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author:("brink, Magnus")
1.  The inflammatory response following an epidermal burn depends on the activities of mouse mast cell proteases 4 and 5 
A second degree epidermal scald burn in mice elicits an inflammatory response mediated by natural IgM directed to non-muscle myosin with complement activation that results in ulceration and scarring. We find that such burn injury is associated with early mast cell (MC) degranulation and is absent in WBB6F1-KitW/KitWv mice which lack MCs in a context of other defects due to a mutation of the KIT receptor. To further address a MC role, we used transgenic strains with normal lineage development and a deficiency in a specific secretory granule component. Mouse strains lacking the MC-restricted chymase, mouse MC protease (mMCP)-4, or elastase, mMCP-5, show decreased injury following a second degree scald burn while mice lacking the MC-restricted tryptases, mMCP-6 and mMCP-7, or the MC-specific carboxypeptidase A3 activity are not protected. Histologic sections showed some disruption of the epidermis at the scald site in the protected strains suggesting the possibility of topical reconstitution of full injury. Topical application of recombinant mMCP-5 or human neutrophil elastase to the scalded area increases epidermal injury with subsequent ulceration and scarring, both clinically and morphologically, in mMCP-5-deficent mice. Restoration of injury requires that topical administration of recombinant mMCP-5 occurs within the first h post burn. Importantly, topical application of human MC chymase restores burn injury to scalded mMCP-4-deficient mice but not to mMCP-5-deficient mice revealing non-redundant actions for these two MC proteases in a model of innate inflammatory injury with remodeling.
doi:10.4049/jimmunol.1002803
PMCID: PMC3058366  PMID: 21076070
2.  Neurotensin increases mortality and mast cells reduce neurotensin levels in a mouse model of sepsis 
Nature medicine  2008;14(4):392-398.
Sepsis is a complex, incompletely understood and often fatal disorder,1 typically accompanied by hypotension,2 that is considered to represent a dysregulated host response to infection.3,4,5 Neurotensin (NT) is a 13-amino-acid peptide that, among its multiple effects, induces hypotension.6 We find that intraperitoneal and plasma concentrations of NT are increased in mice after severe caecal ligation and puncture (CLP), a model of sepsis, and that mice treated with a pharmacological antagonist of NT, or NT-deficient mice, exhibit reduced mortality during severe CLP. In mice, mast cells can degrade NT and reduce NT-induced hypotension and CLP-associated mortality, and optimal expression of these effects requires mast cell expression of neurotensin receptor 1 and neurolysin. These findings show that NT contributes to sepsis-related mortality in mice during severe CLP and that mast cells can lower NT concentrations, and suggest that mast cell-dependent reduction in NT levels contributes to the ability of mast cells to enhance survival after CLP.
doi:10.1038/nm1738
PMCID: PMC2873870  PMID: 18376408
3.  Independent degeneration of photoreceptors and retinal pigment epithelium in conditional knockout mouse models of choroideremia 
Journal of Clinical Investigation  2006;116(2):386-394.
Choroideremia (CHM) is an X-linked degeneration of the retinal pigment epithelium (RPE), photoreceptors, and choroid, caused by loss of function of the CHM/REP1 gene. REP1 is involved in lipid modification (prenylation) of Rab GTPases, key regulators of intracellular vesicular transport and organelle dynamics. To study the pathogenesis of CHM and to develop a model for assessing gene therapy, we have created a conditional mouse knockout of the Chm gene. Heterozygous-null females exhibit characteristic hallmarks of CHM: progressive degeneration of the photoreceptors, patchy depigmentation of the RPE, and Rab prenylation defects. Using tamoxifen-inducible and tissue-specific Cre expression in combination with floxed Chm alleles, we show that CHM pathogenesis involves independently triggered degeneration of photoreceptors and the RPE, associated with different subsets of defective Rabs.
doi:10.1172/JCI26617
PMCID: PMC1326146  PMID: 16410831

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