I never thought about being allergic to metals before I ran across this study. LPS is the toxin suspected in the neuroinflammatory hypothesis of PD. Prenatally it can disrupt dopamine producing capacity of the adult and set up a hypersensitivity that ultimately destroys the SN. It causes widespread inflammation which weakens the BBB as well. Now add in the triggering of metal allergies with the weakened BBB allowing more metals to pass...


1. Clin Exp Allergy. 2007 May;37(5):743-51.

Lipopolysaccharide promotes and augments metal allergies in mice, dependent on
innate immunity and histidine decarboxylase.

Sato N, Kinbara M, Kuroishi T, Kimura K, Iwakura Y, Ohtsu H, Sugawara S, Endo Y.

Department of Fixed Prosthodontics, Graduate School of Dentistry, Tohoku
University, Sendai, Japan.

BACKGROUND: Few adequate murine models exist for metal allergies, it being
especially difficult to induce Ni allergy in mice. OBJECTIVE: We examined the
effect of lipopolysaccharide (LPS) on allergies to Ni and other metals in mice.
METHODS: Ten days after sensitization with a metal salt and LPS, the ears were
challenged with the same metal salt. RESULTS: LPS+NiCl(2) (1 mM) was effective at
sensitizing mice to Ni, LPS being effective at very low concentrations whether
injected intradermally or intraperitoneally. The ear-swelling response to Ni was
more severe and more rapid in C57BL/6 mice than in BALB/c mice. In
mast-cell-deficient mice, TNF-alpha-deficient mice, and interestingly even in
nude (T cell deficient) mice, NiCl(2)+LPS induced a Ni allergy similar in degree
to that in the respective control mice, but it induced Ni allergy only weakly in
TLR4-mutant mice, macrophage-depleted mice, and IL-1-deficient mice. The activity
of the histamine-forming enzyme histidine decarboxylase (HDC) in the ears
increased in parallel with ear swelling, and HDC-deficient mice were resistant to
ear swelling. Challenge with NiCl(2)+LPS augmented ear swelling (vs. NiCl(2)
alone). LPS induced effective sensitization to other metals (Cr, Co, Pd, or Ag).
CONCLUSIONS: These results indicate that in mice, LPS is a very important inducer
of metal allergies, and potently promotes them (dependent on both innate immunity
and HDC induction in cells other than mast cells). We discussed the idea that the
bacterial environment is important for the establishment of metal allergies and
for their provocation, and that the current thinking (including the contribution
of T cells) should be reappraised in future studies.

PMID: 17456222 [PubMed - indexed for MEDLINE]