Lymphocyte Depletion in Ileal Peyer’s Patch Follicles in Lambs Infected withEimeria ovinoidalis

Abstract

A total of 14 lambs were experimentally infected with Eimeria ovinoidalis in two separate experiments in two consecutive years. Nine lambs served as uninoculated controls. Material was collected from the ileum 2 weeks after infection in eight lambs and 3 weeks after infection in six lambs. Lambs examined 2 weeks after infection had normal follicles. After three weeks, the follicle-associated epithelium covering the lymphoid follicles of the ileal Peyer's patches showed fusions with adjacent absorptive epithelium, focal hyperplasia, and occasionally necrosis. Macrogametes, microgamonts, and oocysts were often found in the follicle-associated epithelium and the dome region. Various degrees of lymphocyte depletion were present in the ileal lymphoid follicles in all six infected lambs 3 weeks after infection, and four lambs had decreased follicle size. Reduced staining for leukocyte common antigen (CD45), B-cell markers, and the proliferation marker Ki-67 was present in these lambs. Application of the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling method for apoptotic cells revealed decreased staining in the ileal lymphoid follicles 3 weeks after infection. A marker of follicular dendritic cells, 5-nucleotidase, showed increased reactivity, probably due to condensation of reticular cells following loss of follicle lymphocytes. Reduced staining for carbonic anhydrase in the follicle-associated epithelium and the domes was present in all six lambs examined 3 weeks after infection, indicating decreased production of carbonic anhydrase-reactive 50-nm particles and a decreased lymphoproliferative stimulus. In conclusion, the present study shows that severe E. ovinoidalis infection in lambs causes lesions of the follicle-associated epithelium and may result in lymphocyte depletion and atrophy of the ileal Peyer's patch follicles.Coccidiosis in lambs is an intestinal infection characterized clinically by diarrhea and dehydration. A major cause of ovine coccidiosis is Eimeria ovinoidalis, but other species, such as Eimeria crandallis, may also be associated with this disease. Morphological changes in Eimeria sp. infections in lambs are characterized by inflammation, villus atrophy, epithelial hyperplasia, glandular loss, and mucosal collapse (8, 9, 11). Cellular immune responses play an important role in immunity against Eimeria spp., whereas humoral immunity probably represents a less important factor (3,46,51).Immunity is dependent on effective antigen detection, and the Peyer's patches are important for the generation of an immune response. Ruminants have two distinct types of Peyer's patches, the jejunal Peyer's patches and the ileal Peyer's patches (IPP), which differ in their development, cellular composition, and function (13,28,45). IPP have been attributed to have a role as a central lymphoid organ in the development of B cells, whereas a function in mucosal immune responses has been questioned (12, 36). The Peyer's patches of ruminants are outlined by a modified, follicle-associated ep...

Identification of Novel Genes in Intestinal Tissue That Are Regulated after Infection with an Intestinal Nematode Parasite

“…Equally, some of these down-regulated genes may simply be markers of persisting infection. For instance, the expression of carbonic anhydrase (Car2) is reduced in gut tissue of AKR mice at both day 19 and day 60 postinfection and has also been shown to be reduced postinfection in other models of intestinal parasite infections (1). Equally, the decrease in transcripts for the water channel aquaporin 8 may be a response by the host to decrease fluid transport across the epithelium during chronic infection.…”

Kokzidiose der kleinen Hauswiederkäuer

“…Histologisch sind unter anderem Epithelverlust, Nekrosen, Atrophie der Mikrovilli bei gleichzeitiger Hyperplasie (Verlängerung) der Krypten, Einwanderung von Entzündungszellen wie eosinophile und neutrophile Granulozyten, Lymphozyten und Makrophagen und, abhängig vom Erreger, petechiale Blutungen zu beobachten (21,31,33,50). Eine Depletion der Lymphozyten der ilealen Peyer'schen Platten wird häufig beschrieben und E. ovinoidalis ist möglicherweise in der Lage, eine Atrophie der Peyer'schen Platten zu verursachen (1,21,23). Bei schweren Infektionen durch E. crandallis oder E. ovinoidalis beim Schaf kann die komplette Architektur der Mukosa zerstört werden (21,50).…”

Differentiation of the follicle-associated epithelium in ileal Peyer?s patch and production of 50-nm particles are maintained in B-cell-depleted fetal sheep

“…The intimate association of particle formation with macromolecular transcytosis and carbonic anhydrase reactivity in the apical plasma membrane has been used as a basis for the suggestion that the enveloping membrane of particles is derived from the luminal plasma membrane of cells of the FAE (Landsverk et al 1990a). Although indirect evidence, such as decreased carbonic anhydrase reactivity in follicles following abrogated FAE function during infection (Aleksandersen et al 2002;Landsverk et al 1990b), suggests an epithelial origin of the 50-nm membrane-bounded particles, existing data cannot formally exclude a B-cell origin for these particles. Indeed, B-cells have been reported to produce exosomes, which are extracellular membrane-bounded vesicles that are about the size of the particles associated with the FAE (Escola et al 1998;Raposo et al 1996).…”