Release of the mucosal mast cell granule chymase, rat mast cell protease-II, during anaphylaxis is associated with the rapid development of paracellular permeability to macromolecules in rat jejunum.

Abstract

SummaryThe soluble granule chymase, rat mast cell protease-II (RMCP-1I), is abundantly expressed in intestinal mucosal mast cells (MMC) but its function is not known. One hypothesis is that RMCP-Il degrades the epithelial basement membrane and promotes the loss of enterocytes typically associated with type I hypersensitivity reactions in the rat . To test this hypothesis more directly, ex vivo perfusion of the cranial mesenteric artery and jejunal lumen was used to monitor the anaphylactic release of RMCP-11 and its effects on mucosal permeability and epithelial integrity . Within 2 min of intravascular challenge with soluble adult Nippostrongylus brasiliensis worm antigen there was a 1,000-fold (P <0.02) increase in the concentration of RMCP-11 in the vascular perfusate from the jejunum of Nippostrongylus-sensitized rats but not the controls. Similarly, translocation of RMCP-1I into the gut lumen increased 10-fold (P <0 .02) after 2 min only in worm antigen-challenged immune rats. Using an identical protocol, but incorporating Evans blue-labeled human serum albumin (EB-HSA) in the vascular perfusate, the timing of the release ofRMCP-II into the two compartments was very similar to the first experiment and furthermore the translocation ofEB-HSA increased 18-fold (P <0.05) after 4 min in sensitized rats challenged with worm antigen . To examine the effects of RMCP-11 more directly 1 mg ofthe highly purified chymase was introduced into the cranial mesenteric artery in ex vivo perfused normal rats. A significant (P <0.05) 70-fold increase in concentration of RMCP-II in jejunal perfusate occurred after 6 min. In a repeat dose-response experiment, infusion of 0.375, 0.75, or 1 .5 mg of RMCP-11, together with EB-HSA, established that the cumulative amounts of RMCP-II and EB-HSA translocated from the vasculature to the gut lumen in each perfusion (during the 10-min period of RMCP-II infusion) were significantly correlated. Analysis of intestinal perfusates by SIDS-PAGE and by Western blotting using monoclonal anti-RMCP-11 antibody confirmed that there was a concomitant translocation of both the protease and EB-HSA into the gut lumen . Histological evaluation of the mucosa failed to reveal any significant morphological change in any of the experiments . The rapid development ofmacromolecular leak, its association with the translocation of RMCP-11, and the absence of gross epithelial lesions, suggest for the first time that a mast cell granule chymase increases epithelial permeability via a paracellular route and implies that the substrate may be a protein, or proteins, in the epithelial junctional complex .Hypersensitivity reactions in the gastrointestinal tract are associated with a secretory response ofthe epithelium and, frequently, increased permeability to macromol-'Abbreviations used in this paper: cx,Pl, a l -protease inhibitor; EB-HSA, human serum albumin labeled with Evans blue dye ; MMC, mucosal mast cells ; RMCP-11, rat mast cell protease-11 ; we, worm equivalents. ecules (1, 2). Mast cell activation has been...

Antibiotic Administration Early in Life Impairs Specific Humoral Responses to an Oral Antigen and Increases Intestinal Mast Cell Numbers and Mediator Concentrations

“…In contrast, amoxicillin-treated animals showed increased RMCPII levels and higher number of mast cells in the intestinal tissue in comparison to those in the saline-treated groups, independently of the intragastric challenge. No significant morphological changes (neither major inflammatory infiltrates nor epithelial lesions) accompanied the increase in RMCPII levels, which is consistent with published data obtained with an anaphylactic animal model (37). The mild increase in the number of mast cells present in the intestinal mucosa, together with the higher levels of expression of mast cell protease genes previously observed in antibiotic-treated animals compared to those observed in control animals (16,35), could explain this difference and suggests a local more than a systemic immune response.…”

Mucosal Defense against Gastrointestinal Nematodes: Responses of Mucosal Mast Cells and Mouse Mast Cell Protease 1 during PrimaryStrongyloides venezuelensisInfection in FcRγ-Knockout Mice

“…Systemic release of mast cell proteinases during primary and challenge nematode infections has been described in rodents and sheep and cited as evidence that MMC are active during nematode expulsion (4,5,13,15,22,23,29,30). Our data on MMC and MMCP-1 release support the proposition that MMCP-1 is a correlate for mast cell activity.…”

“…In fact, there is evidence that repeated treatment of normal mice twice daily for 5 days with 10 4 U of IL-3 resulted in mastocytosis and spontaneous release of MMCP-1 at concentrations up to 200 times higher than the concentration in control animals given only medium (2), and that murine IL-3 could induce the spontaneous release of histamine by mouse peritoneal mast cells (28). However, MMCP-1 may still have an indirect role in S. venezuelensis expulsion since ex vivo and in vivo studies showed that MMC proteinases permeabilize enterocyte tight junctions and promote the escape of MMC and the translocation of plasmaderived molecules into the gut lumen (9,23).…”

A Role of Mast Cell Glycosaminoglycans for the Immunological Expulsion of Intestinal Nematode, Strongyloides venezuelensis

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