Follistatin-like protein 1 and its role in inflammation and inflammatory diseases

Gut microbiome and blood biomarkers reveal differential responses to aerobic and anaerobic exercise in collegiate men of diverse training backgrounds

The gut microbiome influences physiological responses to exercise by modulating inflammatory markers and metabolite production. Athletes typically exhibit greater microbial diversity, which may be associated with improved performance, but the mechanisms linking different exercise modalities to the gut microbiome are not fully understood. In this study, blood and stool samples were collected from endurance athletes, strength athletes, and non-athletic controls performing two maximal exercise tests (the anaerobic Wingate test and the aerobic Bruce Treadmill Test) to integrate serum biomarker data with gut bacterial metagenomic profiles. While most biochemical markers showed similar post-exercise trends across groups, SPARC (secreted protein acidic and rich in cysteine) and adiponectin levels showed modality-specific responses. Strength-trained participants showed unique microbiome-biomarker associations after the Wingate test. In addition, baseline enrichment of certain bacterial taxa, including Clostridium phoceensis and Catenibacterium spp., correlated with reduced Bruce Treadmill test response in strength-trained individuals. These findings, while requiring further validation, indicate the complex interplay between exercise type, training background, and the gut microbiome, and suggest that specific microbial species may help shape recovery and adaptation.

Poliumoside Exhibits Neuroprotective Effects against Cerebral Ischemia-Reperfusion Injury by Relieving Microglia-Mediated Neuronal Damage and Astrocytic Activation

Excessive activation of microglia contributes to neuronal damage and astrocytic activation during cerebral ischemia and hypoxia. Poliumoside (Pol) is a caffeoylated phenylpropanoid glycoside with significant anti-inflammatory and antioxidant functions. However, whether Pol can mediate microglia-mediated neurotoxicity in the ischemic brain remains nebulous. Here, a cerebral ischemia-reperfusion injury (CI/RI) mouse model was conducted to investigate Pol's role in microglial activation and neurotoxicity. We found that Pol significantly reduced neurological deficits, cerebral infarction volume, and neuronal damage in the CI/RI mouse model. Pol inhibited proinflammatory cytokines and microglial and astrocytic activation, while enhancing anti-inflammatory cytokines. Mechanistically, Pol markedly suppressed Fstl1, NF-κB phosphorylation, and the Nlrp3-Asc-Caspase1 inflammasome. In the oxygen-glucose-deprivation (OGD)-mediated BV2 microglia, Fstl1 overexpression significantly enhanced microglial activation. The conditioned medium of Fstl1-overexpressed microglia promoted astrocytic activation and neuronal injuries. However, Pol treatment or NF-κB pathway inhibition reversed Fstl1-mediated effects. In conclusion, Pol restrained microglia-modulated neuroinflammation and neurotoxicity in the cerebral hypoxic-ischemic model by restraining the Fstl1-NF-κB pathway.

Proteomics analysis of extracellular vesicles during Vibrio anguillarum infection in lumpfish (Cyclopterus lumpus)

Lumpfish (Cyclopterus lumpus) is a native fish of the North Atlantic Ocean used as sea lice biocontrol in Atlantic salmon farms. Lumpfish also has been used as model for marine infectious diseases and immunity. Lumpfish is susceptible to Vibrio anguillarum infection, and upon infection, lumpfish immunity is activated to preclude the disease progression. Extracellular vesicles (EVs) play an important role in early immune cellular communication. Lumpfish EVs and their potential role in immunity have not been explored. Herein, EVs where isolated from serum of naïve lumpfish and from lumpfish infected with V. anguillarum at 5 and 10 days post infection (dpi). EVs characteristics were studied by electron microscopy and nanoparticle tracking, and protein cargo was analysed by Western blot and proteomic analysis. The isolated EVs showed a spherical shape ranging from ∼30 nm to 300 nm in diameter, but at 5 dpi the size variation was higher. A total of 395 proteins were identified. Upregulated proteins were linked to complement pathway/innate immunity, heme/iron binding, defense response to bacterium, apoptotic signaling pathway, and actin binding. Downregulated proteins were associated with ribonucleoprotein/ribosomal protein, transport and translation elongation factor activity, acute phase, protein phosphorylation and apoptotic process. Upon infection V. anguillarum infection, lumpfish EVs cargo was modified, from transporting metabolic proteins to proteins related to immunity. Characterization of peripheral lumpfish EVs protein profile during V. anguillarum infection provided with potential biomarkers repertoire that could be utilised in the development of novel tools to diagnose and control of V. anguillarum infection in finfish aquaculture.

Follistatin-like protein 1: Implications for renal disease progression

Renal diseases, including glomerulonephritis, acute kidney injury, chronic kidney failure, and kidney tumors are all current global health challenges. Lesions in other systems can cause renal diseases and can affect other systems or even the whole body. Despite ongoing advancements in pharmaceutical and technological innovations, the prognosis for end-stage renal disease, encompassing renal failure and tumors, continues to be bleak. Follistatin-like protein 1 (FSTL1) is a secreted glycoprotein produced mainly by mesenchymal cells. FSTL1 is a glycoprotein that belongs to the family of secreted, cysteine-rich acidic proteins (SPARC). It plays a pivotal role in cell survival, proliferation, differentiation, and migration, as well as in modulating inflammation and immune responses. Research has shown that FSTL1 plays a crucial role in the onset and progression of renal diseases. This review explores the functions and underlying mechanisms of FSTL1 in kidney pathology. SIGNIFICANCE STATEMENT: This review highlights the pivotal role of FSTL1 in renal diseases, particularly its involvement in renal fibrosis, inflammation, and ischemia-reperfusion injury. By elucidating its dual roles across different pathologies, this work underscores FSTL1's potential as both a biomarker and a therapeutic target, offering novel insights for managing chronic kidney disease and associated complications.

Hypoxemia exerts detrimental effects on the choroid plexuses and cerebrospinal fluid system in rats

BACKGROUND

Hypoxemia can cause secondary acute brain injury, but the mechanisms behind it are not entirely clear and could involve disturbances in the brain extracellular fluids. We aimed to explore the effects of hypoxemia on the choroid plexus (CPs) and cerebrospinal fluid (CSF) system in rats.

METHODS

Male Sprague Dawley rats were kept in O2 control in vivo cabinet with either 21% (normoxia) or 8% O2 (hypoxemia) for up to 48 h. In some cases, signaling of selected cytokines was inhibited prior to hypoxemia. CSF and blood samples were collected by Cisterna Magna puncture and through venous catheters, respectively. The percentages of dead cells in the CPs and ependymal layers (EL) after hypoxemia or normoxia was estimated using TUNEL staining. CP's ultrastructure was analyzed by transmission electron microscopy. Protein concentration in the CSF and plasma was measured and the CSF albumin-to-total protein ratios were estimated. Concentrations of hypoxia-related cytokines in the CSF and plasma samples were estimated using the multiplex immunoassay. Data was analyzed by one-way ANOVA followed by either Bonferroni or Tukey's multiple comparison tests, or Student's t-test. Results are presented as mean ± SD; p < 0.05 was considered statistically significant.

RESULTS

Duration of hypoxemia exerted significant effects on the cell viability in the CPs (p < 0.01) and EL (p < 0.01) and caused apoptosis-related changes in the CP. Hypoxemia had significant effects on the protein concentration in the CSF (p < 0.05), but not in plasma (p > 0.05), with a significant increase in the CSF albumin-to-total protein ratio after 6 h hypoxemia (p < 0.05). Thirty-two cytokines were detected in the CSF. Hypoxemia caused a statistically significant reduction in the concentrations of 12 cytokines, while concentrations of erythropoietin (EPO) and vascular endothelial growth factor (VEGF) increased significantly. Exposure to hypoxemia after inhibitions of EPO, VEGF, or tumor necrosis factor alpha (TNFα) signaling resulted in more dead cells (p < 0.01), less dead cells (p < 0.01) and more dead cells (p < 0.01) in the CPs, respectively, when compared to the number of dead cells when these cytokines were not inhibited. The density of macrophages in the CPs decreased significantly during hypoxemia; that effect was cancelled out by TNFα inhibition.

CONCLUSION

Hypoxemia had detrimental effects on the CPs and CSF system, which was modulated by hypoxia- and inflammation-related cytokines.

FSTL1 and TLR4 interact with PEDV structural proteins to promote virus adsorption to host cells

Infection with porcine epidemic diarrhea virus (PEDV) results in enormous economic damage to the global swine industry. PEDV starts its life cycle by binding to the receptors of host cells and adsorbing onto the cellular surfaces. However, it is still unknown how PEDV adsorbs onto the surface of host cells and the mechanism beneath the interplay of host cell transmembrane protein with PEDV proteins. FSTL1, which is a secreted glycoprotein, participates in diverse pathological and physiological processes, including immune modulation and cell proliferation and differentiation. The transmembrane protein, TLR4, serves as a pattern recognition receptor recognizing a broad spectrum of pathogens, which exerts a crucial effect on the host immune system. In this study, we identified that FSTL1 promoted PEDV infection. Further studies demonstrated the interactive relationship between FSTL1 and PEDV structural proteins (N and S2). In addition, we also confirmed that TLR4 interacted with FSTL1 and PEDV N, S1, and S2 proteins on the cell surface. Moreover, FSTL1 promoted the interaction of TLR4 and PEDV and induced viral adsorption to host cells. This study offers explicit evidence that FSTL1 and TLR4 act as mediators for host cell adsorption of PEDV by interacting with PEDV N/S proteins.IMPORTANCEAs a highly infectious porcine epidemic diarrhea virus (PEDV)-induced intestinal condition of swine, porcine epidemic diarrhea (PED) results in a 100% death rate among suckling piglets and poses a serious economic burden to global swine farming. Therefore, it is essential to investigate the mechanism of virus infection, replication, and proliferation. Virus begins its life cycle by binding to the receptor of host cells and adsorbing onto the cellular surfaces. However, it remains unclear how PEDV adsorbs onto the host cell surfaces. This study revealed that host protein FSTL1 interacted with the PEDV N and S2 proteins, while TLR4 interacted with the FSTL1 and PEDV proteins (N, S1, and S2). Moreover, we thoroughly and methodically demonstrated that FSTL1 was engaged in the PEDV internalization and attachment processes by promoting the recognition of PEDV N\S proteins by TLR4 and induced the viral adsorption to host cells.

