortalin/GRP75 in mediating vascular inflammation and permeability linked to the pathogenesis of acute lung injury (ALI). In an aerosolized bacterial lipopolysaccharide inhalation mouse model of ALI, we found that administration of mortalin/GRP75 inhibitor mean kinetic temperature-077, both prophylactically and therapeutically, protected against polymorphonuclear leukocytes influx into alveolar airspaces, microvascular leakage, and expression of pro-inflammatory mediators such as interleukin-1β, E-selectin, and tumor necrosis factor TNFα. Consistent with this, thrombin-induced inflammation in cultured human endothelial cells (EC) was also protected upon before and after treatment with mean kinetic temperature-077. Similar to pharmacological inhibition of mortalin/GRP75, siRNA-mediated depletion of mortalin/GRP75 also blocked thrombin-induced expression of proinflammatory mediators such as intercellular adhesion molecule-1 and vascular adhesion molecule-1. Mechanistic analysis in EC revealed that inactivation of mortalin/GRP75 interfered with the binding of the liberated NF-κB to the DNA, thereby leading to inhibition of downstream expression of adhesion molecules, cytokines, and chemokines. Importantly, thrombin-induced Ca signaling and EC permeability were also prevented upon mortalin/GRP75 inactivation/depletion. Thus, this study provides evidence for a novel role of mortalin/GRP75 in mediating EC inflammation and permeability associated with ALI.

NLRP3 and Infections: β-Amyloid in Inflammasome beyond Neurodegeneration

Amyloid beta (Aβ)-induced abnormal neuroinflammation is recognized as a major pathological feature of Alzheimer’s disease (AD), which results in memory impairment. Research exploring low-grade systemic inflammation and its impact on the development and progression of neurodegenerative disease has increased. A particular research focus has been whether systemic inflammation arises only as a secondary effect of disease, or it is also a cause of pathology. The inflammasomes, and more specifically the NLRP3 inflammasome, are crucial components of the innate immune system and are usually activated in response to infection or tissue damage. Although inflammasome activation plays critical roles against various pathogens in host defense, overactivation of inflammasome contributes to the pathogenesis of inflammatory diseases, including acute central nervous system (CNS) injuries and chronic neurodegenerative diseases, such as AD. This review summarizes the current literature on the role of the NLRP3 inflammasome in the pathogenesis of AD, and its involvement in infections, particularly SARS-CoV-2. NLRP3 might represent the crossroad between the hypothesized neurodegeneration and the primary COVID-19 infection.

Standardization of methods for sampling the distal airspace in mechanically ventilated patients using heat moisture exchange filter fluid

Noninvasive sampling of the distal airspace in patients with acute respiratory distress syndrome (ARDS) has long eluded clinical and translational researchers. We recently reported that fluid collected from heat moisture exchange (HME) filters closely mirrors fluid directly aspirated from the distal airspace. In the current study, we sought to determine fluid yield from different HME types, optimal HME circuit dwell time, and reliability of HME fluid in reflecting the distal airspace. We studied fluid yield from four different filter types by loading increasing volumes of saline and measuring volumes of fluid recovered. We collected filters after 1, 2, and 4 h of dwell time for measurement of fluid volume and total protein from 13 subjects. After identifying 4 h as the optimal dwell time, we measured total protein and IgM in HME fluid from 42 subjects with ARDS and nine with hydrostatic pulmonary edema (HYDRO). We found that the fluid yield varies greatly by filter type. With timed sample collection, fluid recovery increased with increasing circuit dwell time with a median volume of 2.0 mL [interquartile range (IQR) 1.2-2.7] after 4 h. Total protein was higher in the 42 subjects with ARDS compared with nine with HYDRO [median 708 µg/mL (IQR 244-2017) vs. 364 µg/mL (IQR 136-578), P = 0.047], confirming that total protein concentration in HME is higher in ARDS compared with hydrostatic edema. These studies establish a standardized HME fluid collection protocol and confirm that HME fluid analysis is a novel noninvasive tool for the study of the distal airspace in ARDS.

Chronic inflammation of middle ear cholesteatoma promotes its recurrence via a paracrine mechanism

Background

Cholesteatoma disease is an expanding lesion in the middle ear. Hearing loss and facial paralysis alongside with other intracranial complications are found. No pharmaceutical treatment is available today and recurrence after surgical extraction occurs. We investigated possible TLR4-based mechanisms promoting recurrence and explore possible treatments strategies.

Methods

We isolated fibroblasts and epidermal stem cells from cholesteatoma tissue and healthy auditory canal skin. Subsequently, their expression under standard culture conditions and after stimulation with LPS was investigated by RT-qPCR. Cell metabolism and proliferation were analysed upon LPS treatment, with and without TLR4 antagonist. An indirect co-culture of fibroblasts and epidermal stem cells isolated from cholesteatoma tissue was utilized to monitor epidermal differentiation upon LPS treatment by RT-qPCR and immunocytochemistry.

Results

Under standard culture conditions, we detected a tissue-independent higher expression of IL-1β and IL-8 in stem cells, an upregulation of KGF and IGF-2 in both cell types derived from cholesteatoma and higher expression of TLR4 in stem cells derived from cholesteatoma tissue. Upon LPS challenge, we could detect a significantly higher expression of IL-1α, IL-1β, IL-6 and IL-8 in stem cells and of TNF-a, GM-CSF and CXCL-5 in stem cells and fibroblasts derived from cholesteatoma. The expression of the growth factors KGF, EGF, EREG, IGF-2 and HGF was significantly higher in fibroblasts, particularly when derived from cholesteatoma. Upon treatment with LPS the metabolism was elevated in stem cells and fibroblasts, proliferation was only enhanced in fibroblasts derived from cholesteatoma. This could be reversed by the treatment with a TLR4 antagonist. The cholesteatoma fibroblasts could be triggered by LPS to promote the epidermal differentiation of the stem cells, while no LPS treatment or LPS treatment without the presence of fibroblasts did not result in such a differentiation.

Conclusion

We propose that cholesteatoma recurrence is based on TLR4 signalling imprinted in the cholesteatoma cells. It induces excessive inflammation of stem cells and fibroblasts, proliferation of perimatrix fibroblasts and the generation of epidermal cells from stem cells thru paracrine signalling by fibroblasts. Treatment of the operation site with a TLR4 antagonist might reduce the chance of cholesteatoma recurrence.

