The role of endothelin and RAS/ERK signaling in immunopathogenesis-related fibrosis in patients with systemic sclerosis: an updated review with therapeutic implications

Fibrosis mechanisms in systemic sclerosis and new potential therapies

Systemic sclerosis is a rare rheumatic disease characterized by immune cell activation, tissue fibrosis, and endothelial dysfunction. Extracellular matrix synthesis disorder causes widespread fibrosis, primarily in skin and internal organs. Various factors such as TGFβ, VEGF, Galectin-3, and signaling pathways like Wnt/β-catenin are involved in pathophysiological processes. Treatment lacks a unified approach but combines diverse modalities tailored to disease subtype and progression. Current therapeutic strategies include biologics, JAK inhibitors, and IL-6 pathway modulators. Monoclonal antibodies and hypomethylating agents demonstrate potential in fibrosis inhibition. This review focuses on emerging therapeutic evidence regarding drugs targeting collagen, cytokines, and cell surface molecules in systemic sclerosis, aiming to provide insight into potential innovative treatment strategies.

Salirasib Inhibits the Expression of Genes Involved in Fibrosis in Fibroblasts of Systemic Sclerosis Patients

BACKGROUND

Fibrosis is a principal sign of systemic sclerosis (SSc) which can affect several organs including the lung, heart, and dermis. Dermal fibroblasts of SSc patients are characterized by persistent and activated Ras and ERK1/2 signaling which stimulates extreme collagen and extracellular matrix synthesis. Salirasib is a Ras inhibitor that competitively prevents the adherence of GTP-bound Ras to the plasma membrane, that inhibits Ras signaling. This study intended to clarify whether salirasib can influence fibrotic mediators in SSc fibroblasts.

MATERIALS AND METHODS

Dermal fibroblasts from 10 SSc patients were treated with salirasib in the presence of TGF-β1, and mRNA levels of H-Ras and genes related to fibrosis, such as COL1A1, COL1A2, CTGF, TGF-β1, fibronectin, ACTA2, and MMP1 was measured by real-time PCR. The α-SMA protein expression was analyzed by immunofluorescence staining.

RESULTS

In dermal fibroblasts of SSc patients, salirasib treatment, markedly downregulated the H-Ras gene expression. In addition, the protein expression of α-SMA and gene expression of ACTA2 were inhibited upon salirasib treatment. Salirasib also significantly reduced the expression of COL1A1, and COL1A2 genes and augmented the gene expression of MMP1. The mRNA levels of other genes related to fibrosis such as FN1, CTGF, and TGF-β1 were significantly decreased upon salirasib treatment.

CONCLUSION

Considering salirasib significantly reduced the expression of genes related to the fibrosis process and α-SMA gene and protein expression, and given significant upregulation of MMP1 by salirasib, it can be considered as a new curative strategy for fibrotic diseases like SSc.

LC-Orbitrap HRMS-Based Proteomics Reveals Novel Mitochondrial Dynamics Regulatory Proteins Associated with RasV12-Induced Glioblastoma (GBM) of Drosophila

Glioblastoma multiforme (GBM) is the most prevalent and aggressive brain tumor found in adult humans with a poor prognosis and average survival of 14-15 months. In order to have a comprehensive understanding of proteome and identify novel therapeutic targets, this study focused mainly on the differentially abundant proteins (DAPs) of RasV12-induced GBM. RasV12 is a constitutively active Ras mutant form essential for tumor progression by continuously activating signaling pathways leading to uncontrolled tumor growth. This study used a transgenic Drosophila model with RasV12 overexpression using the repo-GAL4 driver line, specifically in glial cells, to study GBM. The high-resolution mass spectrometry (HRMS)-based proteomic analysis of the GBM larval central nervous system identified three novel DAPs specific to mitochondria. These DAPs, probable maleylacetoacetate isomerase 2 (Q9VHD2), bifunctional methylene tetrahydrofolate dehydrogenase (Q04448), and glutamine synthetase1 (P20477), identified through HRMS were further validated by qRT-PCR. The protein-protein interaction analysis revealed interactions between RasV12 and DAPs, with functional links to mitochondrial dynamics regulators such as Drp1, Marf, Parkin, and HtrA2. Notably, altered expressions of Q9VHD2, P20477, and Q04448 were observed during GBM progression, which offers new insights into the involvement of mitochondrial dynamic regulators in RasV12-induced GBM pathophysiology.

