Transforming growth factor beta 1 activation, storage, and signaling pathways in idiopathic pulmonary fibrosis in dogs

Osteopontin and fibronectin in lung tissue, serum, and bronchoalveolar lavage fluid of dogs with idiopathic pulmonary fibrosis and control dogs

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) affects West Highland white terriers (WHWTs). Osteopontin (SPP1) and fibronectin (FN1) are associated with human IPF and are overexpressed by bronchoalveolar lavage fluid (BALF) macrophages in dogs with IPF.

OBJECTIVE

To investigate the value of these proteins as biomarkers of IPF.

ANIMALS

West Highland white terriers (WHWTs) with IPF, control WHWTs, and terriers.

METHODS

Cross-sectional observational study. Immunohistochemistry was used to localize SPP1 and FN1 in lung tissue. Serum and BALF SPP1 and FN1 concentrations were measured using canine ELISA kits and compared between groups.

RESULTS

Osteopontin stained ciliated epithelial cells, smooth muscular cells, and macrophages of all included dogs, and type-II pneumocytes and extracellular matrix of all 12 diseased WHWTs, 4/6 control WHWTs, and none of the 3 terriers. Osteopontin serum concentration was higher in diseased WHWTs (n = 22; 2.15 ng/mL [0.74-5.30]) compared with control WHWTs (n = 13; 0.63 ng/mL [0.41-1.63]; P = .005) and terriers (n = 15; 0.31 ng/mL [0.19-0.51]; P < .0001), and in control WHWTs compared with terriers (P = .005). Osteopontin BALF concentrations were higher in diseased (0.27 ng/mL [0.14-0.43]) and control WHWTs (0.25 ng/mL [0.14-0.40]), compared with terriers (0.02 ng/mL [0.01-0.08]; P < .0001 and P = .003, respectively). Fibronectin (FN1) serum concentrations were lower in diseased dogs (1.03 ng/mL [0.35-1.48]) and control WHWTs (0.61 ng/mL [0.24-0.65]) compared with terriers (2.72 ng/mL [0.15-5.21]; P < .0001 and P = .0001, respectively). There was no difference in FN1 immunostaining and FN1 BALF concentrations between groups.

CONCLUSIONS

Results suggest that SPP1 is involved in pathogenesis of IPF and could predispose that breed to the disease. Osteopontin serum concentration could serve as a diagnostic biomarker of IPF.

Bryodulcosigenin attenuates bleomycin-induced pulmonary fibrosis via inhibiting AMPK-mediated mesenchymal epithelial transition and oxidative stress

Fibrosis is a pathological result of a dysfunctional repair response to tissue injury and occurs in several organs, including the lungs. Bryodulcosigenin (BDG) is a cucurbitane-type triterpene isolated from Siratia grosvenori and has clear-cut anti-inflammatory effects, yet its benefit of pulmonary fibrosis (PF) remains unclear. In this study, we investigated the protective effects of BDG (10 mg/kg/day, for 14 days) against TGF-β1-stimulated mouse alveolar epithelial MLE-12 cells and bleomycin (BLM)-induced PF mice. In vitro experiments showed that BDG could inhibit epithelial-mesenchymal transition (EMT) and oxidative stress. In vivo experiments indicated that BDG could ameliorate BLM-induced PF in mice as evidenced by characteristic structural changes in histopathology, increased collagen deposition and reduced survival and weight of mice. The abnormal increased expressions of TGF-β1, p-Smad2/3, α-SMA, COL-I, and NOX4 and decreased expressions for Sirt1 and p-AMPK were improved in BDG treatment. But these beneficial effects could be eliminated by co-treatment with Compound C (CC, a selective AMPK inhibitor). Molecular docking technology also revealed the potential of BDG to activate AMPK. In summary, AMPK activation modulated by BDG not only ameliorated TGF-β1/Smad2/3 signaling pathways but also partially mediated the suppression effects on EMT and oxidative stress, thus mediating the anti-fibrotic effects.