Epigenetic underpinnings of inflammation: Connecting the dots between pulmonary diseases, lung cancer and COVID-19

Inflammation is an essential component of several respiratory diseases, such as chronic obstructive pulmonary disease (COPD), asthma and acute respiratory distress syndrome (ARDS). It is central to lung cancer, the leading cancer in terms of associated mortality that has affected millions of individuals worldwide. Inflammation and pulmonary manifestations are also the major causes of COVID-19 related deaths. Acute hyperinflammation plays an important role in the COVID-19 disease progression and severity, and development of protective immunity against the virus is greatly sought. Further, the severity of COVID-19 is greatly enhanced in lung cancer patients, probably due to the genes such as ACE2, TMPRSS2, PAI-1 and furin that are commonly involved in cancer progression as well as SAR-CoV-2 infection. The importance of inflammation in pulmonary manifestations, cancer and COVID-19 calls for a closer look at the underlying processes, particularly the associated increase in IL-6 and other cytokines, the dysregulation of immune cells and the coagulation pathway. Towards this end, several reports have identified epigenetic regulation of inflammation at different levels. Expression of several key inflammation-related cytokines, chemokines and other genes is affected by methylation and acetylation while non-coding RNAs, including microRNAs as well as long non-coding RNAs, also affect the overall inflammatory responses. Select miRNAs can regulate inflammation in COVID-19 infection, lung cancer as well as other inflammatory lung diseases, and can serve as epigenetic links that can be therapeutically targeted. Furthermore, epigenetic changes also mediate the environmental factors-induced inflammation. Therefore, a better understanding of epigenetic regulation of inflammation can potentially help develop novel strategies to prevent, diagnose and treat chronic pulmonary diseases, lung cancer and COVID-19.

Qidonghuoxue Decoction Ameliorates Pulmonary Edema in Acute Lung Injury Mice through the Upregulation of Epithelial Sodium Channel and Aquaporin-1

QDHX decoction is an effective traditional Chinese medicine that has been used to treat ALI, a disease characterized by pulmonary edema and inflammation. In this study, the aim is to elucidate the molecular mechanisms of QDHX decoction on improving the alveolar-capillary membrane permeability and alleviating inflammatory response. The BALB/c mice were divided into five groups including the control group, ALI group, ALI + low-dose QDHX decoction, ALI + high-dose QDHX decoction, and ALI + dexamethasone. When the animals were sacrificed, the pathology and wet/dry of lung tissue were tested and confirmed Ali model, the LDH and nucleated cells in BALF, and TNF-α and IL-1β in serum; α-ENaC and AQP-1 in lung tissue were examined. In the results, QDHX decoction downregulated the cytokine such as TNF-α and IL-1β, reduced the nucleated cells, and some biochemical parameters of the BALF. It also ameliorated the ENaC-α and AQP-1 expression induced by LPS in primary epithelial cells. These findings may provide new insights into the application of QDHX decoction for the prevention and treatment of LPS-related ALI.

Systemic Markers of Monocyte Activation in Acute Pulmonary Oedema

BACKGROUND

Hydrostatic lung injury followed by pulmonary remodelling variably complicates cardiogenic acute pulmonary oedema (APO). Pulmonary remodelling may be regulated by the balance between distinct phenotypes of pulmonary macrophages; activated/inflammatory (M1), and reparative/anti-inflammatory (M2), derived from circulating monocyte populations. The aim of this study was to identify biomarkers in peripheral blood that are consistent with hydrostatic lung injury and pulmonary remodelling in APO and which follow the variable clinical course.

METHODS

To examine peripheral markers of lung inflammation, resolution and remodelling, 18 patients, admitted to the intensive care unit (ICU) with a clinical diagnosis of APO, were enrolled. Admission, 12- and 24-hour post-admission bloods were assayed for cytokines by ELISA (R&D Systems, Minneapolis, MN, USA) and leukocyte surface markers by flow cytometry.

RESULTS

Admission PaO₂ to FiO₂ ratio was positively correlated with Mon 2 (intermediate) monocyte prevalence, through increasing ratio of CD16⁺ monocytes to CD11b⁺ and CD40⁺ monocytes, and negatively correlated with Mon 1 (classical) monocyte prevalence, through decreasing ratio of CD16⁺ monocytes to CD62L⁺. Secondary cohort analysis compared 10 APO patients with established chronic heart failure (CHF) to eight without CHF. An increase in monocyte chemotactic peptide (MCP)-1, monocyte prevalence, and CD16^-CD62L⁺ monocytes with CHF, all characteristic of monocyte activation to a Mon 1 phenotype, were found in the CHF APO patients.

CONCLUSIONS

Increased systemic monocyte prevalence and expression of cell surface markers suggest a Mon 1 profile in CHF patients during episodes of APO. Future studies should define the role of systemic monocyte prevalence and activation in decompensated CHF.

Targeting the NLRP3 Inflammasome in Severe COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a member of the genus Betacoronavirus within the family Coronaviridae. It is an enveloped single-stranded positive-sense RNA virus. Since December of 2019, a global expansion of the infection has occurred with widespread dissemination of coronavirus disease 2019 (COVID-19). COVID-19 often manifests as only mild cold-like symptomatology, but severe disease with complications occurs in 15% of cases. Respiratory failure occurs in severe disease that can be accompanied by a systemic inflammatory reaction characterized by inflammatory cytokine release. In severe cases, fatality is caused by the rapid development of severe lung injury characteristic of acute respiratory distress syndrome (ARDS). Although ARDS is a complication of SARS-CoV-2 infection, it is not viral replication or infection that causes tissue injury; rather, it is the result of dysregulated hyperinflammation in response to viral infection. This pathology is characterized by intense, rapid stimulation of the innate immune response that triggers activation of the Nod-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome pathway and release of its products including the proinflammatory cytokines IL-6 and IL-1β. Here we review the literature that describes the pathogenesis of severe COVID-19 and NLRP3 activation and describe an important role in targeting this pathway for the treatment of severe COVID-19.

HIP/PAP protects against bleomycin-induced lung injury and inflammation and subsequent fibrosis in mice

Hepatocarcinoma‐intestine‐pancreas/pancreatitis‐associated protein (HIP/PAP), a C‐type lectin, exerts anti‐oxidative, anti‐inflammatory, bactericidal, anti‐apoptotic, and mitogenic functions in several cell types and tissues. In this study, we explored the role of HIP/PAP in pulmonary fibrosis (PF). Expression of HIP/PAP and its murine counterpart, Reg3B, was markedly increased in fibrotic human and mouse lung tissues. Adenovirus‐mediated HIP/PAP expression markedly alleviated bleomycin (BLM)‐induced lung injury, inflammation, and fibrosis in mice. Adenovirus‐mediated HIP/PAP expression alleviated oxidative injury and lessened the decrease in pulmonary superoxide dismutase (SOD) activity in BLM‐treated mice, increased pulmonary SOD expression in normal mice, and HIP/PAP upregulated SOD expression in cultured human alveolar epithelial cells (A549) and human lung fibroblasts (HLF‐1). Moreover, in vitro experiments showed that HIP/PAP suppressed the growth of HLF‐1 and ameliorated the H₂O₂‐induced apoptosis of human alveolar epithelial cells (A549 and HPAEpiC) and human pulmonary microvascular endothelial cells (HPMVEC). In HLF‐1, A549, HPAEpiC, and HPMVEC cells, HIP/PAP did not affect the basal levels, but alleviated the TGF‐β1‐induced down‐regulation of the epithelial/endothelial markers E‐cadherin and vE‐cadherin and the over‐expression of mesenchymal markers, such as α‐SMA and vimentin. In conclusion, HIP/PAP was found to serve as a potent protective factor in lung injury, inflammation, and fibrosis by attenuating oxidative injury, promoting the regeneration of alveolar epithelial cells, and antagonizing the pro‐fibrotic actions of the TGF‐β1/Smad signaling pathway.

