Inflammatory hypoxia induces syndecan-2 expression through IL-1β-mediated FOXO3a activation in colonic epithelia

Capillary leak and endothelial permeability in critically ill patients: a current overview

Capillary leak syndrome (CLS) represents a phenotype of increased fluid extravasation, resulting in intravascular hypovolemia, extravascular edema formation and ultimately hypoperfusion. While endothelial permeability is an evolutionary preserved physiological process needed to sustain life, excessive fluid leak-often caused by systemic inflammation-can have detrimental effects on patients' outcomes. This article delves into the current understanding of CLS pathophysiology, diagnosis and potential treatments. Systemic inflammation leading to a compromise of endothelial cell interactions through various signaling cues (e.g., the angiopoietin-Tie2 pathway), and shedding of the glycocalyx collectively contribute to the manifestation of CLS. Capillary permeability subsequently leads to the seepage of protein-rich fluid into the interstitial space. Recent insights into the importance of the sub-glycocalyx space and preserving lymphatic flow are highlighted for an in-depth understanding. While no established diagnostic criteria exist and CLS is frequently diagnosed by clinical characteristics only, we highlight more objective serological and (non)-invasive measurements that hint towards a CLS phenotype. While currently available treatment options are limited, we further review understanding of fluid resuscitation and experimental approaches to target endothelial permeability. Despite the improved understanding of CLS pathophysiology, efforts are needed to develop uniform diagnostic criteria, associate clinical consequences to these criteria, and delineate treatment options.

Serum Osteopontin, KL-6, and Syndecan-4 as Potential Biomarkers in the Diagnosis of Coal Workers' Pneumoconiosis: A Case-Control Study

Background

Coal worker's pneumoconiosis (CWP) is a chronic occupational disease mainly caused by coal dust inhalation in miners. This study aimed to investigate the clinical value of Osteopontin (OPN), KL-6, Syndecan-4 and Gremlin-1 as serum biomarkers in CWP.

Patients and Methods

We integrated reported lung tissues transcriptome data in pneumoconiosis patients with silica-exposed alveolar macrophage microarray data to identify four CWP-associated serum biomarkers. The serum concentrations of Osteopontin, Krebs von den Lungen-6 (KL-6), Syndecan-4 and Gremlin-1 were measured in 100 healthy controls (HCs), 100 dust-exposed workers (DEWs) and 200 patients of CWP. Receiver operating characteristic (ROC) curve analysis was used to determine the sensitivity, specificity, cut-off value and area under the curve (AUC) value of biomarkers.

Results

The pulmonary function parameters decreased sequentially, and the serum OPN, KL-6, Syndecan-4 and Gremlin-1 concentrations were increased sequentially among the HC, DEW and CWP groups. Among all participants, multivariable analysis revealed that these four biomarkers were negatively correlated with the pulmonary function parameters (all p<0.05). Compared with HCs, patients with higher OPN, KL-6, Syndecan-4 and Gremlin-1 had higher risk for CWP. The combination of OPN, KL-6, and Syndecan-4 can improve the diagnostic sensitivity and specificity of CWP patients differentiated from HCs or DEWs.

Conclusion

OPN, KL-6 and Syndecan-4 are novel biomarkers that can be used for CWP auxiliary diagnosis. The combination of three biomarkers can improve the diagnostic values of CWP.

Endothelial Damage and the Microcirculation in Critical Illness

Endothelial integrity maintains microcirculatory flow and tissue oxygen delivery. The endothelial glycocalyx is involved in cell signalling, coagulation and inflammation. Our ability to treat critically ill and septic patients effectively is determined by understanding the underpinning biological mechanisms. Many mechanisms govern the development of sepsis and many large trials for new treatments have failed to show a benefit. Endothelial dysfunction is possibly one of these biological mechanisms. Glycocalyx damage is measured biochemically. Novel microscopy techniques now mean the glycocalyx can be indirectly visualised, using sidestream dark field imaging. How the clinical visualisation of microcirculation changes relate to biochemical laboratory measurements of glycocalyx damage is not clear. This article reviews the evidence for a relationship between clinically evaluable microcirculation and biological signal of glycocalyx disruption in various diseases in ICU. Microcirculation changes relate to biochemical evidence of glycocalyx damage in some disease states, but results are highly variable. Better understanding and larger studies of this relationship could improve phenotyping and personalised medicine in the future. Damage to the glycocalyx could underpin many critical illness pathologies and having real-time information on the glycocalyx and microcirculation in the future could improve patient stratification, diagnosis and treatment.

