Nickel allergy and allergic contact dermatitis: A clinical review of immunology, epidemiology, exposure, and treatment

Innate Immune Mechanisms in Contact Dermatitis

Allergies are highly prevalent hypersensitivity responses to usually harmless substances. They are mediated by the immune system which causes pathologic responses such as type I (rhinoconjunctivitis, allergic asthma, atopy) or type IV hypersensitivity (allergic contact dermatitis). The different types of allergy are mediated by effector and memory T cells and, in the case of type I hypersensitivity, B cells. A prerequisite for the activation of these cells of the adaptive immune system is the activation of the innate immune system. The resulting inflammation is essential not only for the initiation but also for the elicitation and maintenance of allergies. Great progress has been made in the elucidation of the cellular and molecular pathomechanisms underlying allergen-induced inflammation. It is now recognized that the innate immune system in concert with tissue stress and damage responses orchestrates inflammation. This should enable the development of novel mechanism-based anti-inflammatory treatment strategies as well as of animal-free in vitro assays for the identification and potency classification of contact allergens.

Keratinocytes Regulate the Threshold of Inflammation by Inhibiting T Cell Effector Functions

Whilst the importance of keratinocytes as a first-line defense has been widely investigated, little is known about their interactions with non-resident immune cells. In this study, the impact of human keratinocytes on T cell effector functions was analyzed in an antigen-specific in vitro model of allergic contact dermatitis (ACD) to nickel sulfate. Keratinocytes partially inhibited T cell proliferation and cytokine production. This effect was dependent on the keratinocyte/T cell ratio and was partially reversible by increasing the number of autologous dendritic cells. The inhibition of T cell proliferation by keratinocytes was independent of the T cell subtype and antigen presentation by different professional antigen-presenting cells. Autologous and heterologous keratinocytes showed comparable effects, while the fixation of keratinocytes with paraformaldehyde abrogated the immunosuppressive effect. The separation of keratinocytes and T cells by a transwell chamber, as well as a cell-free keratinocyte supernatant, inhibited T cell effector functions to the same amount as directly co-cultured keratinocytes, thus proving that soluble factor/s account for the observed suppressive effects. In conclusion, keratinocytes critically control the threshold of inflammatory processes in the skin by inhibiting T cell proliferation and cytokine production.

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.

CXCL12/CXCR4 signaling induced itch and pain sensation in a murine model of allergic contact dermatitis

Allergic contact dermatitis is a skin inflammatory disease manifested with itch and pain symptom around the inflamed area. Chemokines such as CXCL12 are involved in the pathophysiology of allergic contact dermatitis, but little has been known about the effect of CXCL12/CXCR4 signaling for nociceptive sensation accompanying allergic contact dermatitis. Our study showed that CXCL12 and CXCR4 were upregulated in trigeminal ganglion with the progression of allergic contact dermatitis through western blotting and immunofluorescence. CXCL12 and CXCR4 were mainly upregulated in small-diameter neurons, which were co-localized with nociceptive markers in trigeminal ganglion. CXCR4 and CXCL12 were also expressed in trigeminal ganglion neurons retrograded from the skin lesion. Intradermal injection of CXCL12 enhanced the itch- and pain-like behavior which could be relieved by AMD3100, a CXCR4 antagonist, without changes of mast cells. Our findings suggested that blockade of CXCL12/CXCR4 signaling pathway might be beneficial to relieve itch and pain sensation accompanying allergic contact dermatitis.

Contact dermatitis

Contact dermatitis (CD) is among the most common inflammatory dermatological conditions and includes allergic CD, photoallergic CD, irritant CD, photoirritant CD (also called phototoxic CD) and protein CD. Occupational CD can be of any type and is the most prevalent occupational skin disease. Each CD type is characterized by different immunological mechanisms and/or requisite exposures. Clinical manifestations of CD vary widely and multiple subtypes may occur simultaneously. The diagnosis relies on clinical presentation, thorough exposure assessment and evaluation with techniques such as patch testing and skin-prick testing. Management is based on patient education, avoidance strategies of specific substances, and topical treatments; in severe or recalcitrant cases, which can negatively affect the quality of life of patients, systemic medications may be needed.

Analysis of Prevalence and Risk Factors of Contact Sensitization with respect to the Occupational Profiles in a Greek Patient Cohort: A Retrospective Analysis of a Greek Referral Centre and Future Perspectives

Contact dermatitis is a frequent skin disorder related to environmental and occupational etiological factors, which could potentially affect all age groups, as well as both genders. The current study is aimed at exploring the patterns of contact sensitization with respect to the population's occupational patterns in Greece. A retrospective analysis was performed in a cohort of 1978 patients from 2014 to 2016. Patients were divided into two categories; blue collars (BlC) and white collars (WhC), as well as detailed occupation was considered. Separation was performed on the basis of their profession, i.e., labor workers and handicraftsmen were sorted to the BlC group, while office employees were sorted to the WhC group. The common allergen in all occupational subgroups was nickel sulphate. The three most prevalent allergens in both BlC and WhC were nickel sulphate 5%, fragrance mix (I) 8%, and Balsam of Peru 25%. WhC males were uniquely sensitized to colophony 20% and formaldehyde 2%, and WhC females were uniquely sensitized to 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and neomycin sulphate 20%. Sensitization to allergens manifested occupation-specific patterns. Allergic contact dermatitis surveillance is of great importance towards the clinical and systematic understanding of the disease, especially with respect to the patient's occupational profile.

Nickel and tattoos: Where are we?

