Cytokines and pulmonary fibrosis

Evaluation of three formulations based on Polymorphic membrane protein D in mice infected with Chlamydia trachomatis

The significant impact of Chlamydia trachomatis(Ct) infections worldwide highlights the need to develop a prophylactic vaccine that elicits effective immunity and protects the host from the immunopathological effects of Ct infection. The aim of this study was to evaluate a vaccine based on a fragment of the Polymorphic membrane protein D (FPmpD) of C. trachomatis as an immunogen using a heterologous DNA prime-protein boost strategy in female mice Three different formulations were evaluated as protein boost: free recombinant FPmpD (rFPmpD) or rFPmpD formulated with a liposomal adjuvant alternatively supplemented with CpG or a cationic gemini lipopeptide as immunostimulants. The three candidates induced an increase in the cervicovaginal and systemic titers of anti-rFPmpD antibodies in two strains of mice (BALB/c and C57BL/6), with no evidence of fertility alterations. The three formulations induced a rapid and robust humoral immune response upon the Ct challenge. However, the booster with free rFPmpD more efficiently reduced the shedding of infective Ct and prevented the development of immunopathology. The formulations containing adjuvant induced a strong inflammatory reaction in the uterine tissue. Hence, the prime-boost strategy with the adjuvant-free FPmpD vaccine formulation might constitute a promissory candidate to prevent C. trachomatis intravaginal infection.

Molecular and immune signatures, and pathological trajectories of fatal COVID-19 lungs defined by in situ spatial single-cell transcriptome analysis

Despite intensive studies during the last 3 years, the pathology and underlying molecular mechanism of coronavirus disease 2019 (COVID-19) remain poorly defined. In this study, we investigated the spatial single-cell molecular and cellular features of postmortem COVID-19 lung tissues using in situ sequencing (ISS). We detected 10 414 863 transcripts of 221 genes in whole-slide tissues and segmented them into 1 719 459 cells that were mapped to 18 major parenchymal and immune cell types, all of which were infected by SARS-CoV-2. Compared with the non-COVID-19 control, COVID-19 lungs exhibited reduced alveolar cells (ACs) and increased innate and adaptive immune cells. We also identified 19 differentially expressed genes in both infected and uninfected cells across the tissues, which reflected the altered cellular compositions. Spatial analysis of local infection rates revealed regions with high infection rates that were correlated with high cell densities (HIHD). The HIHD regions expressed high levels of SARS-CoV-2 entry-related factors including ACE2, FURIN, TMPRSS2 and NRP1, and co-localized with organizing pneumonia (OP) and lymphocytic and immune infiltration, which exhibited increased ACs and fibroblasts but decreased vascular endothelial cells and epithelial cells, mirroring the tissue damage and wound healing processes. Sparse nonnegative matrix factorization (SNMF) analysis of niche features identified seven signatures that captured structure and immune niches in COVID-19 tissues. Trajectory inference based on immune niche signatures defined two pathological routes. Trajectory A primarily progressed with increased NK cells and granulocytes, likely reflecting the complication of microbial infections. Trajectory B was marked by increased HIHD and OP, possibly accounting for the increased immune infiltration. The OP regions were marked by high numbers of fibroblasts expressing extremely high levels of COL1A1 and COL1A2. Examination of single-cell RNA-seq data (scRNA-seq) from COVID-19 lung tissues and idiopathic pulmonary fibrosis (IPF) identified similar cell populations consisting mainly of myofibroblasts. Immunofluorescence staining revealed the activation of IL6-STAT3 and TGF-β-SMAD2/3 pathways in these cells, likely mediating the upregulation of COL1A1 and COL1A2 and excessive fibrosis in the lung tissues. Together, this study provides a spatial single-cell atlas of cellular and molecular signatures of fatal COVID-19 lungs, which reveals the complex spatial cellular heterogeneity, organization, and interactions that characterized the COVID-19 lung pathology.

Innovative Pre-Clinical Data Using Peptides to Intervene in the Evolution of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive, relentless, and deadly disease. Little is known about its pathogenetic mechanisms; therefore, developing efficient pharmacological therapies is challenging. This work aimed to apply a therapeutic alternative using immunomodulatory peptides in a chronic pulmonary fibrosis murine model. BALB/c mice were intratracheally instilled with bleomycin (BLM) and followed for 30 days. The mice were treated with the immune modulatory peptides ToAP3 and ToAP4 every three days, starting on the 5th day post-BLM instillation. ELISA, qPCR, morphology, and respiratory function analyses were performed. The treatment with both peptides delayed the inflammatory process observed in the non-treated group, which showed a fibrotic process with alterations in the production of collagen I, III, and IV that were associated with significant alterations in their ventilatory mechanics. The ToAP3 and ToAP4 treatments, by lung gene modulation patterns, indicated that distinct mechanisms determine the action of peptides. Both peptides controlled the experimental IPF, maintaining the tissue characteristics and standard function properties and regulating fibrotic-associated cytokine production. Data obtained in this work show that the immune response regulation by ToAP3 and ToAP4 can control the alterations that cause the fibrotic process after BLM instillation, making both peptides potential therapeutic alternatives and/or adjuvants for IPF.

Mechanisms of Action of Mesenchymal Stem Cells in Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD) is currently the most common chronic liver disease worldwide. However, its pathophysiological mechanism is complicated, and currently, it has no FDA-approved pharmacological therapies. In recent years, mesenchymal stem cell (MSC) therapy has attracted increasing attention in the treatment of hepatic diseases. MSCs are multipotent stromal cells that originated from mesoderm mesenchyme, which have self-renewal and multipotent differentiation capability. Recent experiments and studies have found that MSCs have the latent capacity to be used for MAFLD treatment. MSCs have the potential to differentiate into hepatocytes, which could be induced into hepatocyte-like cells (HLCs) with liver-specific morphology and function under appropriate conditions to promote liver tissue regeneration. They can also reduce liver tissue injury and reverse the development of MAFLD by regulating immune response, antifibrotic activities, and lipid metabolism. Moreover, several advantages are attributed to MSC-derived exosomes (MSC-exosomes), such as targeted delivery, reliable reparability, and poor immunogenicity. After entering the target cells, MSC-exosomes help regulate cell function and signal transduction; thus, it is expected to become an emerging treatment for MAFLD. In this review, we comprehensively discussed the roles of MSCs in MAFLD, main signaling pathways of MSCs that affect MAFLD, and mechanisms of MSC-exosomes on MAFLD.

Oral encapsulated transforming growth factor β1 reduces endogenous levels: Effect on inflammatory bowel disease

BACKGROUND

TreXTAM^® is a combination of the key regulatory cytokine transforming growth factor beta (TGFβ) and all trans retinoic acid (ATRA) microencapsulated for oral delivery to immune structures of the gut. It is in development as a novel treatment for inflammatory bowel disease (IBD).

