Resveratrol attenuates inflammation and fibrosis in rheumatoid arthritis-associated interstitial lung disease via the AKT/TMEM175 pathway.

BACKGROUND AND PURPOSE: Interstitial lung disease (ILD) represents a significant complication of rheumatoid arthritis (RA) that lacks effective treatment options. This study aimed to investigate the intrinsic mechanism by which resveratrol attenuates rheumatoid arthritis complicated with interstitial lung disease through the AKT/TMEM175 pathway. METHODS: We established an arthritis model by combining chicken type II collagen and complete Freund's adjuvant. Resveratrol treatment was administered via tube feeding for 10 days. Pathological changes in both the joints and lungs were evaluated using HE and Masson staining techniques. Protein expression of TGF-ß1, AKT, and TMEM175 was examined in lung tissue. MRC-5 cells were stimulated using IL-1ß in combination with TGF-ß1 as an in vitro model of RA-ILD, and agonists of AKT, metabolic inhibitors, and SiRNA of TMEM175 were used to explore the regulation and mechanism of action of resveratrol RA-ILD. RESULTS: Resveratrol mitigates fibrosis in rheumatoid arthritis-associated interstitial lung disease and reduces oxidative stress and inflammation in RA-ILD. Furthermore, resveratrol restored cellular autophagy. When combined with the in vitro model, it was further demonstrated that resveratrol could suppress TGF-ß1 expression, and reduce AKT metamorphic activation, consequently inhibiting the opening of AKT/MEM175 ion channels. This, in turn, lowers lysosomal pH and enhances the fusion of autophagosomes with lysosomes, ultimately ameliorating the progression of RA-ILD. CONCLUSION: In this study, we demonstrated that resveratrol restores autophagic flux through the AKT/MEM175 pathway to attenuate inflammation as well as fibrosis in RA-ILD by combining in vivo and in vitro experiments. It further provides a theoretical basis for the selection of therapeutic targets for RA-ILD.

The Lung in Rheumatoid Arthritis-Friend or Enemy?

Rheumatoid arthritis (RA) is a chronic autoimmune condition frequently found in rheumatological patients that sometimes raises diagnosis and management problems. The pathogenesis of the disease is complex and involves the activation of many cells and intracellular signaling pathways, ultimately leading to the activation of the innate and acquired immune system and producing extensive tissue damage. Along with joint involvement, RA can have numerous extra-articular manifestations (EAMs), among which lung damage, especially interstitial lung disease (ILD), negatively influences the evolution and survival of these patients. Although there are more and more RA-ILD cases, the pathogenesis is incompletely understood. In terms of genetic predisposition, external environmental factors act and subsequently determine the activation of immune system cells such as macrophages, neutrophils, B and T lymphocytes, fibroblasts, and dendritic cells. These, in turn, show the ability to secrete molecules with a proinflammatory role (cytokines, chemokines, growth factors) that will produce important visceral injuries, including pulmonary changes. Currently, there is new evidence that supports the initiation of the systemic immune response at the level of pulmonary mucosa where the citrullination process occurs, whereby the autoantibodies subsequently migrate from the lung to the synovial membrane. The aim of this paper is to provide current data regarding the pathogenesis of RA-associated ILD, starting from environmental triggers and reaching the cellular, humoral, and molecular changes involved in the onset of the disease.

Levels of Lysozyme and SLPI in Bronchoalveolar Lavage: Exploring Their Role in Interstitial Lung Disease.

Interstitial lung diseases (ILDs) are characterized by inflammation or fibrosis of the pulmonary parenchyma. Despite the involvement of immune cells and soluble mediators in pulmonary fibrosis, the influence of antimicrobial peptides (AMPs) remains underexplored. These effector molecules display a range of activities, which include immunomodulation and wound repair. Here, we investigate the role of AMPs in the development of fibrosis in ILD. We compare the concentration of different AMPs and different cytokines in 46 fibrotic (F-ILD) and 17 non-fibrotic (NF-ILD) patients by ELISA and using peripheral blood mononuclear cells from in vitro stimulation in the presence of lysozyme or secretory leukocyte protease inhibitor (SLPI) from 10 healthy donors. We observed that bronchoalveolar lavage (BAL) levels of AMPs were decreased in F-ILD patients (lysozyme: p < 0.001; SLPI: p < 0.001; LL-37: p < 0.001; lactoferrin: p = 0.47) and were negatively correlated with levels of TGF-ß (lysozyme: p = 0.02; SLPI: p < 0.001) and IL-17 (lysozyme: p < 0.001; SLPI: p < 0.001). We observed that lysozyme increased the percentage of CD86+ macrophages (p < 0.001) and the production of TNF-α (p < 0.001). We showed that lysozyme and SLPI were associated with clinical parameters (lysozyme: p < 0.001; SLPI: p < 0.001) and disease progression (lysozyme: p < 0.001; SLPI: p = 0.01). These results suggest that AMPs may play an important role in the anti-fibrotic response, regulating the effect of pro-fibrotic cytokines. In addition, levels of lysozyme in BAL may be a potential biomarker to predict the progression in F-ILD patients.