Molecular determinants of mesenchymal cell activation in fibroproliferative diseases

Uncontrolled scarring, or fibrosis, can interfere with the normal function of virtually all tissues of the body, ultimately leading to organ failure and death. Fibrotic diseases represent a major cause of death in industrialized countries. Unfortunately, no curative treatments for these conditions are yet available, highlighting the critical need for a better fundamental understanding of molecular mechanisms that may be therapeutically tractable. The ultimate indispensable effector cells responsible for deposition of extracellular matrix proteins that comprise scars are mesenchymal cells, namely fibroblasts and myofibroblasts. In this review, we focus on the biology of these cells and the molecular mechanisms that regulate their pertinent functions. We discuss key pro-fibrotic mediators, signaling pathways, and transcription factors that dictate their activation and persistence. Because of their possible clinical and therapeutic relevance, we also consider potential brakes on mesenchymal cell activation and cellular processes that may facilitate myofibroblast clearance from fibrotic tissue-topics that have in general been understudied.

Lung inflammatory environments differentially alter mesenchymal stromal cell behavior

Mesenchymal stromal (stem) cells (MSCs) are increasingly demonstrated to ameliorate experimentally induced lung injuries through disease-specific anti-inflammatory actions, thus suggesting that different in vivo inflammatory environments can influence MSC actions. To determine the effects of different representative inflammatory lung conditions, human bone marrow–derived MSCs (hMSCs) were exposed to in vitro culture conditions from bronchoalveolar lavage fluid (BALF) samples obtained from patients with either the acute respiratory distress syndrome (ARDS) or with other lung diseases including acute respiratory exacerbations of cystic fibrosis (CF) (non-ARDS). hMSCs were subsequently assessed for time- and BALF concentration–dependent effects on mRNA expression of selected pro- and anti-inflammatory mediators, and for overall patterns of gene and mRNA expression. Both common and disease-specific patterns were observed in gene expression of different hMSC mediators, notably interleukin (IL)-6. Conditioned media obtained from non-ARDS BALF-exposed hMSCs was more effective in promoting an anti-inflammatory phenotype in monocytes than was conditioned media from ARDS BALF-exposed hMSCs. Neutralizing IL-6 in the conditioned media promoted generation of anti-inflammatory monocyte phenotype. This proof of concept study suggest that different lung inflammatory environments potentially can alter hMSC behaviors. Further identification of these interactions and the driving mechanisms may influence clinical use of MSCs for treating lung diseases.

Attenuation of hyperoxic acute lung injury by Lycium barbarum polysaccharide via inhibiting NLRP3 inflammasome

Lycium barbarum polysaccharide (LBP), an active component from Goji berry which is a traditional Chinese medicine, has anti-inflammatory and antioxidant features. The aim of our study was to investigate whether LBP has any role in hyperoxia-induced acute lung injury (ALI). Using a murine model of hyperoxia-induced ALI, we investigate the effect of LBP on pulmonary pathological changes as well as Sirtuin 1 (SIRT1) and the nucleotide binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome. Exposure to 100% oxygen for 72 h in male C57BL/6 mice resulted in increased protein levels of tumor necrosis factor-α and interleukin-1β in lung tissues, and aggravated lung histological alterations. These hyperoxia-induced changes and mortality were improved by LBP. LBP markedly suppressed the activation of NLRP3 inflammasome both in vivo and in vitro. Moreover, LBP upregulated SIRT1 expression compared with vehicle-treated group. Importantly, knockdown of SIRT1 reversed the inhibitory effect of LBP on NLRP3 inflammasome activation in vitro. LBP meliorated hyperoxia-induced ALI in mice by SIRT1-dependent inhibition of NLRP3 inflammasome activation.

Interleukin-6 is required for Neuregulin-1 induced HER2 signaling in lung epithelium

A clear understanding of the mechanisms that regulate the alveolar epithelium's barrier is critical to develop new therapeutic strategies to mitigate lung injury. The HER2/HER3 receptor tyrosine kinase complex plays a central role in maintaining the alveolar-capillary barrier. This receptor complex is activated by its ligand, neuregulin-1 (NRG-1). Interleukin-6 (IL-6) is also known to induce HER2 signaling through HER2 transphosphorylation by the IL-6 receptor (IL-6R) complex (1). Due to this interaction, we hypothesized that NRG-1 and IL-6 cooperatively interacted to activate the HER2/HER3 complex. Studies were performed in cultured pulmonary epithelial cells measuring the HER2/IL-6/IL-6R/GP130 interaction and receptor activation by western blotting and confocal microscopy, IL-6 production by ELISA, and IL-6 inhibition using specific antibodies, small molecule inhibitors and shRNA. We found that IL-6 was required for NRG-1 induced activation of HER2 in pulmonary epithelial cells. IL-6 inhibition led to a decrease in NRG-1 induced HER2 activation. The IL-6R and GP130, a subunit of the IL-6R complex, were physically associated with HER2 and were required for NRG-1 induced HER2 activation. Inhibition of GP130, the β-subunit of the IL-6 receptor decreased NRG-1 induced HER2 activation lower than control by 38% Finally, HER2 activation increased IL-6 secretion more than two-fold over resting cells (526 ± 131 vs 231 ± 39.7 pg/ml), and inhibition of HER2 gene expression decreased basal IL-6 secretion over 80% (89 + 4.6 vs 1.3 + 0.8 pg/ml). These findings identify a requirement for IL-6 and the IL-6R complex to allow NRG-1 mediated HER2 activation, and a HER2 driven IL-6 production feedback loop.

Pathogenesis of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a syndrome of acute respiratory failure caused by noncardiogenic pulmonary edema. Despite five decades of basic and clinical research, there is still no effective pharmacotherapy for this condition and the treatment remains primarily supportive. It is critical to study the molecular and physiologic mechanisms that cause ARDS to improve our understanding of this syndrome and reduce mortality. The goal of this review is to describe our current understanding of the pathogenesis and pathophysiology of ARDS. First, we will describe how pulmonary edema fluid accumulates in ARDS due to lung inflammation and increased alveolar endothelial and epithelial permeabilities. Next, we will review how pulmonary edema fluid is normally cleared in the uninjured lung, and describe how these pathways are disrupted in ARDS. Finally, we will explain how clinical trials and preclinical studies of novel therapeutic agents have further refined our understanding of this condition, highlighting, in particular, the study of mesenchymal stromal cells in the treatment of ARDS.