AIM

To measure TGFβ levels in blood and tissue after oral administration of encapsulated TGFβ.

METHODS

Animals were orally administered encapsulated TGFβ by gavage. Levels of drug substance in blood and in gut tissues at various times after administration were measured by ELISA.

RESULTS

We made the surprising discovery that oral administration of TreXTAM dramatically (approximately 50%) and significantly (P = 0.025) reduced TGFβ levels in colon, but not small intestine or mesenteric lymph nodes. Similarly, levels in rat serum after 25 d of thrice weekly dosing with either TreXTAM, or microencapsulated TGFβ alone (denoted as TPX6001) were significantly (P < 0.01) reduced from baseline levels. When tested in the SCID mouse CD4+CD25- adoptive cell transfer (ACT) model of IBD, oral TPX6001 alone provided only a transient benefit in terms of reduced weight loss.

CONCLUSION

These observations suggest a negative feedback mechanism in the gut whereby local delivery of TGFβ results in reduced local and systemic levels of the active form of TGFβ. Our findings suggest potential clinical implications for use of encapsulated TGFβ, perhaps in the context of IBD and/or other instances of fibrosis and/or pathological TGFβ signaling.

Atractylenolide III attenuates bleomycin-induced experimental pulmonary fibrosis and oxidative stress in rat model via Nrf2/NQO1/HO-1 pathway activation

BACKGROUND

Bleomycin (BLM) is a chemotherapy drug used to treat cancer, one of which side effects is that it can lead to pulmonary fibrosis (PF). Atractylenoide III (AtrIII), derived from the dried roots of rhizoma atractylodis of compositae, is one of the main active substances of rhizoma atractylodis. It has anti-inflammatory, anti-tumor and other effects. This study aimed to investigate whether AtrIII alleviated BLM-induced PF and oxidative stress in rats through the nuclear factor erythroid-2-related factor 2/NQO1,NAD(P)H:quinine oxidoreductase 1/Heme oxygenase-1 (Nrf2/NQO1/HO-1) pathway.

METHODS

A BLM-induced pulmonary fibrosis model in SD rats was established. The respiratory dynamics were evaluated by using Wholebody flow-through plethysmography. Lung injury and pulmonary fibrosis were observed by Hematoxylin-eosin (HE) and Masson staining. Apoptosis was assay by Tunel assay. Inflammatory factors were detected with commercial kits. Expression of mRNAs and proteins were detected by RT-qPCR and Western blot, respectively.

RESULTS

AtrIII (1.2, 2.4 mg/kg) improved the lung injury and lung function in the BLM-induced Sprague-Dawley (SD) rats. AtrIII reduced the apoptosis rate and protein expression of Caspase-3 and Caspase-9. AtrIII (1.2, 2.4 mg/kg) decrease the pulmonary fibrosis damage and protein expression transforming growth factor-β (TGF-β) and α-smooth muscle actin (α-SMA). AtrIII also down-regulated the levels of interleukin 6 (IL-6), inductible nitric oxide synthase (iNOS) and tumor necrosis factor-α (TNF-α), while up-regulated the level of IL-10 in peripheral blood serum. Moreover, AtrIII (1.2, 2.4 mg/kg) increased the activity of superoxide dismutase (SOD) and glutathione (GSH), while decreased the malondialdehyde (MDA) content and lactate dehydrogenase (LDH) activity. AtrIII (1.2, 2.4 mg/kg) increased the levels of Nrf2, NQO1 and HO-1. In addition, AtrIII reversed the effects of Nrf2 interference on pulmonary fibrosis damage, decreased SOD and GSH activity, and increased MDA content.

CONCLUSION

AtrIII could attenuate the pulmonary fibrosis and reliev oxidative stress through the Nrf2/NQO1/ HO-1 pathway.

Attenuation of lipopolysaccharide-induced lung inflammation by ascorbic acid in rats: Histopathological and ultrastructural study

Introduction:

Lipopolysaccharide is a bacterial endotoxin that induces acute lung injury in experimental animals, which is similar to acute respiratory distress syndrome in humans. The induced tissue trauma ends in fibrosis. Understanding the pathogenesis is important in the prevention and treatment of the complications. This study was assigned to investigate the long-term lipopolysaccharide-induced lung injury and the postulated protective effect of ascorbic acid on these changes.

Materials and methods:

Twenty-four adult male albino rats were divided into three groups. Group I was the controls, group II received lipopolysaccharide and group III received lipopolysaccharide and ascorbic acid. After 30 days of starting treatment, lung tissue samples were obtained.

Results:

Group II lung tissues showed marked thickening of the alveolar septa with collapsed alveolar sacs, detached bronchial epithelium, inflammatory cell infiltration and excessive deposition of collagen. Group III showed mild thickening of the alveolar walls, scanty inflammatory cell infiltration, mild parabronchial fibrosis and less marked collagen deposition. α-Smooth muscle actin staining of group II showed marked expression of the actin-positive cells. Less potential expression of the dye was found in group III. Ultrastructural examination of group II showed evident structural changes in pneumocytes with capillary basement membrane irregularity and interruption compared to uniform basement membrane in group III with less prominent intracellular changes in pneumocytes.

Conclusion:

Ascorbic acid attenuated the inflammatory response and fibrosis in the lungs of rats treated with lipopolysaccharide as evidenced by the histological, immunohistochemical and ultrastructural studies.

Characterization of pulmonary responses in mice to asbestos/asbestiform fibers using gene expression profiles

Humans exposed to asbestos and/or asbestiform fibers are at high risk of developing many lung diseases including asbestosis, lung cancer, and malignant mesothelioma. However, the disease-causing potential and specific metabolic mechanisms and pathways associated with various asbestos/asbestiform fiber exposures triggering different carcinogenic and non-carcinogenic outcomes are still largely unknown. The aim of this this study was to investigate gene expression profiles and inflammatory responses to different asbestos/asbestiform fibers at the acute/sub-acute phase that may be related to delayed pathological outcomes observed at later time points. Mice were exposed to asbestos (crocidolite, tremolite asbestos), asbestiform fibers (erionite), and a low pathogenicity mineral fiber (wollastonite) using oropharyngeal aspiration. Similarities in inflammatory and tissue damage responses, albeit with quantitative differences, were observed at day 1 and 7 post treatment. Exposure to different fibers induced significant changes in regulation and release of a number of inflammatory cytokines/chemokines. Comparative analysis of changes in gene regulation in the lung on day 7 post exposure were interpretable in the context of differential biological responses that were consistent with histopathological findings at days 7 and 56 post treatment. Our results noted differences in the magnitudes of pulmonary responses and gene regulation consistent with pathological alterations induced by exposures to four asbestos/asbestiform fibers examined. Further comparative mechanistic studies linking early responses with the long-term endpoints may be instrumental to understanding triggering mechanisms underlying pulmonary carcinogenesis, that is lung cancer versus mesothelioma.

