P311 Promotes Lung Fibrosis via Stimulation of Transforming Growth Factor-β1, -β2, and -β3 Translation

NREP, transcriptionally upregulated by HIF-1α, aggravates breast cancer cell growth and metastasis by promoting glycolysis

Breast cancer (BC) poses a great threat to women's health. Neuronal regeneration related protein (NREP) is a multifunctional protein that is involved in embryonic development, regeneration, and human disease. However, the biological function of NREP in tumors is rarely reported and its role in BC remains unknown. Bioinformatics analysis showed that NREP is highly expressed and closely correlated with poor survival in BC patients. Under hypoxic conditions, NREP was upregulated in BC cells, and this promotion was reversed by hypoxia-inducible factor HIF-1α suppression. Luciferase reporter system and chromatin immunoprecipitation assays confirmed that HIF-1α directly binds to the promoter of NREP to increase the transcriptional activity of NREP. NREP suppression inhibited cell proliferation, arrested the cell cycle at the G1/S phase, and promoted apoptosis and caspase-3 activity in BC cells. Suppression of NREP decreased the tube formation ability of HUVECs. In addition, NREP downregulation showed an inhibition effect on cell migration, invasion, and EMT of BC cells. In NREP overexpressed cells, all these changes were reversed. In vivo, animal experiments also confirmed that NREP promotes BC tumor growth and metastasis. In addition, NREP promoted cellular glycolysis and enhanced the levels of glucose consumption, ATP, lactate production, and glucose transporters expression in NREP-overexpressed BC cells. In summary, our results demonstrated that NREP could be transcriptional activated by HIF-1α, which may aggravate BC tumor growth and metastasis by promoting cellular glycolysis. This result suggested that NREP may play an essential part in BC progression.

Advances and Challenges in Targeting TGF-β Isoforms for Therapeutic Intervention of Cancer: A Mechanism-Based Perspective

The TGF-β family is a group of 25 kDa secretory cytokines, in mammals consisting of three dimeric isoforms (TGF-βs 1, 2, and 3), each encoded on a separate gene with unique regulatory elements. Each isoform plays unique, diverse, and pivotal roles in cell growth, survival, immune response, and differentiation. However, many researchers in the TGF-β field often mistakenly assume a uniform functionality among all three isoforms. Although TGF-βs are essential for normal development and many cellular and physiological processes, their dysregulated expression contributes significantly to various diseases. Notably, they drive conditions like fibrosis and tumor metastasis/progression. To counter these pathologies, extensive efforts have been directed towards targeting TGF-βs, resulting in the development of a range of TGF-β inhibitors. Despite some clinical success, these agents have yet to reach their full potential in the treatment of cancers. A significant challenge rests in effectively targeting TGF-βs' pathological functions while preserving their physiological roles. Many existing approaches collectively target all three isoforms, failing to target just the specific deregulated ones. Additionally, most strategies tackle the entire TGF-β signaling pathway instead of focusing on disease-specific components or preferentially targeting tumors. This review gives a unique historical overview of the TGF-β field often missed in other reviews and provides a current landscape of TGF-β research, emphasizing isoform-specific functions and disease implications. The review then delves into ongoing therapeutic strategies in cancer, stressing the need for more tools that target specific isoforms and disease-related pathway components, advocating mechanism-based and refined approaches to enhance the effectiveness of TGF-β-targeted cancer therapies.

