The chemokine, CCL3, and its receptor, CCR1, mediate thoracic radiation-induced pulmonary fibrosis

Inflammatory Role of CCR1 in the Central Nervous System

BACKGROUND

Chemokine ligands and their corresponding receptors are essential for regulating inflammatory responses. Chemokine receptors can stimulate immune activation or inhibit/promote signaling pathways by binding to specific chemokine ligands. Among these receptors, CC chemokine receptor 1 (CCR1) is extensively studied as a G protein-linked receptor target, predominantly expressed in various leukocytes, and is considered a promising target for anti-inflammatory therapy. Furthermore, CCR1 is essential for monocyte extravasation and transportation in inflammatory conditions. Its involvement in inflammatory diseases of the central nervous system (CNS), including multiple sclerosis, Alzheimer's disease, and stroke, has been extensively studied along with its ligands. Animal models have demonstrated the beneficial effects resulting from inhibiting CCR1 or its ligands.

SUMMARY

This review demonstrates the significance of CCR1 in CNS inflammatory diseases, the molecules implicated in the inflammatory pathway, and potential drugs or molecules for treating CNS diseases. This evidence may offer new targets or strategies for treating inflammatory CNS diseases.

Network pharmacology combines machine learning, molecular simulation dynamics and experimental validation to explore the mechanism of acetylbinankadsurin A in the treatment of liver fibrosis

ETHNOPHARMACOLOGICAL RELEVANCE

The Kadsura coccinea (Lem.) A. C. Smith is known as "Heilaohu" of the Tujia ethnomedicine in China. It has anti-tumor, anti-oxidation, anti-HIV, anti-inflammatory and liver protective effects, used to treat diseases such as rheumatoid arthritis, cancer, gastritis and hepatitis. In this research, we investigated the anti-fibrotic effect and possible mechanisms of acetylbinankadsurin A (ACBA) in vitro and in vivo, which is a natural compound derived from roots of K. coccinea.

AIM OF THE STUDY

We try to evaluate the efficacy of ACBA in the treatment of liver fibrosis and to explore the underlying mechanisms of ACBA by network pharmacology, machine learning, molecular docking, molecular dynamics simulations, and experimental assessment.

MATERIALS AND METHODS

ACBA was isolated from the CH2Cl2 layer of the roots of K. coccinea through column chromatographic techniques. The structure of ACBA was determined by using 1D and 2D NMR. CCl4-induced C57BL/6 mouse liver fibrosis models were established to evaluate the anti-fibrosis effects of ACBA in vivo. The molecular targets of ACBA and liver fibrosis were obtained from various databases, then constructed a protein-protein interaction (PPI) networks through the STRING database. Gene ontology (GO) enrichment and kyoto encyclopedia of genes and genomes (KEGG) analysis were applied using the "clusterProfiler" R package. Furthermore, the key genes for ACBA treatment of liver fibrosis were identified by the least absolute shrinkage and selection operator (LASSO). Molecular docking and molecular dynamics simulations were also carried out. Finally, the target and pathway of ACBA were verified by immunofluorescence staining, RT-PCR and Western blot.

RESULT

First, ACBA attenuated CCl4-induced liver injury and fibrosis in vivo. These findings were accompanied by decreased expression of α-SMA and collagen I. Second, ACBA significantly decreased serum levels of ALT, AST, TNF-α and IL-6. Then, we identified 133 potential targets of ACBA and 7987 targets of liver fibrosis. KEGG analysis showed that ACBA could regulate the drug metabolism - cytochrome P450, fructose and mannose metabolism, IL-17 and NF-κB signaling pathways. Next, six core targets was screened by LASSO analysis including AKR1B1, PFKFB3, EPHA3, CDK1, CCR1 and CYP3A4. Molecular docking showed that ACBA has a good binding affinity for CCR1. Furthermore, compared with CCR1 inhibitor BX-471, The results of molecular simulation dynamics showed that ACBA was stable in binding with CCR1. Consistently, ACBA remarkably downregulated the expression of CCR1, p-NF-κBp65, p-IκBα, p-STAT1 and TNF-α proteins, which were upregulated in CCl4-induced hepatic fibrosis and LPS-THP-1 cells.

CONCLUSION

Our results suggest that ACBA significantly attenuated CCl4-induced liver fibrosis in histopathological and in serum level. This effect may be mediated by CCR1, NF-κB and STAT1 signalling.

The interplay of Cxcl10+/Mmp14+ monocytes and Ccl3+ neutrophils proactively mediates silica-induced pulmonary fibrosis

As a fatal occupational disease with limited therapeutic options, molecular mechanisms underpinning silicosis are still undefined. Herein, single-cell RNA sequencing of the lung tissue of silicosis mice identified two monocyte subsets, which were characterized by Cxcl10 and Mmp14 and enriched in fibrotic mouse lungs. Both Cxcl10+ and Mmp14+ monocyte subsets exhibited activation of inflammatory marker genes and positive regulation of cytokine production. Another fibrosis-unique neutrophil population characterized by Ccl3 appeared to be related to the pro-fibrotic process, specifically the "inflammatory response". Meanwhile, the proportion of monocytes and neutrophils was significantly higher in the serum of silicosis patients and slices of lung tissue from patients with silicosis further validated the over-expression of Cxcl10 and Mmp14 in monocytes, also Ccl3 in neutrophils, respectively. Mechanically, receptor-ligand interaction analysis identified the crosstalk of Cxcl10+/Mmp14+ monocytes with Ccl3+ neutrophils promoting fibrogenesis via coupling of HBEGF-CD44 and CSF1-CSF1R. In vivo, administration of clodronate liposomes, Cxcl10 or Mmp14 siRNA-loaded liposomes, Ccl3 receptor antagonist BX471, CD44 or CSF1R neutralizing antibodies significantly alleviated silica-induced lung fibrosis. Collectively, these results demonstrate that the newly defined Cxcl10+/Mmp14+ monocytes and Ccl3+ neutrophils participate in the silicosis process and highlight anti-receptor-ligand pair treatment as a potentially effective therapeutic strategy in managing silicosis.

Sinomenine attenuates bleomycin-induced pulmonary fibrosis, inflammation, and oxidative stress by inhibiting TLR4/NLRP3/TGFβ signaling

OBJECTIVE

The present work concentrated on validating whether sinomenine alleviates bleomycin (BLM)-induced pulmonary fibrosis, inflammation, and oxidative stress.

METHODS

A rat model of pulmonary fibrosis was constructed through intratracheal injection with 5 mg/kg BLM, and the effects of 30 mg/kg sinomenine on pulmonary inflammation, fibrosis, apoptosis, and 4-hydroxynonenal density were evaluated by hematoxylin and eosin staining, Masson's trichrome staining, TUNEL staining, and immunohistochemistry. Hydroxyproline content and concentrations of inflammatory cytokines and oxidative stress markers were detected using corresponding kits. MRC-5 cells were treated with 10 ng/ml PDGF, and the effects of 1 mM sinomenine on cell proliferation were assessed by EdU assays. The mRNA expression of inflammatory cytokines and the protein levels of collagens, fibrosis markers, and key markers involved in the TLR4/NLRP3/TGFβ signaling were tested with RT-qPCR and immunoblotting analysis.