Tattoos are not mentioned as a source of exposure to nickel. Traces of nickel are, however, almost inevitably found in tattoo inks as impurities and sometimes in tattooed skin. Whether nickel in tattoos has any health consequence is debated. We performed a narrative review of what is currently known about this topic. Today, nickel is frequently detected in inks, but at highly variable levels. It appears to be at higher concentrations in green, blue, and sometimes brown and violet inks. Only nickel allergy in tattooed individuals and nickel-associated tattoo ink allergy are addressed in the literature. Reports of tattoo ink allergy related to nickel are rare and heterogenous. Authors often neglect possible implications of other metals or dyes. A positive patch test is not enough to confirm the role of nickel in a reaction observed after tattooing. We found no report of any systemic complication attributed to nickel from tattoos. The Council of Europe ResAP(2008)1 bans the presence of nickel at high levels in tattoo inks, which is a safety net for individuals with nickel allergy. Large epidemiologic case-control studies with systematic biopsies on normal and inflamed tattoos and patch testing would help to understand the role of nickel in tattoo ink allergies.

Occupational Dermatitis in Welding: Does Nickel Exposure Account for Higher Rates in Women? Analysis of a Canadian Cohort

OBJECTIVES

Women are reported to have higher rates of nickel sensitization than men, but there have been few studies of sex-related differences in dermatitis associated with occupational nickel exposure. This analysis examines dermatitis in a large cohort of women and men in welding and electrical occupations and considers how far differences in rates of dermatitis may be accounted for by nickel exposure.

METHODS

Women and men were recruited to cohorts of workers who had entered welding and electrical apprenticeships (the WHAT-ME and WHAT-MEN studies). Participants completed questionnaires at baseline and every 6 months for up to 5 years. At each contact, cohort members were asked about current dermatitis and whether it was made worse by work. From the first follow-up after recruitment, those working in their trade completed detailed subroutines about tasks in their trade including, for welders, the process, base metal, and consumables. Exposures were considered by trade and, within welding, by stainless or high alloy steel (SOHAS) as the base metal. Urinary nickel concentration was also examined. Using only report of dermatitis that began after entry to the trade, new-onset dermatitis, all episodes of dermatitis, and dermatitis made worse by work were examined against exposure by multilevel, multivariable logistic regression, allowing for potential confounding.

RESULTS

Among 1885 participants (welders; 447 women, 554 men: electrical trades; 438 women, 446 men), 200 reported dermatitis that started before they entered the trade, leaving 1685 for analysis. Women, but not men, who had entered the welding trades were more at risk of new onset [odds ratio (OR) = 1.54; 95% confidence interval (CI) 1.02-2.32] or dermatitis episodes (OR = 1.75; 95% CI 1.10-2.77) than those entering the electrical trades. Within welding, women were more at risk than men of new-onset dermatitis (OR = 1.85; 95% CI 1.15-2.96) and dermatitis episodes (2.14; 95% CI 1.24-3.68) but were not more likely to report these were made worse by work. Use of SOHAS as the base metal was associated with reports that dermatitis was made worse by work (3.54; 95% CI 1.04-12.03), but having adjusted for SOHAS use, women still remained at greater risk. A final analysis considered the effect on risk estimates of removing those welding SOHAS from the analysis. The risk for women of episodes of dermatitis was essentially unchanged, whether the comparison group was male welders or women in the electrical trades.

CONCLUSIONS

Welding is associated with risk of dermatitis in women. Although welding of SOHAS was associated with dermatitis that was made worse by work, it does not importantly explain the higher female rates in welding and other causes must be examined to support preventive measures.

Memory T helper cells identify patients with nickel, cobalt, and chromium metal allergy

BACKGROUND

Patch testing is the gold standard for identifying culprit allergens in allergic contact dermatitis; however, it is laborious and positive reactions are difficult to quantitate. Development of complementary in vitro tests is, therefore, of great importance.

OBJECTIVES

This study aimed to improve the in vitro lymphocyte proliferation test (LPT) to detect allergic responses to nickel (Ni), cobalt (Co), and chromium (Cr).

METHODS

Twenty-one metal allergic patients with a positive patch test to Ni (n=16), Co (n=8), and Cr (n=3) and 13 controls were included. All were tested by a flow cytometric LPT.

RESULTS

Metal-reactive cells were identified as T helper (Th) cells with high expression of the memory marker CD45RO. Skin-homing (cutaneous lymphocyte-associated antigen positive [CLA+]) Ni-reactive memory Th (Th_mem ^hi ) cells identified individuals with a positive patch test for Ni with 100% sensitivity (95% confidence interval [CI] 81%-100%) and 92% specificity (95% CI 67%-100%). Moreover, Co-specific Th_mem ^hi cells expressing CCR6 identified patients with a positive patch test for Co with 63% sensitivity (95% CI 31%-86%) and 100% specificity (95% CI 77%-100%). In Cr allergic individuals, Cr-reactive Th_mem ^hi cells tended to increased CLA and CCR6 expression.

CONCLUSION

Metal-reactive Th cells with high expression of CD45RO and coexpression of CLA and CCR6 improved the LPT, making it an attractive supplement to the patch test.

Effects of metal nanoparticles on tight junction-associated proteins via HIF-1α/miR-29b/MMPs pathway in human epidermal keratinocytes

Background

The increasing use of metal nanoparticles in industry and biomedicine raises the risk for unintentional exposure. The ability of metal nanoparticles to penetrate the skin ranges from stopping at the stratum corneum to passing below the dermis and entering the systemic circulation. Despite the potential health risks associated with skin exposure to metal nanoparticles, the mechanisms underlying the toxicity of metal nanoparticles on skin keratinocytes remain unclear. In this study, we proposed that exposure of human epidermal keratinocytes (HaCaT) to metal nanoparticles, such as nickel nanoparticles, dysregulates tight-junction associated proteins by interacting with the HIF-1α/miR-29b/MMPs axis.

