JNK inhibition reduces lung remodeling and pulmonary fibrotic systemic markers

Fra-2-expressing macrophages promote lung fibrosis in mice

Idiopathic Pulmonary Fibrosis (IPF) is a deadly disease with limited therapies. Tissue fibrosis is associated with Type 2 immune response, although the causal contribution of immune cells is not defined. The AP-1 transcription factor Fra-2 is upregulated in IPF lung sections and Fra-2 transgenic mice (Fra-2tg) exhibit spontaneous lung fibrosis. Here we show that Bleomycin-induced lung fibrosis is attenuated upon myeloid-inactivation of Fra-2 and aggravated in Fra-2tg bone marrow chimeras. Type VI collagen (ColVI), a Fra-2 transcriptional target, is up-regulated in three lung fibrosis models, and macrophages promote myofibroblast activation in vitro in a ColVI- and Fra-2-dependent manner. Fra-2 or ColVI inactivation does not affect macrophage recruitment and alternative activation, suggesting that Fra-2/ColVI specifically controls the paracrine pro-fibrotic activity of macrophages. Importantly, ColVI knock-out mice (KO) and ColVI-KO bone marrow chimeras are protected from Bleomycin-induced lung fibrosis. Therapeutic administration of a Fra-2/AP-1 inhibitor reduces ColVI expression and ameliorates fibrosis in Fra-2tg mice and in the Bleomycin model. Finally, Fra-2 and ColVI positively correlate in IPF patient samples and co-localize in lung macrophages. Therefore, the Fra-2/ColVI pro-fibrotic axis is a promising biomarker and therapeutic target for lung fibrosis, and possibly other fibrotic diseases.

Follistatin-Like 1 Promotes Bleomycin-Induced Pulmonary Fibrosis through the Transforming Growth Factor Beta 1/Mitogen-Activated Protein Kinase Signaling Pathway

Background

Follistatin-like 1 (FSTL1) is a novel profibrogenic factor that induces pulmonary fibrosis (PF) through the transforming growth factor-beta 1 (TGF-β1)/Smad signaling. Little is known about its effects on PF through the non-Smad signaling, like the mitogen-activated protein kinase (MAPK) pathway. Therefore, this study aimed to investigate the role of FSTL1 in PF through the MAPK signaling pathway and its mechanisms in lung fibrogenesis.

Methods

PF was induced in Fstl1^+/-and wild-type (WT) C57BL/6 mice with bleomycin. After 14 days, the mice were sacrificed, and lung tissues were stained with hematoxylin and eosin; the hydroxyproline content was measured to confirm PF. The mRNA and protein level of FSTL1 and the change of MAPK phosphorylation were measured by quantitative polymerase chain reaction and Western blotting. The effect of Fstl1 deficiency on fibroblasts differentiation was measured by Western blotting and cell immunofluorescence. MAPK signaling activation was measured by Western blotting in Fstl1^+/- and WT fibroblasts treated with recombinant human FSTL1 protein. We pretreated mouse lung fibroblast cells with inhibitors of the extracellular signal-regulated kinase (ERK), p38, and Jun N-terminal kinase (JNK) signaling and analyzed their differentiation, proliferation, migration, and invasion by Western blotting, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis, and transwell assays. The Student's t-test was used to compare the differences between two groups.

