The NF-kappaB inhibitor pyrrolidine dithiocarbamate blocks IL-1beta induced hyaluronan synthase 1 (HAS1) mRNA transcription, pointing at NF-kappaB dependence of the gene HAS1

Hyaluronic acid metabolism and chemotherapy resistance: recent advances and therapeutic potential

Hyaluronic acid (HA) is a major component of the extracellular matrix, providing essential mechanical scaffolding for cells and, at the same time, mediating essential biochemical signals required for tissue homeostasis. Many solid tumors are characterized by dysregulated HA metabolism, resulting in increased HA levels in cancer tissues. HA interacts with several cell surface receptors, such as cluster of differentiation 44 and receptor for hyaluronan-mediated motility, thus co-regulating important signaling pathways in cancer development and progression. In this review, we describe the enzymes controlling HA metabolism and its intracellular effectors emphasizing their impact on cancer chemotherapy resistance. We will also explore the current and future prospects of HA-based therapy, highlighting the opportunities and challenges in the field.

Gene expression profiles in COVID-19-associated tracheal stenosis indicate persistent anti-viral response and dysregulated retinol metabolism

INTRODUCTION

Coronavirus disease 2019 (COVID-19)-associated tracheal stenosis (COATS) may occur as a result of prolonged intubation during COVID-19 infection. We aimed to investigate patterns of gene expression in the tracheal granulation tissue of patients with COATS, leverage gene expression data to identify dysregulated cellular pathways and processes, and discuss potential therapeutic options based on the identified gene expression profiles.

METHODS

Adult patients (age ≥ 18 years) presenting to clinics for management of severe, recalcitrant COATS were included in this study. RNA sequencing and differential gene expression analysis was performed with transcriptomic data for normal tracheal tissue being used as a control. The top ten most highly upregulated and downregulated genes were identified. For each of these pathologically dysregulated genes, we identified key cellular pathways and processes they are involved in using Gene Ontology (GO) and KEGG (Kyoto Encyclopedia of Genes and Genomes) applied via Database for Annotation, Visualization, and Integrated Discovery (DAVID).

RESULTS

Two women, aged 36 years and 37 years, were included. The profile of dysregulated genes indicated a cellular response consistent with viral infection (CXCL11, PI15, CCL8, DEFB103A, IFI6, ACOD1, and DEFB4A) and hyperproliferation/hypergranulation (MMP3, CASP14 and HAS1), while downregulated pathways included retinol metabolism (ALDH1A2, RBP1, RBP4, CRABP1 and CRABP2).

CONCLUSION

Gene expression changes consistent with persistent viral infection and dysregulated retinol metabolism may promote tracheal hypergranulation and hyperproliferation leading to COATS. Given the presence of existing literature highlighting retinoic acid's ability to favorably regulate these genes, improve cell-cell adhesion, and decrease overall disease severity in COVID-19, future studies must evaluate its utility for adjunctive management of COATS in animal models and clinical settings.

Hyaluronan and Reactive Oxygen Species Signaling—Novel Cues from the Matrix?

Hyaluronan (HA) is a naturally occurring non-sulfated glycosaminoglycan (GAG) localized to the cell surface and the tissue extracellular matrix (ECM). It is composed of disaccharides containing glucuronic acid and N-acetylglucosamine, is synthesized by the HA synthase (HAS) enzymes and is degraded by hyaluronidase (HYAL) or reactive oxygen and nitrogen species (ROS/RNS) actions. HA is deposited as a high molecular weight (HMW) polymer and degraded to low molecular weight (LMW) fragments and oligosaccharides. HA affects biological functions by interacting with HA-binding proteins (hyaladherins). HMW HA is anti-inflammatory, immunosuppressive, and antiangiogenic, whereas LMW HA has pro-inflammatory, pro-angiogenetic, and oncogenic effects. ROS/RNS naturally degrade HMW HA, albeit at enhanced levels during tissue injury and inflammatory processes. Thus, the degradation of endothelial glycocalyx HA by increased ROS challenges vascular integrity and can initiate several disease progressions. Conversely, HA exerts a vital role in wound healing through ROS-mediated HA modifications, which affect the innate immune system. The normal turnover of HA protects against matrix rigidification. Insufficient turnover leads to increased tissue rigidity, leading to tissue dysfunction. Both endogenous and exogenous HMW HA have a scavenging capacity against ROS. The interactions of ROS/RNS with HA are more complex than presently perceived and present an important research topic.