Systemic Immune Inflammation Index, Systemic Inflammation Response Index, Aggregate Index of Systemic Inflammation, and Follistatin-Like Protein-1 Levels in Children Diagnosed with Pneumonia

Background: This study aims to evaluate systemic immune inflammation index, systemic inflammatory response index (SIRI), aggregate index of systemic inflammation (AISI), and follistatin-like protein-1 (FSTL-1) levels in children with pneumonia and healthy controls. Methods: The study was carried out at the Seydisehir State Hospital between February 1, 2024 and June 1, 2024. The patient group included 44 children diagnosed with pneumonia and the control group included 45 healthy children without any disease. Index values obtained from hemogram data. Enzyme-linked immunosorbent assay was used to measure FSTL-1 levels. Results: A total of 89 participants, 44 in the patient group and 45 in the healthy control group, were included in the study. White blood cells, monocyte, eosinophil, neutrophil, c-reactive protein, SIRI, and AISI levels were significantly higher in the patient group than in the control group. FSTL-1 levels were higher in the patient group, but did not differ statistically significant. The patient and control groups were compared in the receiver operating characteristics analysis, we found the highest area under curve (AUC) in the SIRI (AUC: 0.754) and AISI (AUC: 0.713) parameters. Conclusion: In conclusion, compared to healthy controls, SIRI and AISI levels were significantly higher in the patient group, and the highest AUC values belonged to these indices. Therefore, we believe that SIRI and AISI indices, which are inexpensive and simple tests, are useful for early diagnosis and treatment of pneumonia.

Post-symptomatic administration of hMSCs exerts therapeutic effects in SCA2 mice

BACKGROUND

Defects in the ataxin-2 (ATXN-2) protein and CAG trinucleotide repeat expansion in its coding gene, Atxn-2, cause the neurodegenerative disorder spinocerebellar ataxia type 2 (SCA2). While clinical studies suggest potential benefits of human-derived mesenchymal stem cells (hMSCs) for treating various ataxias, the exact mechanisms underlying their therapeutic effects and interaction with host tissue to stimulate neurotrophin expression remain unclear specifically in the context of SCA2.

METHODS

Human bone marrow-derived MSCs (hMSCs) were injected into the cisterna magna of 26-week-old wild-type and SCA2 mice. Mice were assessed for impaired motor coordination using the accelerating rotarod, open field test, and composite phenotype scoring. At 50 weeks, the cerebellum vermis was harvested for protein assessment and immunohistochemical analysis.

RESULTS

Significant loss of NeuN and calbindin was observed in 25-week-old SCA2 mice. However, after receiving multiple injections of hMSCs starting at 26 weeks of age, these mice exhibited a significant improvement in abnormal motor performance and a protective effect on Purkinje cells. This beneficial effect persisted until the mice reached 50 weeks of age, at which point they were sacrificed to study further mechanistic events triggered by the administration of hMSCs. Calbindin-positive cells in the Purkinje cell layer expressed bone-derived neurotrophic factor after hMSC administration, contributing to the protection of cerebellar neurons from cell death.

CONCLUSION

In conclusion, repeated administration of hMSCs shows promise in alleviating SCA2 symptoms by preserving Purkinje cells, improving neurotrophic support, and reducing inflammation, ultimately leading to the preservation of locomotor function in SCA2 mice.

Gut microbiota and their relationship with circulating adipokines in an acute hepatic encephalopathy mouse model induced by surgical bile duct ligation

Background and aims

Various studies have shown the importance of the gut microbiota in human health. However, little is known about gut microbiome patterns and their effect on circulating adipo-myokine levels in hepatic encephalopathy (HE). We investigated the relationship between the gut microbiota and adipo-myokine levels using a mouse model of HE induced by surgical bile duct ligation (BDL).

Methods and results

Wild-type C57BL/6J mice were subjected to sham surgery or BDL. Severe body weight loss, suppressed feed intake, and liver failure were observed in BDL mice compared with sham control mice. Additionally, changes in gut microbial communities and serum adipo-myokine levels were noted in BDL mice. In the BDL mouse gut, we identified 15 differentially abundant taxa including the phylum Verrucomicrobiota, the classes Actinomycetes and Verrucomicrobiae, the order Verrucomicrobiales, the families Akkermansiaceae, Bacteroidaceae, Rikenellaceae, and Oscillospiraceae, the genera Alistipes, Akkermansia, Muribaculum, and Phocaeicola, and the species Akkermansia muciniphila, Alistipes okayasuensis, and Muribaculum gordoncarteri by LEfSe analysis (LDA score≥4.0). Higher levels of certain adipo-myokines such as BDNF were detected in the serum of BDL mice. Spearman correlation analysis revealed that certain adipo-myokines (e.g., FSTL1) were positively correlated with the class Actinomycetes, the family Rikenellaceae, the genus Alistipes, and the species Alistipes okayasuensis. Interestingly, A. okayasuensis and M. gordoncarteri, recently isolated microbes, showed richness in the gut of BDL mice and demonstrated positive correlations with adipo-myokines such as FGF21.

Conclusions

Overall, our results suggest that alteration of the gut microbiota in patients with HE may be closely correlated to the levels of adipo-myokines in the blood.

Differential expression of FSTL1 and its correlation with the pathological process of periodontitis

AIMS

This study aimed to elucidate the alterations in Follistatin-like protein 1 (FSTL1) and its association with the pathological process of periodontitis.

METHODS

This study included 48 patients with periodontitis and 42 healthy controls. The expression level of FSTL1 in the gingiva was determined by RT-qPCR, validated using the dataset GSE16134, and subsequently examined by western blotting. Bioinformatics analysis revealed a single-cell distribution of FSTL1, characteristic of angiogenesis and immune cell infiltration. The expression and distribution of FSTL1, vascular endothelial marker protein CD31 and myeloperoxidase (MPO), the indicator of neutrophil activity, were determined by immunohistochemistry (IHC). A series of correlation analyses was performed to determine the associations between FSTL1 and clinical parameters, including probing depth (PD) and clinical attachment loss (CAL), and their potential role in angiogenesis (CD31) and neutrophil infiltration (MPO).

RESULTS

FSTL1 was significantly upregulated in the gingiva of patients with periodontitis compared to their healthy counterparts. In addition, FSTL1 was positively correlated with the clinical parameters PD (r = .5971, p = .0005) and CAL (r = .6078, p = .0004). Bioinformatic analysis and IHC indicated that high FSTL1 expression was significantly correlated with angiogenesis and neutrophil infiltration in periodontitis. Moreover, receiver operating characteristic (ROC) analysis demonstrated that FSTL1 could serve as an independent indicator for evaluating the severity of periodontitis (area under the curve [AUC] = 0.9011, p < .0001).

CONCLUSION

This study demonstrated FSTL1 upregulation in periodontitis and its potential contribution to the disease via angiogenesis and neutrophil infiltration.

A site-specific phosphorylation in FSTL1 determines its promigratory role in wound healing

Follistatin like-1 (FSTL-1) is a secreted glycoprotein of mesenchymal in origin. In human skin, FSTL1 is upregulated in the epidermal keratinocytes upon acute injury and is required for the migration of keratinocytes. Failure to upregulate FSTL1 leads to the lack of keratinocyte migration and the non-healing nature of diabetic foot ulcer (DFU). FSTL1 undergoes extensive post-translational modification (PTM) at specific residues. Glycosylation at N144, N175 and N180, are the only experimentally demonstrated PTM in FSTL1, wherein, N180 and N144 glycosylations have been found to be critical for its function in cardiac tissue regeneration and pre-adipocyte differentiation, respectively. However, it is not known if PTMs other than glycosylation occurs in FSTL1 and how it impacts its pro-migratory function. Using in-silico analysis of mass spectrometric datasets, we found a novel PTM, namely, Serine 165 (S165) phosphorylation in FSTL1. To address the role of S165 phosphorylation in its pro-migratory function, a phosphorylation defective mutant of FSTL1 (S165A) was constructed by converting serine 165 to alanine and over expressed in 293T cells. S165A mutation did not affect the secretion of FSTL1 in vitro. However, S165A abolished the pro-migratory effect of FSTL1 in cultured keratinocytes likely via its inability to facilitate ERK signaling pathway. Interestingly, bacterially expressed recombinant FSTL1, trans-dominantly inhibited wound closure in keratinocytes highlighting the prime role of FSTL1 phosphorylation for its pro-migratory function. Further, under high glucose conditions, which inhibited scratchwound migration of keratinocytes, we noticed a significant decrease in S165 phosphorylation. Taken together, our results reveal a hitherto unreported role of FSTL1 phosphorylation PTM with profound implications in wound healing.

