RNA-seq characterization of histamine-releasing mast cells as potential therapeutic target of osteoarthritis

OBJECTIVE

Mast cells in the osteoarthritis (OA) synovium correlate with disease severity. This study aimed to further elucidate the role of mast cells in OA by RNA-Seq analysis and pharmacological blockade of the activity of histamine, a key mast cell mediator, in murine OA.

METHODS

We examined OA synovial tissues and fluids by flow cytometry, immunostaining, single-cell and bulk RNA-Seq, qPCR, and ELISA. Cetirizine, a histamine H1 receptor (H1R) antagonist, was used to treat the destabilization of the medial meniscus (DMM) mouse model of OA.

RESULTS

Flow cytometry and immunohistology analysis of OA synovial cells revealed KIT+ FcεRI+ and TPSAB1+ mast cells. Single-cell RNA-Seq of OA synovial cells identified the expression of prototypical mast cell markers KIT, TPSAB1, CPA3 and HDC, as well as distinctive markers HPGD, CAVIN2, IL1RL1, PRG2, and CKLF, confirmed by bulk RNA-Seq and qPCR. A mast cell prototypical marker expression score classified 40 OA patients into three synovial pathotypes: mast cell-high, -medium, and -low. Additionally, we detected mast cell mediators including histamine, tryptase AB1, CPA3, PRG2, CAVIN2, and CKLF in OA synovial fluids. Elevated H1R expression was detected in human OA synovium, and treatment of mice with the H1 receptor antagonist cetirizine reduced the severity and OA-related mediators in DMM.

CONCLUSION

Based on differential expression of prototypical and distinct mast cell markers, human OA joints can be stratified into mast cell-high, -medium, and -low synovial tissue pathotypes. Pharmacologic blockade of histamine activity holds the potential to improve OA disease outcome.

A review of hand-held Electrocardiogram (ECG) recording devices

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): St Barts NHS Trust

Introduction

The advent of portable hand-held devices to record an electrocardiogram (ECG) in-clinic, has the potential to streamline patient assessment in many clinical environments. These ECG technologies are able to record one to six lead ECGs and enable rapid responses to clinical situations. These devices may also have a role in reducing interdepartmental movement of patients during the COVID-19 pandemic, by facilitating a one-stop shop for clinical evaluation.  However despite their benefit, they can be more prone to artefact than a 12-lead ECG.

Purpose

To describe the currently available hand-held ECG technologies, their ease of use and diagnostic accuracy for rhythm assessment.

Method

An online review was conducted to identify new ECG technologies. Clinical colleagues were also surveyed for recommendations with respect to specifications, availability of alternative products, and informed of the inclusion /exclusion criteria. The review included devices which had built-in abnormal rhythm notification or display, were cost-effective and easy to use. Devices were automatically excluded if cutaneous skin electrodes were required, no in-built ECG display or notification, additional data transfer required to access ECG data or a high unit cost.

Results

An initial search uncovered nine devices, with five meeting inclusion /exclusion criteria. These devices were tabulated and compared predefined criteria (See table 1: ECG Technology comparisons). The analysis revealed that all devices utilised two finger placement on their recording electrodes to produce immediate ECG results – no cutaneous ECG application required. The KardiaMobile 6L™ had the largest number of beneficial features, namely multi-channel device, QTc interpretation, rapid diagnosis time and low cost. The intended use of hand-held devices is to detect AF. Four of five devices produced a snapshot ECG for rhythm identification on their display. However, AfibAlert™ devices provided an instant light alert if atrial fibrillation (AF) was detected. Instant check™, Dimitek™ and AfibAlert™ benefit from being complete stand-alone devices. In contrast, KardioMobile devices have a built-in ECG display for instant review however, they require a smart phone or tablet to store and transfer the data. These devices support a reliable internal AF algorithm to obtain a high negative predicted value to safely rule out AF. Frequent premature atrial contractions (PACs) are often difficult to distinguish from AF and can lead to high false-positive rate. Hand-held devices are prone to artefact, however accurate visual assessment able to significantly reduce the amount of ECGs deemed uninterpretable.

Conclusions

Hand-held ECG technology has potential to become a useful, cost-effective tool during patient consultations, with rapid identification of clinically important arrhythmias. However, limitations exist across providers. A pilot trial of these devices is planned to assess further.

MicroRNA-mRNA Interactions at Low Levels of Compressive Solid Stress Implicate mir-548 in Increased Glioblastoma Cell Motility

Glioblastoma (GBM) is an astrocytic brain tumor with median survival times of <15 months, primarily as a result of high infiltrative potential and development of resistance to therapy (i.e., surgical resection, chemoradiotherapy). A prominent feature of the GBM microenvironment is compressive solid stress (CSS) caused by uninhibited tumor growth within the confined skull. Here, we utilized a mechanical compression model to apply CSS (<115 Pa) to well-characterized LN229 and U251 GBM cell lines and measured their motility, morphology, and transcriptomic response. Whereas both cell lines displayed a peak in migration at 23 Pa, cells displayed differential response to CSS with either minimal (i.e., U251) or large changes in motility (i.e., LN229). Increased migration of LN229 cells was also correlated to increased cell elongation. These changes were tied to epigenetic signaling associated with increased migration and decreases in proliferation predicted via Ingenuity® Pathway Analysis (IPA), characteristics associated with tumor aggressiveness. miRNA-mRNA interaction analysis revealed strong influence of the miR548 family (i.e., mir-548aj, mir-548az, mir-548t) on differential signaling induced by CSS, suggesting potential targets for pharmaceutical intervention that may improve patient outcomes.

