Hypersensitivity Reactions to Components of Cardiac Implantable Electronic Devices and Their Treatment: A Systematic Review

Background: Hypersensitivity reactions (HSRs) to components of cardiac implantable electronic devices (CIEDs) are rare but difficult to differentiate from device infection. Data on best management strategies of HSRs to CIEDs are lacking. The aims of this systematic review are to summarise the available literature on the aetiology, diagnosis and management of HSR in CIED patients and to provide guidance on best management strategies for these patients. Methods and results: A systematic search for publications on HSR to CIED in PubMed from January 1970 to November 2022 was conducted, resulting in 43 publications reporting on 57 individual cases. The quality of data was low. The mean age was 57 ± 21 years, and 48% of patients were women. The mean time from implant to diagnosis was 29 ± 59 months. Multiple allergens were identified in 11 patients (19%). In 14 cases (25%) no allergen was identified. Blood tests were mostly normal (55%), but eosinophilia (23%), raised inflammatory markers (18%) and raised immunoglobulin E (5%) were also encountered. Symptoms included local reactions, systemic reactions or both in 77%, 21% and 7% of patients, respectively. Explantation of CIED and reimplantation of another CIED coated with a non-allergenic material was usually successful. Use of topical or systemic steroids was associated with high failure rates. Conclusion: Based on the limited data available, the treatment of choice for HSRs to CIEDs is full CIED removal, reassessment of CIED indication and reimplantation of devices coated in non-allergenic materials. Steroids (topical/systemic) have limited efficiency and should not be used. There is an urgent need for further research in this field.

Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties

In this paper, we present the idea and development of a new gold-copper-zinc-germanium (AuCuZnGe) alloy, which is related to the method of production and research of its key properties, so that the new Au alloy could be used for jewelry production and in dental technology. The research design was associated with the determination of appropriate chemical composition, manufacturing technology, and performing the characterization. Melting and casting technologies were used to cast the AuCuZnGe alloy while rolling was used to prepare the cylinders and cutting to make square plates with a = 10 mm and thickness of 1 mm. Such plates were provided for corrosion testing. Observation of the plate′s microstructure was performed with Scanning Electron Microscopy (SEM) equipped by Energy-Dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD). Corrosion testing involved performing the following measurements: Polarization, the open circuit potentials, and linear polarization resistance. Based on the SEM, EDS, XRD, and results of corrosion testing it can be concluded that the new AuCuZnGe alloy possesses high corrosion stability and can be classified as a high noble alloy.

Nickel Hypersensitivity to Atrial Septal Occluders: Smoke Without Fire?

Nickel is one of the most common contact allergens worldwide; it is used as the main component of the devices used for atrial septal defects (ASDs) and patent foramen ovale (PFO) closure. Developing nickel hypersensitivity after PFO/ASD occlusion is significantly rarer described in medical literature than typical nickel contact sensitization. The exact pathophysiological mechanism of this "device syndrome" remains unknown, and many question the real incidence or even the existence of this clinical entity. Nevertheless, it has been associated with a wide spectrum of symptoms, including chest pain, migraines, palpitation, and dyspnea. Skin patch tests are the first-line approach to diagnose nickel hypersensitivity. However, diagnostic criteria for the device syndrome have not been developed, and diagnosis in reported cases is established by a process of elimination. Management-drug therapy (corticosteroids, clopidogrel, etc.) or even surgical explantation in severe cases-of patients developing such clinical manifestations after percutaneous PFO/ASD occlusion is empirical. Undoubtedly, endocardiac device-related nickel hypersensitivity requires more focused research to discover the underlying mechanism as well as to develop reliable prognostic tests for detecting high-risk patients and preventing severe nickel hypersensitivity reactions.