Multi-omics profiling reveals peripheral blood biomarkers of multiple sclerosis: implications for diagnosis and stratification

Background

Multiple sclerosis (MS), a chronic autoimmune disorder marked by demyelination in the central nervous system, is exceptionally uncommon in China, and remains poorly understood in terms of its peripheral blood manifestations.

Methods

We conducted a cohort study comprising 39 MS patients and 40 normal controls (NC). High-dimensional mass cytometry, protein arrays, and targeted metabolomics were utilized to profile immune subsets, proteins, and metabolites in blood. Differences in multi-omics signatures were scrutinized across varying MS subtypes.

Results

Immune profiling demonstrated an elevation in various B cell subsets and monocytes, alongside a reduction in dendritic cells among MS patients. Proteomic data revealed a downregulation in neurotrophic and tissue repair proteins. Metabolomic assessment showed a noted decrease in anti-inflammatory molecules and sphingolipids. Integrated analysis identified distinct molecular patterns distinguishing MS from controls. Additionally, multi-omics differences among different MS subtypes were uncovered. Notably, hippuric acid levels was consistently lower in MS subgroups with greater disease severity.

Conclusion

This study represents the pioneering exploration of multi-omics in Chinese MS patients, presenting a comprehensive view of the peripheral blood changes in MS. Our study underscores the robust capability of multi-omics assessments in identifying peripheral blood biomarkers that delineate the varied clinical presentation, and facilitates future development of biomarkers and targeted therapeutic interventions in MS.

FSTL1 Accelerates Nucleus Pulposus Cell Senescence and Intervertebral Disc Degeneration Through TLR4/NF-κB Pathway

Intervertebral disc degeneration (IVDD) is a major contributor to low back pain (LBP), and inflammatory factors play crucial roles in its pathogenesis. Follistatin-like 1 (FSTL1) has been reported to induce an inflammatory response in chondrocytes, microglia and preadipocytes, but its role in the pathogenesis of nucleus pulposus cell (NPC) degeneration remains unclear. In this study, we mainly utilized an acidosis-induced NPC degeneration model and a rabbit puncture IVDD model to investigate the role of FSTL1 in IVDD both in vitro and in vivo. We confirmed that FSTL1 expression significantly increased in nucleus pulposus (NP) tissues from IVDD patients and rabbit puncture IVDD models. The expression levels of FSTL1 were significantly increased in all three models of NPC degeneration under harsh microenvironments. In addition, recombinant human FSTL1 (rh-FSTL1) was found to upregulate the expression of p16 and p21, increase the number of senescence-associated β-galactosidase (SA-β-gal)-positive cells, induce senescence-related secretory phenotypes (SASP), and downregulate extracellular matrix (ECM) protein expressions, leading to an imbalance in ECM metabolism destructions. Conversely, silencing of FSTL1 by small interfering RNA (siRNA) ameliorated senescence of NPCs associated with inflammation in IVDD. Furthermore, Toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) pathway plays a crucial role in regulating NPC senescence through FSTL1 regulation. Inhibition of TLR4 expression partly reversed the effects of rh-FSTL1 on NPC senescence-associated inflammation. Finally, rabbit IVDD model experiments demonstrated that the specific FSTL1 siRNA markedly repressed the development of IVDD. These findings may offer a therapeutic approach for mitigating inflammation-induced senescence associated with IVDD.

Impact of Bariatric Surgery on metabolic health in a Uruguayan cohort and the emerging predictive role of FSTL1

Obesity poses significant challenges, necessitating comprehensive strategies for effective intervention. Bariatric Surgery (BS) has emerged as a crucial therapeutic approach, demonstrating success in weight loss and comorbidity improvement. This study aimed to evaluate the outcomes of BS in a cohort of 48 Uruguayan patients and investigate the interplay between BS and clinical and metabolic features, with a specific focus on FSTL1, an emerging biomarker associated with obesity and inflammation. We quantitatively analyzed BS outcomes and constructed linear models to identify variables impacting BS success. The study revealed the effectiveness of BS in improving metabolic and clinical parameters. Importantly, variables correlating with BS success were identified, with higher pre-surgical FSTL1 levels associated with an increased effect of BS on BMI reduction. FSTL1 levels were measured from patient plasma using an ELISA kit pre-surgery and six months after. This research, despite limitations of a small sample size and limited follow-up time, contributes valuable insights into understanding and predicting the success of BS, highlighting the potential role of FSTL1 as a useful biomarker in obesity.

FSTL1: A double-edged sword in cancer development

Flolistatin-related protein 1 (FSTL1), a secreted glycoprotein that is involved in many physiological functions, has attracted much interest and has been implicated in a wide range of diseases, including heart diseases and inflammatory diseases. In recent years, the involvement of FSTL1 in cancer progression has been implicated and researched. FSTL1 plays a contradictory role in cancer, depending on the cancer type as well as the contents of the tumor microenvironment. As reviewed here, the structure and distribution of FSTL1 are first introduced. Subsequently, the expression and clinical significance of FSTL1 in various types of cancer as a tumor enhancer or inhibitor are addressed. Furthermore, we discuss the functional role of FSTL1 in various processes that involve tumor cell proliferation, metastasis, immune responses, stemness, cell apoptosis, and resistance to chemotherapy. FSTL1 expression is tightly controlled in cancer, and a multitude of cancer-related signaling cascades like TGF-β/BMP/Smad signaling, AKT, NF-κB, and Wnt-β-catenin signaling pathways are modulated by FSTL1. Finally, FSTL1 as a therapeutic target using monoclonal antibodies is stated. Herein, we review recent findings showing the double-edged characteristics and mechanisms of FSTL1 in cancer and elaborate on the current understanding of therapeutic approaches targeting FSTL1.

Protein profiles in the transfected oviductal secreting cells of laying hen (Gallus gallus domesticus)

Due to the intensive development of novel biopharming applications, there is a need for the in vitro verification models prior to in vivo testing. Laying hen has been already applied as an animal bioreactor to produce the therapeutical enzyme in a rare disease called lysosomal acid lipase deficiency. In this study, we aimed to verify how the proteome of the transfected oviduct epithelial cells would be affected by genetic nonviral modification with the human exogene. The study was based on a previously developed method to cultivate chicken oviduct epithelial cells (COEC). The typical characteristics of the COEC epithelial cells were retained across the experiments. The mean efficiency of nucleofection ranged from 2.6 to 19.7% depending on the cells' isolation and location in the oviduct (upper, infundibulum site, or magnum). The PCR confirmed the incorporation of human interferon alpha2a (hIFNα2a) exogene into the nucleofected COEC but, the production of hIFNα2a protein did not exceed the detection level in this study. The ovalbumin protein was detected in the nontransfected and transfected COEC, which confirmed the normal secreting functions of the cells subject to modification. Proteomic analysis revealed an increase in abundance of the cell adhesion molecules and collagen molecules after introducing gene under ovalbumin promoter. According to the bioinformatic analyses there was a limited negative impact of transfection on cells, and the normal biochemical pathways were not severely disordered. In conclusion, the observations provide new knowledge about the proteomic profile of the manipulated COEC with regard to the retained normal functionality of the cells, which can be informative for avian biopharma research.

Single-cell transcriptome analysis reveals cellular heterogeneity and highlights Fstl1-regulated alveolar myofibroblasts in mouse lung at birth

The matricellular protein, follistatin-like 1 (FSTL1), regulates lung development and saccular formation. Here, we employed single-cell RNA sequencing (scRNA-seq) to construct a transcriptomic atlas of 22,774 individual cells from wild-type (WT) and Fstl1-/- lung (E18.5) samples and identified 27 cell subtypes. We observed abnormal population sizes and gene expression profiles in diverse cell subtypes in Fstl1-/- lung samples. We identified Pdgfra and Tgfbi as genetic markers specifically expressed in postnatal myofibroblasts (MyoFBs). Fstl1 deletion decreased the number of MyoFB cells and downregulated their roles in ECM organization and muscle tissue/vasculature development, partly through the TGF-β1/BMP4 signaling pathway. Our data provide a single-cell view of the cellular heterogeneity and the molecular mechanisms underlying abnormal saccular formation and atelectatic lungs in Fstl1-/- mice.

Clinical implications of circulating follistatin-like protein-1 in hemodialysis patients

Follistatin-like protein-1 (FSTL-1) is secreted glycoprotein, which regulates cardiovascular, immune and skeletal system. However, the clinical significance of circulating FSTL-1 levels remains unclear in hemodialysis patients. A total 376 hemodialysis patients were enrolled from June 2016 to March 2020. Plasma FSTL-1 level, inflammatory biomarkers, physical performance, and echocardiographic findings at baseline were examined. Plasma FSTL-1 levels were positively correlated with TNF-α and MCP-1. Handgrip strength showed weak positive correlation in male patients only, and gait speed showed no correlation with FSTL-1 levels. In multivariate linear regression analysis, FSTL-1 level was negatively associated with left ventricular ejection fraction (β =  - 0.36; p = 0.011). The cumulative event rate of the composite of CV event and death, and cumulative event rate of CV events was significantly greater in FSTL-1 tertile 3. In multivariate Cox-regression analysis, FSTL-1 tertile 3 was associated with a 1.80-fold risk for the composite of CV events and death(95% confidence interval (CI) 1.06-3.08), and a 2.28-fold risk for CV events (95% CI 1.15-4.51) after adjustment for multiple variables. In conclusion, high circulating FSTL-1 levels independently predict the composite of CV events and death, and FSTL-1 level was independently associated with left ventricular systolic dysfunction.