Quantitative proteomic analysis of bronchoalveolar lavage fluid in West Highland white terriers with canine idiopathic pulmonary fibrosis

Background

Canine idiopathic pulmonary fibrosis (CIPF) is a chronic, progressive, interstitial fibrosing lung disease, manifesting as cough, exercise intolerance and ultimately, dyspnea and respiratory failure. It mainly affects West Highland white terriers (WHWTs), lacks curable treatment and has a poor prognosis. Aspiration of gastroesophageal refluxate may play a role in the development of CIPF. In the first part of this study, we completed label-free quantitative proteomic analysis of bronchoalveolar lavage fluid (BALF) from CIPF and healthy WHWTs. In the second part, we evaluated potential protein markers of reflux aspiration from canine gastric juice and vomitus and whether these were present in BALF from the two groups.

Results

Across all BALF samples, 417 proteins were identified, and of these, 265 proteins were identified by two or more unique tryptic peptides. Using the 265 high confidence assignments, the quantitative proteome profiles were very similar in the two cohorts, but they could be readily resolved by principal component analysis on the basis of differential protein expression. Of the proteins that were differentially abundant in the two groups, several (including inflammatory and fibrotic markers) were elevated in CIPF, and a smaller, more diverse group of proteins were diminished in CIPF. No protein markers indicative of reflux aspiration were identified.

Conclusions

Label-free proteomics allowed discrimination between CIPF and healthy WHWTs, consistent with fibrotic process but did not provide clear evidence for gastrointestinal aspiration. The measurement of proteins may provide a proteomics signature of CIPF that could be used to evaluate treatment options.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03202-x.

Interleukin 10 and transforming growth factor-beta 1 plasma levels in atopic dogs before and during immunotherapy

BACKGROUND

Human studies suggest that the cytokines, interleukin 10 (IL-10) and transforming growth factor-beta 1 (TGF-ß1) may play an important role in allergen-specific immunotherapy (ASIT). However, there is little known about the function of these cytokines in atopic dogs. This study compared the plasma levels of IL-10 and TGF-ß1 in atopic and control dogs and investigated their changes during different ASIT approaches.

METHODS

A total of 54 atopic and 32 control dogs were included. Immunotherapy was performed in 30 atopic dogs. The dogs undergoing immunotherapy were allocated to four groups of different ASIT approaches (namely subcutaneous, intralymphatic, sublingual ASIT and subcutaneous ASIT with recombinant allergens). Blood samples were collected at four timepoints throughout the one year of ASIT. Canine atopic dermatitis extent and severity index, pruritus visual analogue scale and medication score were recorded at each timepoint. Commercially available ELISA kits were used to quantify IL-10 and TGF-ß1 in plasma.

RESULTS

There was no significant difference in IL-10 and TGF-ß1 between atopic and control dogs. The IL-10 levels were significantly increased in the intralymphatic group at the end of the study. No significant differences were found in the other groups for both IL-10 and TGF-ß1.

CONCLUSION

The findings of this work suggest that IL-10 and TGF-ß1 cannot be used to monitor the course of the disease during ASIT.

LncRNA CTD-2528L19.6 prevents the progression of IPF by alleviating fibroblast activation

Long non-coding RNAs (lncRNAs) have emerged as critical factors for regulating multiple biological processes during organ fibrosis. However, the mechanism of lncRNAs in idiopathic pulmonary fibrosis (IPF) remains incompletely understood. In the present study, two sets of lncRNAs were defined: IPF pathogenic lncRNAs and IPF progression lncRNAs. IPF pathogenic and progression lncRNAs-mRNAs co-expression networks were constructed to identify essential lncRNAs. Network analysis revealed a key lncRNA CTD-2528L19.6, which was up-regulated in early-stage IPF compared to normal lung tissue, and subsequently down-regulated during advanced-stage IPF. CTD-2528L19.6 was indicated to regulate fibroblast activation in IPF progression by mediating the expression of fibrosis related genes LRRC8C, DDIT4, THBS1, S100A8 and TLR7 et al. Further studies showed that silencing of CTD-2528L19.6 increases the expression of Fn1 and Collagen I both at mRNA and protein levels, promoted the transition of fibroblasts into myofibroblasts and accelerated the migration and proliferation of MRC-5 cells. In contrast, CTD-2528L19.6 overexpression alleviated fibroblast activation in MRC-5 cells induced by TGF-β1. LncRNA CTD-2528L19.6 inhibited fibroblast activation through regulating the expression of LRRC8C in vitro assays. Our results suggest that CTD-2528L19.6 may prevent the progression of IPF from early-stage and alleviate fibroblast activation during the advanced-stage of IPF. Thus, exploring the regulatory effect of lncRNA CTD-2528L19.6 may provide new sights for the prevention and treatment of IPF.