RESULTS

Sinomenine attenuated pulmonary fibrosis and inflammation while reducing hydroxyproline content and the protein expression of collagens and fibrosis markers in BLM-induced pulmonary fibrosis rats. Sinomenine reduced apoptosis in lung samples of BLM-challenged rats by increasing Bcl-2 and reducing Bax and cleaved caspase-3 protein expression. In addition, sinomenine alleviated inflammatory response and oxidative stress in rats with pulmonary fibrosis induced by BLM. Moreover, sinomenine inhibited the TLR4/NLRP3/TGFβ signaling pathway in lung tissues of BLM-stimulated rats. Furthermore, TLR4 inhibitor, TAK-242, attenuated PDGF-induced fibroblast proliferation and collagen synthesis in MRC-5 cells.

CONCLUSION

Sinomenine attenuates BLM-caused pulmonary fibrosis, inflammation, and oxidative stress by inhibiting the TLR4/NLRP3/TGFβ signaling, indicating that sinomenine might become a therapeutic candidate to treat pulmonary fibrosis.

Influenza breakthrough infection in vaccinated mice is characterized by non-pathological lung eosinophilia

Eosinophils are important mediators of mucosal tissue homeostasis, anti-helminth responses, and allergy. Lung eosinophilia has previously been linked to aberrant Type 2-skewed T cell responses to respiratory viral infection and may also be a consequence of vaccine-associated enhanced respiratory disease (VAERD), particularly in the case of respiratory syncytial virus (RSV) and the formalin-inactivated RSV vaccine. We previously reported a dose-dependent recruitment of eosinophils to the lungs of mice vaccinated with alum-adjuvanted trivalent inactivated influenza vaccine (TIV) following a sublethal, vaccine-matched H1N1 (A/New Caledonia/20/1999; NC99) influenza challenge. Given the differential role of eosinophil subset on immune function, we conducted the investigations herein to phenotype the lung eosinophils observed in our model of influenza breakthrough infection. Here, we demonstrate that eosinophil influx into the lungs of vaccinated mice is adjuvant- and sex-independent, and only present after vaccine-matched sublethal influenza challenge but not in mock-challenged mice. Furthermore, vaccinated and challenged mice had a compositional shift towards more inflammatory eosinophils (iEos) compared to resident eosinophils (rEos), resembling the shift observed in ovalbumin (OVA)-sensitized allergic control mice, however without any evidence of enhanced morbidity or aberrant inflammation in lung cytokine/chemokine signatures. Furthermore, we saw a lung eosinophil influx in the context of a vaccine-mismatched challenge. Additional layers of heterogeneity in the eosinophil compartment were observed via unsupervised clustering analysis of flow cytometry data. Our collective findings are a starting point for more in-depth phenotypic and functional characterization of lung eosinophil subsets in the context of vaccine- and infection-induced immunity.

Characterization of Chemotaxis-Associated Gene Dysregulation in Myeloid Cell Populations in the Lungs during Lipopolysaccharide-Mediated Acute Lung Injury

During endotoxin-induced acute lung injury (ALI), immune cell recruitment resulting from chemotaxis is mediated by CXC and CC chemokines and their receptors. In this study, we investigated the role of chemokines and their receptors in the regulation of myeloid cell populations in the circulation and the lungs of C57BL/6J mice exhibiting LPS-mediated ALI using single-cell RNA sequencing. During ALI, there was an increase in the myeloid cells, M1 macrophages, monocytes, neutrophils, and other granulocytes, whereas there was a decrease in the residential alveolar macrophages and M2 macrophages. Interestingly, LPS triggered the upregulation of CCL3, CCL4, CXCL2/3, and CXCL10 genes associated with cellular migration of various subsets of macrophages, neutrophils, and granulocytes. Furthermore, there was an increase in the frequency of myeloid cells expressing CCR1, CCR3, CCR5, and CXCR2 receptors during ALI. MicroRNA sequencing studies of vehicle versus LPS groups identified several dysregulated microRNAs targeting the upregulated chemokine genes. This study suggests that chemokine ligand-receptors interactions are responsible for myeloid cell heterogenicity and cellular recruitment to the lungs during ALI. The single-cell transcriptomics allowed for an in-depth assessment and characterization of myeloid cells involved in immune cell trafficking during ALI.

Influence of the irradiated pulmonary microenvironment on macrophage and T cell dynamics

BACKGROUND

The lung is sensitive to radiation, increasing normal tissue toxicity risks following radiation therapy. Adverse outcomes include pneumonitis and pulmonary fibrosis, which result from dysregulated intercellular communication within the pulmonary microenvironment. Although macrophages are implicated in these pathogenic outcomes, the impact of their microenvironment is not well understood.

MATERIALS AND METHODS

C57BL/6J mice received 6Gyx5 irradiation to the right lung. Macrophage and T cell dynamics were investigated in ipsilateral right lungs, contralateral left lungs and non-irradiated control lungs 4-26wk post exposure. Lungs were evaluated by flow cytometry, histology and proteomics.

RESULTS

Following uni-lung irradiation, focal regions of macrophage accumulation were noted in both lungs by 8wk, however by 26wk fibrotic lesions were observed only in ipsilateral lungs. Infiltrating and alveolar macrophages populations expanded in both lungs, however transitional CD11b + alveolar macrophages persisted only in ipsilateral lungs and expressed lower CD206. Concurrently, arginase-1 + macrophages accumulated in ipsilateral but not contralateral lungs at 8 and 26wk post exposure, while CD206 + macrophages were absent from these accumulations. While radiation expanded CD8 + T cells in both lungs, T regulatory cells only increased in ipsilateral lungs. Unbiased proteomics analysis of immune cells revealed a substantial number of differentially expressed proteins in ipsilateral lungs when compared to contralateral lungs and both differed from non-irradiated controls.

CONCLUSIONS

Pulmonary macrophage and T cell dynamics are impacted by the microenvironmental conditions that develop following radiation exposure, both locally and systemically. While macrophages and T cells infiltrate and expand in both lungs, they diverge phenotypically depending on their environment.

Mesenchymal stem cells in radiation-induced lung injury: From mechanisms to therapeutic potential

Radiotherapy (RT) is an effective treatment option for multiple thoracic malignant tumors, including lung cancers, thymic cancers, and tracheal cancers. Radiation-induced lung injury (RILI) is a serious complication of radiotherapy. Radiation causes damage to the pulmonary cells and tissues. Multiple factors contribute to the progression of Radiation-induced lung injury, including genetic alterations, oxidative stress, and inflammatory responses. Especially, radiation sources contribute to oxidative stress occurrence by direct excitation and ionization of water molecules, which leads to the decomposition of water molecules and the generation of reactive oxygen species (ROS), reactive nitrogen species (RNS). Subsequently, reactive oxygen species and reactive nitrogen species overproduction can induce oxidative DNA damage. Immune cells and multiple signaling molecules play a major role in the entire process. Mesenchymal stem cells (MSCs) are pluripotent stem cells with multiple differentiation potentials, which are under investigation to treat radiation-induced lung injury. Mesenchymal stem cells can protect normal pulmonary cells from injury by targeting multiple signaling molecules to regulate immune cells and to control balance between antioxidants and prooxidants, thereby inhibiting inflammation and fibrosis. Genetically modified mesenchymal stem cells can improve the natural function of mesenchymal stem cells, including cellular survival, tissue regeneration, and homing. These reprogrammed mesenchymal stem cells can produce the desired products, including cytokines, receptors, and enzymes, which can contribute to further advances in the therapeutic application of mesenchymal stem cells. Here, we review the molecular mechanisms of radiation-induced lung injury and discuss the potential of Mesenchymal stem cells for the prevention and treatment of radiation-induced lung injury. Clarification of these key issues will make mesenchymal stem cells a more fantastic novel therapeutic strategy for radiation-induced lung injury in clinics, and the readers can have a comprehensive understanding in this fields.

