Pulmonary Immunotoxic Potentials of Metals Are Governed by Select Physicochemical Properties: Vanadium Agents

Figures & data

FIG. 1 Chemical structures of the V^III and V^IV dipic complexes used.

TABLE 1 Exposure parameters from the exposure studies

Exposure regimen	^aActual exposure level	^bMMAD
Sodium vanadate (NaVO3)	110.14 ± 3.59	0.21 μ m (σg = 2.1)
Vanadium pentoxide (V2O5)	132.62 ± 37.19	0.74 μ m (σg = 2.8)
V^IV dipic	108.24 ± 1.32	0.37 μ m (σg = 2.5)
V^III dipic	98.62 ± 2.38	0.24 μ m (σg = 1.9)

^aValues in terms of μ g V/m³ over the entire 5-d exposure period (mean ± SE).

^bMass median aerodynamic diameters

FIG. 2 Lung V burdens at Day 0 (i.e., pre-infection) and Day 3 of infection with Listeria. Each bar represents the average burden ([A] ng V; [B] ng V/g lung) (± SE) in the lungs of n = 5 (Day 0; solid bar) or n = 8–10 (Day 3; hatched bar) rats/treatment with V₂O₅ (insoluble V[V]), NaVO₃ (soluble V[V]), V^III dipic, or V^IV dipic. In Day 0 sets; *value significantly (p < 0.05) different from that in rats in all other groups; ^†value significantly (p < 0.05) different from that in soluble V^III dipic and V^IV dipic-treated rats. In Day 3 sets: *value significantly (p < 0.05) different from that in rats in all other groups; ^# value significantly (p < 0.05) different from that in soluble V^III dipic and V^IV dipic-treated rats.

FIG. 3 Average retention of V in the lungs of Listeria-infected rats in each V treatment group. Each bar represents the average retention (%; ± SE) of Day 0 burden in the lungs of n = 8–10 Day 3 rats per treatment with V₂O₅ (insoluble V[V]), NaVO₃ (soluble V[V]), V^III dipic, or V^IV dipic. Data analyzed in terms of ng V (solid bar) or of ng V/g lung (hatched bar). ^†Value significantly (p < 0.05) different from that in rats in the soluble V^III and V^IV groups.

FIG. 4 Listeria (bacterial) burdens in the lung of rats at each day postinfection. (A) V₂O₅; (B) NaVO₃; (C) V^IV dipic; (D) V^III dipic regimens. Values shown with ◊ represent the mean (± SE) of n = 6, 8, and 10 rats at 24, 48, and 72 hr post-infection/V regimen, respectively; values indicated with λ represent mean (± SE) of n = 5 air control rats at same timepoints. Statistical significance (p value) of result (V vs. air)—when present—is indicated.

TABLE 2 Relative difference in Listeria burden in lungs of rats at day 3 post-infection

Exposure regimen	^aAt 100 μ g V/m^3 level	^aAt 10 μ g V/m^3 level
Sodium vanadate (NaVO3)	^†435.43 ± 130.16	1.73 ± 22.23
Vanadium pentoxide (V2O5)	−23.46 ± 14.69	Exposure not performed
V^IV dipic	33.87 ± 23.38	Exposure not performed
V^III dipic	^†43.09 ± 12.57	−4.09 ± 16.71

^aEach value represents mean (± SE) average percentage difference in Listeria levels (compared to those in air controls) in lungs of 8–10 Day 3 rats/indicated treatment.

*Value significantly (p < 0.05) different from that in rats in 100 μ g V/m³ NaVO₃ group.

^†Value significantly (p < 0.05) different from that in respective experiment air control rats.

FIG. 5 Relative difference in Listeria burden in the lungs of rats at Day 3 postinfection as a function of Day 0 lung V burdens. Each bar represents the mean from n = 10 Day 3 rats/indicated treatment with 100 μ g V/m³ as V₂O₅ (insoluble V[V]), NaVO₃ (soluble V[V]), V^III dipic, or V^IV dipic; ± SE) average percentage differences in Listeria levels (LM; solid bar) or of total Listeria/g lung (LM/g; hatched bar) compared to respective values in air controls, in the context of ng V in lungs at Day 0. ^†Value significantly (p < 0.05) different from that in rats in soluble NaVO₃ group.

TABLE 3 Percentages of immune cell types in BAL fluid of day 0 rats

Exposure regimen	MACS	PMN	Lymphocyte
Sodium vanadate (NaVO3)	94.33 ± 1.13	0.08 ± 0.08	5.67 ± 1.13
Vanadium pentoxide (V2O5)	96.00 ± 0.41	0.22 ± 0.15	3.78 ± 0.43
V^IV dipic	93.40 ± 0.72	0.47 ± 0.26	6.13 ± 0.59
V^III dipic	87.92 ± 2.48	0.62 ± 0.21	11.39 ± 2.49

^aValues are percentage of cells in minimum of 100 cells counted per slide (mean ± SE).

*Value significantly (p < 0.05) different from that in rats in each of the other treatment regimens (n = 5 rats/regimen).