Epidemiology of Bovine Hemorrhagic Bowel Syndrome in Belgium and The Netherlands

Hemorrhagic bowel syndrome (HBS) is a poorly understood, sporadic and often fatal disease in cattle. Although, HBS is considered an important disease in dairy cattle, epidemiological data is largely lacking. This study describes the epidemiology of HBS in Belgium and the Netherlands, based on necropsy records from 2009 to 2022, and reports characteristics from 27 cows and 35 dairy operations with HBS, gathered through a survey. The annual incidence of HBS has a significantly increasing trend both at cow and herd level, with incidence above 3.2% in necropsied mature dairy cattle in the most recent years. Estimated herd-level incidence in the Netherlands was double the estimated incidence in Belgium, which might be explained by higher herd size in the Netherlands. Occurrence of HBS was most prevalent in fall, being 40.1% higher than the average of the other seasons. In 35 Flemish (Belgian) surveyed dairy herds with HBS, manifestation of HBS was mostly as solitary cases, and if multiple cases occurred, the time interval was highly variable. In addition, the majority of cows with HBS (61.1%; 16/26) were in more than 100 days lactation. In conclusion, HBS is an important and possibly emerging disease in dairy cattle in Belgium and the Netherlands.

Biodistribution Studies of Epithelial Cell Adhesion Molecule (EpCAM)-Directed Monoclonal Antibodies in the EpCAM-Transgenic Mouse Tumor Model

The human pancarcinoma-associated epithelial cell adhesion molecule (EpCAM) (EGP-2, CO17-1A) is a well-known target for carcinoma-directed immunotherapy. Mouse-derived mAbs directed to EpCAM have been used to treat colon carcinoma patients showing well-tolerable toxic side effects but limited antitumor effects. Humanized or fully human anti-EpCAM mAbs may induce stronger antitumor activity, but proved to produce severe pancreatitis upon use in patients. To evaluate treatment-associated effects before a clinical trial, we have generated a transgenic mouse tumor model that expresses human EpCAM similar to carcinoma patients. In this study, we use this model to study the in vivo behavior of two humanized and one mouse-derived anti-EpCAM mAb, i.e., MOC31-hFc, UBS54, and MOC31. The pharmacokinetics and tissue distribution of the fully human mAb UBS54 and the mouse-derived MOC31 were largely the same after injection in tumor-bearing transgenic mice, whereas the molecularly engineered, humanized MOC31-hFc behaved differently. Injection of UBS54 and MOC31 resulted in significant, dose-dependent uptake of mAb in EpCAM-expressing normal and tumor tissues, accompanied by a drop in serum level, whereas injection of MOC31-hFc resulted in uptake in tumor tissue, limited uptake by normal tissues, and slow blood clearance. It is concluded that the EpCAM-transgenic mouse model provides valuable insights into the potential behavior of humanized anti-EpCAM mAbs in patients. mAbs sharing the same epitope and isotype but constructed differently were shown to behave differently in the model, indicating that the design of mAbs is important for eventual success in in vivo application.

Macrophages direct tumour histology and clinical outcome in a colon cancer model

Macrophages generally constitute a major component of the tumour stroma. Although conventionally considered to be cytotoxic effector cells, macrophages have recently been described as promoters of tumour progression. The present study shows that selective depletion of peritoneal or liver macrophages prior to CC531 tumour cell inoculation resulted in highly differentiated tumours in rats. In contrast, tumours from control rats, in which macrophages are abundantly present, showed a desmoplastic stromal reaction with hallmark features of malignancy, such as neovascularization and matrix remodelling, indicating that the presence of macrophages is associated with malignant histopathological differentiation. Remarkably, macrophage-depleted rats, bearing highly differentiated tumours, had a worse prognosis, as they displayed a higher tumour load and poorer survival. Thus, while macrophages direct tumours towards malignant tumour histology, their role in anti-tumour defence is important. The selective inhibition of macrophage functions involved in malignant progression without interfering with cytotoxic ability may therefore identify important new targets for cancer therapy.