[Tofacitinib inhibits the transformation of lung fibroblasts into myofibroblasts through JAK/STAT3 pathway].

OBJECTIVE: To investigate the effect of tofacitinib, a pan-Janus kinase (JAK) inhibitor, on transforming growth factor-beta 1 (TGF-ß1)-induced fibroblast to myofibroblast transition (FMT) and to explore its mechanism. To provide a theoretical basis for the clinical treatment of connective tissue disease-related interstitial lung disease (CTD-ILD). METHODS: (1) Human fetal lung fibroblast 1 (HFL-1) were cultured in vitro, and 6 groups were established: DMSO blank control group, TGF-ß1 induction group, and TGF-ß1 with different concentrations of tofacitinib (0.5, 1.0, 2.0, 5.0 µmol/L) drug intervention experimental groups. CCK-8 was used to measure the cell viability, and wound-healing assay was performed to measure cell migration ability. After 48 h of combined treatment, quantitative real-time PCR (RT-PCR) and Western blotting were used to detect the gene and protein expression levels of α-smooth muscle actin (α-SMA), fibronectin (FN), and collagen type Ⅰ (COL1). (2) RT-PCR and enzyme-linked immunosorbnent assay (ELISA) were used to detect the interleukin-6 (IL-6) gene and protein expression changes, respectively. (3) DMSO carrier controls, 1.0 µmol/L and 5.0 µmol/L tofacitinib were added to the cell culture media of different groups for pre-incubation for 30 min, and then TGF-ß1 was added to treat for 1 h, 6 h and 24 h. The phosphorylation levels of Smad2/3 and signal transducer and activator of transcription 3 (STAT3) protein were detected by Western blotting. RESULTS: (1) Tofacitinib inhibited the viability and migration ability of HFL-1 cells after TGF-ß1 induction. (2) The expression of α-SMA, COL1A1 and FN1 genes of HFL-1 in the TGF-ß1-induced groups was significantly up-regulated compared with the blank control group (P < 0.05). Compared with the TGF-ß1 induction group, α-SMA expression in the 5.0 µmol/L tofacitinib intervention group was significantly inhi-bited (P < 0.05). Compared with the TGF-ß1-induced group, FN1 gene was significantly inhibited in each intervention group at a concentration of 0.5-5.0 µmol/L (P < 0.05). Compared with the TGF-ß1-induced group, the COL1A1 gene expression in each intervention group did not change significantly. (3) Western blotting results showed that the protein levels of α-SMA and FN1 in the TGF-ß1-induced group were significantly higher than those in the control group (P < 0.05), and there was no significant difference in the expression of COL1A1. Compared with the TGF-ß1-induced group, the α-SMA protein level in the intervention groups with different concentrations decreased. And the differences between the TGF-ß1-induced group and 2.0 µmol/L or 5.0 µmol/L intervention groups were statistically significant (P < 0.05). Compared with the TGF-ß1-induced group, the FN1 protein levels in the intervention groups with different concentrations showed a downward trend, but the difference was not statistically significant. There was no difference in COL1A1 protein expression between the intervention groups compared with the TGF-ß1-induced group. (4) After TGF-ß1 acted on HFL-1 cells for 48 h, the gene expression of the IL-6 was up-regulated and IL-6 in culture supernatant was increased, the intervention with tofacitinib partly inhibited the TGF-ß1-induced IL-6 gene expression and IL-6 in culture supernatant. TGF-ß1 induced the increase of Smad2/3 protein phosphorylation in HFL-1 cells for 1 h and 6 h, STAT3 protein phosphorylation increased at 1 h, 6 h and 24 h, the pre-intervention with tofacitinib inhibited the TGF-ß1-induced Smad2/3 phosphorylation at 6 h and inhibited TGF-ß1-induced STAT3 phosphorylation at 1 h, 6 h and 24 h. CONCLUSION: Tofacitinib can inhibit the transformation of HFL-1 cells into myofibroblasts induced by TGF-ß1, and the mechanism may be through inhibiting the classic Smad2/3 pathway as well as the phosphorylation of STAT3 induced by TGF-ß1, thereby protecting the disease progression of pulmonary fibrosis.