Biomarkers reflecting the pathogenesis, clinical manifestations, and guide therapeutic approach in systemic sclerosis: a narrative review

Systemic sclerosis (SSc) is a progressive autoimmune disorder that mainly affects the skin. There are other clinical manifestations as renal, pulmonary, cardiovascular, and gastrointestinal tract involvements. Based on the skin involvement there are two subtypes of SSc, as limited cutaneous SSc (lSSc) which involves the acral part of the body and diffuse cutaneous SSc (dSSc) resulting in significant skin thickening of the body. Despite of the extensive research the pathomechanism is not fully clarified, how Ssc develops, moreover identifying biomarkers to predict the clinical outcome and prognosis still remains challenging. Circulating biomarkers can be crucial to define the diagnosis, to predict the prognosis and monitor the clinical course. However, only some patients are responsive to the therapy in SSc, and there is a need to reach the ideal therapy for any individual to prevent or slow down the progression in early stages of the disease. In this narrative review, our purpose was to summarize the potential biomarkers in Ssc, describe their role in the diagnosis, pathomechanism, clinical course, organ manifestations, as well as the response to the therapy. Biomarkers assessment aids in the evaluation of disease progression, and disease outcome.

Systemic Sclerosis-Associated Pulmonary Arterial Hypertension: From Bedside to Bench and Back Again

Systemic sclerosis (SSc) is a heterogeneous disease characterized by autoimmunity, vasculopathy, and fibrosis which affects the skin and internal organs. One key aspect of SSc vasculopathy is pulmonary arterial hypertension (SSc-PAH) which represents a leading cause of morbidity and mortality in patients with SSc. The pathogenesis of pulmonary hypertension is complex, with multiple vascular cell types, inflammation, and intracellular signaling pathways contributing to vascular pathology and remodeling. In this review, we focus on shared molecular features of pulmonary hypertension and those which make SSc-PAH a unique entity. We highlight advances in the understanding of the clinical and translational science pertinent to this disease. We first review clinical presentations and phenotypes, pathology, and novel biomarkers, and then highlight relevant animal models, key cellular and molecular pathways in pathogenesis, and explore emerging treatment strategies in SSc-PAH.

LATS2 degradation promoted fibrosis damage and rescued by vitamin K3 in lupus nephritis

BACKGROUND

Lupus nephritis (LN) is the most common complication of systemic lupus erythematosus (SLE). The limited treatment options for LN increase the economic burdens on patients. Because fibrotic progression leads to irreversible renal damage in LN patients and further progresses to chronic kidney disease (CKD) and the end stage of renal disease (ESRD), developing new targets to prevent LN fibrotic progression could lead to a feasible treatment strategy for LN patients.

METHODS

In this study, we examined YAP activation and LATS2 downregulation in LN kidney biopsy samples (LN: n = 8, normal: n = 2) and lupus-prone MRL/lpr mice (n = 8 for each disease stage). The function of LATS2 was further investigated by in situ injection of Ad-LATS2 into mice with LN (n = 6 mice per group). We examined the role of SIAH2-LATS2 regulation by IP-MS and co-IP, and the protective effect of the SIAH2 inhibitor was investigated in mice with LN.

RESULTS

Restoring LATS2 by an adenovirus in vivo alleviated renal fibrotic damage in mice with LN. Moreover, we found that LATS2 was degraded by a K48 ubiquitination-proteasome pathway mediated by SIAH2 and promoted YAP activation to worsen fibrosis progression in LN. The H150 region of the substrate binding domain (SBD) is an important site for SIAH2-LATS2 binding. The SIAH2-specific inhibitor vitamin K3 protected against LN-associated fibrotic damage in vivo.

CONCLUSION

In summary, we identified the SIAH2-LATS2 axis as an attractive intervention target in LN to alter the resistance to fibrosis.

The extracellular matrix glycoprotein fibrillin-1 in health and disease

Fibrillin-1 (FBN1) is a large, cysteine-rich, calcium binding extracellular matrix glycoprotein encoded by FBN1 gene. It serves as a structural component of microfibrils and provides force-bearing mechanical support in elastic and nonelastic connective tissue. As such, mutations in the FBN1 gene can cause a wide variety of genetic diseases such as Marfan syndrome, an autosomal dominant disorder characterized by ocular, skeletal and cardiovascular abnormalities. FBN1 also interacts with numerous microfibril-associated proteins, growth factors and cell membrane receptors, thereby mediating a wide range of biological processes such as cell survival, proliferation, migration and differentiation. Dysregulation of FBN1 is involved in the pathogenesis of many human diseases, such as cancers, cardiovascular disorders and kidney diseases. Paradoxically, both depletion and overexpression of FBN1 upregulate the bioavailability and signal transduction of TGF-β via distinct mechanisms in different settings. In this review, we summarize the structure and expression of FBN1 and present our current understanding of the functional role of FBN1 in various human diseases. This knowledge will allow to develop better strategies for therapeutic intervention of FBN1 related diseases.

