Endoglin: An 'Accessory' Receptor Regulating Blood Cell Development and Inflammation

Hereditary haemorrhagic telangiectasia: A primer for the paediatrician

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant condition characterised by small telangiectasias and larger multisystem arteriovenous malformations (AVMs). Common sites of AVMs include in the nose, lungs, brain and liver. These lesions are prone to rupture, leading to complications including recurrent epistaxis and significant haemorrhage. Pulmonary hypertension (PH) can also occur. This review presents an update on the genetics, clinical manifestations, management options, and screening recommendations for children with HHT.

High-fat diet triggers transcriptomic changes in the olfactory bulb

Metabolic imbalance contributes to cognitive impairment, anxiety, depressive behavior, and impaired olfactory perception. Recent studies have focused on olfactory dysfunction in patients with obesity and diabetes accompanied by cognitive dysfunction, considering that the synaptic signal from the olfactory bulb is directly transmitted to memory consolidation-related brain regions. This study investigated transcriptomic changes in the olfactory bulb in high-fat diet (HFD)-fed mice compared to that in normal-diet-fed mice. We sampled olfactory bulbs from HFD-fed mice, performed RNA sequencing, and measured mRNA levels in olfactory bulb tissue. Additionally, we assessed plasma cytokine levels in HFD-fed mice. We found differences in the expression of protein-coding and non-coding RNAs involved in insulin, lipid metabolism, neurogenesis, serotonin, dopamine, and gamma-aminobutyric acid-related signaling in the olfactory bulb of HFD-fed mice compared to control mice. Thus, our findings suggest potential therapeutic targets for treating olfactory dysfunction and related neural disorders in individuals with metabolic syndrome.

The Impact of Inflammation on the Etiopathogenesis of Benign Salivary Gland Tumors: A Scoping Review

Salivary gland tumors are rare head and neck tumors constituting up to 6% of all head and neck neoplasms; despite being mostly benign, these tumors present in diverse histological subtypes, making them challenging to diagnose and treat. Our research aims to investigate the link between inflammation and tumorigenesis within the salivary glands based on the literature regarding the etiopathogenesis of benign salivary gland tumors. This scoping review was conducted following the PRISMA extension for scoping reviews and reporting guidelines. The search was conducted using the Pubmed and Embase databases. Articles published between 2004 and May 2024 were included in the review. A total of 1097 papers were collected and identified. After 271 duplicates were removed, 826 titles and abstracts were independently reviewed by two researchers. Based on the title and abstract, 735 citations were excluded, and 91 articles were assessed for eligibility. Data were extracted from 46 articles that met the inclusion criteria. The review highlights the significance of inflammation-related factors and its relations with benign salivary gland tumors (SGTs). Knowledge of the etiopathogenesis of these tumors remains insufficient, and their rich immunological background poses challenges in diagnosis. The findings also point to directions for further clinical research, which will be necessary to implement these molecules in clinical practice.

A systematic review and meta-analysis of the endothelial-immune candidate biomarker endoglin in rheumatic diseases

Existing challenges in accurately diagnosing various rheumatic diseases (RDs) have stimulated the search for novel biomarkers to aid clinical evaluation and monitoring. We conducted a systematic review and meta-analysis of studies investigating the candidate biomarker endoglin (CD105), a transmembrane glycoprotein expressed in endothelial, myeloid, and lymphoid cells, in RD patients and healthy controls. We searched PubMed, Scopus, and Web of Science from inception to 10 August 2024 to identify relevant studies. We evaluated the risk of bias using the JBI Critical Appraisal Checklist and the certainty of evidence using GRADE (PROSPERO registration number: CRD42023581008). Overall, circulating endoglin concentrations were significantly higher in RD patients compared to controls (13 studies; standard mean difference, SMD = 0.64, 95% CI 0.13 to 1.14, p = 0.014; low certainty of evidence). The effect size of the between-group differences in endoglin concentrations was not significantly associated with age, male-to-female ratio, year of publication, number of participants, or mean RD duration. By contrast, the effect size was statistically significant in studies conducted in the European region (p = 0.033), involving patients with systemic sclerosis (p = 0.032), and measuring serum (p = 0.019). The results of this systematic review and meta-analysis suggest the potential pathophysiological role of endoglin in RDs. This, however, requires further investigation in prospective studies, particularly in patients with systemic sclerosis.

Erythropoietin-dependent Acquisition of CD71 hi CD105 hi Phenotype within CD235a - Early Erythroid Progenitors