Protective role of NKT cells and macrophage M2-driven phenotype in bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is a result of an abnormal wound healing in lung tissue triggered by an excessive accumulation of extracellular matrix proteins, loss of tissue elasticity, and debit of ventilatory function. NKT cells are a major source of Th1 and Th2 cytokines and may be crucial in the polarization of M1/M2 macrophages in pulmonary fibrogenesis. Although there appears to be constant scientific progress in that field, pulmonary fibrosis still exhibits no current cure. From these facts, we hypothesized that NKT cells could influence the development of pulmonary fibrosis via modulation of macrophage activation. Wild type (WT) and NKT type I cell-deficient mice (Jα18^-/-) were subjected to the protocol of bleomycin-induced pulmonary fibrosis with or without treatment with NKT cell agonists α-galactosylceramide and sulfatide. The participation of different cell populations, collagen deposition, and protein levels of different cytokines involved in inflammation and fibrosis was evaluated. The results indicate a benign role of NKT cells in Jα18^-/- mice and in wild-type α-galactosylceramide-sulfatide-treated groups. These animals presented lower levels of collagen deposition, fibrogenic molecules such as TGF-β and vimentin and improved survival rates. In contrast, WT mice developed a Th2-driven response augmenting IL-4, 5, and 13 protein synthesis and increased collagen deposition. Furthermore, the arginase-1 metabolic pathway was downregulated in wild-type NKT-activated and knockout mice indicating lower activity of M2 macrophages in lung tissue. Hence, our data suggest that NKT cells play a protective role in this experimental model by down modulating the Th2 milieu, inhibiting M2 polarization and finally preventing fibrosis.

Crosstalk Between T Lymphocytes and Lung Fibroblasts: Generation of a Hyaluronan-Enriched Extracellular Matrix Adhesive for Monocytes

In immunity and inflammation, T cells are often associated with stromal mesenchymal cells such as fibroblasts. Hyaluronan and proteins that associate with hyaluronan such as versican and tumor necrosis factor-inducible gene-6 (TSG-6) are extracellular matrix (ECM) components that promote leukocyte adhesion, accumulation, and activation. However, the factors responsible for producing this specialized ECM and its impact on inflammatory events are not well understood. In this study, we explored the role of T cells in stimulating lung fibroblasts to produce an ECM that impacts monocyte adhesion. We found that CD3/CD28-activated human CD4+ T cells when co-cultured with human lung fibroblasts stimulated the expression of mRNA for hyaluronan synthase 2 (HAS2) and decreased the expression of hyaluronidase 2 (HYAL2). This led to an increase in the deposition of hyaluronan that formed cable-like structures within the ECM. Co-culturing activated T cells with fibroblasts also led to increased expression and accumulation of TSG-6. Surprisingly, addition of activated CD4+ T cells to the fibroblasts reduced the expression of mRNA for versican, and increased the expression of enzymes that degrade versican, such as ADAMTS4 and ADAMTS9 (a disintegrin and metalloproteinase with a thrombospondin type-1 motif) leading to a decrease in versican in the ECM of the co-cultures. Furthermore, addition of human monocytes to these co-cultures resulted in elevated monocyte adhesion to the cable-like structures in the ECM when compared to controls. These results illustrate the importance of crosstalk between T cells and fibroblasts in promoting the generation of a matrix that is adhesive for monocytes. J. Cell. Biochem. 118: 2118-2130, 2017. © 2016 Wiley Periodicals, Inc.

Pulmonary Hypoplasia Induced by Oligohydramnios: Findings from Animal Models and a Population-Based Study

Pulmonary hypoplasia is a substantial cause of death in newborn infants, and oligohydramnios is one of the most commonly associated abnormalities. Lung growth is influenced by physical factors such as the intrauterine space, lung liquid volume and pressure, and fetal breathing movements. During lung development, the main physical force experienced by the lungs is stretching induced by breathing movements and the lung fluid in the airspaces. Oligohydramnios reduces the intrathoracic cavity size, thus disrupting fetal lung growth and leading to pulmonary hypoplasia. The exact mechanism by which oligohydramnios alters the respiratory system structure and the effect of oligohydramnios on long-term respiratory outcomes remain unknown. In this review, we summarize the effects of oligohydramnios on lung development, discuss the mechanisms of oligohydramnios-induced pulmonary hypoplasia identified in various animal studies, and describe the long-term respiratory outcomes in childhood of oligohydramnios-exposed fetuses reported by a population-based study.

Pathobiology of wound healing after glaucoma filtration surgery

Conjunctival and subconjunctival fibrogenesis and inflammation are sight compromising side effects that can occur subsequent to glaucoma filtration surgery. Despite initial declines in intraocular pressure resulting from increasing aqueous outflow, one of the activated responses includes marshalling of proinflammatory and pro-fibrogenic cytokine mediator entrance into the aqueous through a sclerostomy window and their release by local cells, as well as infiltrating activated immune cells. These changes induce dysregulated inflammation, edema and extracellular matrix remodeling, which occlude outflow facility. A number of therapeutic approaches are being taken to offset declines in outflow facility since the current procedure of inhibiting fibrosis with either mitomycin C (MMC) or 5-fluorouracil (5-FU) injection is nonselective. One of them entails developing a new strategy for reducing fibrosis induced by wound healing responses including myofibroblast transdifferentiation and extracellular matrix remodeling in tissue surrounding surgically created shunts. The success of this endeavor is predicated on having a good understanding of conjunctival wound healing pathobiology. In this review, we discuss the roles of inappropriately activated growth factor and cytokine receptor linked signaling cascades inducing conjunctival fibrosis/scarring during post-glaucoma surgery wound healing. Such insight may identify drug targets for blocking fibrogenic signaling and excessive fibrosis which reduces rises in outflow facility resulting from glaucoma filtration surgery.

Oral Delivery of Particulate Transforming Growth Factor Beta 1 and All-Trans Retinoic Acid Reduces Gut Inflammation in Murine Models of Inflammatory Bowel Disease

BACKGROUND AND AIMS

We investigated oral delivery of transforming growth factor beta 1 [TGFβ]- and all-trans retinoic acid [ATRA]-loaded microspheres as therapy for gut inflammation in murine models of inflammatory bowel disease [IBD].

METHODS

ATRA and TGFβ were separately encapsulated in poly [lactic-co-glycolic] acid or polylactic acid microspheres [respectively]. TGFβ was encapsulated using proprietary phase-inversion nanoencapsulation [PIN] technology.

RESULTS

PIN particles provided sustained release of bioactive protein for at least 4 days and were stable for up to 52 weeks when stored at either 4(0)C or -20(0)C. In the SCID mouse CD4 + CD25- T cell transfer model of IBD, oral treatment starting at disease onset prevented weight loss, significantly reduced average disease score [~ 50%], serum amyloid A levels [~ 5-fold], colon weight-to-length ratio [~ 50%], and histological score [~ 5-fold].

