CXCL4 is a novel nickel-binding protein and augments nickel allergy.
BACKGROUND
Nickel (Ni) is the most frequent metal allergen and induces a TH1-dependent type-IV allergy. Although Ni2+is considered to bind to endogenous proteins, it currently remains unclear whether these Ni-binding proteins are involved in Ni allergy in vivo. We previously reported the adjuvant effects of lipopolysaccharide (LPS) in a Ni allergy mouse model. As LPS induces a number of inflammatory mediators, we hypothesized that Ni-binding protein(s) are also induced by LPS.


OBJECTIVE
The objective of this study was to purify and identify Ni-binding protein(s) from serum taken from LPS-injected mice (referred as LPS serum) and examined the augmenting effects of these Ni-binding protein(s) on Ni allergy in an in vivo model.


METHODS
BALB/cA mice were sensitized with an i.p. injection of NiCl2and LPS. Ten days after sensitization, mice were challenged with NiCl2by an i.d. injection into ear pinnae. Ni-binding protein(s) were purified by Ni-affinity column chromatography and gel filtration.


RESULTS
Lipopolysaccharide serum, but not serum taken from saline-injected mice, augmented ear swelling induced by Ni-allergic inflammation. Ni-binding, but not non-binding fraction, purified from LPS serum augmented Ni-allergic inflammation. Mass spectrometry and Western blotting detected CXCL4 in the active fraction. A batch analysis with Ni-sepharose and a surface plasmon resonance analysis revealed direct binding between CXCL4 and Ni2+. Recombinant CXCL4 augmented Ni-allergic inflammation and exerted adjuvant effects at the sensitization phase.


CONCLUSIONS
These results indicate that CXCL4 is a novel Ni-binding protein that augments Ni allergy at the elicitation and sensitization phases. This is the first study to demonstrate that the Ni-binding protein augments Ni allergy in vivo.
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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http://orcid.org/0000-0003-1633-8615
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Kuroishi
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan.|Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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Bando
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan.|Division of Pediatric Dentistry, Department of Oral Health and Developmental Sciences, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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Tanaka
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan.|Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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Shishido
Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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Kinbara
Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
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Ogawa
Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
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Muramoto
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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Endo
Division of Oral Immunology, Department of Oral Biology, Tohoku University Graduate School of Dentistry, Sendai, Japan.
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Sugawara
D000818:Animals; D004195:Disease Models, Animal; D006967:Hypersensitivity / Q000097:blood / Q000276:immunology*; D008070:Lipopolysaccharides / Q000633:toxicity; D051379:Mice; D008807:Mice, Inbred BALB C; D009532:Nickel / Q000493:pharmacokinetics / Q000633:toxicity; D010978:Platelet Factor 4 / Q000097:blood / Q000276:immunology*
D008070:Lipopolysaccharides; D010978:Platelet Factor 4; C022838:nickel chloride; D009532:Nickel
CXCL4; contact hypersensitivity; metal allergy; nickel