The development of committed erythroid progenitors and their continued maturation into mature erythrocytes requires the cytokine erythropoietin (Epo). Here, we describe the immunophenotypic identification of a unique Epo-dependent colony-forming unit-erythroid (CFU-E) cell subtype that forms during early erythropoiesis (EE). This previously undescribed CFU-E subtype, termed late-CFU-E (lateC), lacks surface expression of the characteristic erythroid marker CD235a (glycophorin A) but has high levels of CD71 and CD105. LateCs could be prospectively detected in human bone marrow (BM) cells and, upon isolation and reculture, exhibited the potential to form CFU-E colonies in medium containing only Epo (no other cytokines) and continued differentiation along the erythroid trajectory. Analysis of ex vivo cultures of BM CD34 + cells showed that acquisition of the CD7 hi CD105 hi phenotype in lateCs is gradual and occurs through the formation of four EE cell subtypes. Of these, two are CD34 + burst-forming unit-erythroid (BFU-E) cells, distinguishable as CD7 lo CD105 lo early BFU-E and CD7 hi CD105 lo late BFU-E, and two are CD34 - CFU-Es, also distinguishable as CD71 lo CD105 lo early CFU-E and CD7 hi CD105 lo mid-CFU-E. The transition of these EE populations is accompanied by a rise in CD36 expression, such that all lateCs are CD36 + . Single cell RNA-sequencing analysis confirmed Epo-dependent formation of a CFU-E cluster that exhibits high coexpression of CD71, CD105, and CD36 transcripts. Gene set enrichment analysis revealed the involvement of genes specific to fatty acid and cholesterol metabolism in lateC formation. Overall, in addition to identifying a key Epo-dependent EE cell stage, this study provides a framework for investigation into mechanisms underlying other erythropoiesis-stimulating agents.

Receptors and Signaling Pathways Controlling Beta-Cell Function and Survival as Targets for Anti-Diabetic Therapeutic Strategies

Preserving the function and survival of pancreatic beta-cells, in order to achieve long-term glycemic control and prevent complications, is an essential feature for an innovative drug to have clinical value in the treatment of diabetes. Innovative research is developing therapeutic strategies to prevent pathogenic mechanisms and protect beta-cells from the deleterious effects of inflammation and/or chronic hyperglycemia over time. A better understanding of receptors and signaling pathways, and of how they interact with each other in beta-cells, remains crucial and is a prerequisite for any strategy to develop therapeutic tools aimed at modulating beta-cell function and/or mass. Here, we present a comprehensive review of our knowledge on membrane and intracellular receptors and signaling pathways as targets of interest to protect beta-cells from dysfunction and apoptotic death, which opens or could open the way to the development of innovative therapies for diabetes.

Antisense oligonucleotide-mediated terminal intron retention of endoglin: A potential strategy to inhibit renal interstitial fibrosis

TGF-β is considered an important cytokine in the development of interstitial fibrosis in chronic kidney disease. The TGF-β co-receptor endoglin (ENG) tends to be upregulated in kidney fibrosis. ENG has two membrane bound isoforms generated via alternative splicing. Long-ENG was shown to enhance the extent of renal fibrosis in an unilateral ureteral obstruction mouse model, while short-ENG inhibited renal fibrosis. Here we aimed to achieve terminal intron retention of endoglin using antisense-oligo nucleotides (ASOs), thereby shifting the ratio towards short-ENG to inhibit the TGF-β1-mediated pro-fibrotic response. We isolated mRNA from kidney biopsies of patients with chronic allograft disease (CAD) (n = 12) and measured total ENG and short-ENG mRNA levels. ENG mRNA was upregulated 2.3 fold (p < 0.05) in kidneys of CAD patients compared to controls, while the percentage short-ENG of the total ENG mRNA was significantly lower (1.8 fold; p < 0.05). Transfection of ASOs that target splicing regulatory sites of ENG into TK173 fibroblasts led to higher levels of short-ENG (2 fold; p < 0.05). In addition, we stimulated these cells with TGF-β1 and measured a decrease in upregulation of ACTA2, COL1A1 and FN1 mRNA levels, and protein expression of αSMA, collagen type I, and fibronectin. These results show a potential for ENG ASOs as a therapy to reduce interstitial fibrosis in CKD.

Qijiao Shengbai Capsule alleviated leukopenia by interfering leukotriene pathway: Integrated network study of multi-omics

BACKGROUND

Leukopenia could be induced by chemotherapy, which leads to bone marrow suppression and even affects the therapeutic progression of cancer. Qijiao Shengbai Capsule (QSC) has been used for the treatment of leukopenia in clinic, but its bioactive components and mechanisms have not yet been elucidated clearly.

PURPOSE

This study aimed to elucidate the molecular mechanisms of QSC in treating leukopenia.

STUDY DESIGN

Serum pharmacochemistry, multi-omics, network pharmacology, and validation experiment were combined to study the effect of QSC in murine leukopenia model.

METHODS

First, UPLC-QTOF-MS was used to clarify the absorbed components of QSC. Then, cyclophosphamide (CTX) was used to induce mice model with leukopenia, and the therapeutic efficacy of QSC was assessed by an integrative approach of multi-omics and network pharmacology strategy. Finally, molecular mechanisms and potential therapeutic targets were identified by validated experiments.

RESULTS

121 compounds absorbed in vivo were identified. QSC significantly increase the count of white blood cells (WBCs) in peripheral blood of leukopenia mice with 15 days treatment. Multi-omics and network pharmacology revealed that leukotriene pathway and MAPK signaling pathway played crucial roles during the treatment of leukopenia with QSC. Six targets (ALOX5, LTB4R, CYSLTR1, FOS, JUN, IL-1β) and 13 prototype compounds were supposed to be the key targets and potential active components, respectively. The validation experiment further confirmed that QSC could effectively inhibit the inflammatory response induced by leukopenia. The inhibitors of ALOX5 activity can significantly increase the number of WBCs in leukopenia mice. Molecular docking of ALOX5 suggested that calycosin, daidzein, and medicarpin were the potentially active compounds of QSC.