CONCLUSIONS

Both agents given together outperformed either separately. Highest TGFβ doses and most frequent dose schedule were most effective. Activity was associated with a significant increase [45%] in Foxp3 expression by colonic lamina propria CD4+ CD25+ T-cells. Activity was also demonstrated in dextran sulphate sodium-induced colitis. The data support development of the combination product as a novel, targeted immune based therapy for treatment for IBD.

Fibroblast growth factor 2 is required for epithelial recovery, but not for pulmonary fibrosis, in response to bleomycin

The pathogenesis of pulmonary fibrosis involves lung epithelial injury and aberrant proliferation of fibroblasts, and results in progressive pulmonary scarring and declining lung function. In vitro, fibroblast growth factor (FGF) 2 promotes myofibroblast differentiation and proliferation in cooperation with the profibrotic growth factor, transforming growth factor-β1, but the in vivo requirement for FGF2 in the development of pulmonary fibrosis is not known. The bleomycin model of lung injury and pulmonary fibrosis was applied to Fgf2 knockout (Fgf2(-/-)) and littermate control mice. Weight loss, mortality, pulmonary fibrosis, and histology were analyzed after a single intranasal dose of bleomycin. Inflammation was evaluated in bronchoalveolar lavage (BAL) fluid, and epithelial barrier integrity was assessed by measuring BAL protein and Evans Blue dye permeability. Fgf2 is expressed in mouse and human lung epithelial and inflammatory cells, and, in response to bleomycin, Fgf2(-/-) mice have significantly increased mortality and weight loss. Analysis of BAL fluid and histology show that pulmonary fibrosis is unaltered, but Fgf2(-/-) mice fail to efficiently resolve inflammation, have increased BAL cellularity, and, importantly, deficient recovery of epithelial integrity. Fgf2(-/-) mice similarly have deficient recovery of club cell secretory protein(+) bronchial epithelium in response to naphthalene. We conclude that FGF2 is not required for bleomycin-induced pulmonary fibrosis, but rather is essential for epithelial repair and maintaining epithelial integrity after bleomycin-induced lung injury in mice. These data identify that FGF2 acts as a protective growth factor after lung epithelial injury, and call into question the role of FGF2 as a profibrotic growth factor in vivo.

Toxicology of ambient particulate matter

It is becoming increasingly clear that inhalation exposure to particulate matter (PM) can lead to or exacerbate various diseases, which are not limited to the lung but extend to the cardiovascular system and possibly other organs and tissues. Epidemiological studies have provided strong evidence for associations with chronic obstructive pulmonary disease (COPD), asthma, bronchitis and cardiovascular disease, while the evidence for a link with lung cancer is less strong. Novel research has provided first hints that exposure to PM might lead to diabetes and central nervous system (CNS) pathology. In the current review, an overview is presented of the toxicological basis for adverse health effects that have been linked to PM inhalation. Oxidative stress and inflammation are discussed as central processes driving adverse effects; in addition, profibrotic and allergic processes are implicated in PM-related diseases. Effects of PM on key cell types considered as regulators of inflammatory, fibrotic and allergic mechanisms are described.

Activation of NF-κB signaling in rare earth neodymium oxide particle-induced acute lung injury

The activation mechanism of the NF-κB signaling pathway in Nd₂O₃exposure-induced acute lung inflammation and pneumoconiosis.

Current concepts in clinical radiation oncology

Based on its potent capacity to induce tumor cell death and to abrogate clonogenic survival, radiotherapy is a key part of multimodal cancer treatment approaches. Numerous clinical trials have documented the clear correlation between improved local control and increased overall survival. However, despite all progress, the efficacy of radiation-based treatment approaches is still limited by different technological, biological, and clinical constraints. In principle, the following major issues can be distinguished: (1) The intrinsic radiation resistance of several tumors is higher than that of the surrounding normal tissue, (2) the true patho-anatomical borders of tumors or areas at risk are not perfectly identifiable, (3) the treatment volume cannot be adjusted properly during a given treatment series, and (4) the individual heterogeneity in terms of tumor and normal tissue responses toward irradiation is immense. At present, research efforts in radiation oncology follow three major tracks, in order to address these limitations: (1) implementation of molecularly targeted agents and 'omics'-based screening and stratification procedures, (2) improvement of treatment planning, imaging, and accuracy of dose application, and (3) clinical implementation of other types of radiation, including protons and heavy ions. Several of these strategies have already revealed promising improvements with regard to clinical outcome. Nevertheless, many open questions remain with individualization of treatment approaches being a key problem. In the present review, the current status of radiation-based cancer treatment with particular focus on novel aspects and developments that will influence the field of radiation oncology in the near future is summarized and discussed.

Co-culture of human bronchial fibroblasts and CD4+ T cells increases Th17 cytokine signature

BACKGROUND

Airway inflammation is an important characteristic of asthma and has been associated with airway remodelling and bronchial hyperreactivity. The mucosal microenvironment composed of structural cells and highly specialised extracellular matrix is able to amplify and promote inflammation. This microenvironment leads to the development and maintenance of a specific adaptive response characterized by Th2 and Th17. Bronchial fibroblasts produce multiple mediators that may play a role in maintaining and amplifying this response in asthma.

OBJECTIVE

To investigate the role of bronchial fibroblasts obtained from asthmatic subjects and healthy controls in regulating Th17 response by creating a local micro-environment that promotes this response in the airways.

METHODS

Human bronchial fibroblasts and CD4(+)T cells were isolated from atopic asthmatics and non-atopic healthy controls. CD4(+)T were co-cultured with bronchial fibroblasts of asthmatic subjects and healthy controls. RORc gene expression was detected by qPCR. Phosphorylated STAT-3 and RORγt were evaluated by western blots. Th17 phenotype was measured by flow cytometry. IL-22, IL17, IL-6 TGF-β and IL1-β were assessed by qPCR and ELISA.

RESULTS

Co-culture of CD4(+)T cells with bronchial fibroblasts significantly stimulated RORc expression and induced a significant increase in Th17 cells as characterized by the percentage of IL-17(+)/CCR6(+) staining in asthmatic conditions. IL-17 and IL-22 were increased in both normal and asthmatic conditions with a significantly higher amount in asthmatics compared to controls. IL-6, IL-1β, TGF-β and IL-23 were significantly elevated in fibroblasts from asthmatic subjects upon co-culture with CD4(+)T cells. IL-23 stimulates IL-6 and IL-1β expression by bronchial fibroblasts.

CONCLUSION

Interaction between bronchial fibroblasts and T cells seems to promote specifically Th17 cells profile in asthma. These results suggest that cellular interaction particularly between T cells and fibroblasts may play a pivotal role in the regulation of the inflammatory response in asthma.

