Immune Mechanisms and Related Targets for the Treatment of Fibrosis in Various Organs

Inflammation and fibrosis are two inter‐related disease pathologies with several overlapping components. Three specific cell types, macrophages, T helper cells and myofibroblasts, each play important roles in regulating both processes. Following tissue injury, an inflammatory stimulus is often necessary to initiate tissue repair, where cytokines released from infiltrating and resident immune and inflammatory cells stimulate the proliferation and activation of extracellular matrix-producing myofibroblasts. However, persistent tissue injury drives an inappropriate pro‐fibrotic response. Additionally, activated myofibroblasts can take on the role of traditional antigen-presenting cells, secrete pro‐inflammatory cytokines, and recruit inflammatory cells to fibrotic foci, amplifying the fibrotic response in a vicious cycle. Moreover, inflammatory cells have been shown to play contradictory roles in the initiation, amplification and resolution of fibrotic disease processes. The central role of the inflammasome molecular platform in contributing to fibrosis is only beginning to be fully appreciated. In this review, we discuss the immune mechanisms that can lead to fibrosis, the inflammasomes that have been implicated in the fibrotic process in the context of the immune response to injury, and also discuss current and emerging therapies that target inflammasome-induced collagen deposition to treat organ fibrosis.

Enhanced Liver Fibrosis Score as a Biomarker for Vascular Damage Assessment in Patients with Takayasu Arteritis—A Pilot Study

Takayasu arteritis (TA) is characterized by granulomatous panarteritis, vessel wall fibrosis, and irreversible vascular impairment. The aim of this study is to explore the usefulness of the Enhanced Liver Fibrosis score (ELF), procollagen-III aminoterminal propeptide (PIIINP), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), and hyaluronic acid (HA) in assessing vascular damage in TA patients. ELF, PIIINP, TIMP-1, and HA were measured in 24 TA patients, and the results were correlated with the clinical damage indexes (VDI and TADS), an imaging damage score (CARDS), and disease activity scores (NIH and ITAS2010). A mean ELF score 8.42 (±1.12) and values higher than 7.7 (cut-off for liver fibrosis) in 21/24 (87.5%) of patients were detected. The VDI and TADS correlated significantly to ELF (p < 0.01). Additionally, a strong association across ELF and CARDS (p < 0.0001), PIIINP and CARDS (p < 0.001), and HA and CARDS (p < 0.001) was observed. No correlations of the tested biomarkers with inflammatory parameters, NIH, and ITAS2010 scores were found. To our knowledge, this is the first study that suggests the association of the serum biomarkers PIIINP, HA, and ELF score with damage but not with disease activity in TA patients. The ELF score and PIIINP may be useful biomarkers reflecting an ongoing fibrotic process and quantifying vascular damage.

The Extracellular Matrix Enriched With Exosomes for the Treatment on Pulmonary Fibrosis in Mice

Pulmonary fibrosis (PF) is a severe respiratory disease caused by lung microenvironment changes. TGF-β/Smad3 signaling pathway plays a critical role in the fibrotic process. MicroRNA-29 (miR-29) has proved to alleviate the occurrence of PF by downregulating TGF-β/Smad3 signaling pathway. The miRNA application encounters obstacles due to its low stability in body and no targeting to lesions. Exosomes can be used for therapeutic delivery of miRNA due to their favorable delivery properties. However, low efficiency of separation and production impedes the therapeutic application of exosomes. In this study, we developed a liquid natural extracellular matrix (ECM) enriched with miR-29-loaded exosomes for PF treatment. The collagen-binding domain (CBD)-fused Lamp2b (CBD-Lamp2b) and miR-29 were overexpressed in human foreskin fibroblast (HFF) host cells for the entrapment of miR-29-loaded exosomes in ECM of the cells. The repeated freeze-thaw method was performed to prepare the liquid ECM enriched with exosomes without destroying the exosomal membrane. In summary, this study developed a novel functional ECM biomaterial for therapy of PF, and also provided a promising gene therapy platform for different diseases by treatment with liquid ECM that is, enriched with exosomes loaded with different functional miRNAs.

The Normal and Fibrotic Mouse Lung in Situ Classified by High Dimensional Single Cell Analysis on Routinely Processed Tissue

Single cell classification is elucidating homeostasis and pathology in tissues and whole organs. We applied in situ spatial proteomics by multiplex antibody staining to routinely processed mouse lung, healthy and during a fibrosis model. With a limited validated antibody panel (24) we classify the normal constituents (alveolar type I and II, bronchial epithelia, endothelial, muscular, stromal and hematopoietic cells) and by quantitative measurements, we show the progress of lung fibrosis over a 4 weeks course, the changing landscape and the cell-specific quantitative variation of a multidrug transporter. An early decline in AT2 alveolar cells and a progressive increase in stromal cells seems at the core of the fibrotic process.

Is the Macrophage Phenotype Determinant for Fibrosis Development?

Fibrosis is a pathophysiological process of wound repair that leads to the deposit of connective tissue in the extracellular matrix. This complication is mainly associated with different pathologies affecting several organs such as lung, liver, heart, kidney, and intestine. In this fibrotic process, macrophages play an important role since they can modulate fibrosis due to their high plasticity, being able to adopt different phenotypes depending on the microenvironment in which they are found. In this review, we will try to discuss whether the macrophage phenotype exerts a pivotal role in the fibrosis development in the most important fibrotic scenarios.