Low expression of TGF-β2 and matrilin2 in human aqueous humour with acute primary angle closure

Primary angle-closure glaucoma (PACG) is the leading cause of irreversible blindness in the world. Angle closure induced by pupil block and secondary iris synechia is the fundamental pathology of the PACG. The molecular mechanisms of angle closure have not yet been clearly illustrated. This study was designed to investigate the protein difference in the aqueous humour and explore new biomarker of the PACG. Aqueous humour (AH) was collected from patients with acute primary angle closure (APAC) and cataract (n = 10 in APAC group) and patients with cataract only (n = 10 in control group). Samples were pooled and measured using label-free proteome technology. Then, the differentially expressed proteins (DEPs) were verified by ELISA using independent AH samples (n = 20 each group). More than 400 proteins were revealed in both groups through proteomics. Comparing the two groups, there were 91DEPs. These proteins participate in biological activities such as inflammation, fibrosis, nerve growth and degeneration and metabolism. We found that the expression of transforming growth factor-β2 and matrilin2 was downregulated in the APAC group. The two proteins are related to inflammation and extracellular matrix formation, which might be involved in angle closure. This study characterized DEPs in AH of the APAC and found a downregulated protein matrilin2.

H3K18 lactylation promotes the progression of arsenite-related idiopathic pulmonary fibrosis via YTHDF1/m6A/NREP

As epigenetic modifications, lactylation and N6-methyladenosine (m6A) have attracted wide attention. Arsenite is an environmental pollutant that has been proven to induce idiopathic pulmonary fibrosis (IPF). However, the molecular mechanisms of lactylation and m6A methylation are unclear in arsenite-related IPF (As-IPF). In view of the limited understanding of molecular mechanism of m6A and lactylation in As-IPF, MeRIP-seq, RNA-seq and ChIP-seq were analyzed to verify the target gene regulated by m6A and H3K18 lactylation (H3K18la). We found that, for As-IPF, the global levels of m6A, levels of YTHDF1 and m6A-modified neuronal protein 3.1 (NREP) were elevated in alveolar epithelial cells (AECs). The secretion levels of TGF-β1 were increased via YTHDF1/m6A/NREP, which promoted the fibroblast-to-myofibroblast transition (FMT). Further, extracellular lactate from myofibroblasts elevated levels of the global lactylation (Kla) and H3K18la via the lactate monocarboxylate transporter 1 (MCT1), and, in AECs, H3K18la facilitated the transcription of Ythdf1. This report highlights the role of crosstalk between AECs and myofibroblasts via lactylation and m6A and the significance of H3K18la regulation of YTHDF1 in the progression of As-IPF, which may be useful for finding effective therapeutic targets.

The silencing of NREP aggravates OA cartilage damage through the TGF-β1/Smad2/3 pathway in chondrocytes

Background

Osteoarthritis (OA) is a common chronic degenerative joint disease. Due to the limited understanding of its complex pathological mechanism, there is currently no effective treatment that can alleviate or even reverse cartilage damage associated with OA. With improvement in public databases, researchers have successfully identified the key factors involved in the occurrence and development of OA through bioinformatics analysis. The aim of this study was to screen for the differentially expressed genes (DEGs) between the normal and OA cartilage through bioinformatics, and validate the function of the TGF-β1/Smad2/3 pathway-related neuron regeneration related protein (NREP) in the articular cartilage.

Methods

The DEGs between the cartilage tissues of OA patients and healthy controls were screened by bioinformatics, and functionally annotated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. The expression levels of the DEG in human and murine OA cartilage was verified by reverse transcription-quantitative PCR (RT-qPCR), Western blotting and immunohistochemistry (IHC). RT-qPCR, Western-blotting, Cell Counting Kit-8(CCK8) and EdU assays were used to evaluate the effects of knocking down NREP in normal chondrocytes, and the molecular mechanisms were investigated by RT-qPCR, Western blotting and IHC.

Results

In this study, we identified NREP as a DEG in OA through bioinformatics analysis, and found that NREP was downregulated in the damaged articular cartilage of OA patients and mouse model with surgically-induced OA. In addition, knockdown of NREP in normal chondrocytes reduced their proliferative capacity, which is the pathological basis of OA. At the molecular level, knock-down of NREP inactivated the TGF-β1/Smad2/3 pathway, resulting in the downregulation of the anabolic markers Col2a1 and Sox9, and an increase in the expression of the catabolic markers MMP3 and MMP13.

Conclusion

NREP plays a key role in the progression of OA by regulating the TGF-β1/Smad2/3 pathway in chondrocytes, and warrants further study as a potential therapeutic target.