Methods

We performed dose-response and time-response studies in HaCaT cells to observe the effects of Nano-Ni or Nano-TiO₂ on the expression and activity of MMP-2 and MMP-9, and on the expression of tight junction-associated proteins, TIMP-1, TIMP-2, miR-29b, and HIF-1α. In the dose-response studies, cells were exposed to 0, 10, or 20 μg/mL of Nano-Ni or Nano-TiO₂ for 24 h. In the time-response studies, cells were exposed to 20 μg/mL of Nano-Ni for 12, 24, 48, or 72 h. After treatment, cells were collected to either assess the expression of mRNAs and miR-29b by real-time PCR or to determine the expression of tight junction-associated proteins and HIF-1α nuclear accumulation by Western blot and/or immunofluorescent staining; the conditioned media were collected to evaluate the MMP-2 and MMP-9 activities by gelatin zymography assay. To further investigate the mechanisms underlying Nano-Ni-induced dysregulation of tight junction-associated proteins, we employed a HIF-1α inhibitor, CAY10585, to perturb HIF-1α accumulation in one experiment, and transfected a miR-29b-3p mimic into the HaCaT cells before Nano-Ni exposure in another experiment. Cells and conditioned media were collected, and the expression and activities of MMPs and the expression of tight junction-associated proteins were determined as described above.

Results

Exposure of HaCaT cells to Nano-Ni resulted in a dose-dependent increase in the expression of MMP-2, MMP-9, TIMP-1, and TIMP-2 and the activities of MMP-2 and MMP-9. However, exposure of cells to Nano-TiO₂ did not cause these effects. Nano-Ni caused a dose-dependent decrease in the expression of miR-29b and tight junction-associated proteins, such as ZO-1, occludin, and claudin-1, while Nano-TiO₂ did not. Nano-Ni also caused a dose-dependent increase in HIF-1α nuclear accumulation. The time-response studies showed that Nano-Ni caused significantly increased expressions of MMP-2 at 24 h, MMP-9 at 12, 24, and 48 h, TIMP-1 from 24 to 72 h, and TIMP-2 from 12 to 72 h post-exposure. The expression of miR-29b and tight junction-associated proteins such as ZO-1, occludin, and claudin-1 decreased as early as 12 h post-exposure, and their levels declined gradually over time. Pretreatment of cells with a HIF-1α inhibitor, CAY10585, abolished Nano-Ni-induced miR-29b down-regulation and MMP-2/9 up-regulation. Introduction of a miR-29b-3p mimic into HaCaT cells by transfection before Nano-Ni exposure ameliorated Nano-Ni-induced increased expression and activity of MMP-2 and MMP-9 and restored Nano-Ni-induced down-regulation of tight junction-associated proteins.

Conclusion

Our study herein demonstrated that exposure of human epidermal keratinocytes to Nano-Ni caused increased HIF-1α nuclear accumulation and increased transcription and activity of MMP-2 and MMP-9 and down-regulation of miR-29b and tight junction-associated proteins. Nano-Ni-induced miR-29b down-regulation was through Nano-Ni-induced HIF-1α nuclear accumulation. Restoration of miR-29b level by miR-29b-3p mimic transfection abolished Nano-Ni-induced MMP-2 and MMP-9 activation and down-regulation of tight junction-associated proteins. In summary, our results demonstrated that Nano-Ni-induced dysregulation of tight junction-associated proteins in skin keratinocytes was via HIF-1α/miR-29b/MMPs pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00405-2.

Occupational contact dermatitis: Retrospective analysis of North American Contact Dermatitis Group Data, 2001 to 2016

BACKGROUND

Patch testing is an important diagnostic tool for suspected allergic contact dermatitis (ACD) in occupational settings.

OBJECTIVE

Provide an overview of occupational skin disease (OSD) and an analysis of occupational ACD in North American patients undergoing patch testing between 2001and 2016.

METHODS

Patients with OSD were analyzed for frequency of allergic reactions to a screening series of allergens, occupational relevance, location of skin disease, and exposure sources. Demographic, occupation, and industry information were recorded.

RESULTS

Of 38,614 patients evaluated, 4471 (11.6%) had OSD, of whom 3150 (70.5%) had ACD. The most common occupationally related allergens included rubber accelerators, preservatives, and bisphenol A epoxy resin. Hands (75.8%), arms (30.0%), and face (15.9%) were common sites of dermatitis. The occupations most affected were service workers and machine operators.

LIMITATIONS

Our cohort may not reflect the general working population.

CONCLUSION

This study identified common occupational allergens, exposure sources, and occupations/industries at risk. This information may help the clinician evaluate and manage patients with occupational contact dermatitis.

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.

Integrative transcriptome analysis deciphers mechanisms of nickel contact dermatitis

Background

Nickel‐induced allergic contact dermatitis (nACD) remains a major occupational skin disorder, significantly impacting the quality of life of suffering patients. Complex cellular compositional changes and associated immunological pathways are partly resolved in humans; thus, the impact of nACD on human skin needs to be further elucidated.

Methods

To decipher involved immunological players and pathways, human skin biopsies were taken at 0, 2, 48, and 96 hours after nickel patch test in six nickel‐allergic patients. Gene expression profiles were analyzed via microarray.

