Spectrophotometric Determination of Nickel in Calcium Metal Using 1,2-Cyclohexanedionedioxime

Surfactant-associated protein B is critical to survival in nickel-induced injury in mice

The etiology of acute lung injury is complex and associated with numerous, chemically diverse precipitating factors. During acute lung injury in mice, one key event is epithelial cell injury that leads to reduced surfactant biosynthesis. We have previously reported that transgenic mice that express transforming growth factor alpha (TGFA) in the lung were protected during nickel-induced lung injury. Here, we find that the mechanism by which TGFA imparts protection includes maintenance of surfactant-associated protein B (SFTPB) transcript levels and epidermal growth factor receptor-dependent signaling in distal pulmonary epithelial cells. This protection is complex and not accompanied by a diminution in inflammatory mediator transcripts or additional stimulation of antioxidant transcripts. In mouse lung epithelial (MLE-15) cells, microarray analysis demonstrated that nickel increased transcripts of genes enriched in MTF1, E2F-1, and AP-2 transcription factor-binding sites and decreased transcripts of genes enriched in AP-1-binding sites. Nickel also increased Jun transcript and DNA-binding activity, but decreased SFTPB transcript. Expression of SFTPB under the control of a doxycycline-sensitive promoter increased survival during nickel-induced injury as compared with control mice. Together, these findings support the idea that maintenance of SFTPB expression is critical to survival during acute lung injury.

Inhibition of nitric oxide restores surfactant gene expression following nickel-induced acute lung injury

The role of nitric oxide (NO) in acute lung injury remains controversial. Although inhaled NO increases oxygenation in clinical trials, inhibiting NO-synthase (NOS) can be protective. To examine the latter, nickel-exposed mice were treated with saline or NOS inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME). Initial microarray analysis of nickel-induced gene expression of saline-treated mice revealed increased inflammatory mediator, matrix injury-repair, and hypoxia-induced factor-mediated sequences and decreased lung-specific (e.g., surfactant-associated protein B and C) sequences. Compared with saline control, L-NAME-treated mice had enhanced survival with attenuated serum nitrate/nitrite, endothelial NOS activity, and lavage neutrophils and protein. Although initial cytokine (i.e., interferon-gamma, interleukins-1beta and -6, macrophage inflammatory protein-2, monocyte chemotactic protein-1, and tumor necrosis factor-alpha) gene expression was similar between groups, subsequent larger cytokine increases only occurred in saline-treated mice. Similarly, surfactant protein gene expression decreased initially in both groups yet was restored subsequently with L-NAME treatment. Interestingly, the role of inducible NOS (iNOS) in these responses seems minimal. iNOS gene expression was unaltered, iNOS activity and nitrotyrosine residues were undetectable, and an iNOS antagonist, aminoguanidine, failed to increase survival. Rather, systemic L-NAME treatment appears to attenuate pulmonary endothelial NOS activity, subsequent cytokine expression, inflammation, and protein permeability, and thereby restores surfactant gene expression and increases survival.

Dose-related protection from nickel-induced lung injury in transgenic mice expressing human transforming growth factor-alpha

To determine the role of transforming growth factor-alpha (TGF-alpha) in protecting the lung from aerosolized nickel injury, transgenic mouse lines expressing human TGF-alpha in the pulmonary epithelium, under control of the human surfactant protein-C gene promoter, were tested. Higher expressing TGF-alpha transgenic mouse lines, expressing distinct levels of TGF-alpha, survived longer than nontransgenic control mice. Increased survival correlated with levels of TGF-alpha expression in the lung. After 72 h of nickel exposure (70 microg Ni/m3), transgenic lines with intermediate levels of the TGF-alpha expression demonstrated attenuation of lung injury. The highest expressing line (line 28) demonstrated reduced lung inflammation and edema, reduced lung wet-to-dry weight ratios, decreased bronchoalveolar lavage (BAL) protein and neutrophils, reduced interleukin (IL)-1beta, interleukin-6, and macrophage inflammatory protein-2, and maintained surfactant protein-B (SP-B) levels compared with nontransgenic controls. In the TGF-alpha transgenic mouse model, TGF-alpha protects against nickel-induced acute lung injury, at least in part, by attenuating the inflammatory response, reducing pulmonary edema, and preserving levels of SP-B.

