Evaluation of skin irritation following weathered crude oil exposure in two mouse strains
TOXICOLOGY AND INDUSTRIAL HEALTH
Authors: Kemp, Jesse M.; Luckett-Chastain, Lerin R.; Calhoun, Kaitlin N.; Frempah, Benjamin; Schartz, Tayler R.; Harty, Linda E.; Kemp, Philip M.; Gallucci, Randle M.
Abstract
Petroleum crude oil spills are common and vary in size and scope. Spill response workers throughout the course of remediation are exposed to so-called weathered oil and are known to report diverse health effects, including contact dermatitis. A murine model of repeated exposure to weathered marine crude oil was employed utilizing two strains of mice, C57BL/6 and BALB/c, to investigate the pathology of this irritant and identify the principal hydrocarbon components deposited in skin. Histopathology demonstrated clear signs of irritation in oil-exposed skin from both mouse strains, characterized by prominent epidermal hyperplasia (acanthosis). BALB/c mice exposed to oil demonstrated more pronounced irritation compared with C57BL/6 mice, which was characterized by increased acanthosis as well as increased inflammatory cytokine/chemokine protein expression of IL-1 beta, IL-6, CXCL10, CCL2, CCL3, CCL4, and CCL11. A gas chromatography/mass spectrometry method was developed for the identification and quantification of 42 aliphatic and EPA priority aromatic hydrocarbons from full thickness skin samples of C57BL/6 and BALB/c mice exposed to oil samples. Aromatic hydrocarbons were not detected in skin; however, aliphatic hydrocarbons in skin tended to accumulate with carbon numbers greater than C16. These preliminary data and observations suggest that weathered crude oil is a skin irritant and this may be related to specific hydrocarbon components, although immune phenotype appears to impact skin response as well.
Roles of the DOCK-D family proteins in a mouse model of neuroinflammation
JOURNAL OF BIOLOGICAL CHEMISTRY
Authors: Namekata, Kazuhiko; Guo, Xiaoli; Kimura, Atsuko; Azuchi, Yuriko; Kitamura, Yuta; Harada, Chikako; Harada, Takayuki
Abstract
The DOCK-D (dedicator of cytokinesis D) family proteins are atypical guanine nucleotide exchange factors that regulate Rho GTPase activity. The family consists of Zizimin1 (DOCK9), Zizimin2 (DOCK11), and Zizimin3 (DOCK10). Functions of the DOCK-D family proteins are presently not well-explored, and the role of the DOCK-D family in neuroinflammation is unknown. In this study, we generated three mouse lines in which DOCK9 (DOCK9(?/?)), DOCK10 (DOCK10(?/?)), or DOCK11 (DOCK11(?/?)) had been deleted and examined the phenotypic effects of these gene deletions in MOG(35?55) peptide-induced experimental autoimmune encephalomyelitis, an animal model of the neuroinflammatory disorder multiple sclerosis. We found that all the gene knockout lines were healthy and viable. The only phenotype observed under normal conditions was a slightly smaller proportion of B cells in splenocytes in DOCK10(?/?) mice than in the other mouse lines. We also found that the migration ability of macrophages is impaired in DOCK10(?/?) and DOCK11(?/?) mice and that the severity of experimental autoimmune encephalomyelitis was ameliorated only in DOCK10(?/?) mice. No apparent phenotype was observed for DOCK9(?/?) mice. Further investigations indicated that lipopolysaccharide stimulation up-regulates DOCK10 expression in microglia and that microglial migration is decreased in DOCK10(?/?) mice. Up-regulation of C?C motif chemokine ligand 2 (CCL2) expression induced by activation of Toll-like receptor 4 or 9 signaling was reduced in DOCK10(?/?) astrocytes compared with WT astrocytes. Taken together, our findings suggest that DOCK10 plays a role in innate immunity and neuroinflammation and might represent a potential therapeutic target for managing multiple sclerosis.