Pulmonary fibrosis: from pathogenesis to clinical decision-making

Pulmonary fibrosis (PF) encompasses a spectrum of chronic lung diseases that progressively impact the interstitium, resulting in compromised gas exchange, breathlessness, diminished quality of life (QoL), and ultimately respiratory failure and mortality. Various diseases can cause PF, with their underlying causes primarily affecting the lung interstitium, leading to their referral as interstitial lung diseases (ILDs). The current understanding is that PF arises from abnormal wound healing processes triggered by various factors specific to each disease, leading to excessive inflammation and fibrosis. While significant progress has been made in understanding the molecular mechanisms of PF, its pathogenesis remains elusive. This review provides an in-depth exploration of the latest insights into PF pathophysiology, diagnosis, treatment, and future perspectives.

Idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive devastating lung disease with substantial morbidity. It is associated with cough, dyspnea and impaired quality of life. If left untreated, IPF has a median survival of 3 years. IPF affects ∼3 million people worldwide, with increasing incidence in older patients. The current concept of pathogenesis is that pulmonary fibrosis results from repetitive injury to the lung epithelium, with fibroblast accumulation, myofibroblast activation, and deposition of matrix. These injuries, in combination with innate and adaptive immune responses, dysregulated wound repair and fibroblast dysfunction, lead to recurring tissue remodeling and self-perpetuating fibrosis as seen in IPF. The diagnostic approach includes the exclusion of other interstitial lung diseases or underlying conditions and depends on a multidisciplinary team-based discussion combining radiological and clinical features and well as in some cases histology. In the last decade, considerable progress has been made in the understanding of IPF clinical management, with the availability of two drugs, pirfenidone and nintedanib, that decrease pulmonary lung function decline. However, current IPF therapies only slow disease progression and prognosis remains poor. Fortunately, there are multiple clinical trials ongoing with potential new therapies targeting different disease pathways. This review provides an overview of IPF epidemiology, current insights in pathophysiology, diagnostic and therapeutic management approaches. Finally, a detailed description of current and evolving therapeutic approaches is also provided.

P311 knockdown alleviates hyperoxia-induced injury by inactivating the Smad3 signaling pathway in type II alveolar epithelial cells

P311 is associated with alveolar formation and development. However, the role and possible mechanism of P311 in hyperoxia-induced injury in type II alveolar epithelial cells (AEC II) need to be elucidated. In our study, rat AEC II (RLE-6TN) were exposure to normoxia (21% O₂ and 5% CO₂) or hyperoxia (95% O₂ and 5% CO₂) for 24 h, followed by determination of P311 expression. After knockdown of P311 and hyperoxic treatment, cell viability, cell cycle progression, apoptosis and the Smad3 signaling pathway were examined. Rat AEC II were pretreated with SIS3 HCl for 4 h and then subjected to P311 overexpression plasmid transfection and hyperoxic exposure. Then, cell viability, apoptosis and the Smad3 signaling pathway were determined. The results showed that hyperoxic exposure significantly elevated P311 levels in rat AEC II. P311 knockdown increased cell viability, accelerated cell cycle progression and inhibited apoptosis, as well as suppression of the Smad3 signaling pathway in hyperoxia-exposed AEC II. Additionally, we found that P311 overexpression enhanced the effects of hyperoxia. Interestingly, SIS3 HCl incubation blocked the effects of P311 overexpression on rat AEC II function under hyperoxic condition, as evidenced by an increase in cell viability, and suppressions of apoptosis and the Smad3 signaling pathway. These results indicate that P311 knockdown may ameliorate hyperoxia-induced injury by inhibiting the Smad3 signaling pathway in rat AEC II. P311 may be a novel target for the treatment of hyperoxia-induced lung injury and even bronchopulmonary dysplasia (BPD).

