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Autoimmune pancreatitis results from loss of TGFbeta signalling in S100A4-positive dendritic cells.

Boomershine CS, Chamberlain A, Kendall P, Afshar-Sharif AR, Huang H, Washington MK, Lawson WE, Thomas JW, Blackwell TS, Bhowmick NA - Gut (2009)

Bottom Line: DCs were confirmed to express S100A4, a previously reported protein expressed by fibroblasts.Tgfbr2(fspKO) DCs undergo elevated maturation in response to antigen and increased activation of naïve CD4-positive T cells.The loss of immune tolerance in myeloid S100A4(+) DCs can mediate mAIP and may explain some aspects of AIP disease pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Vanderbilt-Ingram Cancer, Vanderbilt University, Nashville 37232, Tennessee, USA.

ABSTRACT

Background and aims: Autoimmune pancreatitis (AIP) is a poorly understood human disease affecting the exocrine pancreas. The goal of the present study was to elucidate the pathogenic mechanisms underlying pancreatic autoimmunity in a murine disease model.

Methods: A transgenic mouse with an S100A4/fibroblast-specific protein 1 (FSP1) Cre-mediated conditional knockout of the transforming growth factor beta (TGFbeta) type II receptor, termed Tgfbr2(fspKO), was used to determine the direct role of TGFbeta in S100A4(+) cells. Immunohistochemical studies suggested that Tgfbr2(fspKO) mice develop mouse AIP (mAIP) characterised by interlobular ductal inflammatory infiltrates and pancreatic autoantibody production. Fluorescence-activated cell sorting (FACS)-isolated dendritic cells (DCs) from diseased pancreata were verified to have S100A4-Cre-mediated DNA recombination.

Results: The Tgfbr2(fspKO) mice spontaneously developed mAIP by 6 weeks of age. DCs were confirmed to express S100A4, a previously reported protein expressed by fibroblasts. Adoptive transfer of bone marrow-derived DCs from Tgfbr2(fspKO) mice into 2-week-old syngenic wild-type C57BL/6 mice resulted in reproduction of pancreatitis within 6 weeks. Similar adoptive transfer of wild-type DCs had no effect on pancreas pathology of the host mice. The inability to induce pancreatitis by adoptive transfer of Tgfbr2(fspKO) DCs in adult mice suggested a developmental event in mAIP pathogenesis. Tgfbr2(fspKO) DCs undergo elevated maturation in response to antigen and increased activation of naïve CD4-positive T cells.

Conclusion: The development of mAIP in the Tgfbr2(fspKO) mouse model illustrates the role of TGFbeta in maintaining myeloid DC immune tolerance. The loss of immune tolerance in myeloid S100A4(+) DCs can mediate mAIP and may explain some aspects of AIP disease pathogenesis.

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Related in: MedlinePlus

Tgfbr2fspKO mice produce pancreatic autoantibodies. Dog pancreas was incubated with (A) phosphate-buffered saline or serum from (B) Tgfbr2floxE2/floxE2 (n = 4) and (C) Tgfbr2fspKO mice (n = 8). The immunoreactivity of the tissues was subsequently visualised with antimouse immunoglobulin G Fab fragment (in red) and Hoechst nuclear counterstain (in blue).
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gut-58-09-1267-f03: Tgfbr2fspKO mice produce pancreatic autoantibodies. Dog pancreas was incubated with (A) phosphate-buffered saline or serum from (B) Tgfbr2floxE2/floxE2 (n = 4) and (C) Tgfbr2fspKO mice (n = 8). The immunoreactivity of the tissues was subsequently visualised with antimouse immunoglobulin G Fab fragment (in red) and Hoechst nuclear counterstain (in blue).

Mentions: Histological sections from pancreata of Tgfbr2fspKO mice had periductal, interlobular inflammatory infiltrates that were not present in littermate control Tgfbr2floxE2/floxE2 mice (fig 1). There was evidence of acinar metaplasia and expansion of fibroblastic cells periductally by 6 weeks of age without evidence for pancreatic islet inflammatory infiltration in these mice. The Tgfbr2fspKO pancreata had no gross pathological differences from the Tgfbr2floxE2/floxE2 age-matched littermates. Masson’s trichrome staining suggested no significant fibrosis, as indicated by the lack of collagen deposition in either the Tgfbr2fspKO or Tgfbr2floxE2/floxE2 pancreata. Immunolocalisation of phosphorylated Smad2, indicating active TGFβ signalling, was seen in pancreatic cells from both mice but was absent in inflammatory areas of acinar metaplasia and stromal expansion in Tgfbr2fspKO pancreata. As in human AIP, the inflammatory infiltrates were composed predominantly of macrophages and T cells with sparing of the endocrine pancreas (fig 2A and B, respectively). Further evidence for a non-fibrotic pancreatitis phenotype in Tgfbr2fspKO mice was demonstrated by the lack of expansion of nestin-positive stellate cells (fig 2C). As in human AIP, endocrine function did not seem to be overtly impaired in Tgfbr2fspKO mice, as determined by insulin (fig 2D) and somatostatin expression in the islets and serum (data not shown). Autoantibody production against pancreatic proteins is a hallmark of human AIP.2 To determine if Tgfbr2fspKO mice produced pancreatic autoantibodies, canine pancreatic tissue was incubated with serum from either Tgfbr2fspKO mice or Tgfbr2floxE2/floxE2 littermate controls. Tgfbr2fspKO serum was found to contain mouse antibodies against pancreatic acinar tissue that were absent in serum from control, Tgfbr2floxE2/floxE2 animals (fig 3).