Role of follistatin-like 1 levels and functions in calcific aortic stenosis

Background

Calcific aortic valve disease (CAVD) is a progressive disease resulting in severe calcific aortic stenosis (AS), and there is increasing interest in the discovery of novel biomarkers to identify patients with potential future calcific AS at an early stage. This study aimed to determine whether follistatin-like 1 (FSTL1) is associated with calcific AS events and its exact role in aortic valve calcification.

Methods

A prospective observational cohort study involving 656 patients was performed to investigate the relationship between serum FSTL1 and calcific AS incidence during a follow-up of 5 years. Furthermore, we detected FSTL1 levels in valvular interstitial cells (VICs) from calcified valves and explored the effects of FSTL1 on VIC osteogenic differentiation in vitro as well as the signaling pathways involved.

Results

During a median follow-up of 5 years, lower FSTL1 levels were associated with a significantly higher risk of calcific AS events (log rank test, P = 0.007). In addition, Cox multivariable regression analyses verified the predictive value of FSTL1 after adjusting for both demographic features and laboratory confounders. Consistent with our results for serum, a lower concentration of FSTL1 was observed in calcified human valves (n = 11) and mainly colocalized with VICs. Recombinant human FSTL1 (rhFSTL1) stimulation inhibited calcium deposition, alkaline phosphatase (ALP) activity, and osteogenic gene expression partly through the downregulation of the ERK1/2 pathway.

Conclusion

Taken together, this study provides a strong rationale to consider FSTL1 as a potential therapeutic target for calcific AS.

FSTL1 promotes liver fibrosis by reprogramming macrophage function through modulating the intracellular function of PKM2

OBJECTIVE

Follistatin-like protein 1 (FSTL1) is widely recognised as a secreted glycoprotein, but its role in modulating macrophage-related inflammation during liver fibrosis has not been documented. Herein, we aimed to characterise the roles of macrophage FSTL1 in the development of liver fibrosis.

DESIGN

Expression analysis was conducted with human liver samples obtained from 33 patients with liver fibrosis and 18 individuals without fibrosis serving as controls. Myeloid-specific FSTL1-knockout (FSTL1^M-KO) mice were constructed to explore the function and mechanism of macrophage FSTL1 in 3 murine models of liver fibrosis induced by carbon tetrachloride injection, bile duct ligation or a methionine-deficient and choline-deficient diet.

RESULTS

FSTL1 expression was significantly elevated in macrophages from fibrotic livers of both humans and mice. Myeloid-specific FSTL1 deficiency effectively attenuated the progression of liver fibrosis. In FSTL1^M-KO mice, the microenvironment that developed during liver fibrosis showed relatively less inflammation, as demonstrated by attenuated infiltration of monocytes/macrophages and neutrophils and decreased expression of proinflammatory factors. FSTL1^M-KO macrophages exhibited suppressed proinflammatory M1 polarisation and nuclear factor kappa B pathway activation in vivo and in vitro. Furthermore, this study showed that, through its FK domain, FSTL1 bound directly to the pyruvate kinase M2 (PKM2). Interestingly, FSTL1 promoted PKM2 phosphorylation and nuclear translocation, reduced PKM2 ubiquitination to enhance PKM2-dependent glycolysis and increased M1 polarisation. Pharmacological activation of PKM2 (DASA-58) partially countered FSTL1-mediated glycolysis and inflammation.

CONCLUSION

Macrophage FSTL1 promotes the progression of liver fibrosis by inducing M1 polarisation and inflammation based on the intracellular PKM2 reprogramming function of macrophages.

The Expression of Follistatin-like 1 Protein Is Associated with the Activation of the EMT Program in Sjögren’s Syndrome

Background: The activation of the epithelial to mesenchymal transition (EMT) program is a pathological response of the Sjögren’s syndrome (SS) salivary glands epithelial cells (SGEC) to chronic inflammation. Follistatin-like 1 protein (FSTL1) is a secreted glycoprotein induced by transforming growth factor-β1 (TGF-β1), actively involved in the modulation of EMT. However, the role of FSTL1 in the EMT program activation in SS has not yet been investigated. Methods: TGF-β1-stimulated healthy human SGEC, SS SGEC, and SS salivary glands (SGs) biopsies were used to assess the effect of FSTL1 on the activation of the EMT program. FSTL1 gene activity was inhibited by the siRNA gene knockdown technique. Results: Here we reported that FSTL1 is up-regulated in SS SGs tissue in a correlated manner with the inflammatory grade. Blockage of FSTL1 gene expression by siRNA negatively modulates the TGF-β1-induced EMT program in vitro. We discovered that these actions were mediated through the modulation of the SMAD2/3-dependent EMT signaling pathway. Conclusions: Our data suggest that the TGF-β1-FSTL1-SMAD2/3 regulatory circuit plays a key role in the regulation of EMT in SS and targeting FSTL1 may be a strategy for the treatment of SGs EMT-dependent fibrosis.

The role of exercise-induced myokines in promoting angiogenesis

Ischemic diseases are a major cause of mortality or disability in the clinic. Surgical or medical treatment often has poor effect on patients with tissue and organ ischemia caused by diffuse stenoses. Promoting angiogenesis is undoubtedly an effective method to improve perfusion in ischemic tissues and organs. Although many animal or clinical studies tried to use stem cell transplantation, gene therapy, or cytokines to promote angiogenesis, these methods could not be widely applied in the clinic due to their inconsistent experimental results. However, exercise rehabilitation has been written into many authoritative guidelines in the treatment of ischemic diseases. The function of exercise in promoting angiogenesis relies on the regulation of blood glucose and lipids, as well as cytokines that secreted by skeletal muscle, which are termed as myokines, during exercise. Myokines, such as interleukin-6 (IL-6), chemokine ligand (CXCL) family proteins, irisin, follistatin-like protein 1 (FSTL1), and insulin-like growth factor-1 (IGF-1), have been found to be closely related to the expression and function of angiogenesis-related factors and angiogenesis in both animal and clinical experiments, suggesting that myokines may become a new molecular target to promote angiogenesis and treat ischemic diseases. The aim of this review is to show current research progress regarding the mechanism how exercise and exercise-induced myokines promote angiogenesis. In addition, the limitation and prospect of researches on the roles of exercise-induced myokines in angiogenesis are also discussed. We hope this review could provide theoretical basis for the future mechanism studies and the development of new strategies for treating ischemic diseases.

Endogenous Follistatin-like 1 guarantees the immunomodulatory properties of mesenchymal stem cells during liver fibrotic therapy

Background

Mesenchymal stem cell (MSC) therapy has been shown to be a promising option for liver fibrosis treatment. However, critical factors affecting the efficacy of MSC therapy for liver fibrosis remain unknown. Follistatin-like 1 (FSTL1), a TGF-β-induced matricellular protein, is documented as an intrinsic regulator of proliferation and differentiation in MSCs. In the present study, we characterized the potential role of FSTL1 in MSC-based anti-fibrotic therapy and further elucidated the mechanisms underlying its action.

Methods

Human umbilical cord-derived MSCs were characterized by flow cytometry. FSTL1^low MSCs were achieved by FSTL1 siRNA. Migration capacity was evaluated by wound-healing and transwell assay. A murine liver fibrotic model was created by carbon tetrachloride (CCl₄) injection, while control MSCs or FSTL1^low MSC were transplanted via intravenous injection 12 weeks post CCl₄ injection. Histopathology, liver function, fibrosis degree, and inflammation were analysed thereafter. Inflammatory cell infiltration was evaluated by flow cytometry after hepatic nonparenchymal cell isolation. An MSC-macrophage co-culture system was constructed to further confirm the role of FSTL1 in the immunosuppressive capacity of MSCs. RNA sequencing was used to screen target genes of FSTL1.

Results

FSTL1^low MSCs had comparable gene expression for surface markers to wildtype but limited differentiation and migration capacity. FSTL1^low MSCs failed to alleviate CCl₄-induced hepatic fibrosis in a mouse model. Our data indicated that FSTL1 is essential for the immunosuppressive action of MSCs on inflammatory macrophages during liver fibrotic therapy. FSTL1 silencing attenuated this capacity by inhibiting the downstream JAK/STAT1/IDO pathway.

Conclusions

Our data suggest that FSTL1 facilitates the immunosuppression of MSCs on macrophages and that guarantee the anti-fibrotic effect of MSCs in liver fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03042-4.

CircPTTG1IP knockdown suppresses rheumatoid arthritis progression by targeting miR-431-5p/FSTL1 axis

BACKGROUND

It is observed that circular RNA (circRNA) PTTG1 interacting protein (circPTTG1IP) level is notably up-regulated in rheumatoid arthritis (RA) patients by previous study. However, its precise role and working mechanism in RA pathology remain to be clarified.

