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A lympho-follicular microenvironment is required for pathological prion protein deposition in chronically inflamed tissues from scrapie-affected sheep.

Maestrale C, Di Guardo G, Cancedda MG, Marruchella G, Masia M, Sechi S, Macciocu S, Santucciu C, Petruzzi M, Ligios C - PLoS ONE (2013)

Bottom Line: We demonstrated that ectopic PrP(Sc) deposition occurs exclusively in the context of lymphofollicular inflammatory sites, inside newly formed and well-organized lymphoid follicles harboring follicular dendritic cells.A significantly more consistent expression of lymphotoxin α and β mRNA was detected in lymphofollicular inflammation compared to the other two types, with lymphotoxin α and β signaling new lymphoid follicles' formation and, likely, the occurrence of ectopic PrP(Sc) deposition inside them.Our findings suggest that, in sheep co-affected by scrapie and chronic inflammatory conditions, only newly formed lymphoid follicles provide a suitable micro-environment that supports the scrapie agent's replication in inflammatory sites, with an increased risk of prion shedding through body secretions/excretions.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Sanità Animale, Istituto Zooprofilattico Sperimentale della Sardegna, Sassari, Italy.

ABSTRACT
In sheep scrapie, pathological prion protein (PrP(Sc)) deposition occurs in the lymphoreticular and central nervous systems. We investigated PrP(Sc) distribution in scrapie-affected sheep showing simultaneous evidence of chronic lymphofollicular, lymphoproliferative/non-lymphofollicular, and/or granulomatous inflammations in their mammary gland, lung, and ileum. To do this, PrP(Sc) detection was carried out via immunohistochemistry and Western Blotting techniques, as well as through inflammatory cell immunophenotyping. Expression studies of gene coding for biological factors modulating the host's inflammatory response were also carried out. We demonstrated that ectopic PrP(Sc) deposition occurs exclusively in the context of lymphofollicular inflammatory sites, inside newly formed and well-organized lymphoid follicles harboring follicular dendritic cells. On the contrary, no PrP(Sc) deposition was detected in granulomas, even when they were closely located to newly formed lymphoid follicles. A significantly more consistent expression of lymphotoxin α and β mRNA was detected in lymphofollicular inflammation compared to the other two types, with lymphotoxin α and β signaling new lymphoid follicles' formation and, likely, the occurrence of ectopic PrP(Sc) deposition inside them. Our findings suggest that, in sheep co-affected by scrapie and chronic inflammatory conditions, only newly formed lymphoid follicles provide a suitable micro-environment that supports the scrapie agent's replication in inflammatory sites, with an increased risk of prion shedding through body secretions/excretions.

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PrPSc is detected only in inflamed sheep mammary glands containing newly formed lymphoid follicles.Inflammatory cell immunophenotyping in serial paraffin-embedded sections of mammary glands from sheep simultaneously affected by scrapie and lymphofollicular, lymphoproliferative/non-lymphofollicular, or granulomatous mastitis. A normal ovine palatine tonsil is also shown for comparison. CNA-42, CD3, and CD79 were used as markers for FDCs, T cells, and B cells (Panel A), while CD172a, CD68, and CD11c were used for activated macrophages and DCs (Panel B), respectively. In panel C, a representative set of negative controls are shown. These were obtained by omitting all the primary antibodies used on the tonsil sections (photos 1, 2, 3, 4, 6, and 7), as well as from granulomatous mastitis (photo 5). The omitted primary antibodies are indicated on each photo. It is noteworthy that the relative positioning of these cell populations was similar in newly formed lymphoid follicles and constitutive follicles normally hosted inside the palatine tonsil. CD172a+ macrophages were the most representative cell population in granulomatous mastitis, which also displayed a moderate presence of T and B cells and DCs. CD3+ T cells were the most abundant cellular component in the context of lymphoproliferative/non-lymphofollicular mastitis. PrPSc deposition occurred in co-localization with CD79+ B cells and the CNA42+ FDC network both in palatine tonsil and in newly formed lymphoid follicles. Immune reactions were visualized by 3-3′-diaminobenzidine (DAB) chromogen, with F99 primary MoAb being used for PrPSc detection. Mayer’s hematoxylin counterstain. Scale bar = 100 µm.
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pone-0062830-g004: PrPSc is detected only in inflamed sheep mammary glands containing newly formed lymphoid follicles.Inflammatory cell immunophenotyping in serial paraffin-embedded sections of mammary glands from sheep simultaneously affected by scrapie and lymphofollicular, lymphoproliferative/non-lymphofollicular, or granulomatous mastitis. A normal ovine palatine tonsil is also shown for comparison. CNA-42, CD3, and CD79 were used as markers for FDCs, T cells, and B cells (Panel A), while CD172a, CD68, and CD11c were used for activated macrophages and DCs (Panel B), respectively. In panel C, a representative set of negative controls are shown. These were obtained by omitting all the primary antibodies used on the tonsil sections (photos 1, 2, 3, 4, 6, and 7), as well as from granulomatous mastitis (photo 5). The omitted primary antibodies are indicated on each photo. It is noteworthy that the relative positioning of these cell populations was similar in newly formed lymphoid follicles and constitutive follicles normally hosted inside the palatine tonsil. CD172a+ macrophages were the most representative cell population in granulomatous mastitis, which also displayed a moderate presence of T and B cells and DCs. CD3+ T cells were the most abundant cellular component in the context of lymphoproliferative/non-lymphofollicular mastitis. PrPSc deposition occurred in co-localization with CD79+ B cells and the CNA42+ FDC network both in palatine tonsil and in newly formed lymphoid follicles. Immune reactions were visualized by 3-3′-diaminobenzidine (DAB) chromogen, with F99 primary MoAb being used for PrPSc detection. Mayer’s hematoxylin counterstain. Scale bar = 100 µm.

