Treatment of idiopathic pulmonary fibrosis and progressive pulmonary fibrosis: A position statement from the Thoracic Society of Australia and New Zealand 2023 revision

SULF1 expression is increased and promotes fibrosis through the TGF-β1/SMAD pathway in idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial lung disease of unknown etiology. Despite the increasing global incidence and poor prognosis, the exact pathogenic mechanisms remain elusive. Currently, effective therapeutic targets and treatment methods for this disease are still lacking. This study tried to explore the pathogenic mechanisms of IPF. We found elevated expression of SULF1 in lung tissues of IPF patients compared to normal control lung tissues. SULF1 is an enzyme that modifies heparan sulfate chains of heparan sulfate proteoglycans, playing a critical role in biological regulation. However, the effect of SULF1 in pulmonary fibrosis remains incompletely understood. Our study aimed to investigate the impact and mechanisms of SULF1 in fibrosis.

METHODS

We collected lung specimens from IPF patients for transcriptome sequencing. Validation of SULF1 expression in IPF patients was performed using Western blotting and RT-qPCR on lung tissues. ELISA experiments were employed to detect SULF1 concentrations in IPF patient plasma and TGF-β1 levels in cell culture supernatants. We used lentiviral delivery of SULF1 shRNA to knock down SULF1 in HFL1 cells, evaluating its effects on fibroblast secretion, activation, proliferation, migration, and invasion capabilities. Furthermore, we employed Co-Immunoprecipitation (Co-IP) to investigate the regulatory mechanisms involved.

RESULTS

Through bioinformatic analysis of IPF transcriptomic sequencing data (HTIPF) and datasets GSE24206, and GSE53845, we identified SULF1 may potentially play a crucial role in IPF. Subsequently, we verified that SULF1 was upregulated in IPF and predominantly increased in fibroblasts. Furthermore, SULF1 expression was induced in HFL1 cells following exposure to TGF-β1. Knockdown of SULF1 suppressed fibroblast secretion, activation, proliferation, migration, and invasion under both TGF-β1-driven and non-TGF-β1-driven conditions. We found that SULF1 catalyzes the release of TGF-β1 bound to TGFβRIII, thereby activating the TGF-β1/SMAD pathway to promote fibrosis. Additionally, TGF-β1 induces SULF1 expression through the TGF-β1/SMAD pathway, suggesting a potential positive feedback loop between SULF1 and the TGF-β1/SMAD pathway.

CONCLUSIONS

Our findings reveal that SULF1 promotes fibrosis through the TGF-β1/SMAD pathway in pulmonary fibrosis. Targeting SULF1 may offer a promising therapeutic strategy against IPF.

Pulmonary rehabilitation in idiopathic pulmonary fibrosis

PURPOSE OF REVIEW

This review synthesizes the expanding evidence for pulmonary rehabilitation that has led to its recommended inclusion in the holistic care of people with idiopathic pulmonary fibrosis (IPF), as well as discussing strategies that may maximize and sustain benefits.

RECENT FINDINGS

Pulmonary rehabilitation is an effective intervention leading to significant improvements in exercise tolerance, symptoms, and quality of life for people with IPF. Improvements in symptoms and quality of life can persist longer term, whereas functional capacity does not; therefore, strategies to preserve functional capacity are an important area of research. Referral early in the disease course is encouraged to promote longer lasting effects. Evidence that high-intensity interval training may optimize benefits of exercise training is emerging. Supplemental oxygen is frequently used to manage exercise-induced desaturation, although its use as an adjunct therapy requires more evidence.

SUMMARY

Current evidence strongly supports the inclusion of pulmonary rehabilitation in the standard holistic care of IPF, with early participation encouraged. Further research is needed to establish the optimal exercise strategies, modalities and adjunct therapies that enhance outcomes of pulmonary rehabilitation and promote longer lasting effects.