METHODS AND RESULTS

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were carried out to examine RNA and protein expression. Cell proliferation was analyzed by colony formation assay and 5-Ethynyl-2'-deoxyuridine (EdU) assay. Cell motility was assessed by transwell assays and wound healing assay. Flow cytometry (FCM) analysis was performed to assess cell apoptosis rate. Dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA-pull down assays were conducted to confirm the interaction between microRNA-431-5p (miR-431-5p) and circPTTG1IP or follistatin like 1 (FSTL1). CircPTTG1IP expression was up-regulated in the synovial tissues of RA patients and RA patients-derived fibroblast-like synoviocytes (RA-FLS). CircPTTG1IP absence suppressed the proliferation, migration, and invasion and induced the apoptosis of RA-FLS. CircPTTG1IP negatively regulated the expression of miR-431-5p by directly binding to it in RA-FLS. CircPTTG1IP interference-mediated effects in RA-FLS were largely counteracted by the silence of miR-431-5p. miR-431-5p directly interacted with the 3' untranslated region (3'UTR) of FSTL1. FSTL1 overexpression largely overturned miR-431-5p accumulation-mediated effects in RA-FLS. CircPTTG1IP positively regulated FSTL1 expression by sponging miR-431-5p in RA-FLS.

CONCLUSION

CircPTTG1IP absence suppressed RA progression through mediating miR-431-5p/FSTL1 signaling cascade.

Effects of Moderate Intensity Aerobic Exercise to FSTL-1 Regulation in Atherosclerosis: A Systematic Review

Moderate intensity exercise is considered as a primary step to prevent coronary artery diseases (CADs) by stimulated FSTL-1 secretion as a novel myokines to improve endothelial cell function, prevent arterial stiffness, or vascular inflammation. This review aims to provide the current evident role of FSTL-1 as a novel myokine secreted during exercise to prevent atherosclerosis progression. A systematic review using databases from (PubMed), ScienceDirect, and The Cochrane Library, was conducted up to October 2021 to identify all the eligible experimental and observational studies that assess how moderate intensity exercises stimulate FSTL-1 secretion to prevent atherosclerosis. Results were described through narrative synthesis of the evidence. From 84 retrieved references, 15 studies met the inclusion criteria and were included in this review. The overall results suggest that exercise or physical activity can stimulate myokines secretion, especially in FSTL-1. FSTL-1 is a myokine or adipokine that plays a potential role in preventing atherosclerosis by various mechanisms such as via improvement of endothelial functions, suppression of smooth muscle cells (SMCs) proliferation, and reduction of arterial thickening. FSTL-1 is a relatively new and less known myokine, but probably holds a key role in assessing how moderate intensity aerobic exercise prevents atherosclerosis progression by preventing endothelial dysfunction, arterial stiffness, or vascular inflammation.

Follistatin-like 1 (FSTL1) interacts with Wnt ligands and Frizzled receptors to enhance Wnt/β-catenin signaling in obstructed kidneys in vivo

Follistatin (FS)-like 1 (FSTL1) is a member of the FS-SPARC (secreted protein, acidic and rich in cysteine) family of secreted and extracellular matrix proteins. The functions of FSTL1 have been studied in heart and lung injury as well as in wound healing; however, the role of FSTL1 in the kidney is largely unknown. Here, we show using single-cell RNA-Seq that Fstl1 was enriched in stromal cells in obstructed mouse kidneys. In addition, immunofluorescence demonstrated that FSTL1 expression was induced in fibroblasts during kidney fibrogenesis in mice and human patients. We demonstrate that FSTL1 overexpression increased renal fibrosis and activated the Wnt/β-catenin signaling pathway, known to promote kidney fibrosis, but not the transforming growth factor β (TGF-β), Notch, Hedgehog, or Yes-associated protein (YAP) signaling pathways in obstructed mouse kidneys, whereas inhibition of FSTL1 lowered Wnt/β-catenin signaling. Importantly, we show that FSTL1 interacted with Wnt ligands and the Frizzled (FZD) receptors but not the coreceptor lipoprotein receptor-related protein 6 (LRP6). Specifically, we found FSTL1 interacted with Wnt3a through its extracellular calcium-binding (EC) domain and von Willebrand factor type C-like (VWC) domain, and with FZD4 through its EC domain. Furthermore, we show that FSTL1 increased the association of Wnt3a with FZD4 and promoted Wnt/β-catenin signaling and fibrogenesis. The EC domain interacting with both Wnt3a and FZD4 also enhanced Wnt3a signaling. Therefore, we conclude that FSTL1 is a novel extracellular enhancer of the Wnt/β-catenin pathway.

Screening of candidate genes associated with high titer production of oncolytic measles virus based on systems biology approach

The number of viral particles required for oncolytic activity of measles virus (MV) can be more than a million times greater than the reported amount for vaccination. The aim of the current study is to find potential genes and signaling pathways that may be involved in the high-titer production of MV. In this study, a systems biology approach was considered including collection of gene expression profiles from the Gene Expression Omnibus (GEO) database, obtaining differentially expressed genes (DEGs), performing gene ontology, functional enrichment analyses, and topological analyses on the protein-protein interaction (PPI) network. Then, to validate the in-silico data, total RNA was isolated from five cell lines, and full-length cDNA from template RNA was synthesized. Subsequently, quantitative reverse transcription-PCR (RT-qPCR) was employed. We identified five hub genes, including RAC1, HSP90AA1, DNM1, LTBP1, and FSTL1 associated with the enhancement in MV titer. Pathway analysis indicated enrichment in PI3K-Akt signaling pathway, axon guidance, proteoglycans in cancer, regulation of actin cytoskeleton, focal adhesion, and calcium signaling pathways. Upon verification by RT-qPCR, the relative expression of candidate genes was generally consistent with our bioinformatics analysis. Hub genes and signaling pathways may be involved in understanding the pathological mechanisms by which measles virus manipulates host factors in order to facilitate its replication. RAC1, HSP90AA1, DNM1, LTBP1, and FSTL1 genes, in combination with genetic engineering techniques, will allow the direct design of high-throughput cell lines to answer the required amounts for the oncolytic activity of MV.

Hsa_circ_0058129 regulates papillary thyroid cancer development via miR‐873‐5p/follistatin‐like 1 axis

Background

Papillary thyroid cancer (PTC) is an endocrine malignancy with a high incidence. Circular RNAs (circRNAs) participate in regulating PTC. Here, we analyzed the role of hsa_circ_0058129 (circ_0058129) in PTC.

Methods

The expression of circ_0058129, fibronectin 1 (FN1) mRNA, microRNA‐873‐5p (miR‐873‐5p), and follistatin‐like 1 (FSTL1) was detected by qRT‐PCR and western blot. Cell proliferation was analyzed by CCK‐8, EdU, and flow cytometry analysis assays. Cell migration and invasion were evaluated by Transwell assay. The targeting relationship of miR‐873‐5p and circ_0058129 or FSTL1 was identified through dual‐luciferase reporter assay, RIP assay, and RNA pull‐down assay. Xenograft mouse model assay was implemented to determine the effect of circ_0058129 on tumor formation in vivo.

Results

The circ_0058129 and FSTL1 abundances were increased, while the miR‐873‐5p content was decreased in PTC tissues and cells compared with control groups. Circ_0058129 shortage inhibited PTC cell proliferation, migration, and invasion. Moreover, miR‐873‐5p repressed PTC cell malignancy by binding to FSTL1. Circ_0058129 targeted miR‐873‐5p to regulate FSTL1.

Conclusion

Circ_0058129 expedited PTC progression through the miR‐873‐5p/FSTL1 pathway.

Changes of FSTL1 and MMP-9 levels in patients with acute cerebral infarction and its relationship with hemorrhagic transformation

BACKGROUND

hemorrhagic transformation is a serious complication of acute ischemic stroke, which may lead to poor prognosis and delayed use of anticoagulant therapy.

METHODS

125 patients with cerebral infarction from December 2019 to December 2020 in the Second Affiliated Hospital of Zhejiang University were selected. All patients did not receive intravascular therapy, intravenous thrombolysis and other reperfusion treatment; and the relevant laboratory data were collected within 24 h after admission. At the same time, 15 healthy subjects were selected as the research objects for prospective analysis. Hemorrhagic transformation (HT) was defined as a condition in which computed tomography (CT) did not indicate bleeding at admission, but follow-up magnetic resonance imaging (MRI) or CT showed hemorrhage. The patients were divided into HT group (n = 50) and non-HT group (n = 75) according to whether there was HT after admission. The concentrations of FSTL1 and MMP-9 in peripheral blood of the two groups were detected.

RESULTS

The concentrations of FSTL1 and MMP-9 in acute cerebral infarction (ACI) group were significantly higher than those in control group. However the HT group had a higher concentration of FSTL1 and MMP-9 than the non-HT group. The serum FSTL1 and MMP-9 were independent risk factors for hemorrhagic transformation. The area under the ROC curve of FSTL1 and MMP-9 in diagnosis of HT was 0.809 and 0.856 respectively, and their combined value was 0.923.

CONCLUSION

The high levels of FSTL1 and MMP-9 had strong correlation with HT in ACI patients.

