Therapeutic Effects of Omentin-1 on Pulmonary Fibrosis by Attenuating Fibroblast Activation via AMP-Activated Protein Kinase Pathway

Omentin-1 attenuates atrial fibrillation via Src/PI3K/Akt signaling-mediated anti-fibrotic effects in cardiac fibroblasts

BACKGROUND

Atrial fibrillation (AF) is characterized by progressive atrial fibrosis, leading to increased morbidity and mortality. While the novel adipokine Omentin-1 demonstrates anti-fibrotic potential across organ systems, its role in AF pathogenesis remains unclear. This study investigates Omentin-1's therapeutic effects and the underlying mechanisms in angiotensin II (Ang II)-induced atrial fibrosis and AF.

METHODS

Atrial fibrosis was induced in C57BL/6 mice via continuous Ang II infusion for 4 weeks. Omentin-1 overexpression was achieved using adeno-associated virus serotype 2/9 (AAV2/9). AF susceptibility was assessed by programmed electrical stimulation, and atrial fibrosis was quantified using histological staining and Western blot analysis. Immunofluorescence co-localization assessed cell-type specific expression of Omentin-1, and proteomic analysis of atrial fibroblasts was conducted to explore molecular pathways involved. In vitro studies using primary fibroblasts were conducted to validate Omentin-1's effects.

RESULTS

Omentin-1 levels were significantly decreased in both serum and atrial tissue of Ang II-treated mice. Omentin-1 overexpression reduced AF inducibility, decreased atrial fibrosis, and improved left atrial strain parameters. Immunofluorescence showed that Omentin-1 predominantly localized to atrial fibroblasts. Mechanistically, Omentin-1 regulated collagen metabolism by targeting fibroblasts, with Src kinase acting as a critical mediator of fibroblast activation through the PI3K/Akt signaling pathway.

CONCLUSION

Omentin-1 attenuates atrial fibrosis and AF susceptibility through regulation of the Src/PI3K/Akt signaling pathway in atrial fibroblasts. These findings suggest that Omentin-1 may represent a potential therapeutic target for the prevention and treatment of AF.

Omentin-General Overview of Its Role in Obesity, Metabolic Syndrome and Other Diseases; Problem of Current Research State

Background: Omentin (omentin-1, intelectin-1, ITLN-1) is an adipokine considered to be a novel substance. Many chronic, inflammatory, or civilization diseases are linked to obesity, in which omentin plays a significant role. Methods: MEDLINE and SCOPUS databases were searched using the keywords "omentin" or "intelectin-1". Then the most recent articles providing new perspectives on the matter and the most important studies, which revealed crucial insight, were selected to summarize the current knowledge on the role of omentin in a literature review. Results and Conclusions: The valid role of this adipokine is evident in the course of metabolic syndrome. In most cases, elevated omentin expression is correlated with the better course of diseases, including: type 2 diabetes mellitus, polycystic ovary syndrome, rheumatoid arthritis, metabolic dysfunction-associated steatotic liver disease, Crohn's disease, ulcerative colitis, atherosclerosis, or ischemic stroke, for some of which it can be a better marker than the currently used ones. However, results of omentin studies are not completely one-sided. It was proven to participate in the development of asthma and atopic dermatitis and to have different concentration dynamics in various types of tumors. All of omentin's effects and properties make it an attractive subject of research, considering still unexplored inflammation mechanisms, in which it may play an important role. Omentin was proven to prevent osteoarthritis, hepatocirrhosis, and atherosclerosis in mouse models. All of the above places omentin among potential therapeutic products, and not only as a biomarker. However, the main problems with the omentin's research state are the lack of standardization, which causes many contradictions and disagreements in this field.

circ0066187 promotes pulmonary fibrogenesis through targeting STAT3-mediated metabolism signal pathway

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial pneumonia, with increasing incidence and prevalence. One of the cellular characteristics is the differentiation of fibroblasts to myofibroblasts. However, the metabolic-related signaling pathway regulated by circular RNAs (circRNAs) during this process remains unclear. Here, we demonstrated that circ0066187 promoted fibroblast-to-myofibroblast differentiation by metabolic-related signaling pathway. Mechanism analysis research identified that circ0066187 directly targeted signal transducer and activator of transcription 3 (STAT3)-mediated metabolism signal pathway to enhance fibroblast-to-myofibroblast differentiation by sponging miR-29b-2-5p, resulting in pulmonary fibrosis. Integrative multi-omics analysis of metabolomics and proteomics revealed three pathways co-enriched in proteomics and metabolomics, namely, Protein digestion and absorption, PI3K-Akt signaling pathway, and FoxO signaling pathway. In these three signaling pathways, seven differentially expressed metabolites such as L-glutamine, L-proline, adenosine monophosphate (AMP), L-arginine, L-phenylalanine, L-lysine and L-tryptophan, and six differentially expressed proteins containing dipeptidyl peptidase-4 (DPP4), cyclin D1 (CCND1), cyclin-dependent kinase 2 (CDK2), fibroblast growth factor 2 (FGF2), collagen type VI alpha 1 (COL6A1) and superoxide dismutase 2 (SOD2) were co-enriched. Gain-and loss-of-function studies and rescue experiments were performed to verify that circ0066187 promoted STAT3 expression by inhibiting miR-29b-2-5p expression to control the above metabolites and proteins. As a result, these metabolites and proteins provided the material basis and energy requirements for the progression of pulmonary fibrosis. In conclusion, circ0066187 can function as a profibrotic metabolism-related factor, and interference with circ0066187 can prevent pulmonary fibrosis. The finding supported that circ0066187 can be a metabolism-related therapeutic target for IPF treatment.