Novel drug delivery systems and disease models for pulmonary fibrosis

Pulmonary fibrosis (PF) is a serious and progressive lung disease which is possibly life-threatening. It causes lung scarring and affects lung functions including epithelial cell injury, massive recruitment of immune cells and abnormal accumulation of extracellular matrix (ECM). There is currently no cure for PF. Treatment for PF is aimed at slowing the course of the disease and relieving symptoms. Pirfenidone (PFD) and nintedanib (NDNB) are currently the only two FDA-approved oral medicines to slow down the progress of idiopathic pulmonary fibrosis, a specific type of PF. Novel drug delivery systems and therapies have been developed to improve the prognosis of the disease, as well as reduce or minimize the toxicities during drug treatment. The drug delivery routes for these therapies are various including oral, intravenous, nasal, inhalant, intratracheal and transdermal; although this is dependent on specific treatment mechanisms. In addition, researchers have also expanded current animal models that could not fully restore the clinicopathology, and developed a series of in vitro models such as organoids to study the pathogenesis and treatment of PF. This review describes recent advances on pathogenesis exploration, classifies and specifies the progress of drug delivery systems by their delivery routes, as well as an overview on the in vitro and in vivo models for PF research.

The roles of CC chemokines in response to radiation

Radiotherapy is an effective regimen for cancer treatment alone or combined with chemotherapy or immunotherapy. The direct effect of radiotherapy involves radiation-induced DNA damage, and most studies have focused on this area to improve the efficacy of radiotherapy. Recently, the immunomodulatory effect of radiation on the tumour microenvironment has attracted much interest. Dying tumour cells can release multiple immune-related molecules, including tumour-associated antigens, chemokines, and inflammatory mediators. Then, immune cells are attracted to the irradiated site, exerting immunostimulatory or immunosuppressive effects. CC chemokines play pivotal roles in the trafficking process. The CC chemokine family includes 28 members that attract different immune subsets. Upon irradiation, tumour cells or immune cells can release different CC chemokines. Here, we mainly discuss the importance of CCL2, CCL3, CCL5, CCL8, CCL11, CCL20 and CCL22 in radiotherapy. In irradiated normal tissues, released chemokines induce epithelial to mesenchymal transition, thus promoting tissue injury. In the tumour microenvironment, released chemokines recruit cancer-associated cells, such as tumour-infiltrating lymphocytes, myeloid-derived suppressor cells and tumour-associated macrophages, to the tumour niche. Thus, CC chemokines have protumour and antitumour properties. Based on the complex roles of CC chemokines in the response to radiation, it would be promising to target specific chemokines to alleviate radiation-induced injury or promote tumour control.

Dihydroartemisinin attenuates pulmonary inflammation and fibrosis in rats by suppressing JAK2/STAT3 signaling

Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has induced a worldwide pandemic since early 2020. COVID-19 causes pulmonary inflammation, secondary pulmonary fibrosis (PF); however, there are still no effective treatments for PF. The present study aimed to explore the inhibitory effect of dihydroartemisinin (DHA) on pulmonary inflammation and PF, and its molecular mechanism. Morphological changes and collagen deposition were analyzed using hematoxylin-eosin staining, Masson staining, and the hydroxyproline content. DHA attenuated early alveolar inflammation and later PF in a bleomycin-induced rat PF model, and inhibited the expression of interleukin (IL)-1β, IL-6, tumor necrosis factor α (TNFα), and chemokine (C-C Motif) Ligand 3 (CCL3) in model rat serum. Further molecular analysis revealed that both pulmonary inflammation and PF were associated with increased transforming growth factor-β1 (TGF-β1), Janus activated kinase 2 (JAK2), and signal transducer and activator 3(STAT3) expression in the lung tissues of model rats. DHA reduced the inflammatory response and PF in the lungs by suppressing TGF-β1, JAK2, phosphorylated (p)-JAK2, STAT3, and p-STAT3. Thus, DHA exerts therapeutic effects against bleomycin-induced pulmonary inflammation and PF by inhibiting JAK2-STAT3 activation. DHA inhibits alveolar inflammation, and attenuates lung injury and fibrosis, possibly representing a therapeutic candidate to treat PF associated with COVID-19.

Immunomodulation by radiotherapy in tumour control and normal tissue toxicity

Radiotherapy (RT) is a highly effective anticancer treatment that is delivered to more than half of all patients with cancer. In addition to the well-documented direct cytotoxic effects, RT can have immunomodulatory effects on the tumour and surrounding tissues. These effects are thought to underlie the so-called abscopal responses, whereby RT generates systemic antitumour immunity outside the irradiated tumour. The full scope of these immune changes remains unclear but is likely to involve multiple components, such as immune cells, the extracellular matrix, endothelial and epithelial cells and a myriad of chemokines and cytokines, including transforming growth factor-β (TGFβ). In normal tissues exposed to RT during cancer therapy, acute immune changes may ultimately lead to chronic inflammation and RT-induced toxicity and organ dysfunction, which limits the quality of life of survivors of cancer. Here we discuss the emerging understanding of RT-induced immune effects with particular focus on the lungs and gut and the potential immune crosstalk that occurs between these tissues.

CCR5 Antagonist Maraviroc Inhibits Acute Exacerbation of Lung Inflammation Triggered by Influenza Virus in Cigarette Smoke-Exposed Mice

Influenza A virus (IAV) infection is a common cause of acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Since macrophage inflammatory protein 1 α, a chemokine that acts through CC-chemokine receptor (CCR)-5, appears elevated in COPD patients’ airways, we evaluated whether CCR5 antagonist Maraviroc could inhibit the exacerbated lung inflammatory response noted after IAV H1N1 infection in mice exposed to cigarette smoke (Cs). C57BL/6 mice, subjected or not to Cs inhalation for 11 days, were infected with H1N1 at day 7. Maraviroc (10 mg/kg) or dexamethasone (1 mg/kg) were given in a therapeutic schedule, followed by the analyses of lung function, survival rate, and inflammatory changes. As compared to mice subjected to Cs or H1N1 alone, the insult combination significantly worsened airway obstruction, neutrophil infiltration in the airways, and the survival rate. All changes were sensitive to Maraviroc but not dexamethasone. Maraviroc also reduced the accumulation of neutrophils and macrophages as well as CXCL1 production in the lung tissue, and serum levels of IL-6, whereas comparable viral titers in the lungs were noted in all infected groups. Collectively, these findings suggest that Maraviroc oral treatment could be an effective therapy for controlling acute exacerbations of respiratory diseases such as COPD.

