Clark Lantz

Clark Lantz

Professor, Cellular and Molecular Medicine
Investigator, Center for Toxicology
Professor, Public Health
Professor, BIO5 Institute
Primary Department
Department Affiliations
Contact
(520) 626-6084

Work Summary

We are interested in the effects of early life exposures to environmental toxicants on lung growth and development. We determine if the early life exposures leads to adult disease.

Research Interest

R. Clark Lantz, PhD Exposure to environmental toxicants alters lung structure and function and leads to chronic lung disease, including cancer. Current investigations are examining the effects of exposure to environmentally relevant doses of arsenic and uranium. Arsenic is a naturally occurring metalloid found in water, soil and air. Exposure to inorganic arsenic occurs worldwide through environmental (contaminated drinking water, air, food and domestic fuel sources) and occupational exposures (smelting industries, pesticide production). In addition to its association with non-malignant diseases, arsenic is of major worldwide health concern because of its carcinogenic potential in humans. Epidemiologic studies have associated arsenic exposure with an increased risk of multiple human cancers including lung, skin, bladder, kidney, liver and stomach cancers. Our current research is focusing on two models to examine the effects of arsenic in the lung. One model relies on exposure to arsenic during lung development, both in utero and postnatally. We have shown that exposure of pregnant female mice and their offspring to 50 or 100 ppb as arsenic in drinking water resulted in altered pulmonary function in 28 day old animals. Airways were more responsive to bronchoconstriction. These changes were specific for exposure during development and were not reversible if arsenic was withdrawn. Associated with these functional changes, arsenic exposure resulted in a dose-dependent increase in airway smooth muscle and alterations in airway connective tissue expression. We are currently analyzing mediators that may be involved in this response to arsenic. In addition, we are beginning investigations into the effect of inhalation of arsenic on lung development. We are also currently using in vitro airway epithelial cell cultures to determine the effects of arsenic on wound repair and epithelial barrier function. In collaboration with Dr. Scott Boitano, we have been able to show that arsenic inhibits wound repair. This may be due in part to arsenic- induced alteration in calcium signaling. We have also been able to show that arsenic alters expression of epithelial junctional proteins and decreases epithelial barrier resistance. Research is also on going to identify protein alterations in lung lining fluid as biomarkers of exposure and effect. This study uses the technology of proteomics to evaluate and identify biomarkers of chronic environmental exposure to arsenic by evaluating large numbers of proteins simultaneously. We are comparing alterations in protein expression in exposed human populations in Arizona and Mexico, human cell lines, and in vivo rodent studies. Patterns of alterations in protein expression, both common and unique to these different test systems, will be identified. Finally, we are evaluating the chemical genotoxicity of uranium. In addition to its radioactive effects, uranium may also have adverse health effects because of its interactions with cellular macromolecules. We have found that uranium causes DNA damage through forming adducts which results in single strand breaks. In addition, uranium also inhibits double strand break DNA repair in airway epithelial cells. Keywords: pulmonary toxicology, arsenic, early life exposures

Publications

Recio-Vega, R., Gonzalez-Cortes, T., Olivas-Calderon, E., Lantz, R. C., Gandolfi, A. J., & Alba, C. G. (2015). In utero and early childhood exposure to arsenic decreases lung function in children. Journal of applied toxicology : JAT, 35(4), 358-66.

The lung is a target organ for adverse health outcomes following exposure to As. Several studies have reported a high prevalence of respiratory symptoms and diseases in subjects highly exposed to As through drinking water; however, most studies to date has been performed in exposed adults, with little information on respiratory effects in children. The objective of the study was to evaluate the association between urinary levels of As and its metabolites with lung function in children exposed in utero and in early childhood to high As levels through drinking water. A total of 358 healthy children were included in our study. Individual exposure was assessed based on urinary concentration of inorganic As. Lung function was assessed by spirometry. Participants were exposed since pregnancy until early childhood to an average water As concentration of 152.13 µg l(-1) . The mean urinary As level registered in the studied subjects was 141.2 µg l(-1) and only 16.7% had a urinary concentration below the national concern level. Forced vital capacity was significantly decreased in the studied population and it was negatively associated with the percentage of inorganic As. More than 57% of the subjects had a restrictive spirometric pattern. The urinary As level was higher in those children with restrictive lung patterns when compared with the levels registered in subjects with normal spirometric patterns. Exposure to As through drinking water during in utero and early life was associated with a decrease in forced vital capacity and with a restrictive spirometric pattern in the children evaluated.

dos Santos, M. D., Chen, G., Almeida, M. C., Soares, D. M., de Souza, G. E., Lopes, N. P., & Lantz, R. C. (2010). Effects of caffeoylquinic acid derivatives and C-flavonoid from Lychnophora ericoides on in vitro inflammatory mediator production. Natural product communications, 5(5), 733-40.