Results

Fstl1 deficiency attenuated phosphorylation of the ERK, p38, and JNK signaling in bleomycin-induced fibrotic lung tissue 14 days after injury (0.67 ± 0.05 vs. 1.22 ± 0.03, t = 14.92, P = 0.0001; 0.41 ± 0.01 vs. 1.15 ± 0.07; t = 11.19; P = 0.0004; and 0.41 ± 0.01 vs. 1.07 ± 0.07, t = 8.92, P = 0.0009; respectively), compared with WT lungs at the same time and in primary lung fibroblasts (0.82 ± 0.01 vs. 1.01 ± 0.04, t = 4.06, P = 0.0150; 1.04 ± 0.03 vs. 1.24 ± 0.03, t = 4.44, P = 0.0100; and 0.76 ± 0.05 vs. 0.99 ± 0.05, t = 4.48, P = 0.0100; respectively), compared with TGF-β1-stimulated WT group. Recombinant human FSTL1 protein in lung fibroblasts enhanced TGF-β1-mediated phosphorylation of the ERK (1.19 ± 0.08 vs. 0.55 ± 0.04, t = 6.99, P = 0.0020), p38 (1.18 ± 0.04 vs. 0.66 ± 0.03, t = 11.20, P = 0.0020), and JNK (1.11 ± 0.01 vs. 0.84 ± 0.04, t = 6.53, P = 0.0030), compared with the TGF-β1-stimulated WT group. Fstl1-deficient fibroblasts showed reduced alpha-smooth muscle actin (α-SMA) expression (0.70 ± 0.06 vs. 1.28 ± 0.11, t = 4.65, P = 0.0035, compared with the untreated WT group; 1.40 ± 0.05 vs. 1.76 ± 0.02, t = 6.31, P = 0.0007; compared with the TGF-β1-treated WT group). Compared with the corresponding condition in the control group, the TGF-β1/FSTL1-mediated α-SMA expression was significantly suppressed by pretreatment with an inhibitor of p38 (0.73 ± 0.01 vs. 1.13 ± 0.10, t = 3.92, P = 0.0078) and JNK (0.78 ± 0.03 vs. 1.08 ± 0.06, t = 4.40, P = 0.0046) signaling. The proliferation of mouse lung fibroblast cells (MLgs) significantly decreased after treatment of an inhibitor of p38 (0.30 ± 0.01 vs. 0.46 ± 0.03, t = 4.64, P = 0.0009), JNK (0.30 ± 0.01 vs. 0.49 ± 0.01, t = 12.84, P = 0.0001), and Smad2/3 (0.18 ± 0.02 vs. 0.46 ± 0.02, t = 12.69, P = 0.0001) signaling compared with the dimethylsulfoxide group. The migration and invasion cells of MLgs significantly decreased in medium pretreated with an inhibitor of p38 (70.17 ± 3.28 vs. 116.30 ± 7.11, t = 5.89, P = 0.0042 for the migratory cells; 19.87 ± 0.84 vs. 32.70 ± 0.95, t = 10.14, P = 0.0005 for the invasive cells), JNK (72.30 ± 3.85 vs. 116.30 ± 7.11, t = 5.44, P = 0.0056 for the migratory cells; 18.03 ± 0.94 vs. 32.70 ± 0.95, t = 11.00, P = 0.0004 for the invasive cells), and Smad2/3 (64.76 ± 1.41 vs. 116.30 ± 7.11, t = 7.11, P = 0.0021 for the migratory cells; 18.03 ± 0.94 vs. 32.70 ± 0.95, t = 13.29, P = 0.0002 for the invasive cells) signaling compared with the corresponding condition in the dimethylsulfoxide group.

Conclusion

FSTL1 affects lung fibroblast differentiation, proliferation, migration, and invasion through p38 and JNK signaling, and in this way, it might influence the development of PF.

Novel management strategies for idiopathic pulmonary fibrosis

INTRODUCTION

Idiopathic pulmonary fibrosis (IPF) treatment was revolutionized by the advent of two novel antifibrotics, nintedanib and pirfenidone. However, neither is a panacea and other agents are still sorely needed. This review presents on-going efforts to improve outcomes for patients with IPF by targeting novel pharmacologic pathways, improving comorbidity management, and aiming for improved quality of life. Areas covered: We provide an overview of on-going basic and clinical science efforts focused on development of additional drug therapies for patients with IPF. Known and emerging pathogenic pathways such as the microbiome and pulmonary vasculature hold promise as targets for therapy. While the focus remains on pharmacologic intervention, the impact of comorbidities and their management may also impact patient outcomes significantly. Supportive care with pulmonary rehabilitation, oxygen therapy, and palliative care remain integral at various stages of the disease course. Finally, lung transplant is the only lifesaving intervention for patients with end-stage fibrosis. Expert commentary: Future investigation should aim to prevent the initial insult or injury that engages the multiple pathways associated with the development and progression of IPF. Targeted therapies represent just one management aspect with a multidisciplinary approach necessary for the global holistic care of these complex patients.