Results

Leukocyte deconvolution of nACD‐affected skin identified major leukocyte compositional changes at 48 and 96 hours, including natural killer (NK) cells, macrophage polarization, and T‐cell immunity. Gene set enrichment analysis mirrored cellular‐linked functional pathways enriched over time. NK cell infiltration and cytotoxic pathways were uniquely found in nACD‐affected skin compared to sodium lauryl sulfate–induced irritant skin reactions.

Conclusion

These results highlight key immunological leukocyte subsets as well as associated pathways in nACD, providing insights into pathophysiology with the potential to unravel novel therapeutic targets.

Nickel: Intrinsic Skin Sensitization Potency and Relation to Prevalence of Contact Allergy

Nickel remains the most commonly identified contact allergen. However, it has proven difficult to demonstrate significant skin-sensitizing activity for nickel in toxicology tests, which typically have indicated a weak skin sensitization potential. Information indicates that in vivo assays are not predictive of dermal sensitization hazard or potency for nickel due to a human-specific mechanistic route for nickel sensitization that animals lack. A similar rationale will apply to in vitro alternatives-although these currently have limited ability to determine intrinsic potency. Generally, in silico methods are not designed for metal allergens and cannot contribute to the analysis. For ethical reasons, human experimental work has been limited, with a single study suggesting moderate potency. Accordingly, it seems reasonable to conclude that the high frequency of contact allergy to nickel in humans is a function of both its intermediate potency coupled with a high level of dermal exposure, particularly to damaged/inflamed skin.

The "Maskne" microbiome - pathophysiology and therapeutics

"Maskne" is a new term coined during the 2020 COVID-19 pandemic. It refers to a subset of acne mechanica, deserving consideration in view of widespread reusable fabric mask-wearing to control the pandemic worldwide. Understanding of underlying pathophysiology directly relates to the novel skin microenvironment and textile-skin friction created by mask-wearing, distinct from nontextile-related acne mechanica previously linked to wearing of headgear. Specifically, the occlusive microenvironment leads to microbiome dysbiosis, which is linked to various dermatological conditions. Additional textile-skin interactions include factors such as breathability, stickiness sensations, moisture saturation, and hygiene maintenance. Increased skin temperatures can trigger sweat/heat-related dermatoses, and ear loops potentially trigger pressure-induced dermatoses. Important therapeutic considerations include increased skin irritation potential of conventional acne treatments under occlusion, exacerbation of chronic dermatoses, that is, perioral dermatitis, rosacea, and eczema, and susceptibility of these same patient groups to heightened discomfort with mask-wearing. Cotton, as the traditional fabric of choice for dermatology patients, has limited benefits in the context of face masks - increased subjective discomfort relates to increased moisture saturation and stickiness, inevitable because of high biofluid load of the nasal and oral orifices. Prolonged textile-skin contact time, directly proportional to the risk of maskne, can be an opportunity for the application of biofunctional textiles.

Nickel ions attenuate autophagy flux and induce transglutaminase 2 (TG2) mediated post-translational modification of SQSTM1/p62

Nickel, the most frequent contact allergy cause, is widely used for various metallic materials and medical devices. Autophagy is an intracellular protein degradation system and contributes to metal recycling. However, it is unclear the functions of nickel in autophagy. We here demonstrated that NiCl2 induced microtubule-associated protein 1 light chain 3 (LC3)-II and LC3 puncta, markers of autophagosomes. Bafilomycin A1 (BafA1) treatment did not enhance LC3 puncta under NiCl2 stimulation, suggesting that NiCl2 did not induce autophagic flux. In addition, NiCl2 promotes the accumulation of SQSTM1/p62 and increased SQSTM1/p62 colocalization with lysosomal-associated membrane protein 1 (LAMP1). These data indicated that NiCl2 attenuates autophagic flux. Interestingly, NiCl2 induced the expression of the high-molecular-weight (MW) form of SQSTM1/p62. Inhibition of NiCl2-induced reactive oxygen species (ROS) reduced the high-MW SQSTM1/p62. We also showed that NiCl2-induced ROS activate transglutaminase (TG) activity. We found that transglutaminase 2 (TG2) inhibition reduced high-MW SQSTM1/p62 and SQSTM1/p62 puncta under NiCl2 stimulation, indicating that TG2 regulates SQSTM1/p62 protein homeostasis under NiCl2 stimulation. Our study demonstrated that nickel ion regulates autophagy flux and TG2 restricted nickel-dependent proteostasis.

The effectiveness of a nonalcoholic disinfectant containing metal ions, with broad antimicrobial activity

Disinfectants have different efficacies depending on their use and the target microorganism. This study aimed to evaluate the efficacy and safety of our new nonalcoholic disinfectant, which consists mainly of metal ions. According to the 17th revised Japanese Pharmacopoeia and ASTM international E1052 method, the bactericidal and virucidal efficacy of this new disinfectant against 13 microorganisms was evaluated by the in vitro quantitative suspension test. Additionally, the disinfectant cytotoxicity against multiple cell lines was examined. Then, a safety test using a human open patch test was performed with 26 healthy volunteers. This disinfectant showed strong bactericidal and virucidal activities: all microorganisms except enterovirus were inactivated very quickly. The infectivity of 12 microbial strains was eliminated within 5 min of disinfectant exposure. Additionally, this disinfectant showed little acute cytotoxicity in vitro. All volunteers were negative in the human open patch test. Our new disinfectant has a broad spectrum of microbial targets, is safe for human skin, and demonstrates no cytotoxicity. This disinfectant could prevent common microbial infections.