Syndecan-2 selectively regulates VEGF-induced vascular permeability

Vascular endothelial growth factor (VEGF)- driven increase in vascular permeability is a key feature of many disease states associated with inflammation and ischemic injury, contributing significantly to morbidity and mortality in these settings. Despite its importance, no specific regulators that preferentially control VEGF-dependent increase in permeability versus its other biological activities, have been identified. Here we report that a proteoglycan Syndecan-2 (Sdc2) regulates the interaction between a transmembrane phosphatase DEP1 and VEGFR2 by controlling cell surface levels of DEP1. In the absence of Sdc2 or the presence of an antibody that blocks Sdc2-DEP1 interaction, increased plasma membrane DEP1 levels promote selective dephosphorylation of the VEGFR2 Y951 site that is involved in permeability control. Either an endothelial-specific Sdc2 deletion or a treatment with an anti-Sdc2 antibody result in a highly significant reduction in stroke size due to a decrease in intracerebral edema.

Emerging role of syndecans in maintaining homeostasis of colon epithelium during inflammation

The syndecans are a family of transmembrane proteoglycans that are widespread in mammalian tissues. Located at the cell surface membrane, they contribute to modulating the composition of the extracellular matrix via glycosaminoglycan chains (GAGs) attached to their extracellular domains. Syndecans can interact with a variety of extracellular ligands through their core proteins and GAGs, and may also transmit signals through their transmembrane domain to regulate intracellular functions. These properties enable syndecan to modulate glycocalyx formation, epithelial cell-to-cell connections for cell barrier formation, and epithelial cell-lamina propria interactions in the colon epithelium, all of which are crucial for the homeostasis of this tissue. Inflammation induces structural alterations of the colon epithelium, and accumulating evidence suggests that syndecan expression might play important regulatory functions during inflammation. This review summarizes the possible roles of syndecans in maintaining tissue homeostasis in the colon epithelium, especially under inflammation.

Hypoxia inhibits colonic uptake of the microbiota-generated forms of vitamin B1 via HIF-1α-mediated transcriptional regulation of their transporters

Hypoxia exerts profound effects on cell physiology, but its effect on colonic uptake of the microbiota-generated forms of vitamin B1 (i.e., thiamin pyrophosphate [TPP] and free thiamine) has not been described. Here, we used human colonic epithelial NCM460 cells and human differentiated colonoid monolayers as in vitro and ex vivo models, respectively, and were subjected to either chamber (1% O2, 5% CO2, and 94% N2) or chemically (desferrioxamine; 250 μM)-induced hypoxia followed by determination of different physiological-molecular parameters. We showed that hypoxia causes significant inhibition in TPP and free thiamin uptake by colonic NCM460 cells and colonoid monolayers; it also caused a significant reduction in the expression of TPP (SLC44A4) and free thiamin (SLC19A2 and SLC19A3) transporters and in activity of their gene promoters. Furthermore, hypoxia caused a significant induction in levels of hypoxia-inducible transcription factor (HIF)-1α but not HIF-2α. Knocking down HIF-1α using gene-specific siRNAs in NCM460 cells maintained under hypoxic conditions, on the other hand, led to a significant reversal in the inhibitory effect of hypoxia on TPP and free thiamin uptake as well as on the expression of their transporters. Finally, a marked reduction in level of expression of the nuclear factors cAMP responsive element-binding protein 1 and gut-enriched Krüppel-like factor 4 (required for activity of SLC44A4 and SLC19A2 promoters, respectively) was observed under hypoxic conditions. In summary, hypoxia causes severe inhibition in colonic TPP and free thiamin uptake that is mediated at least in part via HIF-1α-mediated transcriptional mechanisms affecting their respective transporters.

Effect of Ulinastatin on Syndecan-2-Mediated Vascular Damage in IDH2-Deficient Endothelial Cells