Recombinant human serum amyloid P in healthy volunteers and patients with pulmonary fibrosis

PRM-151, recombinant human Pentraxin-2 (PTX-2) also referred to as serum amyloid P (SAP), is under development for treatment of fibrosis. A First-in-Human (FIH) trial was performed to assess the safety, tolerability, and pharmacokinetics of single ascending intravenous doses of PRM-151 administered to healthy subjects, using a randomized, blinded, placebo controlled study design. Each cohort included three healthy subjects (PRM-151:placebo; 2:1). SAP levels were assessed using a validated ELISA method, non-discriminating between endogenous and exogenous SAP. At a dose level of 10 mg/kg, at which a physiologic plasma level of SAP was reached, two additional healthy volunteers and three pulmonary fibrosis (PF) patients were enrolled enabling comparison of the pharmacokinetic SAP profile between healthy volunteers and PF patients. In addition, the percentage of fibrocytes (CD45+/Procollagen-1+ cells) in whole blood samples was assessed to demonstrate biological activity of PRM-151 in the target population. PRM-151 administration was generally well tolerated. In two pulmonary fibrosis patients non-specific, transient skin reactions (urticaria and erythema) were observed. PRM-151 administration resulted in a 6-to 13-fold increase in mean baseline plasma SAP levels at dose levels of 5, 10, and 20 mg/kg. The estimated t1/2 of PRM-151 in healthy volunteers was 30 h. Pharmacokinetic profiles were comparable between healthy volunteers and PF patients. PRM-151 administration resulted in a 30-50% decrease in fibrocyte numbers 24 h post-dose. This suggests that administration of PRM-151 may be associated with a reduction of fibrocytes in PF patients, a population for which current pharmacotherapeutic options are limited. The pharmacological action of PRM-151 should be confirmed in future research.

CYLD negatively regulates transforming growth factor-β-signalling via deubiquitinating Akt

Lung injury, whether induced by infection or caustic chemicals, initiates a series of complex wound-healing responses. If uncontrolled, these responses may lead to fibrotic lung diseases and loss of function. Thus, resolution of lung injury must be tightly regulated. The key regulatory proteins required for tightly controlling the resolution of lung injury have yet to be identified. Here we show that loss of deubiquitinase CYLD led to the development of lung fibrosis in mice after infection with Streptococcus pneumoniae. CYLD inhibited transforming growth factor-β-signalling and prevented lung fibrosis by decreasing the stability of Smad3 in an E3 ligase carboxy terminus of Hsc70-interacting protein-dependent manner. Moreover, CYLD decreases Smad3 stability by deubiquitinating K63-polyubiquitinated Akt. Together, our results unveil a role for CYLD in tightly regulating the resolution of lung injury and preventing fibrosis by deubiquitinating Akt. These studies may help develop new therapeutic strategies for preventing lung fibrosis.

Osteopontin modulates inflammation, mucin production, and gene expression signatures after inhalation of asbestos in a murine model of fibrosis

Inflammation and lung remodeling are hallmarks of asbestos-induced fibrosis, but the molecular mechanisms that control these events are unclear. Using laser capture microdissection (LCM) of distal bronchioles in a murine asbestos inhalation model, we show that osteopontin (OPN) is up-regulated by bronchiolar epithelial cells after chrysotile asbestos exposures. In contrast to OPN wild-type mice (OPN(+/+)) inhaling asbestos, OPN null mice (OPN(-/-)) exposed to asbestos showed less eosinophilia in bronchoalveolar lavage fluids, diminished lung inflammation, and decreased mucin production. Bronchoalveolar lavage fluid concentrations of inflammatory cytokines (IL-1β, IL-4, IL-6, IL-12 subunit p40, MIP1α, MIP1β, and eotaxin) also were significantly less in asbestos-exposed OPN(-/-) mice. Microarrays performed on lung tissues from asbestos-exposed OPN(+/+) and OPN(-/-) mice showed that OPN modulated the expression of a number of genes (Col1a2, Timp1, Tnc, Eln, and Col3a1) linked to fibrosis via initiation and cross talk between IL-1β and epidermal growth factor receptor-related signaling pathways. Novel targets of OPN identified include genes involved in cell signaling, immune system/defense, extracellular matrix remodeling, and cell cycle regulation. Although it is unclear whether the present findings are specific to chrysotile asbestos or would be observed after inhalation of other fibers in general, these results highlight new potential mechanisms and therapeutic targets for asbestosis and other diseases (asthma, smoking-related interstitial lung diseases) linked to OPN overexpression.

Prostaglandin E2 and the pathogenesis of pulmonary fibrosis

Prostaglandin (PG)E(2) is a bioactive eicosanoid that regulates many biologically important processes in part due to its ability to signal through four distinct G-protein-coupled receptors with differential signaling activity and unique expression patterns in different cell types. Although PGE(2) has been linked to malignancy in many organs, it is believed to play a beneficial role in the setting of fibrotic lung disease. This is in part due to the ability of PGE(2) to limit many of the pathobiologic features of lung fibroblasts and myofibroblasts, including the ability of PGE(2) to limit fibroblast proliferation, migration, collagen secretion, and, as originally reported in the Journal by us in 2003, the ability to limit transforming growth factor (TGF)-β-induced myofibroblast differentiation. In the setting of lung fibrosis, PGE(2) production and signaling is often diminished. In the last 8 years, significant advances have been made to better understand the dysregulation of PGE(2) production and signaling in the setting of lung fibrosis. We also have a clearer picture of how PGE(2) inhibits myofibroblast differentiation and the receptor signaling pathways that can influence fibroblast proliferation. This review highlights these recent advances and offers new insights into the potential ways that PGE(2) and its downstream signals can be regulated for therapeutic benefit in a disease that has no validated treatment options.

Bleomycin induces upregulation of lysyl oxidase in cultured human fetal lung fibroblasts

AIM

To investigate the mechanism of bleomycin (BLM)-induced pulmonary fibrosis.

METHODS

Cultured human fetal lung fibroblast (HLF) cells were exposed to bleomycin (BLM) at 0-30 microg/mL for 24 h. Western blot analysis was used to detect lysyl oxidase (LO) protein expression. Real-time RT-PCR was used to detect LO mRNA level. LO catalytic activity was measured using diaminopentane as a substrate and Amplex red as a hydrogen peroxide probe. Copper (Cu) concentration was detected by flame atomic absorption spectrophotometry.