MARCH8 downregulation modulates profibrotic responses including myofibroblast differentiation.

Interstitial lung diseases can result in poor patient outcomes, especially in idiopathic pulmonary fibrosis (IPF), a severe interstitial lung disease with unknown causes. The lack of treatment options requires further understanding of the pathological process/mediators. Membrane-associated RING-CH 8 (MARCH8) has been implicated in immune function regulation and inflammation, however, its role in the development of pulmonary fibrosis and particularly the fibroblast to myofibroblast transition (FMT) remains a gap in existing knowledge. In this study, we demonstrated decreased MARCH8 expression in patients with IPF compared with non-PF controls and in bleomycin-induced PF. TGF-ß dose- and time-dependently decreased MARCH8 expression in normal and IPF human lung fibroblast (HLFs), along with induction of FMT markers α-SMA, collagen type I (Col-1), and fibronectin (FN). Interestingly, overexpression of MARCH8 significantly suppressed TGF-ß-induced expression of α-SMA, Col-1, and FN. By contrast, the knockdown of MARCH8 using siRNA upregulated basal expression of α-SMA/Col-1/FN. Moreover, MARCH8 knockdown enhanced TGF-ß-induced FMT marker expression. These data clearly show that MARCH8 is a critical "brake" for FMT and potentially affects PF. We further found that TGF-ß suppressed MARCH8 mRNA expression and the proteasome inhibitor MG132 failed to block MARCH8 decrease induced by TGF-ß. Conversely, TGF-ß decreases mRNA levels of MARCH8 in a dose- and time-dependent manner, suggesting the transcriptional regulation of MARCH8 by TGF-ß. Mechanistically, MARCH8 overexpression suppressed TGF-ß-induced Smad2/3 phosphorylation, which may account for the observed effects. Taken together, this study demonstrated an unrecognized role of MARCH8 in negatively regulating FMT and profibrogenic responses relevant to interstitial lung diseases.NEW & NOTEWORTHY MARCH8 is an important modulator of inflammation, immunity, and other cellular processes. We found that MARCH8 expression is downregulated in the lungs of patients with idiopathic pulmonary fibrosis (IPF) and experimental models of pulmonary fibrosis. Furthermore, TGF-ß1 decreases MARCH8 transcriptionally in human lung fibroblasts (HLFs). MARCH8 overexpression blunts TGF-ß1-induced fibroblast to myofibroblast transition while knockdown of MARCH8 drives this profibrotic change in HLFs. The findings support further exploration of MARCH8 as a novel target in IPF.

Hypoxia-inducible factor 1α modulates interstitial pneumonia-mediated lung cancer progression.

BACKGROUND: The prognosis of patients with lung cancer accompanied by interstitial pneumonia is poorer than that of patients with lung cancer but without interstitial pneumonia. Moreover, the available therapeutic interventions for lung cancer patients with interstitial pneumonia are limited. Therefore, a new treatment strategy for these patients is required. The aim of the present study was to investigate the pathophysiological relationship between interstitial pneumonia and lung cancer and explore potential therapeutic agents. METHODS: A novel hybrid murine model of lung cancer with interstitial pneumonia was established via bleomycin-induced pulmonary fibrosis followed by orthotopic lung cancer cell transplantation into the lungs. Changes in tumor progression, lung fibrosis, RNA expression, cytokine levels, and tumor microenvironment in the lung cancer with interstitial pneumonia model were investigated, and therapeutic agents were examined. Additionally, clinical data and samples from patients with lung cancer accompanied by interstitial pneumonia were analyzed to explore the potential clinical significance of the findings. RESULTS: In the lung cancer with interstitial pneumonia model, accelerated tumor growth was observed based on an altered tumor microenvironment. RNA sequencing analysis revealed upregulation of the hypoxia-inducible factor 1 signaling pathway. These findings were consistent with those obtained for human samples. Moreover, we explored whether ascorbic acid could be an alternative treatment for lung cancer with interstitial pneumonia to avoid the disadvantages of hypoxia-inducible factor 1 inhibitors. Ascorbic acid successfully downregulated the hypoxia-inducible factor 1 signaling pathway and inhibited tumor progression and lung fibrosis. CONCLUSIONS: The hypoxia-inducible factor 1 pathway is critical in lung cancer with interstitial pneumonia and could be a therapeutic target for mitigating interstitial pneumonia-mediated lung cancer progression.