Bone marrow mesenchymal stem cells tune the differentiation of myeloid-derived suppressor cells in bleomycin-induced lung injury

Background

Bone marrow mesenchymal stem cells (BMSC) transfer has been attempted as a therapeutic strategy in experimental lung injury and fibrosis. Reduction of neutrophilic infiltration is one of the mechanisms involved in this effect. However, the mechanisms by which BMSC modulate neutrophil remains unknown.

Methods and results

Exposure of mice to bleomycin (BLM) resulted in significant accumulation of cells that express neutrophilic markers Gr-1^HighCD11b⁺Ly-6G^HighF4/80^―CD115^―CD49d^―. These cells lacked immunosuppressive activity and could not be defined as myeloid-derived suppressor cells (MDSC). When BMSC were administrated to BLM-treated mice, they tuned the differentiation of Gr-1^HighCD11b⁺ toward Gr-1^LowCD11b⁺ cells. Gr-1^LowCD11b⁺ cells exhibited unsegmented nuclei and expressed F4/80, Ly-6C, CD49d, and CD115 markers. These cells had potent immunosuppressive activity and thus could be defined as monocytic MDSC. As a result of such immunoregulation, BMSC mediated a decrease of pro-inflammatory products and amelioration of lung injury in BLM-treated mice. Further study using antibody array showed increased expression of macrophage colony-stimulating factor (M-CSF) in BMSC-treated mice. Accumulation of Gr-1^LowCD11b⁺ cells in BMSC-treated mice was abrogated in M-CSF neutralizing mice. The beneficial effect of BMSC was independent of the ability of the cells to engraft in lung and in vitro coculture study of BMSC with Gr-1⁺CD11b⁺ cells showed that the induction of Gr-1^LowCD11b⁺ cells by BMSC was independent of cell-cell contact.

Conclusions

These results document the generation of Gr-1^HighCD11b⁺ cells in BLM-treated mice, and suggest that BMSC tune the differentiation of Gr-1^HighCD11b⁺ toward Gr-1^LowCD11b⁺ cells and therefore inhibit the progression of BLM-induced lung injury.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0983-1) contains supplementary material, which is available to authorized users.

Specialized Pro-resolving Mediators Regulate Alveolar Fluid Clearance during Acute Respiratory Distress Syndrome

Objective

Acute respiratory distress syndrome (ARDS) is an acute and lethal clinical syndrome that is characterized by the injury of alveolar epithelium, which impairs active fluid transport in the lung, and impedes the reabsorption of edema fluid from the alveolar space. This review aimed to discuss the role of pro-resolving mediators on the regulation of alveolar fluid clearance (AFC) in ARDS.

Data Sources

Articles published up to September 2017 were selected from the PubMed, with the keywords of "alveolar fluid clearance" or "lung edema" or "acute lung injury" or "acute respiratory distress syndrome", and "specialized pro-resolving mediators" or "lipoxin" or "resolvin" or "protectin" or "maresin" or "alveolar epithelial cells" or "aspirin-triggered lipid mediators" or "carbon monoxide and heme oxygenase" or "annexin A1".

Study Selection

We included all relevant articles published up to September 2017, with no limitation of study design.

Results

Specialized pro-resolving mediators (SPMs), as the proinflammatory mediators, not only upregulated epithelial sodium channel, Na,K-ATPase, cystic fibrosis transmembrane conductance regulator (CFTR), and aquaporins levels, but also improved Na,K-ATPase activity to promote AFC in ARDS. In addition to the direct effects on ion channels and pumps of the alveolar epithelium, the SPMs also inhibited the inflammatory cytokine expression and improved the alveolar epithelial cell repair to enhance the AFC in ARDS.

Conclusions

The present review discusses a novel mechanism for pulmonary edema fluid reabsorption. SPMs might provide new opportunities to design "reabsorption-targeted" therapies with high degrees of precision in controlling ALI/ARDS.

SOCS-1 rescues IL-1β-mediated suppression of epithelial sodium channel in mouse lung epithelial cells via ASK-1

Background

Acute lung injury (ALI) is characterized by alveolar damage, increased levels of pro-inflammatory cytokines and impaired alveolar fluid clearance. Recently, we showed that the deletion of Apoptosis signal-regulating kinase 1 (ASK1) protects against hyperoxia-induced acute lung injury (HALI) by suppressing IL-1β and TNF-α. Previously, our data revealed that the suppressor of cytokine signaling-1 (SOCS-1) overexpression restores alveolar fluid clearance in HALI by inhibiting ASK-1 and suppressing IL-1β levels. Furthermore, IL-1β is known to inhibit the expression of epithelial sodium channel α-subunit (ENaC) via a p38 MAPK signaling pathway.

Objective

To determine whether SOCS-1 overexpression in MLE-12 cells would protect against IL-1β-mediated depletion of αENaC by suppressing ASK-1 expression.

Methods

We co-transfected MLE-12 cells with SOCS-1 overexpressing plasmid with or without IL-1β in the presence or absence of sodium channel inhibitor, amiloride. We measured potential difference, transepithelial current, resistance, and sodium uptake levels across MLE-12 cells. We studied the effect of ASK-1 depletion, as well as ASK-1 and SOCS-1 overexpression on αENaC expression.

Results

SOCS-1 overexpression sufficiently restored transepithelial current and resistance in MLE-12 cells treated with either IL-1β or amiloride. The αENaC mRNA levels and sodium transport were increased in SOCS-1 overexpressing MLE-12 cells exposed to IL-1β. Depletion of ASK-1 in MLE-12 cells increased αENaC mRNA levels. Interestingly, SOCS-1 overexpression restored αENaC expression in MLE-12 cells in the presence of ASK-1 overexpression.

Conclusion

Collectively, these findings suggest that SOCS-1 may exert its protective effect by rescuing αENaC expression via suppression of ASK-1.

Fluid Management in Lung Transplant Patients

Overall, there is a lack of randomized controlled trials examining the correlation between fluid volume delivery and outcomes in postoperative lung transplant patients. However, using thoracic surgery patients as a guide, the evidence suggests that hypervolemia correlates with pulmonary edema and should be avoided in lung transplant patients. However, it is recognized that patients with hemodynamic instability may require volume for attenuation of this situation, but it can likely be mitigated with the use of inotropic medication to maintain adequate perfusion and avoid the development of edema.