Syndecan-2 (SDC2), a cell-surface heparin sulfate proteoglycan of the glycocalyx, is mainly expressed in endothelial cells. Although oxidative stress and inflammatory mediators have been shown to mediate dysfunction of the glycocalyx, little is known about their role in vascular endothelial cells. In this study, we aimed to identify the mechanism that regulates SDC2 expression in isocitrate dehydrogenase 2 (IDH2)-deficient endothelial cells, and to investigate the effect of ulinastatin (UTI) on this mechanism. We showed that knockdown of IDH2 induced SDC2 expression in human umbilical vein endothelial cells (HUVECs). Matrix metalloproteinase 7 (MMP7) influences SDC2 expression. When IDH2 was downregulated, MMP7 expression was increased, as was TGF-β signaling, which regulates MMP7. Inhibition of MMP7 activity using MMP inhibitor II significantly reduced SDC2, suggesting that IDH2 mediated SDC2 expression via MMP7. Moreover, expression of SDC2 and MMP7, as well as TGF-β signaling, increased in response to IDH2 deficiency, and treatment with UTI reversed this increase. Similarly, the increase in SDC2, MMP7, and TGF-β signaling in the aorta of IDH2 knockout mice was reversed by UTI treatment. These findings suggest that IDH2 deficiency induces SDC2 expression via TGF-β and MMP7 signaling in endothelial cells.

MicroRNAs expression influence in ulcerative colitis and Crohn's disease: A pilot study for the identification of diagnostic biomarkers

BACKGROUND

Inflammatory bowel disease (IBD) comprises two distinct diseases, Crohn’s disease (CD) and ulcerative colitis (UC), both of which are chronic, relapsing inflammatory disorders of the gastrointestinal tract with a mostly unknown etiology. The incidence and prevalence of IBD are continually increasing, indicating the need for further studies to investigate the genetic determinants of these diseases. Since microRNAs (miRNAs) regulate protein translation via complementary binding to mRNA, discovering differentially expressed miRNAs (DE) in UC or CD patients could be important for diagnostic biomarker identification, assisting in the appropriate disease differentiation progressing the understanding of IBD pathogenesis.

AIM

To determine the miRNA expression profile in UC and CD patients and the potential pathophysiological contributions of differentially expressed miRNA.

METHODS

A total of 20 formalin-fixed paraffin-embedded colonic samples were collected from the Pathology Department of Botucatu Medical School at São Paulo State University (Unesp). The diagnosis of UC or CD was based on clinical, endoscopic, radiologic, and histological criteria and confirmed by histopathological analysis at the time of selection. The TaqMan™ Array Human MicroRNA A+B Cards Set v3.0 (Applied Biosystems™) platform was used to analyze 754 miRNAs. Targets of DE-miRNAs were predicted using miRNA Data Integration Portal (mirDIP) and the miRNA Target Interaction database (MiRTarBase). All statistical analyses were conducted using GraphPad Prism software. Parametric and nonparametric data were analyzed using t-tests and Mann-Whitney U tests, respectively.

RESULTS

The results showed that of the 754 miRNAs that were initially evaluated, 643 miRNAs were found to be expressed in at least five of the patients who were diagnosed with either CD or UC; the remaining 111 miRNAs were not considered to be expressed in these patients. The expression levels of 28 miRNAs were significantly different between the CD and UC patients (P ≤ 0.05); 13 miRNAs demonstrated a fold-change in expression level greater than 1. Five miRNAs with a downregulated expression were selected for enrichment analysis. The miRNAs whose expression levels were significantly lower in UC patients than in CD patients were enriched in certain signaling pathways that were mostly correlated with cancer-related processes and respective biomarkers.

CONCLUSION

MiRNAs could be used to differentiate UC from CD, and differently expressed miRNAs could help explain the distinct pathophysiology of each disease.

Impacts of different intensities of exercise on inflammation and hypoxia markers in low altitude

Background

This study aims to determine and compare the effects of exercise modalities with different intensities on the secretion of key inflammation and hypoxia markers in amateur athletes.

Methods

Twenty-three athletes with a mean age of 20.1 years, living at low altitude (1850 m) participated in this study. The participants' maximal oxygen consumption values (VO₂ max) were determined with an incremental cycle exercise test as 54.15 ± 6.14 mL kg min⁻¹. Athletes performed four protocols: at rest, 50% VO₂ max, 75% VO₂ max and 100% VO₂ max (until exhaustion) with one-week intervals. 50% VO₂ max, 75% VO₂ max sessions were performed continuously for 30 min on a bicycle ergometer and 100% VO₂ max session was performed by cycling until exhaustion. Blood samples were obtained at rest and immediately after each exercise session. Serum tumor necrosis factor alpha (TNF-α), C-reactive protein (CRP), interleukin-10 (IL-10), and hypoxia inducible factor-1 alpha (HIF-1α) levels were measured.