Tuftelin1 drives experimental pulmonary fibrosis progression by facilitating stress fiber assembly.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease (ILD) with unknown etiology, characterized by sustained damage repair of epithelial cells and abnormal activation of fibroblasts, the underlying mechanism of the disease remains elusive. METHODS: To evaluate the role of Tuftelin1 (TUFT1) in IPF and elucidate its molecular mechanism. We investigated the level of TUFT1 in the IPF and bleomycin-induced mouse models and explored the influence of TUFT1 deficiency on pulmonary fibrosis. Additionally, we explored the effect of TUFT1 on the cytoskeleton and illustrated the relationship between stress fiber and pulmonary fibrosis. RESULTS: Our results demonstrated a significant upregulation of TUFT1 in IPF and the bleomycin (BLM)-induced fibrosis model. Disruption of TUFT1 exerted inhibitory effects on pulmonary fibrosis in both in vivo and in vitro. TUFT1 facilitated the assembly of microfilaments in A549 and MRC-5 cells, with a pronounced association between TUFT1 and Neuronal Wiskott-Aldrich syndrome protein (N-WASP) observed during microfilament formation. TUFT1 can promote the phosphorylation of tyrosine residue 256 (Y256) of the N-WASP (pY256N-WASP). Furthermore, TUFT1 promoted transforming growth factor-ß1 (TGF-ß1) induced fibroblast activation by increasing nuclear translocation of pY256N-WASP in fibroblasts, while wiskostatin (Wis), an N-WASP inhibitor, suppressed these processes. CONCLUSIONS: Our findings suggested that TUFT1 plays a critical role in pulmonary fibrosis via its influence on stress fiber, and blockade of TUFT1 effectively reduces pro-fibrotic phenotypes. Pharmacological targeting of the TUFT1-N-WASP axis may represent a promising therapeutic approach for pulmonary fibrosis.

Bronchoalveolar cytokine profile differentiates Pulmonary Langerhans cell histiocytosis patients from other smoking-related interstitial lung diseases.

BACKGROUND: Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial lung disease (ILD) associated with smoking, whose definitive diagnosis requires the exclusion of other forms of ILD and a compatible surgical lung biopsy. Bronchoalveolar lavage (BAL) is commonly proposed for the diagnosis of ILD, including PLCH, but the diagnostic value of this technique is limited. Here, we have analyzed the levels of a panel of cytokines and chemokines in BAL from PLCH patients, in order to identify a distinct immune profile to discriminate PLCH from other smoking related-ILD (SR-ILD), and comparing the results with idiopathic pulmonary fibrosis (IPF) as another disease in which smoking is considered a risk factor. METHODS: BAL samples were collected from thirty-six patients with different ILD, including seven patients with PLCH, sixteen with SR-ILD and thirteen with IPF. Inflammatory profiles were analyzed using the Human Cytokine Membrane Antibody Array. Principal component analysis (PCA) was performed to reduce dimensionality and protein-protein interaction (PPI) network analysis using STRING 11.5 database were conducted. Finally, Random forest (RF) method was used to build a prediction model. RESULTS: We have found significant differences (p < 0.05) on thirty-two cytokines/chemokines when comparing BAL from PLCH patients with at least one of the other ILD. Four main groups of similarly regulated cytokines were established, identifying distinct sets of markers for each cluster. Exploratory analysis using PCA (principal component analysis) showed clustering and separation of patients, with the two first components capturing 69.69% of the total variance. Levels of TARC/CCL17, leptin, oncostatin M (OSM) and IP-10/CXCL10 were associated with lung function parameters, showing positive correlation with FVC. Finally, random forest (RF) algorithm demonstrates that PLCH patients can be differentiated from the other ILDs based solely on inflammatory profile (accuracy 96.25%). CONCLUSIONS: Our results show that patients with PLCH exhibit a distinct BAL immune profile to SR-ILD and IPF. PCA analysis and RF model identify a specific immune profile useful for discriminating PLCH.

Quantifying Functional Impairment of ABCA3 Variants Associated with Interstitial Lung Disease.

