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 (Thmem 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 Thmem 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 Thmem 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.

Diagnosis of Metal Hypersensitivity in Total Knee Arthroplasty: A Case Report.

Delayed type hypersensitivity (DTH) reactions are considered infrequent complications in arthroplasty, but have been recognized to be associated with devastating morbidity and substantial decrease in quality of life of affected patients. Chronic inflammation of artificial joints and associated loss of peri-implant bone often require revision surgery. Methods for the diagnosis of implant-related DTH are available but infrequently considered to the full extent. Sequential diagnostics based on exclusion of septic complications, local and systemic metal level determination, lymphocyte transformation testing (LTT), and local T cell subset analysis are required for an unequivocal DTH diagnosis. Here, we report on a patient with a history of chronic rheumatoid arthritis and an unfavorable outcome of unilateral knee arthroplasty. This case illustrates pitfalls and difficulties in the course of recurrent inflammation following joint replacement. In the early course, suspicion of low-grade bacterial infection led to three two-stage revisions. Afterwards, the joint was proven to be sterile. However, metal level quantification revealed release of especially cobalt and chromium from the joint, LTT indicated persisting cobalt and nickel sensitization and subset analysis of T cells from the synovium suggested DTH as a root cause for the inflammatory symptoms. This report aims to recommend the depicted diagnostic algorithm as an adequate tool for future DTH detection. Yet, systemic to local subset ratios for effector memory and regulatory T cells should be derived from sufficient patient numbers to establish it as a diagnostic marker. Moreover, future prospects regarding implant-related DTH diagnostics are discussed. Therapeutic options for the portrayed patient are proposed, considering pharmaceutical, cell-therapeutic and surgical aspects. Patients who experience peri-implant inflammation but do not have obvious mechanical or infectious problems remain a diagnostic challenge and are at high risk of being treated inadequately. Since potentially sensitizing materials are regularly used in arthroplasty, it is essential to detect cases of acute DTH-derived inflammation of an artificial joint at early postoperative stages. This would reduce the severity of inflammation-related long-term consequences for affected patients and may avoid unnecessary revision surgery.

Improved metal allergen reactivity of artificial skin models by integration of Toll-like receptor 4-positive cells.

BACKGROUND: Reconstructed human epidermis (RhE) is widely used to replace animal models in order to assess the proinflammatory and allergenic effects of chemicals. Unfortunately, RhE lacks proinflammatory responsiveness for metal haptens, which are the most prevalent human contact allergens, raising concerns about its reliability for predicting skin allergens. OBJECTIVES: To investigate whether this limitation of RhE might be attributable to a lack of functional expression of Toll-like receptor 4 (TLR4), which governs proinflammatory sensitivity to nickel and cobalt. MATERIALS AND METHODS: RhE, dendritic cell (DC)-containing RhE and full-thickness skin equivalent (FTSE) were compared regarding their proinflammatory responsiveness to metal allergens. RESULTS: The incorporation of dermal fibroblasts was sufficient to confer metal sensitivity to RhE. Unlike keratinocytes, normal human fibroblasts expressed high levels of TLR4 mRNA and induced interleukin-8 expression upon stimulation with nickel or cobalt. Consistently, dermal isolates from FTSE expressed considerable amounts of TLR4 mRNA, whereas RhE or epidermis isolated from FTSE, normal human epidermis or inflamed human epidermis failed to express TLR4. Similarly, co-culture with TLR4-positive DCs bestowed RhE with proinflammatory responsiveness to metals. CONCLUSION: Our data suggest that FTSE or DC/RhE co-culture models can circumvent the shortcomings of RhE assays, and combine the benefits of complex and monoculture-based test systems in a single assay.

Failure of facet replacement system with metal-on-metal bearing surface and subsequent discovery of cobalt allergy: report of 2 cases.

The aim of this study was to report on 2 patients in whom metal-on-metal (MOM) facet replacements failed, with subsequent positive findings on allergy testing. Motion-preserving devices have been used with limited success when instrumentation is indicated in the mobile spine. MOM-bearing surfaces in orthopedics were developed to increase implant longevity, yet have been associated with numerous adverse outcomes, including local tissue reactions, pseudotumors, metallosis, and the need for revision surgery. Five patients with spinal stenosis and low-grade spondylolisthesis were randomized to undergo facet replacement surgery with the ACADIA facet replacement system at the authors' institution. Two patients experienced a return of neurological symptoms after a pain-free interval (< 2 years) with development of local tissue reaction and positive findings on allergy testing to cobalt, the metal in the MOM-bearing surface. Both patients underwent successful removal of the implant and revision to titanium posterior spinal fusion and interbody fusion without further complication. Motion-preserving devices have been designed and trialed for specific indications in the mobile spine. Given the adverse results from MOM devices in hip arthroplasty and now the early reports with MOM facet replacements, caution is warranted when moving forward with any MOM joint-bearing surface. Both patients presented here had an unusual tissue reaction locally and subsequent positive allergy testing results to cobalt. These 2 patients appear to have developed a delayed hypersensitivity reaction to the metal, likely from fine debris at the MOM interface.