CONCLUSION

Leukotriene pathway was found for the first time to be a key role in the development of leukopenia, and ALOX5 was conformed as the potential target. QSC may inhibit the inflammatory response and interfere the leukotriene pathway, it is able to improve hematopoiesis and achieve therapeutic effects in the mice with leukopenia.

A Multifunctional Therapeutic Strategy Using P7C3 as A Countermeasure Against Bone Loss and Fragility in An Ovariectomized Rat Model of Postmenopausal Osteoporosis

By 2060, an estimated one in four Americans will be elderly. Consequently, the prevalence of osteoporosis and fragility fractures will also increase. Presently, no available intervention definitively prevents or manages osteoporosis. This study explores whether Pool 7 Compound 3 (P7C3) reduces progressive bone loss and fragility following the onset of ovariectomy (OVX)-induced osteoporosis. Results confirm OVX-induced weakened, osteoporotic bone together with a significant gain in adipogenic body weight. Treatment with P7C3 significantly reduced osteoclastic activity, bone marrow adiposity, whole-body weight gain, and preserved bone area, architecture, and mechanical strength. Analyses reveal significantly upregulated platelet derived growth factor-BB and leukemia inhibitory factor, with downregulation of interleukin-1 R6, and receptor activator of nuclear factor kappa-B (RANK). Together, proteomic data suggest the targeting of several key regulators of inflammation, bone, and adipose turnover, via transforming growth factor-beta/SMAD, and Wingless-related integration site/be-catenin signaling pathways. To the best of the knowledge, this is first evidence of an intervention that drives against bone loss via RANK. Metatranscriptomic analyses of the gut microbiota show P7C3 increased Porphyromonadaceae bacterium, Candidatus Melainabacteria, and Ruminococcaceae bacterium abundance, potentially contributing to the favorable inflammatory, and adipo-osteogenic metabolic regulation observed. The results reveal an undiscovered, and multifunctional therapeutic strategy to prevent the pathological progression of OVX-induced bone loss.

Soluble Endoglin and Syndecan-1 levels predicts the clinical outcome in COVID-19 patients

Endothelial instability is reported to be involved in the pathogenesis of COVID-19. The mechanism that regulates the endothelial dysfunction and disease virulence is not known. Studies on proteins that are released into circulation by activated endothelial cells may provide some means to understand the disease manifestation. The study investigated the circulating levels of two molecules Endoglin (Eng) and Syndecan-1 (SDC-1) that are presumed to be involved in the maintenance of endothelial integrity and their association with hypercoagulation marker in COVID-19 patients. The serum levels of Eng, SDC-1, D-mer were evaluated using ELISA at the time of admission (DOA) and day 7 post-admission among COVID-19 patients (N = 39 with 17 moderate and 22 severe cases). Compared to the time of admission, there was an increase in sEng and sSDC1 levels in all COVID-19 cases on day 7 post admission. The serum levels of sEng and sSDC-1 was significantly (P ≤ 0.001 & P ≤ 0.01 respectively) elevated in severe cases including the four deceased group compared to moderate cases on day 7 post admission. Further, the study molecules showed a strong positive association (P ≤ 0.001) with the hypercoagulation marker D-mer. The results show an early shedding of the endothelial proteins sEng and sSDC-1 into circulation as a host response to the viral infection during the febrile phase of infection. Increased levels of sEng and sSDC-1 along with D-mer could be beneficial in predicting COVID-19 disease severity.

Endoglin mutants retained in the endoplasmic reticulum exacerbate loss of function in hereditary hemorrhagic telangiectasia type 1 (HHT1) by exerting dominant negative effects on the wild type allele

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder affecting 1 in 5000-8000 individuals. Hereditary hemorrhagic telangiectasia type 1 (HHT1) is the most common HHT and manifests as diverse vascular malformations ranging from mild symptoms such as epistaxis and mucosal and cutaneous telangiectases to severe arteriovenous malformations (AVMs) in the lungs, brain or liver. HHT1 is caused by heterozygous mutations in the ENG gene, which encodes endoglin, the TGFβ homodimeric co-receptor. It was previously shown that some endoglin HHT1-causing variants failed to traffic to the plasma membrane due to their retention in the endoplasmic reticulum (ER) and consequent degradation by ER-associated degradation (ERAD). Endoglin is a homodimer formed in the ER, and we therefore hypothesized that mixed heterodimers might form between ER-retained variants and WT protein, thus hampering its maturation and trafficking to the plasma membrane causing dominant negative effects. Indeed, HA-tagged ER-retained mutants formed heterodimers with Myc-tagged WT endoglin. Moreover, variants L32R, V105D, P165L, I271N and C363Y adversely affected the trafficking of WT endoglin by reducing its maturation and plasma membrane localization. These results strongly suggest dominant negative effects exerted by these ER-retained variants aggravating endoglin loss of function in patients expressing them in the heterozygous state with the WT allele. Moreover, this study may help explain some of the variability observed among HHT1 patients due to the additional loss of function exerted by the dominant negative effects in addition to that due to haploinsufficiency. These findings might also have implications for some of the many conditions impacted by ERAD.