Dysregulated integrin αVβ3 and CD47 signaling promotes joint inflammation, cartilage breakdown, and progression of osteoarthritis

Osteoarthritis (OA) is the leading cause of joint failure, yet the underlying mechanisms remain elusive, and no approved therapies that slow progression exist. Dysregulated integrin function was previously implicated in OA pathogenesis. However, the roles of integrin αVβ3 and the integrin-associated receptor CD47 in OA remain largely unknown. Here, transcriptomic and proteomic analyses of human and murine osteoarthritic tissues revealed dysregulated expression of αVβ3, CD47, and their ligands. Using genetically deficient mice and pharmacologic inhibitors, we showed that αVβ3, CD47, and the downstream signaling molecules Fyn and FAK are crucial to OA pathogenesis. MicroPET/CT imaging of a mouse model showed elevated ligand-binding capacities of integrin αVβ3 and CD47 in osteoarthritic joints. Further, our in vitro studies demonstrated that chondrocyte breakdown products, derived from articular cartilage of individuals with OA, induced αVβ3/CD47-dependent expression of inflammatory and degradative mediators, and revealed the downstream signaling network. Our findings identify a central role for dysregulated αVβ3 and CD47 signaling in OA pathogenesis and suggest that activation of αVβ3 and CD47 signaling in many articular cell types contributes to inflammation and joint destruction in OA. Thus, the data presented here provide a rationale for targeting αVβ3, CD47, and their signaling pathways as a disease-modifying therapy.

IgE-mediated mast cell activation promotes inflammation and cartilage destruction in osteoarthritis

Osteoarthritis is characterized by articular cartilage breakdown, and emerging evidence suggests that dysregulated innate immunity is likely involved. Here, we performed proteomic, transcriptomic, and electron microscopic analyses to demonstrate that mast cells are aberrantly activated in human and murine osteoarthritic joint tissues. Using genetic models of mast cell deficiency, we demonstrate that lack of mast cells attenuates osteoarthritis in mice. Using genetic and pharmacologic approaches, we show that the IgE/FcεRI/Syk signaling axis is critical for the development of osteoarthritis. We find that mast cell-derived tryptase induces inflammation, chondrocyte apoptosis, and cartilage breakdown. Our findings demonstrate a central role for IgE-dependent mast cell activation in the pathogenesis of osteoarthritis, suggesting that targeting mast cells could provide therapeutic benefit in human osteoarthritis.

Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

Non-surgical interventions for eosinophilic oesophagitis

BACKGROUND

Patients with eosinophilic oesophagitis (EO) present with difficulty swallowing, vomiting, regurgitation, chest and/or abdominal pain. People with EO frequently fail to respond to treatment with gastric acid suppressants or anti-reflux surgery.

OBJECTIVES

To evaluate the benefits and harms of medical interventions for eosinophilic oesophagitis.

SEARCH STRATEGY

We searched the Cochrane Upper Gastrointestinal and Pancreatic Diseases Group trials register (The Cochrane Library Issue 1, 2004), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2004), MEDLINE (1966 to February 2004) and EMBASE (1980 to February 2004).

SELECTION CRITERIA

Randomised controlled trials were included if they compared a medical or dietary intervention for eosinophilic oesophagitis with a placebo or one medical intervention with another medical intervention.

DATA COLLECTION AND ANALYSIS

Two reviewers independently screened the title of abstracts.

MAIN RESULTS

No completed RCTs were found in the published literature. We found one abstract reporting preliminary data from an RCT (not completed) comparing oral prednisolone with topical (swallowed metered dose) fluticasone in children. In this study (50 children enrolled to date) healing rates of oesophagitis and symptom resolution with fluticasone were similar to those with prednisolone. For another ongoing RCT, comparing the efficacy of swallowed fluticasone with placebo for eosinophilic oesophagitis in males and females aged 3 to 21 years no results are available.

REVIEWERS' CONCLUSIONS

The lack of completed RCT's makes it impossible to compare the relative benefits and harms of the wide range of medical interventions currently used for treating EO. Published case series suggest that an elemental diet, oral steroids and topical steroids all offer some benefits. However, lack of a comparison group in these studies makes it impossible to evaluate the effect of these interventions.

Anthracycline antibiotic blockade of SV40 T antigen helicase action

We previously showed that anthracycline antibiotics potently block SV40 large T antigen helicase; in the present study, we describe the kinetics and the structure-activity characteristics of this process. The concentration vs effect data for helicase blockade were fitted by the Hill equation to yield nearly parallel log-concentration effect curves for a series of active anthracycline antibiotics. The effective concentration for 50% helicase blockade (EC50) values ranged from 0.34 microM for daunorubicin to 40.8 microM for 3'-deaminodaunorubicin. Clinically inactive 3'-N-acyl anthracyclines produced no blockade. The Hill constants for the blockade ranged from 1.1 to 1.6 for the entire series of active anthracyclines, indicating no positive cooperativity and suggesting that a single molecule of bound drug is sufficient to block helicase action. The EC50 values for several clinically effective anthracyclines showed a relationship to the average DNA binding constants for these drugs, and Lineweaver-Burk analysis of the blockade kinetics indicated non-competitive inhibition. The kinetics of the blockade indicated that the anthracycline, DNA, and helicase form a ternary complex that is irreversible under the reaction conditions. This mechanism may be central to the cytotoxic and anti-cancer activities of anthracycline antibiotics and may be useful in understanding the enzymatic mechanism of DNA helicase action.