Matrix metalloproteinase-2, -7, and -9 activities in dogs with idiopathic pulmonary fibrosis compared to healthy dogs and dogs with other respiratory diseases

BACKGROUND

Canine idiopathic pulmonary fibrosis (CIPF) is a chronic, interstitial lung disease that mainly affects West Highland white terriers (WHWTs) and is characterized by excessive deposition of extracellular matrix (ECM) in the lung. Matrix metalloproteinases (MMPs) participate in remodeling of ECM.

OBJECTIVES

To compare metalloproteinase-2, -7 and -9 activities in blood or bronchoalveolar lavage fluid (BALF) samples or both of CIPF WHWTs with healthy WHWTs, healthy dogs of other breeds, and dogs with other lung diseases and determine if these MMPs could be used as diagnostic and prognostic markers for CIPF.

ANIMALS

Forty-four CIPF WHWTs, 24 dogs with chronic bronchitis (CB), 17 with eosinophilic bronchopneumopathy (EBP), 10 with bacterial pneumonia, 39 healthy WHWTs, and 35 healthy dogs of other breeds.

METHODS

Cross-sectional observational study. Pro-MMP and active MMP activities were analyzed by zymography.

RESULTS

In serum, significantly higher (P < .01) pro-MMP-7 activities were observed in CIPF WHWTs compared to healthy dogs of other breeds, dogs with CB and dogs with EBP. In BALF of CIPF WHWTs, both pro-MMP-9 and pro-MMP-2 activities were significantly higher (P < .01) compared to healthy WHWTs, but these differences were not detected in plasma. The CIPF WHWTs had significantly higher (P < .05) activities of pro-MMP-9 compared to dogs with CB and of pro-MMP-2 compared to dogs with CB and EBP. No statistically significant prognostic factors were observed in CIPF WHWTs.

CONCLUSIONS AND CLINICAL RELEVANCE

Serum MMP-7 and BALF MMP-2 and -9 potentially may be useful diagnostic markers but not prognostic markers for CIPF.

Effects of tacrolimus on the TGF‑β1/SMAD signaling pathway in paraquat‑exposed rat alveolar type II epithelial cells

Paraquat is a highly toxic pesticide, which often causes pulmonary interstitial fibrosis after poisoning, and there is no specific antidote. At present, limited studies have reported that tacrolimus, as an immunosuppressant, can inhibit pulmonary fibrosis, but the specific mechanism remains unknown. The aim of the present study was to demonstrate the effect of tacrolimus on the TGF-β1 pathway associated with pulmonary fibrosis in paraquat exposed alveolar type II epithelial cells, and to identify the antipulmonary fibrosis mechanism of tacrolimus The rat alveolar epithelial type II RLE-6TN cell line was exposed to paraquat and treated with or without tacrolimus for 24 h, or with a TGF-β1 receptor type I/II inhibitor (LY2109761) for 1, 4, 8 or 16 h. MTT assays were used to detect the viability of rat alveolar type II epithelial cells under these different treatment conditions, while the concentrations of TGF-β1, SMAD3, SMAD7 and connective tissue growth factor (CTGF) in the cell culture supernatant were determined using ELISAs. Additionally, reverse transcription-quantitative PCR and immunofluorescence were used to analyze the mRNA and protein expression levels of TGF-β1, SMAD3, CTGF and SMAD7. The results demonstrated that the inhibition of the proliferation of RLE-6TN cells exposed to 200 nmol/l paraquat was 26.05±2.99%. The inhibition rate of 10 ng/ml tacrolimus on paraquat-exposed alveolar type II epithelial cells was 18.40±3.49%. The inhibition rate caused by 5 µmol/l LY2109761 was 26.56±4.49%. The expression levels of TGF-β1, SMAD3 and CTGF, as well as their concentrations in the culture supernatant, were significantly downregulated in the tacrolimus group compared with the paraquat group. However, both the concentration and expression levels of SMAD7 were significantly upregulated in the tacrolimus group compared with the paraquat group. In conclusion, tacrolimus can reduce the levels of TGF-β1, SMAD3 and CTGF, increase the level of SMAD7 in TGF-β1 signaling pathway and protect the development of pulmonary fibrosis in paraquat exposed alveolar epithelial cells.