Epidemics of Dermatitis

Allergic contact dermatitis (ACD) remains a globally prevalent disease for both children and adults. The silent ACD epidemic continues to be fueled by the introduction of novel allergens in industrial and household products and the continued presence of known allergens. In 1997, Allan Dillarstone noted a sinusoidal pattern to epidemics when allergenic preservatives were replaced by alternative chemicals within the market, which then similarly increased in allergenicity. A call for public health vigilance and prevention initiatives is needed to intervene in the ACD epidemic.

Nickel release from metallic earrings: A survey of the Danish market and validation of the nickel spot test

BACKGROUND

Exposure to nickel-releasing ear-piercing jewellery may explain the persistently high prevalence of nickel allergy in Europe. While nickel release from earrings is regulated, field studies show that the regulation is not always respected. More knowledge is needed regarding the risk of piercing exposure including suitable screening methods.

OBJECTIVE

To examine the proportion of earrings on the Danish market that release more nickel than allowed, and to validate the use of the dimethylglyoxime (DMG) test as a screening tool.

METHODS

A total of 304 earrings were purchased and tested with the DMG test and X-ray fluorescence spectrometry. The level of nickel release was quantified in a selected subsample of 100 earrings by the European reference test EN 1811. The DMG spot test was validated against EN 1811 at different thresholds.

RESULTS

Excessive nickel release according to the European regulation was found in 45 (14.8%) tested earrings. The sensitivity of the DMG test decreased with reduced levels of nickel release (sensitivity of 45.2% at ≥0.2 μg/cm2 /week vs 61.1% at >0.5 μg/cm2 /week).

CONCLUSION

Excessive nickel release is common in earrings on the Danish market. Because of low sensitivity, the DMG test has limited use in screening of earrings for research but may still be used clinically.

Changing trends of contact allergens: A 40-year retrospective study from a referral centre in northern Taiwan

BACKGROUND

The common contact allergens may change over time as the environmental exposure changes.

OBJECTIVES

To identify the prevalence rates and changing trends of contact allergens in Taiwan over a 40-year period.

MATERIALS & METHODS

The patch testing results of a referral centre from 1978 to 2018 were retrospectively reviewed. The study population was divided into four groups according to 10-year intervals. The prevalence rates of contact sensitization to each agent and the clinical relevance were analysed. For patients with positive reactions to relevant allergens, the occupations and sites of dermatitis were analysed.

RESULTS

From 1978 to 2018, a total of 4005 patients underwent patch testing. Successively increasing trends of positive reactions to cobalt, fragrance mix I, and para-phenylenediamine (PPD) were found. Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) was an emerging contact allergen. Hairdressers, cosmetologists, and aromatherapists became the occupations most commonly having positive reactions in the most recent 10 years. In the first two decades, the face and neck were the most commonly affected areas. Later, hands became the most commonly affected sites.

CONCLUSIONS

The prevalence rates of positive reactions to cobalt, fragrance mix I, and PPD increased successively. MCI/MI was an emerging contact allergen of special concern.

Pediatric allergic contact dermatitis. Part 2: Patch testing series, procedure, and unique scenarios

Patch testing is the criterion standard for diagnosing allergic contact dermatitis. Causative allergens differ between children and adults, necessitating the development of pediatric-specific patch test series. The Pediatric Baseline Series was developed in 2018 through expert consensus and includes relevant pediatric allergens that dermatologists can use in practice. Obstacles in patch testing, such as the need for multiple office visits, length of patch application, and avoidance of sweat and water on the testing area, are particularly challenging for the pediatric population, and several strategies are proposed. Aside from formal patch testing, alternatives like the repeat open application test and empiric allergen avoidance can be helpful in children. The key to management of allergic contact dermatitis is allergen avoidance, with emphasis on the need to properly identify causative allergens. Continued data collection through registries allows for a better understanding of the diagnosis and management of pediatric allergic contact dermatitis.

Heavy metals and the skin: Sensitization patterns in Lithuanian metalworkers

BACKGROUND

Metalworkers are exposed to many sensitizing and irritant substances. There are no published data on contact allergy in this population in the Baltic countries.