Autoimmune pancreatitis results from loss of TGFbeta signalling in S100A4-positive dendritic cells.

Boomershine CS, Chamberlain A, Kendall P, Afshar-Sharif AR, Huang H, Washington MK, Lawson WE, Thomas JW, Blackwell TS, Bhowmick NA - Gut (2009)

Tgfbr2fspKO mice produce pancreatic autoantibodies. Dog pancreas was incubated with (A) phosphate-buffered saline or serum from (B) Tgfbr2floxE2/floxE2 (n = 4) and (C) Tgfbr2fspKO mice (n = 8). The immunoreactivity of the tissues was subsequently visualised with antimouse immunoglobulin G Fab fragment (in red) and Hoechst nuclear counterstain (in blue).
© Copyright Policy - openaccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2719085&req=5

gut-58-09-1267-f03: Tgfbr2fspKO mice produce pancreatic autoantibodies. Dog pancreas was incubated with (A) phosphate-buffered saline or serum from (B) Tgfbr2floxE2/floxE2 (n = 4) and (C) Tgfbr2fspKO mice (n = 8). The immunoreactivity of the tissues was subsequently visualised with antimouse immunoglobulin G Fab fragment (in red) and Hoechst nuclear counterstain (in blue).
Mentions: Histological sections from pancreata of Tgfbr2fspKO mice had periductal, interlobular inflammatory infiltrates that were not present in littermate control Tgfbr2floxE2/floxE2 mice (fig 1). There was evidence of acinar metaplasia and expansion of fibroblastic cells periductally by 6 weeks of age without evidence for pancreatic islet inflammatory infiltration in these mice. The Tgfbr2fspKO pancreata had no gross pathological differences from the Tgfbr2floxE2/floxE2 age-matched littermates. Masson’s trichrome staining suggested no significant fibrosis, as indicated by the lack of collagen deposition in either the Tgfbr2fspKO or Tgfbr2floxE2/floxE2 pancreata. Immunolocalisation of phosphorylated Smad2, indicating active TGFβ signalling, was seen in pancreatic cells from both mice but was absent in inflammatory areas of acinar metaplasia and stromal expansion in Tgfbr2fspKO pancreata. As in human AIP, the inflammatory infiltrates were composed predominantly of macrophages and T cells with sparing of the endocrine pancreas (fig 2A and B, respectively). Further evidence for a non-fibrotic pancreatitis phenotype in Tgfbr2fspKO mice was demonstrated by the lack of expansion of nestin-positive stellate cells (fig 2C). As in human AIP, endocrine function did not seem to be overtly impaired in Tgfbr2fspKO mice, as determined by insulin (fig 2D) and somatostatin expression in the islets and serum (data not shown). Autoantibody production against pancreatic proteins is a hallmark of human AIP.2 To determine if Tgfbr2fspKO mice produced pancreatic autoantibodies, canine pancreatic tissue was incubated with serum from either Tgfbr2fspKO mice or Tgfbr2floxE2/floxE2 littermate controls. Tgfbr2fspKO serum was found to contain mouse antibodies against pancreatic acinar tissue that were absent in serum from control, Tgfbr2floxE2/floxE2 animals (fig 3).

Bottom Line: DCs were confirmed to express S100A4, a previously reported protein expressed by fibroblasts.Tgfbr2(fspKO) DCs undergo elevated maturation in response to antigen and increased activation of naïve CD4-positive T cells.The loss of immune tolerance in myeloid S100A4(+) DCs can mediate mAIP and may explain some aspects of AIP disease pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Vanderbilt-Ingram Cancer, Vanderbilt University, Nashville 37232, Tennessee, USA.

ABSTRACT

Background and aims: Autoimmune pancreatitis (AIP) is a poorly understood human disease affecting the exocrine pancreas. The goal of the present study was to elucidate the pathogenic mechanisms underlying pancreatic autoimmunity in a murine disease model.

Methods: A transgenic mouse with an S100A4/fibroblast-specific protein 1 (FSP1) Cre-mediated conditional knockout of the transforming growth factor beta (TGFbeta) type II receptor, termed Tgfbr2(fspKO), was used to determine the direct role of TGFbeta in S100A4(+) cells. Immunohistochemical studies suggested that Tgfbr2(fspKO) mice develop mouse AIP (mAIP) characterised by interlobular ductal inflammatory infiltrates and pancreatic autoantibody production. Fluorescence-activated cell sorting (FACS)-isolated dendritic cells (DCs) from diseased pancreata were verified to have S100A4-Cre-mediated DNA recombination.

Results: The Tgfbr2(fspKO) mice spontaneously developed mAIP by 6 weeks of age. DCs were confirmed to express S100A4, a previously reported protein expressed by fibroblasts. Adoptive transfer of bone marrow-derived DCs from Tgfbr2(fspKO) mice into 2-week-old syngenic wild-type C57BL/6 mice resulted in reproduction of pancreatitis within 6 weeks. Similar adoptive transfer of wild-type DCs had no effect on pancreas pathology of the host mice. The inability to induce pancreatitis by adoptive transfer of Tgfbr2(fspKO) DCs in adult mice suggested a developmental event in mAIP pathogenesis. Tgfbr2(fspKO) DCs undergo elevated maturation in response to antigen and increased activation of naïve CD4-positive T cells.

Conclusion: The development of mAIP in the Tgfbr2(fspKO) mouse model illustrates the role of TGFbeta in maintaining myeloid DC immune tolerance. The loss of immune tolerance in myeloid S100A4(+) DCs can mediate mAIP and may explain some aspects of AIP disease pathogenesis.

Show MeSH
Related in: MedlinePlus