PD-L1 Inhibits T Cell-Induced Cytokines and Hyaluronan Expression via the CD40-CD40L Pathway in Orbital Fibroblasts From Patients With Thyroid Associated Ophthalmopathy

Thyroid associated ophthalmopathy (TAO), characterized by T cell infiltration and orbital fibroblast activation, is an organ-specific autoimmune disease which is still short of effective and safety therapeutic drugs. The PD-1/PD-L1 pathway has been reported hindering the progression of Graves’ disease to some extent by inhibiting T cell activity, and tumor therapy with a PD-1 inhibitor caused some adverse effects similar to the symptoms of TAO. These findings suggest that the PD-1/PD-L1 pathway may be associated with the pathogenesis of TAO. However, it remains unknown whether the PD-1/PD-L1 pathway is involved in orbital fibroblast activation. Here, we show that orbital fibroblasts from patients with TAO do not express PD-L1. Based on in vitro OF-T cell co-culture system, exogenous PD-L1 weakens T cell-induced orbital fibroblast activation by inhibiting T cell activity, resulting in reduced production of sICAM-1, IL-6, IL-8, and hyaluronan. Additionally, exogenous PD-L1 treatment also inhibits the expression of CD40 and the phosphorylation levels of MAPK and NF-κB pathways in orbital fibroblasts of the OF-T cell co-culture system. Knocking down CD40 with CD40 siRNA or down-regulating the phosphorylation levels of MAPK and NF-κB pathways with SB203580, PD98059, SP600125, and PDTC can both reduce the expression of these cytokines and hyaluronan. Our study demonstrates that the orbital immune tolerance deficiency caused by the lack of PD-L1 in orbital fibroblasts may be one of the causes for the active orbital inflammation in TAO patients, and the utilization of exogenous PD-L1 to reconstruct the orbital immune tolerance microenvironment may be a potential treatment strategy for TAO.

Expression of genes involved in the NF-κB-dependent pathway of the fibrosis in the mare endometrium

Equine endometrosis is a multifactorial chronic degenerative condition, considered to be one of a major causes of equine infertility. The formation of periglandular fibrosis seems to be linked to chronic inflammation of the mare endometrium in a paracrine way and in a response to numerous forms of inflammatory stimuli elicit the net deposition of extracellular matrix (ECM) around the endometrial glands and stroma. We hypothesized some of these stimuli, such as monocyte chemoattractant protein-1 (MCP-1), interleukin-6 (IL-6), and hyaluronan synthases (HASs), may share the nuclear factor-κB (NF-κB) dependent activation pathway. This study aimed to determine whether mRNA expression of MCP-1, IL-6, HASs, and proteins of canonical (RelA/NK-κβ1) and noncanonical (NK-κβ2) signaling pathways for NF-kB would change in subsequent categories of endometrosis during the estrous cycle. The expression of selected genes was established in mare endometrium (n = 80; Kenney and Doig categories I, IIA, IIB, III), obtained in the follicular phase (FLP) and mid-luteal phase (MLP). The high expression of RelA mRNA was observed in III, whereas of NK-κβ1 and NK-κβ2 also in IIA, and IIA and IIB, respectively. The expression of MCP-1 mRNA occurred constantly, regardless of the category, whereas IL-6 mRNA was low in IIA, IIB, and III. The expression of HAS 1 was high in IIA and HAS 3 in IIA, IIB, and III. All those changes were observed in FLP, but not MLP. Our results suggest that NF-κB may be involved in progression of the chronic degenerative condition of the mare endometrium, on both canonical and noncanonical pathways. The most important changes in target genes expression were observed only in FLP, which may suggest the hormone-dependent activation of the NF-κB-dependent fibrosis pathway.