TMT-Based Proteomics Analysis Revealed the Protein Changes in Perirenal Fat from Obese Rabbits

Obesity has become increasingly prevalent in recent years, and there is a need for a deeper understanding of the complex pathogenesis underlying the obesity condition. Therefore, the objective of this study was to investigate how a high-fat diet (HFD) affects protein expression in a female-rabbit model compared to a standard normal-diet group (SND), to gain comprehensive insights into the molecular mechanisms involved in obesity. To achieve this objective, a tandem mass tag (TMT)-based quantitative proteomics analysis was conducted to examine the molecular changes occurring in the white adipose tissue (WAT) from the HFD and SND groups. The sequencing results identified a total of 4215 proteins, among which 151 proteins exhibited significant differential expression. Specifically, there were 85 upregulated proteins and 66 downregulated proteins in the HFD group compared to the SND group. Further analysis of these differentially expressed proteins (DEPs) revealed their involvement in crucial biological processes, including energy metabolism, hormonal regulation, and inflammatory response. In conclusion, this study sheds light on the impact of HFD on protein expression in a female-rabbit model, providing new insights into the molecular mechanisms underlying obesity and the associated metabolic disorders.

Nonfunctional TGF-β/ALK1/ENG signaling pathway supports neutrophil proangiogenic activity in hereditary hemorrhagic telangiectasia

The transforming growth factor β (TGF-β)/ALK1/ENG signaling pathway maintains quiescent state of endothelial cells, but at the same time, it regulates neutrophil functions. Importantly, mutations of this pathway lead to a rare autosomal disorder called hereditary hemorrhagic telangiectasia (HHT), characterized with abnormal blood vessel formation (angiogenesis). As neutrophils are potent regulators of angiogenesis, we investigated how disturbed TGF-β/ALK1/ENG signaling influences angiogenic properties of these cells in HHT. We could show for the first time that not only endothelial cells, but also neutrophils isolated from such patients are ENG/ALK1 deficient. This deficiency obviously stimulates proangiogenic switch of such neutrophils. Elevated proangiogenic activity of HHT neutrophils is mediated by the increased spontaneous degranulation of gelatinase granules, resulting in high release of matrix-degrading matrix metalloproteinase 9 (MMP9). In agreement, therapeutic disturbance of this process using Src tyrosine kinase inhibitors impaired proangiogenic capacity of such neutrophils. Similarly, inhibition of MMP9 activity resulted in significant impairment of neutrophil-mediated angiogenesis. All in all, deficiency in TGF-β/ALK1/ENG signaling in HHT neutrophils results in their proangiogenic activation and disease progression. Therapeutic strategies targeting neutrophil degranulation and MMP9 release and activity may serve as a potential therapeutic option for HHT.

Novel vascular roles of human endoglin in pathophysiology

Endoglin, alias CD105, is a human membrane glycoprotein highly expressed in vascular endothelial cells. It is involved in angiogenesis and angiogenesis-related diseases, including the rare vascular pathology known as hereditary hemorrhagic telangiectasia type 1. Although endoglin acts as an accessory receptor for members of the transforming growth factor-β family, in recent years, emerging evidence has shown a novel functional role for this protein beyond the transforming growth factor-β system. In fact, endoglin has been found to be an integrin counterreceptor involved in endothelial cell adhesion processes during pathological inflammatory conditions and primary hemostasis. Furthermore, a circulating form of endoglin, also named as soluble endoglin, whose levels are abnormally increased in different pathological conditions, such as preeclampsia, seems to act as an antagonist of membrane-bound endoglin and as a competitor of the fibrinogen-integrin interaction in platelet-dependent thrombus formation. These studies suggest that membrane-bound endoglin and circulating endoglin are important components involved in vascular homeostasis and hemostasis.

CD105 in the progression and therapy of renal cell carcinoma

Molecular biomarkers that interact with the vascular and immune compartments play an important role in the progression of solid malignancies. CD105, which is a component of the transforming growth factor beta (TGF β) signaling cascade, has long been studied for its role in potentiating angiogenesis in numerous cancers. In renal cell carcinoma (RCC), the role of CD105 is more complicated due to its diverse expression profile on the tumor cells, tumor vasculature, and the components of the immune system. Since its discovery, its angiogenic role has overshadowed other potential functions, especially in cancers. In this review, we aim to summarize the recent evidence and findings of the multifunctional roles of CD105 in angiogenesis and immunomodulation in the context of the various subtypes of RCC, with a specific emphasis on the clear cell RCC subtype. Since CD105 is an established biomarker and tumor antigen, we also provide an update on the preclinical and clinical applications of CD105 as a therapeutic platform in RCC.