Mentions: The inflammatory cell immunophenotyping that was carried out on the mammary glands from all 14 sheep affected by chronic mastitis yielded the results outlined here below. Newly formed lymphofollicular structures were characterized by the presence of well-defined areas populated by CD79+ B lymphocytes forming GCs, which were surrounded by CD3+ T lymphocytes, along with CD11c+ DCs and rare CD68+ cells, as observed in perifollicular areas of the palatine tonsil (Figure 4A and 4B). Additionally, in serial mammary gland sections, GCs exhibited a CNA42+ FDC network. Therefore, the micro-architecture and organization of newly formed lymphoid follicles appeared to be strikingly similar to those of secondary lymphoid organs, as in palatine tonsils (Figure 4A and 4B). The lymphoproliferative/non-lymphofollicular infiltrate appeared to be mostly, if not totally, represented by CD3+ T lymphocytes, with scattered CD11c+ DCs and CD68+ cells (Figure 4A and 4B).


A lympho-follicular microenvironment is required for pathological prion protein deposition in chronically inflamed tissues from scrapie-affected sheep.

Maestrale C, Di Guardo G, Cancedda MG, Marruchella G, Masia M, Sechi S, Macciocu S, Santucciu C, Petruzzi M, Ligios C - PLoS ONE (2013)

PrPSc is detected only in inflamed sheep mammary glands containing newly formed lymphoid follicles.Inflammatory cell immunophenotyping in serial paraffin-embedded sections of mammary glands from sheep simultaneously affected by scrapie and lymphofollicular, lymphoproliferative/non-lymphofollicular, or granulomatous mastitis. A normal ovine palatine tonsil is also shown for comparison. CNA-42, CD3, and CD79 were used as markers for FDCs, T cells, and B cells (Panel A), while CD172a, CD68, and CD11c were used for activated macrophages and DCs (Panel B), respectively. In panel C, a representative set of negative controls are shown. These were obtained by omitting all the primary antibodies used on the tonsil sections (photos 1, 2, 3, 4, 6, and 7), as well as from granulomatous mastitis (photo 5). The omitted primary antibodies are indicated on each photo. It is noteworthy that the relative positioning of these cell populations was similar in newly formed lymphoid follicles and constitutive follicles normally hosted inside the palatine tonsil. CD172a+ macrophages were the most representative cell population in granulomatous mastitis, which also displayed a moderate presence of T and B cells and DCs. CD3+ T cells were the most abundant cellular component in the context of lymphoproliferative/non-lymphofollicular mastitis. PrPSc deposition occurred in co-localization with CD79+ B cells and the CNA42+ FDC network both in palatine tonsil and in newly formed lymphoid follicles. Immune reactions were visualized by 3-3′-diaminobenzidine (DAB) chromogen, with F99 primary MoAb being used for PrPSc detection. Mayer’s hematoxylin counterstain. Scale bar = 100 µm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3643908&req=5