ATP-binding cassette subfamily A member 3 (ABCA3) is a lipid transporter within alveolar type II cells. Patients with bi-allelic variants in ABCA3 may suffer from a variable severity of interstitial lung disease. We characterized and quantified ABCA3 variants' overall lipid transport function by assessing the in vitro impairment of its intracellular trafficking and pumping activity. We expressed the results relative to the wild type, integrated the quantitative readouts from eight different assays and used newly generated data combined with previous results to correlate the variants' function and clinical phenotype. We differentiated normal (within 1 normalized standard deviation (nSD) of the wild-type mean), impaired (within 1 to 3 nSD) and defective (beyond 3 nSD) variants. The transport of phosphatidylcholine from the recycling pathway into ABCA3+ vesicles proved sensitive to the variants' dysfunction. The sum of the quantitated trafficking and pumping predicted a clinical outcome. More than an approximately 50% loss of function was associated with considerable morbidity and mortality. The in vitro quantification of ABCA3 function enables detailed variant characterization, substantially improves the phenotype prediction of genetic variants and possibly supports future treatment decisions.

Fibronectin-EDA accumulates via reduced ubiquitination downstream of Toll-like receptor 9 activation in SSc-ILD fibroblasts.

Accumulation of excessive extracellular matrix (ECM) components from lung fibroblasts is a feature of systemic sclerosis-associated interstitial lung disease (SSc-ILD), and there is increasing evidence that innate immune signaling pathways contribute to these processes. Toll-like receptors (TLRs) are innate immune sensors activated by danger signals derived from pathogens or host molecular patterns. Several damage-associated molecular pattern (DAMP) molecules are elevated in SSc-ILD plasma, including ligands that activate TLR9, an innate immune sensor recently implicated in driving profibrotic responses in fibroblasts. Fibronectin and the isoform fibronectin-extra domain A (FN-EDA) are prominent in pathological extracellular matrix accumulation, but mechanisms promoting FN-EDA accumulation are only partially understood. Here, we show that TLR9 activation increases FN-EDA accumulation in MRC5 and SSc-ILD fibroblasts, but that this effect is independent of changes in FN-EDA gene transcription. Rather, we describe a novel mechanism where TLR9 activation inhibits FN-EDA turnover via reduced FN-EDA ubiquitination. TLR9 ligand ODN2006 reduces ubiquitinated FN-EDA destined for lysosomal degradation, an effect abrogated with TLR9 knockdown or inhibition. Taken together, these results provide rationale for disrupting the TLR9 signaling axis or FN-EDA degradation pathways to reduce FN-EDA accumulation in SSc-ILD fibroblasts. More broadly, enhancing intracellular degradation of ECM components through TLR9 inhibition or enhanced ECM turnover could be a novel strategy to attenuate pathogenic ECM accumulation in SSc-ILD.

Antiviral proinflammatory phenotype of monocytes in anti-MDA5 antibody-associated interstitial lung disease.

OBJECTIVE: To evaluate upstream and downstream regulators leading to macrophage activation and subsequent cytokine storm in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-associated interstitial lung disease (ILD). METHODS: We conducted an integrated miRNA-mRNA association analysis using circulating monocytes from 3 patients with anti-MDA5-associated ILD and 3 healthy controls and identified disease pathways and a regulator effect network by Ingenuity Pathway Analysis (IPA). The expression of relevant genes and proteins was verified using an independent validation cohort, including 6 patients with anti-MDA5-associated ILD, 5 with anti-aminoacyl tRNA synthetase antibody-associated ILD, and 6 healthy controls. RESULTS: IPA identified 26 matched pairs of downregulated miRNA and upregulated mRNAs and revealed that canonical pathways mediated by type I IFN signalling and C-C motif ligand 2 (CCL2) were responsible for the pathogenic process (P < 0.05 for all pathways). The regulatory network model identified IFN-ß; Toll-like receptors 3, 7, and 9; and PU.1 as upstream regulators, while the downstream effect of this network converged at the inhibition of viral infection. mRNA and protein expression analysis using validation cohort showed a trend towards the increased expression of relevant molecules identified by IPA in patients with anti-MDA5-associated ILD compared with those with anti-aminoacyl tRNA synthetase antibody-associated ILD or healthy controls. The expression of all relevant genes in monocytes and serum levels of CCL2 and IFN-ß declined after treatment in survivors with anti-MDA5-associated ILD. CONCLUSION: An antiviral proinflammatory network orchestrated primarily by activated monocytes/macrophages might be responsible for cytokine storm in anti-MDA5-associated ILD.

The use of exhaled air analysis in discriminating interstitial lung diseases: a pilot study.