Annexin A2 contributes to lung injury and fibrosis by augmenting factor Xa fibrogenic activity

In lung injury and disease, including idiopathic pulmonary fibrosis (IPF), extravascular factor X is converted into factor Xa (FXa), a coagulant protease with fibrogenic actions. Extracellular annexin A2 binds to FXa, augmenting activation of the protease-activated receptor-1 (PAR-1). In this study, the contribution of annexin A2 in lung injury and fibrosis was investigated. Annexin A2 immunoreactivity was observed in regions of fibrosis, including those associated with fibroblasts in lung tissue of IPF patients. Furthermore, annexin A2 was detected in the conditioned media and an EGTA membrane wash of human lung fibroblast (LF) cultures. Incubation with human plasma (5% vol/vol) or purified FXa (15–50 nM) evoked fibrogenic responses in LF cultures, with FXa increasing interleukin-6 (IL-6) production and cell number by 270 and 46%, respectively ( P < 0.05, n = 5–8). The fibrogenic actions of plasma or FXa were attenuated by the selective FXa inhibitor apixaban (10 μM, or antibodies raised against annexin A2 or PAR-1 (2 μg/ml). FXa-stimulated LFs from IPF patients ( n = 6) produced twice as much IL-6 as controls ( n = 10) ( P < 0.05), corresponding with increased levels of extracellular annexin A2. Annexin A2 gene deletion in mice reduced bleomycin-induced increases in bronchoalveolar lavage fluid (BALF) IL-6 levels and cell number (* P < 0.05; n = 4–12). Lung fibrogenic gene expression and dry weight were reduced by annexin A2 gene deletion, but lung levels of collagen were not. Our data suggest that annexin A2 contributes to lung injury and fibrotic disease by mediating the fibrogenic actions of FXa. Extracellular annexin A2 is a potential target for the treatment of IPF.

Inflammatory Responses Regulating Alveolar Ion Transport during Pulmonary Infections

The respiratory epithelium is lined by a tightly balanced fluid layer that allows normal O₂ and CO₂ exchange and maintains surface tension and host defense. To maintain alveolar fluid homeostasis, both the integrity of the alveolar–capillary barrier and the expression of epithelial ion channels and pumps are necessary to establish a vectorial ion gradient. However, during pulmonary infection, auto- and/or paracrine-acting mediators induce pathophysiological changes of the alveolar–capillary barrier, altered expression of epithelial Na,K-ATPase and of epithelial ion channels including epithelial sodium channel and cystic fibrosis membrane conductance regulator, leading to the accumulation of edema and impaired alveolar fluid clearance. These mediators include classical pro-inflammatory cytokines such as TGF-β, TNF-α, interferons, or IL-1β that are released upon bacterial challenge with Streptococcus pneumoniae, Klebsiella pneumoniae, or Mycoplasma pneumoniae as well as in viral infection with influenza A virus, pathogenic coronaviruses, or respiratory syncytial virus. Moreover, the pro-apoptotic mediator TNF-related apoptosis-inducing ligand, extracellular nucleotides, or reactive oxygen species impair epithelial ion channel expression and function. Interestingly, during bacterial infection, alterations of ion transport function may serve as an additional feedback loop on the respiratory inflammatory profile, further aggravating disease progression. These changes lead to edema formation and impair edema clearance which results in suboptimal gas exchange causing hypoxemia and hypercapnia. Recent preclinical studies suggest that modulation of the alveolar–capillary fluid homeostasis could represent novel therapeutic approaches to improve outcomes in infection-induced lung injury.

Alveolar Fluid Clearance in Pathologically Relevant Conditions: In Vitro and In Vivo Models of Acute Respiratory Distress Syndrome

Critically ill patients with respiratory failure from acute respiratory distress syndrome (ARDS) have reduced ability to clear alveolar edema fluid. This reduction in alveolar fluid clearance (AFC) contributes to the morbidity and mortality in ARDS. Thus, it is important to understand why AFC is reduced in ARDS in order to design targeted therapies. In this review, we highlight experiments that have advanced our understanding of ARDS pathogenesis, with particular reference to the alveolar epithelium. First, we review how vectorial ion transport drives the clearance of alveolar edema fluid in the uninjured lung. Next, we describe how alveolar edema fluid is less effectively cleared in lungs affected by ARDS and describe selected in vitro and in vivo experiments that have elucidated some of the molecular mechanisms responsible for the reduced AFC. Finally, we describe one potential therapy that targets this pathway: bone marrow-derived mesenchymal stem (stromal) cells (MSCs). Based on preclinical studies, MSCs enhance AFC and promote the resolution of pulmonary edema and thus may offer a promising cell-based therapy for ARDS.

Cytokine-Regulation of Na+-K+-Cl- Cotransporter 1 and Cystic Fibrosis Transmembrane Conductance Regulator-Potential Role in Pulmonary Inflammation and Edema Formation

Pulmonary edema, a major complication of lung injury and inflammation, is defined as accumulation of extravascular fluid in the lungs leading to impaired diffusion of respiratory gases. Lung fluid balance across the alveolar epithelial barrier protects the distal airspace from excess fluid accumulation and is mainly regulated by active sodium transport and Cl^- absorption. Increased hydrostatic pressure as seen in cardiogenic edema or increased vascular permeability as present in inflammatory lung diseases such as the acute respiratory distress syndrome (ARDS) causes a reversal of transepithelial fluid transport resulting in the formation of pulmonary edema. The basolateral expressed Na⁺-K⁺-2Cl^- cotransporter 1 (NKCC1) and the apical Cl^- channel cystic fibrosis transmembrane conductance regulator (CFTR) are considered to be critically involved in the pathogenesis of pulmonary edema and have also been implicated in the inflammatory response in ARDS. Expression and function of both NKCC1 and CFTR can be modulated by released cytokines; however, the relevance of this modulation in the context of ARDS and pulmonary edema is so far unclear. Here, we review the existing literature on the regulation of NKCC1 and CFTR by cytokines, and-based on the known involvement of NKCC1 and CFTR in lung edema and inflammation-speculate on the role of cytokine-dependent NKCC1/CFTR regulation for the pathogenesis and potential treatment of pulmonary inflammation and edema formation.

Chronic microaspiration of bile acids induces lung fibrosis through multiple mechanisms in rats

Gastroesophageal reflux (GER) and microaspiration of duodenogastric refluxate have been recognized as a risk factor for pulmonary fibrosis. Recent evidence suggests that bile acid microaspiration may contribute to the development of lung fibrosis. However, the molecular evidence is scarce and the underlying mechanisms remain to be elucidated. We have recently demonstrated that bile acids induce activation of alveolar epithelial cells (AECs) and lung fibroblasts in vitro In the present study, a rat model of bile acid microaspiration was established by weekly intratracheal instillation of three major bile acids including chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), and lithocholic acid (LCA). Repeated microaspiration of CDCA, DCA, and LCA caused fibrotic changes, including alveolar wall thickening and extensive collagen deposition, in rat lungs. Bile acid microaspiration also induced alveolar epithelial-mesenchymal transition (EMT), as indicated by up-regulation of mesenchymal markers α-smooth muscle actin (α-SMA) and vimentin, as well as down-regulaton of epithelial markers E-cadherin and cytokeratin in alveolar epithelium of rat lungs. The expression of fibrogenic mediators, including transforming growth factor-β1 (TGF-β1), connective tissue growth factor (CTGF), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and periostin, was significantly elevated in rat lungs exposed to microaspiration of bile acids. Furthermore, microaspiration of bile acids also induced p-Smad3 and farnesoid X receptor (FXR) expression in rat lungs. Our findings suggest that microaspiration of bile acids could promote the development of pulmonary fibrosis in vivo, possibly via stimulating fibrogenic mediator expression and activating TGF-β1/Smad3 signaling and FXR.