OBJECTIVES

To detect skin symptoms related to occupational exposure and to describe the reactivity pattern to the European baseline series in workers from two metal plants in Lithuania.

METHODS

In this cross-sectional study 185 metalworkers (154 production workers and 31 office staff) filled an interviewer-administered questionnaire. Patch testing was performed in 135 metalworkers and office staff, as a control group.

RESULTS

Metalworkers younger than 40 years complained statistically significantly more often of skin symptoms, especially on the hands and face, than older workers. Physician-diagnosed skin diseases were reported in 1.7% of cases. Metalworkers, working <20 years in the factory, more often had skin symptoms. Contact with chemicals at the workplace was suspected as the main factor provoking skin symptoms. Metalworkers were sensitized mainly to cobalt, and nickel was the most prevalent allergen among office staff.

CONCLUSION

Younger metalworkers more often had skin symptoms suspected of being work-related compared to older ones. Sensitization to cobalt was more prevalent in the metalworkers than in the control group.

A scoping review to identify strategies that work to prevent four important occupational diseases

BACKGROUND

Despite being largely preventable, many occupational diseases continue to be highly prevalent and extremely costly. Effective strategies are required to reduce their human, economic, and social impacts.

METHODS

To better understand which approaches are most likely to lead to progress in preventing noise-related hearing loss, occupational contact dermatitis, occupational cancers, and occupational asthma, we undertook a scoping review and consulted with a number of key informants.

RESULTS

We examined a total of 404 articles and found that various types of interventions are reported to contribute to occupational disease prevention but each has its limitations and each is often insufficient on its own. Our principal findings included: legislation and regulations can be an effective means of primary prevention, but their impact depends on both the nature of the regulations and the degree of enforcement; measures across the hierarchy of controls can reduce the risk of some of these diseases and reduce exposures; monitoring, surveillance, and screening are effective prevention tools and for evaluating the impact of legislative/policy change; the effect of education and training is context-dependent and influenced by the manner of delivery; and, multifaceted interventions are often more effective than ones consisting of a single activity.

CONCLUSIONS

This scoping review identifies occupational disease prevention strategies worthy of further exploration by decisionmakers and stakeholders and of future systematic evaluation by researchers. It also identified important gaps, including a lack of studies of precarious workers and the need for more studies that rigorously evaluate the effectiveness of interventions.

Nickel Allergic Contact Dermatitis: Identification, Treatment, and Prevention

Nickel is a ubiquitous metal added to jewelry and metallic substances for its hardening properties and because it is inexpensive. Estimates suggest that at least 1.1 million children in the United States are sensitized to nickel. Nickel allergic contact dermatitis (Ni-ACD) is the most common cutaneous delayed-type hypersensitivity reaction worldwide. The incidence among children tested has almost quadrupled over the past 3 decades. The associated morbidities include itch, discomfort, school absence, and reduced quality of life. In adulthood, individuals with Ni-ACD may have severe disabling hand eczema. The increasing rate of Ni-ACD in children has been postulated to result from early and frequent exposure to metals with high amounts of nickel release (eg, as occurs with ear piercing or with products used daily in childhood such as toys, belt buckles, and electronics).To reduce exposure to metal sources with high nickel release by prolonged and direct contact with human skin, Denmark and the European Union legislated a directive several decades ago with the goal of reducing high nickel release and the incidence of Ni-ACD. Since then, there has been a global reduction in incidence of Ni-ACD in population-based studies of adults and studies of children and young adults being tested for allergic contact dermatitis. These data point to nickel exposure as a trigger for elicitation of Ni-ACD and, further, provide evidence that legislation can have a favorable effect on the economic and medical health of a population.This policy statement reviews the epidemiology, history, and appearances of Ni-ACD. Examples of sources of high nickel release are discussed to highlight how difficult it is to avoid this metal in modern daily lives. Treatments are outlined, and avoidance strategies are presented. Long-term epidemiological interventions are addressed. Advocacy for smarter nickel use is reviewed. The American Academy of Pediatrics supports US legislation that advances safety standards (as modeled by the European Union) that protect children from early and prolonged skin exposure to high-nickel-releasing items. Our final aim for this article is to aid the pediatric community in developing nickel-avoidance strategies on both individual and global levels.