Human ucMSCs seeded in a decellularized kidney scaffold attenuate renal fibrosis by reducing epithelial-mesenchymal transition via the TGF-β/Smad signaling pathway

BACKGROUND

Renal fibrosis occurs largely through epithelial-mesenchymal transition (EMT). This study explored the beneficial effects of a human umbilical cord mesenchymal stem cell-loaded decellularized kidney scaffold (ucMSC-DKS) on renal fibrosis in a rodent model of post-transplantation renal failure, and the underlying mechanism.

METHODS

Rat-derived DKSs were examined after preparation, and then recellularized with human ucMSCs to prepare cell-loaded patches. A rat model of renal failure was established after subtotal nephrectomy (STN). The cell patches were transplanted to remnant kidneys. Changes in renal function, histology, EMT, and proteins related to the transforming growth factor-β (TGF-β)/Smad signaling pathway in the remnant kidneys were examined 8 weeks after surgery, compared with non-cell patch controls.

RESULTS

The DKSs were acellular and porous, with rich cytokine and major extracellular matrix components. The ucMSCs were distributed uniformly in the DKSs. Renal function was improved, renal fibrosis and EMT were reduced, and the TGF-β/Smad signaling pathway was inhibited compared with controls at 8 weeks after ucMSC-DKS patch transplantation.

CONCLUSIONS

The ucMSC-DKS restores renal function and reduces fibrosis by reducing EMT via the TGF-β/Smad signaling pathway in rats that have undergone STN. It provides an alternative for renal fibrosis treatment.

Association of Common Genetic Variants in the CPSF7 and SDHAF2 Genes with Canine Idiopathic Pulmonary Fibrosis in the West Highland White Terrier

Canine idiopathic pulmonary fibrosis (CIPF) is a chronic fibrotic lung disease that is observed at a higher frequency in the West Highland White Terrier dog breed (WHWT) and may have molecular pathological overlap with human lung fibrotic disease. We conducted a genome-wide association study (GWAS) in the WHWT using whole genome sequencing (WGS) to discover genetic variants associated with CIPF. Saliva-derived DNA samples were sequenced using the Riptide DNA library prep kit. After quality controls, 28 affected, 44 unaffected, and 1,843,695 informative single nucleotide polymorphisms (SNPs) were included in the GWAS. Data were analyzed both at the single SNP and gene levels using the GEMMA and GATES methods, respectively. We detected significant signals at the gene level in both the cleavage and polyadenylation specific factor 7 (CPSF7) and succinate dehydrogenase complex assembly factor 2 (SDHAF2) genes (adjusted p = 0.016 and 0.024, respectively), two overlapping genes located on chromosome 18. The top SNP for both genes was rs22669389; however, it did not reach genome-wide significance in the GWAS (adjusted p = 0.078). Our studies provide, for the first time, candidate loci for CIPF in the WHWT. CPSF7 was recently associated with lung adenocarcinoma, further highlighting the potential relevance of our results because IPF and lung cancer share several pathological mechanisms.