Promoting Re-epithelialization in an oxidative diabetic wound microenvironment using self-assembly of a ROS-responsive polymer and P311 peptide micelles

Engineering smart nano-therapeutics for re-epithelialisation of chronic wounds facilitates the wound healing process. However, due to excessive oxidative stress damage and persistent inflammation in diabetic wound microenvironment, the migration of stimulating epidermal cells in diabetic wounds represents a significant challenge. Here we synthesised P311-loaded micelles by self-assembly of P311 peptides and diblock copolymer poly (ethylene glycol)-block-poly (propylene sulfide) (PEG-b-PPS, denoted as PEPS) that have unique ability to transform an oxidative wound microenvironment into a proregenerative one while also providing cues for epidermal cell migration. The P311@PEPS showed an accelerated migration of epidermal cells via activation of the Akt signalling pathway, simultaneously suppressing the unfavourable oxidative wound microenvironment by scavenging reactive oxygen species (ROS), ultimately leading to the induction of an environment conducive to cell migration. Furthermore, the micelles were able to bypass the inhibitory effect of ROS on the Akt signalling pathway, thereby promoting epidermal cell migration. Additionally, we observed that diabetic wounds treated with P311@PEPS showed accelerated chronic wound healing, granulation tissue formation, collagen deposition and re-epithelialisation, thereby suggesting the efficacy of P311@PEPS as a promising nanoplatform for the treatment of chronic wounds. STATEMENT OF SIGNIFICANCE: Based on the unique conditions of the diabetic wound microenvironment, a smart drug delivery system with ROS-responsive nanomaterials has been widely investigated to enhance diabetic wound healing. In our previous studies, we observed that P311 promotes epidermal cell migration to induce wound re-epithelialisation. However, the application of P311 suffers from its instability. Herein, we developed a therapeutic platform with P311-loaded micelles (P311@PEPS), which were synthesized by the self-assembly of P311 peptides and diblock copolymer poly (ethylene glycol)-block-poly (propylene sulfide) (PEG-b-PPS, denoted as PEPS). These micelles provide continuous migration signals for epidermal cells by ROS-trigged P311 release. Additionally, P311@PEPS scavenges excess ROS and provides a microenvironment that reduces inflammation, which could protect P311 from enzymatic degradation and improve the bioavailability of P311.

Gene silencing by EZH2 suppresses TGF-β activity within the decidua to avert pregnancy-adverse wound healing at the maternal-fetal interface

A little-appreciated feature of early pregnancy is that embryo implantation and placental outgrowth do not evoke wound-healing responses in the decidua, the specialized endometrial tissue that surrounds the conceptus. Here, we provide evidence that this phenomenon is partly due to an active program of gene silencing mediated by EZH2, a histone methyltransferase that generates repressive histone 3 lysine 27 trimethyl (H3K27me3) histone marks. We find that pregnancies in mice with EZH2-deficient decidual stromal cells frequently fail by mid-gestation, with the decidua showing ectopic myofibroblast formation, peri-embryonic collagen deposition, and gene expression profiles associated with transforming growth factor β (TGF-β)-driven fibroblast activation and fibrogenic extracellular matrix (ECM) remodeling. Analogous responses are observed when the mutant decidua is surgically wounded, while blockade of TGF-β receptor signaling inhibits the defects and improves reproductive outcomes. Together, these results highlight a critical feature of reproductive success and have implications for the context-specific control of TGF-β-mediated wound-healing responses elsewhere in the body.

Common and Rare Genetic Variants That Could Contribute to Severe Otitis Media in an Australian Aboriginal Population

BACKGROUND

Our goal was to identify genetic risk factors for severe otitis media (OM) in Aboriginal Australians.

METHODS

Illumina® Omni2.5 BeadChip and imputed data were compared between 21 children with severe OM (multiple episodes chronic suppurative OM and/or perforations or tympanic sclerosis) and 370 individuals without this phenotype, followed by FUnctional Mapping and Annotation (FUMA). Exome data filtered for common (EXaC_all ≥ 0.1) putative deleterious variants influencing protein coding (CADD-scaled scores ≥15] were used to compare 15 severe OM cases with 9 mild cases (single episode of acute OM recorded over ≥3 consecutive years). Rare (ExAC_all ≤ 0.01) such variants were filtered for those present only in severe OM. Enrichr was used to determine enrichment of genes contributing to pathways/processes relevant to OM.