The fibrogenic actions of lung fibroblast-derived urokinase: a potential drug target in IPF

The role of urokinase plasminogen activator (uPA) in idiopathic pulmonary fibrosis (IPF) remains unclear. uPA-generated plasmin has potent fibrogenic actions involving protease activated receptor-1 (PAR-1) and interleukin-6 (IL-6). Here we characterize uPA distribution or levels in lung tissue and sera from IPF patients to establish the mechanism of its fibrogenic actions on lung fibroblasts (LFs). uPA immunoreactivity was detected in regions of fibrosis including fibroblasts of lung tissue from IPF patients (n = 7). Serum uPA levels and activity were also higher in IPF patients (n = 18) than controls (n = 18) (P < 0.05), being negatively correlated with lung function as measured by forced vital capacity (FVC) %predicted (P < 0.05). The culture supernatants of LFs from IPF patients, as compared to controls, showed an increase in plasmin activity after plasminogen incubation (5–15 μg/mL), corresponding with increased levels of uPA and IL-6 (n = 5–6, P < 0.05). Plasminogen-induced increases in plasmin activity and IL-6 levels were attenuated by reducing uPA and/or PAR-1 expression by RNAi. Plasmin(ogen)-induced mitogenesis was also attenuated by targeting uPA, PAR-1 or IL-6. Our data shows uPA is formed in active regions of fibrosis in IPF lung and contributes to LF plasmin generation, IL-6 production and proliferation. Urokinase is a potential target for the treatment of lung fibrosis.

Bile acids induce activation of alveolar epithelial cells and lung fibroblasts through farnesoid X receptor-dependent and independent pathways

BACKGROUND AND OBJECTIVE

The roles of bile acid microaspiration and bile acid-activated farnesoid X receptor (FXR) in the pathogenesis of idiopathic pulmonary fibrosis (IPF) remain unclear. We hypothesized that bile acids activate alveolar epithelial cells (AECs) and lung fibroblasts, which may be regulated by FXR activation.

METHODS

Human AECs and normal or IPF-derived lung fibroblast cells were incubated with the three major bile acids: lithocholic acid (LCA), deoxycholic acid (DCA) and chenodeoxycholic acid (CDCA). The AECs injury indices, epithelial-mesenchymal transition (EMT) and lung fibroblast activation were evaluated. FXR expression in IPF lungs and the roles of FXR and FXR-independent pathways in bile acid-induced profibrotic effects were also investigated.

RESULTS

LCA, DCA and CDCA reduced cell viability and increased intracellular reactive oxygen species (ROS) production in A549 cells. They all induced EMT, as shown by enhanced α-SMA and vimentin and decreased E-cadherin levels. LCA directly induced differentiation of lung fibroblasts to myofibroblasts. All three bile acids promoted cellular migration but not proliferation of lung fibroblasts. FXR expression was upregulated in IPF lungs, and inhibition of FXR restrained the bile acid-induced EMT and lung fibroblast activation. Differentiation and proliferation were enhanced in lung fibroblasts exposed to conditioned medium from bile acid-stimulated A549 cells, which contained increased levels of profibrotic factors. TGF-β/Smad3 signaling was also involved in the bile acid-induced EMT and lung fibroblast differentiation.

CONCLUSION

Bile acid microaspiration may promote the development of pulmonary fibrosis by inducing activation of AECs and lung fibroblasts via FXR-dependent and independent pathways.

Proteomic study of acute respiratory distress syndrome: current knowledge and implications for drug development

The acute respiratory distress syndrome (ARDS) is a common cause of acute respiratory failure, and is associated with substantial mortality and morbidity. Dozens of clinical trials targeting ARDS have failed, with no drug specifically targeting lung injury in widespread clinical use. Thus, the need for drug development in ARDS is great. Targeted proteomic studies in ARDS have identified many key pathways in the disease, including inflammation, epithelial injury, endothelial injury or activation, and disordered coagulation and repair. Recent studies reveal the potential for proteomic changes to identify novel subphenotypes of ARDS patients who may be most likely to respond to therapy and could thus be targeted for enrollment in clinical trials. Nontargeted studies of proteomics in ARDS are just beginning and have the potential to identify novel drug targets and key pathways in the disease. Proteomics will play an important role in phenotyping of patients and developing novel therapies for ARDS in the future.

Neuronal Wiskott-Aldrich syndrome protein regulates TGF-β1-mediated lung vascular permeability

TGF-β1 induces an increase in paracellular permeability and actin stress fiber formation in lung microvascular endothelial and alveolar epithelial cells via small Rho GTPase. The molecular mechanism involved is not fully understood. Neuronal Wiskott-Aldrich syndrome protein (N-WASP) has an essential role in actin structure dynamics. We hypothesized that N-WASP plays a critical role in these TGF-β1-induced responses. In these cell monolayers, we demonstrated that N-WASP down-regulation by short hairpin RNA prevented TGF-β1-mediated disruption of the cortical actin structure, actin stress filament formation, and increased permeability. Furthermore, N-WASP down-regulation blocked TGF-β1 activation mediated by IL-1β in alveolar epithelial cells, which requires actin stress fiber formation. Control short hairpin RNA had no effect on these TGF-β1-induced responses. TGF-β1-induced phosphorylation of Y256 of N-WASP via activation of small Rho GTPase and focal adhesion kinase mediates TGF-β1-induced paracellular permeability and actin cytoskeleton dynamics. In vivo, compared with controls, N-WASP down-regulation increases survival and prevents lung edema in mice induced by bleomycin exposure-a lung injury model in which TGF-β1 plays a critical role. Our data indicate that N-WASP plays a crucial role in the development of TGF-β1-mediated acute lung injury by promoting pulmonary edema via regulation of actin cytoskeleton dynamics.-Wagener, B. M., Hu, M., Zheng, A., Zhao, X., Che, P., Brandon, A., Anjum, N., Snapper, S., Creighton, J., Guan, J.-L., Han, Q., Cai, G.-Q., Han, X., Pittet, J.-F., Ding, Q. Neuronal Wiskott-Aldrich syndrome protein regulates TGF-β1-mediated lung vascular permeability.