Cytokines IL-17, TNF and IFN-γ Alter the Expression of Antimicrobial Peptides and Proteins Disparately: A Targeted Proteomics Analysis using SOMAscan Technology

Antimicrobial peptides, also known as host defence peptides, are immunomodulatory molecules required to resolve infections. Antimicrobial peptides and proteins (APPs) are important in the control of infections in the lungs. Despite evidence that APPs exhibit a wide range of immune functions and modulate inflammation, the effect of inflammatory cytokines on the expression of APPs is not completely defined. In this study, we profiled the expression of 39 different APPs in human bronchial epithelial cells (HBEC) using Slow Off-rate Modified Aptamer (SOMAmer)-based protein array, in the presence and absence of three different inflammatory cytokines (IL-17, TNF and IFN-γ). Expression of 13 different APPs was altered in response to IL-17, TNF or IFN-γ. Independent validations of selected proteins from the proteomics screen i.e., those that were significantly enhanced by >2-fold change (p < 0.01) using western blots conclusively demonstrated that inflammatory cytokines alter the expression of APPs differentially. For example, the abundance of cathepsin S was enhanced by only IFN-γ, whereas lipocalin-2 was increased by IL-17 alone. Abundance of elafin increased in presence of IL-17 or TNF, but decreased in response to IFN-γ. Whereas the abundance of cathepsin V decreased following stimulation with IL-17, TNF and IFN-γ. The results of this study demonstrate that inflammatory cytokines alter the expression of APPs disparately. This suggests that the composition of the inflammatory cytokine milieu may influence APPs abundance and thus alter the processes required for infection control and regulation of inflammation in the lungs.

ASK1 inhibitor treatment suppresses p38/JNK signalling with reduced kidney inflammation and fibrosis in rat crescentic glomerulonephritis

Activation of p38 mitogen‐activated protein kinase (MAPK) and c‐Jun amino terminal kinase (JNK) is prominent in human crescentic glomerulonephritis. p38 and JNK inhibitors suppress crescentic disease in animal models; however, the upstream mechanisms inducing activation of these kinases in crescentic glomerulonephritis are unknown. We investigated the hypothesis that apoptosis signal‐regulating kinase 1 (ASK1/MAP3K5) promote p38/JNK activation and renal injury in models of nephrotoxic serum nephritis (NTN); acute glomerular injury in SD rats, and crescentic disease in WKY rats. Treatment with the selective ASK1 inhibitor, GS‐444217 or vehicle began 1 hour before nephrotoxic serum injection and continued until animals were killed on day 1 (SD rats) or 14 (WKY rats). NTN resulted in phosphorylation (activation) of p38 and c‐Jun in both models which was substantially reduced by ASK1 inhibitor treatment. In SD rats, GS‐444217 prevented proteinuria and glomerular thrombosis with suppression of macrophage activation on day 1 NTN. In WKY rats, GS‐444217 reduced crescent formation, prevented renal impairment and reduced proteinuria on day 14 NTN. Macrophage activation, T‐cell infiltration and renal fibrosis were also reduced by GS‐444217. In conclusion, GS‐444217 treatment inhibited p38/JNK activation and development of renal injury in rat NTN. ASK1 inhibitors may have therapeutic potential in rapidly progressive glomerulonephritis.

The positive role of vitronectin in radiation induced lung toxicity: the in vitro and in vivo mechanism study

Background

Radiation-induced lung toxicity (RILT) is a severe complication of radiotherapy in patients with thoracic tumors. Through proteomics, we have previously identified vitronectin (VTN) as a potential biomarker for patients with lung toxicity of grade ≥ 2 radiation. Herein, we explored the molecular mechanism of VTN in the process of RILT.

Methods

In this study, lentivirus encoding for VTN and VTN-specific siRNA were constructed and transfected into the cultured fibroblasts and C57BL mice. Real-time PCR, western blot and ELISA were used to examine expression of collagens and several potential proteins involved in lung fibrosis. Hematoxylin–eosin and immunohistochemical staining were used to assess the fibrosis scores of lung tissue from mice received irradiation.

Results

The expression of VTN was up-regulated by irradiation. The change trend of collagens, TGF-β expression and p-ERK, p-AKT, and p-JNK expression levels were positively related with VTN mRNA level. Furthermore, overexpression of VTN significantly increased the expression level of α-SMA, as well as the degree of lung fibrosis in mice at 8 and 12 weeks post-irradiation. By contrast, siRNA VTN induced opposite results both in vitro and in vivo.

Conclusions

VTN played a positive role in the lung fibrosis of RILT, possibly through modulation of fibrosis regulatory pathways and up-regulating the expression levels of fibrosis-related genes. Taken together, all the results suggested that VTN had a novel therapeutic potential for the treatment of RILT.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1474-y) contains supplementary material, which is available to authorized users.