The progress of chemokines and chemokine receptors in autism spectrum disorders

Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders and the main symptoms of ASD are impairments in social communication and abnormal behavioral patterns. Studies have shown that immune dysfunction and neuroinflammation play a key role in ASD patients and experimental models. Chemokines are groups of small proteins that regulate cell migration and mediate inflammation responses via binding to chemokine receptors. Thus, chemokines/chemokine receptors may be involved in neurodevelopmental disorders and associated with ASD. In this review, we summarize the research progress of chemokine aberrations in ASD and also review the recent progress of clinical treatment of ASD and pharmacological research related to chemokines/chemokine receptors. This review highlights the possible connection between chemokines/chemokine receptors and ASD, and provides novel potential targets for drug discovery of ASD.

Prediction of severity and subtype of fibrosing disease using model informed by inflammation and extracellular matrix gene index

Fibrosis is a chronic disease with heterogeneous clinical presentation, rate of progression, and occurrence of comorbidities. Systemic sclerosis (scleroderma, SSc) is a rare rheumatic autoimmune disease that encompasses several aspects of fibrosis, including highly variable fibrotic manifestation and rate of progression. The development of effective treatments is limited by these variabilities. The fibrotic response is characterized by both chronic inflammation and extracellular remodeling. Therefore, there is a need for improved understanding of which inflammation-related genes contribute to the ongoing turnover of extracellular matrix that accompanies disease. We have developed a multi-tiered method using Naïve Bayes modeling that is capable of predicting level of disease and clinical assessment of patients based on expression of a curated 60-gene panel that profiles inflammation and extracellular matrix production in the fibrotic disease state. Our novel modeling design, incorporating global and parametric-based methods, was highly accurate in distinguishing between severity groups, highlighting the importance of these genes in disease. We refined this gene set to a 12-gene index that can accurately identify SSc patient disease state subsets and informs knowledge of the central regulatory pathways in disease progression.

Inflammatory Cell Differentiation and Chemotaxis and Extracellular Tissue Repair Markers Are Correlated with Pulmonary Dysfunction in HIV Infected Individuals Presenting with Community-Acquired Pneumonia

Prior studies have shown that HIV patients develop permanent pulmonary dysfunction following an episode of community-acquired pneumonia (CAP). However, the mechanism causing pulmonary dysfunction remains an enigma. HIV patients experience chronic inflammation. We hypothesized that CAP exacerbates inflammation in HIV patients resulting in an accelerated decline in lung function. A prospective cohort pilot study enrolled HIV patients hospitalized in Medellin, Colombia, with a diagnosis of CAP. Sixteen patients were eligible for the study; they were split into 2 groups: HIV and HIV+CAP. Plasma, sputum, and pulmonary function test (PFT) measurements were retrieved within 48 h of hospital admission and at 1 month follow-up. The concentrations of 13 molecules and PFT values were compared between the 2 cohorts. The HIV+CAP group had lower lung function compared to the HIV group; forced vital capacity (FVC)% predicted and forced expiratory volume in 1 s (FEV₁)% predicted decreased, while FEV₁/FVC remained constant. APRIL, BAFF, CCL3, and TIMP-1 correlated negatively with FVC% predicted and FEV₁% predicted; the relationships however were moderate in strength. Furthermore, the concentrations of BAFF, CCL3, and TIMP-1 were statistically significant between the 2 groups (P ≤ 0.05). Our results indicate that HIV patients with CAP have a different inflammatory pattern and lower lung function compared to HIV patients without CAP. BAFF, CCL3, and TIMP-1 were abnormally elevated in HIV patients with CAP. Future studies with larger cohorts are required to verify these results. In addition, further investigation is required to determine if BAFF, CCL3, and TIMP-1 play a role in the process causing pulmonary dysfunction.

Cryptotanshinone Ameliorates Radiation-Induced Lung Injury in Rats

Cryptotanshinone (CTS) was reported to repress a variety of systemic inflammation and alleviate cardiac fibrosis, but it is still unclear whether CTS could prevent radiation-induced lung injury (RILI). Here, we investigated the effects and underlying mechanisms of CTS on a RILI rat model. Our data revealed that CTS could efficiently preserve pulmonary function in RILI rats and reduce early pulmonary inflammation infiltration elicited, along with marked decreased levels of IL-6 and IL-10. Moreover, we found that CTS is superior to prednisone in attenuating collagen deposition and pulmonary fibrosis, in parallel with a marked drop of HYP (a collagen indicator) and α-SMA (a myofibroblast marker). Mechanistically, CTS inhibited profibrotic signals TGF-β1 and NOX-4 expressions, while enhancing the levels of antifibrotic enzyme MMP-1 in lung tissues. It is noteworthy that CTS treatment, in consistent with trichrome staining analysis, exhibited a clear advantage over PND in enhancing MMP-1 levels. However, CTS exhibited little effect on CTGF activation and on COX-2 suppression. Finally, CTS treatment significantly mitigated the radiation-induced activation of CCL3 and its receptor CCR1. In summary, CTS treatment could attenuate RILI, especially pulmonary fibrosis, in rats. The regulation on production and release of inflammatory or fibrotic factors IL-6, IL-10, TGF-β1, NOX-4, and MMP-1, especially MMP-1 and inhibition on CCL3/CCR1 activation, may partly attribute to its attenuating RILI effect.

Synthetic analogues of the parasitic worm product ES-62 reduce disease development in in vivo models of lung fibrosis

Parasitic worms are receiving much attention as a potential new therapeutic approach to treating autoimmune and allergic conditions but concerns remain regarding their safety. As an alternative strategy, we have focused on the use of defined parasitic worm products and recently taken this one step further by designing drug-like small molecule analogues of one such product, ES-62, which is anti-inflammatory by virtue of covalently attached phosphorylcholine moieties. Previously, we have shown that ES-62 mimics are efficacious in protecting against disease in mouse models of rheumatoid arthritis, systemic lupus erythematosus and skin and lung allergy. Given the potential role of chronic inflammation in fibrosis, in the present study we have focused our attention on lung fibrosis, a debilitating condition for which there is no cure and which in spite of treatment slowly gets worse over time. Two mouse models of fibrosis - bleomycin-induced and LPS-induced - in which roles for inflammation have been implicated were adopted. Four ES-62 analogues were tested - 11a and 12b, previously shown to be active in mouse models of allergic and autoimmune disease and 16b and AIK-29/62 both of which are structurally related to 11a. All four compounds were found to significantly reduce disease development in both fibrosis models, as shown by histopathological analysis of lung tissue, indicating their potential as treatments for this condition.