Contact allergen (PPD and DNCB)-induced keratinocyte sensitization is partly mediated through a low molecular weight hyaluronan (LMWHA)/TLR4/NF-κB signaling axis

Allergic contact dermatitis (ACD) is caused by topical exposure to chemical allergens. Keratinocytes play a key role in innate immunity, as well as in ACD progression. The transmembrane Toll-like receptor 4 (TLR4), strongly implicated in skin inflammation, has the ability to bind Damage Associated Molecular Patterns (DAMPs), like Low Molecular Weight Hyaluronan (LMWHA). Previously, we had determined that p-phenylenediamine (PPD) and 2,4-dinitrochlorobenzene (DNCB) modulate keratinocyte HA deposition in a manner correlated to their sensitization. In the present study, we aimed to investigate putative co-operation of HA and TLR4 in the process of PPD and DNCB-induced keratinocyte activation. Contact sensitizers were shown to significantly increase the expression of Hyaluronan Synthases (HAS) and TLR4 in NCTC2544 human keratinocytes, as demonstrated by western blot and Real-Time PCR. These data, in correlation to earlier shown enhanced HA degradation suggest that the contact sensitizers facilitate HA turnover of keratinocytes and increase the release of pro-inflammatory, LMWHA fragments. Treatment with exogenous LMWHA enhanced TLR4, HAS levels and Nuclear factor-kappa beta (NF-κΒ) activation. PPD, DNCB and LMWHA-effects were shown to be partly executed through TLR4 downstream signaling as shown by Real-Time, western blot, siRNA and confocal microscopy approaches. Specifically, PPD and DNCB stimulated the activation of the TLR4 downstream mediator NF-κB. Therefore, the shown upregulation of TLR4 expression is suggested to further facilitate the release of endogenous, bioactive HA fragments and sustain keratinocyte activation. In conclusion, keratinocyte contact allergen-dependent sensitization is partly mediated through a LMWHA/TLR4/ NF-κB signaling axis.

Interaction with hyaluronan matrix and miRNA cargo as contributors for in vitro potential of mesenchymal stem cell-derived extracellular vesicles in a model of human osteoarthritic synoviocytes

BACKGROUND

Osteoarthritis (OA) is the most prevalent joint disease, and to date, no options for effective tissue repair and restoration are available. With the aim of developing new therapies, the impact of mesenchymal stem cells (MSCs) has been explored, and the efficacy of MSCs started to be deciphered. A strong paracrine capacity relying on both secreted and vesicle-embedded (EVs) protein or nucleic acid-based factors has been proposed as the principal mechanism that contributes to tissue repair. This work investigated the mechanism of internalization of extracellular vesicles (EVs) released by adipose-derived MSCs (ASCs) and the role of shuttled miRNAs in the restoration of homeostasis in an in vitro model of human fibroblast-like synoviocytes (FLSs) from OA patients.

METHODS

ASC-EVs were isolated by differential centrifugation and validated by flow cytometry and nanoparticle tracking analysis. ASC-EVs with increased hyaluronan (HA) receptor CD44 levels were obtained culturing ASCs on HA-coated plastic surfaces. OA FLSs with intact or digested HA matrix were co-cultured with fluorescent ASC-EVs, and incorporation scored by flow cytometry and ELISA. ASC-EV complete miRNome was deciphered by high-throughput screening. In inflamed OA FLSs, genes and pathways potentially regulated by ASC-EV miRNA were predicted by bioinformatics. OA FLSs stimulated with IL-1β at physiological levels (25 pg/mL) were treated with ASC-EVs, and expression of inflammation and OA-related genes was measured by qRT-PCR over a 10-day time frame with modulated candidates verified by ELISA.

RESULTS

The data showed that HA is involved in ASC-EV internalization in FLSs. Indeed, both removal of HA matrix presence on FLSs and modulation of CD44 levels on EVs affected their recruitment. Bioinformatics analysis of EV-embedded miRNAs showed their ability to potentially regulate the main pathways strictly associated with synovial inflammation in OA. In this frame, ASC-EVs reduced the expression of pro-inflammatory cytokines and chemokines in a chronic model of FLS inflammation.

CONCLUSIONS

Given their ability to affect FLS behavior in a model of chronic inflammation through direct interaction with HA matrix and miRNA release, ASC-EVs confirm their role as a novel therapeutic option for osteoarthritic joints.