Quantitative trait analysis of nickel-induced acute lung injury in mice

The genetic determinants underlying susceptibility to acute lung injury have not been identified. Recently, we found that the strain distribution pattern for mean survival time (MST) to three irritants-ozone, ultrafine Teflon, and nickel sulfate- was shared between inbred mouse strains. For ozone-induced acute lung injury, survival was found to be a complex trait controlled by at least three quantitative trait loci (QTLs), designated Aliq1, Aliq2, and Aliq3. To explore whether similar genes might be involved in survival to acute lung injury induced by nickel sulfate, we took advantage of the 2-fold difference in MSTs between the sensitive A/J and resistant C57BL/6J mice. QTL analysis of 307 backcross mice generated from these strains identified significant linkage to chromosome 6 (proposed as Aliq4) and suggestive linkage on chromosomes 1 and 12. Loci on chromosomes 9 and 16 had lod scores (log of the odds ratio, which equals the log of the "likelihood of linkage divided by the likelihood of no linkage") below significance, but contributed to the overall response. Comparing MSTs of backcross mice with similar haplotypes identified an allelic combination of four QTLs that could account for the survival time difference between the parental strains. Similar QTL intervals on chromosomes 6 and 12 were previously identified with ozone, suggesting that the interplay between different combinations of relatively few genes might be important for irritant-induced acute lung injury survival.

Differential gene expression in the initiation and progression of nickel-induced acute lung injury

Acute lung injury, an often fatal condition, can result from a wide range of insults leading to a complex series of biologic responses. Despite extensive research, questions remain about the interplay of the factors involved and their role in acute lung injury. We proposed that assessing the temporal and functional relationships of differentially expressed genes after pulmonary insult would reveal novel interactions in the progression of acute lung injury. Specifically, 8,734 sequence-verified murine complementary DNAs were analyzed in mice throughout the initiation and progression of acute lung injury induced by particulate nickel sulfate. This study revealed the expression patterns of genes previously associated with acute lung injury in relationship to one another and also uncovered changes in expression of a number of genes not previously associated with acute lung injury. The overall pattern of gene expression was consistent with oxidative stress, hypoxia, cell proliferation, and extracellular matrix repair, followed by a marked decrease in pulmonary surfactant proteins. Also, expressed sequence tags (ESTs), with nominal homology to known genes, displayed similar expression patterns to those of known genes, suggesting possible roles for these ESTs in the pulmonary response to injury. Thus, this analysis of the progression and response to acute lung injury revealed novel gene expression patterns.

Genetic susceptibility to irritant-induced acute lung injury in mice

Recent studies suggest that genetic variability can influence irritant-induced lung injury and inflammation. To begin identifying genes controlling susceptibility to inhaled irritants, seven inbred mouse strains were continuously exposed to nickel sulfate (NiSO(4)), polytetrafluoroethylene, or ozone (O(3)), and survival time was recorded. The A/J (A) mouse strain was sensitive, the C3H/He (C3) strain was intermediate, and the C57BL/6 (B6) strain was resistant to NiSO(4)-induced acute lung injury. The B6AF(1) offspring were also resistant. The strain sensitivity pattern for NiSO(4) exposure was similar to that of polytetrafluoroethylene or ozone (O(3)). Pulmonary pathology was comparable for A and B6 mice. In the A strain, 15 microg/m(3) of NiSO(4) produced 20% mortality. The strain sensitivity patterns for lavage fluid proteins (B6 > C3 > A) and neutrophils (A >/= B6 > C3) differed from those for acute lung injury. This phenotype discordance suggests that these traits are not causally linked (i.e., controlled by independent arrays of genes). As in acute lung injury, B6C3F(1) offspring exhibited phenotypes (lavage fluid proteins and neutrophils) resembling those of the resistant parental strain. Agreement of acute lung injury strain sensitivity patterns among irritants suggested a common mechanism, possibly oxidative stress, and offspring resistance suggested that sensitivity is inherited as a recessive trait.