Di(2-picolyl)amine-functionalized poly(ethylene glycol) hydrogels with tailorable metal–ligand coordination crosslinking

A new class of metallo-hydrogels has been developed using di(2-picolyl)amine (DPA)-functionalized 4-arm polyethylene glycol (4A-PEG-DPAn) polymers crosslinked by metal–ligand coordination.

Conjugated polymers – a versatile platform for various photophysical, electrochemical and biomedical applications: a comprehensive review

Tuneable properties of conjugated polymers are attractive for use in multiple domains like optical, electronic and biological applications.

Occupational skin disease in mining: an Australian case series

The mining industry has one of the highest rates of occupational disease across all industries. However, occupational skin disease (OSD) is not commonly reported in this industry, although has been estimated to affect up to 51 people per 100,000 workers, with contact dermatitis accounting for the majority of cases. It often has a poor prognosis and leads to days lost from work. There have been relatively few reports regarding the specific forms of OSD encountered by miners worldwide. We report our experience of miners attending our Occupational Dermatology Clinic and our investigations at two Australian mines. We compare our findings with other reports of OSD in the mining population. The most commonly observed skin condition was irritant contact dermatitis, but miliaria and allergic contact dermatitis were also observed. It is not surprising that most cases of OSD appear to be related to harsh working conditions and exposures to multiple skin irritants, however, specific exposures causing ACD should not be forgotten. Our findings are consistent with previous studies of OSD in miners.

The Many Faces of CD4+ T Cells: Immunological and Structural Characteristics

As a major arm of the cellular immune response, CD4⁺ T cells are important in the control and clearance of infections. Primarily described as helpers, CD4⁺ T cells play an integral role in the development and activation of B cells and CD8⁺ T cells. CD4⁺ T cells are incredibly heterogeneous, and can be divided into six main lineages based on distinct profiles, namely T helper 1, 2, 17 and 22 (Th1, Th2, Th17, Th22), regulatory T cells (Treg) and T follicular helper cells (Tfh). Recent advances in structural biology have allowed for a detailed characterisation of the molecular mechanisms that drive CD4⁺ T cell recognition. In this review, we discuss the defining features of the main human CD4⁺ T cell lineages and their role in immunity, as well as their structural characteristics underlying their detection of pathogens.

Nickel Sensitivity Is Associated with GH-IGF1 Axis Impairment and Pituitary Abnormalities on MRI in Overweight and Obese Subjects

Nickel (Ni) is a ubiquitous metal, the exposure of which is implied in the development of contact dermatitis (nickel allergic contact dermatitis (Ni-ACD)) and Systemic Ni Allergy Syndrome (SNAS), very common among overweight/obese patients. Preclinical studies have linked Ni exposure to abnormal production/release of Growth Hormone (GH), and we previously found an association between Ni-ACD/SNAS and GH-Insulin-like growth factor 1 (IGF1) axis dysregulation in obese individuals, altogether suggesting a role for this metal as a pituitary disruptor. We herein aimed to directly evaluate the pituitary gland in overweight/obese patients with signs/symptoms suggestive of Ni allergy, exploring the link with GH secretion; 859 subjects with overweight/obesity and suspected of Ni allergy underwent Ni patch tests. Among these, 106 were also suspected of GH deficiency (GHD) and underwent dynamic testing as well as magnetic resonance imaging for routine follow up of benign diseases or following GHD diagnosis. We report that subjects with Ni allergies show a greater GH-IGF1 axis impairment, a higher prevalence of Empty Sella (ES), a reduced pituitary volume and a higher normalized T2 pituitary intensity compared to nonallergic ones. We hypothesize that Ni may be detrimental to the pituitary gland, through increased inflammation, thus contributing to GH-IGF1 axis dysregulation.

Machine-learning-driven biomarker discovery for the discrimination between allergic and irritant contact dermatitis

Contact dermatitis tremendously impacts the quality of life of suffering patients. Currently, diagnostic regimes rely on allergy testing, exposure specification, and follow-up visits; however, distinguishing the clinical phenotype of irritant and allergic contact dermatitis remains challenging. Employing integrative transcriptomic analysis and machine-learning approaches, we aimed to decipher disease-related signature genes to find suitable sets of biomarkers. A total of 89 positive patch-test reaction biopsies against four contact allergens and two irritants were analyzed via microarray. Coexpression network analysis and Random Forest classification were used to discover potential biomarkers and selected biomarker models were validated in an independent patient group. Differential gene-expression analysis identified major gene-expression changes depending on the stimulus. Random Forest classification identified CD47, BATF, FASLG, RGS16, SYNPO, SELE, PTPN7, WARS, PRC1, EXO1, RRM2, PBK, RAD54L, KIFC1, SPC25, PKMYT, HISTH1A, TPX2, DLGAP5, TPX2, CH25H, and IL37 as potential biomarkers to distinguish allergic and irritant contact dermatitis in human skin. Validation experiments and prediction performances on external testing datasets demonstrated potential applicability of the identified biomarker models in the clinic. Capitalizing on this knowledge, novel diagnostic tools can be developed to guide clinical diagnosis of contact allergies.