Occupationally Related Nickel Reactions: A Retrospective Analysis of the North American Contact Dermatitis Group Data 1998-2016

BACKGROUND

The epidemiology of nickel allergy in occupational settings is not well understood.

OBJECTIVE

The aim of the study was to characterize occupationally related nickel allergy (ORNA).

METHODS

This is a retrospective cross-sectional analysis of 44,378 patients patch tested by the North American Contact Dermatitis Group from 1998 to 2016. Characteristics of individuals with ORNA were compared with those with non-ORNA (NORNA).

RESULTS

A total of 7928 (18.2%) individuals were positive to nickel sulfate 2.5%. Two hundred sixty-eight (3.4%) had ORNA. As compared with NORNA, ORNA was statistically associated with the male sex (41.0% vs 12.9%, P < 0.001), a diagnosis of irritant contact dermatitis (22.4% vs 12.0%, P < 0.001), and no history of eczema (81.7% vs 75.7%, P = 0.0217). The most common sites of ORNA dermatitis were hand (39.9%) and arm (18.1%), which were significantly more common than in NORNA (P < 0.0001). Sixteen industry categories and 22 occupation categories were identified for ORNA; the most common industries were durable goods manufacturing (24.6%) and personal services (15.7%), and the most frequent occupations were hairdressers/cosmetologists/barbers (14.3%), machine operators (9.3%), and health care workers (7.1%). Overall 30% of ORNA occupations were in metalworking. Of 215 ORNA sources identified, instruments/phones/other equipment (16.3%), vehicles/machinery (15.8%), and tools (15.3%) were the most common.

CONCLUSIONS

Occupational nickel allergy is distinct from nonoccupational nickel allergy.

Associations of Nickel Co-Reactions and Metal Polysensitization in Adults

BACKGROUND

Allergic contact dermatitis to metals is a significant clinical and public health problem. Little is known about the determinants of polysensitization to metals.

OBJECTIVE

The aim of the study was to determine the frequency and predictors of nickel co-reactions and metal polysensitization.

METHODS

This is a retrospective chart review of 686 adults (age ≥ 18 years) who were patch tested from 2014 to 2017.

RESULTS

Overall, 267 patients (38.9%) had 1 or more positive patch-test reactions to a metal allergen, most commonly nickel (17.4%), mercury (12.3%), and palladium (9.2%). Nickel reactions were inversely associated with age (logistic regression; adjusted odds ratio [95% confidence interval], 0.39 [0.29-0.78]). Among patients with positive reactions to nickel, 34.5%, 15.1%, and 5.0% had positive reactions to 1, 2, or 3 additional metals, respectively. The most common nickel co-reactors were palladium, mercury, and gold. Polysensitization to metals occurred in 11.8% of patients. Polysensitization to metal allergens was associated with female sex (6.67 [1.01-44.21]) and inversely associated with age (0.40 [0.18-0.88]).

CONCLUSIONS

Nickel-sensitized patients have high rates of metal co-reactions. Polysensitization to metals is common in adults. These results may help guide future strategies for allergen avoidance.

Nickel-Related Adverse Reactions in the Treatment of Cerebral Aneurysms: A Literature Review

BACKGROUND

Nickel is the most common metal allergen and predominantly affects women. It is also the ubiquitous component in the alloys used to manufacture intracranial devices for aneurysm treatments, including aneurysm clips, self-expanding stents, flow-diverting stents, and endosaccular occlusion devices. Adverse events related to nickel allergy after deployment of such devices are uncommon but can be severe, resulting in dilemmas in the choice of treatment strategies and devices in managing nickel-sensitive patients with intracranial aneurysms.