CpG-oligodeoxynucleotides may be effective for preventing ionizing radiation induced pulmonary fibrosis

Pulmonary fibrosis is a serious adverse effect of radiotherapy for thoracic tumor, which is believed to be a process that is tightly regulated by the phenotype of the developing Th response after radiation. Here, we will investigate whether CpG-oligodeoxynucleotides (ODN) prevent radiation-induced pulmonary fibrosis by shifting the imbalance of Th1 and Th2 response and summarizes the possible mechanism. In this study, female C57BL/6 mice were chosen to preform pulmonary fibrosis model, the whole-thorax of mice was exposed to a single radiation dose of 15 Gy. When irradiated mice were administrated with CpG-ODN, forming of pulmonary fibrosis was significantly prevented. Th2-related cytokines (IL-4 and IL-13) expression decreased, Th1 related-cytokine (IFN-γ and IL-12) expression increased. Alveolar macrophage accumulation was reduced in irradiated tissue. Profibrotic cytokine TGF-β1 expression stayed at lower level. In TGF-β1-Smad-dependent pathways, TGF-β1, TβR and phosphor-Smad 2/3 were down regulated, and Smad 7 was up regulated. These suggested that CpG-ODN prevented pulmonary fibrosis after radiation. The mechanism might be associated with reduction of alveolar macrophages accumulation and profibrogenic cytokines secretion TGF-β1 through stimulating the combination of Th1-promoting and Th2-limiting responses after radiation, and finally inhibited the fibrosis-related downstream TGF-β1-Smad-dependent pathway.

Radiation-induced pulmonary gene expression changes are attenuated by the CTGF antibody Pamrevlumab

BACKGROUND

Fibrosis is a delayed side effect of radiation therapy (RT). Connective tissue growth factor (CTGF) promotes the development of fibrosis in multiple settings, including pulmonary radiation injury.

METHODS

To better understand the cellular interactions involved in RT-induced lung injury and the role of CTGF in these responses, microarray expression profiling was performed on lungs of irradiated and non-irradiated mice, including mice treated with the anti-CTGF antibody pamrevlumab (FG-3019). Between group comparisons (Welch's t-tests) and principal components analyses were performed in Genespring.

RESULTS

At the mRNA level, the ability of pamrevlumab to prolong survival and ameliorate RT-induced radiologic, histologic and functional lung deficits was correlated with the reversal of a clear enrichment in mast cell, macrophage, dendritic cell and mesenchymal gene signatures. Cytokine, growth factor and matrix remodeling genes that are likely to contribute to RT pneumonitis and fibrosis were elevated by RT and attenuated by pamrevlumab, and likely contribute to the cross-talk between enriched cell-types in injured lung.

CONCLUSIONS

CTGF inhibition had a normalizing effect on select cell-types, including immune cells not typically regarded as being regulated by CTGF. These results suggest that interactions between RT-recruited cell-types are critical to maintaining the injured state; that CTGF plays a key role in this process; and that pamrevlumab can ameliorate RT-induced lung injury in mice and may provide therapeutic benefit in other immune and fibrotic disorders.

Otitis Media and Nasopharyngeal Colonization in ccl3-/- Mice

We previously found CC chemokine ligand 3 (CCL3) to be a potent effector of inflammation during otitis media (OM): exogenous CCL3 rescues the OM phenotype of tumor necrosis factor-deficient mice and the function of macrophages deficient in several innate immune molecules. To further delineate the role of CCL3 in OM, we evaluated middle ear (ME) responses of ccl3^-/-mice to nontypeable Haemophilus influenzae (NTHi). CCL chemokine gene expression was evaluated in wild-type (WT) mice during the complete course of acute OM. OM was induced in ccl3^-/- and WT mice, and infection and inflammation were monitored for 21 days. Phagocytosis and killing of NTHi by macrophages were evaluated by an in vitro assay. The nasopharyngeal bacterial load was assessed in naive animals of both strains. Many CCL genes showed increased expression levels during acute OM, with CCL3 being the most upregulated, at levels 600-fold higher than the baseline. ccl3^-/- deletion compromised ME bacterial clearance and prolonged mucosal hyperplasia. ME recruitment of leukocytes was delayed but persisted far longer than in WT mice. These events were linked to a decrease in the macrophage capacity for NTHi phagocytosis and increased nasopharyngeal bacterial loads in ccl3^-/- mice. The generalized impairment in inflammatory cell recruitment was associated with compensatory changes in the expression profiles of CCL2, CCL7, and CCL12. CCL3 plays a significant role in the clearance of infection and resolution of inflammation and contributes to mucosal host defense of the nasopharyngeal niche, a reservoir for ME and upper respiratory infections. Therapies based on CCL3 could prove useful in treating or preventing persistent disease.

The Th1/Th17 balance dictates the fibrosis response in murine radiation-induced lung disease

Radiotherapy can result in lung diseases pneumonitis or fibrosis dependent on patient susceptibility. Herein we used inbred and genetically altered mice to investigate whether the tissue adaptive immune response to radiation injury influences the development of radiation-induced lung disease. Six inbred mouse strains were exposed to 18 Gy whole thorax irradiation and upon respiratory distress strains prone to pneumonitis with fibrosis presented an increased pulmonary frequency of Thelper (Th)17 cells which was not evident in strains prone solely to pneumonitis. The contribution of Th17 cells to fibrosis development was supported as the known enhanced fibrosis of toll-like receptor 2&4 deficient mice, compared to C57BL/6J mice, occurred with earlier onset neutrophilia, and with increased levels of pulmonary Th17, but not Th1, cells following irradiation. Irradiated Il17−/− mice lacked Th17 cells, and were spared both fibrosis and pneumonitis, as they survived to the end of the experiment with a significantly increased pulmonary Th1 cell frequency, only. Interferon-γ−/− mice, deficient in Th1 cells, developed a significantly enhanced fibrosis response compared to that of C57BL/6J mice. The tissue adaptive immune response influences the pulmonary disease response to radiotherapy, as an increased Th17 cell frequency enhanced and a Th1 response spared, fibrosis in mice.

Implications of the Bystander and Abscopal Effects of Radiation Therapy

Siva and colleagues have demonstrated that localized thoracic radiation resulted in DNA damage at out-of-field sites. Although these interesting findings require validation, we discuss the important clinical implications of these data, especially in the era of immune therapies. Clin Cancer Res; 22(19); 4763-5. ©2016 AACRSee related article by Siva et al., p. 4817.

Stereotactic body radiation therapy and intensity modulated radiation therapy induce different plasmatic cytokine changes in non-small cell lung cancer patients: a pilot study

PURPOSE

To assess kinetics of plasmatic cytokines during radiation therapy (RT) for locally advanced and early-stage non-small cell lung cancer (NSCLC).

METHODS

This prospective study was conducted on 15 early-stage NSCLC underwent to extreme hypofractionated regimen (52 Gy in 8 fractions) with stereotactic body RT (SBRT), and 13 locally advanced NSCLC underwent to radical moderated hypofractionated regimen (60 Gy in 25 fractions) with intensity modulated RT (IMRT). For patients undergoing SBRT, peripheral blood samples were collected on the first day of SBRT (TFd), the last day (TLd) and 45 days (T45d) after the end of SBRT. For patients undergoing IMRT, blood samples were collected at: TFd, 2 weeks (T2w), 4 weeks (T4w), TLd, and T45d. The following cytokines were measured: IL-1, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IL-15, IL-17A, EGF, FGF-2, INF-γ, MIP-1α, MIP-1β, TGF-α, TNF-α, and VEGF. Cytokine levels measured in different RT time and compared.