Analysis of Immunophenotypic Changes during Ex Vivo Human Erythropoiesis and Its Application in the Study of Normal and Defective Erythropoiesis

Erythropoiesis is a highly regulated process and undergoes several genotypic and phenotypic changes during differentiation. The phenotypic changes can be evaluated using a combination of cell surface markers expressed at different cellular stages of erythropoiesis using FACS. However, limited studies are available on the in-depth phenotypic characterization of progenitors from human adult hematopoietic stem and progenitor cells (HSPCs) to red blood cells. Therefore, using a set of designed marker panels, in the current study we have kinetically characterized the hematopoietic, erythroid progenitors, and terminally differentiated erythroblasts ex vivo. Furthermore, the progenitor stages were explored for expression of CD117, CD31, CD41a, CD133, and CD45, along with known key markers CD36, CD71, CD105, and GPA. Additionally, we used these marker panels to study the stage-specific phenotypic changes regulated by the epigenetic regulator; Nuclear receptor binding SET Domain protein 1 (NSD1) during erythropoiesis and to study ineffective erythropoiesis in myelodysplastic syndrome (MDS) and pure red cell aplasia (PRCA) patients. Our immunophenotyping strategy can be used to sort and study erythroid-primed hematopoietic and erythroid precursors at specified time points and to study diseases resulting from erythroid dyspoiesis. Overall, the current study explores the in-depth kinetics of phenotypic changes occurring during human erythropoiesis and applies this strategy to study normal and defective erythropoiesis.

High concentrations of soluble endoglin can inhibit BMP9 signaling in non-endothelial cells

Endoglin (ENG) is a single-pass transmembrane protein highly expressed on vascular endothelial cells, although low expression levels can be detected in many other cell types. Its extracellular domain can be found in circulation known as soluble endoglin (sENG). Levels of sENG are elevated in many pathological conditions, in particular preeclampsia. We have shown that while loss of cell surface ENG decreases BMP9 signaling in endothelial cells, knocking down ENG in blood cancer cells enhances BMP9 signaling. Despite sENG binding to BMP9 with high affinity and blocking the type II receptor binding site on BMP9, sENG did not inhibit BMP9 signaling in vascular endothelial cells, but the dimeric form of sENG inhibited BMP9 signaling in blood cancer cells. Here we report that in non-endothelial cells such as human multiple myeloma cell lines and the mouse myoblast cell line C2C12, both monomeric and dimeric forms of sENG inhibit BMP9 signaling when present at high concentrations. Such inhibition can be alleviated by the overexpression of ENG and ACVRL1 (encoding ALK1) in the non-endothelial cells. Our findings suggest that the effects of sENG on BMP9 signaling is cell-type specific. This is an important consideration when developing therapies targeting the ENG and ALK1 pathway.

Natural Killer Cell Derived Microvesicles Affect the Function of Trophoblast Cells

The interaction of natural killer (NK) and trophoblast cells underlies the formation of immune tolerance in the mother-fetus system and the maintenance of the physiological course of pregnancy. In addition, NK cells affect the function of trophoblast cells, interacting with them via the receptor apparatus and through the production of cytokines. Microvesicles (MVs) derived from NK cells are able to change the function of target cells. However, in the overall pattern of interactions between NK cells and trophoblasts, the possibility that both can transmit signals to each other via MVs has not been taken into account. Therefore, the aim of this study was to assess the effect of NK cell-derived MVs on the phenotype, proliferation, and migration of trophoblast cells and their expression of intracellular messengers. We carried out assays for the detection of content transferred from MV to trophoblasts. We found that NK cell-derived MVs did not affect the expression of CD54, CD105, CD126, CD130, CD181, CD119, and CD120a receptors in trophoblast cells or lead to the appearance of CD45 and CD56 receptors in the trophoblast membrane. Further, the MVs reduced the proliferation but increased the migration of trophoblasts with no changes to their viability. Incubation of trophoblast cells in the presence of MVs resulted in the activation of STAT3 via pSTAT3(Ser727) but not via pSTAT3(Tyr705). The treatment of trophoblasts with MVs did not result in the phosphorylation of STAT1 and ERK1/2. The obtained data indicate that NK cell-derived MVs influence the function of trophoblast cells, which is accompanied by the activation of STAT3 signaling.

Comprehensive analysis of autoimmune-related genes in amyotrophic lateral sclerosis from the perspective of 3P medicine

Background

Although growing evidence suggests close correlations between autoimmunity and amyotrophic lateral sclerosis (ALS), no studies have reported on autoimmune-related genes (ARGs) from the perspective of the prognostic assessment of ALS. The purpose of this study was to investigate whether the circulating ARD signature could be identified as a reliable biomarker for ALS survival for predictive, preventive, and personalized medicine.

Methods

The whole blood transcriptional profiles and clinical characteristics of 454 ALS patients were downloaded from the Gene Expression Omnibus (GEO) database. A total of 4371 ARGs were obtained from GAAD and DisGeNET databases. Wilcoxon test and multivariate Cox regression were applied to identify the differentially expressed and prognostic ARGs. Then, unsupervised clustering was performed to classify patients into two distinct autoimmune-related clusters. PCA method was used to calculate the autoimmune index. LASSO and multivariate Cox regression was performed to establish risk model to predict overall survival for ALS patients. A ceRNA regulatory network was then constructed for regulating the model genes. Finally, we performed single-cell analysis to explore the expression of model genes in mutant SOD1 mice and methylation analysis in ALS patients.