Chemical Tattoo Treatment Leading to Systemic Cobalt Hypersensitivity.

An otherwise healthy 36-year-old Caucasian woman, without prior history of atopic dermatitis or eczema, presented to an outside dermatologist with a generalized, severely pruritic eruption involving the entire body except the face. One month previously, she had used a 50% trichloroacetic acid tattoo removal solution on a blue-colored tattoo on the medial aspect of the left ankle. The patient's eruption persisted for 7 months, and after several attempts to slowly taper her prednisone dose, she presented to our institution. On physical examination, there was a 3-cm erythematous, lichenified plaque surrounding the tattoo (Figure). On the trunk and upper regions of the arms, there were scattered, 1- to 2-cm, nummular patches and plaques. Biopsy of a truncal lesion revealed spongiotic pustules with a mixed dermal infiltrate and scattered eosinophils, consistent with subacute spongiotic dermatitis.

Folic acid attenuates cobalt chloride-induced PGE2 production in HUVECs via the NO/HIF-1alpha/COX-2 pathway.

Prostaglandin E2 (PGE2), an important lipid inflammatory mediator involved in the progression of vascular diseases, can be induced by hypoxia in many cell types. While folic acid has been shown to protect against inflammation in THP-1 cells during hypoxia and hypoxia-induced endothelial cell injury, whether it might do so by attenuating PGE2 production remains unclear. To investigate this we constructed a hypoxia-induced injury model by treating human umbilical vein endothelial cells (HUVECs) with cobalt chloride (CoCl2), which mimics the effects of hypoxia. In CoCl2-treated HUVECs, folic acid significantly attenuated PGE2 production and increased vasoprotective nitric oxide (NO) content. Folic acid also decreased cyclooxygenase-2 (COX-2) and hypoxia-inducible factor 1-alpha (HIF-1α) expression and altered endothelial nitric oxide synthase (eNOS) signaling by increasing p-eNOS(Ser1177) and decreasing p-eNOS(Thr495) in a dose-dependent manner. Further investigation of the pathway demonstrated that treatment with 2-Methoxyestradiol (2-MeOE2) and celecoxib both decreased CoCl2-induced COX-2 expression but only 2-MeOE2 decreased HIF-1α expression. The ability of folic acid to down-regulate HIF-1α and COX-2 protein levels was dramatically abrogated by L-NAME treatment, which also decreased eNOS mRNA and NO production. The NO donor sodium nitroprusside also dose-dependently down-regulated HIF-1α and COX-2 protein levels. Overall, these findings suggest a novel application for folic acid in attenuating CoCl2-induced PGE2 production in HUVECs via regulation of the NO/HIF-1α/COX-2 pathway.

Immunostimulatory capacity of dental casting alloys on endotoxin responsiveness.

STATEMENT OF PROBLEM: Oral metal exposure has been associated with systemic and local adverse reactions, probably due to elemental release from the alloys. Although supraphysiological concentrations of salts from dentally applied metals can activate innate cells through TLR4 (Ni, Co, Pd) and TLR3 (Au), whether direct exposure to solid alloys can also trigger innate immune reactivity is still unknown. PURPOSE: The purpose of this in vitro study was to determine whether dental cast alloy specimens can activate innate cells and influence their responsiveness to bacterial endotoxin. MATERIAL AND METHODS: Human monocyte-derived dendritic cells (MoDC) and THP-1 cells were cultured on top of different alloy specimens (Ni-Cr, Co-Cr, Pd-Cu, Pd-Ag, Ti-6Al-4V, amalgam, gold, and stainless steel) or in alloy-exposed culture medium with or without endotoxin (lipopolysaccharide [LPS]; Escherichia coli 055:B5). Interleukin-8 (IL-8) production was used as the parameter for innate stimulation and evaluated by enzyme-linked immunosorbent assay after 24 hours of culture. The statistical significance of the effects of various casting alloys on the secretion of IL-8 was analyzed by using the nonparametric Wilcoxon rank sum test (α=.05). RESULTS: Dental cast alloys induced IL-8 production in MoDC and THP-1 cells, with Au and Pd-Cu providing the strongest stimulation. The alloy-exposed culture media tested contained sufficient stimulatory metal ions to induce detectable IL-8 production in THP-1 cells, except for the Ni-Cr and stainless steel exposed media. Au and Pd-Cu alloys were also most effective in potentiating LPS responsiveness as measured by IL-8 production. CONCLUSIONS: Using an in vitro culture system to expose MoDC and THP-1 cells to different alloy specimens this study showed that contact with the solid alloys, in particular when they contain Pd or Au, can trigger innate immune responses and augment responsiveness to bacterial endotoxin.