Immunotoxicity of nickel: Pathological and toxicological effects

Nickel (Ni) is a widely distributed metal in the environment and an important pollutant because of its many industrial applications. With increasing incidences of Ni contamination, Ni toxicity has become a global public health concern and recent evidence suggests that Ni adversely affects the immune system. Hence, this paper reviews the literature on immune-related effects of Ni exposure, the immunotoxicological effects of Ni, and the underlying mechanism of Ni immunotoxicity. The main focus was on the effect of Ni on the development of organs of immune system, lymphocyte subpopulations, cytokines, immunoglobulins, natural killer (NK) cells, and macrophages. Moreover, Ni toxicity also induces inflammation and several studies demonstrated that Ni could induce immunotoxicity. Excessive Ni exposure can inhibit the development of immune organs by excessively inducing apoptosis and inhibiting proliferation. Furthermore, Ni can decrease T and B lymphocytes, the specific mechanism of which requires further research. The effects of Ni on immunoglobulin A (IgA), IgG, and IgM remain unknown and while Ni inhibited IgA, IgG, and IgM levels in an animal experiment, the opposite result was found in research on humans. Ni inhibits the production of cytokines in non-inflammatory responses. Cytokine levels increased in Ni-induced inflammation responses, and Ni activates inflammation through toll like (TL)4-mediated nuclear factor-κB (NF-κB) and signal transduction cascades mitogen-activated protein kinase (MAPK) pathways. Ni has been indicated to inactivate NK cells and macrophages both in vitro and in vivo. Identifying the mechanisms underlying the Ni-induced immunotoxicity may help to explain the growing risk of infections and cancers in human populations that have been exposed to Ni for a long time. Such knowledge may also help to prevent and treat Ni-related carcinogenicity and toxicology.

Patch test results with the European baseline series and additions thereof in the ESSCA network, 2015-2018

BACKGROUND

Clinical surveillance of the prevalence of contact allergy in consecutively patch tested patients is a proven instrument to continually assess the importance of contact allergens (haptens) assembled in a baseline series.

OBJECTIVES

To present current results from the European Surveillance System on Contact Allergies, including 13 countries represented by 1 to 11 departments.

METHODS

Anonymized or pseudonymized patch test and clinical data from various data capture systems used locally or nationally as transferred to the Erlangen data centre were pooled and descriptively analysed after quality control.

RESULTS

In the 4 years (2015-2018), data from 51 914 patients patch tested with the European baseline series (EBS) of contact allergens were analysed. Contact allergy to nickel was most frequent (17.6% positive), followed by contact allergy to fragrance mix I (6.9%), methylisothiazolinone (MI; 6.2%), and Myroxylon pereirae resin (balsam of Peru; 5.8%).

CONCLUSIONS

While the prevalence of MI contact allergy decreased substantially following regulatory intervention, the persistently high levels of allergy to metals, fragrances, other preservatives, and rubber chemicals point to problems needing further research and, potentially, preventive efforts. Results with national additions to the baseline series provide important information on substances possibly to be considered for inclusion in the EBS.

Thiolated Chitosans: A Multi-talented Class of Polymers for Various Applications

Various properties of chitosan can be customized by thiolation for very specific needs in a wide range of application areas. Since the discovery of thiolated chitosans, many studies have proven their advantageous characteristics, such as adhesion to biological surfaces, adjustable cross-linking and swelling behavior, controllable drug release, permeation as well as cellular uptake enhancement, inhibition of efflux pumps and enzymes, complexation of metal ions, antioxidative properties, and radical scavenging activity. Simultaneously, these polymers remain biodegradable without increased toxicity. Within this Review, an overview about the different possibilities to covalently attach sulfhydryl ligands to the polymeric backbone of chitosan is given, and the resulting versatile physiochemical properties are discussed in detail. Furthermore, the broad spectrum of applications for thiolated chitosans in science and industry, ranging from their most advanced use in pharmaceutical and medical science over wastewater treatment to the impregnation of textiles, is addressed.

Patch Testing With an Extended Metal Allergen Series at the Massachusetts General Hospital (2006-2017)

BACKGROUND

Reports of patch test data with an extended metal series that includes rare metals are limited.

OBJECTIVE

The aims of the study were to analyze and report patch testing results from an extended metal series, examine associations with sex and age, and highlight concomitant metal reactions.

METHODS

This study is a retrospective review of 150 patients referred for suspected metal allergy from January 1, 2007, to December 31, 2016.

RESULTS

The most common indications for evaluation referral were those having symptoms after implantation of a metal device (55.3%) and those with a history and concern of metal allergy before implantation of a metal device (22.0%). One or more positive patch test reactions were observed in 87 patients (58.0%). Metals with the highest frequencies were nickel sulfate 2.5% (26.2%), gold sodium thiosulfate 0.5% (23.0%), gold sodium thiosulfate 2.0% (20.7%), palladium chloride 2.0% (19.6%), cobalt chloride 1.0% (12.0%), and manganese chloride 2.0% (10.1%). Of the 45 metals tested, 15 caused no patch test reactions. Female patients were more likely to be sensitized to nickel, gold, and palladium (P < 0.05). Younger patients (≤40 years) had higher reaction rates to nickel, mercury, palladium, and cobalt. Concomitant reactions of the top metals (nickel, palladium, gold, and cobalt) were statistically associated bidirectionally (P < 0.05), except for cobalt and gold.

CONCLUSIONS

Allergy to metals, including those not included in standard series, may be more prevalent than previously suspected. Results may help guide future testing for suspected metal allergy, although future studies are warranted.

Occupational Exposure to Metals and Solvents: Allergy and Airway Diseases

PURPOSE OF REVIEW

Occupational allergic diseases (OAD) such as occupational contact dermatitis (OCD), occupational asthma (OA), and occupational rhinitis (OR) are the most prevalent occupational diseases in industrialized countries. The purpose of this review is to provide an update about the main occupational metal and solvent exposures related to allergy and airway diseases and to discuss newly defined causative agents and industries in this field.