METHODS

A literature search was performed in accordance with the PRISMA guidelines to identify studies reporting on nickel-related adverse events in patients being treated for cerebral aneurysm. The materials of the culprit devices, clinical presentation, histological features, and treatments were reviewed. Clinical considerations and management options for nickel allergy patients were evaluated.

RESULTS

Nickel is a major component of the cobalt alloy used in aneurysm clips and also of nitinol, which is commonly used in flow diverters and intracranial stents. Our literature review identified 9 articles reporting 10 unique cases of nickel-related adverse events after aneurysm treatment. Five of the cases occurred after aneurysm clipping, and the other 5 were attributed to endovascular devices. Two patients presented with dermatologic manifestations and 8 with neurologic manifestations, including cerebral edema and cerebritis.

CONCLUSIONS

Neurologic complications related to nickel in cerebral aneurysm treatments are rare but remain concern owing to the high prevalence of nickel allergy in the population. Surgeons and interventionists should consider the metal allergy history and its potential clinical significance in managing nickel-allergic patients with aneurysms.

Imaging mass spectrometry for novel insights into contact allergy - a proof-of-concept study on nickel

BACKGROUND

In spite of extensive regulation to limit exposure, nickel remains the main cause of contact allergy in the general population. More detailed knowledge on the skin uptake of haptens is required. So far, no method exists for the visualization of this clinically relevant hapten and its distribution in the skin.

OBJECTIVES

To show, in terms of a proof of concept, that imaging mass spectrometry [time of flight secondary ion mass spectrometry (ToF-SIMS)] can be applied for investigation of the penetration and distribution of nickel in human skin.

METHOD

Full-thickness human skin obtained from breast reduction surgery was exposed to nickel sulfate (5% in deionized water) for 24 h in Franz-type diffusion cells. Biopsies were obtained from nickel-treated samples and control (deionized water). The tissue was sliced, and analysed with ToF-SIMS, generating high-resolution images of ion distribution in the epidermis and upper dermis.

RESULTS

The skin layers could be discerned from the ToF-SIMS data, particularly on the basis of the collagen signal. Nickel ions were localized to the stratum corneum and upper epidermis.

CONCLUSIONS

This is the first time that ToF-SIMS has been applied to trace the distribution of a hapten in human skin. Proof of principle was shown for nickel, and the technique can, in the future, be expanded for investigation of the skin distribution of clinically relevant sensitizers in general.

Availability of Total Knee Arthroplasty Implants for Metal Hypersensitivity Patients

Purpose

To provide information on the type of "hypersensitivity-friendly" components available for primary total knee arthroplasty (TKA) in the current market.

Materials and Methods

Implant manufactures were identified using the 2013 National Joint Registries of the United Kingdom and Sweden and contacted to obtain information about the products they offer for patients with metal hypersensitivity.

Results

Information on 23 TKA systems was provided by 13 implant manufacturers. Of these, 15 systems had options suitable for metal hypersensitivity patients. Two types of "hypersensitivity-friendly" components were identified: 10 implants were cobalt chrome prostheses with a "hypersensitivity-friendly" outer coating and 5 implants were made entirely from non-cobalt chrome alloys.

Conclusions

The results of this study suggest that several hypersensitivity TKA options exist, some of which provide the same designs and surgical techniques as the conventional implants. The information in this study can guide TKA surgeons in making informed choices about implants and identifying implants that could be examined in future controlled studies comparing outcomes between "hypersensitivity-friendly" and conventional implants.

Low patch test reactivity to nickel in unselected adolescents tested repeatedly with nickel in infancy

BACKGROUND

It is questionable how repeated patch tests with nickel sulfate in infancy affect nickel patch test reactivity at a later age.

METHODS

The Danish Allergy Research Center (DARC) cohort encompasses 562 infants invited to a clinical examination including patch tests with nickel sulfate six times during the first 36 months of life. At the follow-up investigation at 14 years of age (2013-2014), participants were offered re-patch tests with nickel sulfate. The Odense Adolescence Cohort Study TOACS cohort encompasses 1501 schoolchildren evaluated for the first time at 14 years of age (1995-1996) including clinical examination and nickel sulfate patch tests. The prevalence of nickel sensitization in the DARC cohort was compared to the prevalence in the TOACS cohort at 14 years of age.