pone-0062830-g004: PrPSc is detected only in inflamed sheep mammary glands containing newly formed lymphoid follicles.Inflammatory cell immunophenotyping in serial paraffin-embedded sections of mammary glands from sheep simultaneously affected by scrapie and lymphofollicular, lymphoproliferative/non-lymphofollicular, or granulomatous mastitis. A normal ovine palatine tonsil is also shown for comparison. CNA-42, CD3, and CD79 were used as markers for FDCs, T cells, and B cells (Panel A), while CD172a, CD68, and CD11c were used for activated macrophages and DCs (Panel B), respectively. In panel C, a representative set of negative controls are shown. These were obtained by omitting all the primary antibodies used on the tonsil sections (photos 1, 2, 3, 4, 6, and 7), as well as from granulomatous mastitis (photo 5). The omitted primary antibodies are indicated on each photo. It is noteworthy that the relative positioning of these cell populations was similar in newly formed lymphoid follicles and constitutive follicles normally hosted inside the palatine tonsil. CD172a+ macrophages were the most representative cell population in granulomatous mastitis, which also displayed a moderate presence of T and B cells and DCs. CD3+ T cells were the most abundant cellular component in the context of lymphoproliferative/non-lymphofollicular mastitis. PrPSc deposition occurred in co-localization with CD79+ B cells and the CNA42+ FDC network both in palatine tonsil and in newly formed lymphoid follicles. Immune reactions were visualized by 3-3′-diaminobenzidine (DAB) chromogen, with F99 primary MoAb being used for PrPSc detection. Mayer’s hematoxylin counterstain. Scale bar = 100 µm.
Mentions: The inflammatory cell immunophenotyping that was carried out on the mammary glands from all 14 sheep affected by chronic mastitis yielded the results outlined here below. Newly formed lymphofollicular structures were characterized by the presence of well-defined areas populated by CD79+ B lymphocytes forming GCs, which were surrounded by CD3+ T lymphocytes, along with CD11c+ DCs and rare CD68+ cells, as observed in perifollicular areas of the palatine tonsil (Figure 4A and 4B). Additionally, in serial mammary gland sections, GCs exhibited a CNA42+ FDC network. Therefore, the micro-architecture and organization of newly formed lymphoid follicles appeared to be strikingly similar to those of secondary lymphoid organs, as in palatine tonsils (Figure 4A and 4B). The lymphoproliferative/non-lymphofollicular infiltrate appeared to be mostly, if not totally, represented by CD3+ T lymphocytes, with scattered CD11c+ DCs and CD68+ cells (Figure 4A and 4B).

Bottom Line: We demonstrated that ectopic PrP(Sc) deposition occurs exclusively in the context of lymphofollicular inflammatory sites, inside newly formed and well-organized lymphoid follicles harboring follicular dendritic cells.A significantly more consistent expression of lymphotoxin α and β mRNA was detected in lymphofollicular inflammation compared to the other two types, with lymphotoxin α and β signaling new lymphoid follicles' formation and, likely, the occurrence of ectopic PrP(Sc) deposition inside them.Our findings suggest that, in sheep co-affected by scrapie and chronic inflammatory conditions, only newly formed lymphoid follicles provide a suitable micro-environment that supports the scrapie agent's replication in inflammatory sites, with an increased risk of prion shedding through body secretions/excretions.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Sanità Animale, Istituto Zooprofilattico Sperimentale della Sardegna, Sassari, Italy.

ABSTRACT
In sheep scrapie, pathological prion protein (PrP(Sc)) deposition occurs in the lymphoreticular and central nervous systems. We investigated PrP(Sc) distribution in scrapie-affected sheep showing simultaneous evidence of chronic lymphofollicular, lymphoproliferative/non-lymphofollicular, and/or granulomatous inflammations in their mammary gland, lung, and ileum. To do this, PrP(Sc) detection was carried out via immunohistochemistry and Western Blotting techniques, as well as through inflammatory cell immunophenotyping. Expression studies of gene coding for biological factors modulating the host's inflammatory response were also carried out. We demonstrated that ectopic PrP(Sc) deposition occurs exclusively in the context of lymphofollicular inflammatory sites, inside newly formed and well-organized lymphoid follicles harboring follicular dendritic cells. On the contrary, no PrP(Sc) deposition was detected in granulomas, even when they were closely located to newly formed lymphoid follicles. A significantly more consistent expression of lymphotoxin α and β mRNA was detected in lymphofollicular inflammation compared to the other two types, with lymphotoxin α and β signaling new lymphoid follicles' formation and, likely, the occurrence of ectopic PrP(Sc) deposition inside them. Our findings suggest that, in sheep co-affected by scrapie and chronic inflammatory conditions, only newly formed lymphoid follicles provide a suitable micro-environment that supports the scrapie agent's replication in inflammatory sites, with an increased risk of prion shedding through body secretions/excretions.

Show MeSH
Related in: MedlinePlus