RECENT FINDINGS

Currently for over 400 causative agents for OA and OCD, several hundreds of agents for OR have been identified. Although many studies have reported an overall decline in OAD related to known agents after implementation of efficient and effective workplace preventive measures, the constant development of new products continuously introduces to the market potential unknown respiratory hazards. Workplace allergens are often high molecular weight (HMW) agents that are > 10 kDa molecular weight and capable of eliciting IgE sensitization. Sensitizing low molecular weight (LMW) agents are often reactive chemicals. Metals and solvents are two large causative agent groups related to OADs that mainly behave as LMW (< 10 kDa) sensitizers and/or irritants. Avoidance of causative exposures through control strategies is the primary prevention approach for OADs. These strategies must be applied and covered for all known and newly defined causative agents. This review aims to summarize current status of known occupational metal and solvent exposures related to allergy and airway diseases and to discuss newly defined causative agents and industries in this field.

Peptide bond cleavage in the presence of Ni-containing particles

NiO nanoparticles and non-stoichiometric black NiO were shown to be effective sources of Ni2+ ions causing sequence-selective peptide bond hydrolysis. NiO nanoparticles were as effective in this reaction as their molar equivalent of soluble Ni(ii) salt. These findings highlight the efficacy of delivery of toxic Ni2+ by these environmentally available particles.

Dendritic Epidermal T Cells in Allergic Contact Dermatitis

Allergic contact dermatitis (ACD) is a common inflammatory skin disease with a prevalence of approximately 20% in the European population. ACD is caused by contact allergens that are reactive chemicals able to modify non-immunogenic self-proteins to become immunogenic proteins. The most frequent contact allergens are metals, fragrances, and preservatives. ACD clinically manifests as pruritic eczematous lesions, erythema, local papules, and oedema. ACD is a T cell-mediated disease, involving both CD4⁺ and CD8⁺ T cells. In addition, γδ T cells appear to play an important role in the immune response to contact allergens. However, it is debated whether γδ T cells act in a pro- or anti-inflammatory manner. A special subset of γδ T cells, named dendritic epidermal T cells (DETC), is found in the epidermis of mice and it plays an important role in immunosurveillance of the skin. DETC are essential in sensing the contact allergen-induced stressed environment. Thus, allergen-induced activation of DETC is partly mediated by numerous allergen-induced stress proteins expressed on the keratinocytes (KC). Several stress proteins, like mouse UL-16-binding protein-like transcript 1 (Mult-1), histocompatibility 60 (H60) and retinoic acid early inducible-1 (Rae-1) α-ε family in mice and major histocompatibility complex (MHC) class I-chain-related A (MICA) in humans, are upregulated on allergen-exposed KC. Allergen-induced stress proteins expressed on the KC are consequently recognized by NKG2D receptor on DETC. This review focuses on the role of γδ T cells in ACD, with DETC in the spotlight, and on the role of stress proteins in contact allergen-induced activation of DETC.

A comprehensive study of nickel levels in everyday items in Brazil

BACKGROUND

Nickel is a ubiquitous element used in many everyday items. In recent decades nickel has become a leading allergen, which has become a public health problem.

OBJECTIVE

To evaluate frequently used nickel products in Brazil. We investigated if these objects release nickel that is capable of inducing sensitization or cause clinical manifestations in terms of allergic contact dermatitis (ACD).

METHODS

Dimethylglyoxime (DMG) spot tests assessed nickel release from several common utensils used in everyday life in São Paulo and Rio de Janeiro, Brazil.

RESULTS

We tested 46 coins (two denominations) and 90 common utensils. Approximately 91.1% produced nickel-positive results using the DMG spot test.

CONCLUSIONS

The DMG limit of detection was 1.67 ppm of nickel. We observed that many objects in our test series released nickel above the DMG test limit. This observation suggests that nickel-sensitive individuals may be exposed to nickel, representing a public health issue.

The Effects of Low-Nickel Diet Combined with Oral Administration of Selected Probiotics on Patients with Systemic Nickel Allergy Syndrome (SNAS) and Gut Dysbiosis

Background: Nickel (Ni) oral consumption may elicit systemic reactions in patients affected by systemic nickel allergy syndrome (SNAS), including gastrointestinal symptoms, which in turn are associated with gut dysbiosis. We evaluated the effects of a low-Ni diet alone or in combination with the oral consumption of appropriate probiotics on Ni-sensitivity and urinary dysbiosis markers in SNAS patients. Methods: n = 51 patients with SNAS and concomitant intestinal dysbiosis were enrolled in the study. According to the urinary indican/skatole levels, quantified through a colorimetric and a high-performance liquid chromatographic method, respectively, patients were assigned to a dysbiosis type/grade and followed a low-Ni diet for three months. Along with the diet, 22 patients also consumed probiotics based on the dysbiosis type. In particular, a Lactobacilli- or Bifidobacteria-containing formulation was administered to patients with fermentative or putrefactive dysbiosis, respectively, while a broad-spectrum probiotic formulation containing both Lactobacilli and Bifidobacteria was administered to patients with mixed dysbiosis. After three months, patients were invited to repeat the Ni-stimulation and the dysbiosis tests. Results: The fermentative dysbiosis group represented the largest group followed by the mixed dysbiosis group, while only two patients had putrefactive dysbiosis. Overall, at three months of treatment in general (diet alone with or without probiotics), the Ni-sensitivity and dysbiosis levels were strongly ameliorated. The association of a low-Ni diet with a specific probiotic oral supplementation was significantly more effective in decreasing dysbiosis levels or reaching eubiosis than with diet alone. Conclusion: Our results, while confirming the benefits of a low-Ni diet in SNAS patients, strongly support that appropriate adjuvant treatment with probiotics significantly helps to improve intestinal dysbiosis or restore a healthy microbiota.