[Coronary Artery Bypass Grafting for In-stent Restenosis Probably Caused by Allergic Response;Report of a Case].

A 58-year-old female presented to our hospital with recurrence of chest pain. She had undergone coronary intervention using biolimus-eluting-stent for total occlusion of the left anterior descending artery(LAD) 3 years before. Since then in-stent restenosis had repeated 4 times in 3 years. In the interim, another everolimus-eluting-stent had been placed on the same lesion. The contact metal allergic patch test revealed the existence of allergic response to nickel and cobalt which were the structural components of these stents. She underwent off-pump coronary artery bypass grafting, and these stents were removed. The invasions of macrophages and eosinophils around the stent-s were pathologically proven. One year after surgery she is doing well without angina or allergic symptom. These observations suggested the allergic reaction of the coronary artery against the stents.

Immune response in adverse reactions to metal debris following metal-on-metal total hip arthroplasty.

BACKGROUND: The purpose of the present study was to determine whether T cell-mediated type IV hypersensitivity reactions could be a major cause of adverse reaction to metal debris (ARMD) after metal-on-metal total hip arthroplasty (THA). METHODS: Thirteen patients (1 man and 12 women; mean age 68 years, age range 60 to 83 years) with ARMD underwent revision surgery following metal-on-metal THA (15 hips). Lymphocyte stimulation testing was conducted. Periprosthetic tissue specimens underwent immunohistochemical studies. RESULTS: Lymphocyte stimulation testing showed that five patients were nickel-sensitive, and one patient was also cobalt-sensitive. Immunohistochemical studies showed that T cells were dominant in five hips, and B cells were dominant in 10 hips. In four of the five patients with a positive lymphocyte stimulation test, the dominant lymphocytes were T cells, suggesting type IV hypersensitivity. The major cause of ARMD was not type IV hypersensitivity in the remaining nine patients. CONCLUSION: Metal hypersensitivity does not appear to be the dominant biological reaction involved in the occurrence of ARMD.

Cobalt.

Cobalt has been a recognized allergen capable of causing contact dermatitis for decades. Why, therefore, has it been named 2016 "Allergen of the Year"? Simply put, new information has come to light in the last few years regarding potential sources of exposure to this metallic substance. In addition to reviewing some background on our previous understanding of cobalt exposures, this article will highlight the recently recognized need to consider leather as a major site of cobalt and the visual cues suggesting the presence of cobalt in jewelry. In addition, a chemical spot test for cobalt now allows us to better identify its presence in suspect materials.

Recent trends in epidemiology, sensitization and legal requirements of selected relevant contact allergens.

Numerous studies have focused on emerging allergens causing contact allergy and allergic contact dermatitis in eczema populations and the general population, whereas only a few European multicenter studies systematically manage to detect prevalence rates of various contact allergies over time in eczema populations. Contact allergy is a life-time condition, which may lead to allergic contact dermatitis in individuals who do not manage to avoid exposure to the ascertained allergen in question. It is therefore of utmost importance that clinicians and dermatologists have sufficient knowledge on common allergens causing contact allergies in the general and working population. This review aimed to highlight the newest knowledge of frequent allergens of clinical importance. Literature was sought from the Pubmed™ database, Google™ scholar and textbooks. On the basis of the literature within the last 5 years, a comprehensive review of methylisothiazolinone, chromium, cobalt, rubber accelerators and fragrance ingredients were conducted. Of each allergen we discuss in detail the temporal trend of prevalence, source of exposure, clinical manifestation of allergic contact dermatitis and legislative measurements on how to regulate the exposure.

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.

Nickel acts as an adjuvant during cobalt sensitization.

Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses in the draining lymph nodes compared to mice sensitized with cobalt alone. In contrast, the presence of cobalt during nickel sensitization only induced an increased CD8(+) T cell proliferation during challenge to nickel. Thus, the presence of nickel during cobalt sensitization potentiated the challenge response against cobalt more than the presence of cobalt during sensitization to nickel affected the challenge response against nickel. Taken together, our study demonstrates that sensitization with a mixture of nickel and cobalt leads to an increased immune response to both nickel and cobalt, especially to cobalt, and furthermore that the adjuvant effect appears to correlate with the inflammatory properties of the allergen.

Heavy metal (monoclonal) bands: a link between cutaneous T-cell lymphoma and contact allergy to potassium dichromate, nickel and cobalt?

It has been proposed that chronic antigenic stimulation plays a role in the pathogenesis of cutaneous T-cell lymphoma (CTCL). By definition, antigenic stimulation triggers allergic contact dermatitis (ACD). It is therefore plausible that chronic ACD could serve as a precursor to CTCL. We report two cases of contact allergy to potassium dichromate, nickel and cobalt, where CTCL was diagnosed in one patient, and a diagnosis of CTCL is imminent in the other. We also review the literature on the diagnostic criteria for CTCL in the setting of ACD and explore potential mechanisms for the progression from ACD tos CTCL.

The immunobiology of cobalt: demonstration of a potential aetiology for inflammatory pseudotumours after metal-on-metal replacement of the hip.

Abnormal wear of cobalt-containing metal-on-metal joints is associated with inflammatory pseudotumours. Cobalt ions activate human toll-like receptor 4 (TLR4), which normally responds to bacterial lipopolysaccharide (LPS) in sepsis. Activation of TLR4 by LPS increases the expression of chemokines IL-8 and CXCL10, which recruit leukocytes and activated T-cells, respectively. This study was designed to determine whether cobalt induces a similar inflammatory response to LPS by promoting the expression of IL-8 and CXCL10. A human monocytic cell line, derived from acute monocytic leukaemia, was treated with cobalt ions and expression of IL-8 and CXCL10 measured at mRNA and protein levels. Cobalt-treated macrophages showed a 60-fold increase in IL-8 mRNA, and an eightfold increase in production of the mature chemokine (both p < 0.001); expression of the CXCL10 gene and protein was also significantly increased by cobalt (both p < 0.001). Experiments were also performed in the presence of CLI-095, a TLR4-specific antagonist which abrogated the cobalt-mediated increase in IL-8 and CXCL10 expression. These findings suggest that cobalt ions induce inflammation similar to that observed during sepsis by the simultaneous activation of two TLR4-mediated signalling pathways. These pathways result in increased production of IL-8 and CXCL10, and may be implicated in pseudotumour formation following metal-on-metal replacement.

Metal sensitivities among TJA patients with post-operative pain: indications for multi-metal LTT testing.

Metal sensitivity testing is generally the diagnosis method of last resort for aseptic painful implants with elevated inflammatory responses. However, the relationship between implant-related pain and implant-debris-related metal sensitization remains incompletely understood. Although a sensitivity to nickel alone has been used as a general measure of metal allergy, it may lack the specificity to correlate sensitivity to specific implant metals and thus to select a biologically appropriate implant material. In this retrospective study, we report the incidence of pain and nickel sensitivity in patients with total joint arthroplasties (TJAs) referred for metal sensitivity testing (n=2018). We also correlated the degree of nickel hypersensitivity to implant pain levels (none, mild, moderate, and high, using a scale of 0-10) and the incidence of sensitivity to alternative implant metals in highly nickel-reactive subjects. Most patients (>79%) reported pain levels that were moderate to high regardless of implant age, whereas patients with severely painful TJAs had a statistically greater incidence of nickel sensitivity over the short-term post-operative period (≤4 years). Patients with moderate pain scores (4-7) and high pain scores (≥8) also exhibited significantly higher sensitivity to nickel compared to patients with no pain and no implant (controls) (p<0.05). Highly nickel-sensitive subjects (SI>8) also showed incidences of sensitization to alternative materials such as cobalt, chromium, or molybdenum (57%) or aluminum or vanadium alloy (52%). These data suggest that painful TJAs caused by metal sensitivity more likely occur relatively early in the post-operative period (≤4 years). The incidences of sensitivity to alternative implant metals in only a subset of nickel-reactive patients highlights the importance of testing for sensitization to all potential revision implant materials.