Design, synthesis and ability of non-gold complexed substituted purine derivatives to inhibit LPS-induced inflammatory response

In order to study the anti-inflammatory activity of novel 6-substituted and 6,9-disubstituted purine derivatives, 20 compounds, L1-10 and W1-10, derived from purine and lacking a gold complex were designed, synthesized and their anti-inflammatory activity was screened. LPS-induced TNF-α, IL-1β, IL-6, PGE2, NO, COX-2 and iNOS mRNA were evaluated, and western blot and NF-κB p65 translocation assay were performed in RAW 264.7 macrophages. Furthermore, carrageenan-induced hind paw edema experiments were performed in mice. Compound L1, L4, W2, and W4 markedly exerted a dose-dependent inhibition of TNF-α, IL-1β, IL-6 and PGE2 release induced by LPS in RAW 264.7 macrophages. Moreover, these compounds strongly inhibited LPS-induced NO, COX-2 and iNOS mRNA in the same cells. Anti-inflammatory activity tests in vivo showed that L1 and L4 were more effective than Au(L₃)(PPh₃), a known anti-inflammatory agent, at 2-5 h, and W4 was the most effective at 3-5 h after dosing. Thus, W2, W4, and L1, L4, could effectively inhibit LPS-induced inflammatory response in vitro and in vivo suggesting a promising role as anti-inflammatory agents.

MicroRNA-221/222 Family Counteracts Myocardial Fibrosis in Pressure Overload-Induced Heart Failure

Pressure overload causes cardiac fibroblast activation and transdifferentiation, leading to increased interstitial fibrosis formation and subsequently myocardial stiffness, diastolic and systolic dysfunction, and eventually heart failure. A better understanding of the molecular mechanisms underlying pressure overload-induced cardiac remodeling and fibrosis will have implications for heart failure treatment strategies. The microRNA (miRNA)-221/222 family, consisting of miR-221-3p and miR-222-3p, is differentially regulated in mouse and human cardiac pathology and inversely associated with kidney and liver fibrosis. We investigated the role of this miRNA family during pressure overload-induced cardiac remodeling. In myocardial biopsies of patients with severe fibrosis and dilated cardiomyopathy or aortic stenosis, we found significantly lower miRNA-221/222 levels as compared to matched patients with nonsevere fibrosis. In addition, miRNA-221/222 levels in aortic stenosis patients correlated negatively with the extent of myocardial fibrosis and with left ventricular stiffness. Inhibition of both miRNAs during AngII (angiotensin II)-mediated pressure overload in mice led to increased fibrosis and aggravated left ventricular dilation and dysfunction. In rat cardiac fibroblasts, inhibition of miRNA-221/222 derepressed TGF-β (transforming growth factor-β)-mediated profibrotic SMAD2 (mothers against decapentaplegic homolog 2) signaling and downstream gene expression, whereas overexpression of both miRNAs blunted TGF-β-induced profibrotic signaling. We found that the miRNA-221/222 family may target several genes involved in TGF-β signaling, including JNK1 (c-Jun N-terminal kinase 1), TGF-β receptor 1 and TGF-β receptor 2, and ETS-1 (ETS proto-oncogene 1). Our findings show that heart failure-associated downregulation of the miRNA-221/222 family enables profibrotic signaling in the pressure-overloaded heart.

The JNK Signaling Pathway in Renal Fibrosis

Fibrosis of the glomerular and tubulointerstitial compartments is a common feature of chronic kidney disease leading to end-stage renal failure. This fibrotic process involves a number of pathologic mechanisms, including cell death and inflammation. This review focuses on the role of the c-Jun amino terminal kinase (JNK) signaling pathway in the development of renal fibrosis. The JNK pathway is activated in response to various cellular stresses and plays an important role in cell death and inflammation. Activation of JNK signaling is a common feature in most forms of human kidney injury, evident in both intrinsic glomerular and tubular cells as well as in infiltrating leukocytes. Similar patterns of JNK activation are evident in animal models of acute and chronic renal injury. Administration of JNK inhibitors can protect against acute kidney injury and suppress the development of glomerulosclerosis and tubulointerstitial fibrosis. In particular, JNK activation in tubular epithelial cells may be a pivotal mechanism in determining the outcome of both acute kidney injury and progression of chronic kidney disease. JNK signaling promotes tubular epithelial cell production of pro-inflammatory and pro-fibrotic molecules as well as tubular cell de-differentiation toward a mesenchymal phenotype. However, the role of JNK within renal fibroblasts is less well-characterized. The JNK pathway interacts with other pro-fibrotic pathways, most notable with the TGF-β/SMAD pathway. JNK activation can augment TGF-β gene transcription, induce expression of enzymes that activate the latent form of TGF-β, and JNK directly phosphorylates SMAD3 to enhance transcription of pro-fibrotic molecules. In conclusion, JNK signaling plays an integral role in several key mechanisms operating in renal fibrosis. Targeting of JNK enzymes has therapeutic potential for the treatment of fibrotic kidney diseases.