RESULTS

Nickel sulfate sensitization was found in 1.2% of the participants from the DARC cohort tested repeatedly with nickel sulfate in early childhood and retested at 14 years of age compared to 8.6% of the participants from the TOACS cohort patch-tested for the first time at 14 years of age using the same patch test system and test concentration.

CONCLUSION

The significant difference in nickel patch test reactivity comparing the two cohorts may reflect an immunologic effect or the effect of nickel regulation.

High prevalence of contact allergy in adolescence: results from the population-based BAMSE birth cohort

BACKGROUND

Contact allergy is common among adults. However, little is known about the prevalence in adolescents.

OBJECTIVES

To assess the prevalence of allergy to common contact allergens in Swedish adolescents in the general population.

PARTICIPANTS AND METHODS

The BAMSE cohort is a population-based birth cohort with the main aim of studying the risk factors for asthma, rhinitis, and atopic dermatitis. Patch testing was performed at the 16-year follow-up. The test (TRUE Test(®) ) was applied at home, and removed 2 days later by nurses, who recorded and photographed the results. Dermatologists made final assessments on the basis of photographs and protocols.

RESULTS

Two thousand two hundred and eighty-five participants (88% of all 16-year follow-up participants) were patch tested; 15.3% had at least one positive reaction. Contact allergy was more common in girls than in boys (17.0% versus 13.4%, p = 0.018). Sensitization to nickel was most common (7.5%), followed by sensitization to fragrance mix I (2.1%) and p-tert-butylphenol formaldehyde resin (1.9%). Nickel allergy was more frequent in girls (9.8% versus 4.9%, p < 0.001). Solitary sensitization to cobalt was more common than co-sensitization to nickel and cobalt.

CONCLUSIONS

The prevalence of contact allergy in adolescents is of almost the same high magnitude as in adults. The applied method was feasible in the population-based setting.

Nickel Allergy and Our Children's Health: A Review of Indexed Cases and a View of Future Prevention

Nickel is the leading cause of allergic contact dermatitis (ACD) from early childhood through adolescence. Studies have shown that skin piercings and other nickel-laden exposures can trigger the onset of nickel ACD in those who are susceptible. Nickel ACD causes a vast amount of cutaneous disease in children. Cases of nickel ACD in children have been reported in peer-reviewed literature from 28 states. Common items that contain inciting nickel include jewelry, coins, zippers, belts, tools, toys, chair studs, cases for cell phones and tablets, and dental appliances. The diagnosis of nickel ACD has been routinely confirmed by patch testing in children older than 6 months suspected of ACD from nickel. Unlike in Europe, there are no mandatory restrictions legislated for nickel exposure in the United States. Denmark has demonstrated that regulation of the nickel content in metals can lower the risk of ACD and the associated health care-related costs that arise from excess nickel exposure. To further awareness, this article reviews the prominent role of nickel in pediatric skin disease in the United States. It discusses the need for a campaign by caretakers to reduce nickel-related morbidity. Lastly, it promotes the model of European legislation as a successful intervention in the prevention of nickel ACD.

Belt Buckles-Increasing Awareness of Nickel Exposure in Children: A Case Report

Children, especially those with atopic dermatitis, are at risk for nickel sensitization and subsequent dermatitis from metal-containing objects, namely belt buckles. We describe allergic contact dermatitis in 12 children with peri-umbilical nickel dermatitis (with and without generalized involvement) caused by dimethylglyoxime-positive belt buckles. The patients' symptoms resolved with avoidance of the nickel-containing products.

Patch test results in children and adolescents across Europe. Analysis of the ESSCA Network 2002-2010

BACKGROUND

Contact sensitization in children is more frequent than previously thought.