Update of Aging Hallmarks in Idiopathic Pulmonary Fibrosis

Idiopathic Pulmonary Fibrosis (IPF) is an epithelial-driven interstitial lung disease of unknown etiology characterized by the excessive proliferation of fibroblast populations that synthesize large amounts of extracellular matrix. In this devastating disorder, all aging hallmarks appear prematurely or are altered. This review highlights key findings about IPF characteristics recently recognized as hallmarks of aging, including mechanical alterations, inflammaging, dysbiosis, alternative splicing, and disabled macroautophagy. It also revisits the classic hallmarks of aging, which encompass stem cell exhaustion, cellular senescence, and altered intercellular communication. Enhancing our understanding of the fundamental processes that underlie the altered hallmarks of aging in IPF may facilitate the development of innovative experimental strategies to improve therapeutic outcomes.

Relationship between serum Midkine and Omentin-1 levels and the severity of sepsis in patients and their prognostic value

To explore the relationship between serum levels of midkine and omentin-1 and the severity of sepsis in patients, and their prognostic value. A retrospective analysis was conducted on the clinical data of 180 sepsis patients. According to the severity of the patient's condition, they were separated into sepsis group (n = 76), severe sepsis group (n = 59), and sepsis shock group (n = 45). Based on the survival within 28 days of admission, they were grouped into survivors group (n = 128) and nonsurvivors group (n = 52). The serum Midkine level and APACHE II score in the sepsis shock group were higher than those in the severe sepsis group and sepsis group, while the Omentin-1 level was lower than that in the severe sepsis group and sepsis group (p < 0.05). The serum Midkine level and APACHE II score in the severe sepsis group were higher than those in the sepsis group, while the Omentin-1 level was lower than that in the sepsis group (p < 0.05). The Midkine and APACHE II score in the nonsurvivors group was higher than those in the survivors group, while the Omentin-1 score was lower than that in the survivors group (p < 0.05). Midkine and APACHE II score were independent risk factors for the prognosis of sepsis patients, while Omentin-1 was a protective factor for the prognosis of sepsis patients (p < 0.05). The AUC of the combined prediction of serum Midkine and Ommentin-1 for the prognosis of sepsis patients was 0.880, with a sensitivity of 90.38% and a specificity of 72.66%. The combined prediction of serum Midkine and Ommentin-1 was better than that of individual prediction of Midkine and Ommentin-1. Serum Midkine is highly expressed and Omentin-1 is lowly expressed in sepsis patients, and the combination of the two has a high predictive power for the prognosis of sepsis patients.

Omentin-1 induces mechanically activated fibroblasts lipogenic differentiation through pkm2/yap/pparγ pathway to promote lung fibrosis resolution

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease characterized by extensive extracellular matrix (ECM) deposition by activated myofibroblasts, which are specialized hyper-contractile cells that promote ECM remodeling and matrix stiffening. New insights on therapeutic strategies aimed at reversing fibrosis by targeting myofibroblast fate are showing promise in promoting fibrosis resolution. Previously, we showed that a novel adipocytokine, omentin-1, attenuated bleomycin (BLM)-induced lung fibrosis by reducing the number of myofibroblasts. Apoptosis, deactivation, and reprogramming of myofibroblasts are important processes in the resolution of fibrosis. Here we report that omentin-1 reverses established lung fibrosis by promoting mechanically activated myofibroblasts dedifferentiation into lipofibroblasts. Omentin-1 promotes myofibroblasts lipogenic differentiation by inhibiting dimerization and nuclear translocation of glycolytic enzymes pyruvate kinase isoform M2 (PKM2) and activation of the downstream Yes-associated protein (YAP) by increasing the cofactor fructose-1,6-bisphosphate (F1, 6BP, FBP). Moreover, omentin-1 activates proliferator-activated receptor gamma (PPARγ) signaling, the master regulator of lipogenesis, and promotes the upregulation of the lipogenic differentiation-related protein perilipin 2 (PLIN2) by suppressing the PKM2-YAP pathway. Ultimately, omentin-1 facilitates myofibroblasts transformation into the lipofibroblast phenotype, with reduced collagen synthesis and enhanced degradation properties, which are crucial mechanisms to clear the ECM deposition in fibrotic tissue, leading to fibrosis resolution. Our results indicate that omentin-1 targets mechanical signal accelerates fibrosis resolution and reverses established lung fibrosis by promoting myofibroblasts lipogenic differentiation, which is closely associated with ECM clearance in fibrotic tissue. These findings suggest that targeting mechanical force to promote myofibroblast lipogenic differentiation is a promising therapeutic strategy against persistent lung fibrosis.

[Adipocytes, adipokines and metabolic alterations in pulmonary fibrosis]

Idiopathic pulmonary fibrosis (IPF) is a fatal respiratory disease characterized by severe remodeling of the lung parenchyma, with an accumulation of activated myofibroblasts and extracellular matrix, along with aberrant cellular differentiation. Within the subpleural fibrous zones, ectopic adipocyte deposits often appear. In addition, alterations in lipid homeostasis have been associated with IPF pathophysiology. In this mini-review, we will discuss the potential involvement of the adipocyte secretome and its paracrine or endocrine-based contribution to the pathophysiology of IPF, via protein or lipid mediators in particular.