RESULTS

No difference in baseline levels of cytokines was documented between patient radiation approaches (except for MIP-1α). For SBRT patients, a mean reduction of IL-10 and IL-17 plasma level was documented between TLd and TFd, respectively (p < 0.05). For IMRT patients, a statistically significant (p < 0.05) mean plasma level reduction was documented between T4w and TFd for all the following cytokines: IL-1, IL-1ra, IL-2, IL-12, FGF-2, MIP-1α, MIP-1β, TGF-α, TNF-α, VEGF.

CONCLUSIONS

SBRT and IMRT induce different plasmatic cytokine changes in NSCLC patients, supporting hypothesis that RT regimes of dose schedules and techniques have different impacts on the host immune response.

CCL15/CCR1 axis is involved in hepatocellular carcinoma cells migration and invasion

The identification of new biomarkers for the early detection of hepatocellular carcinoma is critical in the development of tumor-targeted therapy, which is possibly advantageous on the prognosis of this disease. Results from our previous study indicated that CCL15 can be a specific proteomic biomarker of hepatocellular carcinoma, which plays an important role in tumorigenesis and tumor invasion. In this study, we found that CCL15 can induce hepatocellular carcinoma cell migration and invasion. Furthermore, CCR1, the receptor of CCL15, was demonstrated to play a critical role in metastatic hepatocellular carcinoma. CCR1 short hairpin RNA significantly inhibited CCL15-induced chemotaxis and invasion of HepG2 cells. Moreover, CCR1 knockdown significantly limited the activity and expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. These findings suggest that CCR1 plays critical roles in hepatocellular carcinoma metastasis, which indicates that CCR1 may be a potential molecular target in hepatocellular carcinoma therapy.

Radiation-induced pulmonary injury accelerated pulmonary metastasis in a mouse model of breast cancer

The aim of the present study was to investigate the acceleration of pulmonary metastasis due to pulmonary injury caused by radiation treatment in a mouse model of breast cancer, in addition to determining the associated mechanism. The passive metastatic breast cancer model was used in radiation-treated BALB/c mice. In total, 24 mice were randomly separated into two groups, with 12 mice per group, and the groups were treated with or without pulmonary radiation. The survival time and variation of the weights of the lungs, spleen and liver were recorded. Lung metastasis was also evaluated, and chemokine (C-X-C motif) ligand 12 (CXCL12)/chemokine (C-X-C motif) receptor 4 (CXCR4) expression was determined. The results revealed that the group with radiation-induced pulmonary injury exhibited an increased incidence of pulmonary metastasis and shorter survival time compared with the mice without pulmonary radiation. The radiation-treated group possessed an increased number of metastatic nodules in the lungs, but metastasis was not evident in the liver and spleen. The CXCL12/CXCR4 axis was markedly expressed and the expression was significantly increased subsequent to radiation compared with the expression in normal lung tissues. The present study demonstrated that radiation-induced pulmonary injury may accelerate metastatic tumor growth and decrease the overall survival rate of the mice following in situ injection of tumor cells. Tumor localization and growth may have been favored by metastatic conditioning in the lung subsequent to radiotherapy. The CXCL12/CXCR4 axis may affect key elements in the multistep process of metastasis induced by radiation injury.

Therapeutic effects of C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me; bardoxolone methyl) on radiation-induced lung inflammation and fibrosis in mice

The C-28 methyl ester of 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO-Me), one of the synthetic triterpenoids, has been found to have potent anti-inflammatory and anticancer properties in vitro and in vivo. However, its usefulness in mitigating radiation-induced lung injury (RILI), including radiation-induced lung inflammation and fibrosis, has not been tested. The aim of this study was to explore the therapeutic effect of CDDO-Me on RILI in mice and the underlying mechanisms. Herein, we found that administration of CDDO-Me improved the histopathological score, reduced the number of inflammatory cells and concentrations of total protein in bronchoalveolar lavage fluid, suppressed secretion and expression of proinflammatory cytokines, including transforming growth factor-β and interleukin-6, elevated expression of the anti-inflammatory cytokine interleukin-10, and downregulated the mRNA level of profibrotic genes, including for fibronectin, α-smooth muscle actin, and collagen I. CDDO-Me attenuated radiation-induced lung inflammation. CDDO-Me also decreased the Masson's trichrome stain score, hydroxyproline content, and mRNA level of profibrotic genes, and blocked radiation-induced collagen accumulation and fibrosis. Collectively, these findings suggest that CDDO-Me ameliorates radiation-induced lung inflammation and fibrosis, and this synthetic triterpenoid is a promising novel therapeutic agent for RILI. Further mechanistic, efficacy, and safety studies are warranted to elucidate the role of CDDO-Me in the management of RILI.

Transcriptional analysis identifies key genes involved in metabolism, fibrosis/tissue repair and the immune response against Fasciola hepatica in sheep liver

BACKGROUND

Although fascioliasis has been relatively well studied, little is known about the molecular basis of this disease. This is particularly relevant, considering the very different response that sheep have to Fasciola hepatica relative to cattle. The acute phase of this disease is severe in sheep, whereas chronic fascioliasis is more common in cattle.

METHODS

To begin to explore the host-response to Fasciola in sheep and improve the understanding of the host-pathogen interactions during the parasite's migration through liver parenchyma to the bile duct, we used RNA sequencing (RNA-seq) to investigate livers from sheep infected for eight weeks compared with those from uninfected controls.

RESULTS

This study identified 572 and 42 genes that were up- and down-regulated, respectively, in infected livers relative to uninfected controls. Our molecular findings provide significant new insights into the mechanisms linked to metabolism, fibrosis and tissue-repair in sheep, and highlight the relative importance of specific components of immune response pathways, which appear to be driven toward a suppression of inflammation.

CONCLUSIONS

This study is, to our knowledge, the first detailed investigation of the transcriptomic responses in the liver tissue of any host to F. hepatica infection. It defines the involvement of specific genes associated with the host's metabolism, immune response and tissue repair/regeneration, and highlights an apparent overlapping function of many genes involved in these processes.

Long intergenic non-coding RNA induced by X-ray irradiation regulates DNA damage response signaling in the human bronchial epithelial BEAS-2B cell line

Long non-coding RNAs (lncRNAs) have been regarded as the primary genetic regulators of several important biological processes. However, the biological functions of lncRNAs in radiation-induced lung damage remain largely unknown. The present study aimed to investigate the potential effects of lncRNAs on radiation-induced lung injury (RILI). Female C57BL/6 mice were exposed to 12 Gy single doses of total body irradiation (TBI). LncRNA microarray screening was conducted at 24 h post-irradiation (IR) to investigate the differentially-expressed lncRNAs during RILI. Following the subsequent bioinformatics analysis and reverse transcription-polymerase chain reaction (RT-PCR) validation, one of the verified differentially-expressed long intergenic radiation-responsive ncRNAs (LIRRs), LIRR1, was selected for further functional study. The normal human bronchial epithelial BEAS-2B cell line was used as the cell model. The recombinant eukaryotic expression vector for the lncRNA was designed, constructed and transfected using lipofectamine. RT-PCR, clonogenic and flow cytometry assays, immunofluorescence detection and western blot analysis were performed to reveal the role of the lncRNA in the radiosensitivity regulation of the RILI target cells. In lung tissues 24 h after 12 Gy TBI, six of the identified differentially-expressed LIRRs near the coding genes were validated using quantitative (q)PCR. The upregulation of two LIRRs was observed and confirmed using qPCR. LIRR1 was chosen for further functional study. Following the stable transfection of LIRR1, identified through G418 screening, increased radiosensitivity, evident cell cycle G1 phase arrest and increased γ-H2AX foci formation were observed in the bronchial epithelial BEAS-2B cell line subsequent to IR. LIRR1 overexpression also led to decreased expression of the KU70, KU80 and RAD50 DNA repair proteins, marked activation of p53, decreased mouse double minute 2 homolog (MDM2) expression, and substantially induced p21 and suppressed cyclin-dependent kinase 2 in BEAS-2B following IR. Subsequent to the use of Pifithrin-α, a specific inhibitor of p53 activation, increased MDM2 expression was observed in the LIRR1-overexpressing cells, suggesting that LIRR1 could mediate the DNA damage response (DDR) signaling in a p53-dependent manner. The present study provides a novel mechanism for RILI, using the concept of lncRNAs.