Update on Canine Idiopathic Pulmonary Fibrosis in West Highland White Terriers

Canine idiopathic pulmonary fibrosis (CIPF) is a chronic, progressive, interstitial lung disease (ILD) affecting older West Highland white terriers (WHWTs). According to one classification, CIPF is a familial fibrotic ILD in the group of idiopathic interstitial pneumonias. Etiology is unknown but likely arises from interplay between genetic and environmental factors. CIPF shares features with human idiopathic pulmonary fibrosis and human nonspecific interstitial pneumonia. This article describes clinical signs, findings in physical examination, arterial oxygenation, diagnostic imaging, bronchoscopy, bronchoalveolar lavage, histopathology, disease course, and outcome of WHWTs with CIPF; compares canine and human diseases; summarizes biomarker research; and gives an overview of potential treatment.

Haemostatic, fibrinolytic and inflammatory profiles in West Highland white terriers with canine idiopathic pulmonary fibrosis and controls

BACKGROUND

Canine idiopathic pulmonary fibrosis (CIPF) is a progressive interstitial lung disease mainly affecting old West Highland white terriers (WHWTs). The aetiology of CIPF is currently unknown and pathogenesis poorly understood. A genetic basis is strongly suspected based on the breed predisposition. CIPF shares clinical and pathological features with human IPF. In human IPF, coagulation disorders favouring a local and systemic pro-thrombotic state have been demonstrated in association with disease severity and outcome. The aim of this study was to compare the systemic haemostatic, fibrinolytic and inflammatory profiles of WHWTs affected with CIPF with breed-matched controls (CTRLs). Additionally, data collected in both groups were interpreted with regard to the reference intervals (when available) to assess possible pro-thrombotic features of the WHWT breed that may be related to CIPF predisposition. A total of 14 WHWTs affected with CIPF and 20 CTRLs were included.

RESULTS

WHWTs affected with CIPF had prolonged activated partial thromboplastine time in comparison with CTRLs (12.2 ± 0.9 s vs. 11.5 ± 0.7 s, P = 0.028), whereas results obtained in both groups were all within reference ranges. There was no significant difference between groups for the other factors assessed including plasmatic concentrations of fibrinogen, D-dimers concentration, antithrombin III activity, protein S and protein C activities, anti-factor Xa activity, activated protein C ratio, serum C-reactive protein concentration, and rotational thromboelastometry indices. Platelet count and plasmatic fibrinogen concentration were found to be above the upper limit of the reference range in almost half of the WHWTs included, independently of the disease status.

CONCLUSIONS

Results of this study provide no clear evidence of an altered systemic haemostatic, fibrinolytic or inflammatory state in WHWTs affected with CIPF compared with CTRLs. The higher platelet counts and fibrinogen concentrations found in the WHWT breed may serve as predisposing factors for CIPF or simply reflect biological variation in this breed.

Yangyin Yiqi Mixture Ameliorates Bleomycin-Induced Pulmonary Fibrosis in Rats through Inhibiting TGF-β1/Smad Pathway and Epithelial to Mesenchymal Transition

Objective

The aim of the current study was to investigate the protective effect of Yangyin Yiqi Mixture (YYYQ) on Bleomycin-induced pulmonary fibrosis in rats based on TGF-β1/Smad signal pathway and epithelial to mesenchymal transition (EMT).

Methods

120 Wistar rats were randomly divided into six groups: control group, BLM group, BLM + Pred group, BLM+YYYQ-L group, BLM+YYYQ-M group, and BLM+YYYQ-H group. Rats were given an intratracheal instillation of 3 mg/kg BLM to establish the pulmonary fibrosis model and followed by different dosages of YYYQ (11, 22, 44g/kg, via intragastric gavage) or prednisone soluble (4.2mg/kg, via intragastric gavage) or water. After 14 days and 28 days, tissue sections were stained with hematoxylin-eosin and Masson's trichrome to observe histopathological changes. Protein levels of TGF-β1, CTGF, Interleukin 18, and hydroxyproline were detected by ELISA method, and mRNA expressions of TGF-β1, TβRI, TβRII, Smad3, Smad7, α-SMA, E-cadherin, laminin, and collagen I were detected by RT-PCR.