Forsythoside A regulates pulmonary fibrosis by inhibiting endothelial-to-mesenchymal transition and lung fibroblast proliferation via the PTPRB signaling

BACKGROUND

Pulmonary fibrosis (PF) is an end-stage change in many interstitial lung diseases, whereas no proven effective anti-pulmonary fibrotic treatments. Forsythoside A (FA) derived from Forsythia suspensa (Thunb.) Vahl, has been found to possess lung-protective effect. However, studies on its anti-pulmonary fibrosis effect are limited and its mechanism of action remains unknown.

PURPOSE

This study aimed to explore the underlying mechanism of FA on PF.

METHODS

Male C57BL/6 mice were randomized into normal (CON), model (BLM), pirfenidone (PFD), low- and high-dose FA (FA-L, FA-H, respectively). Except for the CON group, which was injected with the same dose of saline, the model of PF was established by intratracheal instillation of BLM, during which the survival rate and body weight changes of the mice were measured. The lung histopathology was evaluated by Hematoxylin-eosin, Sirius red, and Masson staining. Transcriptome analysis was performed to screen for the differential genes associated with the role of FA in PF. Differential genes in normal and pulmonary fibrosis patients with the GSE2052 dataset were analyzed in the GEO database. The levels of CTGF, α-SMA, MMP-8 in lung and TNF-α in bronchoalveolar lavage fluid (BALF) were detected by ELISA. The levels of HYP in lungs were detected by digestion. The mRNA and protein levels of MMP-7, E-cadherin, CD31, α-SMA, TGF-β1, IL-6, β-catenin, ZO-1, PTPRB, E-cadherin, and vimentin in lungs were detected by RT-qPCR and Western blot. The expression of CD31, α-SMA, TGF-β1 and ZO-1 were detected by immunofluorescence. TGF-β1-stimulated HFL1 cells and human umbilical vein endothelial cells (HUVECs) were used in an attempt to explore the possible role of protein tyrosine phosphatase receptor type B (PTPRB) involved in FA-induced improvement of PF.

RESULTS

The results showed that FA could improve the survival rate and body weight of PF mice. FA could alleviate the symptoms of alveolar wall thickening, inflammatory cell infiltration, blue collagen fiber deposition, collagen fiber type Ⅰ and type Ⅲ in mice with PF. In addition, FA could reduce the levels of HYP, CTGF, α-SMA, TGF-β1, TNF-α, β-catenin and MMP8, and regulate the expression levels of CD31, ZO-1, PTPRB and E-cadherin in lung of mice with PF, inhibiting endothelial-to-mesenchymal transition (EndMT) and fibroblasts proliferation. In the GSE2052 dataset, the expression level of PTPRB is reduced in lung tissue from PF patients, and results from transcriptome sequencing indicate that PTPRB expression is also reduced in PF mice. In addition, the effect of FA on TGF-β1-induced HFL1 or HUVECs cells could be attenuated by the inhibitor of PTPRB, suggesting that the effect of FA on PF is related to PTPRB.

CONCLUSION

This study demonstrated that FA could ameliorate PF by inhibiting lung fibroblast proliferation and EndMT, and that PTPRB might be a target of FA to ameliorate PF, which provided evidence to support FA as a candidate phytochemical for PF.

Reply to: Optimal clinical practice in IPF and PPF: Integrating scientific ethos and clinical reasoning

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Optimal clinical practice in IPF and PPF: Integrating the scientific ethos and clinical reasoning

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The role and regulation of SIRT1 in pulmonary fibrosis

Pulmonary fibrosis (PF) is a progressive and fatal lung disease with high incidence and a lack of effective treatment, which is a severe public health problem. PF has caused a huge socio-economic burden, and its pathogenesis has become a research hotspot. SIRT1 is a nicotinamide adenosine dinucleotide (NAD)-dependent sirtuin essential in tumours, Epithelial mesenchymal transition (EMT), and anti-aging. Numerous studies have demonstrated after extensive research that it is crucial in preventing the progression of pulmonary fibrosis. This article reviews the biological roles and mechanisms of SIRT1 in regulating the progression of pulmonary fibrosis in terms of EMT, oxidative stress, inflammation, aging, autophagy, and discusses the potential of SIRT1 as a therapeutic target for pulmonary fibrosis, and provides a new perspective on therapeutic drugs and prognosis prospects.