Hyaluronan synthase 1: a mysterious enzyme with unexpected functions

Hyaluronan synthase 1 (HAS1) is one of three isoenzymes responsible for cellular hyaluronan synthesis. Interest in HAS1 has been limited because its role in hyaluronan production seems to be insignificant compared to the two other isoenzymes, HAS2 and HAS3, which have higher enzymatic activity. Furthermore, in most cell types studied so far, the expression of its gene is low and the enzyme requires high concentrations of sugar precursors for hyaluronan synthesis, even when overexpressed in cell cultures. Both expression and activity of HAS1 are induced by pro-inflammatory factors like interleukins and cytokines, suggesting its involvement in inflammatory conditions. Has1 is upregulated in states associated with inflammation, like atherosclerosis, osteoarthritis, and infectious lung disease. In addition, both full length and splice variants of HAS1 are expressed in malignancies like bladder and prostate cancers, multiple myeloma, and malignant mesothelioma. Interestingly, immunostainings of tissue sections have demonstrated the role of HAS1 as a poor predictor in breast cancer, and is correlated with high relapse rate and short overall survival. Utilization of fluorescently tagged proteins has revealed the intracellular distribution pattern of HAS1, distinct from other isoenzymes. In all cell types studied so far, a high proportion of HAS1 is accumulated intracellularly, with a faint signal detected on the plasma membrane and its protrusions. Furthermore, the pericellular hyaluronan coat produced by HAS1 is usually thin without induction by inflammatory agents or glycemic stress and depends on CD44–HA interactions. These specific interactions regulate the organization of hyaluronan into a leukocyte recruiting matrix during inflammatory responses. Despite the apparently minor enzymatic activity of HAS1 under normal conditions, it may be an important factor under conditions associated with glycemic stress like metabolic syndrome, inflammation, and cancer.

Astrocytes in aged nonhuman primate brain gray matter synthesize excess hyaluronan

The glycosaminoglycan hyaluronan (HA) accumulates in central nervous system lesions where it limits astrogliosis but also inhibits oligodendrocyte progenitor cell (OPC) maturation. The role of hyaluronan in normative brain aging has not been previously investigated. Here, we tested the hypothesis that HA accumulates in the aging nonhuman primate brain. We found that HA levels significantly increase with age in the gray matter of rhesus macaques. HA accumulation was linked to age-related increases in the transcription of HA synthase-1 (HAS1) expressed by reactive astrocytes but not changes in the expression of other HAS genes or hyaluronidases. HA accumulation was accompanied by increased expression of CD44, a transmembrane HA receptor. Areas of gray matter with elevated HA in older animals demonstrated increased numbers of olig2(+) OPCs, consistent with the notion that HA may influence OPC expansion or maturation. Collectively, these data indicate that HAS1 and CD44 are transcriptionally upregulated in astrocytes during normative aging and are linked to HA accumulation in gray matter.

Proinflammatory cytokines induce hyaluronan synthesis and monocyte adhesion in human endothelial cells through hyaluronan synthase 2 (HAS2) and the nuclear factor-kappaB (NF-kappaB) pathway

Chronic inflammation is now accepted to have a critical role in the onset of several diseases as well as in vascular pathology, where macrophage transformation into foam cells contributes in atherosclerotic plaque formation. Endothelial cells (EC) have a critical function in recruitment of immune cells, and proinflammatory cytokines drive the specific expression of several adhesion proteins. During inflammatory responses several cells produce hyaluronan matrices that promote monocyte/macrophage adhesion through interactions with the hyaluronan receptor CD44 present on inflammatory cell surfaces. In this study, we used human umbilical chord vein endothelial cells (HUVECs) as a model to study the mechanism that regulates hyaluronan synthesis after treatment with proinflammatory cytokines. We found that interleukin 1beta and tumor necrosis factors alpha and beta, but not transforming growth factors alpha and beta, strongly induced HA synthesis by NF-kappaB pathway. This signaling pathway mediated hyaluronan synthase 2 (HAS2) mRNA expression without altering other glycosaminoglycan metabolism. Moreover, we verified that U937 monocyte adhesion on stimulated HUVECs depends strongly on hyaluronan, and transfection with short interference RNA of HAS2 abrogates hyaluronan synthesis revealing the critical role of HAS2 in this process.

CD44 deficiency attenuates chronic murine ileitis

BACKGROUND & AIMS

Lymphocyte recruitment to sites of inflammation requires the sequential engagement of adhesion molecules and chemokine receptors. In the current studies we analyzed the role of CD44 for the development of chronic small-intestinal inflammatory infiltrates in vivo.