Local genetic variation of inflammatory bowel disease in Basque population and its effect in risk prediction

Inflammatory bowel disease (IBD) is characterised by chronic inflammation of the gastrointestinal tract. Although its aetiology remains unknown, environmental and genetic factors are involved in its development. Regarding genetics, more than 200 loci have been associated with IBD but the transferability of those signals to the Basque population living in Northern Spain, a population with distinctive genetic background, remains unknown. We have analysed 5,411,568 SNPs in 498 IBD cases and 935 controls from the Basque population. We found 33 suggestive loci (p < 5 × 10-6) in IBD and its subtypes, namely Crohn's Disease (CD) and Ulcerative Colitis (UC), detecting a genome-wide significant locus located in HLA region in patients with UC. Those loci contain previously associated genes with IBD (IL23R, JAK2 or HLA genes) and new genes that could be involved in its development (AGT, BZW2 or FSTL1). The overall genetic correlation between European populations and Basque population was high in IBD and CD, while in UC was lower. Finally, the use of genetic risk scores based on previous GWAS findings reached area under the curves > 0.68. In conclusion, we report on the genetic architecture of IBD in the Basque population, and explore the performance of European-descent genetic risk scores in this population.

Myokines: Novel therapeutic targets for diabetic nephropathy

With the increasing incidence of diabetic nephropathy (DN), there is an urgent need to find effective DN preventive and therapeutic modalities. It is widely believed that effective exercise is good for health. However, the beneficial role of exercise in kidney disease, especially in DN, and the underlying molecular mechanisms have rarely been reported. Muscle is not only an important motor organ but also an important endocrine organ, secreting a group of proteins called "myokines" into the blood circulation. Circulating myokines then move to various target organs to play different biological roles. In this review, we summarize the currently known myokines and the progress in research relating them to DN and discuss its potential as a therapeutic target for DN.

Association between Plasma Follistatin-like Protein 1 Levels and the Presence and Severity of Coronary Artery Disease

Follistatin-like protein 1 (FSTL1) is a secreted glycoprotein known for its role in inflammation. However, plasma FSTL1 levels in patients with coronary artery disease (CAD) have not been fully elucidated. Thus, in this study, we investigated the plasma FSTL1 levels of 350 patients who underwent elective coronary angiography. The severity of CAD was represented as the numbers of > 50% stenotic vessels and segments and the severity score. CAD was detected in 196 patients, of whom 84 had 1-vessel disease (1-VD), 62 had 2-VD, and 50 had 3-VD. Plasma high-sensitivity C-reactive protein (hsCRP) levels were higher in patients with CAD than in those without CAD (median 0.56 versus 0.44 mg/L, P < 0.01). Notably, plasma FSTL1 levels were higher in patients with CAD than in those without CAD (median 4.05 versus 3.47 ng/mL, P < 0.02). A stepwise increase in FSTL1 levels was found depending on the number of > 50% stenotic vessels: 3.47 in CAD (-), 3.74 in 1-VD, 4.42 in 2-VD, and 4.65 ng/mL in 3-VD (P < 0.05). FSTL1 levels also correlated with the number of > 50% stenotic segments and the severity score (r = 0.14 and r = 0.15, respectively, P < 0.005) and hsCRP levels (r = 0.10, P < 0.05). In the multivariate analysis, FSTL1 levels were an independent factor associated with CAD. The odds ratio for CAD was 1.61 (95% CI = 1.01-2.58) for high FSTL1 level of > 3.6 ng/mL (P < 0.05). In conclusion, plasma FSTL1 levels in patients with CAD were found to be high and associated with the presence and severity of CAD, thus, suggesting that FSTL1 may play a role in the progression of coronary atherosclerosis.

Follistatin-Like Proteins: Structure, Functions and Biomedical Importance

Main forms of cellular signal transmission are known to be autocrine and paracrine signaling. Several cells secrete messengers called autocrine or paracrine agents that can bind the corresponding receptors on the surface of the cells themselves or their microenvironment. Follistatin and follistatin-like proteins can be called one of the most important bifunctional messengers capable of displaying both autocrine and paracrine activity. Whilst they are not as diverse as protein hormones or protein kinases, there are only five types of proteins. However, unlike protein kinases, there are no minor proteins among them; each follistatin-like protein performs an important physiological function. These proteins are involved in a variety of signaling pathways and biological processes, having the ability to bind to receptors such as DIP2A, TLR4, BMP and some others. The activation or experimentally induced knockout of the protein-coding genes often leads to fatal consequences for individual cells and the whole body as follistatin-like proteins indirectly regulate the cell cycle, tissue differentiation, metabolic pathways, and participate in the transmission chains of the pro-inflammatory intracellular signal. Abnormal course of these processes can cause the development of oncology or apoptosis, programmed cell death. There is still no comprehensive understanding of the spectrum of mechanisms of action of follistatin-like proteins, so the systematization and study of their cellular functions and regulation is an important direction of modern molecular and cell biology. Therefore, this review focuses on follistatin-related proteins that affect multiple targets and have direct or indirect effects on cellular signaling pathways, as well as to characterize the directions of their practical application in the field of biomedicine.

Menstrual fluid endometrial stem/progenitor cell and supernatant protein content: cyclical variation and indicative range

STUDY QUESTION

Does natural variation exist in the endometrial stem/progenitor cell and protein composition of menstrual fluid across menstrual cycles in women?

SUMMARY ANSWER

Limited variation exists in the percentage of some endometrial stem/progenitor cell types and abundance of selected proteins in menstrual fluid within and between a cohort of women.

WHAT IS KNOWN ALREADY

Menstrual fluid is a readily available biofluid that can represent the endometrial environment, containing endometrial stem/progenitor cells and protein factors. It is unknown whether there is natural variation in the cellular and protein content across menstrual cycles of individual women, which has significant implications for the use of menstrual fluid in research and clinical applications.

STUDY DESIGN, SIZE, DURATION

Menstrual fluid was collected from 11 non-pregnant females with regular menstrual cycles. Participants had not used hormonal medications in the previous 3 months. Participants collected menstrual fluid samples from up to five cycles using a silicone menstrual cup worn on Day 2 of menstrual bleeding.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Menstrual fluid samples were centrifuged to separate soluble proteins and cells. Cells were depleted of red blood cells and CD45+ leucocytes. Menstrual fluid-derived endometrial stem/progenitor cells were characterized using multicolour flow cytometry including markers for endometrial stem/progenitor cells N-cadherin (NCAD) and stage-specific embryonic antigen-1 (SSEA-1) (for endometrial epithelial progenitor cells; eEPC), and sushi domain containing-2 (SUSD2) (for endometrial mesenchymal stem cells; eMSC). The clonogenicity of menstrual fluid-derived endometrial cells was assessed using colony forming unit assays. Menstrual fluid supernatant was analyzed using a custom magnetic Luminex assay.

MAIN RESULTS AND THE ROLE OF CHANCE

Endometrial stem/progenitor cells are shed in menstrual fluid and demonstrate clonogenic properties. The intraparticipant agreement for SUSD2+ menstrual fluid-derived eMSC (MF-eMSC), SSEA-1+ and NCAD+SSEA-1+ MF-eEPC, and stromal clonogenicity were moderate-good (intraclass correlation; ICC: 0.75, 0.56, 0.54 and 0.52, respectively), indicating limited variability across menstrual cycles. Endometrial inflammatory and repair proteins were detectable in menstrual fluid supernatant, with five of eight (63%) factors demonstrating moderate intraparticipant agreement (secretory leukocyte protein inhibitor (SLPI), lipocalin-2 (NGAL), lactoferrin, follistatin-like 1 (FSTL1), human epididymis protein-4 (HE4); ICC ranges: 0.57-0.69). Interparticipant variation was limited for healthy participants, with the exception of key outliers of which some had self-reported menstrual pathologies.

LARGE SCALE DATA

N/A. There are no OMICS or other data sets relevant to this study.

LIMITATIONS, REASONS FOR CAUTION

The main limitations to this research relate to the difficulty of obtaining menstrual fluid samples across multiple menstrual cycles in a consistent manner. Several participants could only donate across <3 cycles and the duration of wearing the menstrual cup varied between 4 and 6 h within and between women. Due to the limited sample size used in this study, wider studies involving multiple consecutive menstrual cycles and a larger cohort of women will be required to fully determine the normal range of endometrial stem/progenitor cell and supernatant protein content of menstrual fluid. Possibility for selection bias and true representation of the population of women should also be considered.

WIDER IMPLICATIONS OF THE FINDINGS

Menstrual fluid is a reliable source of endometrial stem/progenitor cells and related endometrial proteins with diagnostic potential. The present study indicates that a single menstrual sample may be sufficient in characterizing a variety of cellular and protein parameters across women's menstrual cycles. The results also demonstrate the potential of menstrual fluid for identifying endometrial and menstrual abnormalities in both research and clinical settings as a non-invasive method for assessing endometrial health.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the Australian National Health and Medical Research Council to C.E.G. (Senior Research Fellowship 1024298 and Investigator Fellowship 1173882) and to J.E. (project grant 1047756), the Monash IVF Research Foundation to C.E.G. and the Victorian Government's Operational Infrastructure Support Program. K.A.W., M.L.D.-T., S.G.S. and J.E. declare no conflicts of interest. C.E.G. reports grants from NHMRC, during the conduct of the study; grants from EndoFound USA, grants from Ferring Research Innovation, grants from United States Department of Defence, grants from Clue-Utopia Research Foundation, outside the submitted work. CEF reports grants from EndoFound USA, grants from Clue-Utopia Research Foundation, outside the submitted work.

