The response of mast cells and serglycin-dependent proteases to parasitic infection

The proteoglycan (PG), serglycin (SG), is expressed in several hematopoietic cells and studies of the SG knockout mice (SG-/-) revealed prominent effects on the storage of certain mouse mast cell proteases (mMCPs) such as mMCP-4, -5 and -6.In this thesis, the role of SGPG during parasitic infection was addressed. Both SG+/+ and SG-/- animals infected with Toxoplasma gondii had significantly elevated levels of hyaluronan and chondroitin sulfate A PG in the peritoneum. In contrast, whereas heparin/heparan sulfate was confined to the peritoneal cells in SG+/+ animals, it was almost undetectable in SG-/- animals. Surprisingly, both SG+/+ and SG-/- animals were shown to secrete active MC proteases to almost the same levels in the peritoneal cavity, despite defective storage of proteases in SG-/- MCs. Furthermore, SG-/- animals showed a delayed neutrophil recruitment and decreased levels of proinflammatory cytokines such as IL-6, IL-12, TNF-a and MCP-1. In vitro stimulation of peritoneal derived MCs (PCMCs) with soluble Toxoplasma antigen induced significantly lower secretion of IL-6, IL-12 and TNF-a in SG-/- PCMCs than in SG+/+ PCMCs. In addition, when studying aging SG-/- animals, the deficiency manifested as enlargements of lymphoid tissues, particularly spleens, Peyer’s patches and bronchus associated lymphoid tissue, and was not shown to be associated with infection. Analysis of this phenomenon revealed an expansion of naïve lymphocytes through an increase in the CD4+ and CD45RC+ leukocyte population. Moreover, peritoneal macrophages were markedly increased in number in aging SG-/- animals. In response to Dictyocaulus viviparus infection in calves, tryptase positive MCs in the bovine lung and BALF were shown to correlate with disease progression. The activity and expression levels of tryptase were increased in the lungs of infected calves compared to non-infected control animals. In conclusion, MCs are actively involved in the host response to Toxoplasma gondii infection in mice and Dictyocaulus viviparus infection in calves

Serglycin proteoglycans limit enteropathy in Trichinella spiralis-infected mice

Background: Serglycin proteoglycans are essential for maturation of secretory granules and for the correct granular storage of cationic proteases in hematopoietic cells, e.g. mast cells. However, little is known about the in vivo functions of serglycin proteoglycans during infection. Here we investigated the potential role of serglycin proteoglycans in host defense after infection with the nematode Trichinella spiralis. Results: Twelve days post infection lack of serglycin proteoglycans caused significantly increased enteropathy. The serglycin-deficient mice showed significantly increased intestinal worm burden, reduced recruitment of mast cells to the intestinal crypts, decreased levels of the mast cell proteases MCPT5 and MCPT6 in intestinal tissue, decreased serum levels of TNF-alpha, IL-1 beta, IL-10 and IL-13, increased levels of IL-4 and total IgE in serum, and increased intestinal levels of the neutrophil markers myeloperoxidase and elastase, as compared to wild type mice. At five weeks post infection, increased larvae burden and inflammation were seen in the muscle tissue of the serglycin-deficient mice. Conclusions: Our results demonstrate that the serglycin-deficient mice were more susceptible to T. spiralis infection and displayed an unbalanced immune response compared to wild type mice. These findings point to an essential regulatory role of serglycin proteoglycans in immunity

Additional file 1: of Serglycin proteoglycans limit enteropathy in Trichinella spiralis-infected mice

Supplementary material & methods and results. (DOCX 21 kb

Mast cell chymase degrades the alarmins heat shock protein 70, biglycan, HMGB1, and interleukin-33 (IL-33) and limits danger-induced inflammation

During infection and tissue damage, virulence factors and alarmins are pro-inflammatory and induce activation of various immune cells including macrophages and mast cells (MCs). Activated MCs instantly release preformed inflammatory mediators, including several proteases. The chymase mouse mast cell protease (MCPT)-4 is thought to be pro-inflammatory, whereas human chymase also degrades pro-inflammatory cytokines, suggesting that chymase instead limits inflammation. Here we explored the contribution of MCPT4 and human chymase to the control of danger-induced inflammation. We found that protein extracts from wild type (WT), carboxypeptidase A3-, and MCPT6-deficient mice and MCs and recombinant human chymase efficiently degrade the Trichinella spiralis virulence factor heat shock protein 70 (Hsp70) as well as endogenous Hsp70. MC-(W(sash))-, serglycin-, NDST2-, and MCPT4-deficient extracts lacked this capacity, indicating that chymase is responsible for the degradation. Chymase, but not MC tryptase, also degraded other alarmins, i.e. biglycan, HMGB1, and IL-33, a degradation that was efficiently blocked by the chymase inhibitor chymostatin. IL-7, IL-22, GM-CSF, and CCL2 were resistant to chymase degradation. MCPT4-deficient conditions ex vivo and in vivo showed no reduction in added Hsp70 and only minor reduction of IL-33. Peritoneal challenge with Hsp70 resulted in increased neutrophil recruitment and TNF-α levels in the MCPT4-deficient mice, whereas IL-6 and CCL2 levels were similar to the levels found in WT mice. The rapid and MC chymase-specific degradation of virulence factors and alarmins may depend on the presence of accessible extended recognition cleavage sites in target substrates and suggests a protective and regulatory role of MC chymase during danger-induced inflammation.status: publishe

Additional file 2: Figure S1. of Serglycin proteoglycans limit enteropathy in Trichinella spiralis-infected mice

T. spiralis infection in serglycin-deficient mice. Paraffin embedded intestinal tissues from control and infected WT and SG−/− mice (12 dpi) were sectioned and stained with H&E and the histopathological changes were observed. In (a) goblet cell hyperplasia was evaluated. Serum was collected from infected WT (N = 15) and serglycin-deficient (N = 15) mice and in (b) T.spiralis specific IgG levels was measured. Not significant, ns P >0.05 (TIF 241 kb