Histochemical and Ultrastructural Modification of Mucosal Mast Cell Granules in Parasitized Mice Lacking the β-Chymase, Mouse Mast Cell Protease-1

Abstract

The soluble beta-chymases mouse mast cell protease-1 (mMCP-1) and rat mast cell protease-II are predominantly expressed by intestinal mucosal mast cells (IMMCs) and may promote mucosal epithelial permeability when released during intestinal allergic hypersensitivity responses. To study the function of these chymases, we generated mice with a homozygous null mutation of the mMCP-1 gene and investigated their response to infection with the intestinal nematode Nippostrongylus brasiliensis. Whereas mMCP-2, -4, and -5 were transcribed normally, there was no transcription of the mMCP-1 gene in null (-/-) mice, nor was mature mMCP-1 protein detected in (-/-) jejunal mucosa. In contrast, levels of mMCP-1 in wild-type (+/+) jejunal mucosa increased 200- to 350-fold from 0.66 microg mMCP-1/g wet weight in uninfected mice to 129 and 229 microg/g wet weight on days 8 and 10 of infection, respectively. The kinetics of IMMC recruitment differed in -/- mice compared with +/+ controls on days 8 (P < 0.05) and 10 (P < 0.03) of infection. The IMMCs in infected -/- mice stained poorly, if at all, for esterase with naphthol AS-D chloroacetate compared with the intense staining observed in +/+ controls. Ultrastructurally, the prominent crystal intragranular structures that are found in intraepithelial +/+ IMMCs were absent from -/- IMMCs. These data show that disruption of the mMCP-1 gene leads to profound histochemical and ultrastructural changes in IMMC granules.

Immunomodulatory mast cells: negative, as well as positive, regulators of immunity

“…Some of the positive immunomodulatory functions of mast cells that have been proposed based on in vitro studies have been confirmed in vivo using mast cell knock-in mice 1,54,[57][58][59][60][61][62][63][64][65][66][67][68][69][70] or in mice lacking specific mast-cell-associated proteases [26][27][28][32][33][34] or lacking specific protease enzymatic activity 11 (Table 1 ). In many of these studies, the end points assessed included the recruitment of particular immune cells, such as granulocytes 28,32,33,[57][58][59][60][61]63,64,[67][68][69][70] , DCs 62,64,65,71 or various subpopulations of lymphocytes 64,67,70,72 .…”

“…If that mediator is selectively expressed by mast cells, and if its deletion does not significantly influence the expression of other mastcell products, then it is possible to draw conclusions about the role of that mast-cell product in vivo. For example, mice that lack mouse mast-cell protease-1 (mMCP-1) [26][27][28] , mMCP-4 29,30 , mMCP-6 [31][32][33] , or mouse mast cell-carboxypeptidase A (mMC-CPA) 34 , or that have a mutated mMC-CPA that essentially lacks enzymatic activity 11 , have been used to analyze whether the absence of these proteases (or their enzymatic activity) influences other aspects of the mast-cell phenotype, such as content of other stored mediators, as well as to define the functions of such mast-cell-associated proteases in vivo.…”

Innate BALB/c Enteric Epithelial Responses to Trichinella spiralis: Inducible Expression of a Novel Goblet Cell Lectin, Intelectin-2, and Its Natural Deletion in C57BL/10 Mice

“…Three-centimeter lengths of jejunum were removed starting 10 cm from the pylorus, fixed in 4% paraformaldehyde, and processed and sectioned as previously described (20). In a second experiment, samples of jejunum were obtained from T. spiralis-infected age-and sexmatched BALB/c mice (bred at Easter Bush Veterinary Centre, University of Edinburgh, Edinburgh, U.K.) on days 7, 14, and 28, and also from uninfected control mice.…”

“…To confirm the identity of the PCR products, gels were subjected to Southern blotting following standard protocols and hybridized using dioxygenin-labeled gene-specific probes, using methods previously described (20 …”

Expressão e caracterização das quimases recombinantes específicas de mastócitos de camundongos (mMCP4 e 5)

“…Com camundongos knockout para mMCP-1 foi possível demonstrar que a ausência desta protease afeta a cinética do recrutamento de MMCs após infecção por Nippostrongylus brasiliensis (WASTLING et al, 1998). Estudos posteriores mostraram que os camundongos com deficiência para esta protease eram mais susceptíveis a infecções por Trichinella spiralis (KNIGHT et al, 2000).…”