Improving the Algorithm for the Management of Patients with Viral Hepatitis Using Contrast-Free Hepatic Arterial Spin Labelling Magnetic Resonance Perfusion

Objective: improving the algorithm for the management of patients with viral hepatitis using contrast-free arterial spin labelling (ASL) magnetic resonance (MR) perfusion.Material and methods. A total of 116 patients with viral hepatitis (VH) B, C and B + C were examined on the basis of Clinical hospital No. 1 (Smolensk): 75 (64.7%) men and 41 (35.3%) women, mean age 49.7 ± 2.3 years. The patients underwent instrumental diagnostic methods: ultrasound, clinical elastography, contrast-free hepatic ASL MR perfusion. Liver biopsy (n = 57) was used as the reference method.Results. The results of ASL MR perfusion had a high correlation with the data of clinical elastography in the diagnosis of fibrotic process; the diagnostic and prognostic significance of ASL liver perfusion in the diagnosis of fibrotic process was: AUROC 0.943 (95% CI, 0.884–0.953). There was a high correlation between ASL MR perfusion with Doppler ultrasound of hepatic blood vessels in the diagnosis of arterial blood flow disorders, but in VH В + C and cirrhosis – diagnostic and prognostic significance of the method: AUROC 0.951 (95% CI 0.932–0.972).Conclusion. ASL MR perfusion in VH patients allows to predict fibrotic changes in the hepatic parenchyma (AUROC 0.934 (95% CI 0.845–0.957)), provides information about changes in blood flow in the parenchymal structure (p < 0.005). The algorithm for the examination of VH patients should include contrast-free ASL MR perfusion at admission (AUROC 0.865 (95% CI 0.843–0.928)) and in dynamic follow-up (AUROC 0.915 (95% CI 0.881–0.946)).

Telomere Dysfunction in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is an age-dependent progressive and fatal lung disease of unknown etiology, which is characterized by the excessive accumulation of extracellular matrix inside the interstitial layer of the lung parenchyma that leads to abnormal scar architecture and compromised lung function capacity. Recent genetic studies have attributed the pathological genes or genetic mutations associated with familial idiopathic pulmonary fibrosis (IPF) and sporadic IPF to telomere-related components, suggesting that telomere dysfunction is an important determinant of this disease. In this study, we summarized recent advances in our understanding of how telomere dysfunction drives IPF genesis. We highlighted the key role of alveolar stem cell dysfunction caused by telomere shortening or telomere uncapping, which bridged the gap between telomere abnormalities and fibrotic lung pathology. We emphasized that senescence-associated secretory phenotypes, innate immune cell infiltration, and/or inflammation downstream of lung stem cell dysfunction influenced the native microenvironment and local cell signals, including increased transforming growth factor-beta (TGF-β) signaling in the lung, to induce pro-fibrotic conditions. In addition, the failed regeneration of new alveoli due to alveolar stem cell dysfunction might expose lung cells to elevated mechanical tension, which could activate the TGF-β signaling loop to promote the fibrotic process, especially in a periphery-to-center pattern as seen in IPF patients. Understanding the telomere-related molecular and pathophysiological mechanisms of IPF would provide new insights into IPF etiology and therapeutic strategies for this fatal disease.

Mineralocorticoid Receptor Antagonists in Diabetic Kidney Disease

Diabetic kidney disease (DKD) is a major cause of end-stage kidney disease (ESKD) worldwide. Mineralocorticoid receptor (MR) plays an important role in the development of DKD. A series of preclinical studies revealed that MR is overactivated under diabetic conditions, resulting in promoting inflammatory and fibrotic process in the kidney. Clinical studies demonstrated the usefulness of MR antagonists (MRAs), such as spironolactone and eplerenone, on DKD. However, concerns regarding their selectivity for MR and hyperkalemia have remained for these steroidal MRAs. Recently, nonsteroidal MRAs, including finerenone, have been developed. These agents are highly selective and have potent anti-inflammatory and anti-fibrotic properties with a low risk of hyperkalemia. We herein review the current knowledge and future perspectives of MRAs in DKD treatment.

Oxidative Stress Induced by Reactive Oxygen Species (ROS) and NADPH Oxidase 4 (NOX4) in the Pathogenesis of the Fibrotic Process in Systemic Sclerosis: A Promising Therapeutic Target

Numerous clinical and research investigations conducted during the last two decades have implicated excessive oxidative stress caused by high levels of reactive oxygen species (ROS) in the development of the severe and frequently progressive fibrotic process in Systemic Sclerosis (SSc). The role of excessive oxidative stress in SSc pathogenesis has been supported by the demonstration of increased levels of numerous biomarkers, indicative of cellular and molecular oxidative damage in serum, plasma, and other biological fluids from SSc patients, and by the demonstration of elevated production of ROS by various cell types involved in the SSc fibrotic process. However, the precise mechanisms mediating oxidative stress development in SSc and its pathogenetic effects have not been fully elucidated. The participation of the NADPH oxidase NOX4, has been suggested and experimentally supported by the demonstration that SSc dermal fibroblasts display constitutively increased NOX4 expression and that reduction or abrogation of NOX4 effects decreased ROS production and the expression of genes encoding fibrotic proteins. Furthermore, NOX4-stimulated ROS production may be involved in the development of certain endothelial and vascular abnormalities and may even participate in the generation of SSc-specific autoantibodies. Collectively, these observations suggest NOX4 as a novel therapeutic target for SSc.