METHODS

The ESSCA collected patch test data from 11 European countries aggregated to 4 European regions.

RESULTS

Six thousand and eight patients aged 1-16 years old with suspected allergic contact dermatitis were analyzed during a period of 8 years (2002-2010). The overall prevalence of at least one positive reaction to a hapten was 36.9%. The 10 most frequent haptens were as follows: nickel sulfate, cobalt chloride and potassium dichromate, neomycin sulfate, Myroxylon pereirae resin (balsam of Peru), para-phenylenediamine, chloromethylisothiazolinone/methylisothiazolinone 3:1, fragrance mix, lanolin alcohols, and colophony. No difference was found in the prevalence of at least one positive reaction to at least one hapten between boys and girls and between children with atopic dermatitis and children without. Children without atopic dermatitis, when compared with those with, had a significantly higher prevalence of contact sensitization for nickel sulfate (20.91% vs 16.87%, respectively), 4-tert. butylphenol formaldehyde resin (1.61% vs. 0.7%), and para-phenylenediamine (2.49% vs. 1.3%).

LIMITATIONS OF THE STUDY

Chamber loading is not an exact science and variation may occur between staff and departments. Interinstitution variations in readings can occur. A possible geographic confounder is that the southern regions tested more children in the younger age group. Relevance was not addressed due to difficulties in the application of a set of uniform definitions.

CONCLUSIONS

Our study adds information on the most common contact allergens detected in children which could help to define a Standard European Pediatric Baseline Series.

MD-2 determinants of nickel and cobalt-mediated activation of human TLR4

Recent findings unexpectedly revealed that human TLR4 can be directly activated by nickel ions. This activation is due to the coordination of nickel by a cluster of histidine residues on the ectodomain of human TLR4, which is absent in most other species. We aimed to elucidate the role of MD-2 in the molecular mechanism of TLR4/MD-2 activation by nickel, as nickel binding site on TLR4 is remote from MD-2, which directly binds the endotoxin as the main pathological activator of TLR4. We identified MD-2 and TLR4 mutants which abolished TLR4/MD-2 receptor activation by endotoxin but could nevertheless be significantly activated by nickel, which acts in synergy with LPS. Human TLR4/MD-2 was also activated by cobalt ions, while copper and cadmium were toxic in the tested concentration range. Activation of TLR4 by cobalt required MD-2 and was abolished by human TLR4 mutations of histidine residues at positions 456 and 458. We demonstrated that activation of TLR4 by nickel and cobalt ions can trigger both the MyD88-dependent and the -independent pathway. Based on our results we propose that predominantly hydrophobic interactions between MD-2 and TLR4 contribute to the stabilization of the TLR4/MD-2/metal ion complex in a conformation that enables activation.

MD-2 determinants of nickel and cobalt-mediated activation of human TLR4

Recent findings unexpectedly revealed that human TLR4 can be directly activated by nickel ions. This activation is due to the coordination of nickel by a cluster of histidine residues on the ectodomain of human TLR4, which is absent in most other species. We aimed to elucidate the role of MD-2 in the molecular mechanism of TLR4/MD-2 activation by nickel, as nickel binding site on TLR4 is remote from MD-2, which directly binds the endotoxin as the main pathological activator of TLR4. We identified MD-2 and TLR4 mutants which abolished TLR4/MD-2 receptor activation by endotoxin but could nevertheless be significantly activated by nickel, which acts in synergy with LPS. Human TLR4/MD-2 was also activated by cobalt ions, while copper and cadmium were toxic in the tested concentration range. Activation of TLR4 by cobalt required MD-2 and was abolished by human TLR4 mutations of histidine residues at positions 456 and 458. We demonstrated that activation of TLR4 by nickel and cobalt ions can trigger both the MyD88-dependent and the -independent pathway. Based on our results we propose that predominantly hydrophobic interactions between MD-2 and TLR4 contribute to the stabilization of the TLR4/MD-2/metal ion complex in a conformation that enables activation.