BACKGROUND: Fibrotic Interstitial lung diseases (ILD) are a heterogeneous group of chronic lung diseases characterized by diverse degrees of lung inflammation and remodeling. They include idiopathic ILD such as idiopathic pulmonary fibrosis (IPF), and ILD secondary to chronic inflammatory diseases such as connective tissue disease (CTD). Precise differential diagnosis of ILD is critical since anti-inflammatory and immunosuppressive drugs, which are beneficial in inflammatory ILD, are detrimental in IPF. However, differential diagnosis of ILD is still difficult and often requires an invasive lung biopsy. The primary aim of this study is to identify volatile organic compounds (VOCs) patterns in exhaled air to non-invasively discriminate IPF and CTD-ILD. As secondary aim, the association between the IPF and CTD-ILD discriminating VOC patterns and functional impairment is investigated. METHODS: Fifty-three IPF patients, 53 CTD-ILD patients and 51 controls donated exhaled air, which was analyzed for its VOC content using gas chromatograph- time of flight- mass spectrometry. RESULTS: By applying multivariate analysis, a discriminative profile of 34 VOCs was observed to discriminate between IPF patients and healthy controls whereas 11 VOCs were able to distinguish between CTD-ILD patients and healthy controls. The separation between IPF and CTD-ILD could be made using 16 discriminating VOCs, that also displayed a significant correlation with total lung capacity and the 6 min' walk distance. CONCLUSIONS: This study reports for the first time that specific VOC profiles can be found to differentiate IPF and CTD-ILD from both healthy controls and each other. Moreover, an ILD-specific VOC profile was strongly correlated with functional parameters. Future research applying larger cohorts of patients suffering from a larger variety of ILDs should confirm the potential use of breathomics to facilitate fast, non-invasive and proper differential diagnosis of specific ILDs in the future as first step towards personalized medicine for these complex diseases.

TNF-α and IL-10 Control CXCL13 Expression in Human Macrophages.

The chemokine CXCL13 controls the normal organization of secondary lymphoid tissues and the neogenesis of ectopic lymphoid structures in nonlymphoid organs, particularly the lungs. The progression and severity of idiopathic pulmonary fibrosis (IPF), a fatal and irreversible interstitial lung disease, is predicted by the circulating blood concentrations of CXCL13. Although CXCL13 is produced by pulmonary tissues, it has not been determined which cells are involved. This study examines CXCL13 production by lung tissue macrophages from patients with IPF and the signaling pathways controlling CXCL13 gene expression in human alveolar macrophages (AM) and monocyte-derived macrophages (MoDM). CXCL13 is found in CD68- and CD206-positive AM from patients with IPF, and the CXCL13 gene is induced in these macrophages and MoDM when they are stimulated with LPS. We found that TNF-α and IL-10 control optimal CXCL13 gene expression in MoDM and possibly in AM by activating the NF-κB and JAK/STAT pathways, respectively. We also found that blood TNF-α and CXCL13 concentrations are significantly correlated in patients with IPF, suggesting that TNF-α contributes to CXCL13 production in humans. In conclusion, the results of this study demonstrate that AM from patients with IPF produces CXCL13 and that the NF-κB and JAK/STAT pathways are required to induce the expression of this major chemokine.

Increased L-Selectin on Monocytes Is Linked to the Autoantibody Profile in Systemic Sclerosis.

Monocytes are known to be implicated in the pathogenesis of systemic sclerosis (SSc), as they exert prominent migratory, adhesive, and chemotactic properties. The aim of our study was to characterize the surface expression of adhesion/chemotactic molecules (CD62L, CD11b, CCR2, CCR5) on the SSc monocytes and determine correlations with the clinical presentation of SSc. We included 38 SSc patients and 36 healthy age-and sex-matched controls. Isolated monocytes, as well as in vitro serum-treated monocytes, were analyzed by flow cytometry; additionally, soluble CD62L was measured in serum. We found increased soluble CD62L in the SSc serum samples and increased CD62L on the surface of the SSc monocytes in the in the same set of patients. Among samples with determined SSc-specific autoantibodies, the surface CD62L was the lowest in patients positive for anti-PM/Scl autoantibodies and the highest in patients with anti-topoisomerase I autoantibodies (ATA). The treatment of isolated healthy monocytes with ATA-positive SSc serum resulted in increased surface CD62L expression. Moreover, surface CCR5 was reduced on the monocytes from SSc patients with interstitial lung disease but also, along with CCR2, negatively correlated with the use of analgesics/anti-inflammatory drugs and immunosuppressants. In conclusion, increased CD62L on SSc monocytes, particularly in ATA-positive patients, provides new insights into the pathogenesis of SSc and suggests CD62L as a potential therapeutic target.

Human MIKO-1, a Hybrid Protein That Regulates Macrophage Function, Suppresses Lung Fibrosis in a Mouse Model of Bleomycin-Induced Interstitial Lung Disease.