METHODS

By using a tumor necrosis factor (TNF)-driven model of chronic ileitis (ie, B6.129P-TNF(DeltaAU-rich element [ARE])) that recapitulates many features of Crohn's disease, we noticed dynamic changes in the expression and functional state of CD44 and its ligand hyaluronan via enzyme-linked immunosorbent assay, real-time reverse-transcription polymerase chain reaction, immunohistochemistry, and flow cytometry. In addition, we assessed the role of lymphocyte populations during induction of ileitis through adoptive transfer studies, and generated CD44-deficient TNFDeltaARE mice to assess the role of CD44 for development of ileitis.

RESULTS

Soluble hyaluronan levels and expression of hyaluronan synthase-1 were increased in TNFDeltaARE mice. This coincided with increased expression of CD44 (including variant 7) and reactivity towards hyaluronan on CD4(+) T cells. CD44 was spatially colocalized with the gut-homing integrin alpha(4)beta(7), spatially linking lymphocyte rolling with arrest. These cells had an effector phenotype because they lacked L-selectin and a higher proportion in diseased mice produced TNF and interleukin-2 compared with wild-type littermates. Lastly, CD4(+) but not CD8(+) T cells conferred ileitis to RAG(-/-) recipients and deficiency of one or both alleles of the CD44 gene resulted in attenuation of the severity of ileitis in TNFDeltaARE mice.

CONCLUSIONS

Our findings support an important role of CD44 expressed by CD4(+) and CD8(+) for development of ileitis mediated by TNF overproduction.

Changes in cytokine signaling and extracellular matrix production induced by inflammatory factors in cultured vocal fold fibroblasts

OBJECTIVES

Modulating cytokine signaling in vocal fold fibroblasts after injury may influence extracellular matrix (ECM) production and eventual fibrotic outcome. To evaluate previously established in vivo cytokine and ECM gene expression hypotheses, we examined in vitro vocal fold fibroblast responses to exogenous inflammatory factor stimulation.

METHODS

Rat vocal fold fibroblast lines derived from explants were separately treated with interleukin-13 (IL-13), interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), transforming growth factor beta subtype 1 (TGF-beta1), or prostaglandin E2 (PGE2). We examined the in vitro messenger RNA expression profiles of IL-1beta, IFN-gamma, TNF-alpha, TGF-beta1, and cyclooxygenase 2 (COX-2), as well as those of hyaluronic acid synthase (HAS) 1, HAS-2, procollagen subtype 1, and procollagen subtype 3, at 1,4, 8, 16, 24, and 72 hours after treatment, and compared them to those of untreated fibroblasts and in vivo data, using real-time reverse transcription-polymerase chain reaction.

RESULTS

IL-1beta and TNF-alpha induced each other and synergistically increased HAS-1 and HAS-2 expression. PGE2 also up-regulated HAS-1 and HAS-2 expression. IFN-gamma, IL-1beta, TNF-alpha, and TGF-beta1 up-regulated HAS expression alongside either transient up-regulation of, or no change in, procollagen 1 and 3 expression. Most treatments appeared to suppress procollagen expression, possibly through HAS up-regulation. All inflammatory factors attenuated TGF-beta1 expression.

CONCLUSIONS

These results confirm several in vivo trends, identify potential cytokine pathways and therapeutic candidates, and suggest the utility of this in vitro setup for future studies.

Hyaluronan and hyaluronidase in genitourinary tumors

Genitourinary cancers are the most frequently diagnosed cancers in men and the fifth most common in women. Management of disease through accurate and cost effective early diagnostic markers, as well as identification of valid prognostic indicators, has contributed significantly to improved treatment outcomes. In this review, we will discuss the function, regulation and clinical utility of hyaluronan (HA), genes encoding its metabolic enzymes and receptors that mediate its cellular effects. Specific HA synthase (HAS) and hyaluronidase (HAase) genes encode the enzymes that produce HA polymers and oligosaccharides, respectively. Differential effects of these enzymes in progression of genitourinary tumors are determined by the relative balance between HAS and HAase levels, as well as the distribution of receptors. The genes are regulated in a complex fashion at the transcriptional and post-translational levels, but also by epigenetic events, alternative mRNA splicing, and subcellular localization. Importantly, the major tumor-derived HAase enzyme, HYAL-1, either alone or together with HA, is an accurate diagnostic and prognostic marker for genitourinary tumors.