RESULTS

Exposure of HLF cells to BLM at 10 microg/mL and 30 microg/mL increased LO catalytic activity to 130% and 158% of the control in the conditioned media. The expression of LO mRNA was increased to 5.5-fold of the control in HLF cells exposure to BLM at 3 microg/mL. BLM at 3 microg/mL also increased the expression of 46 kDa preproLO, 50 kDa proLO and 32 kDa mature LO to 219%, 130%, and 135% of the control, respectively. The Cu concentrations in conditioned media of cultured HLF cells exposed to BLM (10 and 30 microg/mL) were increased significantly to 1.48 and 2.46-fold of the control, respectively.

CONCLUSION

Bleomycin induces upregulation of LO in cultured human fetal lung fibroblasts, which may be the mechanism of bleomycin-induced pulmonary fibrosis.

Discovery of (Z)-5-(4-methoxybenzylidene)thiazolidine-2,4-dione, a readily available and orally active glitazone for the treatment of concanavalin A-induced acute liver injury of BALB/c mice

A large amount of evidence suggests that monocytes/macrophages infiltration is implicated in a variety of inflammatory diseases including acute liver injury. Monocyte chemoattractant protein 1 (MCP-1) plays a crucial role in the process of macrophages recruitment. We herein presented a small-molecule library and a feasible quick screening method of evaluating potency of inhibition of chemotaxis of RAW264.7 cells stimulated by MCP-1. Fifty-three small molecules were synthesized and screened, and four compounds (2g, 2h, 4f, and 6h) showed inhibitory effects with IC(50) values range from 0.72 to 20.47 microM, with compound 4f being the most efficient. Further in vivo studies demonstrated that oral administration of 2g, 2h, 4f, or 6h decreases, most significantly for 4f, the serum levels of alanine aminotransaminase (ALT) and asparate aminotransaminase (AST) in ConA-induced acute livery injury BALB/c mice. Histopathological evaluation liver sections confirmed 4f as a potent, orally active compound for hepatoprotective effects against ConA-induced acute liver injury in BALB/c mice.

Granuloma formation induced by low-dose chronic silica inhalation is associated with an anti-apoptotic response in Lewis rats

Chronic human silicosis results primarily from continued occupational exposure to silica and exhibits a long asymptomatic latency. Similarly, continued exposure of Lewis rats to low doses of silica is known to cause delayed granuloma formation with limited lung inflammation and injury. On the other hand, intratracheal exposure to large doses of silica induces acute silicosis characterized by granuloma-like formations in the lung associated with apoptosis, severe alveolitis, and alveolar lipoproteinosis. To ascertain similarities/differences between acute and chronic silicosis, in this communication, we compared cellular and molecular changes in established rat models of acute and chronic silicosis. In Lewis rats, acute silicosis was induced by intratracheal instillation of 35 mg silica, and chronic silicosis through inhalation of aerosolized silica (6.2 mg/m(3), 5 d/wk for 6 wk). Animals exposed to acute high-dose silica were sacrificed at 14 d after silica instillation while chronically silica-treated animals were sacrificed between 4 d and 28 wk after silica exposure. The lung granulomas formation in acute silicosis was associated with strong inflammation, presence of TUNEL-positive cells, and increases in caspase-3 activity and other molecular markers of apoptosis. On the other hand, lungs from chronically silica-exposed animals exhibited limited inflammation and increased expression of anti-apoptotic markers, including dramatic increases in Bcl-2 and procaspase-3, and lower caspase-3 activity. Moreover, chronic silicotic lungs were TUNEL-negative and overexpressed Bcl-3 and NF-kappaB-p50 but not NF-kappaB-p65 subunits. These results suggest that, unlike acute silicosis, chronic exposures to occupationally relevant doses of silica cause significantly lower lung inflammation and elevated expression of anti-apoptotic rather than proapoptotic markers in the lung that might result from interaction between NF-kappaB-p50 and Bcl-3.

Notch1 signaling in FIZZ1 induction of myofibroblast differentiation

Notch1 is an evolutionarily conserved receptor that regulates cell fate, including such events as differentiation, proliferation, and apoptosis. Myofibroblast differentiation is a key feature of lung fibrosis. Found in inflammatory zone 1 (FIZZ1) has direct fibrogenic properties because of its ability to induce myofibroblast differentiation. However, the downstream signaling pathway that mediates FIZZ1 induction of myofibroblast differentiation remains unknown. The objective of this study was to investigate the involvement of Notch signaling in FIZZ1 induction of lung myofibroblast differentiation and thus explore the potential role of Notch1 in pulmonary fibrosis. The results showed that FIZZ1 increased the expression levels of activated intracellular domain of Notch1 (NIC), its ligand Jagged1, and its target gene Hes1, which were associated with elevated alpha-smooth muscle actin expression levels. Fibroblast alpha-smooth muscle actin expression is induced by the overexpression of NIC but is suppressed by the inhibition of NIC. Moreover, lung fibroblasts that were isolated from mice lacking the GDP-4-keto-6-deoxymannose3,5-epimerase-4-reductase enzyme (FX knockout) exhibited significantly reduced responsiveness to FIZZ1, which was reversed by fucose supplementation. In the absence of exogenous fucose, these FX-deficient cells exhibited defective fucosylation, which is required for Notch signaling. These knockout mice also showed impaired lung fibrosis. These findings suggest that Notch1 signaling in response to FIZZ1 may play a significant role in myofibroblast differentiation during lung fibrosis.

EM703, a new derivative of erythromycin, inhibits transforming growth factor-beta signaling in human lung fibroblasts

Long-term, low-dose macrolide therapy has been proven to improve survival in patients with diffuse panbronchiolitis and cystic fibrosis, although the mechanisms by which it does so remain unknown. To elucidate the molecular mechanisms of the anti-inflammatory effects of macrolides, the authors examined the effects of erythromycin (EM-A) and new derivative EM703 on transforming growth factor (TGF)-beta /Smad signaling fibroblasts. EM-A and EM703 each inhibited fibroblast proliferation and the collagen production in human lung fibroblasts induced by TGF-beta. EM-A and EM703 inhibited the augmentation of Smad3 mRNA induced by TGF-beta. Smad7 mRNA was inhibited by TGF-beta, but augmented by coincubation with EM-A or EM703. EM-A and EM703 each inhibited p-Smad2/3 proteins induced by TGF-beta. Smad7 protein inhibited by TGF-beta restored beyond basal level by EM-A and EM703. These findings suggest that EM-A and EM703 inhibit TGF-beta signaling in human lung fibroblasts via inhibition of p-Smad2/3 through recovery of Smad7 level.

Antioxidants as potential therapeutics for lung fibrosis

Interstitial lung disease encompasses a large group of chronic lung disorders associated with excessive tissue remodeling, scarring, and fibrosis. The evidence of a redox imbalance in lung fibrosis is substantial, and the rationale for testing antioxidants as potential new therapeutics for lung fibrosis is appealing. Current animal models of lung fibrosis have clear involvement of ROS in their pathogenesis. New classes of antioxidant agents divided into catalytic antioxidant mimetics and antioxidant scavengers are being developed. The catalytic antioxidant class is based on endogenous antioxidant enzymes and includes the manganese-containing macrocyclics, porphyrins, salens, and the non-metal-containing nitroxides. The antioxidant scavenging class is based on endogenous antioxidant molecules and includes the vitamin E analogues, thiols, lazaroids, and polyphenolic agents. Numerous studies have shown oxidative stress to be associated with many interstitial lung diseases and that these agents are effective in attenuating fibroproliferative responses in the lung of animals and humans.