Matrix-driven Myosin II Mediates the Pro-fibrotic Fibroblast Phenotype

Pro-fibrotic mesenchymal cells are known to be the key effector cells of fibroproliferative disease, but the specific matrix signals and the induced cellular responses that drive the fibrogenic phenotype remain to be elucidated. The key mediators of the fibroblast fibrogenic phenotype were characterized using a novel assay system that measures fibroblast behavior in response to actual normal and fibrotic lung tissue. Using this system, we demonstrate that normal lung promotes fibroblast motility and polarization, while fibrotic lung immobilizes the fibroblast and promotes myofibroblast differentiation. These context-specific phenotypes are surprisingly both mediated by myosin II. The role of myosin II is supported by the observation of an increase in myosin phosphorylation and a change in intracellular distribution in fibroblasts on fibrotic lung, as compared with normal lung. Moreover, loss of myosin II activity has opposing effects on protrusive activity in fibroblasts on normal and fibrotic lung. Loss of myosin II also selectively inhibits myofibroblast differentiation in fibroblasts on fibrotic lung. Importantly, these findings are recapitulated by varying the matrix stiffness of polyacrylamide gels in the range of normal and fibrotic lung tissue. Comparison of the effects of myosin inhibition on lung tissue with that of polyacrylamide gels suggests that matrix fiber organization drives the fibroblast phenotype under conditions of normal/soft lung, while matrix stiffness drives the phenotype under conditions of fibrotic/stiff lung. This work defines novel roles for myosin II as a key regulatory effector molecule of the pro-fibrotic phenotype, in response to biophysical properties of the matrix.

Microbubble-mediated ultrasound promotes accumulation of bone marrow mesenchymal stem cell to the prostate for treating chronic bacterial prostatitis in rats

Chronic bacterial prostatitis (CBP) is an intractable disease. Although bone marrow mesenchymal stem cells (BMMSCs) are able to regulate inflammation in CBP, the effect of microbubble-mediated ultrasound- induced accumulation of BMMSCs on CBP remains unclear. To address this gap, a model of CBP was established in SD rats, which were then treated with BMMSCs alone (BMMSC group), BMMSCs with ultrasound (ultrasound group), BMMSCs with microbubble-mediated ultrasound (MMUS group) and compared with a healthy control group. A therapeutic-ultrasound apparatus was used to treat the prostate in the presence of circulating microbubbles and BMMSCs. The BMMSC distribution was assessed with in vivo imaging, and the prostate structure with light microscopy. Real-time quantitative RT-PCR, ELISA, and immunohistochemistry were used to assess the expressions of TNF-α and IL-1β. More BMMSCs were found in the prostate in the MMUS group than in the CBP, ultrasound, and BMMSC groups. Inflammatory cell infiltration, fibrous tissue hyperplasia, and tumor-like epithelial proliferation were significantly reduced in the MMUS group, as were the mRNA and protein expressions of TNF-α and IL-1β. Microbubble-mediated ultrasound-induced accumulation of BMMSCs can inhibit inflammation and decrease TNF-α and IL-1β expressions in the prostate of CBP rats, suggesting that this method may be therapeutic for CPB.

Hirsutella sinensis mycelium attenuates bleomycin-induced pulmonary inflammation and fibrosis in vivo

Hirsutella sinensis mycelium (HSM), the anamorph of Cordyceps sinensis, is a traditional Chinese medicine that has been shown to possess various pharmacological properties. We previously reported that this fungus suppresses interleukin-1β and IL-18 secretion by inhibiting both canonical and non-canonical inflammasomes in human macrophages. However, whether HSM may be used to prevent lung fibrosis and the mechanism underlying this activity remain unclear. Our results show that pretreatment with HSM inhibits TGF-β1–induced expression of fibronectin and α-SMA in lung fibroblasts. HSM also restores superoxide dismutase expression in TGF-β1–treated lung fibroblasts and inhibits reactive oxygen species production in lung epithelial cells. Furthermore, HSM pretreatment markedly reduces bleomycin–induced lung injury and fibrosis in mice. Accordingly, HSM reduces inflammatory cell accumulation in bronchoalveolar lavage fluid and proinflammatory cytokines levels in lung tissues. The HSM extract also significantly reduces TGF-β1 in lung tissues, and this effect is accompanied by decreased collagen 3α1 and α-SMA levels. Moreover, HSM reduces expression of the NLRP3 inflammasome and P2X₇R in lung tissues, whereas it enhances expression of superoxide dismutase. These findings suggest that HSM may be used for the treatment of pulmonary inflammation and fibrosis.

Switch regulation of interleukin-1 beta in downstream of inflammatory cytokines induced by two micro-sized silica particles on differentiated THP-1 macrophages

To investigate the regulated role of IL-1β in initiating and maintaining inflammation, PMA-differentiated THP-1 macrophages were exposed to two micro-sized crystalline silica particles (Si3-5μm and Si1μm) from 3h to 24h, respectively. Cytotoxicity and inflammatory cytokines (IL-1β, TNF-α and IL-6) expressions measured showed that they were induced by both silica particles in positive dose-dependent manners. The levels of inflammatory cytokines induced by Si1μm were higher than those induced by Si3-5μm at low concentration. When pretreated with anti-human IL-1β, not only the high levels of IL-1β but also elevated TNF-α and IL-6 induced by both silica particles were remarkably blocked, especially Si1μm particle. In addition, recombinant human IL-1β protein could induce macrophages to strikingly augment TNF-α and IL-6 expressions. Our data suggest that IL-1β could play a critical role of switching regulation in the downstream inflammation induced by micro-sized silica particles.

Synergistic effect of bolus exposure to zinc oxide nanoparticles on bleomycin-induced secretion of pro-fibrotic cytokines without lasting fibrotic changes in murine lungs

Zinc oxide (ZnO) nanoparticles are widely used in various products, and the safety evaluation of this manufactured material is important. The present study investigated the inflammatory and fibrotic effects of pulmonary exposure to ZnO nanoparticles in a mouse model of pulmonary fibrosis. Pulmonary fibrosis was induced by constant subcutaneous infusion of bleomycin (BLM). Female C57BL/6Jcl mice were divided into BLM-treated and non-treated groups. In each treatment group, 0, 10, 20 or 30 µg of ZnO nanoparticles were delivered into the lungs through pharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and the lungs were sampled at Day 10 or 14 after administration. Pulmonary exposure by a single bolus of ZnO nanoparticles resulted in severe, but transient inflammatory infiltration and thickening of the alveolar septa in the lungs, along with the increase of total and differential cell counts in BLAF. The BALF level of interleukin (IL)-1β and transforming growth factor (TGF)-β was increased at Day 10 and 14, respectively. At Day 10, the synergistic effect of BLM and ZnO exposure was detected on IL-1β and monocyte chemotactic protein (MCP)-1 in BALF. The present study demonstrated the synergistic effect of pulmonary exposure to ZnO nanoparticles and subcutaneous infusion of BLM on the secretion of pro-fibrotic cytokines in the lungs.

