SummaryDefensins are antimicrobial peptides of the innate immune defence. The aim of the present study was to examine if b-defensin is expressed in the equine endometrium. Endometrial tissue samples were available from 29 mares. Performed were a histological examination (n=28), and immunohistochemistry (n =28). Mares aged 3 -20 years. Endometrosis was diagnosed in 20 mares; in the biopsy of 1 mare, endometrial glands could not be evaluated. Endometritis was observed in 12 and angiosclerosis in 21 mares. No endometrial alterations were found in 3 mares. Expression of equine b-defensin-1 mRNA was detected in all 29 mares and confirmed by sequencing in 11 cases. Immunostaining for b-defensin was detected in all 28 mares investigated; however, in 1 mare the surface and in another mare the glandular epithelium could not be evaluated. Immunopositive cell populations were the luminal epithelium (n=27), the glandular epithelium (n=20), stromal cells (n=6) and the vascular tunica media (n=14). The majority of immunopositive cells were located within the luminal epithelium and the duct of the endometrial glands. The immunostainig of the epithelium was predominantly cytoplasmic and less frequently nuclear. Stromal cells showed a nuclear staining. The smooth muscle cells of the vascular tunica media displayed a cytoplasmic labelling in 13 mares and a nuclear staining in 1 mare. This study demonstrates the expression of b-defensins in the healthy and diseased equine endometrium and indicates that b-defensin contributes to the endometrial immune defence in the mare.

Summary: Equine endometrial diseases are a frequent cause of subfertility causing financial loss. Degenerative and inflammatory diseases are often associated with alterations of the innate immunity and beta-defensin has been identified within the equine endometrium. The aim of this study was to further characterize the expression of beta-defensin protein within in the equine endometrium by immunohistochemistry. For in situ investigations, endometrial samples were collected from 26 mares once at different stages of the oestrus cycle and from 3 mares repeatedly during the same oestrus cycle (days 0, 5, 10, 13, 16, 19 and 21; day 0 is defined as ovulation day). In vitro examinations were performed on cultured epithelial cells obtained from endometrial specimens of 15 mares. The following results were obtained: Endometrial tissue sections of the 26 mares were either without pathological alterations (n = 3) or showed varying degrees of endometritis, endometrosis and/or angiosclerosis. Beta-defensin protein was mainly expressed within the cytoplasm of epithelial cells lining the luminal surface (100 %, 26 mares) and glandular ducts (69 %, 18 mares) and rarely within the nucleus of these cell populations (8 % and 19 %, respectively). The vast majority of cells showed either a cytoplasmic or a nuclear immunostaining. A simultaneous cytoplasmic and nuclear immunoreaction within the same cell was seldom observed (3 mares, up to 1% of the analyzed cells). Mid and basal glands without endometrosis were rarely immunopositive (nuclear immunostaining: 5 mares; cytoplasmic labelling: 1 mare). In contrast, endometrotic glands often contained small to moderate numbers of epithelial cells with a cytoplasmic immunosignal (15 of 19 cases; 79 %). In regard to the repeatedly collected biopsies of three mares, the percentage of immunopositive cells and the calculated immunoreactive scores were highly variable over the course of the oestrus cycle and between individual mares. In regard to cultured endometrial epithelial cells (n =15 mares), a positive beta-defensin immunosignal was observed in almost all cells (97 % of 521 analyzed cells) and was mainly located solely within the cytoplasm (76% of the analyzed cells), less frequently within the cytoplasm and nucleus (17 %) and rarely only within the nucleus (4 %). These results lead to the following conclusions: the antimicrobial peptide beta-defensin can be detected within the equine endometrium, the almost complete lack of beta-defensin immunostaining of unaltered glands could predispose to bacterial colonization of glandular lumina, the frequent beta-defensin immunoreaction of endometrotic glands indicates their functional alteration also in regard to the synthesis of beta-defensin, the variations in regard to the beta-defensin immunostaining between individual mares suggest a complex regulation of the beta-defensin expression, possibly under the influence of genetic factors, the beta-defensin immunostaining of cultured epithelial cells is similar to the in situ situation and therefor...

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Summary Only single cells in the carrier fish species Carassius carassius (Linnaeus, 1758) for koi herpesvirus (KHV) are infected in contrast to large numbers in the susceptible species common carp Cyprinus carpio (Linnaeus 1758). Several species of the family Cyprinidae have been described as virus carrier species, showing no clinical signs of a KHV disease but able to transmit the virus to other susceptible fish. In this study, 72 common carp Cyprinus carpio (Linnaeus, 1758), 36 tench Tinca tinca (Linnaeus, 1758), 36 crucian carp Carassius carassius (Linnaeus, 1758) and 36 common roach Rutilus rutilus (Linnaeus, 1758) were experimentally infected with KHV (isolate “Israel”) by immersion and kept at 20°C. The fish were euthanized at 12 timepoints over a period of 90 days and virus DNA was quantified in tissues by a real‐time TaqMan PCR. Whereas KHV‐DNA was found in Cyprinus carpio for up to 90 days, the virus DNA was detectable only in single individuals of Rutilus rutilus, Tinca tinca and Carassius carassius for up to 25 days after experimental virus exposure. Tissue samples of Cyprinus carpio and Carassius carassius were screened by in‐situ hybridization. Positive signals were found in various organs of the common carp tested crucian carp. In the latter species a much smaller number of virus‐positive stained cells was detected compared to the infected carp.