Positive feedback loops between fibroblasts and the mechanical environment contribute to dermal fibrosis

Dermal fibrosis is characterized by excessive deposition of extracellular matrix in the dermis and affects millions of people worldwide and causes limited movement, disfigurement and psychological distress in patients. Fibroblast dysfunction of plays a central role in the pathogenesis of dermal fibrosis and is controlled by distinct factors. Recent studies support the hypothesis that fibroblasts can drive matrix deposition and stiffening, which in turn can exacerbate the functional dysregulation of fibroblasts. Ultimately, through a positive feedback loop, uncontrolled pathological fibrosis develops. This review aims to summarize the phenomenon and mechanism of the positive feedback loop in dermal fibrosis, and discuss potential therapeutic targets to help further elucidate the pathogenesis of dermal fibrosis and develop therapeutic strategies. In this review, fibroblast-derived compositional and structural changes in the ECM that lead to altered mechanical properties are briefly discussed. We focus on the mechanisms by which mechanical cues participate in dermal fibrosis progression. The mechanosensors discussed in the review include integrins, DDRs, proteoglycans, and mechanosensitive ion channels. The FAK, ERK, Akt, and Rho pathways, as well as transcription factors, including MRTF and YAP/TAZ, are also discussed. In addition, we describe stiffness-induced biological changes in the ECM on fibroblasts that contribute to the formation of a positive feedback loop. Finally, we discuss therapeutic strategies to treat the vicious cycle and present important suggestions for researchers conducting in-depth research.

Ras family signaling pathway in immunopathogenesis of inflammatory rheumatic diseases

The Ras (rat sarcoma virus) is a GTP-binding protein that is considered one of the important members of the Ras-GTPase superfamily. The Ras involves several pathways in the cell that include proliferation, migration, survival, differentiation, and fibrosis. Abnormalities in the expression level and activation of the Ras family signaling pathway and its downstream kinases such as Raf/MEK/ERK1-2 contribute to the pathogenic mechanisms of rheumatic diseases including immune system dysregulation, inflammation, and fibrosis in systemic sclerosis (SSc); destruction and inflammation of synovial tissue in rheumatoid arthritis (RA); and autoantibody production and immune complexes formation in systemic lupus erythematosus (SLE); and enhance osteoblast differentiation and ossification during skeletal formation in ankylosing spondylitis (AS). In this review, the basic biology, signaling of Ras, and abnormalities in this pathway in rheumatic diseases including SSc, RA, AS, and SLE will be discussed.

Immunosuppressants Tacrolimus and Sirolimus revert the cardiac antifibrotic properties of p38-MAPK inhibition in 3D-multicellular human iPSC-heart organoids

Cardiac reactive fibrosis is a fibroblast-derived maladaptive process to tissue injury that exacerbates an uncontrolled deposition of large amounts of extracellular matrix (ECM) around cardiomyocytes and vascular cells, being recognized as a pathological entity of morbidity and mortality. Cardiac fibrosis is partially controlled through the sustained activation of TGF-β1 through IL-11 in fibroblasts. Yet, preclinical studies on fibrosis treatment require human physiological approaches due to the multicellular crosstalk between cells and tissues in the heart. Here, we leveraged an iPSC-derived multi-lineage human heart organoid (hHO) platform composed of different cardiac cell types to set the basis of a preclinical model for evaluating drug cardiotoxicity and assessing cardiac fibrosis phenotypes. We found that the inhibition of the p38-MAPK pathway significantly reduces COL1A1 depositions. Yet, concomitant treatment with organ-rejection immunosuppressant drugs Tacrolimus or Sirolimus reverts this effect, opening new questions on the clinical considerations of combined therapies in reducing fibrosis after organ transplantation.

Shared mechanisms and crosstalk of COVID-19 and osteoporosis via vitamin D

Recently accumulated evidence implicates a close association of vitamin D (VitD) insufficiency to the incidence and clinical manifestations of the COVID-19 caused by severe acute respiratory syndrome coronavirus-2 (SARS-COV-2). Populations with insufficient VitD including patients with osteoporosis are more susceptible to SARS-COV-2 infection and patients with COVID-19 worsened or developed osteoporosis. It is currently unknown, however, whether osteoporosis and COVID-19 are linked by VitD insufficiency. In this study, 42 common targets for VitD on both COVID-19 and osteoporosis were identified among a total of 243 VitD targets. Further bioinformatic analysis revealed 8 core targets (EGFR, AR, ESR1, MAPK8, MDM2, EZH2, ERBB2 and MAPT) in the VitD-COVID-19-osteoporosis network. These targets are involved in the ErbB and MAPK signaling pathways critical for lung fibrosis, bone structural integrity, and cytokines through a crosstalk between COVID-19 and osteoporosis via the VitD-mediated conventional immune and osteoimmune mechanisms. Molecular docking confirmed that VitD binds tightly to the predicted targets. These findings support that VitD may target common signaling pathways in the integrated network of lung fibrosis and bone structural integrity as well as the immune systems. Therefore, VitD may serve as a preventive and therapeutic agent for both COVID-19 and osteoporosis.