Results

Based on the expressions of 85 prognostic ARGs, two autoimmune-related clusters with various biological features, immune characteristics, and survival outcome were determined. Cluster 1 with a worsen prognosis was more active in immune-related biological pathways and immune infiltration than Cluster 2. A higher autoimmune index was associated with a better prognosis than a lower autoimmune index, and there were significant adverse correlations between the autoimmune index and immune infiltrating cells and immune responses. Nine model genes (KIF17, CD248, ENG, BTNL2, CLEC5A, ADORA3, PRDX5, AIM2, and XKR8) were selected to construct prognostic risk signature, indicating potent potential for survival prediction in ALS. Nomogram integrating risk model and clinical characteristics could predict the prognosis more accurately than other clinicopathological features. We constructed a ceRNA regulatory network for the model genes, including five lncRNAs, four miRNAs, and five mRNAs.

Conclusion

Expression of ARGs is correlated with immune characteristics of ALS, and seven ARG signatures may have practical application as an independent prognostic factor in patients with ALS, which may serve as target for the future prognostic assessment, targeted prevention, patient stratification, and personalization of medical services in ALS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-022-00299-w.

Hereditary Hemorrhagic Telangiectasia: Genetics, Pathophysiology, Diagnosis, and Management

Hereditary hemorrhagic telangiectasia is an inherited disease related to an alteration in angiogenesis, manifesting as cutaneous telangiectasias and epistaxis. As complications, it presents vascular malformations in organs such as the lung, liver, digestive tract, and brain. Currently, diagnosis can be made using the Curaçao criteria or by identifying the affected gene. In recent years, there has been an advance in the understanding of the pathophysiology of the disease, which has allowed the use of new therapeutic strategies to improve the quality of life of patients. This article reviews some of the main and most current evidence on the pathophysiology, clinical manifestations, diagnostic approach, screening for complications, and therapeutic options, both pharmacological and surgical.

The impact of periodontitis on vascular endothelial dysfunction

Periodontitis, an oral inflammatory disease, originates from periodontal microbiota dysbiosis which is associated with the dysregulation of host immunoinflammatory response. This chronic infection is not only harmful to oral health but is also a risk factor for the onset and progress of various vascular diseases, such as hypertension, atherosclerosis, and coronary arterial disease. Vascular endothelial dysfunction is the initial key pathological feature of vascular diseases. Clarifying the association between periodontitis and vascular endothelial dysfunction is undoubtedly a key breakthrough for understanding the potential relationship between periodontitis and vascular diseases. However, there is currently a lack of an updated review of their relationship. Therefore, we aim to focus on the implications of periodontitis in vascular endothelial dysfunction in this review.

Prognostic value of soluble endoglin in patients with septic shock and severe COVID-19

Sepsis is a clinical syndrome characterized by a dysregulated response to infection. It represents a leading cause of mortality in ICU patients worldwide. Although sepsis is in the point of interest of research for several decades, its clinical management and patient survival are improving slowly. Monitoring of the biomarkers and their combinations could help in early diagnosis, estimation of prognosis and patient's stratification and response to the treatment. Circulating soluble endoglin (sEng) is the cleaved extracellular part of transmembrane glycoprotein endoglin. As a biomarker, sEng has been tested in several pathologic conditions where its elevation was associated with endothelial dysfunction. In this study we have tested the ability of sEng to predict mortality and its correlation with other clinical characteristics in the cohort of septic shock patients (n = 37) and patients with severe COVID-19 (n = 40). In patients with COVID-19 sEng did not predict mortality or correlate with markers of organ dysfunction. In contrast, in septic shock the level of sEng was significantly higher in patients with early mortality (p = 0.019; AUC = 0.801). Moreover, sEng levels correlated with signs of circulatory failure (required dose of noradrenalin and lactate levels; p = 0.002 and 0.016, respectively). The predominant clinical problem in patients with COVID-19 was ARDS, and although they often showed signs of other organ dysfunction, circulatory failure was exceptional. This potentially explains the difference between sEng levels in COVID-19 and septic shock. In conclusion, we have confirmed that sEng may reflect the extent of the circulatory failure in septic shock patients and thus could be potentially used for the early identification of patients with the highest degree of endothelial dysfunction who would benefit from endothelium-targeted individualized therapy.

Role of TGF-Beta Signaling in Beta Cell Proliferation and Function in Diabetes

Beta (β) cell dysfunction or loss is the common pathological feature in all types of diabetes mellitus (diabetes). Resolving the underlying mechanism may facilitate the treatment of diabetes by preserving the β cell population and function. It is known that TGF-β signaling plays diverse roles in β cell development, function, proliferation, apoptosis, and dedifferentiation. Inhibition of TGF-β signaling expands β cell lineage in the development. However, deletion of Tgfbr1 has no influence on insulin demand-induced but abolishes inflammation-induced β cell proliferation. Among canonical TGF-β signaling, Smad3 but not Smad2 is the predominant repressor of β cell proliferation in response to systemic insulin demand. Deletion of Smad3 simultaneously improves β cell function, apoptosis, and systemic insulin resistance with the consequence of eliminated overt diabetes in diabetic mouse models, revealing Smad3 as a key mediator and ideal therapeutic target for type-2 diabetes. However, Smad7 shows controversial effects on β cell proliferation and glucose homeostasis in animal studies. On the other hand, overexpression of Tgfb1 prevents β cells from autoimmune destruction without influence on β cell function. All these findings reveal the diverse regulatory roles of TGF-β signaling in β cell biology.