c-Jun N-terminal kinase in pancreatic tumor stroma augments tumor development in mice

Pancreatic ductal adenocarcinoma (PDAC) is a life‐threatening disease and there is an urgent need to develop improved therapeutic approaches. The role of c‐Jun N‐terminal kinase (JNK) in PDAC stroma is not well defined even though dense desmoplastic reactions are characteristic of PDAC histology. We aimed to explore the role of JNK in PDAC stroma in mice. We crossed Ptf1a^Cre/+;Kras^G12D/+ mice with JNK1^−/− mice to generate Ptf1a^Cre/+;Kras^G12D/+;JNK1^−/− (Kras;JNK1^−/−) mice. Tumor weight was significantly lower in Kras;JNK1^−/− mice than in Kras;JNK1^+/− mice, whereas histopathological features were similar. We also transplanted a murine PDAC cell line (mPC) with intact JNK1 s.c. into WT and JNK1^−/− mice. Tumor diameters were significantly smaller in JNK1^−/− mice. Phosphorylated JNK (p‐JNK) was activated in α‐smooth muscle actin (SMA)‐positive cells in tumor stroma, and mPC‐conditioned medium activated p‐JNK in tumor‐associated fibroblasts (TAF) in vitro. Relative expression of Ccl20 was downregulated in stimulated TAF. Ccl20 is an important chemokine that promotes CD8⁺ T‐cell infiltration by recruitment of dendritic cells, and the number of CD8⁺ T cells was decreased in Kras;JNK1^+/− mice compared with Kras;JNK1^−/− mice. These results suggest that the cancer secretome decreases Ccl20 secretion from TAF by activation of JNK, and downregulation of Ccl20 secretion might be correlated with reduction of infiltrating CD8⁺ T cells. Therefore, we concluded that inhibition of activated JNK in pancreatic tumor stroma could be a potential therapeutic target to increase Ccl20 secretion from TAF and induce accumulation of CD8⁺ T cells, which would be expected to enhance antitumor immunity.

Lipoteichoic acid upregulates plasminogen activator inhibitor-1 expression in parapneumonic effusions

BACKGROUND AND OBJECTIVE

Parapneumonic effusion (PPE) is commonly caused by Gram-positive bacteria (GPB) and often presents with pleural loculation, which is characterized by overproduction of plasminogen activator inhibitor (PAI)-1. Lipoteichoic acid (LTA), a surface adhesion molecule of GPB, binds to the pleural mesothelium and triggers inflammation. However, the effects of LTA on PAI-1 expression in PPE and underlying mechanisms remain unclear.

METHODS

Thirty consecutive patients with PPE were enrolled, including uncomplicated culture negative (CN, n = 11), Gram-negative bacteria (GNB, n = 7) and GPB (n = 12) groups stratified by pleural fluid characteristics and bacteriology, and the effusion PAI-1 levels were measured. In addition, human pleural mesothelial cells (PMC) were treated with LTA and the expression of PAI-1 and activation of signalling pathways were assayed.

RESULTS

The median levels of PAI-1 were significantly higher in GPB (160.5 ng/mL) and GNB (117.0 ng/mL) groups than in the uncomplicated CN (58.0 ng/mL) group. In human PMC, LTA markedly upregulated PAI-1 mRNA and protein expression and enhanced elaboration of Toll-like receptor 2 (TLR2). Furthermore, LTA increased c-Jun N-terminal kinase (JNK) phosphorylation, induced activating transcription factor 2 (ATF2)/c-Jun nuclear translocation and activated PAI-1 promoter activity. Pretreatment with TLR2 siRNA significantly inhibited LTA-induced JNK phosphorylation and PAI-1 protein expression.

CONCLUSION

Culture-positive PPE, especially that caused by GPB, has a significantly higher level of PAI-1 than uncomplicated CN PPE. LTA upregulates PAI-1 expression through activation of TLR2/JNK/activator protein 1 (AP-1) pathway in human PMC. Better understanding of the modulation of PAI-1 synthesis by LTA in PPE may provide potential therapies for infected pleural effusions.