Results

TGF-β1, CTGF, Interleukin 18, and hydroxyproline levels and mRNA expression of TGF-β1, TβRI, TβRII, Smad3, α-SMA, laminin, and collagen I were significantly increased (p <0.01), while Smad7 and E-cadherin levels were significantly decreased in BLM group (p <0.01). YYYQ-M and YYYQ-H group had downregulated the TGF-β1, CTGF, hydroxyproline contents, and mRNA expression of TGF-β1, TβRI, TβRII, Smad3, α-SMA, laminin, and collagen I and upregulated mRNA levels of Smad7 and E-cadherin significantly (p <0.01 or p <0.05). The result from the present study, which was also supported by histological evidence, suggested that YYYQ-M group and YYYQ-H group exhibited better treatment effect on Bleomycin-induced pulmonary fibrotic rats when compared to that of BLM + Pred group (p <0.01). Meanwhile, the effect of YYYQ, in three different dosages, on the level of interleukin 18 was not significant.

Conclusion

These results showed that YYYQ has the potential of ameliorating the progression of pulmonary fibrosis, and the mechanism may be related to suppressing TGF-β1/Smad signal pathway and EMT in BLM-induced pulmonary fibrosis of rats.

Idiopathic pulmonary fibrosis in West Highland white terriers: An update

Canine idiopathic pulmonary fibrosis (CIPF) affects middle-aged to older dogs of a single breed, mainly the West Highland white terrier (WHWT), which is suggestive of a genetic predisposition. CIPF causes exercise intolerance, restrictive dyspnoea and coughing. Coarse crackles are heard on thoracic auscultation. Abnormal blood gas parameters and a shortened '6-min-walking test' distance are common; secondarily induced pulmonary hypertension and/or airway collapse are frequent. These features of CIPF mimic those of idiopathic pulmonary fibrosis (IPF) in humans and therefore identify CIPF as a possible spontaneously arising model for study of human IPF. However, computed tomographic and histopathological findings of CIPF are not identical to those of human IPF. As in human IPF, the aetiology of CIPF is not yet fully elucidated. There are no curative treatments and the prognosis is poor. This paper reviews advances in understanding of the clinical description and natural history of CIPF, the investigation of biomarkers and the exploration of possible aetiologies and mechanistic hypotheses.

Unsupervised gene expression analyses identify IPF-severity correlated signatures, associated genes and biomarkers

Background

Idiopathic Pulmonary Fibrosis (IPF) is a fatal fibrotic lung disease occurring predominantly in middle-aged and older adults. The traditional diagnostic classification of IPF is based on clinical, radiological, and histopathological features. However, the considerable heterogeneity in IPF presentation suggests that differences in gene expression profiles can help to characterize and distinguish disease severity.

Methods

We used data-driven unsupervised clustering analysis, combined with a knowledge-based approach to identify and characterize IPF subgroups.

Results

Using transcriptional profiles on lung tissue from 131 patients with IPF/UIP and 12 non-diseased controls, we identified six subgroups of IPF that generally correlated with the disease severity and lung function decline. Network-informed clustering identified the most severe subgroup of IPF that was enriched with genes regulating inflammatory processes, blood pressure and branching morphogenesis of the lung. The differentially expressed genes in six subgroups of IPF compared to healthy control include transcripts of extracellular matrix, epithelial-mesenchymal cell cross-talk, calcium ion homeostasis, and oxygen transport. Further, we compiled differentially expressed gene signatures to identify unique gene clusters that can segregate IPF from normal, and severe from mild IPF. Additional validations of these signatures were carried out in three independent cohorts of IPF/UIP. Finally, using knowledge-based approaches, we identified several novel candidate genes which may also serve as potential biomarkers of IPF.

Conclusions

Discovery of unique and redundant gene signatures for subgroups in IPF can be greatly facilitated through unsupervised clustering. Findings derived from such gene signatures may provide insights into pathogenesis of IPF and facilitate the development of clinically useful biomarkers.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0472-9) contains supplementary material, which is available to authorized users.