Results

There were significant differences in serum TNF-α levels in 75% VO₂ max and 100% VO₂ max sessions (489.03 ± 368.37 and 472.70 ± 365.21 ng/L, respectively) compared to rest conditions (331.65 ± 293.52 ng/L). Serum CRP levels of 50% VO₂ max and 75% VO₂ max sessions (1.19 ± 0.50; 1.07 ± 0.52 mg/L) were significantly higher than the rest condition (0.74 ± 0.35 mg/L). There were significant differences in serum IL-10 levels of rest condition and 50% VO₂ max; 50% VO₂ max, and 100% VO₂ max sessions (328.09 ± 128.87; 446.36 ± 142.84; 347.44 ± 135.69; 324.88 ± 168.06 pg/mL). Serum HIF-1α levels were significantly higher in 75% VO2 max session compared to rest (1.26 ± 0.16; 1.08 ± 0.19 ng/mL) (P < 0.05 for all comparisons).

Conclusions

Both inflammatory and anti-inflammatory pathway is induced on different exercise intensities. Exercise protocols performed until exhaustion may lead to activation of inflammatory pathways and hypoxia-induced damage.

Drivers of transcriptional variance in human intestinal epithelial organoids

Human intestinal epithelial organoids (enteroids and colonoids) are tissue cultures used for understanding the physiology of the human intestinal epithelium. Here, we explored the effect on the transcriptome of common variations in culture methods, including extracellular matrix substrate, format, tissue segment, differentiation status, and patient heterogeneity. RNA-sequencing datasets from 276 experiments performed on 37 human enteroid and colonoid lines from 29 patients were aggregated from several groups in the Texas Medical Center. DESeq2 and gene set enrichment analysis (GSEA) were used to identify differentially expressed genes and enriched pathways. PERMANOVA, Pearson's correlation, and dendrogram analysis of the data originally indicated three tiers of influence of culture methods on transcriptomic variation: substrate (collagen vs. Matrigel) and format (3-D, transwell, and monolayer) had the largest effect; segment of origin (duodenum, jejunum, ileum, colon) and differentiation status had a moderate effect; and patient heterogeneity and specific experimental manipulations (e.g., pathogen infection) had the smallest effect. GSEA identified hundreds of pathways that varied between culture methods, such as IL1 cytokine signaling enriched in transwell versus monolayer cultures and E2F target genes enriched in collagen versus Matrigel cultures. The transcriptional influence of the format was furthermore validated in a synchronized experiment performed with various format-substrate combinations. Surprisingly, large differences in organoid transcriptome were driven by variations in culture methods such as format, whereas experimental manipulations such as infection had modest effects. These results show that common variations in culture conditions can have large effects on intestinal organoids and should be accounted for when designing experiments and comparing results between laboratories. Our data constitute the largest RNA-seq dataset interrogating human intestinal epithelial organoids.

Colocalization with MMP-7 in the Distal Colon is Crucial for Syndecan-2 Shedding in Dextran Sulfate Sodium-Induced Colitis Mice

Introduction

Syndecan-2 expression is elevated during chronic inflammation and cancer development, and its shedding is observed in cancer patients. However, it remained unknown whether inflammation triggers syndecan-2 shedding.

Methods

The colitis model was produced in C57BL/6 mice by oral administration of 2–3% dextran sulfate sodium (DSS) in the drinking water. Syndecan-2 and MMP-7 expression levels in tissues and cells were detected by real-time PCR, Western blotting, and immunohistochemistry. Shed syndecan-2 levels were detected by slot blotting. For tissue culture, colon tissues were divided into proximal, transverse, and distal parts, and incubated in culture media.

Results

In C57BL/6 mice with DSS-induced colitis, syndecan-2 shedding began to increase after week 12 of chronic inflammation and continued to increase at week 15. The level of shed syndecan-2 correlated with the colocalization of syndecan-2 and MMP-7 in distal colon tissues. The mRNA expression of IL-6 was increased specifically in trans-distal colon tissues from weeks 9 to 15. IL-6 induced syndecan-2 expression and shedding and MMP-7 expression in ex vivo-cultured distal colon tissues and adenoma cell lines derived from the distal colon. IL-6 treatment induced STAT3 phosphorylation and MMP-7 expression in DLD-1 cells. The application of MMP-7 to ex vivo-cultured colon tissues increased the shedding of syndecan-2 to the culture medium.

Conclusion

Our findings suggest that chronic inflammation induces syndecan-2 shedding via the site-specific colocalization of syndecan-2 with MMP-7 in the distal colon.

