Effects of metal compounds with distinct physicochemical properties on iron homeostasis and antibacterial activity in the lungs: chromium and vanadium.
In situ reactions of metal ions or their compounds are important mechanisms by which particles alter lung immune responses. The authors hypothesized that major determinants of the immunomodulatory effect of any metal include its redox behavior/properties, oxidation state, and/or solubility, and that the toxicities arising from differences in physicochemical parameters are manifest, in part, via differential shifts in lung iron (Fe) homeostasis. To test the hypotheses, immunomodulatory potentials for both pentavalent vanadium (VV; as soluble metavanadate or insoluble vanadium pentoxide) and hexavalent chromium (CrVI; as soluble sodium chromate or insoluble calcium chromate) were quantified in rats after inhalation (5h/day for 5 days) of each at 100 microg metal/m3. Differences in effects on local bacterial resistance between the two VV, and between each CrVI, agents suggested that solubility might be a determinant of in situ immunotoxicity. For the soluble forms, VV had a greater impact on resistance than CrVI, indicating that redox behavior/properties was likely also a determinant. The soluble VV agent was the strongest immunomodulant. Regarding Fe homeostasis, both VV agents had dramatic effects on airway Fe levels. Both also impacted local immune/airway epithelial cell Fe levels in that there were significant increases in production of select cytokines/chemokines whose genes are subject to regulation by HIF-1 (whose intracellular longevity is related to cell Fe status). Our findings contribute to a better understanding of the role that metal compound properties play in respiratory disease pathogenesis and provide a rationale for differing pulmonary immunotoxicities of commonly encountered ambient metal pollutants.
Cohen
Mitchell D
MD
Department of Environmental Medicine, New York University School of Medicine, Tuxedo, New York, USA.
Sisco
Maureen
M
Prophete
Colette
C
Yoshida
Kotaro
K
Chen
Lung-chi
LC
Zelikoff
Judith T
JT
Smee
Jason
J
Holder
Alvin A
AA
Stonehuerner
Jacqueline
J
Crans
Debbie C
DC
Ghio
Andrew J
AJ
D000818:Animals; D000900:Anti-Bacterial Agents; D001273:Atmosphere Exposure Chambers; D001822:Body Burden; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D018932:Chemokine CCL2 / Q000378:metabolism; D002857:Chromium / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity*; D005293:Ferritins / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects*; D007109:Immunity / Q000187:drug effects; D007501:Iron / Q000378:metabolism*; D033862:Iron-Binding Proteins / Q000378:metabolism; D008089:Listeria monocytogenes / Q000187:drug effects; D008168:Lung / Q000187:drug effects* / Q000276:immunology / Q000382:microbiology*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D014168:Transferrin / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014639:Vanadium / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity*
D000900:Anti-Bacterial Agents; C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D033862:Iron-Binding Proteins; D014168:Transferrin; D014409:Tumor Necrosis Factor-alpha; D014639:Vanadium; D002857:Chromium; D005293:Ferritins; D007501:Iron