Endoglin Wild Type and Variants Associated With Hereditary Hemorrhagic Telangiectasia Type 1 Undergo Distinct Cellular Degradation Pathways

Endoglin, also known as cluster of differentiation 105 (CD105), is an auxiliary receptor in the TGFβ signaling pathway. It is predominantly expressed in endothelial cells as a component of the heterotetrameric receptor dimers comprising type I, type II receptors and the binding ligands. Mutations in the gene encoding Endoglin (ENG) have been associated with hereditary hemorrhagic telangiectasia type 1 (HHT1), an autosomal dominant inherited disease that is generally characterized by vascular malformation. Secretory and many endomembrane proteins synthesized in the Endoplasmic reticulum (ER) are subjected to stringent quality control mechanisms to ensure that only properly folded and assembled proteins are trafficked forward through the secretory pathway to their sites of action. We have previously demonstrated that some Endoglin variants causing HHT1 are trapped in the ER and fail to traffic to their normal localization in plasma membrane, which suggested the possible involvement of ER associated protein degradation (ERAD) in their molecular pathology. In this study, we have investigated, for the first time, the degradation routes of Endoglin wild type and two mutant variants, P165L and V105D, and previously shown to be retained in the ER. Stably transfected HEK293 cells were treated with proteasomal and lysosomal inhibitors in order to elucidate the exact molecular mechanisms underlying the loss of function phenotype associated with these variants. Our results have shown that wild type Endoglin has a relatively short half-life of less than 2 hours and degrades through both the lysosomal and proteasomal pathways, whereas the two mutant disease-causing variants show high stability and predominantly degrades through the proteasomal pathway. Furthermore, we have demonstrated that Endoglin variants P165L and V105D are significantly accumulated in HEK293 cells deficient in HRD1 E3 ubiquitin ligase; a major ERAD component. These results implicate the ERAD mechanism in the pathology of HHT1 caused by the two variants. It is expected that these results will pave the way for more in-depth research studies that could provide new windows for future therapeutic interventions.

TGF-β superfamily co-receptors in cancer

Transforming growth factor-β (TGF-β) superfamily signaling via their cognate receptors is frequently modified by TGF-β superfamily co-receptors. Signaling through SMAD-mediated pathways may be enhanced or depressed depending on the specific co-receptor and cell context. This dynamic effect on signaling is further modified by the release of many of the co-receptors from the membrane to generate soluble forms that are often antagonistic to the membrane-bound receptors. The co-receptors discussed here include TβRIII (betaglycan), endoglin, BAMBI, CD109, SCUBE proteins, neuropilins, Cripto-1, MuSK, and RGMs. Dysregulation of these co-receptors can lead to altered TGF-β superfamily signaling that contributes to the pathophysiology of many cancers through regulation of growth, metastatic potential, and the tumor microenvironment. Here we describe the role of several TGF-β superfamily co-receptors on TGF-β superfamily signaling and the impact on cellular and physiological functions with a particular focus on cancer, including a discussion on recent pharmacological advances and potential clinical applications targeting these co-receptors.

Generation of a Soluble Form of Human Endoglin Fused to Green Fluorescent Protein

Endoglin (Eng, CD105) is a type I membrane glycoprotein that functions in endothelial cells as an auxiliary receptor for transforming growth factor β (TGF-β)/bone morphogenetic protein (BMP) family members and as an integrin ligand, modulating the vascular pathophysiology. Besides the membrane-bound endoglin, there is a soluble form of endoglin (sEng) that can be generated by the action of the matrix metalloproteinase (MMP)-14 or -12 on the juxtamembrane region of its ectodomain. High levels of sEng have been reported in patients with preeclampsia, hypercholesterolemia, atherosclerosis and cancer. In addition, sEng is a marker of cardiovascular damage in patients with hypertension and diabetes, plays a pathogenic role in preeclampsia, and inhibits angiogenesis and tumor proliferation, migration, and invasion in cancer. However, the mechanisms of action of sEng have not yet been elucidated, and new tools and experimental approaches are necessary to advance in this field. To this end, we aimed to obtain a fluorescent form of sEng as a new tool for biological imaging. Thus, we cloned the extracellular domain of endoglin in the pEGFP-N1 plasmid to generate a fusion protein with green fluorescent protein (GFP), giving rise to pEGFP-N1/Eng.EC. The recombinant fusion protein was characterized by transient and stable transfections in CHO-K1 cells using fluorescence microscopy, SDS-PAGE, immunodetection, and ELISA techniques. Upon transfection with pEGFP-N1/Eng.EC, fluorescence was readily detected in cells, indicating that the GFP contained in the recombinant protein was properly folded into the cytosol. Furthermore, as evidenced by Western blot analysis, the secreted fusion protein yielded the expected molecular mass and displayed a specific fluorescent signal. The fusion protein was also able to bind to BMP9 and BMP10 in vitro. Therefore, the construct described here could be used as a tool for functional in vitro studies of the extracellular domain of endoglin.