The Influence of Polysaccharides-Based Material on Macrophage Phenotypes

Macrophage polarization is a key factor in determining the success of implanted tissue engineering scaffolds. Polysaccharides (derived from plants, animals, and microorganisms) are known to modulate macrophage phenotypes by recognizing cell membrane receptors. Numerous studies have developed polysaccharide-based materials into functional biomaterial substrates for tissue regeneration and pharmaceutical application due to their immunostimulatory activities and anti-inflammatory response. They are used as hydrogel substrates, surface coatings, and drug delivery carriers. In addition to their innate immunological functions, the newly endowed physical and chemical properties, including substrate modulus, pore size/porosity, surface binding chemistry, and the mole ratio of polysaccharides in hybrid materials may regulate macrophage phenotypes more precisely. Growing evidence indicates that the sulfation pattern of glycosaminoglycans and proteoglycans expressed on polarized macrophages leads to the changes in protein binding, which may alter macrophage phenotype and influence the immune response. A comprehensive understanding of how different types of polysaccharide-based materials alter macrophage phenotypic changes can be beneficial to predict transplantation/implantation outcomes. This review focuses on recent advances in promoting wound healing and balancing macrophage phenotypes using polysaccharide-based substrates/coatings and new directions to address the limitations in the current understanding of macrophage responses to polysaccharides.

Syndecans in Inflammation at a Glance

Syndecans are transmembrane proteoglycans with heparan and chondroitin sulfate chains attached to their extracellular domain. Like many proteoglycans, they interact with a large number of ligands, such as growth factors, adhesion receptors, soluble small molecules, proteinases, and other extracellular matrix proteins to initiate downstream signaling pathways. Syndecans play a major role in inflammation, mainly by regulating leukocyte extravasation and cytokine function. At the same time, syndecans can undergo cytokine mediated changes in their expression levels during inflammation. The function of syndecans during inflammation appears to depend on the stage of inflammation, sulfation of heparan/chondroitin sulfate chains, the rate of ectodomain shedding and the solubility of the ectodomains. From the current literature, it is clear that syndecans are not only involved in the initial recruitment of pro-inflammatory molecules but also in establishing a balanced progression of inflammation. This review will summarize how cell surface and soluble syndecans regulate multiple aspects of inflammation.

Hypoxic-inflammatory responses under acute hypoxia: In Vitro experiments and prospective observational expedition trial

Induction of hypoxia-inducible-factor-1α (HIF-1α) pathway and HIF-target genes allow adaptation to hypoxia and are associated with reduced incidence of acute mountain sickness (AMS). Little is known about HIF-pathways in conjunction with inflammation or exercise stimuli under acute hypobaric hypoxia in non-acclimatized individuals. We therefore tested the hypotheses that (1) both hypoxic and inflammatory stimuli induce hypoxic-inflammatory signaling pathways in vitro, (2) similar results are seen in vivo under hypobaric hypoxia, and (3) induction of HIF-dependent genes is associated with AMS in 11 volunteers. In vitro, peripheral blood mononuclear cells (PBMCs) were incubated under hypoxic (10%/5% O₂) or inflammatory (CD3/CD28) conditions. In vivo, Interleukin 1β (IL-1β), C-X-C Chemokine receptor type 4 (CXCR-4), and C-C Chemokine receptor type 2 (CCR-2) mRNA expression, cytokines and receptors were analyzed under normoxia (520 m above sea level (a.s.l.)), hypobaric hypoxia (3883 m a.s.l.) before/after exercise, and after 24 h under hypobaric hypoxia. In vitro, isolated hypoxic (p = 0.004) or inflammatory (p = 0.006) stimuli induced IL-1β mRNA expression. CCR-2 mRNA expression increased under hypoxia (p = 0.005); CXCR-4 mRNA expression remained unchanged. In vivo, cytokines, receptors, and IL-1β, CCR-2 and CXCR-4 mRNA expression increased under hypobaric hypoxia after 24 h (all p ≤ 0.05). Of note, proinflammatory IL-1β and CXCR-4 mRNA expression changes were associated with symptoms of AMS. Thus, hypoxic-inflammatory pathways are differentially regulated, as combined hypoxic and exercise stimulus was stronger in vivo than isolated hypoxic or inflammatory stimulation in vitro.