FSTL1 aggravates OVA-induced inflammatory responses by activating the NLRP3/IL-1β signaling pathway in mice and macrophages

OBJECTIVE

Asthma, a well-known disease with high morbidity, is characterized by chronic airway inflammation. However, the allergic inflammation mechanisms of follistatin-like protein 1 (FSTL1) have not been elucidated. This study aims to investigate the effects of FSTL1 in ovalbumin (OVA)-induced mice and macrophages on nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3)/interleukin-1β (IL-1β) signaling pathway.

METHODS

Mice were randomly divided into control-WT, OVA-WT, control-Fstl1±, OVA-Fstl1±. Histological changes were assessed by HE and PAS staining. The protein levels of Muc-5AC, FSTL1, NLRP3, and IL-1β in lung tissue were detected by immunohistochemistry and ELISA. The bronchoalveolar lavage fluid (BALF) in mice and human serum samples were detected by ELISA. Then, mice were grouped into control, FSTL1, MCC950 + FSTL1 to further investigate the relationship between FSTL1 and NLRP3/IL-1β. Alveolar macrophage cells (MH-S cells) were separated into control, OVA, FSTL1, OVA + FSTL1, OVA + siNC, OVA + siFSTL1, MCC950, and FSTL1 + MCC950 groups to explore the effect of FSTL1 on the NLRP3/IL-1β signaling. The protein expression of NLRP3 and IL-1β in MH-S cells was detected by Western blot analysis.

RESULTS

The present results uncovered that Fstl1± significantly ameliorated OVA-induced Muc-5AC production and mucus hypersecretion. Fstl1± was also found to decrease the production of inflammatory cytokines and inflammatory cell infiltration in OVA-induced asthmatic mice. Meanwhile, the serum concentrations of FSTL1 and IL-1β were higher in  asthma subjects than the health subjects, and Fstl1± ameliorated the production of NLRP3 and IL-1β in OVA-induced asthmatic mice. Furthermore, mice by injected FSTL1 substantially stimulated the expression of NLRP3 and IL-1β, while pretreatment with MCC950 in mice significantly weakened the production of NLRP3 and IL-1β induced by injection FSTL1. Pretreatment with siFSTL1 or MCC950 significantly reduced the production of NLRP3 and IL-1β induced by OVA or FSTL1 in MH-S cells.

CONCLUSIONS

The study results showed that FSTL1 played an important role in allergic airway inflammation by activating NLRP3/IL-1β. Hence, inhibition FSTL1 could be applied as a therapeutic agent against asthma.

Effect of Fas/FasL signaling pathway activation in trophoblasts on recurrent spontaneous abortion

OBJECTIVE

To investigate the expression of Fas/FasL in human villous trophoblast cell HTR8-S/Vneo of patients with recurrent spontaneous abortion (RSA), and to explore the related function and molecular mechanism of Fas/FasL signaling pathway.

METHODS

The expression levels of FasL, Fas, and E-cadherin in the villous tissues of patients with RSA and those with artificial abortion in normal pregnancy (Normal) were detected by Western blot. CCK-8, flow cytometry, and wound healing were used to detect cell proliferation, apoptosis, and reactive oxygen species (ROS) level, and cell migration ability. Quantitative reverse transcription PCR (RT-qPCR) and Western blot were used to detect the expression of mRNA and protein of Notch1, FasL, Fas, E-cadherin, PKC, Hesl, sFlt-1, VEGF.

RESULTS

Compared with normal group, the protein expression of FasL, Fas, and E-cadherin in villous tissues of RSA group were increased. HTR-8/SVneo cells in the H/R group had decreased proliferation and migration, increased apoptosis, and up-regulated ROS level compared with the Control group. The activation of Fas/FasL signaling pathway promoted HTR-8/SVneo cell injury in H/R group compared with the Fas/FasL+H/R group. Further RT-qPCR and Western blot experiments revealed that the mRNA and protein expression of Notch1, PKC, and Hesl were decreased in H/R group compared with Control group, while the mRNA and protein expression levels of E-cadherin, sFlt-1, and VEGF were significantly increased.

CONCLUSION

The activation of Fas/FasL signaling pathway promotes trophoblast apoptosis induced by oxidative stress. This molecular mechanism relates to the inhibition of Notch1 signaling pathway activation, and the up-regulation of E-cadherin, sFlt-1, and VEGF expression.

Follistatin-like protein 1 functions as a potential target of gene therapy in proliferative diabetic retinopathy

The degree of retinal fibrosis increased in proliferative diabetic retinopathy (PDR) patients after administration of anti-Vascular endothelial growth factor (VEGF) injections. Previous studies showed that the balance between connective tissue growth factor (CTGF) and VEGF plays an important role. Therefore, in a high-glucose state, an anti-VEGF and CTGFshRNA dual-target model was used to simulate clinical dual-target treatment in PDR patients, and RNA sequencing (RNA-Seq) technology was used for whole transcriptome sequencing. A hypoxia model was constructed to verify the sequencing results at the cellular level, and the vitreous humor and proliferative membranes were collected from patients for verification. All sequencing results included Follistatin-like protein 1 (FSTL1) and extracellular matrix (ECM) receptor pathway, indicated that anti-VEGF therapy may upregulate FSTL1 expression, while dual-target treatment downregulated FSTL1. Thus, we further studied the function of FSTL1 on the expression of VEGF and ECM factors by both overexpressing and silencing FSTL1. In conclusion, our results suggested that FSTL1 may be involved in the pathogenesis of PDR and is related to fibrosis caused by the anti-VEGF treatment, thus providing a potential target for gene therapy in PDR.

Follistatin-like 1 deficiency impairs T cell development to promote lung metastasis of triple negative breast cancer

Our study aims to detect the underlying mechanism of the suppressive effect of Follistatin-like 1 (FSTL1) on lung metastasis of triple negative breast cancer (TNBC). We found that FSTL1 had no effect on the proliferation and metastasis of 4T1 cells in vitro, while in the tumor-bearing Fstl1 heterozygous (Fstl1^+/-) mice, the number of anti-tumor T lymphocytes in the lung was significantly reduced with the increase in lung metastasis. Impaired development of T cells can cause dysfunction of adaptive immune system, which promotes cancer metastasis. Therefore the effect of FSTL1 on T cell development was further investigated. Lower population of T cells in periphery and decreased proliferation of CD4^- CD8^- double negative (DN) thymocytes and impairment development of T cells were found in Fstl1^+/- mice. Furthermore, high expression of FSTL1 in medullary thymus epithelial (mTEC) cells and decreased mRNA expression of inducible costimulator on activated T-cell ligand (Icosl) in mTEC^{sh Fstl1} were detected. Combining other studies that the generation of ICOSL by mTEC cells promotes CD4⁺ single positive (SP) thymocytes to produce IL-2, which promotes T cell development. Our results indicate FSTL1 deficiency in mTEC cells impairs T cell development to promote the lung metastasis of TNBC.

FSTL1 aggravates cigarette smoke-induced airway inflammation and airway remodeling by regulating autophagy

BACKGROUND

Cigarette smoke (CS) is a major risk factor for Chronic Obstructive Pulmonary Disease (COPD). Follistatin-like protein 1 (FSTL1), a critical factor during embryogenesis particularly in respiratory lung development, is a novel mediator related to inflammation and tissue remodeling. We tried to investigate the role of FSTL1 in CS-induced autophagy dysregulation, airway inflammation and remodeling.

METHODS

Serum and lung specimens were obtained from COPD patients and controls. Adult female wild-type (WT) mice, FSTL1^± mice and FSTL1^flox/+ mice were exposed to room air or chronic CS. Additionally, 3-methyladenine (3-MA), an inhibitor of autophagy, was applied in CS-exposed WT mice. The lung tissues and serum from patients and murine models were tested for FSTL1 and autophagy-associated protein expression by ELISA, western blotting and immunohistochemical. Autophagosome were observed using electron microscope technology. LTB4, IL-8 and TNF-α in bronchoalveolar lavage fluid of mice were examined using ELISA. Airway remodeling and lung function were also assessed.

RESULTS

Both FSTL1 and autophagy biomarkers increased in COPD patients and CS-exposed WT mice. Autophagy activation was upregulated in CS-exposed mice accompanied by airway remodeling and airway inflammation. FSTL1^± mice showed a lower level of CS-induced autophagy compared with the control mice. FSTL1^± mice can also resist CS-induced inflammatory response, airway remodeling and impaired lung function. CS-exposed WT mice with 3-MA pretreatment have a similar manifestation with CS-exposed FSTL1^± mice.

CONCLUSIONS

FSTL1 promotes CS-induced COPD by modulating autophagy, therefore targeting FSTL1 and autophagy may shed light on treating cigarette smoke-induced COPD.

FSTL1 increases cisplatin sensitivity in epithelial ovarian cancer cells by inhibition of NF-κB pathway

OBJECTIVE

To investigate the effects of FSTL1-mediated NF-κB signaling pathway on cisplatin (DDP) sensitivity of EOC cells.

METHODS

FSTL1 expression was determined in epithelial ovarian cancer (EOC) tissues and corresponding adjacent tissues using immunohistochemistry. SKOV3 and SKOV3/DDP cells were transfected and grouped into Blank, Vector, and FSTL1 groups. The sensitivity and 50% inhibitory concentration (IC50) of cells treated with different concentrations of DDP were detected by MTT assay. SKOV3/DDP cells were treated with 20 μM DDP, followed by evaluation of cell proliferation, cell apoptosis and determination of NF-κB pathway-related proteins while SKOV3 cells without.