Studying human respiratory disease in animals--role of induced and naturally occurring models

Respiratory disorders like asthma, emphysema, and pulmonary fibrosis affect millions of Americans and many more worldwide. Despite advancements in medical research that have led to improved understanding of the pathophysiology of these conditions and sometimes to new therapeutic interventions, these disorders are for the most part chronic and progressive; current interventions are not curative and do not halt disease progression. A major obstacle to further advancements relates to the absence of animal models that exactly resemble the human condition, which delays the elucidation of relevant mechanisms of action, the unveiling of biomarkers of disease progression, and identification of new targets for intervention in patients. There are currently many induced animal models of human respiratory disease available for study, and even though they mimic features of human disease, discoveries in these models have not always translated into safe and effective treatments in humans. A major obstacle relates to the genetic, anatomical, and functional variations amongst species, which represents the major challenge to overcome when searching for appropriate models of respiratory disease. Nevertheless, rodents, in particular mice, have become the most common species used for experimentation, due to their relatively low cost, size, and adequate understanding of murine genetics, among other advantages. Less well known is the fact that domestic animals also suffer from respiratory illnesses similar to those found in humans. Asthma, bronchitis, pneumonia, and pulmonary fibrosis are among the many disorders occurring naturally in dogs, cats, and horses, among other species. These models might better resemble the human condition and are emphasized here, but further investigations are needed to determine their relevance.

Immunoexpression of TGF-β/Smad and VEGF-A proteins in serum and BAL fluid of sarcoidosis patients

Background

The chronic course of pulmonary sarcoidosis can lead to lung dysfunction due to fibrosis, in which the signalling pathways TGF-β/Smad and VEGF-A may play a key role.

Methods

We evaluated immunoexpression of TGF-β₁, Smad2, 3, and 7, and VEGF-A in serum and bronchoalveolar lavage (BAL) fluid of patients (n = 57) classified according to the presence of lung parenchymal involvement (radiological stage I vs. II-III), acute vs. insidious onset, lung function test (LFT) results, calcium metabolism parameters, percentage of BAL lymphocytes (BAL-L%), BAL CD4⁺/CD8⁺ ratio, age, and gender. Immunoexpression analysis of proteins was performed by ELISA.

Results

The immunoexpression of all studied proteins were higher in serum than in BAL fluid of patients (p >0.05). The serum levels of TGF-β₁ (p = 0.03), Smad2 (p = 0.01), and VEGF-A (p = 0.0002) were significantly higher in sarcoidosis patients compared to healthy controls. There were no differences within the sarcoidosis group between patients with vs. without parenchymal involvement, acute vs. insidious onset, or patients with normal vs. abnormal spirometry results. In patients with abnormal spirometry results a negative correlation was found between forced vital capacity (FVC) % predicted value and TGF-β₁ immunoexpression in BAL fluid, and positive correlations were observed between the intensity of lung parenchymal changes estimated by high-resolution computed tomography (HRCT scores) and Smad 2 level in serum.

Conclusions

TGF-β/Smad signalling pathway and VEGF-A participate in the pathogenesis of sarcoidosis. BAL TGF-β₁, and Smad 2 in serum seem to be promising biomarkers with negative prognostic value, but further studies are required to confirmed our observations.

The potential role of IL-33/ST2 signaling in fibrotic diseases

IL-33, a new member of the IL-1F, is widely expressed throughout the body and can be up-regulated by stimulation with proinflammatory factors. It has been identified as a functional ligand for the plasma membrane receptor complex that is a heterodimer consisting of membrane-bound ST2L, which is a member of the IL-1R family, and IL-1RAcP. IL-33 is crucial for the induction of Th2 immune responses. Additionally, under other circumstances, it can also act as an endogenous danger signal. Recently, many studies have demonstrated that IL-33 may be related to the development and progression of fibrotic diseases. It has proinflammatory effects in some fibrotic diseases but has anti-inflammatory effects in others. In this review, the biologic characteristics of IL-33 and the role of the IL-33/ST2 signaling pathway in various fibrotic diseases will be discussed. We hope this overview will provide new insights for the treatment of these diseases.