Macelignan inhibits the inflammatory response of microglia and regulates neuronal survival

Neuroinflammation is an important pathological process of neurodegenerative diseases, and microglial contributes to chronic inflammation and neuronal loss in progressive neurodegenerative. Therefore, regulating the inflammatory response of microglia could lead to the discovery of promising treatments for neurodegenerative diseases. In this study, we investigated the effects of the nutmeg plant seed extract, macelignan, on the inflammatory response of microglia and neuronal cell survival. We detected NO and iNOS using the Griess test and Western blotting. We measured phosphoinositide 3 kinase (PI3K)/Akt expression by Western blotting. The release of NO and inflammatory cytokines and the expression of iNOS decreased in a concentration-dependent manner, with an increase in macelignan concentration. PI3K/Akt phosphorylation levels decreased in a dose-dependent manner in lipopolysaccharide (LPS)-activated microglial cells after exposure to macelignan. We also demonstrated that macelignan improved HT22 cell viability, following exposure to a microglial-conditioned medium. Furthermore, macelignan inhibited microglial cell near neurons treated with a hypoxic conditioned medium. Finally, macelignan treatment reduced the expression of p27 and cyclin D1 in neurons cultured in an LPS-activated microglia-conditioned medium. Therefore, these results imply that macelignan can inhibit the inflammatory response of microglia and regulate neuronal survival through the PI3K/Akt pathway.

Microtubule-associated protein 4 phosphorylation regulates epidermal keratinocyte migration and proliferation

Both cell migration and proliferation are indispensable parts of reepithelialization during skin wound healing, which is a complex process for which the underlying molecular mechanisms are largely unknown. Here, we identify a novel role for microtubule-associated protein 4 (MAP4), a cytosolic microtubule-binding protein that regulates microtubule dynamics through phosphorylation modification, as a critical regulator of epidermal wound repair. We showed that MAP4 phosphorylation was induced in skin wounds. In an aberrant phosphorylated MAP4 mouse model, hyperphosphorylation of MAP4 (S737 and S760) accelerated keratinocyte migration and proliferation and skin wound healing. Data from both primary cultured keratinocytes and HaCaT cells in vitro revealed the same results. The promigration and proproliferation effects of MAP4 phosphorylation depended on microtubule rearrangement and could be abolished by MAP4 dephosphorylation. We also identified p38/MAPK as an upstream regulator of MAP4 phosphorylation in keratinocytes. Our findings provide new insights into the molecular mechanisms underlying wound-associated keratinocyte migration and proliferation and identify potential targets for the remediation of defective wound healing.

Up-regulation of syndecan-2 in proximal colon correlates with acute inflammation

We previously reported that syndecan-2 expression is increased on the colonic epithelium during chronic inflammation. Here, we report that syndecan-2 exhibits a different pattern of site-specific colonic expression during acute inflammation. Syndecan-2 expression was up-regulated predominantly in the proximal colon of dextran sulfate sodium-induced colitis mice. The colitis-associated up-regulation of syndecan-2 was barely detected in Rag-1^-/- (recombination activating gene 1 knockout) mice under colitis-inducing conditions. Increased syndecan-2 expression correlated with increased levels of infiltrated CD4⁺ IL-17A⁺ T cells in the proximal colon. Serum levels of IL-17A were increased during the acute inflammatory response in normal mice but not Rag-1^-/- mice. IL-17A directly induced IL-17 receptor (IL-17RA) and syndecan-2 expression in ex vivo-cultured proximal colon tissues and adenoma cell lines from proximal colon. IL-17RA knockdown reduced the IL-17A-mediated syndecan-2 expression in SNU1235 cells. No elevation of syndecan-2 or IL-17RA was observed in colonic tissues from IL-17A^-/- mice during colitis induction. Finally, increased expression of syndecan-2 and IL-17RA was observed in the proximal colons of cecal ligation and puncture-induced sepsis mice and infectious pan colitis patients. Together, these data suggest that acute inflammation induces syndecan-2 expression predominantly in the proximal colon via IL-17A-IL-17RA signaling during the early stage of the inflammatory response and that proximal colonic syndecan-2 might be a biomarker for acute inflammation.-Hong, H., Song, H.-K., Hwang, E. S., Lee, A. R., Han, D. S., Kim, S.-E., Oh, E.-S. Up-regulation of syndecan-2 in proximal colon correlates with acute inflammation.

Hypoxia as a signal for prison breakout in cancer

PURPOSE OF REVIEW

We discuss recent discoveries in hypoxic cellular pathophysiology and explore the interplay between hypoxic malignant cells and other stromal elements. This review will provide an update on the effects of hypoxia on cancer outcomes and therapeutic resistance.