Biological therapies in the acute respiratory distress syndrome

INTRODUCTION

The acute respiratory distress syndrome (ARDS) is characterised by life-threatening respiratory failure requiring mechanical ventilation, and multiple organ failure. It has a mortality of up to 30 - 45% and causes a long-term reduction in quality of life for survivors, with only approximately 50% of survivors able to return to work 12 months after hospital discharge.

AREAS COVERED

In this review we discuss the complex pathophysiology of ARDS, describe the mechanistic pathways implicated in the development of ARDS and how these are currently being targeted with novel biological therapies. These include therapies targeted against inflammatory cytokines, mechanisms mediating increased alveolar permeability and disordered coagulation, as well as the potential of growth factors, gene therapy and mesenchymal stem cells.

EXPERT OPINION

Although understanding of the pathophysiology of ARDS has improved, to date there are no effective pharmacological interventions that target a specific mechanism, with the only potentially effective therapies to date aiming to limit ventilator-associated lung injury. However, we believe that through this improved mechanistic insight and better clinical trial design, there is cautious optimism for the future of biological therapies in ARDS, and expect current and future biological compounds to provide treatment options to clinicians managing this devastating condition.

Autologous transplantation of adipose-derived stromal cells ameliorates ventilator-induced lung injury in rats

Background

Adipose-derived stromal cells (ADSCs) are a good alternative to multipotent stem cells for regenerative medicine. Low tidal volume (LVT) has proved to be an effective ventilation strategy. However, it is not known if ADSCs and LVT can protect against ventilator-induced lung injury (VILI). This study was aimed to determine the potential of ADSCs and LVT to repair following VILI and to elucidate the mechanisms responsible for this section.

Methods

A total of 72 rats were randomly assigned into group I (sham group, n = 18), group II (1 h of high tidal volume-ventilated (HVT) 40 mL/kg to peak airway pressures of approximately 35 cm H₂O and 100% oxygen, n = 18), group III (1 h of HVT followed by 6 h LVT 6 mL/kg to peak airway pressures of approximately 6 cm H₂O and 100% oxygen, n = 18) and group IV (1 h of HVT followed by intravenous injection of 5 × 10⁶ ADSCs, n = 18). All animals were sacrificed 7 after the experiments lasted for 7 hours. Bronchoalveolar lavage fluid (BALF) was collected and lungs were harvested for analysis.

Results

High tidal volume-ventilated (HVT) rats exhibited typical VILI features compared with sham rats. Lung edema, histological lung injury index, concentrations of total protein, total cell counts, number of neutrophils in bronchoalveolar lavage fluid (BALF), tumor necrosis factor-α, interleukin (IL)-1β, IL-6, IL-10 and transforming growth factor-β1 in BALF were significantly increased in HVT rats. Additionally, gene and protein levels of Na⁺ channel subunits, Na-K-ATPase pump activity and alveolar fluid clearance were significantly decreased in HVT rats. All these indices of VILI were significantly improved in rats treated with ADSCs. However, compared with ADSCs treatment, LVT strategy had little therapeutic effect in the present study.

Conclusion

These results may provide valuable insights into the effects of ADSCs in acute lung injury.

Mechanisms of acute respiratory distress syndrome in children and adults: a review and suggestions for future research

OBJECTIVES

To provide a current overview of the epidemiology and pathophysiology of acute respiratory distress syndrome in adults and children, and to identify research questions that will address the differences between adults and children with acute respiratory distress syndrome.

DATA SOURCES

Narrative literature review and author-generated data.

DATA SELECTION

The epidemiology of acute respiratory distress syndrome in adults and children, lung morphogenesis, and postnatal lung growth and development are reviewed. The pathophysiology of acute respiratory distress syndrome is divided into eight categories: alveolar fluid transport, surfactant, innate immunity, apoptosis, coagulation, direct alveolar epithelial injury by bacterial products, ventilator-associated lung injury, and repair.

DATA EXTRACTION AND SYNTHESIS

Epidemiologic data suggest significant differences in the prevalence and mortality of acute respiratory distress syndrome between children and adults. Postnatal lung development continues through attainment of adult height, and there is overlap between the regulation of postnatal lung development and inflammatory, apoptotic, alveolar fluid clearance, and repair mechanisms. Therefore, there is a different biological baseline network of gene and protein expression in children as compared with adults.

CONCLUSIONS

There are significant obstacles to performing research on children with acute respiratory distress syndrome. However, epidemiologic, clinical, and animal studies suggest age-dependent differences in the pathophysiology of acute respiratory distress syndrome. In order to reduce the prevalence and improve the outcome of patients with acute respiratory distress syndrome, translational studies of inflammatory, apoptotic, alveolar fluid clearance, and repair mechanisms are needed. Understanding the differences in pathophysiologic mechanisms in acute respiratory distress syndrome between children and adults should facilitate identification of novel therapeutic interventions to prevent or modulate lung injury and improve lung repair.

Activation of the heat shock response attenuates the interleukin 1β-mediated inhibition of the amiloride-sensitive alveolar epithelial ion transport

Acute lung injury (ALI) is a clinical syndrome characterized by hypoxia, which is caused by the breakdown of the alveolar capillary barrier. Interleukin 1β (IL-1β), a cytokine released within the airspace in ALI, downregulates the α subunit of the epithelial sodium channel (αENaC) transcription and protein expression via p38 MAP kinase-dependent signaling. Although induction of the heat shock response can restore alveolar fluid clearance compromised by IL-1β following the onset of severe hemorrhagic shock in rats, the mechanisms are not fully understood. In this study, we report that the induction of the heat shock response prevents IL-1β-dependent inhibition of αENaC mRNA expression and subsequent channel function. Heat shock results in IRAK1 detergent insolubility and a disruption of Hsp90 binding to IRAK1. Likewise, TAK1, another client protein of Hsp90 and signaling component of the IL-1β pathway, is also detergent insoluble after heat shock. Twenty-four hours after heat shock, both IRAK1 and TAK1 are again detergent soluble, which correlates with the IL-1β-dependent p38 activation. Remarkably, IL-1β-dependent p38 activation 24 h after heat shock did not result in an inhibition of αENaC mRNA expression and channel function. Further analysis demonstrates prolonged preservation of αENaC expression by the activation of the heat shock response that involves inducible Hsp70. Inhibition of Hsp70 at 24 h after heat shock results in p38-dependent IL-1β inhibition of αENaC mRNA expression, whereas overexpression of Hsp70 attenuates the p38-dependent IL-1β inhibition of αENaC mRNA expression. These studies demonstrate new mechanisms by which the induction of the heat shock response protects the barrier function of the alveolar epithelium in ALI.