Transforming growth factor alpha is a critical mediator of radiation lung injury

Radiation fibrosis of the lung is a late toxicity of thoracic irradiation. Epidermal growth factor (EGF) signaling has previously been implicated in radiation lung injury. We hypothesized that TGF-α, an EGF receptor ligand, plays a key role in radiation-induced fibrosis in lung. Mice deficient in transforming growth factor (TGF-α(-/-)) and control C57Bl/6J (C57-WT) mice were exposed to thoracic irradiation in 5 daily fractions of 6 Gy. Cohorts of mice were followed for survival (n ≥ 5 per group) and tissue collection (n = 3 per strain and time point). Collagen accumulation in irradiated lungs was assessed by Masson's trichrome staining and analysis of hydroxyproline content. Cytokine levels in lung tissue were assessed with ELISA. The effects of TGF-α on pneumocyte and fibroblast proliferation and collagen production were analyzed in vitro. Lysyl oxidase (LOX) expression and activity were measured in vitro and in vivo. Irradiated C57-WT mice had a median survival of 24.4 weeks compared to 48.2 weeks for irradiated TGF-α(-/-) mice (P = 0.001). At 20 weeks after irradiation, hydroxyproline content was markedly increased in C57-WT mice exposed to radiation compared to TGF-α(-/-) mice exposed to radiation or unirradiated C57-WT mice (63.0, 30.5 and 37.6 μg/lung, respectively, P = 0.01). C57-WT mice exposed to radiation had dense foci of subpleural fibrosis at 20 weeks after exposure, whereas the lungs of irradiated TGF-α (-/-) mice were largely devoid of fibrotic foci. Lung tissue concentrations of IL-1β, IL-4, TNF-α, TGF-β and EGF at multiple time points after irradiation were similar in C57-WT and TGF-α(-/-) mice. TGF-α in lung tissue of C57-WT mice rose rapidly after irradiation and remained elevated through 20 weeks. TGF-α(-/-) mice had lower basal LOX expression than C57-WT mice. Both LOX expression and LOX activity were increased after irradiation in all mice but to a lesser degree in TGF-α(-/-) mice. Treatment of NIH-3T3 fibroblasts with TGF-α resulted in increases in proliferation, collagen production and LOX activity. These studies identify TGF-α as a critical mediator of radiation-induced lung injury and a novel therapeutic target in this setting. Further, these data implicate TGF-α as a mediator of collagen maturation through a TGF-β independent activation of lysyl oxidase.

Early detection of acute radiation-induced lung injury with multi-section CT perfusion imaging: An initial experience

AIM

To explore the value of 64-section computed tomography (CT) perfusion imaging (CTPI) in the early diagnosis of acute radiation-induced lung injury (ARILI).

MATERIALS AND METHODS

Fifty-one patients with oesophageal cancers or malignant thymomas received postoperative radiation therapy with a 60-62 Gy dose and underwent CTPI at pre- and post-radiation therapy time points (week 0, week 4, week 8, and week 12 respectively). The CTPI values were prospectively compared and analysed in order to evaluate the diagnostic utility of CTPI in the early diagnosis of ARILI.

RESULTS

Eighteen cases (18/51) of ARILI were diagnosed. The mean values of relative regional blood flow (rrBF), relative regional volume (rrBV), and relative regional permeability surface (rrPS) in the ARILI group were correspondingly higher than those of the non-ARILI group. At week 4, rrBF, rrBV, and rrPS in the ARILI group were significantly higher than those at pre-radiation (each p < 0.05). In the non-ARILI group, rrBF and rrBV were higher than those at pre-radiation (each p < 0.05); however, rrPS was not statistically different from that of pre-irradiation. Applying the diagnostic threshold value of rrPS = 1.22, the sensitivity, specificity, and positive and negative predictive values of CTPI for early diagnosis of ARILI were better than those of CT.

CONCLUSION

CTPI metrics may reflect haemodynamic changes in the post-irradiation lung and can detect cases of early ARILI that appear normal at CT. CTPI is a promising technique for early diagnosis of ARILI.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

Direct isolation of myofibroblasts and fibroblasts from bleomycin-injured lungs reveals their functional similarities and differences

Background

Myofibroblasts play a crucial role in tissue repair. The functional similarities and differences between myofibroblasts and fibroblasts are not fully understood because they have not been separately isolated from a living body. The purpose of this study was to establish a method for the direct isolation of myofibroblasts and fibroblasts from injured lungs by using fluorescence-activated cell sorting and to compare their functions.

Results

We demonstrated that lineage-specific cell surface markers (lin), such as CD31, CD45, CD146, EpCAM (CD326), TER119, and Lyve-1 were not expressed in myofibroblasts or fibroblasts. Fibroblasts of bleomycin-injured lungs and saline-treated lungs were shown to be enriched in lin^neg Sca-1^high, and myofibroblasts of bleomycin-injured lungs were shown to be enriched in lin^neg Sca-1^low CD49e^high. Results from in-vitro proliferation assays indicated in-vitro proliferation of fibroblasts but not myofibroblasts of bleomycin-injured lungs and of fibroblasts of saline-treated lungs. However, fibroblasts and myofibroblasts might have a low proliferative capacity in vivo. Analysis of genes for collagen and collagen synthesis enzymes by qRT-PCR showed that the expression levels of about half of the genes were significantly higher in fibroblasts and myofibroblasts of bleomycin-injured lungs than in fibroblasts of saline-treated lungs. By contrast, the expression levels of 8 of 11 chemokine genes of myofibroblasts were significantly lower than those of fibroblasts.

Conclusions

This is the first study showing a direct isolation method of myofibroblasts and fibroblasts from injured lungs. We demonstrated functional similarities and differences between myofibroblasts and fibroblasts in terms of both their proliferative capacity and the expression levels of genes for collagen, collagen synthesis enzymes, and chemokines. Thus, this direct isolation method has great potential for obtaining useful information from myofibroblasts and fibroblasts.