RESULTS

FUMA analysis identified 2 plausible genetic risk loci for severe OM: NR3C1 (Pimputed_1000G = 3.62 × 10-6) encoding the glucocorticoid receptor, and NREP (Pimputed_1000G = 3.67 × 10-6) encoding neuronal regeneration-related protein. Exome analysis showed: (i) association of severe OM with variants influencing protein coding (CADD-scaled ≥ 15) in a gene-set (GRXCR1, CDH23, LRP2, FAT4, ARSA, EYA4) enriched for Mammalian Phenotype Level 4 abnormal hair cell stereociliary bundle morphology and related phenotypes; (ii) rare variants influencing protein coding only seen in severe OM provided gene-sets enriched for "abnormal ear" (LMNA, CDH23, LRP2, MYO7A, FGFR1), integrin interactions, transforming growth factor signaling, and cell projection phenotypes including hair cell stereociliary bundles and cilium assembly.

CONCLUSIONS

This study highlights interacting genes and pathways related to cilium structure and function that may contribute to extreme susceptibility to OM in Aboriginal Australian children.

Overexpression of NREP Promotes Migration and Invasion in Gastric Cancer Through Facilitating Epithelial-Mesenchymal Transition

The identification of biomarkers and effective therapeutic targets for gastric cancer (GC), the most common cause of cancer-related deaths around the world, is currently a major focus area in research. Here, we examined the utility of Neuronal Regeneration Related Protein (NREP) as a prognostic biomarker and therapeutic target for GC. We assessed the clinical relevance, function, and molecular role of NREP in GC using bioinformatics analysis and experimental validation. Our results showed that in GC, NREP overexpression was significantly associated with a poor prognosis. Our findings also suggested that NREP may be involved in the activation of cancer-associated fibroblasts and the epithelial-mesenchymal transition (EMT), with transforming growth factor β1 mediating both processes. In addition, NREP expression showed a positive correlation with the abundance of M2 macrophages, which are potent immunosuppressors. Together, these results indicate that NREP is overexpressed in GC and affects GC prognosis. Thus, NREP could be a prognostic biomarker and therapeutic target for GC.

Extracellular HSP90α Interacts With ER Stress to Promote Fibroblasts Activation Through PI3K/AKT Pathway in Pulmonary Fibrosis

Pulmonary fibrosis is characterized by alveolar epithelial cell injury, lung fibroblast proliferation, differentiation, and extracellular matrix (ECM) deposition. Our previous study indicated that extracellular HSP90α (eHSP90α) promotes pulmonary fibrosis by activating the MAPK signaling pathway. Thus, treatment with 1G6-D7 (a selective HSP90α monoclonal antibody) to antagonize eHSP90α could effectively ameliorate fibrosis. This study aimed to elucidate the mechanism underlying the effects of eHSP90α in pulmonary fibrosis by focusing on its link with endoplasmic reticulum (ER) stress. Our results showed that eHSP90α promoted lung fibroblast differentiation by activating ER stress. Treatment with the ER stress inhibitor tauroursodeoxycholate (TUDCA) or glucose-regulated protein 78 kDa (GRP78) depletion significantly abrogated the effect of eHSP90α on ER stress and fibroblast activation. In addition, eHSP90α induced ER stress in fibroblasts via the phosphoinositide-4,5-bisphosphate 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway, which could be blocked by the PI3K/AKT inhibitor LY294002, and blockade of eHSP90α by 1G6-D7 markedly inhibited ER stress in the model, indicating preventive and therapeutic applications. Intriguingly, we observed that TUDCA effectively reduced the secretion of eHSP90α in vitro and in vivo. In conclusion, this study shows that the interaction between eHSP90α and ER stress plays a crucial role in pulmonary fibrosis, indicating a positive feedback in lung fibroblasts. Targeting eHSP90α and alleviating fibroblast ER stress may be promising therapeutic approaches for pulmonary fibrosis.