Cobalt skin dose resulting from short and repetitive contact with hard metals

BACKGROUND

Many daily contacts with metallic items are short and repetitive, and result in metal release; material, sweat, friction and wear may all be important.

OBJECTIVES

To study cobalt release and skin deposition as a result of many short and repetitive contacts with two cobalt-containing materials.

MATERIALS/METHODS

Study participants (n = 5) handled two types of hard metal disc (Co 6% and Co 15% Cr 0.6%) for 30 min. Deposited cobalt skin doses were measured with acid wipe sampling and chemical analysis. Cobalt release from the hard metal discs in artificial sweat was measured under conditions simulating those present during the handling of discs.

RESULTS

Average cobalt skin doses from discs containing 6% Co and 15% Co 0.6% Cr were 1.1 µg/cm(2) [standard deviation (SD) 0.4 µg/cm(2) ] and 0.7 µg/cm(2) (SD 0.5 µg/cm(2) ), respectively. More cobalt was released from hard metal discs containing 6% Co [11.4 µg/cm(2) (SD 1.2 µg/cm(2) )] than from discs containing 15% Co 0.6% Cr [4.8 µg/cm(2) (SD 0.6 µg/cm(2) )]. 10% to 15% of the potentially available cobalt was deposited on the skin during handling.

CONCLUSIONS

It is likely that the cobalt deposited as a result of short and repetitive contact with hard metals may cause harm. Research regarding cobalt exposure, metal release and the deposition of skin-sensitizing metals resulting from short and repetitive contact is needed for a better understanding of the allergy risk.

New UK nickel-plated steel coins constitute an increased allergy and eczema risk

BACKGROUND

Nickel-plated steel coins have recently been introduced in the United Kingdom.

OBJECTIVES

To compare the performance and allergy risk of the new nickel-plated coins (five and ten pence) with those of the cupro-nickel coins being replaced.

MATERIALS AND METHODS

Coin handling studies with assessment of skin exposure and metal release in artificial sweat were performed. Six volunteers participated.

RESULTS

The amount of nickel deposited onto skin during the handling of nickel-plated coins for 1 hr was 7.5 µg/cm(2) , four times higher than that from cupro-nickel coins. The nickel content in the oxidized surface of nickel-plated coins was higher, explaining the higher skin dose. Initial nickel release rates were 10-27 times higher than 1-week rates, emphasizing that brief and repeated contact results in significant nickel exposure.

CONCLUSIONS

Nickel-plated coins deposit higher levels of nickel onto skin than cupro-nickel coins, and hence pose an increased allergy risk. One-week release in artificial sweat is not suitable for determining the risk of handling items with high nickel release that come into short, repeated contact with the skin. The nickel skin dose is recommended for risk assessment. UK citizens are now, because of this change in coinage, unnecessarily exposed to higher levels of nickel on the skin. This is of public health concern.

Nickel and cobalt release from jewellery and metal clothing items in Korea

BACKGROUND

In Korea, the prevalence of nickel allergy has shown a sharply increasing trend. Cobalt contact allergy is often associated with concomitant reactions to nickel, and is more common in Korea than in western countries.

OBJECTIVE

The aim of the present study was to investigate the prevalence of items that release nickel and cobalt on the Korean market.

MATERIALS AND METHODS

A total of 471 items that included 193 branded jewellery, 202 non-branded jewellery and 76 metal clothing items were sampled and studied with a dimethylglyoxime (DMG) test and a cobalt spot test to detect nickel and cobalt release, respectively.

RESULTS

Nickel release was detected in 47.8% of the tested items. The positive rates in the DMG test were 12.4% for the branded jewellery, 70.8% for the non-branded jewellery, and 76.3% for the metal clothing items. Cobalt release was found in 6.2% of items. Among the types of jewellery, belts and hair pins showed higher positive rates in both the DMG test and the cobalt spot test.

CONCLUSION

Our study shows that the prevalence of items that release nickel or cobalt among jewellery and metal clothing items is high in Korea.