In this study we aimed at evaluating the effect of the major polar constituents of the medicinal plant Lychnophora ericoides on the production of inflammatory mediators produced by LPS-stimulated U-937 cells. The 6,8-di-C-beta-glucosylapigenin (vicenin-2) presented no effect on tumor necrosis factor (TNF)-alpha production, but inhibited, in a dose-dependent manner, the production of prostaglandin (PG) E2 without altering the expression of cyclooxygenase (COX)-2 protein. 3,5-Dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid, at lower concentrations, had small but significant effects on reducing PGE2 levels; at higher doses these compounds stimulated PGE2 and also TNF-alpha production by the cells. All the caffeoylquinic acid derivatives, in a dose-dependent fashion, were able to inhibit monocyte chemoattractant protein-3 synthesis/release, with 4,5-DCQ being the most potent at the highest tested concentration. These results add important information on the effects of plant natural polyphenols, namely vicenin-2 and caffeoylquinic acid derivatives, on the production of inflammatory mediators by cultured cells.

Jolad, S. D., Lantz, R. C., Solyom, A. M., Chen, G. J., Bates, R. B., & Timmermann, B. N. (2004). Fresh organically grown ginger (Zingiber officinale): composition and effects on LPS-induced PGE2 production. Phytochemistry, 65(13), 1937-54.

Gas chromatography in conjunction with mass spectrometry, a technique previously employed to analyze non-volatile pungent components of ginger extracts modified to trimethylsilyl derivatives, was applied successfully for the first time to analyze unmodified partially purified fractions from the dichloromethane extracts of organically grown samples of fresh Chinese white and Japanese yellow varieties of ginger, Zingiber officinale Roscoe (Zingiberaceae). This analysis resulted in the detection of 20 hitherto unknown natural products and 31 compounds previously reported as ginger constituents. These include paradols, dihydroparadols, gingerols, acetyl derivatives of gingerols, shogaols, 3-dihydroshogaols, gingerdiols, mono- and diacetyl derivatives of gingerdiols, 1-dehydrogingerdiones, diarylheptanoids, and methyl ether derivatives of some of these compounds. The thermal degradation of gingerols to gingerone, shogaols, and related compounds was demonstrated. The major constituent in the two varieties was [6]-gingerol, a chemical marker for Z. officinale. Mass spectral fragmentation patterns for all the compounds are described and interpreted. Anti-inflammatory activities of silica gel chromatography fractions were tested using an in vitro PGE2 assay. Most of the fractions containing gingerols and/or gingerol derivatives showed excellent inhibition of LPS-induced PGE2 production.

Wong, S. S., Vargas, J., Thomas, A., Fastje, C., McLaughlin, M., Camponovo, R., Lantz, R. C., Heys, J., & Witten, M. L. (2008). In vivo comparison of epithelial responses for S-8 versus JP-8 jet fuels below permissible exposure limit. Toxicology, 254(1-2), 106-11.

This study was designed to characterize and compare the pulmonary effects in distal lung from a low-level exposure to jet propellant-8 fuel (JP-8) and a new synthetic-8 fuel (S-8). It is hypothesized that both fuels have different airway epithelial deposition and responses. Consequently, male C57BL/6 mice were nose-only exposed to S-8 and JP-8 at average concentrations of 53mg/m(3) for 1h/day for 7 days. A pulmonary function test performed 24h after the final exposure indicated that there was a significant increase in expiratory lung resistance in the S-8 mice, whereas JP-8 mice had significant increases in both inspiratory and expiratory lung resistance compared to control values. Neither significant S-8 nor JP-8 respiratory permeability changes were observed compared to controls, suggesting no loss of epithelial barrier integrity. Morphological examination and morphometric analysis of airway tissue demonstrated that both fuels showed different patterns of targeted epithelial cells: bronchioles in S-8 and alveoli/terminal bronchioles in JP-8. Collectively, our data suggest that both fuels may have partially different deposition patterns, which may possibly contribute to specific different adverse effects in lung ventilatory function.

Freels, J. L., Nelson, D. K., Hoyt, J. C., Habib, M., Numanami, H., Lantz, R. C., & Robbins, R. A. (2002). Enhanced activity of human IL-10 after nitration in reducing human IL-1 production by stimulated peripheral blood mononuclear cells. Journal of immunology (Baltimore, Md. : 1950), 169(8), 4568-71.

Nitric oxide and superoxide form the unstable compound, peroxynitrite, which can nitrate proteins and compromise function of proinflammatory cytokines at sites of inflammation. Reduced function of proinflammatory proteins such as IL-8, macrophage inflammatory protein-1alpha, and eotaxin suggest an anti-inflammatory effect of nitration. The effects of nitration on anti-inflammatory cytokines such as IL-10 are unknown. We hypothesized that peroxynitrite would modify the function of anti-inflammatory cytokines like IL-10. To test this hypothesis, the capacity of recombinant human IL-10 to inhibit production of human IL-1beta (IL-1) from LPS-stimulated human PBMC was evaluated. Human IL-10 was nitrated by incubation with peroxynitrite or by incubation with 3-morpholinosydnonimine, a peroxynitrite generator, for 2 h and then incubated with LPS-stimulated PBMC for 6 h, and IL-1 was measured in the culture supernatant fluids. Human IL-1 production was significantly lower in the peroxynitrite- or 3-morpholinosydnonimine-nitrated IL-10 group than in the IL-10 controls (p 0.05, all comparisons). This finding demonstrates that although peroxynitrite inhibits proinflammatory cytokines, it may augment anti-inflammatory cytokines and further point to an important role for peroxynitrite in the regulation of inflammation.