Review of the female Duroc/Yorkshire pig model of human fibroproliferative scarring

Hypertrophic scarring after burns is an unsolved problem and remains as devastating today as it was in the 40s and it may be that the main reason for this is the lack of an accepted, useful animal model. The female, red Duroc pig was described as a model of hypertrophic scarring nearly 30 years ago but then vanished from the literature. This seemed strange since the authors reported that 12 of 12 pigs developed thick scar. In the mid 90s we explored the model and found that, indeed, the red Duroc pig does make thick scar. Other authors have established that the Yorkshire pig does not heal in this fashion so there is the possibility of a same species control. We have continued to explore the Duroc/Yorkshire model and herein describe our experiences. Is it a perfect model of hypertrophic scarring? No. Is it a useful model of hypertrophic scarring? Time will tell. We have now obtained gene expression data from the Duroc/Yorkshire model and analysis is underway.

Interleukin 1 receptor antagonist mediates the antiinflammatory and antifibrotic effect of mesenchymal stem cells during lung injury

Mesenchymal stem cells (MSCs) have been exploited as cellular vectors to treat a wide array of diseases but the mechanisms responsible for their therapeutic effect remain indeterminate. Previously, we reported that MSCs inhibit bleomycin (BLM)-induced inflammation and fibrosis within the lungs of mice. Interrogation of the MSC transcriptome identified interleukin 1 receptor antagonist (IL1RN) as a potential mediator of this effect. Fractionation studies indicated that MSCs are the principal source of IL1RN in murine bone marrow and that its expression is restricted to a unique subpopulation of cells. Moreover, MSC-conditioned media was shown to block proliferation of an IL-1alpha-dependent T cell line and inhibit production of TNF-alpha by activated macrophages in vitro. Studies conducted in mice revealed that MSC administration was more effective than recombinant IL1RN delivered via adenoviral infection or osmotic pumps in inhibiting BLM-induced increases in TNF-alpha, IL-1alpha, and IL1RN mRNA in lung, IL1RN protein in bronchoalveolar lavage (BAL) fluid, and trafficking of lymphocytes and neutrophils into the lung. Therefore, MSCs protect lung tissue from BLM-induced injury by blocking TNF-alpha and IL-1, two fundamental proinflammatory cytokines in lung. Identification of IL1RN-expressing human MSC subpopulations may provide a novel cellular vector for treating chronic inflammatory diseases in humans.

An essential role for CCAAT/enhancer binding protein beta in bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is characterized by inflammation, genesis of myofibroblasts, and abnormal tissue repair. Despite extensive research, its pathogenesis remains incompletely understood. Previously, the transcription factor CCAAT/enhancer binding protein beta (C/EBPbeta) was found to be a key regulator of myofibroblast differentiation in vitro, and to be involved in the acute phase and inflammatory responses. In an attempt to test the role of C/EBPbeta in the development of pulmonary fibrosis, experiments using C/EBPbeta null mice and their wild-type littermates were conducted. Our findings indicated that, compared to wild-type mice, animals deficient in C/EBPbeta showed significantly reduced fibrotic lesions and collagen deposition in the lung upon endotracheal injection of bleomycin. Further studies on the mechanisms by which C/EBPbeta regulates fibrosis indicated that knockout of C/EBPbeta attenuates inflammatory cytokine expression in bleomycin-treated mice. The reduced alpha-smooth muscle actin gene expression in either isolated lung fibroblasts or lung tissue from bleomycin or saline-treated C/EBPbeta deficient mice suggests that C/EBPbeta regulates myofibroblast differentiation during fibrosis. Consistent with this finding, cells from C/EBPbeta deficient mice exhibited higher proliferative rates than those from wild-type mice. These data suggest that C/EBPbeta plays an essential role in pulmonary fibrosis and that this role appears to be multifactorial with respect to cytokine expression, cell differentiation, and proliferation.

Oligohydramnios decreases platelet-derived growth factor expression in fetal rat lungs

OBJECTIVE

To evaluate the effects of experimental oligohydramnios on lung growth, expression of platelet-derived growth factor (PDGF) and its receptors, and lung morphology in fetal rats.

METHODS

On day 16 of gestation, we anesthetized timed pregnant Sprague-Dawley dams and punctured uterine wall and fetal membranes of each uterine sac which resulted in oligohydramnios. The fetuses in the opposite uterine horn served as controls. On days 19 and 21 of gestation, the fetuses were delivered by cesarean section and weighed, and the lungs were dissected free and weighed.

RESULTS

Rats exposed to oligohydramnios exhibited significantly lower lung/body weight ratios on days 19 and 21 of gestation and significantly lower radial saccular counts on day 21 of gestation than did the control rats. Lung PDGF-A and PDGF-B gene and protein expression and elastin level were significantly decreased in rats exposed to oligohydramnios on days 19 and 21 of gestation. The PDGF receptor alpha and beta gene expression levels were significantly decreased in rats exposed to oligohydramnios on day 19 of gestation.

CONCLUSION

A decreased PDGF expression may be important in the pathogenesis of oligohydramnios-induced pulmonary hypoplasia and suggests that supplementation may provide useful therapeutic strategies.

A kampo medicine, Yin-Chiao-san, Prevents bleomycin-induced pulmonary injury in rats

Yin-Chiao-San (YCS), a kampo medicine, is widely used for patients with pulmonary disease and was applied for the treatment of SARS in Asia countries in 2003. For this reason, the present study investigated the preventive effect of YCS on bleomycin (BLM)-induced pulmonary fibrosis (PF) in rats. Animals were divided into four groups: (1) saline control group; (2) BLM-induced group, in which 15 mg/kg BLM was intraperitoneally injected three times per week for a period of 5 weeks; (3) BLM + vitamin E (10 mg/kg/day) as a positive group; (4) and BLM + YCS (1000 mg/kg/day). After 35 days, the rats were anesthetized, killed and then the lungs and bronchoalveolar lavage fluids (BALFs) were collected. The attenuation of pulmonary fibrosis was estimated according to the lung index, malondialdehyde (MDA), catalase (CAT), hydroxyproline (HP) and tumor necrosis factor-alpha (TNF-alpha) level in lung tissue and BALF. The serial sections of lung were stained with haematoxylin-eosin and Masson trichrome for histopathological observation of pulmonary fibrosis. The results indicated that YCS significantly reduced the lung index, MDA, HP and TNF-alpha, but YCS significantly enhanced the CAT level when compared with the BLM-induced group (p < 0.05). Additionally, the BLM group displayed severe histopathological change in the lung tissue, but YCS treatment could attenuate the BLM-induced PF. In conclusion, the results demonstrated that YCS possesses antioxidant and antiinflammatory activities and also inhibited collagen formation. Thus, YCS exhibited a preventive effect in BLM-induced PF and it is suggested that YCS may be applied to attenuate the side effects of BLM in chemotherapy.