RECENT FINDINGS

Hypoxia has been discovered to be a key driver for tumor progression, both because of impacts on tumor cells and separately on the wider tumor microenvironment. The latter effects occur via epithelial mesenchymal transition, autophagy and metabolic switching. Through epithelial mesenchymal transition, hypoxia both drives metastasis and renders key target tissues receptive to metastasis. Autophagy is a double-edged sword which requires greater understanding to ascertain when it is a threat. Metabolic switching allows tumor cells to access hypoxic survival mechanisms even under normoxic conditions.Every element of the malignant stroma contributes to hypoxia-driven progression. Exosomal transfer of molecules from hypoxic tumor cells to target stromal cell types and the importance of microRNAs in intercellular communication have emerged as key themes.Antiangiogenic resistance can be caused by hypoxia-driven vasculogenic mimicry. Beyond this, hypoxia contributes to resistance to virtually all oncological treatment modalities.

SUMMARY

Recent advances have moved us closer to being able to exploit hypoxic mechanisms to overcome hypoxia-driven progression and therapy failure.

NLRP3 Inflammasome: A Possible Link Between Obesity-Associated Low-Grade Chronic Inflammation and Colorectal Cancer Development

Emerging evidence reveals that adipose tissue-associated inflammation is a main mechanism whereby obesity promotes colorectal cancer risk and progression. Increased inflammasome activity in adipose tissue has been proposed as an important mediator of obesity-induced inflammation and insulin resistance development. Chronic inflammation in tumor microenvironments has a great impact on tumor development and immunity, representing a key factor in the response to therapy. In this context, the inflammasomes, main components of the innate immune system, play an important role in cancer development showing tumor promoting or tumor suppressive actions depending on the type of tumor, the specific inflammasome involved, and the downstream effector molecules. The inflammasomes are large multiprotein complexes with the capacity to regulate the activation of caspase-1. In turn, caspase-1 enhances the proteolytic cleavage and the secretion of the inflammatory cytokines interleukin (IL)-1β and IL-18, leading to infiltration of more immune cells and resulting in the generation and maintenance of an inflammatory microenvironment surrounding cancer cells. The inflammasomes also regulate pyroptosis, a rapid and inflammation-associated form of cell death. Recent studies indicate that the inflammasomes can be activated by fatty acids and high glucose levels linking metabolic danger signals to the activation of inflammation and cancer development. These data suggest that activation of the inflammasomes may represent a crucial step in the obesity-associated cancer development. This review will also focus on the potential of inflammasome-activated pathways to develop new therapeutic strategies for the prevention and treatment of obesity-associated colorectal cancer development.

Effect of Polarization and Chronic Inflammation on Macrophage Expression of Heparan Sulfate Proteoglycans and Biosynthesis Enzymes

Heparan sulfate (HS) proteoglycans on immune cells have the ability to bind to and regulate the bioactivity more than 400 bioactive protein ligands, including many chemokines, cytokines, and growth factors. This makes them important regulators of the phenotype and behavior of immune cells. Here we review how HS biosynthesis in macrophages is regulated during polarization and in chronic inflammatory diseases such as rheumatoid arthritis, atherosclerosis, asthma, chronic obstructive pulmonary disease and obesity, by analyzing published micro-array data and mechanistic studies in this area. We describe that macrophage expression of many HS biosynthesis and core proteins is strongly regulated by macrophage polarization, and that these expression patterns are recapitulated in chronic inflammation. Such changes in HS biosynthetic enzyme expression are likely to have a significant impact on the phenotype of macrophages in chronic inflammatory diseases by altering their interactions with chemokines, cytokines, and growth factors.

Norisoboldine, a natural AhR agonist, promotes Treg differentiation and attenuates colitis via targeting glycolysis and subsequent NAD+/SIRT1/SUV39H1/H3K9me3 signaling pathway