Contact Allergy-Emerging Allergens and Public Health Impact

Contact allergy (sensitisation) and allergic contact dermatitis (ACD) resulting from it have a considerable public health impact. For the present review, all pertinent articles were systematically searched via Medline and Web of Science™; additionally, all available issues of the journals "Contact Dermatitis" and "Dermatitis" were manually searched, covering the years 2018-2019, thereby extending and re-focusing a previous similar review. New allergens, or previously described allergens found in a new exposure context or of other current importance, are described in sections according to substance classes, e.g., metals, preservatives, fragrances. As a common finding in many investigations, a lack of information on product composition has been noted, for instance, regarding a newly described allergen in canvas shoes (dimethylthiocarbamylbenzothiazole sulfide) and, most notably, absence of co-operation from manufacturers of glucose-monitoring devices and insulin pumps, respectively. These latter devices have been shown to cause severe ACD in a considerable number of diabetic patients caused by the liberation of isobornyl acrylate and N,N'-dimethylacrylamide, respectively, as demonstrated by an international collaboration between dermatologists and chemists. Improved and complete ingredient labelling for all types of products, and not just cosmetics, must be put on the legislative agenda.

Nickel allergy is associated with wheezing and asthma in a cohort of young German adults: results from the SOLAR study

Background

Nickel allergy is the most prevalent contact allergy. It belongs to a different hypersensitivity type to asthma and rhinoconjunctivitis. The aim of this analysis was to assess whether self-reported nickel allergy is associated with incident wheezing, asthma and rhinoconjunctivitis in young German adults, taking into account potential effect modification by sex.

Methods

In total, 2051 (70.6%) participants aged 19–24 years took part in the second phase of SOLAR (Study on Occupational Allergy Risks), a follow-up study of ISAAC II (the second phase of the International Study of Asthma and Allergies in Childhood) in Germany. Self-reported nickel allergy, as well as having pierced ears, and the three outcomes incident wheezing, asthma and rhinoconjunctivitis, were analysed stratified for sex. Logistic regression adjusted for potential confounders was performed.

Results

An association between self-reported nickel allergy and incident wheezing was observed for men and women, while only in males did pierced ears show a significant association with the outcome (adjusted OR 2.26, 95% CI 1.10–4.62). Also only in males, self-reported nickel allergy was associated with elevated odds for incident asthma (adjusted OR 4.34, 95% CI 1.22–15.41). Neither in men nor in women was a significant association observed for incident rhinoconjunctivitis.

Conclusion

Our results suggest that self-reported nickel allergy is associated with incident wheezing. Whether this association is due to environmental or genetic predisposition, or due to an overlap of the mechanisms of type I and type IV hypersensitivity, needs to be elucidated.

Self-reported nickel allergy is associated with incident wheezing in young German males and females, and with incident asthma in males, whereas no significant association was observed for self-reported nickel allergy and incident rhinoconjunctivitishttp://bit.ly/2YHmwBA

Nickel allergy in lipid transfer protein sensitized patients: Prevalence and clinical features

Nickel (Ni), the main responsible for allergic contact dermatitis worldwide, is also involved in systemic condition called "Systemic Nickel Sulfate Allergy Syndrome (SNAS)." Likewise, IgE-mediated reactivity to Lipid Transfer Protein (LTP) represents the main cause of primary food allergy in adults of Mediterranean countries. We evaluated the prevalence of SNAS in LTP allergic patients and investigated patients' clinical features with double sensitization (LTP and Ni). A retrospective, single-center, observational study was conducted performing a complete allergological work-up including: (1) skin prick tests; (2) serum specific IgE for plant food allergens and rPru p3 (LTP); (3) patch test with 5% Ni sulfate in petrolatum. We enrolled 140 LTP allergic patients of which 36 patients (25.7% of sample) showed additional positivity to Ni patch test. Patients with double sensitization were more frequently females and reported fewer cutaneous symptoms. Higher values of sIgE for peach, apple, peanut, walnut, grain, corn, and garlic were found in LTP allergic patients, while higher values for hazelnut in the other subgroup. The prevalence of SNAS in the LTP allergic population is clinically relevant. Moreover, the clinical and immunological profiles of patients with double sensitization were different from patients monosensitized to LTP.

Prevalence of contact allergy to metals: nickel, palladium, and cobalt in Southern Sweden from 1995-2016

BACKGROUND

In 2001, the EU nickel directive was introduced to prevent contact allergy to nickel. Contact allergy to palladium and/or cobalt is often seen together with contact allergy to nickel.

OBJECTIVES

To compare the contact allergy prevalence of nickel, palladium, and cobalt allergy before and after the introduction of the EU nickel directive in consecutive patients with dermatitis.

METHODS

A retrospective analysis of patch test results from 1995-2016 was performed (n = 18 264). Chi-square tests were used to examine trends for nickel, palladium, and cobalt across test years. Logistic regression was used for associations.

RESULTS

The prevalence of nickel allergy decreased significantly in the youngest age group (6-30 years) for both female and male patients from 1995-1999 to 2012-2016: females: 33.4% to 19.1% (P < .001); males: 5.9% to 2.1% (P < .05). The concomitant reactions between nickel and palladium and nickel and cobalt among young females, respectively, also decreased significantly. Isolated palladium and cobalt allergy remained stable (1.4% and 2.3%, respectively) during the same time period for both men and women.

CONCLUSIONS

The prevalence of nickel has decreased among young females and males suspected of contact allergy in Southern Sweden after the introduction of the EU nickel directive. There has been no change in isolated palladium or cobalt allergy.