Engineering of Biologically Active Living Heart Valve Leaflets Using Human Umbilical Cord–Derived Progenitor Cells

This study demonstrates the engineering of biologically active heart valve leaflets using prenatally available human umbilical cord-derived progenitor cells as the only cell source. Wharton's Jelly-derived cells and umbilical cord blood-derived endothelial progenitor cells were subsequently seeded on biodegradable scaffolds and cultured in a biomimetic system under biochemical or mechanical stimulation or both. Depending on the stimulation, leaflets showed mature layered tissue formation with functional endothelia and extracellular matrix production comparable with that of native tissues. This demonstrates the feasibility of heart valve leaflet fabrication from prenatal umbilical cord-derived progenitor cells as a further step in overcoming the lack of living autologous replacements with growth and regeneration potential for the repair of congenital malformation.

Mechanistically identified suitable biomarkers of exposure, effect, and susceptibility for silicosis and coal-worker's pneumoconiosis: a comprehensive review

Clinical detection of silicosis is currently dependent on radiological and lung function abnormalities, both late manifestations of disease. Markers of prediction and early detection of pneumoconiosis are imperative for the implementation of timely intervention strategies. Understanding the underlying mechanisms of the etiology of coal workers pneumoconiosis (CWP) and silicosis was essential in proposing numerous biomarkers that have been evaluated to assess effects following exposure to crystalline silica and/or coal mine dust. Human validation studies have substantiated some of these proposed biomarkers and argued in favor of their use as biomarkers for crystalline silica- and CWP-induced pneumoconiosis. A number of "ideal" biological markers of effect were identified, namely, Clara cell protein-16 (CC16) (serum), tumor necrosis factor-alpha (TNF-alpha) (monocyte release), interleukin-8 (IL-8) (monocyte release), reactive oxygen species (ROS) measurement by chemiluminescence (neutrophil release), 8-isoprostanes (serum), total antioxidant levels measured by total equivalent antioxidant capacity (TEAC), glutathione, glutathione peroxidase activity, glutathione S-transferase activity, and platelet-derived growth factor (PDGF) (serum). TNF-alpha polymorphism (blood cellular DNA) was identified as a biomarker of susceptibility. Further studies are planned to test the validity and feasibility of these biomarkers to detect either high exposure to crystalline silica and early silicosis or susceptibility to silicosis in gold miners in South Africa.

Early changes in basement membrane thickness in airway walls post-lung transplantation

BACKGROUND

Identification of early histopathologic markers of future bronchiolitis obliterans syndrome (BOS) may enable preemptive targeted intervention, delaying and perhaps preventing the onset of BOS. This study aimed to determine if early changes in airway epithelial basement membrane thickness predisposes transplant recipients to the subsequent development of BOS.

METHODS

Basement membrane thickness was measured in serial endobronchial biopsies taken from 29 initially stable lung transplant recipients (sLTR) recruited 148 +/- 80 days post-transplant and followed for 3 years. A further 2 years of clinical follow-up was undertaken without biopsies to follow lung function and define ultimate BOS status. Nine healthy subjects (non-atopic, non-asthmatic) were recruited as controls. Sections of paraffinized endobronchial biopsies were stained for collagen type I immunohistochemically, and basement membrane thickness was assessed by computer image analysis.

RESULTS

BOS developed in 21 of 29 patients in the 5 years of follow-up, 16 of which had endobronchial biopsies available for analysis before BOS developed (ever-BOS). The first endobronchial biopsies showed increased BMT in the combined sLTR and ever-BOS patients compared with the controls. This initial increase in basement membrane thickness resolved to normal levels within 300 days post-transplant, with a strong negative correlation (r2 = 0.424, p < 0.0001) of basement membrane thickness vs time. Paradoxically, the sLTR tended to have the greatest basement membrane thickness at baseline.

CONCLUSION

An initial increase in basement membrane thickness is seen in the airway walls of all lung transplant recipients. This is transient and does not appear to be a risk factor for the subsequent development of BOS in lung allograft recipients.

Short courses of low dose dexamethasone delay bleomycin-induced lung fibrosis in rats

After comparing mortality and clinical signs in rats receiving different dexamethasone treatments, we investigated whether 0.5 mg/kg/d dexamethasone could delay pulmonary fibrosis induced by bleomycin and its time course (1, 3, 7, 14, 21 and 28 days). Tissue injury was assessed by apoptosis, lactate dehydrogenase (LDH) release, malondialdehyde content, and protein content; and inflammation was measured in terms of myeloperoxidase (MPO) activity, inflammatory cell count, and the mRNA expression of pro/inflammatory cytokines. Fibrogenic activity was analyzed by measuring the mRNA expression of fibrotic cytokines in tissue, and the promotion of fibroproliferation and synthesis of collagen type I by bronchoalveolar lavage fluids in vitro; and fibrosis was assessed by measuring the hydroxyproline content and collagen-I mRNA expression, and by histology. Bleomycin treatment induced tissue injury, inflammation and fibrogenic activity in lung, and led to fibrosis. Treatment with dexamethasone diminished the extent of fibrosis by strongly reducing inflammation, lung damage, and fibrogenic activity. These results demonstrate that the progression of bleomycin-induced pulmonary fibrosis in rats can be delayed by dexamethasone treatment, which appeared to alleviate not only inflammation but also lung damage and fibrogenic activity, indicating a possible new role for dexamethasone in the treatment of fibrosis.

Lung inflammatory responses

Inflammation is an important manifestation of respiratory disease in domestic animals. The respiratory system is mucosal in nature and has specific defense mechanisms used to control invasion by microbes and environmental elements. Inflammation can be beneficial or detrimental to the host. This article broadly discusses the primary mediators and mechanisms of inflammation within the respiratory tract of domestic animals. The role of cells, chemokines, cytokines and mediators in both acute and chronic inflammation are addressed. The pathogenesis of the initial insult determines the type of inflammation that will be induced, whether it is acute, chronic or allergic in origin. Maintenance of the microenvironment of cytokines and chemokines is critical for pulmonary homeostasis. Uncontrolled inflammation in the respiratory tract can be life threatening to the animal. The understanding of the mechanisms of inflammation, whether due to microbes or through inappropriate immune activation such as those occurring with allergies, is required to develop successful intervention strategies and control respiratory disease in animals.