The chemokine CCL3 promotes experimental liver fibrosis in mice

Liver fibrosis is associated with infiltrating immune cells and activation of hepatic stellate cells. We here aimed to investigate the effects of the CC chemokine CCL3, also known as macrophage inflammatory protein-1α, in two different fibrosis models. To this end, we treated mice either with carbon tetrachloride or with a methionine- and choline-deficient diet to induce fibrosis in CCL3 deficient and wild-type mice. The results show that the protein expression of CCL3 is increased in wild-type mice after chronic liver injury. Deletion of CCL3 exhibited reduced liver fibrosis compared to their wild-type counterparts. We could validate these results by treating the two mouse groups with either carbon tetrachloride or by feeding a methionine- and choline-deficient diet. In these models, lack of CCL3 is functionally associated with reduced stellate cell activation and liver immune cell infiltration. In vitro, we show that CCL3 leads to increased proliferation and migration of hepatic stellate cells. In conclusion, our results define the chemokine CCL3 as a mediator of experimental liver fibrosis. Thus, therapeutic modulation of CCL3 might be a promising target for chronic liver diseases.

Gene expression profiles reveal molecular mechanisms involved in the progression and resolution of bleomycin-induced lung fibrosis

Lung fibrosis is the final result of a large number of disorders and is usually considered an irreversible process. However, some evidence suggests that fibrosis could eventually be reversible. In this study we aimed to document the time-related reversibility of bleomycin-induced lung fibrosis and to examine the gene expression profile associated with its initial progression and subsequent resolution. C57BL/6 mice were instilled with a single dose of bleomycin and euthanized at 1, 4, 8, 12, and 16 wk. Control animals received an equal volume of saline. Lung fibrosis was examined by morphology and hydroxyproline content and the transcriptional signature by gene microarray analysis. Our results showed that bleomycin-injured mice developed prominent inflammation at 1 wk, followed by fibrosis that peaked at 2 mo. Then fibrosis resolved until lungs displayed almost normal architecture at 4 mo. Genomewide transcriptional profiling revealed 533 significantly changed genes. Self-organizing maps analysis of these genes identified four clusters based on the temporal pattern of gene expression. Clusters 1 and 2 contained genes upregulated during the inflammatory and fibrotic response and were enriched for extracellular matrix-related genes including several collagens, matrix metalloproteinases, and TIMP-1. Cluster 3 identified upregulated genes during the fibrotic response, and cluster 4 contained genes decreased during inflammation and fibrosis that increased during resolution. Most enriched pathways included genes involved in cell cycle and in regulation of transcription. Our findings corroborate the reversibility of bleomycin-induced lung fibrosis and reveal transcriptional signatures that characterize the progression and resolution.

The role of alveolar epithelium in radiation-induced lung injury

Pneumonitis and fibrosis are major lung complications of irradiating thoracic malignancies. In the current study, we determined the effect of thoracic irradiation on the lungs of FVB/N mice. Survival data showed a dose-dependent increase in morbidity following thoracic irradiation with single (11–13 Gy) and fractionated doses (24–36 Gy) of ¹³⁷Cs γ-rays. Histological examination showed a thickening of vessel walls, accumulation of inflammatory cells, collagen deposition, and regional fibrosis in the lungs 14 weeks after a single 12 Gy dose and a fractionated 30 Gy dose; this damage was also seen 5 months after a fractionated 24 Gy dose. After both single and fractionated doses, i] aquaporin-5 was markedly decreased, ii] E-cadherin was reduced and iii] prosurfactant Protein C (pro-SP-c), the number of pro-SP-c⁺ cells and vimentin expression were increased in the lungs. Immunofluorescence analysis revealed co-localization of pro-SP-c and α-smooth muscle actin in the alveoli after a single dose of 12 Gy. These data suggest that, i] the FVB/N mouse strain is sensitive to thoracic radiation ii] aquaporin-5, E-cadherin, and pro-SP-c may serve as sensitive indicators of radiation-induced lung injury; and iii] the epithelial-to-mesenchymal transition may play an important role in the development of radiation-induced lung fibrosis.

Genetic deficiency in complement component 4b does not alter radiation-induced lung disease in mice

Previous investigations have shown altered levels of complement components to be associated with radiation-induced lung disease. In this study we aimed to determine whether a deficiency in complement component 4b alters the lung response to irradiation of C57BL/6 mice. The pulmonary phenotype of C57BL/6 C4b(-/-) mice and their wild-type littermates was assessed following an 18 Gy single dose to the thoracic cavity. The assessed end points included, survival time postirradiation, bronchoalveolar lavage cell differential, hydroxyproline measures and histological evidence of alveolitis and fibrosis. The lung phenotype of C4b-deficient mice did not differ from that of wild-type mice in terms of survival time postirradiation, tissue hydroxyproline levels or by histological evidence of alveolitis or fibrosis. No differences in bronchoalveolar cell differential counts were evident among the irradiated mice grouped by C4b genotype. We concluded that a deficiency in C4b does not alter radiation-induced lung disease in the C57BL/6 mouse model.

Mouse genetic approaches applied to the normal tissue radiation response

The varying responses of inbred mouse models to radiation exposure present a unique opportunity to dissect the genetic basis of radiation sensitivity and tissue injury. Such studies are complementary to human association studies as they permit both the analysis of clinical features of disease, and of specific variants associated with its presentation, in a controlled environment. Herein I review how animal models are studied to identify specific genetic variants influencing predisposition to radiation-induced traits. Among these radiation-induced responses are documented strain differences in repair of DNA damage and in extent of tissue injury (in the lung, skin, and intestine) which form the base for genetic investigations. For example, radiation-induced DNA damage is consistently greater in tissues from BALB/cJ mice, than the levels in C57BL/6J mice, suggesting there may be an inherent DNA damage level per strain. Regarding tissue injury, strain specific inflammatory and fibrotic phenotypes have been documented for principally, C57BL/6 C3H and A/J mice but a correlation among responses such that knowledge of the radiation injury in one tissue informs of the response in another is not evident. Strategies to identify genetic differences contributing to a trait based on inbred strain differences, which include linkage analysis and the evaluation of recombinant congenic (RC) strains, are presented, with a focus on the lung response to irradiation which is the only radiation-induced tissue injury mapped to date. Such approaches are needed to reveal genetic differences in susceptibility to radiation injury, and also to provide a context for the effects of specific genetic variation uncovered in anticipated clinical association studies. In summary, mouse models can be studied to uncover heritable variation predisposing to specific radiation responses, and such variations may point to pathways of importance to phenotype development in the clinic.

Molecular and cellular mechanisms of pulmonary fibrosis

Pulmonary fibrosis is a chronic lung disease characterized by excessive accumulation of extracellular matrix (ECM) and remodeling of the lung architecture. Idiopathic pulmonary fibrosis is considered the most common and severe form of the disease, with a median survival of approximately three years and no proven effective therapy. Despite the fact that effective treatments are absent and the precise mechanisms that drive fibrosis in most patients remain incompletely understood, an extensive body of scientific literature regarding pulmonary fibrosis has accumulated over the past 35 years. In this review, we discuss three broad areas which have been explored that may be responsible for the combination of altered lung fibroblasts, loss of alveolar epithelial cells, and excessive accumulation of ECM: inflammation and immune mechanisms, oxidative stress and oxidative signaling, and procoagulant mechanisms. We discuss each of these processes separately to facilitate clarity, but certainly significant interplay will occur amongst these pathways in patients with this disease.