Growth hormone gene expression in canine normal growth plates and spontaneous osteosarcoma

The indirect growth-promoting action of pituitary-derived growth hormone (GH) on skeletal growth is thought to be mediated by systemically released insulin-like growth factor-I (IGF-I) and by locally produced IGF-I. The aim of the present study was to document whether GH is expressed locally in canine bone and spontaneous osteosarcoma. Using RT-PCR the expression of GH mRNA was demonstrated in the metaphyseal, but not in the majority of epiphyseal ends of the canine growth plate. GH mRNA was also present in 25% of the canine osteosarcoma specimens. The expression of GH mRNA in predominantly active osteoid forming areas was associated with the presence of immunoreactive GH in osteoblasts, as shown by immunohistochemistry. It is concluded that locally produced GH is involved in osteoid formation and may play a role in the growth of neoplastic bone lesions in the dog.

Morphogenic and tumorigenic potentials of the mammary growth hormone/growth hormone receptor system

Due to the characteristics of the luteal phase of the ovarian cycle in the dog, which spans a prolonged time period, this species is a suitable model to study the role of progestins in both normal morphogenic and abnormal tumorigenic processes in the mammary gland. It has been convincingly shown that progestins, including endogenous progesterone, induce the synthesis of growth hormone (GH) in the normal and the tumorous canine mammary gland. The growth hormone receptor (GHR) is also expressed in normal and tumorous canine mammary tissues and in this concise overview we highlight recent advances in our understanding of the significance of the GH/GHR system for mammary gland (patho)biology. In an attempt to unravel the cellular and molecular mechanisms associated with the GH/GHR system, we were able to show that both GH and GHR are differentially expressed in normal canine mammary tissues. Maximum expression of both GH and GHR occurs during the proliferation phase of the tissue, which links the progestin-induced mammary GH synthesis to the progestin-associated proliferation of epithelial cells in the mammary gland. Expression of the GH/GHR system is also present in most canine mammary tumors, albeit that GHR expression may be downregulated in undifferentiated mammary carcinomas. Upon GH stimulation of the GHR-positive CMT-U335 canine mammary tumor cell line, the transcription factors STAT5A and STAT5B become phosphorylated on their tyrosine residues, which is likely to reflect the significance of mammary GH in vivo. Molecular analysis of the canine mammary GHR transcripts by RT-PCR provided evidence for normal and alternative processing of the GHR primary transcript encoding the full-length plasma membrane GHR and at least four putative GH binding proteins (GHBPs), respectively. The translation products from the alternatively spliced GHR transcripts indicate an intact N-terminal ligand binding domain and an unique C-terminal portion, lacking the transmembrane domain and cytoplasmic tail. Thus, these proteins are considered to be able to bind GH, but have lost their signaling potential. The exact biological role of these GHBPs remains to be established, but GHBPs may have a transport function in the endocrine route, regulate the level of biologically available GH locally, or dominant-negatively influence the full-length plasma membrane GHR. In dog mammary cancer specimens strongly reduced levels of alternatively spliced GHR transcripts were found compared to the non-malignant mammary tissue. Notably, expression of both GH and GHR in mammary cancer cells is not restricted to dogs. Recent experiments generated evidence for GH and GHR expression in human breast cancer cells, and also in human prostate cancer cells, which represents another highly prevalent hormone-sensitive human malignancy. In agreement with our findings in the dog, the expression of the hGH-N gene in human mammary cancer cells seemed to correlate positively with their progesterone receptor status, which warrants, in our opinion, a reconsideration of the role of progestins in breast cancer of women. In human prostate cancer cells four different hGH-N transcripts were detected, which encode classical 22 kDa GH and GH-related proteins. Consistent with the findings on the canine GHR, different GHR transcripts in human mammary cancer cells and prostate cancer cells were detected encoding the full-length plasma membrane GHR and putative GHBPs.