Norisoboldine (NOR), a natural aryl hydrocarbon receptor (AhR) agonist, has been demonstrated to attenuate ulcerative colitis (UC) and induce the generation of Treg cells. Under UC condition, hypoxia widely exists in colonic mucosa, and secondary changes of microRNAs (miRs) expressions and glycolysis contribute to Treg differentiation. At present, we worked for exploring the deep mechanisms for NOR-promoted Treg differentiation in hypoxia and its subsequent anti-UC action from the angle of AhR/miR or AhR/glycolysis axis. Results showed that NOR promoted Treg differentiation in hypoxia and the effect was stronger relative to normoxia. It activated AhR in CD4⁺ T cells under hypoxic microenvironment; CH223191 (a specific AhR antagonist) and siAhR-3 abolished NOR-promoted Treg differentiation. Furthermore, the progress of glycolysis, levels of Glut1 and HK2, and expression of miR-31 rather than miR-219 and miR-490 in CD4⁺ T cells were downregulated by NOR treatment under hypoxic microenvironment. However, HK2 plasmid but not miR-31 mimic significantly interfered NOR-enhanced Treg polarization. In addition, NOR reduced NAD⁺ and SIRT1 levels, facilitated the ubiquitin-proteasomal degradation of SUV39H1 protein, and inhibited the enrichment of H3K9me3 at -1, 201 to -1,500 region of Foxp3 promoter in CD4⁺ T cells under hypoxic microenvironment, which was weakened by HK2 plasmid, CH223191, and siAhR-3. Finally, the correlation between NOR-mediated activation of AhR, repression of glycolysis, regulation of NAD⁺/SIRT1/SUV39H1/H3K9me3 signals, induction of Treg cells, and remission of colitis was confirmed in mice with DSS-induced colitis by using CH223191 and HK2 plasmid. In conclusion, NOR promoted Treg differentiation and then alleviated the development of colitis by regulating AhR/glycolysis axis and subsequent NAD⁺/SIRT1/SUV39H1/H3K9me3 signaling pathway.

Serum suPAR and syndecan-4 levels predict severity of community-acquired pneumonia: a prospective, multi-centre study

Background

Community-acquired pneumonia (CAP) is a major cause of death worldwide and occurs with variable severity. There are few studies focused on the expression of soluble urokinase-type plasminogen activator receptor (suPAR) and syndecan-4 in patients with CAP.

Methods

A prospective, multi-centre study was conducted between January 2014 and December 2016. A total of 103 patients with severe CAP (SCAP), 149 patients with non-SCAP, and 30 healthy individuals were enrolled. Clinical data were recorded for all enrolled patients. Serum suPAR and syndecan-4 levels were determined by quantitative enzyme-linked immunosorbent assay. The t test and Mann–Whitney U test were used to compare between two groups; one-way analysis of variance and the Kruskal–Wallis test were used to compare multiple groups. Correlations were assessed using Pearson and Spearman tests. Area under the curve (AUCs), optimal threshold values, sensitivity, and specificity were calculated. Survival curves were constructed and compared by log-rank test. Regression analyses assessed the effect of multiple variables on 30-day survival.

Results

suPAR levels increased in all patients with CAP, especially in severe cases. Syndecan-4 levels decreased in patients with CAP, especially in non-survivors. suPAR and syndecan-4 levels were positively and negatively correlated with severity scores, respectively. suPAR exhibited high accuracy in predicting SCAP among patients with CAP with an AUC of 0.835 (p < 0.001). In contrast, syndecan-4 exhibited poor diagnostic value for predicting SCAP (AUC 0.550, p = 0.187). The AUC for predicting mortality in patients with SCAP was 0.772 and 0.744 for suPAR and syndecan-4, respectively; the respective prediction threshold values were 10.22 ng/mL and 6.68 ng/mL. Addition of both suPAR and syndecan-4 to the Pneumonia Severity Index significantly improved their prognostic accuracy, with an AUC of 0.885. Regression analysis showed that suPAR ≥10.22 ng/mL and syndecan-4 ≤ 6.68 ng/mL were reliable independent markers for prediction of 30-day survival.

Conclusion

suPAR exhibits high accuracy for both diagnosis and prognosis of SCAP. Syndecan-4 can reliably predict mortality in patients with SCAP. Addition of both suPAR and syndecan-4 to a clinical scoring method could improve prognostic accuracy.

Trial registration

ClinicalTrials.gov, NCT03093220. Registered on 28 March 2017 (retrospectively registered).

Emerging roles of syndecan 2 in epithelial and mesenchymal cancer progression

Syndecan 2 (SDC2) belongs to a four-member family of evolutionary conserved small type I transmembrane proteoglycans consisting of a protein core to which glycosaminoglycan chains are covalently attached. SDC2 is a cell surface heparan sulfate proteoglycan, which is increasingly drawing attention for its distinct characteristics and its participation in numerous cell functions, including those related to carcinogenesis. Increasing evidence suggests that the role of SDC2 in cancer pathogenesis is dependent on cancer tissue origin rendering its use as a biomarker/therapeutic target feasible. This mini review discusses the mechanisms, through which SDC2, in a distinct manner, modulates complex signalling networks to affect cancer progression. © 2017 IUBMB Life, 69(11):824-833, 2017.