Higher interleukin-6 levels and changes in transforming growth factor-β are associated with lung impairment in pulmonary tuberculosis

Pulmonary tuberculosis (PTB) is associated with granuloma formation, necrosis and cavitation in lung tissue. Lung injury in PTB can persist despite microbiological cure and is associated with COPD independent of smoking exposure [1]. Furthermore, pulmonary sequelae of PTB are an under-recognised cause of respiratory disability and excess mortality [2].

Higher levels of IL-6 and slow-to-resolve TGF-β are associated with lung impairment in treated tuberculosis. These results have important implications for clinical trials of immunomodulatory therapies to prevent tuberculosis-associated lung disease.https://bit.ly/2FQEtsz

Impaired Myofibroblast Dedifferentiation Contributes to Nonresolving Fibrosis in Aging

Idiopathic pulmonary fibrosis (IPF) is a fatal age-associated disease with no cure. Although IPF is widely regarded as a disease of aging, the cellular mechanisms that contribute to this age-associated predilection remain elusive. In this study, we sought to evaluate the consequences of senescence on myofibroblast cell fate and fibrotic responses to lung injury in the context of aging. We demonstrated that nonsenescent lung myofibroblasts maintained the capacity for dedifferentiation, whereas senescent/IPF myofibroblasts exhibited an impaired capacity for dedifferentiation. We previously demonstrated that the transcription factor MyoD acts as a critical switch in the differentiation and dedifferentiation of myofibroblasts. Here, we demonstrate that decreased levels of MyoD preceded myofibroblast dedifferentiation and apoptosis susceptibility in nonsenescent cells, whereas MyoD expression remained elevated in senescent/IPF myofibroblasts, which failed to undergo dedifferentiation and demonstrated resistance to apoptosis. Genetic strategies to silence MyoD restored the susceptibility of IPF myofibroblasts to undergo apoptosis and led to a partial reversal of age-associated persistent fibrosis in vivo. The capacity for myofibroblast dedifferentiation and subsequent apoptosis may be critical for normal physiologic responses to tissue injury, whereas restricted dedifferentiation and apoptosis resistance in senescent cells may underlie the progressive nature of age-associated human fibrotic disorders. These studies support the concept that senescence may promote profibrotic effects via impaired myofibroblast dedifferentiation and apoptosis resistance, which contributes to myofibroblast accumulation and ultimately persistent fibrosis in aging.

Butyrate alleviates diabetic kidney disease by mediating the miR-7a-5p/P311/TGF-β1 pathway

It has been reported that butyrate played an protect role in diabetic kidney disease (DKD) while the mechanism was still not clear. Transforming growth factor-β1 (TGF-β1) is the initial factor which triggers the profibrotic signaling cascades. P311 is an RNA-binding protein, which could stimulate TGF-β1 translation in several cell types. In our study, we found that supplementary of butyrate alleviated fibrosis and suppressed the expression of TGF-β1 and P311 in the kidney of db/db mice as well as high glucose (HG)-induced SV40-MES-13 cells. Overexpression of P311 offset the inhibition of butyrate on TGF-β1 in SV40-MES-13 cells. To make clear the mechanism of butyrate in regulating P311, microRNAs (miRNAs) of the SV40-MES-13 cells were sequenced. We found that miR-7a-5p was significantly decreased in the HG-induced SV40-MES-13 cells and the kidney of db/db mice, while giving butyrate reversed this change. Besides, miR-7a-5p could specifically target the 3' UTR of P311's mRNA and suppressed the expression of P311 in the SV40-MES-13 cells. Giving miR-7a-5p inhibitor blocked the inhibition of butyrate on P311 and TGF-β1. Introducing the miR-7a-5p agomir into db/db mice alleviated renal fibrosis and inhibit the expression of P311 and TGF-β1. In conclusion, butyrate alleviated DKD by mediating the miR-7a-5p/P311/TGF-β1 pathway.