Although interstitial lung disease (ILD) is a life-threatening pathological condition that causes respiratory failure, the efficiency of current therapies is limited. This study aimed to investigate the effects of human MIKO-1 (hMIKO-1), a hybrid protein that suppresses the abnormal activation of macrophages, on murine macrophage function and its therapeutic effect in a mouse model of bleomycin-induced ILD (BLM-ILD). To this end, the phenotype of thioglycolate-induced murine peritoneal macrophages co-cultured with hMIKO-1 was examined. The mice were assigned to normal, BLM-alone, or BLM + hMIKO-1 groups, and hMIKO-1 (0.1 mg/mouse) was administered intraperitoneally from day 0 to 14. The mice were sacrificed on day 28, and their lungs were evaluated by histological examination, collagen content, and gene expression levels. hMIKO-1 suppressed the polarization of murine macrophages to M2 predominance in vitro. The fibrosis score of lung pathology and lung collagen content of the BLM + hMIKO-1 group were significantly lower than those in the BLM-alone group. The expression levels of TNF-α, IL-6, IL-1ß, F4/80, and TIMP-1 in the lungs of the BLM + hMIKO-1 group were significantly lower than those in the BLM-alone group. These findings indicate that hMIKO-1 reduces lung fibrosis and may be a future therapeutic candidate for ILD treatment.

Epigenetic Mechanisms in Parenchymal Lung Diseases: Bystanders or Therapeutic Targets?

Epigenetic responses due to environmental changes alter chromatin structure, which in turn modifies the phenotype, gene expression profile, and activity of each cell type that has a role in the pathophysiology of a disease. Pulmonary diseases are one of the major causes of death in the world, including lung cancer, idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), pulmonary hypertension (PH), lung tuberculosis, pulmonary embolism, and asthma. Several lines of evidence indicate that epigenetic modifications may be one of the main factors to explain the increasing incidence and prevalence of lung diseases including IPF and COPD. Interestingly, isolated fibroblasts and smooth muscle cells from patients with pulmonary diseases such as IPF and PH that were cultured ex vivo maintained the disease phenotype. The cells often show a hyper-proliferative, apoptosis-resistant phenotype with increased expression of extracellular matrix (ECM) and activated focal adhesions suggesting the presence of an epigenetically imprinted phenotype. Moreover, many abnormalities observed in molecular processes in IPF patients are shown to be epigenetically regulated, such as innate immunity, cellular senescence, and apoptotic cell death. DNA methylation, histone modification, and microRNA regulation constitute the most common epigenetic modification mechanisms.

Targeting Alveolar Repair in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease with limited therapeutic options. Current evidence suggests that IPF may be initiated by repeated epithelial injuries in the distal lung, which are followed by abnormal wound healing responses that occur because of intrinsic and extrinsic factors. Mechanisms contributing to chronic damage of the alveolar epithelium in IPF include dysregulated cellular processes such as apoptosis, senescence, abnormal activation of the developmental pathways, aging, and genetic mutations. Therefore, targeting the regenerative capacity of the lung epithelium is an attractive approach in the development of novel therapies for IPF. Endogenous lung regeneration is a complex process involving coordinated cross-talk among multiple cell types and reestablishment of a normal extracellular matrix environment. This review will describe the current knowledge of reparative epithelial progenitor cells in the alveolar region of the lung and discuss potential novel therapeutic approaches for IPF, focusing on endogenous alveolar repair.

FK506-Binding Protein 13 Expression Is Upregulated in Interstitial Lung Disease and Correlated with Clinical Severity. A Potentially Protective Role.

Pulmonary fibrosis is a progressive lung disease characterized by myofibroblast accumulation and excessive extracellular matrix deposition. We sought to investigate the role of FKBP13 (13-kD FK506-binding protein), an endoplasmic reticulum-resident molecular chaperone, in various forms of pulmonary fibrosis. We first characterized the gene and protein expression of FKBP13 in lung biopsy specimens from 24 patients with idiopathic pulmonary fibrosis and 17 control subjects. FKBP13 expression was found to be elevated in the fibrotic regions of idiopathic pulmonary fibrosis lung tissues and correlated with declining forced vital capacity and dyspnea severity. FKBP13 expression was also increased in lung biopsy specimens of patients with hypersensitivity pneumonitis, rheumatoid arthritis, and sarcoidosis-associated interstitial lung disease. We next evaluated the role of this protein using FKBP13-/- mice in a bleomycin model of pulmonary fibrosis. Animals were assessed for lung function and histopathology at different stages of lung injury including the inflammatory (Day 7), fibrotic (Day 21), and resolution (Day 50) phases. FKBP13-/- mice showed increased infiltration of inflammatory cells and cytokines at Day 7, increased lung elastance and fibrosis at Day 21, and impaired resolution of fibrosis at Day 50. These changes were associated with an increased number of cells that stained positive for TUNEL and cleaved caspase 3 in the FKBP13-/- lungs, indicating a heightened cellular sensitivity to bleomycin. Our findings suggest that FKBP13 is a potential biomarker for severity of interstitial lung diseases and that it has a biologically relevant role in protecting mice against bleomycin-induced injury, inflammation, and fibrosis.