The potential regulatory role of BMP9 in inflammatory responses

Inflammation is a protective response of the body to pathogens and injury. Hence, it is particularly important to explore the pathogenesis and key regulatory factors of inflammation. BMP9 is a unique member of the BMP family, which is widely known for its strong osteogenic potential and insensitivity to the inhibition of BMP3. Recently, several studies have reported an underlying pivotal link between BMP9 and inflammation. What is clear, though not well understood, is that BMP9 plays a role in inflammation in a carefully choreographed manner in different contexts. In this review, we have summarized current studies focusing on BMP9 and inflammation in various tissues and the latest advances in BMP9 expression, signal transduction, and crystal structure to better understand the relationship between BMP9 and inflammation. In addition, we also briefly summarized the inflammatory characteristics of some TGF-β superfamily members to provide better insights and ideas for the study of BMP9 and inflammation.

Blockade of the interaction between BMP9 and endoglin on erythroid progenitors promotes erythropoiesis in mice

Bone morphogenetic protein‐9 (BMP9), a member of the transforming growth factor β (TGFβ) superfamily, plays important roles in the development and maintenance of various cell lineages via complexes of type I and type II TGFβ receptors. Endoglin is a coreceptor for several TGFβ family members, including BMP9, which is highly expressed in a particular stage of differentiation in erythroid cells as well as in endothelial cells. Although the importance of the interaction between BMP9 and endoglin for endothelial development has been reported, the contribution of BMP9 to endoglin‐expressing erythroid cells remains to be clarified. To address this point, we prepared an anti‐BMP9 antibody that blocks the BMP9‐endoglin interaction. Of note, challenge with the antibody promotes erythropoiesis in wild‐type mice but not in a mouse model of renal anemia in which erythropoietin (EPO) production in the kidneys is genetically ablated. While endoglin‐positive erythroid progenitors are mainly maintained as progenitors when bone marrow‐derived lineage‐negative and cKit‐positive cells are cultured in the presence of EPO and stem cell factor, the erythroid‐biased accumulation of progenitors is impeded by the presence of BMP9. Our findings uncover an unrecognized role for BMP9 in attenuating erythroid differentiation via its interaction with endoglin on erythroid progenitors.

Zbtb46-dependent altered developmental program in embryonic stem cell-derived blood cell progenitors

Zbtb46 is a recently identified dendritic cell (DC)-specific transcription factor with poorly defined biology. Although Zbtb46 is highly expressed in conventional DCs, evidence also points to its presence in erythroid progenitors and endothelial cells suggesting that this factor might influence the early hematopoietic development. Here, we probe the effect of this transcription factor in embryonic stem cell (ESC)-derived blood cell progenitors using chemically inducible mouse cell lines. Unexpectedly, forced expression of this protein elicited a broad repressive effect at the early stage of ESC differentiation. Ectopic expression of Zbtb46 interfered with the mesoderm formation and cell proliferation was also negatively impacted. More importantly, reduced number of CD11b+ myeloid blood cells were generated from ESC-derived Flk1+ mesoderm cells in the presence of Zbtb46. Consistent with this finding, our gene expression profiling revealed that numerous myeloid and immune response related genes, including Irf8, exhibited lower expression in the Zbtb46-primed cells. Despite these repressive effects, however, Zbtb46 overexpression was associated with enhanced formation of erythroid blood cell colonies and increased adult hemoglobin (Hbb-b1) expression at the early phase of ESC differentiation. Moreover, elevated percent of CD105 (Endoglin) positive cells were detected in the Zbtb46-primed samples. In summary, our results support that Zbtb46 suppresses the ESC-derived myeloid development and diverts mesoderm cells toward erythroid developmental pathway. Moreover, our transcriptomic data provide a resource for exploration of the Zbtb46 regulatory network in ESC-derived progenitors.

Vascular Endothelial Growth Factor, a Key Modulator of the Anti-Tumor Immune Response

During tumor growth, angiogenesis is required to ensure oxygen and nutrient transport to the tumor. Vascular endothelial growth factor (VEGF) is the major inducer of angiogenesis and appears to be a key modulator of the anti-tumor immune response. Indeed, VEGF modulates innate and adaptive immune responses through direct interactions and indirectly by modulating protein expressions on endothelial cells or vascular permeability. The inhibition of the VEGF signaling pathway is clinically approved for the treatment of several cancers. Therapies targeting VEGF can modulate the tumor vasculature and the immune response. In this review, we discuss the roles of VEGF in the anti-tumor immune response. In addition, we summarize therapeutic strategies based on its inhibition, and their clinical approval.

Hot and Cold Tumors: Is Endoglin (CD105) a Potential Target for Vessel Normalization?

Tumors are complex masses formed by malignant but also by normal cells. The interaction between these cells via cytokines, chemokines, growth factors, and enzymes that remodel the extracellular matrix (ECM) constitutes the tumor microenvironment (TME). This TME can be determinant in the prognosis and the response to some treatments such as immunotherapy. Depending on their TME, two types of tumors can be defined: hot tumors, characterized by an immunosupportive TME and a good response to immunotherapy; and cold tumors, which respond poorly to this therapy and are characterized by an immunosuppressive TME. A therapeutic strategy that has been shown to be useful for the conversion of cold tumors into hot tumors is vascular normalization. In this review we propose that endoglin (CD105) may be a useful target of this strategy since it is involved in the three main processes involved in the generation of the TME: angiogenesis, inflammation, and cancer-associated fibroblast (CAF) accumulation. Moreover, the analysis of endoglin expression in tumors, which is already used in the clinic to study the microvascular density and that is associated with worse prognosis, could be used to predict a patient's response to immunotherapy.