Overexpression of TIM-3 in Macrophages Aggravates Pathogenesis of Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive lung disorder and lacks effective treatments because of unclear mechanisms. Aberrant function of alveolar macrophages is directly linked to pulmonary fibrosis. Here, we show TIM-3 (T-cell immunoglobulin domain and mucin domain-3), a key regulator of macrophage function, aggravates pulmonary fibrosis. TIM-3 mRNA of patients with IPF was analyzed based on the Gene Expression Omnibus and Array Express databases. Lung pathology and profibrotic molecules were assessed in a bleomycin (BLM)-induced pulmonary fibrosis model using wild-type (WT) and TIM-3 transgenic (TIM-3-TG) mice. Macrophage cells, RAW264.7, were then applied to investigate the effect of macrophage TIM-3 under BLM exposure in vitro. Macrophage depletion and adoptive-transfer experiments were finally performed to examine lung morphology and profibrotic molecules. TIM-3 expression was increased both in patients with IPF and in our BLM-induced mouse model. TIM-3-TG mice developed more serious pathological changes in lung tissue and higher expressions of TGF-β1 (transforming growth factor-β1) and IL-10 than WT mice. After BLM treatment, TGF-β1 and IL-10 expression was significantly decreased in RAW264.7 cells after TIM-3 knock-out, whereas it was increased in TIM-3-TG peritoneal macrophages. The scores of pulmonary fibrosis in WT and TIM-3-TG mice were significantly reduced, and there was no difference between them after macrophage depletion. Furthermore, WT mice receiving adoptive macrophages from TIM-3-TG mice also had more serious lung fibrosis and increased expression of TGF-β1 and IL-10 than those receiving macrophages from WT mice. Our findings revealed that overexpressed TIM-3 in alveolar macrophages aggravated pulmonary fibrosis.

Role of angiopoietin-like protein 2 in atrial fibrosis induced by human epicardial adipose tissue: Analysis using an organo-culture system

BACKGROUND

We have recently reported that peri-left atrial epicardial adipose tissue (EAT) is associated with atrial myocardial fibrosis, in which angiopoietin-like protein 2 (Angptl2) protein content in EAT is associated with atrial myocardial fibrosis.

OBJECTIVE

This study aimed to examine whether Angptl2 contained in peri-left atrial EAT can induce atrial myocardial fibrosis.

METHODS

Human peri-left atrial EAT and abdominal subcutaneous adipose tissue (SAT) were collected from 9 autopsy cases. EAT- or SAT-conditioned medium was dropped onto the rat left atrial epicardial surface using an organo-culture system. Conditioned medium, recombinant Angptl2, and its antibody effects on organo-cultured rat atrial myocardial fibrosis were evaluated. Angptl2 effects on cultured neonatal rat fibroblasts were also investigated.

RESULTS

EAT-conditioned medium induced atrial fibrosis in organo-cultured rat atrium with a progressive increase in the number of myofibroblasts. The profibrotic effect of EAT was greater than that of SAT. EAT in patients with atrial fibrillation induced a more significant atrial fibrosis than in those without. Treatment with human recombinant Angptl2 induced fibrosis in organo-cultured rat atrium, which was suppressed by the concomitant treatment with Angptl2 antibody. In cultured fibroblasts, Angptl2 upregulated the expression of α-smooth muscle actin, transforming growth factor-β1, phospho-extracellular signal-regulated kinase,phospho-inhibitor of κBα, and phospho-p38 mitogen-activated protein kinase.

CONCLUSION

This study demonstrated that Angptl2 contained in EAT played a crucial role in EAT-induced inflammatory atrial fibrosis. The results also suggested that antagonizing the expression of Angptl2 in EAT can be a novel therapeutic approach to prevent atrial fibrillation.