Two sensitizing oxidation products of p-phenylenediamine patch tested in patients allergic to p-phenylenediamine

p-Phenylenediamine induces immediate contact allergy and non-histaminergic itch via MRGPRX2

p-phenylenediamine (PPD) is a common component of hair dye known to induce immediate allergy, even acute dermatitis and contact dermatitis. MAS-related G protein coupled receptor-X2 (MRGPRX2) in mast cells (MCs) mediates small molecular substances-induced pseudo-allergic reactions. However, the role of MRGPRX2 in PPD-induced immediate contact allergy needs further exploration. The aim of this study was to investigate whether PPD activates MCs via MRGPRX2 and induces immediate allergies that contribute to contact dermatitis. Wild-type (WT) and kitw-sh/w-sh mice (MUT) were treated with PPD to observe local inflammation and MC degranulation in vivo. The release of inflammatory mediators was measured in vitro. Histamine 1 receptor (H1R)-/- mice were used to analyze itch type. PPD caused immediate contact allergy in WT mice, induced scratching, and local inflammatory reactions, while exhibiting minimal effects on MUT mice. PPD did not induce histamine release, but induced significant tryptase release in vivo and in vitro. PPD activated MRGPRX2 to induce MC degranulation in vitro. PPD caused immediate contact allergy in WT mice, induced scratching and local inflammatory reactions, while exhibited minimal effect on MUT mice. PPD did not induce histamine release, while induced significant tryptase release in vivo and in vitro. PPD induced immediate contact allergy by MCs activation via MRGPRX2 and lead to tryptase release. The scratching times showed no significant difference in WT mice or H1R-/- mice, which indicated PPD caused non-histaminergic itch. The results showed that PPD activated MCs via MRGPRX2 and induced immediate contact allergy, leading to the release of tryptase without monoamine release, which might induce non-histaminergic itch.

Clinical manifestations of device-related infective endocarditis in cardiac resynchronization therapy recipients

INTRODUCTION

The aim of the study was to analyse microbiological characteristics and clinical manifestations of cardiac device-related infective endocarditis (CDRIE) in cardiac resynchronization therapy (CRT) recipients, and to compare the diagnostic value of modified Duke (MDC) versus modified Duke lead criteria (MDLC; including to MDC local infection and pulmonary infection or embolism as major criteria).

MATERIAL AND METHODS

The study population comprised 765 consecutive CRT patients from a high-volume, tertiary care centre from 2002 to 2015. All patients were screened for CDRIE.

RESULTS

During a median follow-up of 1692 days (range: 457-3067) 5.36% of patients (n = 41) developed CDRIE, which was accompanied by CRT pocket infection in 17.1% (n = 7) and recurrent pulmonary infection or pulmonary embolism in 29.3% (n = 12). Fever was present in 95.1% of patients (n = 39), whereas blood cultures were positive in 65.9% (n = 27). Staphylococcus was the most prevalent pathogen in 59.3% (n = 16), Gram-negative bacteria in 25.9% (n = 7). Transoesophageal echocardiography showed intracardiac vegetations in 73.2% of patients (n = 30). Non-different pathogen types with the most common methicillin-sensitive Staphylococcus aureus were observed for early versus late CDRIE (endocarditis ≤ 6 vs. > 6 months from CRT or other device-related procedure). All 3 inflammatory markers (C-reactive protein, white blood cells, procalcitonin) were normal in 4.9% of patients (n = 2). MDC versus MDLC indicated definite CDRIE in 48.8% versus 80.5%, respectively (p = 0.003).

CONCLUSIONS

Fever is the most common symptom of CRT-related CDRIE, and transoesophageal echocardiography allows vegetations to be visualised in nearly 3/4 of patients with CDRIE. Although the most common pathogens were Staphylococci, Gram-negative bacteria accounted for a quarter of CDRIE. Modified Duke lead criteria proved superior to MDC.