RESULTS

FSTL1 expression in EOC tissues and cells was significantly down-regulated, especially decreased in DDP-resistant EOC cells SKOV3/DDP. In SKOV3 cells and SKOV3/DDP cells, the cell viability was reduced and the DDP sensitivity was improved with the decreased IC50 after over-expressing FSTL1. Compared with Blank group, FSTL1 group had declined number of SKOV3 cell colonies and increased cell apoptosis, with obvious up-regulations of FSTL1, Bax/Bcl-2 and cleaved caspase-3 expression and the down-regulations of p-IκBα, p-p65 and survivin expression. Combination of up-regulation of FSTL1 and DDP treatment can also effectively reduce cell colony forming, increase cell apoptosis, and inhibit NF-κB pathway activity of SKOV3/DDP cells. Moreover, this combination can also significantly suppress the growth of subcutaneous xenograft tumors in nude mice.

CONCLUSION

FSTL1 may inhibit NF-κB signaling pathway to suppress the growth and promote the apoptosis of epithelial ovarian cancer cells, and thereby enhancing its DDP sensitivity.

Development of Cancer in Patients With Heart Failure: How Systemic Inflammation Can Lay the Groundwork

In the last decade, cardiologists and oncologists have provided clinical and experimental evidence that cancer, and not only chemotherapeutic agents, can cause detrimental effects on heart structure and function, a consequence that has serious clinical implications for patient management. In parallel, the intriguing idea that heart failure (HF) may be an oncogenic condition has also received growing attention. A number of epidemiological and clinical studies have reported that patients with HF have a higher risk of developing cancer. Chronic low-grade systemic inflammation has been proposed as a major pathophysiological process linking the failing heart to the multi-step process of carcinogenesis. According to this view, pro-inflammatory mediators secreted by the damaged heart generate a favorable milieu that promotes tumor development and accelerates malignant transformation. HF-associated inflammation synergizes with tumor-associated inflammation, so that over time it is no longer possible to distinguish the effects of one or the other. Experimental studies have just begun to search for the molecular effectors of this process, with the ultimate goal that of identifying mechanisms suitable for anti-cancer target therapy to reduce the risk of incident cancer in patients already affected by HF. In this review we critically discuss strengths and limitations of clinical and experimental studies that support a causal relationship between HF and cancer, and focus on HF-associated inflammation, cardiokines and their endocrine functions linking one and the other disease.

Myokines in treatment-naïve patients with cancer-associated cachexia

Cancer-associated cachexia is a complex metabolic syndrome characterized by weight loss and systemic inflammation. Muscle loss and fatty infiltration into muscle are associated with poor prognosis in cancer patients. Skeletal muscle secretes myokines, factors with autocrine, paracrine and/or endocrine action, which may be modified by or play a role in cachexia. This study examined myokine content in the plasma, skeletal muscle and tumor homogenates from treatment-naïve patients with gastric or colorectal stages I-IV cancer with cachexia (CC, N = 62), or not (weight stable cancer, WSC, N = 32). Myostatin, interleukin (IL) 15, follistatin-like protein 1 (FSTL-1), fatty acid binding protein 3 (FABP3), irisin and brain-derived neurotrophic factor (BDNF) protein content in samples was measured with Multiplex technology; body composition and muscle lipid infiltration were evaluated in computed tomography, and quantification of triacylglycerol (TAG) in the skeletal muscle. Cachectic patients presented lower muscle FSTL-1 expression (p = 0.047), higher FABP3 plasma content (p = 0.0301) and higher tumor tissue expression of FABP3 (p = 0.0182), IL-15 (p = 0.007) and irisin (p = 0.0110), compared to WSC. Neither muscle TAG content, nor muscle attenuation were different between weight stable and cachectic patients. Lumbar adipose tissue (AT) index, visceral AT index and subcutaneous AT index were lower in CC (p = 0.0149, p = 0.0455 and p = 0.0087, respectively), who also presented lower muscularity in the cohort (69.2% of patients; p = 0.0301), compared to WSC. The results indicate the myokine profile in skeletal muscle, plasma and tumor is impacted by cachexia. These findings show that myokines eventually affecting muscle wasting may not solely derive from the muscle itself (as the tumor also may contribute to the systemic scenario), and put forward new perspectives on cachexia treatment targeting myokines and associated receptors and pathways.

Targeting FSTL1 for Multiple Fibrotic and Systemic Autoimmune Diseases

Follistatin-like 1 (FSTL1) is a matricellular protein that is upregulated during development and disease, including idiopathic pulmonary fibrosis (IPF), keloid, and arthritis. The profibrotic and pro-inflammatory roles of FSTL1 have been intensively studied during the last several years, as well as in this report. We screened and identified epitope-specific monoclonal neutralizing antibodies (nAbs) to functionally block FSTL1. FSTL1 nAbs attenuated bleomycin-induced pulmonary and dermal fibrosis in vivo and transforming growth factor (TGF)-β1-induced dermal fibrosis ex vivo in human skin. In addition, FSTL1 nAbs significantly reduced existing lung fibrosis and skin fibrosis in experimental models. FSTL1 nAbs exerted their potent antifibrotic effects via reduced TGF-β1 responsiveness and subsequent myofibroblast activation and extracellular matrix production. We also observed that FSTL1 nAbs attenuated the severity of collagen-induced arthritis in mice, which was accompanied by reduced inflammatory responses in vitro. Our findings suggest that FSTL1 nAbs are a promising new therapeutic strategy for the treatment of multiple organ fibrosis and systemic autoimmune diseases.

The Follistatin-like Protein 1 Pathway Is Important for Maintaining Healthy Articular Cartilage

OBJECTIVE

We sought to determine whether follistatin-like protein 1 (FSTL1), a protein produced by articular chondrocytes, promotes healthy articular cartilage and prevents chondrocytes from undergoing terminal differentiation to hypertrophic cells.

METHODS

In vitro experiments were performed with immortalized human articular chondrocytes. The cells were transduced with a lentivirus encoding human FSTL1 small hairpin RNA or with an adenovirus encoding FSTL1. A quantitative polymerase chain reaction was used for gene expression analysis. Protein expression was assessed by Western blotting. Co-immunoprecipitation was used to identify interacting partners of FSTL1. FSTL1 expression in human articular cartilage was analyzed using confocal microscopy.

RESULTS

Downregulation of FSTL1 expression in transforming growth factor β (TGFβ)-stimulated chondrocyte pellet cultures led to chondrocyte terminal differentiation characterized by poor production of cartilage extracellular matrix and altered expression of genes and proteins involved in cartilage homeostasis, including MMP13, COL10A1, RUNX2, COL2A1, ACAN, Sox9, and phospho-Smad3. We also showed that FSTL1 interacts with TGFβ receptor proteins, Alk1 and endoglin, suggesting a potential mechanism for its effects on chondrocytes. Transduction of chondrocytes with an FSTL1 transgene increased COL2A1 expression, whereas it did not affect MMP13 expression. FSTL1 protein expression was decreased in human osteoarthritic cartilage in situ.

CONCLUSION

Our data suggest that FSTL1 plays an important role in maintaining healthy articular cartilage and the FSTL1 pathway may represent a therapeutic target for degenerative diseases of cartilage.

[Study of the influence of etoxidol on expression of follistatin-like protein-1 (FSTL-1) in myocardium after experimental infarction in rats]

In heart attack, FSTL-1 is actively secreted by cardiomyocytes, accelerates growth of heart myofibrils and stimulates of vascular endothelial growth factor expression. The aim of this work was to investigate the effect of Etoxidol on synthesis of FSTL-1 in rats after myocardial infarction. The experiments were performed on Wistar rats weighing 250-350 g with simulated myocardial infarction or intact (group 5). Animals of control groups (groups 1, 2) were treated with saline for 7 and 14 days; Ethoxidol (24 mg/kg) was injected to animals of experimental groups (group 3, 4) (the daily dose was 6.36 mg/animal) for 6 or 14 days. The injection volume was 0.2 ml. At the beginning and at the end of the study plasma concentrations of FSTL-1 were determined by the ELISA method. Myocardial FSTL-1 gene expression was determined by real-time PCR. At the end of the experiments, the hearts were also used for histochemical analysis. To determine the size of the scar formed after the modeled heart attack, we used the classic Mallory staining method. The results show that the development of experimental acute myocardial infarction is accompanied by a significant increase in FSTL-1 expression in the heart, which was detected on the 7th day and stored increased by 14 days after a heart attack. After therapy with Ethoxidol, a tendency to a decrease in the expression of FSTL-1 by the 14th day was observed; it coincided with the dynamics of the plasma protein FSTL-1 level. It can be assumed that the downregulation trend in the FSTL-1 expression is associated with a more effective repair process after a heart attack, since FSTL-1 increases precisely in response to myocardial damage and decreases when the incentives for its expression from damaged heart tissue are reduced. Indirectly, this assumption is confirmed by the detected tendency to reduce the size of post-infarction fibrosis in the treatment with Ethoxidol. The results indicate the ability of Ethoxidol to influence FSTL-1 synthesis of in rats after myocardial infarction.