IL-23 amplifies the epithelial-mesenchymal transition of mechanically conditioned alveolar epithelial cells in rheumatoid arthritis-associated interstitial lung disease through mTOR/S6 signaling.

Epithelial-mesenchymal transition (EMT) creates an environment facilitating fibrosis following alveolar epithelial cell injury. IL-23 has important roles in chronic autoimmune conditions like rheumatoid arthritis (RA), but its role in the interstitial lung disease that affects patients with RA is unclear. This study aimed to determine the profibrogenic role of IL-23 on somatic alveolar type I (ATI) epithelial cells. Primary ATI cells were isolated from rats and cultured on plastic dishes for 1-3 wk. After prolonged culture (≥14 days) on rigid culture dishes, primary ATI cells gradually acquired a mesenchymal phenotype, identified by decreased expression of caveolin-1, and reorganization of F-actin cytoskeleton, indicating the initiation of EMT by matrix stiffness. To determine how IL-23 promotes EMT in vitro, transitioning ATI cells, cultured on a stiff substrate for ≥14 days were stimulated with IL-23. The EMT phenotype was significantly enhanced by IL-23, which upregulated α-smooth muscle actin (α-SMA), collagen I/III protein, and decreased caveolin-1. Furthermore, IL-23 significantly promoted cell invasion, as well as apoptotic resistance on transitioning ATI cells. Mechanistically, IL-23-induced EMT was mammalian target of rapamycin/ribosomal protein S6 (mTOR/S6) signaling dependent and reversible by rapamycin. Transcriptional sequencing analysis of human lung fibrosis biopsy tissue revealed key roles for IL-23 in rheumatoid arthritis-associated interstitial lung disease (RA-ILD). This result was further validated by significantly upregulated IL-23 expression at the mRNA level in RA-ILD lung sections. Notably, transitioning ATI epithelial cells were abundantly detected in RA-ILD tissue. Taken together, these data support a role for IL-23 in the pathogenesis of RA lung fibrosis by promoting EMT in alveolar epithelial cells through mTOR/S6 signaling.

Cytokeratin 19 fragment is associated with severity and poor prognosis of interstitial lung disease in anti-MDA5 antibody-positive dermatomyositis.

OBJECTIVES: In the present study, we aimed to assess the clinical significance of cytokeratin 19 fragment (CYFRA21-1) in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive DM-interstitial lung disease (MDA5-DM-ILD). METHODS: A total of 73 MDA5-DM-ILD patients were retrospectively analysed in this work. Their clinical characteristics, including clinical manifestations, laboratory findings, peripheral blood lymphocyte subsets and lung function, were compared between patients with acute/subacute interstitial pneumonia (A/SIP) and chronic interstitial pneumonia (CIP). The level of serum CYFRA21-1 was also compared between the above-mentioned two groups of patients, and its association with the clinical features and mortality of MDA5-DM-ILD was also evaluated. RESULTS: Of the 73 MDA5-DM-ILD patients, 26 patients exhibited the A/SIP pattern. The level of serum CYFRA21-1 was higher in MDA5-DM patients with A/SIP compared with the CIP group (P = 0.009). Lower oxygenation index (OI), CD3+CD4+ T cell counts and percentage of CD3+CD4+ cells were also observed in MDA5-DM patients with A/SIP compared with the CIP group. Higher serum CYFRA21-1, lower OI, and lower zone consolidation were associated with a higher risk of A/SIP in MDA5-DM-ILD. In addition, 38 decedents with MDA5-DM-ILD exhibited a greater level of CYFRA21-1 compared with 35 survivors (P < 0.001). Furthermore, it was a prognostic factor and also associated with a higher mortality rate (log-rank test, P < 0.001). CONCLUSIONS: CYFRA21-1 could be a useful serum indicator associated with occurrence of A/SIP in MDA5-DM-ILD. Moreover, it was associated with a poor survival in MDA5-DM-ILD patients.